[Stoves] Misuderstanding of TLUD stoves Re: Refuelable TLUD Coal Stove developed in Mongolia that is not a batch process.

Sun Mar 6 08:45:04 CST 2011

Dear Kevin

>From all that I have learned from Dr Tom and his books, Paul and Ron and my
own experiments, I think you are substantially correct on the analysis
below. 

I think the Chip energy furnace can be run with fuel going in and out the
other side, so to speak, in a charred or partially charred condition. The
same is true of a downdraft device if you pulled the char out the side. 

I can add that in a coal stove, nearly all conditions apply at some point
during the burn somewhere in the stove.

Tomorrow we will test a TLUD coal stove with a large refuelling episode.
That should put the fire cat among the lexicographical pigeons.

We are also running our second training session this month on converting a
bottom-lit updraft stove into an end lit crossdraft stove with added
combustion tube. The combustion tube is sort of an afterburner that
dramatically reduces PM. Maybe 80% in combination with the crossdraft fire.
It is extremely simple to change  stove and costs about $0.80. The
participants are all professional drives and tour guides who light fires
during the course of their work.

Regards
Crispin

-----Original Message-----
From: stoves-bounces at lists.bioenergylists.org
[mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of
kchisholm at ca.inter.net
Sent: 06 March 2011 17:46
To: Discussion of biomass cooking stoves; Paul S. Anderson
Cc: Discussion of biomass cooking stoves
Subject: Re: [Stoves] Misuderstanding of TLUD stoves Re: Refuelable TLUD
Coal Stove developed in Mongolia that is not a batch process.

Dear Paul and Ron

Quoting "Paul S. Anderson" <psanders at ilstu.edu>:

> see below
>
> Quoting Ron Larson <rongretlarson at comcast.net>:
>
>> Paul and ccs:
>>
>>   I had not realized that your Chip Furnace operated in the manner 
>> you describe below.  Am I correct then in assuming that the word 
>> pyrolyzer (which you didn't use) would be inapproproriate - and that 
>> char production is minimal?

# I would propose for your consideration the following definitions:
1: PYROLYSIS is destructive distillation, yielding a pyrolysis gas, and a
char. There are two basic methods for PYROLYSIS:
a: The RETORT method, where additional energy required for pyrolysis is
provided through the walls of the retort, and
b: additional required thermal energy is provided by partial combustion of
the pyrolysis gases and/or char through addition of air.

2: GASIFICATION is a process where a solid feedstock is substantially all
converted to a gas.

It would thus appear that a device that produces significant quantities of
char, whether by accident or intent,  would be a PYROLYZER and not a
GASIFIER.
>
> Char production is controlable by the operator.  With fast throughput, 
> we could extract chars with many volatiles and some torrified fuel.

It is my understanding that this would not be a controllable process.  
Have you actually been able to produce charcoal AND torrified wood at the
same time in teh same reactor, OR was the product a mixture of char plus
partially charred wood?

   With very slow throughput, it could output only
> ash/minimal char.  The control also allows for use of different fuel 
> in the same device (but not at the same time).  Chip Energy furnaces 
> make char if (and how) you want it.

# A FURNACE is NOT a "GASIFIER" or "PYROLYZER". A FURNACE is a device whose
intended purpose is the release of heat through combustion of a fuel.
>>
>>   But also that much of your other writing is on char-making stoves 
>> of a batch type and that you would then not use the term "gasifier"?
>
> "Gasification" to the majority of readers includes making gases via 
> pyrolysis and/or by char-gasification.

# A PYROLYSER produces a fuel gas PLUS a char product. A GASIFIER is
intended to convert all, or substantially all, of the feedstock into a fuel
gas for subsequent use elsewhere. If you gasify char, then it is a gasifier.
If you produce char, it is a pyrolyser.

> A gasifier can pyrolyze.

# True, but a GASIFIER does not have CHAR as a desirable end product.  
A device that has CHAR as a desirable end product is a PYROLYZER. It stops
the pyrolysis at the char stage, and does not continue on to gasify the
char.
>>
>>   I have not heard whether Nat Mulcahy demonstrated at the Ethos 
>> meeting that he could add extra fuel at the end of a run - and that 
>> TLUD was therefore Inappropriate for his design.
>
> Nat did not operate any of his stoves at ETHOS.  He did explain why he 
> does not consider his stoves to be TLUD technology.
>>
>>   I believe (perhaps like Crispin) that a BLDD could produce char - 
>> and could add extra fuel at the top - and hope that someone will 
>> report on that pair of desirable characteristics in a collating.

# Definitely. A "Stratified Downdraft Gasifier" can be operated in a manner
where biomass can be added continuously and char can be produced
continuously, and a fuel gas can be produced continuously.  
There is a requirement for continuous removal of char.
>
> Good luck.  I too await such a report, but that technology works 
> against the creation of char.

# If the desired objective is char production, then it is basically a
PYROLYSER. If the desired production is a fuel gas, then it is basically a
GASIFIER. If the desired production is HEAT, the it is a FURNACE.

  Meanwhile, I have a char-making device
> in the form of the Chip Energy Biomass Furnace and (as of this past
> month) the Chip Energy "Dragon" (shoots out fire or combustible gases 
> to the user-provided destination/application - US$15,000 with variable 
> configurations.)

# Does it burn gases to completion? What is the heat output rate? What
percentage of the energy in the input fuel shows up as heat, and what
percentage of the input fuel energy shows up in the char? Can the
"Combustible Gases" be piped elsewhere for use?

Best wishes,

Kevin
>
> --
> Paul S. Anderson, PhD
> Known to some as:  Dr. TLUD    Doc    Professor
> Phone (USA): 309-452-7072   SKYPE: paultlud   Email: psanders at ilstu.edu
>
>
>
>
>>
>> Ron
>>
>>
>>
>> Sent from my iPad
>>
>> On Mar 3, 2011, at 12:30 PM, "Paul S. Anderson" <psanders at ilstu.edu>
wrote:
>>
>>> Quoting Crispin Pemberton-Pigott <crispinpigott at gmail.com>:
>>>   snipped
>>>>
>>>> A TLUD is just a down draft built upside down. They can be 
>>>> refuelled continuously but if the desire is to get char out, that 
>>>> could be a problem.
>>>>
>>> This is a very common misunderstanding that was even promoted by Tom 
>>> Reed who initialy call it "inverted down draft" gasification.
>>>
>>> In a true downdraft gasifier, there is a hot zone that stays at the 
>>> bottom all the time, and the fuel moves downward to it, becomes char 
>>> and is later subjected to char gasification.  The air flow is also 
>>> downward.
>>>
>>> In a TLUD, the hot zone starts at the top, but then the hot 
>>> pyrolysis front migrates downward until reaching the bottom of the 
>>> fuel pile.  That is FUNDAMENTALLY DIFFERENT from the downdraft 
>>> gasifiers.
>>>
>>> Furthermore, after the pyrolysis front reaches the bottom, the air 
>>> flow still continues to be updraft.  Placing a significant amount of 
>>> fuel onto the top of the fuel bed can cause variations in the gases 
>>> created (initially much water vapor while the fuel is drying, then 
>>> the pyrolytic gases start later).
>>>
>>> Note:  In the case of the Chip Energy Biomass Furnace
>>> (www.chipenergy.com) which is a true updraft gasifier with 
>>> continuous operation (and the hot zone is at the bottom where the 
>>> air is entering), the new fuel enters in small amounts, avoiding the 
>>> problem mentioned in the above paragraph about water vapor.
>>>
>>> I hope this helps explain what is happening in the TLUDs
>>>
>>> Paul
>>>
>>>
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