design of a desalination by reverse osmosis laboratory...
TRANSCRIPT
University of Strathclyde
Department of Mechanical Engineering
5th Year MEng Group Project
Design of a Desalination by Reverse Osmosis
Laboratory Test Facility
Stephen Cooper – 200938919
Laura Nicholls – 200942455
Andrew Crowe – 200900479
Michael Osman – 200905982
Supervisor – Dr William Nicholls
2014
URL: www.ro-test-rig.weebly.com
i
Abstract
The aim of this project was to design, source and cost a test facility that can be used to
investigate the properties of membrane materials used for desalination of water by reverse
osmosis. A review of current and potential future membrane technologies was carried out
to provide a background to the industry and to understand where future development may
be required. Components which make up the test facility were chosen based on a
compromise between cost and practicality. Most of the components required were
sourced directly from suppliers, with the exception of the membrane holder; this
component was specially designed to meet the design criteria.
The design for the facility may be created in future projects by the Strathclyde Engineering
Department and used for experimental study. A project build schedule was devised that
would be used by the future interested party and provides an overview of the build
process. A section on how to conduct a reverse osmosis test is also included in order to give
instructions of how the facility should be used and instructions on how to achieve specific
pressures or flow rates.
ii
Acknowledgements
The group would like to thank Dr William Nicholls for his help and guidance throughout the
length of the project. He gave key insight into the deliverables of the task and made the
project interesting and enjoyable. He was readily available whenever any help was
required and enthusiastic with any challenge we brought to him.
Dr Barbara Keating has previously worked in the desalination industry and was very helpful
at the initial stages of the project by providing insight into the developments required by
the industry and also helped to provide information on some of the current companies
working in the industry.
Chris Cameron was very helpful with various parts of the project, helping us with
discussions about technician times and costs and providing information about what the
technicians could achieve.
Jim Doherty was once again incredibly helpful with tips of where would be best to source
parts of the test facility.
John Redgate helped with discussions about the test facility-heating element and ensured
us that we were heading in the right direction with our decision.
We would also like to thank Stuart Willgoss and Steven Greenwell (Michael Smith
Engineers), Sam Bass (VWR International) and Kenny Lamont (Righton ltd.) for helping with
the sourcing of their respective products. All responded quickly to any enquiries, which
was very helpful throughout the course of the project.
iii
Contents
Nomenclature ......................................................................................................................... vi
1. Introduction ..................................................................................................................... 1
1.1 Problem Definition ................................................................................................... 1
1.2 Statement of Purpose .............................................................................................. 1
1.3 Success Criteria ........................................................................................................ 2
1.3.1 Objective 1 ....................................................................................................... 2
1.3.2 Objective 2 ....................................................................................................... 2
1.3.3 Objective 3 ....................................................................................................... 2
1.3.4 Objective 4 ....................................................................................................... 2
2. Project Planning and Management ................................................................................. 3
2.1 Group structure........................................................................................................ 3
2.2 Role Assignment....................................................................................................... 3
2.2.1 Client ................................................................................................................ 4
2.2.2 Project Manager ............................................................................................... 4
2.3 Planned Work Structure........................................................................................... 4
2.4 Communications ...................................................................................................... 4
2.5 Risk Analysis ............................................................................................................. 5
2.6 Budget ...................................................................................................................... 6
3. Current Market ................................................................................................................ 7
3.1 Companies................................................................................................................ 7
3.1.1 DOW/Filmtec ................................................................................................... 7
3.1.2 Nano H2O.......................................................................................................... 7
3.1.3 Toray ................................................................................................................ 7
3.1.4 Hydranautics .................................................................................................... 7
3.1.5 Toyobo ............................................................................................................. 8
3.2 Test Rig Designs ....................................................................................................... 8
4. A review of RO Membrane Materials for Desalination .................................................... 9
4.1 Membrane Information ........................................................................................... 9
4.2 Future Challenges in the Desalination Industry ..................................................... 10
4.3 Additional Information ........................................................................................... 10
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5. Future Reverse Osmosis Membrane Technologies ....................................................... 11
5.1 Carbon-nanotube membranes............................................................................... 12
5.2 Zwitterion Functionalized Carbon Nanotube/Polyamide Nano-composite
Membranes ........................................................................................................................ 12
5.3 Graphyne Nanoweb Membranes ........................................................................... 12
5.4 Biomimetic RO membranes ................................................................................... 13
5.5 Future Reverse Osmosis Membranes and the Industry ........................................ 13
5.6 Future Reverse Osmosis Membranes and Test Rig Design .................................... 14
6. Test Rig design ............................................................................................................... 14
6.1 System Schematic .................................................................................................. 14
6.2 Water Tank Selection ............................................................................................. 15
6.3 Heating element Selection ..................................................................................... 16
6.4 Pump Selection ...................................................................................................... 16
6.5 Pipe Selection ......................................................................................................... 17
6.6 Pressure Gauge selection ....................................................................................... 18
6.7 Collection Tank Selection ....................................................................................... 18
6.8 Membrane Holder Design ...................................................................................... 19
6.8.1 Design Concepts ............................................................................................. 20
6.8.2 Performance Matrix ....................................................................................... 21
6.8.3 Final Selection ................................................................................................ 21
6.8.4 Safety Analysis ............................................................................................... 22
6.9 Test Rig Support ..................................................................................................... 23
6.10 Test Area ................................................................................................................ 24
7. Costing ........................................................................................................................... 24
8. Construction Schedule ................................................................................................... 24
8.1 Conducting a Test................................................................................................... 26
9. Reflective Analysis on Project Planning and Team Dynamics ........................................ 28
9.1 Delivering Objectives ............................................................................................. 28
9.2 Meeting Deadlines ................................................................................................. 28
9.3 Test Rig Design Criteria .......................................................................................... 29
9.4 Team Dynamics ...................................................................................................... 29
10. Conclusions ................................................................................................................ 29
v
Bibliography ........................................................................................................................... 30
Appendix
A. Contract............................................................................................................................ 1
B. Product Design Specification (PDS) .................................................................................. 4
C. Example of Minutes ......................................................................................................... 5
D. Original Gantt Chart ......................................................................................................... 6
E. Amended Gantt Chart ...................................................................................................... 7
F. Selection of Water Tank ................................................................................................... 8
G. Selection of Heating Element ......................................................................................... 11
H. Selection of Pump .......................................................................................................... 14
I. Selection of Piping System ............................................................................................. 25
J. Selection of Pressure Gauge .......................................................................................... 34
K. Selection of Collection Tank ........................................................................................... 36
L. Membrane Holder Design .............................................................................................. 38
M. Drawings and Visuals ................................................................................................. 56
N. Costing ........................................................................................................................... 60
O. Construction Schedule ................................................................................................... 65
vi
Nomenclature
EDI Electrode Ionization
PDS Product Design Specification
PRN When Required
PM Pugh Matrix
RO Reverse Osmosis
SF Safety Factor
SWRO Salt Water Reverse Osmosis
NPT Threading (or National Pipe Thread)
UF Ultrafiltration
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1. Introduction
1.1 Problem Definition
The World Health Organisation projects that by the year 2050 around 4 billion people
across 48 countries will be without safe drinking water. The majority of water on Earth is
seawater and is considered unsafe for consumption due to the salt content. There are
currently many desalination plants worldwide producing safe drinking water but as the
population increases, especially in developing countries, the need for more plants is
growing. Many of these plants use reverse osmosis (RO) methods to remove the salt
content. Reverse osmosis is achieved by passing salt water through a membrane at a
pressure of around 55 Bar so that both the brine product and the fresh water can be
collected separately. Unfortunately RO plants are not highly efficient and a large amount
of power is required to produce clean drinking water, currently research is being conducted
to develop new membrane materials that can increase efficiencies, therefore reducing
costs and making the technology more available for those who require it the most.
The main aim of this project was to design a membrane test facility to investigate the
effectiveness of current RO membrane materials, which is also adaptable to test future
membrane sheet designs. An accompanying project plan to implement the building of the
final rig design was also produced to allow the work to be continued at a later date. A
review of current membranes was conducted and research into future designs was also
pursued to provide a literature background.
This report discusses some of the key project management challenges faced during the
project as well as an overview of what has been achieved.
1.2 Statement of Purpose
A project schedule was created for the development of an experimental test rig that would
be used to test various desalination membrane materials as well as researching deeper into
the current and future reverse osmosis technologies available. The key objectives to be
covered in the project are as follows:
1. Design and cost an experimental test rig that enables the assessment of different
reverse osmosis membranes materials.
2. Create a project schedule that includes a test facility construction timeline.
3. Review of current reverse osmosis membranes used in industry.
4. Review of new nano-scale membrane technology including carbon nanotube
membranes.
At the initial phase of the project a contract was drafted and agreed upon by all team
members and the client, which specifies these objectives (Appendix A).
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1.3 Success Criteria
In order to achieve the statement of purpose it was necessary to create a list of
deliverables, each with a clear set of criteria that must be met. For each key objective a list
of criteria was generated:
1.3.1 Objective 1
1. For the laboratory rig design a full product design specification (PDS) must be
developed, this can be found in Appendix B.
2. A costing list is required to be created alongside the design, with an estimated
maximum budget of £30,000.
3. Possible alternatives to the final design should also be investigated for the possibility
of a change in the current criteria (multiple sample testing).
1.3.2 Objective 2
1. The schedule should include instructions on ordering the correct parts for the final test
rig design and the manufacturers from where they were sourced. Delivery times should
be included in the project schedule to properly manage time.
2. The schedule shall include CAD models for any components that require manufacturing
within the department.
3. The schedule shall include an appropriate review time of the design to implement any
alterations to the final design if required (the project may be subject to change and the
design may need to perform different criteria than what was previously agreed upon).
1.3.3 Objective 3
1. Give a basic overview of research papers and highlight key points of current RO
membrane materials currently being used in the desalination industry.
2. Investigate material properties of membranes paying particular attention to
permeability, salt rejection, and fouling probability.
3. Gain insight into membrane cartridge structure.
4. Specify future challenges in the desalination industry.
1.3.4 Objective 4
1. Investigate the needs and reasoning behind the requirements for novel designs of RO
membrane technology.
2. Investigate various designs and gain an understanding of how new technologies can
reduce power requirements and the cost of RO desalination.
3. To determine whether future membrane technologies can be incorporated into the
test rig design.
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2. Project Planning and Management
2.1 Group structure
In order to make effective use of time it was essential to assign roles to each individual
member.
Figure 1: Group Framework
2.2 Role Assignment
Each key objective was assigned a leader depending on the members’ interests and results
from Belbin tests (results displayed in Table 1). The design of the laboratory test facility was
the main focus of this project and therefore required more time and more attention than
the other objectives. This was reflected in the group structuring since this required more
people to focus on certain aspects of the design.
Member Primary Role Secondary Role
Stephen Company Worker Team Worker
Andrew Chairman Shaper
Laura Completer Finisher Monitor Evaluator
Michael Team Worker Company Worker
Table 1: Belbin Test Results
It was the roll of each key objective leader to ensure that work being carried out in their
section was documented properly and progress was communicated to other members
effectively.
Client - Dr Nicholls
Project Manager - Rotating
Arrangement
Research - Current
Technology - Stephen
Research - Future Technology -
Michael Rig Design - Laura
Device Design - Andrew
Pump Selection - Michael
Materials Selection - Laura
Sourcing & Costing - Michael
Build Schedule - Andrew
Web Designer - Stephen
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2.2.1 Client
The client for this body of work is the project supervisor Dr William Nicholls. The founding
of this project was due to a need to design a test rig facility for future research into reverse
osmosis membranes. The client’s needs were vital in the development of the aims and
criteria of the project. Future clients could also include any personnel that will take on the
building of the rig as well as the future potential to carry out work in testing membranes
from other companies. Due to the possibility that the project could be continued or altered
to test for other properties (such as membrane fouling tests) it was essential that the
overall design can disassemble to allow for alterations.
2.2.2 Project Manager
Initially it was agreed that the project manager role would not go to one individual but
instead a rotating arrangement would be adopted. Since this is a learning experience each
member wanted a chance to develop his or her own skills for future projects.
The project manager’s roll was to assign responsibility for tasks to members and ensure
that each member fully understood their piece of work. At formal meetings it was also the
project manager’s job to ensure minutes were recorded and distributed amongst all
members. An example is provided in Appendix C. Projected deadlines were then agreed
upon and it was then the manager’s roll to ensure that work was going ahead as planned
and all members were working to both short-term deadlines and that the major deadlines
were being met in accordance to the Gantt chart (Appendix D).
2.3 Planned Work Structure
At the initial stages of the project a Gantt chart was developed covering all the main tasks
and a projection of the length of time required to complete each section. This was then
used as a guide to ensure the project was running on course. The main project deadlines
were included in this document which were agreed upon with the client to ensure an
acceptable timescale was adopted.
The initial Gantt chart was adapted after the first semester of work was completed in
accordance with the new planned work schedule, re-allocating team members to sections
that required more attention and updating the areas of work which were completed ahead
of schedule. The new chart can be found in Appendix E.
2.4 Communications
For the project to run smoothly it was essential to develop a good communication base
between group members and the client. Multiple communication channels were utilized
and the details for which can be found Table 2. For both formal and client meetings it was
the project manager’s responsibility to record minutes and to allocate tasks according to
any new developments.
5
Method Purpose Frequency
Formal Meetings An agreed date and time was selected and all members attend to present their work. Also used to query any issues or concerns.
PRN
Informal Meetings These were used to discuss any new developments or to clear up any issues as soon as they arose.
PRN
Client Meetings Used to update the client with project progress and to obtain support where necessary.
