Any new small charcoal retorts out there?

[Woodworks]

Thanks for the help but as far as I concerned burn time is not my problem at the moment. Main snag is too much heat. To protect the internals I now have various insulation materials on there way but the snag with this is temperatures will now be higher still.

 

Options as I see it are

 

Starve it of air but presume this will result in lots of gases going up the flue unburnt then have flaring out the top?

 

Build a much larger fire box so temperature are lower.

 

Butterfly valve on flue?

 

Insulate charge chamber so everything runs at high temps but steel survives. Looking at the Pressvess video it looks like this is the route they take.

Edited April 11, 2017 by Woodworks

[HertsWood]

Charcoal ad promised

[LewisB]

Black gold!

 

Do you have the bits on the very bottom getting tar on them? If so, it might help to slightly raise the back legs to help drain the "juices" out the front door.

[Woodworks]

Charcoal ad promised [ATTACH]218789[/ATTACH][ATTACH]218790[/ATTACH][ATTACH]218791[/ATTACH]

 

Looks great but using best ash logs to make charcoal?

 

What was the conversion rate? Looks amazingly high. Only ever got 50% with our retort.

[HertsWood]

Hi Woodworks,

The bulk bag of ash was the first I lifted with the 520.

I've got a lot of ash, alder and oak dry at the moment - I don't preselect what firewood be get, so the same is true for selecting bags for firewood.

 

It took 1.25x 1.2m3 bags to fill the Retort. And I've 3/4 filled a1m3 cooling bin with Ash and nearly brimmed the 2nd one with the second batch.

 

Probably getting 4:1 maybe 3.5:1

 

It's early days - only 3rd burn....

[Woodworks]

Hi Woodworks,

The bulk bag of ash was the first I lifted with the 520.

I've got a lot of ash, alder and oak dry at the moment - I don't preselect what firewood be get, so the same is true for selecting bags for firewood.

 

It took 1.25x 1.2m3 bags to fill the Retort. And I've 3/4 filled a1m3 cooling bin with Ash and nearly brimmed the 2nd one with the second batch.

 

Probably getting 4:1 maybe 3.5:1

 

It's early days - only 3rd burn....[ATTACH]218796[/ATTACH][ATTACH]218797[/ATTACH]

 

OK thanks

 

So a 50% conversion rate for you as well. In the picture it looks a lot better than that.

 

I asked about the ash logs as I am fiscally unsure about converting quality logs of any species to charcoal. Only using small branch wood in ours at present that I would rather not put in with the logs.

[richardwale]

Charcoal ad promised [ATTACH]218789[/ATTACH][ATTACH]218790[/ATTACH][ATTACH]218791[/ATTACH]

 

Looks great. Did it char all the wood completely?

[openspaceman]

Certainly if you measure efficiency in burn time then warm, oven-dry wood would take less time to process. However, if it doesn't reduce the total cycle time (inc. heat up and cool down) by enough to get a second cycle in a working day, assuming you want to stick with single shift working it won't increase productivity.

 

i GUESS MOST PEOPLE WILL MEASURE THE CONVERSION OF DRY INPUT INTO WEIGHT OF SALEABLE CHARCOAL AS THE MAIN METRIC. wE'LL HAVE TO DISAGREE ABOUT WHETHER BURN TIME IS SIGNIFICANT, ALSO i SAID THERE WERE OTHER REASONS. Sorry about the caps, I only just noticed my granddaughter had left caps lock on as I am a two finger typist and look at the keyboard

 

However, drying the wood to this level will take longer or require more energy input.

 

No reason why it should, it is a matter of size matching and the heat is available from the pyrolysis.

 

In an ideal world, where the off-gas was being productively extracted you it would pay to run with the driest wood possible, however in current systems where there is a surplus of gas, it could be argued to be more productive overall to burn the gas to dry the wood, ie to start with the wettest wood in the retort that you can still process in a day.

 

I disagree with this last too, simply because drying time is considerably longer than pyrolysis time, most will not realise this because the two processes are happening concurrently.

 

The measurements we took suggest that at standard retorting temperatures you don't get the water-gas shift reaction so you don't reduce yield by doing the above.

 

Water gas shift oxidises carbon monoxide and reduces steam to hydrogen I think, cannot see the benefit from this in charcoal production and as you say the ~500C temperatures we are seeing won't be hot enough. A bit of a red herring

 

 

 

 

 

Batch-sequential definitely has advantages as you are using the waste heat so don't suffer time penalties for drying. Continuous brings different issues - it is typically used at much higher temperatures for gasification, so is deliberately inducing water-gas shift to achieve H2 and CO output rather than charcoal.

 

I suspect you are mixing the watergas shift reaction with the water gas reaction, the first produces CO2 and hydrogen the latter CO and hydrogen, both need higher temperatures than in a retort and typically in a down draught gasifier the water gas reaction will pull down the temperature from the 1100C oxidation of carbon to carbon monoxide to the 800C where the reaction is too cool. As you will see this is the last thing you want if you are conserving carbon (charcoal) but it is useful in that it evolves a true syngas for further chemical process.

 

 

 

Universities are good at understanding fundamental concepts, ie working out why something happens. They are generally not so good at the commercial side. The consortium we are working with is purely industrial (apart from us - we are a commercial research and technology organisation) and everyone just wants to make it work, technically and financially. Everyone accepts that the markets will be niche, but niche commercial is still commercial.

 

I wish you the best of luck with it there was a good researcher on ours but one out of 5 including a bit of hegemony soon eats the budget and causes time to overrun ., I can dig out some of our work if you wish.

 

If you're interested, the public summary of the project is here:

 

http://gtr.rcuk.ac.uk/projects?ref=132408

 

Note, in the course of the project we have established that internal combustion is more cost-effective than a Stirling engine

 

 

I read the summary and see the objectives have already changed.

 

Stirling engines have never found a large market and the reason is probably fundamental in that conversion of heat to motive work in a reciprocating engine is proportional to the difference between the pressure developed to the pressure the working gas is at the cold side when it is rejected. A diesel engine with a 17:1 compression ratio has very little space left in the head at top dead centre, so pressure is high, the Stirling has all the space in the regenerator which compromises the pressure difference it can attain.

 

We had much the same reasoning and because of all the difficulties and oil contamination problems the reciprocating engine enthusiasts have with their Imbert style down draught gasifiers and the sensible heat loss of the producer gas as it is cleaned and cooled (reducing the cold gas efficiency), plus the contamination of the filter medium meant our internal combustion engine ran on the Brayton cycle. I was happy for this to produce a small amount of motive power on a low pressure cycle and use all the heat for process but as soon as you require ~20% electricity then size and pressure go up and capital costs escalate

 

The problem was the wish to maximise electricity production because that's what the government wants from renewable energy. My view is that whilst wood is an energy source it is a poor fuel and as 70% of our winter energy requirement is for heat all the time fossil fuels provide 70% of our electricity it is not worth trying to compete, FITS skew the argument slightly.

 

It's late so I cannot follow up all you said in an interesting post.

[openspaceman]

So a 50% conversion rate for you as well. In the picture it looks a lot better than that.

.

 

That's 50% volume, it will be lower weight, are you allowed to sell charcoal by volume now?

[openspaceman]

Charcoal ad promised [ATTACH]218789[/ATTACH][ATTACH]218790[/ATTACH][ATTACH]218791[/ATTACH]

 

Looks like a good yield and charcoal