Supercritical Boiler-1
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ONCE THROUGH STEAM GENERATORS
Benson boiler growth • •
1926 –Siemens maufactures 30–125t/h boilers 1949 –First OT boiler with high steam conditions(175 bar/610 DegC – Leverkusen) • 1963 – First spiral tube waterwall in membrane design(Rhodiaceta) • 1987- Largest hard coal fired boiler (Heyden 900 MW More than 980 boilers with > 700000 t/h
CONTROLLED CIRCULATION (Vs) ONCE THRU’
CC
OT
Once Through Principle Comparison Natural Circulation / Once-Through-System
Source: Siemens
Cumulative Steam Capacity of Ordered BENSON Boilers BBP´s share about 44 %
Total Steam Output about 200.000 kg/s
Source: Siemens
Once Through Boiler-Concept
Once through system
ONCE - THROUGH OPERATING RANGE
Increase of Cycle Efficiency due to Steam Parameters Increase of efficiency [% ] 10
6,77
9
5,79
5,74
8
4,81
7
3,74
4,26
6 5
3,44
3,37
4
2,64
3
1,47
2,42
2
2,76
600 / 620
1,78
0,75
1
580 / 600 566 / 566
0 300 Pressure [bar]
0 241
175
538 / 538
538 / 566 HP / RH outlet temperature [deg. C]
Comparison of Plant part load efficiency 46
42,4 %
Plant net efficiency
43,6 %
43,2 %
40,1 %
40
41,1 %
40,5 % 39,3 %
Supercritical unit acc. Alternative 2 255 bar 538°C / 538°C
36,7 %
Subcritical unit acc. Alternative 1 166 bar 538°C / 538°C
30
30
40
50
60
70
80
90
Load %
100
Examples of Boiler Concepts Tower Boiler
Two-Pass Boiler without platen superheater
Two-Pass Boiler with platen superheater
66,0 m
PS Staudinger 5 - 550 MW el
PS Heyden 4 - 920 MW el
PS Kogan Creek - 700 MW el
Comparison of Lignite, Coal and Oil Fired Units
PS Offleben (C), 325 MWel
PS Farge, 320 MWel
mHD = 1000 t/h; B = 16,4 m
mHD = 1020 t/h; B = 16,5 m
Heat input / furnace area [kW/m²] Σ SH heating surfaces [m²] Σ RH heating surfaces [m²] Σ Bundel surfaces [m²]
215 17.781 15.290 33.071
330 6.791 12.072 18.863
PS Doha West, 300 MWel mHD = 1100 t/h; B = 14 m
680 10.953 5.202 16.155
Benson Boiler Main Configuration - Single-pass / Two-pass
Source: Siemens
DRUM vs ONCE THROUGH SH
ECO
STEAM TO TURBINE
STEAM TO TURBINE
SH
DRUM
DOWN COMER CIRC. PUMP
Pressure Steam Separation Types Burner Panel Load Change Cold Start Hot Start
HEAT
HEAT Water Wall ORIFICE
Sub critical Drum Natural / Assisted Straight tube Base 4-5 Hours 1-2 Hours
ECO
Water Wall
Sub & super Critical Separator (Low loads) (Sulzer) / (Benson) Spiral Tube / Straight (MHI) Faster 2 Hours 0.5 Hours
Drum type boiler • Steam generation takes place furnace water walls • Fixed evaporation end point - the drum • Steam -water separation takes place in the drum • Separated water mixed with incoming feed water
Once Through Boiler • Once -through flow through all sections of boiler (economiser, water walls & superheater) • Feed pump provides the driving head • Suitable for sub critical & super critical pressures
Once -thru Boiler Advantages: • • • •
Quick response to load changes Shorter start up time Better suited for sliding pressure operation Steam temperature can be maintained over wider load range under sliding pressure • Higher tolerance to varying coal quality • Suitable for sub critical & super critical pressures
ADVANTAGES OF ONCE THROUGH BOILERS Once thru boiler enables : • Peak power generation with better efficiency levels • Quicker response to TG load changes • Better heat rate of lower loads
Once -through Boiler
Characteristics :
• Provides Quicker response to TG load changes • Supports achievement of better heat rate at lower loads • Higher furnace wall pressure drop and consequent higher feed pump auxiliary power consumption • Needs ultra pure quality feed water - Cannot operate under conditions of condenser leak
Tower Vs Two pass • • •
For Indian Pit-head power station BBP preference is tower type ( to overcome flyash erosion) For power stations firing beneficiated Indian coals – Two pass boiler For coastal power stations firing imported coals – Two pass boiler
Flow Scheme of Membrane Walls for Two-Pass Boilers 3.)
