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Comparison: Reciprocating vs. Turbine Engines


Based on "parts of heat", the comparison is roughly diagramed in "simple cycle" as follows:

To get the same generation work:

  • 40% made into horsepower
  • 40% waste heat in exhaust
  • 20% waste heat in water
 
  • 30% made into horsepower
  • 70% waste heat in exhaust
  • 0% waste heat in water

Waste heat can be captured to generate steam, but only at 70% recovery.

  • 68% horsepower or steam
  • 12% waste heat in exhaust
  • 20% waste heat in water
 
  • 79% horsepower or steam
  • 21% waste heat in exhaust
  • 0% waste heat in water

To get more steam from the reciprocating technology, firing excess air in the exhaust is done.  The advantage is that this heat can be recovered at nearly 100% due to temperatures:

  • 76% horsepower or steam
  • 9% waste heat in exhaust
  • 15% waste heat in water
  1. About 168,000 lb/hr at 180 PSIG at 38mW
  2. Can add more (or less) duct firing & heat recovery for more (or less) steam
  3. can reduce steam flow separate from power generation
  4. Eliminates need for separate steam from package boilers with their emission issues
  5. If hot water at 180 F could be used, recips enormously more effective!
  6. Less air flow to treat for emissions
 
  • About 180,000 lb/hr steam
  • Less flexible steam flow
  • More exhaust flow for emissions equipment to control
  1. 180,000 lb/hr at 180 PSI & 38 mW
  2. same as recip
  3. Less flexible steam flow
  4. same as recip
  5. Can generate hot water
  6. More air flow to treat for emissions

Summary

  1. Both reciprocating and turbine technology have good features.  Both are readily available to be relocated immediately.
  2. The turbine will have a higher flow in the exhaust, the recips a higher heat flow in the cooling water.
  3. The recips fire at higher temperatures for more mechanical conversion of fuel to shaft horsepower.
  4. The recips allow a smaller investment to get on line with good efficiency.
  5. The recips allow flexible addition of duct firing and steam recovery to meet future steam demands.  Conversion of duct heat to steam is very efficient.  
  6. Turbine technology in simple cycle is inefficient requiring almost 33% more fuel for the same power output compared to recips.  
  7. With steam recovery, however, turbines are very efficient.