CEMENT CLINKER PLANT AND METHOD FOR SEPARATION OF A VOLATILE COMPONENT

Description

[0001] The invention relates to a plant, in particular a cement clinker plant, for separating a volatile component, in particular mercury, from flue gases, comprising: a mobile container with a supply line and a discharge line for the flue gases, wherein the mobile container is designed as a transportable swap body.

[0002] Furthermore, the invention relates to a process for separating a volatile component, in particular mercury, from flue gases, in particular from cement clinker production.

[0003] Various processes have already been proposed in the prior art for removing harmful components such as mercury from flue gases. EP 2 892 861, for example, describes how mercury is introduced into the process via the raw materials in cement clinker production. The raw materials for cement clinker production are passed through a preheater, exchanging heat with the kiln exhaust gases, and then fired in a rotary kiln. By heating the raw materials in the preheater, the mercury bound in the raw materials is evaporated. A portion of the flue gases is first dedusted using a hot gas filter and then brought to a temperature below 250 °C using an evaporative cooler. A sorbent such as activated carbon is then injected into the flue gases, to which the mercury is bound. The activated carbon is separated using a bag filter.The cleaned flue gas can then be returned to the process.

[0004] In addition to entrained-flow adsorption, EP 2 892 861 also mentions that mercury can be removed from the flue gases using a fixed-bed or moving-bed adsorber.

[0005] The use of a moving bed adsorber is also described in "Lignite coke moving bed adsorber for cement plants - BAT or beyond BAT?", Harald Schoenberger in Journal of Cleaner Production, 2011. In this process, the raw gas is passed through a moving bed reactor, which in this design has two modules. Each module contains two large-volume moving beds of coke. The moving beds consist of a thin layer for pre-cleaning and a thick layer for further cleaning. The exhaust gases are forced through the moving bed by a fan. The cleaned exhaust gas is collected in two central lines and discharged. The saturated coke is replaced every three hours with fresh coke, which moves downwards over time. At the bottom, the coke is removed and recycled to the thin moving beds via conveyors.

[0006] However, the disadvantage is the high cost of the moving-bed reactor, which requires particularly mobile equipment such as fans and conveyors. On the other hand, this state-of-the-art technology caused operational problems due to the spontaneous combustion of the activated carbon.

[0007] KR200410276 discloses a system for reducing emissions from exhaust gases. The dry emission control system is based on the adsorption of ionic mercury compounds using a fixed-bed adsorber, for example, based on a mixture of granular activated carbon or furnace coke. A dust collector is installed in the tube furnace.

[0008] The object of the invention is therefore to alleviate or eliminate at least some of the disadvantages of the prior art. The invention preferably aims to create a structurally simple and operationally reliable system and a corresponding method for the separation of volatile components such as mercury from flue gases. This object is achieved by a system according to claim 1 and a method according to claim 11. Preferred embodiments are specified in the dependent claims.

[0009] According to the invention, a plurality of containers, each filled with a fixed bed of a sorbent, in particular a carbon-containing and / or mineral sorbent, are arranged in the mobile container, and the mobile container has a holder for attaching a lifting device.

[0010] The flue gases are thus freed of the volatile component, in particular mercury, with the aid of a fixed bed adsorber. A preferably cuboid-shaped mobile or interchangeable container is provided as the fixed bed adsorber, in the interior of which several, in particular more than 5, preferably more than 10, for example more than 15, containers are arranged, each containing the fixed bed of the sorbent. Due to the fixed bed design, the sorbent is arranged stationary (i.e. immobile) during the separation of the volatile component. To reduce operating problems such as self-ignition, the sorbent is distributed among the individual containers in the mobile container. Advantageously, the temperature of the flue gas in the containers can thus be more than 40 °C, in particular more than 50 °C and preferably less than 210 °C, in particular less than 200 °C, without having to increase the fire protection measures.A carbon-containing sorbent, particularly pure activated carbon, particularly brominated activated carbon, can be used as the sorbent. Alternatively, a mixture of activated carbon and minerals, such as lime, can be used as the sorbent. These designs offer particularly high explosion protection. The flue gases are fed into the mobile container via the supply line and distributed among the individual containers. The flue gases preferably flow through the containers from bottom to top; however, flow through the containers from top to bottom is also possible. In this case, the volatile component, particularly gaseous mercury, is adsorbed on the sorbent. The inventive design of the fixed-bed adsorber is structurally particularly simple, compact, and reduces maintenance costs. It is particularly advantageous if the fixed-bed adsorber mobile container is free of a conveying device, such as a rotary valve, for the sorbent.For sorbent replacement, the containers are essentially hermetically sealed. Once hermetically sealed, the containers containing the loaded sorbent can be replaced with containers containing unloaded sorbent. This replacement can be done, for example, once a year. External disposal and treatment by qualified personnel is also particularly advantageous. The mobile container is designed as a transportable swap body.

