Dry pelletiser for dry granulation of molten material, in particular slag

Abstract

The invention relates to a dry granulator (10), wherein the dry granulator (10) comprises a housing (15) and an atomizer (20) arranged in the housing (15) with an atomizer element (55) rotatably mounted about a rotational axis (45), wherein the housing (15) comprises a first inner housing wall (70) with a first inner housing wall section (295) and a second inner housing wall section (305), wherein the atomizer element (55) comprises a wall (115) and a base (110), wherein the wall (115) has an axially spaced rim (125) on an axially facing side away from the base (110), wherein the rim (125) is formed with a varying shape between a first high point (185) and a first low point (190), wherein the rim (125) is spaced closer together at the first low point (190). is arranged towards the ground (110) as at the first high point (185),wherein the edge (125) is formed between including the first high point (185) and including the first low point (190), to spray molten material (35) from the atomizing element (55) towards the first and second housing inner wall sections (295, 305) along different trajectories (291, 296).

Description

[0001] The invention relates to a dry granulator for dry granulation of molten material according to claim 1.

[0002] A wet granulator for granulating slag and recovering waste heat is known from CN 108 998 604 A. The wet granulator has a granulating unit with a rotating slag pan. The slag pan has a plurality of channels arranged in a star shape, extending from radially inward to radially outward. The slag striking the slag pan is conveyed radially outward through the channels and is spun off from the slag pan radially outward, essentially in one plane. The liquid slag flies radially outward and falls downward along a trajectory path. The granulated slag is guided past an atomizer nozzle. The atomizer nozzle sprays atomized water onto the slag.

[0003] JP 2003 342047 A discloses a granulator with a substantially flat atomizing disc. The atomizing disc is made of a metallic material. Furthermore, the granules are cooled by water.

[0004] Dry granulation of molten material is a technology under development for processing molten material into solid granules. Molten material is, for example, molten metal or metallurgical slag, such as molten blast furnace slag. The process is then also called dry slag granulation (DSG) and is described, for example, in EP 2 747 920 B1. In this context, "dry" means that the molten material does not come into direct contact with liquid water during granulation. This contrasts, for example, with conventional industrial processes for granulating blast furnace slag, in which the molten slag is introduced into a water stream.The granulator is a container enclosed by a casing, which has a slag inlet, a gas inlet for the process gas used for cooling, and an exhaust line for heated process gas – for example, air, also called process air. The molten material, such as molten metallurgical slag, is applied to an atomization unit located in the casing of the granulator. This unit is, for example, a rapidly rotating unit known as a rotary atomizer; such a unit is shown, for example, in EP 2 747 920 B1. Due to the accelerations or forces transmitted when the molten slag comes into contact with the rotary atomizer, the molten material is broken up into fine droplets and ejected outwards.These fine, initially still molten droplets are cooled and solidify in the granulator. This occurs, for example, through the process gas and by impacting on – possibly cooled – surfaces of the granulator, such as the water-cooled granulator casing. As a result, solid particles are formed, referred to here as granules, which are then removed from the granulator. According to a well-known procedure, liquid or partially solidified – i.e., partly liquid, partly solidified – droplets fall downwards in the granulator after leaving the rotary atomizer and subsequently impacting the granulator casing, for example, into a fixed bed or a fluidized bed.

[0005] Conventional granulation technologies for dry granulation of molten material, such as liquid blast furnace slag, with rotary atomizers and the use of an impact on the casing have a large diameter. To prevent agglomeration of liquid and / or partially solidified droplets and / or fully solidified particles during flight from the rotary atomizer to the casing or after impact with the casing, the distance to the casing—which is usually arranged rotationally symmetrically to the rotary atomizer and thus generally round in cross-section—must be sufficiently large. A larger distance leads to a fanning out of the stream of droplets or particles emanating from the rotary atomizer, so that they fly less closely to one another or impact less closely. This reduces the risk of agglomeration during flight or upon impact.Agglomeration can occur upon impact, for example, when fully or partially liquid particles are deformed upon impact and thus come into contact with neighboring particles. However, increasing diameters lead to increasing space requirements, which is technologically and economically disadvantageous.

[0006] The object of the invention is to provide an improved dry granulator.

[0007] This object is achieved by means of the features of patent claim 1. Advantageous embodiments are specified in the dependent claims.

[0008] It has been recognized that an improved dry granulator for the dry granulation of molten material, in particular slag, can be provided by having a housing and an atomizer arranged in the housing with an atomizer element mounted so as to be rotatable about a rotation axis. The housing has a first housing inner wall with a first housing inner wall section and a second housing inner wall section. The second housing inner wall section is arranged axially offset from the first housing inner wall section along the rotation axis. The atomizer element has a wall and a base. The wall is circumferentially formed relative to the rotation axis and extends radially outwardly adjacent to the base. On an axial side facing away from the base in the axial direction, the wall has an edge arranged at an axial distance from the base.The edge is configured to extend at varying distances from the base between a first high point and a first low point. The edge is positioned closer to the base at the first low point than at the first high point. The edge is configured to spray molten material from the atomizer element toward the first and second housing inner wall sections along different trajectories, including the first high point and the first low point.

[0009] This design has the advantage that the molten granulate is distributed toward the first inner wall section of the housing, thus preventing a concentration of the molten material on the first inner wall in the region of a narrow band. In particular, adhesions of the molten material, which is propelled radially outward by the atomizer element, can be avoided.

[0010] For example, at the first high point, the edge can spray a first portion of the molten material from the atomizer element toward the first inner housing wall section along a first trajectory. At the first low point, the edge can spray a second portion of the molten material from the atomizer element toward the second inner housing wall section along a second trajectory. The first trajectory can be offset in the axial direction from the second trajectory, thereby avoiding the concentration of the molten material on the first inner housing wall. In the circumferential direction between the first high point and the first low point, the edge can also spray a further portion of the molten material along a further trajectory that runs axially between the first trajectory and the second trajectory.

