Process device for the thermal treatment of process material

Abstract

The invention relates to a process device for the thermal treatment of process material, comprising a housing in which a process chamber is arranged, wherein the process material can be subjected to thermal treatment in the process chamber, and a conveying device with which the process material can be conveyed through the process chamber. According to the invention, the housing is largely gas-tight from the external environment of the process device, the process chamber is largely gas-tight from the interior of the process device enclosed by the housing, the process chamber has a plurality of process zones, each process zone has a fixed bearing, wherein the process zone is fixed relative to the housing by means of the fixed bearing, and each process zone is gas-tightly connected to the adjacent process zone(s) via compensators.

Description

BACKGROUND OF THE INVENTION 1. Field of the invention

[0001] The invention relates to a process device for the thermal treatment of process material with a housing in which a process chamber is arranged, wherein the process material can be subjected to thermal treatment in the process chamber, and a conveying device with which the process material can be conveyed through the process chamber. 2. Description of the state of the art

[0002] Such process equipment is used on an industrial scale, for example in industrial furnaces for the production of anode materials. These anode materials require porous carbon material with a very high surface area and pore sizes ranging from, for example, < 2 nm to 50 nm. In the production of the anode materials, the starting material is subjected to a series of process steps, from the pyrolysis and activation of organic starting materials, such as synthetic organic resin compounds, to the production of high-purity carbon powder, to the deposition or infiltration of additional components, such as silicon, into the resulting carbon framework.

[0003] For this purpose, the starting material, which may be in powder form, for example, is heated in suitable containers in a continuous process to temperatures of up to 600°C under a protective gas atmosphere and subsequently exposed to a suitable process gas in the process device. Some of the process gases used are toxic and / or flammable. Heating to high temperatures leads to a linear expansion of the materials involved, which must be taken into account when designing the process device. SUMMARY OF THE INVENTION

[0004] It is an object of the invention to provide a process device of the type mentioned above which has a high safety standard with reasonable design effort.

[0005] This task is solved by a process device according to the independent claim.

[0006] The process device according to the invention for the thermal treatment of process material comprises a housing in which a process chamber is arranged, wherein the process material can be subjected to thermal treatment in the process chamber. Furthermore, the process device comprises a conveying device with which the process material can be conveyed through the process chamber.

[0007] According to the invention, the housing is largely gas-tight from the external environment of the process device, and the process chamber is largely gas-tight from the interior of the process device enclosed by the housing. The process chamber has a plurality of process zones. Each process zone has a fixed bearing and is fixed to the housing by means of the fixed bearing.

[0008] Each process zone is connected to the adjacent process zone(s) via compensators in a gas-tight manner.

[0009] The resulting process space is gas-tight, as the compensators ensure a gas-tight connection between the process zones. Simultaneously, the fixed support of each process zone allows it to expand relative to the support. This relative expansion is then absorbed by the compensators and thus balanced relative to the adjacent process zone(s).

[0010] This results in a process device with dual gas-tight protection, as independent gas tightness is provided separately for the housing and the process chamber. This redundancy ensures a high level of operational reliability. Should a leak occur in the process chamber, for example, the housing provides a second sealing layer, guaranteeing the tightness of the entire process device for a specific period. During this time, the process device can be shut down in a controlled manner; for instance, the supply of hazardous gases can be shut off and the temperatures can be lowered in a controlled manner.

[0011] At the same time, dividing the process chamber into process zones and arranging compensators and fixed bearings minimizes the overall length change of the process device. This also contributes to the operational reliability of the system. Furthermore, this approach sometimes makes it possible to implement external penetrations into the process chamber, for example for process gas supply, exhaust gas removal, etc., which remain functional at the various temperatures during normal operation and, for example, during maintenance work in a cooled state.

[0012] Furthermore, the minimal change in length due to temperature fluctuations allows for the easy integration of the process device into larger units such as an industrial furnace.

