Report of vocational training

Melamine Plant - 1 & 2

TO : Training Institute, GSFC. Prepared by : Himalaya Savalia

Kandarp PanchalVishwa Patel

Students From

Institute Of Infrastructure, Technology, Research And Management ( IITRAM )

Ahmedabad

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COMPANY PROFILE

GSFC is Gujarat State Fertilizers and Chemicals Ltd. A joint sector industrial complex of Gujarat situated at Baroda. Which was started on 15 th Feb. 1962.The Company’s annual turnover is around Rs 3000 Crores and its employees are over 10,000.In 1967 & today GSFC is multi Location, M0ulti plant, Multi service, with Multi products company with turnover approx 2220 Crores.

GSFC is one of the largest fertilizers and petrochemicals complex in India. having various plants of different technologies. It would have been difficult to keep pace with changing business environment with old plants of GSFC.

GSFCL is certified for the ISO - 9001 Quality Management System.ISO – 14001 Environment Management System and also ISO – 18001 OHSAS (Occupational Health and Safety Assessment Series).

Diversification has been a challenge that GSFC has been meeting with remarkable success, ever since its inception in the early 60’s. The fruitful result of this philosophy has been the establishment of the only Caprolactum (CH2)5CONH plant in India and entry into the field of plastics, Melamine resins and styrene Acronytrile Copolymer, Methacrylate sheets, Polymethyle Methacrylate pellets, etc. GSFC has also installed facilities for the production of Argon Gas, Methane and O2 gas.

Pioneering Landmarks & Achievements: - 1st joint Sector industrial Complex in India 1st adopter Steam Naptha Reforming process for Mfg. Ammonia, DAP Develop and use of Phosphate Gypsum for Mfg. Ammonium Sulphate. Set up plants for Caprolactum, Melamine and O2 in the country. Treating facilities for removal of phosphate and fluorides from liquid

effluent. Setup styrene Acronytrile mfg.

GSFC - A symbol of culture, heritage & development with its depp strong roots & well defined branches to serve the mother land better.

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PLANTS IN GSFC

1) AMMONIA (NH3) PLANTS AND STORAGE FACILITIES :APPLICATION :

Used as nitrogenous fertilizers. Used as raw material for various chemical dyes and pharmaceuticals.

2) UREA (NH2 CO NH2) PLANTS :APPLICATION :

Used as nitrogenous fertilizers. In processing of cotton and textile mills also for chemicals products.

3) MELAMINE (C3H6H6) PLANTS :APPLICATION :

Used as LAMINATES (kitchen shelves, platforms, instrument panels) Consumer Moulded Goods (Crockery, Cutlery, Buttons) Industrial Moulded Goods

4) SULPHURIC ACID (H2SO4) PLANTS :APPLICATION :

Used In Various Field Like Fertilizers, Rayon, Steel Ind., Refineries, Petrochemical, Paints, Textiles Detergents, Lab Etc.

5) PHOSPHORIC ACID PLANTS :APPLICATION :

Used In Lime Ind. Detergent Ind. Agricultural Product

6) DI AMMONIUM PHOSPHATE ((NH4)2 HPO4)) PLANTS :APPLICATION :

Used As Complex Fertilizer For Supply of N and P nutrients

7) CAPROLACTUM PLANTS :APPLICATION :

Used as base material for Nylon 6

8) METHYL ETHYL KETOXIME PLANTS :APPLICATION :

MEK Oxime is an essential additive for the plant varnish and printing in ind.

It is an ideal anti skinning Agent.

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9) NYLON PLANTS :APPLICATION :

Used as precision engineering components. Components for Defense and Automobiles. Packing of food, stuffs

vegetable oils.

10) CO GENERATION PLANTS :APPLICATION :

Generation of Steam and Power for all processing Plants in GSFC.

11) WATER TREATMENT PLANT :APPLICATION :

For Dematerializing and Polishing Water And Feed Water

12) INERT GAS PLANT :APPLICATION :

For Desulfurication and Purification of Gas

13) EFFLUENT TREATMENT PLANT :APPLICATION :

Used for Oil Removal and Equalization Treatment

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Melamine Plant

DETAILS OF GSFC MELAMINE PLANTS

Process Know-How : M/S AGRO LINZ, Austria Commissioning year : Mel-I : 1982 Mel-II : 1997 Capacity : Mel-I : 5000 MTPY

Mel-II : 10000 MTPYRaw Material : Molten Urea (through pipe line from

urea plant)By-product : Ammonia (through pipe line to

GSFC

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Types Of Machinary :

STATIC ROTARY

TanksHeat Exchangers

Air receiversScrubbersVenturies

Towers & ColumnsPiping

Compressors: Centrifugal & ReciprocatingPumps: Centrifugal & Reciprocating

Cooling Tower Fans & BlowersRotary Drum Filter

Rotary DryerScrew Conveyors & Bucket Elevator

Grinding MachineryAir Conditioning Units

CentrifugesAgitators

Process :

Process Steps :- 1) Urea Decomposition2) Melamine Synthesis3) Melamine Scrubbing4) Filtration & Drying5) Off Gas Treatment & Ammonia Recovery6) AC Liquor Treatment 7) Mother Liquor Treatment 8) Ammonia Reliquification9) Process Condensate System10) Bagging Of Product11) Steam & Condensate System

Section wise Process Description :-

1) Urea Decomposition:- Molten Urea from either of urea plants at 135° C and 6-8 kg/cm 2g.

Pressure is injected in the hot fluidized sand bed by means of 2 phase injector (molten urea and hot ammonia gas). The fluidized condition of sand bed is maintained by preheated ammonia gas in the urea decomposer. Decomposition of urea into isocyanic acid and NH3 is the endothermic reaction the decomposition of molten salt through. Heating coils in decomposer and temperature is maintained at about 360-375°C.