1.)
5.) 2.)
4.)
Detail: Ties for Spiral Tubing
Temperature difference between the wall systems (Example Studstrup Power Plant)
Boiler Load Location 100% 35% 1.) 2K 1K 2.) 7K 1K 3.) 13 K 1K 4.) 2K 3K 5.) 7K 17 K
Flow Scheme of Membrane Walls for Tower Boilers
Transition from Spiral Tubing to Vertical Tubing
Start-Up Times [min] of Power Plants Plants with Drum Boiler 167 bar / 538°C / 538°C From ignition to: After shut down hours
From ignition to:
first steam to Turbine
full load
first steam to Turbine
full load
<1
20 - 30
60 - 80
20 - 30
30 - 40
8
40 - 60
80 - 100
30 - 40
50 - 60
48
150 - 210
300 - 350
60 - 80
150 - 200
>48
150 - 210
450 - 600
60 - 80
400 - 600
Modern Coal-Fired Power Plant EV 2 / ; NTPC Presentation.ppt
Plants with BENSON Boiler 250 bar / 540°C / 560°C
KWU 99 152d Page 23
BOILERS - DISCUSSED AT BBP MAJUBA 660 MW TOWER 192 bar 555 C SCHKOPAU 450 MW TOWER 262 bar 545 C VOERDE 700 MW TWO PASS 206 bar 530 C
19286x19286 17846x17846 23668x15773
BOXBERG 900 MW TOWER 266 bar 545 C ELKRAFT 300 MW TWO PASS 250 bar 545 C
24086X24086 12720X14280
MAJUBA,SCHKOPAU,VOERDE : WITH VERTICAL TUBE HOPPER BOXBERG: WITH SPIRAL TUBE HOPPER ELKRAFT: WITH SPIRAL HOPPER & SPIRAL IN FRONT/REAR , HORIZONTAL IN SIDES
Once -thru Boiler - Furnace Wall
Furnace Arrangement
SPIRAL TYPE
VERTICAL TYPE
FURNACE WALL ARRANGEMENT
BOILER PRESSURE PARTS WEIGHT BOILER TYPE
PIPES
TUBES
210 MW
315 MT
1100 MT
250 MW
410 MT
1440 MT
500 MW
695 MT
2870 MT
1070 MT
5080 MT
660 MW**
** Worked out based on the Alstom BOM supplied for SIPAT boiler.
Technology Acquisition Thru Collaboration – Status •BHEL entered into a TCA with M/S Babcock Borsig Power(BBP), Grmany in 1999. •First phase of training provided by BPP in 2001. •BBP has become insolvent in July 2002 & further training planned during the execution of the first contract and technology transfer was not possible. •Subsequently a new Engg company , Babcock Borsig Power Systems (BBPS), owned by Babcock Hitachi, Japan was formed. •BBPS was found acceptable for Technical collaboration after “due deligence” exercises. But the collaboration route with BBPS could not be utilised for Sipat tender as NTPC spec required the collaborator to provide financial guarantees.
