Patent FR-2863920-A1 (FR)
Title: Treating and valorizing flow of waste involves gasification phase using superheated steam
Inventor: CANTEGRIL MARC
IPC: C10J1/213
Filed: 2003-12-19
Abstract: The gasification phase has a first step of pyrolysis supplying at its outlet pyrolysis gases (103) and carbonated solid materials (101, 102), followed by a gasification of the solid amterials and pyrolysis gases to supply at the outlet a purified gas (GE) which can be stored with the intention of energetic valorisation : The gasification stage includes the channelling and injection of the solid materials and the pyrolysis gases in a dense fluidised bed furnace (301), with the pyrolysis gases forming the means (305) of fluidisation in the furnace. The process includes a stage of crushing the carbonated solid materials after pyrolysis so only fine materials (102) pass to the gasification stage. The refuse from the crusher (103) is calcinated or burned, sorted and the carbonated fraction reinjected into the pyrolysis furnace. The pyrolysis gases are used as the means of pneumatic transport for the fine solid materials from the pyrolysis stage to the dense fluidised bed furnace. The pyrolysis gases are blown by a steam jet (104) to form a flow of steam and pyrolysis gases (105) and a rotating gate (106) is used to allow the fine solid materials to be transported. The steam flow (V) is generated internally using a cooler (501) for the process gases (GP) supplied from the outlet from the dense fluidised bed furnace. A separation stage separates the solid material from the flow of steam and pyrolysis gas which carried them to a cyclonic device (302) to be injected into the dense fluidised bed furnace. The pyrolysis gas (GV) is heated using a heat exchanger (303) before injection as the means of fluidisation. The purified gas and other gases and/or exhaust generated by the process are recycled in a post-combustion chamber (304) to supply at its outlet high temperature exhaust (FF) for use as a heating flow in the pyrolysis stage to dry and pyrolyse the flow of waste (FxE) entering the pyrolysis stage. The high temperature exhausts are also used as a heating flow in the exchanger. The solid residues (SI) form the fluidised bed furnace undergo combustion using a circulating fluidized bed furnace (306). The combustion temperature of the circulating fluidized bed furnace is controlled to allow sand to be recovered in suspension in the exhaust and reinjected into the dense fluidized bed furnace. The exhaust from the post-combustion chamber is treated and cooled in a heat exchanger (401) using ambient air as the cooling fluid. The heated air is recycled at least in part as combustion air in the circulating fluidised bed furnace. The process includes an integrated mechano-biological treatment and composting of the industrial and/or household waste and/or biomass to supply the combustible material from the waste CDD), by separating the fermentable materials, crushing and sorting the valorisable materials, inert materials and unburnable materials to provide a stock of combustible materials of constant quality to form the inlet flow of waste (FxE) to the pyrolysis stage. These combustible materials are formed into briquettes by compression. An independent claim is made for an installation to carry out the above process.