Shaft furnace and method for calcining carbonate-containing material in a shaft furnace

Abstract

The invention relates to a shaft furnace (1) for calcining in particular carbonate-containing material, with a shaft (2) having, in the flow direction of the material, a material inlet (3), a preheating zone (21) for preheating the material, a calcining zone (20) for calcining the material, a cooling zone (22) for cooling the calcined material, and a material outlet (40) for discharging the material from the shaft furnace (1), wherein the shaft furnace (1) has a waste-gas outlet (19) for discharging waste gas from the preheating zone of a shaft (2), wherein the shaft (2) has an inner cylinder (58), which extends centrally through the shaft (2) and is gas-technically connected to a cooling-gas line such that cooling gas flows into the inner cylinder (58) and wherein the inner cylinder (58) is gas-technically separate from the area of the shaft (2) that is filled with material.

Description

[0001] Shaft kiln and method for burning carbonate-containing material in a shaft kiln

[0002] The invention relates to a shaft kiln with at least one shaft and a method for burning limestone or other carbonates, with a shaft kiln having at least one firing zone and a cooling zone.

[0003] From CH 378 217 A a shaft furnace for the continuous firing of mineral materials with a firing zone and a cooling zone is known.

[0004] The lime industry currently requires lime kilns with a high throughput of at least 400 to 800 tons per day. Furthermore, highly reactive lime is desired, while the resulting exhaust gas should simultaneously have a high CO2 concentration to enable subsequent cost-effective carbon capture and storage. Another global goal is to reduce overall CO2 emissions. Current lime kilns are maintenance-intensive and also incur high manufacturing costs.

[0005] It is therefore the object of the present invention to provide a shaft furnace and a method for burning and / or calcining carbonate rock, wherein the shaft furnace can be manufactured cost-effectively and requires low maintenance.

[0006] This problem is solved according to the invention by a shaft furnace with the features of independent apparatus claim 1 and by a method with the features of independent method claim 14. Advantageous embodiments are described in the dependent claims.

[0007] The shaft kiln for firing materials, particularly those containing carbonate, comprises, according to a first aspect, a shaft with a material inlet, a preheating zone for preheating the material, a firing zone for firing the material, a cooling zone for cooling the fired material, and a material outlet for discharging the material from the shaft kiln. The shaft kiln has an exhaust gas outlet for releasing exhaust gas from the preheating zone of the shaft. The shaft has an inner cylinder extending centrally through the shaft and connected to a cooling gas line, allowing cooling gas to flow into the inner cylinder. The inner cylinder is preferably completely separated from the process chamber, particularly the material-filled area of ​​the shaft, by means of gases.The cooling gas line is preferably connected to a cooling gas source, such as ambient air, and in particular to a fan. The process chamber filled with material preferably has an annular, especially circular, cross-sectional area and is preferably designed as an annular shaft. The inner cylinder is preferably gas-tightened from the annular shaft area of ​​the shaft so that no process gas flows into the inner cylinder. Process gas is understood to be the gas used for lime production, which flows inside the annular space, especially in the void volume of the material being burned, and interacts thermally and chemically with the material to produce lime. The interior of the inner cylinder is preferably filled exclusively with cooling gas.

[0008] The cooling air-conducting inner cylinder offers the advantage of efficient cooling, creating a uniformly heated annular shaft area filled with material and enabling the production of lime of consistently high quality. Additionally, an inner cylinder filled exclusively with cooling air and separated from the process chamber by gases requires comparatively little maintenance, as it is not contaminated by dust particles and experiences little to no material buildup inside.

[0009] The shaft kiln is, for example, a single-shaft kiln. The material to be fired is, for example, limestone or dolomite, particularly with a grain size of 10 to 200 mm, preferably 15 to 120 mm, and most preferably 20 to 100 mm. The exhaust gas preferably has a CO2 content of 25%, optionally at least 35% to 45%, preferably at least 90%, and ideally more than 95%, for example, based on dry gas. The material inlet is located, in particular, at the upper end of the shaft. A preheating zone is located upstream of the combustion zone in the direction of material flow. The preheating zone preferably connects directly to the material inlet into the shaft kiln and serves to preheat the material to a temperature of approximately 600°C to 800°C.The combustion zone preferably connects directly to the preheating zone and serves for the combustion, in particular calcination, of the material, which is preferably heated to a temperature of approximately 900°C to 1700°C, particularly a maximum of 1200°C. The cooling zone preferably connects directly to the combustion zone and serves to cool the combustion material to a temperature of, for example, 100°C. Optionally, a gas separation zone is arranged between the cooling zone and the combustion zone, in which mostly combustion gases from the combustion zone and no or only a very small proportion of cooling gas from the cooling zone flow. The material outlet is arranged, for example, in an outlet hopper connected to the cooling zone, wherein the material outlet has, for example, a rotary table or push tables for discharging material from the cooling zone into the outlet hopper.The cooling gas, in particular cooling air, is preferably blown into the cooling zone of the shaft furnace via a cooling air inlet.

[0010] The material inlet and / or outlet is / are designed, in particular, as an airlock for introducing and / or discharging material into the shaft furnace. A material inlet designed as an airlock is preferably configured such that only the raw material to be burned enters the shaft, but not the ambient air. Preferably, the airlock is designed to seal the shaft airtight against the environment while allowing solids, such as the material to be burned, to enter the shaft.

[0011] An exhaust gas outlet duct preferably connects to the exhaust gas outlet located in the preheating zone to guide the exhaust gas drawn from the shaft, particularly the preheating zone. The exhaust gas discharged from the preheating zone via the exhaust gas outlet preferably has a temperature of approximately 100°C to 400°C. The exhaust gas outlet duct includes, for example, a compressor, particularly a fan, and an exhaust gas filter downstream of the exhaust gas outlet in the direction of flow. Preferably, a cooling device, such as a water-cooled heat exchanger, is connected downstream in the direction of flow. The cooling device preferably cools the exhaust gas to a temperature of 30°C. Preferably, a partial flow of the exhaust gas is diverted, and another partial flow is preferably fed to the combustion zone via at least one further fan or compressor and an exhaust gas duct.

[0012] For example, the exhaust gas released from the preheating zone of the shaft via the exhaust gas outlet is at least partially heated by the hot gas generator or a heat exchanger and fed into the combustion zone. Alternatively, the exhaust gas from the preheating zone can be partially discharged from the shaft furnace or fed into the combustion zone. Feeding exhaust gas to the hot gas generator or the combustion zone offers an energy-efficient way to utilize the exhaust gas.

[0013] The exhaust gas has, for example, a CO2 content of at least 90 vol%, in particular at least 95 vol% up to preferably 99 vol% or 100 vol%. This enables subsequent cost-effective liquefaction and storage of the CO2-rich exhaust gas. Preferably, only a portion of the exhaust gas, for example approximately 20% to 80%, in particular 50%, is returned to the combustion zone, with the remaining portion of the exhaust gas being discharged from the shaft furnace and stored, for example, for subsequent sequestration in a storage tank.

[0014] According to a first embodiment, the inner cylinder extends from the cooling zone through the combustion zone into the preheating zone. Preferably, the inner cylinder is designed as a material-free space. Preferably, the inner cylinder has a constant cross-section. The inner cylinder is, in particular, arranged coaxially with the shaft wall.

