EP4643067A1 - Procédé de calcination de pierres minérales carbonées dans un four de régénération à flux parallèle et four mis en oeuvre - Google Patents

Procédé de calcination de pierres minérales carbonées dans un four de régénération à flux parallèle et four mis en oeuvre

Info

Publication number
EP4643067A1
EP4643067A1 EP23840990.8A EP23840990A EP4643067A1 EP 4643067 A1 EP4643067 A1 EP 4643067A1 EP 23840990 A EP23840990 A EP 23840990A EP 4643067 A1 EP4643067 A1 EP 4643067A1
Authority
EP
European Patent Office
Prior art keywords
shaft
kiln
gaseous
heated
calcining
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP23840990.8A
Other languages
German (de)
English (en)
Inventor
Olivier VAN CANTFORT
Tristan CLOAREC
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Lhoist Recherche et Developpement SA
Original Assignee
Lhoist Recherche et Developpement SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Lhoist Recherche et Developpement SA filed Critical Lhoist Recherche et Developpement SA
Publication of EP4643067A1 publication Critical patent/EP4643067A1/fr
Pending legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B1/00—Shaft or like vertical or substantially vertical furnaces
    • F27B1/005—Shaft or like vertical or substantially vertical furnaces wherein no smelting of the charge occurs, e.g. calcining or sintering furnaces
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2/00—Lime, magnesia or dolomite
    • C04B2/10—Preheating, burning calcining or cooling
    • C04B2/12—Preheating, burning calcining or cooling in shaft or vertical furnaces
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B1/00—Shaft or like vertical or substantially vertical furnaces
    • F27B1/02—Shaft or like vertical or substantially vertical furnaces with two or more shafts or chambers, e.g. multi-storey
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B1/00—Shaft or like vertical or substantially vertical furnaces
    • F27B1/02—Shaft or like vertical or substantially vertical furnaces with two or more shafts or chambers, e.g. multi-storey
    • F27B1/04—Combinations or arrangements of shafts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B1/00—Shaft or like vertical or substantially vertical furnaces
    • F27B1/08—Shaft or like vertical or substantially vertical furnaces heated otherwise than by solid fuel mixed with charge
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B1/00—Shaft or like vertical or substantially vertical furnaces
    • F27B1/10—Details, accessories or equipment specially adapted for furnaces of these types
    • F27B1/22—Arrangements of heat-exchange apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D17/00—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases
    • F27D17/10—Arrangements for using waste heat
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D17/00—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases
    • F27D17/10—Arrangements for using waste heat
    • F27D17/18—Arrangements for using waste heat for preheating solid materials
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D99/00—Subject matter not provided for in other groups of this subclass
    • F27D99/0001—Heating elements or systems
    • F27D99/0006—Electric heating elements or system
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D99/00—Subject matter not provided for in other groups of this subclass
    • F27D99/0001—Heating elements or systems
    • F27D99/0006—Electric heating elements or system
    • F27D2099/0031—Plasma-torch heating

