After reading about and building a T-LUD stove last summer I was very impressed with it's capability. Thank you Tom!!!! The T-LUD
seemed to be a great system for cooking but had a couple of things which might have been improved for making the stove useful beyond cooking. I
had filed a discovery with the USPO on my additions to the T-LUD but have decided to publicly disclose my additions (making them public
domain). I wish I had more time to commercialize them because I think these variations could substantialy increase the practicality of
increasing the scale of the system. I will continue to work on the system and others related to it but my product development business is keeping my too busy in other paying fields.
***note that I used a pressurized system for reasons of my own, and don't reccomend it to those unfamiliar with pressure vessels. Both of these additions would work fine on a suction based system or an open system like the "normal" T-LUD
***please make any comments on this system to the list, I will not be able to answer off list questions due to time constraints but do remember to cut and paste any required quotes, don't clog the list by reposting this whole text unnessarily, it is useful to us all to keep the lists short and to the point.
My addition are in two directions:
The first was to create air paths through the fuel bed this opens up the possiblity of an "infinite" fuel stack. The air passages are of
1/2 inch diameter so changing air resistance is not a significant factor in the declining height of the fuel stack. The effect of this is is
that the primary air adjustment does not need to adjusted once satisfactory pyrolisis is taking place. The air passages were formed
by wrapping a layer of newsprint around a steel rod and placing the steel rod in the center of the gassifier running from the primary air induction zone to the top of the fuel bed. Once the gassifier is filled with fuel the steel rod is withdrawn and the gassifier is lit (a little tricky with the ceramic balls in place) as a normal T-LUD. This lead
to a good system, but was improved (before the introduction of the balls) by setting the gassifier on an angle of 45% this provided a gravity assist to help collapse the char bed on the air induction tube, keeping the raw air from mixing with the pyrolisis gas. In the angled system the best results were obtained when the air tube was offset towards the lower end of the tube, maintaining a large char bed on the collapsing air induction tube. The effect of this to provides a consistant air flow to the moving pyrolisis zone on the top of the fuel
bed regardless of stack height. This I have effectively done on a 48" by 6" dia fuel stack without having to make any air adustments to the
system once the airflow requirements were adjusted. This system I belive could be used with small engines though the gass was always a
little tarry. I also tried multipul tubes but found that in most fuels they didn't make much differance with a 6" diameter bed that was inclined......
The second addition began as an attempt to not have to incline the gassifier, it became a bit more important than that as it developed.
In an attempt to make the char bed consistantly collapse over the air induction tube I tried adding ceramic chips to the top of the fuel bed, these rode the char bed and effectivly agitated it as the char below them was consumed. Ash seemed to be carried through the bed and deposited on top of the balls. The addition of the balls also seemed
to make a large differance in the gass quality, much less tar. I belive that it was effectively increasing the dwell time the gass spent in contact with radiantly heating material, and also decreased the char beds radiation heat loss to the surrounding vessel (sides and top). This may be very useful to other T-LUD experimenters due to the ease
with which it can be attempted. I started by using "terra cotta" hards, then mixed up a batch of fireclay-sand- perlite and made random
sized balls from 1"dia to 2" dia. I found the balls to be the most effective when layered on the top of the fuel about 3" deep, that was
the deepest that I tried. I did consider adding dolimite to the balls for it's catalyitic effect (tar cracking) but never had time. I also
would have liked to try a deeper "ball bed" to find an optimum. I also found that in this configuration a little cleaner gas was obtained by using three air induction tubes spaced equaly around the vessel.
For experimenters in North America who are looking to work with the T-LUD system I found that 4 foot lengths of very nice used SS lined insulated chimey pipe are cheaply obtainable from stove suppliers that are replacing stoves with new models, or going to pellet systems. I got 8 feet for free. I used a pressurized system, taking the top and
bottom off SS soft drink syrup containers and tig welding them to the stove pipe. The nice thing about the tops of these containers is that
they have two flare fitting gas ports, and a largeish oval door. The doors gasket was rubber so I replaced it with a copper tube gasket that
I fabricated. The same effect could be obtained by welding a SS pressure cooker to the top, but I would not recomend it as Stainless
Steel alloys sometimes are subject to embrittlement after welding. I ran air into the vessel through one of the ports, down a copper tube through the fire bed to the bottom of the vessel ( primitive air preheat) and had a piece of expanded metal (diamond mesh) on the bottorm that created an air plemum for the steel rods to drop through. I
will attach an illustration.
I have also shown how a variation on this system can be made continuous feed without the use of augers, either as a char burning or char producing setup with and without steam injection and found the steam injection to be very benifical in producing a high btu gas and would be happy to discuss this with people willing to complete non-disclosure requirements.
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