[0011] The mobile container has a mounting bracket, for example, an eyelet, for attaching a lifting device, such as a crane. In a preferred embodiment, several, in particular four, mounting brackets, in particular eyelets, are provided. The mounting brackets are preferably designed so that the total weight of the mobile container with the containers can be supported by the mounting brackets.

[0012] In a preferred embodiment, the containers each have a perforated bottom, in particular a perforated plate, with first openings on the underside through which the flue gases can flow. Furthermore, the containers can each have a perforated lid, in particular a further perforated plate, on the top side through which the flue gases can flow.

[0013] To avoid the risk of self-ignition, the capacity of the containers (and thus the volume of the respective fixed bed) is preferably less than 300 liters (l), in particular less than 250 l, preferably less than 220 l . Furthermore, it is preferred if the capacity of the containers (and thus the volume of the respective fixed bed) is more than 100 liters, preferably more than 150 liters. For example, the capacity of the containers is essentially 200 liters. .

[0014] In a particularly preferred embodiment, the system comprises an additional mobile container with an additional supply line for flue gases to be freed of volatile components and an additional discharge line for flue gases freed of volatile components, wherein additional containers, each filled with a sorbent, are arranged in the additional mobile container. Therefore, in this embodiment, (at least) two mobile containers are provided, each with several containers for the sorbent. This allows the separation efficiency to be increased. A particular advantage is that in this series connection, the sorption potential can be fully utilized until the end, i.e., until breakthrough.

[0015] In a first switching position, the mobile container and the additional mobile container can be connected in series, with the mobile container's outlet connected to the additional supply line of the additional mobile container. Thus, the flue gases are first directed through the containers in the mobile container and then through the additional containers in the additional mobile container. This increases the separation efficiency for the volatile component, especially mercury.

[0016] In a second switching position, the mobile container and the additional mobile container can be connected in parallel, whereby the flue gases to be freed of the volatile component can be fed optionally to the supply line of the mobile container or the additional supply line of the additional mobile container. If the volatile component is separated exclusively with the additional mobile container in the parallel connection, the mobile container can be removed from the system in order to replace the fixed bed of sorbent loaded with the volatile component with an unloaded sorbent free of volatile component. Advantageously, the system does not have to be taken out of operation to replace the sorbent. For this purpose, the mobile container can be disconnected from the supply and discharge lines. For example, the supply and discharge lines can each be blocked with a blind flange.A crane can be used to remove the mobile container, which in a preferred design is connected to the support. The containers can then be disposed of. The mobile container is then refilled with fresh containers. While the containers are being exchanged, the flue gas can be directed through the other containers within the additional mobile container. The sorbent in the other containers of the additional mobile container is exchanged accordingly.

[0017] The additional mobile container with the additional containers is preferably identical to the mobile container with the containers. Thus, all preferred design variants of the mobile container can equally apply to the additional mobile container with the additional containers.

[0018] The container is preferably a barrel, in particular with a capacity of more than 100 liters, preferably more than 150 liters, for example, essentially 200 liters. The barrel preferably has a circular cross-section.

[0019] The mobile container is preferably designed as a cuboid with a length, a width and a height, wherein the length is preferably greater, in particular several times greater, than the width of the mobile container.

[0020] Preferably, the mobile container has a length of 5 meters (m) to 13 m, in particular substantially 12 m, a width of 2 m to 3 m, in particular substantially 2.5 m, and a height of 1.5 m to 3 m, in particular substantially 2 m.

[0021] Preferably, several rows, in particular at least three rows, each with several, in particular with more than three, for example with more than five, containers are provided in the interior of the mobile container.

[0022] To distribute the incoming flue gases among the individual containers in the mobile container, the mobile container preferably has an intermediate floor with passage openings, above which the containers containing the sorbent are arranged, in particular positioned. The intermediate floor preferably extends parallel to a floor of the mobile container. The intermediate floor is preferably arranged closer to the floor than to a ceiling of the mobile container. The containers preferably have openings on the underside through which the flue gases enter the respective fixed bed of sorbent.

[0023] The supply and discharge lines are preferably arranged in such a way that the flue gases flow through the containers within the mobile container from bottom to top.

