COMPARISON OF EFFICIENCY ON DIFFERENT LOAD DURING ENERGY AUDIT OF THERMAL POWER PLANT

International Journal of Exploring Emerging Trends in Engineering (IJEETE)

Vol. 01, Issue 04, DEC, 2014 WWW.IJEETE.COM

ISSN – 2394-0573 All Rights Reserved © 2014 IJEETE Page 69

COMPARISON OF EFFICIENCY ON DIFFERENT LOAD DURING ENERGY AUDIT OF

THERMAL POWER PLANT

1Pankaj Sindhu,

2Somvir Arya,

3Dr. Rohit Garg

1Dept. of Mechanical Engineering, IIET, Kinana, Jind, Haryama

2Dept. of Mechanical Engineering, IIET, Kinana, Jind, Haryama

3Professor, Dept. of Mechanical Engineering, IIET, Kinana, Jind, Haryama

Abstract—This document carry out the reading

of efficiency of a thermal power plant for

different load factor of 450MWand 480 MW.

And calculate the efficiency of Boiler, turbine

and heaters.

Keywords—Energy audit , Thermal power

Plant

I. INTRODUCTION

Objective of energy management is to manage

the energy efficiency of the individual sub-

system equipment etc., the objective of energy

audit is to balance the total energy inputs with

its use and to identify all energy streams in a

facility. Energy Audit quantifies the usage of

energy according to its discrete functions.

Energy audit focuses attention on energy cost

also. Costs involved in achieving higher

performance are studied by financial analysis

and the best alternative is selected. The analysis

basically checked the efficiency of energy use at

present. Energy Audit covers the overall process

of data collection and carrying out technical and

financial analysis to evolving specific energy

management action. Energy Audit identifies the

performance of each equipment and compares it

with the base case.

Energy Conservation and Energy Audit

Energy conservation means reduction in energy

consumption but without making any sacrifice

of quantity and quality of production. It is

therefore imperative that electricity, Which is in

shortage, be utilize efficiently and corrective

measures are searched for adoption. This could

be done by “Energy Audit”Maintaining the

Integrity of the Specifications

Need of Energy Conservation and Energy

Audit

In the present scenario of rapidly growing

demand of energy in transportation, agriculture,

domestic and industrial sectors, the conservation

of energy has become essential for over coming

the mounting problems of the world wide crisis

and environmental degradation. There are two

factors contributing to the increase in the energy

consumption (i) more than 20% increase in

world’s population and (ii) world wide

improvement standard of living. The industrial

sector consumes about 50% of our energy and

therefore improving energy efficiency is the

focus of the thesis work. It has been estimated

that 25% improvement in the energy efficiency

of the industrial sectors as per the data given in

Table-1 is possible. In industry there are about

ten energy intensive like steel, petroleum,

fertilizer, cement, paper etc. which consumes

about 60% of the energy used by industrial

sector. Increasing government regulation,

shortage of energy resources, soaring prices

have compelled the energy consumers to go in

for energy savings.

Energy audit is of the tool to help in energy

savings. Therefore energy conservation and

energy audit in industry are never concepts for

improving energy efficiency and have emerged

as thrust areas. The conservation of energy

programs of an industrial process contributes in

improving energy efficiency and further

increased energy efficiency enhances the




productivity. Along with conservation of energy

there is urgent need to explore newer

alternatives and renewable energy resources

Sr.No. Energy

ConsumingnSectors

Scope of

Improvement

1 Industrial 25%

2 Domestic 30%

3 Agriculture 30%

4 Transportation 20%

To meet the growing demand for energy in

industries, one of the aims is to identify the

technical support in improving their energy

performance through comprehensive energy

audits, implementation assistance, technology

audits, and capacity-building. Energy audits

help in identifying energy conservation

opportunities in all the energy consuming

sectors. While these do not provide the final

answer to the problem, but do help to identify

the existing potential for energy conservation,

and induces the organizations/individuals to

concentrate their efforts in this area in a focused

manner.

Problem Formulation

In RGTPP Khedar, 600 MW units is

consideration for energy Audit for Energy Audit

and Efficiencies of main sub-units as like Boiler,

Turbine and generator, Condenser & Heater are

calculated and compared are different loads

which highlights in NTPC 210MW units energy

efficiency has to be improved to survive in

Global Market.

