Technologies to convert wood to energy. Thermo-chemical conversion.

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1 Technologies to convert wood to energy. Thermo-chemical conversion. First thematic seminar and study visit in Tartu region. INTEREG IVC Project BIO-EN AREA. Ülo Kask Tallinn University of Technology, Thermal Engineering Department

2 Preface During last year strong interest for biomass gasification topic has been emerged in our country from one side and much efforts for development of gasifiers has been done in the world from other side. Following I try shortly to introduce this field in my presentation.

3 Topics Biomass energy chain Opportunities to convert wood and use it in energy Thermo-chemical conversion of biomass (wood) Wood gas and wood gasifiers CHP running on wood gas Automobiles running on wood gas

4 Biomass energy chain Cultivating, harvesting/gathering Processing, transport, storage Conversion Thermo-chemical, Physical-chemical, Bio-chemical Carbonization Grinding Aerobic degradation Gasification Pressing Anaerobic digestion Pyrolysis Esterification Fermentation (C 2 H 5 OH) Solid, liquid and gaseous products (fuels) Combustion Thermo-mechanical conversion Heat, electricity, motor-fuels

5 Opportunities to convert wood and use it in energy Physical-mechanical conversion of wood (pretreatment) and combustion in fire places and energetical furnaces. Bio-chemical conversion of wood (wood waste) (biogas, bio-ethanol, bio-methanol). Thermo-chemical conversion of wood (decomposition) and combustion of products (wood gas, charcoal, wood oil) in large combustion facilities or in in internal combustion engines.

6 Physical-mechanical conversion of wood (pre-treatment) and combustion in fire places and energetical furnaces Wood chips (felling residues chips), wood briquettes and pellets, wood logs, saw dust etc

7 Termo-chemical conversion of biomass (wood) By thermo-chemical conversion processes (such gasification, pyrolysis and carbonization), solid biofuels are transformed into solid, liquid and/or gaseous secondary energy carriers primarily using heat. 2C + O 2 2CO CO + H 2 O CO 2 + H 2

8 Selection of decomposition products of wood is presented on figure at right During conversion of biomass at high temperature three main products are forming: gas, bio-oil and char.

9 Gasification Within a thermo-chemical gasification solid biomass (biofuels) are preferably converted into gaseous energy carriers. The process my be viewed as combustion-like conversion, but of less oxygen available than needed for burning, excess air is 0,2-0,4 (equivalence ratio), it means that up to 40% of oxygen needed for complete burning is given). This is the region of maximum energy transfer to the gas.. The goal in gasification is to break down this wide variety of forms into the simple fuel gasses of H 2 and CO hydrogen and carbon monoxide. The produced gas may alternatively also be further converted into liquid or gaseous secondary energy carriers (e.g. methanol, Fisher-Tropsh-Diesel fuel, bio-sng) suitable for use in transport sector.

10 Processes in gasification Gasification is made up for 4 discrete thermal processes: Drying, Pyrolysis, Combustion and Reduction. All 4 of these processes are naturally present in the flame you see burning off a match. Gasification is merely the technology to pull apart and isolate these separate processes, so that we might interrupt the fire and pipe the resulting gasses elsewhere. Gasification like choked combustion. Gasification is the operating system of fire

11 Chemical reactions of combustion Through this process, CO 2 is reduced to CO. And H 2 O is reduced to H 2 and CO. Combustion products become fuel gasses again. And those fuel gasses can then be piped off to do desired work elsewhere.

12 Gas quality and application fields The gas produced by gasification of biomass called a medium-quality gas, calorific (heating) value is within MJ/m 3. This gas may be used directly in Otto or Diesel engines, it may be used to drive heat pump compressor or alternatively, it may be upgraded to pipe-line quality gas (about 30 MJ/m 3 ) or converted to methanol.

13 Pyrolysis For pyrolysis solid biomasses are treated exclusively by the use of thermal energy with the goal to maximize the share of liquid products. Pyrolysis is dry distillation or retorting or cracking. As the equivalence ratio (excess air) below 0,1 the gasification process is called pyrolysis. Only a modest fraction of the biomass energy is found in the gaseous product the rest being in char and oil residues.

14 Pyrolysis 2 Biomass begins to fast decompose with once its temperature rises above around 240 C. Typically it takes place at temperatures over 430 C (800 F). Word comes from Greece words pyr fire" and lysis exclusion". Pyrolysis process of wood begin at temperatures C ( F). The biomass breaks down into a combination of solids, liquids and gasses. The solids that remain commonly is called charcoal. The gasses and liquids that are released collectively called tars. Thus in review, pyrolysis is the application of heat to biomass in the absence of air/oxygen. The volatiles in the biomass are evaporated off as tars, and the fixed carbonto-carbon chains are what remains otherwise known as charcoal.

15 Pyrolysis 3 Highest efficiency of process is achieved by using fast (flash) pyrolysis there raw material is heated quickly for less than 2 seconds between ranges 350 up to 500 C (660 and 930 F).

16 Triangle diagram Obtained gaseous, liquid and solid stage relations depending on conditions of pyrolysis.

17 Carbonization Carbonization refers to the thermo-chemical conversion of solid biomass aiming at a maximum output of solid products (charcoal, bio-char). Carbonization is the term used when complex carbonaceous substances such as wood or agricultural residues are broken down by heating into elemental carbon and chemical compounds which may also contain some carbon in their chemical structure.

