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Mark,
After doing the analysis the interersting point for me will be the
relative humidity of exhaust for a wood gas fueled engine because there
will be SO much extra nitrogen due to the nitrogen in the woodgas and the
combustion air. I suspect the calculated RH will be much less, but the
analysis will be less believable because I will have to assume there is no
steam in the wood gas which is just wrong but unquantifiable. I bet in
the real world the exhaust RH for a woodgas fueled engine will be the same
or higher than gasoline.
Stephen
-----Original Message-----
From: Mark Ludlow <[email protected]>
To: 'Discussion of biomass pyrolysis and gasification'
<[email protected]>
Sent: Sun, Dec 19, 2010 8:56 am
Subject: Re: [Gasification] Drying fuel with IC exhause and other
pleasures...
Steven,
omehow, your answer is about what I expected. The air you describe is very
et. You would have some latitude for drying feedstock, if the exhaust were
ery hot, however.
Thanks for making the effort!
ark
-----Original Message-----
rom: [email protected]
mailto:[email protected]] On Behalf Of
[email protected]
ent: Sunday, December 19, 2010 5:35 AM
o: [email protected]
ubject: Re: [Gasification] Drying fuel with IC exhause and other
leasures...
i Guys and Gals,
decided to tackle the relative humidity of exhaust question. The answer I
ot is that GASOLINE burning IC exhaust is 100% relative humidity at 120F.
t 140F it is 60% relative humidity. My analysis is at:
ttp://groups.yahoo.com/group/WoodGas/photos/album/118107394/pic/2025686540/
iew?picmode=&mode=tn&order=ordinal&start=41&count=20&dir=asc
or everyone to critique/inspect/laugh at. I will try to do the woodgas
quivalent tommorow. If you don't have access to this yahoo group, email
me
nd I will send the .jpg image of the writeup. Enjoy.
tephen
----Original Message-----
rom: Ken Calvert <[email protected]>
o: Discussion of biomass pyrolysis and gasification
[email protected]>
ent: Sat, Dec 18, 2010 8:39 pm
ubject: Re: [Gasification] Drying fuel with IC exhause and other
leasures...
----Original Message-----
rom: Ken Calvert <[email protected]>
o: Discussion of biomass pyrolysis and gasification
[email protected]>
ent: Sat, Dec 18, 2010 8:39 pm
ubject: Re: [Gasification] Drying fuel with IC exhause and other
leasures...
Heh! How often do us old timers have to come back on and say, forget
about
our
eorising, and will it or won't it? We have done it!
At Onesua Mission High School in the Pacific Isllands of Vanuatu, in the
ddleof the first Oil Shock in 1978, we had the boys cutting green Leucaena
ush as thick as your wrist and filling a hopper which had the exhaust of
a
onverted Toyota FJ ute engine driving a 25kva generator piped into the
ottom
th more than a couple of flame traps in the exhaust line. Even at 30ft
own
insulated exhaust pipe the gas is RED HOT. Dull red, but still hot. It
ook
three fires to learn that lesson! And there is such a thing as
ountercurrent' flow! The dryest wood comes out the bottom were the
hottest
as with the lowest relative humidity is going in! Psychometric charts
only
nto vogue in the last foot or so near the top of the hopper. And then the
ain
tion is heating the wood, not driving out moisture.
50mm x 50mm Wood blocks dripping-sap and moisture went in the top of
he
pper and three days later they came out the bottom so dry and so shrunken
nd
acked and shattered that you could pull them apart with your fingers.
And
hey were so dry that you could light them with a match. Didn't have any
isture meters, or what have you then, but they were dry! If you have
read
ny of the old literature, during the boom time in producer gas firing,
uring
e second World War,
u will know that with dry fuels there is very little hydrogen around to
oduce water vapour with. Burning charcoal alone, the gas is so dry that
he
s will lick all the oil off the cylinder walls and unless you take extra
ecial measures with lubrication you will sieze up your engine very rapidly
deed. When it comes to wood, there is just the right stoichiometrical
mount
water vapour available as the cellulose and other carbohydrates break
own
om C6H1206 to CO2 and H20 carbon and water vapour. You do need to add
xtra
ter as steam for coal coke and charcoal, but not for wood, even if it has
solutely zero water content. But don't let me stop you! Keep talking!
isten
Doug Williams. Hes not as old as me, but he's been there and done that!
en C.
