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US 2026/0210631 A1Published application
Method for calcining carbonated mineral stones in a parallel flow regenerative kiln and implemented kiln
AssigneeS.A. Lhoist Recherche et Developpment
InventorsOlivier Van Cantfort, Tristan Cloarec
Life of this patent
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Abstract
Parallel flow regenerative kiln, comprising at least two shafts (1,2) interconnected by a crossover channel (4) wherein each shaft comprises means for injecting a heated gas (6) inside the shaft (1) in calcination working at the top of the calcination zone (B) and means for removing (21, 23) from the kiln the cooling air which has been heated in contact with the calcined material, at a level lower than the crossover channel (4).
Claims12
Method for calcining carbonated mineral stones in a parallel flow regenerative kiln having at least two shafts interconnected by a crossover channel, comprising, in standard operation,
- loading carbonated mineral stones at the top of each shaft,
- preheating these loaded stones in a preheating zone,
- calcining these preheated stones in a calcination zone with production of a decarbonated calcined material,
- cooling the calcined material with cooling air in a cooling zone, with formation of heated cooling air by heat exchange,
- discharging the calcined material from the bottom of the shafts,
- exhausting a gaseous effluent from the kiln,
- each shaft alternately working in a calcining way and in a preheating way, one shaft working in a calcination way during a predetermined time period during which at least another shaft works in a preheating way, and inversely,
- the calcining way comprising:
- said loading step of carbonated mineral stones at the top of a kiln shaft,
- said calcining step by means of an increase of temperature inside said carbonated mineral stones having been preheated, with production of said decarbonated calcined material and release of a gaseous stream which flows in co-current with the calcined material, and
- through said crossover channel, a passage of said gaseous stream toward the at least one shaft working in a preheating way,
- said preheating way comprising:
- said preheating step of the loaded carbonated mineral stones by heat exchange with said gaseous stream coming from the crossover channel, which is ascending and flows in counter-current through the loaded carbonated mineral stones, and
- said exhausting step of said gaseous stream as gaseous effluent at the top of said at least one shaft in preheating way,
- said cooling step comprising a supply of cooling air at the bottom of each of said shafts or only of the shaft working in the calcining way,
- characterized in that said method further comprises
- recirculating a fraction of the gaseous effluent exhausted from the top of said at least one shaft in preheating way,
- outside the kiln, heating said recirculated fraction of gaseous effluent by means of at least one device able to heat gas,
- injecting the heated fraction of recirculated gaseous effluent into the shaft working in calcining way at a level which is located at the top of the calcination zone, in order to obtain said increase of temperature allowing a calcining of the carbonated mineral stones, and
- extracting the heated cooling air from each shaft wherein cooling air has been supplied at a level located below the crossover channel, the gaseous effluent exiting from the kiln being CO2 concentrated.
17 more elements
Parallel flow regenerative kiln, comprising at least two shafts (1,2) interconnected by a crossover channel (4),
- each shaft comprising, in position in service or out of service,
- at least one entrance opening (5) for loading carbonated mineral stones, at the top of the shaft,
- at least one exit opening (11) for discharging a decarbonated calcined material, at the bottom of the shaft,
- a removal duct (13) for exhausting a CO2 based gaseous effluent from the top of the shaft, and
- a cooling air supply (8) at the bottom of the shaft for cooling the decarbonated calcined material to be discharged,
- the kiln further comprising a reversing system (15) which is arranged to drive said positions in service and out of service of each shaft alternately in calcination working and in preheating working, a shaft (1) being in calcination working during a predetermined time period while at least another shaft (2) is in preheating working and inversely according to the control of said reversing system (15),
- the shaft (1) in calcining working comprising from the top to the bottom successively a preheating zone (A), a calcination zone (B) and a cooling zone (C), and said interconnecting crossover channel (4) being located at the bottom of the calcination zone (B),
- characterized in that each shaft comprises means for injecting a heated gas (6) inside the shaft (1) in calcination working at the top of the calcination zone (B) and means for removing (21, 23) from the kiln the cooling air which has been heated in contact with the calcined material, at a level lower than the crossover channel (4),
- and in that the kiln further comprises an external recirculation circuit (17) which comprises
- a separation body (16) for taking off a fraction of said gaseous effluent from said removal duct (13),
- a heating device (19) able to heat a gas which is connected with said separation body (16) and arranged for heating said fraction of gaseous effluent, and
- said means for injecting a heated gas (6) inside the shaft (1) in calcination working, which are connected to the heating device (19) and inject said heated fraction of gaseous effluent at a temperature equal or higher than the temperature of calcination of the loaded mineral stones.
9 more elements
Dependencies are inferred from the claim text.