WO2025196221A1 - Procédé de calcination de pierres minérales carbonatées dans un four régénératif à flux parallèle et four mis en œuvre - Google Patents

Procédé de calcination de pierres minérales carbonatées dans un four régénératif à flux parallèle et four mis en œuvre

Info

Publication number
WO2025196221A1
WO2025196221A1 PCT/EP2025/057699 EP2025057699W WO2025196221A1 WO 2025196221 A1 WO2025196221 A1 WO 2025196221A1 EP 2025057699 W EP2025057699 W EP 2025057699W WO 2025196221 A1 WO2025196221 A1 WO 2025196221A1
Authority
WO
WIPO (PCT)
Prior art keywords
mixing gas
shaft
connecting channel
combustion
stream
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
PCT/EP2025/057699
Other languages
English (en)
Inventor
Olivier VAN CANTFORT
Ziad Habib
Robin FORSTER
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
Priority claimed from PCT/EP2024/058011 external-priority patent/WO2025195612A1/fr
Application filed by Lhoist Recherche et Developpement SA filed Critical Lhoist Recherche et Developpement SA
Publication of WO2025196221A1 publication Critical patent/WO2025196221A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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
    • F27B1/10—Details, accessories or equipment specially adapted for furnaces of these types
    • F27B1/26—Arrangements of controlling devices
    • 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
    • F27D17/20—Arrangements for treatment or cleaning of waste gases

Definitions

  • the present invention relates to a method for calcining carbonate 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 connecting 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.
  • connecting channel it is meant according to the present invention, all the ducting and spaces void of stones that allow the combustion gases to flow from the shaft in calcining mode to the shaft(s) in preheating mode.
  • This connecting channel comprises one or several crossover channels and possibly peripheral channels.
  • crossing channel it is meant according to the present invention, the straight part (as seen from top) of the connecting channel located between two shafts.
  • peripheral channel it is meant according to the present invention, the part of the connecting channel located at the periphery, or around a shaft, particularly in the case of a circular shaft, at the exception of the part of the periphery already occupied by the crossover channel.
  • Carbonate mineral according to the present patent application is typically a calcium-magnesium carbonate, also known as limestone, when containing low amount of magnesium, and dolostone, when the magnesium content is close to the one of calcium on a molar basis.
  • a Parallel Flow Regenerative Kiln usually has 2 to 3 shafts, of circular or rectangular section, which do not work in a continuous way.
  • the classical method for calcining carbonate mineral stones in a parallel flow regenerative kiln having at least two shafts interconnected by a connecting channel comprises, in standard operation, - loading carbonate 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 a 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 mode and in a preheating mode, one shaft working in a calcination mode during a predetermined time period during which at least another shaft works in a preheating mode, and inversely, - the calcining mode comprising : said loading step of
  • the stones introduced into the kiln are at ambient temperature and the flue gas drawn outside the kiln has a temperature typically comprised between 80 and 250°C, preferably between 100 and 200°C and generally 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.
  • carbonate mineral stones particularly mean calcareous stones (limestones), dolomitic stones (dolostones or unburnt dolomites) and/or magnesite stones which are calcined into quicklime, (quick) dolime and/or magnesia, respectively.
  • the calcination reaction of limestone into quicklime is : CaCO3 (solid) + heat CaO (solid)+ CO2 (gas) This is a reversible endothermic reaction and the lime recombines with the CO2 at the first opportunity below 900°C, with an equilibrium and more or less fast kinetics depending on the temperature and the ambient concentration of CO2. Below 850 to 900°C lime and CO2 can easily recombine.
  • Variation of the common calcination process have been proposed in order to improve capture of CO2, such as for example in WO2022/002869 or WO2022/229120.
  • PFRK kilns operation with a regular combustion of fuel in presence of combustion air, the mixing between fuel and comburant gas is relatively poor in the combustion shaft. This leads to CO generation.
  • the generated CO is typically reburned in contact with the cooling air that comes in contact with the combustion fumes in the connecting channel or a bit earlier. Even if the mixing of these two streams is relatively poor, the vast excess of cooling air allows to reburn the CO at the level of the connecting channel.
  • WO2022/002869 it was proposed to extract the cooling air in a ring collector, through a collector tunnel or through a central device, located below the connecting channel to avoid as much as possible mixing between the exhaust gaseous effluent concentrated in CO 2 and the cooling air. In the absence or limited residual presence of cooling air, the aforementioned CO reburning by the cooling air will not occur.
  • the kiln is likely to be operated under excess of oxygen with respect to the combustion stoichiometric conditions. However, it is expected that the excess of oxygen during combustion is going to be as limited as possible to avoid dilution of the CO2 in the exhaust effluent.
  • the present invention provides a method for calcining carbonate mineral stones in a parallel flow regenerative kiln having at least two shafts interconnected by a connecting channel, comprising, in standard operation, - loading carbonate 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 method according to the present invention carries out fuel combustion in dioxygen which results in the mixing gas stream containing the combustion fumes and in the calcination of the carbonate stones.