[0024] For the purposes of this disclosure, location references such as "above," "below," "horizontal," and "vertical" refer to the intended arrangement of the system, in particular the mobile container, on a horizontal surface. Directional references such as "before" and "after" refer to the flow direction of the flue gases.

[0025] To dedust the flue gases before separating the volatile components, a dust filter, in particular a hot gas filter, is preferably arranged in front of the mobile container. The hot gas filter is designed to dedust the flue gases at a temperature of more than 250 °C. The dust separated by the hot gas filter can be recirculated. If the plant is designed as a cement clinker plant, the dust can be recirculated to the preheater.

[0026] In order to cool the flue gases to the appropriate temperature for the separation of the volatile components, one design variant includes a cooler, in particular an evaporative cooler or a heat exchanger, arranged between the dust filter and the mobile container. With the help of the cooler, the flue gases can be cooled to the temperature required for the separation of the volatile components, in particular less than 210 °C, for example to 50 to 200 °C. In the evaporative cooler, the exhaust gas stream is cooled by injecting extremely fine water droplets into the hot exhaust gas stream. The evaporation process extracts heat from the flue gases and reaches the desired temperature level for subsequent exhaust gas purification. However, the cooler can be designed as a heat exchanger. This avoids the disadvantages of an evaporative cooler, which in particular consist of the potential for clumping during the process.Furthermore, acidic gas components can react with the water from the quench, creating an acidic environment that is highly corrosive.

[0027] With a device for transferring heat from the flue gases upstream of the mobile container to the flue gases downstream of the mobile container, energy efficiency can be increased and corrosion reduced. The device can comprise a heat exchanger upstream of the mobile container and another heat exchanger downstream of the mobile container. A heat transfer medium can be routed between the heat exchanger and the additional heat exchanger.

[0028] If the flue gases are heavily contaminated with nitrogen oxides (NOx), an SCR module (SCR = Selective Catalytic Reduction) can be installed between the dust filter and the mobile container. In addition to denitrification, the SCR module can also serve to minimize the ammonia concentration in the flue gas. The ammonia is adsorbed by the activated carbon and neutralizes it. This would result in poorer adsorption of mercury, which requires an acidic environment for adsorption.

[0029] The process according to the invention for separating the volatile component, in particular mercury, from flue gases, in particular from cement clinker production, comprises at least the following steps: Feeding the flue gases into a mobile container in which several containers filled with a fixed bed of a sorbent, in particular a carbonaceous and / or mineral sorbent, are arranged; separating the volatile component of the flue gases on the sorbent in the containers; and discharging the flue gases from the mobile container.

[0030] In order to improve the separation of the volatile component in the flue gases, the flue gases can be passed through another mobile container after flowing through the mobile container, in which further containers are arranged, each filled with a sorbent, in particular a carbon-containing and / or mineral sorbent.

[0031] In a parallel circuit, the flue gases for exchanging the loaded sorbent in the containers of the mobile container can be led exclusively through the other containers of the other mobile container.

[0032] The method may further comprise the following step: dedusting the flue gases, in particular with a hot gas filter, before feeding the flue gases into the mobile container.

[0033] In a preferred application, a process for producing cement clinker is carried out with the following steps: Burning raw material to produce cement clinker in a kiln, separating a volatile component, in particular mercury, from flue gases produced in the kiln using a process in one of the embodiments described above.

[0034] The invention will be further explained below with reference to preferred embodiments in the drawings. Fig. 1 shows a schematic diagram of a cement clinker plant with a solid adsorber mobile container for removing mercury from the flue gases from the preheating tower. Fig. 2 shows in detail the mobile container, which contains several rows of containers with carbon-containing sorbent. Fig. 3 shows a section through the mobile container of the cement clinker plant. Fig. 4 shows an alternative plant scheme in which two mobile containers, each with containers for the carbon-containing sorbent, are operated either in series or in parallel.

[0035] In Fig. 1 A cement clinker plant 1 for producing cement clinker from raw material, in particular raw meal, is shown schematically. Plant 1 has a conventional plant design, symbolized here by field 2. This plant design 2 includes a (rotary) kiln, which can be connected to a clinker cooler on the one hand and to a preheating stage on the other. The preheating stage can have a cyclone cascade with several cyclones with which the raw material is preheated. For this purpose, the raw material can be fed into the uppermost cyclone of the preheating stage via a material feeder. The preheated raw material enters the rotary kiln, in which the raw material is fired to produce the cement clinker. The kiln exhaust gases or flue gases produced during combustion are passed through the preheating stage against the flow of the raw material. The plant can also have a calciner.The cement clinker plant 1 can further comprise a raw mill in which the raw material can be ground and dried, in particular with the aid of the flue gases.