Efficiency of any plant or equipment is the ratio

of output to its input, expressed as percentage.

Output and input are expressed in same physical

units. The output is the electrical energy sent to

the grid and input is the heat energy of the fuel

fired in boiler.

Overall station efficiency =

Output of Station X 100

Input of Station

= Energy sent out (KW) ______

Fuel burnt (Kg) x Calorific value of fuel (K

Cal/Kg)

Thermal Power Plant Cycle

Thermal Power Plant burns fuels and use the

resultant heat to raise the steam, which drive the

turbo generator. The fuel may be ‘fossil’ (Coal,

Oil or Natural Gas) or it may be fissionable

(uranium). Whichever fuel is used the object is

same to convert heat into mechanical energy

into electricity by rotating a magnet inside a set

of windings.

Conventional power plants work on Rankine

cycle. The cycle may be split into distinct

operations:

Water is admitted to the boiler raised to

boiling temperature and then

superheated.

The superheated steam is fed to a steam

turbine where it does work on the blades

as it expends.

The expended steam is rejected o the

condenser and the resultant condensate is

fed back to the boiler via feed heaters.

The turbine drives a generator, which is turn

supplies electricity to the bus bars.

Working Cycle of Typical Coal Fired Power

Station

Layout shows a Coal Fired Power Station. Its

main raw material is Coal, air and Water. The

Coal brought to the station by trains or by the

other means & this travels from Coal handling

plant by conveyor belt to the coalbunkers, from

where it is fed to the Pulverizing Mills, which

grind it as fine as face as face powder. The

finely powdered coal mixed with pre-heated air,

is then blown into the Boiler by a fan called

Primary Air Fan where it burns, more like a gas

than as a solid in the conventional domestic or

industrial grate, with additional amount of air

called secondary air supplied by a Forced Draft

Fan.

As the coal has been ground so finely the

resultant ash is also a fine powder. Some of it

binds together to from lumps, which fall into the

ash pits at the bottom of furnace. The water-




quenched ash from the bottom of furnace is

conveyed to pits subsequent disposal or sale.

Most of ash, still in fine particles form is carried

out of the boiler to the Precipitators as dust,

where electrodes charged with high voltage

electricity traps it. The dust is then conveyed by

water to disposal areas or to Bunkers

For sale while the cleaned flue gases pass on

through Induced Draft Fan to be discharged up

the Chimney.

Meanwhile the heat released from the coal has

been absorbed by the many Kilometers of tubing

which line the boiler walls. Inside the tubes is

the Boiler Feed Water, which is transformed by

the heat into steam at high pressure and

temperature. The steam, super heated is further

tubes (Super Heater) passes to the Turbine

where it is discharged through nozzles on the

turbine blades. Just as the energy of the wind

turns the sails of the windmill, so the energy of

steam, striking the blades, makes the turbine

rotate. Coupled

To the end of the turbine is the rotor of the

Generator –a large cylindrical magnet- so that

when the turbine rotates the rotor with it. The

rotor is housed inside the stator having heavy

coils of copper bars in which electricity is

produced through the movement of the magnetic

fields created by the rotor. The electricity passes

from the stator winding to the Step-up

Transformer which increases its voltage so that

it can be transmitted efficiently over the power

lines of the grid.

The steam, which has given up its heat energy,

is changed back into water in a condenser so

that it is ready for re-use. The condenser

contains many Kilometers of tubing through

which cold water is constantly pumped. The

steam passing around the tubes loses heat and is

rapidly changed back to water. But the two lots

of water (i.e., boiler feed water and cooling

water) must never mix. The cooling water is

drawn from the river/sea, but the boiler feed

water must be absolutely pure, far purer than the

water, which we drink, if it is not to damage the

boiler tubes.

Heat, which the water extracts from the steam in

the condenser, is removed by pumping the water

out to the Cooling Towers. The water is sprayed

out at top of the towers and as it falls into the

pond beneath it is cooled by the upward draught

of air. The Pump then recalculates the cold

water in the pond.

