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

Abstract

The invention relates to a shaft furnace (1) for firing carbonate-containing material in particular, having a shaft (2) which has, in the flow direction 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). The shaft furnace (1) has an exhaust gas outlet (19) for discharging exhaust gas from the preheating zone of a shaft (2), at least one beam-shaped flow element (16) is provided within the shaft (2) such that a material-free chamber (46) is formed below the flow element (16), and the shaft furnace (1) has a hot gas chamber (8, 9) in which a firing lance (10) for firing fuel is provided or which is connected to a hot gas generator in terms of gas flow, the hot gas chamber (8, 9) being formed in the material-free chamber (49) outside of the shaft (2).

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 200 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 also has an exhaust gas outlet for releasing exhaust gas from the preheating zone of the shaft.Within the shaft, at least one beam-shaped flow element is arranged, such that a material-free space is formed below the flow element, and wherein 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.

[0008] 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. This space allows for the simple extraction or supply of gas to the shaft. The use of beam-shaped flow elements is comparatively cost-effective and requires little maintenance. Positioning the hot gas chamber in the material-free space outside the shaft offers the advantage of a simple hot gas supply into the shaft interior, with the material-free space within the shaft serving as the hot gas conduit.

[0009] 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 interior of the shaft, preferably from one shaft wall to the opposite shaft wall. Preferably, the flow elements are constructed of masonry, especially 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, this area of ​​the shaft also being referred to as the process chamber. 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 part of the combustion zone has a smaller cross-sectional area than the rest of the shaft.

[0010] 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.

[0011] In addition to the material-free spaces formed below the flow elements, the shaft wall preferably has one or more outwardly projecting widenings of the shaft cross-section in which additional hot gas chambers are formed.

[0012] A beam-shaped element is defined as one that has 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 2-5 times greater than its cross-section, particularly its diameter. The cross-sectional area may be constant or vary along the length of the flow element.

[0013] 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 30 to 100 mm. The exhaust gas preferably has a CO2 content of at least 35% to 45%, preferably at least 90%, for example, based on dry gas. The material inlet is located, in particular, at the upper end of the shaft. A preheating zone is arranged upstream of the combustion zone in the direction of material flow. The preheating zone preferably connects directly to the material inlet of 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 1200°C. The cooling zone preferably connects directly to the combustion zone and serves to cool the calcined 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 adjoining the cooling zone, wherein the material outlet has, for example, a rotary table or pusher 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.

[0014] 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.

[0015] The shaft preferably contains one or more hot gas chamber levels, in which material-free spaces, in particular hot gas chambers, are preferably 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 six hot gas generators. The term "material-free" preferably means "free of combustible material." A material-free space is preferably a space in which no material to be combusted is present.The material-free space features, 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.

[0016] 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 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.

[0017] For example, the exhaust gas discharged from the preheating zone of the shaft 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. 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, about 20% to 80%, in particular 50%, is fed back into the combustion zone, with the remaining portion being discharged from the shaft furnace and stored, for example, for subsequent sequestration in a storage tank.

[0018] The shaft furnace has a material-filled process chamber in which process gas flows, wherein the at least one beam-shaped flow element preferably extends completely and, in particular, exclusively through the process chamber of the shaft. The process chamber is preferably exclusively the material-filled inner region of the shaft. The process chamber has, for example, a round, oval, circular, angular, elliptical, rectangular, or square cross-section, wherein the process chamber is designed as a cylinder or cuboid. The process gas preferably flows within the process chamber. Preferably, the shaft has a rectangular cross-section, wherein the at least one flow element extends from one side wall of the shaft to the opposite side wall.In particular, the shaft has a round, circular, oval, or elliptical cross-section, with the flow element extending radially through the shaft, especially exclusively through the material-filled portion of the shaft. For example, the beam-shaped flow element is arranged within the shaft such that material rests against the upward-facing surface and / or the side surfaces of the flow element and, in particular, flows away from it, with the material-free space being formed on the downward-facing surface of the flow element. The beam-shaped flow element is preferably arranged freely within the material-filled portion of the shaft and preferably attached to the shaft wall only at its respective ends. Preferably, the beam-shaped flow element is arranged and designed to allow material to flow completely around it.The beam-shaped flow element is preferably straight, extending exclusively within a single flow element plane. The flow elements allow process gas to be extracted via the material-free space created by the flow elements. This extraction can be easily accomplished through an outlet in the outer wall of the shaft, resulting in only minimal dust accumulation on the inner wall, which can be easily removed.

