Heating with Woodchips

[Arob]

No. most european boilers run at over 85% efficiency even with fresh chip.

All your doing is usingthe exhaust gasses to heat the boiler rather than the direct flame. Effectively your gassifying the chip and using the heat and combusting gasses to heat your boiler.

 

 

 

Certain boilers have feed issues... and some dont. its down the design.

 

And after nearly 30 years of feeding a log boiler, I'm sick of it.

 

 

Ed, have you any good links for these systems?

Like Buzz, I'd have thought that damp chip would require a high base heat to combust it, and that in evaporating excess moisture that energy would be lost reducing efficiency and base heat accordingly - imagine there's a heat recovery condensing system involved, to get higher efficiencies. Would be interesting to learn more.

[Mr Ed]

All you need to burn chip with a high moisture content is a ceramic refractory lined combustion chamber. This ensures that the combustion temperature remains very high. If your combustion chamber temperature is high (700+ degrees), and the chip is introduced down a sloping grate, the rising heat dries the chip out before it combusts. Dont forget that all that rising superheated steam and vapour will both combust and transfer heat into your boiler.

 

Of course, the best thing is to have dry chip, but I want a system that will be highly tolerant of moisture content.

 

If you look at the picture below, youll see the lined combustion chamber and the 3 pass boiler design. The flame never reaches the boiler, its the high temp. combustion gasses that go through.

Edited January 8, 2009 by Mr Ed

[Arob]

Thanks Ed, that's impressive engineering.

Presumably then you'll have an optimum level of throughput - you'll need to a minimum throughput of energy for the system to function - so will this mean that it is great in the winter but not useful for parts of the year when you still might want some background heat?

[Mr Ed]

Most of the modern chip boilers can cycle down to 25% output quite easily.

[BARNSLEY BOB]

what happens when electricity goes off....????

seldom happens at the moment, but when ww3 breaks out and the eastern europeans turn the tap off,we will be back to essential services only.

most systems will / should work by convection alone. ie heat rises..

these systems have augers in//out..

[skyhuck]

what happens when electricity goes off....????

seldom happens at the moment, but when ww3 breaks out and the eastern europeans turn the tap off,we will be back to essential services only.

most systems will / should work by convection alone. ie heat rises..

these systems have augers in//out..

 

My boiler needs leccy, I have a small generator.

[BARNSLEY BOB]

found this.

centralboiler.com

[Mr Ed]

Central boiler is just a crappy yank single pass log boiler. All central heating systems need electricity, as you need to move the heat around.

[Log-ologist]

As a seasoned tree-man I cannot see the reasoning behind Ed's choice of wet chip unless he wishes to bring home a few sackfuls of residues each night. Nobody here comes home and slings wet wood on their fire. ( maybe they do). I would think that he, like most of us would rather have a less demanding machine that can be fed the premium fuel rather than a premium machine that must be fed a premuim fuel.

 

a costing that may be of interest follows.

 

http://www.actionrenewables.org/uploads_documents/LgeDomesticWoodBoiler.pdf

[Arran Woodfuels]

a costing that may be of interest follows.

 

Note that the figures shown in this costing are from 2006, and in my opinion, are really out of date.

 

 

The Wood Boiler was installed and

commissioned in September 2006.