scaleban brochure for thermal power plants
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ABOUT US:
SCALE-BAN EQUIPMENTS PVT. LTD. was established in the year 1996 with its office and
manufacturing setup at Indore, with a vision to providing a non-chemical online solution for the
hard water scaling related problems in heat transfer areas.
Today the company has established itself well in the market and is known for its commitment,
product performance, customer relations, after-sales-service and customised product design for
specific applications.
The manufacturing plant situated at Indore is about 10 km from the city centre and has capacity
to manufacture the product in required sizes and numbers. The production planning is done as
per order position and committed delivery dates to ensure timely delivery as per individual
purchase order.
We manufacture non-chemical water treatment equipment by the name of SCALE-BAN™, which
prevents deposition of hard water scale in the heat transfer area. It can also be installed in the
existing pipe line with absolutely no changes in the piping route and layout.
This On-line equipment does not require any energy input for its operation. It also does not
require any regeneration or maintenance, resulting in zero equipment down time and zero
equipment deterioration.
Our product has been already tested with circulating water having Hardness of 10000 ppm and
TDS count of 40000 ppm. With its ability to successfully operate and perform even at such
extreme parameters, SCALE-BAN™ can save precious water for industries with operation of
cooling tower at higher COC’s. Also due to its unique design, it can work even with RAW WATER
(as makeup water for cooling tower) without its pre-treatment such as softening or addition of
anti scale chemicals.
In addition to excellent water savings, it also offers total prevention of hard water scales in
heat exchangers found in different types of industry.
Having been in market for over a decade, we have developed a vast data base of satisfied clients,
which have been benefitted by achieving substantial operational savings with our proven
technology.
We are awaiting a Patent Number from Office of Controller General of Patents, Designs and
Trademarks (Intellectual Property India), Mumbai, Government of India, pending our application
number 2335/MUM/2009 dated 7th October 2009.
WATER AND ITS PROPERTIES:
Water is nature’s most wonderful, most abundant, and most useful substance. It is estimated
that two-thirds of earth’s surface constitutes of water. It also occupies a unique position in
industries. It plays a very important role as a coolant for steam condensation in thermal power
generation; it is also used as a coolant in process plants. Water is very complex in nature and it
contains a lot of impurities in dissolved and suspended form. Calcium and Magnesium salts
present in water determine the hardness of water and it is this hardness of water, which is the
main cause for HARD WATER SCALE formation in heat exchangers in various industries.
INSULATING PROPERTIES OF HARD WATER SCALE:
Scale formation is a common phenomenon in any industry using water as a coolant OR for steam
generation.
Hard water scale has higher thermal insulating properties, thus resulting in poor heat transfer
efficiencies (see graph below).
Apart from causing this drop in thermal efficiency, it also causes overheating of heat exchange
equipment and results in frequent breakdowns because of equipments chocking. The cleaning
process is recurring and tedious and it also greatly reduces the life of various heat exchangers.
HOW DOES SCALE-BANTM
PREVENT SCALING IN YOUR EQUIPMENT?
THE GALVANIC PRINCIPLE:
The working principle of SCALE-BAN™ is very simple and proven. It incorporates use of the
Galvanic Principle, Chemical Characteristics of water and Fluid Dynamics. SCALE-BAN™ exploits
solubility characteristics of Calcium and Magnesium salts in water with change in its pH value.
SCALE-BAN™ locally increases the pH value of water before it reaches high temperature zone
and then precipitates out hardness causing salts as water flows through SCALE-BAN™.
CHEMICAL CHARACTERISTICS OF WATER:
Effect of rise in temperature of water on solubility of Calcium and Magnesium salts:
As is known, the main cause responsible for formation of scales inside any equipment is the rise
in temperature of water flowing through it, since at higher temperatures, water has a tendency
to precipitate dissolved Calcium and Magnesium salts. A graphic representation of solubility of
these salts in water vis-á-vis its temperature indicates that with the rise in temperature of water
from T1 to T2 the solubility of these salts reduces from S1 to S2.
Thus with higher temperatures of water - as it comes in contact with any heat exchange surface -
Calcium and Magnesium salts precipitate out and form scale on the surface of heat transfer area.
