Charcoal Gas Temps

Over on my “Charcoal Gasifier for Generator” thread, the subject of exit temperatures has come up.

I am new to charcoal gasifiers, and have been running / experimenting with a simple fire design for a month or two.

Up to this point, my impression from reading the forums has been that the gas temperature will start to heat up when the charcoal level is reduced below some critical level.

However, my experience contradicts this to some degree.

In particular, as long as the amount of charcoal in the reactor is something reasonable, it doesn’t seem to make a lot of difference whether the reactor is 5/8 full or 3/4 full.

My temps start rising above what I consider the “critical” level after about 45 minutes no matter what the level.

So, I have two questions that I am wondering about:

(1) Is it true that gas exit temps are a function of time to a greater extent than charcoal level (assuming some minimum depth of charcoal) and

(2) Should I care about the gas exit temps, other than for the fact that I am using low temp. sump pump hose to carry the gas? In other words, if I used some higher temp. hose, could I run with higher gas temps? At what temp. would this start to be detrimental to the engine? Currently, I am cutting off when the gas exit temp. hits around 150 F (I am sure it is much cooler than this by the time it runs through the hoses and passes through the filter, but I don’t have an exact number).

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I have been following all the posts on charcoal gasification. I am studying anything I can get in front of me on charcoal gasification And like you it seems to me that, gas temp is the issue here. if a person was to use flexible exhaust pipe instead of sump hose or pvc pipe, theoretically you could run a much higher temp. Sump hose starts to degrade at about 130F, PVC at about 150F flexable metal exhaust pipe?
Then sump hose to the engine? Has anybody tried running with metal, and just let it go and see what happens? I realise the barrel will degrade significantly if the over all temp gets to high. I’ve crushed a couple barrels that way
What was used back in the 40s
Like I said I’m book smart on this not practical application.
I could study this for yrs. and you would still know more than me because your doing it.
Have you looked at the Sweedish gasification sites? Seems like I read that there are still quite a few People running wood and coal down the road over there.
Food for thought.


Hi Kyle,

Its all a question of balance… the descending charcoal should keep pace with the ascending gasstream to prevent the heating …

Also, the heat transfer by the reactor wall’s will also heat the output gas or at least give the impression.
Heat creeps up so easy

On my test run’s with the trike, i noticed once and since then always, that the airflow from driving, cool down the outside of my tank, so the gas and the tank stay’s cool untill reasonable empty… ( about 16 inches above the nozzle)

The size and uniformity of your charcoal also helps a lot in retaining heat.


Hi Jesse,

Better keep the heat in the charcoal :wink:
The colder the gas you get in your engine, the more hp …

second on the list: use the heat to preheat the charcoal to burn, as it does in the gilmore style gasifier’s, will save about 15% in consumption… just keep your gasifier filled and the outside cold :stuck_out_tongue:


Thanks Koen
I’ll remember that, for when I get set up on charcoal.
I have to finish this micro project and get it set up so I can use it for several different things that involve gas

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