“A CASE STUDY OF MTPS, DVC”
OPTIMUM CONDENSER PRESSURE FOR
BETTER TURBINE OPERATION AND
PERFORMANCE WITH REDUCTION IN GHG
Damodar Valley Corporation
Presented by :
1.
2.
3.
4.
Dr. Jagannath Munda, Sr. Divisional Engineer (Mechanical)
Mr. Arjunlal Mandal, Sr. Divisional Engineer (Mechanical)
Ms. Kalyani Pyne, Executive Engineer (Electrical)
Mr. Sumit Anand, Executive Engineer (Mechanical)
POWER GENERATING INSTALLATIONS
THERMAL POWER STATIONS & HYDEL POWER STATIONS
Bokaro TPS-A
Koderma TPS
Bokaro’B’ TPS
Maithon DAM
MPL, JV
Tilaiya DAM
Durgapur TPS
Durgapur STPS
KONAR DAM
BPSCL, JV
Chandrapura TPS
Panchet DAM
Mejia TPS
Raghunathpur TPS Ph-I &
II
GENERATION CAPACITY:COMMISSIONED
Type of Power
Thermal Power
(DVC)
(Commissioned
Units)
Station
Mejia TPS
Bokaro TPS ‘B’
630 (3X210)
890 (3X130+2x250)
Durgapur TPS
350 (1X140+1X210)
DSTPS
1000 (2x 500)
KTPS
1000 (2x 500)
6210
Maithon Hydel Station
63.2 (2X20 + 1x23.2)
Panchet Hydel Station
80 (2X40)
Tilaiya Hydel Station
4 (2X2)
Total Hydel
Total DVC Generation Capacity
Thermal(JV)
2340 (4X210+2X250+2x500)
Chandrapura TPS
Total Thermal
Hydel Power
(DVC)
Capacity (MW)
BPSCL
147.2
6357.2
338
MPL
1050 (2x 525)
Total DVC Generation Capacity including JV
7745.2
GENERATION CAPACITY:COMMISSIONED
Name of Thermal Power
Station
Mejia Thermal Power
Station
Durlavpur, Bankura, West
Bengal
2340 = (4X210+2X250+2x500)
MW
Station
Dt. Of
commission
Unit
Capacity (MW)
Unit # 1
Dec.1997
210
Unit # 2
Mar.1999
210
Unit # 3
Sep.1999
210
Unit # 4
Feb.2005
210
Unit # 5
Feb.2008
250
Unit # 6
Sep.2008
250
Unit # 7
Aug.2011
500
Unit # 8
Aug.2012
500
INTRODUCTION

The electricity generated from TPP constitutes 68.14 % of total generation. India’s
present total installed capacity is 308834.28MW out of which 214003.90MW is
thermal and majority of which 187802.88MW is coal fired.
Modified Rankine Cycle is used in thermal power
plant.
Inefficient cyclic
greenhouse gases
operation
produce
more

India ranks fourth among the top emitter of greenhouse gases and contributes
6.96% of the total emission.

By adopting best practices in operation through energy and exergy analysis
specific coal consumption can be reduced.

