Thermal power Plants
Environmental Regulations ON THERMAL POWER STATIONS
A : Coal Based Thermal Power Plants
Standards for discharge of liquid effluents
S.
No.
Source
Pollutants
Concentration
(i)
Condenser
cooling water
(once through
cooling system)
pH
6.5-8.5
Temperature
More than 10°C than the intake water
temperature
Free available
Chlorine
0.5 mg/l
(ii)
Boiler blow down
Suspended
solids
100 mg/l
Oil and grease
20 mg/l
Copper (total)
1.0 mg/l
Iron (total)
1.0 mg/l
(iii)
Cooling tower
blow down
Free available
Chlorine
0.5 mg/l
Zinc
1.0 mg/l
Chromium
0.2 mg/l
Phosphate
5.0 mg/l
Other corrosion
inhibiting
materials
Limit to be established on case by case basis
(iv)
Ash pond
effluent
pH
6.5-8.5
SS
100 mg/l
Oil & grease
20 mg/l
No limits for heavy metals are given at present
Temperature Limit for discharge of Condenser Cooling Water from Thermal Power plant
A. New thermal power plants commissioned after June 1, 1999.
New thermal power plants, which will be using water from rivers/lakes/reservoirs, shall install cooling
towers irrespective of location and capacity. Thermal power plants which will use sea water for cooling
purposes, the condition below will apply.
B. New projects in coastal areas using sea water
The thermal power plants using sea water should adopt suitable system to reduce water temperature
at the final discharge point so that the resultant rise in the temperature of receiving water does not
Rise in temperature of condenser cooling water from inlet to the outlet of condenser shall not be more
than
10o C.
D. Guidelines for discharge point:
1. The discharge point shall preferably by located at the bottom of the water body at mid-stream
for proper dispersion of thermal discharge.
2. In case of discharge of cooling water into sea, proper marine outfall shall be designed to
achieve the prescribed standards. The point of discharge may be selected in consultation with
concerned State Authorities/NIO.
3. No cooling water discharge shall be permitted in estuaries or near ecologically sensitive areas
such as mangroves, coral reefs/spawning and breeding grounds of aquatic flora and fauna.
(ii) Emission Standards
Power generation capacity (MW)
Particulate matter emission
Less than 210 MW
350 mg/Nm3
210 MW or more
150 mg/Nm3
Note:
Depending upon the requirement of local situations, which may warrant stricter standards as in case of
protected areas the State Pollution Control Board and other implementing agencies within the
provisions of the EPA, 1980 may prescribe limit of 150 mg/Nm3 irrespective of the generation capacity
of the plant.
Andhra Pradesh Pollution Control Board and Delhi Pollution Control Committees have stipulated
stringent standards of 115 and 50 mg/Nm3 respectively for control of particulate matter emission.
(iii) Stack Height Requirement
In order to proper dispersion of SO2 emissions from thermal power plants, stack height criteria have
been adopted in the country. However, for larger capacities of boilers (500 m and above), space
provision for installing FGD system has been recommended;
Power generation capacity
Stack height (metre)
Less than 200/210 MW
H = 14(Q) 0.3
where Q is emission rate of SO2 in kg/hr,
H = Stack height in metre
200/210 MW or less than 500 MW
220
500 MW and above
275
Note :
The power plants sanctioned by CEA earlier to July 1, 1994 may not be required to increase existing
stack height as per regulation notified, vide Government of India notification no. GSR 742(E) dated
August 30, 1990 subject to following conditions:
• The ambient sulphur dioxide and NOx concentrations around the power plant is less than 1/3 th
prescribed ambient air quality standard for SO2 and Nox for the concerned area.
• For (1) the power plant shall install adequate number of air quality monitoring stations in and around
the power stations. The stations should be selected in consultation with the CPCB/SPCB.
( Vide office Memorandum No B-34011/1/01/PCI-II dated January 10, 1996 )
(iv) Use of beneficiated coal
In order to minimize flyash generation, it was recommended to use beneficiated coal in the power
plants. The Ministry of Environment & Forests, Govt. of India has promulgated Gazette Notification
(GSR 560(E) & 378(E), dated September 19, 1997 and June 30, 1998 respectively) on use of
beneficiated/blended coal containing ash not more than 34 percent w.e.f. June 2002 in the following
power plants :
• any thermal power plant located beyond one thousand kilometers from the pit-head and
• any thermal power plant located in urban area or sensitive area or critically polluted area irrespective
of their distance from pit-head except any pit-head power plant”.
The power plants using FBC( CFBC,PFBC & AFBC) and IGCC combustion technologies are exempted
to use beneficiated coal irrespective of their locations.
(v) Utilisation of Flyash
In order to make mondatory use of flyash and flyash based products by the brick kilns, Thermal Power
Stations and CPWD& State PWDs , vide notification no. S.O. 763(E) dated September 14, 1999,
Ministry of Environment & Forests has issued directions under sub-rule 3 of rule 5 of EPA, 1986 that
• No person, located within 50 km radius of any Thermal Power Station, shall to manufacture clay
bricks, tiles or blocks without mixing atleast 25% flyash or pond ash with soil.
• Thermal Power Plants shall submit action plan for hundred percent utilization.
New Plants
30% within three yrs
100% within 9 yrs
Existing Plants
20% within three yrs
100% within 15 yrs
Existing notification on utilisation of flyash was amended vide notification no S.O. 979(E) , dated
August 27, 2003 .by Ministry of Environment & Forests incorporating
• No person shall within a radius of 100 kms from thermal power plants, manufacture clay bricks, tiles
or blocks without mixing atleast 25% of flyash or pond ash with soil.
