Plant and process for the production of cement with carbon dioxide capture

Abstract

The invention relates to a method for producing cement clinker (110) from raw meal (120), comprising the following steps: preheating (10) the raw meal (120) to hot meal (122), separating (20) the hot meal (122) in a cyclone separator (161) and introducing the hot meal (122) via a hot meal line (163) into an entrained-flow reactor (170), calcining (30) the hot meal (122) to deacidified raw meal (121) in the entrained-flow reactor (170) as a calciner, separating (40) the deacidified raw meal (121) in a cyclone separator (177) following the entrained-flow reactor (170) as a calciner in the gas flow direction, sintering (50) the separated, deacidified raw meal (121) into a rotary kiln (130) to produce cement clinker (110) and a corresponding plant. According to the invention, preheating (10) of the raw meal (120) to hot meal (122) is provided in an entrained-flow reactor (160) as the first entrained-flow reactor and the exhaust gases of the rotary kiln (130) are supplied (55) to this first entrained-flow reactor (160).

Description

The invention relates to a method for producing cement clinker from raw meal, comprising the following steps: preheating the raw meal to hot meal, separating the hot meal in a cyclone separator and introducing the hot meal via a hot meal line into an entrained flow reactor, calcining the hot meal to deacidified raw meal in the entrained flow reactor as a calciner, separating the deacidified raw meal in a cyclone separator following the entrained flow reactor as a calciner in the gas flow direction, sintering the separated, deacidified raw meal in a rotary kiln to form cement clinker and a plant corresponding thereto.In the known production of cement clinker from a mixture of a silicate-containing and carbonate-containing rock flour, the raw flour, carbon dioxide (CO 2) is formed equally from two sources independent of one another. Firstly, carbon dioxide (CO 2) is formed during the combustion of fossil fuels and also during the combustion of alternative secondary fuels for the strongly endothermic process. On the other hand, carbon dioxide (CO 2) is formed during the calcining of the carbonate-containing rock powder, in which carbon dioxide (CO 2) is precipitated from the carbonate, in order to obtain quicklime (CaO) as intermediate. Carbon dioxide (CO 2) from both sources is usually discharged to the free atmosphere as exhaust gas. Carbon dioxide (CO 2) contained in the atmosphere of the earth has been recognized as the cause of a currently observed change in climate on the earth. Therefore, efforts are currently being made to prevent or at least reduce the introduction of carbon dioxide (CO 2) into the atmosphere.The separation of carbon dioxide (CO 2) from exhaust gases is a highly endothermic process and requires thermal energy. It is therefore obvious to use the waste heat of the cement process for the operation of the CO 2- separation. However, the waste heat available in the production process of cement clinker is not sufficient for a separation of the entire CO 2. Cement production according to current methods produces more carbon dioxide (CO 2) than can be separated by waste heat available in the process. One way to drive up the missing thermal energy is to replace this heat by heat pumps. However, heat pumps require electrical power to operate them, the conversion from heat of which is very inefficient. A further possibility for providing the thermal energy necessary for the separation and storage of carbon dioxide (CO 2) is a separate hot gas generator, which, however, causes additional plant costs and during the operation thereof with fossil fuels further CO 2 is emitted and in which the ash of the fuel is produced as waste. This waste itself constitutes a disposal problem. It would therefore be necessary to design this hot gas generator in such a way that as little problematic ash as possible is produced as waste. The construction and operation of such a plant is in turn very economically complicated.International patent application published as WO 2022 / 179 847 A1 discloses an entrained flow reactor in a heat treatment plant for preheating mineral substances. The heat is generated with the aid of fuel.German laid-open specification DE 10 2016 111 291 A1 likewise discloses an entrained flow reactor for preheating mineral material. This entrained flow reactor is also intended to be heated with fuel.It is the object of the invention to modify a known method for producing cement clinker in such a way that sufficient waste heat is available in the production process. In a conventional method for producing cement clinker, efforts are made to optimize the entire method in such a way that as little waste heat as possible is produced, since a heat loss is associated with a low economic efficiency. According to the object of the invention presented here, exactly the opposite is desired, namely that the method discharges as much waste heat as possible, which can be used for the operation of a method for separating carbon dioxide (CO 2) off. If the method known per se for producing cement clinker is modified so that as much waste