[Gasification] Fluidised Bed Reactor

[Phil Marsh]

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 

To: 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 writes:

Dear Dan

Quoting 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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