Carbonisation and agglomeration - Casindo · Carbonisation and Agglomeration ... for cooking or barbecue, ii) ... consumer tests, market study, and a feasibility study in 2002. 14

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Module 2a

Carbonisation and Agglomeration

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Training course on Renewable Energy

Carbonisation

Agglomeration– Relevance– Agglo-briquettes

Process description– Overview– Photo series

Case study in Mali– Background– Setup– Market and feasibility– Bottlenecks– Conclusions

Torrefaction

Outline

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Overview of carbonisation processesA large variety of processes, ranging from traditional to very modern, from smallscale to large scale, etc.

A useful subdivision:

Direct heating

Indirect heating

Heating withrecirculating gases

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Often traditional systems, like the Brazilian Beehive or Americal Missouri kiln

Characterised by: Long cycle times (x0 days) Moderate efficiencies (max 25%) Pollution through emissions to air and groundwater Low capital costs, high labour requirements

Carbonisation: Direct Heating

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Carbonisation: indirect heating

The Dutch “Twin Retort” system

The Russian “Ecolon” system

Indirectly heated by combustionof carbonisation gases

Semi-batch systems Good efficiencies (ca. 30%) Cooling separated from reactor

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Heating with recirculating gases

Large systems, high capital costs, low labour costs Wood flows downwards and converts gradually to charcoal Heating is performed by recirculating combusted, cleaned

gases Efficiencies are often high (35%) Sometimes combined with liquid product recovery High level of process and product control possible

Reichert/Degussa retort Lambiotte CISR retort

Lambiotte/SIFICretort

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Lurgi SIMCOA plant, Western Australia Two retorts, 7 m diameter, 35 m high Production is 13,000 tonne of charcoal/year/retort Efficiency 30%-40% Carbonisation and cooling integrated Only 20-40% of heat provided externally, the rest

is provided by the carbonisation reaction itself Capital costs 10 MUS$ in 1989

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Comparison of systems

Indirect systems better than recirculating systems, although efficiency is a bitLower and operational costs are not included

Recirculating systems have low reactor utilisation, probably because ofintegrated drying

University of Hawaii Flash Carboniser is very promising, but doubts remainregarding status of technology

Efficiency Capital costs per tonne of charcoal Production per unit reaction volume

(%) (kEuro/tonne charcoal) (tonne charcoal/year/m3)

Direct heating

JCKB retort 23% 0.18 12.6

University of Hawaii 50% 0.18 594

Indirect heating

Twin Retort Carboniser 33% 0.38 70

Policor (Ecolon system) 25% 0.06 71

Enviro Carboniser 53% 0.14 192

LSIWS carboniser n.d. 0.27 63


Reichert 34% n.d. 34

Lambiotte CISR 30% 0.36 16

Lurgi process 35% 0.32 10

Rheinbraun process n.r. n.d. 265

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CarbonisationHeating of biomass in absence of air, while maximising charcoal production.

• Temperature: 500 - 700 °C

• Residence time: 8 hours - a number of days

Can be produced very high-tech as well as traditionally

Global use of charcoal in 2000, 40.5 million tonne, and 19.8 million tonne just forAfrica (mainly for cooking)

In Europe, FSU, USA and Japan charcoal is a luxury product. Applications are i) fuelfor cooking or barbecue, ii) as reducing agent in the steel industry, iii) as feedstock foractive coal production

Efficiencies of traditional systems range from 8% (wt. basis) to 25% (wt. basis).

Efficiencies of high-tech systems are >30%, because combustion of the volatile gasesprovides heat.

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Examples of carbonisation

Drum carbonisation in Sudan Twin-retort carbonisation inthe Netherlands

Modern systems generally cannot compete with traditional systemsin developing countries, mainly because of high capital costs.

