Heating by pyrolysis coppers. Pyrolysis of wood waste
Waste from the woodworking enterprises (sawdust, spill, firewood), the enterprises of agricultural production (straw, pod from sunflower etc.) has sufficient heating capacity for extraction of warmth from them for needs of heating.
Burning of this waste in the boiling layer sushchestvlyatsya in solid propellant pyrolysis coppers (gas generators).
Pyrolysis. What is it?
It is process of thermal decomposition of vegetable waste from production at a lack of oxygen. Humidity of the burned vegetable remains can make 50. But for effective work of a gas generator humidity of this fuel is recommended to 15-20.
Receiving generating gas by a pyrolysis method happens as follows:
I stage: decomposition of a gemitsellyuloza (° C t=220-250);
II stage: cellulose decomposition (° C t=280-350);
III stage: decomposition of a lignin (° C t=280-500).
Or that the same, process of gasification on zones:
I zone: drying of wood waste (exit of flying);
II zone: fuel is exposed to a shvelevaniye, i.e. thermal decomposition in current of heated gas (carbon burning out) - an oxygen zone;
III zone: gasification happens already to coal, a wood shvelevaniye product - carbon burning out - a recovery zone: O2=0;
IV zone: slag pillow.
On amount of generating gas humidity of wood waste substantially affects. So, dry spill gives 1,5 nm3/kg gas, and damp 1,8 nm3/kg.
Composition of generating gas, as a rule:
- % CO211,8-12,8;
- % CH41,4-2,4;
- % H216,2-18,5;
- % N247,1-51,3.
1 m3 of generating gas with warmth of combustion of Qn =5040 kJ / нм3 demand 1,13 m3 of air.
Data on receiving generating gas for different wood waste are provided in the following table:
Generating gas is received, as a rule, with flying pitches which hammer a torch at combustion of this gas. Therefore there is a problem on purification of generating gas before burning. It is reached by use of such devices as the condenser where there is a fall of temperature of gas and condensation of pitches - 16-26%, and also a tar stripper centrifugal where centrifugal force for removal of droplets of pitch - 74-84% is used.
In modern pyrolysis coppers (gas generators) the received generating gas directly is burned in a copper, in a fire chamber for needs of heating without preliminary purification of generating gas.