[0011] In a further embodiment, the dry granulator has a granulate storage unit with a fluidized bed. The granulate storage unit is arranged radially between the housing and the atomizer element. The fluidized bed has a first storage section and a second storage section. The first storage section is arranged radially offset inward from the second storage section. The first housing inner wall section is oriented obliquely to the axis of rotation in order to deflect the first part of the molten material striking the first housing inner wall section towards the first storage section. The second housing inner wall section is oriented obliquely to the axis of rotation in order to deflect the second part of the molten material striking the second housing inner wall section towards the second storage section.This design has the advantage that the first and second portions of the molten material fall into the granule reservoir at a radial distance from each other, where they are cooled by the air flow flowing in via the fluidized bed and by the granules already present in the granule reservoir. In particular, the distribution of the molten material over the first and second housing inner wall sections also prevents parts of the molten material, in particular multiple droplets, from adhering to one another in the granule reservoir. This allows the droplets of molten material to be quickly cooled to granules in the granule reservoir, and the granules to have a substantially uniform granule size.

[0012] In a further embodiment, the first housing inner wall is arranged at an angle of 30° to 60°, in particular 40° to 50°, to a plane of rotation, inclined inward toward the axis of rotation. This configuration ensures that the molten material impacting the first housing inner wall is evenly distributed in the granule storage chamber.

[0013] The wall of the atomizer element is divided in the circumferential direction relative to the axis of rotation into at least a first wall section and at least one second wall section. The second wall section adjoins the first wall section in the circumferential direction. The edge extends on the first wall section between the first high point and a first low point, which is arranged offset in the circumferential direction from the first high point. On the second wall section, the edge extends from the first low point in the circumferential direction away from the first wall section. The edge is designed on the first wall section and on the second wall section to run at an angle to a plane of rotation relative to the axis of rotation. On both the first wall section and the second wall section, the edge is designed to spray the molten material from the atomizer element in the direction of the first housing inner wall.This design ensures that the top side of the atomizer element is substantially completely covered with the molten material, thereby preventing corrosion, in particular oxidation, of the atomizer element.

[0014] In a further embodiment, the atomizer element has a conical element. The conical element is arranged at the bottom on the side facing the wall and centered on the axis of rotation. The conical element extends away from the bottom along the axis of rotation. A tip of the conical element, which is arranged on a side of the conical element facing away from the bottom, projects beyond the first low point in the axial direction. Preferably, the tip of the conical element is arranged axially between the first high point and the first low point. This configuration ensures that the molten material striking the atomizer element does not accidentally spray off prematurely, thus ensuring an even distribution of the molten material on the atomizer element.

[0015] In a further embodiment, the atomizer element has a maximum total radial extent in the radial direction. The conical element has a first maximum radial extent at the base. A first ratio of the first maximum total radial extent to the maximum total radial extent is preferably 0.05 to 0.4 inclusive, in particular 0.1 to 0.25 inclusive. This configuration ensures that the material requirement for the conical element can be kept low, thus minimizing the manufacturing effort required to produce the atomizer element.

[0016] In a further embodiment, the atomizer element has a maximum total radial extent in the radial direction. The first high point has a first maximum distance from the base. A fourth ratio of the first maximum distance to the maximum total radial extent lies in a range from 0.1 to 1, preferably in a range from 0.15 to 0.3.

[0017] In a further embodiment, the atomizer element has a maximum overall radial extent in the radial direction, wherein the first low point has a first minimum distance from the bottom. A fifth ratio of the first minimum distance to the maximum overall radial extent lies in a range from 0.05 to 0.95 inclusive, preferably in a range from 0.05 to 0.3 inclusive, in particular from 0.08 to 0.2 inclusive. This ensures that the first low point is always arranged above the bottom. This ensures reliable coverage of the bottom by damming up the molten material through the wall. In particular, this prevents areas of the bottom from being exposed and not covered by the molten material. This reduces unwanted oxidation of the atomizer element.

[0018] In a further embodiment, a sixth ratio of a difference between the first maximum distance and the first minimum distance to the maximum total radial extent is in a range from 0.05 to 0.1 inclusive. This configuration ensures that the material requirement for producing the atomizer element, which is preferably machined from a solid material, can be kept low.

[0019] In a further embodiment, the wall has a radially inner wall side and a radially outer circumferential side. The wall extends in the radial direction between the wall inside and the outer circumferential side, tapering from the base in the axial direction towards the edge. Radially on the outside, the base has a second maximum radial extent. The wall has a minimum radial wall extent at the edge. A second ratio of the maximum total radial extent to the second maximum radial extent is 1.2 up to and including 1.9, in particular 1.4 up to and including 1.7. A third ratio of the maximum total radial extent to the minimum radial wall extent is 1.1 up to and including 1.5, in particular 1.2 up to and including 1.35.This design has the advantage that the wall is sufficiently wide so that in the event of oxidation of the outer circumferential side, which leads to material removal on the outer circumferential side and thus to a wall that becomes thinner from radially outside to radially inside with increasing operating time of the atomizer element, a long service life of the atomizer element is nevertheless ensured.

[0020] In order to minimize oxidation of the atomizer element on an outer peripheral side, the atomizer has a drive device with a receptacle and a protective gas channel. The atomizer element engages in the receptacle with a first section and is positively connected to the drive device for torque transmission. The atomizer element projects over the drive device with a second section, wherein the protective gas channel is guided in the drive device and opens into the receptacle on one side. A protective gas can be guided via the protective gas channel to act on the second section of the atomizer element. The second section, which is not arranged in the receptacle, is acted upon by the protective gas. The protective gas can be nitrogen, for example. The protective gas reduces oxidation of the outer peripheral side, so that the service life of the atomizer element can be further increased.

[0021] It is particularly advantageous if the atomizer element is made predominantly, in particular at least 80 percent by mass, of a carbon-based material, preferably graphite. This design has the advantage that adhesion of molten material to the atomizer element can be avoided.