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2) Melamine Synthesis:- Mixture of Isocyanic acid & Ammonia which is formed in Urea

decomposer enters into contact furnace. Having 4 beds of catalyst . here the isocyanic acid is converted into melamine and CO2 with conversion efficiency of 90 to 95%. The operating temperature is maintained between 375 to 380°C. the conversion of isocyanic acid into melamine is exothermic reaction. The diphyl tubes are embedded in all the 4 catalyst beds & diphyl in circulation gets heated from controlling contact furnace bed temperature. Heated diphyl is used for preheating. Ammonia used for fluidization of sand in decomposer. Thus proper heat recovery and temperature of reaction is maintained.

3) Melamine Scrubbing :- Melamine vapour along with NH3 &CO2 coming from contact furnace

are quenched and washed out of the gas stream in the Main Scrubber by dilute Ammonium Carbonate Liquor ((NH4)2CO2) and Mother Liquor melamine crystals from suspension in the ammonium carbonate liquor scrubbing liquid circulation is taken out as melamine suspension which is collected in suspension tank for production of melamine. The gases from the main scrubber are scrubbed once again in the Venturi Scrubber for final melamine recovery from the system. Melamine suspension is collected in Crystallisation tank for filtration of melamine from melamine suspension.

4) Filtration & Drying:-

Filtration :-Filtration is again divided into 4 different zones. The filtration equipment used is Centrifugal Filter i.e. the filtration is done by developing centrifugal force. The 4 different zones of filtration are as follows:- i) Filtration

ii) Washing iii) Pilling

Drying :-

Melamine is dried in Rotary Drier which is having 2 zones :i) Dryingii)Cooling Filter

i) Drying Zone:- 13.0kg/cm2g pressure steam is circulated in the steam coils for indirect drying melamine coming from the pressure filter.

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ii) Cooling Filter:- Dried powder of melamine is cooled by circulating cold DM(De-Mineralized) water of the drier for cooling melamine to almost ambient temperature dried melamine powder passes through milling unit consisting of Hammer Mill, Rotary Valves & Pin Disc Mill for crushing of big lumps and to maintain proper grain size powdered melamine is conveyed through Screw Conveyor and Bucket Elevator to Bunker for bagging as final product.

1)2)3)4)5)

a.5) Off Gas Treatment & Ammonia Recovery :-

After scrubbing melamine vapour in the main scrubber and venturi scrubber the gaseous stream is fed to the lower part of Ammonium Carbonate Column-I (AC-I). Together with vapour from mother liquor stripper. Here water vapour gets condensed and NH3 & CO2 gets dissolved in the H2O. upper part of AC-I is designed to expel excess NH3 for minimizing the load onNH3 Stripper for stripping out NH3 & CO2. In AC-II mixture of NH3 & CO2 from AC-I is further absorbed. The unabsorbed excess NH3 is taken out of AC-II and is recirculated through centrifuged. Compressor part of it is taken out for liquefaction.

6) AC Liquor Treatment (Ammonium Carbonate) :- AC Liquor from AC-I top is fed to NH3 Stripper to remove excess

NH3. NH3 stripper is a valve tray type column where NH3 is stripped out by heating it in Reboiler. AC liquor from NH3 stripper is fed to lower part of the CO2 Stripper. CO2 stripper operates at 20kg/cm2g pressure. The upper part of the column expels CO2 which is washed through cooled condensate and becomes free from NH3. Bottom product of CO2 stripper is divided in 2 parts. The major part is recycled to AC-II and rest to CO2. NH3 & CO2 stripper for stripping of NH3 & CO2. (NH4)2CO3 stripper and scrubbed water from washing column as well as vapour condensate from NH3 stripper reboiler for stripping of NH3 & CO2. NH3 & CO2 discharged on the top of total stripper and again recycled to AC-I for Absorption. Bottom condensate having maximum 300ppm of NH3 is feed to process condensate tank for using it in the process.

7) Mother Liquor Treatment:-

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Part of the Mother Liquor coming from Centrifuge Filter is fed to upper part of Mother Liquor Stripper. NH3 & CO2 are expelled from the solution which gets discharged on the top and are recycled to AC-I. in the lower part of the column mother liquor is evaporated for increasing melamine concentration & also urea gets hydrolyzed. Concentrated mother liquor is fed to Crystallization Tank which is further cooled in the suspension cooler and fed to the Centrifuge Filter for filtration of Off gases and specially melamine. The wet melamine is collected separately which is about 2% of total plant capacity. Mother liquor is again fed to mother liquor stripper for further hydrolysis of urea in the mother liquor stripper.

8) NH3 Re-Liquefication:- The NH3 produced during melamine synthesis is compressed

through reciprocating ammonia compressor to 17 kg/cm2g. Pressure and Compressed NH3 condenses with the help of cooling water in the condenser. The liquid NH3 produced is stored in liquid NH3 tank & from thereon it is sent to NH3 Plant.

9) Process Condensate System: Sump product of NH3 & CO2 Stripper(Total Stripper) enters into

process condensate tank from where condensate is pumped to cartridge filters & condensate cooler. After cooling process condensate pump to CO2 Stripper top for absorption.

10) Bagging Unit:- Bagging Unit of Melamine Plant consists of 2 Bunkers, Screw

Conveyors, Rotary Valves, Intermediate Bunkers, Air Blower, One Belt Conveyor & Bagging Machine. The capacity of each Bunker is about 60 MT each for holding the melamine product. The final melamine product is bagged in 4 ply valve type paper bags. The net weight of each melamine filled bag is 25kg. The bags are stacked on wooden pallets – one wooden pallet consists of 40 bags of 25kg each. (Net 1.00 MT)

11) Steam & Condensate System:- Melamine plant receives 35.0kg/cm2g steam from utility plant. The

35.0kg/cm2g steam is further stepped down to 13.0kg/cm2g. In which 6.0kg/cm2g and 3.0kg/cm2g pressure in the plant. Condensate from various steam consumers in the plant is collected in the Flash Drums for producing flashed steam, which is used in the plant and excess is exported to other plants.