SCALE-BAN™ precipitates out these salts much before the water attains this critical temperature
due to its coming in contact with the heat exchange surface.
Effect of increase in the pH value of water on solubility of Calcium and Magnesium salts:
Similar to its tendency to precipitate out dissolved Calcium and Magnesium salts at higher
temperature, water also tends to precipitate out dissolved Calcium and Magnesium salts at its
higher pH value i.e. when it tends to be slightly alkaline. A graph plotted to illustrate solubility of
Calcium and Magnesium in water vis-á-vis its pH value indicates that with the rise in pH value of
water from P1 to P2 the solubility of these salts reduces from S1 to S2 causing their precipitation at
higher pH values.
SCALE-BAN™ makes use of above principle by locally enhancing the pH value of circulating water
to precipitate these salts before the circulating cooling water actually comes in contact with heat
exchange surface. Consequently, once the precipitation of these hardness causing salts has taken
place, further precipitation due to temperature variation is not possible.
These precipitated salts are in the colloidal form (small particles dispersed in another substance)
and are suspended in water, therefore, because of their very small size (Ø ≈ 0.01µ ~ 0.5µ) and
lighter weight the turbulent water flowing through SCALE-BAN™ carries away these precipitated
salts. THE NET RESULT IS A TOTALLY SCALE FREE SYSTEM.
HOW DOES SCALE-BANTM
EXPLOIT THESE PRINCIPLES AND CHEMICAL
CHARACTERISTICS OF WATER?
THE FUNCTIONING OF SCALE-BANTM
:
As cooling water passes through SCALE-BAN™, and as the circulating cooling water itself acts as
an electrolyte within the equipment, the whole core placed inside the equipment gets negatively
charged. This negatively charged core attracts H+ ions from water, which are the lightest ions.
The relationship between pH of water and H+ ion is expressed by the formula pH α 1/H+
Thus, with the concentration of H+ ion becoming less and less in the circulating cooling water, pH
value of water increases, thereby precipitating Calcium and Magnesium salts; that are
responsible for forming hard water scale on the heat exchange surface within any equipment.
A doubt could arise in the mind regarding formation of scales within SCALE-BANTM
itself due to
adsorption (the adhesion of a thin layer of molecules of some substance to the surface of a solid
or liquid) and that the equipment itself might get chocked after sometime. However, this is not
the case since the geometry of the core is trapezoidal, which creates substantial turbulence in
the water. This turbulence of the water flowing past the SCALE-BANTM
physically cleans the
surface of the core as well as causes pressure variation resulting in low pressure zones being
created downstream of SCALE-BANTM. As the precipitated colloids of are very small in size and
extremely light in weight, the turbulent flow of water carries these away towards low pressure
zone downstream of SCALE-BANTM and the equipment itself remains completely clean forever.
As with any other equipment, SCALE-BANTM
too has its optimal operating range, within which it
performs best. Ideally, the pH value of water should not exceed 8.3 in recirculation and the
minimum flow rate as is applicable for various pipe sizes should be strictly maintained. Minimum
and maximum flow rates corresponding to various pipe sizes are indicated later for ready
reference.
SCALE-BANTM
AND IMPROVEMENT IN POWER GENERATED IN THERMAL POWER
PLANTS DUE ZERO SCALING IN CONDENSER AND BETTER WATER MANAGEMENT
At present 54.09% or 93918.38 MW (Data Source CEA, as on 31/03/2011) of total electricity
production in India is from Coal Based Thermal Power Station.
Advantages of coal based thermal Power Plant:
• They can respond to rapidly changing loads without difficulty
• A portion of the steam generated can be used as a process steam in different industries
• Steam engines and turbines can work under 25 % of overload continuously
Disadvantages of coal based thermal Power Plant:
• A large quantity of water is required
• Operating costs are high
• Unavailability of good quality coal
• Most of the heat energy is lost
Notwithstanding their disadvantages, thermal power plants continue to remain a major source of
electricity supply in India and their population is still increasing. The conventional method of
power generation and supply to the customer is wasteful in the sense that only about a third of
the primary energy fed into the power plant is actually made available to the user in the form of
electricity. In conventional power plant, efficiency is only 35% and remaining 65% of energy is
lost. The major source of loss in the conversion process is the heat rejected to the surrounding
water or air due to the inherent constraints of the different thermodynamic cycles employed in
power generation.