[0022] In a further embodiment, the edge has a predefined first number of high points and a predefined second number of low points. The first number is from 1 to 5 inclusive. Additionally or alternatively, the second number is from 1 to 5 inclusive. It is particularly advantageous if the edge has only two or three or four high points and / or two or three or four low points. The small number of high points and / or low points has the advantage that the edge has a lower inclination in the circumferential direction to the plane of rotation and this reliably ensures that the molten material between the high point and the low point is also thrown off over the edge between the high point and the low point.This ensures complete wetting of the atomizer element on the top side, so that oxidation of the atomizer element can be avoided, especially when graphite is used for the atomizer element.

[0023] It is particularly advantageous if the predefined first number of high points is less than or equal to 1 per 0.5 m of circumference at the edge. Additionally or alternatively, the predefined second number of low points is also less than or equal to 1 per 0.5 m of circumference at the edge. This design ensures that there is sufficient distance between a high point and a low point, thus avoiding, in particular, a large gradient of the edge in the circumferential direction relative to a rotation plane between the high point and the low point.

[0024] The invention is explained in more detail below with reference to the figures. These show: FIG 1 shows a schematic sectional view through a dry granulator; FIG 2 shows a perspective section of the dry granulator; FIG 3 shows a sectional view along a FIG 2 shown sectional plane AA through the atomizer; and FIG 4 a sectional view along a FIG 2 shown section plane BB through the FIG 1 shown atomizer.

[0025] FIG 1 shows a schematic sectional view through a dry granulator 10.

[0026] The dry granulator 10 is designed for the dry granulation of molten material 35, in particular molten slag from a metallurgical process, for example, a blast furnace process. The dry granulator 10 comprises a housing 15, an atomizer 20, a granulate storage 25, and a feed 30 for supplying the molten material 35.

[0027] The housing 15 defines a housing interior 40, wherein the housing 15 extends substantially in the circumferential direction around a rotational axis 45 of the atomizer 20. The feed line 30 is guided through the housing 15 and opens into the housing interior 40 on one side adjacent to the atomizer 20. In particular, the feed line 30 can be guided at least in sections along the rotational axis 45 and / or open into the housing interior 40 on the rotational axis 45.

[0028] The atomizer 20 extends along the rotational axis 45 and has a drive device 50, an atomizer element 55, and an atomizer housing 60. The atomizer element 55 is rotatably mounted about the rotational axis 45 and is further connected in a rotationally fixed manner to the drive device 50. The drive device 50 can have a drive motor (not shown) that is designed to drive the atomizer element 55 and to rotate it about the rotational axis 45 during operation of the dry granulator 10. The drive motor can be arranged outside the housing interior 40 to prevent thermal overload of the drive motor. The drive motor can be connected to the drive motor in a torque-locking manner, preferably in a rotationally fixed manner, for example by means of a shaft 65. The shaft 65 can be rotatably mounted in the atomizer housing 60.

[0029] In the exemplary embodiment, the atomizer element 55 comprises graphite as its predominant material. "Predominantly" means that at least 50 percent by mass, preferably at least 80 percent by mass, is made of a carbon-based material. The carbon-based material can, in particular, be graphite.

[0030] The housing 15 has at least a first housing inner wall 70 and at least a second housing inner wall 75. In addition, the housing 15 can have a housing cover 80, preferably arranged on the top, wherein, for example, a discharge opening 85 is arranged in the housing cover 80. For example, the second housing wall 75 can be arranged adjacent to the first housing wall 70. Another configuration of the housing 15 is possible. In particular, for example, the discharge opening 85 can be arranged at a different position on the housing 15, for example on the first and / or second housing inner wall 70, 75.

[0031] The second housing inner wall 75 can extend substantially cylindrically around the rotational axis 45. In this case, the granulate storage 25 can be arranged in the radial direction between the second housing inner wall 75 and the atomizer housing 60. On the upper side, FIG 1 The first housing inner wall 70 adjoins the second housing inner wall 75. At least the first housing inner wall 70, preferably the first and second housing inner walls 70, 75, are designed to be cooled. The first housing inner wall 70 is arranged at an angle inwardly inclined position in the direction of the rotation axis 45. The first housing inner wall 70 can be substantially partially conical. At the first housing inner wall 70, the housing interior 40 tapers from the granulate reservoir 25 toward the discharge opening 85 along the rotation axis 45 in the axial direction.

[0032] Preferably, the first housing inner wall 70 is arranged at a wall angle δ to a rotation plane 76 perpendicular to the rotation axis 45. The wall angle δ can be a value of 30° to 60°, in particular of 40° to 50°. By way of example, FIG 1 the first housing inner wall 70 is arranged at the wall angle δ of 45° to the plane of rotation.

[0033] The first housing inner wall 70 is preferably smooth. Smooth means that the first housing inner wall 70 essentially has no elevations (> 0.2 mm), in particular no kinks, compressions, bumps, or the like.

[0034] The granulate storage 25 is delimited, for example, by the second housing inner wall 75 arranged in the axial direction on the underside of the first housing inner wall 70.

[0035] The atomizer element 55 is arranged substantially at the level of the first housing inner wall 70. As a result, the first housing inner wall 70 and the atomizer element 55 have an axial overlap. Axial overlap is understood to mean that when two components are projected in a radial direction perpendicular to the rotation axis 45 into a projection plane in which the rotation axis 45 extends, the two components, for example, the atomizer element 55 and the first housing inner wall 70, overlap.

[0036] The granulate storage unit 25 has a fluidized bed 90 and a compressor 95. The compressor 95 is fluidically connected to the fluidized bed 90. The fluidized bed 90 adjoins the underside of the housing interior 40. The fluidized bed 90 has a distributor base 100, with the distributor base 100 fluidically connected externally to the compressor 95. The distributor base 100 is arranged circumferentially between the atomizer housing 60 and the second housing inner wall 75.

[0037] FIG 2 shows a perspective section of the dry granulator 10.

[0038] The atomizer element 55 is bowl-shaped. The atomizer element 55 has at least one base 110 and a wall 115 adjoining the base 110 on the radially outer side. The wall 115 is arranged radially outwardly of the base 110 and extends away from the base 110 in the axial direction relative to the rotation axis 45. Together, the base 110 and the wall 115 define an atomizer interior 120. The wall 115 is formed to completely encircle the rotation axis 45 in the circumferential direction and encloses the base 110 on the radially outer side. As a result, the atomizer interior 120 is completely enclosed in the radial direction.

