Chinese Method Of Firing Bamboo Charcoal

(1)Dry distillation pyrolysis method: its equipment is mainly external heat vertical dry distillation kettle, this kind of dry distillation kettle can be used in the firing of bamboo charcoal, both pre-dried to the moisture content of 20% to 25% of the bamboo, can also be used without pre-dried bamboo, but the use of pre-dried bamboo is better. Since there is basically no oxidation problem of bamboo charcoal in the firing process, the yield of bamboo charcoal is relatively high, generally about 25%, and the highest can reach 35%, and the firing cycle is generally 48-72 hours. But the refining temperature is not high, which affects the density of bamboo charcoal. The volume of retort is small and the yield of bamboo charcoal is low. Some manufacturers in Zhejiang Province use this vertical retort to fire bamboo charcoal.

(2)(2) earth kiln firing method: it is the direct heating of fuel (wood), that is, the heat generated by fuel combustion at the kiln mouth rises to the top of the kiln and diffuses to the kiln, most of which hot gas flows in the upper layer, a small amount of heat radiates around, slowly drying from top to bottom and reaching pre-carbonization; Burning part of the bamboo in the kiln makes the temperature in the kiln continue to rise and remove volatile substances. At this time, the flue gas in the kiln circulates, the heat and temperature at each point are basically uniform, and the carbonization and refining stages are completed, and bamboo charcoal with dense structure is obtained. The kiln firing method usually has the stages of smoke pre-drying, drying, pre-carbonization, carbonization, calcination (refining), natural cooling, etc. Each stage has different temperatures, the smoke pre-drying stage is 60 ~ 100℃, the drying stage is 100 ~ 150℃, the pre-carbonization stage is 150 ~ 270℃, the carbonization stage is 270 ~ 450℃, and the calcination stage is about 450℃ to 1000℃. From the point of view of the process of kiln charcoal burning, the temperature and carbonization speed of each stage are through the operator's "eyes and noses", one is to observe the change of smoke from the chimney and the kiln door; The second is to smell the smoke to determine. The fresh bamboo used in the earth kiln is generally placed outdoors for about a week, and is smoked and pre-dried in the kiln for about 1 week, while it takes a week to cool naturally to the kiln temperature of 50 ~ 60 ° C, and it generally takes 2 days to leave the kiln. Therefore, it generally takes 25 to 30 days from the kiln to the carbon, and the yield of bamboo charcoal is generally about 20%. The process is reasonable, and the yield is more than 20% if the amount of oxidation and combustion in the later period is small, otherwise it will be lower than 20%, or even lower (because the air leaks into or the amount of air enters too much). The kiln cost is cheap, the refining temperature is high, the density of bamboo charcoal is high, but the quality stability is poor, the yield is not high.