Mobile Retorts

[Woodworks]

So is it that refractory brick is too heavy or would it flex and crack it if moved? Never used it only watched it being used to line a 150 kWh burner. How about the heat proof sheets that are used in wood burners. It is certainly light enough. As for barrels limiting how much can be done in a burn I can only comment from our experience with our homemade retort. I have the fortune to have a tractor with forks and the retort holds 2 barrels. It would be easy to do 4 burns in a day with small material being converted. We simply pull the barrels out hot with the tractor forks and leave them to cool with earth blocking the gas holes. Conversion rate is around 50%-60% by volume that's 1000- 1200 litres of charcoal a day before sieving. Would have thought a bit cunning design to change barrels without a tractor would be possible.

 

Only throwing ideas out there

[MartinN]

Sounds like you have a neat system going already. Any chance of photos?

 

Refractory is not really designed for moving and would crack. Weight is an issue as well. The insulation boards and blankets are a much better bet. Some have carcinogenic properties from dust due to small particle size.

 

How long is your burn from for 2 drums to cooling?

[Woodworks]

Sounds like you have a neat system going already. Any chance of photos?

 

Refractory is not really designed for moving and would crack. Weight is an issue as well. The insulation boards and blankets are a much better bet. Some have carcinogenic properties from dust due to small particle size.

 

How long is your burn from for 2 drums to cooling?

 

 

Hi Martin.

I did post some pictures some time back but I will pop them in here as well. It's not a classy job but it took a morning with bits and bobs that were laying around the farm but the principle works very well. The wood is put into the barrels with the clamp type lids. There are no complicated pipes to direct the gases into the flames just holes drilled into the side of the barrel that direct the gasses straight into the flames. The external vessel is an old water tank that was waiting to go to the scrap yard. After the first few burns it was showing signs of distress so a sacrificial lining was added to the inside (old corrugated sheets) This seems to help with insulation as well. The biggest snag was the frame that supports the barrels buckling with the combination of heat and weight. An extra leg or two has help this. Hope these pictures and short video explain it.

 

[ame]

[/ame]

[MartinN]

Thanks for posting pictures. Looks good. Definitely a top setup for the two drums.

 

How long is one cycle would you say, till end of gassing?

[Woodworks]

Thanks for posting pictures. Looks good. Definitely a top setup for the two drums.

 

How long is one cycle would you say, till end of gassing?

 

Around 2 hours. This is with small diameter wood from our branch logger so suspect it would take longer with larger diameter material.

[LewisB]

How do you stop air getting into the drum once it has been gassed? Do you have a method for blocking the holes or do you have to do something else?

[Woodworks]

I remove them with the tractor forks and lay them hole side down on the ground. Once out I used to earth up around the edge but this appears to be unnecessary.

[timbernut]

Good stuff woodworks is similar to what I am trying to do except I'm using an old rolling/off skip and redundant 500lt lpg tanks. Do the holes face directly down onto the box? Does the initial thicker smoke not smother the fire before it reaches higher temp?

[Woodworks]

Yes I aim the holes straight down or slightly in to avoid the flames being directed at the sides of the retort and the heat being wasted. It's slightly hit and miss though when loading with a barrel on the forks. I should add I have no idea on the longevity of this set up as it's only used occasionally.

[the village idiot]

I will try to find some holes

 

Welding thin 316 is not difficult. I am not the world's best welder, but I am pretty good at it - I have run a whole load of seams in 1mm 316, both in butt and corner lap configuration. Some of the butt welds were unsupported freehand across about a foot and I managed not to burn holes and where I did, to fill them in again. Finding a nuclear coded welder is harder, but you don't need one for this. If you just want a fabricator I can find you one who is very reasonable if you want me to drop you a number (they're near Newmarket but if this is to be trailable it shouldn't be a problem).

 

Dished ends are good, but the fundamental problem here is that the heating in a horizontal barrel design is non-uniform. This creates differential stresses, it has to go somewhere and so it warps it. Extra strength does not help you enough as the material is too thin to resist the stresses.

 

Graham, I would be very happy to come over and see your set-up. I can even try to explain what I am on about in English!

 

Alec

 

Thanks Alec, that would be great. I'll send you a PM