Burner and burner stack

Abstract

Burning capsule (1a; b) for receiving a burning material, preferably a pourable, preferably powdery or granular, burning material, in particular a powder for producing an electrode material, preferably a cathode material, for batteries, preferably for lithium-ion batteries, during the burning process, in the form of an upwardly open container (2), wherein the burning capsule (1a; b) has a bottom wall (3) and several, preferably four, side walls (4) adjoining one another in pairs and each adjoining the bottom wall (3), wherein the bottom wall (3) merges into one of the side walls (4) via a respective transition edge (10), characterized in that the transition edges (10) each have a transition edge inner surface (10a) and a transition edge outer surface (10b), wherein the transition edge inner surfaces (10a) each have a concave curvature with an inner radius of curvature (R i) and the transition edge outer surfaces (10b) each have a convex curvature with an outer radius of curvature (R a ) and the inner and outer radius of curvature (R i ; R a ) are dimensioned such that the transition edges (10) have a constant wall thickness.

Description

[0001] The present invention relates to a burning capsule for receiving a burning material during the burning process and a burning capsule stack comprising at least two burning capsules stacked one above the other.

[0002] Firing capsules are usually box-shaped kiln furniture. Firing capsules serve to hold a material to be fired, which is fired in a high-temperature process, particularly for ceramic sintering. In particular, the material to be fired is a pourable material, preferably in powder or granular form. For example, this is powder for the production of an electrode material, preferably a cathode material, for batteries, preferably lithium-ion batteries. However, the material to be fired can also be, for example, shaped bodies to be ceramically fired.

[0003] During the firing process, the material to be fired is preferably transported through the respective kiln in the firing capsule. In the case of electrode material, this is preferably a roller kiln. Furthermore, at least two firing capsules are usually stacked on top of each other for firing.

[0004] The burning capsules are made of fired refractory material, for example mullite, cordierite, corundum, spinel or SiC.

[0005] The burning capsules are usually manufactured by pressing or casting and subsequent firing.

[0006] The term "refractory" in the context of the invention should not be limited to the definition according to ISO 836 or DIN 51060, which define a cone softening point of > 1500° C. Refractory products or refractory material within the meaning of the invention have a compression softening point T 0,5 according to DIN EN ISO 1893: 2008-09 by T 0,5 ≥ 600 °C, preferably T 0,5≥ 800 °C. Accordingly, refractory or refractory granular materials or grains within the meaning of the invention are those materials or grains which are suitable for a refractory product or material with the above-mentioned pressure softening point T 0,5 are suitable.

[0007] Furthermore, a distinction is known between non-basic (Practical Handbook, 4.1) and basic refractory products (Practical Handbook, 4.2). According to DIN EN ISO 10081:2005-05, a distinction is made between non-basic and basic refractory products based primarily on their chemical reactivity. The non-basic product group includes materials of the SiO2-Al2O3 series and other materials that cannot be further classified according to their chemical reactivity, such as SiC and carbon products. A key characteristic of most basic products is that the sum of the oxides MgO and CaO predominates. Chromite, picrochromite, spinel, and forsterite bricks are also considered basic products, even though they are virtually neutral.

[0008] Coarse ware products are also known to be products made from grains with grain sizes up to 6 mm, and in special cases even up to 25 mm (see "Gerald Routschka / Hartmut Wuthnow, Practical Handbook "Refractory Materials", 6th edition, Vulkan-Verlag (hereinafter referred to simply as "Practical Handbook"), Chapter 2). Coarse ware is distinguished from fine ware by the grain size of its structural components. If the structural components are at least partially larger than 1 mm, it is a coarse ware product; if the structural components are exclusively ≤ 1 mm, it is a fine ware product.

[0009] The burning capsules are usually open-topped, preferably square, containers with a bottom wall and four side walls. The side walls each merge into the bottom wall via a transition edge. To ensure thorough cleaning of the burning capsules with brushes after the burning process, the transition edge is often rounded on the inside.