• Every construction Agency including private sector builders within a radius of fifty to one hundred
kilometers from coal or lignite based thermal power plant shall use minimum of following percentage of
ash based products such as: bricks, block & tiles in their construction work:
25% by 31 st August, 2004
50% by 31 st August, 2005
75% by 31 st August, 2006
100% by 31 st August, 2007
In respect of construction of buildings within a radius of fifty kilometers from coal or lignite based
thermal power plant the following minimum percentage of use of bricks, blocks and tiles shall apply:
75% by 31 st August, 2004
100% by 31 st August, 2005
• Authority sanctioning or renewing mining lease shall not grant or extend the lease if the manufacturer
does not use the 25% of the Flyash in the manufacturing of bricks, blocks and tiles.
• Utilisation of Flyash for reclamation of sea subject to compliance of the rules made under the EPA,
1986.
B: Gas/Naptha based Thermal Power Plants
(i) Emission standards for NOx
(a) For existing units 150 ppm (v/v) at 15% excess oxygen
(b) For new units with effect from 1-6-1999.
Generation capacity of gas
turbine
Limit for NOx emission (v/v), at 15% excess
oxygen)
(a) 400 MW and above
(i) 50 ppm for the units burning natural gas.
(ii) 100 ppm for the units burning naphtha
(b) Less than 400 MW but upto
100 MW
(i) 75 ppm for the units burning natural gas
(ii) 100 ppm for the units burning naphtha
(c) Less than 100 MW
100 ppm for units burning natural gas or
naphtha as fuel
(d) For the plants burning gas
in a conventional boiler.
100 ppm
(ii) Stack height H in m should be calculated using the formula H= 14 Q 0.3 , where Q is the emission
of SO2 in kg/hr, subject to a minimum of 30 mts.
(iii) Liquid waste discharge limit
Parameter
Maximum limit of concentration (mg/l except for
pH and temperature)
pH
6.5 - 8.5
Temperature
Free available
chlorine
Suspended solids
Oil & grease
Copper (total)
Iron (total)
Zinc
Chromium (total)
Phosphate
As applicable for other thermal power plants
0.5
100.0
20.0
1.0
1.0
1.0
0.2
5.0
C: Liquid fuel based Thermal Power Plants
(i) Emission Standards for Diesel Engines (Engine Ratingmore Than 0.8 Mw (800 Kw) for Power
Plant, Generator Set applications and other requirements
Parameter
Area
Category
Total engine
rating of the
plant
(includes
existing as
well as new
generator
sets)
Gerator sets commissioning date
Before
1/7/2003
Between
1/7/2003 and
1/7/2005
On or
after
1/7/2005
Nox (as NO2 ) (at 15% O2 ),
dry basis, in ppmv
A
Upto 75MW
1100
970
710
B
Upto 150MW
A
More than
75MW
1100
710
360
B
More than
150MW
NMHC (as C) (at 15% O2 ),
mg/Nm3
Both A and B
150
100
PM (at 15%
O2 ), mg/Nm3
Diesel Fuels -
HSD & LDO
Both A and B
75
75
Furnace Oils
- LSHS & FO
Both A and B
150
100
CO (at 15% O2 ), mg/Nm3
Both A and B
150
150
Sulphur content in fuel
A
<2%
B
<4%
Fuel specification
For A only
Up to 5MW
Only Diesel Fuels (HSD, LDO) shall be
used.
Stack height (for generator
sets commissioned after
1/7/2003)
Stack height shall be maximum of the following, in meter:
I. 14 Q 03 , Q = Total SO2 emission from the plant in kg/hr
II. inimum 6 m above the building where generator set is installed.
III. 30 m.
Note: 1. Acronyms used
MW : Mega (106 ) Watt, FO : Furnace Oil, NOX : Oxides of Nitrogen HSD : High Speed Diesel, NO2 :
Nitrogen Dioxide, LDO : Light Diesel Oil, O2 : Oxygen , LSHS : Low Sulphur Heavy Stock, NMHC :
Non- Methane Hydrocarbon kPa : Kilo Pascal, C : Carbon, mm : Milli (10 -3 ) metre, PM : Particulate
Matter kg/hr : Kilo (103 ) gram per hour, CO : Carbon Monoxide, mg/Nm3 : Milli (10 -3 ) gram per Normal
metre cubic, SO2 : Sulphur Dioxide , ppmv : part per million (10 6 ) by volume
2. Area categories A and B are defined as follows
Category A: Areas within the municipal limits of towns/cities having population more than 10 lakhs and
also upto 5 km beyond the municipal limits of such towns/cities.
Category B: Areas not covered by category A.
3. The standards shall be regulated by the State Pollution Control Boards or Pollution Control
Committees, as the case may be.
4. Individual units with engine ratings less than or equal to 800 KW are not covered by this notification.
5. Only following liquid fuels viz. High Speed Diesel, Light Diesel Oil, Low Sulphur Heavy Stock and
Furnace Oil or liquid fuels with equivalent specifications shall be used in these power plants and
generator sets.
6. For expansion project, stack height of new generator sets shall be as per total Sulphur Dioxide
emission (including existing as well as additional load).
7. For multi engine plants, flues shall be grouped in cluster to get better plume rise and dispersion.
Provision for any future expansion should be made in planning stage itself.
8. Particulate Matter, Non-Methane Hydrocarbon and percent moisture (dry basis). Carbon Monoxide
results -are to be normalized to 25 0 C, 1.01 Kilo Pascal (760 mm of mercury) pressure and zero
9. Measurement shall be performed at steady load conditions of more than 85% of the rated load.
10. Continuous monitoring of Oxides of Nitrogen shall be done by the plants whose total engine
capacity is more than 50 Mega Waft. However, minimum once in six month monitoring for other
parameters shall be adopted by the plants.
11. Following methods may be adopted for the measurement of emission parameters,-
Sl.No.
