[Stoves] small-scale torrefaction

Sat Mar 8 19:13:52 CST 2008

Tom et al..

I wouldbriquette add, that with a selected blends the biomass  
briquette has a double duty in being pre heated :  A biomass  
briquette with  a blend including, say eucalyptus or lemon grass   
leaves, stacked against the stove  will emit aromatics rapidly to  
dispel in this case mossies, as the briquette proceeds to   become  
too hot to handle --in some cases actually beginning to char n the  
outer surface.. The seasoned user will then toss it into the fire for  
instant ignition and a blazing burn...

Designer fuel, that...!

Richard Stanley,
Legacy Foundation
www.legacyfound.org
State of Jefferson

On Mar 8, 2008, at 3:04 PM, Thomas Reed wrote:

> Dear Tom and All:
>
> Briquetting biomass is good for stoves and gasification, but  
> briquetting
> torrefied biomass is much better.  Great pictures at your
>
> http://www.practicalaction.org/docs/consulting/Briquette%20annex% 
> 207%20-%20picture%20gallery.pdf
>
> site.
>
>
> I am glad to see someone being practical in the torrefied wood niche.
> (Torrefied Wood:  Roast biomass at 225-275 C and it loses A LOT of H2O
> and CO2 and a little CO, H2 and CH4 to leave a fuel with 24-28 kJ/g,
> rather than the 19 kJ of dry biomass.  It greatly reduce its  
> strength so
> it is MUCH easier to briquette.
>
> Tom's description mentions torrefaction, but I didn't see anything in
> the pictures suggesting it.
>
> The one briquetter looks like a Haussman brighetter.  Any Info?
>
> I hope this technology will help clean up the world and supply energy.
>
>
>
>
> Tom Miles wrote:
>> Gerrit,
>>
>>
>>
>> The SAM Muhima women's group project was funded at $73,500 by  
>> USAID by
>> Associates in Rural Development (ARD). There are about 600,000  
>> people in the
>> Muhima Service Availability Mapping (SAM) area. In this case  
>> torrefaction
>> seem to be used as a way to clean up the garbage and facilitate  
>> briquetting.
>> So it's a sanitary product. Broken briquettes are used as fuel to  
>> heat the
>> reactor. There is no indication of how much fuel is used to heat the
>> reactor.   If it makes a clean product that people in Kigale are  
>> willing to
>> pay for then it is worthwhile.  Organic fertilizer is also
>>
>> mentioned.
>>
>>
>>
>> See the pictures from the Practical Action/ITC report.
>>
>> http://www.practicalaction.org/docs/consulting/Briquette%20annex% 
>> 207%20-%20picture%20gallery.pdf
>>
>>
>>
>>
>>
>> I haven't checked the energy saved to briquette torrified biomass  
>> compared
>> with straight paper and wood. The specific energy for the latter  
>> is about 50
>> kWh/ton for briquetting plus 20-50 kWh/ton for grinding and  
>> processing.
>>
>>
>>
>> It looks like most of the USAID funding since has gone into the  
>> President's
>> HIV/AIDS programs.
>>
>>
>>
>> Tom
>>
>>
>>
>> Links
>>
>>
>>
>> Practical Action
>>
>> http://www.practicalaction.org/docs/consulting/briquette%20rwanda% 
>> 20final%20
>> report.pdf
>>
>> http://www.practicalaction.org/docs/consulting/Briquette%20annex% 
>> 207%20-%20p
>> icture%20gallery.pdf
>>
>>
>>
>> USAID
>>
>> http://www.usaid.gov/our_work/economic_growth_and_trade/energy/ 
>> publications/
>> success_stories/rwanda_biomass.pdf
>>
>> http://unfpa.co.rw/transforming%20garbage.html
>>
>> http://www.usaid.gov/locations/sub-saharan_africa/countries/rwanda/ 
>> stories/r
>> w_briq.html
>>
>> http://www.state.gov/g/oes/rls/or/2006/65709.htm
>>
>> http://www.globalization-africa.org/papers/51.pdf
>>
>> http://www.energyandsecurity.com/images/5._Gender.pdf
>>
>> http://www.state.gov/documents/organization/66321.pdf
>>
>>
>>
