Gas turbine operation methods during
Wobbie index of fuel gas change
without fuel gas nozzles modification!
CHARCRIST KUHAKARN!
ELCTRICITY GENERATING AUTHORITY OF THAILAND!
1 !
2 !
Contents!1. Location and structure of the power plant
and fuel gas characteristic • Power plant location • Power plant structure
2. Fuel gas characteristic • Before fuel gas change • After fuel gas change
3. MHI Gas turbine operation (When fuel gas changes.) • Principle of Dry Low NOX combustion • Tuning method for Dry Low NOX combustion • Operation method when fuel gas changed
4. Result 5. Other gas turbine operation (When fuel gas changes.) 6. Conclusion
3 !
The effect of fuel gas change
without fuel gas nozzle
modification. !
The effect of fuel gas change!
Fuel gas was not appropriated with combustion part. 1. Combustion will not stable.
Gas turbine will trip. 2. Hot gas part may be damaged. !
1. Location and structure of the power plant !
4 !
South Bangkok Power plant, Samutprakan
Power plant Location
5 !Power plant structure: Combined cycle power plant
Gas turbine 2 units ! HRSG 2 units ! Steam turbine 1 unit!
2 Gas turbines per 1 Steam turbine (Multi shaft combined cycle power plant!
Structure of combined cycle power plant !
1. Location and structure of the power plant !
Gas turbine at south Bangkok power plant block III • Manufacturer: MHI (Mitsubishi Heavy Industries) • Combustion: Dry Low NOX combustion
6 !
1. Location and structure of the power plant !
7 !
!
!
! Fuel gas heating value
- Before: 950 – 1,051 Btu/scf
- After: 1,030 – 1,051 Btu/scf
- Future: 1,030 – 1,220 Btu/scf
2. Fuel gas characteristic !
Before
Future
After (New fuel gas)
8 !
2. Fuel gas characteristic !
Fuel gas heating value of South Bangkok power plant (BTU/SCF)!
(Before fuel gas change)!
Gas from West side!
9 !
Gas from East side!
Mixing point!
South Bangkok power plant
block III !
2. Location and structure of the power plant !
3. MHI Gas turbine operation !
Dry Low NOX combustion principle
Detail Diffusion Combustion
Premixed combustion
Combustion temperature High Low Stable region Large Small Oxides of Nitrogen (NOX) High Low
Combustion Tuning : Diffusion & Premixed combustion
• Stable combustion (Combustion Fluctuation Limits)
• Low Oxides of Nitrogen (NOX) **Stable region at high load is smaller stable region at low load.** !
10 !
3. MHI Gas turbine operation !
Dry Low NOX combustion principle
11 !
Combustion Principle!
Heat !
Fuel ! Air!Combustion !
SBK
-C31
&
SBK
-C32
12 !
Combustion tuning • Fuel
• Main Nozzle • Pilot Nozzle (Pilot Ratio) (PL Bias) • Top Hat Nozzle (Top Hat Ratio) (TH_Bias)
• Air • Air bypass valve (BV_Bias)
3. MHI Gas turbine operation !
3. MHI Gas turbine operation !
Operation preparation for combustion tuning
13 !
4. Result!
Gas turbine unit 31 swing Load Test!
14 !
NOX Limits
4. Result!
15 !
Combustion Fluctuation limits
Combustion Fluctuation limits
4. Result!
16 !
Gas turbine unit 32 swing Load Test!
NOX Limits
4. Result!
17 !
Combustion Fluctuation limits
Combustion Fluctuation limits
5. Other gas turbine operation !
North Bangkok Power plant, Nonthaburi!
18 !
5. Other gas turbine operation !
19 !
Combustion of GE gas turbine at North Bangkok Power plant block I, Nonthaburi!
DLN 2.0+ Combustion chamber (Before fuel gas change) !
DLN 2.6+ Combustion chamber (Before fuel gas change) !
5. Other gas turbine operation !
20 !
Combustion of ALSTOM gas turbine at North Bangkok Power plant block II, Nonthaburi!
6. Conclusion !
Gas from West side!
Gas from East side!
Mixing point!
South Bangkok power plant
block III !
21 !
Mixing point!
South Bangkok power plant
block III !
980.00
1,000.00
1,020.00
1,040.00
1,060.00
1,080.00
0:00
0:
55
1:50
2:
45
3:40
4:
35
5:30
6:
20
7:15
8:
10
9:05
10
:00
10:5
5 11
:50
12:4
5 13
:40
14:3
5 15
:30
16:2
0 17
:15
18:1
0 19
:05
20:0
0 20
:55
21:5
0 22
:45
23:4
0
Fuel gas WI of South Bangkok power plant during tuning
SBMR NBMR 22 !
Designed: 1,030 – 1,051 Btu/scf
Time delay of Fuel gas change from Mixing point ≈ 4 hours
4 hours
Actual: 990 – 1,051 Btu/scf
6. Conclusion !
23 !
1. Check Fuel gas from mixing point at least every 2 hours !
to check the change of fuel gas. !
(Traveling time of Fuel gas at mixing point to South Bangkok power plant is 4 hours) !
2. If WI > 1,051 Btu/scf !
Gas turbine’s load should be decreased to Min generation (140 MW) !
To protect gas turbine from Run back or Trip !
!
!
6. Conclusion !