Emission Parameters
Measurement Methods
1.
Particulates
Gravimetric
2.
SO2
Barium Perchlorate- Thorin indicator method
3.
NOX
Chemiluminescence, Non Dispersive Infra Red, Non
Dispersive Ultra-violet (for continuous measurement),Phenol
disulphonic method
4.
CO
Non Dispersive Infra Red
5.
O2
Paramagnetic, Electrochemical sensor
6.
NMHC
Gas Chromatograph - Flame lonisation Detector
LIST OF THERMAL POWER PLANTS IN INDIA
S. No.
Name
State
Capacity (MW)
1.
Ramagundam, NTPC
Andhra Pradesh
2100
2.
Ramagundam ‘B'
-do-
62.5
3.
Vijaywada
-do-
1260
4.
Rayalseema
-do-
420
5
Simhadri, NTPC
-do-
1000
6.
Nellore
-do-
30
7.
Kothagudem
-do-
1210
8.
Bongaigaon
Assam
740
9.
Barauni
Bihar
320
10.
Kahalgoan
-do-
840
11.
Muzaffarpur
-do-
220
12.
Korba, NTPC
Chhattisgarh
2100
13.
Korba East
-do-
440
14.
Korba [West]
-do-
840
15
Badarpur,NTPC
Delhi
705
16
Rajghat
-do-
135
17.
I.P.Station
-do-
247.5
18.
Gandhinagar
Gujrat
870
19.
Utkai
-do-
850
20.
Wanakbori
-do-
1260
21
Dhuvaran
-do-
534
22.
Sabarmati, AEC
-do-
400
23.
Sikka
-do-
240
24.
Kutch lignite
-do-,
215
25.
Surat Lignite
-do-
250
26.
Faridabad
Haryana
180
27
Panipat
-do-
1150
28.
Raichur
Karnataka
1470
29.
Bokaro ‘B'
Jharkhand
630
30.
Tenughat
-do-
420
31.
Patratu
-do-
840
32.
Bokaro (A)_( Closed0
-do-
33.
Chandrapura
-do-
750
34.
Amarkantak
Madhya Pradesh
290
35.
Birsinghpur
-do-
840
36.
Satpura
-do-
1142.5
37.
Vindhyachal, NTPC
-do-
2760
38.
Trombay
Maharashtra
1330(500)
39.
Khapakheda
-do-
840
40.
Nasik
-do-
910
41.
Koradi
-do-
1100
42.
Bhusawal
-do-
482.5
43.
Chandrapur
-do-
2340
44.
Paras
-do-
62.5
45.
Parli
-do-
690
46.
Ballarshah (closed)
-do-
47.
Dahanu
-do-
500
48.
Talcher (N), NTPC
Orissa
3000
49.
Talcher (old),NTPC
-do-
470
50.
Ib Valley
-do-
420
51.
Bhatinda, GNTP
Punjab
440
52.
GGSSTP,Ropar
-do-
1260
53.
GHTP (Lehra
Mohabbat)
-do-
420
54.
Kota
Rajasthan
1045
55.
Suratgarh
-do-
1250
56.
Ennore
Tamilnadu
450
57.
Tuticorin
-do-
1050
58.
North Madras
-do-
630
59.
Mettur
-do-
840
60.
Neyveli-Lgnite
-do-
2490
61.
Basin Bridge (Closed)
-do-
62.
Singrauli, NTPC
Uttar Pradesh
2000
63.
Rihand, NTPC
-do-
1000
64.
Anpara
-do-
1630
65.
NCTPS – Dadri,NTPC
-do-
840
66.
Panki
-do-
210
67.
Unchahar, NTPC
-do-
840
68.
Tanda
-do-
440
69.
Paricha
-do-
220
70.
Obra A
Obra B
-do
1482
71.
Harduaganj
-do-
515
72.
Farakka,NTPC
West Bengal
1600
73.
Budge-Budge, CESC
-do-
500
74.
Mezia, DVC
-do-
630
75.
Southern, CESC
-do-
135
76.
Barkeshwar
-do-
630
77.
Durgapur (DVC)
-do-
350
78.
Titagarh, CESC
-do-
240
79.
Santaldih
-do-
480
80.
DPL, Durgapur
-do-
395
81.
Kolaghat
-do-
1260
82.
Bandel
-do-
540
83.
Gauirpore (closed)
-do-
THERMAL POWER PLANTS REQUIRED TO USE BENEFICIATED COAL
A. EXISTING
S.
No.
Name of Thermal
Power Station
Capacity
(MW)
Category
+
Estimated Annual
beneficiated Coal
Requirement (MTPA)
1.
Badarpur
705
UA
2.75
2.
Indraprastha
278
UA
0.67
3.
Rajghat
135
UA
0.58
4.
Faridabad
165
UA
0.80*
5.
Panipat (Units 1-5)
650
>1000 km
3.60*
6.
Bhatinda (Units 1-4)
440
>1000 km
1.98
7.
Ropar (Units 1-6)
1260
>1000 km
5.08
8.
NCR Dadri
840
>1000 km
4.00
9.
Harduaganj
425
>1000 km
1.06
10.
Panki
274
U.A.
0.79
11.
Paricha
220
>1000 km
0.89
12.
Kota (Units 1-5)
850
U.A.
3.65
13.
Sabarmati
410
U.A.
1.32*
14.
Wanakbori (Units 1-
6)
1260
>1000 km
6.06
15.
Gandhi Nagar
660
U.A.
3.00*
16.
Ukai
850
>1000 km
3.36*
17.
Sikka (Units 1-2)
240
>1000 km
1.00*
18.
Bhusawal
478
>1000 km
2.24
19.
Koradi
1080
U.A.
5.50*
20.
Nasik
910
>1000 km
3.60
21.
