[Stoves] Stoves for School Kitchen

Mon Apr 4 16:07:43 CDT 2016

Dear Tony,

Introductory message:

1.  I have been on the Stoves Listserv for about 15 years and IMHO your 
message is by far the most complete INITIAL CONTACT that has ever been 
received, complete with photos!!!   I and probably many others are 
impressed with your thorough introduction and evident preparations.

2.  Raw loose sawdust is generally not a good fuel for rockets or TLUDs 
or almost any stove type (unless in a fluidized bed with blowers and 
much expense in larger systems).

3.  It sounds like your school and local community and local area would 
be good candidates for some type of pelletizing operation. But that 
involves some serious investment of funds and time, and you should get 
good advice on it.   (Not from me.   I like pellets, but somebody else 
needs to make them, or make briquettes, etc.) Briquetting might be a 
better option.   Check the website of legacyfound.org   and discuss with 
Richard Stanley, who is a subsrciber to this Stoves Listserv.   Making 
(pre-processing) of fuels should be considered as a related but separate 
"business venture" with leadership and workers who can function 
separately from the stoves and cooking activities.

4.  Paal Wendelbo always said "Start with the fuel."   What can you tell 
us about dry biomass fuels available in addition to sawdust? This will 
shape the discussions and final stoves.  Scrap wood, scrap bamboo (or 
bamboo harvested for stove fuel), can be put to use if you have it.   
What agricultural residues are in the area?   Corn stalks and cobs?   
Rice straw that is burned to get rid of it? There is no sense promoting 
a specific design untill we have a better feel of the fuel options.

5.  Your school-kitchen operation is large enough that you should 
consider some larger heat-units that can send flame to more than one 
pot.   That is not done very frequently, so some development work would 
be needed.   Also, you might want to consider having a "fire tender" who 
looks after several (or all) stoves and is not involved in cooking.   
Division of labor to get the jobs done efficiency can be useful.

6.  Multiple stoves can use one chimney, especially if arranged in a 
line or curve so that the distance from each stove is as short as 
possible.   You might even use that distance for having pre-drying of 
your biomass fuels.    If you had a brick chimney about 6 feet tall (or 
2 meters), it would get hot and give a good natural draft.   With a 
chimney, you must have the pots essentially seal off the air gaps; too 
much excess air will severely hurt your draft.

7.  The ability to have Forced Air (FA) is extremely important. Tell us 
more about the reliabily of electrical power at your site.

8.  Please tell us more about your operation.   Where are you in 
Indonesia?   More info about yourself, please.  What is your timetable 
and your resources (skills, funds, personnel, etc.).

Others on the Stoves Listserv will be joining into this conversation.

Paul

Doc  /  Dr TLUD  /  Prof. Paul S. Anderson, PhD
Email:  psanders at ilstu.edu
Skype:   paultlud    Phone: +1-309-452-7072
Website:  www.drtlud.com

On 4/4/2016 2:56 PM, Tony Vovers wrote:
>
> Dear Stoves experts I am looking for some advice and help from experts 
> in the field on a specific project.
>
> Cooking Stoves for a School
>
> Currently this international school in Indonesia is using Rocket style 
> cookstoves with sawdust as fuel source. (and some used timber/bamboo)
>
> Typical daily activity is to prepare food for up to 600 people, 
> smaller breakfast, full on lunch.
>
> The stoves are used for all types of cooking, typically in large pots 
> 20-40lt. There are up to 10 stoves running at any one time in a 
> covered but not indoor area.
>
> Most of the stoves are constructed from bricks with some metal gratings
>
> The current cookstoves were a part of a previous environmentally 
> focused student lead project.
>
> The key issues are:
>
> The rocket stoves though not very labor intensive are normally not 
> functioning even close to original designs in practice with variable 
> output and quite often loss of the “rocket” during burn.
>
> The kitchen staff do not have a lot of time to devote to maintenance 
> and operation, they need a stable and repeatable solution.
>
> The current stoves are not very efficient creating considerable smoke, 
> attempts to add some forced air as both primary and secondary air have 
> been largely unsuccessful (too complicated to control)
>
> This link shows some pictures of current setup:
>
> https://goo.gl/photos/6PfARtHjAYwB66oo8
>
> I have been following this list now for last 6 months or so and 
> reviewing with interest many of the projects in particular the TLUD 
> concepts and some of the innovative use of venturi from both air and 
> water(steam) and am looking for some advice/ideas to move ahead with a 
> better concept and direction for both the stoves and maybe the fuel in 
> this application.
>
> Key design points for up to 10 stoves:
>
> Sawdust as fuel source
>
> Fast load and start
>
> 2-4 hours of efficient burn time (prefer continuous feed if practical 
> for some units)
>
> 20-40Liter Cook Pots or Wok of similar size.
>
> Ability to adjust or divert heat as temperature control
>
> Simple maintenance and control, long stove life
>
> Control of effluent / exhaust in the work area – we are thinking in 
> terms of chimneys or ducting.
>
> Current stoves vent around the pot.
>
> Fuel – is it worth to add steps (pelletizing?) to the fuel preparation
>
> Soft features:
>
> Ability to use instrumentation and control for development of project 
> and student training on the use of advanced cook stoves, on use of 
> BioFuels for cooking and Biochar creation and to develop the best in 
> class design for this kitchen.
>
> Primary& Secondary air measurement and control
>
> Monitoring/Observing the burn real time (hard to see under the potJ)
>
> Burn efficiency (thermal and chemical) monitoring/measurement and 
> effluent testing, both gases and solid waste
>
> Overall energy efficiency – low / no use of external power 
> (electricity) preferred but not a showstopper
>
> Longer term if project is successful simpler designs would be rolled 
> out to neighboring school and community facilities as currently the 
> sawdust is available as a local “waste” product. It is very likely 
> that existing TLUD designs can fit the community needs but some 
> convincing is needed for the local community.
>
> I understand that this is a little away from the typical focus of this 
> group but there is no doubt that at the moment Indonesia has a massive 
> “burning” problem affecting health and well being of people and 
> animals. We want to increase students knowledge and interest in the 
> real opportunities that managed burning and Biochar creation could 
> have over the current practices of open fires for both cooking and 
> disposal of organic waste.
>
> For sure whatever we end up doing will be shared with this (stoves) 
> community.
>
> We expect some or all of this project to be student lead or student 
> involved.
>
> Some key questions:
>
> Is TLUD the recommended solution type for this application or is some 
> other approach more suitable?
>
> How to maintain cooking efficiency but include exhaust duct/chimney in 
> the design?
>
> If continuous feed or in-situ reloading is not feasible is there some 
> kind of quick change design that would allow cooking to resume with 
> minimal downtime between burns?
>
> Is there something that could be done with multiple stoves to simplify 
> design (ducting?)
>
> Are bricks and mortar a suitable building material or should the focus 
> move to steel?
>
> How to efficiently “tune” a stove for efficiency – correct amounts of 
> primary, secondary air. Previous local experiments are inconclusive as 
> there have been far too many variables.
>
> Is sawdust a suitable fuel?? or should it be compressed/pelletized for 
> use??
>
> Tony Vovers
>
> +62 (813) 3888 9062
>
>
>
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