[0010] WO 2024 / 126477 A1 discloses a generic combustion capsule which is open at the top and has a bottom wall and four side walls, the bottom wall and the side walls having a maximum wall thickness of 10 mm.

[0011] A box-shaped, upwardly open combustion capsule is also known from EP 3 458 428 B1 and from the article “Mobility Revolution: Refractory Saggars For Calcination Of Ternary Cathode Materials”, 66 th International Colloquium on Refractories 2024, Anna-Lena Schäfer.

[0012] Within the scope of the invention, it was found that during the firing process, due, among other things, to the temperature change, mechanical and thermal stresses often occur, particularly in the area of ​​the transition edge, which can even lead to the breakage of the firing capsules in the area of ​​the transition edge.

[0013] The object of the present invention is to provide a burning capsule with improved service life.

[0014] In addition, the object of the invention is to provide a stack of burning capsules comprising at least two burning capsules stacked one above the other.

[0015] These objects are achieved by a scorch capsule having the features of claim 1 and a scorch capsule stack according to claim 22. Advantageous developments of the invention are characterized in the respective subsequent subclaims.

[0016] The invention is explained in more detail below using a drawing as an example. The drawings show: Fig. 1: A perspective view of a lower or middle burning capsule according to the invention, obliquely from above Fig. 2: A perspective view of the scorch capsule obliquely from below Fig. 3: A central cross-section through the scorch capsule Fig. 4: A side view of the scorch capsule Fig. 5: An enlarged perspective view of a portion of the scorching capsule according to Fig. 1 Fig. 6: A perspective view of an upper combustion capsule according to the invention obliquely from above Fig. 7: A perspective view of a combustion capsule stack according to the invention, obliquely from above Fig. 8: An enlarged perspective view of a portion of the scorch capsule stack according to Fig. 7 Fig. 9: An enlarged view of a cross-section of a portion of the scorch capsule stack according to Fig. 7 Fig. 10a-d: The Von Mises stress, equivalent strain, deflection (displacement) and the safety factor determined by FEM for a standard geometry without curved bottom wall and with tapered transition edge outer surface Fig. 11a-d: The Von Mises stress, equivalent strain, deflection (displacement) and the safety factor determined by FEM for a combustion capsule according to the invention Fig. 12: The temperature curve used for the FEM

[0017] The burning capsule 1a;b according to the invention ( Fig. 1-8) is designed as a container 2 open at the top with a bottom wall 3 and four side walls 4 which are arranged in pairs adjacent to one another and each adjacent to the bottom wall 3.

[0018] Preferably, the combustion capsule 1a; b is box-shaped, preferably square. The bottom wall 3 thus has a rectangular, preferably square, outline.

[0019] The side walls 4 each have an inner side wall surface 4a and an outer side wall surface 4b. The inner side wall surface 4a and the outer side wall surface 4b are preferably each flat. Furthermore, the inner side wall surface 4a and the outer side wall surface 4b are preferably not parallel to one another. In particular, the outer side wall surface 4b is vertical or extends parallel to a, in particular vertical, vertical axis 12 of the combustion capsule 1a;b. And the inner side wall surface 4a is slightly inclined to the vertical axis 12, so that the side wall 4 tapers from bottom to top. This serves to improve demoldability.

[0020] The side walls 4 therefore preferably have a decreasing wall thickness as viewed upwards from the bottom wall 3. The wall thickness of the side walls 4 is preferably 8 to 15 mm, more preferably 10 to 12 mm.

[0021] The wall thickness of the side walls 4 can also be constant in the vertical direction 12. Furthermore, the side wall outer surface 4b can also be inclined to the vertical axis 12.

[0022] Each pair of side walls 4 also merges into one another at a side edge 5. Furthermore, the side walls 4 each have a free side wall upper edge 6. The side wall upper edges 6 of the individual side walls 4 also merge into one another in pairs and form a continuous, circumferential container upper edge 7. Preferably, the container upper edge 7 merges into the side wall inner surfaces 4a via a circumferential chamfer 20. The chamfer 20 reduces the risk of breakage at the transition between the container upper edge 7 and the side wall inner surfaces 4a when the capsules 1a;b are placed one on top of the other.

