The primary purpose of solid waste pyrolysis is to achieve harmless disposal. It is a thermochemical conversion technology. Pyrolysis of solid waste uses heat in the absence or absence of oxygen to break down organic matter into storable fuels (pyrolysis oil, syngas) and a solid residue (carbon black/biochar). This is fundamentally different from incineration (oxygen combustion).
The solid waste pyrolysis process differs fundamentally from incineration. Incineration requires ample oxygen to ensure complete combustion of the material. Pyrolysis, however, requires little or no oxygen, resulting in either no combustion or only partial combustion.
Pyrolysis equipment uses indirect heating to provide the heat required for the pyrolysis process when processing solid waste (tires, plastics).
The products of solid waste pyrolysis and incineration are significantly different. Incineration produces large amounts of flue gas, which is difficult to handle and poses serious environmental risks. Incineration has no other means of utilizing the sensible heat. However, the combustible gases and oils produced by pyrolysis can be recycled in various ways, offering high energy recovery and minimal environmental pollution.
Organic Solid Waste Pyrolysis Treatment
Pyrolysis treatment is suitable for organic solid waste with a certain calorific value. The Pyrolysis Of Solid Waste can process a variety of materials, including municipal solid waste, oil sludge, industrial waste such as plastics, rubber, and tires, and agricultural waste such as crop straw and livestock manure.
The organic solid waste pyrolysis is a complex, continuous chemical reaction process. It involves complex reactions such as bond breaking and isomerization.
During the pyrolysis process, intermediate products undergo two transformations: One is a cracking process, from large molecules to small molecules and ultimately to gases. The other is a polymerization process, from small molecules to larger molecules.
Typically, the pyrolysis process of organic matter begins with dehydration, followed by demethylation. The water produced in the first reaction reacts with the methine groups in the bridging moiety of the second reaction product. Further increasing the temperature, the aromatic compounds produced in these reactions undergo further cracking, dehydrogenation, condensation, and hydrogenation.
Waste Pyrolysis Products
Pyrolysis plant can store the heat stored in solid waste in the form of combustible gas, oil, solid charcoal, etc. Thus, solid waste is converted into valuable fuel that can be stored and transported. Pyrolysis products occur in three forms: gas, liquid, and solid. Pyrolysis products vary significantly depending on the type of waste and the pyrolysis reaction conditions.
The temperature range of the pyrolysis reactor’s heat-absorbing reduction zone is 320°C-540°C, with carbon black as the primary pyrolysis product.
The temperature range of the heat-releasing oxidation zone is 760°C-1150°C, with heavy oil-like substances as the primary pyrolysis product. High-temperature pyrolysis should be above 1000°C, with gas as the primary pyrolysis product. The pyrolysis gas products can be condensed and separated to obtain fuel oil and fuel gas.
Pyrolysis Gas Purification
The purification of pyrolysis gas products should include cooling, dust removal, and deacidification.
Depending on the required heat energy utilization, the cooling method for pyrolysis gas products can be either waste heat recovery or direct spray cooling.
Bag filters should be used as dust collectors. Deacidification systems can utilize spray drying, fluidized bed deacidification, or wet deacidification processes, depending on the needs.