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Properties Of Different Liquids And Gases Used In Process :-

1) Natural Gas : - Material Name : Natural Gas Mfg’s Name : ONGC Flammable Gas: 80% Methane Physical State : Gas Odour & Appearance: Odourless Boiling Point : -161.5°C Freezing Point: -183.2°C

2) Melamine : - Material Name : Melamine Mfg’s Name : GSFC Chemical Identity : Colorless, Prisms, Fine White Crystal

Powder Trade Name: Aero Cynuramide, Cynuretriamide, Cymel, Tri-

amino-Tri-azine Product Use : Raw Material for the mfg. of laminates,

crockeries and domestic appliances. Approx. Concentration : Min. 98% Physical State : Solid Boiling Point (°C) : Sublimes Freezing Point (°C) : <350°C pH : 7.5 Means of Extinction : Water FOG Hazardous Products of Combustion : Releases NOx and CN- Chemical Stability : Yes, stable under normal conditions Incompatibility to Other Substances : Yes, avoid contact with

Strong Acids Hazardous Products of /Decomposition : When heated to

decomposition it emits toxic fumes of NOx and CN-, CO & CO2

Eye Contact Ingestion : Skin Contact, Eye Contact Ingestion, Inhalation-Chronic

Engg. Controls : Pneumatic Fillings during bagging operation, Mechanical Ventilation, Local Exhaust Ventilation.

Storage Requirements : Stored on Wooden Pallets in a cool, well ventilated area.

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3) NH3 (AMMONIA) :-

Physical State: Gas Odour & Appearance: Extremely Pungent Boiling Point(°C)- -33.4°C Freezing Point: -77.7°C Solubility in Water (20°C) : Very soluble in Water pH: Alkaline Density (gm/ml): 0.771 Flammability: Yes, when exposed to heat or flame

moderate explosion when exposed to flame or fire Ammonia + Air in fire can detonate.

Means of Extinction: Water, foam, DCP, CO2. Auto Ignition Temp. (°C): 651 Hazardous Products of Combustion: Toxic, Ammonia and

Nox Incompatibility to Other Substances: Yes, Mercury,

Chlorine, Iodine, Bromine, Calcium, Silver Oxide or Hydrochloride can form explosive mixtures.

Hazardous Products of Decomposition: Toxic Nox Fumes. Eye Contact: Skin Contact, Eye Contact Inhalation Storage Requirements: Store in a cool, well ventilated, in

an Isolated Area.

4) Urea :-

Chemical Identity: White Granules Product Used: (i) As Nitrogenous Fertilizers

(ii)For the Manufacture of Melamine Physical State: Solid Boiling Point(°C): Decomposer Freezing Point(°C): 132.7°C pH: Alkaline Flammability: Reacts with Sodium Hydrochlorite, Calcium

Hydrochlorite to form Explosive Nitrogen Trichloride Hazardous Products Of Combustion: Emits Nox Chemical Stability: Yes, stable under normal conditions Incompatibility to Other Substances: Yes, NaNO2, P2Cl5,

Nitrosyl Perchlorate

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Irritancy of Material: Skin Treatment Handling Procedures & Equipments: Bulk material through

belt conveyor5) Carbon Dioxide:

Chemical Stability: Colorless, Odorless Gas Product Use: For the manufacture of Urea, AS, OXO-SYN

Gas and other internal use Physical State: Gas Odour & Appearance: Odourless Boiling Point(°C): Sublimes at -78.5°C Freezing Point(°C): -78.5°C pH: Acidic Flammability: Non-Flammable Chemical Stability: Yes, stable under normal conditions Irritancy of Material: Eye Irritant Storage Requirements: No storage as this material is an

intermediate product

6) Diphyl:

Chemical Identity: Colorless, Sweet, Odourless Liquid Physical State: Liquid Odour & Appearance: Sweet Boiling Point(°C): 257 Freezing Point(°C): 28 Flammability: Yes Auto Ignition Temp. (°C): 620 Chemical Stability: Yes, stable under normal conditions Hazardous Products of Decomposition: Emits Acrid

Fumes& Irritant Fumes when add Water to Decomposition Storage Requirements: In a Storage Tank and keep in a

Coolwell Ventilated Area

Reactions :

a) Decomposition of Urea :-

350°C NH2CONH2 → HNCO + NH3

135° C 350° C 350° C Liquid Urea Gas Isocyanic Gas Ammonia Acid

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H = +701.5 kcal/kg urea Yield = 100%

Part of the isocyanic acid (HNCO) reacts with NH3 to form dicyanide.

HNCO + NH3 → NH=C=NH + H2OIsocyanic Ammonia DicyanideThe remaining isocyanic acid reacts with water to produce NH3 & CO2.

HNCO + H2O → NH3 + CO2

Isocyanic Acid The dicyanide is unsafe and changes to cyamide.

NH=C=NH → N=C-NH2

Dicyanide Cyamide

b) Synthesis of Melamine :-

Al2O3

6HNCO → C3H6N6 + 3CO2

350°C 380°C 380°C Gas Gas GasIsocyanic Acid Melamine

H = -703.9 kcal/kg melamineYield = 92%

c) Cyamide in the presence of catalyst trimorises to melamine :- 400°C

3N=C-NH2 → C3H6N6

Cyamide Melamine

Isocyanic Acid tries to convert into Cyanuric Acid.

