Basic Gasifier Build

Moderator: Mike Everman

Post Reply
PyroJoe
Posts: 1743
Joined: Wed Aug 29, 2007 5:44 pm
Antipspambot question: 125
Location: Texas

Basic Gasifier Build

Post by PyroJoe » Tue Sep 01, 2009 9:25 pm

Here is the preliminary illustration of a gasifier that is currently under construction. More to come.
Attachments
g1.JPG
Last edited by PyroJoe on Wed Sep 02, 2009 1:23 pm, edited 1 time in total.

PyroJoe
Posts: 1743
Joined: Wed Aug 29, 2007 5:44 pm
Antipspambot question: 125
Location: Texas

Re: Basic Gasifier Build

Post by PyroJoe » Tue Sep 01, 2009 9:43 pm

Wood chips are rare in this region, but brush is abundant, so one criteria is to use bundles of sticks as fuel stock.

The main fire tube was extended upward to allow bundles of sticks to be fed directly, without the possibility of jamming a upper hopper. Unfortunately, this results in constantly reloading bundles, but not a big problem.

After the tube is full, a very heavy plunger forces the stick bundles downward onto a grate below the fire region.
Attachments
brush.JPG
brush.JPG (10.95 KiB) Viewed 1647762 times
loaded.JPG
Last edited by PyroJoe on Wed Sep 02, 2009 4:45 pm, edited 1 time in total.

PyroJoe
Posts: 1743
Joined: Wed Aug 29, 2007 5:44 pm
Antipspambot question: 125
Location: Texas

Re: Basic Gasifier Build

Post by PyroJoe » Tue Sep 01, 2009 10:02 pm

Here is how I think it will operate. Fresh air entering the right side and woodgas exiting the upper left.
Attachments
process.JPG

PyroJoe
Posts: 1743
Joined: Wed Aug 29, 2007 5:44 pm
Antipspambot question: 125
Location: Texas

Re: Basic Gasifier Build

Post by PyroJoe » Wed Sep 02, 2009 2:16 pm

The outflow above is shown at a short height. If were to use it as a "stand alone" gasifier, would make the outflow much higher to utilize the chimney effect.

Decided to include a draft engine to show more ideas of how the chimney effect can be used to aid in gasifier/engine preheat and startup.

During preheat a plate/cap is placed over the engine inlet. This directs the hot gas flow up the exhaust pipe.

It may be possible to light the top of the exhaust pipe and check the gasifier output, watching the size and speed of the flame.

After the exhaust pipe achieves reasonably high heat and good flow is established, the inlet cap can be removed.

There should be enough upward draft in the exhaust pipe to continue pulling the gasifier gas up the engine exhaust pipe even with the intake cap removed.

At this point its time for engine ignition, and the task of adjusting variables to achieve sustained operation.


Anyhow, thats the overall idea. Will be posting on the gasifier build from here forward.
Attachments
combined.JPG

PyroJoe
Posts: 1743
Joined: Wed Aug 29, 2007 5:44 pm
Antipspambot question: 125
Location: Texas

Re: Basic Gasifier Build

Post by PyroJoe » Wed Sep 09, 2009 11:28 pm

The housing is pretty much ready to go. It is made from two seperate propane tanks welded together. One tank was in rough shape, had two dents about the size of a fist. Both were more than a inch deep.

Several sessions with a 13 lb. hammer finally worked those dents out. Alot of fun swinging a 13 pound hammer inside a 12" diameter tank. ha
Attachments
gs 002.jpg

vturbine
Posts: 357
Joined: Wed Jul 08, 2009 9:41 pm
Antipspambot question: 125
Location: Vermont

Re: Basic Gasifier Build

Post by vturbine » Tue Sep 15, 2009 1:25 am

Hi Joe, just saw this -- didn't realize it was in this section.