Losses suffered in operating a thermal power plant and typical parameters corresponding to
operation of a 1000 MW thermal power station are indicated in the figures below:
TYPICAL SCHEMATIC OF A THERMAL POWER PLANT WITH EXTRACTION TYPE
SURFACE CONDENSING TURBINE
Operational Efficiency (Plant load Factor):
Operational efficiency is the ratio of the total electricity produced by a plant during a fixed period
of time compared to the total electricity that could have been produced if the plant had
operated at 100 percent capacity in that period.
Operational efficiency ► η(o) is expressed as:
η(o) = (100) E / E100%
where,
η(o) = Operational Efficiency (%)
E = Energy output from the power plant in a particular period (kWh)
E100% = Energy output from the power plant operated at 100% installed capacity in that period
(kWh)
Status of plant load factors in various sectors over a period of last five years:
The PLF in the country during 2007-08 to 2011-12 is as under:
Year Target Actual Sector-wise Actual
(%) (%) Central State Private
2007-08 77.1 78.6 86.7 71.9 90.8
2008-09 79.17 77.19 84.30 71.17 91.01
2009-10 77.20 77.50 85.49 70.90 85.68
2010-11 72.1 75.1 85.1 66.7 85.6
2011-12 68.69 73.32 82.12 68.0 76.19
Though it appears from above data that the actual production has exceeded the target
production, the overall situation indicates that there remains a tremendous scope for
improvement in plant load factor; particularly in the private sector.
In 1884, Charles Parsons developed the first practical, modern, high-speed steam turbine which
overcame many short comings of earlier trails.
There are two basic types of turbines, namely REACTION and IMPULSE. Turbines can be further
classified as:
• The back pressure turbine:
The back pressure turbine discharges the steam into a pressurized piping system to be
used for process heating elsewhere or as the supply to other turbines. For instance a
turbine may receive steam at "(X)" Kg./cm2 and discharge into a "(X – α)" Kg./cm2 system.
• The atmospheric turbine:
The atmospheric turbine is obvious. Here the usually short discharge piping is used just to
get the steam out of the building or to direct it away safely.
• The condensing turbine:
The discharge of a condensing turbine connects to a surface condenser to extend the
range of pressure drop through the turbine to extract more power. The discharge
pressure is actually a vacuum.
Of the three types above, steam surface condensers are the most commonly used condensers in
modern power plants. The exhaust steam from the turbine flows on the shell side (under
vacuum) of the condenser, while the plant’s circulating water flows in the Tube side. The
condensed steam from the turbine, called condensate, is collected in the bottom of the
condenser, which is called a hot well. The condensate is then pumped back to the steam
generator to repeat the cycle.
The main heat transfer mechanisms in a surface condenser are the condensing of saturated
steam on the outside of the tubes and the heating of the circulating water inside the tubes. Thus
for a given circulating water flow rate, the water inlet temperature to the condenser determines
the operating pressure of the condenser. As this temperature is decreased (due to cleaner heat
transfer areas and proper heat exchange), the condenser pressure will also decrease. This
decrease in the pressure (proper maintenance of vacuum) will increase the plant output and
efficiency.
Due to the fact that a surface condenser operates under vacuum, with better vacuum, more
steam will migrate towards the condenser and increase the turbine efficiency due to reduced
back pressure.
On the other hand, the partly condensed steam (due to poor vacuum) will increase the operating
pressure of the condenser. Since the total pressure of the condenser will be the sum of partial
pressures of the steam and the gases, as more and more partly condensed steam remains in the
system, the condenser pressure will rise. This rise in pressure will decrease the turbine output
and efficiency. This will also blanket the outer surface of the tubes and will severely decrease the
heat transfer from the steam to the circulating cooling water and again, the pressure in the
condenser will tend to increase.
Effect of exhaust pressure/ vacuum:
Higher exhaust pressure i.e. lower vacuum, increases the steam consumption in the turbine,
keeping all other operating parameters constant. Exhaust pressure lower than the specified will
reduce the steam consumption and improves the turbine efficiency. Similarly exhaust vacuum
lower than the specified, will lower the turbine efficiency and reduces the steam consumption.