Data Collection:

Table No.2




DATA OF 600MW THERMAL POWER

PLANT AT LOAD 480MW

Sr.

No. Description Condition

Pressure

(bar)

Tem.

(0C)

Flow

(T/Hr)

Enthalpy

(KJ/Kg)

Energy

(MW)

1 Steam Inlet HPT Superheat

Steam 161 538 835 3586 831.75

2 Steam Outlet HPT and

Inlet Re-heater

Superheat

Steam 31.6 326 735 3090 630.88

3 Steam Outlet Re-heater and

inlet IPT

Superheat

Steam 28.6 522 675 3529 661.69

4 Steam Outlet IPT and inlet LPT Superheat

Steam 10.85 360 600 3190 531.66

5 6th Extraction HPT and inlet

HPH6

Superheat

Steam 31.5 320 100 3025 84.027

6 HPH6 Outlet and Inlet HPH5 Water 20 205 100 2007.6 55.76

7 5th Extraction IPT and Inlet

HPH5

Superheat

Steam 16.6 453 60 3389 56.48

8 HPH5 Outlet and Inlet Dearator Water 6.5 171 100 1864.8 51.8

9 3rd Extraction IPT and Inlet

LPH3

Superheat

Steam 4.5 317 20 3078 1.71

10 Drip Outlet LPH3 and Inlet

LPH2 Water 122.4

11 2nd Extraction LPT and Inlet

LPH2

Superheat

Steam 0.9 233 17 2910 1.37


LPH1 Water 120 1650.6

13 1st Extraction LPT Inlet LPH1 Superheat

Steam -1.5 97 23 1554 9.85

14 Drip Outlet LPH1 and Inlet to

Hot-well Water 47 1344

15 Exhaust Steam Outlet LPT Superheat

Steam 0.08 45 505 1335.6 187.36

16 Condenser Outlet & Inlet Hot-

well Water 0.08 40 505 1314.6 184.41

17 Condensed Steam Inlet to

LPH1 Water 11 45 600 1335.6 222.6

18 Condensate Outlet LPH1 and

Inlet LPH2 Water 10.5 71 600 1444.8 240.8




Sr.


Pressure

(bar)

Tem.

(0C)

Flow

(T/Hr)

Enthalpy

(KJ/Kg)

Energy

(MW)

19 Condensate Outlet LPH2

and Inlet LPH3 Water 11.8 115 600 789.9 253.41


and Inlet Dearator Water 11.9 151 600 798.4 273.01

21 BFP Inlet Water 9.2 169 718 746.8 362.7

22 Condensate Inlet HPH5 Water 184.5 173 718 1756.5 363.54

23 Condensate Outlet HPH5

and Inlet HPH6 Water 184 205 718 1754 352.66


and Inlet Economizer Water 184 236 718 1754 428.04

25 Feed Water Inlet Drum

Water 179.5 321 718 1734.8 434.74

26 Steam Inlet LTSH Steam 176.04 365 718 820 522.69

27 Steam Inlet Platen SH Steam 172.05 408 718 860

28 Steam Inlet Final Super

Heater Steam 168.7 490 718 898 674.3

29 Flue Gas Inlet Re-heater Flue Gas -10 635 800 3813.6 847.46

30 Flue Gas Inlet Final

Super Heater Flue Gas -7 620 800 3750.6 833.46

31 Flue Gas Inlet Platen

Super-heater Flue Gas -0.08 950 800 5136.6 1141.46

32 Flue Gas Inlet LTSH Flue Gas -0.4 861 800 4762.8 1058.39

33 Flue Gas Inlet Economizer Flue Gas -0.65 433 800 2965.2 658.93

34 Flue Gas Inlet APH Flue Gas 93.7 313.8 800 1356 529.19

35 Flue Gas To Stack Flue Gas 101.4 121.7 800 2727 392

36 SA Inlet APH Air 145.6 32 800 2629 526.39

37 SA Inlet Boiler Air 240 272 850 2289 540.45

38 PA Inlet APH Air 615 36.5 142 1299.9 51.27

39 PA Inlet Boiler Air 615 292 142 2373 93.59

40 Coal Supply to Boiler Coal 228

41 Cold Water Inlet to

Condenser Water 6 30 40000 1272.6 14139.99

42 Hot Water Outlet From

Condenser Water 5 37 40000 1302 14466.67




Data Analysis

Data Analysis of plant at 480 MW

Boiler Section

Inlet in Boiler

(1)At (40) Coal = 228T/hr

= 228 x 1000/3600 =63.33 Kg./Sec.