Trombay
1150
U.A.
Oil/Coal
22.
Dahanu
500
S.A.
2.01
23.
DPL
390
CPA
0.49
24.
Muddanur
(Rayalaseema)
420
>1000 km
2.37
25.
North Chennai -I
630
U.A.
2.97
26.
Ennore
450
>1000 km
1.92*
27.
Raichur (1-4)
840
>1000 km
4.38
28.
Mettur
840
>1000 km
4.39
29.
Tuticorin (1-5)
1050
>1000 km
4.08*
30.
Bokaro
820
CPA
1.84
31.
Durgapur
350
CPA
1.00
Sub Total (A)
19570
77.37
B. IX Plan
S.
No.
Name of Thermal
Power Station
Capacity
(MW)
Category
+
Estimated Annual
Coal Requirement
(MTPA)
32.
Bhatinda-5&6
420
>1000 km
1.88*
33.
Wanakbori-7
210
>1000 km
1.00*
34.
Gandhinagar-7
210
>1000 km
0.95
35.
Raichur (5-6)
420
>1000 km
2.14
36.
North Chennai II
1050
U.A.
IC (Imported Coal)
37.
Mangalore
1000
>1000 km
IC
38.
Tranagallu
260
>1000 km
IC
39.
Suratgarh-I
500
>1000 km
IC
Sub Total (B)
4370
8.09
Total coal consumption based on 1999-2000 data upto ix plan 85.46 mtpa
* Revised based on data provided by SEBs/utilities
UA : Urban Area, CPA : Critically Polluted Area, SA: Sensitive Area and
IC : Imported Coal
(Source : Central Electricity Authority)
THERMAL POWER PLANTS WHICH HAVE DRY FLYASH COLLECTION FACILITIES
1. Dahanu, Maharashtra
2. Sabarmati, Gujarat
3. Budge-Budge, West Bengal
4. Titagarh, West Bengal
5. Vizaywada, AP
6. Rayalseema, AP
7. Kothagundem, AP
8. Ramagundem ‘B', AP
9. Nellore , AP
10. Rajghat, Delhi
11. Raichur, Karnataka
12. Singrauli NTPC, UP
13. Vindhyachal, MP
14. Ramagundem, AP
15. *Farakka, West Bengal
16. *Kahalgaon, Bihar
17. *Korba, Chhatisgarh
18. *Talcher (old), Orissa
19. Talcher (Kaniha N), Orissa
20. Badarpur, Delhi
21. Dadri, U.P.
22. Unchahar, U.P.
23. DPL, West Bengal
24. Nasik , Maharashtra
25. Chandrapur, Maharashtra
26. Kota , Rajasthan
27. Ropar, Punjab
28. Bhatinda, Punjab
29. Lehra Mohabbat, Punjab
30. Sabarmati, Gujrat
31. Suratgarh, Rajasthan
32. *Neyveli Lignite Corporation,TN
33. North - Chennai , TN
34. Ib Valley, Orissa
35. Meizia ,WB
36. ** Faridabad , Haryana
37. **Panipat, Haryana
38 Sikka, Gujrat
* : Facility is being provided
**: PFC has sanctioned the scheme, same is being developed
Flyash utilization during 2005-06
State
Name Capacity
Capacity
( MW)
Coal
Cons.
( mta)
Ash Gen.
( mta)
Ash Uti.
( mta)
%
utilisation
Andhra
Pradesh
Nellore
APGENCO
30
0.149
0.065
0.158
243
Andhra
Pradesh
Ramagundam ,
APGENCO
62.5
0.283
0.106
0.073
68.9
Andhra
Pradesh
Ramagundam,
NTPC
2100
11.79
3.887
1.863
47.9
Andhra
Pradesh
Rayalseema,
APGENCO
420
1.519
0.603
0.386
61.3
Andhra
Pradesh
Simhadri, NTPC
1000
4.98
1.765
0.856
48.5
Andhra
Pradesh
Vijayawada ,
APGENCO
1260
6.81
2.646
1.501
56.7
Andhra
Pradesh
Kothagudem
APGENCO
1200
3.639
1.507
Nil
-
Assam
Bongaigaon ,
ASEB
710
Plant
Closed
Bihar
Barauni
240
0.131
0.052
0.058
111.5
Bihar
Muzaffarpur,
BSEB
220
Nil
Nil
-
Bihar
Kahalgaon, NTPC
840
5.848
1.431
0.703
49.1
Chhattisgarh
Korba, NTPC
2100
11.66
4.832
2.288
47.4
Chhattisgarh
Korba West
840
3.975
1.75
0.589
33.6
Chhattisgarh
Korba East,
ChEB
440
2.853
1.28
1.155
90.0
Delhi
I.P. .IPPGENCO
247.5
0.974
0.331
0.157
47.4
Delhi
Rajghat ,
IPPGENCO
135
0.501
0.172
0.157
91.3
Delhi
Badarpur, NTPC
705
3.77
0.128
0.608
475
Gujarat
Ukai, Gujarat
Elect.Board,
850
3.54
1.157
0.471
40.7
Gujarat
Gandhi Nagar,
GEB
870
3.17
0.916
0.597
65.2
Gujarat
Sikka , GEB
240
0.941
0.278
0.17
61.2
Gujarat
Sabarmati, AEC,
Ahmedabad
400
1.773
0.323
0.304
94.1
Gujarat
Kutchlignite,
Kutch
215
0.735
0.108
0.1.08
100
Gujarat
Surat Lignite,
250
0.766
0.303
0.303
100
Gujarat
Wanakbori
1470
6.85
2.445
1.546
63.2
Haryana
Panipat
1360
3.85
1.54
1.668
108.3
Haryana
Faridabd
165
0.798