[0039] The wall 115 has an edge 125 on the side facing away from the base 110. The edge 125 is arranged completely spaced apart from the base 110 in the axial direction. The edge 125 is formed on the wall 115 so as to extend completely around the axis of rotation 45. The wall 115 is blunt at the edge 125. Radially on the outside, at an outer edge 130, the edge 125 abuts an outer peripheral side 135 of the atomizer element 55. A first partial section 140 of the wall 115 adjoining the outer edge 130 can be formed cylindrically and extending around the axis of rotation 45.

[0040] The edge 125 varies in an edge distance between the bottom 110 and the edge 125 between at least a first high point 185 and a first low point 190.

[0041] At the first high point 185, the edge distance is maximum, whereas at the first low point 190, the edge distance is minimum. Furthermore, the first low point 190 is arranged offset in the circumferential direction from the first high point 185. In the embodiment, the edge 125 additionally has a second high point 195 and a second low point 200, which are arranged offset from one another and from the first high point 185 and the first low point 190. In this case, the high point 185, 195 and the low point 190, 200 are each arranged offset in the circumferential direction about the axis of rotation. As a result, the edge 125 runs obliquely inclined in the circumferential direction between the high point 185, 195 and the nearest low point 190, 200 to a rotation plane perpendicular to the axis of rotation 45.

[0042] It has proven particularly advantageous if a first number of high points is limited to 185, 195 and a second number of low points to 190, 200. It is advantageous if the first number is from 1 to 5 inclusive and the second number is from 1 to 5 inclusive. It is even more advantageous if the edge 125 has only two or three or four high points 185, 195 and / or two or three or four low points 190, 200.

[0043] In the embodiment, the edge 125 has, for example, a jagged or wave-shaped profile, wherein, for example, a turning point of the profile of the edge 125 is arranged in the high point 185, 195 and / or the low point 190, 200. In a further development of the FIG 2 With the atomizer element 55 shown, it is also possible for the edge 125 to be designed according to a mathematical function instead of the serrated configuration of the edge 125. For example, it is conceivable for the edge 125 to be wave-shaped, in particular in the manner of a uniform wave. For example, the edge 125 could also be sinusoidal. A key feature of the design of the edge 125 is that it does not include jumps, in particular flanks extending in the axial direction parallel to the axis of rotation 45.

[0044] Between the high points 185, 195 and the low points 190, 200, the wall 115 is divided into wall sections 155, 160, 205, 210. A first wall section 155 extends, for example, between the first high point 185 and the first low point 190. In the first wall section 155, the edge 125 is continuously extending. In particular, the edge 125 at the first wall section 155 can have a constant gradient. In the embodiment, the edge 125 in the first wall section 155 slopes downwards from the first high point 185, which is arranged at a greater distance from the base 110 than the first low point 190, toward the first low point 190.

[0045] A second wall section 160 directly adjoins the first wall section 155 in the circumferential direction. The second wall section 160 extends in the circumferential direction between the first low point 190 and the second high point 195, which is closest in the circumferential direction and is located on a side facing away from the first high point 185. The second wall section 160 is continuous. In the second wall section 160, the edge 125 has a constant slope. In the second wall section 160, the edge 125 is continuous and increases continuously.

[0046] In the circumferential direction, a third wall section 205 adjoins the second high point 195. The third wall section 205 extends in the circumferential direction between the second high point 195 and the second low point 200, which is arranged in the circumferential direction on the side facing away from the first low point 190. The third wall section 205 can be designed essentially identically to the first wall section 155. In the circumferential direction, the fourth wall section 210 adjoins the second low point 200, with the fourth wall section 210 extending in the circumferential direction between the second low point 200 and the first high point 185. Thus, the fourth wall section 210 is arranged, for example, in the circumferential direction between the third wall section 205 and the first wall section 155. The fourth wall section 210 can be designed identically to the second wall section 160.At the first high point 185, the fourth wall section 210 abuts the first wall section 155 on the side facing away from the third wall section 205. The edge 125 is also continuous in the third wall section 205 and the fourth wall section 210.

[0047] FIG 3 shows a sectional view along a FIG 2 shown section plane AA through the atomizer 20.

[0048] For example, the section plane AA extends through the two low points 190, 200.

[0049] Additionally, the atomizer element 55 can have a conical element 215. The conical element 215 is arranged at a fixed end 220 on the base 110 and extends from a bottom 145 of the atomizer element 55. The conical element 215 is arranged centered on the rotation axis 45 and extends away from the base 110. The bottom 145 is arranged on an axial side facing away from the base relative to the rotation axis 45. The conical element 215 tapers from the fixed end 220 toward a tip 225. The tip 225 is arranged in the axial direction relative to the rotation axis 45 between the first low point 190 and the first high point 185.

[0050] In other words, the tip 225 projects beyond the edge 125 at least at the first low point 190 and / or the second low point 200. Furthermore, the tip 225 is preferably projected beyond the edge 125 at least at the first high point 185 and / or the second high point 195.

[0051] The mouth 230 of the feed 30 is arranged axially opposite the tip 225. The mouth 230 is also preferably arranged centered relative to the rotation axis 45, with the feed 30 preferably being arranged centered along the rotation axis 45, at least in the section adjacent to the mouth 230.

[0052] The atomizer element 55 has a maximum total radial extent R in the radial direction. The maximum total radial extent R refers, for example, to the outer edge 130 at the rim 125. In the exemplary embodiment, the outer circumferential side 135 is designed to be cylindrical, extending around the axis of rotation 45, so that the maximum total radial extent R also refers to the outer circumferential side 135. At the fixed end 220, the conical element 215 has a first maximum radial extent d1. Preferably, a first ratio d1 / of the first total radial extent d1 to that of the maximum total radial extent R is 0.05 to 0.4 inclusive, in particular 0.1 to 0.25 inclusive, particularly advantageously 0.15 to 0.2 inclusive.