Figures below represents the effects of exhaust vacuum on steam consumption and turbine
efficiency respectively, keeping all other factors constant for the condensing type turbine.
These figures also indicate that improvement in exhaust vacuum by 10 mm Hg (Mercury),
reduces the steam consumption in the turbine by about 1.1 % and improvement in turbine
efficiency varies significantly from 0.24 % to 0.4 %.
1. Effect of exhaust vacuum on steam
consumption in condensing type turbine
2. Effect of exhaust vacuum on turbine
efficiency in condensing type turbine
SCALE-BANTM
AND THE CONDENSERS OF CONDENSING TYPE STEAM TURBINES:
SCALE-BAN
TM can be very gainfully installed in thermal power plants operating on extraction type
surface condensation (Extraction Condensing Steam Turbine) as well as in combined cycle power
plants employing Extraction Condensing Steam Turbine.
Typically, a 1000 MW power plant would require approximately 98000 M3 of water per day,
most of which is wasted resulting in higher operating costs for the plant.
SCALE-BANTM
offers a huge potential by way of:
• Saving this precious water,
• Improving the Plant Load Factor (PLF) due to maintenance of constant condenser vacuum
thus resulting in higher power generation,
• Actually reducing the plant down time required for condenser cleaning.
As one might expect, with millions of litres of circulating (cooling) water flowing through the
condenser tubing from seawater to fresh water, anything that is contained within the water and
flowing through the tubes, can ultimately end up on either on the condenser tube-sheet or
within the tube itself. Tube side fouling for surface condensers is caused mainly due to SCALING,
which are crystalline forms of Calcium and Magnesium salts.
Depending on the extent of this fouling, the impact can be quite severe on the condenser's ability
to condense the exhaust steam coming from the turbine. As fouling builds up within the tubing,
an insulating effect is created and the heat transfer characteristics of the tubes are diminished
requiring the turbine to be slowed to a point where the condenser can handle the exhaust steam
produced. Typically, this can be quite costly to power plants in the form of reduced output,
increased fuel consumption and increased CO2 emissions. This "de-rating" of the turbine to
accommodate the condenser's fouled or blocked tubing is an indication that the plant needs to
clean the tubing in order to return to the turbine's rated capacity.
SCALE-BANTM
INSTALLATION
Installation instructions for SCALE-BAN™:
• Ensure that the Heat Exchanger / Condenser is properly De-Scaled
and thoroughly cleaned before installation of SCALE-BAN™.
• Identify the location for installation of SCALE-BAN™, (which should
be nearest to the Heat Exchanger / Condenser inlet) and there
should not be any valve, strainer or any other appurtenance
upstream of SCALE-BAN™.
• First measure the length of SCALE-BAN™ to be installed.
• Cut the equivalent length of "DISTANCE PIECE" from inlet line at a
point nearest to the heat exchanger. Weld both the flanges
provided with SCALE-BAN™ on both cut ends of the inlet line.
• Properly install SCALE-BAN™ between these two flanges.
• Complete the installation by inserting SCALE-BANTM along with
gaskets and properly tightening all the bolts and nuts supplied
with SCALE-BAN™.
Operating Guidelines for SCALE-BAN™:
• Ensure that the Heat Exchanger / Condenser is properly De-Scaled and thoroughly cleaned
before installation of SCALE-BAN™.
• There should not be any Zero velocity zone or static part between SCALE-BAN™ and heat
Exchanger / Condensers to be protected.
• There should not be any valve or strainer between SCALE-BAN™ and
Heat Exchanger/Condensers.
• Cooling tower sump should be cleaned for any dust/sludge/debris etc. before start of
operation.
• Side Stream filter should be operated daily with open top back wash once in a week.
• pH value of the re-circulating cooling water should be maintained between 7.5 to 8 for
optimal results of SCALE-BAN™.
• pH can be maintained by dosing pH maintaining Chemicals or by dosing of commercial H2SO4.
• The Quantity of Sulphuric Acid (H2SO4) dosing can be finalised on commencement of the
operation as it is dependent on the Sump holding capacity, quality of water, pH of makeup
water, flow rate, evaporation and drift losses etc.