0.231
0.029
12.6
Jharkhand
Patratu
840
0.812
0.32
0.122
38.1
Jharkhand
Chandrapura,
DVC
750
1.396
0.592
0.675
114.0
Jharkhand
Bokaro ‘B', DVC
630
2.18
0.715
0.688
96.2
Karnataka
Raichur, KPCL
1470
6.991
2.269
0.951
41.9
Madhya
Pradesh
Satpura MPEB,
(MP)
1142.5
6.936
2.463
0.105
4.3
Madhya
Pradesh
Sanjay Gandhi
,MPEB
840
4.38
1.752
0.589
33.6
Madhya
Pradesh
Amarkantak ,
Chachai, MPEB,
290
0.977
0.298
0.247
82.9
Madhya
Pradesh
Vindhyachal
NTPC
2260
11
3.111
1.463
47.0
Maharashtra
Trombey, Tata
Poweri
1330
1.802
0.034
0.0384
112.9
Maharashtra
Koradi, MSEB
1100
4.914
1.744
0.175
10.0
Maharashtra
Parli , MSEB
690
3.799
1.578
0.376
23.8
Maharashtra
Bhusawal MSEB
482.5
2.394
0.797
0.462
57.9
Maharashtra
Dahanu ,
Relience Energy
500
2.37
0.585
0.147
25.1
Maharashtra
Khaperkheda,
MSEB
840
4.47
1.668
0.634
38.0
Maharashtra
Paras
62.5
0.325
0.102
0.102
100
Maharashtra
Chandrapur
2340
9.557
3.966
0.453
11.4
Maharashtra
Nasik
840
3.463
1.247
0.13
10.4
Orissa
Talcher ,
Angul,NTPC
460
2.82
1.073
0.66
61.5
Orissa
Ib. , OPGCL
420
2.605
1.057
0.07
6.6
Orissa
Talcher ,
Kaniha,NTPC
2500
13.87
4.982
1.232
24.7
Punjab
Gurunanak Dev,
PSEB
440
1.747
0.539
0.223
41.3
Punjab
Lehra Mohabat,
PSEB
420
1.83
0.62
0.445
71.8
Punjab
GurugobindSingh,
PSEB
1260
6.29
2.158
1.626
75.3
Rajasthan
Kota
1045
5.325
1.506
1.198
79.5
Rajasthan
Suratgrah ,
RVUNL
1250
6.096
1.759
0.836
47.5
Tamilnadu
Tuticorin TNEB
1050
5.69
2.116
0.946
44.7
Tamilnadu
Mettur TNEB
840
4.18
1.514
1.304
86.1
Tamilnadu
North Chennai ,
TNEB
630
2.54
0.946
0.304
32.1
Tamilnadu
Ennore TNEB
450
0.58
0.233
0.061
26.2
Tamilnadu
NLC, Neyveli
2490
15.886
1.835
0.499
27.2
Tamil nadu
ST CMS Electric
(P) Ltd.
250
1.442
0.067
0.052
77.6
Uttar Pardesh
Unchahar, NTPC
840
0.705
1.838
1.565
85.1
Uttar Pardesh
Dadari, NTPC
840
4.21
1.507
0.802
53.2
Uttar Pardesh
Rihand, NTPC
1000
4.75
1.407
0.73
51.9
Uttar Pardesh
Tanda, NTPC
440
2.56
0.842
0.402
47.7
Uttar Pardesh
Singrauli, NTPC
2000
10.2
3.123
1.468
47.0
Uttar Pardesh
Parichha
,UPVUNL
220
0.726
0.218
0.41
188.1
Uttar Pardesh
Obra , UPVUNL
1550
4.94
1.884
0.014
0.7
Uttar Pradesh
Anpara, UVUNL
1630
8.47
2.974
0.072
2.4
Uttar Pradesh
Panki, UVUNL
210
0.96
0. 25
0.337
133.2
West Bengal
Meizia, DVC
630
3.32
1.32
0.0013
0.1
West Bengal
Durgapur , DVC
350
0.872
0.349
0.495
141.8
West Bengal
Durgapur Projects
Ltd.
401
1.686
0.573
0.737
128.6
West Bengal
Santaldih,
WBPDCL
480
0.843
0.253
0.875
345.8498
West Bengal
Budge Budge,
500
2.52
0.908
0.908
100
CESC
West Bengal
Titagarh , CESC
240
1.17
0.33
0.33
100
West Bengal
Sounthern ,
CESC,
135
0.68
0.24 0.24
100
West Bengal
Kolaghat.
WBPDCL
1260
5.086
1.618
1.988
122.9
West Bengal
Farrakka, NTPC
1600
9.26
3.426
2.06
60.1
West Bengal
Bakreswar,
WBPDCL
630
2.487
0.689
0.242
35.1
West Bengal
Bandel, WBPDCL
530
1.285
0.413
0.18
43.6
Total
63738.5
285.742
95.414
45.9827
48.2
Captive Power plants
capative
power
plants
Name Capacity
Capacity
( MW)
Coal Cons.
( mta)
Ash Gen.
( mta)
Ash Uti.
( mta)
%
utilisation
UP
Renusagar,
HINDALCO
741.7
5.43
2.205
0.938
42.5
Orissa
NALCO
55.5
0.994
0.414
0.016
3.94
Gujarat
Tata Chemicals
70
0.077
0.034
44.2
Punjab
NFL, Bhatinda
*30
0.122
0.254
0
Karnataka
Rahshree Cemnet
38.2
0.096
0.305
317.7
Kerala
Hindustan News
Print
*22
0.166
0.049
0.049
100
AP
Sirpur Paper Mill
*31.9
0.29
0.139
0
Tamilnadu
TCP Limited
63.75
0.373
0.068
0.073
107.4
AP
Nava Bharat
Ferro alloy
50
0.276
0.137
0.014
10.2
Karnataka
Grasim Industries
10
0.089
0.027
0.025
92.6
Karnataka
Mysore
PaperMills
41
0.217
0.05
0.034
68
Gujarat
JK Paper ltd.