SIPAT 3x660MW – Joint Bidding with Alstom •In the original bid submitted in Oct 2003, BHEL-Alstom joint bid was placed at L3, with Dossan/Korea as L1 and TPE/Russia as L2. •In Dec 2003, NTPC invited snap bids to be submitted by all the three bidders by 9 Jan 2003 •The new requirements (with increased steam flow & for vacating certain deviations) called for a total redesign by Alstom with estimated three months time. Accordingly BHEL sought extension till 05 March 2004 for submitting the revised bid. •However since the request for extension was not granted by NTPC, the snap bid could not be submitted by BHEL
Immediate OTB projects •NTPC – BARH 3x660MW Tender due in May 2004. QR same as Sipat project. •APGENCO, Vijayawada 1X660MW Four companies (Alstom, Siemens/Doosan,Sumitomo/Babcock Hitachi & TPE/Russia) have been pre-qualified for EPC
Benson boiler growth • •
1926 –Siemens maufactures 30–125t/h boilers 1949 –First OT boiler with high steam conditions(175 bar/610 DegC – Leverkusen) • 1963 – First spiral tube waterwall in membrane design(Rhodiaceta) • 1987- Largest hard coal fired boiler (Heyden 900 MW More than 980 boilers with > 700000 t/h
CONTROLLED CIRCULATION (Vs) ONCE THRU’
CC
OT
Once Through Principle Comparison Natural Circulation / Once-Through-System
Source: Siemens
Cumulative Steam Capacity of Ordered BENSON Boilers BBP´s share about 44 %
Total Steam Output about 200.000 kg/s
Source: Siemens
Once Through Boiler-Concept
Once through system
ONCE - THROUGH OPERATING RANGE
Increase of Cycle Efficiency due to Steam Parameters Increase of efficiency [% ] 10
6,77
9
5,79
5,74
8
4,81
7
3,74
4,26
6 5
3,44
3,37
4
2,64
3
1,47
2,42
2
2,76
600 / 620
1,78
0,75
1
580 / 600 566 / 566
0 300 Pressure [bar]
0 241
175
538 / 538
538 / 566 HP / RH outlet temperature [deg. C]
Comparison of Plant part load efficiency 46
42,4 %
Plant net efficiency
43,6 %
43,2 %
40,1 %
40
41,1 %
40,5 % 39,3 %
Supercritical unit acc. Alternative 2 255 bar 538°C / 538°C
36,7 %
Subcritical unit acc. Alternative 1 166 bar 538°C / 538°C
30
30
40
50
60
70
80
90
Load %
100
Examples of Boiler Concepts Tower Boiler
Two-Pass Boiler without platen superheater
Two-Pass Boiler with platen superheater
66,0 m
PS Staudinger 5 - 550 MW el
PS Heyden 4 - 920 MW el
PS Kogan Creek - 700 MW el
Comparison of Lignite, Coal and Oil Fired Units
PS Offleben (C), 325 MWel
PS Farge, 320 MWel
mHD = 1000 t/h; B = 16,4 m
mHD = 1020 t/h; B = 16,5 m
Heat input / furnace area [kW/m²] Σ SH heating surfaces [m²] Σ RH heating surfaces [m²] Σ Bundel surfaces [m²]
215 17.781 15.290 33.071
330 6.791 12.072 18.863
PS Doha West, 300 MWel mHD = 1100 t/h; B = 14 m
680 10.953 5.202 16.155
Benson Boiler Main Configuration - Single-pass / Two-pass
Source: Siemens
DRUM vs ONCE THROUGH SH
ECO
STEAM TO TURBINE
STEAM TO TURBINE
SH
DRUM
DOWN COMER CIRC. PUMP
Pressure Steam Separation Types Burner Panel Load Change Cold Start Hot Start
HEAT
HEAT Water Wall ORIFICE
Sub critical Drum Natural / Assisted Straight tube Base 4-5 Hours 1-2 Hours
ECO
Water Wall
Sub & super Critical Separator (Low loads) (Sulzer) / (Benson) Spiral Tube / Straight (MHI) Faster 2 Hours 0.5 Hours
Drum type boiler • Steam generation takes place furnace water walls • Fixed evaporation end point - the drum • Steam -water separation takes place in the drum • Separated water mixed with incoming feed water
Once Through Boiler • Once -through flow through all sections of boiler (economiser, water walls & superheater) • Feed pump provides the driving head • Suitable for sub critical & super critical pressures
Once -thru Boiler Advantages: • • • •
Quick response to load changes Shorter start up time Better suited for sliding pressure operation Steam temperature can be maintained over wider load range under sliding pressure • Higher tolerance to varying coal quality • Suitable for sub critical & super critical pressures
ADVANTAGES OF ONCE THROUGH BOILERS Once thru boiler enables : • Peak power generation with better efficiency levels • Quicker response to TG load changes • Better heat rate of lower loads
Once -through Boiler
Characteristics :
• Provides Quicker response to TG load changes • Supports achievement of better heat rate at lower loads • Higher furnace wall pressure drop and consequent higher feed pump auxiliary power consumption • Needs ultra pure quality feed water - Cannot operate under conditions of condenser leak
Tower Vs Two pass • • •
For Indian Pit-head power station BBP preference is tower type ( to overcome flyash erosion) For power stations firing beneficiated Indian coals – Two pass boiler For coastal power stations firing imported coals – Two pass boiler
Flow Scheme of Membrane Walls for Two-Pass Boilers 3.)