HNCO → HOCN

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Isocyanic CyanoricAcid Acid3HOCN + 3NH3 → C3H6N6+ 3H20Cyanuric Acid Ammonia Melamine

d) Urea Hydrolysis :-

NH2CONH2 + H2O → 2NH3 + CO2

120°C 120°C 120°C 120°C Soluted Urea Liquid Water Gas Carbon Dioxde Ammonia H = +500.0kcal/kg urea

a)b)c)

e) Sublimation of melamine :- 380°C

C3H6N6 → C3H6N6

Melamine Gas Melamine SolidH = +233.6 kcal/kg melamine

a)b)c)d)

f) Decomposition of Ammonia :- NH3 → NH3 + Aqueous LiquidLiquid Gas

H = +470.6 kcal/kg ammonia

g) Formation of Ammonium Carbonate :- 2NH3 + CO2 + H2O → (NH4) 2CO2

Gas Gas Liquid Aqueous H = -423.6kcal/kg A

h) Reaction on Heating of Melamine :-

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2C3H6N6 → C6H9N11 + NH3

Melamine Melon Ammonia 2C3H6N6 → C6H6N10 + NH3

Melamine Melem Ammonia 2C3H6N6 → C6H3N9 + 3NH3

Melamine Melon Ammonia Yellow

i) Hydrolysis of Melamine :- C3H6N6 + H2O → C3N5H5O + NH3

Melamine Ammeline Ammonia

C3H6N6 + 2H2O → C3H4N4O2 + 2NH3

Melamine Ammelide Ammonia White

Different processes for Mfg. of Melamine from Urea: 1) High Pressure Non-Catalytic Process2) Medium Pressure Catalytic Process

3) Low Pressure Catalytic Process

1) High Pressure Non-Catalytic Process:- Molten urea is heated to about 380-400°C under press of 70-100

Kg/cm2 in an autoclave where synthesis of melamine takes place in liquid phase without catalyst. The reaction product of autoclave are further processed to separate.

2) Medium Pressure Catalytic Process:- Molten Urea is injected into a fluidized bed reactor at 380-400°C

temp. & 7Kg/cm2 pressure. The Urea Decomposes in to a gaseous Isocynic Acid which converts in to melamine in presence of catalyst. The melamine vapour, NH3 & Co2 gases from the reactor are quenched to condense Melamine.

3) Low Pressure Catalytic Process:- Urea decomposition and Melamine synthesis are carried out in

the 2 stage. The temp. & press. are 350-390°C and slightly above atmosphere pressure.

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An Chemie Linz process is low pressure catalytic process and hence due to low energy consumption, GSFC has selected this process.

Advantages of Chemie Linz Process:- Urea decomposition & Melamine synthesis in two stages at optimum

conditions for less by products formation. No catalyst loss only makeup during turnaround required for breakage. Product recrystalisation is not necessary. Less corrosion of vessels. Recovery of pure NH3 & Co2 products and hence processing of OFF gases

in other plant is not required.

General Characteristics:- Melamine is white substance & its specific gravity is 1.574 gm/cc. It is

slightly soluble in cold water & soluble in cold water & soluble up to 5% in hot water. The solution is weakly basic & forms salts which can be readily isolated. It has high melting point (554°C) but sublimation begins at temp. below melting point. Thus purification by sublimation is possible.

Melamine is hydrolysed on prolonged boiling with aqueous alkali to give ammeline. Hydrolsis with boiling dilute mineral converts it to ammilide and cyanuric. On heating strongly, it melts and decomposes with loss of NH3.

Overall Reaction :

6NH2CONH2 → C3H6N6 + 3NH2 + 3CO2

135°C 390°C 390°C

Urea Melamine Ammonia

When molten Urea is heated to about 360-370°C in pressure of quartz sand urea decomposes to iscyanic acid and ammonia. Further isocyanic acid is converted in to melamine in the presence of aluumina catalyst and carbon dioxide is produced as byproduct.

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Detail description of Equipments :

1. Pumps :- Type of Pumps :-

Centrifugal Pumps (Melamine-I&II) High pressure multistage centrifugal pump (Melamine-I) High pressure multistage centrifugal pump with G.B. (Melamine-II) Vertical centrifugal pump (salt pump)(Mel-I_II) Cooling tower pump (Mel-I&II) Reciprocating pump (plunger) (Mel- I&II)

Mechanical pumps may be submerged in the fluid they are pumping or be placed external to the fluid. Pumps can be classified by their method of displacement into positive displacement pumps, impulse pumps, velocity pumps, gravity pumps, steam pumps and valveless pumps. There are two basic types of pumps: positive displacement and centrifugal.

PrincipleIt converts kinetic energy to pressure energy (Only for non compressible media liquid) for delivery of liquid at particular height.

Application Melamine suspension Ac liquor Mother liquor Cooling water Drinking water Process condensate

2. Compressor :- A gas compressor is a mechanical device that increases the pressure of a gas by reducing its volume. An air compressor is a specific type of gas compressor.

Reciprocating (IR) compressor (Mel-I&II) Centrifugal compressor (Mel-I&II) Service Air compressor-Chicago (Mel-II) Service Air compressor-Khosla (Mel-II) Mini IR compressor-2stage single acting (Mel-I) Mini IR compressor-3stage single acting (Mel-II)

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PrincipleIt compresses a compressible media.

Application For service air Ammonia gas

3. Blower :- Centrifuge blower (Me-I&II) Lobe blower (Me-I&II)

Principle To through air, vapour, gas.