  • This produces mainly CO2 and steam with some impurities, present as traces in the fuel and in the material to be calcined, and some oxygen not used up by the fuel combustion.
  • these combustion fumes also contain the CO 2 supplied to the oxidizing mixture. This evidently results in a significant increase in the CO 2 content of the gaseous effluent discharged from the top of the furnace, compared to the conventional method.
  • a gaseous effluent concentrated in CO 2 means that it has a CO 2 content of at least 60%, more preferably of at least 70%, more particularly of at least 75%, especially at least 80% and particularly advantageously at least 90% by volume on dry gas.
  • This CO2 can then be used or sequestered under favorable conditions, drastically decreasing the contribution of the furnace to the greenhouse effect.
  • the use of this oxy-combustion method does not necessarily require any particular design of the furnace itself. The only changes to be made to the furnace may be simply external to the furnace and consist of changing the effluent circuits leaving the furnace and providing at least one source of concentrated dioxygen.
  • a mixing gas stream is injected through a series of mixing gas entry means, such as a series of nozzle(s) or orifices connected to respective pipes, at high velocity in such a way that a ratio of momentum J between the gas stream and the combustion fumes is higher than 1, forming combustion fumes depleted in CO exiting the connecting channel.
  • the momentum of a fluid flow is defined as the mass flow of this fluid (in kg/s) multiplied by its average velocity (in m/s). It is expressed in Newtons (kg*m/s2).
  • the momentum ratio between a mixing gas stream and the combustion fumes flow is defined as the ratio of the momentum of the mixing gas stream and the momentum of the combustion fumes.
  • the momentum of the mixing gas stream is measured at the mixing gas outlet.
  • the momentum of the combustion fumes is measured at the cross-section perpendicular to its flow direction and intersecting the center of the mixing gas entry means.
  • said ratio of momentum J is higher or equal to 2, more preferably higher or equal to 4, more preferably higher or equal to 5, more preferably higher or equal to 6, in particular higher than or equal to 7, more particularly higher than or equal to 8, even higher than or equal to 9 or higher than or equal to 10 or higher than or equal to 11 or higher than or equal to 12 or higher than or equal to 13 or higher than or equal to 14 or higher than or equal to 15 or higher than or equal to 16 or higher than or equal to 17 or higher than or equal to 18 or higher than or equal to 19 or higher than or equal to 20 or higher than or equal to 21 or higher than or equal to 22 or higher than or equal to 23 or higher than or equal to 24 or higher than or equal to 25 or higher than or equal to 26 or higher than or equal to 27 or higher than or equal to 28 or higher than or equal to 29 or higher than or equal to 30 to ensure a good mixing between the mixing gas stream and the exhaust effluent.
  • the loading of carbonate mineral stones occurs at the top of the shaft that works in a preheating mode or at the top of the shaft that works in a calcination mode.
  • the loading of carbonate mineral stones occurs at the top of the shaft that works in a preheating mode.
  • said mixing gas stream is chosen in the group consisting of a CO 2 -rich mixing gas stream, a O2-rich mixing gas stream, a steam mixing gas stream or a mixture thereof, to be compatible with oxyfuel or oxy-combustion CO2 concentration.
  • said mixing gas stream is pressurized before passing through the series of mixing gas entry means to reach a differential pressure between said mixing gas stream and the gas inside the connecting channel comprised between 100 mbar and 10 000 mbar, preferably between 200 and 1000 mbar to achieve high velocity, wherein preferably the gas inside the connecting channel has an average velocity (calculated on a cross-section, preferably according to a median plan between two shafts, the average velocity being the volume flow (in m 3 /s) divided by the cross-section of the passage perpendicular to the general direction of the gas flow in m 2 ) of at least 5 m/s, preferably comprised between 5 m/s and 30 m/s, preferably between 10 m/s and 25 m/s, more preferably between 12 m/s and 20 m/s wherein preferably said mixing gas stream has an average velocity of at least 50 m/s, preferably comprised between 50 m/s and 400 m/s, preferably between 100 m/s
  • said mixing gas stream is pressurized before passing through the series of mixing gas entry means by a pressurization device in order to achieve said differential pressure between said mixing gas stream and the gas inside the connecting channel.
  • the pressure of said mixing gas stream is measured by a first pressure sensor within at least one mixing gas entry means of the series of mixing gas entry.
  • the pressure of the gas inside the connecting channel is either measured by a second pressure sensor preferably located on an upper part of a cross-section of the connecting channel, for example located in the roof of the connecting channel to facilitate the access to the sensor and/or preventing dust accumulation on sensor, or is accepted to be between 100 and 400 mbar due to the inherent operation of the kiln.
