# wood chip boilers?



## mikeyny (Nov 4, 2011)

I have access to lots of hardwood chips from a chip truck. The tree guy will dump all I want. I k now there are commercially made chip boilers out there but they are big bucks. Anyone build their own? I have some materials and some fabrication skills, and Im thinking about experimenting with it. Naturally most of the chips will be green and wet. There is no practical way to dry chips in volume that i know of so burning as is would be part of the challenge.  Any thoughts?


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## Gasifier (Nov 4, 2011)

mikeyny said:
			
		

> I have access to lots of hardwood chips from a chip truck. The tree guy will dump all I want. I k now there are commercially made chip boilers out there but they are big bucks. Anyone build their own? I have some materials and some fabrication skills, and Im thinking about experimenting with it. Naturally most of the chips will be green and wet. There is no practical way to dry chips in volume that i know of so burning as is would be part of the challenge.  Any thoughts?



Yes. Stick with your Tarm you have. Save money for gasser down the road. I think you would be going to far and make things to much  of a pain in the ....... doing the chip thing. Nice things about cord wood are it is easy to handle, store, move, dry, etc. How do you like that Tarm? I have heard nothing but good about them.


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## Dune (Nov 4, 2011)

mikeyny said:
			
		

> I have access to lots of hardwood chips from a chip truck. The tree guy will dump all I want. I k now there are commercially made chip boilers out there but they are big bucks. Anyone build their own? I have some materials and some fabrication skills, and Im thinking about experimenting with it. Naturally most of the chips will be green and wet. There is no practical way to dry chips in volume that i know of so burning as is would be part of the challenge.  Any thoughts?



Chips are usualy burned green as you noted.
As a result, a lot more chips are used.
Efficency in fuel use generaly doesn't enter the equation until fuel cost becomes an issue.
Nevertheless, being able to dry the chips at all would reduce the resulting polution as well as amount of fuel used.
 I have long envisioned a system where the chips are fed into the burner through the exhaust stream, possibly drying at least some.
 Enough philosophy.

You will need a self clearing hopper and an auger or some other mechanism to deliver chips.
You will need to be able to regulate the volume of chips delivered, and since the moisture content IIRC will be about 50%, you will likely need to supply 
forced combustion air. Not sure about that though.

As an aside, since you want to go down this road anyway, there would be a lot of overlap between a chip boiler and a wood gas producer.

Using the flamable gas from a wood gas producer, one could power a water-cooled internal combustion gen-set.

The internal combustion engine would be your "boiler", using a heat exchanger the engine coolant could heat your home, charge your storage tank or whatever, and the electricity you generate, through net metering could power your home year round, even though you only run it during the heating season, if the gen-set were sized correctly.

Wood gas producers are well established technology at this point, with a hundred year history, and can be bought "off the shelf" or built by a handyman with some fab skills.

Sized correctly, you could even charge electric cars and be energy independent, all from free woodchips, without the work involved in cordwood.
There is lots of info on wood gasification on the web.


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## Gasifier (Nov 4, 2011)

It is interesting stuff, and I am not trying to dissuade you from this mikeyny. Just trying to understand it.

Would it be less expensive and less hassle to put in one of the less expensive wood gassification boilers you can buy? Right in the same place of your current boiler. I have also seen used gassification boilers for sale. That people do not want because the do not want the work of burning wood.

A few questions. Because I certainly do not know the answers to them.  :lol: 

Where do you store the chips? 
Would you need to store them inside a heated building so they do not freeze? 
What will you need to buy to handle the chips when it is time to move them around during the heating season? 
How much room would you need for a hopper? 
How big would the hopper have to be in order to fill it and get an 8 hour burn out of it? 
What would you use to get the chips into the boiler from the hopper? I know they have augers for pellets, corn, etc. Do they have them for chips? 
Would the chips plug a normal auger up? 
Will the free chips always be there for you?
Will it be worth it when it is done? I'm just trying to figure that out I guess.

I know it could be done.