Application Air/ammonia gas

4. Reactor :- Urea compressor (Mel-I&II) Contact furnace (Mel-I&II)

Principle Chemical reaction

Application Sand bed reaction -Endothermic reaction Catalyst bed reaction- Exothermic reaction

5. Cooling Tower :- Principle

To cooled water & supplied it at various equipment.

Application

Service water

6. Heat exchanger :- A heat exchanger is a piece of equipment built for efficient heat transfer from one medium to another. Shell & tube type (Mel-I&II)

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Plate type (Mel-I&II) Fins tube type (Mel-I&II)

Principle It exchanges heat & to reduce temp.

Application Steam, mother liquorAc liquor, DM water

7. Conveyor :- Screw conveyor (horizontal) (Mel-I&II) Bucket elevator (vertical) (Mel-I)

Principle To passed material from one place to another place.

Application Melamine power

8. Other equipments :- Gear box> Speed variation Agitator (Mel-I&II) – mixing of any liquid + crystallization Dryer (Mel-I&II) – for drying material Hammer mill –To crush the material & convert into power form Pressure filter (Mel-I) – Separate the mother liquor from melamine & produce

wet cake form. Centrifuge (Mel-II) – same principle as pressure filter

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Pumps

Centrifugal Pumps :- Introduction :

The operating manual of any centrifugal pump often starts with a general statement, “Your centrifugal pump will give you completely trouble free and satisfactory service only on the condition that it is installed and operated with due care and is properly maintained.”

Despite all the care in operation and maintenance, engineers often face the statement“the pump has failed i.e. it can no longer be kept in service”.

Inability to deliver the desired :

Flow and head is just one of the most common conditions for taking a pump out of service.

There are other many conditions in which a pump, despite suffering no loss in flow or head, is considered to have failed and has to be pulled out of service as soon as possible. These include seal related problems (leakages, loss of flushing, cooling,

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PUMPS

quenching systems, etc), pump and motor bearings related problems (loss of lubrication, cooling, contamination of oil, abnormal noise, etc), leakages from pump casing, very high noise and vibration levels, or driver (motor or turbine) related problems.

The list of pump failure conditions mentioned above is neither exhaustive nor are the conditions mutually exclusive. Often the root causes of failure are the same but the symptoms are different. A little care when first symptoms of a problem appear can save the pumps from permanent failures. Thus the most important task in such situations is to find out whether the pump has failed mechanically or if there is some process deficiency, or both. Many times when the pumps are sent to the workshop, the maintenance people do not find anything wrong on disassembling it. Thus the decision to pull a pump out of service for maintenance / repair should be made after a detailed analysis of the symptoms and root causes of the pump failure. Also, in case of any mechanical failure or physical damage of pump internals, the operating engineer should be able to relate the failure to the process unit’s operating problems.

Any operating engineer, who typically has a chemical engineering background andwho desires to protect his pumps from frequent failures must develop not only a good understanding of the process but also thorough knowledge of the mechanics of the pump.

Effective troubleshooting requires an ability to observe changes in performance over time, and in the event of a failure, the capacity to thoroughly investigate the cause of the failure and take measures to prevent the problem from re-occurring.

The fact of the matter is that there are three types of problems mostly encounter with centrifugal pumps:

design errors poor operation poor maintenance practice

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Working Mechanism of a Centrifugal Pump :

A centrifugal pump is one of the simplest pieces of equipment in any process plant. Its purpose is to convert energy of a prime mover (a electric motor or turbine) first into velocity or kinetic energy and then into pressure energy of a fluid that is being

pumped. The energy changes occur by virtue of two main parts of the pump, the impeller and the volute or diffuser. The impeller is the rotating part that converts driver energy intothe kinetic energy. The volute or diffuser is the stationary part that converts the kinetic energy into pressure energy.

Generation of Centrifugal Force :

The process liquid enters the suction nozzle and then into eye (center) of a revolving device known as an impeller. When the impeller rotates, it spins the liquid sitting in the cavities between the vanes outward and provides centrifugal acceleration.

A liquid leaves the eye of the impeller. A low-pressure area is created causing more liquid to flow toward the inlet. Because the impeller blades are curved, the fluid is pushed in tangential and radial direction by the centrifugal force. This force acting inside the pump is the same one that keeps water inside a bucket that is rotating at the end of a string.

Figure A.01 below depicts a side cross-section of a centrifugal pump indicating the movement of the liquid.

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CF PUMPFLOWRADIALAXIALMIXEDSUCTIONSINGLEDOUBLESPLITRADIALAXIALSTAGESINGLEMULTIIMPELLERCLOSEDSEMI-OPENOPEN

General Components of Centrifugal Pump :

A centrifugal pump has two main components:

I. A rotating component comprised of an impeller and a shaftII. A stationary component comprised of a casing, casing cover, and bearings.The general components, both stationary and rotary, are depicted in Figure.The main components are discussed in brief below. Figure shows these parts on a photograph of a pump in the field.

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Stationary Components :A. Casing :

Casings are generally of two types: volute and circular. The impellers are fitted inside the casings.

1. Volute casings build a higher head; circular casings are used for low head and high capacity.o A volute is a curved funnel increasing in area to the discharge port as shown in Figure. As the area of the cross-section increases, the volute reduces the speed of the liquid and increases the pressure of the liquid.

One of the main purposes of a volute casing is to help balance the hydraulic pressure on the shaft of the pump. However, this occurs best at the manufacturer's recommended capacity. Running volute-style pumps at a lower capacity than the manufacturer

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recommends can put lateral stress on the shaft of the pump, increasing wear-and-tear on the seals and bearings, and on the shaft itself. Double-volute casings are used when the radial thrusts become significant at reduced capacities.

2. Circular casing have stationary diffusion vanes surrounding the impeller periphery that convert velocity energy to pressure energy. Conventionally, the diffusers are applied to multi-stage pumps.o The casings can be designed either as solid casings or split casings.

