When the rotary kiln is used to treat industrial hazardous waste, coking will occur. There are two main forms of coking. The infiltration of air or water evaporation cooling water leads to localized coking. Regardless of the type of coke, its formation principle is produced during the incineration of industrial hazardous waste. Specifically, the hazardous waste is decomposed at high temperature, and the elements produced are recombined together, and finally some low-melting point salts are formed. class of substances.

Generally speaking, the composition of the waste produced in the industrial production process is relatively complex, and there are many types of salt and other low-melting point substances in it. These hazardous wastes form molten and semi-molten states when incinerated. Coking on the inner wall of hazardous waste incineration is a relatively common phenomenon. The temperature at the center of the furnace flame is relatively high, and the fuel ash is mostly in the form of melting. The reason why slagging occurs is mainly due to the constituent elements of ash and the melting point

characteristics of each constituent. Industrial waste will form slagging after incineration, mainly due to the formation of ash layer and the increase of the amount of inert gas, and the oxidant enters into the material and reacts with combustibles. The temperature at this time is lower than that in the incineration section, and the next step will be the burnout stage until the remaining waste is burned out. Generally speaking, the temperature at the center of the rotary kiln incineration chamber can reach 1100°C, and the fuel ash is in a molten state; the temperature of the surrounding wall smoke is relatively low, if the ash particles in the flue gas still appear viscous when they touch the wall Or in a molten state, it will gradually adhere to the pipe wall and form a relatively compact layer of ash.

It is very important to understand the characteristics of formation of low molten salt, etc., for controlling the coking formed by low molten salt bonding. Generally, the ash and slag characteristics of waste can be determined by elemental analysis of waste. In the process of waste incineration, the composition of salt substances will be changed due to the combination with other elements, and they will recombine with other components to form new components. A typical example is the combination of alkaline components (sodium, potassium) and halides (chlorine, fluorine). Most of the waste to be treated contains chlorine or fluorine, and low melting salts are formed when other wastes to be treated contain sodium or potassium. Typical sodium salt (NaCl), the melting point of a single component is 800°C. By chemically combining sodium and chlorine it becomes very viscous, it sticks to itself and sticks to other substances. Once a large lump or oblong is formed, it binds more other substances. The sticky material may not be fully decomposed by incineration until it is completely covered. They fall into the ash handling system and can become clogged.

The reason why the coking phenomenon occurs in the rotary kiln incinerator is not a complete overview. In fact, it is caused by many factors, such as the type of combustion furnace, the aerodynamic field in the furnace, and the layout and structural characteristics of the burner. Initiating coking phenomenon, even the size, specification and type of industrial hazardous waste are also important factors affecting coking in the furnace. In practice, when ensuring the effective mixing of fuel and air (oxygen), care should also be taken to avoid the formation of reducing spaces around the inner wall of the furnace. Reasonable use of air power in the furnace can effectively prevent the occurrence of coking in the rotary kiln boiler