Waste incineration does not necessarily produce dioxin.
The main reasons for waste incineration to produce dioxin are as follows:
1, in the incineration process of chlorinated plastics such as vinyl chloride, incineration temperature is lower than 800 ° C, chlorinated garbage incomplete combustion, it is very easy to generate dioxin. After combustion to form chlorobenzene, the latter becomes the precursor of dioxin synthesis;
2, other chlorine-containing, carbon-containing substances such as paper, wood products, food scraps, etc. through the catalytic effect of copper, cobalt and other metal ions without chlorobenzene to generate dioxin.
But with the development of science and technology, the waste incineration system has been perfected.
"Controlled gas pyrolysis incinerator" incineration process is divided into two combustion chambers, a combustion chamber for thermal decomposition of garbage temperature control for 700 ℃ or less, so that the garbage in the absence of oxygen state of low-temperature decomposition, when the metal Cu, Fe, Al, and other metal elements will not be oxidized, which will greatly reduce the amount of dioxin;
At the same time, because the amount of HCl generated due to anoxic combustion will be reduced; and it is difficult to generate a large number of reducing atmosphere. Because the gas-controlled waste incinerator is a solid bed, so there will be no soot, there will be no unburned residual carbon into the second combustion chamber. The combustible components in the garbage are decomposed into combustible gases and introduced into the second combustion chamber with sufficient oxygen for combustion.
The temperature of the second combustion chamber is about 1000℃ and the length of the flue enables the flue gas to stay for more than 2s, which ensures that the dioxin and other toxic organic gases are completely decomposed and burned under high temperature. In addition, the use of bag filter to avoid the use of electrostatic precipitator Cu, Ni, Fe particles on the generation of dioxin catalytic effect.
Expanded Information: Extended Information:
Atmospheric sources of dioxins:
Steel smelting, non-ferrous metal smelting. automobile exhaust, incineration of inadequate production (including pharmaceutical wastewater incineration, chemical plant waste incineration, household waste incineration, coal-fired power plants, etc.).
Leaded gasoline, coal, preservative-treated wood and petroleum products, a variety of wastes, especially medical waste at a combustion temperature of less than 300-400 ° C in the easy generation of dioxins. Polyvinyl chloride plastic, paper, chlorine and some pesticides in the production chain, steel smelting, catalysts, high temperature chlorine activation and other processes can be released into the environment dioxin.
Dioxin is also present as an impurity in some pesticide products such as pentachlorophenol, 2,4,5-T, and so on.
Baidu Encyclopedia - Dioxin
Baidu Encyclopedia - Waste Incineration (Controlled Emissions)