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## Dune (Nov 4, 2011)

The main thing about chips is the cost. Cordwood is expensive whether you buy it or make it yourself.
There are plenty of existing chip burning systems, but they are large and expensive.
An auger for feeding would need to be powerful enough to not jamb.
I would want a hopper that held at least 24 hours worth of chips.
Some places chips have value, some place they don't.
It depends on the proximity to a biomass generating plant.
Chips can't be trucked very far.


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## FyreBug (Nov 4, 2011)

This outfit makes a great unit... http://www.leiprod.com/bb100.html

Makes a great chip burner. A bit complicated and costly but good grief! What a machine!  Burns wood chips, grains, even horse manure up to 40% humidity. 

We're working ourselves on a less expensive version.


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## flyingcow (Nov 4, 2011)

I haul green wood chips from time to time. I cannot put a load on my trailer and keep over night in the winter. They freeze in. My trailer will hold approx 35 tons. 48ft possum belly trailer. Just a thought.


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## 711mhw (Nov 5, 2011)

Pretty sure that AHS (Wood Gun people) offers one, at least it was when I was inquiring. I think that they even handle the chip delivery sys.


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## Duetech (Nov 5, 2011)

When I bought my EKO the efficiency rating was supposedly based on burning chips. Chips can be dried but that is another process and another expense. Kind of like a grain drier.


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## mikeyny (Nov 5, 2011)

I really like my tarm. I have had it for ten yrs and have it figured out. It took a few yrs to learn the best operation of it. I just ave this easy access to chips and thought it might be worth doing. I really like the idea of wood gas. I have one of the books from Tom Reed about building a gasifier. I have a collection of stuff in the garage to build one, just havent done it yet. I wonder how long a gen set would hold up running most of the time on wood gas. I know the gas must be filtered and clean of all tars and particulate. The Onans seem to be the most hardy gensets out there


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## Dune (Nov 5, 2011)

mikeyny said:
			
		

> I really like my tarm. I have had it for ten yrs and have it figured out. It took a few yrs to learn the best operation of it. I just ave this easy access to chips and thought it might be worth doing. I really like the idea of wood gas. I have one of the books from Tom Reed about building a gasifier. I have a collection of stuff in the garage to build one, just havent done it yet. I wonder how long a gen set would hold up running most of the time on wood gas. I know the gas must be filtered and clean of all tars and particulate. The Onans seem to be the most hardy gensets out there



To make the Co-Gen (combined heat and power) work best you really need a water cooled engine.


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## Duetech (Nov 5, 2011)

Dune: Does your water cooled engine share the storage water or does it wrm the storage water via transfer through a flat plate or other transfer system?

Mikeyny: Your Tarm would probably burn chips. It would probably take some extra handling to dry your chips and some extra power but with a solar array aquatic style heater and even a solar powered blower you could build a drier for your chips and probably store two or three hundred cubic yards of chips for the winter heating needs.


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## mr.fixit (Nov 5, 2011)

I don't know about Dunes ,but here's the start of my mini cogen.  http://www.youtube.com/watch?v=IkIuExMlfXs
Right now running on diesel and connected to my solar inverter.
The cooling system is about 200 ft. of pex pushed inside of my 500gal. boiler storage tank .What a challenge but it seems to work ok so It must not of kinked inside of tank.
Also working on an exhaust HX on the engine to capture that heat.
A automotive radiator is also in the works to run in series because when you need to run the generator and the boiler is also running the temp. on the engine starts to climb.
I should know enough to run the gen. first thing in the morning!
Sure is fun making hot water!


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## Dune (Nov 5, 2011)

Cave2k said:
			
		

> Dune: Does your water cooled engine share the storage water or does it wrm the storage water via transfer through a flat plate or other transfer system?
> 
> Mikeyny: Your Tarm would probably burn chips. It would probably take some extra handling to dry your chips and some extra power but with a solar array aquatic style heater and even a solar powered blower you could build a drier for your chips and probably store two or three hundred cubic yards of chips for the winter heating needs.



There is a big difference between engine anti-freeze and hydronic anti-freeze. 

You need a heat exchanger.


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## thecontrolguy (Nov 5, 2011)

flyingcow said:
			
		

> I haul green wood chips from time to time. I cannot put a load on my trailer and keep over night in the winter. They freeze in. My trailer will hold approx 35 tons. 48ft possum belly trailer. Just a thought.