heat as possible is produced, further process properties can be used which make an ash after-treatment superfluous. The method to be proposed fundamentally changes the requirements for the process design. If the generation of waste heat should be avoided as far as possible, then just as much waste heat as is required in the separation of CO 2 from the exhaust gas should be generated as specifically as possible. Nevertheless, the production of cement clinker remains the primary objective.First, there is the recognition that it is not possible to operate a known plant for producing cement clinker by means of an excess of fuel and thus an excess of waste heat, because this would result in the plant being overheated. The solution of the object of the invention consists in modifying the known production process from preheating the raw meal, calcining the preheated raw meal, sintering the raw meal and subsequently cooling the sintered cement clinker in such a way that waste heat which arises during cooling and waste heat which exists in the sintering furnace are not used for the endothermic calcination and the waste heat which again arises during the calcination is again used for preheating, but instead firstly use this waste heat for preheating and only then use the then still excess heat for calcining, wherein then the still missing thermal energy is added for calcination by burning preferably waste-based secondary fuels. According to the concept of the invention, the sequence of the waste heat utilization during preheating, calcining and sintering is modified. Only this enables working with a high excess of fuel, so that as much waste heat as possible is produced. Specifically, the object according to the invention is achieved by preheating a portion of the raw meal in an entrained-flow reactor as a first entrained-flow reactor and subjecting this first entrained-flow reactor to the hot offgases from the rotary kiln. Further advantageous embodiments of the method are specified in the dependent claims for claim 1. The reaction of the process according to the invention can take place in a plant according to claim 10. Further advantageous embodiments of the plant are specified in the dependent claims for claim 10.In order to be able to implement the concept according to the invention as optimally as possible, it is advantageous to replace the established cyclone heat exchanger by an entrained flow reactor, wherein this entrained flow reactor acts as a preheater. Two requirements are then imposed for the calcination from the gas and waste heat flow direction in the subsequent reactor. The temperature required for the ignition of the fuel that takes place there must have been transferred to the flour stream in the first entrained stream reactor, which flour stream serves as a heat carrier in this second step, so that the fuel is to be ignited from raw flour, air and oxygen in an atmosphere that is now too cold. A very long residence time in the entrained flow reactor, which acts as a calciner, is required in order to heat the fuel and the raw material and to allow the burning out of the tertiary air, which can be taken from optionally heat for preheating. These requirements can be achieved by the person skilled in the art by appropriately optimized design of the method.In addition to the method reversed from the gas flow direction and the waste heat flow direction, first of all using the waste heat of the rotary kiln for preheating part of the flour (20-50%) and using the remaining heat for the CO2 separation, there are, according to the idea of the invention, further possibilities for generating even more waste heat in the method, namely cooling the cement clinker in a clinker cooler which is arranged downstream of the rotary kiln in the material flow direction and introducing heated cooling air as tertiary air from a cooler head housing of the clinker cooler into a second entrained flow reactor which acts as a calciner via a tertiary air line. The thermal energy in the tertiary air is then used to ignite the fuel during the calcination. In order to further increase the available amount of waste heat, it is possible to remove waste heat from the tertiary air via a heat exchanger, wherein the heat exchanger is connected into the tertiary air line. The tertiary air carries with it high-caloric heat, which can be used well as operating energy in a further process for separating off carbon dioxide (CO 2). The tertiary air cools down strongly. In order to compensate for this heat loss, it is now possible to use far more fuel in the entrained flow reactor, which acts as a calciner.In order to be able to use even more waste heat from the method for producing cement clinker, it is possible to remove waste heat from heated cooling air as exhaust air via a heat exchanger which is connected into a gas line for discharging exhaust air from the cooler. This waste heat is low-caloric heat and is suitable for drying fuels or for heating catalysts used in the chemical reaction of carbon dioxide (CO 2). The removal of the waste heat from the cooler does not require any additional compensation of the thermal energy in the existing method for producing cement clinker.The