[0015] According to a further embodiment, the inner cylinder has a separating agent that extends through the inner cylinder and separates a first cooling channel from a second cooling channel. The separating agent is, for example, designed as a partition wall or a separating tube. The separating agent preferably extends entirely in a vertical direction. The inner cylinder preferably comprises the first and the second cooling channels, which extend vertically, particularly parallel or coaxially to each other. In particular, the separating agent is made of a thermally conductive material, so that heat exchange occurs between the first and the second cooling channels. The first and the second cooling channels are preferably arranged and configured such that the cooling gas flows counter-currently to the second cooling channel within the first cooling channel. The separating agent, designed as a separating tube, is preferably arranged coaxially with the inner cylinder.In particular, a cooling channel, for example the first cooling channel, is formed in the annular space between the wall of the inner cylinder and the wall of the separating tube, wherein a further cooling channel, in particular the second cooling channel, is formed inside the separating tube.

[0016] According to a further embodiment, the inner cylinder has a cooling gas inlet for introducing cooling gas into the inner cylinder, wherein the cooling gas inlet is arranged in or above the preheating zone, or in or below the cooling zone. Preferably, the cooling gas inlet is arranged at the upper or lower end of the inner cylinder. In particular, the cooling gas inlet is connected to the cooling gas line. The cooling gas inlet is, for example, designed as a cooling gas inlet line that extends, in particular, from the inner cylinder through the shaft wall and preferably runs in a radial direction. The cooling gas inlet line is preferably a straight pipe. The cooling gas inlet line extends, in particular, radially through the preheating zone or through the annular shaft area above the preheating zone.The inner cylinder is connected to the cooling gas inlet line for the supply of cooling gas, particularly cooling air, such that the cooling gas flows into the inner cylinder. Specifically, the cooling gas inlet line extends through a cooling gas inlet opening in the shaft, with the cooling gas inlet being located in or above the preheating zone or in or below the cooling zone. The cooling gas inlet line extends from the inner cylinder through the preheating zone or the cooling zone and out of the shaft, and is preferably completely separated from the annular shaft section of the shaft filled with material. According to a further embodiment, the inner cylinder has a cooling gas outlet for releasing cooling gas from the inner cylinder, and the cooling gas outlet is located in or above the preheating zone or in or below the cooling zone.Preferably, the cooling gas outlet is arranged at the upper or lower end of the inner cylinder. The cooling gas outlet is, for example, designed as a cooling gas outlet line that extends from the inner cylinder through the shaft wall and preferably in a radial direction. The cooling gas outlet line extends, in particular, radially through the preheating zone, through the annular shaft area above the preheating zone, or through the cooling zone. The inner cylinder is connected, in particular, to the cooling gas outlet line for conveying cooling gas, especially cooling air, such that the cooling gas flows out of the inner cylinder. In particular, the cooling gas outlet line extends through a cooling gas outlet opening in the shaft, with the cooling gas outlet being arranged in or above the preheating zone or in or below the cooling zone.The cooling gas outlet line extends from the inner cylinder through the preheating zone or the cooling zone and out of the shaft, preferably being completely separated from the material-filled annular shaft area of ​​the shaft. Positioning the cooling gas inlet and outlet in or above the preheating zone or in or below the cooling zone ensures that the cooling gas flows through the inner cylinder from the level of the preheating zone to the level of the combustion zone, where it is heated. The cooling gas then flows within the inner cylinder through the cooling zone, is cooled again, and flows once more through the combustion zone and the preheating zone out of the inner cylinder. This achieves highly efficient cooling of the inner cylinder.

[0017] According to a further embodiment, the separating agent is spaced apart from the lower or upper end of the inner cylinder, so that the cooling channels are gas-connected, preferably exclusively, at the lower or upper end of the inner cylinder. Within the inner cylinder, the cooling gas preferably flows in opposite directions in the two cooling channels. With a separating agent designed as a partition and a cooling gas inlet and outlet located at the upper end of the inner cylinder, the cooling gas flows from top to bottom in the first cooling channel and from bottom to top in the second cooling channel. The cooling gas is preferably deflected within the inner cylinder, preferably at the level of the cooling zone or the preheating zone, by a deflection of preferably 180°, thereby lengthening the cooling gas line running through the cooling zone or preheating zone and thus achieving efficient cooling of the preheated cooling gas.

[0018] According to a further embodiment, at least one beam-shaped flow element is arranged and configured within the shaft such that a material-free space is formed below the flow element, and the flow element and / or the material-free space is each connected to a respective gas inlet for introducing gas into the shaft or to a respective gas outlet for releasing gas from the shaft. The material-free space preferably serves to guide gas within the shaft to a gas outlet or a gas inlet.

[0019] The shaft furnace preferably has a plurality of beam-shaped flow elements within the shaft. The at least one flow element extends, in particular, through the process chamber of the shaft, preferably from the inner cylinder in a radial direction outwards to the shaft wall. No beam-shaped flow element is arranged within the inner cylinder. Preferably, the flow elements are constructed of masonry, in particular of refractory material. The at least one flow element preferably extends completely, and in particular exclusively, through the area of ​​the shaft filled with material to be burned.

[0020] A beam-shaped element is defined as having a length that is large relative to its cross-section, particularly its diameter. For example, the length of a beam-shaped flow element is at least 1.5 to 5 times greater than its cross-section, particularly its diameter. The cross-sectional area is either constant or variable along the length of the flow element. At least one beam-shaped flow element within the shaft offers the advantage that, during operation of the shaft furnace, a material-free space forms below the flow element, from which a gas flow can be easily drawn into or supplied to the shaft. The use of beam-shaped flow elements is comparatively inexpensive and requires little maintenance.

[0021] According to a further embodiment, the shaft furnace has a hot gas chamber in which a burner lance for combustion of fuel is arranged or which is connected to a hot gas generator via a gas supply system, and wherein the hot gas chamber is preferably located exclusively in the material-free space outside the shaft, in particular outside the interior of the shaft. The hot gas chamber is preferably arranged below the flow element. The flow element preferably extends outwards through at least one shaft wall into an area outside the interior of the shaft. The shaft preferably has vertical shaft walls that delimit the interior of the shaft. The shaft preferably has a cross-sectional area that is essentially constant in the vertical direction and optionally tapers upwards.In particular, the preheating zone and / or the upper area of ​​the combustion zone has a smaller cross-sectional area than the rest of the shaft area.

[0022] The hot gas generator is, for example, an electrically operated hot gas generator, where the hot gas is generated, for instance, by a plasma. Optionally, the hot gas generator is operated using a solid fuel. The hot gas generator is preferably located entirely outside the shaft. The hot gases generated in the hot gas generator are preferably directed into the hot gas chamber. The fuel is, for example, a gaseous fuel such as natural gas or hydrogen.

[0023] In addition to the material-free spaces formed below the flow elements, the shaft wall preferably has one or more outwardly projecting expansions in the shaft cross-section, in which additional hot gas chambers are formed. Preferably, one or more hot gas chamber levels are arranged in the shaft, in which material-free spaces, in particular hot gas chambers, are arranged circumferentially around the combustion zone. For example, the hot gas chamber is designed as a combustion chamber, with burner lances preferably arranged within each combustion chamber, which are in particular connected to a fuel line for supplying fuel gas. Optionally, the hot gas chambers are connected to a hot gas generator, for example, an electrically operated one. For example, each hot gas chamber level comprises at least one or two to eight hot gas generators. The term "material-free" preferably means "free of combustible material."A material-free space is preferably a space in which no combustible material is present. The material-free space has, in particular, a plurality of gas inlets through which, in particular, recirculated and heated exhaust gas is introduced into the combustion zone. Optionally, at least one burner lance designed as a side burner is provided between the hot gas chambers / combustion chambers of a hot gas chamber level. This lance extends into the shaft, in particular the combustion zone, and is designed for the combustion of fuel in the shaft.

