Parallel regenerative shaft kiln and method for burning carbonate rocks

Abstract

The present invention also relates to a parallel flow regenerative (PFR) vertical kiln (1) for burning and cooling materials such as carbonate rock, the kiln having two shafts (2) that can be operated alternately as a combustion shaft (2a) and as a regenerative shaft (2b) and are connected to each other via a connecting channel (19), wherein: each shaft (2) includes a preheating zone (21) for preheating the material, a combustion zone (20) for burning the material and a cooling zone (22) for cooling the material in the direction of material flow; each shaft (2) has an exhaust gas outlet (6) for discharging exhaust gas from the shaft (2); and the PFR vertical kiln (1) has at least one cooling gas conduit (44) for guiding cooling gas from the cooling zone (22) to the preheating zone (21). The present invention also relates to a method for burning materials such as carbonate rock in a parallel-flow regenerative vertical kiln (1) having two shafts (2), the shafts operating alternately as combustion shafts and as regenerative shafts and connected to each other via a connecting channel (19), wherein: 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 material, in order to reach a material outlet (40); cooling gas is introduced into the cooling zone; exhaust gas is discharged from one of the shafts (2) via an exhaust gas outlet (6); and the cooling gas is guided to the preheating zone (21) via a cooling gas pipe (44).

Description

Technical Field

[0001] This invention relates to a parallel flow regenerative vertical kiln (PFR kiln) and a method for burning and cooling materials such as carbonate rocks in a PFR kiln. Background Technology

[0002] Combustion of carbonate rocks in PFR vertical kilns has been known for approximately 60 years. This type of PFR vertical kiln, known for example from DE 102021 204 176 A1, has two vertical, parallel shafts in cyclic operation, where combustion occurs only in one shaft (the combustion shaft), while the other operates as a regenerative shaft. The combustion shaft is supplied with oxidant gas in parallel with the material and fuel, and the resulting hot exhaust gas, along with heated cooling air supplied from below, is directed via a transfer port into the regenerative shaft, where the exhaust gas is directed upwards counter-currently towards the material and preheats the material in the process. The material is typically supplied from above to the shaft along with the oxidant gas, where fuel is injected into the combustion zone.

[0003] In each shaft, the material to be burned typically passes through a preheating zone for preheating the material, a combustion zone in which the material burns downstream, and a cooling zone where cooling air is supplied to the hot material downstream.

[0004] Furthermore, the demand for environmentally friendly combustion lime production is increasing, and therefore certain requirements for CO2 content in waste gas used for subsequent reprocessing must be met. However, environmentally friendly lime production should be as cost-effective as possible and require only minimal modifications to existing equipment. In addition, lime kiln operation should be as energy-efficient as possible. The specific energy consumption of PFR vertical kilns should therefore be as low as possible, while technical complexity, particularly the number of maintenance-intensive components, should be reduced. Invention Summary

[0005] Therefore, the object of the present invention is to provide a PFR vertical kiln and a method for burning carbonate rock in a PFR vertical kiln, which enables the production of highly reactive lime while separating CO2 from the exhaust gas, wherein the production of lime is carried out in an energy-efficient and cost-efficient manner.

[0006] This objective is achieved according to the invention by means of an apparatus having the features of claim 1, which is an independent device, and by means of a method having the features of claim 15, which is an independent method. Advantageous improvements are derived from the dependent claims.

[0007] According to a first aspect, the present invention includes a parallel-flow regenerative vertical kiln for burning and cooling materials such as carbonate rock, having two shafts that can be alternately operated as combustion shafts and as regenerative shafts and are connected to each other via transfer ports. Each shaft includes, in the material flow direction, a preheating zone for preheating the material, a combustion zone for burning the material, and a cooling zone for cooling the material. Each shaft has an exhaust gas outlet for discharging exhaust gases from the shaft. The PFR kiln has cooling gas conduits for guiding cooling gases from the cooling zone to the preheating zone. The cooling gas conduits are designed, for example, as bypass lines for bypassing the combustion zone. In particular, the cooling gas conduits are arranged fluidically parallel to the combustion gases in the combustion zone. Each shaft preferably has a cooling gas conduit.

[0008] Such cooling gas piping offers the advantage that heated cooling air is supplied to the preheating zone and thus can be used for material preheating. Additional regenerators for heat exchange with the cooling gas and / or exhaust gas are not necessary. As a result, the energy consumption of the PFR vertical kiln is significantly reduced, and its complexity is further reduced.

[0009] The material to be burned is preferably limestone or dolomite, having a particle size of 10 mm to 200 mm, more preferably 15 to 120 mm, and most preferably 30 mm to 100 mm. The cooling gas is, for example, air.

[0010] A parallel-flow regenerative vertical kiln has at least two shafts, which are preferably arranged parallel and vertically to each other. Each shaft preferably has an angular, triangular, quadrilateral, rectangular, circular, elliptical, polygonal, semi-circular, partially circular, or circular cross-section. The shafts can operate alternately as combustion shafts and as regenerative shafts, wherein each shaft has a preheating zone for preheating the material, a combustion zone for burning the material, and a cooling zone for cooling the material in the direction of material flow. Each shaft preferably has a material inlet for introducing the material to be burned into the shaft, wherein the material inlet is particularly located at the upper end of the respective shaft so that the material falls into the respective shaft under gravity. The material inlet and / or material outlet are particularly in the form of locks for introducing material into and / or discharging material from the kiln. The lock-type material inlet is preferably designed so that only the raw material to be burned enters the shaft, not ambient air. The material lock also prevents gas from escaping from the shaft via the material inlet. The lock is preferably designed to airtightly seal the shaft from the environment and allow solids (e.g., materials to be burned) to enter the shaft. The combustion zone, preheating zone, and cooling zone should preferably be understood as the material-filled areas of the shaft. Spaces without material (which are separated from the material-filled areas of the shaft, for example, by walls) are preferably not part of the preheating zone, combustion zone, or cooling zone.

[0011] The transfer port is designed to fluidically connect two shafts and preferably connect the combustion zones of the shafts to each other. In the operation of the PFR shaft kiln, one shaft operates as a combustion shaft and is active in each case, while the corresponding other shaft operates as a regenerative shaft and is passive. The PFR shaft kiln is particularly cyclical, with the function of the shafts switching after the cycle time has elapsed. This process is repeated continuously. In the active shaft operating as a combustion shaft, fuel is introduced into the combustion zone via burner nozzles. The material to be burned is heated in the preheating zone of the combustion shaft, preferably to a temperature of approximately 700°C. In the shaft operating as a combustion shaft, the combustion zone is in the form of a co-current combustion zone, where the material to be burned flows parallel to the gas. The gas flows from the preheating zone to the combustion zone within the combustion shaft and then flows via the transfer port to the combustion zone and preheating zone of the regenerative shaft. In the shaft operating as a regenerative shaft, the gas flows counter-currently to the material to be burned in the preheating zone and combustion zone.

[0012] In both the combustion shaft and the regenerator shaft, the cooling gas is guided countercurrently through the cooling zone and preferably completely discharged from the cooling zone, especially from the shaft, via cooling gas ducts, so that preferably no gas flows into the combustion zone. The cooling gas ducts and / or cooling gas outlets are preferably arranged such that at least 60%, especially at least 70%, preferably at least 80% to at least 90% of the cooling gas supplied to the PFR shaft is discharged from the cooling zone, especially from the shaft, via cooling gas ducts. The cooling gas ducts are preferably arranged separately from the combustion zone, especially the shaft. In particular, the cooling gas outlets and / or cooling gas ducts are arranged and designed such that 85% to 115%, especially 90% to 110%, preferably 105% of the cooling gas supplied to the PFR shaft is discharged as cooling gas via cooling gas outlets and cooling gas ducts. It is also conceivable that all cooling air is supplied to the combustion shaft, or at least more cooling air is supplied to the latter (combustion shaft) than to the regenerator shaft. This prevents, for example, a portion of the kiln exhaust gas from flowing out of the combustion shaft via the lower connecting channel. For example, 60–100% of the cooling air is supplied to the combustion shaft.