  • the first pressure sensor and the second pressure sensor are connected to the pressurization device wherein the pressurization device receives either (i) a signal from the first pressure sensor and a signal from the second pressure sensor and wherein the pressurization device adapts the pressurization of the mixing gas stream based on the signals received from the first and second pressure sensors in order to reach a differential pressure between said mixing gas stream and the gas inside the connecting channel comprised between 100 mbar and 10 000 mbar, preferably between 200 and 1000 mbar, or (ii) a signal from the first pressure sensor and the accepted value of the pressure of the gas inside the connecting channel being between 100 and 400 mbar due to the inherent operation of the kiln and wherein the pressurization device adapt the pressurization of the mixing gas stream based on the signal received from the first pressure sensor and this accepted
  • This accepted value is significantly different from the pressure at the entry of the series of mixing gas to not be measured but taken as a reference for determining the pressure of the mixing gas which should then be preferably higher than 400 mbar to achieve high velocity, in a manner that the average velocity of said mixing gas stream is higher than the average velocity of said gas inside the connecting channel, for example higher by 20 m/s, 30 m/s, 40 m/s, 50 m/s, 60 m/s, in such a way that a ratio of momentum J between the each gas stream and the combustion fumes is higher than 1, forming combustion fumes depleted in CO exiting the connecting channel.
  • said mixing gas stream is heated before passing the series of mixing gas entry means to a temperature comprised between 10 °C and 1000 °C, more preferably between 50°C and 1000°C, most preferably between 75°C and 800°C, as the increase of temperature will increase volume and therefore the (injection) velocity.
  • the exhaust effluent is partially or fully collected in at least one buffer after said exhausting step to absorb fluctuation due to the operation of the kiln, especially during the inversion phase.
  • the buffer ensures a regular feeding of exhaust effluent to the kiln or to any downstream device, such as purification and/or concentration units, filters, ...
  • at least one buffer it is meant according to the present invention at least one device of any kind of gas storage allowing to store at least the quantity corresponding to 10 seconds of the gas flow in the connected pipe.
  • said combustion stream containing a comburant is chosen amongst O2-rich gas mixture, in particular pure oxygen, a steam-based gas mixture containing oxygen or their mixture.
  • O 2 -rich gas mixture a mixing gas stream containing more than 70 vol% on dry basis of di-oxygen with respect to the volume of combustion stream containing a comburant, more preferably a mixing gas stream containing more than 80 vol%, even more than 90 vol%, more particularly more than 93 vol% on dry basis di-oxygen, with respect to the volume of combustion stream containing a comburant, such as for example oxygen generated by pressure swing adsorption method which has generally a O2 concentration of 93 vol% on dry basis di-oxygen.
  • the volume ratio between steam and the O2-rich gas mixture is of at least 10-90, at least 20-80, at least 30-70, at least 40-60, at least 50-50, at least 60-40, at least 70-30, at least 80-20, at least 90-10.
  • oxygen is introduced in the kiln at one or more locations to provide a total amount of oxygen introduced in the kiln higher than the amount required for a stoichiometric combustion for the oxy-combustion of fuel in presence of oxygen in excess, and is preferably is introduced at an excess from 2 to 30%, preferably from 3 to 20 %, in particular from 4 to 17%, advantageously from 5 to 15 % in volume with respect to the stoichiometric need of the combustion reaction.
  • the total amount of oxygen introduced in the kiln is equal to the amount of oxygen needed for a stoichiometric combustion for the oxy-combustion of fuel in presence of oxygen multiplied by an excess factor from 1.02 to 1.30, preferably 1.03 to 1.2, in particular from 1.04 to 1.17, advantageously from 1.05 to 1.15.
  • the oxy-combusting step of fuel in the presence of oxygen is carried out in the combustion zone fed by the exhaust effluent and by the combustion stream containing a comburant, simultaneously or separately, or by a mixture of said exhaust effluent and said combustion stream containing a comburant.
  • the temperature in the combustion zone is comprised between 1100°C and 1500 °C, more preferably between 1200°C and 1400°C.
  • said cooling step comprises a supply of cooling gas at the bottom of each of said shafts or only of the shaft working in the calcining mode.
  • said cooling step comprises a supply of cooling gas at the bottom of the shaft having worked in the preheating mode and before the activation of the inversion means, in order to have each shaft encountering sequentially said preheating mode, a cooling step and then a calcining mode.
  • said cooling gas is air, nitrogen (such as nitrogen from the air separation unit when present) or steam or any mixture thereof and preferably air.
  • said cooling gas, preferably said air, supplied at the bottom of each shaft or of the shaft under calcining mode is ascending, flowing in counter-current through the calcined mineral stones forming a heated cooling gas, preferably a heated air, said heated cooling gas, preferably said heated air being extracted at a level below the connecting channel.
  • said heated cooling gas, preferably said heated air is extracted outside of the kiln.
  • the temperature of the heated cooling gas, preferably of the heated air, extracted at a level below the connecting channel is comprised between 500°C and 1000°C, more preferably between 700°C and 950°C.
