EPA-HQ-OAR-2008-0708-DRAFT-0315[1]

----- Forwarded by Melanie King/RTP/USEPA/US on 12/08/2009 02:52 PM

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

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 |Melanie King/RTP/USEPA/US@EPA 

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 |12/08/2009 02:39 PM 

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 |RE: stationary engine malfunction 

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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 

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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 

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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 control 

scheme 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

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______________________________________________________________________________

____________________________________________________

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 

Agency

Mail Code D243-01

RTP, NC 27711

Phone: (919) 541-2469

Fax: (919) 541-5450

king.melanie@epa.gov

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