[0023] Preferably, at least two firing capsules 1a;b filled with firing material are stacked on top of each other. They form a firing capsule stack 18 ( Fig. 7 and Fig. 8).

[0024] For a lower or middle burning capsule 1a ( Fig. 1-5, 7-8), the side wall upper edges 6 each have, starting from a side wall transition edge 5, an outer, horizontal, preferably flat, upper edge bearing section 8 and, between the two outer upper edge bearing sections 8, a known recess 9. The recesses 9 serve to allow the scorching capsules 1a;b to be automatically gripped and placed on top of one another and removed from one another. Furthermore, the recesses 9 serve for product ventilation.

[0025] With an upper burning capsule 1b ( Fig. 6-8), the side wall upper edges 6 are preferably designed to be horizontal throughout without a recess. This allows for a larger amount of fuel to be accommodated. However, the upper firing capsule 1b can also be designed analogously to the lower firing capsule 1a.

[0026] The bottom wall 3 has a bottom wall inner surface 3a and a bottom wall outer surface 3b.

[0027] The bottom wall 3 transitions into one of the side walls 4 via a transition edge or edge 10. The transition edges 10 each also have an inner transition edge surface 10a and an outer transition edge surface 10b.

[0028] In addition, two transition edges 10 and one of the four side edges 5 merge into one another in a corner edge 11.

[0029] Within the scope of the invention, it has now been found that the thermal and mechanical stresses in the region of the transition edges 10 can be significantly reduced if the transition edges 10 have a substantially constant wall thickness ( Fig. 3) and whose wall thickness corresponds to the wall thickness of the bottom wall 3 and the side walls 4.

[0030] This is achieved by rounding the transition edges 10 not only on the inside but also on the outside. The transition edge inner surfaces 10a thus have a concave curvature with an inner radius of curvature R i and the transition edge outer surfaces 10b have a convex curvature with an outer radius of curvature R a The inner and outer radii of curvature R i ; R a are dimensioned so that the transition edges 10 have a constant wall thickness. Preferably, the inner radius of curvature R i 8 to 20 mm, preferably 8 to 10 mm and the outer radius of curvature R a is preferably 10 to 30 mm, preferably 18 to 22 mm.

[0031] The wall thickness of the side walls 4, the bottom wall 3, and the transition edges 10 is therefore essentially the same in the area where they adjoin each other. "Essentially the same" means that deviations within the range of normal, manufacturing-related tolerances are possible.

[0032] Since the transition edge outer surfaces 10b are rounded, mounting the transition edge outer surfaces 10b on the upper edge bearing sections 8 is no longer readily possible. Consequently, the scorching capsules 1a;b according to the invention have a plurality of bearing feet 13 for mounting an upper or middle scorching capsule 1a;b on the upper edge bearing sections 8 of the scorching capsule 1a arranged below.

[0033] The bearing feet 16 are each integrally formed on the outside of one of the transition edges 10. Thus, they each adjoin the outer surface 10b of the transition edge and protrude from it. Furthermore, the bearing feet 16 are formed integrally with the transition edge 10 or with the rest of the container 2.

[0034] The bearing feet 13 also each have a bearing surface 14, two foot side surfaces 15, and a foot back surface 16. The foot back surface 16 adjoins the side wall outer surface 4b of the respective side wall 4 and preferably forms its extension. It is therefore coplanar with it.

[0035] The bearing surface 14 is preferably perpendicular to the height axis 12. In addition, the bearing surface 14 is preferably offset slightly upwards in relation to the lowest point or the lowest extension of the bottom wall 3 and to the lowest point or the lowest extension of the transition edges 10, preferably the transition edge outer surfaces 10b ( Fig. 9). Preferably, the offset V is 2 to 4 mm.

[0036] Furthermore, the bearing feet 13 are preferably arranged adjacent to one of the corner edges 11. Thus, a bearing foot 13 is arranged on each side of a corner edge 11. Or, for each transition edge 10, two bearing feet 13 are formed thereon.