[0013] The exhaust gas is preferably discharged from only one shaft, particularly a regenerative shaft. Control elements, such as baffles, fans, or valves, are preferably arranged downstream of the exhaust gas outlet, by means of which the amount of exhaust gas to be discharged is adjustable. The discharged exhaust gas is preferably supplied to a corresponding other shaft, particularly to a combustion shaft. Preferably, only a portion of the exhaust gas discharged from the regenerative shaft is returned to at least one shaft. A portion of the exhaust gas discharged from the regenerative shaft is discharged, for example, from a PFR kiln and supplied, for example, to further treatment, such as storage. For example, the exhaust gas discharged from the regenerative shaft is supplied to a buffer storage tank and temporarily stored therein. The exhaust gas preferably comprises CO2 and optionally H2O. The PFR kiln preferably has a combustion gas inlet for introducing combustion gas into the preheating or combustion zone, wherein the exhaust gas outlet is optionally connected to the combustion gas inlet via an exhaust gas return pipe.

[0014] Fuel is preferably supplied via fuel pipeline to the combustion zone and / or preheating zone of the shaft operating as a combustion shaft. Fuel is preferably supplied to burner lances arranged in the combustion zone and / or preheating zone. The fuel is, for example, a fuel gas, such as blast furnace gas or natural gas, or pulverized coal or biomass or liquid fuel. The material is preferably heated to a temperature of approximately 1050°C in the combustion zone.

[0015] Each shaft preferably has multiple burner nozzles that extend at least partially through the preheating zone and are particularly open in the combustion zone of the respective shaft for guiding, for example, fuel and / or oxidizer gases, such as air or oxygen-enriched air or pure oxygen. The PFR shaft kiln preferably has a combustion gas inlet connected to a combustion gas source comprising combustion gas having an oxygen content of more than 60%, preferably more than 75%, and particularly more than 80% to more than 95% by volume.

[0016] Each shaft preferably has a corresponding cooling gas inlet for introducing cooling gas into the cooling zone. Each inlet is equipped with a control element for regulating the amount of cooling gas supplied to the corresponding cooling gas inlet, wherein the control element adjusts to supply a larger amount of cooling air to the combustion shaft than to the regenerator shaft. The control element is, for example, an infinitely adjustable valve or baffle. The control element is arranged, for example, upstream of the cooling gas inlet and particularly in the cooling gas duct connected to the cooling air inlet. The control element is preferably configured and specified such that 70% to 100%, preferably 90%, of the total cooling gas supplied to the PFR shaft is supplied to the combustion shaft.

[0017] Returning the waste gas to at least one shaft enables the production of highly reactive lime while simultaneously producing process gas with a CO2 content of more than 30%, particularly more than 50%, preferably more than 70% or more than 90% by volume based on dry gas. Such process waste gas allows for a relatively low level of complexity in its liquefaction and storage. For example, the liquefied process waste gas can be supplied to further process steps or for storage. The aforementioned PFR shaft kiln can also be used alternatively to generate waste gas with even lower CO2 content, such as 40% to 50% for soda production, or 30% to 35% based on dry gas for beet sugar or precipitated calcium carbonate production.

[0018] According to a discovery by the inventors, the oxygen-containing cooling gas flows essentially separately from the combustion gas within the shaft, especially in the preheating zone, resulting in only a very slight mixing of the combustion gas and cooling gas flow.

[0019] According to the first embodiment, the cooling gas conduit is arranged outside or inside the shaft. Preferably, the cooling gas conduit extends entirely outside the shaft and is particularly fluidically parallel to the corresponding shaft, especially the combustion zone of the regenerable shaft. Optionally, the cooling gas conduit is arranged entirely inside the shaft and is particularly fluidically separated from the remaining areas of the combustion zone and / or preheating zone by separation devices (such as partition walls or pipes). In the case of a PFR shaft kiln with an angular shaft cross-section, the cooling gas conduit is preferably arranged inside the shaft. In particular, the cooling gas conduit is arranged inside the shaft in the area near the shaft wall opposite the transfer port. Compared to known PFR shaft kilns, the gas mixing in the corresponding shaft is less intense because the cooling gas does not flow through the combustion zone of the regenerable shaft.

[0020] According to a further embodiment, the vertical kiln has a cooling gas outlet for discharging cooling gas from the cooling zone, particularly from the shaft, wherein the cooling gas outlet is arranged within the cooling zone and fluidically connected to a cooling gas conduit. The cooling gas outlet is preferably formed as an opening in the shaft wall. The cooling gas preferably flows entirely out of the corresponding shaft through the cooling gas outlet, and more preferably only from the cooling zone of the shaft. For example, the cooling gas outlet is trough-shaped and extends circumferentially, particularly horizontally, within the shaft wall of the cooling zone.

[0021] According to a further embodiment, the vertical kiln has a cooling gas inlet in the preheating zone, which is fluidly connected to a cooling gas conduit for introducing cooling gas into the preheating zone. A cooling gas outlet is connected, particularly via a cooling gas conduit, to the cooling gas inlet for introducing cooling gas into the shaft. The cooling gas inlet is preferably located entirely within the preheating zone, particularly at the lower end of the preheating zone of the respective shaft. Each shaft preferably has its own cooling gas outlet and its own cooling gas inlet, which are connected to each other via cooling gas conduits for guiding cooling gas from the cooling gas outlet to the cooling gas inlet. Particularly in the case of PFR vertical kilns with angular cross-sections, the cooling gas inlet is located on the shaft wall opposite the transfer port. According to a discovery of the inventors, only a slight mixing of the cooling gas and the CO2-containing combustion gases from the combustion zone occurs within the preheating zone of the regenerative shaft. The introduction of cooling gas into the preheating zone thus serves as an additional heat source for material preheating and ensures energy-efficient kiln operation.

[0022] According to a further embodiment, the cooling gas inlet is designed in a trough shape. For example, in the case of a PFR vertical kiln with a circular shaft cross-section, the cooling gas inlet extends circumferentially around the preheating zone, particularly completely across the entire area. Optionally, in the case of a PFR vertical kiln with an angular shaft cross-section, the cooling gas inlet extends horizontally, particularly completely across the width of the shaft wall opposite the transfer port.

[0023] According to a further embodiment, the vertical kiln has partition walls arranged within the shaft and at least partially forming cooling gas conduits. The cooling gas conduits formed by the partition walls preferably extend entirely within the shaft. In particular, each shaft has its own partition wall. The partition walls preferably extend vertically from the cooling zone or combustion zone to the shaft top cover. Specifically, the lower end of the partition wall is arranged at the level of the transfer port, while the upper end of the partition wall is preferably airtightly supported on the shaft top cover. In particular, the partition walls extend across the entire width, and especially the depth, of the respective shaft and are preferably aligned so as to be geometrically parallel to the shaft wall opposite the transfer port.

[0024] According to a further embodiment, the cooling gas outlet is designed to discharge cooling gas from the cooling zone between the partition wall and the inner wall of the shaft. The partition wall, together with the inner wall of the shaft, particularly the regenerative shaft, preferably forms a cooling gas conduit. The cooling gas conduit exemplarily comprises approximately 20–40%, preferably approximately 33%, of the volume of the combustion zone and / or preheating zone. The cooling gas conduit preferably has a combustion gas inlet for introducing oxygen-enriched exhaust gas. The PFR shaft kiln preferably has a further combustion gas inlet in each shaft, through which oxygen-enriched exhaust gas recirculated is introduced into the combustion shaft outside the cooling gas conduit. According to an inventor's discovery, the cooling air preferably flows only in the outer shaft portion opposite the transfer port, such that the cooling air is hydrodynamically separated from the combustion gas in the combustion zone by the partition wall. Mixing of the combustion gas and the cooling gas is thus reliably prevented.

