Gas turbine operation methods during Wobbie index of fuel gas

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 !