12
0.072
0.028
0.028
100
Orissa
NTPC-SAIL
Power Co.
120
0.906
0.362
0.318
87.8
MP
Orient paper Mills
22
0.204
0.0632
0.068
107.6
Chattisgarh
Bhilai ESCPL
74
0.47
0.125
0.0048
3.84
UP
IFFCO
12.5
0
Uttranchal
CPP-Century
Pulp & paper
27.8
0
Bihar
BCCL
30
0.164
0.068
0.068
100
AP
VSP
247.5
1.429
0.571
Nil
0
Karnataka
Vasavdatta
0.047
0.047
100
Orissa
Nava Bharat
Ferro alloy
30
0.196
0.095
0.009
9.5
West Bengal
NTPC-SAIL
Power Co.
120
0.639
0.25
0.0562
22.48
Jharkhand
Tata Steel
147.5
0.599
0.281
Nil
0
Maharashtra
Ballarpur
30
0.188
0.461
0.0462
10.0
1943.45
12.824
5.8672
2.1332
42.5
Oct 1, 2010
Aug 29, 2010
BOWL MILLS MAINTANACE -BLUE PRINT
A Four-Step Plan:
Blueprinting a pulverizer isn’t rocket science, but it does require close attention to the details. Here is our four-step plan to restore and improve performance of your pulverizer, regardless of its age.
STEP-I :
**Ensure that the grinding elements are in good condition.
Make sure that the grinding surface profiles are optimum. That means using the original design grinding profiles for your mill. The majority of coal pulverizers sized around 120,000 pph use three grinding elements, referred to as journals, rolls, or tires. For best results, all three grinding elements should be replaced in matched sets. The concentricity, physical dimensions, and contours must be exactly the same. This is especially important when maximum preload pressure is required to produce maximum coal fineness and/or with lower-than-original design HGI. We have seen mills assembled with unmatched sets of three grinding journals using maximum spring pressure. The result of such setups: The main shafts break because of the unbalanced load. Matched sets of grinding elements and exactly the same size rolls with exactly the same contour are important for maximum reliability.
The grinding surfaces also must be in good condition and parallel (Figure 3). Don’t expect optimum performance if the grinding elements are well-worn or the tires are "flat" (Figure 4). Unusual wear patterns are often the result of uneven spring frame tolerances, alignment issues, pressure variations, geometry, and/or eccentricity issues.
**Walk the line. The profile of the roll should be parallel with the grinding ring profile.
***Perfectly round. In an MPS mill, the tire and table profiles must match, and the tires should not have flat spots.
.
STEP-II:
**Set the correct grinding pressure.
Check your mill to confirm that the grinding roll or spring frame preload pressure is set correctly. Our experience with both RP and MPS pulverizers has been that mills designed for a throughput of about 120,000 pounds of coal per hour, an HGI of about 45 to 50, and coal fineness exceeding 75% passing 200 mesh will require about the same force on the grinding elements. It is reasonable to expect that grinding coal will take about the same amount of grinding element pressure regardless of the type of medium-speed, vertical spindle pulverizers you use.
In our experience the spring frame of an MPS mill tuned for maximum true capacity will be set at about 20 tons minimum force on the grinding tires. A bowl mill spring or hydraulic preload for this size of mill will also be about 20 tons of pressure. Lower-HGI fuel and greater than passing of 200 mesh requires the maximum pressure of the grinding elements. Keep in mind that in operation there is no metal-to-metal contact, and all coal grinding results from the pressure applied coal particle – to – coal particle on a bed of coal squeezed between the grinding elements.
Internal clearances are also very important. For example, a bowl mill spring canister can be set to the needed preload, but if it is not adjusted for the "button" to roll with assembly minimum clearance, then the preloading does not come into play until the roll rides up on a deeper bed of coal . Ensuring sufficient grinding pressure is absolutely essential, and it begins with setting this critical tolerance.
** Keep your distance. The "button" clearance between the spring canister and the journal assembly is a critical tolerance.
For a spring frame mill, the hydraulic preload must be balanced across the mill and the grinding elements perfectly centered in the assembly
* *Balanced load. The MPS spring frame hydraulic preload must be carefully balanced and the spring frame centered for optimum mill performance.
STEP-III:
** Set the correct pulverizer throat clearance. An oversized pulverizer throat will require more than optimum primary airflow to minimize coal rejects. The pulverizer "free annular jet" of vertically flowing airflow, in our experience, must be adjusted for a minimum of 7,000 fpm under normal operation. Throats that are oversized will result in either excessive coal rejects (not tramp metal or pyrites, but raw coal).
Compounding the problem, high primary airflow is the main cause, in our experience, for poor fuel fineness, poor fuel distribution, and reduced furnace performance. Right-sizing the flow area of the pulverizer throats and matching them for compatibility with the coal pipes and burner nozzle sizes is essential for the best furnace performance. Furthermore, remember that there will be minor variation in mill capacity, fuel quality, and mill inlet airflow rates that must be considered when sizing the pulverizer throat flow area.
The vertically flowing air must be of sufficient velocity to suspend the granular coal bed in the grinding zone. Some designs use mechanical means to keep the coal above the under-bowl pyrite section, while others use airflow. Reducing coal rejects by mechanical means entails increasing the height of the "bull ring" extension ring or the extension of flat surfaces above the rotating throat to trap or dam coal particles mechanically so that they remain above the throat.
