Biocoal is a type of biofuel that is obtained by thermal processing of biomass. The process occurs in an environment low in oxygen and at temperatures above 500º. This technology is the production of biocoal was developed just a few years ago, but experts are already saying that the new fuel will grow rapidly and will take its place. Compared to pellets, biocoal more calories and not afraid of water. It can long be stored under the open sky. Also the biocoal used in conventional solid fuel boilers, while they do not need to re-equip for this type of fuel.
Biocoal is produced by torrefecation.
The whole process consists of several stages:
– On the first stage, the drying of raw material. To the entire mass went excess moisture, drying takes place in three stages. First the mass of raw materials, when a lot of moisture, it is first removed from the upper layer. In the next stage the rate of removal of moisture drops, and it completely leaves out the inner layers. In the third stage the rate of removal of moisture almost completely falling. Mainly at the stage of drying of raw material is given to the first phase, the remaining moisture will go into subsequent stages of production of biocoal. The drying process influences the thickness of the raw material. It is impossible to achieve uniform drying of all layers so the thinner the mass, the more evenly is the withdrawal of heat.
– In the second stage is the process of torrefecation or mild pyrolysis. Feature a soft pyrolysis in that it takes place in a range of temperatures from 160º to 340º. The temperature of the process depends entirely on the material but should not exceed 500º. Different raw materials have different moisture content initially, so you need parameters it achieves under the influence of different temperatures. Torrefecation starts fast, immediately after the last drying step. It is important to monitor temperature during the exposure time of the raw materials of this temperature. Because the non-observance of these parameters may cause mild pyrolysis can go into the stage of coal combustion. Therefore, the control process is automated. This stage takes place with absorption of heat.
– The third stage stage of coal formation upon deep thermal decomposition of raw materials. At this stage there is a release of heat energy.
– And in the final stages of the resulting coal anneal and at this stage, the absorption of heat.
Torrefecation fuel has several advantages. Coal is made from pure organic raw materials. The product yield after torrefecation is about 75%. It has a high calorific value, especially if used as the raw material straw or grass. Also in the production of coal can lay such process parameters to get a different angle of calorific value. The fuel has a low content of harmful substances, heavy metals and sulfur.
To date, has not yet formed a market for biocoal, due to the fact that it is still a new product. But it has many advantages, in the future he will take his place and will be in demand in the market of solid fuel.