Pyrolysis equipment offers new hope and solutions for municipal solid waste MSW treatment. It can turn waste into treasure - pyrolysis oil, syngas, and carbon black.
Pyrolysis plant offers significant environmental benefits and resource recovery potential, demonstrating unique value in addressing the increasingly challenging challenges of municipal solid waste. They not only effectively reduce the environmental pollution associated with traditional treatment methods but also lower the emission of harmful gases, such as dioxins.
Municipal Solid Waste Pyrolysis Principle
Municipal solid waste pyrolysis is the process of heating solid waste in an oxygen-free or oxygen-deficient environment to induce decomposition reactions within the organic matter. This MSW pyrolysis process involves a complex series of chemical reactions, primarily cracking, condensation, and recombination.
Cracking is the foundation of the pyrolysis process. Under the action of heat, the chemical bonds of large organic molecules in the solid waste break down, breaking them down into smaller molecules. Condensation, in contrast to cracking, is the process where small molecules recombine to form larger molecules. These larger molecules may have different chemical structures and properties. Recombination involves the rearrangement of atoms within molecules to form new compounds.
Turn Waste into Treasure Process
The turn waste into treasure pyrolysis process involves several key steps, including waste pretreatment, pyrolysis incineration, and exhaust gas treatment. Each step is closely linked to ensure the efficiency, environmental friendliness, and resource utilization of the solid waste pyrolysis process.
Municipal Solid Waste Pretreatment
During the waste pretreatment stage, collected municipal solid waste must first be carefully sorted. This is because different types of waste vary significantly in composition and properties, and sorting facilitates targeted treatment. For example, waste paper, plastics, metals, glass, kitchen waste, and hazardous waste should be separated. This prevents interference between different materials during the pyrolysis process, which could affect the pyrolysis effect and product quality.
Pyrolysis of Municipal Solid Waste
Pyrolysis is the core step in the entire process of turning waste into treasure. Pre-treated waste is fed into a pyrolysis reactor and heated in an oxygen-free or anoxic environment. Strictly controlling the pyrolysis temperature and oxygen content is crucial to ensuring the pyrolysis reaction proceeds as intended.
Different types of waste require different pyrolysis temperatures. For example, lower temperatures may be sufficient for highly volatile organic compounds, while higher temperatures are required for more difficult-to-degrade materials.
During the municipal solid waste pyrolysis process, the organic matter in the waste decomposes to produce products, including pyrolysis oil, syngas and carbon black.
Syngas primarily consists of carbon monoxide (CO), hydrogen (H₂), and methane (CH₄). These gases have high calorific value and can be used as fuel for power generation and heating. Pyrolysis oil is a complex organic mixture that, after further distillation refining, can be used as fuel oil. The solid carbon black can be used to make adsorbents, soil conditioners, and other products.
Exhaust Gas Treatment
The pyrolysis process of MSW produces exhaust gas, which may contain pollutants such as incompletely reacted organic matter, dust, sulfides, and nitrogen oxides. Direct discharge would cause serious atmospheric pollution. Therefore, MSW pyrolysis plant must equip with exhaust gas treatment system.
Exhaust gas treatment begins with dust removal. Cyclone separators, bag filters, and other equipment remove dust particles from the exhaust gas, making it cleaner. Next, desulfurization treatment is performed. Absorbents such as lime milk and ammonia react with sulfides in the exhaust gas, converting them into solid or liquid sulfates, thereby reducing the sulfur content in the exhaust gas. Denitrification treatment utilizes technologies such as selective catalytic reduction (SCR) or selective non-catalytic reduction (SNCR) to convert nitrogen oxides in the exhaust gas into nitrogen and water, reducing their environmental impact.
After these treatment steps, the pollutant content in the exhaust gas is significantly reduced, meeting national emission standards before discharge into the atmosphere.