[0053] Radially outwardly of the conical element 215, the base 110 has a base surface 235, which is, for example, flat. The base surface 235 extends, for example, perpendicular to the rotation axis 45. In the embodiment with the conical element 215, the base surface 235 is formed in a ring-shaped manner around the conical element 215. At a first transition 236 between the base surface 235 and the conical element 215, the conical element 215 is rounded to ensure a smooth and continuous transition between the conical element 215 and the base surface 235. Furthermore, this prevents the molten material 35 from adhering.

[0054] The wall 115 adjoins the base surface 235 radially on the outside. The base 110 has a second maximum radial extent d2 at the base surface 235, wherein a second ratio R / d2 of the maximum total radial extent R to the second maximum radial extent is preferably 1.2 to 1.9 inclusive, in particular 1.4 to 1.7 inclusive. At a second transition 237 between the base surface 235 and the wall 115, the wall 115 is rounded in order to ensure adhesion of the molten material 35 through a smooth and continuous transition. The second maximum extent d2 can be determined, for example, at an intersection point of a straight line that runs tangential to the wall 115 and a plane in which the base surface 235 runs.

[0055] The wall 115 is wider in the radial direction on the side facing the base 110 than at the edge 125. In other words, the wall 115 tapers in the axial direction from the base 110 towards the edge 125. At the edge 125, the wall 115 has a minimum radial wall extension w2 that is greater than the second maximum radial extension d2. At a third transition 238 between the wall inner side 240 and the edge 125, the wall 115 is rounded so that adhesion of the molten material 35 is ensured by a smooth and continuous transition. At the third transition 238, the edge 125 has the minimum wall extension w2. A third ratio R / w2 of the maximum total radial extension R to the minimum radial wall extension w2 is preferably 1.1 to 1.5 inclusive, in particular 1.2 to 1.35 inclusive.

[0056] The wall 115 primarily forms the bowl-shaped configuration of the atomizer element 55. The wall 115 has the radially inwardly arranged wall inner side 240, wherein the wall inner side 240 is curved and the second transition 237 between the bottom surface 235 and the wall inner side 240 is continuous. The wall inner side 240 runs, for example, at an angle to the bottom surface 235, which runs, for example, perpendicular to the axis of rotation 45. The wall inner side 240 can, for example, be arranged at an angle α to the bottom surface 235. The first angle α is preferably 15° up to and including 60°, in particular 30° up to and including 40°, particularly advantageously 35°.

[0057] The edge 125 is arranged radially outward and on the side of the wall 115 facing away from the base 110. The edge 125 is preferably arranged at an angle β to the rotation plane 76 and the base surface 235. The edge 125 is preferably arranged at an angle β inward toward the rotation axis 45, so that with increasing distance of the edge 125 from the rotation axis 45, a third maximum distance l1 of the edge 125 from the base surface 235 increases.

[0058] At the first high point 185, the edge 125 has a first maximum distance H1 from the base 110. At the first low point 190, the edge 125 has a first minimum distance G1 from the base 110 in the axial direction. At the second high point 195, the edge 125 has a second maximum distance G1 from the base 110. At the second low point 200, the edge has a second minimum distance G1 from the base 110 in the axial direction. In the embodiment, the first minimum distance G1 and the second minimum distance are, by way of example, identical. They can also be different. In the embodiment, the first maximum distance H1 and the second maximum distance are, by way of example, identical. They can also be different.

[0059] At the first low point 190, the edge 125 is thus offset toward the base 110. The first minimum distance G1 is selected such that the first wall section 155 also projects beyond the base 110 at the first low point 190. It is particularly advantageous if a fourth ratio H1 / R of the first maximum distance H1 to the maximum total radial extent R is greater than or equal to 0.1 up to and including 1, and preferably lies in a range from and including 0.1 up to and including 0.3.

[0060] It is particularly advantageous if a fifth ratio G1 / R of the first minimum distance G1 to the maximum total radial extent R is greater than 0.05 to 0.95 inclusive and preferably lies in a range of 0.05 to 0.3 inclusive, in particular 0.08 to 0.2 inclusive.

[0061] Furthermore, a sixth ratio (H1-G1) / R from a difference between the first maximum distance H1 and the first minimum distance G1 and the maximum total radial extent R can be greater than or equal to 0.05 and preferably in a range from or equal to 0.05 to or equal to 0.1.

[0062] Furthermore, it is advantageous if, as a further condition for the first number of high points 185, 195, the first number of high points is less than or equal to 1 per 0.5 m of circumference. Furthermore, it is advantageous if, as an additional condition for the second number of low points 190, 200, the second number is less than or equal to 1 per 0.5 m of circumference. The circumference is hereby referenced to the outer edge 130 of the rim 125.

[0063] The second angle β is smaller than the first angle α. In particular, the second angle β can be 0° to 45°, in particular 3° to 12°. While an inner edge 245 at the third transition 238 of the wall inner side 240 to the edge 125 is continuous and rounded, in the embodiment, the outer edge 130 is sharp-edged. The sharp-edged design of the outer edge 130 serves to ensure reliable spraying of the molten material 35 from the atomizer element 55.

[0064] FIG 4 shows a sectional view along a FIG 2 shown section plane BB through the FIG 1 shown atomizer 20.

[0065] The section plane BB extends, for example, through the two high points 185, 195.

[0066] In the axial direction, a second section 150 adjoins the first section 140 on the side facing the underside 145 of the atomizer element 55. A portion of the second section 150 may, for example, be elliptical in shape. Another configuration of the second section 150 is also conceivable. In particular, the geometric configuration of the second section 150 may be configured as a connecting profile for the positive connection of the atomizer element 55 to the shaft 65.

[0067] In addition to the shaft 65, the drive device 50 has a support unit 250. The support unit 250 is connected to the shaft 65 in a torque-locking manner. The support unit 250 serves to support the atomizer element 55 and to secure it in the housing interior 40. The support unit 250 has a receptacle 255, wherein the atomizer element 55 is arranged in sections in the receptacle 255. The atomizer element 55 protrudes with the first partial section 140 from the receptacle 255, while the second partial section 150 engages in the receptacle 255. In the receptacle 255, the atomizer element 55 is positively connected to the support unit 250.

