I wanted to formulate a certain “to the topic” answer…
1: The tank you are mentioning can only hold about 3 bar pressure
2: the energy needed to compress the woodgas has to be added to the calculation but still positive in the balance compared to lpg
3: if you take the gas from a retort charcoaling unit as seen in one of the later posts, then its at its best in the energy/storage balance ( the gas would be the same as in the old days gazometers )
no dilution with nitrogen
4: a storage tank of 2 CBM at 3 Bar would contain 6 CBM woodgas
with a gas content of 15%H2 , 30% CO, 55% Nitrogen, it would be 1,5 Kwh per CBM * 6 CBM = 10 Kwh gas energy
with a gas content of 100% CO, that would be 3,5 Kwh per CBM
So, if you know your energy consumption, you can calculate your gain /loss for storing
Propane tanks are designed for no less than 250 psi working pressure. 3 bars would be 45 psi, and even ambient temperatures will produce 120 psi or more in a propane tank.
I read that the design standard was for tank failure at no less than close to 900 psi, proved in testing. Pretty amazing pressure vessels, really.
yup, my mistake, i used to calculate with butane… 177 PSI at 37,5ºC for propane to keep it liquid. ( 12 Bar )
only 2 Bar for Butane
Thanks for correcting me Garry
so, can have 12 time the volume in a PROPANE tank…
But the energy needed up to that level ( 177 Psi ) for woodgas, would cost 2 times energy content from the gas value itself. so total 3 times the cost for compressed to 177 Psi
( i tested up to 8 bar myself, energy cost was double value from initial energy content of the gas )
But all the rest agreed, from an energy point of view, compressing syngas is quite inefficient. Maybe useful for certain special applications, like the reports of using syngas / retort gas in an opened up oxy - propane torch.
I still do find the stationary gasometer system attractive though, the relatively small weight needed can be added after…
If l remember right its not the best idea to store hydrogen rich gas in a steel bottle. Being such a small molecule it difuses trugh the walls and allso makes them britle.
I thod a lot about storeing woodgas too. At least for cooking purposes and such, domestic and stationary. perhaps best and safest method is to store it in a bell gasomere but when l calculated capacity nessesery for my neads l preety much stoped thinking in that direction. Why make a 3m3 gasomere holding explosive and poisonous gas when you can make a butcket size gasifier that will suply just the same quantity of gas on demand? I mean it is simpler to open a valve and light a burner but starting a charcoal gasifier is not much harder nor slower.
On compressing woodgas on a vehicle. Now that is a different story and l think we shuld look closee to it. Steve wuld say every woodgaser situation is different and that is indeed the case. If l had acess to “cheap” petrol monster engine trucks like you Americans have, l wuld likely never concider this but the thing is, here, a 2 liter engine is concidered huge. A imported “woodgas suitible” vehicle wuld cost me a fortune on import tax and spare parts, registration tax… with my sallary wich is concidered a good one in this region thats about a year worth of sallary so thats not the way to go.
Anyway my idea is basicly wery simple and straingt forward. Step one is pressurise the gas just minimaly to overcome the drag of the system. This culd be done in many ways, perhaps best wuld be a belt driven centrifugal fan. The power demand shuld be low too sence we are only pushing the gas instead of actualy compressing it. Then, step two is to install a membrane vacuum automixer on, but inverted! Usualy gas comes at the engine at a vacuum and the automixer equalizes the pressure of air with restricting the air. This is the opposite. Air is drawn in the engine at atmospheric presure and the automixer restricts the pressurised gas to equalize. This wuld alow for greater cyl filling ratio and a much better throtle responce while not realy adding a ton of complexity.
The difference between coal gas and wood gas is that the compositions are different.
Coal gas contains a variety of calorific gases including hydrogen, carbon monoxide, methane and MANY different volatile hydrocarbons together with small quantities of non-calorific gases such as carbon dioxide and nitrogen.
Wood gas has a varying amount of nitrogen, but the main burnables are hydrogen, carbon monoxide and small amounts of methane, hydrogen yield varied by how you gasify whatever you have, etc…
Na, that would be to much precise…
Yes he must have towngas in mind, but for the sake of friendly conversation lets call our gas woodgas or chargas or syngas…
Wes, i think you might find many more interesting documentations in the DOW library, besides the extensive experimenting results written down on this site from people who did build gasifiers.
As “Coal” is a fossil fuel, i personally prefer to replace that with “organic fuel derived from air polution” aka wood and refined products there off… allow my smile to be big as i just cleaned the air from pollution ( todays rate was about 116 Tons of Co2 converted into energy… )
Wes, this site is full of actual builders information and your knowledge might be very helpful towards those who build.
