[Gasification] Blue Water Gas

Sun Nov 19 14:29:07 CST 2006

Jonathon, Jeff,

Interesting discussion regrading blue water gas, in particular the
integration wth an IC engine.

IC engines are regularly used as the source of suction to draw air through a
gasifier, and the exhaust gases contain both thermal energy and a source of
CO, CO2 and H2O, and some excess O2 in the case of a diesel.  Running a
diesel at part load, results in a higher level of excess air, and thus some
residual O2 in the exhaust gas.

Yesterday I took delivery of an exhaust gas heat exchanger for my 6hp Lister
engine.  It's a stainless steel tube 3" diameter and 48" long, that contains
19 internal tubes, though which the exhaust gases pass.

It was extremely good at extracting the heat from the exhaust gases, that
they were emerging at about 70F,  plus a lot of condensed water vapour.
Running the engine at 1kW electrical load, produced an equal amount of
energy in the circulating water.

At one stage there was not quite enough circulating water and I rapidly was
dealing with a steam generator.  It needs about 60 US gallons of water per
hour  circulating to keep the temperatures within reasonable limits.  There
is no reason why this could not be used to pre-heat water, and a small
leak-off then run through a super heater coil to produce steam at 600 F.

I have also been running the engine at just 300 rpm, which results in 150
exhaust cycles per minute.  Might it be possible to synchronise the gasifier
to the valve timing such that you draw gas through on the induction cycle,
having previously just used the exhaust cycle to blow steam, CO and CO2 into
the reduction zone?

Gas transfers can occur at surprisingly rapid rates, any one having played
with small Stirling engines will realise that you can easily expand and
compress a gas at some tens of cycles per second.

Might it be possible to use a Stirling type displacer to transfer the
products of  reduction, away from the reduction zone, whilst the hot
charcoal is being regenerated by a steam blast?

Think of it as two pairs of bellows.  The first blows air into the charcoal
to bring it to exothermic incandescence and raise its temperature, then
within half a second, the second bellows blows in steam, CO and CO2 from the
vehicle exhaust to form the gas by endothermic reduction.

Whilst we all think of these reactions taking place in different zones
within the gasifier, why not have them occur in the same zone, but at
different times?    A reaction zone the size of a bean can, continuously fed
with a supply of charred biomass, alternately gets a blast of air, and then
a blast of steam and CO2, with the whole process repeating  perhaps 5 times
per second.

Hot air engines function without valves, with the moving displacer being
driven by a rod through a linear guide or bearing.   It might be possible to
adapt this principle to make a gas transfer device that would shift the
products of gasification, in such a way that is immune to the action of
tars.

One last thought: Oxidisation being an exothermic process will raise the
temperature and pressure of the gas in a sealed reactor vessel. This
increase in pressure could be used to move a piston and do some useful work.
Blowing in steam and CO2 will result in an endothermic reaction and so the
reactor pressure will reduce, causing the piston to return to its original
position.

This is all starting to sound a bit like the Cayley - Buckett  engine of
1863 (UK patents 2075 and 4413) . Sir George Cayley was a pioneer of furnace
gas engines - see Bob Sier's Book "Hot Air, Caloric and Stirling Engines"
page 70 onwards.

Any thoughts?

Ken

----- Original Message ----- 
From: "Jonathan F. Pratt" <jonpratt76 at hotmail.com>
To: <gasification at listserv.repp.org>
Sent: Sunday, November 19, 2006 7:32 PM
Subject: [Gasification] Blue Water Gas

> Jeff,
>
> Seems like it is logical to utilize an ICE engine for a "blue water gas"
> like process.  But the engine exhaust isn't hot enough in itself for a
> straight reaction, not only are high temps required but continuous input
of
> heat is required to maintain the highly endothermic reaction.
>
> My understanding is that roughly half the waste heat of of ICE's come out
of
> the coolant and the other half roughly the exhaust.  To utilize as much of
> the "waste" heat as possibly it would work best to get your water directly
> from the coolant line, maybe run that at a little over boiling temps so
> essentially you use the coolant line as a boiler to make the steam but
> maintain the coolant as liquid water under pressure.  This system would
> require water injection under pressure to maintain equilibrium.  Have a
> pressure release valve of course for safety if water pressures get too
high.
> So there you have your steam source.
>
> Out the exhaust you get your exhaust heat.  You can think of a couple ways
> to extract that heat.  Maybe directly though some kind of  "heat" cycle to
> heat the charcoal, maybe injecting a mix of air+exhaust into the charcoal
> bed?  You could definately use a heat exhanger but I think you would need
an
> additional heat input for the reaction to be continuous, the fuel for that
> burner could come right from the gas output.
>
> Maybe the "optimum" here is to use a fluidizing bed reactor using sand as
> the heat transfer medium.  The sand circulates along with charcoal
particles
> no bigger than a few MM.  The sand is heated on one side by the exhaust +
> burner heat, inside the reactor charcoal is injected along with steam, the
> process and the gas produced keeps the sand "fluidized" in a clockwise
> fashion in and out of the reactor through the heater section.
>
> Jonathan
>
> >
> > Message: 2
> > Date: Sun, 19 Nov 2006 01:09:54 -0500
> > From: Jeff Davis <jeff0124 at velocity.net>
> > Subject: Re: [Gasification] Blue Water gas - Back to the future?
> > To: gasification at listserv.repp.org
> > Message-ID: <200611190109.54688.jeff0124 at velocity.net>
> > Content-Type: text/plain;  charset="iso-8859-1"
> >
> > On Saturday 18 November 2006 09:45 am, Thomas Reed wrote:
>
>> ------------------------------------------------------------------------
> >> Is it possible that we could make even better synthesis gas (water gas)
> >> using the blue water gas process and densified biomass?
> >>
> >> Comments?
> >>
> >> TOM REED            BEF
> >
> >
> > Well, this is a crazy idea that I think about from time to time:
> >
> > Components: engine, charcoal, steam
> >
> > - Special exhaust manifold that would be the reactor (heat charcoal)
> >
> > - More exhaust heat to make steam.
> >
> > - Inject the steam into the red hot charcoal (will the exhaust temp. be
> > high
> > enough??)
> >
> > This way we use the engine exhaust heat to reform our fuel and could
skip
> > the
> > air blown process (that's if the exhaust heat is high enough).
> >
> >
> >
> > Just one more crazy idea......
> >
> >
> >
> > Jeff
> >
> >
> >
> >
> >
> >
> > -- 
> > Jeff Davis
> > Somewhere 20 miles south of Lake Erie, USA
> > http://www.velocity.net/~jeff0124
> >
>
>
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