[0068] A torque for driving the atomizer element 55 is preferably exchanged between the drive motor and the atomizer element 55 via the shaft 65 and the carrier unit 250.

[0069] In the embodiment, the carrier unit 250 has a carrier ring 266. The first carrier ring 266 is coupled directly or indirectly to the shaft 65 in a torque-locking, in particular rotationally fixed, manner. The first carrier ring 266 essentially delimits the receptacle 255. The first carrier ring 266 is preferably positively connected to the outer circumferential side 135 of the atomizer element 55. To form the positive connection between the outer circumferential side 135 of the atomizer element 55 and the first carrier ring 266, the first carrier ring 266 can, for example, have a polygonal profile on an inner circumferential side 280, wherein the outer circumferential side 135 is formed to correspond to the polygonal profile on the inner circumferential side 280 of the first carrier ring 266.On the underside, the atomizer element 55 can rest on the carrier unit 250 in the receptacle 255, wherein an axial position of the atomizer element 55 in the receptacle 255 is secured, for example, by a dead weight of the atomizer element 55.

[0070] Additionally, the support unit 250 can be designed to be cooled. A cooling medium can be fed to the support unit 250 via the shaft 65, which, for example, has an inlet and a return channel, in order to cool the atomizer element 55 on the underside.

[0071] A shielding gas channel 285 is arranged in the support ring 266. The shielding gas channel 285 is guided at an angle from the radial outside to the radial inside. The shielding gas channel 285 opens into the receptacle 255 on the side facing the first sub-section 140. A shielding gas 290, for example nitrogen, can be blown into the end of the receptacle 255 via the shielding gas channel 285 using additional means (not shown). It is particularly advantageous if the shielding gas 290 is blown into the receptacle 255 in a circulating manner, i.e. at a circumferential speed, in the direction of the first sub-section 140. Because the shielding gas channel 285 is designed at an angle inwardly towards the first sub-section 140, the shielding gas 290 is blown onto the first sub-section 140, which is arranged outside the receptacle 255. This can reduce oxidation of the atomizer element 55, which is essentially made of graphite.

[0072] Below are the Figuren 1 bis 4 explained together.

[0073] During operation of the dry granulator 10, the drive motor of the drive device 50 drives the atomizer element 55 via the shaft 65 and the carrier unit 250. The atomizer element 55 can rotate about the rotational axis 45 at a speed of approximately 500 to 1500 revolutions per minute. Furthermore, molten material 35, in particular liquid slag, is introduced into the housing 15 via the feed 30. The molten material 35 exits the feed 30 at the opening 230 and flows downwards along the rotational axis 45. The molten material 35 comes into contact with the atomizer element 55 at the cone element 215. The molten material 35 is redirected outwards by the cone element 215 from its movement along the rotational axis 45. The molten material 35 covers the cone element 215. The molten material 35 flows in the axial direction along the cone element 215 towards the bottom 110.In this case, the molten material 35 is further guided radially outwards towards the bottom surface 235 under the influence of centrifugal force on the cone element 215.

[0074] At the bottom surface 235, the molten material 35 flows radially outward and is strongly accelerated in the radial and circumferential directions by the rotation of the atomizer element 55. Radially outward, the molten material 35 encounters the wall 115. The molten material 35 is further accelerated in the radial outward and circumferential directions. Furthermore, the molten material 35 is guided along the wall inner side 240 in the axial direction away from the bottom 110 toward the edge 125. The continuous second transition 237 between the bottom surface 235 and the wall inner side 240 has the advantage of preventing accumulation of the molten material 35 during radial outward acceleration. Furthermore, the cone element 215 ensures reliable coverage of the bottom surface 235 and the wall inner side 240.This prevents oxidation of the atomizer element 55 with atmospheric oxygen and premature slag from leaving the rotating plate. The molten material 35 flows radially outward and in the axial direction away from the base 110. The molten material 35 flows around the inner edge 245 and remains in contact with the atomizer element 55 due to the small second angle β. The rounded third transition 238 prevents unwanted splashing of the molten material 35 at the inner edge 245.

[0075] The molten material 35 flows around the inner edge 245 and flows radially outward along the edge 125. The molten material 35 flows to the outer edge 130, where the molten material 35 is sprayed off at the outer edge 130.

[0076] At the first high point 185 and at the second high point 195, for example, a first part of the molten material 35 leaves the atomizer element 55 on a first trajectory 291 (cf. FIG 1 ). The first drop of the first part of the molten material 35 flies along the first trajectory 291 in the direction of a first housing inner wall section 295 of the first housing inner wall 70. In the liquid state, the first drop strikes the first housing inner wall section 295. Due to the obliquely inclined arrangement of the first housing inner wall 70, the first drop of the molten material 35 bounces off the first housing inner wall section 295 and is deflected substantially downwards along the axis of rotation 45 in the direction of a first storage section 300 of the granulate storage 25.

[0077] Due to the axially offset arrangement of the first high point 185 and the second high point 195 with respect to the first low point 190 and the second low point 200, a second portion of the molten material 35 is sprayed from the atomizer element 55 at the first and second low points 190, 200 on a second trajectory 296 at the outer edge 130. A second drop of the second portion flies along the second trajectory 296, which is axially offset from the first trajectory 291, in the direction of the first housing inner wall 70. The second drop strikes the first housing inner wall 70 in a second housing inner wall section 305, which is located lower along the rotation axis 45 and thus on the side of the first housing inner wall facing the granulate reservoir 25.The second droplet bounces off the second housing inner wall section 305, which is arranged radially further outward than the first housing inner wall section 295 due to its arrangement on the side facing the granule storage 25. The second storage section 310 of the granule storage 25 is arranged radially outward of the first storage section 300. The second droplet flies into the second storage section 310.

