An Introduction to Fuel Injection Pumps for Gas Turbines

Colfax has pumped a variety of 'burnable' fluids within the power generation market.  These fuels can range from the easily handled Distillate Oil #2 and treated Crude Oil and Bunker Oil (#6) to the more lighter, unique fuels such as Naptha, Methanol, Water-white kerosene and Jet Fuel to name a few.  These fuels can be used as the primary fuel or applied in reserve with natural gas in a dual fuel gas turbine system.  In a dual fuel system, the fuel pumps come online if the gas supply is interrupted allowing the plant to continue to deliver power.

In addition to the changes in fuel, pressures and viscosity can also vary with each gas turbine system. Please review the two examples below that show the effects of varying viscosity and pressures.  In these examples, the delivered flow required is 150gpm.  (Here's a link to a metric/english standard conversion web-site.)

Example 1: Same discharge and inlet pressure with varying inlet viscosity.

Note that the heavier viscosity liquids delivers about 9% more gallons per minute and higher volumetric efficiency.  The slight improvement can be attributed to reduced slip from the heavier fluid.

Example 2: Varying discharge and inlet pressure with same inlet viscosity:

Note the increases in hp required (43%) to pump the fluid; this is because of the linear relationship between pressure and hp (Equation: (gpm * psig)/1714 = oil horsepower)

Conclusion: In the two examples, I've tried to highlight a benefit to positive displacement pump technology, which is the minimal change in gpm output that a three screw pump provides over a wide pressure and viscosity range.  You will see greater changes in horsepower and efficiency when you exceed 31cst.  However, this example covers some of the power generation fuel injection pump applications that we see.  Each application is unique.  Please consult with your field representative or our application engineering department if you have questions.

My colleague, Larry Nowakowski Power Generation Market Manager for Colfax Americas, has worked with nearly all OEM turbine and engine suppliers over his career.  He provides a complimentary lunch and learn presentation where he goes into further detail on power generation systems.  Also, Jim Brennan (retired product engineer for Colfax Americas) has published an excellent article on combustion gas turbine fuel pumps that you can find on the Colfax Americas - Imo Pump website.