This study is being carried out by analysing the data of 500MW Mejia Thermal
Power Plant, DVC at different condenser pressures .
SCHEMATIC DIAGRAM OF 500MW TPP
CV
Theory
The control volumes on which analyses have been done are clearly marked by dotted line
in schematic diagram. In the present analysis, the turbine heat rate and total exergy at
turbine inlet in a control volume is evaluated as below.
STEAM I/L TO
TURBINE
(HP+IP)
CONTROL VOLUME (TURBINE +
GENERATOR)
GEN OUT PUT
(MW)
TURBINE HEAT RATE CALCULATION
Turbine Heat rate (THR) is
commonly used to measure the turbine efficiency in a
steam power plant. It is defined as "the energy input to turbine (in Kcal) divided by the
electricity power generated, (in kW). Heat rate is simply the inverse of efficiency.
Turbine Heat Rate (THR)
= (Heat Added to Feed Water + Heat added to SH Attemperation + Heat Added
CRH + Heat added to RH Attemperation) /(Unit load)
mfw (h1 – h11) + msh_spray (h1-h11)+m2 (h3 - h2 )+ mrh_spray(h3-h18)
= -------------------------------------------------------------------Unit Load
There are two provision of SH attemperation:
a) HPH out let,
b) Kicker stage of boiler feed pump.
…Eqn1
Calculation of Reheat Steam Flow
CRH flow is calculated as follow:
CRH Flow (m2) = Steam Flow (m1) – Extraction Steam Flow (m19) to HPH - HPT
Leak Off Steam flow
…..Eqn2
a) Leak off steam flow derived from design leak off flow as per load from HBD.
b) Extraction flow to all HP Heaters having extraction from HP Turbine exhaust to be
considered for computing CRH Flow.
Calculation of Extraction Steam Flow in HPH#6A/6B
mfw (h11 – h20) + m21h21
(m2) = -----------------------------(h19 – h21)
…..Eqn3
Exergy calculation at turbine inlet
The specific thermo-mechanical exergy (neglecting kinetic and potential energy) is
evaluated from the following equation:
ej=(hj─ h0) – T0(sj – s0)
..…Eqn4
where, ej: specific exergy, hj: Enthalpy at jth state, h0: enthalpy at zero state or
atmospheric condition, T0: temperature enthalpy at zero state or atmospheric
condition, sj: Specific entropy at jth state,
s0:Entropy at zero state or atmospheric condition.
The total rate of exergy in a stream is obtained from its specific value as
Total exergy,
E j = mj e j
Where, mj: mass flow rate.
…Eqn5
VARIATION OF TURBINE HEAT RATE WITH LOAD
Turbine heat rate decreases with increase in load. At lower load throttling loss
increases due to lesser steam flow into the turbine. Turbine inlet steam pressure
decreases at lower load, causes entropy generation or exergy destruction.
Four different sets of data at the maximum unit load in different
condenser pressure have been collected and tabulated in table 1.
Parameters
Value
Value
Value
Value
Condenser pr(ksc)
0.0640
0.0717
0.0810
0.1030
Load(MW)
502.60
500.35
500.51
502.00
Main Steam Pr -R (ksc)
174.9
174.6
174.16
175.8
Main Steam Pr -L (ksc)
174.9
174.6
174.16
175.8
Main Steam Temp -R (oC)
540.5
538.8
537.16
533.48
Main Steam Temp -L (oC)
540.5
538.8
537.16
533.48
Main Steam Flow (TPH)
1608
1604.3
1604.63
1632
Feedwater Flow(TPH)
1611
1602.2
1595.37
1653
FW Temp. HPH #5A inlet(oC)
168
168.1
168.7
168.09
FW Temp. HPH #5B inlet(oC)
168
168
168.56
168.5
FW Temp. HPH #5A Outlet(oC)
208.5
208.5
208.97
209
FW Temp. HPH #5B Outlet(oC)
209
209.1
209.63
209.6
FW Temp. HPH #6A Outlet(oC)
256
257.2
257.4
257
FW Temp.HPH #6B Outlet(oC)
259.2
259.5
259.77
259
FW Pr. HPH #5 Inlet(ksc)
203
201.5
201.65
204
FW Pr.HPH #6 Inlet(ksc)
202
199.5
200
204
CRH Steam Temp.(R) (oC)
176.2
176.2
215.5
216
404.6
404.6
351.8
351
17.6
17.8
45.6
45.5
46.18
46.18
359.2
176.3
176.7
216.1
216.4
403.7
403.6
350.2
349.5
17.9
18.1
45.8
45.9
46.9
46.9
357.7
176.58
177.13
216.26
216.52
410.01
409.97
353.5
352.73
17.84
18.08
45.53
45.48
46.22
46.22
361.29
176.4
177
217
217
401.4
401
346
345.6
17.6
17.8
46.2
46.15
47
47
353.7
CRH Steam Temp.(L) (oC)
HRH Steam pr.(R)(ksc)
HRH Steam pr.(L)(ksc)
HRH Steam Temp.(R)(oC)
HRH Steam Temp.(L)(oC)
SH spray water flow (TPH)
SH spray water Temp(oC)
SH spray water pr.(ksc)
359.2
357.7
361.29
353.7
45.03
45.03
529.3
528.6
9.17
240
198.7
45.3
45.3
526.3
526.8
27.8
250.5
198.3
44.99
44.99
534.16
534.13
38
251.8
197.37
45.76
45.76
523.4
523.86
17
251
200
HPH #5A drain Temp(oC)
HPH #5B drain Temp(oC)
HPH #6A drain Temp(oC)
HPH #6B drain Temp(oC)
HPH #5A Ext Steam Temp(oC)
HPH #5B Ext Steam Temp(oC)
HPH #6A Ext Steam Temp(oC)
HPH #6B Ext Steam Temp(oC)
HPH #5A Ext Steam Pr(ksc)
HPH #5B Ext Steam Pr(ksc)
HPH #6A Ext Steam Pr(ksc)
HPH #6B Ext Steam Pr(ksc)
CRH Steam pr.(R)(ksc)
CRH Steam pr.(L)(ksc)
EFFECT OF CONDENSER PRESSURE ON TURBINE HEAT RATE AT FULL LOAD
Turbine heat rate decreases with decrease in condenser pressure as cycle efficiency increases. It
became minimum at 0.078 kg/cm2. With further decrease in condenser pressure, exit turbine loss
increases, as steam from last stage of LP turbine is directly damped into the condenser without
doing any useful work.
Sl. No.
1.
2.
3.
4.
Unit load: 500MW
Condenser
Pressure
(Kg/cm2)
0.0640
0.0717
0.0801
0.1030
Turbine Heat
Rate (Kcal/kwh)
2028
2020
2015
2042
Table:2
Figure-4
EFFECT OF CONDENSER PRESSURE ON TOTAL EXERGY AT TURBINE INLET
TO GENERATE 500MW
At design condenser pressure, i.e., at 0.1033 kg/cm2 total exergy requirement at turbine inlet is
maximum and decreases with reduction in condenser pressure due to improvement in working
cycle efficiency. It became minimum at around 0.078 kg/cm2 and again increases with further
reduction in condenser pressure as exit steam loss increases.
Sl.
N
o.
1
2
3
4
Unit load: 500MW
Unit
load
500MW
0.0640
Total
Exergy at
Turbine
Inlet (Kcal)
9453750.4
500MW
0.0717
9417284.9
500MW
0.0801
9401233.7
500MW
0.1030
9534858.2
Condenser
Pressure
(Kg/cm2)
Table:3
Fig.5
EFFECT OF CONDENSER PRESSURE ON THR WITH AT 380MW UNIT LOAD.
SL. NO.
1
Unit load: 380MW
Condenser Pressure
(kg/cm2)
Turbine Heat
Rate
(Kcal/Kwh)
0.0465
2050
0.0563
2045
0.0669
2056
0.0853
2082
2
3
4
Turbine heat rate (Kcal/Kwh)
Tab.:4
2085
2080
2075
2070
2065
2060
2055
2050
2045
2040
0.04
0.06
0.08
Condenser pressure (kg/cm2 )
Fig.:6
0.1
THR decreases with increase
in condenser pressure. THR
became minimum at around
0.055 kg/cm2 cond. Pr. THR
increases
with
further
reduction
in
condenser
pressure as exit steam velocity
increases and steam is
damped into the condenser
without doing any useful work.
INFLUENCE OF CONDENSER PRESSURE ON TURBINE VIBRATION
Influence of condenser pressure on turbine
vibration (at unit load: 380MW)
Influence of condenser pressure on turbine
vibration (at unit load: 500MW)
GHG EMISSION REDUCTION
THR improvement by optimising condenser pressure is
directly related to reduction in greenhouse gas emission.