[0024] According to a further embodiment, the shaft furnace has a recirculating gas outlet for releasing gas from the combustion zone and a recirculating gas inlet for introducing the gas released via the recirculating gas outlet into the combustion zone. The recirculating gas outlet is formed in the shaft wall and is fluidically connected to the free space such that exhaust gas from the combustion zone, preferably directly from the process chamber, flows into the free space below the flow element and preferably directly into the recirculating gas outlet. Preferably, the shaft furnace has at least one or more recirculating gas outlets, particularly at the same height, with each recirculating gas outlet being associated with a free space formed below a respective flow element. The recirculating gas outlet is preferably directly connected to the process chamber via the respective free space.Preferably, the shaft furnace has at least one or a plurality of circulating gas inlets, each of which is associated with a material-free space located below a respective flow element. The circulating gas outlet is preferably connected directly to the process chamber via the respective material-free space. The plurality of circulating gas inlets are preferably arranged at the same height.

[0025] The shaft furnace preferably has a recirculation device for circulating recirculating gas within the combustion zone, wherein the recirculation device is connected to a gas injector so that the exhaust gas discharged from the preheating zone is at least partially introduced into the combustion zone together with the recirculating gas. For example, the shaft furnace has a plurality of, in particular two, recirculation devices. For example, a further recirculating gas device is provided in the shaft furnace, which is designed and arranged for circulating recirculating gas within the preheating zone or between the preheating zone and the combustion zone.

[0026] The circulating gas is preferably gas from the combustion zone, particularly the lower region of the combustion zone adjacent to the cooling zone, or gas from the preheating zone. The circulating gas preferably consists primarily of CO2, especially since no cooling gas from the cooling zone enters the combustion zone. It is also conceivable that the circulating gas consists of exhaust gas from the combustion zone and cooling gas. Preferably, the combustion zone comprises a counterflow combustion zone and a directly adjoining coflow combustion zone in the direction of material flow. The circulating gas is preferably drawn exclusively from the coflow combustion zone and, in particular, fed exclusively back to the coflow combustion zone. Optionally, the circulating gas is drawn exclusively from the coflow combustion zone and fed back to both the counterflow and coflow combustion zones.

[0027] The recirculating gas system is preferably designed such that it accelerates the recirculating gas outside the shaft, particularly outside the combustion zone, from the recirculating gas outlet to the recirculating gas inlet. In particular, the recirculating gas system is designed such that it draws in the recirculating gas at the recirculating gas outlet.

[0028] According to a further embodiment, the recirculating gas outlet is arranged below the recirculating gas inlet. A recirculation device is preferably arranged between the recirculating gas inlet and the recirculating gas outlet. This device is gas-connected to both the recirculating gas outlet and the recirculating gas inlet and is designed and configured to accelerate the recirculating gas from the recirculating gas outlet to the recirculating gas inlet. Preferably, the recirculating gas device is designed to draw in the recirculating gas at the recirculating gas outlet.

[0029] The shaft furnace preferably has an injector, which is designed and arranged specifically to accelerate the circulating gas towards the circulating gas inlet into the combustion zone. The injector preferably has a cross-sectional constriction or is, in particular, nozzle-shaped. Accelerating the circulating gas causes a reduction in pressure at the circulating gas outlet, so that a gas flow develops within the combustion zone towards the circulating gas outlet. The circulating device is preferably connected to the injector and the exhaust gas outlet of the shaft furnace via a gas supply system, so that the exhaust gas discharged from the preheating zone is at least partially introduced into the combustion zone together with the circulating gas.

[0030] This gas flow creates the co-current combustion zone between the recirculating gas inlet and outlet. Preferably, the gas within the co-current combustion zone has a temperature of approximately 900°C to 1200°C. The calcination of the material in the counter-current combustion zone and the subsequent further calcination in the co-current combustion zone enables the production of highly reactive quicklime. The recirculation device is preferably connected to the exhaust gas outlet via an exhaust gas line, so that the exhaust gas is introduced into the combustion zone at least partially together with the recirculating gas.

[0031] The exhaust gas line is connected, for example, to a heat exchanger for heating the exhaust gas. The heat exchanger is preferably connected to the cooling gas exhaust system, so that the exhaust gas is heated in the heat exchanger, particularly in counterflow to the extracted cooling air. Preferably, the exhaust gas is heated in the heat exchanger to a temperature of approximately 400°C to 700°C, particularly 500°C. Optionally, the combustion zone has a gas inlet for introducing exhaust gas discharged via the exhaust gas outlet into the combustion zone. The gas inlet is preferably arranged separately from the recirculating gas inlet in the combustion zone.

[0032] According to a further embodiment, the combustion zone comprises a counterflow combustion zone and a coflow combustion zone in the direction of material flow, wherein at least one flow element is arranged in the counterflow combustion zone, in which the material is subjected to counterflow by gases, and / or in the coflow combustion zone, in which the material is subjected to coflow by gases. The recirculating gas outlet is preferably arranged in the coflow combustion zone.

[0033] According to a further embodiment, a gas separation zone is arranged between the combustion zone and the cooling zone, wherein at least one beam-shaped flow element is arranged in the gas separation zone, in which preferably mostly combustion gases from the combustion zone and no or only a very small proportion of cooling gas from the cooling zone flow. Such a gas separation zone enables a reliable separation of the combustion gases and the cooling gases, so that no or only very minimal recarbonization of the burned material can occur.

[0034] According to a further embodiment, the preheating zone and / or the cooling zone each have at least one flow element. Preferably, two or four flow elements are arranged in the preheating zone. In the cooling zone, in particular, exactly two, four, or more flow elements are arranged, which, for example, extend radially.

[0035] According to a further embodiment, the shaft furnace has a plurality of flow element levels, with at least one flow element or a plurality of flow elements arranged in each flow element level. In particular, the shaft furnace has four, five, or eight flow element levels, which are preferably arranged one behind the other in the direction of material flow. The flow element levels are preferably arranged at uniform intervals from one another in the longitudinal direction of the shaft furnace. The first, and in particular the uppermost, flow element level is preferably arranged in the preheating zone or the combustion zone. The combustion zone comprises, for example, in the direction of material flow, a first combustion zone and a second, which are configured as counter-current combustion zones, and a third combustion zone adjoining the second combustion zone, which is configured as a co-current combustion zone.

[0036] The shaft preferably has two, four, or up to eight hot gas chambers in the flow element plane, which are particularly located at the outwardly facing ends of the material-free spaces below the flow elements. The material-free space of the flow element plane preferably extends into the hot gas chambers.

[0037] In particular, the uppermost flow element level forms the boundary between the preheating zone and the combustion zone, especially the first combustion zone. Optionally, only one flow element is arranged in the first flow element level. In particular, the first flow element level has four or up to eight flow elements extending radially, especially in a star-shaped pattern. Preferably, the at least one flow element of the first flow element level extends from a gas outlet for exhaust gas from the combustion zone in the shaft wall to an opposite gas outlet in the opposite shaft wall.

