Chinese waste incinerators typically avoid the high-temperature, high-oxygen "incineration" process for low-temperature pyrolysis. Instead, they achieve low-temperature pyrolysis (typically below 500°C or 932°F) by using inert gases (such as nitrogen) in specialized pyrolysis reactors to prevent combustion and promote thermal decomposition of the waste. This process focuses on optimizing parameters such as reaction temperature, time, and an oxygen-free environment to avoid dioxin formation in the presence of oxygen and catalysts. PRC Fireprint's low-temperature magnetic carbonization and pyrolysis technology for harmless treatment of municipal solid waste uses a controlled temperature range of 50-280°C, making it more environmentally friendly.
The following is a detailed explanation of its operating principle:
Inert Gas:
A key aspect of low-temperature pyrolysis is the absence of oxygen. Waste material is fed into a sealed reactor, and a carrier gas (typically nitrogen) is used to maintain the inert atmosphere. This prevents oxidation and allows for the controlled thermal decomposition of organic matter into simpler components, such as gases and oils.
Temperature Control:
Compared to traditional incineration, this process operates at a specific lower temperature (e.g., below 500°C). Researchers aim to find the optimal temperature for degrading pollutants like dioxins while minimizing the formation of new ones.
Reaction Parameter Optimization:
In addition to temperature, factors such as reaction time and the presence or absence of specific gases are carefully controlled. This involves manipulating the interaction between the waste and gaseous components to promote desired reactions and inhibit undesirable reactions, such as the de novo synthesis of dioxins.
Focusing on Dioxin Prevention:
The goal of low-temperature pyrolysis is generally to degrade existing dioxins and prevent their formation. By controlling the atmosphere to maintain an inert atmosphere and operating at a specific temperature, the process can achieve high dioxin degradation efficiencies (e.g., exceeding 99.7%) while preventing dioxin re-formation.
Reactor Design:
Specialized pyrolysis reactors, such as fixed-bed or fluidized-bed reactors, are designed to process specific waste materials and maintain the inert atmosphere and temperature required for efficient decomposition.
