Drying stage
from the beginning of ignition until the furnace temperature rises to 160℃, the moisture contained in the mechanism rod is evaporated mainly by the added heat and the heat generated by the combustion itself.the chemical composition of the rods has barely changed.
Initial carbonization stage
at this stage, heat is generated mainly by the combustion of the rod itself, so that the furnace temperature rises to between 160 and 280℃.at this time, the wood material thermal decomposition reaction, its composition began to change.the unstable components, such as hemicellulose, decompose into CO2, CO and a small amount of acetic acid.
Full carbonization stage
the temperature at this stage ranges from 300 to 650℃.
at this stage, the wood material is rapidly thermally decomposed, and large quantities of liquid products such as acetic acid, methanol and wood tar are generated.in addition, flammable gases such as methane and ethylene are produced, which are burned in the furnace.Thermal decomposition and gas combustion produce a lot of heat, so that the furnace temperature rises, wood materials at high temperature dry distillation into charcoal.
If you want to calcination high temperature carbon, in addition to the above three stages, we also want to increase the heat, so that the temperature in the furnace continues to rise to about 800℃ ~ 1000℃, so that it can discharge the volatile substances remaining in the charcoal, improve the carbon content in charcoal, so that the graphite structure of carbon increases, enhance electrical conductivity.
Carbonization is an important part of the mechanism of charcoal.Carbonization process is the core of mechanism charcoal production technology.It's like building a building.the good stuff is the base of the building is the underground part.in the carbonization process, the carbonization technology is the above-ground part of the building.Carbonization by low temperature discharge temperature, high temperature calcination, cooling cooling three stages.the rod in the carbonization furnace with about 8% water, these water is the enemy of carbonization.Because the mechanism is most afraid of moisture, moisture in the rod will seriously affect the quality of carbonization.Therefore, drainage time is essential.the drainage time is generally 10-15 hours for earth kilns and 2-3.5 hours for mechanized kilns. A long heating time can prevent the shaft from cracking due to moisture and ensure the quality of carbonization.When the temperature of the furnace rises to 300 degrees, a large amount of combustible gas can be produced in the furnace.Each catty of raw material can produce three cubic meters of methane gas.these gases heat up the furnace.Discharge available for drying heat source above 400 degrees for heat preservation calcination stage need to be sealed without oxygen closed fire can be taken spontaneous combustion cooling or water cooling cooling.Charcoal kiln after the first ventilation out of carbon, to prevent carbon dioxide poisoning.the charcoal out of the kiln should be placed outdoors for more than 8 hours.to prevent the resurgence of fire.
to sum up, we in the whole process of burning charcoal, all the time and not dealing with heat, that is to say, we need to consume a part of the energy to improve the economic value and use of carbon value.