thermal energy still present in the exhaust gas of the rotary kiln after preheating the raw meal can be directly tapped by removing waste heat from heated exhaust gas, separated off via a cyclone separator, from the first entrained flow reactor, which acts as a preheater, via a heat exchanger, which is connected into a gas line for discharging the exhaust gas from this first entrained flow reactor.In order to be able to use even more waste heat from the process for producing cement clinker, it is possible to remove waste heat from heated exhaust gas separated off via a cyclone separator from the entrained flow reactor acting as a calciner via a heat exchanger which is connected to a gas line for discharging the exhaust gas from the second entrained flow reactor.The process can generate even more waste heat by using a further entrained flow reactor which also acts as a calciner. This third entrained flow reactor is connected downstream of the second entrained flow reactor in the gas flow direction, which also acts as a calciner. It is then possible to remove waste heat from heated exhaust gas separated off via a cyclone separator from the entrained flow reactor acting as a calciner via a heat exchanger which is connected to a gas line for discharging the exhaust gas from the second entrained flow reactor.The invention is explained in more detail with reference to the following figures. It shows: FIG. 1 shows a plant for implementing the method according to the invention in a first embodiment, FIG. 2 shows a plant for implementing the method according to the invention in a second embodiment, FIG. 3 shows a flow diagram of the method according to the invention in a first embodiment, FIG. 4 shows a flow diagram of the method according to the invention in a second embodiment.FIG. 1 outlines a plant 100 for implementing the method according to the invention in a first embodiment. This plant 100 is designed primarily for producing cement clinker 110 from raw meal 120, but is intended to produce as much waste heat as possible, unlike known plants. As other known installations also, this installation 100 has at least one rotary kiln 130 for sintering deacidified raw meal 121 to cement clinker 110. The rotary kiln is fired via a burner which is itself supplied with primary fuel 200 and primary air 202. At least one clinker cooler 140 for cooling the cement clinker 110 is arranged downstream of the rotary kiln 130 in the direction of material flow, wherein the clinker cooler 140 shown here has a tertiary air line 150 for removing cooling air 147 heated in the cooler head housing 149 of the clinker cooler 140 as tertiary air 151. The clinker cooler 140 is blown in with atmospheric cooling air 147, which flows from below through the cement clinker 110 and in the process cools the hot cement clinker 110, which has a temperature of about 1,400° C. when it is discharged from the rotary kiln 130. The cooling air 147 which is heated in the process assumes a temperature of approximately 1,250° C. in the vicinity of the rotary kiln head, that is to say that part of the rotary kiln 130 which projects into the cooler 140. This hot cooling air 151 formed in the cooler head housing 149 is partly conducted further into the plant 100 through a tertiary air line 150 for recuperation of the heat contained in the hot cooling air. In this case, it is possible to remove heat from the tertiary air 150, which is otherwise used for recuperation, as waste heat Q via a heat exchanger 155. A further portion of the hot cooling air produced there is conducted as secondary air 203 into the rotary kiln 130. Cooling air 147 which flows further away from the rotary kiln head into the cooler 140 impinges on already cooled cement clinker 110 and there only assumes the lower temperature of the cement clinker 110 located there. At the end of the clinker cooler 140, the heated cooling air is only at a temperature between 200° C. and 300° C.Downstream of the rotary kiln 130 in the gas flow direction, which in the plant 100 is for the most part directed opposite to the material flow direction, a first entrained flow reactor 160 is arranged as a heat exchanger, in which raw meal 120 is preheated by the hot exhaust gases from the rotary kiln 130 to form hot meal 122. This entrained flow reactor 160 is followed in the gas flow direction by a first cyclone separator 161 for separating the hot meal 122. The cyclone separator 161 separates the hot meal 122 from the now cooled exhaust gases of the rotary kiln 130. A first hot meal line 163 directs the hot meal 122 into a second entrained flow reactor 170 which acts as a calciner which is itself connected to the tertiary air line 150 and from which tertiary air 151 is fed. A meal line 179 conducts deacidified raw meal 121 originating from the second entrained-flow reactor 170 acting as a calciner into the rotary kiln 130, wherein this deacidified raw meal 121 is separated from the process gas in the entrained-flow reactor 170 by a cyclone separator 177.In this plant 100, there are a plurality of locations at which heat can be removed from an exhaust gas or a process gas. The heat removed, which is absent in the process for producing cement