[Gasification] Fluidised Bed Reactor

GFWHELL at aol.com GFWHELL at aol.com
Thu Nov 28 18:32:42 CST 2013


Phil,
 Why not make the exhaust manifold,  the structural part of the  pyrolysis  
section of our gasifier.
 A heavily loaded gasoline engine driving an alternator will produce  
enough waste heat to carbonize the biomass.
 
GF 
 
 
In a message dated 11/28/2013 6:32:44 P.M. Eastern Standard Time,  
phil at marshbros.ca writes:

 
Hi  Kevin: 
A  loaded diesel can easily run egt of 550-650C. Pyrometers are common on 
big  diesels but it does depend on where the measurement is taken.   
 
Phil  Marsh 
Marshbros. 
250  569-7858
 
 
From:  Gasification [mailto:gasification-bounces at lists.bioenergylists.org] 
On  Behalf Of Kevin
Sent: November-28-13 12:27 PM
To:  Discussion of biomass pyrolysis and gasification
Subject: Re:  [Gasification] Fluidised Bed Reactor

 
Dear GF

 
-----  Original Message ----- 
 
From: _GFWHELL at aol.com_ (mailto:GFWHELL at aol.com)   
 
To: _gasification at lists.bioenergylists.org_ 
(mailto:gasification at lists.bioenergylists.org)   
 
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, 
_kchisholm at ca.inter.net_ (mailto:kchisholm at ca.inter.net)   writes:

Dear  Dan

Quoting _Carefreeland at aol.com_ (mailto:Carefreeland at aol.com) :

>  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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