Any new small charcoal retorts out there?

[Woodworks]

Sounds more and more like I need to get my design up and working. It will work and will be productive the unknown is lifespan

[SteveA]

High temperature Stainless steel 316 has been mentioned in the Village Idiots thread, which should withstand temps up to 850deg C (apparently).

 

I've just found a couple of higher temperature stainless steels mentioned here: Article: Maximum service temperatures in air for stainless steels

They list up to 1150deg C max temp.

 

Does anyone here know what the average stainless steel oil drum (205litre) would be made out of?... are the barrels stamped with the metal type?

 

cheers, steve

[flatyre]

I too am toying with making a retort, though mine won't be mobile as I would like to use the heat to dry logs, a key point in my design is having a removable inner chamber to cut down on down time while cooling, theory is if you have three 'canisters' you could have one in the retort, one loaded with new wood ready to go, and one cooling, it means you don't need to start a new fire every burn, just re-stoke the fire every time you change the canister. My theory is once the routine is in full swing I can load a new canister and stoke the fire, leaving the old canister to cool, empty and refill the previous canister, then head off to work in the morning, swing round by the yard on my way home (which I do most days anyway to unload/load up for the next day) stoke the fire, swop out canisters, empty and reload cooled canister, come back the next morning and start the cycle over again. Having a removable ash pan means you can empty it while the fire is still burning. You would need a front loader with forks or similar handler but it would be easy enough with a couple of toe lugs welded to the top of each canister and under the ash pan. All just theory.

[agg221]

High temperature Stainless steel 316 has been mentioned in the Village Idiots thread, which should withstand temps up to 850deg C (apparently).

 

I've just found a couple of higher temperature stainless steels mentioned here: Article: Maximum service temperatures in air for stainless steels

They list up to 1150deg C max temp.

 

Does anyone here know what the average stainless steel oil drum (205litre) would be made out of?... are the barrels stamped with the metal type?

 

cheers, steve

 

Stainless steel will typically be 304 unless it is stated otherwise. 316 has more nickel and some molybdenum which pushes up its wet corrosion (seawater) and creep resistance, but it has the same maximum recommended service temperature. See table in the same link.

 

There are two issues - one is corrosion (loss of section) and the other is deformation under thermal cycling, due to a combination of creep and non-uniform expansion. Loss of section does not appear to be an issue with the Exeter but deformation certainly has been. TVI's retort has just had a second adaptation to raise the retort chamber as it sagged where the legs rest on the chamber.

 

Given free choice, starting from sheet material I would probably go for a ferritic stainless as they are cheaper and should perform well enough. This is the sort of steel that diesel exhausts are made from. If I had the option of a pre-made vessel, such as a stainless drum, I would go for that instead though as the mass production method for making this would drop the costs far lower than I could fabricate it for. In an ideal world if I just wanted to avoid distortion I would go for bolted cast iron plates, which would last an extremely long time but the cost of casting moulds would be the limiting factor. This would be a lot heavier and probably not at all portable. I can't see any reason to go for the ultra-high temperature steels or nickel alloys - durable as they would be, the costs would be prohibitive.

 

Alec

[openspaceman]

Biochar is what is produced by activating the char!....

The 'bio' part of the word means poo, urine or generally (nitrogen).

 

Steve am I getting boringly predictable?

 

 

 

The surface area of char! is MASSIVE and for its size can lock in/ or carry a huge amount of bio.

 

Actually activating is a specific process to do with carbon and what you describe isn't it. What you describe is more preparing it for use in the soil.

 

Activation is when a sample of char, traditionally made from bone, is "attacked" by chemicals, e.g. chlorine or super heated steam, which hakes indentations in the cell walls and thus massively increases the surface area of the char, this gives more space for organic chemicals to be adsorbed by the char. It is measured by the mass of iodine the same can adsorb, Freshly made char has only a modest iodine number.

 

Many claims are being made for biochar and it almost certainly is not a cure all in all situations. Even our Malling research stations seemed to make the mistake of "rationing" its use to better soils when the indications are it has more effect in poorer soils likely to leach nutrient.

 

DEFRA still don't licence its use because of fears the smaller particles will wash into the surface waters and affect riparian life (in much the same way cement and builder's sand can).