  • the method according to the present invention comprises at least one heat exchange between the heated cooling air, which has been extracted outside the kiln, and said recirculated fraction of gaseous effluent before injection to the shaft in calcining mode.
  • the mixture when the combustion is carried out in presence of a mixture of gaseous effluent and concentrated dioxygen, the mixture is preferably performed in a mixing chamber in fluid communication with the recirculation of exhaust effluent and one dioxygen source and with the combustion zone of the shaft of the kiln in calcining mode.
  • the heat exchange between the heated cooling air, removed from the furnace, and said collected portion of gaseous effluent discharged from the furnace occurs then before or after it is mixed with concentrated dioxygen.
  • At least one heat exchange between the heated cooling air which has been extracted outside the kiln and said mixing gas stream, before passing through the series of mixing gas entry means is comprised to provide the increase of temperature to the mixing gas stream.
  • the overall quantity of oxygen supplied to the kiln will be calculated by the control system according to the stoichiometric requirement for combustion, multiplied by an excess factor supplied by the operator (typically between 1.02 and 1.30, preferably between1.03 and 1.2, in particular from 1.04 to 1.17, advantageously from 1.05 to 1.15).
  • This global quantity will then, if relevant, be split between oxygen sent to the shaft in calcining mode, at the level of or in the combustion zone (first O2- rich stream) and oxygen sent to the connecting channel (second O2- rich stream).
  • Concerning the quantity of oxygen possibly supplied to the connecting channel it is advantageous to heat it up to high temperature, such as for example above 500°C, preferably above 650°C before injection.
  • the jets are only there to ensure a complete mixing of the incompletely combusted streams with the surrounding remaining comburant mix. Using recycled flue gas ensure no dilution of the flue gas will occur.
  • the mixing gas stream is steam.
  • the gaseous effluent is cooled into a heat exchanger in which water is condensed and discarded forming a cooled and dried gaseous effluent. This is also especially advantageous when the mixing gas stream is steam.
  • a portion of the cooled and dried gaseous effluent is further introduced at the top of the shaft in calcining mode at a temperature below 200°C, preferably below 100°C, more preferably between 30 and 50°C, to keep the benefit from the regeneration, with a slightly higher pressure.
  • PFRK parallel-flow regenerative kiln
  • Such kiln for implementing the method according to the present invention comprising: - at least two shafts, interconnected by a connecting channel, - each of said shafts comprising, in the on or off position, - at least one fuel supply device, - at least one supply opening for oxygen-containing oxidant, - an inlet, for loading carbonate mineral stones, at the top of the shafts, - an outlet for unloading the calcined material produced, at the bottom of the shafts, a gaseous effluent discharge duct at the top of the shafts, which is connected to a chimney, and - a supply of cooling air to cool the calcined material produced, the furnace comprising a system for reversing the operation of the shafts, arranged so that each shaft, in standard mode, operates alternately in calcining mode and in preheating mode, a shaft being in calcining mode for a predetermined time period while at least one other shaft is in preheating mode, and vice-versa, this reversing
  • the kiln according to the present invention comprises a cross channel where the gaseous effluent are transferred to the shaft in preheating mode, the cross over channel is provided with a series of mixing gas entry means to feed a mixing gas stream from outside of the kiln into the lumen of the cross over channel.
  • the series of mixing gas entry means is operatively connected to a pressurization device so as to inject said mixing gas stream from the outside of the kiln at high velocity in the said connecting channel to create the momentum needed to reach the momentum ratio J as defined above.
  • said series of mixing gas entry means is operatively connected to one or more pressurization device(s) through a distributor or distributors connected to more than one entry means or alternatively that each entry means of said series of mixing gas entry means is connected to its own pressurization device.
  • the pressurization device is connected on one side to the distributor and on the other side to a reservoir, a buffer or to a duct of the kiln where the mixing gas stream is a mixing gas stream recovered from the kiln operation.
  • the pressurization device is connected on one side to the entry means and to the other side to a reservoir, a buffer or to a duct of the kiln where the mixing gas stream is a mixing gas stream recovered from the kiln operation.
  • the kiln according to the invention only has a few structural changes to the exterior of the furnace. Therefore, existing parallel-flow regenerative kilns may be easily arranged to implement a calcining method according to the invention.
  • each mixing gas entry means of said series of mixing gas entry means is chosen between a through-hole or a through-nozzle or a through-distributor allowing to connect a source of mixing gas stream outside of the kiln and said lumen of the connecting channel, optionally by means of additional nozzles.
  • each mixing gas entry means of said series of mixing gas entry means is disposed along the external wall of the cross-section of the connecting channel, preferably along the ceiling of the external wall of the cross-section.
  • the gaseous stream entry means each extends across the wall, preferably across the upper external wall of the connecting channel to be able to feed the gaseous stream into the lumen of the connecting channel.
  • L1 is defined such as 0,25 L ⁇ L1 ⁇ 0.75 L.
  • L2 is defined such as 0,25 L ⁇ L2 ⁇ 0.75 L.