Please take your time to follow up on peoples experiences , i am pretty sure there is a win win for learning from each other.
Kristijan,
I tend to agree with Mr Wayne: Most of us are already capable of overheating our gasifiers running vacuum mode only.
I know you live in hilly terrain and would like more power from time to time. Also I know there’s been talk about hard to make variable restrictions.
It suddenly occured to me…
We’ve both been running grateless gasifiers with huge bottom char reserves. Works ok, but with quite a lot of char slipping/flying into the cyclone. How about using some of it for power from time to time?
This is where your charcoal gasifier setup comes in handy. With your horisontal, heavy duty, bottom nozzle pipe buried deep in the wood gasifier dump area char pile, you could open a valve and let air in whenever higher gas production is needed. Kind of two different gasifiers in one.
Of course this is for momentarily use only. The wood gasifier on top would have to get the time needed to catch up making char.
What do you think? Remember this is just a spur of the moment idea
I agree with you on your suggestion to follow people up on their experiences, hence why I came to DOW, I wanted to give ideas and learn from people who’ve built these things, and I hope I help provide info the best I can before I get the book by Mr. Keith and eventually build one.
Wayne, yes. In a wood gasifier such a modification shuld be taken in to concideration. But not so much on a updtaft charcoal gasifier it has a “limitless” turndown ratio.
I remember reading about this. I allso seen to remember you saying such a supercharger operating with woodgas (to boost power) is not the best idea. Am l correct?
Koen, l agree… if we want to remain sciencetific we shuld categourise some. Perhaps most exact nomenclature wuld be to call all air injection gasification process products syngas. Woodgas, chargas, coal gas… then there remain pyrolisis gas, and distilation gas.
JO, no dubt, you are on to something here. I wll need to give my nightshift-drained brain a brake now, but l see whats the topic of tonights dreams
Ha! Ha! Careful KristijanL.
Very precise, descriptive terminology labeling once past just one-two words ALWAYS get made into capital letters need-to-know secret talk.
The 1940’s German gasifier systems became such. Had to know German scientific/technical terms to sort it out.
This is a human nature thing. Law - learn old Latin. Medicine - learn old Greek&Latin. Music - learn old Italian?
Automobile gas emissions I had to memorized and use first about a hundred two letter designations. Then a few hundreds three letter designation. Now . . . hundreds and hundreds of four and five letter designations!
Oh, for the old sailor/logger/farmer/trades days when in-use word-labels meant something. Do this Now. Don’t do this, Ever.
Woodgasifier - uses wood input. Charcoal gasifer -uses pre-made charcoal (including bamboo and char-pellets) input. Bio-mass gasifier - (many do not like it when I refer to these as shit-eaters, or Back-To-The-Future Doc Brown garbage-eating fantasy machines BTTFDBGEM)
'Course many of these old straight forwards direct term-labels were not usable in polite (ladies) presence.
S.U.
Ok so l chewed JOs idea some. I see one problem. Char in the cyclone dump area is rather cold. I think it wuld not light on its own once introduced with air. This culd be corrected with installing a “standby” nozzle in the dump, always alowing a tiny bit of air in just to acheave a tiny glow.
Or, why not add nozzles in a circle under and around the restriction?
This all triggered me to think, what do you guys think is the max rate a gasifier can slip char and still make good gas?
Wow, I get maybe one or two gallons every 100 miles with 10 miles between lightups. Only a cup or two every 100 miles at non-stop road speeds.
I belive as soon as air is introduced you should get a torch effect that will find its way back to the nozzle pretty fast.
If preheated air is used (piped from the upper nozzle manifold) the char should auto-ignite.
My driving around here is up or down hills on pretty rough roads with about 25 mile round trips. It has allways made about the same amount of char. I have about 25000 mile on it now.
I would think a simple cross flow heavy bronze or stainless nozzle a short distance below the restriction would do. (Out of the melting zone) The incandescent particles and gases would auto ignite anywhere in that zone.
I like this idea. I think it might work well with something like Jo’s double nozzle plane, suddenly increase the reaction area, and ensure burning of tars at the same time.
It would probably only work in that mode for a while, as Jo asks, the char slipping and overall gasifier reaction zone dimensions will limit performance, but to me it seems like it could work as a temporary larger gasifier.
Even after a good night’s sleep I still think so too. The most important thing is you can produce more gas without pulling through the restriction. Less vacuum - better cylinder filling- more power. I do agree that only temporary use will be important.
If no one beats me to it I think I will actually try it at some point. Before I went to sleep last night I realised my Rabbit gasifier is already prepared for “dual mode”. One of the auger port caps could be replaced with a nozzle arangement, fed with preheated air, piped from the light port.
Now I need another small vehicle
it has a “limitless” turndown ratio.