-- Original Message -----
om: "Mark Ludlow" <[email protected]>
: "'doug.williams'" <[email protected]>; "'Discussion of biomass
rolysis and gasification'" <[email protected]>
nt: Sunday, December 19, 2010 8:07 AM
bject: [Gasification] Drying fuel with IC exhause and other pleasures...
If the IC exhaust is saturated at 100C, the best the wood can do is reach
n
equilibrium moisture content with respect to this environment. Best check
a
psychrometric chart to convince yourself. It's the partial pressure of
ater
in the exhaust that will, ultimately, inhibit drying, even though if the
feedstock is cooler that the I.C. exhaust, some heat may be transferred to
it via condensation on its surface. One simply need to know the dewpoint
of
the exhaust gas to determine whether or not this is a fool's errand. Flush
Pyrex Erlenmeyer flask with exhaust and fit a stopper with a penetration
or
an RTD and observe the temperature of condensation, as a first
approximation, and observe the water-carrying capacity along the line of
constant water. This is not 100% accurate, of course, because the specific
volume of the gas will change as it cools. Plus, if the dryer is "direct"
the gas will quickly mix with surrounding air.
What about home-made heat pipes? I use the commercial versions for
sensible
heat extraction on industrial heat pump systems.
Best, Mark
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of doug.williams
Sent: Saturday, December 18, 2010 10:29 AM
To: Discussion of biomass pyrolysis and gasification
Subject: Re: [Gasification] Gasifiers and greenhouses and CO2
augmentation.
Hi Toby and Colleagues,
You ask a couple of curly questions:
We seem to have moved on from the direct heating (drying) of fuel without
really answering the original question of water content in IC exhaust. I
understand the indirect heating, like Doug's >nearly horizontal heat
exchanger, but what about the direct introduction of engine exhaust gas
for
drying incoming fuel? Of course not all H2 is converted into H2O in an IC
engine, but one >would hope a significant portion is. Same with CO and
CO2.
If 15% is H2, is 15% of the exhaust water vapor?
I am sure there are equations that will confirm a "perfect" answer, other
than mine, which is more H2, more water vapour. So long as the gas is
otter
than 100C, wood can be dried down without any problems by direct contact.
Has anyone tried putting a producer gas fired engine exhaust directly into
a stock of wood fuel?
You have possibly missed the exchanges of discussing direct exhaust heat
into a fuel pile to make torrified wood. Ken Calvert specifically used
his
to overcome the problems of gasification in the tropics, and I had to use
t
in Papua New Guinea just to get enough dry fuel to start a gasification
project for the first time. We also used it on our first project back in
1978 in New Zealand, resulting in the wood blocks catching fire as we
earnt
the hard way, gaining experience. It's as simple as a drum with a gas
space
in the bottom, connected to the exhaust as close to the engine as possible
to reduce heat loss. It's best to try it and learn by experience if it is
for you, but, I would not want to promote this type of direct drying, for
anything commercial.
One final thought on greenhouse. Engine exhaust would presumably make most
of the CO into CO2 (but not all) and H2 into H2O, benefiting the plants.
Without question, it has been already established, that using producer gas
through an engine without first scrubbing the gas, could place the crop at
risk. I do however see a lot of potential to used scrubbed and compressed
CO2, used in a system of micro-porous support tubing to control white fly
and aphids.
This would seem to be an argument for having not only a gasifier, but an
engine or combustor in greenhouse application.
That is how it might appear, but there is very little demonstrated and
tested using producer gas to support any argument.
But is there any way to assure a safe level of CO for direct exhaust into
a
greenhouse? Does it rise or fall in a collum or can one assure a complete
reaction in some way?
Issues of CO and human safety usually resort to badge monitoring for the
individual. Plants however only thrive, I have been advised, in a 10% CO2
atmosphere. I cannot imagine it piling up as layered slug of inert gas,
as
the greenhouse should have a circulation capability if heated. Not sure
hat
you mean by a complete reaction.
Does this help or hinder?
Doug Williams,
Fluidyne.
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e Gasification list has moved to
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he change.
ease visit http://info.bioenergylists.org for more news on the list move.
ank you,
sification Administrator
_______________________________________________
he Gasification list has moved to
[email protected] - please update your email contacts to
eflect the change.
lease visit http://info.bioenergylists.org for more news on the list move.
hank you,
asification Administrator
_______________________________________________
he Gasification list has moved to
[email protected] - please update your email contacts to
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he change.
lease visit http://info.bioenergylists.org for more news on the list move.
hank you,
asification Administrator
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