Re: GAS-L: Gasifier Annual Use and Engine Life

[AJH <andrew.heggie@dtn.ntl.com>]

On Tue, 29 Oct 2002 09:45:25 -0800, "Tom Miles" <tmiles@trmiles.com>
wrote:

> The requirement for most CHP systems would be 4,000-6,000 hours per year.

The figure of 8000 is more generally used here in UK.

Now with regard to micro chp (which I will hazard a definition as "chp
for personal use" rather than chp for onward sale of heat and
electricity):

Our little diesel genset runs 8 hrs, 5 days a week, It replaced one
that ran 20k hours without major overhaul.

>What are the annual use and engine life targets for companies building gasogensets?

This must also depend on the capital cost of the engine, e.g. our
10kVA genset cost us GBP6000, we anticipate an engine life of > 20k
hours, however there are considerable servicing costs of labour and
parts. Ford licensed an engine designed for outboard use, this was a
total loss lubrication 2 stroke engine. The theory was that a total
loss engine had a constant oil use throughout its life, whereas a
recycled lubrication system burned more oil as the engine became worn.
It contained no serviceable parts, I never did hear what happened to
it. So at what stage would it be worth using a 13hp Honda engine at
GBP400 and replacing it each year?

I know NRI did an analysis of engine wear on 2 engines run on producer
gas (CO and Nitrogen) from a char gasifier and concluded engine life
was not noticeably altered.

Can anyone cite the mechanisms for reduced engine life? I can see
condensation of tars and contamination of oil as reasons for frequent
overhauls and oil changes but the only wear mechanism I can see ( as
long as the lubricant remains in spec)is ash getting into the engine.
IIRC this only becomes a problem when the ash particles are greater
than the depth of lubricant film on the part affected.


AJH

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