Waukesha Knock Index [PDF]

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GE Energy Gas Engines

Waukesha Knock Index* (WKI*)

12V / 18V 220GL Derating Schedules and Theory of Application The 220GL engine is available only for continuous operating power (COP) according to ISO 8528. COP is the available output for continuous electricity supply during an unlimited number of hours per year, in between normal maintenance intervals and under specified ambient conditions, the maintenance being made according to engine manufacturer specifications. No overload or overspeed is available. Certain installations of the 220GL product will require the application of derating due to fuel, ambient, or other site conditions that are beyond the scope of standard application. This specification is meant to document the process and technical data for applying the appropriate derates based on the following factors: 

Fuel WKI



Air inlet temperature to the turbocharger compressor (not site ambient temperature)



Intake manifold temperature



Altitude



Fuel pressure at gas train inlet

The information under DERATING METHODOLOGY (page 1 and 2) is meant to provide a basis for the process to be followed when determining the applicable derates for the site in question. Each K-factor is to be calculated either from the graphs (pages 3-10) or the equations (pages 11-13). It is recommended to use the specific equations for greater accuracy in the end result. These K-factors, along with the calculations for KTOTAL, α, and other variables, are used to determine the maximum power that is available under all site conditions. Pages 14-15 of this specification contain two examples of applying this derating methodology utilizing the information contained within this specification. It is critically important that the right configuration graph and equations are being studied to match the site requirements for engine speed/generator frequency, NOx emissions output, and LT (auxiliary) water inlet temperature. Each graph can be used whether a 12V220GL or 18V220GL is under study. NOTES:

Refer to the WKI program (version 1.17 or newer) for accurate calculation of site fuel WKI to be used for engine derating prediction. If the engine output has been adjusted for WKI, site ambient conditions, or gas feed pressure to gas train, the specific fuel consumption and heat balance has to be adjusted accordingly. Refer to S-sheet S-8154-101, latest revision, for more information.

Contact Waukesha Engine Application Engineering for assistance. DERATING METHODOLOGY K1 = derate factor due to WKI (Waukesha Knock Index) K2 = derate factor due to MCAIT (Maximum Charge Air Inlet Temperature – air temperature before turbocharger compressor) K3 = derate factor due to IMAT (Intake Manifold Air Temperature) K4 = derate factor due to Altitude

Page 1 of 5

220GL Derating Schedules And Theory Of Application

EN: 153107 DATE: 3/11

Ref. S 9200-18

GE Energy Gas Engines

Waukesha Knock Index (WKI)

Prated = maximum allowable power (no derates, no overload allowed) PX1 = adjusted output for WKI PX1 = Prated x K1 PX2 = adjusted output for site ambient conditions PX2 = PX1 x α  1  1  0.9 

  KTOTAL  0.7  1  KTOTAL    Where KTOTAL = K2 x K3 x K4

PX TOTAL = service output (adjusted output for ALL site conditions) PX TOTAL = PX2 if PX2 < PX3 PX TOTAL = PX3 if PX3 < PX2 If Pgas > Pref for the corresponding engine configuration, calculation of PX3 is not needed and PX TOTAL = PX2 PX3 = adjusted power output for gas feed pressure (when Pgas < Pref) PX3 = Prated x [1 – 0.4 x (Pref – Pgas)] Pgas = GAGE gas pressure at gas train inlet

NOX SETTING

T.A. Luft (500 mg/m3N at 5% O2 dry)

1/2 T.A. Luft (250 mg/m3N at 5% O2 dry)

ENGINE SPEED

CHARGE AIR COOLING (LT) INLET TEMPERATURE (°C)

1500 RPM (50Hz) 1200 RPM (60Hz) 1500 RPM (50Hz) 1200 RPM (60Hz)

PREF (BARGAGE)