18 The stages in charcoal formation The three main stages requiring heat inputs in charcoal making are: - The drying of the wood, - Raising the temperature of the oven dry wood to 270 C to start spontaneous pyrolysis which itself liberates heat, - Final heating to around C to drive off tar and increase the fixed carbon to an acceptable figure for good commercial charcoal.

19 Torrefaction or roasting Torrefaction of biomass can be described as a mild form of pyrolysis at temperatures typically ranging between C. During torrefaction the biomass properties are changed to obtain a much better fuel quality for combustion and gasification applications. Torrefaction combined with densification leads to a very energy dense fuel carrier of GJ/ton. Added value of torrefied biomass : Higher energy density, More homogeneous composition, Hydrophobic behavior, Elimination of biological activity, Improved grindability Energy density of GJ/m 3 compared to wood GJ/m 3 driving a 40-50% reduction in transportation costs.

20 Characteristics of solid fuels for comparison

21 Products of thermo-chemical conversion Gas (wood gas) Tars, oils, (bio-oil) Coke (at high temperature, above 1000 C ) Charcoal (barbeque coal, active coal) Bio-char (not finalized pyrolysis product, at C) Carbon fiber diameter 0,005 0,010 mm and contain only carbon atoms. Liquid and gaseous bio fuels (methanol, Fisher-Tropsh-Diesel fuel, bio-sng).

22 Wood gas and wood gasifiers Wood gas - produced by heating of wooden material at temperature over 700 C and absence of air or by dry distillation (pyrolysis) method. Combustible part of wood gas consist of mainly carbon monoxide (CO), hydrogen (H) and methane (CH 4 ). LHV is about 1,25 MWh/1000 m³. From 100 kg wood can get m³ wood gas.

23 Average composition of wood gas Lämmastik - Nitrogen, N % Vingugaas - Carbon monoxide, CO % Vesinik Hydrogen, H 2 : % Süsihappegaas - Carbon dioxide, CO 2-4.5% Metaan Methane, CH 4-3.0% Hapnik Oxygen, O 2-0.6%. Source: Taylor, Charles Fayette (1985). Internal- Combustion Engine in Theory and Practice - Vol.1. Cambridge: The MIT Press. pp ISBN

24 Devices produced wood gas The first device for producing of wood gas was made by Gustav Bischof on year The first car driving on wood gas was built by Thomas Hugh Parker on kg wood can replace petrol (benzine) on normal driving conditions.

25 Imbert gas generator

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27 Stratified down-draft gasifier

28 Self-made wood gas generator and barbeque with gas generator by Estonian engineer

29 Pyrolysis reactor with rotating cone for treatment of wood waste, 250 kg/h. 50 t/d bio-oil. (75% oil, 15% char, 10% losses)

30 Biomass-to-Liquids (BTL) - Concept

31 Slurry lobri, pulp Fast Pyrolysis

32 Slurry with pyrolysis coke Joint grinding of pyrolysis oil and coke gives pumpable/storable slurry. Energy concentration from biomass to slurry by factor 13. Ca. 80% of the energy content of the biomass is contained in the slurry. Crumble lagunema, murenema

33 CHP running on wood gas The wood gasification - a process known for centuries - has practically the only economically attractive option for the simultaneous production of electricity and heat from wood chips in small decentralized system. The Spanner Wood-Power-Plant consists of a gasifier JOOS and a CHP of the company KW Energietechnik. (

34 Spanner Re 2 GmbH Wood-Power-Plant. The special feature of the Joos-carburetor is a small, controlled fire bed. This allows us to produce systems in a power range from kw el and kw th. The system operates using commercial wood chips with a maximum of 30% fine particle and moisture ~15%.

35 Ratings of the wood-power-plant Power range 30 kw electrical 66 kw thermal 40 kw electrical 88 kw thermal 45 kw electrical 100 kw thermal Carburetor assembly Heat output CHP unit Total ca. 10 kw ca. 56 kw ca. 66 kw ca. 12 kw ca. 76 kw ca. 88 kw ca. 15 kw ca. 85 kw ca. 100 kw Wood chips consumption: per 1 kw electrical about about 1 kg per hour.

36 Dimensions of the wood-power-plant. Dimensions Length Width Height Wood-Gasifier + Control cabinet CHP+ Control cabinet 5000 mm mm 1350 mm mm 2300 mm 2250 mm 990 mm 1470 mm

37 Principle of this technology (Bazi) is the fluidization by loop flow between the fluidized bed and pulverized

38 Scheme of present-day wood gas generator

39 Small wood gas generators (CHP) Use wood waste and sawdustable to work off power grids Small wood gas generator fuelled by pellets

40 CHP, capacity 150KWh el and 300KWh th 1 Kg Wood = 1 kwh Electricity + 2 kwh Thermal

41 Urbas Combined Heat & Power (CHP)

42 Wood gas cars before World War II

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44 Van running 100% on gas from coffee grounds

45 Wood logs to fuel vessel

46 Wood logs to fuel vessel

47 Neighbours (Finns) with cars are used renewable fuels

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49 Thank you for your attention!