  • l is defined such as 0,25 L ⁇ l ⁇ 0.75 L.
  • the mixing gas entry means are located in the peripheral channels of the connecting channel.
  • the series of mixing gas entry means comprises x row(s) of y mixing gas entry means positioned in series and/or t rows of z mixing gas entry means positioned in parallel, with x, y, z and t being integer higher or equal to 1 and preferably lower than 50, preferably lower than 30.
  • the mixing gas entry means are disposed in a shifted manner such as for example with for the first raw containing y mixing gas entry means, the second raw containing y-1 mixing gas entry means, the third raw containing y mixing gas entry means and the like.
  • the y mixing gas entry means are disposed aligned in series along a line following the external wall of the cross-section of the crossover channel, equally distanced from each other, but not necessarily along the full perimeter of the crossover channel. It is indeed preferred according to some embodiments to have 5, 6, 7, 8 or even 10 entry means located on the upper wall and extending through the wall of the crossover channel to inject the mixing gas stream in the zone where the hot combustion fumes are transferred. Accordingly, the entry means can be located along 1/3, 1/4, 1/5, 1/6 or even 1/8 or 1/10 of the external wall of the cross over channel, preferably in the upper part of the crossover channel.
  • each gaseous entry means has an implantation orifice in the connecting channel and one or more mixing gas stream exit, said implantation orifice being positioned in the ceiling of the connecting channel, in the bottom of the connecting channel or in the lateral wall of the connecting channel.
  • this later implementation is performed only in the crossover channel, part of the connecting channel.
  • Number n can be for example 1, 2, 3, 4, 5, 6.
  • the installation of gaseous entry means is symmetrical relative to the plane of symmetry of the two shafts.
  • the mixing gas entry means of the n rows have a longitudinal central axis along the flow passing through the mixing gas entry means and centrally, said longitudinal axis of each mixing gas entry means forming an angle with respect to the vertical direction comprised between 15 and 75° in absolute value, injecting co-currently the mixing gas stream with respect to the gaseous effluent or, preferably, injecting counter-currently the mixing gas stream with respect to the gaseous effluent.
  • the mixing gas entry means of the n rows have a longitudinal central axis along the flow passing through the mixing gas entry means and centrally, said longitudinal axis of each mixing gas entry means forming an angle with respect to the horizontal direction comprised between 15 and 75° in absolute value, injecting co-currently the mixing gas stream with respect to the gaseous effluent or, preferably, injecting counter-currently the mixing gas stream with respect to the gaseous effluent.
  • each mixing gas entry means is an elongated hollow body (through distributor), preferably cylindrical hollow body enclosed in an outer tubular wall, said mixing gas entry means having a first end and a second end, opposed to the first end, said first end being protruding in the lumen of the connecting channel and said second end being in fluid communication with the outside of the connecting channel, said mixing gas entry means extending preferably through the wall of the connecting channel, with said one or more mixing gas stream exit being one or more through holes performed on the outer tubular body provided to establish a fluid communication between the lumen of the elongated hollow body and the connecting channel.
  • the elongated hollow body is a divided in a first and a second longitudinal sub-cavities, each sub-cavity having a series of exit holes and wherein the series of exit holes of the first sub-cavity is closed when the series of exit holes of the second sub-cavity is open and wherein the series of exit holes of the first sub-cavity is open when the series of exit holes of the second sub-cavity is closed.
  • said connecting channel further comprises a series of obstacles arranged to increase the mixing between said mixing gas stream and said gaseous effluent.
  • the series of obstacles can contain 1, 2, 3, 4, 5, 6, 7, 8 or even 10 obstacles extending from any part of the internal wall of the cross over- channel.
  • the obstacles can be pillars or baffles and can accordingly be connected at their two ends with the internal wall of the connecting channel or only at one of their ends.
  • the obstacles can be under the form of bars, possibly hollow and cooled, or brick pillars. These obstacles could also be placed in staggered rows.
  • Other types of obstacles are also contemplated such as, for example a "bluff body" suspended in the middle of the channel.
  • the series of obstacles extends from the internal wall of the connecting channel, more particularly from the upper internal wall.
  • L’1 is defined such as 0.25 L ⁇ L’1 ⁇ 0.75 L.
  • L’2 is defined such as 0,25 L ⁇ L’2 ⁇ 0.75 L.
  • the series of obstacles comprises z’ row(s) of t’ obstacles positioned in series, with z’ and t’ being integer equal or higher than 1 and preferably lower than 10.
  • the t’ obstacles are disposed aligned in series along a line following the internal wall of the cross-section of the connecting channel, equally distanced from each other, but not necessarily along the full internal perimeter of the connecting channel. It is indeed preferred according to some embodiments to have 5, 6, 7, 8 or even 10 obstacles located on the internal wall and extending from the internal wall of the connecting channel to create turbulences in the zone where the hot combustion fumes are transferred.