Weekly
Project Timeline Documents
Used to assess the progress of the project. Fortnightly
Social Media Messaging
A group conversation was setup to allow for all members being involved in group related conversation. Used for meeting requests or new updates.
Always Available
Email Used mainly for contact with client and component suppliers.
Always Available
Dropbox Used to allow communal access to all project documents and any new work.
Always Available
Table 2: Communication Methods
2.5 Risk Analysis
During the initial phases of the project, the various risks were considered and counter
measurements devised to be set in place in the event that an issue arose. Table 3 describes
the risk and a rating is given to that risk which was found by:
Where both consequence and probability of the error were rated on a scale of 1 to 3. The
risk rating has a value between 1 and 9, with 9 being the most damaging level of risk to the
project.
Outlined Risk Rating Counter Measures Responsibility
New field of work 2 -Carry out an appropriate level of background research
Project Manager
Incorrect Assumptions
3 -Ensure regular meetings are held with members before using an assumption
-Hold regular meetings with supervisor and
Project Manager
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discuss any assumptions made
Poorly defined product design specification
6 -Ensure a full PDS is generated before design work is carried out
-PDS is subject to change throughout the course of a design but once a final design has been agreed upon no further alterations can be made
-Deliver a final copy of the PDS to the client for approval
Laura
Difficulty in sourcing components
9 -Consult with supervisor for possible suppliers
-Use the technician base and consult with technical staff for other manufacturers previously used within the department
-If the part cannot be sourced consider the viability of building the component within the department (consult technical staff)
Michael
Project falling behind schedule
4 -Use the Gantt chart regularly to ensure project is running on track
-If the project is found to fall behind then hold a meeting to discuss the cause and project means to remedy the situation
Project Manager
Member illness 3 -Depending on the severity of the illness, allowances will be made to reduce the members workload
-If it is a long term condition then a new scope of work may be required due to the loss of project work hours
Project Manager
Table 3: Risk Analysis
2.6 Budget
The project goals do not include the physical building of the completed design, therefore
no real budget was required. However, budgeting was part of the design specification since
there will be plans made to make the rig in the future and part of the project plan was to
cost the different parts and produce an estimated project cost along with a building
schedule. Currently the client has discussed a sum of £30,000 to cover the costs of the build
so this was the maximum amount that was allocated to the design cost. However, it was
an important aim to reduce the price of the rig as far as possible without affecting the
quality of the product.
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3. Current Market
3.1 Companies
The membrane market has been established for over 40 years now with five companies
that hold the largest market share. These are: DOW; Nano H2O; Toray, Hydranautics and
Toyobo. They are constantly trying to develop new membrane technologies for a massive
range of uses, with new products being aimed at giving anything from the highest saltwater
rejection possible to the lowest energy consumption.
3.1.1 DOW/Filmtec
DOW water and Process Solutions are a subsidiary of the DOW Chemical Company
Operates in the following fields: fine partial filters, ultrafiltration (UF) and reverse
osmosis membranes, ion exchange resin technologies and electrode ionization (EDI)
products
Use Filmtec RO elements as their core technology for treatment of brackish and salt
water
Wide range of commercial membranes available to cope with different properties of
water and different RO facilities
Typical uses are seawater desalination, municipal drinking water, industrial
desalination, small desalination systems and marine (yacht) applications [1]
3.1.2 Nano H2O
Small scale company founded out of research from UCLA after technological
breakthrough of thin film nano-composite membranes (TFN)
Operating in 34 countries all over the world NanoH2O’s “Quantum Flux” membranes
produce 66 million gallons of useable water per day
Membrane technology has the highest salt water rejection out of any market products
Recently secured large scale contracts multiple regions of the world [2]
3.1.3 Toray
Japanese based company headquartered in Tokyo
Environmental engineering department specialises in water treatment products from
RO membrane to industrial scale salt water desalination systems
ROMEMBRA technology uses cross-linked polyamide membrane technologies to treat
water
Has a wide range of products available to treat sea water through to brackish water [3]
3.1.4 Hydranautics
Founded in 1975 and based in California
Used in applications such as potable water, boiler feed water, industrial process water,
wastewater treatment, surface water treatment, seawater desalination, electronic
rinse water, agricultural irrigation and pharmaceuticals
8
Large database of internally published papers in the membrane field on company
website [4]
3.1.5 Toyobo
Japanese company - Top makers of fibres and textiles in which one of their products is
RO membrane elements for water treatment.
Have series of membranes for both brackish and seawater treatment.
Have a world brand Toyobo RO module "HOLLOSEP".
Toyobo’s "HOLLOSEP" RO membrane elements were chosen for use in the world's
largest seawater Desalination plants in Saudi Arabia.
Toyobo are currently enhancing its competitive advantages in the seawater
Desalination business in the Middle East.
3.2 Test Rig Designs
As there is a huge amount of development into membrane technologies, there are a wide
range of experimental test rigs around various establishments, both Industrial and
academic. Some of these rig designs are essentially small scale versions of current reverse
osmosis facilities and others focus on flat sheet testing.
A post-doctoral thesis by Murray Thompson [5] aimed to design a small scale reverse
osmosis rig that was to be powered by photovoltaic energy. Figure 2 A) shows the process
instrument design of the final rig.
Figure 2: A) PV RO Desalination Rig Schematic B) Flat Sheet Membrane Cells
The basic components used are standard for any reverse osmosis test rig. An inlet, high
pressure pump, RO membranes, product tank and waste discharge. It should be noted that
this design is not unique; a similar setup was designed by Bilton et al. in a separate
unaffiliated paper that explored a photo voltaic test rig [6].
Whilst most companies have the ability to build on their current technologies and test
membranes in cartridge form; there are examples that in the early stages of research,
membrane materials are tested in flat sheets with low volume flow rates. An investigation
into long-term SWRO testing of nanocomposite membranes was carried out by NanoH2O
9
[7]. The investigation used two forms of facility set up to test the membrane. The first was
a basic cell set up that allowed for flat sheet testing.
Three cells were linked together and then set in parallel. This allowed for the testing of the
membrane’s material as an early stage of membrane design. By using flat sheets the basic
material properties and applicability of the material could be evaluated without having to
manufacture industrial scale membrane cartridges. Additionally, due to the parallel
configuration, multiple types of membranes could be evaluated. (An example of the setup
is shown in Figure 2 B).
The second stage was a similar set up, however made use of membrane cartridges instead
of cells. This allowed for a more in-depth investigation into the nano-composite
membranes to evaluate their performance as part of a functioning system over the
duration of a year.
4. A review of RO Membrane Materials for Desalination
A literature review was carried out as a basis for meeting Objective 3 (Section 1.3.3). It was
required to carry out a review of current RO membranes used in Industry; this section of
the report gives a basis of the overview and highlights key points of the research paper.
RO is currently the most important desalination technology, especially for desalting
brackish and sea water, and is experiencing significant growth. After 1980s the
performance of RO membranes has been optimised via control of membrane formation
reactions, and the use of poly-condensation catalysts and additives. Polymeric membranes
have dominated the RO desalination Industry as they offer low cost fabrication, ease of
handling and improved performance in selectivity and permeability. In order for new RO
membrane materials to be developed performance targets must be defined, the standard
criteria for judging membrane material and performance should be:
Permeability (Preferably Higher)
Ion & Contamination Rejection (Preferably Higher)
Operational Robustness
Resistance to Biological & Chemical Attack.
The reasons for these criteria are shown in the Membrane Information section (4.1) which
follows in this report [8].
4.1 Membrane Information
RO Market dominated by thin film composite polyamide membranes consisting of
three layers:
1) Polyester web acting as structural support (120-150µm)
2) Micro-porous Interlayer (40µm)
3) Ultrathin barrier layer on upper surface (0.2µm).
Membrane pore size is normally less than 0.6nm to achieve salt rejection consistently
higher than 99%.
10
Spiral Wound Membrane Module configuration is the most extensively used design in
RO Desalination.
High salt rejection reduces the number of RO passes to achieve appropriate product
water quality.
Higher Permeability reduces the need for large membrane area, reduces replacement
costs, reduces the plant footprint and also reduces the need for cleaning chemicals.
Reduction in Fouling (via development of chlorine-tolerant membranes) will reduce the
cost of membrane replacement, backwashing chemicals and energy to overcome
additional osmotic pressure.
Typical Membrane Cartridge Parts:
o Brine Seal/Perforated Central Tube/Feed Channel
Spacer/Membrane/Permeate Collection Material/Outer Wrap.
4.2 Future Challenges in the Desalination Industry
Feed Water Characterization
Process Development
Materials Development
Renewable Energy Source
Stringent Water Standard
Brine Management
4.3 Additional Information
There are currently two main membrane “types”:
Polyamide Spiral Wound Membranes
o Dominate market sales with 91% share
o Higher salt rejection and net pressure driving force
o Spiral wound membrane module configuration offers high specific membrane
surface area, easy scale up operation, interchangeability, low replacement
costs and most importantly it is the least expensive configuration to produce
from flat sheet thin film composite membrane.
Asymmetric cellulose acetate hollow fibre Membranes
o Superior Chlorine Resistance (Allows prevention of the growth of
microorganisms and algae via chlorine injection)
o Appears to have a substantial Permeate Flux (m3day-1) when compared to data
of polyamide spiral wound membranes.
An extract from the paper shown in Table 3 highlights some of the best membrane
modules in application. The important comparison in the table is particularly the ‘Permeate
Flux’ and ‘Salt Rejection (%)’.
11
The purpose of this review is to highlight the fact that Membrane material enhancement
makes RO more economical by increasing performance and efficiency. Key limitations of
commercial RO membranes are the degradation by chlorine, which requires de-chlorination
of the RO feed and re-chlorination of the RO permeate. Overall advances in membrane
permselectivity are relatively slow and membrane fouling remains a severe problem. [8]
5. Future Reverse Osmosis Membrane Technologies
As mentioned previously, conventional RO membranes are commonly made with a
polymer-based material and improvements in the technology have been limited since the
late 1990’s [8], especially in permeability. Naturally water will try to go through an osmosis
process, this is the opposite of what is required for RO desalination, therefore a minimum
pressure of 26 Bar is required to overcome the osmotic pressure and push the salt water
through the membrane to induce RO. The low permeability values for polymeric materials
require a high pressure to get the water flux required. A high energy input is required to
provide these pressures and in developing countries this energy costs too much to make
the process justifiable. A reduction in cost is needed in order to deploy this technology into
some of the most deprived areas and the most effective way to do this is to reduce the
amount of energy required in the process. There is currently a number of new membrane
designs that are being researched that will reduce the amount of energy required, some of
the more promising designs are discussed later. The design for the test rig was required to
take these new technologies into account for future testing.
There are a number of criteria that must be fulfilled for a material to be considered for use
as a RO membrane. The main factor is the effect on the fluid flow which is altered by the
permeability of a material. A higher material permeability reduces the amount of energy
required to get the desired flow rate and therefore reduces the cost to produce the
desalinated water. Selectivity is the process of allowing molecules to pass through the
material, for most membranes the molecule rejection is directed by reducing or increasing
the space for specific molecules to pass through. Water molecules are smaller than sodium
chloride and therefore water will pass through the pores and the salt will be rejected. In
the majority of cases this selectivity process requires optimisation to determine the size of
the membrane pores to ensure that the salt is rejected whilst also keeping the size large
enough to allow water to pass through easily, if the pore size is too small the pressure
Figure 3: Membrane Brand Comparison
12
required will increase. Research has been conducted concerning cases where Zwitterion
ions are introduced to increase the selectivity of selected membranes, this will be discussed
later. Membranes with better selectivity should show better results for desalination.
In the fabrication of membrane devices, the clamping process usually introduces
mechanical loading laterally on the membrane and causes its mechanical failure and
integrity loss. Even without failure, the resulting tensile deformations (strain) could
potentially affect its water purification performance [9]. For this reason future designs
must have good mechanical properties to compete with current designs.
5.1 Carbon-nanotube membranes
Permeability is highly increased compared to conventional RO membranes [8].
Reduction in energy required to produce required flow rate. For some systems the
energy required could be reduced by 30-50% [8].
Results from different experiments have shown higher flow velocity than expected
from the Haagen–Poiseuille equation which governs macro scale hydrodynamics [8]
Reasons for these results are not currently known and more research must be carried
out to develop the technology further.
If this technology is developed it may provide a new method of RO desalination that
will reduce cost and therefore the overall cost of fresh water production.
5.2 Zwitterion Functionalized Carbon Nanotube/Polyamide Nano-
composite Membranes
Are essentially the same as carbon nanotube membranes above however include
Zwitterion ion bunches.
A Zwitterion is a neutral molecule with a positive and negative electrical charge,
although many charges may be present.
These Zwitterion ions block the NaCl ions and not the water therefore enhancing the
selectivity of carbon nanotube membranes [10].
Research has been carried out into this technology that shows promising results for
permeability and mechanical stability.
5.3 Graphyne Nanoweb Membranes
In recent years research has been carried out into
the use of 2D nanoweb-like graphyne membranes
(Figure 4) that provide promising results.
Graphyne can be thought of as linking benzene
rings by strings made of N-acetylenic linkages, these
linkages can vary in length (N = 1, 2, 3, 4, 5, 6, …)
and therefore make the graphyne group very
versatile [11].
Varying the length of these linkages increases the Figure 4: Diagram of Graphyne Structure (5)
13
space for molecules to pass through therefore these nanowebs are good for different
applications of water purification, including ultrafiltration.
For values of N<3 the geometric area is too small to allow water to pass through.
Membranes with larger pore openings (N = 3-6) correspond with pore diameters of 2.8,
5.4, 7.0 and 8.6 ̇, these values show good filtration properties as they reject salt ions
[11].