Calorific Value = (C.V) of Coal = 3350 K

Cal/Kg

Energy = 3350 x 63.33 x 4.2/1000 = 891.05

MW

(ii) At (2) Energy = 630.875 MW

(iii)At (24) Energy = 349.825 MW

Outlet from Boiler

(iv) At (1) Energy = 831.75 MW

(v) At (3) Energy = 661.69 MW

(vi) Flue Gases (These are not taken in

consideration)

Total Inlet = (i) + (ii) + (iii)

= 891.05 + 630.875 + 349.825

= 1871.75 MW

Total Outlet = (IV) + (v) + (VI)

= 831.75 + 661.69 + 0

= 1553.4 MW

Loss in Boiler = Inlet – Outlet = 1871.75 –

1553.4

= 318.35 MW

Efficiency of Boiler = 1553.4x 100/ 1871.75

= 82.99 %

Section Turbine & Gen.

(i) HPT Inlet (1) = 831.75 MW

Outlet (2) + (5) = 630.87 + 84.027

= 714.89 MW

Net Energy at HPT = 831.75 – 714.89

= 116.86 MW

(ii) IPT Inlet (3) = 661.69 MW

Outlet (4) + (7) = 531.66+56.48

= 588.14 MW

Net Energy at IPT = 661.69 – 588.14

= 73.55 MW

(iii) LPT Inlet (4) = 531.66 MW

Outlet (9) + (11) + (13) = 1.71 + 1.37 +

9.93

= 13.01 MW

Net Energy at LPT = 531.66 – 13.01

= 518.65 MW

Net Input at Turbine (HPT, IPT & LPT)

= 116.86 + 73.55 + 518.65

= 709.06 MW

Efficiency of Turbo Generator

= 480 x 100/ 709.06

= 67.70 %

Section Condenser:

Condenser Efficiency = Actual Cooling Water

Temp rise

Max Possible Temp.

Rise

= (T42 – T41)

x100

T 17 – T41

= (37 – 30) x100

45 – 30

= 46.67 %

Section Heaters (LP & HP)

LPH1 Effectiveness = T18 – T17

T 13 – T17

= 71 - 45

97 – 45

= 0.50


T 11 – T18

= 89 - 71

218 – 71

= 0.12


T 9 – T19

= 117 - 89

303 – 89

= 0.13

HPH5 Effectiveness = T23 – T22

T 7 – T22

= 196 - 161

420 – 161

= 0.135


T 5 – T23

= 238 - 196



ISSN – 2394-0573 All Rights Reserved © 2014 IJEETE 5

330 – 196

= 0.31

Overall station efficiency = Output of

Station x 100

Input of Station

= Energy sent out (KW)

.

Fuel burnt (Kg) x Calorific value of

fuel (K Cal/kg)

Fuel burnt (Coal) = 114 T/ Hr

= 31.67 Kg/Sec

C.V = 4860 K Cal/kg

= 4860 x 4.2

= 20412 KW

Heat Input = 20412 x 31.67/1000 = 646.45 MW

Overall Efficiency of Plant = 232 x

100/646.45

= 35.89%




DATA OF 600MW THERMAL POWER

PLANT AT LOAD 480 MW

Sr.


Pressure

(bar)

Tem.