[0019] The at least one flow element preferably has an upwardly tapered, in particular wedge-shaped or roof-shaped, geometry. Such a geometry enables reliable material flow away from the flow elements and reduces wear and build-up on the flow element.

[0020] According to a first embodiment, at least one or more beam-shaped flow elements have a U-shaped cross-sectional profile, wherein the U-shaped cross-sectional profile is open, in particular, downwards. Preferably, the cross-sectional profile of the flow element is continuously U-shaped. A U-shaped, downwardly pointing cross-sectional profile offers the advantage that a material-free space reliably forms within the LI shape, thus allowing for simple gas extraction or gas supply via this material-free space. In particular, all flow elements of the shaft furnace are identical and extend parallel to one another. Preferably, the beam-shaped flow elements are arranged parallel to one another and are preferably all identical.

[0021] Preferably, the flow element and / or the material-free space is fluidically connected to a respective gas inlet or gas outlet. The flow elements, together with the material-free spaces, preferably form gas channels for introducing or releasing gas into or out of the shaft. The gas inlet and / or gas outlet is preferably formed in the shaft wall. Preferably, the flow element extends from a gas outlet or gas inlet in the shaft wall to an opposite gas outlet or gas inlet in the opposite shaft wall. The shaft furnace preferably has a process chamber that is preferably completely filled with material. The gas inlet and / or gas outlet is preferably connected directly to the process chamber via the material-free space formed below the flow element.

[0022] According to a further embodiment, the shaft furnace has a recirculating gas outlet for releasing gas, in particular recirculating gas, from the combustion zone or the preheating zone, and a recirculating gas inlet for introducing the gas released via the recirculating gas outlet into the combustion zone. The recirculating gas is preferably gas from the combustion zone or the preheating zone, particularly from the lower region of the combustion zone adjacent to the cooling zone. The recirculating gas consists essentially of CO2, especially since no cooling gas from the cooling zone enters the combustion zone. Preferably, the combustion zone comprises a counterflow combustion zone and a coflow combustion zone directly adjoining it in the direction of material flow. The recirculating gas is preferably drawn exclusively from the coflow combustion zone and, in particular, is returned exclusively to the coflow combustion zone.

[0023] According to a further embodiment, the recirculating gas outlet is formed in the shaft wall and fluidically connected to the free space such that exhaust gas from the combustion zone flows directly from the process chamber into the free space below the flow element and directly into the recirculating gas outlet. Preferably, the shaft furnace has at least one or more recirculating gas outlets, each of which is 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 more recirculating gas inlets, each of which is associated with a free space formed below a respective flow element. The recirculating gas inlet is particularly formed in the shaft wall.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 towards the recirculating gas inlet. Preferably, the recirculating gas device is designed to create a negative pressure at the recirculating gas outlet.

[0024] 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. Acceleration of the circulating gas creates a negative 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.

[0025] 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 or up to 1800°C, particularly up to 1700°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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] According to a further embodiment, the preheating zone and / or the cooling zone each have at least one flow element. Preferably, exactly one flow element is arranged in the preheating zone. In the cooling zone, in particular, exactly one flow element or more, in particular two, flow elements are arranged, which, for example, extend parallel to each other.

[0030] 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 or five 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, 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 designed as counter-current combustion zones, and a third combustion zone adjoining the second combustion zone, which is designed as a co-current combustion zone.

[0031] The shaft preferably has two or four hot gas chambers in the flow element plane, which are formed particularly 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.

[0032] 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. 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 or to an inner cylinder.

[0033] The second flow element level is preferably arranged in the first or second combustion zone. Preferably, a flow element level forms the boundary between the first and second combustion zones, optionally containing only one flow element. Preferably, the flow element of the flow element level in the first and second combustion zones extends from a gas inlet for introducing gas, in particular recirculated exhaust gas, in the shaft wall to an opposing gas inlet in the opposite shaft wall. A further flow element level is preferably arranged in the second or third combustion zone. By way of example, this flow element level forms the boundary between the second and third combustion zones.

[0034] 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.

[0035] 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.

[0036] Preferably, the shaft does not have an inner cylinder extending centrally through the shaft.