Larger pore openings (N>6) allow for too much space and therefore the salt rejection
rate becomes very poor.
Computational experiments have shown that graphyne membranes are superior to
polymer-based membranes in terms of mechanical stability.
Water permeability is found to be higher than standard polymer-based membranes.
5.4 Biomimetic RO membranes
The incorporation of aquaporins in membranes is being investigated due to excellent
water transport properties of biological membranes.
Membranes with Aquaporin Z proteins have been reported to show superior water
transport efficiency relative to conventional reverse osmosis membranes [12] [8].
Initial permeability tests have been carried out testing polymer vesicles by stopped
flow light scattering experiments. The results showed at least an order of magnitude
improvement in permeability compared to commercial membranes [12] [8].
So far a salt separation test has not been reported, but extremely high salt rejection is
expected because the aquaporin’s functional biological performance is to only allow
the passage of water molecules [8].
There appears to be a number of problems with identification of support materials,
understanding the resistance to membrane fouling, and even identification of an
appropriate range of operation conditions. Before these designs can be developed
these unknowns must be found.
Aquaporin is a Danish company that is developing these membranes for practical use.
The company has recently been awarded a patent on the method of fabricating
membranes with aquaporins [8]. This patent unfortunately does not disclose any
numerical data involving flux or salt rejection properties, but it does report information
about concentration polarization and severe fouling.
5.5 Future Reverse Osmosis Membranes and the Industry
As can be seen from the information above there are a number of new membrane designs
that could improve the water industry, however none of these are currently in use. The
reason for this is that problems arise when trying to scale up the product. Current
membranes are designed to include large surface areas by forming cartridges. At present
none of the future designs discussed are at the stage of full scale testing and many have
not been tested as single membrane sheets. More testing must be conducted to ensure
the materials work as predicted and that the membranes can be adapted into cartridges
without substantial deformation. Deformation of the materials is a major challenge facing
the industry as the membranes must be adapted into cartridge form without causing
14
tensile deformation that can potentially affect membrane performance. More research
must be performed to develop these technologies further to ensure that they operate to
full industrial standards and can be adapted into cartridge form.
5.6 Future Reverse Osmosis Membranes and Test Rig Design
The test facility that has been developed is to be used for future research therefore it must
be designed to facilitate these new membrane designs. All designs that are discussed are
assumed to be tested as individual flat sheets as is currently found in industry. The only
alteration between current and future membranes is the permeability and therefore the
pressure required may change and for this reason the pump that supplies the membrane
must have an adjustable pressure output. The minimum pressure allowed corresponds
with the osmotic pressure of typical seawater, which is 26 Bar, due to practical implications
it is more likely that the aim will be a minimum of 40 Bar. The maximum pressure should
be around 70 Bar, this allows for current membranes to be tested and will provide the
option of extra pressure if high pressure tests are required.
6. Test Rig design
The main objective of this project is to design and cost a test rig for the desalination of salt
water using RO membranes. The rig may be built by a future PhD student to evaluate the
effectiveness of new and future membrane designs that are approaching the market and
also membrane performance of current designs. There are various properties that a
student may want to investigate such as permeability, salt rejection and fouling probability
so the aim of the design is to allow for an adaptable rig that can be adjusted for whatever
the student requires. It is assumed that the student will want to be able to vary the flow
rate and the pressure through the membrane in order to assess the flux properties of the
membrane. It is also assumed that the student will wish to collect the water at the outlet
and test for the amount of salt left in the filtered solution. A full PDS for the test rig design
can be found in Appendix B.
The test rig has a number of components that must be correctly selected to ensure
accurate results are found when testing is conducted. Most components are purchased
from various sources with the exception of the membrane holder, which has been designed
for the required task and will be manufactured internally. This section will briefly discuss
the reasons behind part selection and design.
Information on product costing will be included in the Costing section of this report and is
briefly mentioned within this section. The section named Construction Schedule gives an
overview of what a PhD student should consider before continuing with the construction of
the rig. A brief overview of the testing process is also provided in the Conducting a Test
section.
6.1 System Schematic
The initial designs discussed are for a system that is testing one membrane at a time
however it is likely that in practice that more membranes will be tested in parallel. The
15
Figure 5: Test Rig Schematic
reason for this is that a reverse osmosis membrane cartridge that would be used in industry
has a much larger effective area than the test sample. In practice, testing more samples
will allow for a more realistic result to be found by averaging the results. This will increase
the cost of the rig but the design will not be greatly affected; if more samples are to be
tested, all that would be required is the inclusion of a flow splitting manifold and then
multiplying out the system after the split. This is discussed in more detail within the Pipe
Selection section in the appendices. Figure 5 shows a basic schematic of the system.
6.2 Water Tank Selection
The initial water tank will hold the prepared test solution and allow for flow into the
system. It is important that it is corrosion resistant and cost effective. It would also be
preferential to have a welded tap to reduce the chance of the test water leaking.
Product: 20L Carboy (Also available 10L, 25L and 50L) (See Appendix F)
Source: VWR International
Price: £112.00
Needle Valve
Pressure Gauge Adapter
Swivel Fit
Street Tee
Adapter
Swivel Fit
Water
Tank
Pump Holder
Collection
Tank
16
Reasons for Selection:
Good Chemical Resistance
Leak-proof Closure
Welded Tap
Temperature resistant from -100 to +80⁰C
University recommended source
In reality a smaller tank would be preferential,
however for safety reasons it is important that the
heating element does not breach the surface of the water or touch the sides of the vessel
therefore a 20L tank was selected.
6.3 Heating element Selection
The water in the test should be kept at a constant temperature of 25⁰C as this is the
temperature of water in industrial desalination situations. It is assumed that a temperature
rise of 5⁰C is required as the prepared water solution is likely to sit at room temperature
(20⁰C) after being initially heated.
Product: Titanium Aquarium Fish Tank Heater (300W)
Source: www.allpondsolutions.co.uk
Price: £29.99
Reasons for Selection:
Roughly 20 minutes to provide required
temperature. (See Appendix G)
Virtually unbreakable high quality pure titanium
Airtight, corrosion proof design.
External thermostat dial control
Suction cups for easy installation
Dimensions: 17mm × 270mm
There are safety issues that must be considered when inserting the heating element. The
element should not touch the side of the Water Tank; this issue can be removed by careful
insertion. The element should not breach the water surface which can be ensured by
regularly checking the water level.
6.4 Pump Selection
The pump is one of the most important parts of the test facility as it is important that both
the pressure and flow rates are variable (40-70 Bar and 0.05-1.5 L/min respectively). This is
not simple as the majority of pumps are designed to have set parameters and to not vary
unless a problem occurs therefore it was decided that a large amount of the budget could
be allocated to the pump if necessary.
Figure 6: Water Tank
Figure 7: Heating Element
17
A number of pumps were researched and assessed according to price and performance but
the majority of these did not meet the required specifications. Eventually the Wanner
Hydra-cell pump was found that provided the variable pressure and flow rate values
required. The Hydra-cell pump also has the advantage that components come in a variety
of materials; therefore the pump can be adapted to the task at hand (Information in
Appendix H). Wanner also provide inverter motors and pressure relief valves for the
Hydra-cell range of pumps which reduces the need to find an alternative product that fits.
Product: Hydra-cell seal-less diaphragm pump
Pressure Relief Valve
Inverter
Source: Michael Smith Engineers
Price: £12,840
Reasons for Selection:
Variable Pressure (40-70 Bar).
Variable Flow Rate (0.09-1.3L/min).
Positive displacement pump, no head pressure
required.
Virtually pulseless flow.
A range of materials available if selected material deemed unsuitable (See
Appendix H).
All required components provided from same source.
NPT threaded inlets and outlets for piping insertion.
6.5 Pipe Selection
The piping used in the system must be able to withstand a pressure of 70 Bar, be corrosive
resistant and allow for simple building and de-construction of the rig. From these
specifications it was decided that NPT threaded hose piping would be preferential.
Enerpac design and manufacture a wide range of products that are used in high-pressure
hydraulic situations. They produce various hoses and connections that have NPT screw
threaded fittings and therefore it will be simple to construct and disassemble the test
facility as required. All Enerpac products have been previously tested up to pressures of
700 Bar and are therefore well within the safety limits, this also reduces the need for
pressure testing on individual components that would be required if steel piping was used
instead.
As the piping can be used in a wide variety of applications it is necessary to purchase
suitable adapters to connect components together. This means that in some instances
more than one adapter is required to reduce or increase the size to insert it into a
component. This increases the price of the piping system, however, the advantages of this
type of system massively outweigh that of a welded steel piping system and with the initial
Figure 8: Positive Displacement Pump
18
£30,000 estimated budget discussed it was deemed acceptable to suggest that it would be
an effective expenditure.
Product: Variety of components required for piping system. (See appendix I for more
information on requirements)
Source: Powerflow Solutions
Price: £1414.41
Reasons for Selection:
Pressure tested up to 700 Bar
All required components provided from one source
Corrosion Resistant
NPT threaded for simple construction and de-construction
If a multiple test system is required it would be necessary to purchase a split flow manifold
and then multiply the system after this point. More information is found in the Appendix I.
6.6 Pressure Gauge selection
As all other piping equipment is purchased from Enerpac it would seem wise to purchase a
pressure gauge from the same source, unfortunately Enerpac pressure gauges reach
pressures of 700 bar and therefore it is difficult to accurately measure the pressures
required in the test rig. For this reason another source must be found for the pressure
gauge however the pressure gauge adapter is still provide by Enerpac.
Product: Pressure Gauge
Source: S.M. Gauge (www.pressuregauge.co.uk)
Price: £37.20
Reasons for Selection:
50mm, 70 bar/ PSI Pressure
Bottom entry 3/8” NPT
Steel Case
Brass Connection
Suitable for Gas or Liquid
It is also possible to purchase calibration certificates if required at an extra cost of £32.00.
If a multiple test system is desired then each individual test line will require its own
pressure gauge.
6.7 Collection Tank Selection
As it is likely that the flow rate is to be measured, it is important to accurately measure the
amount of water that is produced at the end of the test. It may be possible to use an
alternative container to collect the liquid and then pour this into a measuring cylinder;
however, this is likely to lead to inaccuracies in measurement especially with very low flow
19
rates. It is therefore suggested that a measuring cylinder is selected as the actual collection
tank to allow for these inaccuracies to be omitted.
Product: Measuring Cylinder - 500ml (Available in a range
of different sizes – see Appendices K)
Source: VWR International
Price: £18.30
Reasons for Selection:
Corrosion Resistant
Regular measurement intervals
Blue coloured readings for easy reading
University recommended source.
For a multiple test system multiple collection measuring cylinders would be required as the
variation between samples could be tracked and averages taken over specific experimental
setups.
6.8 Membrane Holder Design
The project contract stated that the membrane had to be in a flat sheet form for the test.
This was to get the base properties of the membrane of salt rejection and permeability
without the other materials that are located in a completed cartridge affecting the results.
Whilst the rest of the rig, e.g. pump, piping etc. could be sourced from external companies
the device for holding the flat sheet membrane is a specialist component and will be
required to be made. This section describes the design process for the various concepts
that were generated. Pugh’s total design theory was employed to ensure the best design
was selected for the task.
The test rig must be able to cope with pressures up to 70 Bar so the holder must also be
able to withstand this pressure safely.
Purpose
The device should be able to securely house a flat sheet of membrane, for the duration of a
20 minute test period at a pressure of 40-70 Bar.
Size
The device should be able to house the membrane so that there is a two inch diameter
available for flow to pass through.
Adaptability
Various membrane materials should be able to be housed within the membrane therefore
the holder should not be designed with only one type of membrane in mind.
Figure 9: Collection Tank (Measuring Cylinder)
20
Logistics
The device should be removable from the rig so as to gain access to the tested membrane.
This should not take an excessive amount of time, nor require equipment that is overly
specialised.
Material
The Membrane holder should be resistant to the corrosive effects of salt water and should
be maintainable through a cleaning process.
Safety
The membrane housing device should not fail under any conditions for reasons of
personnel safety. It should therefore be designed with the repetitive cycle of pressurization
as a key point.
6.8.1 Design Concepts
From the developed PDS, three concepts were generated that were deemed suitable for
the purpose of the assignment. These were: a bolted flange based design; a high pressure
NPT threaded device; and a Hydraulic sealing press.
Bolted Flange
Bolted flanges are used on many pressurized vessel and heat exchangers. For this project
the bolted flange can be said to be a joint between two pipes. Able to be used in high
pressure systems the bolted flange concept was suited to the project’s design due to its
capacity for safety as well as the simplicity of the connection. Within the bolted flange
there are five inter-dependant aspects that needed to be considered: bolts, gasket, flange
ring, taper hub and the shell.
The concept behind the design was to have the membrane material located coincident to
the gasket and thus secured in between the two flange faces.
NPT Threading
NPT Threading (or National Pipe Thread) is a US developed standard for tapered threads on
piping fittings that experience high pressure. The taper on the thread allows the system to
experience a fluid-tight seal and allows pressure upwards of 300 Bar.
The concept behind the design would see the membrane located in a clamp and then
placed in an NPT threaded system. The system would be screwed in using gaskets to
complete the seals around the clamp. The driving idea behind the use of the NPT
membrane holder was the ease at which it could be assembled and disassembled during
cycles of testing. Capitalising on this logistical bonus, two clamps could be made so that the
system could be instantly stopped, disassembled, and then reassembled all within a
minimum time period. A drawback of this design is that typical NPT threading does not go
beyond 2 inches making the design analysis questionable. The main concern with this
design is the gasket seal being damaged by the torsional motion of the threading action.
