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Advanced Compressor Engine Controls to Enhance Operation Reliability and Integrity
Project Number

The goal of this project is to develop, evaluate, and demonstrate advanced, closed-loop NOx emissions controls for two-stroke integral gas compressor engines to enhance the operation, reliability, and integrity of the natural gas transmission system through development of advanced compressor technologies.


Southwest Research Institute (SwRI) – project management and research products
Cooper Energy Services (CES) – project support for cooper bessemer test engine

San Antonio, Texas 78238


The gas transmission industry operates over 4,000 integral engine compressors, the majority being two-stroke, with a median age of 45 years and a median size of 2000 horsepower. These engines pump at least half of the 23 TCF of natural gas presently consumed in the United States. These engines are no longer produced, and with the projections for future increased demand of natural gas and the expense of replacement, it would be advantageous to modernize the existing fleet to allow for continued operation with increased efficiency and emissions compliance.

Integral gas compression engines have historically exhibited poor performance and high emissions, due in part to poor engine control. The end results are misfires and partial burns that lead to increased fuel usage and exhaust emissions. Many of the slow-speed integral engines in the gas compression industry utilize control systems that are outdated, slow, and suffer from poor resolution. The automotive and heavy-duty truck industries have advanced the state of electronics, sensors, and control algorithms for maximum efficiency, minimum emissions, and broadest operating envelope. Communications between the various power train components have also been developed for optimized operation and interaction between auxiliary systems.

Typical Integral Compressor Engine Control System Layout
Typical Integral Compressor Engine Control System Layout

To comply with future emissions legislation, and to increase industry wide competitiveness, existing engines need modern control systems and modern electronic sensors to maximize fuel economy while remaining emissions compliant. In addition, engine health monitoring and safety requirements mandate that additional sensors be installed to prevent inefficient operation, to be emission compliant, be pro-active in maintenance scheduling, expand the operating envelope, and allow for efficient operation at conditions that do not affect the structural integrity of the unit. The work reported under this project is a step toward bringing integral gas compression engine control and health-monitoring up to par with modern engine control technology, with new concepts that address the specific nature of integral compressor engine operation. The results of this program should compliment other industry funded programs for development of more sophisticated electronic engine controls.


The research conducted under this project has several potential impacts. In order to meet emissions legislation, it is essential that existing engines require modern control systems and sensors to enhance fuel economy while remaining emissions compliant. It is also critical to monitor engine health and safety to prevent inefficient operation or emissions violations, to expand the operating envelope, and to be proactive in maintenance scheduling. The proposed work takes steps toward making such monitoring possible and in doing so holds the potential to affect the environmental impact of pollutants from older two-stroke reciprocating engines through optimized operation and to enhance the overall safety, integrity, and delivery reliability of natural gas through real time condition monitoring of these critical gas infrastructure components.

Accomplishments (most recent listed first)
  • Completed an assessment of the status of current technology.
  • Finalized configuration of Cooper–Bessemer GMVH-6 two-stroke compressor engine with equipment, sensors, and instrumentation required for controls development and evaluation.
  • Finished development of control algorithms to evaluate closed loop NOx emissions control on both global and individual cylinder basis for two-stroke integral compressor.
  • Completed baseline mapping of test engine over full load/speed range with performance and emissions data collection.
  • Completed evaluation of closed loop control algorithms at speed/load conditions encompassing the typical engine operating range as well as conditions outside normal range (to demonstrate the ability to increase engine's operating envelope while maintaining NOx levels).
  • Finalized determination of optimum closed loop NOx control algorithms through data reduction and analysis of operational test data.
  • Completed development of flow schematics for optimum control algorithms such that control companies can easily implement algorithms by converting to the appropriate source code.
Current Status

and Remaining Tasks:
Work under this project has been completed resulting in a valuable description of optimum control algorithms for two-stroke integral natural gas compressor systems. Results and algorithms will be made available to potential users (controls development companies) through the release of the project final report and collaborations between SwRI and those companies. Project final report is to be posted by late spring 2005.

Project Start
Project End
DOE Contribution


Performer Contribution


Contact Information

NETL – Richard Baker ( or 304-285-4714)
SwRI – Gary D. Bourn (

Additional Information

Final Report  [PDF-1709KB] 
Status Assessment  [PDF-315KB] 
Kick-off Presentation  [PowerPoint-4194KB]