Definitions

  • the present invention relates to a method for calcining carbonated mineral stones in a parallel flow regenerative kiln (PFRK).
  • PFRK parallel flow regenerative kiln
  • Such a kiln comprises at least two shafts interconnected by means of a crossover channel. In each shaft the stones are introduced in a top portion and follow a downward gravity displacement during which the stones are successively preheated, calcined and thereafter cooled in order to be collected in a low portion of each shaft.
  • stones, carbonated mineral stones, limestone stones pieces of raw carbonated material having a mean particle size d50 comprised between 20 mm to 20 cm, preferably higher than 25 mm, preferably lower than 18 cm, more preferably lower than 16 cm, and typically between 3 and 15 cm.
  • Carbonated mineral according to the present patent application is typically a calcium-magnesium carbonate, also known as limestone.
  • a Parallel Flow Regenerative Kiln has usually 2 to 3 shafts, circular or rectangular, which do not work in a continuous way. In standard operation, in every period, usually of 12 to 20 minutes, a fuel is injected inside a calcining zone of one shaft by means of lances and is burned in presence of combustion air.
  • the descending calcined product is cooled in a cooling zone by heat exchange with a cooling air introduced at the bottom of the shaft.
  • the flue gas consists in the combustion gas, the gas of decarbonation and the heated cooling air.
  • This flue gas is drawn into another shaft through the crossover channel and thereafter through the stones present in this shaft and thereafter outward the kiln. So, in this shaft the present stones are preheated by the exiting flue gas. Consequently, during this period the shaft wherein the combustion takes place works according to a calcining way and the shaft wherein the flue gas is drawn through the stones works according to a preheating way.
  • the classical method for calcining carbonated mineral stones in a parallel flow regenerative kiln having at least two shafts interconnected by a crossover channel comprises, 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, - 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 kil
  • the calcining zone of a classical kiln it is required in calcining way to inject and burn a fuel into the mass of the stones to be calcined under the preheated zone in order to benefit from the heat of the flue gas that was transferred to the stone in the preheating zone.
  • the stones introduced into the kiln are at ambient temperature and the flue gas drawn outside the kiln is at about 150°C, limiting the energy losses.
  • standard operation means that the kiln produces the calcined material in a continuous manner. This operation does not concern the phases of starting, stopping or maintenance of the kiln.
  • carbonated mineral stones particularly mean calcareous stones (limestones), dolomitic stones (dolostones or unburnt dolomites) and/or magnesite stones which are calcined in quicklime, quick dolime and/or magnesia.
  • the calcination reaction of limestone into quicklime is : CaCO 3 (solid) + heat ⁇ CaO (solid)+ CO 2 (gas) This reaction is endothermic and reversible. Below 850-900°C, lime and CO 2 can easily recombine. But from a temperature of the order of 900°C the starting stones give off a significative volume of CO 2 during their decarbonation.
  • the calcined material reactivity can be affected by the fuel ash and the minor pollutants.
  • thermal NOx are also generated due to nitrogen possibly in the fuel and to high contents of nitrogen in the combustion air.
  • This very common calcination process has also the disadvantage of proposing a combustion of fuel with air and a cooling of the calcined product with air. This results in the release at the top of the kiln of a gaseous effluent having a high level of diatomic nitrogen N2, and a comparatively low level of CO2 (concentration by volume of the order of 20% to 27% on dry gas). Due to this high presence of nitrogen in the air, a capture of CO2 is very difficult and expensive.
  • Document EP4015479 discloses a process to reduce CO 2 emission of the cement industry. To reach reduced CO 2 emission, the document contemplates to decarbonize raw material by the use of electrical energy in the calcination device. Document EP4015479 discloses to use in series thermal reactor with growing temperature, where the reactor is heated by electrical energy, either by conduction, convection or radiation.
  • the limestone is heated to a temperature between 650°C-900°C to obtain a partly decarbonized material and CO 2 and then the partly decarbonized material is transferred to a second thermal reactor at a higher temperature with respect to the temperature of the first thermal reactor.
  • this technology can be suitable for cement industry, it is not appropriate for industry where the decarbonation of lime should be controlled to provide suitable properties to the lime, such as lime reactivity, lime t60, low carbonate level in the quicklime obtained, homogenous properties.
  • the method according to EP4015479 relates to crushed or milled limestone and seems poorly adapted to limestone pebble to be decarbonized into quicklime pebble where the properties of the quicklime should be homogeneous through the pebble, with no or very poor over-burned part.
  • the object of the present invention is to remedy at least partially the problem of significant CO 2 emissions of PFRK kilns, without substantially modifying their cyclic functioning and by making little or no changes to their structure.
  • Another object is to avoid as much as possible overheating of the calcined material and introduction of impurities in this material and in the gaseous effluent exiting from the kiln.
