Process and installation for recycling solid unburnt materials in a fluidized bed

Claim 2

Process for supplying with combustible material a fluidized bed combustion installation comprising a vessel (1) having therein a fluidized bed for the combustion of a combustible material producing smoke, conduit means (17) for evacuating said smoke carrying along solid particles containing unburned matter, a device (3) for separating out said solid particles carried along by said smoke, and a circuit (41) for recycling to said fluidized bed said solid particles recovered in said separating device, said process comprising two alternating phases for supplying said fluidized bed with combustible material, viz., (1) a first phase of normal operation in which said fluidized bed is supplied with combustible material at an adjustable flow rate by supply means (21) so as to produce a predetermined temperature in said fluidized bed, and during which said solid particles recovered in said separating device (3) are accumulated in a reverse silo (4), said recycling circuit being closed, and (2) a second periodic recycling phase during which supply from said supply means (21) is halted and said recycling circuit (41) is opened, in order to recycle to said fluidized bed said solid particles accumulated in said reserve silo (4) during said first phase, recycling being so regulated that the combustion of said unburnt matter contained in said solid particles maintains the temperature of said fluidized bed at a desired level, said recycling circuit (41) being closed as soon as said temperature can no longer be maintained at said level, the accumulated particles being removed during a period sufficiently small not to cause a drop in temperature of said fluidized bed below a predetermined limit, whereupon normal first phase operation resumes; (3) an exothermic reaction being maintained alternatively by combustion of said combustible material in said first phase and by combustion of said unburnt matter in said second phase.

Claim 3

Process according to claim 1, wherein said solid particles entrained said smoke during said second phase are accumulated in an intermediate silo interposed between said separating device and said reserve silo.

Claim 4

Process according to claim 1, wherein the temperature of said fluidized bed is measured permanently and recycling of said solid particles is servo-coupled to the temperature of said fluidized bed so as to maintain said temperature at the same level as during said first phase.

Claim 5

Process according to claim 3, wherein detection of a drop in temperature below said desired level determines the stopping of said second phase and resumption of said first phase.

Claim 6

Process according to claim 4, wherein the flow rate of recycling said solid particles is measured continuously, said second phase being terminated and return to said first phase being actuated when said flow rate necessary for the maintainence of said desired temperature level exceeds a predetermined limit.

Claim 7

Process for supplying with combustible material a fluidized bed combustion installation comprising a vessel (1) having therein a fluidized bed for the combustion of a combustible material producing smoke, conduit means (17) for evacuating said smoke carrying along solid particles containing unburned matter, a device (3) for separating out said solid particles carried along by said smoke, and a circuit (41) for recycling to said fluidized bed said solid particles recovered in said separating device, said process comprising two alternating phase for supplying said fluidized bed with combustible material, viz., (1) a first phase of normal operation in which said fluidized bed is supplied with combustible material at an adjustable flow rate by supply means (21) so as to produce a predetermined temperature in said fluidized bed, and during which said solid particles recovered in said separating device (3) are accumulated in a reserve silo (4), said recycling circuit being closed, and (2) a second periodic recycling phase during which supply from said supply means (21) is halted and said recycling circuit (41) is opened, in order to recycle to said fluidized bed said solid particles accumulated in said reserve silo (4) during said first phase, recycling being so regulated that the combustion of said unburnt matter contained in said solid particles maintains the temperature of said fluidized bed at a desired level, said recycling circuit (41) being closed as soon as said temperature can no longer be maintained at said level, the return to normal supply of said fluidized bed with combustible matter and the rapid removal of accumulated particles being actuated simultaneously at the end of said second phase, said rapid removal being stopped before the complete emptying of said silo when the level of the particles in the latter reaches a predetermined limit, whereupon normal first phase operation resumes; (3) an exothermic reaction being maintained alternatively by combustion of said combustible material in said first phase and by combustion of said unburnt matter in said second phase.