[0037] 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 discharged from the preheating zone of a shaft via an exhaust gas outlet, and wherein at least one beam-shaped flow element is arranged within the shaft, such that a material-free space is formed below at least one beam-shaped flow element within the shaft, and wherein a hot gas is generated in a hot gas chamber in the material-free space outside the shaft.

[0038] The advantages and features described with regard to the device also apply to the method in a corresponding manner. According to a further embodiment, gas, in particular process gas, is released from the process chamber, preferably directly, through the material-free space out of the shaft or introduced into the shaft. The process gas preferably flows outwards within the shaft towards the gas outlet arranged in the shaft wall, wherein the process gas flows from the process chamber directly through the material-free space below the flow element to the outside to the gas outlet and is released from the shaft.

[0039] 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.

[0040] According to a further embodiment, a countercurrent combustion zone and a cocurrent combustion zone are formed in the combustion zone in the direction of flow of the material, wherein the circulating gas is removed from the cocurrent combustion zone and introduced into the countercurrent combustion zone.

[0041] Preferably, a recirculating gas is drawn off from the combustion zone and introduced into the combustion zone along 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 second combustion zone, and reintroduced at an upper part of the combustion zone, particularly the first combustion zone. 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.

[0042] 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.

[0043] Description of the drawings

[0044] The invention is explained in more detail below with reference to several exemplary embodiments and the accompanying figures.

[0045] Fig. 1 shows two schematic representations of a shaft furnace in a longitudinal section view and a longitudinal section view rotated by 90° according to an exemplary embodiment.

[0046] Fig. 2a-e shows schematic representations of a shaft furnace in several cross-sectional views of different planes according to further embodiments.

[0047] Fig. 3 shows two schematic representations of a shaft furnace in a longitudinal section view according to a further embodiment.

[0048] Fig. 1 shows a shaft kiln 1 in two views. 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. By way of example, the upper region of the shaft 2, in particular the preheating zone 21 and / or at least a part of the firing zone 20, has a smaller cross-sectional area than the remaining region of the shaft 2. 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 inner wall.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.

[0049] 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.

[0050] 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, parallel to one another. The flow elements 16 extend, for example, through the interior of the shaft 2, preferably from one shaft wall to the opposite shaft wall of the shaft 2. Preferably, the flow elements 16 are constructed of masonry, in particular of refractory material.

[0051] 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 2-5 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.

[0052] 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. By way of example, the shaft furnace 1 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. By way of example, only one flow element 16 is arranged in the first flow element level 5a. Fig.Figure 2a shows a shaft cross-section in the first flow element level 5a. The flow element 16 of the first flow element level 5a extends, by way of example, centrally through the shaft cross-section and, in particular, through the center point of the shaft cross-section. Preferably, the flow element 16 of the first flow element level 5a extends from a gas outlet 12 in the shaft wall to an opposite gas outlet 12 in the opposite shaft wall. The gas outlet 12 is arranged for the discharge of 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 zones 20a, b.

[0053] 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. By way of example, only one flow element 16 is arranged in the second flow element level 5b. Fig. 2b shows a shaft cross-section in the second flow element level 5b. The flow element 16 of the second flow element level 5b extends, by way of example, centrally through the shaft cross-section and, in particular, through the center point of the shaft cross-section. Preferably, the flow element 16 of the second flow element level 5b extends from a gas inlet 15 in the shaft wall to an opposite gas inlet 15 in the opposite shaft wall.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 an outwardly projecting, particularly radial, widening of the shaft cross-section in the second flow element level 5b, into which the beam-shaped flow element 16 opens. A combustion chamber 8 is preferably formed in the widening. The shaft 2 preferably has two or four combustion chambers 8 in the second flow element level 5b, which are, for example, arranged at uniform circumferential intervals. A burner lance 10 is arranged in each combustion chamber 8, each of which is connected to the gas inlet 15 for introducing recirculated exhaust gas. The material-free space 49 of the second flow element level 5b preferably extends into the combustion chamber 8.

