[Stoves] combusting Coffee Pulp/Cherry

Fri Feb 10 19:56:30 CST 2012

Frank,

Here in Vietnam we have both dry coffee husks and wet coffee pulp.
We gasify the dry coffee husk as a source of fuel for drying the coffee
bean from a wet mill,
 and that we ferment the wet coffee pulp as a feed for pigs.
The fermented coffee pulp has a crude protein content as high as 14%.

Wet coffee pulp is an extremely low-grade fuel, but it can be easily
converted into a quality pig feed.
All that is needed to ferment it is to add 5% molasses by weight and put it
into a sealed container or bag.
The pH of this fermented brew drops below 4.0.
After one week it can be fed to pigs.

Some types of waste earn more money as a fuel,
 and some types of waste earn more money as a feed.
>From an economic point of view, it's far from ideal to burn pig feed.

Thanks.
Paul

On Sat, Feb 11, 2012 at 8:30 AM, Frank Scott <franks at q-net.net.au> wrote:

> **
> Paul
>
> I build a proto-type Cremasco Bioheater for the Pinhalense Group in Brazil
> where we successfully combusted freshly processed coffee pulp that
> contained a moisture content of about 80% without
> any smoke emissions. See below;
> Cheers
> Frank Scott
> **********************
>
>
> The Cremasco Bioheater for the Coffee Processing Industry******
>
> **
>
> The Cremasco Bioheater gets its name from its inventor, Father Dominic
> Cremasco, who in the 1960s design a furnace to completely combust (at high
> combustion temperatures) low-grade wet biomass materials that normally
> would not be considered fuel. While numerous Cremasco Bioheaters have
> successfully operated since the mid-1980s, only recently has there been a
> focused engineering effort to match the process with specific commercial
> applications. A feasibility study by The Rocky Mountain Process Group in
> the United States concluded that the drying of wet coffee beans using heat
> produced from the combustion of coffee pulp in a bioheater is a viable
> application of this technology. The coffee processing application
> simultaneously addresses an environmental problem (pulp waste disposal) and
> offers the economic and environmental benefit of reduced or eliminated
> fossil fuel and wood consumption.****
> **** HOW IT WORKS****
>
> Wet feed materials like coffee pulp can be successfully processed because
> the bioheater is designed to first dry and partially burn the biomass feed
> material in a primary chamber followed by complete combustion of the gases
> and residual char material in a secondary chamber. Biomass is fed either
> manually or automatically to the bioheater and ash is withdrawn from the
> bottom of the unit. From such wet fuels, the bioheater has demonstrated
> that it can sustain combustion temperatures of 1,000ºC to 1,200ºC with no
> visible emissions to the atmosphere. Heat in the flue gas is transferred by
> a heat exchanger to flowing air or water for space or process heating such
> as coffee bean drying.****
>
> ****
> WHY COFFEE PROCESSING****
>
> Dried green coffee beans represent only about 16% of the weight of ripe
> coffee cherries, resulting in a large amount of pulp waste with limited use
> in other applications. Coffee pulp waste is a pollutant that is banned from
> some waterways but in some regions continues to be dumped in rivers. In
> most cases, solar drying is not completely effective. Freshly pulped,
> fermented, and washed parchment coffee has a moisture content of about 55%
> by weight and must be reduced to under 11% for long term storage and
> roasting. At this moisture content, the parchment husk prevents
> deterioration of the dry coffee beans. Optimal temperatures for mechanical
> air drying of coffee beans are in the range of 45 to 55ºC and the drying
> process typically takes 24 to 36 hours. The beans are subject to a
> continual flow of warm air during which time they undergo distinct changes
> in color, hardness, and chemical composition.****
>
> **
>
> *BENEFIT TO COFFEE GROWERS*
>
> The Cremasco Bioheater consumes coffee pulp as fuel to generate heat for
> drying wet green coffee beans. This approach offers the following
> significant advantages and no obvious technical drawbacks:****
>
> ****
>
> · the potential for the solution of multiple environmental
> problems.(consumption of polluting coffee pulp as fuel, and reduction in
> deforestation for fuel wood),****