  • the obstacles can be located along 1/3, 1 ⁇ 4, 1/5, 1/6 or even 1/8 or 1/10 of the internal wall of the cross over channel.
  • Number a is an integer and can be for example 1, 2, 3, 4, 5, 6.
  • the obstacle of the series of obstacles has a heigh that is comprised between 10 and 75% of the height or diameter of the lumen of the connecting channel.
  • the shafts have a circular cross-section, in that the connecting channel comprises a crossover channel and the peripheral channels, the cross over channel connecting the peripheral channels arranged around each shaft so as to allow a transfer of gas and in that, below the connecting channel, the shafts are provided with a collector ring connecting with an evacuation element so as to allow heated cooling air to be removed from the furnace.
  • the circular shafts further comprise, at the bottom, a central collector element connecting with an evacuation element so as to allow heated cooling air to be removed from the furnace, below the connecting channel.
  • the shafts have a rectangular cross-section, in that a first side of a shaft faces a first side of a neighboring shaft and each shaft comprises a second side that is opposite those facing each other and in that the connecting channel is a crossover channel which directly connects one shaft to the other via their first sides, and in that, below the connecting channel, said first sides and said second sides of the shafts are provided with a collection tunnel connecting with an evacuation element so as to allow heated cooling air to be removed from the furnace.
  • the furnace comprises, as a dioxygen source for the recirculation circuit, an air separation unit for separating air into dioxygen and dinitrogen. An oxygen tank may also be provided.
  • the kiln according to the present invention comprises a control system provided for, when said combustion fumes comprising a comburant is O2-rich gas and said mixing gas stream is O2-rich mixing gas stream, calculating an amount of oxygen in excess for the step of oxy-combusting the fuel according to the stoichiometric requirement for combustion multiplied by an excess factor supplied by the operator and a spreader provided to spread said amount of oxygen between a first O 2- rich stream and a second O 2 -rich stream, said first O 2- rich stream being supplied to the combustion zone of the shaft in calcining mode and said second O 2- rich stream being supplied to the connecting channel.
  • the kiln according to the present invention comprises, downstream or upstream the pressurization means, heating means to heat said mixing gas stream before injection in the connecting channel, said heating means being preferably chosen amongst a heat exchanger, a combustion chamber, electrical heater.
  • said recirculation circuit is connected to at least one buffer unit.
  • said recirculation circuit is connected to storage unit provided to store a CO2-rich gaseous effluent, optionally before or after a buffer unit.
  • FIG. 1 schematically shows a conventional PFRK furnace of circular cross-section.
  • FIGS. 2, 3 and 4 schematically show several embodiments of the furnace with a circular cross-section according to the invention.
  • FIG. 5 schematically shows one embodiment of the mixing gas entry means of the furnace according to the present invention.
  • FIG. 6 schematically shows one embodiment of the mixing gas entry means of the furnace according to the present invention arranged to ensure a counterflow injection of the mixing gas stream in a kiln with circular or rectangular shaft.
  • FIGS. 7, 8 and 9 show cross-section views of different embodiments of the furnace according to the invention.
  • identical or similar parts use the same references.
  • the shaft shown on the left is in calcination mode and the shaft shown on the right is in preheating mode.
  • Standard parts such as loading or unloading equipment, are not shown or they are shown very schematically, in order to not overload the drawings.
  • the PFRK furnace shown is a vertical double-shaft furnace 1, 2, where the fuel is injected alternately in one shaft 1 then in another 2 for approximately 12 minutes with a stop period between cycles of 1 to 2 minutes to reverse the circuits. This is the “reversing” period.
  • Both shafts have a circular cross-section and are provided with peripheral channels 13 which are interconnected by a crossover channel 3.
  • the shafts are divided vertically into three areas, the preheating area A where the carbonate stones is preheated before calcination, the combustion area B where the calcination of the carbonate stones occurs and the cooling area C where the cooling of the calcined material occurs.
  • a fuel supply device in the form of lances 4 injects a fuel 9 into the shaft, which, in the example shown, is natural gas.
  • the carbonate stones loaded at the top of the shaft via an inlet 5 in the open position, progressively descends in the shaft.
  • Combustion air is introduced at the top of the shaft via a supply opening 6, which allows for fuel combustion at the outlet of the lances 4 and a decarbonation of the carbonate stones to calcined material 10.
  • the mixing gas stream 11 formed by the combustion and decarbonation descends co-currently to the calcined material and, using the peripheral channel 13, moves into the crossover channel 3.
  • Cooling air is introduced via a supply duct 7 at the bottom of the shaft, counter- currently to the calcined material, to cool it.
  • the heated cooling air 12 introduced in the calcination shaft mixes with the combustion fumes 11 in order to move into the crossover channel 3.
  • the calcined material is unloaded via the outlet 8 into a piece of unloading equipment 24.
  • the fuel supply device When a shaft is in preheating mode, here the shaft 2 , the fuel supply device is closed and the lances 4 are therefore off.