[0078] In the first storage section 300 and the second storage section 310, the first drop and the second drop are cooled by the process air in the fluidized bed 90 blown in by the compressor 95 to such an extent that the first drop solidifies in the first storage section 300 and the second drop solidifies at a distance from the first drop in the second storage section 310.

[0079] Of course, molten material 35 is also sprayed off at the edge 125 between the high point 185, 195 and the low point 190, 200. The additional droplets sprayed off between the high point 185, 195 and the low point 190, 200 each fly along additional trajectories, which are fanned out between the first trajectory 291 and the second trajectory 296, toward the first housing inner wall 70. Due to the design of the atomizer element 55, a jet of droplets, which forms on the atomizer element 55 from the molten material 35 by spraying, is thus fanned out and impinges on the first housing inner wall 70 in a fanned-out manner between the first and second trajectories 291, 296.The fanned-out design has the advantage that adhesion of the drops of the molten material 35 to the first housing inner wall 70 can be avoided and thus detachment of conglomerated drops of molten material 35 on the first housing inner wall 70 can be easily avoided.

[0080] Furthermore, fanning out the molten material 35 at the atomizer element 55 has the further advantage of reducing the likelihood that drops entering the granule reservoir 25 in a liquid state will not collide with other drops that have not yet solidified, thus preventing multiple drops of molten material 35 from adhering to one another. This ensures high quality and, in particular, a reliable grain size of the molten material 35 solidified into granules in the granule reservoir 25.

[0081] Furthermore, reliable cooling of the drops of molten material 35 arriving in the granulate storage 25 and reliable solidification of the drops of molten material 35 in the granulate in the fluidized bed 90 of the granulate storage 25 can be ensured.

[0082] Furthermore, the molten droplets release large amounts of heat into the process air as they cool. The process air can be discharged from the housing interior 40 via the discharge opening 85 and used, for example, to flow through a heat exchanger to generate steam. This configuration has the advantage that, using the dry granulator 10 shown in the figures, not only is high process reliability ensured, but also a high quality of the molten material 35 solidified into granules and a corresponding grain size can be ensured, and the heat contained in the molten material 35 can be further utilized.

[0083] Furthermore, the use of water for cooling the molten material 35 can be dispensed with, so that environmental pollution with the dry granulator 10 shown in the figures is reduced.

[0084] To ensure a long service life of the atomizer element 55, which is preferably made of graphite, the atomizer element 55 is essentially completely wetted by the molten material 35 on the side facing the orifice 230. This ensures that the atomizer element 55, heated to 1500°C, is protected against oxidation. To counteract oxidation of the graphite occurring on the outer peripheral side 135 in the region of the first subsection 140, the protective gas 290 can be blown onto the first subsection 140 by means of the protective gas channel 285, thus preventing or reducing oxidation of the atomizer element 55 on the outer peripheral side 135.

[0085] Should oxidation of the first section 140 on the outer peripheral side 135 nevertheless occur, the minimal radial wall extension w2 ensures a long service life. Furthermore, reliable spray-off behavior is ensured by the blunt wall 115 at the edge 125, even if the wall 115 on the first section 140 on the outer peripheral side 135 has been eroded by oxidation. List of reference symbols

[0086] 10 Dry granulator 15 Housing 20 Atomizer 25 Granule storage 30 Feed 35 Molten material 40 Housing interior 45 Rotation axis 50 Drive device 55 Atomizer element 60 Atomizer housing 65 Shaft 70 First housing inner wall 75 Second housing inner wall 76 Rotation plane 80 Housing cover 85 Discharge opening 90 Fluidized bed 95 Compressor 100 Distributor base 105 Storage volume 110 Base 115 Wall 120 Atomizer interior 125 Rim 130 Outer edge 135 Outer peripheral side 140 First section 145 Bottom 150 Second section 155 First wall section 160 Second wall section 165 First angular segment 170 second angle segment 175 first edge section 180 second edge section 185 first high point 190 first low point 195 second high point 200 second low point 205 third wall section 210 fourth wall section 215 conical element 220 fixed end 225 tip 230 mouth 235 base surface 236 first transition 240 wall inside 245 inner edge 250 support unit 255 receptacle 266 first support ring 280 innerPeripheral side 285Shielding gas channel 290Shielding gas 295First housing inner wall section 300First storage section 305Second housing inner wall section 310Second storage section d1first maximum radial extension d2second maximum radial extension d3third maximum radial extension G1first minimum distance HRedge distance H 1first maximum distance 11third maximum distance Rmaximum total radial extension w2minimal radial wall extension αfirst angle βsecond angle δwall angle

Claims

1. Dry granulator (10) for dry granulation of molten material (35), in particular slag from a metallurgical process, - wherein the dry granulator (10) has a housing (15) and an atomizer (20) arranged in the housing (15) with an atomizer element (55) mounted rotatably about a rotation axis (45), - wherein the housing (15) has a first housing inner wall (70) with a first housing inner wall section (295) and a second housing inner wall section (305) arranged axially offset from the first housing inner wall section (295) along the rotation axis (45), - wherein the atomizer element (55) has a wall (115) and a base (110),- wherein the wall (115) is designed to run circumferentially relative to the rotational axis (45) and adjoins the base (110) radially on the outside and has, on an axial side facing away from the base (110) in the axial direction, an edge (125) arranged at a distance axially from the base (110), - wherein the edge (125) is designed to run at a varying distance from the base (110) between a first high point (185) and a first low point (190), - wherein the edge (125) is arranged at a closer distance to the base (110) at the first low point (190) than at the first high point (185), - wherein the edge (125) is designed between and including the first high point (185) and and including the first low point (190), molten material (35) from the atomizer element (55) in the direction of the first and the second housing inner wall section (295, 305) along different trajectories (291, 296).

