Process and installation for pyrolysis of a product in the form of divided solids, in particular polymer waste

Abstract

An installation for pyrolyzing divided solids, such as waste plastics, rubbers, or elastomers. The installation has a device for making divided solids suitable for facilitating pyrolysis by a pyrolysis reactor. The reactor inlet is leak-tightly connected to the preconditioning device and has at least one heating transfer member for transferring the divided solids within the reactor while also pyrolyzing the solids. The member is a conveyor screw or a vibrating tube, and being made of a material that is associated with means for heating it by the Joule effect. The preconditioning device includes liquefaction means for bringing the substance to the outlet of the preconditioning device in a liquid state at an outlet temperature, and a regulator for regulating the temperature of the substance at the outlet from the preconditioning device as a function of a temperature representative of an inlet temperature of the reactor.

1 . An installation for pyrolyzing a substance in the form of divided solids, in particular polymeric waste such as waste plastics, rubbers, or elastomers, the installation comprising:
 a preconditioning device ( 10 ) for preconditioning the substance and for bringing it to a state suitable for facilitating pyrolysis thereof; and   a pyrolysis reactor ( 20 ) having an inlet connected in leaktight manner to the outlet ( 16 ) of the preconditioning device and provided with at least one heating transfer member ( 22 ) for transferring the substance from the inlet to the outlet of the reactor while also pyrolyzing the substance, the member being in the form of a conveyor screw or a vibrating tube, and being made of a material that is associated with means for heating it by the Joule effect;   the installation being characterized in that the preconditioning device includes liquefaction means ( 10 ) for bringing the substance to the outlet of the preconditioning device in a liquid state at an outlet temperature, together with regulator means for regulating the temperature of the substance at the outlet from the preconditioning device as a function of a temperature that is representative of an inlet temperature of the reactor.   
     
     
         2 . An installation according to  claim 1 , wherein the regulator means maintain the outlet temperature of the substance from the extruder at a temperature lower than the inlet temperature of the reactor, with a difference that is less than one hundred and fifty degrees Celsius. 
     
     
         3 . An installation according to  claim 2 , wherein the difference is less than one hundred degrees Celsius. 
     
     
         4 . An installation according to  claim 1 , wherein the liquefaction means comprise a heating extruder. 
     
     
         5 . A method of pyrolyzing a substance in the form of divided solids, in particular polymeric solids such as plastics, rubber, or elastomer waste, the method comprising the following successive steps:
 preconditioning the substance in order to bring it into a state suitable for facilitating pyrolysis thereof; and   pyrolyzing the substance as preconditioned in this way by means of a pyrolysis reactor having an inlet connected in leaktight manner to an outlet of the preconditioning device and provided with at least one heating transfer member for transferring the substance from the inlet to an outlet of the reactor while pyrolyzing the substance, the device being in the form of a rotary tubular screw or a vibrating tube, and being made of material that is associated with means for heating it by the Joule effect;   the method being characterized in that the preconditioning step includes liquefaction suitable for bringing the substance, prior to being introduced into the reactor, into a liquid state at a given outlet temperature, with the outlet temperature being regulated as a function of an inlet temperature of the reactor.   
     
     
         6 . A method according to  claim 5 , wherein the regulation comprises maintaining the outlet temperature of the substance below the inlet temperature of the reactor, with a difference of less than one hundred and fifty degrees Celsius. 
     
     
         7 . A method according to  claim 6 , wherein the difference is less than one hundred degrees Celsius. 
     
     
         8 . A method according to  claim 5 , wherein the liquefaction step comprises hot extrusion.