45

2.6

55

2.6

45

2.9

55

2.8

45

2.7

55

2.8

45

3.2

55

3.0

NOTES:PREF AND PGAS MUST BE IN BARGAGE

Page 2 of 5

220GL Derating Schedules And Theory Of Application

EN: 153107 DATE: 3/11

Ref. S 9200-18

GE Energy Gas Engines SPEED

Waukesha Knock Index (WKI) NOX SETTING

LT INLET TEMPERATURE

DERATING METHODOLOGY K1 – WKI

1500 RPM (50Hz)

T.A. Luft

45°C (113°F)

1500 RPM (50Hz)

T.A. Luft

55°C (131°F)

1500 RPM (50Hz)

1/2 T.A. Luft

45°C (113°F) & 55°C (131°F)

1200 RPM (60Hz)

T.A. Luft

45°C (113°F) & 55°C (131°F)

1200 RPM (60Hz)

1/2 T.A. Luft

45°C (113°F)

1200 RPM (60Hz)

1/2 T.A. Luft

55°C (131°F)

1500 RPM (50Hz) & 1200 RPM (60Hz)

T.A. Luft & 1/2 T.A. Luft

45°C (113°F) & 55°C (131°F)

WKI ≥ 84.6 73.3 ≤ WKI ≤ 84.6 66.5 ≤ WKI ≤ 73.3 WKI ≥ 93.0 64.0 ≤ WKI ≤ 93.0 WKI ≥ 80.1 41.0 ≤ WKI ≤ 80.1 WKI ≥ 90.2 80.1 ≤ WKI ≤ 90.2 73.3 ≤ WKI ≤ 80.1 WKI ≥ 80.1 66.5 ≤ WKI ≤ 80.1 58.8 ≤ WKI ≤ 66.5 WKI ≥ 90.2 80.1 ≤ WKI ≤ 90.2 73.3 ≤ WKI ≤ 80.1

K1 = 1 K1 = 0.0079*WKI + 0.3281 K1 = 0.0236*WKI – 0.8197 K1 = 1 K1 = 0.0086*WKI + 0.2 K1 = 1 K1 = 0.0115*WKI + 0.0780 K1 = 1 K1 = 0.0099*WKI + 0.1046 K1 = 0.0206*WKI – 0.7535 K1 = 1 K1 = 0.0074*WKI + 0.4095 K1 = 0.0206*WKI – 0.4720 K1 = 1 K1 = 0.0099*WKI + 0.1046 K1 = 0.0206*WKI - 0.7535

K2 – MCAIT

NOTES:

1. 2. 3.

MCAIT ≤ 40°C 40°C ≤ MCAIT ≤ 50°C

K2 = 1 K2 = 1 + 0.004*(40 – MCAIT)

MCAIT MUST BE IN °C Minimum MCAIT is 0°C Maximum MCAIT is 50°C K3 – IMAT

1500 RPM (50Hz) & 1200 RPM (60Hz) NOTES:

1500 RPM (50Hz) & 1200 RPM (60Hz) NOTES:

T.A. Luft & 1/2 T.A. Luft 1. 2. 3.

IMAT ≤ 55°C

K3 = 1

55°C ≤ IMAT ≤ 65°C

K3 = 1 + 0.01*(55 – IMAT)

IMAT MUST BE IN °C Maximum IMAT is 65°C The charged air temperature is approximately 10°C higher than the charge air coolant temperature.

T.A. Luft & 1/2 T.A. Luft 1. 2. 3.

45°C (113°F)

55°C (131°F)

IMAT ≤ 65°C

K3 = 1

65°C ≤ IMAT ≤ 75°C

K3 = 1 + 0.01*(65 – IMAT)

IMAT MUST BE IN °C Maximum IMAT is 75°C The charged air temperature is approximately 10°C higher than the charge air coolant temperature. K4 – ALTITUDE

1500 RPM (50Hz) & 1200 RPM (60Hz)

T.A. Luft

45°C (113°F) & 55°C (131°F)

ALTITUDE ≤ 1500m

K4 = 1

1500m ≤ ALTITUDE ≤ 3000m

K4 = 1 + 0.0001*(1500 – ALTITUDE)

1500 RPM (50Hz) & 1200 RPM (60Hz)

1/2 T.A. Luft

45°C (113°F) & 55°C (131°F)

ALTITUDE ≤ 500m

K4 = 1

500m ≤ ALTITUDE ≤ 3000m

K4 = 1 + 0.0001*(500 – ALTITUDE)

NOTES:

1. 2.