  • the inlet 5 for the carbonate stones and to the opening 6 for supplying combustion air.
  • the supply duct 7 for the cooling air and the outlet 8 for the calcined material remain in the open position.
  • the heated cooling air mixes with the combustion fumes 11 which, from the crossover channel 3, enters the shaft via the peripheral channel 13.
  • the combustion fumes 11 progresses until reaching the top of the shaft where it is discharged from the furnace via a discharge duct 14 and transferred to a chimney 15, possibly after treatment in equipment’s such as filters.
  • the furnace also comprises a reversing system 16, shown schematically. It controls, in a synchronized manner, the operation of the shafts during the reversing time of the shafts, either directly or remotely. It controls the on and off switching of all elements of the furnace in such a way that, in production mode, each shaft operates alternately in calcination mode and in preheating mode. In some cases, there are three shafts, two in preheating mode and one in combustion.
  • FIG.2 is a view of an advantageous furnace according to the present invention.
  • this embodiment comprises separating member 17, capable of collecting a portion of gaseous effluent discharged from the furnace and introducing it into the recirculation circuit 18, and which has been provided on the exterior, on the discharge duct 14.
  • the collected portion of gaseous effluent is advantageously treated in a treatment unit 19, where it may, for example, be filtered and/or dried.
  • An air separation unit 20 separates air supplied by the duct 21 into N2 discharged via the duct 22 and O2 supplied to the recirculation circuit 18 via the supply duct 23.
  • This circuit 18 then brings the oxidizing mixture formed from the recirculated portion of gaseous effluent and concentrated O2 to the top of each of the shafts at the supply opening 6.
  • the separating member 17 is continuously in service during combustion, the same as the treatment unit 19 and the air separation unit 20.
  • the reversing system 16 closes the discharge duct 14 at the top of the shaft in calcination mode. However, at the top of this shaft, it opens the supply opening 6 to allow the oxidizing mixture to be introduced, while it is closed at the top of the shaft in preheating mode.
  • the heated cooling air is extracted after contact with the calcined material, by installing a removal system.
  • the shafts 1 and 2 are each provided with a collector ring 25, below the crossover channel 3, which connects with an evacuation element 26 so as to allow heated cooling air to be removed from the furnace.
  • the shafts may further optionally comprise, at the bottom, a central collector element 27 connecting with the evacuation element 26 as to also allow a central removal of the heated cooling air, below the crossover channel 3.
  • a heat exchange may be provided with the portion of recirculated gaseous effluent using a heat exchanger 36, before or after the mixing thereof with concentrated dioxygen.
  • an injection of a fraction of said collected portion of gaseous effluent discharged from the furnace using an injection duct 37 may also be provided.
  • FIG.3 is a view of another advantageous furnace according to the present invention. As can be seen, this embodiment is similar to the embodiment of the furnace described in FIG.
  • the system to inject a mixture of fuel and oxygen into the connecting channel or crossover channel 3 comprises : - a combustion chamber 42, - a duct 41 in fluid connection with the supply duct 23 and with the combustion chamber 42, the duct 41 being arranged to provide oxygen into the combustion chamber 42, - a fuel injection duct 40 in fluid connection with the combustion chamber 42, wherein the fuel injection duct 40 is arranged to inject fuel able to heat the oxygen in the combustion chamber 42 in order to provided hot oxygen, - a duct 43 in fluid connection with the combustion chamber 42 and the series of mixing gas entry means of the connecting channel or crossover channel 3 arranged to inject the mixing gas stream (mixture of fuel and oxygen) at high velocity in such a way that a ratio of momentum J between the gas stream and the combustion fumes is higher than 1, forming combustion fumes depleted in CO exiting the connecting channel.
  • the mixing gas stream mixture of fuel and oxygen
  • FIG. 5 shows a section of a part of the furnace according to the present invention centered on the crossover channel 3 showing one mixing gas entry means 46 of the series of mixing gas entry means fluidly connected to a circuit arranged to provide a fluid connection between each mixing gas entry means 46 and the gaseous effluent duct, injection duct, 37 or 43 or 45, said circuit comprising: - a pressurization device 47 fluidly connected to said gaseous effluent duct 37 or 43 or 45, - a valve system 48 fluidly connecting the pressurization device 47 and each mixing gas entry means 46.
  • each mixing gas entry means 46 of said series of mixing gas entry means comprises one end being a series of nozzle 50 and/or a series of hole 51.
  • the valve system 48 is a distribution valve or at least two separate valves.
  • the direction of the arrows 53 in the crossover channel 3 indicates the direction of the combustion fumes 11.
  • the mixing gas stream 54 is injected in counter-current with respect to the combustion fumes, i.e. the nozzle 50 injects said mixing gas stream in the combustion fumes through the exit hole 51 when the shaft on the left 1 is in calcining mode and the nozzle 50’ is not open.