[0025] According to a further embodiment, the vertical kiln has a cooling gas outlet for discharging cooling gas from the shaft, and the cooling gas outlet is arranged in the preheating zone of the shaft. The cooling gas outlet is arranged, for example, at the upper end of the preheating zone. The cooling gas outlet is preferably arranged in the outer wall of the shaft. In particular, the cooling gas outlet extends completely through the outer wall of the shaft and is particularly arranged in the outer wall surrounding the preheating zone or combustion zone. The PFR vertical kiln preferably has a refractory lining, which extends, for example, from the cooling zone to the preheating zone, particularly to the lower region of the preheating zone. The cooling gas outlet is preferably arranged above the refractory lining or at the upper end region of the refractory lining. The cooling gas outlet is preferably completely arranged in the preheating zone or combustion zone, resulting in the cooling air from the cooling zone flowing particularly completely into the combustion zone. The cooling gas outlet arranged in the outer wall of the preheating zone or combustion zone provides a structurally very simple cooling gas extraction solution. Existing lime kilns can be retrofitted without significant complexity.

[0026] Each shaft preferably has at least one exhaust gas outlet, for example at the upper end of the shaft within the preheating zone. The exhaust gas outlet is preferably located above the material column in the material-free area of ​​the preheating zone. Each shaft preferably has at least one cooling gas outlet, wherein preferably only the cooling gas outlets in shafts operating as regenerative shafts are open, and the cooling gas outlets in combustion shafts are hydrodynamically closed. The PFR shaft kiln preferably has one or more burner lances arranged such that they open into the combustion zone, with the cooling gas outlets located downstream of the opening of at least one burner lance in the gas flow direction of the regenerative shaft. The cooling gas outlets are preferably located downstream of the openings of all burner lances in the gas flow direction.

[0027] Preferably, each shaft has a cooling gas outlet, wherein each cooling gas outlet is provided with a corresponding control element for regulating the amount of cooling gas to be discharged through the cooling gas outlet, and wherein the control element assigned to the cooling gas outlet of the combustion shaft is closed so that preferably no cooling gas can be discharged through the cooling gas outlet of the combustion shaft. The cooling gas outlet is preferably connected to a cooling gas extraction pipe arranged outside the shaft. The control element is preferably fluidically connected to the cooling gas outlet and is particularly arranged in the cooling gas extraction pipe. The control element is, for example, a baffle or valve, which is infinitely movable between an open position and a closed position. The control element assigned to the cooling gas outlet of the regenerator shaft is preferably configured and adapted such that 85% to 115%, particularly 90% to 110%, preferably 105% of the amount of cooling gas supplied to the PFR shaft kiln is discharged as cooling gas exhaust air through the cooling gas outlet of the regenerator shaft. Cooling gas extraction pipes are connected, for example, to combustion gas inlets, and in particular to exhaust gas return pipes for guiding exhaust gas discharged from exhaust gas outlets, so that cooling gas discharged from cooling gas outlets is supplied to combustion gas inlets, particularly to the combustion zone of the combustion shaft. In such interconnections, it is advantageous that no CO2-containing gases are discharged into the atmosphere via cooling gas outlets, but rather all of the exhaust gas is preferably supplied via the exhaust gas outlets for further treatment or storage.

[0028] The cooling gas outlet is preferably located in the area opposite the transfer port on the outer wall of the preheating or combustion zone. The PFR shaft kiln preferably has direct or indirect transfer ports for directly or indirectly connecting the combustion shaft to the regenerative shaft. For example, the PFR shaft kiln has an annular channel that fluidly connects the shafts to each other at the same level as the transfer port. Alternatively, the PFR shaft kiln may not have an annular channel; in this case, the shafts are fluidly connected directly to each other via the transfer port. Exemplarily, the combustion and preheating zones of the shaft have a substantially constant cross-section along the shaft length. The outer wall of the shaft, pointing radially outward from the transfer port, extends vertically only along the entire shaft length, particularly along the length of the combustion and cooling zones. The cooling zone preferably has a cross-section that expands in the direction toward the transfer port and opens into the transfer port. The shaft of the PFR shaft kiln is preferably completely filled with material, such that no unfilled annular space is formed, particularly in the combustion and cooling zones, at the level of the transfer port.

[0029] For example, the cooling gas outlet in the outer wall of the shaft extends horizontally. The cooling gas outlet is preferably designed as a horizontal channel. In particular, the cooling gas outlet extends across the entire width of the outer wall of the shaft opposite the transfer port. The cooling gas outlet includes, for example, multiple channel openings in the outer wall of the shaft, which are arranged adjacent to each other in the horizontal direction and preferably on a single horizontal plane. Optionally, the cooling gas outlet is designed as an annular channel. In the case of a PFR shaft kiln with partitioned walls as described above, for example, recirculated and oxygen-enriched exhaust gas is introduced via the cooling gas outlet into a cooling gas duct between the partitioned sections and the shaft walls opposite the transfer port.

[0030] According to a further embodiment, at least one or more control elements are arranged in the cooling gas duct and designed to control, in an open-loop or closed-loop manner, the amount of cooling air from the cooling gas outlet and / or to the cooling gas inlet. The control elements are, for example, baffles, fans, or valves. Preferably, a control device is provided, connected to the control elements, and specified and designed to control, in an open-loop or closed-loop manner, the amount of cooling gas discharged via the cooling gas outlet and / or flowing to the cooling air inlet, particularly as a function of the desired CO2 proportion in the exhaust gas. The control elements are preferably specified such that the cooling gas is supplied only to the heat storage shaft via the cooling gas inlet, particularly to the preheating zone of the heat storage shaft.

[0031] According to a further embodiment, the transfer port has a first connecting channel and a second connecting channel, which are arranged in parallel hydrodynamically. The connecting channels are preferably arranged separately from each other. The first connecting channel is, for example, arranged above the second connecting channel.

[0032] According to a further embodiment, the first connecting channel is arranged and designed such that only exhaust gas from the combustion zone can flow into the first connecting channel. According to a further embodiment, the second connecting channel is arranged and designed such that only cooling gas from the cooling zone can flow into the second connecting channel. This ensures that cooling gas from the combustion shaft is introduced into the heat storage shaft independently of the combustion gas, and that mixing of combustion gas and cooling gas in the transfer port is reliably prevented.

[0033] The first connecting channel is designed, for example, as a direct transfer port and the second transfer port is designed as an indirect transfer port. The PFR vertical kiln has, for example, an annular channel in the form of a material-free space, which is preferably fluidically connected to the transfer port, especially to the first or second connecting channel.

[0034] The exhaust gas discharged from the shaft via the exhaust outlet preferably has a CO2 content of at least 70%, particularly at least 85%, and preferably at least 90 to 95% by volume. Optionally, the exhaust gas, for example, used in the soda or sugar industry, has a CO2 content of 35% to 45% by volume, wherein in particular, no exhaust gas is returned to the combustion shaft.

[0035] The present invention also includes a method for burning materials (e.g., carbonate rocks) in a co-current regenerative vertical kiln, wherein the explanations and advantages described regarding the co-current regenerative vertical kiln are similarly applicable to this method.

[0036] In a method for burning material (e.g., carbonate rock) in a co-current regenerative vertical kiln having two shafts, the shafts operate alternately as combustion shafts and as regenerative shafts and are connected to each other via transfer ports. 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 material to a material outlet, wherein cooling gas is introduced into the cooling zone, and exhaust gas is discharged from one of the shafts via an exhaust gas outlet. The cooling gas is guided from the cooling zone to the preheating zone via a cooling gas conduit.

[0037] The exhaust gas discharged from the shaft via the exhaust outlet is preferably supplied to the combustion shaft. The exhaust gas may be introduced, for example, into the preheating zone of the shaft that operates as a combustion shaft.

[0038] According to one embodiment, the cooling gas is guided separately from the combustion gas in the combustion zone to the preheating zone in a cooling gas duct. Preferably, the cooling gas is guided to the preheating zone parallel to the combustion gas in the combustion zone.

[0039] In a further embodiment, the cooling gas is preferably discharged only from the thermal storage shaft.

[0040] According to a further embodiment, cooling gas is drawn from the cooling zone and introduced into the preheating zone. In particular, the cooling gas is introduced into the lower region of the preheating zone adjacent to the combustion zone.