Claim 8

Process for supplying with combustible material a fluidized bed combustion installation comprising a vessel (1) having therein a fluidized bed for the combustion of a combustible material producing smoke, conduit means (17) for evacuating said smoke carrying along solid particles containing unburned matter, a device (3) for separating out said solid particles carried along by said smoke, and a circuit (41) for recycling to said fluidized bed said solid particles recovered in said separating device, said process comprising two alternating phase for supplying said fluidized bed with combustible material, viz., (1) a first phase of normal operation in which said fluidized bed is supplied with combustible material at an adjustable flow rate by supply means (21) so as to produce a predetermined temperature in said fluidized bed, and during which said solid particles recovered in said separating device (3) are accumulated in a reserve silo (4), said recycling circuit being closed, and (2) a second periodic recycling phase during which supply from said supply means (21) is halted and said recycling circuit (41) is opened, in order to recycle to said fluidized bed said solid particles accumulated in said reserve silo (4) during said first phase, recycling being so regulated that the combustion of said unburnt matter contained in said solid particles maintains the temperature of said fluidized bed at a desired level, said recycling circuit (41) being closed as soon as said temperature can no longer be maintained at said level, the return to normal supply of said fluidized bed with combustible matter and the rapid removal of accumulated particles being actuated simultaneously at the end of said second phase, said rapid removal being stopped before the complete emptying of said silo when the level of the particles in the latter reaches a predetermined limit, whereupon normal first phase operation resumes; (3) an exothermic reaction being maintained alternatively by combustion of said combustible material in said first phase and by combustion of said unburnt matter in said second phase.

Claim 9

Process for supplying with combustible material a fluidized bed combustion installation comprising a vessel (1) having therein a fluidized bed for the combustion of a combustible material producing smoke, conduit means (17) for evacuating said smoke carrying along solid particles containing unburned matter, a device (3) for separating out said solid particles carried along by said smoke, and a circuit (41) for recycling to said fluidized bed said solid particles recovered in said separating device, said process comprising two alternating phases for supplying said fluidized bed with combustible material, viz., (1) a first phase of normal operation in which said fluidized bed is supplied with combustible material at an adjustable flow rate by supply means (21) so as to produce a predetermined temperature in said fluidized bed, and during which said solid particles recovered in said separating device (3) are accumulated in a reserve silo (4), said recycling circuit being closed, and (2) a second periodic recycling phase during which supply from said supply means (21) is halted and said recycling circuit (41) is opened, in order to recycle to said fluidized bed said solid particles accumulated in said reserve silo (4) during said first phase, recycling being so regulated that the combustion of said unburnt matter contained in said solid particles maintains the temperature of said fluidized bed at a desired level, said recycling circuit (41) being closed as soon as said temperature can no longer be maintained at said level, whereupon normal first phase operation resumes; (3) an exothermic reaction being maintained alternatively by combustion of said combustible material in said first phase and by combustion of said unburnt matter in said second phase; wherein said fluidized bed operates at a pressure higher than atmospheric pressure and is supplied with combustible matter occurring at the same pressure through a lock device, said supply proceeding from a single chamber forming a lock comprising an inlet and an outlet for material, each provided with an isolating valve respectively and pressurizing means and depressurizing means for said supply chamber, previously filled with fuel material, being alternately placed at the pressure of said combustion vessel during said second phase to be placed at atmospheric pressure and filled again with combustible matter.

Claim 10

Process for supplying with combustible material a fluidized bed combustion installation comprising a vessel (1) having therein a fluidized bed for the combustion of a combustible material producing smoke, conduit means (17) for evacuating said smoke carrying along solid particles containing unburned matter, a device (3) for separating out said solid particles carried along by said smoke, and a circuit (41) for recycling to said fluidized bed said solid particles recovered in said separating device, said process comprising two alternating phases for supplying said fluidized bed with combustible material, viz., (1) a first phase of normal operation in which said fluidized bed is supplied with combustible material at an adjustable flow rate by supply means (21) so as to produce a predetermined temperature in said fluidized bed, and during which said solid particles recovered in said separating device (3) are accumulated in a reserve silo (4), said recycling circuit being closed, and (2) a second periodic recycling phase during which supply from said supply means (21) is halted and said recycling circuit (41) is opened, in order to recycle to said fluidized bed said solid particles accumulated in said reserve silo (4) during said first phase, recycling being so regulated that the combustion of said unburnt matter contained in said solid particles maintains the temperature of said fluidized bed at a desired level, said recycling circuit (41) being closed as soon as said temperature can no longer be maintained at said level, whereupon normal first phase operation resumes; (3) an exothermic reaction being maintained alternatively by combustion of said combustible material in said first phase and by combustion of said unburnt matter in said second phase; wherein said fluidized bed operates at a pressure higher than atmospheric pressure and is supplied with combustible matter occurring at the same pressure through a lock device, said supply proceeding from a single chamber forming a lock comprising an inlet and an outlet for material, each provided with an isolating valve respectively and pressurizing means and depressurizing means for said supply chamber, previously filled with fuel material, being alternately placed at the pressure of said combustion vessel during said second phase to be placed at atmospheric pressure and filled again with combustible matter.