[Stoves] [Terrapreta] small-scale torrefaction for developing countries
Thomas Reed
tombreed at comcast.net
Sat Mar 8 17:04:15 CST 2008
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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