SAVINGS
Savings achieved through installation of SCALE-BAN™:
• Improved Plant Load Factor (PLF).
• Begins a march towards Zero Discharge.
• Improved operating profits due to tremendous savings.
• Maintenance of constant vacuum in turbine condenser.
• No shutdown of plant is required for cleaning of Heat Exchanger / Condensers because of
Zero scaling.
• Excellent Water savings due to reduced blow down with high COC operation of cooling tower.
• Since SCALE-BANTM
is tested to run at high hardness (10000 ppm) and TDS (40000 ppm) in
cooling tower without treatments, so blow down from cooling tower is negligible.
• No water softening plant is required hence recurring expenses related to water softening are
saved.
• De-scaling chemicals are not required to be added in cooling water.
• ETP load is reduced significantly.
• Due to repeated cleaning of the hard scales in tubes with rod, tube surfaces become weak
and prone to leakage, which is avoided due to Zero Scale.
• SCALE-BAN™ is "fit and forget" equipment having a guaranteed maintenance free life of 20
years - consuming no power.
ADVANTAGES
Prevention of Scale:
Due to its unique ability to precipitate dissolved solids in to a colloidal suspension, scale tends to
build up on these seed crystals rather than on the heat transfer areas, thereby preventing the
deposition of scale on the heat transfer areas.
Removal of Existing Scale:
Due to the reduction of the free Calcium and Magnesium from solution by the formation of their
Carbonate crystals and the solubility being constant, water can dissolve more salts, which it
tends to pick up from the existing scale in the system, thereby desalting scaled up systems, under
ideal conditions.
However as the solubility of these is affected by the changes in pH, temperature and pressure,
SCALE-BAN™ will de-scale only under ideal conditions of above parameters. Hence it is not
marketed as a scale remover, but as a scale preventer.
Eliminates recurring costs of expensive chemicals, regenerative salts and resins:
SCALE-BAN™ has no recurring costs as associated with Chemical Dosing or Water Softening, as
no chemicals, regenerative salts or resins are used.
Chemical composition of the water does not change:
SCALE-BAN™ does not change the chemical composition of water, but instead, changes the
physical composition of the scaling salts from a dissolved state to a suspended state, thereby
preventing scale build up.
No risk of corrosion:
Water softeners necessitate the use of corrosion inhibitors, as the water tends to be corrosive.
Similarly, Chemical Dosing reduces the pH of water, thereby increasing the risk of corrosion.
SCALE-BAN™ on the other hand has the unique advantage of preventing scale deposition without
increasing the risk of corrosion.
Eliminates recurring labour costs:
SCALE-BAN™ is a "fit - and – forget" system. It does not require any labour, or supervision for
chemical addition or for regeneration salts as required for chemical dosing and water softener.
Does not require any maintenance:
As SCALE-BAN™ has no moving parts, it requires no replacement of parts or maintenance, other
than normal plant maintenance.
Saves fuel consumption:
Scales reduce heat transfer efficiency resulting in increased energy use which can rise by almost
50%. In Air-conditioning systems, a 5 mm fouling of the condensers can result in an increase of
power costs by over 30%. As the SCALE-BAN™ is installed "on-line", it is constantly preventing
the deposition of scale, thereby saving valuable energy costs as compared to manual desalting
systems, which require desalting to be done periodically.
No Energy Consumption:
Unlike conventional water treatment systems, SCALE-BAN™ does not require any power or
electrical inputs.
No Pollution:
Chemical dosing and water softening systems necessitate the use of chemicals which are
hazardous and cause pollution, and hence have to be treated before water is released into the
underground water table. SCALE-BAN™, on the other hand, does not require use of any such
chemicals.
SCALE-BANTM can handle variable water qualities:
In conventional systems of chemical dosing and water softening, the quantity of various
chemicals has to be adjusted according to the water quality; hence the system has to be closely
monitored for variable water qualities. SCALE-BAN™, on the other hand, is not affected by
variable water qualities and can handle water up to any hardness.
No investment risk:
SCALE-BAN™ is sold with a Twenty Years Performance Guarantee. In view of this, there is no
investment risk on part of the user of the equipment. It also offers a low pay back period,
depending upon the type of industry and present means of water treatment.