[0036] In the embodiment of the Fig. 1 Flue gases are extracted from the plant structure 2, in particular from the preheating stage or from the calciner (see arrow 3). The flue gases are fed to a dust filter 4, here a hot gas filter. The hot gas filter has at least one filter element, preferably several filter elements, in particular filter candles, preferably made of ceramic or metal, on which the dust from the flue gases is separated. The separated dust can be fed into the preheater or fed to a silo (see arrow 5). The flue gases are then cooled to temperatures of 50 to 200 °C with the aid of a cooler, here designed as a heat exchanger 6, in order to enable the separation of a volatile component, in particular mercury, from the flue gases. The heat from the flue gases absorbed by the heat exchanger 6 can be used elsewhere in the cement clinker plant 1.

[0037] The dedusted and cooled flue gases are passed through a mobile container 7 with a flue gas inlet line 7A and an outlet line 7B to separate the volatile components. Finally, the flue gases freed of volatile components can be fed to an exhaust gas purification system 10.

[0038] The mobile container 7 for the reduction of the volatile component in the flue gases is in the Fig. 2 and 3 presented in detail.

[0039] Accordingly, the mobile container 7 is cuboid-shaped with a length, a width, and a height, wherein the length is preferably greater than the width. Arranged inside the mobile container 7 are several containers 8, each filled with a fixed bed 9, i.e., a stationary arrangement, in particular a bed, of preferably carbon-containing sorbent, also referred to as sorption agent. Barrels with a circular cross-section can be provided as containers 8. The capacity of the barrels can, for example, be substantially 200 liters. In the embodiment shown, the mobile container 7 has a floor 11A, side walls 11B, and a ceiling 11C. Furthermore, struts 12 are provided, preferably at least on the side walls 11B and the ceiling 11C. Within the mobile container 7, an intermediate floor 13 is arranged closer to the floor 10 than to the ceiling 12. The containers 8 stand on the intermediate floor 13.The intermediate floor 13 is provided with passage openings 14, above which the containers 8 containing the carbon-containing sorbent are arranged. The containers 8 have a perforated floor, in particular a perforated plate, on their underside with openings through which the flue gases can enter. This allows the flue gases to flow from a space 15 below the intermediate floor 13 through the passage openings 14 into the containers 8. With the aid of the carbon-containing sorbent, the proportion of volatile components, in particular mercury, in the flue gases is reduced. After passing through the containers 8, the flue gases are withdrawn from the space 17 above the intermediate floor 13 via the discharge line 7B, which may have at least one pipe 16.

[0040] Thus, a process for separating a volatile component, in particular mercury, from flue gases, in particular from cement clinker production, can be carried out with the following steps: Feeding the flue gases into a mobile container 7, in which several containers 8 are arranged, each filled with a fixed bed of (carbon-containing) sorbent; separating the volatile component of the flue gases on the (carbon-containing) sorbent in the containers 8; and discharging the flue gases from the mobile container 7.

[0041] In Fig. 4 An alternative system diagram is shown, whereby only the differences are pointed out below. Fig. 1 bis 3 should be addressed.

[0042] In the execution of the Fig. 4 The flue gases are also initially fed to a dust filter 4, where dust essentially free of mercury is separated and then, for example, returned to the preheating stage (see arrow 18). The flue gases are then fed, for example at essentially 350°C, to an SCR module 19, which is designed for the selective catalytic reduction of nitrogen compounds ("denitrification"). Upstream of the mobile container 7, the flue gases are fed to the heat exchanger 6, which, together with another heat exchanger 20 downstream of the mobile container 7, forms a device 21 for transferring heat from the flue gases upstream of the mobile container 7 to the flue gases downstream of the mobile container 7. With the help of the device 21, the appropriate temperature level, in particular 50 to 200°C, is maintained for the separation of the volatile component in the mobile container 7, and at the same time, the heat content of the flue gases is recovered.A heat exchange medium can be routed between heat exchanger 6 and the additional heat exchanger 20. This heat exchange medium absorbs the heat from the flue gases upstream of the mobile container at heat exchanger 6 and transfers the heat to the flue gases at the additional heat exchanger 20. As illustrated by arrow 20A, the heat absorbed by heat exchanger 6 can also be transferred to another location in the cement clinker production process. Finally, the flue gases are fed to the exhaust gas purification system 10 or returned to the process.