[0038] The second flow element level is preferably arranged in the first combustion zone or the second combustion zone. Preferably, one flow element level forms the boundary between the first combustion zone and the second combustion zone, with optionally only one flow element being arranged in the flow element level. Preferably, the flow element of the flow element level of the first combustion zone and the second combustion zone extends from a gas inlet for introducing gas, in particular recirculated exhaust gas, in the shaft wall to the inner cylinder.

[0039] Another flow element layer is located particularly in the second or third combustion zone. For example, the flow element layer forms the boundary between the second and third combustion zones.

[0040] A further flow element layer is preferably arranged in the third combustion zone or the gas separation zone. This flow element layer particularly forms the boundary between the combustion zone, especially the third combustion zone, and the gas separation zone.

[0041] Another flow element level is located particularly in the gas separation zone or the cooling zone. For example, the flow element level forms the boundary between the gas separation zone and the cooling zone.

[0042] The invention also includes a method for burning, in particular carbonate-containing, material in a shaft furnace with at least one shaft, wherein the material flows through a material inlet into a preheating zone for preheating the material, a combustion zone for burning the material and a cooling zone for cooling the burned material to a material outlet, wherein cooling air is admitted into the cooling zone, wherein the exhaust gas is released from the preheating zone of a shaft via an exhaust gas outlet, and a cooling gas flows through an inner cylinder and is gas-technically separated from the area of ​​the shaft filled with material.

[0043] The advantages and features described with reference to the device also apply to the method in accordance with the procedure.

[0044] According to another embodiment, the cooling gas flows through the inner cylinder between the cooling zone and the preheating zone. According to a further embodiment, the cooling gas flows within the inner cylinder in a first cooling channel and a second cooling channel, which is separated from the first cooling channel by a separating element, such as a separating tube or a partition.

[0045] According to another embodiment, the cooling gas flows in the first cooling channel in counterflow to the second cooling channel.

[0046] According to another embodiment, the cooling gas flows into the first cooling channel at the upper or lower end of the inner cylinder and out of the inner cylinder through the second cooling channel at the upper or lower end of the inner cylinder.

[0047] According to a further embodiment, a circulating gas is discharged from the combustion zone via a circulating gas outlet and preferably introduced into the combustion zone via a circulating gas inlet together with the exhaust gas discharged via the exhaust gas outlet, wherein the circulating gas is directed from the process chamber directly into the material-free space and to the circulating gas outlet. Preferably, the process gas within the material-free space, which is directly connected to the circulating gas outlet, is directed exclusively outwards in a radial direction.

[0048] Preferably, a recirculating gas is drawn off from the combustion zone and introduced into the combustion zone together with the exhaust gas by means of an injector. Preferably, the recirculating gas is drawn off at the lower part of the combustion zone, particularly the third combustion zone, and reintroduced at an upper part of the combustion zone, particularly between the second and third combustion zones. The injector is, for example, a nozzle designed and arranged such that it draws in the gas flow from the lower part of the combustion zone and accelerates it into the upper part. This preferably creates a co-current combustion zone within the combustion zone, in which the heated gas flows in parallel with the material being burned. A co-current combustion zone ensures particularly uniform and complete calcination of the material.When circulating gas is present within part of the combustion zone, calcination of the material is enabled at low temperatures of approximately 900°C to 1100°C, giving the finished product a high reactivity, as required, for example, for applications in steelworks.

[0049] The shaft furnace preferably has a cooling gas exhaust device for releasing cooling air from the shaft. The cooling gas exhaust device is designed, for example, as a material-free space in the cooling zone, particularly in the flow element plane between the cooling zone and the combustion zone or the gas separation zone. The cooling air from the cooling zone is preferably completely released from the shaft via the cooling gas exhaust device, so that no cooling air enters the combustion zone.

[0050] Description of the drawings

[0051] The invention is explained in more detail below with reference to several exemplary embodiments and the accompanying figures.

[0052] Fig. 1 shows a schematic representation of a shaft furnace in a longitudinal section view according to an exemplary embodiment.

[0053] Fig. 2a shows a schematic representation of a shaft furnace in a longitudinal sectional view according to the embodiment of Fig. 1.

[0054] Fig. 2b shows a schematic representation of the flow elements of the shaft furnace in a developed annular section according to a further embodiment.

[0055] Figs. 2c-e show schematic representations of further embodiments of the shaft furnace.

[0056] Fig. 3a-e shows schematic representations of a shaft furnace in several cross-sectional views of different planes according to further embodiments.

[0057] Fig. 4 shows a schematic representation of a shaft furnace in a longitudinal section view according to an exemplary embodiment.

[0058] Figures 1 and 2a show a shaft kiln 1, in particular an annular shaft kiln. The shaft kiln 1 for firing granular material comprises a shaft 2, which preferably extends vertically and has, for example, a substantially constant cross-section. For example, the shaft 2 has a round, in particular circular, or angular, in particular square, cross-section. The shaft 2 is surrounded by a shaft wall, which is, for example, made of steel with an adjoining refractory, brick-lined inner wall. The shaft kiln 1 is preferably used to achieve high throughput rates, such as 1000 t / d, and is designed as an annular shaft kiln. The annular shaft section 60 of the shaft 2, filled with material, has a ring-shaped or angular cross-section. The shaft kiln 2 of the figure1 and 2a further feature an inner cylinder 58 that extends centrally through the shaft 2 and is, in particular, free of material. The inner cylinder 58 extends, for example, from the cooling zone 22 through the combustion zone 20 into the preheating zone 21. Preferably, the inner cylinder 58 has a constant cross-section. The inner cylinder is preferably gas-tightened from the annular shaft area 60 of the shaft 2, so that no process gas flows into the inner cylinder 58.

[0059] The inner cylinder 58 preferably has a separating element 55, such as a partition 55, which extends through the inner cylinder and separates a first cooling channel from a second cooling channel. The inner cylinder 58 is preferably connected to a cooling gas inlet line 47 for conveying cooling gas, in particular cooling air, such that the cooling gas flows into the inner cylinder 58. The inner cylinder 58 is preferably designed exclusively for conveying cooling gas. The cooling gas inlet line 47 is preferably arranged in or above the preheating zone 21. For example, the cooling gas inlet line 47 extends through a cooling gas inlet opening 44 in the shaft 2, wherein the cooling gas inlet opening 44 is arranged in or above the preheating zone 21.The cooling gas inlet line 47 extends in particular from the inner cylinder 58 through the preheating zone 21 out of the shaft 2 and is preferably not connected in terms of gas technology to the annular shaft area 60 of the shaft 2 filled with material.

[0060] The inner cylinder 58 is connected, in particular, to a cooling gas outlet line 37 for conveying cooling gas, especially cooling air, such that the cooling gas flows out of the inner cylinder 58. The cooling gas outlet line 37 is preferably arranged in or above the preheating zone 21. By way of example, the cooling gas outlet line 37 extends through a cooling gas outlet opening 59 in the shaft 2, wherein the cooling gas outlet opening 59 is arranged in or above the preheating zone 21. The cooling gas outlet line 37 extends, in particular, from the inner cylinder 58 through the preheating zone 21 and out of the shaft 2, and is preferably not connected to the annular shaft area 60 of the shaft 2, which is filled with material.

