Presentation on theme: "Halex3 Kft Burning of wood Heating value of wood Water content (%) Heating value (MJ/kg) Heating value (kWh/kg)"— Presentation transcript:
Halex3 Kft Burning of wood Heating value of wood Water content (%) Heating value (MJ/kg) Heating value (kWh/kg)
Burning of wood Phases of the burning 1.Drying process (until 150°C) In this phase wood shrinks due to heat transmission, wood splits that accelerates the drying process. The higher the water content of the wood is, the more heat has to be transmitted.
Burning of wood Phases of the burning 1.Gasification process After drying and during pirolysis the components of wood become liquid and after vaporisation combustible gases arise. About 83% of wood will be combusted to gases, the rest is the wood ash.
Burning of wood Phases of the burning 1.Burning out phase (500- 1300°C) In the third phase the produced gases react with the oxygen content of air and burn in long, yellow flames. The remaining charcoal smoulders with short, blue flames at about 500-800°C.
Burning of wood Conditions of the effective wood burning: 1.Low water content 2.Adequate, stable furnace chamber temperature 3.Enough (primer and secondary) air for the perfect burning (oxidation) 4.Adequate mixture of wood gases and oxygen 5.Adequate large size of the furnace chamber for the burning out process 6.A well-formed heat exchanger surface for the heat transfer (low temperature of smoke gases)
Relative indexes of different fuels Fuel denomination Heating value (MJ) Cost (HUF/kg, m 3 ) Relative investment Price scale in comparison with natural gas, LPG, or light heating oil (%) Herbaceous bale Herbaceous pellet Arboreal wood chips Arboreal pellet Natural gas34.1822.42.433755896 LPG421804.24.219433353 Light heating oil361403.83.821473761 Herbaceous cereal bale 14.5120.80.8 Extrapolated to 1 MW output: Fuel: Herbaceous pellet Used fuel: 280 kg/h; 4m 3 /d; 500t/y 3000 h operation Herbaceous pellet*16.5301.81.8 Arboreal wood chips12.5181.51.5 Arboreal pellet*15.5352.32.3 *Brickets have similar parameters
Amount of herbaceous plants’ by-products used as fuel (at harvest time) Cereals1.5-3.5 t/haequals29-50 GJ/ha Maize shoots3.5-5.5 t/haequals50-75 GJ/ha Sunflower shoots1.9-3.5 t/haequals25-45 GJ/ha Rape straw3.0-4.0 t/haequals45-65 GJ/ha Mischatus7-15 t/haequals120-260 GJ/ha Sugar sorghum20-25 t/haequals250-350 GJ/ha Energy hemp15-17 t/haequals150-230 GJ/ha Amount of energy crops’ main products used as fuel (at harvest time)