[0043] In the execution of the Fig. 4 In addition, a further mobile container 22 is provided with a further supply line 23 and a further discharge line 24 for the flue gases. The further mobile container 22 is identical to the mobile container 7. Accordingly, further containers are arranged inside the further mobile container 22, each filled with a carbon-containing sorbent. The mobile container 7 and the further mobile container 22 can be flowed through individually or one after the other. In a first switching position, the mobile container 7 and the further mobile container 22 are connected in series, with the discharge line 7B of the mobile container 7 being connected to the further supply line 23 of the further mobile container 22. In the first switching position, the entire flue gas can be passed first through the mobile container 7 and then through the further mobile container 22. For this purpose, the Fig. 4The visible connection between the supply line 7A of the mobile container 7 and the further supply line 23 of the further mobile container 22 must be blocked. In a second switching position, the mobile container 7 and the further mobile container 22 are connected in parallel. This allows the flue gases to be fed either to the supply line 7A of the mobile container 7 or to the further supply line 23 of the further mobile container 22 (or simultaneously to the supply line 7A and the further supply line 23). To replace the carbon-containing sorbent in the containers 8 of the mobile container 7, the supply line 7A and the discharge line 7B can be blocked so that the flue gases are completely conducted via the further mobile container 22. The containers 8, including the loaded sorbent, can then be replaced with containers 8 containing unloaded sorbent.

Claims

1. Installation, in particular a cement clinker installation (1), for separating a volatile component, in particular mercury, from flue gases, comprising: a mobile container (7) with an inlet line (7A) and an outlet line (7B) for the flue gases, the mobile container (7) being designed as a transportable swap body, characterized in that several vessels (8), each filled with a fixed bed (9) of a sorbent, in particular a carbon-containing and / or mineral sorbent, are arranged in the mobile container (7), wherein the mobile container (7) comprises a mount for attaching a lifting device.

2. Installation (1) according to claim 1, characterized by a further mobile container (22) with a further inlet line (23) and a further outlet line (24) for flue gases, in which further vessels, each filled with a sorbent, are arranged.

3. Installation (1) according to claim 2, characterized in that the mobile container (7) and the further mobile container (22) are connected in series in a first switching position, the outlet line (7B) of the mobile container (7) being connected to the further inlet line (23) of the further mobile container (22).

4. Installation (1) according to claim 2 or 3, characterized in that the mobile container (7) and the further mobile container (22) are connected in parallel in a second switching position, the flue gases being feedable selectively to the inlet line (7A) of the mobile container (7) or to the further inlet line of the further mobile container (22).

5. Installation (1) according to one of claims 1 to 4, characterized in that a drum is provided in each case as vessel (8), in particular with a capacity of more than 100 litres, preferably of more than 150 litres and preferably of less than 300 litres, particularly preferably of less than 250 litres, for example substantially 200 litres.

6. Installation (1) according to one of claims 1 to 5, characterized in that the mobile container (22) comprises an intermediate floor (13) with passage openings (14), above which the vessels (8) with the sorbent are arranged.

7. Installation (1) according to one of claims 1 to 6, characterized in that a dust filter (4), in particular a hot-gas filter, is arranged upstream of the mobile container (7).

8. Installation (1) according to claim 7, characterized in that a cooler, in particular an evaporative cooler or a heat exchanger, is arranged between the dust filter (4) and the mobile container (7).

9. Installation (1) according to one of claims 1 to 8, characterized in that a device (21) for shifting heat of the flue gases upstream of the mobile container (7) onto the flue gases downstream of the mobile container (7) is provided.

10. Installation (1) according to one of claims 7 to 9, characterized in that an SCR module is arranged between the dust filter (4) and the mobile container (22).

11. Method for separating a volatile component, in particular mercury, from flue gases, in particular from cement-clinker production, having the steps of: feeding the flue gases into a mobile container (7) in which several vessels (8) filled with a fixed bed (9) of a sorbent, in particular a carbon-containing and / or mineral sorbent, are arranged, the mobile container (7) being designed as a transportable swap body; separating the volatile component of the flue gases on the sorbent in the vessels (8); and discharging the flue gases from the mobile container (7).

12. Method according to claim 11, characterized in that the flue gases, after flowing through the mobile container (7), are passed through a further mobile container (22) in which further vessels, each filled with a sorbent, are arranged.

13. Method according to claim 12, characterized in that, for replacing the loaded sorbent in the vessels (8) of the mobile container (7), the flue gases are conducted exclusively through the further vessels (8) of the further mobile container (22).

14. Method according to claim 12 or 13, characterized by dedusting the flue gases, in particular with a hot-gas filter, before feeding the flue gases into the mobile container (7).