clinker, can then be compensated for by using more fuel in the further plant. A first location where abundant waste heat Q can be extracted is gas line 168. This latter discharges an exhaust gas from the previously mentioned cyclone separator 161 and carries therein valuable waste heat which is removed via a heat exchanger 165 connected into this gas line 168. In the illustration, the heat Q is represented with a point above it, which means that a heat flow is meant here. In order to draw off the exhaust gas from the cyclone separator 161, a compressor 166 can be arranged behind the heat exchanger 165, which compressor assists the gas flow from the rotary kiln 130 to the heat exchanger 165 by the draw off of cooled exhaust gas 169 which carries carbon dioxide (CO 2) therein.The second entrained flow reactor 170, which acts as a calciner, is designed for a residence time of 4 s to 8 s and thus has a longer residence time than known calciners typically exhibit. This longer dwell time is intended to ensure that the secondary fuel 201, which is fed into the entrained flow reactor 170 via a fuel feed 171, safely ignites and burns out. Since the supply air to the entrained flow reactor 170 consists of cooled tertiary air 150, the ignition tendency of the secondary fuel 201 is somewhat reduced. To achieve ignition, the secondary fuel is fed together with the hot meal 122 into the entrained flow reactor acting as a calciner, the hot meal supplying the necessary ignition energy. Not only hot meal 122 from the first entrained flow reactor 160 acting as a heat exchanger is introduced into the entrained flow reactor 170 acting as a calciner, but also cold raw meal which is fed into the entrained flow reactor via a raw meal feed 172. By feeding in cold raw meal, it is possible to control the temperature in the entrained flow reactor 170. The raw meal 121 to be deacidified in the entrained-flow reactor 170 is calcined, hot meal 122 is separated off by a cyclone separator 177 and, as mentioned above, is conducted to the rotary kiln via a meal line 179. Exhaust gas 189 which is formed in the entrained flow reactor 170 and is separated off via the cyclone separator 177 leaves the plant 100 via the gas line 188. However, waste heat Q is previously removed from this exhaust gas 189 via a heat exchanger 185 in the gas line 188 before it leaves the plant 100 as cooled exhaust gas 189.Exhaust gas from the second entrained flow reactor 170, which acts as a calciner, passes through a burn-out chamber 175 in order to safely burn out the fuel. Thereafter, the flour / gas suspension formed in the entrained flow reactor 170 takes the path via the descending branch 176 into the cyclone separator 177.FIG. 2 shows a first embodiment of a plant 200 for implementing the method according to the invention. This plant differs from the plant 100 in FIG. 1 by an additional, third entrained flow reactor 180. The second entrained-flow reactor 170 acting as a calciner is followed in the gas flow direction by this third entrained-flow reactor 180, which has a fuel feed 181 for secondary fuel 201 and a raw meal feed 182 for raw meal 120. This third entrained-flow reactor 180 also has an effect as a calciner, wherein a meal line 183 conducts deacidified raw meal 121 originating from the third entrained-flow reactor 180, which raw meal has been separated off via a cyclone separator 187, into the rotary kiln 130. The exhaust gas from the second entrained flow reactor 170, which acts as a calciner, is fed with an oxygen content of 10-15% into this third entrained flow reactor 180, which also acts as a calciner. There, further secondary fuel 201 is supplied together with a portion of the raw meal 120. The raw meal 120 is also used for temperature control in this entrained flow reactor 180. After the secondary fuel 201 is ignited, the remaining raw meal 120 is added, heated, and calcined. This third entrained flow reactor 180, which also acts as a calciner, is also designed for a residence time of 4 to 8 seconds and has a burning chamber 185 at its deflection in order to support complete burning of the secondary fuel 201. For the remaining plant components of the plant 200, reference is made to the description relating to FIG. 1.FIG. 3 shows a flow diagram of the method according to the invention in a first embodiment. The method for producing cement clinker 110 from raw meal 120 comprises the following steps, starting from the provision of raw meal, a mixture of silicate-containing rock and carbonate-containing rock: preheating 10 the raw meal 120 to hot meal (122), followed by separating 20 the hot meal 122 in a cyclone separator 161 and introducing the hot meal 122 via a hot meal line 163 into an entrained flow reactor 170. This is followed by calcining 30 the hot meal 122 to deacidified raw meal 121 in the entrained flow reactor 170, which acts as a calciner. The deacidification is followed by a separation 40 of the deacidified raw meal 121 in a cyclone separator 177 following the entrained flow reactor 170 acting as a calciner in the gas flow direction. From there, sintering 50 of the separated, deacidified raw meal 121 into a rotary kiln 130 to form cement clinker 110.According to the