Yup, at work we get deliveries this size one or more times daily.  There is a REAL problem having that much green, wet, bio-chips in a pile.  This is the perfect solution to a self-feeding compost pile.  If you have never experienced the heat that a pile like this can put out, it is awesome.  We have a poorly insulated, double-bay, delivery building where the trucks back up to the sub-subterranean bin and the walking-floor of the truck dumps the load.  When the truck leaves and the doors are closed, the interior of the space is often 30degC (air temp) and very high in CO2.  The dust in the chip load contributes to a class 2 explosive atmosphere, and the gasses  make it a regulated, enclosed space (think farmers grain bin).  The devil in the details for chip (or Hog, as we call it up here) is not the burning, heat exchanging, etc, it's the handling of the hog fuel.  Good luck and play safe!


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## Dune (Nov 5, 2011)

mr.fixit said:
			
		

> I don't know about Dunes ,but here's the start of my mini cogen.  http://www.youtube.com/watch?v=IkIuExMlfXs
> Right now running on diesel and connected to my solar inverter.
> The cooling system is about 200 ft. of pex pushed inside of my 500gal. boiler storage tank .What a challenge but it seems to work ok so It must not of kinked inside of tank.
> Also working on an exhaust HX on the engine to capture that heat.
> ...



That's awesome!
If you are going to use a car radiator with an electric fan, or some such thing to dump extra heat, can you place it in your basement?
I use a small modine unit as a heat dump/garage heater.


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## Gasifier (Nov 5, 2011)

That sounds like a lot of chips controlguy, putting out that much heat and gas! 

I thought it was funny in fyrebug's example of that nice looking chip burning unit that it said it would burn horse manure as well. I don't think my wife would go for that in the basement. Maybe a large hopper outside in the backyard? Honey? No?  :lol:


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## tom in maine (Nov 5, 2011)

I had built a wood chip boiler back around 1980. There was a ton of work done at the University of Maine on chip burners.
The advantage, of course, is that they carbureate well since there is a lot of wood surface to air.

The chips I bought were green paper chips and they were delivered to my basement. We filled about 1/4 of the basement with wet green chips. They
dried over time, being in the basement which was heated somewhat by the boiler.
And they grew mold very well as they dried.
I washed the basement down between chip orders.

As mentioned earlier, the efficiency sucked because of the moisture content of the chips.
All the efforts from UMO to develop chip drying schemes were energy intensive. The surface area that makes them burn so well also
helps them grow mold.

I thought it would be great fun for my then small sons to play in the giant chip pile in the basement.
One cried the whole time and the other one got hyperactive from the mold that I did not realize was growing at the time.

I changed the boiler over to stickwood and never looked back.


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## Briquetmaker (Nov 5, 2011)

mikeyny said:
			
		

> I have access to lots of hardwood chips from a chip truck. The tree guy will dump all I want. I k now there are commercially made chip boilers out there but they are big bucks. Anyone build their own? I have some materials and some fabrication skills, and Im thinking about experimenting with it. Naturally most of the chips will be green and wet. There is no practical way to dry chips in volume that i know of so burning as is would be part of the challenge.  Any thoughts?



I talked to these guys when I first started looking into boilers http://biowoodrenewables.com/Endress_USF-S.html They are very nice and very expensive. If you are going to build one maybe you can get a few ideas from the literature


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## tom in maine (Nov 5, 2011)

Tree service chips can be stringy but are certainly cheap or free.

The guys at UMO used to build a bin that used fan and/or solar heat to help dry the chips.
The fan energy that was used was significant.

Most installations, both residential and commercial/industrial just burn them at whatever moisture content
they come in at.


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## mikeyny (Nov 9, 2011)

Burning the chips in the tarm kind of works, but still not very efficient or user friendly. I have a barrel full next to the boiler, I put a good layer of chips on a news paper over the grates, then my kindlin and fire wood and then another heaping layer of chips on top. They do get a chance to dry before they burn, but once i get into the real heating season the chips would take of precious room in the boiler, displacing good burning wood. Not really worth the trouble.


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