[0041] According to a further embodiment, cooling gas introduced into the preheating zone via a cooling gas pipe is discharged from the preheating zone via a cooling gas outlet. Specifically, the cooling gas is discharged from the shaft via a cooling gas outlet located at the upper end of the preheating zone. The amount of cooling gas discharged from the regenerator shaft via the cooling gas outlet is preferably adjusted by means of a control element. Preferably, 85% to 115%, particularly 90% to 110%, and preferably 105% of the cooling gas supplied to the PFR shaft kiln is discharged as cooling gas exhaust air via the cooling gas outlet.

[0042] The aforementioned PFR vertical kiln and the method for operating the PFR vertical kiln enable the achievement of a CO2 content of at least 30%, particularly at least 50%, preferably at least 70% up to at least 90% by volume in the exhaust gas. This allows for further treatment of the exhaust gas or storage of CO2-containing exhaust gas in other industrial processes. Attached Figure Description

[0043] The present invention will be explained in more detail below based on several exemplary embodiments and with reference to the accompanying drawings.

[0044] Figure 1 A schematic diagram of a PFR vertical kiln in cross-section is shown according to an exemplary embodiment.

[0045] Figure 2a , Figure 2b Each shows a schematic diagram of the gas flow path of a PFR vertical kiln in a longitudinal cross-sectional view according to a further exemplary embodiment.

[0046] Figure 3 A schematic diagram of a PFR vertical kiln in a longitudinal cross-section is shown according to a further exemplary embodiment.

[0047] Figure 4a A schematic diagram of a PFR vertical kiln in a longitudinal cross-section is shown according to a further exemplary embodiment.

[0048] Figure 4b A schematic diagram of the gas flow path of a PFR vertical kiln according to a further exemplary embodiment is shown in a cross-sectional view.

[0049] Figure 5a A schematic diagram of a PFR vertical kiln in a longitudinal cross-section is shown according to a further exemplary embodiment.

[0050] Figure 5b A schematic diagram of the gas flow path of a PFR vertical kiln according to a further exemplary embodiment is shown in a cross-sectional view.

[0051] Figure 6 A schematic diagram of a PFR vertical kiln in a longitudinal cross-section is shown according to a further exemplary embodiment. Detailed Implementation

[0052] Figure 1 A PFR vertical kiln 1 is shown with two parallel and vertically aligned shafts 2. The shafts 2 of the PFR vertical kiln 1 are of substantially the same construction, and therefore... Figure 1Only one of the two shafts 2 is fully provided with reference numerals, and for simplicity, only one of the two shafts 2 will be described in the following description in most cases. Each shaft 2 has a corresponding material inlet 3 for introducing the material to be burned into the corresponding shaft 2 of the PFR vertical kiln 1. The material to be burned is, in particular, limestone and / or dolomite, preferably having a particle size of 10 to 200 mm, more preferably 15 to 120 mm, and most preferably 30 to 100 mm. Exemplarily, the material inlet 3 is arranged at the upper end of the corresponding shaft 2, such that the material falls into the shaft 2 under gravity through the material inlet 3. The material inlet 3 is, for example, in the form of an upper opening in the shaft 2 and, in particular, in the form of a lock 3, and preferably extends across all or part of the cross-section of the shaft 2. The material inlet in the form of a lock 3 is preferably configured such that only the raw material to be burned enters the shaft 2, and not the ambient air. The lock 3 is preferably configured such that it airtightly seals the shaft 2 from the environment and allows solids (such as the material to be burned) to enter the shaft.

[0053] Each shaft 2 further has a combustion gas inlet 12 at its upper end for introducing combustion gas for burning fuel. The combustion gas is, for example, dust removal exhaust gas from at least one shaft 2, wherein the exhaust gas is optionally enriched with oxygen. Furthermore, each shaft 2 has an exhaust gas outlet 6 for discharging exhaust gas from the respective shaft 2. Exemplarily, corresponding control elements are assigned to each exhaust gas outlet 6 and combustion gas inlet 12. The control elements (e.g., baffles, valves, or adjustable volumetric compressors) are preferably capable of regulating the amount of combustion gas in the respective combustion gas inlet 12 and the amount of exhaust gas to be drawn through the respective exhaust gas outlet 6. Exemplarily, the combustion gas inlet 12 and exhaust gas outlet 6 are arranged at the same level and particularly within the preheating zone 21 of the respective shaft 2.

[0054] Arranged at the lower end of shaft 2 is a material outlet 40 for discharging the combusted material. Material outlet 40 is, for example, a lock as described with reference to material inlet 3. The combusted material is passed, for example, into an outlet funnel 25, to which material outlet 40 of shaft 2 is connected. Exemplarily, outlet funnel 25 is funnel-shaped. Outlet funnel 25 preferably has a cooling gas inlet 23 for introducing cooling gas into the corresponding shaft 2. The cooling gas is preferably delivered to cooling gas inlet 23 via compressor 33.

[0055] In the direction of material flow, below the material inlet 3 and / or the combustion gas inlet 12, is an adjacent preheating zone 21 of the corresponding shaft 2. The material and combustion gas are preferably preheated to approximately 700°C in the preheating zone 21. The corresponding shaft 2 is preferably filled with the material to be burned. The material is preferably supplied to the corresponding shaft 2 above the preheating zone 21. At least a portion of the preheating zone 21 and a portion of the corresponding shaft 2 following it in the direction of material flow are surrounded, for example, by a refractory lining.

[0056] Multiple burner nozzles 10 are optionally arranged in the preheating zone 21, each serving as an inlet for fuel (such as fuel gas, oil, or ground solid fuel). Multiple, for example twelve or more, burner nozzles 10 are preferably arranged at substantially uniform intervals between each other in each shaft 2. For example, the burner nozzles 10 are L-shaped and preferably extend horizontally into the respective shaft 2 and vertically, particularly in the direction of material flow, inside the shaft 2. The ends of the burner nozzles 10 in the shaft 2 are preferably all arranged at the same height level. Preferably, the plane on which the nozzle ends are arranged is, in each case, the lower end of the respective preheating zone 21. The burner nozzles 10 are preferably connected to fuel conduits 9 for guiding fuel to the burner nozzles 10. Exemplarily, the fuel conduits 9 are at least partially in the form of annular conduits extending circumferentially around the respective shaft 2. Preferably, each shaft 2 has fuel conduits 9, which are respectively assigned to the burner nozzles 10 of the shaft 2 and, in particular, have corresponding control elements for regulating the amount of fuel supplied to the burner nozzles 10.

[0057] The preheating zone 21 is adjacent to the combustion zone 20 in the direction of material flow. The burner lance 10 opens into the combustion zone 20, for example. The flame of the burner lance 10 preferably extends into the combustion zone 20. In the combustion zone 20, fuel is burned and the preheated material is burned at a temperature of approximately 1000°C. The combustion of fuel occurs, for example, with an excess of air relative to stoichiometry. Preferably, complete combustion of the fuel occurs primarily only within the combustion zone 20 of the combustion shaft. It is also conceivable that afterburning of incompletely burned fuel within the combustion zone 20 occurs in the transfer port and / or the regenerator shaft.

[0058] Exemplarily, the PFR vertical kiln 1 further has a transfer port 19 for fluidly connecting the two shafts 2 to each other. The transfer port 19 includes, exemplarily, two connecting channels 19a and 19b. Exemplarily, the connecting channels 19a and 19b are arranged parallel and separate from each other. Exemplarily, the connecting channels 19a and 19b are fluidly separated from each other by a particularly horizontal separating element 13 (e.g., a partition wall). The vertical kiln 1 includes, exemplarily, a first connecting channel 19a, which is particularly directly connected to the combustion zone 20 and preferably arranged above the second connecting channel 19b. The first connecting channel 19a is, exemplarily, arranged and designed such that only exhaust gas from the combustion zone 20 can be introduced into it. The first connecting channel 19a and the second connecting channel 19b are optionally each designed as a material-free space containing no material to be burned. The second connecting channel 19b is preferably arranged below the first connecting channel 19a and is particularly in direct fluid connection with the cooling zone 22. The second connection channel 19b is, by way of example, arranged and designed such that only cooling gas from the cooling zone 22 can be introduced into the second connection channel 19b.