>>
>>
>> Service Availability Mapping
>>
>> http://www.who.int/healthinfo/systems/samreportrwanda.pdf
>>
>>
>>
>>
>>
>> From: Gerald Van Koeverden [mailto:vnkvrdn at yahoo.ca]
>> Sent: Saturday, March 08, 2008 10:50 AM
>> To: Tom Miles
>> Cc: Discussion of biomass cooking stoves
>> Subject: Re: [Terrapreta] small-scale torrefaction for developing  
>> countries
>>
>>
>>
>> It is interesting...I have e-mailed 3 USAID people who have worked  
>> on this
>> project.  But still no answer.
>>
>>
>>
>> I've divided my thoughts into two camps on torrefaction.
>>
>>
>>
>> Pro:  where torrefaction looks really good is when it is compared to
>> charcoal-making where little or no use is made of the energy  
>> released in the
>> process of carbonization.  After all, if torrefied biomass still  
>> has 90% of
>> the original biomass energy, whereas charcoal barely has maybe 50  
>> or 60%,
>> then the use of some energy to torrefy that biomass would probably  
>> add up to
>> a real overall energy saving.  But if the gases and extra heat  
>> released
>> during the process of carbonization (whether through flash  
>> carbonization or
>> pyrolysis) were efficiently harnessed and directed to produce an  
>> energy
>> source to, for example, produce electricity, then this edge might  
>> well
>> disappear.
>>
>>
>>
>> Con:  where torrefaction doesn't look as good is in comparison to  
>> the raw
>> biomass.  After all, the torrefying process loses 10% of the  
>> energy in the
>> original biomass, plus it takes a fair amount of energy to do.  So  
>> why even
>> bother, unless the combustion furnace used needs a consistent high- 
>> density
>> fuel to function properly, or the material has to stored and shipped
>> extensively?
>>
>>
>>
>> Gerald
>>
>>
>>
>> On 8-Mar-08, at 11:08 AM, Tom Miles wrote:
>>
>>
>>
>> Gerrit,
>>
>>
>>
>> Interesting find.
>>
>>
>>
>> It was a pilot study aimed at processing 16,000 tons of solid  
>> waste (of
>> 73,000 tons available) into fuel briquettes. I find a project  
>> summary at
>> http://www.ard-rwanda..org.rw/solidwaste.htm
>> <http://www.ard-rwanda.org.rw/solidwaste.htm>   It looks like  
>> there was a
>> proposal for 2004-2008 but no update.
>>
>>
>>
>> It's not clear from the ARD site if the torrefaction-briquetting  
>> project is
>> still running.
>>
>> http://www.ardinc.com/projects/detail_region.php?id=111
>>
>>
>>
>> The project seems to have stopped when the USAID funding stopped.
>>
>>
>>
>> Can someone contact ARD or USAID Rwanda for an update?
>>
>>
>>
>> Thanks
>>
>>
>>
>> Tom
>>
>>
>>
>> http://www.henrykellam.com/reports/CoP_version_Rwanda.pdf
>>
>>
>>
>>
>>
>>
>>
>> From: terrapreta-bounces at bioenergylists.org
>> [mailto:terrapreta-bounces at bioenergylists.org] On Behalf Of Gerald  
>> Van
>> Koeverden
>> Sent: Saturday, March 08, 2008 5:03 AM
>> To: Terra Preta
>> Subject: [Terrapreta] small-scale torrefaction for developing  
>> countries
>>
>>
>>
>> An extract from a USAID report on introducing small-scale  
>> torrefaction in
>> Rwanda.  Unfortunately, the sketch of the equipment  for  
>> torrefaction,
>> grinding and briquetting, would not transfer to this message.    
>> (They use
>> used car engine oil to heat up their biomass.)  But I included a  
>> link at the
>> bottom.
>>
>>
>>
>> Gerrit
>>
>>
>>
>> Torrefaction Technology
>>
>>
>>
>> A major concern expressed by many potential users of
>>
>> biomass fuel briquettes was the smell emanating from
>>
>> the briquettes, and the amount of smoke they emit
>>
>> during cooking. A pre-processing technology called
>>
>> 'torrefaction' was developed to remove the organic
>>