  • the main object of the calcination kilns must obviously be maintained, i.e.
  • a method as above indicated 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 a gaseous flow by means of at least one plasma torch, mixing said heated gaseous flow with a control gas which has not been heated by said at least one plasma torch, for controlling the temperature of a first gaseous mixture to inject, said gaseous flow to heat and /or said control gas being a part of the recirculated fraction of gaseous effluent, and injecting said first gaseous mixture 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 higher of its recarbonation temperature.
  • the invention relies mostly on externalizing the energy supply while heating a gaseous flow with a plasma torch, which is a fully electrical solution.
  • the CO2 and other molecules in the heated gas will be partially broken down at high temperature in an electric arc, but mostly recombined in the process.
  • No fuel and no air are still necessary for a combustion inside the kiln. Consequently, no or limited additional pollutant will be emitted apart from the minor ones contained in the stones.
  • No ash will be produced resulting to a pure decarbonated material. Due to the absence or the low level of nitrogen in the gas flows, no or very little NOx will be produced enabling the plants to comply with stricter regulations. Overheating the stones by a direct contact with a flame is not to fear.
  • the appropriate temperature of the heated gas from the plasma torch is controlled very easily by means of the step of mixing, leading to a high quality of lime.
  • the heated recirculated gas is introduced inside the shaft in calcination way at the top of the calcining zone, just below the preheating zone, keeping so all the regenerative features of the kiln.
  • said gaseous flow to heat by at least one plasma torch or the control gas or both of them is a part of the recirculated fraction of the gaseous effluent.
  • said gaseous flow to heat by at least one plasma torch or the control gas is comprised of air, steam, CO 2, N 2, noble gas and their mixtures, particularly issuing from a source which is provided outside the kiln.
  • the system will enrich in CO 2 the gaseous effluent exiting from the kiln, making it easier to capture CO 2 .
  • a CO2 may be useable or sequestered in favorable conditions and so reduces the contribution to the greenhouse effect of the kiln.
  • said cooling step comprises a supply of cooling air at the bottom of each of said shafts or only of the shaft working in the calcining way, the method further comprising an extraction of the heated cooling air from the shafts at a level located below the crossover channel.
  • said gaseous effluent exiting from the kiln being CO 2 concentrated.
  • the gaseous effluent removed from the kiln is formed almost exclusively of the gaseous stream resulting from the decarbonation and of the CO 2 based gas injected in the shaft in calcination way and in the crossover channel.
  • the gaseous effluent exhausted from the furnace has a concentrated CO2 content, typically of at least 80% by volume on dry gas, preferably of at least 90% by volume on dry gas, most preferably at least 95% vol on dry gas.
  • a part of the recirculated fraction of gaseous effluent which has not been heated is injected at the top of each shaft in calcining way.
  • the method comprises an adjustment of the temperature of a portion of the first gaseous mixture to inject by mixing said portion with a part of said recirculated fraction of gaseous effluent which has not been heated by said at least one plasma torch and an injection of this mixture into the crossover channel.
  • the method comprises at least one heat exchange between the extracted heated cooling air and said recirculated fraction of the gaseous effluent.
  • the method takes place in a 2-shafts kiln.
  • each shaft of the kiln further comprises means for injecting a heated gas inside the shaft in calcination working at the top of the calcination zone
  • the kiln further comprising an external recirculation circuit which comprises - a separation body for taking off a fraction of said gaseous effluent from said removal duct, - an external electrical furnace connected with said separation body and equipped with at least one plasma torch for heating a gaseous flow and with a mixing chamber wherein said heated gaseous flow is mixed with a first part of the taken off fraction of gaseous effluent, which has not been heated, while so forming a first mixture to inject under the form of a heated gas, said furnace being so arranged that said gaseous flow to heat and /or said control gas is a part of the recirculated fraction of gaseous effluent, and - said means for injecting a gas inside the shaft in calcination working which are connected to the mixing chamber and inject said first mixture to inject at a temperature equal or
  • the PFRK kiln has a cyclic operation, each shaft operating for a predetermined period of time in calcining way, then, after an inversion time of usually 30 seconds to 2 minutes, in preheating way, and so on.
  • the inversion system synchronously controls all the changes necessary to pass from one way to another, for example by opening means for injecting a gas inside the shaft working in calcination way and closing them when the shaft is switched to the preheating way.
  • the inversion system therefor not only controls numerous flaps and valves, but also the operation of loading and unloading equipment or even that of various suction, pumping or injection elements.
  • the kiln according to the invention has only a few structural modifications made to the exterior.