[0061] The partition 55 is preferably spaced apart from the bottom of the inner cylinder 58, so that the cooling channels at the lower end of the inner cylinder 58 are gas-connected. Inside the inner cylinder 58, the cooling gas preferably flows in opposite directions in the two cooling channels, in particular from top to bottom in the first cooling channel and from bottom to top in the second cooling channel.

[0062] The shaft 2 preferably has a material inlet 3 at its upper end, which is designed, for example, as the upper opening of the shaft 2 and, in particular, as an airlock 3, and preferably extends over the entire or a part of the cross-section of the shaft 2. The material inlet 3 serves to introduce material to be burned into the shaft furnace 1. A material inlet designed as an airlock 3 is preferably configured such that only the raw material to be burned enters the shaft 2, but not the ambient air. Preferably, the airlock 3 is designed such that it seals the shaft 2 airtight against the environment and allows the entry of solids, such as the material to be burned, into the shaft.

[0063] Shaft 2 has, by way of example, an exhaust gas outlet 19 in its upper section for removing furnace exhaust gas from the shaft. The exhaust gas is routed from the exhaust gas outlet 19 into an exhaust gas outlet line 39. A process chamber 56, completely filled with material, is formed within the shaft 2. Within the shaft 2, the material to be fired is conveyed downwards by gravity from top to bottom. In the direction of material conveyance, the shaft 2 has a preheating zone 21 for preheating the material, a combustion zone 20 for firing the material, and a cooling zone 22 for cooling the fired material. The preheating zone 21 preferably extends from the material inlet 3 to the combustion zone 20 and serves to preheat the material before firing. In contrast to the preheating zone 21, firing, in particular calcination, preferably by deacidification, of the material takes place in the combustion zone 20.The combustion zone 20 comprises, for example, in the direction of material flow, a first combustion zone 20a, in which the material is subjected to countercurrent gas flow, a second combustion zone 20b, in which the material is subjected to countercurrent gas flow, and a third combustion zone 20c, in which the material is subjected to cocurrent gas flow. For example, a gas separation zone 48 is arranged between the combustion zone 20, particularly the third combustion zone 20c, and the cooling zone 22. Preferably, during operation of the shaft furnace 2, the gas separation zone 48 contains mostly or exclusively exhaust gas from the combustion zone 20 and only a small proportion or no cooling air.

[0064] Fig. 2b shows flow elements 16 in a flow element plane in a circular, developed section looking outwards. The shaft furnace 1 has, by way of example, at least one or more flow elements 16 within the shaft 2. The flow elements 16 are preferably beam-shaped and extend, in particular, radially. Preferably, the flow elements 16 are constructed of masonry, in particular of refractory material.

[0065] A beam-shaped element is understood to be one that has a length that is large in relation to its cross-section, particularly its diameter. For example, the length of the beam-shaped flow element 16 is at least 1.5 to 5 times greater than its cross-section, particularly its diameter. The cross-sectional area is, for example, constant or variable along the length of the flow element 16.

[0066] The beam-shaped flow elements 16 have, for example, a U-shaped cross-sectional profile, with the U-shaped cross-sectional profile being open downwards. In particular, all flow elements 16 of the shaft furnace 2 are identically designed and extend radially. The flow elements 16 preferably have an upwardly tapered, in particular wedge-shaped or roof-shaped, geometry. Preferably, each flow element 16 forms a material-free space 49 below the respective flow element 16. The flow elements are preferably arranged within the shaft such that they are open to material flow.Preferably, the flow elements 16 are arranged within the shaft 2 such that material rests against the upward-facing surface and / or the side surfaces of the flow elements 16 and, in particular, flows away from them, with a material-free space 49 being formed on the downward-facing surface of the flow element 16. The flow elements 16 preferably extend from the, in particular, outer, shaft wall of the shaft 2 into the interior of the shaft 2 up to the outer wall of the inner cylinder 58. In particular, the flow elements 16 are attached to the outer wall of the shaft 2. The beam-shaped flow element 16 is preferably straight, so that it extends exclusively in a flow element plane 5.

[0067] The flow elements 16 and / or the material-free spaces 49 below the flow elements 16 are each fluidically connected to a respective gas inlet 15, 17 or gas outlet 12, 18, 36. Together with the material-free spaces 49, the flow elements 16 form gas channels for introducing or releasing gas into or out of the shaft 2.

[0068] The shaft furnace 2 has, by way of example, a plurality of flow element levels 5a-e, wherein at least one or more flow elements 16 are arranged in each flow element level 5a-e. The flow elements 16 of a flow element level 5a-e are preferably identical to one another and preferably arranged at the same level. By way of example, the flow elements 16 have a cross-sectional area that decreases radially inwards towards the inner cylinder 58. In particular, the shaft furnace 2 has five flow element levels, which are preferably arranged one behind the other in the flow direction of the material. The flow element levels 5a-e are, by way of example, arranged at uniform intervals from one another in the longitudinal direction of the shaft furnace 2. The first, in particular the uppermost, flow element level 5a is preferably arranged in the preheating zone 21 or the combustion zone 20, in particular the first combustion zone 20a.By way of example, the uppermost flow element level 5a forms the boundary between the preheating zone 21 and the combustion zone 20, in particular the first combustion zone 20a. In each flow element level 5a-e, exactly four flow elements 16 are arranged, extending radially and spaced uniformly apart circumferentially. Fig. 3a shows a shaft cross-section in the first flow element level 5a. Preferably, the flow elements 16 of the first flow element level 5a extend from a respective gas outlet 12 in the shaft wall to the inner cylinder 58. The gas outlet 12 is arranged for releasing exhaust gas from the combustion zone 20 out of the shaft 2. Optionally, the shaft furnace 2 does not have a gas outlet 12, in which case the flow element level 5a between the preheating zone 21 and the combustion zone 20 is omitted.In this case, the uppermost flow element level is arranged within the combustion zone 20, in particular between the first and the second co-current combustion zone 20a, b.

[0069] In the direction of material flow, a second flow element level 5b adjoins the first flow element level 5a, preferably located in the first combustion zone 20a or the second combustion zone 20b. By way of example, the second flow element level 5b forms the boundary between the first combustion zone 20a and the second combustion zone 20b. Fig. 3b shows a shaft cross-section in the second flow element level 5b. Preferably, the flow elements 16 of the second flow element level 5b extend from a gas inlet 15 in the shaft wall to the inner cylinder 58. The gas inlet 15 is arranged for introducing gas, in particular recirculated exhaust gas from the combustion zone 20, into the shaft 2. The shaft wall preferably has four outwardly projecting, in particular radial, expansions of the shaft cross-section in the second flow element level 5b, into each of which a beam-shaped flow element 16 opens.Each of the widened sections is exemplified by a combustion chamber 8. The shaft 2 preferably has two or four combustion chambers 8 in the second flow element level 5b, which are arranged, for example, at uniform circumferential intervals. Each combustion chamber 8 contains a burner lance 10, which is connected to the gas inlet 15 for introducing recirculated exhaust gas enriched with oxygen via an oxidizer line 24. The material-free space 49 of the second flow element level 5b preferably extends into the combustion chamber 8.

