[Gasification] water injection of producer gas fired ic engines

[jim mason]

On 7/6/06, Peter Wilson <petergwilson at gmail.com> wrote:
> That is an interesting question. I had always thought that it was possible
> to get a higher energy content from producer gas by applying the blue water
> gas process, after the initial gasification stage. This would introduce the
> water gas shift reaction into the gas at a much earlier stage. What may not
> be possible is carrying all the water on board, as well as the weight (and
> expense) of another reactor vessel to make the blue water gas.
>
> Has anyone tried this in a vehicle application (somehow I doubt it).
>
> Peter
>


i might be misunderstanding, but there is no need for another reactor
vessel.  you want it all to happen in the combustion chamber of the
engine, where the exothermic nature of the reactions can be mined by
the piston.

the two relevant reactions here are:

the carbon-steam reaction: C + H2O = CO + H2

the water-gas reaction: CO + H2O = CO2 + H2

the water under combustion temperatures is adding fuel to the
combustion through introducing more H2 and helping to complete the
shift of C to CO to CO2.

of course there are many gasification processes which introduce steam
into pyrolysis or a gasifier, but typically with an increase in CO2
output.  thus why you don't want too wet of biomass in your gasifier.
but other processes, such as pyrolysis ones which are trying to
optimize methane production (CH4), use the steam to increase the
portion of CH4 created, then scrub out the CO2 later.

anyways, for our purposes, we don't want more steam in the gasifier or
we are going to get too much CO2.  which we don't want until the
combustion chamber of the ic motor.  so i'm only asking a question
about what is the prior art on water injection into an ic motor run on
producer gas.

as for harmons comment on the lack of CO in properly combusted
producer gas, my understanding is that ic motors run on producer gas
actually exhaust significant CO, even when properly mixed.  the number
in the "generator gas" book on the sweedish wwii experience suggests
10-20% i think.  gasoline exhausts CO in the 6-7% range i think.

there are MANY warnings in the sweedish generator gas book about the
dangers of CO not just from the gas generator, but also from the
exhaust.  it is of much greater concern than with a gasoline ic motor.
 espeically at idle.  the precautions suggeted and taken are
non-trivial.  no stopping even your well warm and running producer gas
running engine in garages or under carports.  no sitting in the car on
long idle.  no standing downwind for long time of producer gas running
car.  etc etc.

anyways, the point being, there seems to be much more unburned CO
coming out of a producer gas run ic motor than a gasoline motor.
water injection in the ic intake would likely do much here.

this must have been tried.

?

j






> --
> Peter Wilson
> Dunedin, NZ
>
>
> On 7/7/06, Harmon Seaver <hseaver at gmail.com> wrote:
> >
> > On 7/6/06, jim mason <jimmason at whatiamupto.com> wrote:
> > (snip)
> > >
> > > 1.  the relatively high emission of unburned CO is producer gas fired
> > > ic motors (10-20% i think) would be reduced, with a related increase
> > > in power.
> > >
> >    Why would there be any unburned CO? There shouldn't be any if the
> > engine is appropriate for woodgas; i.e., of high enough compression
> > and spark advanced enough. And as long a stroke as possible.
> >
> >
> >
> > > 2. the notorisously slow flame front of producer gas would be
> > > generally increased as the CO would complete its combusion faster.
> > > higher rpms would be possible.  but also for the same reason, the
> > > engine would be limited to lower compression ratios.
> >
> >   Bad move, that. You want at least 16:1 compression. More is better.
> >
> >
> > >
> > > for a slow speed genset, all this is likley not helpful, as the slow
> > > rpm tends to give enough time for full combustion to happen.  for a
> > > mobile application where momentary higher power is needed, this seems
> > > very important and potentially very helpful.
> >
> >    For the vehicle applications, diesels are the best bet -- that way
> > you not only have the appropriate compression, but the injection pump
> > will automagically add more fuel when needed. So you can have
> > essentially almost full rated hp when accelerating or hillclimbing,
> > but then run most of the time just on woodgas.
> >
> >
> >
> > --
> > Harmon Seaver
> >
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> >
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