Estimated savings after installation of SCALE-BANTM
Plant Data
• Power Plant Capacity in MW. 100
• Flow of Re-Circulating Water M3/Hr. 20000
Status prior to installation of SCALE-BANTM
:
• COC Maintained 4 COC
• Evaporation Losses (Le) @1.5% of circulation rate [A] 300 M3 /hr
• Blow Down from Cooling Tower = {Le / (COC-1)} [B] 100 M3 /hr
• Total consumption per hour = [A]+[B] [C] 400 M3 /hr
• Total water requirement per Day = [C] x 24 as make up to cooling tower [D] 9,600 M3 / Day
• Regeneration Losses in softener per day @10% of feed water to softener [E] 960 M3 / Day
Status Changed after installation of SCALE-BANTM
:
• COC Maintained 20 COC
• Evaporation Losses (Le) @1.5% of circulation rate [A1] 300 M3 /hr
• Blow Down from Cooling Tower = {Le / (COC-1)} [B1] 16 M3 /hr
• Total consumption per hour = [A1]+[B1] [C1] 316 M3 /hr
• Total water requirement per Day = [C1] x 24 as make up to cooling tower [D1] 7,584 M3 / Day
• Total savings of water per day = [D] – [D1] [E1] 2,016 M3 / Day
• Total savings of water per year [E1] x 330 days / year [F1] 6,65,280 M3 / Year
A. TOTAL DIRECT SAVINGS AFTER INSTALLATION OF SCALE-BANTM
1. Saving due to less consumption of water, stoppage of softener operation and non usage of anti-
scaling chemicals:
• Cost of water saved = [F1] x Rs. 15/- per M3 [G] 99,79,200 Rs. Per Year
• Cost of Anti-scaling chemicals saved Lump sum – Assumed [H] 25,00,000 Rs. Per Year
Total Savings per Year (1) = [G] + [H] Rs. 1,24,79,200 Rs. Per Year
2. Savings due to proper HEAT EXCHANGE inside condenser and lesser consumption of High
Pressure steam:
• Profits reduced due to excess consumption of 0.2 Te (being just 5% of
normal consumption) of HP steam per MW generation for an average of
100 days in a year due to scaling in condenser:
Considering normal consumption of 4 Te of HP steam per MW generation;
and assuming the cost of Steam as Rs. 600/- per Te; the total excess
steam consumption per day will be 100MW x 0.05 x 4 Te x 24 hours =
480Te per day
Therefore, Cost of Excess Steam consumed for 100 days shall be = 100 x
480 x 600 = Rs. 2,88,00,000/-P.A.
2,88,00,000 Rs. Per Year
Total Savings per Year (2) Rs. 2,88,00,000 Per Year
B. TOTAL DIRECT SAVINGS = (1) + (2) Rs. 4,12,79,200 Per Year
B. TOTAL INDIRECT SAVINGS AFTER INSTALLATION OF SCALE-BANTM
1. Loss of Profits due to forced plant shutdown of 3 days for De-scaling:
Considering profit to be Rs. 2000/- per MW;
Loss of profits = 2000x100MWx24 hrs.X3 days = 1,44,00,000
Rs. 1,44,00,000 Rs. Per Year
2. Profits reduced due to partial loss of vacuum in condenser because of
scaling in condenser tubes:
Considering less generation of 5 % for 75 days and importing the shortfall
from Grid 0.05x100MWx24x75x2000
Rs. 1,80,00,000 Rs. Per Year
B. TOTAL INDIRECT SAVING (1) + (2) Rs. 3,24,00,000 Rs. Per Year
TOTAL [ (A) DIRECT + (B) INDIRECT ] SAVING = Rs. 7,36,79,200 Rs. Per Year
SELECTION
SCALE-BAN™ is selected on basis of:
[A] Water flow (M3 per hour) rate,
[B] Size of Cooling Water line.
Engineering Data
Notes:
1. Approximate Length of SCALE-BAN™ is one meter.
2. SCALE-BAN™ is supplied in flanged or screwed end connections with matching flanges.
3. The equipment is tailor made as per specific requirements of the application.
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