[0059] Figure 1 An exemplary PFR vertical kiln 1 is shown, having a transfer port 19, which, exemplary, includes first and second connecting channels 19a and b. The vertical kiln 1 has, for example, an angular shaft cross-section. It is also conceivable that the shafts 2 of the PFR vertical kiln 1 have triangular, square, rectangular, circular, elliptical, polygonal, semi-circular, partially circular, or circular cross-sections. The transfer port 19, for example, forms a fluid connection between two shafts 2, wherein cooling gas from the combustion shaft 2a, particularly separate from the combustion gas from the combustion shaft 2a, flows into the transfer port 19 and then into the regenerative shaft 2b. Preferably, the first connecting channel 19a is designed as a direct connecting channel 19a, wherein the second connecting channel 19b is, exemplary, also designed as a direct connecting channel 19b.

[0060] Exemplarily, the combustion zone 20 extends within a shaft portion having a substantially constant cross-section. Exemplarily, the shaft portion extends through its lower region into, or directly adjoins with, the upper region of the cooling zone 22, such that an annular channel, particularly 18, is formed between the combustion zone 20 and the cooling zone 22. The side channel 18 forms a material-free space in which no material to be burned is disposed. The side channel 18 preferably extends longitudinally over the lower region of the combustion zone 20 and / or the upper region of the cooling zone 22 relative to the shaft wall opposite to the connecting channel. The side channel 18 is preferably arranged at the level of the transfer port 19. Exemplarily, the cross-section of the shaft portion of the cooling zone 22 is larger than the cross-section of the lower region of the combustion zone 20, such that a material-free space 18, particularly in the form of a side channel, is formed at the upper end of the cooling zone 22, in which no material is disposed, and adjacent to the combustion zone 20.

[0061] Similarly, it is conceivable that the combustion zone 20 and preheating zone 21 of shafts 2a and 2b have substantially constant cross-sections along the length of the shaft. The outer wall of shaft 2, pointing radially outward from the transfer port, extends vertically only along the entire length of the shaft, particularly along the length of the combustion zone 20 and cooling zone 22. Cooling zone 22 preferably has a cross-section that expands in the direction toward the transfer port 19 and opens into the transfer port 19. Shaft 2 of the PFR shaft kiln 1 is preferably completely filled with material, so that no material-free spaces are formed, especially in the combustion zone 20 and cooling zone 22.

[0062] Combustion zone 20 is adjacent to cooling zone 22 in each shaft 2 in the direction of material flow, and cooling zone 22 extends as far as material outlet 40. Cooling zone 22 is, by way of example, formed in a shaft portion having a substantially constant or downwardly tapering cross section. Material is cooled to approximately 100°C to 250°C within cooling zone 22 with cooling gas flowing counter-currently through the material.

[0063] Cooling gas flowing into cooling zone 22 via cooling gas inlet 23 preferably flows entirely to cooling gas outlet 42, which is preferably designed as an opening in the shaft wall or as a side passage. From cooling gas outlet 42, cooling gas flows out entirely from the respective shaft 2, preferably only from cooling zone 22 of shaft 2. Exemplarily, cooling gas outlet 42 is connected to cooling gas conduit 44, which is arranged outside shaft 2. Cooling gas outlet 42 is connected, in particular, via cooling gas conduit 44 to cooling gas inlet 43 for introducing cooling gas into shaft 2. Cooling gas outlet 42 is preferably arranged entirely within cooling zone 22, particularly within material-free side passage 18, wherein cooling gas inlet 43 is arranged within preheating zone 21, particularly at the lower end of preheating zone 21 of respective shafts 2a, b. Preferably, each shaft 2, the combustion shaft and the heat storage shaft, has a corresponding cooling gas outlet 42 and a corresponding cooling gas inlet 43, which are connected to each other via cooling gas pipes 44 for guiding cooling gas from the cooling gas outlet 42 to the cooling gas inlet 43.

[0064] exist Figure 1 In an exemplary embodiment, cooling gas discharged from cooling zone 22 via cooling gas outlet 44 is supplied to cooling gas inlet 43, particularly to preheating zone 21, via a cooling gas conduit 42 that is designed as a bypass to combustion zone 21. Cooling gas inlet 43 is preferably arranged in preheating zone 21 and is particularly designed as an opening in the shaft wall of preheating zone 21. Cooling gas inlet 43 is designed, for example, as a groove in the shaft wall, which extends particularly horizontally. Cooling gas conduit 44 has a control element 8, such as a baffle or valve, designed, for example, in such a way that the amount of cooling gas to be discharged via cooling gas outlet 42 is adjustable. Control element 8 is preferably adjusted in such a way that the entire amount of cooling gas is discharged from cooling zone via cooling gas outlet 42 and supplied back to cooling gas inlet 43.

[0065] The PFR vertical kiln 1 preferably has a cooling gas outlet 17 for discharging cooling gas from the shaft 2, particularly from the regenerator shaft 2b. The cooling gas outlet 17 is arranged, exemplarily, in the preheating zone 21 of the PFR vertical kiln 1, particularly in the preheating zone 21 of the regenerator shaft 2b and / or the combustion shaft 2a. Each shaft 2 preferably has a cooling gas outlet 17. The cooling gas outlet 17 is particularly arranged in the outer wall of the shaft 2, preferably in the outer wall of the preheating zone 21 or the combustion zone 20, and extends completely through said outer wall and protrudes from the respective shaft 2. The cooling gas outlet 17 is preferably arranged entirely within the preheating zone 21, such that cooling gas is drawn out from the preheating zone 21 and the shaft 2 via the cooling gas outlet 17. The cooling gas outlet 17 is preferably fluidically connected to the preheating zone 21, such that cooling gas is preferably able to flow through the preheating zone 21 and then through the cooling gas outlet 17. The cooling gas outlet 17 is preferably arranged in the region of the outer wall of the preheating zone 21 away from the transfer port 19. Cooling gas outlet 17 is preferably located in the outer wall of shaft 2, especially heat storage shaft 2b, opposite to transfer port 19.

[0066] The unloading device 41 is preferably arranged at the material outlet end of each shaft 2. The unloading device 41 includes, for example, a horizontal plate, preferably an unloading platform, which allows material to pass laterally between the unloading platform and the shell wall of the PFR shaft kiln. The unloading device 41 is preferably designed as a sliding platform or a turntable or as a platform with a pushable scraper. This makes it possible to achieve a uniform throughput of the material to be burned through the shaft 2. Exemplarily, the unloading device 41 further includes an outlet funnel 25 adjacent to the unloading platform and has a material outlet 40 attached to its lower end.

[0067] In the operation of the PFR vertical kiln 1, the material to be burned flows from top to bottom through the corresponding shaft 2, while cooling air flows from bottom to top in a counter-current flow to the material through the corresponding shaft 2. Kiln exhaust gas is discharged from the shaft 2 through exhaust outlet 6. In the operation of the PFR vertical kiln 1, one shaft 2 is active at any given time, while the corresponding other shaft 2 is passive. The active shaft 2a is referred to as the combustion shaft and the passive shaft 2 as the regenerative shaft 2b. The PFR vertical kiln 1 is operated in a particularly cyclical manner, typically with a cycle number of, for example, 75 to 150 cycles per day. After the cycle time has elapsed, the function of the shaft 2 is switched. This process is repeated continuously. Material (such as limestone or dolomite) is alternately supplied to the shaft 2 via material inlet 3. In the active shaft 2 operating as combustion shaft 2a, fuel is introduced into the combustion shaft 2 via burner lance 10. The material to be burned is heated in the preheating zone 21 of the combustion shaft 2a, preferably to a temperature of approximately 700°C. Figure 1 In an exemplary embodiment, the left vertical shaft 2 operates as a combustion vertical shaft 2a, while the right vertical shaft 2 operates as a heat storage vertical shaft 2b.

[0068] In the operation of the PFR vertical kiln 1, in both the combustion shaft 2a and the regenerator shaft 2b, the cooling gas flows counter-currently through the material to be cooled through the cooling zone 22 and is preferably completely guided into the cooling gas duct 44, which is arranged separately from the combustion zone.

