EC

/R Incorporated Providing Environmental Technical Support Since 1989

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MEMORANDUM 

TO: Melanie King, EPA OAQPS/SPPD/ESG

FROM: Bradley Nelson, EC/R, Inc.

DATE: January 15, 2010

SUBJECT: Summary of the October 20, 2009 Teleconference with Exterran and the U.S. 

Environmental Protection Agency to discuss the Proposed NESHAP for Existing 

Stationary Spark Ignition Reciprocating Internal Engines

1.0 INTRODUCTION

Exterran requested this teleconference with EPA to discuss the proposed national 

emission standards for hazardous air pollutants (NESHAP) for existing stationary reciprocating 

internal combustion engines (RICE). The main focus of the discussion was on the proposed 

emission standards for two-stroke lean burn (2SLB) engines. This meeting summary will be 

available in the docket for this rulemaking (Docket ID No. EPA-HQ-OAR-2008-0708). The 

proposed NESHAP for existing stationary RICE was published in the Federal Register on March 

5, 2009 (74 FR 9698). 

2.0 ATTENDEES

U.S. Environmental Protection Agency

Melanie King, OAQPS/SPPD/ESG

Michael Horowitz, OGC

Exterran

Mike Wasson

Bill Bowes

James Harrison 

Kyle Jantzen

Bracewell & Giuliani

Jeff Holmstead

Rebecca Rentz
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JW Power Co.

John Dutton

Compressor Systems Inc.

David O’Leary

EC/R Incorporated

Bradley Nelson

3.0 SUMMARY OF MEETING

Exterran stated that it has approximately 1,000 stationary 2SLB engines operating in the 

field. Nearly all of these 2SLB engines are manufactured by Ajax, and none are equipped with 

oxidation catalyst. Exterran believes that the emission standard for 2SLB engines should not be 

based on the use of an oxidation catalyst because it is not cost effective. In addition, Exterran 

believes that there are technical and reliability issues with retrofitting an existing 2SLB engine 

with an oxidation catalyst in the field. Exterran estimated the cost per ton of using an oxidation 

catalyst on a 2SLB engine to be $120,000 per ton of HAP removed. This value was calculated 

using vendor cost data and assuming 90 percent reduction of hazardous air pollutants (HAP). 

Exterran stated that oxidation catalysts typically only achieve 60-70 percent HAP reduction. 

EPA asked if Exterran could provide the vendor costs. Exterran responded that they would 

provide the cost information to EPA.

Exterran stated that Cooper, Clark, and Ingersoll-Rand engines in the range of 1,500-

2,000 horsepower (HP) used for compression would need manifold work and new ignition 

systems for the oxidation catalyst to operate properly. Exterran believes even with these 

modifications, 90 percent reduction of HAP is not guaranteed. Exterran also stated that many of 

these compressor systems are integrated units (e.g., engine/compressor) and therefore, would in 

many cases need to replace the whole unit. Exterran added that older engines are not fuel 

injected and the combustion system would need to be upgraded before an oxidation catalyst 

could be retrofitted.

Another issue raised by Exterran was whether 90 percent HAP reduction could be 

achieved using an oxidation catalyst. Exterran believes that 2SLB engines have insufficient 

exhaust temperatures to oxidize 90 percent of the HAP in the exhaust stream. Exterran stated 

that exhaust temperatures of 600-650 degrees Fahrenheit (°F) are needed for effective operation 

of the oxidation catalyst, and a 360 HP Ajax 2SLB engine has an exhaust temperature of 350-

400 °F. In addition, Exterran noted that the oxidation catalysts create backpressure in the engine 

exhaust. EPA responded that the information that it has reviewed shows that an oxidation 

catalyst can be effective at exhaust temperatures as low as 450 °F. Exterran stated that it would 

like to receive the data that shows the catalyst in operation. Exterran noted that has not seen any 

data that shows that oxidation catalyst will achieve effective HAP reductions from stationary 

2SLB engines.
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The Exterran group asked EPA if they have received any information on the proposed 

extension for SI engines. EPA responded that they have not received any new information 

regarding the extension for SI engines.