This document provides information on the water treatment and electrical systems for the balance of plant for a 2x500MW thermal power project. It discusses the water requirements and sources, various water treatment processes, desalination processes, and electrical and control systems. The key points are: fresh water is a critical input for thermal power plants but availability is limited, so water conservation and reuse methods are discussed. Membrane and thermal desalination processes are described to supplement fresh water sources. Electrical systems including transformers, switchgear, cables, and control and instrumentation are outlined.

1. BALANCE OF PLANT FOR
THERMAL
POWER PROJECT 2X500MW
WATER TREATMAENT
PLANT
By: Abdullah

2. 1.Water is a key Input required for Thermal Power Generation
2.Available water resource are fixed an water requirement is increasing
3.Water has priority for drinking & irrigation over that for power generation
4.Availability & Allocation of water for Thermal power plant has been
reducing
5.Low grade water is also being supplied as input Raw water to the Thermal
plant
Water Availability Aspect

3. 1.Clarified water as cooling tower make-up and
service water
2.Demineralisd water for heat cycle make-up,
equipment cooling system make-up, condensate
polishing plant regeneration etc.
3.Filtered & disinfected water for potable water
requirement.

4. BOP Comprises
1.Plant Water System
2.Cooling Water System
3.Coal Handling System
4.Ash Handling System
5.Mechanical Auxiliaries (Fuel Oil, Fire Fighting, AC,
Ventilation etc,)
6.Plant Electricals
7.Contorl & Instrumentation
8.Civil Structural & Architectural works

5. Typical Water Uses In Coal Based Thermal
Power plant
1.Cooling of condenser & secondary cooling of PHES in ECW system
2.Power cycle make up
3.Wet Ash Disposal
4.Coal Dust suppression
5.Air conditioning & Ventilation
6.Other uses viz potable uses, plant washing

6. Cooling Water System
Once through system:
Permissible for coastal site with temperature rise of 7 deg c over
temperature of receiving water body
Closed cycle open recirculation system using cooling tower:
Required make up water to compensate for loss of water due to
evaporation , drift and blow down
Blow down is required to maintain a desired level of COC in
CW system

7. CT Make –Up & Blow Down
CT make –up water, M=E.C/C-1
Blow down water, B=E/C-1-D
Where
E=Evaporation
D=Drift
C=COC of CW system

8. Features of Plant water Requirement
1.Source / quality of raw water
2.Type of CW system
3.Quality of coal
4.Plant design aspect
5.Uses of dry fly ash
6.Treatment /Reuse of waste water

9. Earlier water was taken as an assured input
Plant consumptive water with Cooling tower used to be about
7meter cube /h/MW without ash water recirculation
And 5meter cube /h/MW with ash water recirculation

10. Consideration For Reduction Of Plant Water Requirement
1.Clarifier sludge water and filter backwash to be recycle
2.COC of 5 for CW system operation
3.Boiler Blow down to be used as part of CT make-up
4.Power cycle make up as 2% of BMCR flow
5. Waste water to used for coal dust suppression and gardening
6.Dry cooling system as per constraint in availability of raw water

11. Consideration With Dry Cooling System
Condenser cooling by dry cooling system
ACW(Auxiliary Cooling Water) system to be based on wet cooling tower
Fly ash disposal in dry mode/ HCSD mode
Bottom ash disposal in Wet mode

13. Water Treatment system

15. Water Balance Diagram 2x500MW Coal Based TPP With
Dry Cooling System

16. Water Balance Diagram 2x500MW Coastal TPP

19. Wet Cooling System:
3.6meter cube/h/Mw during initial period of plant
operation with fly ash disposal in wet mode
Dry Cooling System:
0.75 meter cube/h/MW during initial period of plant
operation without recovery of bottom ash water
Coastal plant:
Fresh water requirement 0.4 meter cube/h/MW
Sea water to be used for process cooling & ash disposal

20. Direct Dry Cooling:- Air Cooled Condenser
 LP turbine exhaust steam is directly cooled inside a system of finned
tube bundles by ambient air using forced draft fans
 No Terminal Temperature Difference(TTD) is involved
Indirect Dry Cooling:-Surface condenser
 Steam is cooled in a surface condenser by circulating water which in
turn, inside a system of finned tube bundles is cooled by ambient air
using fan or a natural draft tower
 Terminal Temperature Difference (TTD) is involved

