wide range of various woodbased fuels are burned. To some extent also straw and other biomass based fuels are used. All these fuels are considered as renewables and according to the international agreement the CO2 emitted by the combustion of these fuels is not listed as a greenhouse gas. Wood, in particular the shell of wood cells, consists mainly from cellulose, lignin and hemicellulose. Due to the high carbon and hydrogen content, the lignin has higher calorific value than cellulose and hemicellulose. In smaller quantities the wood contains also tar, resins and phenols that can cause fouling of heat transfer surfaces and stack interior with the deposits that are difficult to remove From the point of view of combustion technology and practical use of fuels the following properties of fuels are of most interest: chemical composition, moisture, density, fly and bottom ash content, ash melting characteristics and content of
Stem Branches Leaves Silver birch • The stock of silver birch (Betula pendula) was 119 millions m³ • The annual mean increment of Estonian silver birch stands is 5.0 m³ per hectare • The mean average volume is 182 m³ per hectare Energy • There are different ways of getting the energy out of a wood: –Traditional burning –The gasification of wood The calorific values • The calorific values, in terms of 20% of moisture regain: alder – 700 kWh/ton birch – 1500 kWh/ton Wood gas • Wood gas is produced by heating biomass (wood) in a temperature over 700°C without air access or in a method of pyrolysis. Wood gas consists of carbon dioxide, methane and carbon monoxide. The calorific value of wood gas is approximately 1,25 MWh/1000 m³ wood. 34...40 m³ of wood gas can be produced out of a 100 kg of wood
2 115 138 600 625 3 160 192 870 940 4 190 228 1150 1250 6 260 312 1600 1875 10 400 480 2500 3125 16 560 670 3600 4200 Fuel properties and prices Net calorific value Fuel (alumine kütteväärtus) Price estimation Biomass (wood chips) 0.75 MWh/m3 loose 11 /m3 loose Sod peat 11.9 MJ/kg 34 /t Light fuel oil 36.1 MJ/dm3 570 /m3 Natural gas 33.4 MJ/m3 n 310 /1000 m3 n NB! Data on boilers and fuels might be corrected if you
dega seotud tööstusharudest saadavate produktide, jäätmete ja jääkide aga ka tööstuslike ja olmejäätmete biolagunev osa. Puit ja puitkütused on üks osa biomassist ja biokütustest. Uuringud näitavad, et metsad on mõjutanud meie planeedi kliimat palju rohkem, kui seni arvati, ning nad mängivad üldse kliimamuutustes põhilist osa. Tarbimisaine ülemine kütteväärtus (ingl k. gross calorific value) Tarbimisaine ülemine kütteväärtus (TÜK) on soojushulk, mis vabaneb ühe ühiku kütuse täielikul põlemisel hapnikus ja kui põlemisel tekkinud veeaur kondenseerub veeks. TÜK sisaldab veeauru kondenseerumissoojust ja on seega sõltumatu kütuse niiskusest. Tarbimisaine alumine kütteväärtus (ingl k. net calorific value) Tarbimisaine alumine kütteväärtus (TAK) on soojushulk, mis vabaneb ühe ühiku kü-
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