[Stoves] Designs

[Kevin Chisholm]

Dear Ian

...del...

Rather than starting with a search for stoves designs and evaluating whether 
or not they are appropriate, may I suggest that you "start at the other end" 
and define the problem and opportunity? Once you have the problem described, 
it is much easier to recognize or design a solution.

1: What production rate do you require, in terms of kG of dried Kava product 
per hour?

2: What is the moisture content range of the raw kava?

3: What is the desired moisture content range of the finished kava?

4: What are the permissible temperature and Relative Humidity conditions 
required to avoid product degredation and to produce a top quality product? 
More specifically, is there an advantage to product quality and selling 
price if a special drying and heat treating procedure is employed?

5: What is the size and form of the product being dried? (Leaf, root, 
chopped, grated, sizing, etc...?)

6: Is the process to be continuous or batch?

7: Will the drying process be manned continuously, periodically, or is it 
sensible to automate teh process, because of labor cost or product 
degradation considerations?

8: Do you have a description of the drying procedure used now?

9: Can you pre-dry the raw kava, say by solar drying, or forced flow of 
ambient air, to reduce the thermal load on your fired drying system?

10: Can you describe the typical procedure presently employed for drying 
kava now?

11: Can you describe the fuel available, in terms of size, moisture content, 
heating value, etc?

12: Is electric power available?

13: Is fuel cost, and fuel utilization efficiency, a consideration?

That would be a good starting point.

The next thing would be to explore whether a direct fired dryer could be 
used, or if an indirect drier is required. Direct fired driers are generally 
of higher capacity, greater thermal efficiency, and lower cost per unit of 
capacity. However, unless the burner system is well designed, there might be 
a possibility of product degradation due to contamination with products of 
incomplete combustion or ash. Possibly you should be considering a gasifier 
and burner system. Indirect fired systems are more costly, less efficient 
because of stack and heat transfer energy losses, and generally have a lower 
drying capacity for a system of similar size.

Basically, there are two components to your system: The stove system, where 
fuel energy is converted to hot air of suitable quality, and the dryer 
system, where the heated and conditioned air is brought into contact with 
the product.

>
> Also my application is in the developing world and is targeted toward
> preservation of the environment here. It involves heating for a kiln drier
> for Kava production.

Do you already have a kiln system constructed? If so, could you please 
describe it, and how it is intended to be heated?
>
> What I would like to ask is if anyone knows of another mailing list that
> discusses applications for such designs as the rocket stove for others, 
> for
> uses other than cooking.??  Maybe we could start one?
>
Tom Miles and Company have done a tremendous job of categorizing and storing 
stoving information for general availability. It might be more helpful to 
stay with the Stoves List so that anything helpful evolving from this thread 
would have wider availability.

Best wishes,

Kevin