[0013] In an advantageous embodiment, each process zone can have several supports facing the housing, with the supports being designed as floating bearings. The mounting of the process zones within the housing with fixed and floating bearings enables controlled accommodation of the thermal expansion of the process chamber within the respective process zone, so that the process device as a whole exhibits very little change in length due to temperature changes.

[0014] Advantageously, the fixed bearings are arranged centrally within the process zone. This has the advantage that the total change in length of a process zone is distributed evenly across the two ends of the respective process zone furthest from the fixed bearing.

[0015] In one embodiment, the process chamber is arranged inside a muffle. The muffle can, for example, be designed as a gas-tight structure.

[0016] Advantageously, the space between the muffle and the housing is at least partially designed as a heating chamber for warming the muffle. The muffle can, for example, be made of stainless steel. This allows for uniform heating of the muffle and uniform heat transfer to the process material.

[0017] In this context, it can be advantageous for the heating chamber to have heating elements for warming a medium flowing within it, or flow elements for guiding a medium flowing within it. This allows the temperature, flow velocity, and / or direction of the flowing medium—which serves to heat the muffle and the process materials contained within it—to be controlled, thus achieving uniform and efficient heating of the muffle.

[0018] Further development may include the provision of gas-tight feedthroughs from outside the process device into the process chamber. Preferably, these feedthroughs have two sealing levels. It is particularly preferred that the feedthroughs are located in the area of ​​the fixed bearings. In this way, the feedthroughs are minimally affected by thermal expansion within the process zone.

[0019] The compensators are preferably designed for temperatures of at least 600°C.

[0020] The described process device is suitable for the production of novel anode materials, such as high-purity graphite powder with a SiC coating. The anode material can be produced continuously in the furnace with a consistently homogeneous SiC coating. The anode material is contained, for example, as a bulk material in shallow trays, a large number of which are arranged in a rack. The racks and the trays of anode powder within them pass through a multi-chamber furnace designed as a pass-through furnace. Each rack must be heated to temperatures between 400 and 500°C with homogeneous temperature uniformity under a protective gas atmosphere in a gas-tight heating chamber, such as a steel enclosure.After heating, the racks are placed in a separate, gas-tight furnace chamber, such as a stainless steel muffle, where they are exposed to a process gas, allowing the silicon from the gas phase to deposit onto the anode powder. A homogeneous process gas flow within the chamber is necessary for homogeneous silicon deposition. The powder is then passivated in another separate furnace segment and subsequently cooled. Each segment is further subdivided into several heating zones. The total length of the system is approximately 70 meters.

[0021] The described muffle, for example, is made of stainless steel and is divided into zones. Each zone has a fixed point in its center. At the end of each zone are stainless steel expansion joints that accommodate the muffle's expansion at maximum temperatures of 600°C. Because each zone can accommodate its own change in length, there is no or only a very small change in the overall length of the muffle. This concept offers many functional advantages. It results in a double sealing system between the muffle and the housing, as the gas-tight muffle with its internal process chamber and the gas-tight housing, which contains the muffle's heating chamber, ensure a gas tightness to prevent the escape of flammable process gases.

[0022] Since each process zone has a fixed point in the middle and a compensator is installed at the beginning and end of each zone, each individual zone can accommodate thermal expansion independently. As a result, there is no change in the overall length of the muffle. Consequently, the total muffle length in the cold state is essentially the same as in the hot state.

[0023] Due to the low muffle expansion, gas-tight penetrations such as process gas supply, exhaust gas, fan penetration, etc. can be achieved through two sealing levels.

[0024] Because there is no or only very minimal change in segment length, complex layouts within a furnace can be achieved. For example, several segments can be arranged one behind the other, which would otherwise have to be staggered for conveying and process engineering reasons. This makes furnace lengths of several dozen meters possible.