2. Dry granulator (10) according to claim 1, - comprising a granulate reservoir (25) with a fluidized bed (90), - wherein the granulate reservoir (25) is arranged in the radial direction between the housing (15) and the atomizer element (55), - wherein the fluidized bed (90) has a first reservoir section (300) and a second reservoir section (310), - wherein the first reservoir section (300) is arranged radially offset inwardly from the second reservoir section (310), - wherein the first housing inner wall section (295) is oriented obliquely to the rotation axis (45) in order to deflect a first portion of the molten material (35) striking the first housing inner wall section (295) in the direction of the first reservoir section (300), - wherein the second housing inner wall section (305) is oriented obliquely to the rotation axis (45),to deflect a second part of the molten material (35) striking the second housing inner wall section (305) towards the second storage section (310).

3. Dry granulator (10) according to claim 2, - wherein the first housing inner wall (70) is arranged at a wall angle of 30° to 60° inclusive, in particular 40° to 50° inclusive, to a rotation plane (76) to the rotation axis (45) inclined obliquely inwards in the direction of the rotation axis (45).

4. Dry granulator (10) according to one of the preceding claims, - wherein the wall (115) is divided in the circumferential direction relative to the rotation axis (45) into at least one first wall section (155) and at least one second wall section (160), - wherein the second wall section (160) adjoins the first wall section (155) in the circumferential direction, - wherein the edge (125) on the first wall section (155) extends between the first high point (185) and a first low point (190), which is arranged offset in the circumferential direction from the first high point (185), - wherein the edge (125) on the second wall section (160) extends from the first low point (190) in the circumferential direction away from the first wall section (155), - wherein the edge (125) on the first wall section (155) and on the second wall section (160) is inclined obliquely in circumferential direction to a plane of rotation (76) to the axis of rotation (45),- wherein the edge (125) is designed both on the first wall section (155) and on the second wall section (160) to spray the molten material (35) from the atomizer element (55) in the direction of the first housing inner wall (70).

5. Dry granulator (10) according to one of the preceding claims, - wherein the atomizer element (55) has a conical element (215), - wherein the conical element (215) is arranged on the base (110) on the side facing the wall (115) and centered on the axis of rotation (45), - wherein the conical element (215) extends away from the base (110) along the axis of rotation (45), - wherein a tip (225) of the conical element (215), which is arranged on a side of the conical element (215) facing away from the base (110), projects beyond the first low point (190) in the axial direction, - wherein the tip (225) of the conical element (215) is preferably arranged axially between the first high point (185) and the first low point (190).

6. Dry granulator (10) according to claim 5, - wherein the atomizer element (55) has a maximum total radial extent (R) in the radial direction, - wherein the cone element (215) has a first maximum radial extent (d1) at the bottom (110), - wherein a first ratio (d1 / R) of the first maximum total radial extent (d1) to the maximum total radial extent (R) is preferably 0.05 to 0.4 inclusive, in particular 0.1 to 0.25 inclusive.

7. Dry granulator (10) according to one of the preceding claims, - wherein the atomizer element (55) has a maximum total radial extent (R) in the radial direction, - wherein the first high point (185) has a first maximum distance (H1) from the base (110), - wherein a fourth ratio (H1 / R) of the first maximum distance (H1) to the maximum total radial extent (R) is in a range up to and including 0.1 up to and including 1, preferably in a range from and including 0.1 up to and including 0.

3.

8. Dry granulator (10) according to one of the preceding claims, - wherein the atomizer element (55) has a maximum total radial extent (R) in the radial direction, - wherein the first low point (190) has a first minimum distance (G1) from the base (110), - wherein a fifth ratio (G1 / R) of the first minimum distance (G1) to the maximum total radial extent (R) is in a range from 0.05 to 0.95 inclusive, preferably in a range from 0.05 to 0.3 inclusive, in particular from 0.08 to 0.2 inclusive.

9. Dry granulator (10) according to claim 8, - wherein a sixth ratio ((H1-G1) / R) of a difference between the first maximum distance (H1) and the first minimum distance (G1) to the maximum total radial extent (R) is in a range from 0.05 to 0.1 inclusive.

10. Dry granulator (10) according to one of the preceding claims, - wherein the wall (115) has a radially inner wall side (240) and a radially outer circumferential side (135), - wherein the wall (115) is tapered in the radial direction between the wall inner side and the outer circumferential side (135) from the base (110) in the axial direction towards the edge (125), - wherein the base (110) has a second maximum radial extension (d2) on the radial outside, - wherein the wall (115) has a minimum radial wall extension (w2) at the edge (125), - wherein a second ratio (R / d2) of the maximum total radial extension (R) to the second maximum radial extension (d2) is 1.2 to 1.9 inclusive, in particular 1.4 to 1.7 inclusive,- wherein a third ratio (R / w2) of the maximum total radial extension (R) to the minimum radial wall extension (w2) is 1.1 to 1.5 inclusive, in particular 1.2 to 1.35 inclusive., 11. Dry granulator (10) according to one of the preceding claims, - wherein the atomizer (20) has a drive device (50) with a receptacle (255) and a protective gas channel (285), - wherein the atomizer element (55) engages with a first partial section (140) in the receptacle (255) and is positively connected to the drive device (50) for torque transmission, - wherein the atomizer element (55) projects beyond the drive device (50) with a second partial section (150), - wherein the protective gas channel (285) is guided in the drive device (50) and opens into the receptacle (255) on one side, - wherein a protective gas (290) for acting on the second partial section (150) of the atomizer element (55) can be guided via the protective gas channel (285).

12. Dry granulator (10) according to one of the preceding claims, - wherein the atomizer element (55) is made predominantly, in particular at least 80% by mass, of a carbon-based material, preferably graphite.

13. Dry granulator (10) according to one of the preceding claims, - wherein the edge (125) has a predefined first number of high points (185, 195) and a predefined second number of low points (190, 200), - wherein the first number is from 1 to 5 inclusive and / or the second number is from 1 to 5 inclusive. - wherein advantageously the edge (125) has exclusively two or three or four high points (185, 195) and / or two or three or four low points (190, 200).

14. Dry granulator (10) according to one of the preceding claims, - wherein the predefined first number of high points (185, 195) is less than or equal to 1 per 0.5 m circumference at the edge (125), - and / or - wherein the predefined second number of low points (190, 200) is less than or equal to 1 per 0.5 m circumference at the edge (125).

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