gas engines - oxidation catalyst cleaning 2

[ivymike]

There are a number of companies offering cleaning services for oxidation catalysts and three-way catalysts used on gas (methane, etc) engines. Many of these companies also sell catalysts, catalyst/silencers, and replacement elements. I'm wondering the following:
- have you had good/bad experiences with any particular cleaning services?
- do you generally ship your elements off for cleaning, have someone come pick them up, or have them cleaned on-site?
- how often do you need to have your catalysts cleaned, and how do you know when it is time?

 

[dcasto]

We use EMIT in Sheridan Wyo. We do it everything 6 months.
We clean based on experience. Sometimes, we do not pass quarterly tests and the engines don't pass and we put a spare in and they pass.

 

[catserveng]

The company I worked at for several years provided the service on units we had under maintenance contracts. The results varied so much it became pretty much a money loser and we finally got out of it.

Problems, different masking debris requires different cleaning methods. Severe oil masking, like from a turbo failure never came back to be able to make compliance (at least not in CALIF)

The in and out handleing caused a lot of physical damage to catalyst, face it it's a lousy job and most techs doing it just want to get it done and weren't too careful doing it.

We got very poor support from catalyst manufacturers in how to properly clean their catalysts, and when we did follow their instructions and recommendations, then didn't pass a compliance test is was always our fault anyway.

To be fair, we were in a very tough market, everything had to be in near perfect condition to maintain compliance levels.

We had some sites that had been problem children (older models engines or low load factors causing higher oil consumption) that by installing "guard beds" basically untreated catalyst substrates to act as filters, we had better success.

On oxidation catalysts we tried quarterly vacuuming and blowouts, worked well if somebody checked after guy doing work, problem was no one wanted to give us the time to let the catalyst cool completely to do a proper cleaning.

We tried several companies in California, Arizona and Nevada and never rerally had very good results with any of them, although two of the companies we used in Arizona would take out catalysts that wouldn't pass in SOCAL and sell them into other markets with less stringent requirements.

The primary method we used to determine when a catalyst needed cleaning was a differential pressure gauge. Different manufacturers had varying recommended numbers, overall we used twice the "new" reading to start to schedule, get it out before actual reading got to 4X of the new reading. Our experience on the engines we dealt with, mostly power generation units and some oil field applications was that if you let delta pressure exceed 4 times original reading you likely wouldn't recover the catalyst at all.

Some of our power gen customers watched the delta temp on three way catalysts and compared to other parameters, as soon as they noted a drop in reductions they pulled them and dropped in their spares, costly but cheaper than a fine and associated trouble from APCD.

Hope that helps

 

[ivymike]

that is helpful. 4x original pressure drop seems REALLY high, though.. didn't these start out at 8" H2O or so?

 

[catserveng]

We tended to oversize catalyts a bit (okay alot) because of the high reduction rates required by our customers. New pressure drop across the catalyst was 3-6 inches, our absolute limit was based on exhaust total restriction of 29 inches H20, most of our field guys used a combination of pressure drop and results from the emissions analyzer to determine when to clean. 2 times for start thinking about it and 4 times for "get it off now" were pretty good rules of thumb for us based on most of our customer base.

I've seen what I think are pretty marginally sized catalysts in other parts of the country, so whatever the local air board lets you get by with is the starting point, and my rules of thumb my not exactly apply.

These numbers also varied based on if the site had heat recovery, or a critical grade silencer.

Our own experience came as the result of a number of rear end kickings and financial penalties. We always used an emissions analyzer and did both front and back end readings everytime for NOx, CO and O2, plus did a worksheet for other engine parameters to helps us determine state of tune and compliance levels. It was costly and in the end, cost us some business for a while, then the customers started getting fined and the other service companies just couldn't do all that was needed to keep the engines in compliance. Some customers shut down, some realized it was another cost of doing business in this state and dealt with it.

Hope that helps.

 

[ivymike]

Yeah, that does help. You don't happen to know anyone at Hawthorne who could give me more info on the cleaning services that they provided in the past?

 

[catserveng]

Try Tim Roberts, he is at Hawthorne Power Systems and is the Contracts Maintenance Manager, he was not around back then but he probably has the info available and I think he still has a few contracts that he has to service catalysts as part of the package.

http://www.hawthornecat.com

select San Diego for region and then click on Power Systems, should get you the main number and then they can get you to Tim.

 

[ivymike]

thanks!