[Stoves] Stoves for School Kitchen
Tony Vovers
vovers1 at gmail.com
Tue Apr 5 02:57:42 CDT 2016
Thanks to so many for rapid and extremely valuable feedback.
We are in Bali Indonesia in the hills South West of the Ubud community.
The school is K thru 12 and is operating 5 days per week.
Very few dinners except special occasions.
Limited metal working capabilities in the facility but surely available
within the local community.
Let me digest these feedbacks and dig a little more into fuel sources and
availability.
The school has excellent community engagement programs so the opportunity
is there to impact local polluting waste burning processes with community
support.
I cannot express my gratitude for the clear and focused feedback on this
project and potential. I am as excited about the educational opportunities
as the technology enhancement.
It is clear some quick wins even in current system on fuel, skirting,
covers etc can get us started.
One key issue we have is that the kitchen is a living entity and cannot
stop operation , too many hungry mouths to feed. More soon.
Tony Vovers
+62 (813) 3888 9062
On Apr 5, 2016 07:29, "Ronal W. Larson" <rongretlarson at comcast.net> wrote:
Tony, Paul, et al
I like all of Paul’s comments and questions. Just add some more - with
emphasis on answering our questions.
I especially like the fact that you are interested in biochar. What is
going on with biochar in your area? What costs for charcoal in your area?
Besides TLUDs, there are other options for making char (with a cooking gas
output). Can you give us more data on your present use of biomass (kg per
day). Any estimates on likely efficiencies? Do the cooks complain of any
aspect of fire tending now?
Any pelleting operations now in your area (for animal feed, for instance)?
Is there enough sawdust to establish a separate business?
I see no skirts in use in the photos. They would probably pay off in a few
months, if not weeks.
What grade levels for the students? Are there faculty with metal working
skills?
I am not sure you need a chimney - given that all your cooking seems to be
well ventilated. Most of us who have worked with TLUDs can do so without a
chimney.
See also some insert answers below.
On Apr 4, 2016, at 3:07 PM, Paul Anderson <psanders at ilstu.edu> wrote:
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.
*[RWL: seven days a week? Never dinners? (Thinking about adding a
solar cooker side to your question. Solar will need a TLUD backup - but
could be a best option.)*
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.
*[RWL: How many cooks? What is the smallest and largest pot size and
cooking duration time (4 hours is a lot for a TLUD - but the pot can be
switched.)*
Most of the stoves are constructed from bricks with some metal gratings
* [RWL: generally speaking, bricks are less efficient (soak up a lot of
heat at first). We only hear about bricks these days with planchas - and
those stoves are quite inefficient.*
The current cookstoves were a part of a previous environmentally focused
student lead project.
*[RWL: I was surprised at the many types. Is there existing documentation
on them? How long ago? Any TLUD attempts then?*
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)
*[RWL: Make sure you are also following the GACC site. Also follow the
work of fellow Indonesian Prof. Nurhuda.*
This link shows some pictures of current setup:
<https://goo.gl/photos/6PfARtHjAYwB66oo8>
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.
*[RWL: Having free sawdust should be a powerful motivator. But your
future kitchen could make money for the school (lower cost meals) - if you
can make and sell biochar.*
Key design points for up to 10 stoves:
Sawdust as fuel source
Fast load and start
*[RWL: TLUDs are OK on this, but never as good on high power as can be a
rocket. TLUDs save a lot of a cook’s time in maintaining the right power
level - for long periods.*
2-4 hours of efficient burn time (prefer continuous feed if practical for
some units)
*[RWL: TLUDs can be called continuous feed. Different heights and
diameters of the fuel load can give you the right power and energy
combinations.*
20-40Liter Cook Pots or Wok of similar size.
Ability to adjust or divert heat as temperature control.
*[RWL: We call this TDR = Turn Down Ratio. Most can get to 2:1 (highest
generally at first - to get to a boil). But you have plenty of cockpot
spaces - so it should be easy to give you a wide range of both power and
energy levels. You don’t have the usual problem of trying to do ten types
of cooking on one stove. If your students are to make these stoves - they
can have one general design and vary the heights and diameters.*
Simple maintenance and control, long stove life
*[RWL: Once set via primary air control, the power level can stay constant
for even hours. Stove life will depend on the stove material - generally
meaning stainless. There are possibilities for coatings coming along. But
if you are saving money on fuel - I wouldn’t worry if a stove lasts only a
year.*
Control of effluent / exhaust in the work area – we are thinking in terms
of chimneys or ducting.
Current stoves vent around the pot.
*[RWL: As said above, TLUDs can operate in closed rooms. Operating with
a skirt is much easier without a chimney.*
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.
*[RWL: You are adding a lot here. Simple air monitoring and keeping
track of fuel consumption could be enough for most student learning.*
Primary& Secondary air measurement and control
*[RWL: Measurement is a lot harder than control. And control is very
important (and often not there).*
Monitoring/Observing the burn real time (hard to see under the potJ)
*[RWL: Hmm. I don’t think this will be a big problem. You should see
plenty of flame when you are starting the top-lighting. You will set it
for max primary air and later lower the primary air when boiling (which
presumably you can see) starts. (Incidentally, pots should generally have
lids - and I don’t see that in the photos.)*
Burn efficiency (thermal and chemical) monitoring/measurement and effluent
testing, both gases and solid waste
*[RWL: Paul’s question on reliability of electric power is important. You
should be able to get away with a few watts per stove - minuscule draw for
TLUDs.*
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.
*[RWL: Good plans, and for next.*
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?
*[RWL: If you want biochar, it is likely that TLUDs are the best answer -
but with so many stoves, there may be another way to make gas and char.*
How to maintain cooking efficiency but include exhaust duct/chimney in the
design?
*[RWL: chimneys could be a plus - but I think you can do without - with
TLUDs.*
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?
*[RWL: Yes. Lots in this list archives on switching something.*
Is there something that could be done with multiple stoves to simplify
design (ducting?)
*[RWL: Possibly. A new topic for us I think. Paul gave an idea of
putting multiple outlets in a row.*
Are bricks and mortar a suitable building material or should the focus move
to steel?
*[RWL: My guess is steel for most on this list. Reason is efficiency.
Bricks and mortar are good for heating systems.*
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.
*[RWL: Primary air doesn’t need “tuning”. You need control - a blower
will be helpful, but maybe only a simple air control is needed. Not much
information on secondary air control and almost no-one doing it (and
probably should). We are still learning on that front. There is obviously
an optimum - too little and incomplete combustion (visible smoke - can
improve by cutting back on the primary). Too much and the excess secondary
air drops the temperature of the gases striking the pot.*
Is sawdust a suitable fuel?? or should it be compressed/pelletized for use??
*[RWL: As Paul said - a great fuel, but hard (or worse?) to make char
efficiently unless pelletized or briquettes. Not much use yet of
briquettes with char-making. We haven’t talked much about non-sawdust
fuels - and there may be some that are also free and suitable. Chips are
cheaper.*
* Good luck. *
*Ron*
Tony Vovers
+62 (813) 3888 9062
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