>
> · contributes to the concept of sustainable communities,****
>
> · encompasses an enormous international market,****
>
> · reduces risks relating to coffee spoilage (more rapid drying than solar
> drying),****
>
> · the ash produced from the Bioheater can be used as fertilizer to return
> minerals to the soil for coffee growing, and ****
>
> · dry coffee beans can be sold for many times the value of wet beans,
> thus the farmer gains added sales flexibility due to greatly increased
> storage time.****
>
> ****
>
> *PROPOSED COFFEE DRYER*
>
> The Propsed Cremasco Coffee Dryer is based on drying a 1,000 kg batch of
> wet green beans in a 32 hour period. The wet pulp feed rate to the
> Bioheater is 86.1 lb/h (wet basis) and assumes 65 wt% moisture in the pulp.
> Other key assumptions include a wet pulp / dry green coffee mass ratio =
> 2.5, wet green coffee moisture content = 55 wt%, dry green coffee moisture
> content = 10 wt%, ash content of bone dry pulp = 5 wt%, bone dry pulp heat
> of combustion = 7,333 Btu/lb.****
>
> ****
>
> ****
>
> ****
>
> *Figure 1: Cremasco Bioheater Coffee Drying Process*
>
> ****
>
> Figure 1 illustrates the major components of a simple, small Cremasco
> Bioheater Coffee Bean Drying System. This system has a capacity of 1,000 kg
> of wet coffee beans per batch. Smaller and larger systems can be designed
> for a range of coffee bean processing rates. ****
>
> ****
>
> Other potential applications for the Cremasco Bioheater include the
> coconut oil, palm oil, citronella oil, and domestic farm animal industries.
> ****
>
> ****
>
> Our current proposal is to optimise the bioheater for application in the
> coffee industry. For further information contact Frank Scott on (61-8) 9474
> 1026 or by email at franks at q-net.net.au, ****
>
> ****
>
> ****
>  Mass and Energy Balance for the Cremasco Bioheater: **** Coffee Pulp
> Processing  ****
>
> The following tables provide the results of a mass and energy balance
> spreadsheet model for the Cremasco Bioheater. The model assumes that
> coffee pulp with a moisture content of 65 wt% is the only biomass feed to
> the Bioheater. The heat generated by the combustion of coffee pulp is
> then used to heat a separate air stream, which can be used for drying green
> coffee beans. This high moisture content for coffee pulp is realistic and
> represents the high end or essentially a “worst case” moisture content
> for biomass in general.
>
> ****
>
> ****
>
> As with any process model, key assumptions were required and are
> summarized in Table 1.
>
> ****
>   Table 1. Major Assumptions used In Mass and Energy Balance Model****
>
> Biomass (coffee pulp) feed rate ****
>
> 100 kg/h****
>
> Biomass (coffee pulp) heat of combustion (dry basis)****
>
> 4,073.9 kcal/kg****
>
> Biomass moisture content (wet basis)****
>
> 65 wt%****
>
> Biomass ultimate analysis (dry basis) (wt%)****
>
> ****
>
> Carbon****
>
> 43.400****
>
> Hydrogen****
>
> 7.165****
>
> Oxygen****
>
> 41.495****
>
> Nitrogen****
>
> 2.940****
>
> Ash****
>
> 5.000****
>
> Base temperature for thermodynamic calculations****
>
> 25 0C****
>
> Temperature of inlet air streams****
>
> 25 0C****
>
> Biomass feed internal preheat temperature****
>
> 65.5 0C****
>
> Combustion air internal preheat temperature****
>
> 260 0C****
>
> Bioheater total surface heat loss****
>
> 18,905 kJ/h****
>
> Flue Gas to Atmosphere temperature****
>
> 107.2 0C****
>
> Temperature of drying air to drying process****
>
> 55 0C****
>
> In the model, combustion air (excess air above stoichiometric) is adjusted
> to achieve a minimum 3 % by volume oxygen in the flue gas, simply as a
> general guideline for good combustion practice. The results show that
> even with 65 wt% moisture in the coffee pulp feed, a Bioheater flue gas
> temperature of 979 0C can be achieved. Lower moisture content feed will
> allow Bioheater operation at higher temperatures and/or higher oxygen
> concentrations in the flue gas. The optimum temperature is that which
> provides complete combustion of hydrocarbons in the flue gas. For a given
> biomass composition, biomass feed rate, and air feed rate, preheating of
> feed and combustion air only affects the combustion temperature, and has no
> effect on the available sensible heat in the flue gas.****
>
> ****
>
> The summary energy balance around the Bioheater only is shown in Table 2.*