  • the at least one plasma torch is supplied, as gaseous flow to heat, with said taken off fraction of gaseous effluent by means of said external recirculation circuit.
  • the at least one plasma torch is connected to a source of air, steam, CO 2, N 2, noble gas or their mixtures, as gaseous flow to heat.
  • the mixing chamber (25) is connected with a source (36) of air, steam, CO2, N2, noble gas or their mixtures, as gaseous flow to heat.
  • each shaft comprises a top opening for introducing a part of said taken off fraction of gaseous effluent.
  • said means for removing heated cooling air from the kiln may comprise a central collector element, which communicates with an external extracting device.
  • the kiln according to the invention comprises an additional mixing chamber which is connected to said mixing chamber of the external furnace and means for injecting gas from this additional mixing chamber into the crossover channel, a portion of said mixture to inject from said mixing chamber of the external furnace being mixed in this additional mixing chamber with a part of said taken off fraction of gaseous effluent which has not been heated.
  • each shaft comprises an external shell and said means for injecting a gas inside the shaft comprise at the top of the calcination zone lateral holes in said shell and/or a central perforated cylinder and/or lateral beams, connected to the mixing chamber.
  • a central collector element is provided which communicates with an external extracting device for removing from the kiln, at a level lower than the crossover channel, the cooling air which has been heated in contact with the decarbonated calcined material.
  • each shaft has a circular section and is provided with a peripheral channel at the bottom of the calcination zone, said crossover channel interconnecting the peripheral channels of the shafts in order to allow a passage of gas from one shaft to another one.
  • said means for removing heated cooling air from the kiln may comprise an annular collector which communicates with an external extracting device.
  • each shaft has a rectangular section, a side of one shaft facing a side of another shaft, the crossover channel interconnecting directly the shafts between said facing sides.
  • said means for removing heated cooling air from the kiln comprise on at least some sides of each shaft at least one collector which communicates with an external extracting device.
  • at least one heat exchanger supplied with heated cooling air extracted from the kiln is arranged on said external recirculation circuit.
  • the kiln is a 2-shafts kiln.
  • the illustrated PFRK kiln comprises two shafts which have a circular section and are provided with peripheral channels 3 which are interconnected by a crossover channel 4.
  • the shafts are divided in height into three zones, the preheating zone A where the carbonated stones are preheated before calcination, the calcination zone B wherein the decarbonation of the carbonated preheated stones takes place and the cooling zone C wherein the cooling of the decarbonated calcined material takes place.
  • the carbonated stones are introduced at the top of the shafts by means of an entrance opening 5 which is in open position. By gravity the stones gradually descend in the shaft.
  • the feeding opening 10 for the cooling air and the outlet 14 for the calcined material remain in the open position.
  • the gas stream which comes from the crossover channel 4 progresses to the top of the shaft in counter-current of the stones which are so preheated.
  • an outlet opening 16 which is here in open position, gaseous effluents are exhausted from the kiln through a removal duct 17 and a stack 18.
  • the outlet opening 16 of this removal duct 17 is closed.
  • the kiln also includes a reversing system 19 shown schematically. This system synchronously controls the operation of the shafts, during the inversion time, directly or remotely.
  • the system is arranged to drive said positions in service and out of service of each shaft alternately in calcination working and in preheating working.
  • a separation body 20 is provided outside of the kiln, on the removal duct 17, which is able of taking off a fraction of the gaseous effluent exhausted from the kiln and of introducing it into a recirculation circuit 21.
  • the fraction of gaseous effluent is advantageously treated in a treatment unit 22, wherein it can for example be filtered and/or dried.
  • a control body 26 driven by the reversing system 19 supplies the mixing chamber with the quantity of said cold part of taken off gaseous effluent which is necessary to obtain, in mixture with the heated part, a gas having the temperature appropriate for being injected through the holes 7 of the shaft working in calcination way and for obtaining a thermal decomposition of the preheated stones.
  • a temperature allowing a calcining of the carbonated mineral stones or temperature appropriate for obtaining a thermal decomposition it is meant according to the present invention a temperature in the range of 950°C to 1500°C, preferably of 1100°C to 1400°C.
  • a gas issued from an external source 36 partially or totally in place of a recirculated fraction of gaseous effluent Air at ambient temperature may also be introduced optionally in the mixing chamber 25 from an external source 27 if the temperature is accidentally too high in this chamber.
  • a part of said fraction of gaseous effluent may be taken off from the recirculated circuit 21 upstream of the electrical furnace 23. This taken off gas has a temperature close to the ambient temperature (preferably lower than 200°C) and is introduced in the shaft in calcining way at its top opening 28. This opening is closed in the shaft working in preheating way.
