Drennen Engineering, Inc. is a consulting company formed in 1998 to provide solutions to the fossil power generation business. Through testing and modeling, DE develops systematic methods to reduce pressure part failures due to micron-sized particle impact, i.e., fly ash erosion. The result of this effort is fewer pressure part failures, lower O&M costs, and improved unit availability. To achieve that end, appropriate gas and ash flow redistribution devices are recommended.

Using similar tools and techniques, a new Commercial CoVentilation™ Service has been added. The purpose is to improve awareness of the movement of harmful particles in enclosed spaces using current ventilation practices.  Based on measurement and modeling, recommendations would be made for hardware changes to reduce the residence time and distribution of harmful particles within enclosed spaces.


Utility Steam Generator
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John Drennen
John Drennen

John F. Drennen Jr.

John Drennen is President and principal investigator. Since 1984, he has worked to reduce O&M costs and lost generation due to ash particulate damage.  He has performed fundamental studies in a laboratory environment and designed and evaluated field installed flow modification baffle systems.

  • Particle Analysis and Testing to Determine Erosive Properties
  • Materials (Erosion) Performance at Simulated Boiler Conditions
  • Component Testing to Determine Low Erosion Designs
  • Physical and Computer Modeling of Boiler Components and Systems to Evaluate and Correct Gas and Particulate Distribution
  • Cold Air Velocity Testing in Boiler w/ Fans Running
  • Experience Includes Conventional Pulverized Coal (Utility Scale), and Industrial and Fluidized Bed Steam Generators

Mr. Drennen’s work experience includes 20 years in the ABB Combustion Engineering, Inc. Research and Development Laboratory in Windsor, Ct and 20-years of independent consulting. His expertise includes Instrumentation and Controls, Physical and Computer modeling of boiler systems and components and Cold Air Velocity Testing. He has a B.S. Degree in Engineering Science from SUNY@Buffalo, and is a licensed Professional Engineer in Connecticut.  Papers and Publications