Solid casing implies a design in which the entire casing including the discharge nozzle is all contained in one casting or fabricated piece.

Split casing implies two or more parts are fastened together. When the casing parts are divided by horizontal plane, the casing is described as horizontally split or axially split casing. When the split is in a vertical plane perpendicular to the rotation axis, the casing is described as vertically split or radial split casing. Casing Wear rings act as the seal between the casing and the impeller.

B. Seal Chamber and Stuffing Box:

Seal chamber and Stuffing box both refer to a chamber, either integral with or separate from the pump case housing that forms the region between the shaft and casing where sealing media are installed. When the sealing is achieved by means of a mechanical seal, the chamber is commonly referred to as a Seal Chamber.When the sealing is achieved by means of packing, the chamber is referred to as a Stuffing Box. Both the seal chamber and the stuffing box have the primary function of protecting the pump against leakage at the point where the shaft passes out through the pump pressure casing. When the pressure at the bottom of the chamber is below atmospheric, it prevents air leakage into the pump. When the pressure is above atmospheric, the chambers prevent liquid leakage out of the pump. The seal chambers and stuffing boxes are also provided with cooling or heating arrangement for proper temperature control. Figure below depicts an externally mounted seal chamber and its parts.

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Gland: The gland is a very important part of the seal chamber or the stuffing box. It gives the packings or the mechanical seal the desired fit on the shaft sleeve. It can be easily adjusted in axial direction. The gland comprises of the seal flush, quench, cooling, drain, and vent connection ports as per the standard codes like API 682.

Throat Bushing: The bottom or inside end of the chamber is provided with a stationary device called throat bushing that forms a restrictive close clearance around the sleeve (or shaft) between the seal and the impeller.

Throttle bushing refers to a device that forms a restrictive close clearance around the sleeve (or shaft) at the outboard end of a mechanical seal gland.

Internal circulating device refers to device located in the seal chamber to circulate seal chamber fluid through a cooler or barrier/buffer fluid reservoir. Usually it is referred to as a pumping ring.

Mechanical Seal: The features of a mechanical seal will be discussed in Part-II of the article.

C. Bearing housing : The bearing housing encloses the bearings mounted on the shaft. The bearings keep the shaft or rotor in correct alignment with the stationary parts under the action of radial and transverse loads. The bearing house also includes an oil reservoir for lubrication, constant level oiler, jacket for cooling by circulating cooling water.

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Rotating Components :A. Impeller :

The impeller is the main rotating part that provides the centrifugal acceleration to the fluid. They are often classified in many ways. Based on major direction of flow in reference to the axis of rotation

Radial flow Axial flow Mixed flow

Based on suction type :Single-suction: Liquid inlet on one side.Double-suction: Liquid inlet to the impeller symmetrically from both sides. Based on mechanical construction :Closed: Shrouds or sidewall enclosing the vanes.Open: No shrouds or wall to enclose the vanes.Semi-open or vortex type.

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Closed impellers require wear rings and these wear rings present another maintenance problem. Open and semi-open impellers are less likely to clog, but need manual adjustment to the volute or back-plate to get the proper impeller setting and prevent internal re-circulation. Vortex pump impellers are great for solids and "stringy" materials but they are up to 50% less efficient than conventional designs. The number of impellers determines the number of stages of the pump. A single stage pump has one impeller only and is best for low head service. A two-stage pump has two impellers in series for medium head service.

A multi-stage pump has three or more impellers in series for high head service.

Wear rings: Wear ring provides an easily and economically renewable leakage joint between the impeller and the casing. Clearance becomes too large the pump efficiency will be lowered causing heat and vibration problems. Most manufacturers require that you disassemble the pump to check the wear ring clearance and replace the rings when this clearance doubles.

B. Shaft : The basic purpose of a centrifugal pump shaft is to transmit the torques encountered when starting and during operation while supporting the impeller and other rotating parts. It must do this job with a deflection less than the minimum clearance between the rotating and stationary parts.

Shaft : Pump shafts are usually protected from erosion, corrosion, and wear at the seal chambers, leakage joints, internal bearings, and in the waterways by renewable sleeves. Unless otherwise specified, a shaft sleeve of wear, corrosion, and erosion resistant material shall be provided to protect the shaft. The sleeve shall be sealed at one end. The shaft sleeve assembly shall extend beyond the outer face of the seal gland plate. (Leakage between the shaft and the sleeve should not be confused with leakage through the mechanical seal).

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Coupling: Couplings can compensate for axial growth of the shaft and transmit torque to the impeller. Shaft couplings can be broadly classified into two groups: rigid and flexible. Rigid couplings are used in applications where there is absolutely no possibility or room for any misalignment. Flexible shaft couplings are more prone to selection, installation and maintenance errors. Flexible shaft couplings can be divided into two basic groups: elastomeric and non-elastomeric.

Elastomeric couplings use either rubber or polymer elements to achieve flexibility. These elements can either be in shear or in compression. Tire and rubber sleeve designs are elastomer in shear couplings; jaw and pin and bushing designs are elastomer in compression couplings.

Non-elastomeric couplings use metallic elements to obtain flexibility.

These can be one of two types : lubricated or non-lubricated.Lubricated designs accommodate misalignment by the sliding action of their components, hence the need for lubrication. The non-lubricated designs accommodate misalignment through flexing. Gear, grid and chain couplings are examples of non-elastomeric, lubricated couplings. Disc and diaphragm couplings are non-elastomeric and nonlubricated.

