[Gasification] water injection of producer gas fired ic engines

[jim mason]

On 7/6/06, Jesse Klinkhamer <j.klinkhamer at kleanindustries.com> wrote:
> Dear Peter,
>
> Emulsion has been being used for years and is currently being used in Tokyo
> on many major public transit bus routes in the city center as an alternative
> cleaner burning fuel.
>
> Please have a look at the simple emulsion systems available.
>
> http://www.kleanindustries.com/s/Refining.asp?ReportID=128054
>

sorry for the delay.

yes, the emulsion tech is very interesting.  thank you for that that
link.  yet again kleanindustries seems to be around many of the
interesting problems and opportunities.

after a bit of poking around, i find that there is lots of work going
on (very old in origin) on water injection for NOx, CO and soot
reduction.  especially in diesel engines, the emissions reductions are
impressive, often by multiple, not percentages.  there is also much
work on water for a fuel saver in liquid fuel situations, with results
seeming modest, mostly in the 10-20% range.

the valve eroding issue seems very small, and really, isn't even
highlighted as a problem in the continuous water injection
applicaitons i found, including forums where people are running full
time water injection.  not even much suggestion of the benefits of
distilled water over tap, which certainly will vary the mineral
content hitting metal insides.  but i'm sure very high power in near
continuous operation, like in a fighter plane, will have different
considerations.  most water injection in mobile and gen set apps is
intermittent high amounts of water in high power apps, or constant low
amounts in low power apps.  a very different use scenario than a
Merlin V-12 flat out in a dog fight.


the delivery of the water can be of various systems, each with
benefits and liabilities, as usual.  the emulsions don't require any
mech mods, but also don't allow for the variation of water, which is
important.  higher power loads can take more water.  too much at idle
and things are rough.  also, i don't know how they are running the
emulsions through diesel fuel injectors.  such usually erodes the
nozzles in my experience.  and the injection pump.  thus all the fuss
about getting water OUT of emulsion with veg oil systems.  maybe we
are missing something with the veg oil systems and should solve the
mech problems so we can leave the water IN.

the other delivery methods are combined diesel and water injection
systems.  i found examples of full parallel injection systems, one for
fuel, one for water.  and one system that mixed water in on as a
fractional load on each injection, in the injector body itself.

by far the most common method is intake fumigation/injection.  for
turbo and supercharged motors, this is best done after the charger so
as to not degrade the turbine (same problem as low temp steam in a
power plant turbine) and to act as a intercooler, cooling the charge.

and of course there is lots of piror art on water injection in
performance applications, where you are mostly using the water
injection to keep things cool enough in high boost and compression
ratio situations so as to reduce detonation.  water has a 6x higher
specific heat than gasoline/etc, so a smaller amount of it will do the
same work as more gasoline/etc, so it is better thant he usual
solution of enrichening the fuel mixture to keep things cool and
thereby running as a lower power fuel/air mix ratio.

the additional benefit, and the one that started this discussion, is
the unique ability of water to finish the oxidation of CO to CO2.
this helps in the emissions issue, but also in the power maximizing
issue.  given that producer gas is mostly CO, it seems that water
injection would be of particular interest in producer gas power ic
engines.  but i have yet to be able to find an example of a test.

there are many commercial sellers of water injection products, as well
as plans for DIY units.  some relevant links here:

-main manufacturer: www.aquamist.co.uk/
-good starting info site: http://www.waterinjection.info/
-water injection forum: http://www.waterinjection.info/phpBB2/
-also most all the diesel truck performance companies.  most have
water injection systems.

the core tech papers on this are the WWII era research from NACA.  the
two main papers are here:
-http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930093147_1993093147.pdf
-http://naca.larc.nasa.gov/reports/1945/naca-report-812/naca-report-812.pdf


so in short, and in conclusion, water injection seems like it would be
particularly beneficial to ic motors running on producer gas.  the
high percentage of CO, and tendency to exhaust a good portion of it
due to its slow combustion, would much benefit from the presence of
additional water.

NOTE that the water in the original biomass is NOT in the producer gas
fuel to any significant degree.  it was degraded on the hot char bed
by the reaction C + H2O = CO + H2.  it is this reduction of water that
is one of the main producers of the CO and H2 that we are using in
producer gas.  the other main CO source is from the reduction of CO2
by the equation C + CO2 = 2CO.  if too much water is added in the
gasifier, you get more CO2, as it finished the combustion of the CO
you just struggled to make.  very bad.  we want to do this in the ic
motor, NOT in the gasifier.   so, water injection into the ic motor is
a VERY different proposition than a high water content fuel in a
gasifier.

our associations with water tend to suggest it will be a dilutant in x
process.  in the situation of completing the combustion of CO to CO2,
we should really think of it as a FUEL and OXIDANT.   the decoposition
of hte water is producing more H2, which combusts very quickly, even
when produced late in the combustion cycle.  and it is completing the
CO to CO2 reaction by the liberated O2, and is thus an oxidant.

so, it should be our PLEASURE to carry water onboard.  even if burned
1:1 by weight to biomass, filling a water tanks sure sounds alot
easier to me that preparing more gasifier fuel.

seen as such, a gasifier/ic rig could be sold as  . . .

"the engine that runs on water and trash"

jim


ps- has anyone found a good source for pelletized municipal solid waste?