A couple suggestions, the chimney effect works if the outlet (pulsejet) is above the heat source. Well, looks like the draft pipe does do that -- and cooling along the pipe is minimal (for connecting pipes). It is possible in fact to get a negative directional draft by cooling the exiting gas in a pipe. This fact can be used. Since cooling the gas is an advantage, you might consider insulating upward connecting pipe flows, and using large surface area uninsulated metal "pipe" for downflows. It doesn't have to be pipe actually for this -- could be a metal container.

A good insulating mix is furnace cement mixed with a lot of perlite, available from garden centers and masonry supplies -- also Agway sometimes. I like your ash insulation!

Second you will probably need a grate shaker, and your cleanout for ashes and brands should be large enough to handle what falls there.

Glad to see you working on this!
No problem is too small or trivial if we can really do something about it.

Richard Feynman

PyroJoe
Posts: 1743
Joined: Wed Aug 29, 2007 5:44 pm
Antipspambot question: 125
Location: Texas

Re: Basic Gasifier Build

Post by PyroJoe » Tue Sep 15, 2009 6:07 pm

I figured it would be best to move it here and not muddy up better threads.
Many devils lurking in the details ready to sink their teeth into my posterior. ha

One noteable design change from the above will be to move the gasifier output pipe to the exterior of the housing to allow easy changes in the pipe diameter/size. This will also allow the woodgas to cool some. May put some cooling fins on that section to cool the woodgas and raise its density before it reaches the intake of the engine.

Could install a inline cooler to bring the density up to a more useful level in the future, but will make do for now.

If the draft pipe of the engine is the 2.3" dia. it may "pipe organ" after the exhaust is ignitied. Some adjustment of the cap over the engine intake can lean out the mixture allowing it to pipe organ down 75% of the draft pipe. This creates considerable heat in the draft pipe and spent gas, helping the updraft mode. Not to mention it is good fun. :)

The two middle bars in the grate will be able to pivot and help shed the ash build up. They will only pass through one side of the housing.
Where they exit the housing, there will be a little box located external to hold ash that covers/seals the pass through area.

Usually wood sticks that are 0.5" to 1" dia. will ash-out pretty well, but I haven't used them in a oxygen deprived environment, so not sure what to expect.

Have a cylinder of stainless steel for the lower flame tube. Decided to test a piece of mild steel first to see what the erosion will be. If it is not much, will just make a replaceable 14 gauge section there.The grate bars are also a sacrificial material and can be quickly replaced as needed, although I think they are closer to iron than steel, and are reasonably thick (0.5").

I spy a tea kettle. ha
Attachments
gs2.JPG

Rossco
Posts: 589
Joined: Fri Nov 28, 2003 12:16 pm
Antipspambot question: 0
Location: Australia, Brisbane
Contact:

Re: Basic Gasifier Build

Post by Rossco » Wed Sep 16, 2009 12:31 am

Hey Pyro,

Good to see you putting it to steel, mine seems a long way off yet.
I'm collecting some good info although it is slow going to collect, compare and refine it in usefull order.
Ill put some of the more interesting things up here for some background and ideas.

Yours reminded me of this one.
http://www.bioenergylists.org/stovesdoc ... urnace.pdf
Some interesting stuff in there about fire cutting/reducing raw material.

Rossco
Big, fast, broke, fix it, bigger, better, faster...
[url=callto://aussierossco]Image[/url]

vturbine
Posts: 357
Joined: Wed Jul 08, 2009 9:41 pm
Antipspambot question: 125
Location: Vermont

Re: Basic Gasifier Build

Post by vturbine » Wed Sep 16, 2009 12:44 am

Just a few more thoughts Joe.
Generally the brands and charcoal that fall through to the bottom are helpful in creating a better gas quality. Ideally they'd be a incandescent bed. The best place for the hottest element is the last in the process. Additional moisture will be converted there into more fuel through the water gas reaction, and also heavier tars will be cracked -- or that is the hoped for result.

In a vehicle gas producer, there is constant agitation of the grate causing the ash and small coals to drop through. In this stationary application, we may need to do a lot of hand shaking! If coals and ash don't drop through fast enough, gas quantity and quality may be a problem.