concept of the invention, the following procedure is provided, namely preheating 10 the raw meal 120 to hot meal 122 in an entrained flow reactor 160 as a first entrained flow reactor and subjecting 55 this first entrained flow reactor 160 to the exhaust gases from the rotary kiln 130. At this point, the procedure differs from known methods for producing cement clinker 110 in that the exhaust gas from the rotary kiln 130 is not used for calcining, but rather for preheating 10, and the preheating takes place in an entrained flow reactor 160 in order to be able to withstand the high exhaust gas temperatures of the rotary kiln 130.After sintering, a method step known per se can follow, namely cooling 60 the cement clinker 110 in a clinker cooler 140 which is arranged downstream of the rotary kiln 130 in the material flow direction and subsequently introducing 65 heated cooling air as tertiary air 151 from a cooler head housing 149 of the clinker cooler 140 into the second entrained flow reactor 170 via a tertiary air line 150.In order to be able to remove waste heat from the process, four special points are suitable.A first waste heat removal point Q is located in the gas path downstream of the separator 161 of the first entrained flow reactor 160 which is used for preheating the raw meal 120, in method step 20.A second waste heat removal point Q is located in the gas path downstream of the separator 177 of the second entrained flow reactor 170, which is used for calcining raw meal / hot meal, in process step 40.A third waste heat Q removal location is located in the gas path after "cooling" in method step 60 after cooling in clinker cooler 140.A fourth waste heat removal point Q is located in the gas path of the tertiary air 150, namely in the tertiary air line in method step 65 "introduction".The waste heat Q that can be taken out at the aforementioned take-off points can be used for the operation of another method for separating carbon dioxide (CO 2) that inevitably arises in the production of cement clinker 110.FIG. 4 finally shows a flow diagram of the method according to the invention in a second embodiment. The method according to this flow chart differs from the method according to the flow chart in FIG. 3 by a further process step calcination 70; this is provided after the first calcination step 30 and separation step 40. This second calcination step increases the capacity of the second entrained flow reactor, which acts as a calciner. This is because the second entrained flow reactor 170, which acts as a calciner, is operated with a reduced temperature of the tertiary air feeding it.LIST OF REFERENCE CHARACTERS10 Preheating 20 Separating 25 Removing 30 Calcining 40 Separating 45 Removing 50 Sintering 60 Cooling 65 Introducing 66 Removing 67 Removing 70 Calcining 75 Removing 100 Plant 110 Cement clinker 120 Raw meal 121 Deacidified raw meal 122 Hot meal 130 Rotary kiln 131 Inlet chamber 140 Clinker cooler 145 Heat exchanger 146 Exhaust air 147 Cooling air 148 Gas line 149 Cooler head housing 150 Tertiary air line 151 Tertiary air 155 Heat exchanger 160 First entrained flow reactor 161 Cyclone separator 162 Raw meal feed 163 Hot meal line 165 Heat exchanger 166 Compressor 168 Gas line 169 Exhaust gas 170 Second entrained flow reactor 171 Fuel feed 172 Raw meal feed 175 Burning-out chamber 176 Descending branch 177 Cyclone separator 179 Meal line 180 Third entrained flow reactor 181 Fuel feed 182 Raw meal feed 183 Meal line 185 Heat exchanger 186 descending branch 187 cyclone separator 188 gas line 189 exhaust gas 186 compressor 200 primary fuel 201 secondary fuel 202 primary air 203 secondary air Q waste heat B fuel

Claims

Method for producing cement clinker (110) from raw meal (120), comprising the following steps: - preheating (10) the raw meal (120) to give hot meal (122), - separating (20) the hot meal (122) in a cyclone separator (161) and introducing the hot meal (122) via a hot meal line (163) into an entrained flow reactor (170), - calcining (30) the hot meal (122) to give deacidified raw meal (121) in the entrained flow reactor (170) as a calciner, - separating (40) the deacidified raw meal (121) in a cyclone separator (177) following the entrained flow reactor (170) as a calciner in the gas flow direction, - sintering (50) the separated raw meal, Deacidified raw meal (121) in a rotary kiln (130) to form cement clinker (110), characterized by - preheating (10) the raw meal (120) to form hot meal (122) in an entrained flow reactor (160) as first entrained flow reactor, - subjecting this first entrained flow reactor (160) to the exhaust gases from the rotary kiln (130).Method according to Claim 1, characterized by - cooling (60) the cement clinker (110) in a clinker cooler (140) which is arranged downstream of the rotary kiln (130) in the material flow direction, - introducing (65) heated cooling air as tertiary air (151) from a cooler head housing (149) of the clinker cooler (140) into the second airstream reactor (170) via a tertiary air line (150).Method according to Claim 2, characterized by - removing (66) waste heat (Q) from the tertiary air (151) via a heat exchanger (155) which is connected into the tertiary air line (150).Method according to Claim 2 or 3, characterized by - removing (67) waste heat (Q) from heated cooling air (147) as waste air (146) via a heat exchanger (145) which is connected into a gas line (148) for discharging waste air (146) from the cooler (140).Method according to one of Claims 2 to 4, characterized by - removing (25) waste heat (Q) from heated exhaust gas (169), which is separated off via a cyclone separator (161), from the first entrained-flow reactor (160) via a heat exchanger (165) which is connected into a gas line (168) for discharging the exhaust gas (169) from the first entrained-flow reactor (160).Method according to one of Claims 2 to 5, characterized by - removing (45) waste heat (Q) from heated exhaust gas (189) separated off via a cyclone separator (177) from the entrained-flow reactor (170) acting as a calciner via a heat exchanger (185) which is connected into a gas line (188) for discharging the exhaust gas (189) from the second entrained-flow reactor (170).Method according to one of Claims 1 to 5, characterized by - switching a third entrained-flow reactor (180) as a further calciner downstream of the entrained-flow reactor (170) acting as a calciner in the gas flow direction, - calcining (70) further raw meal (120) in the third entrained-flow reactor (180) to deacidified raw meal (121), - separating (80) the raw meal (121) deacidified in the third entrained-flow reactor (180) in a cyclone separator (187), - introducing deacidified raw meal (121) separated from the cyclone separator (187) into the rotary kiln (130).Method according to Claim 7, characterized by - removing (85) waste heat (Q) from heated exhaust gas (189) from the third entrained-flow reactor (180), which exhaust gas is separated off via a cyclone separator (187), via a heat exchanger (185) which is connected into a gas line (188) for discharging the exhaust gas (189) from the third entrained-flow reactor (180).Method according to one of the claims from claims 3 to 6 and 8, characterised byruding the waste heat (Q) removed for operation of a further method for separating and / or incorporating carbon dioxide (CO 2) from the exhaust gases produced in the method according to one of claims 1 to 8.Plant (100) for producing cement clinker (110) from raw meal (120), according to the method according to claims 1 to 9, having - at least one rotary kiln (130) for sintering deacidified raw meal (121) to cement clinker (110), - at least one clinker cooler (140) for cooling the cement clinker (110), wherein the clinker cooler (140) is arranged downstream of the rotary kiln (130) in the material flow direction, - at least one tertiary air line (150) for removing cooling air (147) heated in the cooler head housing (149) of the clinker cooler (140) as tertiary air (151), characterized in that a first entrained flow reactor (160) is arranged downstream of the rotary kiln (130) in the gas flow direction as heat exchanger, in which raw meal (120) is preheated to hot meal (122), which is in turn followed by a first cyclone separator (161) for separating the hot meal (122) in the gas flow direction, wherein a first hot meal line (163) conducts the hot meal (122) into a second entrained flow reactor (170) as calciner, which is itself connected to the tertiary air line (150) and is fed with tertiary air (151) therefrom, and wherein a meal line (179) conducts deacidified raw meal (121) originating from the second entrained flow reactor (170) acting as calciner into the rotary kiln (130).Plant according to Claim 10, characterized in that the second entrained-flow reactor (170) acting as a calciner has a fuel feed (171) for secondary fuel (201).Plant according to Claim 10 or 11, characterized in that the second entrained-flow reactor (170) acting as calciner has a raw meal feed (172).Plant according to one of Claims 10 to 12, characterized in that the second entrained-flow reactor (170) acting as a calciner is followed in the gas flow direction by a third entrained-flow reactor (180), which has a fuel feed (181) for secondary fuel (201) and a raw meal feed (182) for raw meal (120), wherein a meal line (183) conducts deacidified raw meal (121) originating from the third entrained-flow reactor (180) into the rotary kiln (130).Plant according to one of Claims 10 to 13, characterized in that a respective heat exchanger (145, 165) is connected downstream in a gas line (148, 168) in the gas flow direction in the gas path of the clinker cooler (140) and of the first entrained-flow reactor (160), via which heat (Q) for the operation of a further plant for separating carbon dioxide (CO 2) is separated.Plant according to one of Claims 10 to 14, characterized in that a heat exchanger (155) is connected into the tertiary air line (150), via which heat (Q) is separated for the operation of a further plant for separating carbon dioxide (CO 2).Plant according to claim 13, characterised in that a heat exchanger (185) is connected in a gas line (188) in the gas flow direction in the gas path of the third entrained flow reactor (180), via which heat (Q) for the operation of a further plant for separating carbon dioxide (CO 2) is separated.

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