[0037] As already explained, the bearing feet 13 serve to support an upper or middle combustion capsule 1a;b on the upper edge bearing sections 8 of the combustion capsule 1a arranged below. For this purpose, the bearing surfaces 14 rest on the upper edge bearing sections 8 ( Fig. 7 and Fig. 8). Since the bearing surface 14 of the bearing feet 13 is preferably offset slightly upwards relative to the lowest point of the bottom wall 3 and the transition edges 10, the upper combustion capsule 1b is centered, receives a firm fit, and is protected against displacement or slipping. This is because the bottom wall 3 and, in particular, the transition edges 10 of the upper or middle combustion capsule 1a;b are thus arranged somewhat lower than the upper edge bearing sections 8 of the combustion capsule 1a arranged below and are received between them ( Fig. 9).

[0038] Surprisingly, it was discovered within the scope of the invention that the bearing feet are not knocked off during handling and transport of the sprues 1a; b, especially on the transport rollers of a roller kiln, even though they protrude from the transition edges 10. This is also achieved, among other things, by displacing the bearing surface 14 of the bearing feet 13 upwards relative to the lowest point of the base wall 3. This ensures that the sprues 1a; b are transported on the transition edges 10 and, if applicable, the base wall 3, and not on the bearing feet 13.

[0039] Preferably, the bottom wall 3 is also curved upwards. The bottom wall inner surface 3a is thus convexly curved, and the bottom wall outer surface 3b is concavely curved. This serves to prevent downward deflection of the bottom wall 3 during the production of the sprue capsules 1a;b during ceramic firing and during use of the sprue capsules 1a;b. This increases the service life of the sprue capsules 1a;b. This is because the deflection and falling out of the bottom wall 3 is one of the most common causes of failure. The curvature is designed to such a small extent that the sprue capsule 1a;b can still be moved along the bottom wall 3 as usual.

[0040] Preferably, the base wall 3 is also pyramid-shaped and has four triangular base wall sections 17 adjacent to one another in pairs. The base wall sections 17 each merge into one another in pairs via a base wall edge 19. Furthermore, the base wall sections 17 are preferably each flat. The pyramid-shaped design ensures good rigidity and a uniform wall thickness.

[0041] The firing capsules 1a;b are also made of ceramically fired, preferably fine-ceramic, refractory material. Preferably, the firing capsules 1a;b are made of cordierite, mullite, corundum, SiC, or spinel.

[0042] The T 0,5 of the material is preferably 1300 to 1700 °C, according to DIN EN ISO 1893:2008-09.

[0043] The thermal shock resistance of the material is preferably 50 to 100 cycles, according to DIN 51068:2008-11.

[0044] The production of the sintering capsules 1a;b is preferably carried out by producing a moldable mass, shaping the mass, and then ceramically firing the molded body. Shaping is preferably carried out by casting or pressing, preferably dry pressing. Pressing can also be carried out by uniaxial or isostatic pressing.

[0045] As already explained, the firing capsules 1a; b each serve to hold a firing material, which is fired, in particular ceramically sintered, in a high-temperature process. Firing preferably takes place at a temperature of 900 to 1250°C, more preferably 900 to 1000°C.

[0046] The material to be fired is preferably a pourable material, preferably in powder or granular form. It is preferably a powder for producing an electrode material, particularly preferably a cathode material, for batteries, preferably lithium-ion batteries. However, the material to be fired can also be, for example, shaped bodies to be fired ceramically.

[0047] During the firing process, the firing material is preferably transported through the respective firing kiln in the respective firing capsule 1a;b. Furthermore, at least two firing capsules 1a;b are preferably stacked one above the other to form the firing capsule stack 18.

[0048] The kiln is preferably a tunnel kiln, a hood kiln or a roller kiln.

[0049] Finally, it is pointed out that all of the features mentioned, particularly claimed, of the scorch capsule and the scorch capsule stack are particularly advantageous in themselves and in any combination and are the subject of the present invention.

[0050] In addition, the upper and lower limits specified for each individual range can all be combined with one another according to the invention.