[0070] Figures 2c to 2e show further embodiments of a shaft furnace 1. The shaft furnace 2 of Figure 2c corresponds essentially to the shaft furnace 2 of Figures 1 and 2a, with the difference that the separating element 55 is designed as a separating tube arranged coaxially to the inner cylinder 58. The cooling gas outlet line 37 and the cooling gas inlet line 47 are, by way of example, attached to the lower end of the inner cylinder 58 and extend at least partially through the cooling zone 21 and the outlet funnel. By way of example, the separating tube 55 is connected to the cooling gas outlet line 37, and the annular space around the separating tube 55 is connected to the cooling gas inlet line 47.

[0071] The shaft furnace 1 of Fig. 2d corresponds essentially to the shaft furnace 2 of Fig. 2, with the difference that a further recirculation device 54a is provided, which is arranged and designed for recirculating gas from the preheating zone 21. The recirculation device 54a corresponds essentially to the recirculation device 54 described with reference to Figs. 1 and 2a. The shaft furnace 2 of Fig. 2d has, by way of example, a further recirculation gas outlet 18a, which is arranged at the lower end of the preheating zone 21 or at the upper end of the combustion zone 22. In addition, the shaft furnace has a further recirculation gas inlet 17a, which is arranged at the upper end of the preheating zone 21. The recirculation gas inlet 17a and the recirculation gas outlet 18a are connected to each other via the recirculation device 54a and, in particular, ensure the recirculation of the gas in the preheating zone 21. The shaft furnace 1 of Fig. 2e corresponds essentially to the shaft furnace 1 of Fig.2a with the difference that instead of a recirculation device, three combustion chamber levels with burner lances 10 are provided, with one combustion chamber level each being arranged in the first, second and third combustion zone 20a, b, c. By way of example, the shaft furnace 1 of Fig. 2e does not have a co-current combustion zone and is operated entirely in counter-current flow.

[0072] A third flow element level 5c preferably adjoins the second flow element level 5b in the flow direction of the material, and is particularly located in the second combustion zone 20b or the third combustion zone 20c. By way of example, the third flow element level 5c forms the boundary between the second combustion zone 20b and the third combustion zone 20c. Fig. 3c shows a shaft cross-section in the third flow element level 5c. Preferably, the flow elements 16 of the third flow element level 5c extend from a gas inlet 17, in particular a recirculating gas inlet 17, in the shaft wall to the inner cylinder 58. The recirculating gas inlet 17 is arranged for introducing gas, in particular recirculated, preferably oxygen-enriched, exhaust gas from the combustion zone 20, into the shaft 2.The shaft wall has, for example, four outwardly projecting, particularly radial, expansions of the shaft cross-section in the third flow element level 5c, into which the beam-shaped flow elements 16 each open. A combustion chamber 9 is preferably formed in each of these expansions. The shaft 2 has, for example, two or four combustion chambers 9 in the third flow element level 5c, which are, for example, each formed at the outwardly projecting ends of the material-free spaces 49 below the flow elements 16. A burner lance 10 is arranged in each of the combustion chambers 9, each of which is connected to the recirculating gas inlet 17 for introducing recirculated exhaust gas and, in particular, oxygen. The material-free spaces 49 of the third flow element level 5c preferably extend into the combustion chambers 9.

[0073] In the direction of material flow, a fourth flow element level 5d adjoins the third flow element level 5c, preferably located in the third combustion zone 20c or the gas separation zone 48. The fourth flow element level 5d forms, by way of example, the boundary between the combustion zone 20, in particular the third combustion zone 20c, and the gas separation zone 48. In the fourth flow element level 5d, exactly four flow elements 16 are arranged, preferably at the same level and, in particular, identically designed. Fig. 3d shows a shaft cross-section in the fourth flow element level 5d. The arrangement of the flow elements 16 within the fourth flow element level 5d essentially corresponds to that of the third flow element level 5c.Preferably, the flow elements 16 of the fourth flow element level 5d extend from a gas outlet 18, in particular a recirculating gas outlet 18, in the shaft wall to the inner cylinder 58. The recirculating gas outlet 18 is arranged for releasing gas, in particular exhaust gas from the combustion zone 20, from the shaft 2. The shaft wall preferably has two outwardly projecting, in particular radial, expansions of the shaft cross-section in the fourth flow element level 5d, into which the beam-shaped flow elements 16 open.

[0074] A fifth flow element level 5e preferably adjoins the fourth flow element level 5d in the flow direction of the material, and is particularly located in the gas separation zone 48 or the cooling zone 22. By way of example, the fifth flow element level 5e forms the boundary between the gas separation zone 48 or the cooling zone 22. In the fifth flow element level 5e, exactly four flow elements 16 are arranged, preferably at the same level and, in particular, identically designed. Fig. 3e shows a shaft cross-section in the fifth flow element level 5e. The arrangement of the flow elements 16 within the fifth flow element level 5e essentially corresponds to that of the other flow element levels 5a to 5d, without any widening.Preferably, the flow elements 16 of the fifth flow element level 5e extend from a respective cooling gas outlet 36 in the shaft wall to the inner cylinder 58. The cooling gas outlet 36 is arranged for releasing gas, in particular cooling gas from the cooling zone 22, from the shaft 2. The circulating gas is, for example, gas that is circulated within the combustion zone 20. Preferably, gas is drawn off from the combustion zone 20 via the circulating gas outlet 18 and fed back to the circulating gas inlet 17. A recirculation device 54 is arranged between the circulating gas outlet 18 and the circulating gas inlet 17, by means of which the circulating gas is accelerated from the circulating gas outlet 18 to the circulating gas inlet 17. The circulating gas outlet 18 is arranged downstream of the circulating gas inlet 17 in the flow direction of the material to be burned.Preferably, the pressure at the recirculating gas outlet 18 is lower than the ambient pressure, optionally a negative pressure, so that the recirculating gas within the combustion zone 20 is directed towards the recirculating gas outlet 18. The recirculating gas entering the combustion zone 20 via the recirculating gas inlet 17 flows partly against the flow direction of the material to be burned towards the preheating zone 21 and partly in the same direction as the material towards the recirculating gas outlet 18. Within the combustion zone 20, a co-flow combustion zone 20c preferably forms between the recirculating gas inlet 17 and the recirculating gas outlet 18. Preferably, a counter-flow combustion zone 20a, b is formed upstream of the recirculating gas inlet 17 in the flow direction of the material, in which the material flows through the shaft 2 against the gas flow. The counterflow combustion zone 20a, b of the combustion zone 20 is preferably formed exclusively between the recirculating gas inlet 17 and the preheating zone 21.

[0075] The recirculating gas device 54 comprises, for example, an injector 57, which is preferably designed as a nozzle. The recirculating gas is accelerated by means of the injector 57 towards the recirculating gas inlet 17, whereby a low pressure is generated at the recirculating gas outlet 18, which is preferably adjustable. It is also conceivable not to provide a recirculating device 54, in which case the entire combustion zone 20 is designed as a counterflow combustion zone and the gas inlet 15 is optionally omitted.

[0076] At the lower end of shaft 2, a material outlet 40 is arranged for discharging the calcined material. The material outlet 40 is, for example, a sluice gate as described with reference to the material inlet 3. Adjoining the cooling zone 22 in the material conveying direction is a discharge hopper 25, in particular a lower material bunker, which opens into the material outlet 40 for discharging the material from the shaft kiln 1. An outlet device 41 is arranged in the outlet hopper 25, for example, to discharge material from the cooling zone 22 of the shaft kiln 1 into the outlet hopper 25. The discharge device 41 is, for example, a rotary table or push tables.