Cooling is helpful, but also may cause creosote condensation in the cooler section. The charcoal bed mentioned above should help to reduce creosote levels and increase simpler fuel gasses.

Just things to think about during design and construction -- not necessarily problems.
No problem is too small or trivial if we can really do something about it.

Richard Feynman

PyroJoe
Posts: 1743
Joined: Wed Aug 29, 2007 5:44 pm
Antipspambot question: 125
Location: Texas

Re: Basic Gasifier Build

Post by PyroJoe » Wed Sep 16, 2009 2:58 pm

Hi Rossco, feel free to post your build here if you like.

Not sure how this one will do. Down draft fire is something new. Most stick fueled furnaces built in the past('97-'00) were sidedraft/updraft, and open. Became reasonably proficient with them, could melt 18 cubic inches of aluminum in about 7 minutes from a cold start. Had a small 12V inflator blower for air.

One time was melting aluminum and copper to make a bright brass. The mild steel crucible became hot enough that the steel started eroding into the melt. The 3/16" steel wall eroded through and ended up with a interesting bronze like medallion at the bottom of the furnace. Stuck to a magnet about like steel.

Even stainless crucibles were only good for a few aluminum runs before burn through. Few people realize the energy found in typical small wood sticks.

Of course this was forced high air flow. I figure a draft system will use fuel at a much reduced rate, maybe 25% of a blower driven system. If so, will be going through about 8-10 gallons of sticks in about 30 minutes. Recharging about every 10 minutes or so.

Hopefully the lower chamber will work like a reverberatory furnace and help crack the gas further.

The part that concerns the most is not having direct access & view to the fire area during operation.

PyroJoe
Posts: 1743
Joined: Wed Aug 29, 2007 5:44 pm
Antipspambot question: 125
Location: Texas

Re: Basic Gasifier Build

Post by PyroJoe » Sat Sep 26, 2009 11:23 pm

Found a place that sells 2" pipe nipples and caps. Cut and welded the pipe and cap on the bottom. Welded some legs on. Filled with water for first leak testing. All is good. No illusions that it will be difficult to clean the lower chamber between runs, but this way a 100% lower chamber seal should be easy to maintain.
Attachments
gs2.JPG
gs2.JPG (13.32 KiB) Viewed 1647435 times

Viv
Posts: 2158
Joined: Sat Oct 04, 2003 2:35 pm
Antipspambot question: 125
Location: Normandy, France, Wales, Europe
Contact:

Re: Basic Gasifier Build

Post by Viv » Fri Oct 02, 2009 11:40 am

I was reading this article on Oxide fuel cells and thinking to myself that maybe they could be run from the out put of wood gasifier synth gas? btw how are you getting on with this project? I find it pretty interesting by the by ;-)

http://www.technologyreview.com/energy/23559/?nlid=2400

Viv
"Sometimes the lies you tell are less frightening than the loneliness you might feel if you stopped telling them" Brock Clarke

Viv's blog

Monsieur le commentaire

PyroJoe
Posts: 1743
Joined: Wed Aug 29, 2007 5:44 pm
Antipspambot question: 125
Location: Texas

Re: Basic Gasifier Build

Post by PyroJoe » Fri Oct 02, 2009 2:53 pm

Thanks Viv,
Progress is slow with the rain showers falling mostly on the weekends. Purchased a thin walled 3"
stove pipe/flame tube to do some preliminary testing. Should be good for at least a few test runs
(before better material is used). Welded some alignment tabs for the upper lid.
Figured a lid would be a good way to support/align the upper flame tube. Will be cutting a hole in the lid for the upper flame tube pass through.

Cutting the lower plate this weekend and welding tabs to the inner housing to lay the plate onto. Also cutting a hole in the plate for the lower flame tube pass through. Will rivet or hose clamp lower tabs on flame tube. With any luck I may be able to start installing the grates this weekend and finish the exhaust and start gasifier trials on the weekend of the 10th. Any delays will most likely push it out to the 17th.