(0C)

Flow

(T/Hr)

Enthalpy

(KJ/Kg)

Energy

(MW)

1 Steam Inlet HPT Superheat

Steam 150 540 150 150 540

2 Steam Outlet HPT and

Inlet Re-heater

Superheat

Steam 38 340 38 38 340

3 Steam Outlet Re-heater and

inlet IPT

Superheat

Steam 38 540 38 38 540

4 Steam Outlet IPT and inlet LPT Superheat

Steam

5 6th Extraction HPT and inlet

HPH6

Superheat

Steam 38 340 38 38 340

6 HPH6 Outlet and Inlet HPH5 Water 184 246 184 184 246

7 5th Extraction IPT and Inlet

HPH5

Superheat

Steam 42 326 42 42 326

8 HPH5 Outlet and Inlet Dearator Water 189 200 189 189 200

9 3rd Extraction IPT and Inlet

LPH3

Superheat

Steam 1.7 220 1.7 1.7 220


LPH2 Water 123 123

11 2nd Extraction LPT and Inlet

LPH2

Superheat

Steam -0.28 100 -0.28 -0.28 100


LPH1 Water -0.6 94 -0.6 -0.6 94

13 1st Extration LPT Inlet LPH1 Superheat

Steam -0.376 76 -0.376 -0.376 76

14 Drip Outlet LPH1 and Inlet to

Hot-well Water 50 50

15 Exhaust Steam Outlet LPT Superheat

Steam 0.0945 45 0.0945 0.0945 45

16 Condenser Outlet & Inlet Hot-

well Water 0.1 36 0.1 0.1 36

17 Condensed Steam Inlet to

LPH1 Water 11.8 50 11.8 11.8 50

18 Condensate Outlet LPH1 and

Inlet LPH2 Water 11.8 72 11.8 11.8 72




3.5.2 Data Analysis of plant at 480 MW Boiler Section

Sr.


Pressure

(bar)

Tem.

(0C)

Flow

(T/Hr)

Enthalpy

(KJ/Kg)

Energy

(MW)


and Inlet LPH3 Water 150 540 3414.6 0


and Inlet Dearator Water 38 340 652 2574.6 466.2887

21 BFP Inlet Water 38 540 786 3414.6 745.521

22 Condensate Inlet HPH5 Water 1146.6 0


and Inlet HPH6 Water 38 340 2574.6 0


and Inlet Economizer Water 184 246 786 2179.8 475.923

25 Feed Water Inlet Drum

Water 42 326 2515.8 0

26 Steam Inlet LTSH Steam 189 200 0 0

27 Steam Inlet Platen SH Steam 1.7 220 0 0

28 Steam Inlet Final Super

Heater Steam 123 0 0

29 Flue Gas Inlet Re-heater Flue Gas -0.28 100 1566.6 0

30 Flue Gas Inlet Final

Super Heater Flue Gas -0.6 94 1541.4 0

31 Flue Gas Inlet Platen

Super-heater Flue Gas -0.376 76 1465.8 0

32 Flue Gas Inlet LTSH Flue Gas 50 1356.6 0

33 Flue Gas Inlet Economizer Flue Gas 0.0945 45 1335.6 0

34 Flue Gas Inlet APH Flue Gas 0.1 36 1297.8 0

35 Flue Gas To Stack Flue Gas 11.8 50 1356.6 0

36 SA Inlet APH Air 11.8 72 780 1449 313.95

37 SA Inlet Boiler Air 200 290 2364.6 0

38 PA Inlet APH Air 800 36 150 1297.8 54.075

39 PA Inlet Boiler Air 700 278 2314.2 0

40 Coal Supply to Boiler Coal 142 0 0

41 Cold Water Inlet to

Condenser Water 35 1293.6 0

42 Hot Water Outlet From

Condenser Water 46 1339.8 0




Inlet in Boiler

(i) At (40) Coal = 114T/hr

= 114 x 1000/3600 =31.67 Kg./Sec.

Calorific Value = (C.V) of Coal

= 4860 K Cal/Kg

Energy = 4860 x 31.67 x 4.2/1000 =

646.45 MW

(ii) At (2) Energy = 482.74 MW

(iii) At (24) Energy = 428.04

MW

Outlet from Boiler

(iv) At (1) Energy = 692.01 MW

(v) At (3) Energy =634.73MW

(vi) Flue Gases (These are not taken in

consideration)

Total Inlet= (i) + (ii) + (iii) = 646.45 + 482.74

+ 428.04

= 1557.23

MW

Total Outlet = (iv) + (v) + (vi) = 692.01 +

634.73 + 0

= 1326.74

MW

Loss in Boiler = Inlet – Outlet = 1557.23

- 1326.74

= 230.49

MW

Efficiency of Boiler = 1326.74 x 100/

1557.23

= 85.20 %

Section Turbine & Gen.