  • FIG. 2 illustrates another embodiment of a PFRK kiln according to the invention.
  • the means for injecting a gas coming from the mixing chamber 25, i.e. a gas at a temperature of the order of 950-1400°C, consist not only in holes 7 in the external shell of the shaft but also in a suspended perforated central cylinder 6, in order to distribute heat both from the middle of the shaft and from the periphery thereof.
  • the heated cooling air is drawn through a central collector element 11 which communicates with an external extracting device 12 for removing from the kiln, at a level lower than the crossover channel 4, the cooling air which has been heated in contact with the decarbonated calcined material.
  • each circular shaft may also be equipped with an annular collector 13 which communicates also with said extracting device 12.
  • At least one heat exchanger supplied with heated cooling air extracted from the kiln is advantageously arranged on said external recirculation circuit 21.
  • the heated cooling air drawn by the extracting device 12 is supplied to a heat exchanger 31 wherein a heat exchange takes place with the cold gas exiting from the treatment unit 22.
  • This unit may contain gas treatment steps like for example cooling, dedusting, pollutants removal and/or water condensation. Air at a temperature close to the ambient temperature is so released in the atmosphere by the outlet 32 and there is an energy recovering upstream of the heating device 23. Between the heat exchanger 31 and the electrical furnace 23, a part of the fraction of the gaseous effluent is taken off from the recirculation circuit 21 by a separation element 35 and may be introduced in the mixing chamber 25 by means of the connecting duct 34 and the control body 26.
  • the kiln illustrated on Fig.2 comprises also an additional mixing chamber 29 which is connected to said mixing chamber 25 of the external furnace 23 and means for injecting a gas 30 from this additional mixing chamber into the crossover channel 4.
  • this additional mixing chamber 29 a portion of the gaseous mixture from said mixing chamber 25 is mixed with a part of said taken off fraction of gaseous effluent which has not been heated. This part is taken off from the recirculation circuit 21 upstream to the electrical furnace 23 and downstream of the heat exchanger 31.
  • the gaseous stream entering the shaft 2 consists almost only in the CO2 released during the decarbonation in shaft 1, the heated gas injected inside the shaft 1 by the means 6 and 7 and the heated gas injected inside the crossover channel by the means 30.
  • This gaseous stream is no more diluted by air, except for little amount of false air or cooling air that would not have been extracted.
  • Example The kiln of this example corresponds to the kiln illustrated on Fig.2 and is conceived for the production of 150 to 760 tons of lime per day. All the mentioned gaseous flows are expressed in Nm 3 /t of produced lime, on dry gas. At the top of the shaft 1 working in calcining way, 270 to 1400 tpd(tons per day) of calcareous stones may be loaded through the entrance opening 5.
  • Simultaneously 300 to 500 Nm 3 /t of recycled gas are introduced by the top opening 28 at a temperature of 30-50°C in order to benefit from the regeneration and not to obtain too high temperature at the outlet of the kiln.
  • the means for injecting gas 6 and 7 introduce a hot gas at the top of the calcination zone B in order to obtain a temperature of 1050- 1250°C at the beginning of the calcination. This temperature corresponds to the temperature of the mixture of the cold gas recycled at the top of the shaft and of the hot gas injected at the top of the calcination zone.
  • This obtained temperature is then widely higher than 900°C, and therefrom it results a decarbonation of the stones with a release of 360-390 Nm 3 /t of CO 2 and in the calcination zone there is formation of a gaseous stream of 950-1400 Nm 3 /t which flows in co-current with the calcined material.
  • 250 to 300 Nm 3 /t of cooling air are introduced at the bottom of each shaft by a feeding opening 10. After heat exchange with the calcined material, the heated cooling air is extracted from the kiln by the collector elements 11 and 13. In order to compensate this extraction, 0 to 600 Nm 3 /t of a CO2 based gas having a temperature of 910-1000°C are continuously introduced in the crossover channel 4 by the injection means 30.
  • the separation element 35 separates in two parts the taken off gaseous fraction.
  • the first part is transferred to a plasma torch which heats the gaseous flow at a very high temperature of 3000-5000°C.
  • This heated part is mixed in a controlled manner with the second cold part of the fraction of gaseous effluent in order to obtain in the mixing chamber 25 a regulated temperature of 1300 to 1500°C.
  • a part of 900 to 1200 Nm 3 /t of this hot gaseous mixture is injected in the shaft 1 by means of the injection means 6 and 7 as above disclosed while another part of 0 to 600 Nm 3 /t is transferred to a second mixing chamber 29.
  • the gaseous flow is mixed in a controlled manner with a cold third part of the fraction of gaseous effluent in order to obtain an adjusted temperature of 910 to 1000°C.0 to 600 Nm 3 /t of this mixture are injected in the crossover channel 4 as above disclosed.
  • the fraction of 300 to 500 Nm 3 /t of the gaseous effluent which are exhausted by the stack 18 have a CO2 content of more than 95 vol%, preferably of 98 vol% on dry gas.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • Ceramic Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)