21. Air Cooled Condenser With Fan

22. Indirect Dry Cooling With Surface Condenser

23. Jet Condenser

24. Hybrid condenser

29. DESALINATION
It is a process that removes or separates salts from saline
water to give fresh water, at the expense of energy.
Depending upon the type or form of energy used,
Desalination Processes can be broadly classified into two
groups:
1. Thermal Desalination
2. Membrane Desalination

30. Multi-Stage Flash (MSF) Distillation

31. Typical raw water analysis considered for canal water is as under:
S. No. Constituents Concentration
i) PH 8.2
ii) Conductivity, micro mhos/cm 450
iii) TDS 315
iv) Turbidity, NTU 20-500
v) Calcium hardness as CaCO3 ppm 110
vi) Magnesium hardness as CaCO3 ppm 95
vii) Sodium as CaCO3 ppm 100
viii) Potassium as CaCO3 ppm 10
ix) Total cations as CaCO3 ppm 315
x) P-Alkalinity as CaCO3 ppm Nil
xi) M-Alkalinity as CaCO3 ppm 250
xii) Chloride as CaCO3 ppm 30

32. •Typical consumptive requirement at COC of 5 for 2 x 500 MW thermal project is as under:
S. No. Description Requirement, m3/h
1 Cooling tower make up 2550*
2 DM water 85
3 Potable water 52
4 Service water 200
5 Reservoir evaporation 30$
6 Loss in sludge etc. 2
7 Bottom ash system make up 90#
Total 2899 say 3000

33. THERMAL DESALINATION
Thermal desalination processes involves heating of saline
water to its boiling point to produce water vapor, this pure
vapor is condensed to produce fresh water.
The three types of thermal desalination units used
commercially are:
1. Multistage flash (MSF)
2. Multiple effect distillation (MED)
3. Low Temperature Evaporation (LTE)

34. Multi-Effect Distillation (MED)

35. Low Temperature Evaporation

36. MEMBRANE DESALINATION
 Membrane processes use a semi permeable membrane to
move water across the membrane from the salt solution to
produce fresh water on the other side of the membrane.
 Membrane desalination is classified depending on the
driving force.
Process Size of materials
retained
Driving force
Microfiltration 0.1-10.0 microns
molecules
Pressure difference
Ultrafiltration 5-100 nm molecules Pressure difference(1 -
4 bar)
Nanofiltration 0.5 - 5 nm molecules
(mostly charged
species)
Pressure difference(5 -
15 bar)
Reverse Osmosis < 1 nm molecules Pressure difference(10
- 60 bar)

37. MICROFILTRATION
Microfiltration is a process of separating material of colloidal
size and larger than true solutions.
The MF membranes are made from natural or synthetic
polymers such as cellulose nitrate or acetate, polyvinylidene
difluoride (PVDF), polyamides, polysulfone, polycarbonate,
polypropylene, PTFE etc. The inorganic materials such as
metal oxides (alumina), glass, zirconia coated carbon etc.
are also used for manufacturing the MF membranes.
Applications of MF are:
1. Food & beverages
2. Chemical industry
3. Microelectronics industry
4. Fermentation

38. ULTRAFILTRATION
Ultrafiltration is most commonly used to separate a solution that has a mixture of some
desirable components and some that are not desirable. Rejected species include sugars,
biomolecules, polymers and colloidal particles.
Applications of MF are:
1. Oil emulsion waste treatment
2. Treatment of whey in dairy industries
3. Concentration of biological macromolecules
4. Electrocoat paint recovery
5. Concentration of textile sizing
6. Concentration of heat sensitive proteins for food additives
7. Concentration of gelatin

39. NANOFILTRATION
The separation mechanism of NF involves size exclusion as well as electrostatic
interaction. In NF, organic molecules with molecular wt. greater than 200-400 are
rejected.
Membranes used for NF are of cellulosic acetate and aromatic polyamide type.
Applications of NF are:
1. Concentration of sugars, divalent salts, bacteria, proteins, particles, dyes and other
constituents that have a molecular weight greater than 1000 daltons.
2. Removal of color and total organic carbon (TOC) from surface water
3. Removal of hardness from well water
4. Overall reduction of total dissolved solids (TDS)

40. REVERSE OSMOSIS
RO membranes give 96%-99% NaCl rejection. Greater than 95-99% of inorganic
salts and charged organics will also be rejected by the membrane due to charge
repulsion established at the membrane surface.
RO membranes are made of polymers, cellulosic acetate and aromatic polyamide
types.
Applications:
1. Potable water from sea or brackish water
2. Ultra pure water for food processing and electronic industries
3. Pharmaceutical grade water
4. Water for chemical, pulp & paper industry
5. Waste treatment etc.
6. Municipal and industrial waste treatment

41. MEMBRANE PREPARATION
 Membrane preparation was done using the immersion precipitation
technique.
 Dry polysulfone beads were taken in air tight bottles and then a specific
amount of DMF was added to dissolve the polymer. The same method was
applied the PVDF powder.
 A piece of fabric was kept on the glass plate and the casting solution was
spread on it evenly.
 The entire assembly was immediately immersed in a room temperature
gelling bath made by using Ultra Filtered water.
 The membranes were stored in laboratory refrigerator maintained at 5oC.

