[Stoves] Fuel Management - Bamboo Sawdust

Tue Mar 14 13:44:41 CDT 2017

Dear Tony

I really like the coiled tube. This is on the right track in that you can blow the ash out of the bottom pretty much continuously.

In place of the motor pushing the fuel, in Malawi that have a guy with a stick poking it into a hole.

How you apply the flame is a separate matter – heat transfer being the object. It would be pretty easy to make a version with a sunken pot and a chimney at the back.

Note that they are using the fan as an impeller (pun) of the sawdust so the sawdust has to pass through the fan. It means the clearance on the outside of the impeller has to be pretty large. It is easy enough to sift the fuel before use.

Schools tend to have a lot of kids. They might be employed as sawdust pushers. Don’t overlook that prospect.

I don’t know how you would clean the pipe.

The brick people in Surabaya we located – thanks for the reminder. They are pretty pricey because of the shipping, but I saw something pretty cool in Lombok. They cut the bricks to cut the thickness in half. Then the place them on the floor and case cement over them to make a mostly brick face with a cement backing.  That is what the tobacco barns are using now. It is really effective.

You could make a 6-brick or 8-brick combustion chamber two bricks high and run it at a massive face temperature – certainly you want it to be glowing. That way the sawdust hits it and burns immediately.

I don’t know how efficient you have to be if the fuel is free or nearly so. But for cooking power it will be great.

You are likely to have a lot of fly ash so watch where it vents – away from the food. From observations, the schools tend to have 4 fires: three large and one half the size. You might be able to make a single central fire and heat two sunken pots at low cost.

Re the briquettes – I think the ‘jobs’ angle is loading the solution with an agenda. Don’t worry about that, worry about something t hat will burn the fuel as is. Spend the briquette money on something else.

Regards
Crispin in the snow

Crispin - many thanks for the new suggestion.

I have found source of firebricks and fire cement in Surabaya. PT. BENTENG API TECHNIC - they seem to be a very large facility. Shipping costs to Bali more than the product!

Small centrifugal blowers seem to be used all over the place here by sate vendors cooking with charcoal.
I have not quite envisaged where the cook will fit in this type of design, I assume the blower and sawdust feed would come in from the side  or middle of something like a rocket stove burn chamber, with a small fire inside to keep things burning??  with the exhaust coming out at the top to the cook.

It is well worth investigating this approach for this application or our other pet project a forge..... maybe able to do it without charcoal...

Your 2 new key words (Sawdust combustor) unleashed the power of googles search engine.

This interesting looking device from India looks like it gasifies the sawdust in the burner tube and then uses the gas to maintain the in tube gasification process without using any bricks:
http://mgiri.org/wp-content/uploads/2014/05/Sawdust_Combuster.pdf

 What would be your vote??
Try to burn the sawdust outside the flow tube in a burn chamber?
or gasify the sawdust inside the tube as in this india example and burn the gases?

In the meantime I don't want to give up totally on fuel management (pelletizing) as it is a solution that can create micro enterprises in the area particularly if rice husks are put in the picture. Though these days the pigs seem to be very happy consuming most of that.
 Hopefully I get some ideas on that front from the stove community.

Great Ideas thanks for the feedback

TonyV

Tony Vovers
+1 281 7381000 (VOIP)
+62 (813) 3888 9062 (HP)

On Wed, Mar 15, 2017 at 1:09 AM, Crispin Pemberton-Pigott <crispinpigott at outlook.com<mailto:crispinpigott at outlook.com>> wrote:
Dear Tony

One of the good uses of sawdust when you have electricity is a simple fan and sawdust combustor.

If you start a fire and spray air containing sawdust into it, you can get a really hot clean fire. It will probably be best to do it against a ceramic wall, like fire brick.

The bricks are available from Jakarta, if you are patient. They are used on Lombok to make combustors for palm kernel shells so you may find them easily ‎in Bali.

The burners that work this way use quite high pressure (centrifugal) fans, not the propeller type. ‎The sawdust is dropped into a hole so it is picked up by the air and carried into the fire.

In short, the fuel is not loaded into the stove, it is blown in ‎a little at a time.

Because it is an institutional stove, you can use the fire power. There are such small fans widely used by ‎Lombok blacksmiths among others. They are all 450 watts because that is the limit for a residential home (2 amps).

It would be easy to check. You might be able to lead a pipe into the fire chamber ‎and fill it with sawdust, loosely. As it burns at the bottom, it will fall down. The fan will burn only the bit exposed at the bottom. Build a structure around it.

Regards
Crispin

Dear stovers

Looking for some advice or suggestions to utilise a source of excess sawdust for institutional cookstoves at a school. in Indonesia.

After several attempts with various devices to burn the sawdust directly have failed to be accepted by the kitchen over time I am now looking to better fuel management as the solution.

Looking for simple lowcost options for Pelletizing or making briquettes from the sawdust.

In various postings I have found reference to managing sawdust/husk fuel using cowdung as a binding material and simple screw or lever based press to create briquettes or cakes that are dried.

Although dung is locally available there is considerable resistance from the staff to incorporate dung into the kitchen setting as part of the fuel.

The volume of source material available (6-8sacks/day) does not justify a pelletizing machine and we feel this opportunity could make for a good student lead project to create a sustainable fuel management process for the kitchen/support staff.

The available sawdust fuel is from treated bamboo from local factory which has some moisture content (18-20%) at time it is created.

I have seen reference to other "binding materials" or even partial pyrolysis to bind the fuel and am looking for some suggestions of things to try for a local pelletizing/briquetting process.
Or some arguments to accept dung as binding material.

We need to generate enough fuel to feed 6-8 stoves operating over 2-4 hours food prep time on a daily or twice daily basis with reasonable efficiency.

Suggestions??

Tony Vovers
+62 (813) 3888 9062<tel:0813-3888-9062> (HP)

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