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 !