[Gasification] Two Engines One Gasifier

[Rex Zietsman]

Thanks Doug. I was imagining the challenge of trying to start the two
engines including the gas distribution but had not given the harmonics a
thought at all. Good point. Really where I am coming from is to have a
common generator. The challenge of getting two generators to run in sync is
fine on the MW level but a huge challenge down at small scale. As it is,
speed control is already somewhat of an art as the speed is a function of
load on the generator and a change in speed has an effect on the load of the
gasifier where the gas CV changes until the new equilibrium is established.
Just not as simple as adjusting the throttle as one would with
petrol/diesel. 

The clutch you mention: I am assuming that you would put a stripped down
gearbox on the end of the motor and use a normal car clutch. If there is a
simpler method, I would most welcome it. We frequently want to be able to
offer a system that can both drive a generator or a mechanical devices such
as a maize mill. A belt drive clutch would allow us to choose run the
generator all the time and to pull in the maize mill when required. Do you
know of any system that has this? Possibly I could look at an electric
clutch similar to that used with air conditioners. Any advice would be
appreciated.

Kind regards

Rex Zietsman
Principal Consultant
-----Original Message-----
From: Doug Williams [mailto:doug.williams.nz at gmail.com] 
Sent: 01 April 2015 11:17 PM
To: Discussion of biomass pyrolysis and gasification
Cc: Rex Zietsman; linvent at aol.com
Subject: Re: [Gasification] Two Engines One Gasifier

Hi Rex,

The Multi engine project was done without my input except after the fact!
They could start one but it ended there, plus the concept was flawed due to
how the engines were connected to the central shaft. What they did not
resolve was how to couple the generator and keep the two separate assembles
in line.

The other main factor that worked against the engines all mounted on the
same skid, was that the engine harmonics would have begun to destroy the
fabrication of the structure. I had long talks with Marine engineers about
this after the multi engine inventor left the project.

Two separated engines driving a common shaft clutched to allow separated
starts and stops, would simplify the switch from peak power to the less than
half output that would require only one engine. You also need separate
air/gas mixers, as the gas piping will always affect the gas flow in a way
that is difficult to instrumentally measure. I usually tune the engine by
ear first, then have a fixed mark on the valves for a basic system, and the
engine will start with only a few cranks every time. Hope this helps, but
let me know if you have any problems. Doug Williams, Fluidyne.


> Doug,
> 
>  
> 
> I have seen photos on your website of multi-engine operation driving a
> central shaft to a single generator. So I know you have done it. We have a
> small design that goes nominally up to 40kW as this is the largest petrol
> engine we can reasonably find - 7 litre V8. I guess putting two of them in
> parallel would be manageable as well. I would be squeamish about the start
> up though.


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