Abstract

La présente invention concerne un four de régénération à flux parallèle, comprenant au moins deux arbres (1, 2) interconnectés par un canal de croisement (4), chaque arbre comprenant des moyens d'injection d'un gaz chauffé (6) à l'intérieur de l'arbre (1) en calcination travaillant en haut de la zone de calcination (B), le four comprenant en outre un circuit de recirculation externe (21) qui comprend un corps de séparation (20) pour prélever une fraction d'effluent gazeux d'un conduit d'élimination (17), un four électrique externe (23) relié audit corps de séparation (20) et équipé d'au moins une torche à plasma (24).
EP23840990.8A 2022-12-30 2023-12-28 Procédé de calcination de pierres minérales carbonées dans un four de régénération à flux parallèle et four mis en oeuvre Pending EP4643067A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP22217323.9A EP4394296A1 (fr) 2022-12-30 2022-12-30 Procédé de calcination de pierres minérales carbonatées dans un four à régénération à flux parallèle et four mis en oeuvre
PCT/EP2023/087888 WO2024141577A1 (fr) 2022-12-30 2023-12-28 Procédé de calcination de pierres minérales carbonées dans un four de régénération à flux parallèle et four mis en œuvre.

Publications (1)

Publication Number Publication Date
EP4643067A1 true EP4643067A1 (fr) 2025-11-05

Family

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Application Number Title Priority Date Filing Date
EP22217323.9A Withdrawn EP4394296A1 (fr) 2022-12-30 2022-12-30 Procédé de calcination de pierres minérales carbonatées dans un four à régénération à flux parallèle et four mis en oeuvre
EP23840990.8A Pending EP4643067A1 (fr) 2022-12-30 2023-12-28 Procédé de calcination de pierres minérales carbonées dans un four de régénération à flux parallèle et four mis en oeuvre

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WO2022229120A1 (fr) 2021-04-27 2022-11-03 Maerz Ofenbau Ag Système de four à chaux permettant la calcination de roches carbonatées et procédé pour transformer un four à cuve à régénération à courant parallèle et à contre-courant en un système de four à chaux doté d'un four à cuve
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