21
Hydraulic Sealing Press
Hydraulics is used in a wide range of industrial systems. By utilising an incompressible fluid
a hydraulic sealing press could generate the necessary pressure to keep the system sealed.
The concept behind the hydraulic system was similar to the NPT geometry, however
instead of being sealed with a thread, four cylinders located 0, 90, 180 and 270 degrees
about the flat face of the system would lock the membrane holder into place, again utilising
gaskets to seal the system. As an efficient mechanism with accurate calibration the
hydraulic seal would be easy to assemble. The main disadvantage of this system would be
the cost. Sourced from Enerpac, an entire hydraulic system would be required to be
purchased in order to seal the membrane holder.
6.8.2 Performance Matrix
A Pugh Matrix was constructed in order to examine the three concepts and compare the
desirable attributes.
Attribute Bolted Flange NPT System Hydraulic Seal
Ability to contain 75 Bar plus SF + + +
Size + + -
Ease of assembling into test rig + + -
Time of assembly - + +
Cost + + -
Cycle Lifetime 0 - +
Ease of manufacture 0 - +
Table 4: Pugh Matrix
6.8.3 Final Selection
The final choice for the membrane holder was the bolted flange design. Having performed
adequately in the performance matrix and as well as being a proven method for high
pressure piping designs the bolted flange seemed like a good comprise between
performance, safety and affordability. The overall geometry was designed using Creo
Parametric (see Appendix L) and calculations were carried out in accordance with the
PD5500 code for pressurized systems to ensure the safe operation of the shell under
pressure and the joint under both operating conditions and bolting-up load (see Appendix
L). Table 5 shows the dimensions of the flange in Figure 10 (for simplicity the flange was
designed as being symmetric). Detailed engineering drawings are included in Appendix M.
22
Figure 10: Membrane Holder Design
A Outer diameter of the flange 120mm
B Inner diameter of the flange and cylinder 50.8mm
g0 = es = ed Thickness of the flange shell, cylinder, and hemispherical end
6mm
g1 Thickness of the flange hub at lowest point 15mm
t Thickness of flange 15mm
r Radius of hemispherical cap 25mm
C Bolt circle diameter 100mm
db Bolt diameters 9.85mm
L Total length of the assembled flange 183.8mm
Table 5: Design Dimensions
6.8.4 Safety Analysis
Bolted flange safety is dictated by three different values of stress that act upon the joint.
These are longitudinal, radial and tangential. In order for a joint to be safely assembled and
operated, the three stresses must not exceed a certain allowable value of stress. Table 6
shows the final stress values for the bolting up conditions and the operating conditions.
These are compared with the allowable stresses of the flange design.
23
Stress Bolting Up Operating Allowable
Longitudinal
Radial
Tangential
Table 6: Allowable Stresses
Swivel fit connectors are to be welded onto the nozzle openings either side of the
membrane holder. This allows for assembly into the test rig to consume very little time as
well as the necessary freedom of the test rig during operation. This aspect of the design
also allows for multiple membrane holders to be manufactured therefore allowing a test to
be run whilst another test is being set up. It should be noted that during installation of the
rig the membrane holder should be mounted vertically, and with the outlet at the base so
as to allow the filtered fresh water to be collected using gravity.
One point of concern is that future membranes are suitable to be securely clamped in
position and able to experience the full operating pressure without damage being caused
to the membrane holder or membrane during the experimentation phase.
Gaskets for the operation of the joint are to be sourced from www.ramgaskets.com. These
custom made gaskets are to be made to the specification seen in Appendix M.
Material for the design of the membrane holder is to be sourced from Righton ltd. and the
manufacturing of the design is to be carried out at the University of Strathclyde in the
Mechanical and Aerospace Department.
Product: Stainless steel 316L
Source: Righton Ltd.
Size: 140mm Diameter by 200mm length billets.
Stainless steel was selected due to its excellent material properties for stress related
function as well as being resistant to the corrosion that salt water can cause. It is also an
affordable material and thus fits well within the budget.
6.9 Test Rig Support
As the rig requires a number of pipes and other components it may be wise to create a
support that holds everything in place. When conducting research, a number of similar rigs
were found which had supports that held components in place to ensure a clutter free
environment for testing. This would prevent unnecessary complications with the test and
would allow the user to conduct experiments simply and effectively. It is difficult to fully
assess what would be required until the project proceeds and components are confirmed,
however it is likely that this support could be constructed within the laboratories and could
be manufactured by the student or technician work orders can be discussed at the time if
the student does not feel competent.
24
As mentioned previously, if the system was to test multiple samples then there would be
an increase in the number of pipes required. If it were decided that a multiple sample test
would be preferential it would be highly recommended to discuss the Test Rig Support with
Chris Cameron (Head Technician) to ensure that there is no issue and to see what the
technicians could manufacture.
To take into account that a Test Rig Support may be needed, an extra £250 has been added
to the costing section this should provide the necessary materials however extra may have
to be included if technician costs are required.
6.10 Test Area
The test will be conducted within one of the laboratories at the University of Strathclyde,
before construction of the rig it is important to talk to Chris Cameron to obtain an area
where the test rig can be used. The rig area required is estimated to be around 2m2 and
the initial water tank will need to be held above the pump to allow for flooding. The
University has two laboratories (M4 or M5 Upper) that are used for tests where large
amounts of water are required due to there being increased drainage facilities available; it
would be advantageous to get test space within one of these laboratories. An electrical
connection will be required to run the motor and heating element. The electrical
connection should be isolated from the rig to prevent hazards.
7. Costing
Costs have been worked out including technician work required. There is one quotation for
a single test system and another for a multiple (6) test system. The full Costs including
delivery charges can be found in Appendix N.
Cost for a Single Membrane Test Facility: £16,131.95 (Inc. 20% VAT)
Cost for a Multiple (6) Membrane Test Facility: £24,417.21 (Inc. 20% VAT)
8. Construction Schedule
To plan the creation of the test facility it is necessary to create a construction schedule.
The schedule is based on the idea that this project will be continued by a PhD student and
therefore includes some necessary information that they may need to consider before
proceeding with ordering and construction.
Step 1: Background research into Desalination by reverse osmosis
The student should review what is required for their project. A time cannot be given for
this and the test rig construction schedule is focused on when the student feels ready to
proceed with testing.
Step 2: Review the design presented for the test rig (Roughly 2 weeks)
This project was conducted to design a test rig facility that may be required in the future.
The rig was designed to be adaptable and allows for a wide range of alterations however it
25
is important to ensure that all of the student’s needs are met before continuing with the
discussed design.
Things to consider:
How many membranes should be tested?
Will the pump provide the required pressures and flow rates?
Is there suitable measuring apparatus in place?
Does the suggested plan fit within student’s allocated budget?
Does the suggested plan fit within student’s time allowance?
Have prices or delivery timescales changed?
Step 3: Discussion with Supervisor and other staff (1-2 days depending on availability)
Before continuing with the build it is important that the student contacts all personnel that
are involved in the process.
People to speak to before building:
The supervisor should be informed of what is being built and any budgetary conditions
should be discussed.
Chris Cameron (Head Technician) should be contacted involving the building process
this discussion should include the following topics:
Plans of membrane holder design
Discussion of technicians available
Discussion of how long the work should take
Laboratory space available
Safety issues are highly important and risk assessments are required.
Pressure testing will be required, it is important to discuss this and plan for
what is necessary.
James Doherty (Stores) should be contacted about the process of purchasing the
required components. The Water Tank and Collection Tank are provided by a
University preferred distributor; all other components are provided by other sources, it
is therefore important to discuss sources and costs etc.
Step 4: Purchase required equipment and begin construction (10 weeks)
This part of the build project will be most time consuming due to the wait for components
to be delivered. A list of current delivery times is provided however these may have
changed by the time the build occurs.
Component Company Estimated Delivery (Days)
Water Tank VWR International 4-5
Heating Element www.allpondsolutions.com 2-3
Pump Michael Smith Engineers 8-10 Weeks
26
Piping System Powerflow solutions 5-7
Pressure Gauge S.M. Gauge 4-5
Collection Tank VWR International 4-5
Membrane Holder Righton Ltd 3-4
Table 7: Estimated Delivery Times
The Pump will take the most time to deliver, whilst waiting for this component it may be
possible to construct the membrane holders. In discussions with Chris Cameron he
suggested that it would take around a week to manufacture one membrane holder. He
also suggested that if multiple holders were required it would not take as long for each
component as it would be a repeated manufacturing process.
It is likely that after the membrane holders are created there will be a delay until the pump
arrives. It is planned that when the pump arrives all necessary components should be
available.
Step 5: Complete Construction (Approximately 1 week)
Once all materials are available it should take very little time to build the test rig as all
components connect simply. At this time the student should pay attention to creating a
test rig support. This support should ensure that the water tank is held above the pump to
allow for flow into the inlet. It is important to reduce clutter and ensure that the student
knows the task of every component; it is therefore recommended that the rig is labelled to
avoid confusion.
Step 6: Pressure Testing (2-3 days depending on availability)
Pressure testing can be conducted within the University, discussions should have been held
with Chris Cameron about the testing process and how long this will take at the time.
Schedule
If the plan is conducted as suggested above it should take approximately 16 weeks to build
the test rig however this depends on how much background research the student wants to
conduct before finalising a design and availability of technical staff.
A Gantt chart has been created to visualise the length of time, shown in Appendix O.
8.1 Conducting a Test
The test rig design presented allows for alterations to ensure that the student can test
whatever properties they desire. The following steps advise how the test can be set up to
gain a desired flow rate and stopped after conducting a test.
1. Prepare Feed-water
The water should be prepared to the desired specifications. Sodium chloride should be
added to tap water to gain a desired salt content. For nano-filtration systems it is wise to
27
also include magnesium sulphate and calcium chloride as both these chemicals are found in
water, however for this test it may not be necessary. The feed water pH should then be
adjusted to 8 by adding HCl or NaOH.
2. Heat the Feed-water
In the first test the water will be from a cold tap therefore it will take longer to heat to 25⁰C
but after this it is likely the water will sit at room temperature. The feed water should be
heated to the required temperature using the control from the heating element. Measure
this with an external thermometer to ensure accuracy.
3. Check Piping
Check the piping is correctly installed and that everything is tight.
4. Prepare Membrane
Place the membrane within the membrane holder and do not connect the membrane
holder to the system at this time, allow for flow without membrane holder. This is to
calibrate the system without the membrane.
5. Allow flow from the tank into pump
Open the tap on the water tank to allow flow into the pump.
6. Activate the pump.
Turn the pump on and allow flow through the system. After a few seconds view the
pressure provided on the pressure gauge and take note of this. Adjust the pressure / flow
rate using the pump.
7. Calibrate the needle valves.
The valves on the waste ends can be adjusted to allow for desired pressures and flow rates
in the main system. These should be calibrated and pressure and flow rate should be
measured should be viewed.
8. Turn off the pump after calibration
Turn off the pump and allow the system to drain without touching the needle valves and
pump controls.
9. Connect the membrane
Connect the membrane holder to the system.
10. Run the test.
Turn the pump on and allow flow through the system. Desired measurements should be
taken, it is likely that these will be the time the test runs, the volume of water that passes
through the membrane and the pressure this is conducted at. The temperature in the
initial water tank should be measured at various times and the heating element adjusted
accordingly.
28
11. Close the needle valve into the collection tank and membrane holder.
This will stop the flow into the collection tank / membrane and will allow for an accurate
time measurement to be taken and will ensure no more water passes into the membrane
holder.
12. Turn off the Pump.
This will stop the flow.
13. Quickly open other valves fully.
Opening the other valves will allow for flow back into the initial water tank to avoid waste.
After the water stops flowing, undo the piping before and after the membrane holder and
collect any waste water in a container. Turn off the flow from the initial Water Tank.
14. Conduct further tests.
At this point it may be necessary to test the permeate solution gathered for salt content or
test the membrane for various salt collection.
15. Clean
Clean components that have come in contact with salt water to reduce corrosion. It may
be wise to run non-salt water though the pump to reduce corrosion.
9. Reflective Analysis on Project Planning and Team Dynamics
A review of the project deliverables was conducted along with analysis of the group
dynamic in order to assess the successfulness of the project and hence the usefulness of
the management and control processes used throughout the duration of the project.
9.1 Delivering Objectives
At the initial phase of the project key objectives were drafted from the needs of the client.
After consideration of the objectives, success criteria for each was defined in order to
shape the future scheduled work and to ensure the agreed level of work was achieved. All
objectives and criteria were achieved so in terms of delivering objectives the project was
deemed a success.
9.2 Meeting Deadlines
In accordance to the Gantt chart created prior to the project start date the final hand in
dates were achieved. However, not all deadlines were met as planned during the overall
course of the project but mechanisms were put in place to ensure that the delays were
noticed and a new plan to get the project back on track was deployed.
At the first project presentation deadline some areas of the project had not been fully
completed (due to coursework deadlines occurring at the same time). The research
objectives had been completed ahead of schedule so this allowed for the reallocation to
team members to work on aspects of the rig design. A new Gantt chart was created to
account for the plan changes and was adopted for the second term of work. This allowed
29
for better time management of people and was ultimately responsible for completing the
project on time.
Throughout the course of work not all deadlines were met in accordance to the initial
plans. However the major deadlines, such as presentations and final submission dates,
were met in accordance with the new Gantt chart.
9.3 Test Rig Design Criteria
The main objective of the project was to design a test rig facility for the testing of single
sheet membranes for RO. An initial PDS was created for the entire system followed by an
individual PDS for the membrane holder. Using the original PDS a schematic was created
for the overall system ensuring that all points were met accordingly. For the membrane
holder Pugh’s total design theory was deployed to compare the concepts and select the
best design. This was achieved by constructing a Pugh Matrix (PM) to find the design that
best meets the criteria.
