[Gasification] Turnkey Tarfree

[Thomas Reed]

Dear Craig and All:

Craig has the principles right.  The Community Power Corporation 
(gocpc.com) has reduced it to practice big time.  T'aint easy.

TOM REED  BEF

Craig Meyer wrote:
> Thanks, Dr Reed.
>
>
> Q1:
> So is the moral that tar production is 100% inevitable, and that 
> therefore one must account for its reduction?
>
> Like in BEC's case, my understanding is that it's accounted for in two 
> ways.  First, by flowing over hot charcoal through the hot second half 
> of the co-current pyrolyzer, and then secondarily by reduction at high 
> temperature with oxygen.  It's the one-two punch that makes the BEC 
> process unique.
>
> 'Zat right?
>
>
> Q2:
> I'm flabbergasted that tar production is still a problem even when the 
> output gas is cooled.
>
> Like for instance, in the attached PDF that I came across, it takes 
> care to point out that even though a cross-current pyrolyzer puts out 
> relatively cool gas, there's still a load of tar in it.  But if it's 
> cooled by counter-flowing through fresh biomass, doesn't that stuff 
> condense first and thus stay in the reactor?
>
> I'm not accusing them of lying, but MAN I sure could use some further 
> explanation as to why this isn't a paradox.
>
> --Craig Meyer
> Technology and Development
> Overall Swell Guy
> Cassettes2CDs.com
> 4206 Stone Way N
> Seattle WA 98103
> (866) 669-6496 office
> (206) 669-6496 cell
>
>
> ----- Original Message ----
> From: Thomas Reed <tombreed at comcast.net>
> To: Craig Meyer <craig_r_meyer at yahoo.com>
> Cc: Jim Fournier <jim.fournier at gmail.com>
> Sent: Monday, August 20, 2007 6:29:06 AM
> Subject: Re: Ever heard of a gasifier that ___________?
>
> DEAR CRAIG:
>
> NICE TO MEET YOU.  SEE INTERLINEATIONS BELOW...
>
> Craig Meyer wrote:
>> Dear Dr Reed,
>>
>> I was introduced to your work by Jim, to whom I was introduced by a mutual acquaintance Andrew Hoppin, a sort of financing and team-building facilitator in New York City.  (Jim knows I'm writing you.)
>>
>> I'm sure you're busy, but I'd appreciate your response to the following.  Just use the enclosed paper and envelope to scribble off whatever reaction you feel like sharing, no muss no fuss.  NEVER TOO BUSY TO ADDRESS THE *REAL* PROBLEMS OF BIOMASS ENERGY. 
>>
>> I myself am just starting to get a conceptual grip on The Tar Problem, and how almost all innovation in gasification today has to do with addressing that problem.  The books your foundation sells will no doubt be helpful with my education.  I am both intimidated and impressed by your work with in-stream oxygen/tar reforming (the non-secret elements of which Jim has shared with me), and congratulate you for your bravery and dedication. 
>>  THANKS
>>
>> Nonetheless, I'd appreciate your reaction to the following proposed alternative gasifying scheme.  Given how many people have been working on gasification since mid-century, it was probably tried and dropped seventy years ago, but I'm writing you about it today because I know you'll be able to tell me for sure whether that's true.
>>
>> It's a cross-current gasifier for making syngas for an on-site electricity generator.  The Trick is that instead of being fed with biomass and air, the gasifier is instead fed with biomass and hot (800F? 1000F?) syngas that was counterflow-heat-exchanged with the generator's exhaust.   
>>   
> A FRIEND OF OURS (DANNY DAY) ONCE PYROLYSED A BARREL FULL OF BIOMASS 
> WITH THE HOT EXHAUST FROM A TRUCK AND GOT A 30 FOOT FLARE OF VERY 
> TARRY PYROLYSIS GAS. 
>
> 1)  THERE IS NOT ENOUGH OXYGEN IN WOOD TO CONVERT ALL THE CARBON TO 
> SYN-GAS AS IN
>
>              C H1.4 O0.6 (TYPICAL WOOD) + HEAT ==> 0.4 C + 0.6 CO + 0.7 H2
>
> THIS REACTION IS ENDOTHERMIC AND IS COMPLETE ONLY AT 900C (1620 F)
>
> 2) HEAT EXCHANGERS ARE BIG AND BULKY AND NOT VERY EFFICIENCT
>> The hope is that since the lower biomass is heated to slow-charring temperature (~600F) without actual ignition going on, maybe (and I do mean -maybe-, as I have no idea myself) that keeps most tar from forming/vaporizing.
>>
>>   
> BIOMASS SLOW PYROLYSIS YIELDS  TYPICALLY 1/3 CHARCOAL, 1/3 GAS AND 1/3 
> VOLATILES (TAR)
>> As the syngas pushes up through the biomass column into the upper portion that is still somewhat damp, it cools to 212F as the upper biomass dries.  (There's some threshold water content for the incoming biomass--I guesstimate around 33%--beyond which there isn't enough thermal energy to dry it and the whole scheme doesn't work.)  My second hope is that this cooling to 212F in the upper biomass portion helps "catch" the remaining tars as the syngas marches upwards toward its exit at the top.
>>
>> After that, I suppose some kind of drying is called for, and then a minority portion of the dry and cool syngas feeds the generator while the rest is recycled back to the gasifier via the fancy generator exhaust heat exchanger.
>>
>> And that's what I 'got.  
>>
>> I am by no means trying to convince you that this scheme will work, or that it is a good idea.  I'm -asking-.  I'd really appreciate whatever you have to say about it  and about actual
>>  reactors conceived on similar principles in the past.
>>
>>   
> CHEMICAL ENGINEERS DO A HEAT AND MASS BALANCE ON A PROCESS BEFORE THEY 
> GET TOO EXCITED.  LOTS OF QUALTITATIVE SCHEMES CAN SOUND ATTRACTIVE, 
> BUT REALITY DEMANDS REALITY...
>
> MAYBE YOU CAN ALTER THIS IN THE LIGHT OF THE ABOVE.  JIM AND I LEARNED 
> OF A PROCESS THIS WEEK THAT CONVERTS PRODUCER GAS TO DIESEL WITH GOOD 
> EFFICIENCY. 
>> Thanks!
>>
>>   
> MY PLEASURE,
>
> TOM REED     BEF   BEC
>> --Craig Meyer
>>
>>   Technology and Development
>>   Overall Swell Guy
>>   Cassettes2CDs.com
>>   4206 Stone Way N
>>   Seattle WA  98103
>>   (866) 669-6496 office
>>   (206) 669-6496 cell
>>
>> ----- Original Message ----
>> From: Jim Fournier <jim.fournier at gmail.com>
>> To: Thomas Reed <tombreed at comcast.net>
>> Cc: Craig Meyer <craig_r_meyer at yahoo.com>
>> Sent: Saturday, August 18, 2007 9:05:14 PM
>> Subject: intro
>>
>> Hi Tom,
>>
>> This is to introduce you to Craig Meyer, who is interested in  
>> gasification and was introduced to me by a friend of mine who is also  
>> interrested in BEC.  I have had a couple of back and forth emails  
>> with Craig responding to his questions and after i pointed him to the  
>> BEF and Woodgas sites he asked if he could send you a page of queries  
>> directly himself.
>>
>> please cc me as i always learn more myself.
>>
>> best,
>> -j
>>
>>
>>
>>
>>
>>   
>
> -- 
> ÐÏࡱá
>

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