Carbonization and activation are two essential links in the production and processing of activated carbon.
Carbonization is a slow heating process, roughly divided into three stages: the first stage is the drying stage; the second stage is the beginning of pyrolysis stage; the third stage is the carbonization stage, in which polycondensation and decomposition reactions are the main ones.
Activation methods are generally divided into three types, namely gas activation method, chemical drug activation method and chemical and physical activation method. At present, domestic and foreign manufacturers that produce activated carbon using anthracite, bituminous coal and lignite as raw materials generally use gas activation method.
The traditional preparation process of coal-based activated carbon has the following shortcomings: first, the carbonization process and activation process in the traditional process are carried out in independent workshops, and the carbonization and activation time are long, the yield is low, and the overall manufacturing cost is high; second, , The transfer of the required raw materials requires a large amount of machinery or manpower, which is neither economical nor efficient; third, a separate boiler is required to provide the steam required for carbonization and activation; fourth, during the production process, due to the need for combustion A large amount of fuel coal is emitted, and a large amount of harmful gases and dust such as sulfur dioxide and carbon dioxide are emitted, thus causing serious environmental pollution.
There are many types of carbonization furnaces used for activated carbon production, such as vertical moving bed furnaces, earth kilns, pit furnaces, rake furnaces, rotary furnaces, etc. The rotary carbonization furnace is the most widely used carbonization equipment in the production of coal-based activated carbon at home and abroad. It is divided into two types: external heating type and internal heating type rotary carbonization furnace according to different heating methods.
Activation equipment is the core equipment in the production process of coal-based activated carbon. At present, the activation furnaces that are widely used are rake furnaces, Slep furnaces with large production volumes, and rotary activation furnaces with small production volumes. However, the existing rotary activation furnace has the following shortcomings: first, during the normal production process, a constant external heating source is required, and the required fuel consumption is large; second, the production capacity of a single piece of equipment is small, and process control and adjustment are difficult. The stability of product quality is poor; third, the heat resistance of equipment materials is required to be high, and it can only be used to produce charcoal activated carbon, not coal-based activated carbon. Generally speaking, the process conditions of coal-based activated carbon are higher than those of wood-based activated carbon; the process of wood-based activated carbon cannot be used for the production of coal-based activated carbon, while the process of coal-based activated carbon can be used for the production of wood-based activated carbon.