[0069] Within shaft 2, which operates as combustion shaft 2a, combustion gases flow into the combustion shaft through combustion gas inlet 12 and flow concurrently with the material into transfer port 19 within combustion zone 20, and then into shaft 2, which operates as heat storage shaft 2b. Within heat storage shaft 2b, gases flow counter-currently from connecting channel 19 through combustion zone 20 into preheating zone 21 and exit heat storage shaft 2b through exhaust gas outlet 6. The exhaust gas discharged from shaft 2 is preferably at a temperature between 60°C and 160°C, preferably 100°C.

[0070] The exhaust gas is directed into an exhaust gas duct 39 connected to the exhaust gas outlet 6. Optionally, the exhaust gas duct 39 has an exhaust gas filter 31 downstream of the exhaust gas outlet 6 in the direction of exhaust gas flow for filtering fine particles, particularly dust, from the exhaust gas. The PFR vertical kiln 1 preferably includes multiple control elements, wherein corresponding control elements are assigned to the respective exhaust gas outlet 6 or combustion gas inlet 12 to control the flow to or from the exhaust gas outlet 6 and combustion gas inlet 12 in a closed loop. The control elements are, for example, throttling baffles or compressors. The combustion gas inlet 12 is preferably connected to an upstream control element such that the combustion gas, particularly the oxidant, along with the returned exhaust gas, is preferably supplied only to the combustion gas inlet 12 of the shaft 2, which operates as a combustion shaft 2a.

[0071] Exemplary, the exhaust gas duct 39 has a compressor 34 and a cooling device 32 downstream of the exhaust gas filter 31. The exhaust gas is preferably discharged downstream of the cooling device 32. Preferably, the entire amount of CO2 from calcination and combustion, as well as water from combustion, is discharged from the PFR vertical kiln 1. The cooling device 32 is, for example, a heat exchanger, which preferably operates countercurrently to a coolant (such as water). For example, the cooling device 32 is a trickle cooler. The PFR vertical kiln 1 has an exhaust gas return duct 15, which branches off from the exhaust gas duct 39 and supplies a portion of the exhaust gas to the shaft 2, particularly the combustion gas inlet 12 of the combustion shaft 2a. The exhaust gas return duct 15 is preferably connected to the combustion gas inlet 12 and branches off from the exhaust gas duct 39, particularly downstream of the cooling device 32. Exhaust gas not supplied to the combustion gas inlet 12 by the exhaust gas return duct 15 is preferably discharged from the PFR vertical kiln 1. The exhaust gas return duct 15 is, by way of example, connected to the oxidant duct 14 for guiding the oxidant into the exhaust gas return duct 15. The oxidant is, preferably, air or pure oxygen. The oxidant is, for example, an oxygen-enriched gas having an oxygen content of at least 30%, particularly at least 50% or 60%, preferably 70% to 100%, and preferably 92% by volume. The oxidant duct 14 is preferably connected to an oxidant source and preferably includes control elements for adjusting the amount of oxidant entering the exhaust gas return duct 15.

[0072] The PFR vertical kiln 1 preferably includes a buffer tank 45, which is preferably supplied with exhaust gas that has not been recirculated by the exhaust gas return duct 15. The buffer tank 45 is designed to temporarily store a certain amount of exhaust gas before, for example, drawing it out for further treatment. Exemplarily, at least one fan is arranged upstream and downstream of the buffer tank in each case in the direction of exhaust gas flow.

[0073] Figure 1 The gas flow within the PFR kiln 1 is also shown, with CO2-containing combustion gases indicated by shaded black arrows and oxygen-containing cooling gases indicated by shaded white arrows. According to an inventor's discovery, the oxygen-containing cooling gases flow into the preheating zone 21 along the outer wall of the regenerator 2b, opposite the transfer port 19, in the regenerator 2b and / or combustion 2a. The oxygen-containing cooling gases preferably flow substantially separately from the combustion gases within the 2b, resulting in only very slight mixing of the combustion and cooling gas flow streams. Returning the extracted cooling gases to the preheating zone offers the advantage that the heat from the cooling gases is additionally available for the PFR kiln 1 to heat the material in the preheating zone 21. In the PFR kiln 1 according to the invention, the cooling air preferably flows through a large portion of the bed in the preheating zone, particularly almost the entire height, and has a relatively low outlet temperature. This results in optimal thermal balance, and as a result, the PFR kiln 1 does not require additional structural height. Furthermore, a regenerator arranged downstream of the cooling gas outlet to utilize waste heat is eliminated.

[0074] The cooling gas outlet 17 is preferably located at the end of the burner nozzle 10 in the gas flow direction of the heat storage shaft 2b, particularly downstream of the fuel outlet. The cooling gas outlet 17 is preferably located downstream of the exhaust gas outlet 6 in the material flow direction.

[0075] The cooling gas outlet 17 is designed, for example, in the shape of a trough. In particular, the cooling gas outlet 17 preferably extends horizontally across the entire width of the outer wall of the shaft. It is also conceivable that the cooling gas outlet 17 has a plurality of openings extending through the outer wall of the shaft 2, especially the preheating zone 21, said openings being arranged adjacent to each other horizontally over the total width of the outer wall of the shaft 2 and preferably evenly spaced from each other.

[0076] The burner nozzle 10 includes, for example, a cover, which in Figure 1 Not shown, the covers are arranged in the respective shafts 2 upstream of the inlet of the burner lance 10 in the direction of material flow. The covers are designed and arranged such that they respectively protect at least the upper region of the burner lance 10 from contact, especially impact, with material on the burner lance 10. Cooling gas outlets 17 are arranged above or below the covers. The shafts 2 preferably have a lining, which in particular includes a refractory lining. The cooling gas outlets 17 are preferably arranged on the upper end region of the refractory lining.

[0077] The PFR vertical kiln 1 preferably has a cooling gas extraction duct 11 connected to a cooling gas outlet 17 for drawing cooling air out of the shaft 2. The cooling gas extraction duct 11 is arranged outside the shaft 2 and connected to a filter 16. The filter 16 is preferably a particulate filter, particularly a dust filter. The cooling air extracted via the cooling air outlet 17 preferably has a temperature of 100°C to 300°C. Exemplarily, the cooling air extraction duct 11 of the PFR vertical kiln 1 includes control elements 8, such as baffles or valves, for regulating the amount of cooling air extracted from the preheating zone 21 via the cooling gas outlet. The cooling gas extraction duct 11 is exemplarily supplied with air via a compressor or fan. The cooling gas extraction duct 11 includes, for example, at least two control elements, each control element 8 being assigned to a corresponding cooling gas outlet 17 for regulating the corresponding amount of cooling gas. Preferably, only the control element 8 assigned to the shaft 2 operating as a heat storage shaft 2b is open, while the control element 8 assigned to the combustion shaft 2a is closed. The cooling gas is preferably discharged from the PFR shaft kiln 1 downstream of filter 16. It is also conceivable that the cooling gas extraction conduit 11 is connected to the oxidant conduit 14, and in particular the combustion gas inlet 12, resulting in the extracted cooling air being supplied as combustion gas to the combustion shaft 2a. In this type of interconnection, it is advantageous that no CO2 is emitted into the atmosphere via the cooling gas outlet 17; instead, all of the cooling gas is discharged with the exhaust gas and then preferably post-treated or stored.

[0078] The PFR vertical kiln 1 optionally has a heat exchanger 24 connected to an exhaust gas return pipe 15 and a cooling air extraction pipe 11. Figure 1 The PFR vertical kiln 1 preferably has a waste gas with a CO2 content of more than 70%, particularly more than 75%, and especially more than 90% by volume. Such process waste gas can be liquefied and stored at a relatively low level of complexity. For example, the liquefied process waste gas can be supplied to further process steps or for storage. The aforementioned PFR vertical kiln can also be used to produce waste gas with even lower CO2 content, such as 45% for soda production or 30% for beet sugar or precipitated calcium carbonate production.

