EPA-HQ-OAR-2008-0708-DRAFT-0315[1] ----- Forwarded by Melanie King/RTP/USEPA/US on 12/08/2009 02:52 PM

----- |------------> | From: | |------------>

>--------------------------------------------------------------------------- ---------------------------------------------------------------| |"Stachowicz, Bob" <bob.stachowicz@dresser.com> |

>--------------------------------------------------------------------------- ---------------------------------------------------------------| |------------> | To: | |------------>

>--------------------------------------------------------------------------- ---------------------------------------------------------------| |Melanie King/RTP/USEPA/US@EPA |

>--------------------------------------------------------------------------- ---------------------------------------------------------------| |------------> | Date: | |------------>

>--------------------------------------------------------------------------- ---------------------------------------------------------------| |12/08/2009 02:39 PM |

>--------------------------------------------------------------------------- ---------------------------------------------------------------| |------------> | Subject: | |------------>

>--------------------------------------------------------------------------- ---------------------------------------------------------------| |RE: stationary engine malfunction |

>--------------------------------------------------------------------------- ---------------------------------------------------------------|

Hello Melanie,

I apologize for the length of time that I needed to respond. As I indicated in my first acknowledgement, these are not simple issues and there is no single "correct" answer. Also, while I have some knowledge of industry practices in general, I can speak directly only for Dresser-Waukesha. I will address each of your four questions:

What are some typical causes of malfunctions in engines (and any associated engine emission control system)? Webster's dictionary defines malfunction simply as "to function imperfectly or badly : fail to operate normally". The EPA definition excludes "Failures that are caused in part by poor maintenance or careless operation" and appears to include only something "which causes, or has the potential to cause, the emission limitations in an applicable standard

to be exceeded". This is a much more narrow and directed definition. There are a multitude of potential malfunctions in an engineered product as complex as a reciprocating, internal combustion engine system that includes the Page 1EPA-HQ-OAR-2008-0708-DRAFT-0315[1] engine, an electronic control system which may control both the engine and part - or all - of the aftertreatment system, and the aftertreatment itself.

A malfunction can occur in any of these areas. Current and proposed emissions

standards are so restrictive that there is almost no allowable variation in any area in order to continuously comply with the standards -- everything must function near flawlessly. Since a modern SI RICE system is so complex, failure/malfunction of almost any component can affect output emissions levels although they may not be affected to the point of non-compliance. Note that, while I will try to keep the EPA definition of a malfunction in mind in my responses, many malfunctions that could meet EPA's malfunction definition can be exacerbated by poor maintenance or careless/improper operation. One example of this would be a spark plug that would fail early under normal operation but will fail even earlier under improper operation. Would the "in part" phrase in EPA's definition exclude this circumstance from being considered a "malfunction"? If so, the EPA definition of malfunction may be too restrictive from a practical perspective for an engine system versus other types of stationary sources such as large power plants. This sort of circumstance relates to my question to you about how EPA would look at a malfunction that was colored, in some fashion, by poor maintenance or careless operation. Specifically, how are "poor" and "careless" officially defined and who would make the final determination if the maintenance was "poor" or the operation was "careless"? There are several possible causes of malfunction outside of poor maintenance or careless/improper operation. These can include a manufacturing error such as machining a part outside of blueprint tolerances, a part inadvertently made of, or including, non-conforming material, statistically expected random and early failure such as B10 life for bearings or illustrated by the bell-curve distribution, ambient and operating conditions including a fuel composition change, human error, and "acts of God". An example of the latter may be a nearby lightning strike that directly or indirectly affects electronic controls such that engine operation continues but in an abnormal

manner. Typical gas engine malfunctions originating from any, or other, of the preceding causes include spark misfire, spark timing shift, engine backpressure increase or decrease, engine crankcase pressure change, abnormal coolant temperature, valve train operation out-of-specification, abnormal/high vibration levels, air/fuel ratio shift, and breakage of virtually any engine
component. Some issues that can directly affect emissions may not meet the EPA definition of "malfunction" but may be considered a "failure" even though that failure is normal. "Normal" in this case means very gradual performance degradation, usually of the aftertreatment, due to length of operating time. One of the best examples of this is the steady decrease of performance of a catalyst due to continuous exposure to heat (resulting in slow sintering and loss of performance), particulate (even the cleanest of engine exhaust streams contains some particulate from combustion of engine oil which will eventually mask the active catalyst material), and chemicals (engine exhaust may contain trace amounts of antifreeze if there is a minor, internal, coolant leak and all engine oils contain additives which will add known catalyst poisons to the engine exhaust stream). While such a failure could be considered "reasonably preventable" from one viewpoint since the processes are known as well as the fact that it will happen is known, the way in which these factors combine to degrade a catalyst can vary the degradation rate significantly with the result that loss of compliance could be looked at as sudden and infrequent.

