Burning wood chips in a log burning stove?

[ChissayLuke]

Hi Zeroluke,

Thank you for this. i am just investigating at the moment - trying to find the best way of getting something for nothing!

My only concern about leaving the brush until the Autumn is that of leaving an untidy mess, in big piles, really. Although if this is the way to go, I will be happy to do so!

Just a thought, though - I would want to use this through the winter- if it has all dried out in the summer, will it not become wet again and hard to burn once the winter rains come?

Thanks again,

Luke.

[John Thomas]

Hi, I have ready and free access to brushwood and small branch wood.

I am wondering about chipping and drying this to burn on my log burning stove.

Would this work?

Some advice has been that it would choke the fire, some that it would help it stay 'in' overnight by burning slowly, and some that (given airflow) it would burn really quickly!

Anyone here have any thoughts.

And any advice on a petrol chipper to produce this? I'd like heavy-duty domestic to junior professional. Budget £1-2.5K.

Thank you for your kind thoughts and input.

With all due respects I think your wasting your money

Wood chippings is about only good for tinder

Very small pieces lots of air flow and burns way to fast for a fuel

[Chunkymunky]

You could try making biochar. You'd have to look up the processes but basically its very similar to making charcoal with tweeks. Resulting product is charcoal around outside of the drum and a very good fertiliser on the inside. If you put that on plants in a dry area it absorbs water and slow releases. Also a good seller. It's the new big eco thingy coming

[Woodworks]

Quite pricey but if you are keen on burning brash it might be worth looking at a branch logger. http://arbtalk.co.uk/forum/firewood-forum/20652-tr70-branch-logger-apf.html

[ChissayLuke]

All posts are really helpful, thank you!

I am drying out some woodchips to try out, and depending on results will either buy a chipper or not.

Am I right that (a) if the woodchips burn really quickly that they will produce masses of heat in a very short time (which may have purpose in itself) and (b) if I smother an existing fire in woodchips it may smolder gently over a period of time then burn. (subject to the wood gas being able to escape?

If I can achieve either (or ideally both!) of these possibilities, then woodchips will be well worth using. I am just trying to get something for nothing in order to save money.

My only concern in all of this, is why is no-one else doing it? Or maybe they have just tried, and given up!

Thank you again,

Luke.

[Paul Smith]

I think Z Germans are trailing a burner that takes green chip. It has a double feed system to dry chip before its burnt and a vent for steam.

[openspaceman]

My only concern in all of this, is why is no-one else doing it? Or maybe they have just tried, and given up!

Thank you again,

Luke.

 

Here is a video a friend in Canada made, I have posted the link before. Since this time he has run it on woodchip but there can be an issue with bridging. The chips do need to be dry <30%mc wwb I expect.

 

[ame=http://www.youtube.com/watch?v=yOlu7DdX1gI]Pellet Stove App.wmv - YouTube[/ame]

 

You will see it is basically a cross draught gasifier firing into a standard wood stove with side opening door, so as not to have to cut the stove the wedge is made to seal against the stove and the stove door.

 

The main issue with chip is their higher restriction to gas flow, so there can be difficulty in getting enough primary air through a grate and maintaining the correct secondary air ratio.

 

With wet chip the primary combustion is reduced, less offgas is produced and it is diluted by steam hence secondary combustion never gets going, the firebox never gets hot enough to feedback radiant heat for drying so the fire smoulders and gives off blue-yellow smoke. With my boiler if you cannot raise the flue gas temperature above 140C it will always smoke.

[openspaceman]

I think Z Germans are trailing a burner that takes green chip. It has a double feed system to dry chip before its burnt and a vent for steam.

 

Kob offered this as an add on for their boilers, none I dealt with used one and we could burn chip to 40%wwb with no visible smoke but a steam plume in high RH weather.

 

The dryer would not have been very efficient as it used hot water from the boiler to blow warm air, vented to atmosphere, to dry chip in a delivery auger.

 

Theoretically biomass should have enough energy to evaporate water and burn the dry matter up to 80% mc wwb but of course there would be no spare heat to use, unless you use a bit of cunning.

[Woodworks]

All posts are really helpful, thank you!

I am drying out some woodchips to try out, and depending on results will either buy a chipper or not.

Am I right that (a) if the woodchips burn really quickly that they will produce masses of heat in a very short time (which may have purpose in itself) and (b) if I smother an existing fire in woodchips it may smolder gently over a period of time then burn. (subject to the wood gas being able to escape?

If I can achieve either (or ideally both!) of these possibilities, then woodchips will be well worth using. I am just trying to get something for nothing in order to save money.

My only concern in all of this, is why is no-one else doing it? Or maybe they have just tried, and given up!

Thank you again,

Luke.

 

I am not an expert on this but I have burnt dust chip (not from a chipper but chainsaw chips) and logs on various stoves over the years so here is my take on what will happen when burning dry chip.

 

I think you would need to burn it fast and hot in regular batches. If you try to slow burn what will happen is the wood gas will be driven off and either escape up the chimney un-combusted which is a waste of good energy or it will occasionally flair up almost like a small explosion then slumber for a few moments then explode again this is most unpleasant and often pushes smoke out into the room. I have a workshop stove designed to burn dust, chip and solid wood. When burning chip and larger pieces that my branch logger makes I have to run it flat out until it gets past this gassing stage or else it starts making mini explosions. Once past this initial stage of combustion it is easy to then shut down but with only small material it is not long before you need to refuel or there will not be enough heat to commence the next burn. Your suggestion of mixing the chip with solid wood might work better but again I think you will need to keep a good flame to burn off the gas. I have a friend who is trying ways to burn chip who I will ask to see what his take on it is.

[ChissayLuke]

Thank you all, especially Woodworks. I look forward to hearing what your friend has to say.

Very best,

Luke.