> ***
>
> ****
>     Table 2. Energy Balance Summary for the Cremasco Bioheater****
>
>   *Energy Inputs*
>
> ****
>
> *kJ/h*
>
>   Biomass Combustion Energy
>
> ****
>
> 567,107****
>
>  Air Preheat
>
> ****
>
> 61,639****
>
>  Feed Preheat
>
> ****
>
> 12,903****
>
>  Total Input
>
> ****
>
> *641,649*
>
>  **
>
> ****
>
> ****
>
>   *Energy Outputs*
>
> ****
>
> *kJ/h*
>
>   Latent Heat of Vaporization of H2O
>
> ****
>
> 158,811****
>
>   Surface Heat Loss
>
> ****
>
> 18,905****
>
>   Flue Gas Sensible Heat
>
> ****
>
> 462,470****
>
>   Ash Sensible Heat
>
> ****
>
> 1,398****
>
>   Total Output
>
> ****
>
> *641,584*
>
>   ****
>
> ****
>
> ****
>
>   *Energy Balance Closure =*
>
> **
>
> *99.9899%*
>
>      ****
>
> ****
>
> Fig. 1 and Table 3 provide a Flow Diagram and corresponding Mass and
> Energy Balance for the Cremasco Bioheater. In the diagram (Fig. 1), the
> Bioheater internal heat transfer pathways are shown schematically as brown
> lines and are not intended to reflect the actual physical arrangement of
> the Bioheater.
>
> ****
>
> ****
>
> Direct transfer of heat from the flue gas to drying air using a flue gas
> heat exchanger is assumed in this example. Results show that more than
> enough heat is available in the flue gas from the combustion of coffee pulp
> to dry green coffee beans from the pulping operation. Based on literature
> surveys, it appears that for optimum air drying of a batch of green coffee
> beans (from 55% moisture to 10% moisture), the operation should take about
> 32 hours with a heated air stream temperature of 55 0C. Approximately 1.5
> kg of wet green coffee beans are produced per kg of wet coffee pulp, so the
> wet green bean production rate would be 150 kg/h. The starting green bean
> batch size would be (32 h)(150 kg/h) = 4,800 kg batch. To dry the wet
> green beans from 55% to10% moisture, 74.98 kg/h H2O must be evaporated. The
> total heat required for the drying would be approximately 197,813 kJ/h.
>
> ****
>
> ****
>
> In this example, the Cremasco Bioheater processing 100 kg/h of coffee pulp
> containing 65 wt% moisture will produce flue gas with a gross sensible heat
> content of 387,928 kJ/h. If it is assumed that the temperature of the
> flue gas discharged to the atmosphere is 107 0C as in this example, the
> net sensible heat available for heating air for drying is 352,330 kJ/h. Therefore,
> almost twice as much heat is available from processing coffee pulp as
> required to dry the wet green coffee beans. The surplus heat (154,517
> kJ/h) could be used to dry larger batches of coffee beans or for space
> heating or hot water heating.
>
>
>
> ****
>
> ****
>
> ****
>
> ****
>
> ****
>
>
> *Table 3. Mass and Energy Balance Summary for the Cremasco Bioheater
> (Coffee Pulp Processing)*
>
> ****
>
> ****
>
>
>  ------------------------------
> *From:* stoves-bounces at lists.bioenergylists.org [mailto:
> stoves-bounces at lists.bioenergylists.org] *On Behalf Of *Paul Olivier
> *Sent:* Saturday, February 11, 2012 5:18 AM
> *To:* Discussion of biomass cooking stoves
> *Subject:* Re: [Stoves] Coffee Pulp/Cherry
>
>  One of the best ways to manage wet coffee pulp waste is to ferment it.
> See: http://esrla.com/pdf/landfill_07.pdf
> The fermented coffee pulp is then fed to pigs.
> The feces of the pig is fed to BSF larvae,
> and the residue of the larvae is fed to red worms.
>
> One of the best ways to manage dry coffee husk waste is to gasify it:
> http://esrla.com/pdf/landfill_06.pdf
> To prevent agglomeration of the biochar and to enhance gasification,
> it is best to gasifiy the coffee husk together with some rice hulls.
> I mix them 50%/50% by volume.
> Simply burning coffee husks is really a bad solution,
> since it gives rise to a lot of truly awful black smoke.
>
> Thanks.
> Paul Olivier
> Paul A. Olivier PhD
> 27C Pham Hong Thai Street
> Dalat
> Vietnam
> Louisiana telephone: 1-337-447-4124 (rings Vietnam)
> Mobile: 090-694-1573 (in Vietnam)
> Skype address: Xpolivier
> http://www.esrla.com/
>
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>

-- 
Paul A. Olivier PhD
27C Pham Hong Thai Street
Dalat
Vietnam

Louisiana telephone: 1-337-447-4124 (rings Vietnam)
Mobile: 090-694-1573 (in Vietnam)
Skype address: Xpolivier
http://www.esrla.com/
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