3" I.D.looks small for the flame tube, although the gekgasifier site mentions with proper fuel, that 2.5" can be made to work. Inclined to think they are a like PJs in the smaller they are the more struggle to make them work.
Some rough calcs for a 3" Flame Tube are giving approx. dimensions for the intake and exhaust pipes.

Approx. Inside Diameters:
3" Flame Tube
.78" Intake Pipe
1.2" Exhaust Pipe

Hope these will be ballparkish.
Some consideration of adaptive design has taken careful thought. If built carefully, should be able to dis-assemble and re-assemble in a reasonable time.

http://www.gekgasifier.com/forums/showt ... 40#post740
"we've been debating for some time how small we can go in gas flow rates before we can't reasonably keep up the temps needed for good tar conversion. clearly smaller is more difficult in woodgas, as the smaller restrictions needed for good tar cracking start to prevent reasonable fuel flow. if you have perfect not sticky chunk fuel, you can go down to about 2.5" restriction. the wwII imbert chart goes down to 2.3", suggesting that was the end they saw as tolerable. many of us have personally found that 3" is about the min limit. thus this is what we deliver the gek with, as most are trying to run smallish engines.but how low can a 3" restriction go. well, we're closing in on a real answer with bear's summer and fall of tests. bear has now completed three fully instrumented parallel tests of the gek running on walnut shells, softwood chips and pellets, all using the standard 3" gek inverted V bell. each datalogged run is a few hour endeavor over the full range of pull rates, with temps, pressures, gas flow rates, and tar production logged in parallel. then a week of fussing with the resulting raw data to make it visual.we know that 2m3/hr gas is needed for each 1hp/hr. so reading through the tests we should be able to see where the floor falls out from underneath us and gas flow is no longer high enough to create the needed internal conditions.
what is the tentative answer?
well, the raw data is now up for all three runs now, but the tar vials are still in process for the last two tests as of friday, sept 25, 09. the tar/soot soluble separation takes a few days, as does the pictures and mapping the hue density. thus only the walnut shell run has the run conditions mapped to tar produciton. the woodchip and pellet run pix will be coming out over the next few days. you can watch the progress at the links below even without all the tar data here, there are some very interesting things to see happening between the different fuels. there will likely be some answers here regarding long-standing debates. watch here as more particulars emerge . . . "
Attachments
gs4.JPG

PyroJoe
Posts: 1743
Joined: Wed Aug 29, 2007 5:44 pm
Antipspambot question: 125
Location: Texas

Re: Basic Gasifier Build

Post by PyroJoe » Fri Oct 02, 2009 3:28 pm

Here is the basic plan for assembly:

1.-drop the lower plate on the internal tabs.
2.-insert the bottom of flame tube into the lower plate until it rests on the flame tube tabs.
3.-insert the intake pipe through the housing wall and then through the side of the flame tube.
4.- add ash, careful to keep the tube centered
5.- install the lid over the flame tube onto the housing.

disassembly (after has cooled completely):

1.-remove intake pipe
2.-remove lid
3.-turn upside down, shake vigorously. :D
Attachments
assemble.JPG
assemble.JPG (9.97 KiB) Viewed 1647359 times

Viv
Posts: 2158
Joined: Sat Oct 04, 2003 2:35 pm
Antipspambot question: 125
Location: Normandy, France, Wales, Europe
Contact:

Re: Basic Gasifier Build

Post by Viv » Fri Oct 02, 2009 3:46 pm

Hi Mate

you know ever since I first looked at your drawing for this gasifier I have had the feeling it should have a nice big pipe leading back from the inlet of the PJ to connect to the gas outlet chamber so the pressure pulses from the engines inlet can propagate back in to the gasifier and shake up the grate a bit, then a simple reed valve added before the air throttle valve.

Just one of those ideas :-)

Viv
"Sometimes the lies you tell are less frightening than the loneliness you might feel if you stopped telling them" Brock Clarke

Viv's blog

Monsieur le commentaire

Post Reply