Thermal decomposition and recycling technology of

From a technical point of view, the implementation of this technology needs to be carried out under high temperature, the investment in the equipment used is much more expensive than the previous recovery methods, the recovery cost is relatively high, and there will be coking in the reaction process, which limits the application of this technology. However, with the enhancement of people's "sense of science and technology", the waste plastic industry will set off a wave of thermal decomposition and recycling technology

working principle

thermal decomposition is to use heat energy to break the chemical bond of the compound under the condition of lack of oxygen. There is a long way to practice the molecular weight fuel gas, liquids (oil, grease, etc.) and coke

technological process

technical features

(1) the use value of decomposition products is high

(2) the number of repeated treatment of waste plastics is not limited

(3) pyrolysis technology can treat mixed recycled products, but it needs to be classified according to chlorine containing products and non chlorine containing products

(1) large investment and high recovery cost

(2) coking in the reaction process

(3) strict technical operation requirements

technical classification

according to the heating method, it is divided into external heating type and internal heating type

according to the operating temperature: there are high-temperature pyrolysis and low walk pyrolysis

according to the products, there are gas production technology and oil production technology

according to the type of pyrolysis furnace, it is divided into rotary furnace, shaft furnace, moving bed and fluidized bed, etc

process influencing factors

different thermal decomposition temperatures lead to different products and yields after thermal decomposition. Even the same product has different physical properties due to different pyrolysis temperatures. With high decomposition temperature, the output of gas increases, and the oil and carbides decrease correspondingly. In addition, with different decomposition temperatures, the composition of the gas also changes. The higher the temperature is, the lower molecular carbides CH4 and H2 in the gas increase

with different thermal decomposition rates, the composition of gas produced is also very different

moisture content

the relationship between moisture content in plastic packaging waste and thermal decomposition is negative. The amount of refined fuel produced by 1t waste varies according to the moisture content. For example, the amount of fuel produced by replacing 1t waste with combustible components has almost no effect on the change of moisture content. However, due to the large moisture content of waste, the thermal balance of pyrolysis is difficult, and a large number of auxiliary fuels are required

in the gasification process, if water steam is injected, water gasification will occur due to water, carbon deposition and CO2. We have also achieved this, reducing the carbon content in the residue and increasing the proportion of H2 and CO in the gas

air content

external thermal pyrolysis is carried out in the absence of oxygen, and the calorific value of the gas produced is high; For internal thermal pyrolysis, due to the introduction of air, the gas product contains a considerable amount of nitrogen and CO2, and the calorific value of the gas is low. The calorific value of the gas product produced by pure oxygen pyrolysis is higher than that produced by air

therefore, from the perspective of actual operation, the difference of this technology in actual operation is still great, and its reflection effect varies with the different equipment and process conditions, which is not as meticulous as the fixtures of Instron, MTS, Zwick and other companies. Its main cracking components are generally liquid oil or gas, but also oil, gas, solid and other products. If the vertical gasifier is used, 58% of the fuel gas can be obtained; If the fluidized bed gasification device is used, 84% of the fuel gas can be obtained