>> compounds in the solid waste that emanate bad smell
>>
>> and emit excessive smoke in briquettes.
>>
>>
>>
>> Low temperature carbonization of biomass to obtain
>>
>> roasted or "torrefied" products is a relatively recent
>>
>> development. Torrefied products can substitute charcoal
>>
>> in a variety of applications. Torrefied briquettes have
>>
>> superior combustion characteristics as compared with
>>
>> ordinary briquettes. They are easier to ignite, burn much
>>
>> faster with less smoke, and are essentially odorless
>>
>> compared with ordinary briquettes.
>>
>>
>>
>> The developed torrefaction technology is essentially a
>>
>> thermic fluid system comprising of (a) circulating pump;
>>
>> (b) oil storage tank; (c) furnace; (d) piping, fittings and
>>
>> instruments (Figure 1). The interesting thing about this
>>
>> system is its friendliness to the environment. It utilizes
>>
>> used car-engine oil, which at present is a nuisance
>>
>> waste in almost all the gas stations in Kigali. When
>>
>> servicing vehicles, used-oil is usually allowed to drain
>>
>> freely from the car engine to a container placed beneath
>>
>> the engine. The dirty used-oil is then disposed off in the
>>
>> soil where it can cause groundwater pollution, unfriendly
>>
>> smell that characterizes most gas stations in the City of
>>
>> Kigali, and other adverse effects to the environment. By
>>
>> using this oil in the torrefaction system, we are
>>
>> essentially cleaning the environment. Secondly, the oil-
>>
>> heating furnace is fired using reject briquettes, which
>>
>> again perfects the waste recycling system!
>>
>>
>>
>> The biomass is heated in a modified container system,
>>
>> through which hot used-oil is continuously circulated.
>>
>> The coil, which is meant to circulate the oil in the
>>
>> furnace, is specially designed. The oil gets heated in two
>>
>> sections of the furnace, i.e., the radiative and the
>>
>> convective zones. First, the oil enters into the coil placed
>>
>> in the convective zone and then goes to a portion of the
>>
>> coil in the radiative section. After the exit of the oil from
>>
>> the coil, its temperature depends upon the temperature
>>
>> of the furnace. The oil then goes to the pre-heater where
>>
>> the biomass gets heated up. The torrefied material is
>>
>> then conveyed to a grinder where it's pulverized before
>>
>> being passed into the briquetting machine for
>>
>> processing into biomass fuel briquettes.
>>
>>
>>
>> Also, heating the biomass before processing serves the
>>
>> purpose of relaxing the inherent fibers in the biomass
>>
>> and apparently softening its structure, resulting in
>>
>> release of some bonding or gluing agent on to the
>>
>> surface. This phenomenon is also known as 'sweating
>>
>> the biomass'. The work requirement for densification
>>
>> can be reduced by a factor of about two by preheating
>>
>> the raw material. The preheating therefore, lowers the
>>
>> power input. This phenomenon of thermally induced
>>
>> softening the resistance of fibers is also noticed in the
>>
>> everyday domestic activity of ironing cotton clothes.
>>
>> Only when the press (iron) is hot enough can the fibers
>>
>> in the cotton clothes be oriented in the desired direction
>>
>> with minimum effort. Once the biomass fibers are
>>
>> softened, a drop in resistance to briquetting results in:
>>
>> (a) reduced pressure required for briquetting, resulting in
>>
>> reduction in power consumption; (b) reduced frictional
>>
>> forces leading to a reduction of wear to contact parts,
>>
>> particularly the rotating screw; and (c) reduced
>>
>> resistance to flow leading to an enhanced rate of