[0025] The muffle forms a gas-tight process chamber. Flammable gases are used as the process gas. Should the muffle develop a leak during operation due to unforeseen circumstances, the gas-tight outer casing in which the muffle is installed provides a secondary seal. If leaks are detected in the muffle, the outer casing temporarily seals the furnace, allowing the system to be shut down in a controlled manner without any flammable gases escaping into the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Exemplary embodiments of the invention are explained in more detail below with reference to the drawings. These show: Fig. 1 a perspective view of an embodiment of a process device; Fig. 2 a perspective view of the muffles in Fig. 1 process device shown Fig. 3 a top view of the embodiment of the Fig. 1: Fig. 4 a longitudinal sectional plan view of the embodiment of the Fig. 1; Fig. 5 a side view of the embodiment of the Fig. 1; Fig. 6 a bottom view of the embodiment of the Fig. 1-4 as well Fig. 7 a cross-sectional view of the embodiment of the Fig. 1-5. DESCRIPTION OF PREFERRED EXAMPLES

[0027] Fig.Figures 1-6 illustrate an embodiment of a process device 10 for the thermal treatment of process material. The process device 10 can, for example, be part of an industrial furnace line, which may be designed, for instance, for the production of anode material for batteries or accumulators. The embodiment of the process device 10 can be configured in such a furnace line for the process of integrating silicon into graphite powder. In this process, the material being processed, for example, powdered material guided in shallow trays, is heated in a process chamber to temperatures in the range of, for example, 400°C to 600°C and, in a subsequent step, is exposed to a process gas.

[0028] There are significant temperature differences between the environment and the interior of the process chamber. At the same time, due to the required uniformity of temperature distribution within the process chamber and potentially due to the reactivity of the process gases involved, the highest possible level of safety is required. The design described below meets these requirements.

[0029] The process device 10 comprises a housing 12. The housing 12 essentially has the basic shape of an elongated cuboid, the longitudinal axis of which extends essentially along a conveying direction A. The housing 12 can, for example, be a gas-tight welded steel structure made of standard steel. A process chamber 14 is arranged within the housing 12 of the process device 10, also extending along the conveying direction A. The process chamber 14 can, for example, be located in a muffle 16. The muffle 16 can, for example, be a gas-tight welded steel structure, for example, made of stainless steel. The muffle 16 has a wall 17, for example, made of stainless steel, enclosing the process chamber 14. Inside the housing 12, the muffle 16 is supported by housing legs 19 and has reinforcing ribs 22 along its circumferential direction – relative to the longitudinal axis of the housing.

[0030] The housing 12 is lined on its inside with insulation 18, which provides thermal shielding of the process chamber from the surrounding environment. For the insulation, materials such as mineral fiber-based insulation, ceramic fiber mats, or similar materials designed for the temperatures prevailing inside can be used. The individual insulation materials can also be arranged in layers. A heating chamber 20 is located between the inside of the insulation 18 and the outside of the muffle 16. This chamber essentially surrounds the muffle 16 and is permeable to a heating gas.

[0031] The housing 12 and the muffle 16 are divided into sections along the longitudinal axis. Each section defines a heating zone 24. For example, the process device 10 can have eleven heating zones 24. Each heating zone 24 can, in principle, be controlled independently of the adjacent heating zone(s) 24 with respect to temperature and accordingly divides the process chamber 14 internally into associated process zones. For example, the process device 10 can have several heating zones that are controlled at essentially the same temperature. Alternatively, a first heating zone can be designed as a buffer zone that is not heated or only slightly heated in order to reduce the influence of the ambient temperature. The process chamber 14 and the individual process zones are heated by means of two independent heat sources.

[0032] The muffle 16 is heated externally by a heating element 30 located in the heating chamber 20 – that is, the space between the insulation 18 and the muffle 16 itself – which can, for example, be designed as a metallic heating element 30 and through which the aforementioned heating gas flows. A fan 32 is also provided for this purpose, which, for example, together with the heating element 30, can be arranged as a heating module 34 on the top of the housing 12 and can set the heating gas in motion.

