Hi, Tom!
24. of October 2016
Did you dislike the rectangular grate-frame, as it is still uncommented?
Sorry about jumping in?
Answer preferably where it is discussed! “TomC’s gasifier”.
Moved above post from another thread.
Fine point of etiquette, guys; please don’t post on other threads just to ask for a response. If you need to get in touch faster, use the PM system or email them directly. Thanks!
3 Likes
Hi, Tom!
24. October 2016
to mess. 461
Mess. 456 describes both use and intention:
If you do not have a door placed to draw out the grate directly horizontal,
the bending down of the front-end, when the front taps leave the rails,
makes removal for cleaning easier.
That is the whole purpose.
…
Now, if you intend to make a new “soft material” hearth, make the height
cover both the oxidation part and the reduction part as one piece.
Less welding, more adjustment possibilities?
Hi, Chris!
24. of October 2016
to mess 463
Sorry! Point taken. Trying to find the route.
Trying to understand.
- you are recommending a rectangular grate?
- if the grate is big enough to cover the reduction zone it doesn’t mater if it is round or rectangular. It will be to wide to fit through the ash clean out door.
3 Why do I need to remove the grate. I have run a solid mounted grate and never had it plug up. I have scraped the ash from between the bars on occasions. - Kind of getting ahead of me. I need to get a drawing going so you can see what I am thinking. The mild steel hearth will go from just above the nozzles and down to just below the restriction. It will be about 9 inches in diameter so the nozzles will be like a WK fire tube with holes drilled for the nozzles and machined tube inserts all that will end about 1/2 inche from the wall of the hearth. Below the restriction, the hearth will go to about 7 inches in diameter and that reduction bell you had me build will be installed with room for char between the 7" hearth and the bell. TomC
3 Likes
Hi, Tom!
24. of October 2016
The same applies to me.
-
If applicable, yes. Standing on 4 horizontal taps, it
moves well between the rails. -
If even the door diagonal measure is smaller (less) than
the reduction tube width, there is no possibility to inspect
the grate in “free air”. -
By “hooking off” the front corners’ (left and right ) carrying
taps by a small movement toward the door, this end will
swing downwards, (between the rails) enabling the
emptying of everyting from above. Also you may see the
upper surface of the grate.
The “back pair” (left and right) horizontal carrying taps at
the back-corners of the grate-frame can also be loosened
by turning the hanging grate in the horizontal (compass)
plane a bit. -
It sounds that you are abandoning the calculated nozzle-
hearth, having to do everything from the beginning…
Such a system needs a totally new cooling-metal build-up.
Send your old and new drawings, so the obvious will be
clear.
Hopefully Chris can edit all text paragraphs to the same font? something went wrong again…
Number 4 became no:1 and fonts went south…
Max. Right now I am planning on abandoning the build using “obtanium” Car wheel and brake drums in favor of properly dimensioned mild steel. The nozzle diameter will be kept at 9 inches using ( now ) 10 nozzles, nozzles to restriction 4 inch etc. The dimensions you have recommend in the past.
I will start a drawing for you and myself. I have been reading ALL of your recommendations to JO. I see he has made some very big improvements in the performance of his gasifier AFTER installing it in his truck because he was able to make changes, such as his restriction and the volume of the “reduction zone”. By the WK design you can change the distance from the nozzles to the restriction and the restriction, very easily. JO also has the grate inside the reduction zone so he can adjust that volume. Do you think that grate configuration is a good idea ? TomC
2 Likes
Thank you Chris!
24. of October 2016
to mess. 468
Hoping to learn the PM system…
Tom, makeing a hearth variable is not at all a problem. Manny ways to do it, preetymuch anything can be easyly adjusted.
Per instance, on my build l made nozzles threaded (l think JO has them too) this way l can put in longer, put more or less of them in and so on. The restriction plane is just put in from the top, loosely fiting in the firetube and then sealed with ash. Same goes for the grate.
Shuld l lets say go for a roadtrip around Europe and culdnt get chunks anywhere, but woodchips are available, l just empty the gasifier and flip the restriction plane around. Set the grate higher, screw out the nozzles to protrude more in the hearth and we are woodchips power. Atleast thats the theory 
3 Likes
Tom, my main problem was constipation and the grate plugging. Knowing what I know now I think that was was also due to small mushy fuel which created a lot of fines. A combination of raising the grate and bigger stiff fuel helped.
2 Likes
Hi, Tom!
24. 0f 2016
to mess 469
I sincerely hope, that you do not drop into the habit of
“Cutting-welding, cutting, welding, cutting–welding”, as too many seem to adopt!
Making all critical adjustments screwable with DIFFERENT METALS in contact!
Adjustable flange-joints can use flattened coppertubes, first formed to a ring.
If you want to restrict weight, keep nozzle-tips off the hearth-wall,
because that asks for “metal cooling”!
One tube for whole the process spares weight and welding.
Look at Arvid and Dustin! and others.
1 Like
Sorry but I don’t know what you are trying to say with this comment.
All of our exhaust manifold “nuts” use to be brass to prevent galling. Not sure if the parts stores handle them any more.
Are you suggesting I “make” my own gaskets out of copper. It is possible, but I have had good experience with different types of gasket material, Particularly a latex base that is good to something like 2000 deg. F.
Another one I will have to draw up what I have in mind and then get your opinion.