At 0.103 kg/cm2 cond. pressure THR was obtained
2042 Kcal/Kwh.

At 0.0801 kg/cm2 THR obtained 2015 kcal /kwh.
Deviation in HR=(2042-2015)= 27Kcal/kwh
Total Energy saved in a year if unit is considered to run 365*24 days in full load
with 34% plant efficiency,
=500*365*24*1000*27/0.34= 347823529411.76 Kcal
Average GCV of coal=3600 Kcal/Kg.
So total coal saving in a year =96617647.06 kg =96617.64706 ton, considering
42.8 % of carbon by weight in 1 kg of coal.
CO2 emitted by burning 1kg of coal=(mol wt. of CO2/mol wt of
Carbon)*percentage of carbon by wt in per kg of coal = (44/12)*0.428=1.498kg
So total CO2 emission reduction = 144733.24 ton/year.
CONCLUSION

The country is committed to the development of clean coal technology
applications to mitigate climate impacts in a way that is consistent with
sustainable development.

Power generators have wide latitude in designing their strategies to reduce
emissions. Viable means for substantially reducing specific CO2 emissions from
coal-fired power generations need to be developed and widely adopted by
implementing best practices in operation.

Through our study, by adopting best practices in operation at MTPS through
energy and exergy analysis at different condenser pressures, specific coal
consumption got reduced, and hence total CO2 emission reduced to
144733.24 ton/year.

This study also analyze the effect of condenser pressure on turbine health in
terms of TG vibration and optimum value has been found out for lower TG
vibration.

Exergy and energy analysis to be carried out at site to re-optimise the various
influential parameters for better efficiency and finally to mitigate global
climate change through reduction in GHG emission.