ALTITUDE MUST BE IN METERS If altitude is higher than 3000 meters contact Waukesha Application Engineering.

Page 3 of 5

220GL Derating Schedules And Theory Of Application

EN: 153107 DATE: 3/11

Ref. S 9200-18

GE Energy Gas Engines

Waukesha Knock Index (WKI)

EXAMPLE 1: Derates for WKI, MCAIT, and altitude are applied. No IMAT or fuel pressure derating. GIVEN INFORMATION          

18V220GL 1500 RPM (50Hz) 1/2 T.A. Luft (250 mg/m3N at 5% O2 dry) LT Inlet Temperature = 45 °C Prated = 3200 kWe WKI = 78 MCAIT = 42 °C IMAT = 32 °C Altitude = 750 meters Pgas = 5.1 BARGAGE

SOLUTION Using equations determine K1, K2, K3, and K4 41.0 ≤ WKI ≤ 80.1 K1 = 0.975

K1 = 0.0115* WKI + 0.0780

K1 = 0.0115*78 + 0.0780

40°C ≤ MCAIT ≤ 50°C K2 = 0.992

K2 = 1 + 0.004*(40 – MCAIT)

K2 = 1 + 0.004*(40 – 42 °C)

IMAT ≤ 55°C K3 = 1 500m ≤ ALTITUDE ≤ 3000m K4 = 0.975

K4 = 1 + 0.0001*(500 – ALTITUDE) K4 = 1 + 0.0001*(500 – 750 meters)

Determine PX1 PX1 = Prated x K1

= 3200 x 0.975 = 3120

Determine KTOTAL, α, and PX2 KTOTAL = K2 x K3 x K4 = 0.992 x 1 x 0.975 = 0.967  1   1  = 0.964  0.9 

  0.967  0.7  1  0.967    PX2 = PX1 x α = 3120 x 0.964 = 3007

Determination of PX3 is not needed since Pgas is greater than Pref therefore PTOTAL = PX2 PTOTAL = 3007 kWe

Page 4 of 5

220GL Derating Schedules And Theory Of Application

EN: 153107 DATE: 3/11

Ref. S 9200-18

GE Energy Gas Engines

Waukesha Knock Index (WKI)

EXAMPLE 2: Derates for MCAIT and fuel pressure are applied. No WKI, IMAT, or altitude derating. GIVEN INFORMATION  12V220GL  1200 RPM (60Hz)  T.A. Luft (500 mg/m3N at 5% O2 dry)  LT Inlet Temperature = 45 °C  Prated = 2100 kWe  WKI = 93  MCAIT = 43 °C  IMAT = 50 °C  Altitude = 500 meters  Pgas = 2.9 SOLUTION Using equations determine K1, K2, K3, and K4 WKI ≥ 90.2 K1 = 1

K1 = 1

40°C ≤ MCAIT ≤ 50°C K2 = 0.988

K2 = 1 + 0.004*(40 – MCAIT)

K2 = 1 + 0.004*(40 – 43 °C)

IMAT ≤ 55°C K3 = 1 ALTITUDE ≤ 1500m K4 = 1

K4 = 1

Determine PX1 PX1 = Prated x K1

= 2100 x 1 = 2100

Determine KTOTAL, α, and PX2 KTOTAL = K2 x K3 x K4 = 0.988 x 1 x 1 = 0.988  1   1  = 0.987  0 .9 

  0.988  0.7  1  0.988    PX2 = PX1 X α = 2100 X 0.987 = 2072 Determine Px3

PX3 = Prated x [1 – 0.4 x (Pref – Pgas)] = 2100 x [1 – 0.4 x (3.15 – 2.9)] = 1890 PX TOTAL = PX3 since PX3 < PX2 PX TOTAL = 1890 kWe

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Page 5 of 5

220GL Derating Schedules And Theory Of Application

EN: 153107 DATE: 3/11

Ref. S 9200-18