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Examples of carbonisation

Estonia & China

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Relevance– World wide > 2 billion people depend on woodfuel– Over 40 million tonnes charcoal produced in 2000 (50% in Africa)– High woodfuel consumption leads to deforestation in urban areas– Search for alternatives like: gas, kerosene, alternative biofuels

Agglo-briquettes: alternative for wood-based charcoal– Small, round briquettes (ø 25-30 mm)– Made from carbonised agro residues like cotton stalks or bagasse– Can be used in same cookstoves as traditional charcoal– Simple and low investment technology with a labour intensive

process

Background agglomeration

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Overview

Process (1)

Carbonisation Transport

Agglomeration

Packaging

Agro-residues

Water

Binder Electricity

Curing

Drying

Preparation

Distribution

Carbonisationunits Sacks

Agglomerators

Hammer mills

Drying tables

Curing ovens

Sacks

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Training course on Renewable Energy Raw material: cotton stalk

Process (2)

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Training course on Renewable Energy Gathering of cotton stalk from the field

Process (3)

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Training course on Renewable Energy Carbonisation in many small carbonisation units

Process (4)

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Training course on Renewable Energy Carbonised cotton stalk

Process (5)

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Training course on Renewable Energy The carbonised stalk is packed for transport

Process (6)

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Prior toagglomeration,the stalk isground to apowder using ahammer mill

Process (7)

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Training course on Renewable Energy Agglomeration plant with several agglomeration units

Process (8)

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Process (9)

Production ofthe actualagglo-briquettes

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Process (10)

After agglomeration, the briquettes are left to dry

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Process (11)

The driedagglo-briquettes arecured in aspecial oven,which givesthem highstrength

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Process (12)

The finishedbriquettes arepacked andtransported tothe market,where they aresold to thecustomers

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Process (13)

The briquettescan be usedjust liketraditionalcharcoal

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Case study: agglo-briquettes in Mali (1)

Background and Setting– In Bamako > 100,000 t/a charcoal is used for cooking– Use of wood and charcoal causes severe deforestation– In South of Mali over 480,000 ha cotton is grown (2000)– Most of the cotton stalk is burned in the field as a means of

disposal

Agglo-briquettes in Mali– Work on production of agglo-briquettes in Mali started in the

late 1990s with trial runs, consumer tests, market study, anda feasibility study in 2002

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Project Setup


Agglomerationplant

Cottoncoal

Cottoncoal

Cotton coal production

• Potential of >100,000 t/a cotton coal

• By cotton farmers

• Training provided

• Carbonisation units provided

Agglomeration plant

• Near Bamako (25 km)

• Capacity 2.000 t/a

molasses

Binder supply

• Two sugar plants in Mali

• Sufficient molasses available

Briquettes

Agglo-briquettes

• Sold in Bamako

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Market Study


Quality

• Comparable / better than charcoal

• “Water boiling test” positive

Acceptability

• 50 households and 20 smallconsumers

• Attractive product

• Less smoke

• Longer combustion time

Price level

• Similar to charcoal

Marketing

• Large market potential inBamako (>100,000 t/a)

• Distribution through existingchannels

• Publicity and promotioncampaigns

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Production costs

Financial feasibility– Investment costs: ~ 250 kEUR *– Annual operating costs: ~200 kEUR– Income from sales: ~ 250 kEUR– Simple payback period: ~ 5 years

* Due to learning effects, investment costs may drop

other inputs(25%)

cotton coal(23%)

Molasses(10%)

Personnel(30%)

Depreciation(12%)


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Main factors that influence feasility– Production and price of the cotton stalk charcoal– Sales and price setting of the agglo-briquettes

To eliminate risks a pilot project is recommended– Large scale cotton stalk carbonisation and logisitics experiment– Production at 25% of capacity– Large scale marketting study with cured agglo-briquettes


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Agglo-briquettes are a good alternative for fuelwoodand charcoal where agro-residues are available

The production process is low capital investment andlabour-intensive

Agglo-briquettes have clear benefits– Reduction of deforestation– Reduction of CO2 emissions– Generation of employment and additional income for farmers– No need for subsidising imported fossil fuels

Conclusions

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TorrefactionRoasting – partial carbonisation

of organic material in absence

of oxygen

Main product: Torrefied biomass/

Bio-char

Process conditions

T = 280 - 400 °C

P = atmospheric

solid ~ 5 - 15 min

Autothermal operation by burning

Gases

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Torrefaction

“Torrefaction products” produced at differenttemperatures

Torrefaction pilot plant; capacity ~ 100 – 150 kg/hr input

Lab-scale pilot plant (~ 20 kg/hr)

THANKS FOR YOUR ATTENTION

TERIMAH KASIH

Documents

Carbonisation and agglomeration - Casindo · Carbonisation and Agglomeration ... for cooking or barbecue, ii) ... consumer tests, market study, and a feasibility study in 2002. 14