[Digestion] Biogas fueling a diesel

[Michael Barnett]

Here is a resource online... in case you haven't seen it before.
http://www.gate-international.org/documents/publications/webdocs/pdfs/g36ene.pdf

Mike
JAMAICA


----- Original Message ----- 
From: "gp baron" <gpbaron4091 at yahoo.com>
To: "Zietsman, Rex" <Rex at Process.co.za>; <digestion at listserv.repp.org>
Cc: "Shelby" <shelby at biogaspower.co.za>
Sent: Friday, May 09, 2008 5:55 AM
Subject: Re: [Digestion] Biogas fueling a diesel


> Still on the "How long is this piece of string"" question, I looked at 
> Diesel to Natural Gas engine conversions (for buses & some smaller 
> vehicles) & found that the major work done involved:
> * pulling out the diesel injection system (nozzles, pump, etc.) and
> * replacing it with spark ignition system (plugs, distributor, etc.), 
> adding a governor & adjusting the compression ratio.
> Diesel-type engines apparently are preferred for Natural Gas service (& 
> presumably biogas since both are methane fuels) for their high compression 
> ratios or ratios that can be lowered to suit Natural Gas (or biogas.)
>
> Since governors, gas pressure & flow controllers can be purchased off the 
> shelf and installing spark ignition systems is a doable project, what are 
> the ideal compression ratios needed when fueling with biogas?
>
> Thanks in advance for any info or continued discussions on this topic.
>
> Gerry Baron
> Philippines
>
>
>
> ----- Original Message ----
> From: "Zietsman, Rex" <Rex at Process.co.za>
> To: digestion at listserv.repp.org
> Cc: Shelby <shelby at biogaspower.co.za>
> Sent: Friday, May 9, 2008 7:59:11 AM
> Subject: Re: [Digestion] Digestion Digest, Vol 23, Issue 3
>
> Mike,
>
> Realistically, you can get down to about 70% to 80% replacement but with
> a whole lot of challenges. With bleeding into the air intake, you can
> safely replace 50% of the diesel with low risk of mechanical problems -
> over fueling, etc. If you are running at a nice steady load, you can
> increase the replacement but, to get to the really high replacement
> values, you need to control both the gas and the diesel. This is less
> straight forward than simply bleeding in the biogas.
>
> For your information, there are engines out there that have pilot diesel
> injectors in addition to the main injectors. They start with diesel on
> the main injectors, introduce gas cutting back on the diesel until only
> the pilot injectors are running. This cuts back the diesel to as low as
> 1%, just enough to fire the gas mixture. So, when answering your
> question, it is a bit of "how long is a piece of string?".
>
> I cannot answer the explosivity question but would imagine that the risk
> is no more at a slightly hotter temperature than at a lower temperature.
> The gas density is less but the risk of leaks is just as good at ambient
> temperatures. Just make sure that the engine room is well ventilated to
> allow leaks to dissipate.
>
> All the best
> Rex
>
>
> Thanks Rex, and to all who have responded!
>
> I have taken a look at the website and it seems reasonably easy. Are
> there no explosion concerns about bleeding it into the air intake area?
> I am thinking if the engine room or air intake gets real hot as it can
> here in Jamaica.
>
> I am wondering how much percent diesel usage I could possibly replace by
> this arrangement?
>
> Mike
> JAMAICA
>
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