BENCHMARKING OF KEY AREAS OF
DAHANU POWER STATION
IN
MAHARASHTRA
PERIOD OF VISIT : 17.02.05 TO 19.02.05
I.
BRIEF DESCRIPTION OF THE PLANT
• Dahanu Power Station (DTPS) of Reliance : Installed capacity 500 MW (2 x 250 MW), 135 Km away
from Mumbai city in Thane district.
• Commissioned : Unit 1 - July 1995, Unit 2 - January 1996
• Project started in 1989, cost is Rs 1240 crore
• The transmission project cost is Rs 235 crore
• Total land area
Plant area
Ash Disposal area
Colony area
II.
:
:
:
:
821.58 hectare
351.58 hectare
370 hectare (3 ash ponds at present, 4th one being constructed)
100 hectare
SCOPE OF BUSINESS
• DTPS provides power to North Mumbai
• Maximum System requirement is approx 1300 MW
• The shortfall in supply of demand is met by import of power from Tata Power
III.
•
GENERATION COST BREAKUP
Generation cost breakup for 2003-04 is as follows :
Fuel Cost
Staff Cost
O&M Cost
Insurance
Interest
Depreciation
IV.
:
:
:
:
:
:
71.61%
3.23%
5.81%
0.65%
0.65%
18.06%
OPERATION
A. HEAT RATE
•
MERC approved Heat Rate for 2004-05 is 2319 Kcal/Kwh
•
Heat Rate for 2004-05 (till Jan ‘05) is 2260 Kcal /Kwh
•
GCV of as-fired coal is found out (coal sampling is done at the time of bunkering). Coal consumption is
found out from feeder totaliser readings. Heat rate is thus calculated.
1
Boiler efficiency is found out from loss method on a daily basis. Cycle efficiency is then found out.
Heat rate is calculated like this also for cross checking.
B. COMBUSTIBLES IN ASH
•
•
Combustibles in Fly Ash is 0.6 to 0.8% (design value is 1%)
•
Combustibles in Bottom Ash is 3 to 4% (design value is 5%)
C. OTHER PARAMETERS
•
Other parameter trends is as follows :
PLF (%)
PAF (%)
Loading
Factor (%)
Auxiliary
(%)
Heat Rate
(Kcal/Kwh)
Oil Rate
(ml/Kwh)
Coal Rate
(Kg/Kwh)
DM Make
Up (%)
No of
outages
Trippings
per 1000 hr
running
1998-99
(Actual)
1999-00
(Actual)
2000-01
(Actual)
2001-02
(Actual)
2002-03
(Actual)
2003-04
(Actual)
76.55
92.24
88.68
98.42
82.68
92.33
87.83
93.02
90.53
91.03
100.34
97.94
2004-05
(Actual)
(till
Jan05)
100.99
96.58
82.99
90.10
89.55
94.42
99.45
102.45
104.57
103.00
7.44
7.04
7.20
7.82
7.43
7.34
7.54
7.34
2337
2313
2313
2320
2312
2319
2260
2319
0.50
0.48
0.27
0.17
0.31
0.12
0.127
0.2
1998-99
(Actual)
1999-00
(Actual)
2000-01
(Actual)
2001-02
(Actual)
2002-03
(Actual)
2003-04
(Actual)
2004-05
(Actual)
(till Jan05)
-
0.565
0.538
0.534
0.545
0.526
-
1.25
0.9
0.69
0.74
0.67
0.39
0.37
-
9
26
10
17
6
6
-
0.2892
1.2982
0.2455
0.627
0.117
-
2004-05
(MERC
approved)
98.77
95.89
•
MERC has not allowed backing down of DTPS units when demand is more than generation capacity. The
balance requirement of power over and above generation capacity can only be bought from TPC
•
DTPS operates each unit at around 262 MW, which is higher than the rated capacity of 250 MW. The
unit is being operated within the parameters specified by the equipment manufacturers and no
technical limits are being violated.
•
Both the units have once-through condenser cooling system
2
V.
FUEL AND FUEL HANDLING PLANT
•
Raw coal is procured from Dipka/Gebra collieries (Gr F) of SECL. DTPS receives washed coal from
SBCWL (ST-BSES Coal Washeries Ltd) Coal Washery project at Jamnipalli, Korba, MP. This Washery
project is a joint venture between BSES Ltd (now Reliance Energy Ltd) & Spectrum Technologies,
USA. Cost of washing is approx Rs 100 /Te and yield is 80%.
•
Imported coal is procured from Indonesia (Kideco & Adaro collieries) and China only in the months of
October to April because of rough sea condition in the other months
•
Coal comes from Indonesia by ship, which anchors in the high sea. It is then brought to the jetty (16
km away) alongside DTPS by barges (500 – 1000 Te capacity). Dumpers then bring the coal to the
plant stock yard (3 km away). The handling charge from ship to stock yard is approx Rs 250 /Te.