HPT Inlet (1) = 692.01 MW

Outlet (2) + (5) = 482.74 + 42.22

= 524.96 MW

Net Energy at HPT= 692.01 – 524.96

= 167.05 MW

(ii) IPT Inlet (3) = 634.73 MW

Outlet (4) + (7) = 436.11+32.34

= 468.45 MW

Net Energy at IPT = 634.73 – 468.45

= 166.28 MW

(iii)LPT Inlet (4) = 436.11 MW

Outlet (9) + (11) + (13) = 13.45 +

9.73 + 9.85

= 33.03 MW

Net Energy at LPT = 436.11 – 33.03

= 403.08 MW

Net Input at Turbine (HPT, IPT & LPT)

= 167.05 + 166.28 + 403.08

= 736.41 MW

Efficiency of Turbo Generator

= 232 x 100/ 736.41 = 31.50 %

Section Condenser:

Condenser Efficiency= Actual Cooling Water

Temp rise

Max Possible Temp. Rise

= (T18 – T17) x100

T 13 – T17

= (37 – 30) x100

45 – 30

= 46.67 %

Section Heaters (LP & HP)


T 13 – T17

= 71 - 45

97 – 45

= 0.50


T 11 – T18

= 89 - 71

218 – 71

= 0.12


T 9 – T19

= 117 - 89

303 – 89

= 0.13


T 7 – T22

= 196 - 161

420 – 161

= 0.135


T 5 – T23

= 238 - 196

330 – 196

= 0.31

Overall station efficiency = Output of

Station x 100

Input of Station




= Energy sent out (KW) .

Fuel burnt (Kg) x Calorific value of fuel (K

Cal/kg)

Fuel burnt (Coal) = 114 T/ Hr

= 31.67 Kg/Sec

C.V = 4860 K Cal/kg

= 4860 x 4.2

= 20412 KW

Heat Input = 20412 x

31.67/1000 = 595.45 MW

Overall Efficiency of Plant = 232 x

100/595.45

= 31.5%

Result: in this research we calculate the overall

efficiency of thermal power plant at different

loads 450 MW and 480 MW . this calculation

shows that the power plant work more

efficiently at higher loads as compared to lower

loads.

References

1. Raask, E Lo, K.L. & Song E, Z.

M.(1969)“ Tube Failures Occurring in

the primary super heaters and repeaters

and in the economizers of coal fired

boilers” Vol.12, 1969, pp no. 185

Optimizing Energy efficiency in

industries by G.G. Rajan (January 2001),

“Energy Loss Control-models”,

2. Pilat, J.Micheel Pinterton, A. (1969)

“Source test Cascade impactor for

measuring the size ducts in boilers”,

Energy Conservation in Coal fired

boilers Vol. 10,1969, Page No.(410-418)

3. Schulz,E, Worell, E & Blok, K. “Size

distribution of submission particulars

emitted from Pulverized coal fired plant”

Energy Conservation in Coal Fired

boilers Vol. 10, 1974, Page No.74-80.

4. Neal, P.W.Lo, K.L. (1980)

“Conventional automatic control of

boiler outlet steam pressure” Energy

Conservation in Coal fired boilers Vol.

16, 1980, Page No.91-98

5. Diez, lgnacio, Lvis Hurt F. Earl (2000)

“Evaluation of customary measurements

and adoption of supplementary

instruments” Energy conservation in coal

fired boilers, Vol.42, 2000, Page

No.1100-1110.

6. Dognlin, Chen James, D & Varies B.de

(2001) “Review of current combustion,

technologies for burning pulverized

coal”, Energy conservation in coal fired

boilers Vol.48, 2001, Page No. 121-131.

COMPARISON OF EFFICIENCY ON DIFFERENT LOAD DURING ENERGY AUDIT OF THERMAL POWER PLANT

Documents

Transcript of COMPARISON OF EFFICIENCY ON DIFFERENT LOAD DURING ENERGY AUDIT OF THERMAL POWER PLANT