We prefer the optimum throat area fluidic solution to suspend the coal bed and reduce the potential for fires beneath the bowl or grinding table. Keep in mind that if the fuel is above 17% moisture and the air/fuel ratio is about 1.8, then the under-bowl primary air temperature will be above 450F. Any coal that falls through the throat opening will combust unless it is removed in mere minutes. Combustion of coal particles beneath the grinding zone is not a serious problem, as long as the mill is in operation. But if a mill trips or a boiler has a main fuel trip, then fires in the pyrites zone (beneath the grinding zone) are the most common cause of pulverizer "puffs," in our experience. A fire beneath the grinding zone provides the ignition temperature to initiate a mill "puff" when restarting a mill after a trip or restarting it after a main fuel trip when coal remains in the bed.
For safety as well as for performance reasons, properly sizing the mill throats is extremely important . The optimum throat area is determined by calculating the free annular jet area when the desired air/fuel ratio (usually 1.8 lb air/lb fuel) is known. Also, the throat area must be properly designed to be compatible with the flow areas of the burner coal pipes and coal nozzles
**Optimum design. Ensure optimum arrangement of the mill throat and the coal flow path to improve mill performance.
**Close tolerances. Pulverized coal mills with throats that are too wide will have corresponding low throat velocity in the mill grinding zone that contributes to excessive coal rejects and fires. This is an example of an oversized mill throat.
STEP-IV:
**Properly maintain the classifier.
Once the grinding zone is blueprinted and put in first-class condition, the next component to examine is the classifier. The best furnace combustion performance is governed by uniform coal combustion by the burners and satisfactory coal fineness. Adequate fineness for both western and eastern fuels (Powder River Basin or bituminous) is a minimum of 75% to 80% passing 200 mesh and zero to 0.1% remaining on a 50 mesh screen (Figure 9). To achieve this fineness, the pressurized mill classifier must perform two functions:
· ** It separates particles small enough to be supplied to the burners (mean particle size about 40 to 55 microns) from larger coal particles that need return to the grinding zone for regrinding.
· ** It balances the distribution of coal to each coal pipe.
**Why use a classifier? A classifier recirculates coarse coal in the grinding zone and balances the flow of coal to each burner line to the furnace.
The flow of coal particles through a classifier is several times the amount of coal flowing to the burners because of the large amount of coal recirculated within a pulverizer. For example, if a pulverizer is operating at 100,000 lb/hr coal feed to the burners, as much as 300,000 lb/hr or more may be flowing through the classifier for regrinding. For this reason the surface smoothness and inverted cone clearances are extremely important for good pulverizer performance.
Our experience over the years has helped us develop a number of proven minor enhancements for achieving best classifier performance. The critical dimensions indicated in Figure 10 include:
· Surface smoothness of the classifier cone.
· Synchronized classifier blade angles and lengths.
· Inverted cone to classifier clearances.
· Classifier outlet cylinder length and flared opening.
·
**Better than good. Areas of the classifier where performance can be improved.
Other improvements that should be considered when overhauling a classifier include these:
· Smooth surfaces in the upper turret section for good fuel spinning and uniform distribution (no surface discontinuities, such as "pad eyes").
· Ensure the free movement and closure of the discharge doors (trickle valves).
· Confirm the sound and good condition of the classifier cone assembly (no holes should be worn through).
· Ensure the good mechanical condition of the classifier blades.
** Mill design guide. An internal view of a typical vertical-spindle pulverizer and specific areas where special attention to dimensional tolerances and assembly dimensions can improve mill performance.
COAL PULVERISING IN BOILERS
Pulverizing coal for a boiler is very important factor in overall cycle efficiency. There are many types of pulverizers available, but proper selection will ensure consistent boiler and cycle efficiency. This helps in reduction of carbon-dioxide emission per million units of electricity generated.
Boilers for steam generation in power plants and process industries use coal as fuel. The percentage of boilers operating with coal as fuel outnumbers the boilers using all other fuels combined. Coal is pulverized before firing for achieving a stable and efficient combustion. Many types of pulverizers are used in boilers by different designers.
History of pulverization:
The history of pulverization dates back as early as 1824 and was envisioned by Carnot in a coal fired engine. In 1890 Diesel made use of pulverized coal in his diesel engine. Pulverized coal firing was first developed in the cement industry and then migrated to the power and process industries. Actually Thomas Alva Edison and the Niepce brothers of France
Pulverized coal is the most efficient way of using coal in a steam generator. The coal is ground so that about 70 % will pass through 200 mesh (0.075 mm) and 99 % will pass through 50 mesh (0.300 mm). A pulverized coal boiler can be easily adapted for other fuels like gas if required later without much difficulty. However, during the design stage it is possible to make boilers firing multiple fuels. With pulverization technology, large size boilers could be designed, manufactured, erected, and run much more efficiently.
Types of pulverizers:
Mainly there are three types of pulverizer used in industry: The slow speed mills like ball tube mills, the medium speed mills like bowl, ball and race, roller mills fall in this category, and the third type is the high speed impact mill. The slow speed and medium speed mills are selected for coals ranging from sub-bituminous to anthracite. The high speed mills are used mainly for lignite.
The purpose of a pulverizer in a coal fired boiler:
- To supply pulverized coal to the boiler as per requirement of steam generation
- Transport the pulverized coal from pulverizer to the burners in the boiler
- To remove moisture in coal to an acceptable level for firing in boiler
- To remove high density inorganics from coal during pulverization
- To classify coal particles to the required level of fineness, normally 70 % through 200 mesh and less than 2% on 50 mesh .
-
Coal parameters affecting pulverizer output :
While selecting a pulverizer, the coal characteristics play an important role. The Hardgrove index, total moisture, input coal size, output fineness, and mill wear have direct impact on the mill output.