Yes it does minimize the welding, but where the full tube diameter is not necessary, weight can be saved.
Ok I’m off to find Arvids and Dustin’s post. Fairly familiar with Arvids but have to look up Dustin’s TomC
2 Likes
Hi, Tom!
25. of October 2016
to mess. 474
Writing gets bureaucratic, if one has to rephrase every sentence!
…
“I sincerely hope, that you do not drop into the habit of
Cutting-welding, cutting, welding, cutting–welding”, as too many seem to adopt!"
This is not affecting primary (new) building; it is a conclusion of what is seen many times: Folks are welding critical components in place, instead of doing it mechanically!"
Furthermore, blocking access to places needing adjustments and service… hard repairs.
…
“Making all critical adjustments screwable with DIFFERENT METALS in contact!”
This one handles with internal gasifier parts; Iron, SS, Acid-proof, cast iron… needs no comment.
…
“Adjustable flange-joints can use flattened coppertubes, first formed to a ring.”
Just another alternative for some hard places use…
…
"If you want to restrict weight, keep nozzle-tips off the hearth-wall, because that asks for “metal cooling”! "
This one should be obvious; lighter firetube, no cooling fins and multilayers…
You, as many others have seen how short nozzles heat up the walls… by return sucking.
…
“One tube for whole the process spares weight and welding.”
A thin tube does not bring overly much weight; especially as these volumes mostly are excellent opportunities to do free, ash insulation!
…
Mentioning building principals is not anything personal, it is just collected experiance by many people!
1 Like
Good morning Max; I think it would be much better if you wrote in “paragraphs” instead of “sentences”. Above you have five sentences all on different subjects and as you can see by my reply, you did not convey your thoughts on any of them to me.
A “paragraph” starts with a statement introducing the reader to the subject you are writing about. Then you state your case or write you sentence. Then, you write a summary or a conclusion you want the reader to understand.
I certainly don’t profess to be an English expert, but that was the only language that I was taught from grade 1 through college TomC
PS Working on a drawing which is probably a language we both can understand better.
5 Likes
Ok friends. The word is out that I am building a new gasifier. I wasn’t going to talk about it until I had it together and running or together and need help getting it running. But today I need help designing it. The dimensions are about the same as my old gasifier.
Fire tube diameter-- 10 inches
Nozzle tip diameter — 9.5 inches
Nozzle height above the restriction— 4.5 inches
Restriction diameter ---- 4.75 inches
Restriction to grate ---- 4.5 inches
Number of nozzles ----- 5
Diameter of nozzle orfice ----- 1/2 inches
With the same dimensions, I am going to 10 nozzles. Notes from 2 years ago said I was going to 1/4 inch. I must have thought doubling the nozzles would mean to half the diameter ( makes about as much sense as, "the harder you pull the trigger, the harder the gun goes off!) Now I think the area of the 10 nozzles should equal the area of the previous 5 nozzles. I am not sure of this so I spent a beautiful afternoon down in the clear with the computer going through 12 year old stuff I have in notes. In Kaupp 1984 page 84, or Tom Reed Handbook of Biomass Downdraft Gasifier Engine systems-- Imbert Nozzles & Hearth table.
The line that is dr/dh = 268 / 120 The numbers when converted to English come out very close to what I used. But when I go to 10 nozzles the line does not seem pertinent. This line was for 5 nozzles. The orfice diameter doesn’t seem correct ( if I did it correctly— converting back and forth between metrics is not my strong suit.)
I would appreciate some input from you Imbert guys especially. TomC
6 Likes
Hi Tom,
I am realy glad to see someone is building too!
I havent got much knowlidge on gasifiers yet, so l most likely wasnt the kind of help you aimed for, but lll try it anyway 
The main reason we need air nozzles in the first place is to achive turbolent enviroment in the oxi zone. This is important becouse we want every peace of wood to be in contact with oxigen to burn all tars. So with nozzles to big we dont get enough air speed to penetrate the central part of the hearth. With nozzles too small, we risk starving the gasifier of air so a compromiss must be found.
A lmportant thing is allso fuel type from the same reason.
I use 2.5"x2.5" blocks and have 7 nozzles with internal diameter of 1/3" with a nozzle circle or 7.5". Ofcorse, my engine is s lot smaller. What is your gas consumption rate?
7 Likes
Tom,
I’m sorry If I blew your rocking chair cover. I guess we’re even now
What Kristian said. We share the exact same internal dimensions. I’ve got only one thing to add.
If you look at those tables you’ll find any size gasifier has a 5-8 % total nozzle area to restriction area ratio. Closer to 8% in a small gasifier, closer to 5% in a big one. If I were you I would aim in the middle.
I’ll hurry push the reply button. I get the feeling Max is typing right now
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Thank you guys for your input. The percentage thing is interesting and I will have to play with it to see what it would mean.
( no worries about Max typing to me. I’m a lost cause to him I think) TomC
6 Likes
Very true what KristijanL has said about ALL of the wood particles needing air-in oxygen exposed.
Do realize that the penetrating planer across way, is only one way to achieve this.
The WK doing this with vertical distance tulip form instead.
The IISC/Mukunda and StephenA’s doing this also with a longer vertical oxidization pathway and multiple level of air jets.
Ha!. No. I am not MaxG. This is his sleep time.
Steve Unruh
8 Likes