The final overall design therefore meets all the requirements of the client and the agreed
design specifications with a holder design to be created specifically for this purpose. In
accordance to the PDSs, the final design was deemed successful.
9.4 Team Dynamics
In order for the project to be completed successfully it was essential that the group
performed well as a team. A good team dynamic was essential to meet all of the key
objectives and criteria as defined in sections 1.2 and 1.3. Effective team ethics allowed
individual team members strengths to be utilised for the benefit of the project and this
created a motivational effect. Good communication was key in identifying the aspects of
the project that required more time than was originally planned for.
Possible area of improvement for the group would have been to assign a single project
manager. This would allow for consistent working techniques and this may have been
beneficial to the project in terms of better group dynamics.
10. Conclusions
In conclusion the group successfully met the objectives set out within the contract. A test
facility for reverse osmosis was designed, sourced and priced and a build schedule was
created alongside it for future projects. The industry was researched, covering both
current and future technologies, in order to better understand the deliverables of the
project. The project was completed to a level where another party can continue work with
the test rig construction and membrane testing.
The group worked well to deliver the set out objectives within the given timescale and a
good project management structure was key in achieving this. Rotational team positioning
was adopted in order for group members to obtain the best possible learning experience.
30
Bibliography
[1] DOW Corperation, 2013. [Online]. Available: http://www.dowwaterandprocess.com/en.
[Accessed November 2013].
[2] Nano H2O, 2013. [Online]. Available: http://www.nanoh2o.com/. [Accessed November 2013].
[3] Toray Corperation, 2013. [Online]. Available:
http://www.toray.com/business/products/environment/index.html. [Accessed November
2013].
[4] Hydranautics, 2013. [Online]. Available: http://www.membranes.com/. [Accessed November
2013].
[5] M. Thompson, “Reverse-Osmosis Desalination of Seawater Powered by Photovoltaics Without
Batteries,” Loughbourgh University, 2003.
[6] A. M. Bilton, L. C. Kelley and S. Dubowsky, “Desalination and Water Treatment,” MIT, 2010.
[7] C. Kurth, R. Burk, J. Green, J. LEPARC and P. Choules, “Long-term SWRO Testing of
Nanocomposite Membranes,” Nano H2O, 2009.
[8] K. Lee, T. Lee and D. Mattia, “A review of reverse osmosis membrane materials for desalination
- Development to date and future poential,” 2010.
[9] S. Lin and M. Buehler, “Mechanics and Molecularfiltration performacne of graphyne nanoweb
membranes for selective water purification,” 2013.
[10] M. Majumder, N. Chopra, R. Andrews, M. G. Taylor, X. Shao, E. Marand and J. K. Johnson,
“Zwitterion Functionalized Carbon Nanotube/Polyamide Nanocomposite Membranes for Water
Desalination,” 2013.
[11] F.Diederich, “Carbon Scaffolding: building acetylenic all-carbon and carbon-rich compounds,”
Nature, 1994.
[12] M. Kumar, M. Grezlaowski, J. Zilles, M. Clark and W. Meier, “Highly Permeable polmeric
membranes based on the incorporation of the functional water channel protein aquaporinZ,”
2007.
1
Appendix
A. Contract
Client: Dr William Nicholls
Dr Barbara Keating
Contractors: Laura Nicholls
Stephen Cooper
Andrew Crowe
Michael Osman
The following document will be used to identify our aims for the MEng Group Project.
The document includes the purpose of the investigation and discusses our initial plans;
there is a discussion of risk and what we will require from the supervisors during the
project.
Statement of Purpose
We will design and create a project schedule of an experimental test rig that will be
used to test various desalination membrane cartridges as well as researching deeper
into the current and future reverse osmosis technologies available.
The key objectives are as follows:
1. Design and cost an experimental test rig that enables the assessment of different reverse osmosis membranes.
2. Create a project schedule that includes a test facility construction timeline. 3. Review of current reverse osmosis membranes currently used in industry. 4. Review of new nano-scale membrane technology including carbon nanotube
membranes.
Time Allocation
As a group we have lots of opportunities to work together. Our timetables restrict our
meetings on Mondays and Tuesdays due to many classes, however we are available to
work together on Wednesdays, Thursday afternoons and Fridays. We will allocate as
much group work as possible to our project in these times. As tasks arise we will split
work according to requirements in other classes and commitments outside of
university. Outside of university times we will carry out as much work as our schedule
allows. Our initial plan is to have two members working on key objective 1, the other
two group members will also input with this objective but will look more into pricing
and timescales. All group members should research into current and future membrane
developments as this is key to all parts of the project, however it may be that a group
member may be given the task of researching in more depth.
Schedule of Activities
2
Our schedule of activities can be found in the Gantt chart attached. Various timescales
are subject to change as the project continues. This original chart shows an overview
of the project with each task being expanded as the project advances.
Milestones / Deadlines
These dates may be subject to change.
Statement of Purpose and Contract Submission Friday 18th Oct 2013
Interim Report Submission Friday 22nd Nov 2014
Final Report Submission Wednesday 26th Mar 2014
Presentation Monday 14th Apr 2014
Peer Review Wednesday 30th Apr 2014
Risk Analysis
This project is relatively low risk due to no reliance on materials or parts being created,
however there are a few risks that must be evaluated. These risks correspond with
companies that we are attempting to source materials from and individual risks within
the group itself.
As previously mentioned no parts are required due to this project being design based,
as no building is required we do not have to worry about resourcing time from the
technicians within the department. However, we will be contacting companies to find
the products that they provide, a delay may occur if the company is either unhelpful or
if a problem occurs with the company itself. This is a relatively low risk but it is
important to keep in mind as the project progresses. If a company is not as helpful as
we require it may be possible to ask Dr Nicholls or Dr Keating to front another letter,
therefore giving more substance to the request, once again this is an unlikely situation
to occur in the first place.
Another risk is from the time that we can allocate to the project, all members of the
group commit to spending as much time as the project requires however it is likely that
we may have other coursework that becomes priority for a brief time. In an attempt to
prevent this risk occurring we will continually correspond with each other to ensure
that if someone has other commitments then we will provide assistance with their
tasks within the project.
From a technological point of view we will prevent against loss by backing up the
information that we have and once a week ensuring that we share all data with the rest
of the group. Sharing data will also act as a preventive measure against delays if
something happens to a member of the group.
This project is low risk, there is no complication with money or building and risks with
timing can be kept to a minimum as long as we input the work that we suggest. Our
main aim for risk is to be vigilant and ensure all documents are backed up and that
every group member has access to these documents.
3
Responsibilities of the Client (Supervisor)
We propose having weekly meetings to ensure that the product we are designing is
what the client requires; these should be held on a Wednesday at 12 noon. At these
meeting we will discuss what we have achieved in the last week and also can ensure
that the test rig can be used for all tasks the client requires.
We would like to have gate meetings after key stages to ensure that the clients are
happy with our work before we advance to the next task, these will occur at various
points in the project the first being after we have carried out research into the industry.
Following meetings will be discussed after the research stage. Timings for these
meetings will be discussed as work continues.
We would like to ensure that Dr Nicholls is at these meetings as our primary supervisor
and we would appreciate if Dr Keating could also be available. We understand that
both supervisors have other tasks that require a great deal of attention but would like
24hour notice if a meeting is cancelled or altered so that we can allocate the meeting
time to another part of the project.
4
B. Product Design Specification (PDS)
Using the statement of purpose a Product Design Specification (PDS) was formed. This
contains all of the requirements that the test rig must meet with the needs of the customer
at its centre.
1. Purpose
1.1. Pressurised test Rig
1.2. Used for testing Reverse osmosis membranes
1.3. For use with single layer membranes
1.4. Must have inlet and outlet collection tanks
2. Cost
2.1. Approximate budget of £30,000
3. Customer
3.1. What sort of research is to be carried out?
4. Environment
4.1. Will be in a laboratory environment
5. Size Limitations
5.1. Workspace size approximately 3 meters by 2 meters
5.2. Whole system: test rig plus collection and feed water tanks
5.3. Must suitably fit membrane test samples
6. Adaptability
6.1. Should allow for variation in membrane thickness
6.2. Should have variable pressure capability (40-70bar)
7. Installation
7.1. Must be able to remove specimen easily
7.2. It must have secure attachments around the membrane
8. Materials
8.1. The material must be corrosive resistant
9. Industry Standards
9.1. Pressurised body should comply with British standards
9.2. Join should comply with British standards
10. Safety
10.1. Rig should be fitted with a pressure safety valve
10.2. The machine must not be operated until the joint is fully in place
10.3. The rig should not leak during operation
11. Maintenance
11.1. To reduce the corrosive effect of the saltwater the rig should be cleaned
after tests have been carried out
11.2. Regular changes to the gaskets in the membrane holder
11.3. Pressure testing to ensure the membrane holder is safe and fully functional
5
C. Example of Minutes
Meeting 3 - 23/10/13
Attendance:
Stephen Cooper
Michael Osman
Laura Nicholls
Dr William Nicholls
Andrew could not make this week due to Hockey Captain commitments.
Important Actions During Week
The Contract / Statement of Purpose were submitted on the 18/10/13 as planned.
Dr Nicholls sent some information from the DOW Company. We all read through this and
made notes accordingly.
Discussions During Meeting
The main scope of discussion was on the papers that Dr Nicholls sent and a small amount of
research into the industry.
The paper gave the composition of test water as discussed last week.
There was an overview of the codes DOW use to name their products.
The pressure of the pump and maximum operating pressure were found, these are very important for designing the test facility.
Dr Nicholls seemed reasonably impressed and during a discussion about the material
composition began to talk about zwitterion ions and other advanced topics. He has
forwarded a paper on the subject that Michael and Stephen should especially look into.
The general point of the discussion is that Michael and Stephen should try to find out the
material properties for next week.
Advice From Supervisors
Continue what we are doing and attempt to focus more on the rigs and membranes.
Future work
Laura and Andrew – Look into papers on the testing of membranes and try to discover how
companies carry out their testing. Research papers must explain how testing was carried
out to be valid so this is a good place to start from.
Michael and Stephen – Look for further information on the design of the membranes itself.
Read through the zwitterion ion paper and try to understand this, this is not a priority but
may be useful.
Next Meeting – 30/10/13 @ 12.00
6
D. Original Gantt Chart
7
E. Amended Gantt Chart
8
F. Selection of Water Tank
The salt water that will be used in the system must be previously prepared and stored
correctly. It is important to assess the various types of water tank that are available to
ensure that the selected model will meet all requirements.
Considerations
There are a number of considerations that must be made to ensure that the correct water
tank is selected. A selection specification was created to ensure the important information
was evaluated.
Environment
The water tank must be corrosive resistant due to the salt water content.
The temperature within the tank will be 25⁰C.
Practicality
The tank must have a large enough inlet to allow for heating element and pipe
insertion.
The tank should have an outlet to allow flow into the system.
Dimensions should be taken into consideration to ensure the heating element does
not breach the water surface.
Cost
It is important to limit the costs of the water tank; however focus should be placed
on quality not price.
Safety
As a heating element will be inserted within the bath, considerations must be made
to ensure the element does not make contact with the vessel walls.
The heating element must not breach the surface of the water.
Selection Process
The main consideration for the initial water tank within the system is that it must be made
of a non-corrosive material. A vessel made of plastic should be selected as it will be a
cheaper option that is readily available. The test does not require a huge amount of fluid,
however it is important that the heating element does not breach the surface of the liquid,
therefore a larger tank should be selected.
From these considerations it was decided that the best type of water tank would be one
that is designed to distribute liquids in laboratories. James Doherty (stores) was contacted
to see if he knew of any University sources that provided this type of equipment, he
suggested VWR International.
VWR International is a University recommended source that provides equipment for
various tasks within laboratories. From looking through their brochure a water tank design
was found that filled the selection specification criteria discussed above. This design of
9
tank also comes in various sizes that would ensure that there was enough water within the
tank so that the heating element does not break the surface.
The type of vessel that has been selected has a relatively small inlet at the top, therefore it
may be required that the top of the vessel would need to be cut off to allow for the piping
and heating element insertion. In this case a stiffener would be required. Discussions with
Chris Cameron suggested that this work could be carried out by a technician and would
take around an hour of their time.
The type of vessel selected also has a moulded tap at the bottom to allow flow into the
system. This was one of the benefits of selecting this design as it means that no technician
work is required to insert a tap. This design will require an adapter from tap to NPT pipe or
a pipe can be purchased that will require an adapter into the pump. The latter may be a
cheaper option as the flow is not at high pressure and therefore NPT high pressure piping is
not necessary.
Product and Costing
Before purchasing the water tank it is important to assess the dimensions of the vessel to
ensure that the heating element does not breach the surface of the water. It is believed
that the 20L container will be capable of this task due to the low flow rate required when
testing one sample, however if it was decided that multiple tests were required then a
larger tank may be necessary. Dimensions of all the available tanks are given along with
prices to ensure that the correct choice is made.
For future costing discussions a tank of 20L was selected.
Distributor: VWR International
Address: VWR International
Hunter Boulevard
Magna Park
Lutterworth
Leicestershire
LE17 4XN
Telephone: 0800 22 33 44
Web-site: uk.vwr.com
Contacted: Mr Sam Bass
Contacted by: Mr Michael Osman
Product: Carboy
10
Capacity (L) Catalogue number Height (mm) Diameter (mm)
Price (£) (Inc. VAT)
10 216-4407 389 250 77.40
20 216-4408 528 286 112.00
25 216-4409 594 287 133.00
50 216-4410 678 379 198.00
Delivery: Free
Delivery Time: 4-5 days
Additional materials like piping are available from the source. For the purpose of this evaluation the piping was included in the Enerpac order so that the more expensive option was discussed.