[0079] Preferably, each shaft 2 has a cooling gas inlet 23, which is arranged in the cooling zone 22 and specifically connected to the cooling gas supply pipe 7. Exemplarily, each cooling gas inlet 23 is provided with a corresponding control element 4, such as a baffle or valve, connected to the cooling gas supply pipe 7 for regulating the amount of cooling gas supplied to the corresponding cooling gas inlet 23. Preferably, the control element 4 and / or compressor 33 are adjusted such that the combustion shaft 2a is supplied with a larger amount of cooling air than the heat storage shaft 2b. The combustion shaft 2a is preferably supplied with approximately 20% to 100% of the total cooling gas supplied to the PFR kiln 1, preferably 90%.

[0080] Figure 2a Show Figure 1 The PFR vertical kiln, and Figure 2b Show Figure 2a The cross section A / A of the PFR vertical kiln 1 shows the gas flow of cooling air K and combustion gas V. Figure 2a The PFR vertical kiln 1 has the aforementioned transfer port 19, which has a direct connection channel 19a for combustion gas and a direct connection channel 19b for cooling gas, so that cooling air in the heat storage shaft 2b flows through the preheating zone 21 of the heat storage shaft 2b along a side channel opposite to the transfer port 19. Figure 2b A cross-section through the preheating zone 21 is shown, in which the cooling gas flows only along the shaft wall away from the transfer port 19.

[0081] Figure 3 A further exemplary embodiment of the PFR vertical kiln is shown, which largely corresponds to Figure 1 The difference between the embodiment of and 2 is that the transfer port 19 is designed as a simple connection channel in which the combustion zone, especially the exhaust gas of the combustion gas and the cooling gas, are transported together.

[0082] Figure 4a Figures b illustrate further exemplary embodiments of the PFR vertical kiln, which largely correspond to Figure 1The embodiments of FIG. 2 are shown, and the same elements are given the same reference numerals. Exemplarily, the PFR vertical kiln 1 of FIG. 4 has shafts 2, each shaft 2 having a circular, particularly circular, cross-section. The PFR vertical kiln 1 of FIG. 4 has a cooling gas extraction device comprising an inner cylinder 26 extending at least partially from a cooling zone 22 into a combustion zone 20 and having a cooling gas outlet 42 connected to a cooling gas conduit 44. Exemplarily, the cooling zone 22 is formed in a shaft portion having an approximately constant cross-section. Figure 1 The material-free annular space of the PFR vertical kiln is also in Figure 4a Formed in an exemplary embodiment. Figure 4a Each shaft 2 of the PFR vertical kiln 1 has an inner cylinder 26 that extends vertically through the cooling zone 22. Exemplarily, the inner cylinder 26 extends from the unloading device 41 through the cooling zone 22 into the combustion zone 20, as far as the level of the transfer port 19.

[0083] The inner cylinder 26 of the cooling gas extraction device has a cooling gas outlet 42, which extends radially outward from the inner cylinder 26 through the shaft wall and guides cooling gas from the inner cylinder into a cooling gas conduit 44. The inner cylinder 26 also has a cooling gas inlet 30 for introducing cooling gas from the cooling zone 22 into the inner cylinder 26. The cooling gas inlet 30 extends through the inner cylinder wall into the cooling zone 22 and connects the interior of the inner cylinder 26 with the cooling zone 22. The cooling gas inlet 30 is preferably located in the cooling zone 22 above the cooling gas outlet 42. During operation of the PFR vertical kiln 1, cooling gas flows upward from the bottom through the cooling zone 22 and enters the inner cylinder 26 of the cooling gas extraction device through the cooling gas inlet 30. Preferably, all cooling gas introduced into the cooling zone 22 flows through the cooling gas inlet 30 into the cooling gas extraction device, and therefore no cooling gas enters the combustion zone 20. The cooling air outlet 42 of the inner cylinder 26 is preferably located in the lower region of the cooling zone 22. In particular, cooling gas flows downwards from cooling gas inlet 30 to cooling gas outlet 42 within the inner cylinder 26. Exemplarily, the cooling gas conduit 44 includes at least two control elements 8. Preferably, in each case, one control element 8 is arranged downstream of the corresponding cooling gas outlet 42 and is designed and specified such that the amount of cooling gas flowing through the cooling gas outlet 42 is adjustable via the control element 8. A further control element 8 is preferably arranged upstream of the cooling gas inlet 43 in each case and is designed and specified such that the amount of cooling gas flowing into the cooling gas inlet 43 is adjustable via the control element 8. The cooling gas inlet 43 and / or the cooling gas outlet 17 are each designed, for example, as a trough, which preferably extends across the entire perimeter of the preheating zone 21.

[0084] In an exemplary embodiment, the paths of the cooling gas extracted from the cooling zone 22 and the preheating zone 21, and the path of the exhaust gas extracted from the preheating zone 21, correspond to a reference. Figure 1 Interconnections described in 2 and 3. Figure 4b A cross-section of the preheating zone passing through the heat storage shaft 2b is shown, illustrating combustion gas V, particularly the exhaust gas from combustion zone 20, and cooling gas K. According to a discovery by the inventors, the cooling gas K flows through the preheating zone only in the radially outer region of the shaft 2 close to the wall.

[0085] Figure 5a and Figure 5b A further exemplary embodiment of the PFR vertical kiln is shown, which largely corresponds to Figure 1 Embodiments 1, 2, 3, or 4, wherein the same elements are provided with the same reference numerals. Figure 5a The PFR vertical kiln also has a circular, especially circular, cross-section. Similar to... Figure 3 and 4, Figure 5a The vertical kiln also has a transfer port 19, which is designed as a single connecting channel 19. Combustion zone 20 extends exemplaryly in the first and second vertical shaft sections, wherein the first vertical shaft section has a substantially constant or slightly larger cross-section towards the bottom. The first vertical shaft section is adjacent to the second vertical shaft section in the material flow direction, and the second vertical shaft section has a shaft cross-section that decreases in the material flow direction. The first vertical shaft section extends through its lower region to the upper region of the second vertical shaft section, resulting in a first material-free annular channel 18a formed between the two shaft sections. The upper region of the second vertical shaft section has a larger cross-section than the first vertical shaft section, wherein the cross-section of the second vertical shaft section decreases to the cross-section of the first vertical shaft section in the material flow direction, preferably forming the lower end of combustion zone 20. Cooling zone 22 preferably has a further, second material-free annular space 18b, wherein the first annular space 18a is arranged at the level of the transfer port 19 and the second annular space 18b is arranged below the transfer port 19. Exemplarily, a cooling gas outlet 42 is arranged in the second annular channel 18b and connected to a cooling gas conduit 44.

[0086] Figure 5b A cross-section of the preheating zone 21 passing through the heat storage shaft 2b is shown, illustrating combustion gas V, particularly the exhaust gas from combustion zone 20, and cooling gas K. According to an inventor's discovery, the cooling gas K flows through the preheating zone 21 only in the radially outer region of the shaft 2 close to the wall. In an exemplary embodiment, the paths of the cooling gas extracted from the cooling zone 22 and the preheating zone 21, and the path of the exhaust gas extracted from the preheating zone 21, correspond to a reference. Figure 1 Interconnections described in 1, 2, 3 and 4.

[0087] Figure 6A further exemplary embodiment of the PFR vertical kiln is shown, which largely corresponds to Figure 1 In embodiments up to 5, the same elements are given the same reference numerals. The transfer port 19 includes two parallel, direct connecting channels 19a and 19b. Unlike the PFR vertical kiln 1 described above, Figure 6 The PFR vertical kiln 1 has a cooling gas duct 44 arranged inside the shaft 2. In each shaft 2, the PFR vertical kiln 1 has a partition wall 46, which is fluidly separated by its cooling gas duct 44. The partition wall 46 preferably extends vertically from the combustion zone 20 to the top cover of the shaft. In particular, the lower end of the partition wall 46 is arranged at the level of the transfer port 19, wherein the upper end of the partition wall 46 exemplarily abuts against the top cover of the shaft. In particular, the partition wall 46 extends across the entire width of the shaft, and in particular its depth, and is preferably aligned parallel to the shaft wall opposite to the transfer port 19. The partition wall 46, together with the inner wall of the shaft 2, especially the heat storage shaft 2b, preferably forms the cooling gas duct 44. Preferably, the partition wall 46 is arranged in the region of the shaft 2 opposite to the transfer port 19. Exemplarily, the cooling gas duct 44 comprises approximately 20–40%, preferably approximately 33%, of the volume of the combustion zone 20 and the preheating zone 21.