- The Hardgrove index of coal tells us about the ease with which it can be pulverized. A higher Hardgrove index indicates the coal is easier to grind. 50 HGI normally is taken for calculating the base capacity of the mill. When coal with HGI higher than 50 is fed to the pulverizer, the output will be higher than base capacity, and below 50 HGI, the output will be lower.
- The total moisture in coal has a high effect on mill output. The higher the moisture, the lower the output.
- Higher pulverized coal fineness increases the recirculation in the mill and the output reduces.
- The inlet size of the coal also affects the mill output directly.
- Mill air flow variations result in changes in mill outlet temperature and fineness as well as capacity.
Ball tube mill:
Ball tube mills are either pressurized or suction type. In the pressurized type, the hot primary air is used for drying the coal and to transport the milled coal to the furnace. In this type, leakage in the mill area is high.
In the suction type, the exhauster is used for lifting the milled coal from the pulverizer to the furnace through a cyclone. The tube mills have a large circular drum, with adequate ball charge, which is rotated at about 70% of the speed at which the ball charge would be held against the inner surface by centrifugal force. In this mill the grinding balls can be replenished on the line.
Normally the ball mill designers use three types of balls with three different diameters. These balls reduce in size as the mills operate and so the highest size ball is normally used for recharging. In earlier days, most of the ball mills had a single inlet and outlet, but now designers use both ends to feed coal and also for taking out pulverized coal. The control systems are well made to understand the requirement of ball charge and the output from the mill. Ball mills are always preferred to be operated at full capacity because the power consumption of this type of mill is very high at lower loads when compared with other types. Ball mills can be designed for a very high capacity like 75 tons per hour output for a specific coal.
Vertical spindle mill:
There are many different varieties of vertical mills. Designers use large steel balls ranging from 2 to 6 or more between two grinding rings for pulverizing. There are also other types like conical rollers with shallow bowl; deep bowl, etc. where load is applied on the rollers and the bowl rotates while pulverizing. These types of mill are designed normally up to 60 tons per hour for a specific coal; however there are vertical mills with 90 tons per hour output. A vertical spindle mill is also designed for pressurized and suction type requirements. Boiler designers use this type of mill for poor quality coal as this type of mill rejects foreign materials like stones and other high density materials. The power consumed by the mill per ton of coal ground is only two-thirds of the ball mills. However if the primary air fan power is also taken into account, in the case of a pressurized mill the power consumption is lower only by about 15%.
High speed impact mill:
This type of mill uses a central horizontal shaft which has a number of arms, and a beater of different design is attached to these arms to beat the coal to be pulverized. High speed impact mills are mainly used in pulverizing lignite. Today all boiler designers opt to use ball or vertical spindle mill for coal other than lignite.
While selecting the type of mill boiler designers must clearly understand the coal characteristics, the overall system being used, and the maintenance requirement. It is always seen that if the advantage of the mill alone is considered, then the overall boiler economics can prove to be different.
COAL HANGUP IN BOWL MILLS
Coal Hang-up in Bowl Mill:
Depending on the quality of the coal, sometimes the smooth flow to the coal mill can be disrupted. The mill will then trip on flow protection, upsetting boiler parameters and demanding immediate operator corrective action.
Bowl mills are used for pulversing coal in pulverized coal fired boilers. The coal to the mill is fed by a coal feeder from the coal bunker. There are many type of feeders used for coal feeding like the belt feeder which can be in volumetric or gravimetric mode, the chain link feeder, the drag feeder, etc. Row coal from the yard is sized in crushers and stored in coal bunkers. It is sometimes experienced, depending upon coal quality, that the smooth flow to the coal mill can get disrupted. The mill will trip on no coal flow protection, and such a mill trip can upset boiler parameters and require corrective action.
For taking corrective action during a coal hang-up in bowl mills, the operator will have to know the reason for such a hang up, how the plant will respond, what he has to respond to, and what the local operator will have to do. This will reduce the chance of mill trip and bring the boiler back to normal condition as early as possible.
Specific causes:
The reasons for coal hang-up to mills can be many, like large raw coal size, jamming of the feeder, jamming of the coal chute from the bunker due to high moisture in the coal, foreign material at raw coal inlet to feeder, etc.
Plant responses:
The boiler fuel input coming down due to coal flow hang-up the mill slowly gets unloaded. This can be inferred from the response of the boiler.
• Mill differential pressure comes down
• Mill outlet temperature will rise
• Boiler steam pressure will start falling
• No coal flow alarm will appear
• Coal feeder and mill will trip after some time
• Mill outlet temperature high alarm will appear
Operator responses:
On seeing the changes in the operating parameters of the mill the operator will have to take corrective action.
• Reduce the load on the boiler and inform the steam consumer accordingly
• Maintain boiler pressure and temperature of steam
• Start reserve mill and stabilize, if reserve mill is on maintenance, then ask local operator for the reason for hang-up and his action plan
• Keep steam consumers informed of your action
• Once coal flow is restored through the reserve mill or the same mill, steam consumer can be asked to increase load
Local operator responses:
In this case the local operator will have to play a major role in helping the control room boiler operator by performing the following checks and deciding further course of action.
• Check whether the hot air and cold air gates are closed, if not then close both
• Check hot air to raw coal and feeder is closed, if not close this
• Close the raw coal feeder inlet gate if not already closed
• After making sure all the above are closed, open the inspection door of the mill
o Check if the coal pipe from feeder to mill is clear and make sure they are made clear
o Check raw coal feeder and if chocked then get it cleaned
o Check the raw coal feeder shear pin and replace if needed
o Now operate on no load and check for smooth running
o Check the coal chute from bunker to feeder is clear, that is from the closed feeder inlet gate onwards
• Check the bunker for coal, if empty organize for filling immediately
• If mill has any remnant materials then clean the mill and restart the mill and check for smooth operation
• Now clear the mill for resuming operation
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