Activated carbon activation is one of the most important steps in the production of activated carbon.
Activated carbon activity is generally divided into four main processes according to the temperature change in the thermal decomposition process:
First: the drying process
The main purpose is to evaporate the moisture contained in the raw materials relying on externally supplied heat. The temperature is controlled at about 150 degrees. The temperature is not high, so the chemical composition of the wood material does not change.
Second: Pre-carbonization process
As the temperature rises to about 275 degrees, the thermal decomposition reaction of wood materials is obvious, and the chemical composition of raw materials begins to change. Among them, unstable components such as hemicellulose decompose to produce carbon dioxide, carbon monoxide and a small amount of acetic acid.
Third: the carbonization process
The carbonization process is the most important part of activated carbon carbonization, and the temperature reaches about 400 degrees, so it is also called the exothermic reaction stage. The raw materials undergo thermal decomposition rapidly, producing large amounts of decomposition products. The generated liquid product contains a large amount of acetic acid, methanol and wood tar, and the carbon dioxide content in the generated gas product gradually decreases, while the flammable gases such as methane and ethylene gradually increase.
Fourth: the calcination process
In this process, the temperature reaches 500 degrees and the charcoal is calcined by external heat supply. At this time, the liquid product is very small, and the volatile substances remaining in the charcoal are discharged and the fixed carbon content of the charcoal is increased