1.)
5.) 2.)
4.)
Detail: Ties for Spiral Tubing
Temperature difference between the wall systems (Example Studstrup Power Plant)
Boiler Load Location 100% 35% 1.) 2K 1K 2.) 7K 1K 3.) 13 K 1K 4.) 2K 3K 5.) 7K 17 K
Flow Scheme of Membrane Walls for Tower Boilers
Transition from Spiral Tubing to Vertical Tubing
Start-Up Times [min] of Power Plants Plants with Drum Boiler 167 bar / 538°C / 538°C From ignition to: After shut down hours
From ignition to:
first steam to Turbine
full load
first steam to Turbine
full load
<1
20 - 30
60 - 80
20 - 30
30 - 40
8
40 - 60
80 - 100
30 - 40
50 - 60
48
150 - 210
300 - 350
60 - 80
150 - 200
>48
150 - 210
450 - 600
60 - 80
400 - 600
Modern Coal-Fired Power Plant EV 2 / ; NTPC Presentation.ppt
Plants with BENSON Boiler 250 bar / 540°C / 560°C
KWU 99 152d Page 23
BOILERS - DISCUSSED AT BBP MAJUBA 660 MW TOWER 192 bar 555 C SCHKOPAU 450 MW TOWER 262 bar 545 C VOERDE 700 MW TWO PASS 206 bar 530 C
19286x19286 17846x17846 23668x15773
BOXBERG 900 MW TOWER 266 bar 545 C ELKRAFT 300 MW TWO PASS 250 bar 545 C
24086X24086 12720X14280
MAJUBA,SCHKOPAU,VOERDE : WITH VERTICAL TUBE HOPPER BOXBERG: WITH SPIRAL TUBE HOPPER ELKRAFT: WITH SPIRAL HOPPER & SPIRAL IN FRONT/REAR , HORIZONTAL IN SIDES
Once -thru Boiler - Furnace Wall
Furnace Arrangement
SPIRAL TYPE
VERTICAL TYPE
FURNACE WALL ARRANGEMENT
BOILER PRESSURE PARTS WEIGHT BOILER TYPE
PIPES
TUBES
210 MW
315 MT
1100 MT
250 MW
410 MT
1440 MT
500 MW
695 MT
2870 MT
1070 MT
5080 MT
660 MW**
** Worked out based on the Alstom BOM supplied for SIPAT boiler.
Technology Acquisition Thru Collaboration – Status •BHEL entered into a TCA with M/S Babcock Borsig Power(BBP), Grmany in 1999. •First phase of training provided by BPP in 2001. •BBP has become insolvent in July 2002 & further training planned during the execution of the first contract and technology transfer was not possible. •Subsequently a new Engg company , Babcock Borsig Power Systems (BBPS), owned by Babcock Hitachi, Japan was formed. •BBPS was found acceptable for Technical collaboration after “due deligence” exercises. But the collaboration route with BBPS could not be utilised for Sipat tender as NTPC spec required the collaborator to provide financial guarantees.
SIPAT 3x660MW – Joint Bidding with Alstom •In the original bid submitted in Oct 2003, BHEL-Alstom joint bid was placed at L3, with Dossan/Korea as L1 and TPE/Russia as L2. •In Dec 2003, NTPC invited snap bids to be submitted by all the three bidders by 9 Jan 2003 •The new requirements (with increased steam flow & for vacating certain deviations) called for a total redesign by Alstom with estimated three months time. Accordingly BHEL sought extension till 05 March 2004 for submitting the revised bid. •However since the request for extension was not granted by NTPC, the snap bid could not be submitted by BHEL
Immediate OTB projects •NTPC – BARH 3x660MW Tender due in May 2004. QR same as Sipat project. •APGENCO, Vijayawada 1X660MW Four companies (Alstom, Siemens/Doosan,Sumitomo/Babcock Hitachi & TPE/Russia) have been pre-qualified for EPC
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