[0054] 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. By way of example, exactly two flow elements 16 are arranged in the third flow element level 5c, which are preferably arranged at the same level and are particularly identical in design. Fig. 2c shows a shaft cross-section in the third flow element level 5c. The flow elements 16 of the third flow element level 5c extend, by way of example, parallel to each other through the shaft cross-section.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 an opposing recirculating gas inlet 17 in the opposite shaft wall. The recirculating gas inlet 17 is arranged for introducing gas, in particular recirculated exhaust gas from the combustion zone 20, into the shaft 2. The shaft wall of the third flow element level 5c preferably has two outwardly projecting, in particular radial, expansions of the shaft cross-section into which the beam-shaped flow elements 16 open. A combustion chamber 9 is preferably formed in each of the expansions. The shaft 2 preferably has two or four combustion chambers 9 in the third flow element level 5c, which are exemplarily formed at the outwardly projecting ends of the material-free spaces 49 below the flow elements 16.Each combustion chamber 9 contains a burner lance 10, which is connected to the recirculating gas inlet 17 for introducing recirculated exhaust gas. The material-free space 49 of the third flow element level 5c preferably extends into the combustion chambers 9.

[0055] 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 two flow elements 16 are arranged, preferably at the same level and, in particular, identically designed. Fig. 2d 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. The flow elements 16 of the fourth flow element level 5d extend, by way of example, parallel to each other through the shaft cross-section.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 an opposing recirculating gas outlet 18 in the opposite shaft wall. 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.

[0056] 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. For example, the fifth flow element level 5e forms the boundary between the gas separation zone 48 or the cooling zone 22. For example, exactly two flow elements 16 are arranged in the fifth flow element level 5e, which are preferably arranged at the same level and are particularly identical in design. Fig. 2e 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 third and fourth flow element levels 5c and 5d, with no widening provided. For example, the flow elements 16 of the fifth flow element level 5e extend parallel to each other through the shaft cross-section.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 an opposite cooling gas outlet 36 in the opposite shaft wall. The cooling gas outlet 36 is arranged for releasing gas, in particular cooling gas from the cooling zone 22, from the shaft 2.

[0057] 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 parallel to one another. 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 flow of material.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. 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.

[0058] 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.

[0059] 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 into the circulating gas inlet 17. A circulating 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, a negative pressure is formed at the circulating gas outlet 18, so that the circulating gas within the combustion zone 20 is directed towards the circulating gas outlet 18. The circulating gas entering the combustion zone 20 via the circulating 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 circulating gas outlet 18.Within the combustion zone 20, a co-current combustion zone 20c preferably forms between the recirculating gas inlet 17 and the recirculating gas outlet 18. Preferably, a counter-current combustion zone 20a, b is formed upstream of the recirculating gas inlet 17 in the direction of material flow, in which the material flows through the shaft 2 against the gas flow. The counter-current combustion zone 20a, b of the combustion zone 20 is preferably formed exclusively between the recirculating gas inlet 17 and the preheating zone 21.

[0060] 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 the negative pressure is created at the recirculating gas outlet 18 and 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 omitted.

[0061] 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.

[0062] 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 Fig. 1 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 up to 500 mbar by means of a cooling air compressor 26.

[0063] During the operation of shaft furnace 1, the material flows through shaft 2 primarily due to gravity and is thermally treated in countercurrent or partially in cocurrent flow.

[0064] During operation of the shaft kiln 1, a column of material forms in the combustion zone 20 of the shaft 2, containing the material supplied via the material feed 3. The material descends by gravity and is drawn off as a calcined product, for example quicklime, in the cooling zone 22 via the material outlet 40. The material preferably fills the entire, preferably angular or round, 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 the 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 completely released from the shaft via the cooling gas exhaust device and does not enter the combustion zone 20.

[0065] 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.

[0066] 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.

[0067] The cooled exhaust gas is preferably partially discharged and partially, preferably downstream of the cooling device 32, fed 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.

[0068] 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 cooling air exhaust line 11 is connected, in particular, to the heat exchanger 35 and, optionally, thereafter 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-off cooling air, a coolant, such as air, is optionally mixed with the drawn-off cooling air, preferably before it enters the heat exchanger 35. A dust removal filter is optionally arranged upstream of the control element 46 in the direction of flow of the drawn-off cooling air.In the cooling gas exhaust line 11, the heat exchanger 35, the control element 46, and optionally a filter 50 are arranged sequentially before or after 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 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.

[0069] 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.

[0070] Before the 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 approximately 500°C to 800°C. Fig. 3 shows a further 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. 3 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 pipe 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.3 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 at least partially or completely electrically operated. The plasma generator 64 is in particular arranged outside the shaft 2. For example, each hot gas generator 62 comprises exactly one plasma generator 64.