[0051] It is also within the scope of the invention that the lower combustion capsules 1a do not have bearing feet 13. Examples of implementation:

[0052] FEM studies were conducted to investigate and demonstrate the stresses during the firing process and thus to prove the effect according to the invention. Cordierite was assumed as the material. In addition, both mechanical and thermal FEM studies were carried out. The highest load case was assumed, namely the load on the lower firing capsule in a stack of two firing capsules, since the total load is transferred from the upper firing capsule into the side walls of the lower firing capsule and the associated deformation was expected to cause the highest possible stress buildup. For the FEM studies, a filler corresponding to the cathode material was simulated as the filling. It was assumed that the firing capsules were filled to a height of 30 mm below the top edge of the container. Comparative calculations were carried out for various temperature ranges and the load case temperature of 1000°C was selected to determine the stresses (highest stresses).The temperature curve used for the FEM is shown in . Fig. 12 shown.

[0053] Fig. Figure 10 shows the determined von Mises stress, equivalent strain, deflection and safety factor for a standard geometry without curved bottom wall and with tapered transition edge outer surface. Fig. In comparison, Figure 11 shows the values ​​determined for the geometry according to the invention.

[0054] It can be seen that the von Mises stress in the scorch according to the invention is significantly lower, especially in the area of ​​the transition edge from the bottom wall to the side walls, than in the scorch with the standard geometry. Furthermore, in the scorch with the standard geometry, a concentration of strain occurs at the transition from the side walls to the bottom wall. In contrast to the geometry according to the invention, the safety factor is exceeded and is also much lower. The maximum deflection in the scorch according to the invention is also significantly lower. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] WO 2024 / 126477 A1

[0010] EP 3 458 428 B1

[0011] Cited non-patent literature

[0000] DIN EN ISO 1893: 2008-09 [0006, 0042] DIN EN ISO 10081:2005-05

[0007] Mobility Revolution: Refractory Saggars For Calcination Of Ternary Cathode Materials”, 66 th International Colloquium on Refractories 2024, Anna-Lena Schäfer

[0011] DIN 51068:2008-11

[0043]

