[Gasification] Getting both heat and char .....
Paul Anderson
psanders at ilstu.edu
Thu Jan 5 16:26:09 CST 2017
Doug, (and a thank-you to Art for his comments also)
Your archive update
http://www.fluidynenz.250x.com/Feb2015/Shasta2update.html was very
informative. Although larger and with operational differences, there
are strong similarities with the Chip Energy Biomass Furnace that Paul
Wever and I designed and made some years ago. Info is at
chipenergy.com That is not a TLUD, but is a true up-draft gasifier with
a few innovations that I have written about in 2007 as AVUD (Another
Variation Up-Draft) gasifier.
> http://www.drtlud.com/wp-content/uploads/2012/08/BP53-Anderson-14.pdf
I agree that what Rolf is seeking is not a TLUD.
You wrote:
> May be the ash from the carbon dust will settle in the tunnel
> depending on combustion gas velocity. Usually, a correctly sized flue
> stack is required to assist with removing the exhaust gas, and this is
> where ash dust can become an emission.
I have not experienced carbon dust or ash from carbon dust or ash dust
with the AVUD design.
Again, thank you for your strong support for gasification of biomass.
Paul
Doc / Dr TLUD / Prof. Paul S. Anderson, PhD
Email: psanders at ilstu.edu
Skype: paultlud Phone: +1-309-452-7072
Website: www.drtlud.com
On 1/5/2017 12:27 AM, Doug wrote:
>
> Hi Paul,Rolf and Colleagues,
>
> This is to clarify Paul's questions. I hope the separations do not
> confuse too much.
>
>
> >Pyrolytic gas can be quite wet so precise temperatures are risky to
> quote.
>> Yes. There is no scrubbing or drying or other preparation of the
>> pyrolytic gas. In the TLUD world, the gases are usually created in
>> the 500 C to 650 C range. And the raw biomass fuel might enter with
>> as much as 15% to 20 % Moisture Content (MC).
>>
>> If the MC of the raw fuel was lower (such as 5% MC), would that help
>> raise the temperature?
>
> The short answer is yes, we don't need steam to displace gas volume.
>
>>
>> Hypothetical question: Part A. if the pyrolytic gases were cooled
>> to below 100 C, water could be removed by condensation, and we would
>> have lots of wood vinegar. However, there would also be massive
>> amounts of tars and "gunk" being deposited also. However, the
>> final, non-condensed gases just might have the desired temperature
>> when combusted. Those gases would be H2, CO,
>> methane-and-related-gases, and what else?
> Cooling the gas is a waste of the heat that it contains. Any condensed
> tars, hydrocarbons, or vinegars may have applications, but also add to
> the technical difficulties for their collection. Their removal, other
> than moisture best removed by drying the wood, reduces the calorific
> energy of the pyrolysis gas. Difficult to calculate, but also adding
> to the gas heating value will be carbon particles. Normally we would
> seek to minimize these by using a cyclone, but ceramics need reducing
> atmospheres, or read that as carbon rich heated atmospheres, so carbon
> dust is great.
>>
>> Part B. Alternatively, after the removal of the wood vinegar,
>> perhaps the remaining gases plus the reheated tars, etc. could be
>> reheated to become a dry, quality gas for higher burning
>> temperatures. All of this would be with losses of thermal energy
>> during condensation and then the need to add thermal energy. Could
>> this have benefits that could justify the expense?
> I think the previous answer covered this, but I see no benefit at all
> to this suggestion. At a later date after there is a system working,
> you will then have opportunity to extract condensates. Our experience
> tells us that as toxic black liquor, the less you have the healthier
> the working site. No exaggerating, it's a health and safety hazard.
>>>
>>> What I can tell you from experience, is that it always burns hotter
>>> than clean producer gas, upwards of 1,050C,
>>>
>> If that is the maximum, will this be sufficient for Rolf and his
>> friend to use? There is no way to turn 1000 C into 1300 C, correct?
> Not well explained, sorry. Clean tar free gas will not burn over
> 1,050C, but if the system design produces pyrolysis gas which has all
> it's hydrocarbons, then the temperatures will be upwards and over
> 1,050C, a basic tar test for cleaner specification gas,
>
>>
>> But your next words I do not understand.