>>
>> production.
>>
>>
>>
>> Grinding Mill System
>>
>>
>>
>> This system has been developed/manufactured and
>>
>> ready for mounting. Grinding mills are employed to
>>
>> pulverize and/or reduce the particle size of the feed
>>
>> material. This process results in an increase in the
>>
>> surface area of the material for easy, faster and efficient
>>
>> processing, to achieve optimum briquetting results.
>>
>>
>>
>> For biomass materials, it is essential to avoid gravity
>>
>> discharge from the grinding mills. We have designed
>>
>> and developed a system that utilizes an induced draft
>>
>> blower to produce suction that sucks and conveys the
>>
>> material pneumatically.
>>
>>
>>
>> Screw-Press Briquetting Machine
>>
>>
>>
>> We have manufactured a screw-press briquetting
>>
>> machine and currently awaits mounting, testing and
>>
>> calibration. Torrefied and pulverized organic waste
>>
>> material will be fed continuously into the screw, which
>>
>> forces the material into a cylindrical die. The die will be
>>
>> heated using a high resistance coil to raise the
>>
>> temperature to the point where lignin flow occurred.
>>
>> Pressure builds up smoothly along the screw rather than
>>
>> discontinuously as is common with piston presses.
>>
>>
>>
>> Advantages of the Torrefaction, Grinding and
>>
>> Briquetting Systems
>>
>>
>>
>> The above-described systems are homegrown, made by
>>
>> local people using local technologies and resources.
>>
>> The maintenance costs will be pretty low compared to
>>
>> imported systems. Since they are made locally,
>>
>> everything is known about the systems, hence, can be
>>
>> maintained easily and no need to import any spare parts
>>
>> or expertise because they are readily available locally.
>>
>> Employment has been created, because in our
>>
>> workshop we had no less than 10 technicians working,
>>
>> at any given time. Monetary resources were ploughed
>>
>> back to the Rwandan economy as opposed to if the
>>
>> systems were imported from outside. And more
>>
>> importantly, Rwanda stands a very good chance of
>>
>> starting to export this system to other neighboring
>>
>> countries, when production is scaled up. However, as
>>
>> Jamal Sanghir (director for energy and water with the
>>
>> World Bank) remarked recently, "renewable energies
>>
>> have high upfront costs, and therefore access to
>>
>> financing is necessary to scale-up."
>>
>>
>>
>> Currently, most countries in sub-Saharan Africa are
>>
>> importing their briquetting machines from India and
>>
>> Europe. Most of these machines have been grounded
>>
>> due to high maintenance costs and lack of spare parts.
>>
>> Recent cases occurred in Rwanda and Zambia, where
>>
>> brand new briquetting machines imported from Europe
>>
>> and India stopped functioning just a few weeks after
>>
>> being mounted by experts from the exporting countries.
>>
>>
>>
>> Economic Impact.
>>
>>
>>
>> Our entire briquetting machinery comprising of a modern
>>
>> torrefaction system, grinding mill and a state-of-the-art
>>
>> screw-press briquetting machine cost US $ 21,900,
>>
>> inclusive of installation, training and 3-6 months free
>>
>> maintenance. Investigations reveal that a similar
>>
>> system, if imported from India, Europe or USA would
>>
>> cost anywhere between US $89,500 and 92,300,
>>
>> used to support plant growth and improve soil structure;
>>
>> and (iv) to destroy pathogens or unwanted
>>
>> microorganisms, insect eggs and weed seeds in the
>>
>> organic waste.
>>
>>
>>
>> http://www.henrykellam.com/reports/CoP_version_Rwanda.pdf
>>
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