[0077] The shaft furnace 1 has one or more cooling air inlets 7 for introducing cooling air into the shaft furnace 1. By way of example, the shaft furnace 1 of FIGS. 1 and 2a has one cooling air inlet 7 that introduces cooling air into the outlet hopper 25. Preferably, the cooling air is blown into the outlet hopper 25 at a pressure of 500 mbar by means of a cooling air compressor 26.

[0078] During operation of shaft kiln 1, the material flows through shaft 2 primarily by gravity and is thermally treated in countercurrent or partially cocurrent flow. In the combustion zone 20 of shaft 2, a column of material forms, consisting of the material supplied via material feed 3. This material descends by gravity and is drawn off as a calcined product, for example, quicklime, in the cooling zone 22 via material outlet 40. The material preferably fills the entire, preferably annular, cross-section of the combustion zone 20 and the cooling zone 22. The cooling gas flows through the material bed and enters the material-free space 49 of the fifth flow element level 5e, which is specifically referred to as the cooling gas discharge device. Preferably, only cooling gas, and no exhaust gas from the combustion zone 20, is discharged from shaft 2 via the cooling gas discharge device.In particular, the cooling gas flows through the cooling zone 22 and then into the cooling gas exhaust device, so that the cooling gas is preferably completely released from the shaft via the cooling gas exhaust device and does not enter the combustion zone 20.

[0079] The material-free space 49 of the fifth flow element level 5e is preferably connected via the cooling air exhaust line 11 to a control element 46 in the form of, for example, a flap for controlling the amount of gas flowing through the material-free space 49 of the fifth flow element level 5e, in particular the cooling air exhaust line 11 adjoining it.

[0080] The exhaust gas outlet 19 for discharging the exhaust gas from the preheating zone 21 is preferably connected via the exhaust gas outlet line 39 to an exhaust gas filter 31 for dust removal from the exhaust gas and optionally to a cooling device 32 for cooling the hot exhaust gas, which is exemplified as a heat exchanger. The exhaust gas from the combustion zone 20 is at least partially or completely discharged from the shaft 2 via the exhaust gas outlet line 39. The exhaust gas discharged before or after the cooling device 32 preferably has a high CCh content of at least 90, in particular at least 95 vol% or more, preferably up to 100 vol%, and can, for example, be sequestered and / or used for further industrial purposes, such as the production of soda, sugar, or precipitated calcium carbonate.

[0081] The cooled exhaust gas is preferably partially discharged and, for example, partially downstream of the cooling device 32, conveyed as propellant gas to the circulation device 54 via a propellant gas line 43. Optionally, the propellant gas line 43 is connected to a heat exchanger 35, wherein the heat exchanger 35 is connected to the cooling gas outlet 36, so that the propellant gas 43 is heated in counterflow with the extracted cooling air before entering the circulation device 54.

[0082] The burner lances 10 of the combustion chambers 8, 9 are preferably connected to a fuel line 23 for supplying fuel. Additionally, the combustion chambers 8, 9, and / or the burner lances 10 are connected to an oxidizer line 24 for conveying an oxidizer, such as oxygen, air, or oxygen-enriched air. The oxidizer line 24 is, for example, connected to the exhaust gas line 43, so that oxygen-containing gas is fed into the recirculated exhaust gas.

[0083] The cooling air exhaust line 11 is connected in particular to the heat exchanger 35 and optionally downstream to a filter 50, so that the cooling air drawn off via the material-free space 49 of the fifth flow element level 5e is cooled and dedusted. For further cooling of the drawn cooling air, a coolant, such as air, is optionally mixed with the drawn cooling air, preferably before it enters the heat exchanger 35. A dust removal filter is optionally arranged downstream of the control element 46 in the direction of flow of the drawn cooling air. Thus, in the cooling gas exhaust line 11, the heat exchanger 35, the control element 46, and optionally a filter 50 are arranged sequentially upstream or downstream of the control element 46.It is also conceivable that the cooling air outlet 36 is connected to the heat exchanger 52 for heating the exhaust gas of the exhaust gas line 39, with the gas outlet 12 being connected to the heat exchanger 35 for heating the recirculated exhaust gas of the propellant gas line 43.

[0084] For example, the gas discharged from the combustion zone 20 via the gas outlet 12, in particular the material-free space 49 of the first flow element level 5a, is directed into a second heat exchanger 52 and then via the gas inlet 15 into the material-free space 49 of the second flow element level 5b in the combustion zone 20. The shaft furnace 1 has, for example, two heat exchangers 35 and 52, to each of which a portion of the exhaust gas drawn off via the exhaust gas outlet 19 is supplied for heating. The quantity of the exhaust gas partial flows is preferably adjusted by means of control devices, such as a flap or a valve, in the exhaust gas outlet line 39. The heat exchangers 35 and 52 are preferably connected in parallel to each other.

[0085] Before the extracted exhaust gas is introduced into the combustion zone 20, in particular into the gas inlet 15 of the material-free space 49 of the second flow element level 5b, the exhaust gas is heated, for example, by means of the heat exchanger 35 to a temperature of about 500°C to 800°C.

[0086] Fig. 4 shows another embodiment of a shaft furnace, which largely corresponds to the shaft furnace 1 of Fig. 1, with the difference that the shaft furnace 1 of Fig. 4 has no fuel line 23, no burner lances 10, and no oxidizer line 24. Hot gas generators 62 are preferably arranged in the combustion chambers 8, 9. The hot gas generators 62 are connected, in particular, to the propellant gas line 43 for supplying exhaust gas to the respective hot gas generator 62. For example, a portion of the exhaust gas discharged via the exhaust gas outlet line 39 is introduced into the combustion zone 20 via the hot gas generators 62 and / or the gas inlet 15. The hot gas generator 62 of Fig. 4 includes, by way of example, a plasma generator and / or a resistance heater 64, wherein the plasma generator 64 heats the exhaust gas within the hot gas generator 62 by means of a plasma, in particular a plasma jet or a plasma chamber.The plasma generator 64 is preferably a non-transferred direct current plasma generator configured to generate the plasma by means of a non-transferred direct current arc. The plasma generator 64 is preferably operated at least partially or completely electrically. The plasma generator 64 is particularly arranged outside the shaft 2. For example, each hot gas generator 62 comprises exactly one plasma generator 64.