>>>
>>> 13-1500C is a rough rule of thumb for gas exiting the combustion
>>> chamber.
>>>
> If you combust pyolysis gas full of hydrocarbons, then the flame
> temperature will be 1,300-1,500C. One of the most difficult areas of
> combustion is that thermo-couples start going crazy over 1,300C.
> Expensive ceramic ones damage too easily, so once the TC melts, you
> know the higher temperatures are present, possible over 1,500C.
>
>
> >I am not understanding what that means. The combustion chamber is
> the "burner" of the pyrolytic gases?
>
> The short answer is yes if we were just creating heat. Ceramics like
> Rolf is seeking to fire, are done in a tunnel kiln, and the tunnel
> becomes the combustion chamber. The geometry is important to create
> the combustion phenomena, but to design this we first need a tunnel
> kiln to use.
>
> >>It has a very high radiation factor useful for refractory
> application, but the price for this is that you will get a high ash
> content in the kiln and flue dust emissions.
>
> >Something in the above sentence is not clear to me. The "kiln" is
> part of the gasifier or is it where the materials are being heated?
> And the pyrolytic gases of TLUDs do not >have ash in them. And I am
> not understanding the source of any flue dust emissions.
>
> The gasifier is close coupled to the kiln, and the burner is mounted
> in this case, on the end of the tunnel kiln which forms it's own
> combustion chamber containing the ceramics. The spent gas has to exit
> the tunnel at some point, above the condensation temperature. May be
> the ash from the carbon dust will settle in the tunnel depending on
> combustion gas velocity. Usually, a correctly sized flue stack is
> required to assist with removing the exhaust gas, and this is where
> ash dust can become an emission. It would be good to put aside TLUD
> understanding, as they work on a totally different principle not
> relevant to this project need.
>>
>> Are your comments somehow referring to the FULL gasification
>> processes in downdraft gasifiers (pyrolysis AND char-gasification are
>> both occuring)?
> No, Downdraft gasifiers more often than not make pyrolysis gas and
> need char extraction to work. Full gasification as you say, need
> minimum bed disturbance and between 1-4% of the fuel drops out as
> char. Rolf only has a downdraft engine gasifier for his first trials,
> and we should get plenty of pyrolysis gas out of that, at least for
> the first tests to fire the ceramics. Maybe we will have to extract
> char as well, but all that is still a long way off at this point.
>>>
>>> The actual combustion is complex, but achievable in a non regulated
>>> situation, emissions being the issue, both dust and toxic gas
>>> CO,CH4, and Dioxins. Combustion of these gases have been our focus
>>> for some 6-7 years, and current work at CalForest in California, is
>>> to use this gas to dry the incoming fuel to the charmaker.
>>>
>> The above sentences seem to indicate that your explanation is about
>> FULL gasification and not about only the pyrolysis process with
>> resultant charcoal creation.
> We take raw producer gas from the Shasta gasifier, meaning hot
> cycloned hydrocarbon free downdraft gas for the boiler green house
> application. This has high carbon dust content which burns to ash.
> This is a problem for the boiler, but just needs more cleaning cycles
> than anticipated.
>
> The Charmaker is an updraft system and burns to waste the very dirty
> pyrolysis gas. The gas flare vertically from high stacks making them
> safer, as we have no space to work with them on the ground. The
> radiant heat cooks you from about 3-4ft, so the chances are, unless
> you have stood by an oil rig flare, many researchers just haven't
> acquired this type of experience from pyrolysis gas flares.
>
> You might like to look again at the Fluidyne Archive last update
> showing the charmaker and gas flares in action. The bigger flares at
> higher output are not shown mainly due to us too busy keeping up with
> the input fuel flow. Earlier updates show the Cyclomix burners and
> combustion chamber hooked to a heat exchanger, so there is plenty of
> info to brush up on as we developed these larger gas making system
> components. When operational, we collect data from those points
> important to both the gasifier and process, including continuous gas
> analysis, which cannot be used for pyrolysis gas. (to dirty)
> http://www.fluidynenz.250x.com/
>
> Doug Williams.
>
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