Dear GF
----- Original Message -----
From: [email protected]
To: [email protected]
Sent: Thursday, November 28, 2013 11:51 AM
Subject: Re: [Gasification] Fluidised Bed Reactor
Kevin .
What sort of reaction could be expected if we applied the high temperature
exhaust from an IC engine into a "reactor" containing biomass and at the same
time reheated the "reactor" using some of the volatile vapors so produced?
# My understanding of exhaust twemperatures is that they run something as
follows: (Anyone who knows better, please correct me:):
Unloaded Loaded
Diesel ~300F=150C ~ 752 F =400C Max
Spark. Ig: ~500F=260C ~752 F =400C Max
I conclude that even "hot engine exhaust would not be sufficient to operate
the C + CO2 --> 2Co reaction that requires temperatures in excess of 700C to
run.
perhaps we could also ionize the vapors produced within the reactor to above
5000 deg. which should yield a relatively low tar stream of gas .some of which
could fuel the IC engine.
# 5000 F would certainly run the above reaction. However, "Tars" areof the
general formula CxHyOn. Such temperatures would certainly "partially crack" the
tars, but probably would not "crack" them fully, to give a tar free gas. I am
guessing you would end up with some CO, and some other tars of a different
composition. However, they would likely be "heavier tars" that might be removed
more easily.
# The other issue is the energy required to "ionize" stuff at 5,000 degrees.
This does not compromise the laws of Thermodynamics.
# Exactly! Although many have tried, I don't know of any who have succeeded.
Best wishes,
Kevin
GF
In a message dated 11/28/2013 9:55:19 A.M. Eastern Standard Time,
[email protected] writes:
Dear Dan
Quoting [email protected]:
> Doug and all,
> Would some sort of a high temp molecular cracker be a good companion
> to create a quality gas from a fluidised bed? Possibly some steam and /
or
> preheated air .involved? Seems if you wrapped the exhaust back through
the
> hottest part of the flame in a reactor tube this can be accomplished.
> Sorry but I have been kinda outta the loop for a while.
# Start by appreciating the two Fundamental Rules of Thermodynamics
and Thermo Chemistry:
Fundamental Rule #1: You can't get something for nothing
Fundamental Rule #2: As a matter of fact, you can't even break even.
For example, the reaction
C + O2 --> CO2 (`1)
is strongly exothermic, and gives off about 14,000 BTU per pound of
carbon that is oxidized.
If there was insufficient O2, and the C was only burned to CO, as follows:
C + 1/2O2 --> CO (2)
then only abut 4,000 BTU would be released per pound of carbon.
If we wanted to reverse reaction #1, we would have to put back 14,000
BTU/Lb C
OR, in the case of a gasifier, where the reaction
CO2 + C --> 2 CO (3)
is desired, we would have to "put back" energy as follows:
14,000 + 0 --> 2x4,000 + "X"
14,000 --> 8,000 + "X"
and it is obvious that "X" is 6,000 BTU, in order to respect
Fundamental Rule #1
"Molecular Crackers" and "Catalysts" do indeed work, but only when the
fundamental need to add or remove energy from a reaction is respected.
As long as the "fundamental need for an energy balance" is respected,
then many things are possible.
Best wishes,
Kevin
>
> Dan Dimiduk
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