[0087] The plasma is preferably configured as a plasma jet, a plasma zone, or a plasma-filled space. In contrast to non-transferred plasma, in transferred plasma, heat transfer preferably occurs directly to the solid electrode. The resistance encountered by the current in the electrode heats it up. Non-transferred plasma is preferably used to heat the gas, in particular the recirculated exhaust gas. Preferably, the gas to be heated is passed through the plasma so that it flows through it and is heated in the process. (Reference numeral list)

[0088] 1 shaft furnace

[0089] 2 shafts

[0090] 3 Material inlet / sluice

[0091] 5a-e Flow elements level

[0092] 7 Cooling air intake

[0093] 8 upper combustion chamber

[0094] 9 lower combustion chamber

[0095] 10 burner lances

[0096] 11 Cooling air exhaust duct

[0097] 12 Gas outlet

[0098] 13 Fuel line

[0099] 15 Gas inlet

[0100] 16 Flow element

[0101] 17, a recirculating gas inlet

[0102] 18, a recirculating gas outlet

[0103] 19 Exhaust outlet

[0104] 20 Fire zone

[0105] 20a first fire zone

[0106] 20b second firing zone

[0107] 20c third firing zone

[0108] 21 Preheating zone

[0109] 22 Cooling zone

[0110] 23 Fuel line

[0111] 24 Oxidizing agent line

[0112] 25 outlet funnels

[0113] 26 Cooling air compressors

[0114] 28 compressors / fans

[0115] 30 compressors / fans

[0116] 31 exhaust filters

[0117] 32 Cooling unit

[0118] 33 Compressors / Fans

[0119] 34 Compressors / Fans

[0120] 35 first heat exchanger

[0121] 36 Cooling gas outlet

[0122] 37 Cooling gas outlet line

[0123] 39 Exhaust outlet pipe / Exhaust pipe

[0124] 40 Material outlet / sluice

[0125] 41 Discharge device

[0126] 43 Propellant gas line

[0127] 44 Cooling gas inlet opening

[0128] 46 Regulatory body

[0129] 47 Cooling gas inlet line

[0130] 48 Gas separation zone

[0131] 49 material-free space

[0132] 50 filters

[0133] 51 First cooling channel 52 Second heat exchanger

[0134] 53 second cooling channel

[0135] 54, a circulation device

[0136] 55 Release agent 56 Process room

[0137] 57 Injector

[0138] 58 internal cylinders

[0139] 59 Cooling gas outlet opening

[0140] 60 Ring shaft area 62 Hot gas generator

[0141] 64 Plasma generator / electric resistance heater

Claims

Patent claims 1. Shaft furnace (1) for firing material, in particular containing carbonate, comprising a shaft (2) having, in the direction of flow of the material, a material inlet (3), a preheating zone (21) for preheating the material, a firing zone (20) for firing the material, a cooling zone (22) for cooling the fired material, and a material outlet (40) for discharging the material from the shaft furnace (1), wherein the shaft furnace (1) has an exhaust gas outlet (19) for discharging exhaust gas from the preheating zone of a shaft (2), characterized in that the shaft (2) has an inner cylinder (58) which extends centrally through the shaft (2) and is connected to a cooling gas line, so that cooling gas flows into the inner cylinder (58) and wherein the inner cylinder (58) is arranged to be gas-separated from the material-filled area (60) of the shaft (2).

2. Shaft furnace (1 ) according to claim 1 , wherein the inner cylinder (58) extends from the cooling zone (22) through the combustion zone (20) into the preheating zone (21 ).

3. Shaft furnace (1 ) according to one of the preceding claims, wherein the inner cylinder (58) has a separating agent (55) which extends through the inner cylinder (58) and separates a first cooling channel (51 ) from a second cooling channel (53).

4. Shaft furnace (1) according to one of the preceding claims, wherein the inner cylinder (58) has a cooling gas inlet (47) for introducing cooling gas into the inner cylinder (58) and a cooling gas outlet (37) for releasing cooling gas from the inner cylinder (58) and wherein the cooling gas inlet (47) and / or the cooling gas outlet (37) is / are located in the preheating zone (21), above the preheating zone (21), in or below the cooling zone.

5. Shaft furnace (1 ) according to claim 3, wherein the separating agent (55) is spaced apart from the lower end or the upper end of the inner cylinder (58) so that the cooling channels (51 , 53) are gas-technically connected to each other at the upper or the lower end of the inner cylinder (58).

6. Shaft furnace (1) according to one of the preceding claims, wherein at least one beam-shaped flow element (16) is arranged within the shaft (2), such that a material-free space (49) is formed below the flow element (16) and wherein the flow element (16) and / or the material-free space (49) is each connected to a respective gas inlet (15, 17) for introducing gas into the shaft or to a respective gas outlet (12, 18, 36) for releasing gas from the shaft.

7. Shaft furnace (1 ) according to claim 6, wherein the shaft furnace (1 ) has a hot gas chamber (8, 9) in which a burner lance (10) for combustion of fuel is arranged or which is connected to a hot gas generator in a gas-technical manner and wherein the hot gas chamber (8, 9) is formed in the material-free space (49) outside the shaft (2).

8. Shaft furnace (1) according to one of the preceding claims, wherein the shaft furnace (1) has a recirculating gas outlet (18) for releasing gas from the combustion zone (20) and a recirculating gas inlet (17) for introducing the gas released via the recirculating gas outlet into the combustion zone (20), and wherein the recirculating gas outlet (18) is formed in the shaft wall and is fluidly connected to the material-free space (49) in such a way that exhaust gas from the combustion zone (20) flows into the material-free space (49) below the flow element (16) and into the recirculating gas outlet (18).

9. Shaft furnace (1) according to claim 8, wherein the circulating gas outlet (18) is below of the recirculating gas inlet (17).

10. Shaft furnace (1) according to one of the preceding claims, wherein the combustion zone (20) has a counter-current combustion zone (20a, 20b) and a co-current combustion zone (20c) in the flow direction of the material and wherein at least one flow element (16) is arranged in the counter-current combustion zone (20a, 20b) and / or in the co-current combustion zone (20c).

11. Shaft furnace (1) according to one of the preceding claims, wherein a gas separation zone (48) is arranged between the combustion zone (20) and the cooling zone (22) and wherein at least one flow element (16) is arranged in the gas separation zone (48).

12. Shaft furnace (1) according to one of the preceding claims, wherein the Preheating zone (21) and / or the cooling zone (22) each have at least one Flow element (16) has.

13. Shaft furnace (1) according to one of the preceding claims, wherein the shaft furnace (1) has a plurality of flow element levels (5a-e), wherein at least one flow element (16) or a plurality of flow elements (16) are arranged in each flow element level (5a-e).

14. Method for burning, in particular, carbonate-containing material in a shaft furnace (1) with at least one shaft (2), wherein the material flows through a material inlet (3) into a preheating zone (21) for preheating the material, a combustion zone (20) for burning the material, and a cooling zone (22) for cooling the burned material to a material outlet (40), wherein cooling air is admitted into the cooling zone (22), and wherein the exhaust gas is discharged from the preheating zone of a shaft (2) via an exhaust gas outlet (19), characterized in that a cooling gas flows through an inner cylinder (58) and is separated gas-technically from the material-filled area of ​​the shaft (2).

15. Method according to claim 14, wherein the cooling gas flows through the inner cylinder (58) between the cooling zone (22) and the preheating zone (21).

16. Method according to claim 14 or 15, wherein the cooling gas flows within the inner cylinder (58) in a first cooling channel (51 ) and a second cooling channel (53) which is separated from the first cooling channel (51 ) by a separating agent (55).

17. Method according to claim 16, wherein the cooling gas flows in the first cooling channel (51) in countercurrent flow to the second cooling channel (53).

18. Method according to any one of claims 14 to 16, wherein the cooling gas flows into the first cooling channel (51) at the upper or lower end of the inner cylinder (58) and flows out of the inner cylinder (58) from the second cooling channel (53) at the upper or lower end of the inner cylinder (58).

19. Method according to one of claims 14 to 18, wherein a circulating gas is discharged from the combustion zone (20) via a circulating gas outlet (18) and introduced into the combustion zone (20) via a circulating gas inlet (17), wherein the circulating gas is directed from the material-filled area of ​​the shaft (2) into the material-free space (49) and to the circulating gas outlet (18).

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