•
Washed coal and imported coal is blended in the ratio of 80 : 20
•
Design coal characteristic of DTPS is as follows (Source : BHEL Data Sheet on Dahanu) :
Proximate Analysis
Inherent Moisture (%)
Volatile Matter (%)
Ash (%)
Fixed Carbon (%)
HHV (kcal/kg)
HGI
•
Design Coal
10
19
40
31
3700
55
Best Coal
10
22
34
34
4160
58
Worst Coal
20
17
40
23
3000
50
Imported coal characteristic is as follows :
Proximate Analysis
Total Moisture (%)
25
Inherent Moisture (%)
12
Ash (%)
2.5
Sulphur (%)
0.15
GCV (kcal/kg)
5700
•
Calorific value of fuels for 2003-04 and 2004-05 is as follows :
2003-04
Wtd Avg Coal Calorific
Value (Kcal /Kg)
Wtd Avg Secondary
Oil Calorific Value
(Kcal /L)
Actual
MERC approved
2004-05
MERC approved
4306
4306
4500
9739
9739
10619
3
•
In 2004-05, as approved by MERC, landed cost of washed coal is Rs 2184 /Te and that for imported
coal is Rs 2360 /Te
•
The trends in actual coal price as submitted in the petition to MERC is as follows :
Fuel
Raw Coal
Washed
Coal
Imported
Coal
Coal
Basket*
* Coal
Unit
1998-99
1999-00
2000-01
Rs /MT
1558
1596
1496
Rs /Gcal
428
447
402
Rs /MT
1933
1927
Rs /Gcal
619
458
Rs /MT
2519
2561
2801
Rs /Gcal
426
484
441
Rs /MT
1815
1884
2003
Rs /Gcal
427
489
450
basket includes washed coal and imported coal
2001-02
2002-03
2003-04
1926
464
2661
499
2038
470
1645
467
1985
481
2056
387
1968
457
1638
1915
1691
1864
433
2004-05
(MERC
approved)
2219
433
NB : MERC has approved the actual values in 2003-04
•
The fuel cost of generation as approved by MERC for 2003-04 and 2004-05 is Rs 1.01 /Kwh
•
Unloading of rakes is carried out in 2 Rotary Wagon Tipplers (Elecon make) with Beetel chargers.
There are also 2 shunting locomotives. Free time for unloading is 10 hours and demurrage paid is
almost nil.
•
The wagon tipplers have Avery make electronic weighbridges.
•
The Fuel Handling Plant operation and maintenance is done by contract personnel in 3 shifts
•
There are 4 coal stock yards each of capacity 1 lakh tonnes. Proposal for another stockyard of 1 lakh
Te capacity has already been placed with the higher management.
•
There are 2 stacker /reclaimers in the stock yard. Washed coal and imported coal is stacked
separately. 3 dozers are also used for reclaiming coal through reclaim hoppers.
•
As on 19.02.05, the total coal stock was 354473 Te (washed coal - 181513 Te and imported coal –
172959 Te)
VI.
•
MAINTENANCE
General schedule of Turbine overhauling is as follows :
HP and IP turbine
LP turbine
Generator
– every 6 years
- every 2 years
- after 20000 running hours
4
•
Overhaul details of various units of DTPS are as follows :
Unit 1
Unit 2
2004-05
2003-04
2002-03
2001-02
2000-01
-
18
-
35
7
HP+IP+LP+Gen+Blr
Blr
-
11
LP+Gen+Blr
15
-
LP+Gen+Blr
31
HP+IP+LP+Gen+Blr
Blr
•
The turbine overhaul is carried out wholly by M/s BHEL, who hires all the contract personnel needed
for the job (cost incurred recently is approx Rs 90 lakh for LP + Generator overhauling job)
•
DTPS personnel are engaged in overall supervision of the turbine overhauling while the boiler
overhauling is being done by themselves (cost approx Rs 11-12 lakh for labour part).
•
The total overhaul cost is approx Rs 4 to 5 crores (labour + material)
•
DTPS has spares available for boiler and turbine overhauling till 2005-06
•
Total inventory holding is about Rs 17 crores
•
The R&M Expenses as approved by MERC for 2004-05 is Rs 63.81 crores while expenditure done in
2003-04 and approved by MERC was Rs 78.26 crores.
•
All the maintenance departments work in general shifts. A skeletal gang consisting of 6 Engineers
from Mechanical (4), Electical (1) and C&I (1) along with a handful of non-executives are there on duty
beyond 17.30 hrs till 08.30 hrs next morning.
VII.
DIFFERENT O&M PRACTICE
•
After a forced shutdown (e.g. tube leakage of boiler), the boiler is vented to atmosphere and the
drum metal temperature comes down to maximum 110 deg C within 5 hours. This is achieved by
keeping the HP & LP bypass of the turbine open while forced cooling by draught fans is also being
carried out. Maximum difference that occurs between top and bottom drum metal temperature is 70
deg C.
•
After about 12 hours of shutdown, when turbine inner casing temperature is about 370 deg C, the
barring gear is stopped, lubricating oil pumps are stopped, jacking oil pump continues to run and
blanking of oil pipelines to the generator bearings is carried out (process takes about 15 min).
The generator is now decoupled from the turbine. During the decoupling process, hand barring is
being done regularly. By this process the Generator overhauling job can start from the second day
itself, thereby saving time.
5
•
During overhauling of the boiler, tube thickness gauging is carried out by DTPS Engineers by hand
only. If slight erosion is observed, then the necessary part is replaced. In the burner corners, the
first 5 tubes are always changed.
VIII. ENVIRONMENT
•
DTPS has an ESP of collection efficiency 99.9%.
The ESP has 4 passes, 6 fields per pass and 2 hoppers per field
•
On line SOx, NOx and TPM monitoring is installed
•
4 ambient air quality monitoring stations are positioned within a radius of 25 km to monitor pollution
parameters
•
A mobile pollution testing van is also there
•
The SOx emission limit set by MERC is 80.4 TPD.
IX.
ADMINISTRATION
•
Headed by a Vice President who is the Plant Manager
•
There are approx 200 executives and 300 non-executives working in the plant. About 500 contract
personnel support them
6