[0033] Heating elements 26 are arranged within the muffle 16. These heating elements 26 can, for example, be designed as metallic tubular heating elements 28 and can be arranged primarily vertically within the process zone of the process chamber 14. For example, such tubular heating elements can be arranged on the left and right sides of each heating zone 24 when viewed in the direction of flow A. A circulating fan 36 is attached to the muffle 16 for each heating zone 24. This fan serves to distribute the heated process gas evenly within the process chamber 14. The circulating fan 36 can, for example, be attached to the underside of the muffle 16, be driven directly by a three-phase motor, and distribute the hot process gas evenly within the process chamber 14 inside the muffle 16.

[0034] For conveying the process material, a slide 37 is provided in the process chamber 14 – i.e., inside the muffle 16. The slide 37 extends along the conveying direction A through the process device 10 and enables the process material – for example, trays held in a carrier such as a transport rack 39 – to be transported by means of a pusher in a through-passage through the process chamber 14. For example, the slide 37 can be a graphite slide 37.

[0035] Due to the large temperature differences between the process chamber 14 inside and the ambient temperature outside the housing 12, the process device 10 generally undergoes a large overall thermal expansion when heated to operating temperature or, for example, when the process temperature changes. To compensate for these expansions, several measures are implemented in the present embodiment, which work synergistically: As already mentioned, the housing 12 is divided into heating zones 24 along the conveying direction A. This division is reflected in the division of the muffle 16 into individual muffle modules 38. The muffle modules 38 are connected to each other in a gas-tight manner. For this purpose, expansion compensators 40 are installed between the individual modules 38 at the connection points. The expansion compensators 40 accommodate the thermal expansion of the connected modules 38 and thus compensate for the expansion of the module 38 in the direction of conveying direction A. The expansion compensators 40 are provided around the entire perimeter of the respective muffle modules 38, i.e., in a plane perpendicular to the conveying direction A or the longitudinal axis, at the connection point of the respective muffle modules 38.In a preferred embodiment, the expansion compensators 40 can be metallic, resulting in an overall gas-tight stainless steel construction for the muffle 1 composed of the individual modules 38.

[0036] In addition to the described expansion compensators 40, it is further provided that each muffle module 38, besides supports 41 designed as floating bearings, has a fixed point in the form of a fixed bearing 42 in the center of the module 38 relative to the surrounding housing 12. For example, the fixed point can be realized by the suitable mounting of the circulating fan 36. In the embodiment shown, the circulating fan 36 is installed in the process chamber 14 such that it can distribute the hot process gas evenly in the muffle module 38. The circulating fan 36 typically has a circulating fan housing 44. For example, the circulating fan 36 can be arranged in the lower region of the muffle module 38 such that part of the circulating fan housing 44 extends from the process chamber 14 through the wall 17 of the muffle module 38 into the surrounding housing 14.If the part of the circulating fan housing 44 extending into the housing 14 is fixed to the housing 14 of the process device 10, the circulating fan 36 forms the described fixed point 42. The circulating fan 36 could also be mounted on the top or in the left or right side walls.

[0037] Advantageously, in the present embodiment, the fixed point 42 is arranged in the middle of the muffle module 38 with respect to the conveying direction A, since the total expansion of the module 38 is thus divided between the two expansion compensators 40, which connect each module 38 with a neighboring module 38.

[0038] In addition to the circulating fan 36, the muffle 16 has further penetrations from the outside into the process chamber 14 and from the inside out of the process chamber. For example, supply and return lines 45 are provided for the tubular heating elements 28, which carry a heating medium into and out of the process chamber for temperature control of the tubular heating elements 28 via penetrations in the wall 17 of the muffle 16. These are arranged on both sides of the muffle module 38 (left / right) in the conveying direction A, corresponding to the tubular heating elements 28.

[0039] Further feedthroughs 46 and 48 are provided for the introduction and exhaust of process gases. A first feedthrough 46 serves for the introduction of process gases, and a second feedthrough 48 serves for exhaust gas extraction. The arrangement of the feedthroughs 46 and 48 (left / right / top / bottom, viewed in the direction of flow A) is generally determined by process-related considerations. The gas tightness of the feedthroughs 46 and 48 can be achieved, for example, by gas-tight compression fittings.

