[Gasification] water injection of producer gas fired ic engines

[jim mason]

On 7/8/06, Peter Wilson <petergwilson at gmail.com> wrote:
>
> Fascinating. Thanks for all of this - I now see that it's better to inject
> the water into the cylinder than to introduce it into the gas stream prior.
> I see one problem though - if one uses a Kalle gasifier (which use exhaust
> CO2 to reduce the heat of the gasifier), then there may not be enough CO2
> left in the exhaust to cool the gasifier down. Interesting...
>
>

well no, with water injection you are going to get more CO2 in the
exhaust.  perfect exhaust is ALL CO2 and nothing else, remember.

from my reading on the kalle, it seems the kalle uses the exhaust gas
to mostly cool the nozzle tip, by diluting the O2 in the air blast.
given that kalles run on charcoal dust, the fuel is very dense, and
the combustion zone if very small, thus is gets VERY hot.  the swedish
gengas books says they will melt the nozzle and grate in about three
minutes if the ic exhaust gas recirc is not established immediately on
start.

and also, they claim noticable efficiency increases by the CO2
recirculation of the kalle, but no numbers are given.  this makes
sense, as CO2 is being reintroduced for further reduction to CO.  less
C is needed from the combustion of more char, thus reducing the
consumption of char in the gasifier.  also, the less char that needs
to be oxidized to make CO2, the less heat that is generated, thus
solving the original problem.  two nice gains.  thus why the kalle had
such a long run it seems.

and no, this is not a perpetual motion machine.  there still needs to
be oxidation to produce the process heat that heats the charcoal so
the reduction reactions can happen.  those again, are: C + CO2 = 2CO
 and   C + H2O = CO + H2.


relatedly, has anyone here yet to notice that all this fuel we are
burning to make process heat to run the gasification reaction is
largely the same thing happening next door in the ic motor?

on gasifier/ic rigs, it seems somewhat silly to have two combustion
areas, then waste most all the heat from one of them out the exhaust
(i.e the ic exhaust).  getting most all the heat from the ic exhaust
back into the gasification reduction zone for process heat seems
obvious.  it is odd that the kalle is the only one that is really
doing this.  there is lots of heat coming out the exhaust of an ic
motor.

it seems there is a gasifier/ic rig design floating out in possibility
that is somewhat of a two vessel fluidized bed sort of design.  the ic
engine is the combustor making the heat.  the gasifier uses the ic
exhaust heat as process heat for the gasification reaction.  maybe
both as heat transfer, as well as direct exhaust gas contact, or CO2
blast.

basically a two vessel, CO2 blast gasifier, with process heat from the
ic motor.  given the exhaust velocities, it seems to beg to be a
fluidized bed or suspended flow type.  run it on packed sawdust.

this still wouldn't get rid of the always annoying N.  but it would to
recycle much of the ic waste heat, as well as recycle much of the C,
so that less char is consumed.

has anyone built such a thing?   does this exist?

j



>
> Peter
>
>