11
G. Selection of Heating Element
It is important to keep a standard temperature when evaluating the effectiveness of a
reverse osmosis membrane. In full scale operation water will pass through a membrane
cartridge at around 25⁰C due to room temperature with added heat from other
components. The laboratory facilities within the University will vary in temperature
however it is unlikely that they will be above 25⁰C and therefore a heating element is
required to ensure a constant temperature.
Considerations
There are a number of considerations that must be made to ensure that the heating
element selected will carry out the task effectively. A selection specification was created to
ensure the important details were evaluated.
Environment
The heating element will operate at atmospheric pressure.
The water must be kept at a constant temperature, whilst water volume drops.
Salt Water – Corrosive environment.
Safety
The element must not come out of the water before being turned off
The element must not make contact with the water tank.
The element must not breach the surface of the water.
Cost
The heating element should be kept as cost effective as possible.
Practicality
Heating should be relatively quick.
Temperature control preferential.
To ensure that the water is heated in a reasonably quick time it is important to calculate
the required power.
Where is the Specific heat, m is the mass in kg and T is the temperature difference in
Kelvin. As the liquid used is salt water the specific heat is identified to be 3.93kJ/kg.K. The
mass of water will be a maximum of 20kg. The change in temperature will be very small as
the temperature in the lab is likely to be quite high, however a 5⁰C temperature change will
be used as a maximum. This assumes the water is prepared before and sits at room
temperature however if water is cold it will take a longer time to reach the desired
temperature.
12
This is the equivalent of 109.2W required to heat 20L of water by 5⁰C in an hour. As it is
not practical to wait for an hour to adjust the temperature, an element with a higher power
rating is required. The Product and Costing section includes three different Power rated
elements and the length of time to heat the water.
An important consideration must be made to the corrosive effects within the water tank
due to the solution being salt water. It is important to select a heating element made of a
non-corrosive material in an attempt to improve the life span of the element and to ensure
the salt water is not contaminated by rust. The heating element should be cleaned after
use to ensure corrosion does not occur.
Product and Costing
Various sources were examined to evaluate the best heating element for the test rig. It
became apparent that the best solution was to use a fish aquarium heater. These heaters
operate in salt water and are used in similar temperatures. Mr John Redgate, electrical
technician in the James Weir labs, agreed with this decision and discussed safety issues,
which are mentioned in the selection specification above.
Distributor: www.allpondsolutions.co.uk
Telephone: 01895 437 612
Contacted by: Mr Michael Osman
Component Name: Titanium aquarium fish tank heater
Features:
Suitable for Salt water and freshwater aquariums
Virtually unbreakable high-quality pure titanium
Airtight, corrosion-proof design
Easy to use
External thermostat dial control for easy adjustment
Suction cups supplied for easy installation
Dimensions - 17mm × 270mm
Power (W) Time to heat by 5⁰C Cost (£) Incl VAT
100 ~ 1 hour 22.99
200 ~ 30mins 24.99
300 ~ 20 mins 29.99
Delivery: 2-3 days
Carriage: FREE
13
Additional components may be required to ensure the heating element does not come in
contact with the water tank wall. These can also be purchased from
www.allpondsolutions.co.uk but are not priced because it is difficult to say which part may
be required and it is likely that James Doherty (Stores) would have a solution available.
14
H. Selection of Pump
The pump is likely to be the most important part that is purchased for the test rig. It will
need to provide variable pressures and flow rates to ensure that a membrane can be fully
assessed for a range of properties. The majority of part selection time was spent on
selecting the pump to ensure that the correct product is provided. This section will include
information on what was required when selecting a pump and why the selected pump was
chosen.
Considerations
The pump is a vital piece of equipment within the test rig. To ensure that selection was
carried out correctly a selection specification was created that would allow for the
selection of the best pump for task required.
Main Requirements
The maximum pressure should be 70 Bar.
The pressure should be adjustable. (May not be achieved by pump its self but extra
equipment available)
The inlet and outlets should be NPT threaded.
Flow rate should be adjustable between 0.05L/min and 1.5L/min (this is a goal and
between these values is acceptable)
Environment
Corrosive environment – material selection important
Test rig will probably not take up a large area so keep pump small.
Safety
A pressure relief valve is required to ensure there is no back flow into the pump.
Cost
Likely to be the most expensive equipment.
Attempt to keep cheap but assess the advantages and disadvantages before ruling
out an option.
Price may increase if extra equipment offered
Life-span
Material Selection is important to ensure extended life-span.
Replacement components should be available if required.
Practicality
It is preferential that a motor is offered with the pump to ensure correct fitting and
application.
If the pump can run dry there is less risk of pump damage.
It would be preferential if the pump does not require a large head pressure.
15
It would be wise to speak to distributors to gain advice on what they believe which
pump is best for Desalination situations.
Selection of Pump Process
As the pump is a vital piece of equipment in the test rig it was important to fully
understand the types of pump available and assess what would be best for a reverse
osmosis application. One of the specifications discussed above is that it is important that
the pump does not require a large head pressure. If a large head pressure is required then
it is likely that another pump will be required to reach this pressure. For this reason it was
decided that a positive displacement pump would be required. A positive displacement
pump only needs to be flooded to operate; therefore eliminating the need for an additional
pump.
After deciding that the test rig requires a positive displacement pump the next step was to
research companies that manufacture suitable pumps. A number of different companies
were looked at who supply pumps for use in desalination applications. Unfortunately these
pumps have too high a flow rate as they are used in systems with membrane cartridges and
not with single membrane sheets. Eventually after researching a number of companies the
Wanner Hydra-cell range of pumps was discovered which offered pumps for a wide range
of applications.
The Hydra-cell range of pumps is designed for applications that require pumping abrasive
and corrosive materials. They offer a range of different materials for various components
that can be selected to ensure the pump is purpose built for the task required. It is also
possible to gain a pump that allows for adjustable pressure and flow rates, a property that
was difficult to find in other pumps. To explain the choice of the Hydra-cell pump further
the following information is provided that shows the pump is perfect for the required job.
The pump can be adjusted between 40-70 Bar.
The pump allows for a range of flows between 0.09L/min and 1.3 L/min.
It is a positive displacement pump that only needs to be flooded to operate.
The pump offers virtually pulseless flow.
Sealless leak free design.
The pump can run dry.
Hydraulically balanced diaphragms for long service life.
The pump has three blocked inlets and outlets; these can be used to split flow at an
earlier stage if required.
Small Space Footprint
Low power consumption.
The pump meets API 675 performance standard.
The pump has NPT threaded inlets ad outlets that allow for piping to be easily inserted.
Various materials can be selected to ensure corrosion resistance.
Wanner produce range of pressure relief valves that are set to a previously set
pressure.
Wanner provide the inverter/motor that is required to run the pump.
16
To assess the materials that would be required CES material selector was used to
determine the price/performance ratio. From this assessment Hastelloy C-276 (Nickel-
Molybdenum-Chromium Alloy) was selected for the majority of options. Hastelloy is a
super alloy that is commonly selected for its attractive price/performance ratio. The
primary function of Hastelloy alloys is the survival under high stress applications in severely
corrosive or erosive environments.
The UK distributor for the Wanner Hydra-cell pumps is a company named Michael Smith
Engineers, they supply a range of pumps and discussions with this company have been held
concerning what is best for the task required. They highly recommend this pump for the
test rig and have been very helpful with the selection process. They do supply other pumps
that will operate to the desired specification, however these are more expensive and
Michael Smith Engineers suggested from previous experience that these would have a
reduced life-span compared to the purpose built Hydra-cell pumps. They also confirmed
the idea that Hastelloy C would have the best price/performance ratio and will increase the
life expectancy of the pump.
Product and Costing
Information on the exact product information can be found in the following pages where
the pump brochure and quotation is provided.
The quotation includes the price of following:
Hydra-cell G03 Sealless Diapraghm pump.
Pressure Relief Valve previously set to 72 Bar to prevent backflow and component
damage.
Inverter/motor that is used to power the pump at the variable flow rates.
The following pages include the brochure and original quotation for the pump selected.
17
18
19
20
21
22
23
24
25
I. Selection of Piping System
As the desalination laboratory test facility requires water to be transferred at high pressure
around the components it is important to ensure that the correct piping equipment is
selected. Consideration must also be made to future expansion of the rig if this is desired.
This section will discuss the necessary equipment for the piping system including costing
and will expand to include what is required for the system to be scaled in future.
Considerations
It is important to assess what piping is required for the desalination test facility as there are
a number of safety issues that may arise if this is not done properly. To ensure the correct
design was selected a selection specification was created.
Environment
The piping must withstand pressures up to 70 Bar.
Temperature is not an issue.
The piping must be able to withstand expansion and moving forces.
Corrosive environment
Safety
Components must withstand high pressure
Each connection must be securely locked to ensure no leakage.
Cost
As there will be a number of components it is important to limit costs for individual
items.
Consideration must be made to multiple test system.
Practicality
It would be preferential if piping could be easily manipulated, moved around etc.
It should be simple enough to build and dismantle the piping systems if required.
Should be relatively simple to select required components
Should be relatively simple for work to be carried out by technicians.
How piping was discussed
Initially a piping system involving one membrane test was designed for, this would then be
scaled up if required in the future. There were two design ideas for the piping system,
these were;
Metal piping
Rubber hoses (Enerpac)
These ideas were discussed at various meetings and the advantages and disadvantages
were weighed against each other.
26
From these discussions it was deemed that Rubber hoses would be preferential for the
design as there are numerous advantages with the only disadvantage likely being the price.
When discussing the problem with supervisor he mentioned that previously he had sourced
similar piping from a company named Enerpac and more research was carried out on this
brand.
From further research it was decided that Enerpac piping filled the selection specification
thoroughly but may cause a slight price increase, this was deemed acceptable as it would
increase the practicality of the test facility and would reduce complications involving
building. Enerpac piping has been tested and certified up to pressures of 700bar which is
well within safety standards required. It would allow simple construction and would
require very little man work from the technicians; therefore reducing the costs and time of
construction.
As Enerpac has designed a whole range of equipment for high pressure systems, using this
idea reduces the need for complex calculations to be carried out and the design can be
kept simple. Parts can be selected as required and as they are all from the same company
Metal Piping Rubber Hoses (Enerpac)
Pros Cons Pros Cons
Cheap to purchase
May require extra technicians hours which may be costly
Simple selection method, no calculations required
More expensive
Not flexible Flexible Adapters required
Difficult to dismantle due to welding being required
Certified up to 700 bar Only NPT threaded not BSPT. Must ensure correct for pumps
Requires calculations Simple connection to pump if NPT threaded
Would require extra testing
Simple to dismantle
May not fit into pump simply
Corrosive Resistant
Not corrosive resistant All parts from one supplier
27
they fit together very well, however parts sometimes need 2 or 3 adapters to adjust sizes
etc.
Part Selection
To ensure the correct parts were selected for costing it was important to take all
connections and adapters required into account. This is for a system testing one
membrane at a time; more membranes will require more components.
The piping supplied by Enerpac has 3/8” male fittings on each end. In various components
it is required that this size is increased or decreased. The table below shows the parts
required and how they connect.
Sourcing all parts from Enerpac makes the process much simpler, however a pressure
gauge was found at another source as Enerpac gauges do not operate in the small scale
required; they go from 0-700bar and are not accurate around 70 Bar. More information
can be found in the Pressure Gauge section of the report.
Needle Valve
Pressure Gauge
Adapter
Swivel Fit
Street Tee
Adapter
Swivel Fit
Water
Tank
Water
Tank
Holder
Collection
Tank
28
Brief guide to adapters – Part required is between the From and To components
Part Required Reasons Part code From Part-size To Part-size
Initial System without waste flow
Pipe – 0.6m Simple fit H-7202 Water Tank Outlet*
-* Swivel Fit 3/8” F
Swivel Fit 3/8”F – 1/2” M
Swivel fit allows turning of pipe + adapter
FZ-1660 Pipe* 3/8” Male
Pump Inlet 1/2” Female
Pipe – 0.6m Simple fit H-7202 Pump Outlet
3/8” F Street Tee 3/8” F
Street Tee
3/8” F – 3/8” M
Allows split flow and has male outlet to connect to needle valve
BFZ-16312 Pipe 3/8” M Needle Valve 3/8” F
Needle Valve
3/8” F – 3/8” F
Stop flow into membrane holder allows flow to go to waste
V-82 Street Tee 3/8” M Pipe 3/8” M
Pipe – 0.6m Simple Fit H-7202 Needle Valve
3/8” F Reducer 3/8” F
Reducer 3/8” F – 1/4” M
To reduce down to get to 1/2”
FZ-1630 Pipe 3/8” M Reducer 1/4” F
Reducer
1/4” F – 1/2” M
To reduce down to get to 1/2”
BFZ-1630 Reducer 1/4” M Gauge Adapter
1/2” F
Gauge Adapter
1/2” F – 1/2” M **
Allows Pressure gauge attachment
GA-918 Reducer 1/2” M Reducer 1/2” F
Reducer
1/2” F –
3/8” F
Allows adaption back to pipe dimension
FZ-1625 Gauge Adapter
1/2” M Pipe 3/8” M
29
Pipe – 0.6m Simple Fit H-7202 Reducer 3/8” F Swivel Fit 3/8” F
Swivel Fit 3/8”F – 1/2” M
Swivel fit allows turning of pipe + adapter
FZ-1660 Pipe 3/8” M Membrane holder inlet
1/2” F
Swivel Fit 1/2”M –
3/8” F
Swivel fit allows turning of pipe + adapter
FZ-1660 Membrane holder outlet
1/2” F Pipe 3/8” M
Pipe – 0.6m Simple Fit H-7202 Swivel Fit 3/8” F Street Tee 3/8” F
Street Tee
3/8” F – 3/8” M
Allows split flow and has male outlet to connect to needle valve
BFZ-16312 Pipe 3/8” M Needle Valve 3/8” F
Needle Valve
3/8” F – 3/8” F
Stop flow into collection tank, allows flow to go to waste
V-82 Street Tee 3/8” M Pipe – 0.6m 3/8” M
Pipe – 0.6m Allows flow into tank
H-7202 Needle Valve
3/8” F Collection Tank
-
Back Pressure Waste Flow
Pipe – 1.8m Allows waste from pump pressure release to return to initial water tank
H-7206 Pump Pressure Release outlet
3/8” F Water Tank
-
Waste Flow Before Membrane
Pipe – 0.6m Allows waste flow back to water tank from before the membrane. This system prevents salt build up and waste at end of test.