[0040] In the embodiment shown, the feedthroughs 45, 46, 48 are arranged as close as possible to the fixed point 42 with respect to their position along the conveying direction A, i.e., specifically further away from the outer edges of the muffle module 38 and closer to the center point or the fixed bearing 42 of the module 38.

[0041] In addition to the feedthroughs 45, 46, 48 for conveying media, feedthroughs for acquiring measured values ​​can also be provided inside the process device. In the illustrated embodiment, for example, a thermocouple 49 is installed in the process chamber 14 and a thermocouple 54 in the heating chamber 20. The thermocouples can be provided for each heating zone 24 or each muffle module 38, respectively.

[0042] For guiding the gases in the process chamber 14, vertically oriented perforated plates 50 are arranged in front of the process material being conveyed, such that the process gas directed towards the material can be distributed homogeneously in the flow direction and at a consistent flow velocity. Similarly, perforated plates 51 can be attached to or inside the conveyed transport frame 39 to homogenize the flow.

[0043] In the operation, for example, the powdered process material contained in trays, such as powdered anode material, is conveyed on a goods carrier such as transport rack 39 by means of a push through the slide 19 and the muffle 16.

[0044] The circulation fans 36 of each heating zone 24 are operated such that the process gas in the process chamber 14 is drawn in below the slide rail 37 and thus also below the transport racks 39 and forced towards the side walls 17. The process gas then flows along the tubular heating elements 28 located there and is heated. Upon reaching the upper ceiling 52 of the muffle 16, the airflow is redirected and, on its way back to the circulation fan 36, encounters the perforated plates 50 in front of the transport rack 39 and similar perforated plates 51 inside the transport rack, so that trays 54 arranged in the transport rack 39, containing the process material, are uniformly surrounded by the airflow.

[0045] In this way, a uniform distribution of process gas and heat is achieved within process room 14.

Claims

[1] Process device (10) for the thermal treatment of process material, with a housing (12) in which a process chamber (14) is arranged, wherein the process material can be subjected to thermal treatment in the process chamber (14), and a conveying device (37) with which the process material can be conveyed through the process space, characterized by , that the housing (12) is largely gas-tight in relation to the external environment of the process device (10), the process chamber (14) is largely gas-tight in relation to the interior of the process device (10) enclosed by the housing (12), the process space has a plurality of process zones (24), Each process zone (24) has a fixed bearing (42), wherein the process zone (24) is fixed relative to the housing (12) by means of the fixed bearing (42) and Each process zone (24) is connected gas-tight to the adjacent process zone(s) (24) via compensators (40). [2] Process apparatus according to claim 1, wherein each process zone (24) has several supports (41) towards the housing, wherein the supports (41) are designed as floating bearings. [3] Process device according to one of the preceding claims, wherein the fixed bearing (42) is arranged centrally to the process zone (24). [4] Process apparatus according to one of the preceding claims, wherein the process chamber (14) is located inside a muffle (16). [5] Process apparatus according to claim 4, wherein the space between muffle (16) and housing (12) is at least partially designed as a heating chamber (20) for heating the muffle (16). [6] Process apparatus according to claim 5, wherein the heating chamber (20) has heating elements (28) for heating a medium flowing therein. [7] Process apparatus according to claim 5 or 6, wherein the heating chamber (20) has flow elements (50) for guiding a medium flowing therein. [8] Process device according to one of the preceding claims, wherein gas-tight feedthroughs (45, 46, 48) are provided from outside the process device (10) into the process chamber (14). [9] Process apparatus according to claim 8, wherein the feedthroughs (45, 46, 48) have two sealing levels. [10] Process device according to one of the preceding claims, wherein the feedthroughs (45, 46, 48) are arranged in the area of ​​the fixed bearings (42). [11] Process apparatus according to one of the preceding claims, wherein the compensators (40) are designed for temperatures of at least 600°C.

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