Claims

[1] Burning capsule (1a;b) for receiving a burning material, preferably a pourable, preferably powdery or granular, burning material, in particular a powder for producing an electrode material, preferably a cathode material, for batteries, preferably for lithium-ion batteries, during the burning process, in the form of an upwardly open container (2), wherein the burning capsule (1a;b) has a bottom wall (3) and several, preferably four, side walls (4) adjoining one another in pairs and each adjoining the bottom wall (3), wherein the bottom wall (3) merges into one of the side walls (4) via a respective transition edge (10), characterized by that the transition edges (10) each have a transition edge inner surface (10a) and a transition edge outer surface (10b), wherein the transition edge inner surfaces (10a) each have a concave curvature with an inner radius of curvature (R i) and the transition edge outer surfaces (10b) each have a convex curvature with an outer radius of curvature (R a ) and the inner and outer radius of curvature (R i ; R a ) are dimensioned such that the transition edges (10) have a constant wall thickness. [2] Burning capsule (1a;b) according to claim 1, characterized by that the wall thickness of the side walls (4), the bottom wall (3) and the transition edges (10) is substantially the same in the area where they adjoin one another. [3] Burning capsule (1a; b) according to claim 1 or 2, characterized by that the combustion capsules (1a;b) have a plurality of bearing feet (13) each adjoining the outer surface (10b) of the transition edge of one of the transition edges (10) and projecting therefrom. [4] Burning capsule (1a;b) according to claim 3, characterized bythat the scorching capsule (1a; b) is stackable and the side walls (4) each have a side wall upper edge (6) and the bearing feet (13) are designed such that when the scorching capsule (1a; b) is arranged on a further scorching capsule (1a) they rest on the side wall upper edges (6) of the scorching capsule (1a) arranged underneath. [5] Burning capsule (1a; b) according to one of the preceding claims, characterized by that the inner radius of curvature R i 8 to 20 mm, preferably 8 to 10 mm, and / or the outer radius of curvature R a 10 to 30 mm, preferably 18 to 22 mm. [6] Burning capsule (1a;b) according to one of claims 3 to 5, characterized by that the bearing feet (16) are formed in one piece with the rest of the container (2). [7] Burning capsule (1a;b) according to one of claims 3 to 6, characterized by that the bearing feet (16) have a bearing surface (14) which is preferably perpendicular to the height axis (12). [8] Burning capsule (1a;b) according to claim 7, characterized by that the bearing surface (14) is offset upwards in relation to the deepest extension of the bottom wall (3) and / or to the deepest extension of the transition edges (10), preferably the transition edge outer surfaces 10b, wherein the offset V is preferably 2 to 4 mm. [9] Burning capsule (1a;b) according to one of claims 3 to 8, characterized by that the bearing feet (16) have two foot side surfaces (15) and a foot back surface (16), wherein preferably the foot back surface (16) adjoins the side wall outer surface (4b) of the respective side wall (4) and is preferably coplanar therewith. [10] Burning capsule (1a;b) according to one of the preceding claims, characterized by that the floor wall (3) has a rectangular, preferably square, floor plan. [11] Burning capsule (1a;b) according to one of the preceding claims, characterized bythat the side walls (4) each have a side wall inner surface (4a) and a side wall outer surface (4b), wherein the side wall outer surface (4b) preferably extends parallel to a, in particular vertical, height axis (12) of the combustion capsule (1a;b) and the side wall inner surface (4a) is slightly inclined to the height axis (12), so that the side wall (4) tapers from bottom to top. [12] Burning capsule (1a;b) according to one of the preceding claims, characterized by that the wall thickness of the side walls (4) is 8 to 15 mm, preferably 10 to 12 mm. [13] Burning capsule (1a) according to one of the preceding claims, characterized bythat the side walls (4) each merge into one another in pairs at a side edge (5) and side wall upper edges (6) of the side walls (4) each have, starting from a side wall transition edge (5), initially an outer, horizontal, preferably planar, upper edge bearing section (8) and a recess (9) between the two outer upper edge bearing sections (8). [14] Burning capsule (1a) according to one of the preceding claims, characterized by that the side walls (4) each merge into one another in pairs at a side edge (5) and that two transition edges (10) and one of the side edges (5) each merge into one another at a corner edge (11). [15] Burning capsule (1a) according to claim 14, characterized by that a bearing foot (13) is arranged on both sides adjacent to a corner edge (11). [16] Burning capsule (1a) according to one of the preceding claims, characterized by that the bottom wall (3) is curved upwards. [17] Burning capsule (1a) according to claim 16, characterized by that a bottom wall inner surface (3a) of the bottom wall (3) is convexly curved and a bottom wall outer surface (3b) of the bottom wall (3) is concavely curved. [18] Burning capsule (1a) according to claim 16 or 17, characterized by that the bottom wall (3) is pyramid-shaped and has four triangular bottom wall sections (17) which are adjacent to one another in pairs and which each merge into one another in pairs via a bottom wall edge (19), wherein the bottom wall sections (17) are preferably each flat. [19] Burning capsule (1a) according to one of the preceding claims, characterized by that the combustion capsule (1a;b) consists of ceramically fired, refractory, preferably fine ceramic, material. [20] Burning capsule (1a) according to claim 19, characterized by that the scorch capsule (1a; b) consists of cordierite, mullite, corundum, spinel or SiC. [21] Burning capsule (1a) according to one of claims 11 to 20, characterized by that a container upper edge (7) merges into the side wall inner surfaces (4a) via a circumferential chamfer (20). [22] Burner capsule stack (18) comprising at least two burner capsules (1a;b) arranged one above the other, characterized by that the burning capsules (1a;b) are designed according to one of the preceding claims. [23] Combustion capsule stack (18) according to claim 22, characterized by that the bearing feet (13) of a combustion capsule (1a;b) rest with their bearing surfaces (14) on the side wall upper edges (6), preferably on the upper edge bearing sections (8), of the combustion capsule (1a) arranged underneath.

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