42. Renewable Energy based Desalination
Conventional sources of energy are depleting fast and hence there is an urgent need to
find renewable sources of energy. Desalination can also be carried with the help of
renewable sources of energy such as solar energy. One of the methods is Solar Reverse
Osmosis. This setup can also be done in those areas where access to grid electricity is
not possible. Also, renewable energy based methods are pollution free and
environmental friendly.
Solar Reverse Osmosis Unit:
•POWER PACK
•PRE-TREATMENT
•REVERSE OSMOSIS MEMBRANE
•POST TREATMENT

44. PIPE PRESSURE DROP CALCULATIONS
Factors affecting pressure drop calculations:
1. Friction between the fluid and the wall of the pipe
2. Friction loss as the fluid passes through any pipe
fittings, bends, valves, or components
3. Pressure loss due to a change in elevation of the fluid
(if the pipe is not horizontal)
4. Friction between adjacent layers of the fluid itself

45. ELECTRICAL AND CONTROL & INSTRUMENTATION SYSTEM
Electrical System - Design Criteria :
11kV/ 3.3kV incomers from station switchgears to 11kV/ 3.3kV station auxiliary plant/
system switchgear shall be through adequately rated cables. 3.3kV switchgear shall be
fed from transformer either through cable or busduct. For 415V system, busduct shall be
used for incoming connection from transformers to the switchgear wherever transformer
rating is 1000kVA and above.
Electrical System - General Technical Requirements :
1.Transformers
The transformers shall be provided with delta-connected primary and a star–connected
secondary with the star point brought out and resistance earthed for 3.3kV system and
solidly earthed for 415V system.

46. 2. 11kV and 3.3kV Busducts :
a) Number of phase 3 3
b) Frequency 50 Hz 50 Hz
c) Nominal voltage 11kV 3.3 kV
d) Highest system voltage 12 kV 3.6 kV
e) One minute power frequency withstand
voltage (dry and wet) 28 kV 10 kV
f) Impulse voltage withstand value with
1.2/50 micro-sec wave shap 75 kV 40 kV
g) Continuous current rating as required as required
h) Short time current rating for 1 second 40kA 40kA
i) Dynamic current withstand rating 100 kA(peak) 100kA(peak)
j) Type of cooling Natural Natural
k) Type of bus enclosure Phase segregated Phase segregated

47. 2. 11kV and 3.3kV Switchgears:
The switchgears shall be indoor,
metal clad, draw out type. The
motor feeders above
2000kW rating shall have
vacuum/ SF6 breakers. The
motor feeders below 2000kW
rating shall have either vacuum/
SF6 breakers or vacuum/ SF6
contactors backed up by
HRC fuses. However, in an
application, where frequent start/
stop operations are
required, vacuum contactors/
breakers shall be preferred. The
operating mechanism of the
circuit breakers shall be of the
stored energy type DC motor
operated charging springs.

48. 3. DC System :
DC system comprising of DC storage batteries suitably rated Trickle and Boost chargers
and DC distribution boards shall be provided to cater the normal DC loads.
4. Power and Control cables and Laying & Termination :
For 11/ 3.3kV system, Power cables shall be XLPE insulated with conductor and insulation screens
armoured and FRLS PVC outer sheathed.
 Fire alarm, annunciation and protection system.
 DC supply cables to switchgears.
 DC cables from batteries to DC boards.
 DC emergency lighting cables for main building etc.
5. Lighting system:
The auxiliary building shall be provided with

49. a) Main Lighting system
b) Emergency lighting system
c) Minimum emergency lighting system
d) Suitable no. of Portable lighting units
6. Earthling and Lightning Protection system:
Earthling and lightning protection for the entire areas or buildings covered shall be
provided in accordance with IS 3043, IS 2309, IEEE 80 and IEEE 665 and Indian Electricity
Rules/ Acts.
3. Control & Instrumentation System - Design Criteria :
A totally integrated instrumentation and control system covering the total functional requirements of
sequential control, interlock, protection, monitoring, alarm, data logging, fault analysis etc.