What usually happens when these malfunctions occur? The results of Page 2EPA-HQ-OAR-2008-0708-DRAFT-0315[1] malfunctions are as varied as the possible malfunctions themselves and will cover the entire spectrum from no practical effect to significant effect on either engine performance, engine emissions, or both. Malfunction of a non-critical component, such as breakage of an air filter brace, may increase local vibration levels but will have no discernable effect on engine operation or emissions. Other malfunctions can have an immediate and direct effect on engine operation and output emissions. Examples of the latter would be a sensor or control wire breaking or shorting due to vibration or a spark plug failure resulting in a severely misfiring or dead cylinder. In these latter cases engine emission levels and, of course, engine performance can change drastically and suddenly.

Does the engine typically shut down automatically, or does it have to be manually shut down? This will depend on the exact nature of the failure and the safety and operational control scheme applied to the engine system. Most modern stationary engines have some level of electronic control in addition to mechanical safety and operational sensors and controls. The control response algorithms will determine whether the engine shuts down automatically or is allowed to operate until a manual shut-down is performed to investigate the malfunction. Malfunctions determined by the control algorithms to be critical will likely result in an automatic shut down to protect the engine or aftertreatment or both. See also the following question / response.

Can the engine still continue operating even if it is malfunctioning? Simplistically, of course the answer is yes. However, again, reality will depend on both the specific nature of the malfunction and the specific controlscheme applied to the engine system. Some malfunctions are considered noncritical and the engine will be allowed to continue operating. Note that a secondary function of a control system/scheme may be to send a signal to a monitoring station indicating a malfunction has occurred even if the engine is allowed to continue operation. Other, more significant, malfunctions may call for an emergency stop to prevent a possible catastrophic failure. If the malfunction is serious enough it may cause the engine to cease operation - sometimes catastrophically - independent of any control and shutdown scheme. Usually, significant parameters such as temperatures, pressures, speeds, vibration, knock, etc are monitored rather than trying to detect malfunctions themselves as most malfunctions that will affect engine performance and/or

emissions will manifest themselves as a detrimental shift in one or more of those parameters. The algorithms programmed into the control scheme will decide whether to allow continued engine operation, allow operation and send a warning, or immediately stop engine operation. Older engines, those with mechanical/hydraulic control systems, function the same in principle but have much less response flexibility compared to engines with at least some electronic control. In either case, "nuisance" shut-downs -- those not due to a true malfunction issue -- must be minimized as far as practical without putting the engine, driven equipment, or operational limits in jeopardy. Nuisance shut-downs can become very expensive to an owner/operator if allowed

to continue.

I hope that this adequately addresses your questions. If I can contribute anything further please let me know.

Sincerely,

Bob Stachowicz Page 3EPA-HQ-OAR-2008-0708-DRAFT-0315[1]

_ ____________________________________________________________________________ _

_ __________________________________________________ _ Robert Stachowicz, PE | Staff Engineer | Dresser, Inc., Dresser Waukesha | 1101 West St. Paul Avenue, Waukesha, WI, 53188 | 262.549.2753 | 262.549.2705 (fax)

From: King.Melanie@epamail.epa.gov [mailto:King.Melanie@epamail.epa.gov]

Sent: Tuesday, November 24, 2009 8:21 PM To: Stachowicz, Bob Subject: stationary engine malfunction

Hi Bob, Hope you are doing well. Can you help me with a question about stationary engine malfunctions? What are some typical causes of malfunctions in engines (and any associated engine emission control system)? What usually happens when these malfunctions occur? Does the engine typically shut down automatically, or does it have to be manually shut down? Can the engine still continue operating even if it is malfunctioning? I'm asking about malfunctions as defined by EPA for the MACT program, the

definition is:

"Malfunction means any sudden, infrequent, and not reasonably preventable failure of air pollution control and monitoring equipment, process equipment, or a process to operate in a normal or usual manner which causes, or has the potential to cause, the emission limitations in an applicable standard to be exceeded. Failures that are caused in part by poor maintenance or careless operation are not malfunctions."

So I'm interested in failures that would not be caused by poor maintenance or improper operation of the engine, since by the EPA definition, that wouldn't be considered a malfunction Thanks and have a great Thanksgiving,

Melanie King Energy Strategies Group Sector Policies and Programs Division Office of Air Quality Planning and Standards U.S. Environmental Protection

A genc y

Mail Code D243-01 RTP, NC 27711

Phone: (919) 541-2469 Fax: (919) 541-5450 king.melanie@epa.gov

Page 4