[0071] 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)

[0072] 1 shaft furnace

[0073] 2 shafts

[0074] 3 Material inlet / sluice

[0075] 5a-e Flow elements level

[0076] 7 Cooling air intake

[0077] 8 upper combustion chamber

[0078] 9 lower combustion chamber

[0079] 10 burner lances

[0080] 11 Cooling air exhaust duct

[0081] 12 Gas outlet

[0082] 13 Fuel line

[0083] 15 Gas inlet

[0084] 16 Flow element

[0085] 17 Recirculating gas inlet

[0086] 18 Recirculating gas outlet

[0087] 19 Exhaust outlet

[0088] 20 Fire zone

[0089] 20a first fire zone

[0090] 20b second firing zone

[0091] 20c third firing zone

[0092] 21 Preheating zone

[0093] 22 Cooling zone

[0094] 23 Fuel line

[0095] 24 Oxidizing agent line

[0096] 25 outlet funnels

[0097] 26 cooling air compressors

[0098] 28 compressors / fans

[0099] 30 compressors / fans

[0100] 31 exhaust filters

[0101] 32 Cooling unit

[0102] 33 Compressors / Fans

[0103] 34 Compressors / Fans

[0104] 35 first heat exchanger

[0105] 36 Cooling gas outlet

[0106] 39 Exhaust outlet pipe / Exhaust pipe

[0107] 40 Material outlet / sluice

[0108] 41 Discharge device

[0109] 43 Propellant gas line

[0110] 44 Cooling gas inlet

[0111] 46 Regulatory body

[0112] 48 Gas separation zone

[0113] 49 material-free space

[0114] 50 filters

[0115] 52 second heat exchanger

[0116] 54 Circulation device

[0117] 56 Process chamber 57 Injector

[0118] 62 hot gas generators

[0119] 64 Plasma generator / electric resistance heater

Claims

Patent claims 1. Shaft furnace (1) for firing material, particularly carbonate-containing material, comprising a shaft (2) having, in the direction of material flow, 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 at least one beam-shaped flow element (16) is arranged within the shaft (2), such that a material-free space (46) is formed below the flow element (16), and 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. and wherein the hot gas chamber (8,9) is formed in the material-free space (49) outside the shaft (2).

2. Shaft furnace (1 ) according to claim 1 , wherein the flow element (16) has a u-shaped cross-sectional profile.

3. 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).

4. Shaft furnace (1) according to claim 3, wherein the circulating gas outlet (18) is located in the The shaft wall is formed and is fluidically connected to the material-free space (49) in such a way that exhaust gas from the combustion zone (20) flows directly from the process space into the material-free space (49) below the flow element (16) and into the recirculating gas outlet (18).

5. Shaft furnace (1 ) according to claim 3 or 4, wherein the circulating gas outlet (18) is arranged below the circulating gas inlet (17).

6. 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).

7. 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).

8. 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.

9. 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).

10. Method for firing material, in particular containing carbonate, in a shaft furnace (1) with at least one shaft (2), wherein the material is fed 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 flows to a material outlet (40), wherein cooling air is admitted into the cooling zone (22), wherein the exhaust gas is discharged from the preheating zone of a shaft (2) via an exhaust gas outlet (19), characterized in that at least one beam-shaped flow element (16) is arranged inside the shaft (2), such that a material-free space (49) is formed below at least one beam-shaped flow element (16) inside the shaft (2) and wherein a hot gas is generated in a hot gas chamber in the material-free space outside the shaft.

11. Method according to claim 10, wherein gas from the process chamber (56) is released from the shaft (2) via the material-free space (49) and / or wherein gas is introduced into the shaft (2) via the material-free space (49).

12. Method according to one of claims 10 or 11, wherein a circulating gas is discharged from the combustion zone (20) or the preheating zone (21) 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) directly into the material-free space (49) and to the circulating gas outlet (18).

13. Method according to one of claims 10 to 12, wherein a countercurrent combustion zone (20a, 20b) and a cocurrent combustion zone (20c) are formed in the combustion zone (20) in the flow direction of the material and wherein the circulating gas is removed from the cocurrent combustion zone (20c) and introduced into the countercurrent combustion zone (20a, 20b).

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