H - 7202 Street Tee 3/8” F Needle Valve
3/8” F
Needle Valve
3/8” F – 3/8” F
Regulates flow back to initial water tank, can cause shut off if
V-82 Pipe 3/8” M Pipe 3/8” M
30
required.
Pipe – 0.9m Allows waste flow back to water tank from before the membrane. This system prevents salt build up and waste at end of test.
H-7203 Needle Valve
3/8” F Water Tank
-
Waste Flow After Membrane
Pipe – 0.6m Allows waste flow back to water tank from after the membrane.
H - 7202 Street Tee 3/8” F Needle Valve
3/8” F
Needle Valve
3/8” F – 3/8” F
Regulates flow back to initial water tank, can cause shut off if required.
V-82 Pipe 3/8” M Pipe 3/8” M
Pipe – 1.8m Allows waste flow back to water tank from after the membrane when test completed.
H-7206 Needle Valve
3/8” F Water Tank
-
*Parts are subject to alteration due to complexity of Water Tank outlet
** Pressure gauge adapter purchased from Enerpac actual pressure gauge from another source. See Section 6.6 Pressure Gauge Selection.
All pipe lengths are variable and selection has been made using what seems sensible from
sizes allowed. Sizes that Enerpac advertise are 0.6, 0.9 and 1.8m, however there may be
other types available if requested specifically.
A summary of what products and quantities is shown below. This was the document sent
to the distributor for costing.
Product Type Product Description Item Number Quantity
Hoses Hose 0.6m 3/8 NPT + 3/8 NPT H-7202 8
Hose 0.9m 3/8 NPT + 3/8 NPT H-7203 2
31
Hose 1.8m 3/8 NPT + 3/8 NPT H-7206 2
Adapters 3/8” – 1/2” NPT Swivel Fitting FZ-1660 3
3/8”F – 1/4”M Reducer FZ-1630 1
1/4”F – 1/2”M Reducer BFZ-1630 2
1/2”F – 3/8”F Reducer FZ - 1625 1
Gauge Adapter GA-918 1
Fittings 3/8”F – 3/8”M Street Tee BFZ - 16312 2
Needle Valve 3/8”F-3/8”F V-82 3
Total 25
Summary of what Enerpac equipment is required.
Costs
Distributor: Powerflow Solutions
Address: Powerflow Solutions Ltd
Clifton View
Broxburn
West Lothian
EH52 5NE
Telephone: 01506 853533
Web-site: www.powerflowsolutions.co.uk
Contact regarding existing quote: Mr Stephen Greenwell ([email protected])
Contacted by: Mr Michael Osman
Description Part Number
Quantity Net Price (Each £)
Total Cost (£)
Enerpac Safety Hose 0.6mtr H7202 8 40.50 324.00
Enerpac Safety Hose 0.9mtr H7203 2 48.60 97.20
Enerpac 1.8mtr Hose H7206 2 59.40 118.80
Enerpac 3/8" NPT Male x Female swivel fitting FZ1660 3 54.00 162.00
Enerpac Reducer 3/8” to 1/4” FZ1630 1 5.48 5.48
32
Enerpac Adaptor BFZ1630 2 10.96 21.92
Enerpac Reducing Adaptor 1/2 npt-3/8npt F/F FZ1625 1 24.67 24.67
Enerpac Gauge Swivel Adaptor GA918 1 67.50 67.50
Enerpac Adaptor 3/8" NPT Street TEE BFZ16312 2 42.30 84.60
Enerpac 3/8" NPT Speed control / Shut off Valve
V82 3 85.50 256.50
Carriage 1 16.00 16.00
Excl VAT 1178.67
Incl VAT
(20%)
1414.41
Delivery: 5 to 7 days but may vary at time of purchase.
Quote Reference
Quote Valid: 30 days. Prices may change.
Multiple Test System
If it was decided that a multiple test system was required then Enerpac piping could still be
used, however the costs would be increased and a larger working area would be required.
The selection of piping is not over complicated if this is the case however and it would
simply be a case of purchasing a flow-splitting manifold which would be inserted after the
pump pressure relief outlet and then multiplying the system past this point. To summarise
what may be required a table below suggests the quantities and costs of the piping
equipment necessary (This assumes a test rig with 6 membrane tests, Enerpac supply
manifolds that would allow for 3 or 6 tests).
Description Part Number
Quantity Net Price (Each £)
Total Cost (£)
Enerpac Safety Hose 0.6mtr H7202 44 40.50 1782.00
Enerpac Safety Hose 0.9mtr H7203 12 48.60 583.20
Enerpac Safety Hose 1.8mtr H7206 7 59.40 415.80
Enerpac 3/8" NPT Male x Female swivel fitting FZ1660 13 54.00 702.00
33
Enerpac Reducer 3/8 “ to 1/4” FZ1630 6 5.48 32.88
Enerpac Adaptor BFZ1630 12 10.96 131.52
Enerpac Reducing Adaptor 1/2 npt-3/8npt F/F FZ1625 6 24.67 148.02
Enerpac Gauge Swivel Adaptor GA918 6 67.50 405.00
Enerpac Adaptor 3/8" NPT Street Tee BFZ16312 12 42.30 507.60
Enerpac 3/8" NPT Speed control / Shut off Valve
V82 18 85.50 1539.00
Enerpac 7 port manifold (6 outlets) A65 1 115.20 115.20
Carriage 1 16.00 16.00
Excl VAT 6378.22
Incl VAT
(20%)
7653.86
As mentioned above this would require a greater amount of space, however this is
possible. It also may be possible to reduce the amounts of cables by using manifolds to
bring the flow back to one pipe. In this case the rig would have to be revisited to ensure
that there is no alteration in pressures or flows that must be taken into account. This has
not been looked at further as the project purpose was to design a rig with one membrane
holder but has been suggested so that if a PhD student continues the project then they will
have more idea of the costs required.
Important consideration
ENERPAC FITTINGS ARE NPT STANDARD – ENSURE THAT THE PUMP IS ALSO NPT THREADED
AND NOT BSPT WHICH IS THE STANDARD OF THE PUMP SUGGESTED. NPT THREADED
PUMPS ARE AVAILABLE FROM MICHAEL SMITH ENGINEERS BUT DO NOT ASSUME THAT
THEY WILL BE GIVEN UNLESS REQUESTED FOR.
34
J. Selection of Pressure Gauge
To correctly evaluate the performance of a membrane it is important to assess the pressure
that it operates at. As the pressure output from the pump is variable it is valuable to have
an accurate pressure gauge before the membrane so that an accurate pressure can be
recorded before the fluid passes into the system.
Selection
As the majority of equipment is being sourced from Enerpac it may seem wise to also order
the pressure gauge from this retailer. When evaluating the product required it became
apparent that Enerpac pressure gauges operate at a pressure much higher than what is
required in this system due to the fundamental usage of this equipment being for hydraulic
systems at 700 Bar. For this reason it was decided to source a pressure gauge from a
different retailer. It should be noted at this time that the Pressure gauge adapter would be
purchased from Enerpac as this would fit simply into the piping system.
As the gauge adapter would be purchased from Enerpac it was important to ensure that
the pressure gauge advised would assemble correctly, therefore an NPT screw thread is
required. There also needs to be a maximum pressure of 70 Bar. As has been mentioned
previously there is a possibility that the rig will be created with multiple samples being
tested, in this case it is important that each pipeline has its own individual pressure gauge
as to ensure accurate results.
The company that was selected was done so because it is a specialist in producing pressure
gauges. The prices given were very competitive with other retailers and availability of the
product was much shorter than other retailers.
The company can also provide calibration certificates for all products; this may be required
to show accuracy of measurements however there is a price increase for these.
Product and Costing
Distributor: S.M. Gauge Co.
Address: SM Gauge Company Limited
308/312 Lodge Causeway
Fishponds
Bristol
BS16 3RD
Telephone: 0117 965 4615
Web-site: www.pressuregauge.co.uk
Contacted: Mr Len Baker
Contacted by: Mr Michael Osman
35
Description Net Price (Each £)
Total Cost (£)
50mm, 70 bar/ PSI Pressure Gauge
Bottom entry 3/8” NPT
Steel Case
Brass Connection
Suitable for Gas or Liquid
£16.00 £16.00
Calibration Certificate (Optional) £32.00 £48.00
Carriage £15.00 £63.00
Price One Unit Excl VAT (20%) £63.00
Price One Unit Incl VAT (20%) £75.60
Price six Units including VAT (20%)
£453.60
Delivery: Will currently take 1 to 2 days but may be change at time of purchase.
36
K. Selection of Collection Tank
The water must be collected at the end of the de-salina tion process therefore it is
important to assess what results may be required to find a collection tank that does not
introduce error into the experiment.
Selection
As it is likely that the flow rate is to be measured it is important to accurately measure the
amount of water that is produced at the end of the test. It may be possible to use a bucket
to collect the liquid and then pour this into a measuring cylinder; however this is likely to
lead to inaccuracies in measurement especially with very low flow rates. It is therefore
suggested that a measuring cylinder is selected as the actual collection tank to allow for
these inaccuracies to be omitted.
It may be possible to source a measuring cylinder from the University labs that has been
previously used in other experiments but for the purpose of costing all necessary
components a measuring cylinder has been sourced. The source is VWR International
which is the same source as the initial water tank. The source provides a range of different
sizes of measuring cylinder, these are shown below and the correct size should be selected
when final design is confirmed. It is unclear whether for a multiple test system there would
need to be multiple collection measuring cylinders or one large one; therefore it is
important that selection occurs after the number of membrane tests has been confirmed.
For the purpose of costing the overall rig a measuring cylinder of 500ml was selected for
costing.
Product and Costing
Distributor: VWR International
Address: VWR International
Hunter Boulevard
Magna Park
Lutterworth
Leicestershire
LE17 4XN
Telephone: 0800 22 33 44
Web-site: uk.vwr.com
Contacted: Mr Sam Bass
Contacted by: Mr Michael Osman
Product: Measuring Cylinder
37
Capacity (ml) Catalogue number Height (mm) Price (£) (Inc. 20% VAT)
10 612-0434 140 3.20
25 612-0435 140 4.50
50 612-0436 200 4.70
100 612-0437 250 6.40
250 612-0438 315 11.40
500 612-0439 360 18.30
1000 612-0440 440 25.50
2000 612-0441 535 53.20
Delivery: Free
Delivery Time: 4-5 days
38
L. Membrane Holder Design
Thickness Calculations
All calculations for the design were done in accordance to the PD5500 Code for Pressurised
Vessels. The following design data was used based on Stainless Steel 316L and taken from
the CES Education Pack:
Design Pressure 75 Bar (7.5 N/mm2)
Design Temperature 25 o C
Density of Steel 7860 Kg/m3
Material Yield Point @ 50oC 275.79 N/mm2
Young’s Modulus 188,000 N/mm2
Inner Diameter of Cylinder Shell 50.8mm
Feed Pipe Opening 12.7mm
Cylinder
For allowing thinning and corrosion allowance an extra 3mm was added onto the shell
giving a final thickness of 4mm.
Hemispherical Ends
Therefore:
Pressure is the same as for Hemispherical Cap as it is for the cylindrical shell and f is the
same as f50:
Using the figure 3.5-2 in the PD5500 Code Design curves for unpierced domed ends, e/D
can be read off the graph. The value was taken as being 0.02.
39
Again add approximately 1mm for thinning allowance and 2mm for corrosion allowance to
get a final thickness of 4mm. Furthermore keeping the 4mm thickness as uniform would
also allow for easier manufacturing of the component.
Opening for the Weld of the Feed Pipe
From PD 5500 the following steps were observed:
(a) Calculate eps thus with a new value of Deff:
(b) Select a value of ers the minimum reinforced shell thickness, not less than eps
(c) Calculate the mean shell diameter D using the selected thickness.
(d) Calculate - the minimum required thickness of the nozzle wall for pressure
loading using the following, where is the inner nozzle diameter:
(e) Select a value of – the minimum reinforced nozzle thickness, not less than .
(f) Calculate the mean nozzle diameter d using the thickness:
(g) Calculate from the following:
√
√
And then in accordance with the PD 5500 Code:
40
(h) The following values were calculated:
As
then from the figure 3.5-9 in the PD 550 code
However since the calculated value of
exceeds the value of p for the appropriate figure
then in accordance with PD5500
and therefore no additional reinforcement is
required for the opening and therefore the connector is suitable to be welded on straight
away. Furthermore no more additional iterations are required to complete the calculation.
In summary a uniform thickness of 4mm was deemed to be safe for the thickness of the
design.