Auxiliary Components :Auxiliary components generally include the following piping systems for the followingservices: Seal flushing , cooling , quenching systems Seal drains and vents Bearing lubrication , cooling systems

C. Seal chamber or stuffing box cooling, heating systems:

Pump pedestal cooling systems:

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Auxiliary piping systems include tubing, piping, isolating valves, control valves, relief valves, temperature gauges and thermocouples, pressure gauges, sight flow indicators,orifices, seal flush coolers, dual seal barrier/buffer fluid reservoirs, and all related vent and drains.All auxiliary components shall comply with the requirements as per standard codes likeAPI 610 (refinery services), API 682 (shaft sealing systems) etc.

NPSH: o Net Positive Suction Head Required NPSHro Net Positive Suction Head Available NPSHa

Reciprocating Pump :

Purpose of This Manual:- This article is a note or manual for mechanical engineer where work as rotating engineer or where concern to apply reciprocating pump into the system. Article contain how to select pump, performance analysis, power estimation, NPSH estimation and also to create or complete calculation sheet, datasheet and specification sheet as a part of detail engineering and purchasing activity.

Type and Construction Features of Reciprocating Pump. Type and construction features of reciprocating pump :

1. Position - Vertical - Horizontal 2. Purpose - Metering Pump - Power Pump 3. Piston or Plunger acting : Single acting, Double acting 4. Number of Plunger in

One Casing : Single, Duplex, Triplex, Multiplex 5. Liquid End Type : Direct exposed, Diaphragm 6. Plunger direction : Forward,

Backward.

Components of Reciprocating Pump. Main components of reciprocating pump :- Reduction gear- Coupling - Casing and crankcase- Crankshaft- Connecting Rod - Spacer rod - Plunger - Packing - Check valves - Bearings for crankshaft and connecting rod Following figures show cross sectional drawing for typical of reciprocating pump.

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Operating Range Of Reciprocating Pump:

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Casing Pressure : Up to about 600 kg/cm2 Speed : Low, up to 700 RPM after reducing gear Capacity : Up to about 500 m3/hr. Total head : Up to about 5000 m

LUBRICATION, SEAL OIL AND FLUSHING SYSTEM: Lubrication is required for parts in crankcase to prevent parts from wear. Sealing is required to prevent toxic or harmful liquid for leakage to ambient. Flushing is required to remove crystallized liquid from plunger and packing. For relatively low plunger force and short stroke length, lubrication is oil bath type. Other type is force lubrication. Figure 17 and 18 shows typical forced lubrication, sealing and flushing system.

COMPRESSOR :

CENTRIFUGAL COMPRESSOR :

INTRODUCTION :A compressor is a fluid handling mechanical device capable of efficiently transferring energy to the fluid medium so that it can be delivered in large quantities at elevated pressure conditions. Compressors have numerous applications ranging from aircraft and process industries to household appliances such as refrigerators and air conditioners. There are numerous types of compressors, each suitable for a particular application. Generally, compressors can be categorized under two basic types-positive displacement and dynamic . Positive displacement compressors include piston, screw, vane, and lobe compressors. Axial and centrifugal compressor types are dynamic compressor as the required pressure rise and flow is imparted to the fluid medium by transferring kinetic energy to the process gas. Flowrate, efficiency, and the pressure rise within the compressor are the Positive displacement compressors are generally suitable for small flowrates while centrifugal and axial compressors are more commonly applied for medium and large flow applications respectively.

The advantages of centrifugal compressors are that they are reliable, compact and robust, have better resistance to foreign object damage, and are less affected by performance degradation due to fouling . Above all, as can be seen , they have a wider operating domain when compared to other compressor types.

Centrifugal compressors are most commonly applied in petrochemical or process industries in the flowrates ranging from 1 000 to 1 00,000 ft3/min. Typical centrifugal compressor applications three most important parameters used .

BASIC COMPONENTS AND PRINCIPLES OF OPERATION :

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FRAME HOUSING MAIN BEARING HOUSING OIL PUMP PUG OIL RELIEF VALVE CRANK SHAFT CONNECTING ROD CROSSHEAD DISTANCE PIECE PACKING PARTION HEAD FRAME CYLINDER VALVE PISTON ROD SUPPORT HEAD FRAME BEARINGS

Centrifugal compressors for industrial applications have relatively low pressure ratios per stage. This condition is necessary so that the compressors can have a wide operating range while stress levels are kept at a minimum. Because of the low pressure ratios for each stage, a single machine may have a number of stages in one "barrel" to achieve the desired overall pressure ratio.

RECIPROCATING COMPRESOR :

Components Of Reciprocating Compressor :

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Piston Piston Rod Crosshead Pin Crank Shaft Distance Piece Connecting Rod

Types : Single Stage Multi Cylinder Multi Stage Compressor

Fans & Blower : Introduction :

Fans and blowers provide air for ventilation and industrial process requirements. Fans generate a pressure to move air (or gases) against a resistance caused by ducts, dampers, or other components in a fan system. The fan rotor receives energy from a rotating shaft and transmits it to the air.

Difference between Fans, Blowers and Compressors :

Fans, blowers and compressors are differentiated by the method used to move the air, and by the system pressure they must operate against. As per American Society of Mechanical Engineers (ASME) the specific ratio - the ratio of the discharge pressure over the suction pressure - is used for defining the fans, blowers and compressors.

Fan Types :

Table 5.2 Fan EfficienciesType of fan Peak Efficiency

RangeCentrifugal Fan

Airfoil, backward curved/inclined 79-83Modified radial 72-79

Radial 69-75Pressure blower 58-68Forward curved 60-65

Axial fanVan axial 78-85Tube axial 67-72Propeller 45-50

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Fan and blower selection depends on the volume flow rate, pressure, type of material handled, space limitations, and efficiency. Fan efficiencies differ from design to design and also by types. Typical ranges of fan efficiencies are given in Table 5.2.