 

My interest evolved from work on a specific type of cookstove aimed at cleaning the indoor atmosphere in those parts of the world where cooking is done inside over an open wood flame. A quirk of this type of stove (Reed-Larson aka TLUD) is that whilst producing a very clean flame it left a ~25% residue of char, burning this char increase the particulates released so being able to use it on the soil offered an alternative.

 

Obviously there is some negative affect on wood consumption as 50% of the fuel value stays in the char.

 

Now to the global picture: a huge amount of CO2 (6+ billion tonnes/annum) is being released into the atmosphere from fossil fuel combustion and whilst it is a small part of the 100+ billion tonnes cycled by plant growth and decay it is increasing. Intervention in the decay by making biochar is a way of sequestering carbon which would otherwise quickly enter the atmosphere but politically there seems no way of those producing excess carbon dioxide rewarding a distributed system of sequestering via biochar in this way. As I see it biochar would have all the advantages of a cash crop without the disadvantages of needing to export fertility with the crop IF there were a way of rewarding the activity by otherwise subsistence farmers.

[Woodworks]

 

Given free choice, starting from sheet material I would probably go for a ferritic stainless as they are cheaper and should perform well enough.

 

Alec

 

Any idea one sheet price of it in 1mm Alec?

 

I was thinking of a double skinned retort with the outer being steel and maybe a stainless liner with some insulation between the skins.

[Gary Prentice]

Many claims are being made for biochar and it almost certainly is not a cure all in all situations. Even our Malling research stations seemed to make the mistake of "rationing" its use to better soils when the indications are it has more effect in poorer soils likely to leach nutrient.

 

.

 

Sorry to derail and maybe the biochar issue deserves another thread.

 

A client asked if the thirty quid a bag biochar she's chucking around the garden is worth it (ornamental planting).

 

She's composted leaf litter, prunings, vegetable kitchen waste etc for twenty odd years and it's probably a clay soil. I think she's wasting her money because I think her soil should be relatively good and nutrient rich. i.e a natural(ish) soil. Thoughts?

[openspaceman]

 

A client asked if the thirty quid a bag biochar she's chucking around the garden is worth it (ornamental planting).

 

She's composted leaf litter, prunings, vegetable kitchen waste etc for twenty odd years and it's probably a clay soil. I think she's wasting her money because I think her soil should be relatively good and nutrient rich. i.e a natural(ish) soil. Thoughts?

 

I agree, in a clay soil biochar probably adds a bit of drainage but clay soils will have all the humus and minerals she needs for things other than grain crops.

 

There's a lot of hype marketing by the likes of carbon gold, who incidentally turned me down for a job.

[agg221]

I agree, in a clay soil biochar probably adds a bit of drainage but clay soils will have all the humus and minerals she needs for things other than grain crops.

 

There's a lot of hype marketing by the likes of carbon gold, who incidentally turned me down for a job.

 

I agree that a clay soil will not benefit greatly from it, certainly with regard to nutrient management. However, clay can be difficult to work with in a garden, being sticky and heavy in winter and then drying out like a rock in summer, so breaking up the structure will make it more pleasant to dig and it would help to stop a pan developing on the surface in summer so any flash summer storms soak in rather than running away. However, it is a lot easier and cheaper to get a good load of chippings in, stack them for a year and then spread them as a thick mulch on the surface to get essentially the same benefit, topping up as needed.

 

The only point where it would be useful is if the soil is in fact silt rather than clay. Fine silt can look superficially similar but will benefit a lot more.

 

Alec

[Gary Prentice]

I agree that a clay soil will not benefit greatly from it, certainly with regard to nutrient management. However, clay can be difficult to work with in a garden, being sticky and heavy in winter and then drying out like a rock in summer, so breaking up the structure will make it more pleasant to dig and it would help to stop a pan developing on the surface in summer so any flash summer storms soak in rather than running away. However, it is a lot easier and cheaper to get a good load of chippings in, stack them for a year and then spread them as a thick mulch on the surface to get essentially the same benefit, topping up as needed.

 

The only point where it would be useful is if the soil is in fact silt rather than clay. Fine silt can look superficially similar but will benefit a lot more.

 

Alec

 

The last time the soil dried here was probably 1976, being on the foothills of the pennines in Saddleworth.