Bolted Flange Calculations
Bolt Loads and Areas
PD5500 requires that sufficient bolting is provided to produce enough load for gasket in the
‘Bolting-up Condition’ and that the bolts be designed to absorb the required ‘Operating
Condition’, sustaining both the hydrostatic end force and maintaining sufficient gasket
pressure to ensure a leak free joint.
Since the gasket’s are to be as custom made from ramgaskets.com the following data
should be used in order to safely bolt the joint for each test cycle.
Gasket Diameter 60.8mm
Gasket Width 10mm
Gasket Thickness 2.8mm
Pressure Factor (m) 1.25
Internal Pressure 7.5 N/mm2
Sa 120 N/mm2
Sb 120 N/mm2
Values for Sa and Sb are taken from Table 3.8.1 in PD5500. The values are for the bolt design
stress for atmospheric temperature and design temperature respectively. Since the
operating temperature of the rig is 25oC then these values were taken as being the same.
The gasket factor m is taken from table 3.8-4 as being rubber with a cotton insert (in order
to take into account the membrane behind the gasket.
In section 3.8.3.2 of the PD5500 code it states that the bolting load should be the greater of
the following:
41
Where,
And,
Thus,
And,
Therefore the value for the required bolt area was taken as being Am1. In order to balance
between safety and economy the bolting up load is averaged out between the calculated
area and the actual bolt area.
For a table of bolt root areas (Table 3.8-2 in PD5500), the bolt M12 x 1.75 was selected. It
would be required to use 8 of these bolts to reach the necessary root bolt area. Thus the
total bolting load was found as follows:
Flange Moments
Flange moments are calculated for both the bolting-up and operating conditions. For these
calculations the Integral method is used throughout. The integral method takes into
account the support from the shell and the stresses in the shell are also evaluated and
compared with the allowable stress. Section 3.8.3.3 of the PD5500 is used for the following
procedure.
Bolting-Up Conditions
The total moment acting on the bolted flange during bolting up conditions can be
calculated from the following:
Operating Conditions
The total moment acting upon the flange from the operating conditions can be found from
the following:
42
Flange Stresses and Stress Limits
Flange stresses and stress limits are calculated from Section 3.8.3.4. As with the flange
moments the integral method was used to find the stresses. The three stresses that are
used to evaluate a bolted flange are the longitudinal, radial and tangential.
Bolting Up Conditions
Flange stresses shall be determined from the moment, M, as follows where:
Where CF is the bolt pitch correction factor:
√
In this scenario the value of CF was taken as 1 as PD5500 says if CF<1 then it should be taken
as 1. Therefore:
With the Moment found the three stresses can then be calculated.
Longitudinal:
Radial:
Tangential:
Operating Conditions
Flange stresses shall be determined from the moment, M, as follows where:
Where CF is the bolt pitch correction factor:
√
In this scenario the value of CF was taken as 1 as PD5500 says if CF<1 then it should be taken
as 1. Therefore:
43
With the Moment found the three stresses can then be calculated.
Longitudinal:
Radial:
Tangential:
Allowable Stress
Section 3.8.3.4.2 of the PD5500 code states that the following conditions should be met in
order for the flange to be adequately safe at both operating and bolting-up conditions:
And,
For this flange, the operating temperature is the same as the atmospheric temperature and
all the materials are the same throughout. Therefore it can be said that:
And,
It can be seen that all the stresses are within the allowable limits and thus the bolted flange
is safely designed.
Nomenclature and Corresponding Tables and Figures
Nomenclature
Section
P Design Pressure 7.5 N/mm2 (75 Bar)
Design Temperature 25oC
σy50 Material Yield Point @50oC 275.79 N/mm2
ρ Density of Steel 7860 Kg/m3
44
E Young’s Modulus 188,000 N/mm2
Di Inner Diameter of Cylinder 50.8mm
Feed Pipe Opening 12.7mm
f50 Design Stress @50oC Calculated from the Material Yield Point
es The analysis thickness of the shell plate
he The internal depth of a dished head
ed The analysis thickness of the dished end
Section
Deff The effective mean sphere diameter
eps The required unreinforced shell thickness for pressure loading only
ers The minimum reinforced thickness of the shell as required
Greater than eps
epb The required unreinforced nozzle thickness for pressure loading only
erb The minimum reinforced thickness of nozzle as required
Greater than erb
ρ A non-dimensional parameter as defined in 3.5.4.3
√
d The mean of the inside and outside diameter of the nozzle, or the bore of an opening not provided with a nozzle
13.7mm
D The mean diameter of the spherical section of the shell
93.44mm
C A factor that takes into account
45
external loads
Section
G Gasket Diameter 60.8mm
b Gasket Width 10mm
y Gasket Thickness 2.8mm
m Pressure Factor 1.25 (Table 3.8-4)
P Internal Pressure 7.5 N/mm2 (75 Bar)
Sa The bolt design stress at atmospheric temperature
120 N/mm2 (Table 3.8-1)
Sb The bolt design stress at design temperature
120 N/mm2 (Table 3.8-1)
Wm1 The minimum required bolt load for operating conditions
Wm2 The minimum required bolt load for gasket sealing
Am1 The total required cross-sectional area of bolts required for operating conditions
Am2 The total cross-sectional area of bolts required for gasket sealing
W The flange design bolt load
Ab The actual total cross-sectional area of bolts at the section of least diameter under load
(Table 3.8-2)
Section
G Gasket Diameter 60.8mm
C Bolt Circle Diameter 100mm
W Bolting Up load Section
Matm The total moment acting upon the flange for bolting-up condition
46
Mop The total moment acting upon the flange for operating condition
HD The hydrostatic end force applied via shell to the flange
HT The hydrostatic end force due to pressure on flange face
HG The compression load on gasket to ensure tight joint
H The total hydrostatic end force
hD The radial distance from bolt circle to circle on which HD acts
hG The radial distance from gasket load reaction to bolt circle
hT The radial distance from bolt circle to circle on which HT acts
B The inside diameter of the flange 50.8mm
A The outside diameter of the flange 120mm
g1 The analysis thickness of the hub at the back of the flange
6mm
p Design pressure 7.5 N/mm2 (75 Bar)
b The effective gasket width 10mm
f The hub stress correction factor for integral method flange design
Figure 3.8-10
λ Dimensionless Factor [
]
k A design stress factor for narrow-faced gasketted flanges
See 3.8.3.4.2
Y A dimensionless factor See figure 3.8-5
Z A dimensionless factor Figure 3.8-5
T A dimensionless factor Figure 3.8-5
47
e A dimensionless factor
F A factor for the integral method flange design
See Figure 3.8-6
ho √
h The hub length
d A factor for the integral method flange design
U A dimensionless factor Figure 3.8-5
V A factor for the integral method Figure 3.8-7
Cf The bolt pitch correction factor. If calculated value is less than 1, then use 1.
√
t The minimum allowable flange thickness
20mm
Bolt Dia Bolt Diameter Calculated from the bolt root area
m The gasket factor Table 3.8-4
M from Matm Moment on bolting up condition
M from Mop Moment on operating condition
SH The calculated longitudinal stress in the hub
SR The calculated radial stress
ST The calculated tangential stress in the flange
48
SFA The design stress of the material at atmospheric temperature
183.3 N/mm2
SFO The design stress of the flange material at design temperature
183.3 N/mm2
SHA The lower of the design stress hub and shell materials at atmospheric temperature
183.86 N/mm2
SHO The lower of the design stress hub and the shell materials at design temperature
183.86 N/mm2
Graphs and Tables from PD5500
49
50
51
52
53
54
55
The following document is the quote provided by Righton Ltd.
56
M. Drawings and Visuals
Bolted Flange Membrane Holder
Drawings for the membrane holder were developed using the software suite Creo. The
dimensions were assigned partly based on the client’s specifications with the remainder
being assigned and calculated in order to keep the design safe, economic (in terms of the
cost of both material and manufacturing time) and functional.
The design was sketched and rotated about the z axis. Holes for the bolts were placed using
the pattern function and the salt water chamber was excavated. For simplicity and safety
the design was modelled as being symmetric even though there was no pressure located
on the other side of the membrane. This meant that should any damage be caused the
membrane holder had the required thickness and durability to withstand it.
Bolts were designed as being 60mm long with a 9.85mm diameter and a M12 x 1.75 thread.
Figure # shows the exploded view of the membrane holder assembly.
57
58
59
NPT Threading and Hydraulic Seal
Two rough concept drawings were generated using Creo in order to gain a better visual of
the two ideas. Both operated with the same dimensions with the only difference being that
the NPT had a thread locking mechanism on two surfaces and the hydraulic seal did not.
Figure # shows the rough concept for the design.
60
N. Costing
Costs are summarised into each section as discussed above. There is one quotation for a
system that requires one test and another for one which has multiple tests; this is
estimation for 6 membrane tests.
All costs were updated on the 17/03/2014 and may vary.
Costs for Single Membrane Test Rig
Equipment Description Quantity Unit Cost (£)
Total Cost (No-VAT) (£)
Water Tank
20L Carboy 1 93.33 93.33
Carriage Free
Total 93.33
Heating Element
Titanium aquarium fish tank heater 300W 1 24.99 24.99
Carriage Free
Total 24.99
Pump
Hydra-cell sealless diaphragm metering pump 1 8038.00 8038.00
Pressure Relief Valve 1 2238.00 2238.00
0.75 kW Inverter motor 1 424.00 424.00
Carriage Free
Total 10700.00
Pipe Selection
Enerpac Safety Hose 0.6mtr 8 40.50 324.00
Enerpac Safety Hose 0.9mtr 2 48.60 97.20
Enerpac Safety Hose 1.8mtr 2 59.40 118.80
Enerpac 3/8" NPT Male x Female swivel fitting 3 54.00 162.00
61
Enerpac Reducer 3/8 “ to 1/4” 1 5.48 5.48
Enerpac Adaptor 2 10.96 21.92
Enerpac Reducing Adaptor 1/2 npt-3/8npt F/F 1 24.67 24.67
Enerpac Gauge Swivel Adaptor 1 67.50 67.50
Enerpac Adaptor 3/8" NPT Street Tee 2 42.30 84.60
Enerpac 3/8" NPT Speed control / Shut off Valve 3 85.50 256.50
Carriage 1 16.00 16.00
Total 1178.67
Pressure Gauge
50mm, 70 bar Pressure Gauge 1 16.00 16.00
Calibration Certificate (Not Essential) 1 32.00 32.00
Carriage 15.00 15.00
Total 63.00
Collection Tank
500ml Measuring cylinder 1 18.30 18.30
Carriage Free
Total 18.30
Test Rig Support
Miscellaneous Materials 1 250.00 250.00
Total 250.00
Membrane Holder
Billets 1 80.00 80.00
Carriage 15.00 15.00
Total 95.00
Technician Costs (May vary – Discuss with Chris Cameron before proceeding)(NO VAT)
Manufacturing of Membrane Holder 40 hours 17.00 680.00
62
Manufacturing of Test Rig Support 8 hours 17.00 136.00
Construction of Test Rig 8 hours 17.00 136.00
Pressure Testing 16 hours 17.00 272.00
Total 1224.00
Total Excluding VAT 13647.29
Total Including 20% VAT 16131.95
Cost for Multiple Membrane Test (6 membranes)
Equipment Description Quantity Unit Cost (£)
Total Cost (No-VAT) (£)
Water Tank
20L Carboy 1 93.33 93.33
Carriage Free
Total 93.33
Heating Element
Titanium aquarium fish tank heater 300W 1 24.99 24.99
Carriage Free
Total 24.99
Pump
Hydra-cell sealless diaphragm metering pump 1 8038.00 8038.00
Pressure Relief Valve 1 2238.00 2238.00
0.75 kW Inverter motor 1 424.00 424.00
Carriage Free
Total 10700.00
Pipe Selection
Enerpac Safety Hose 0.6mtr 44 40.50 1782.00
63
Enerpac Safety Hose 0.9mtr 12 48.60 583.20
Enerpac Safety Hose 1.8mtr 7 59.40 415.80
Enerpac 3/8" NPT Male x Female swivel fitting 13 54.00 702.00
Enerpac Reducer 3/8 “ to 1/4” 6 5.48 32.88
Enerpac Adaptor 12 10.96 131.52
Enerpac Reducing Adaptor 1/2 npt-3/8npt F/F 6 24.67 148.02
Enerpac Gauge Swivel Adaptor 6 67.50 405.00
Enerpac Adaptor 3/8" NPT Street Tee 12 42.30 507.60
Enerpac 3/8" NPT Speed control / Shut off Valve 18 85.50 1539.00
Enerpac 7 port manifold 1 115.20 115.20
Carriage 1 16.00 16.00
Total 6378.22
Pressure Gauge
50mm, 70 bar Pressure Gauge 6 16.00 96.00
Calibration Certificate (Not Essential) 1 32.00 32.00
Carriage 15.00 15.00
Total 143.00
Collection Tank
500ml Measuring cylinder 6 18.30 109.80
Carriage Free
Total 109.80
Test Rig Support
Miscellaneous Materials 1 250.00 250.00
Total 250.00
Membrane Holder
Billets 6 80.00 480.00
64
Carriage 15.00 15.00
Total 495.00
Technician Costs (May vary – Discuss with Chris Cameron before proceeding)(NO VAT)
Manufacturing of Membrane Holder 120 hrs. 17.00 2040.00
Manufacturing of Test Rig Support 8 hours 17.00 136.00
Construction of Test Rig 8 hours 17.00 136.00
Pressure Testing 16 hours 17.00 272.00
Total 2584.00
Total Excluding VAT 20778.34
Total Including 20% VAT 24417.21
65
O. Construction Schedule