US 7,878,131 B2Granted

Integrated process for waste treatment by pyrolysis and related plant

AssigneeBEG S.p.A.

InventorsFrancesco Becchetti, Franz-Eicke Von Christen

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Abstract

Process for solid waste treatment, and particularly municipal solid waste, with recovery of the thermal energy, which is based on the general pyrolysis process modified in order to improve, on the one hand, the energy yield and, on the other, to reduce the quantity of unusable solid residues to be sent to the waste disposal, the unusable solid waste being limited to 10-15% of the total weight of the initial residue. The process and relative plant include a boosted treatment of the incoming waste, with a preliminary separation into three solid fractions, the first one of which is separately subjected to a preliminary drying step and the third one undergoes further shredding. The process and relative plant also include a section for recovering energy from the pyrolysis coke, wherein the latter is subjected to a thermochemical treatment with the production of a further quantity of synthesis gas.

Claims19

Dependent claims

A process for the treatment, by pyrolysis, of solid waste made up at least in part of municipal solid waste, wherein the waste to be treated undergoes a pyrolysis stage inside one or more rotary drum reactors with the production of a pyrolysis gas stream and a carbonaceous solid residue essentially composed of pyrolysis coke, characterized by the fact that the waste to be treated is preliminarily separated into three fractions, the first one of which, of smaller particle size and greater moisture contents, is subjected to a preliminary drying step in one or more rotary drum driers before being fed—together with the other waste fractions—to the pyrolysis stage, and by the fact that the carbonaceous solid waste obtained from the pyrolysis stage is further subjected to a gasification step to recover a further synthesis gas fraction, which is subsequently added to the pyrolysis gas stream to be fed to an energy recovery stage with the production of thermal energy, the solid residue of the gasification step substantially representing the final waste matter of the entire process,

wherein the three fractions include, besides the first fraction of smaller particle size and greater moisture contents and a second dry fraction of larger particle size than the first one, also a third fraction, dry and of even coarser size than the second one, which is subjected to a preliminary shredding step to homogenize its size to the second fraction before being fed, together with the other waste fractions, to the pyrolysis stage.

Dependencies are inferred from the claim text.