[0088] exist Figure 6 In an exemplary embodiment, a cooling gas outlet 42 for discharging cooling gas from the cooling zone 22 is formed between the partition wall 46 and the shaft wall opposite to the transfer port 19. Figure 6 The vertical kiln 1 also has a cooling gas outlet 17, which is located at the upper end of the preheating zone 21. The cooling gas outlet 17 of the combustion shaft 2a is preferably connected to a waste gas return pipe so that during the combustion operation of the corresponding shaft 2, the recirculated oxygen-enriched waste gas is introduced into the combustion shaft 2a via the cooling gas outlet 17. In particular, the oxygen-enriched waste gas recirculated via the cooling gas outlet 17 is introduced into a cooling gas pipe 44 between the partition wall 46 and the shaft wall opposite to the transfer port 19. Figure 6 The PFR vertical kiln 1 preferably has a further combustion gas inlet 12 in each shaft, through which oxygen-enriched exhaust gas, recirculated, is introduced into the combustion shaft 2a outside the cooling gas duct 44. According to an inventor's discovery, the cooling air preferably flows only in the outer shaft portion opposite the transfer port 19, such that the cooling air is hydrodynamically separated from the combustion gas in the combustion zone 20 by the partition wall 46. Mixing of the combustion gas and the cooling gas is thus reliably prevented.

[0089] Figure 6The vertical kiln 1 preferably has multiple material inlets 3. In particular, the vertical kiln 1 has at least two material inlets 3 in each shaft 2, wherein at least one material inlet is assigned to a cooling gas conduit 44 and arranged such that the material to be burned is supplied to the cooling gas conduit 44. In an exemplary embodiment, the paths of the cooling gases extracted from the cooling zone 22 and the preheating zone 21, and the path of the exhaust gas extracted from the preheating zone 21, correspond to reference... Figure 1 The interconnections described in section 5.

[0090] List of reference numerals in the attached diagram: 1 PFR vertical kiln 2 Shafts 2a Combustion Shaft 2b Thermal Storage Shaft 3 Material Inlet / Lock 4. Control Components 6. Exhaust gas outlet 7 Cooling gas supply pipeline 8 Control Components 9. Fuel Pipeline 10. Burner spray gun 11 Cooling gas extraction pipeline 12 Combustion Gas Inlet 13 Separating elements 14 Oxidizing agent pipeline 15. Exhaust gas recirculation duct 16 Filters 17 Cooling gas outlet 18 side passages / circular passages / material-free spaces 19 Transfer Port 19a First Connection Channel 19b Second Connection Channel 20 Combustion Zone 21. Preheating Zone 22 Cooling Zone 23 Cooling gas inlet 24 Heat Exchanger 25 Outlet Funnel 26 Inner Tube 30 Cooling gas inlet 31 Exhaust Gas Filter 32 Cooling device 33, 34, 35 Compressors 39. Exhaust gas duct 40 Material Export / Lock 41 Unloading device 42 Cooling gas outlet 43 Cooling gas inlet 44 Cooling gas pipeline 45 Buffer tank 46 partition walls K Cooling air V Combustion exhaust gas

Claims

1. A co-current regenerative vertical kiln (1) for burning and cooling materials such as carbonate rock, the co-current regenerative vertical kiln (1) having two shafts (2) that can be operated alternately as combustion shafts (2a) and as regenerative shafts (2b), and connected to each other via transfer ports (19), in, In the direction of material flow, each shaft (2) includes a preheating zone (21) for preheating the material, a combustion zone (20) for burning the material, and a cooling zone (22) for cooling the material. Each shaft (2) has an exhaust gas outlet (6) for discharging exhaust gas from the shaft (2). Its features are, The PFR vertical kiln (1) has a cooling gas pipe (44) for guiding cooling gas from the cooling zone (22) into the preheating zone (21).

2. The parallel-flow regenerative vertical kiln (1) according to claim 1, wherein, The cooling gas pipe (44) is located outside or inside the shaft (2).

3. The parallel-flow regenerative vertical kiln (1) according to any one of the preceding claims, wherein, The vertical kiln (1) has a cooling gas outlet (42) for discharging cooling gas from the cooling zone (22), and wherein the cooling gas outlet (42) is disposed within the cooling zone (22) and is fluidly connected to the cooling gas pipe (44).

4. The parallel-flow regenerative vertical kiln (1) according to any one of the preceding claims, wherein, The vertical kiln (1) has a cooling gas inlet (43) in the preheating zone (21), the cooling gas inlet (43) being used to introduce cooling gas into the preheating zone (21) and being fluidly connected to the cooling gas pipe (44).

5. The parallel-flow regenerative vertical kiln (1) according to claim 4, wherein, The cooling gas inlet (43) is designed in a slot shape.

6. The parallel-flow regenerative vertical kiln (1) according to any one of claims 1 to 3, wherein, The vertical kiln (1) has partition walls (46) disposed within the vertical shaft (2) and at least partially forming the cooling gas duct (44).

7. The parallel-flow regenerative vertical kiln (1) according to claim 6, wherein, The cooling gas outlet (44) is designed to discharge cooling gas from the cooling zone (22) between the partition wall (46) and the inner wall of the shaft (2).

8. The parallel-flow regenerative vertical kiln (1) according to any one of the preceding claims, wherein, The vertical kiln (1) has a cooling gas outlet (17) for discharging the cooling gas from the vertical shaft (2), and wherein the cooling gas outlet (17) is located in the preheating zone (21) of the vertical shaft (2).

9. The parallel-flow regenerative vertical kiln (1) according to any one of the preceding claims, wherein, At least one or more control elements (8) are disposed in the cooling gas duct (44) and are designed to control the amount of cooling air from the cooling gas outlet (42) and / or to the cooling gas inlet (43) in an open-loop or closed-loop manner.

10. The parallel-flow regenerative vertical kiln (1) according to any one of the preceding claims, wherein, The transfer port (19) includes a first connecting channel (19a) and a second connecting channel (19b), which are fluidly arranged in parallel.

11. The parallel-flow regenerative vertical kiln (1) according to claim 10, wherein, The first connecting channel (19a) is arranged and formed in such a way that only the exhaust gas from the combustion zone (20) can flow into the first connecting channel (19a).

12. The parallel-flow regenerative vertical kiln (1) according to claim 10 or 11, wherein, The second connection channel (19b) is configured and designed in such a way that only the cooling gas of the cooling zone (22) can flow into the second connection channel (19b).

13. A method for burning materials such as carbonate rock in a parallel-flow regenerative vertical kiln (1), the parallel-flow regenerative vertical kiln (1) having two shafts (2) that operate alternately as combustion shafts and regenerative shafts, and are connected to each other by a connecting channel (19), wherein, The material flows through the material inlet (3) into the preheating zone (21) for preheating the material, the combustion zone (20) for burning the material, and the cooling zone (22) for cooling the material, and reaches the material outlet (40). Cooling gas is introduced into the cooling zone. Among them, exhaust gas is discharged from one of the shafts (2) via exhaust gas outlet (6), and Its features are, The cooling gas is guided from the cooling zone (22) to the preheating zone (21) via a cooling gas pipe (44).

14. The method according to claim 13, wherein, The cooling gas is guided separately from the combustion gas in the combustion zone (20) in the cooling gas duct (44).

15. The method according to claim 13 or 14, wherein, The cooling gas is drawn from the cooling zone (22) and introduced into the preheating zone (21).

16. The method according to any one of claims 13 to 15, wherein, The cooling gas introduced into the preheating zone (21) via the cooling gas pipe (44) is discharged from the preheating zone (21) by means of the cooling gas outlet (17).

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