Fans fall into two general categories: centrifugal flow and axial flow. In centrifugal flow, airflow changes direction twice - once when entering and second

when leaving (forward curved, backward curved or inclined, radial) In axial flow, air enters and leaves the fan with no change in direction (propeller,

tubeaxial, vaneaxial)

Centrifugal Fans Axial-flow Fans

Type Characteristics Typical Applications Type Characteristics Typical

Applications

Radial

High pressure, medium flow,

efficiency close to tube-axial fans, power

increases continuously

Various industrial

applications, suitable for dust laden,

moist air/gases

Propeller

Low pressure, high flow, low

efficiency, peak efficiency close to point of free

air delivery (zero static pressure)

Air-circulation, ventilation,

exhaust

Forward-curved blades

Medium pressure, high

flow, dip in pressure curve, efficiency higher than radial fans,

power rises continuously

Low pressure HVAC,

packaged units,

suitable for clean and

dust laden air / gases

Tube-axial

Medium pressure, high

flow, higher efficiency than propeller type, dip in pressure-

flow curve before peak

pressure point.

HVAC, drying ovens,

exhaust systems

Backward curved blades

High pressure, high flow, high

efficiency, power reduces

as flow increases

beyond point of highest

efficiency

HVAC, various

industrial applications, forced draft

fans, etc.

Vane-axial

High pressure, medium flow,

dip in pressure-flow curve, use of guide vanes

improves efficiency

High pressure

applications including

HVAC systems, exhausts

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BEARING : Definition A support or guide by means of which a moving part is positioned with respect to other parts of a mechanism.

Function To transmit load and support shaft which rotates, oscillates and / or reciprocates.

Types of bearings - Plain Bearing- Antifriction Bearing

1. Plain Bearings: Types

- Journal Bearings- Thrust Bearings- Guide Bearing

Materials- Babbits - Cu, Sb, Sn, Pb - Copper base- Aluminium Base

Bearing Loads : - Axial Load- Radial load- Dynamic Load- Static Load- Locating bearings- Non Locating bearings

Bearing selection criteria: - Load rating- Direction of load- Speed- Bearing location

Bearing Design : - Tolerance on bearing dimensions- Tolerance on shaft- Tolerance on housing- Chamfer design- Bearing clearance- Type of cage

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Different Bearings: Deep groove ball bearingAngular Contact ball bearingsSelf Aligning ball bearingsCylindrical Roller bearingsNeedle roller bearingsTapered roller bearingsSpherical roller bearing

Bearing accessories: Rolling elements:

- Balls : Hardness HRC 63+ - 3- Rollers : Hardness HRC 58 to 65Balls dia 0.05 to 320 mm

Bearing failures: 1/3 rd - due to ageing1/3rd - due to improper lubrication1/3rd - due to improper design, handlingincorrect mounting

Maintenance of bearings: - Proper fits & tolerances on shaft and housing- Proper dismounting of bearing- Proper mounting of bearing - Lubrication- Inspection and storage- Condition monitoring - Shock pulse, 2 - 50 kHZ - Troubleshooting

Lubrication: - Grease lubrication- Oil lubrication

Properties of lubricant- Viscosity ( mm2/s) - Viscosity Index > 85- Consistency ( NLGI grade)- Film forming abilit- Boundary lubrication- Hydrodynamic lubrication- Elasto-hydrodynamic lubrication

Grease:- Thickener - Ca, Na, Li, bentonite, PTFE, silica gel- Oils - Mineral, synthetic, silicones- Additives - Antirust agents, anti oxidants, EP additives

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VALVE :1) On-Off Service Valve :

Gate ValvePlug Valve Ball ValveButterfly Valve

2) Check Valve :Swing Check ValveBall Check ValveLift Check Valve

3) Flow Control Valve :Niddle ValveAngle ValveAutomatic Flow Control ValveGlobe Valve

4) Pressure Relief Valve

5) Safty Valve

Alignment :Alignment, primarily for rotating machinery is the activity to check that centerlines of two rotating shafts ( of Driver & Driven machine ) are in line i.e. collinear with each other at operating conditions.

Introduction to Shaft Alignment :Shaft misalignment is the deviation of relative shaft position from a collinear axis of rotation measured at the points of power transmission when equipment is running at normal operating condition.

Objectives of Accurate Alignment : Reduce excessive axial and radial forces on the bearings to insure longer bearing life Minimize the amount of shaft bending Minimize the amount of wear in the coupling components Reduce mechanical seal failure Maintain proper internal rotor clearances Eliminate the possibility of shaft failure from cyclic fatigue Lower vibration levels in machine casings, bearing housings, and rotors

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Alignment Techniques : Straight edge & feeler gauge Shaft alignment using dial indicators :

- Face-Rim method~ Two indicator method~ Three indicator method

- Reverse indicator method Laser alignment method

Straight Edge & Feeler Gauge Method :Advantages :

Simplest & cheapest of all methods. Does not require too many tools. Does not require specialized skills

Disadvantages: Least accurate of all methods. Too much Scope for human errors

Face-rim Dial Indicator Method :

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Face-rim Two Dial Indicator Method :

Face-rim Three Dial Indicator Method :

Reverse Indicator Method :

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Laser Alignment :

Symptoms of Misalignment : Premature bearing or Mech. seal failures Excessive radial and axial vibration High casing temperatures at or near the bearings Excessive amount of oil leakage at the bearing seals Loose foundation bolts Loose or broken coupling bolts Unusually high number of coupling failures The shafts are breaking (or cracking) at or close to the inboard bearings or

coupling hubs

CONCLUSION : Precision alignment reduces maintenance cost Aligned equipment run longer & smoother Always align to a known tolerance Don’t skip the pre alignment checks

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