  • the shafts 1 and 2 of the furnace are on either side of the crossover channel 3 wherein openings 54 are located in a plane that is equally distance from shafts 1 and 2 and perpendicular to the longitudinal axis having a length L along the crossover channel 3.
  • the shafts have either a circular cross-section (FIG.7A) or a rectangular cross- section (FIG. 7B).
  • FIG. 8 which shows a cross-section view of a furnace according to the invention, the injection of the gases containing additional air can be carried out not only through the openings 54 provided in the crossover channel, but also by the openings 57 provided in the peripheral channels 13.
  • FIG. 8 which shows a cross-section view of a furnace according to the invention
  • FIG. 9 shows a cross-section view in such an embodiment of the furnace according to the invention comprising 3 shafts 1, 2 and 58 interconnected by 3 crossover channels 3 , 59 and 60.
  • the shafts 2 and 58 are in preheating mode while the shaft 1 is in calcination mode and so on.
  • the present invention is not limited to the disclosed embodiment and several modifications may be provided without being outside the scope of the appended claims.

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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)
  • Furnace Details (AREA)

Abstract

La présente invention concerne un procédé de calcination de pierres minérales carbonatées dans un four régénératif à flux parallèle dans lequel à travers ledit canal de liaison, où un flux de gaz de mélange est injecté à travers une série de moyens d'entrée de gaz de mélange à grande vitesse de telle sorte qu'un rapport de quantité de mouvement J entre chaque flux de gaz et les fumées de combustion est supérieur à 1, formant des fumées de combustion appauvries en CO sortant du canal de liaison.
PCT/EP2025/057699 2024-03-20 2025-03-20 Procédé de calcination de pierres minérales carbonatées dans un four régénératif à flux parallèle et four mis en œuvre Pending WO2025196221A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
EPPCT/EP2024/057449 2024-03-20
EP2024057449 2024-03-20
EPPCT/EP2024/058011 2024-03-25
PCT/EP2024/058011 WO2025195612A1 (fr) 2024-03-20 2024-03-25 Procédé de calcination de pierres minérales carbonatées dans un four régénératif à écoulement parallèle et four mis en oeuvre

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WO2025196221A1 true WO2025196221A1 (fr) 2025-09-25

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Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1050081A (zh) 1989-09-06 1991-03-20 哈姆林传动公司 自动定位的皮带松紧调整器
JP2002060254A (ja) 2000-08-16 2002-02-26 Nkk Corp シャフト式石灰焼成炉および生石灰の製造方法
CN105000811A (zh) 2015-07-24 2015-10-28 东北大学 一种基于co2富集的并流蓄热式石灰窑生产工艺方法
US20200048146A1 (en) 2017-04-17 2020-02-13 Shiheng ZHANG Lime kiln apparatus fully recycling co2
WO2022002869A1 (fr) 2020-07-03 2022-01-06 S.A. Lhoist Recherche Et Developpement Procédé de calcination de roche minérale dans un four droit vertical à flux parallèles régénératif et four mis en oeuvre
DE102021204176A1 (de) * 2021-04-27 2022-10-27 Maerz Ofenbau Ag Gleichstrom-Gegenstrom-Regenerativ-Schachtofen und Verfahren zum Brennen von Karbonatgestein
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
WO2022238385A1 (fr) 2021-05-11 2022-11-17 Tecforlime Procédé de décarbonatation de matériaux carbonatés dans un four vertical à plusieurs cuves
WO2022238384A1 (fr) 2021-05-11 2022-11-17 Tecforlime Procédé de décarbonatation de matériaux carbonatés dans un four vertical à plusieurs cuves

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1050081A (zh) 1989-09-06 1991-03-20 哈姆林传动公司 自动定位的皮带松紧调整器
JP2002060254A (ja) 2000-08-16 2002-02-26 Nkk Corp シャフト式石灰焼成炉および生石灰の製造方法
CN105000811A (zh) 2015-07-24 2015-10-28 东北大学 一种基于co2富集的并流蓄热式石灰窑生产工艺方法
US20200048146A1 (en) 2017-04-17 2020-02-13 Shiheng ZHANG Lime kiln apparatus fully recycling co2
WO2022002869A1 (fr) 2020-07-03 2022-01-06 S.A. Lhoist Recherche Et Developpement Procédé de calcination de roche minérale dans un four droit vertical à flux parallèles régénératif et four mis en oeuvre
DE102021204176A1 (de) * 2021-04-27 2022-10-27 Maerz Ofenbau Ag Gleichstrom-Gegenstrom-Regenerativ-Schachtofen und Verfahren zum Brennen von Karbonatgestein
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
WO2022238385A1 (fr) 2021-05-11 2022-11-17 Tecforlime Procédé de décarbonatation de matériaux carbonatés dans un four vertical à plusieurs cuves
WO2022238384A1 (fr) 2021-05-11 2022-11-17 Tecforlime Procédé de décarbonatation de matériaux carbonatés dans un four vertical à plusieurs cuves

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