Batch furnace for annealing material and method for heat treatment of a furnace material

Abstract

The present invention relates to a batch furnace for annealing material comprising a furnace housing which has a closable loading opening, a receiving chamber for furnace material and a device for convective heat transfer to the furnace material by a heat transfer medium, wherein the device for convective heat transfer comprises at least one heating device and at least one fan which is arranged in the furnace housing wherein the receiving chamber is arranged on the suction side of the fan and at least one nozzle array is arranged on the pressure side of the fan, wherein the nozzle array has a central opening which forms an intake duct of the fan and the nozzle array projects radially beyond the fan. The invention further relates to a method for heat treatment of a furnace material.

Claims

1. A batch furnace for annealing material comprising: a furnace housing which has a closable loading opening, a receiving chamber for furnace material, and a device for convective heat transfer to the furnace material by a heat transfer medium, the device for convective heat transfer including a heating device and a fan which is arranged in the furnace housing, the receiving chamber arranged on a suction side of the fan, and a nozzle array arranged on a pressure side of the fan and that projects radially beyond the fan, wherein the nozzle array and the receiving chamber are positioned relative to one another so that during operation, the heat transfer medium flows through the nozzle array into the receiving chamber directly onto the furnace material for convective heat transfer, and the nozzle array includes a central opening which forms an intake duct of the fan, a nozzle plate with an inner side that faces the receiving chamber, and a plurality of nozzles having nozzle ends that protrude beyond the nozzle plate, the plurality of nozzles disposed on the inner side of the nozzle plate so that during the operation, the nozzle ends are directed directly at the furnace material and the heat transfer medium flows from the nozzle ends directly at the furnace material in the receiving chamber.

2. The batch furnace according to claim 1, wherein the fan and the nozzle array are arranged concentrically with respect to one another.

3. The batch furnace according to claim 1, wherein the heating device is arranged concentrically with respect to the fan in a pressure duct between the fan and the furnace housing.

4. The batch furnace according to claim 1, wherein the nozzle array terminates in a fluid-tight manner at an inner wall of the furnace housing.

5. The batch furnace according to claim 1 wherein the nozzle array is arranged directly upstream of the suction side of the fan.

6. The batch furnace according to claim 1, wherein the nozzle plate is a funnel-shaped nozzle plate.

7. The batch furnace according to claim 6, wherein the funnel-shaped nozzle plate is configured to be annular.

8. The batch furnace according to claim 6, wherein the plurality of nozzles are tubular and/or slot-shaped and are arranged around a centre of the nozzle plate on an inner side in at least one nozzle region in a circular manner.

9. The batch furnace according to claim 8, wherein the pressure side of the fan is in fluid communication with the receiving chamber through the plurality of nozzles.

10. The batch furnace according to claim 1, wherein the central opening of the nozzle array is arranged directly opposite the suction side of the fan.

11. The batch furnace according to claim 1, wherein the intake duct is formed between the fan and the receiving chamber for the circulation of the heat transfer medium.

12. The batch furnace according to claim 1, further comprising at least two of the fans arranged in juxtaposition on both sides of the receiving chamber, wherein each of the fans is assigned at least one of the heating device and/or at least one inlet for an externally heated heat transfer medium.

13. The batch furnace according to claim 1, wherein the fan has at least one flow duct which is arranged on the pressure side of the fan and the flow duct conducts the heat transfer medium to the heating device.

14. The batch furnace according to claim 1, wherein the fan is a radial fan.

15. The batch furnace according to claim 1, wherein the fan has a drive which is arranged outside the furnace housing.

16. The batch furnace according to claim 1, wherein the receiving chamber is configured to be a substantially hollow cylinder, wherein the fan is arranged on a front side of the receiving chamber.

17. The batch furnace according to claim 1, wherein the furnace housing has at least one inlet for an externally heated heat transfer medium.

18. The batch furnace according to claim 1, wherein the heating device comprises a heating line for a gaseous externally heated heat transfer medium.

19. A method for heat treatment of a furnace material with the batch furnace according to claim 1, the method comprising: arranging the furnace material in the receiving chamber of the batch furnace; guiding the heat transfer medium by the fan to the heating device; heating the heat transfer medium with the heating device; and guiding the heated heat transfer medium through the plurality of nozzles of the nozzle array directly onto the furnace material for convective heat transfer.

20. The method according to claim 19, wherein the fan is a radial fan.

Description

(1) In the Figures

(2) FIG. 1 shows a perspective view of a housing part of a batch furnace with a nozzle array according to one exemplary embodiment of the invention and

(3) FIG. 2 shows a perspective longitudinal sectional view through the housing part of the batch furnace according to FIG. 1.

(4) A batch furnace with a housing part 10a of the furnace housing according to FIG. 1 is preferably used for the heat treatment of aluminium annealing material, for example of aluminium coils. The batch furnace can be generally used for coils (independent of material) or other annealing material. The batch furnace specifically involves a single coil furnace which is adapted for heat treatment of individual coils. The invention can also be applied to single-chamber furnaces which are suitable for the heat treatment of slabs, billets or coils.

(5) The batch furnace comprises a furnace housing 10 which substantially comprises an aluminium receiving chamber 11, a closable loading opening not shown and one or more devices for convective heat transfer 20 to the furnace material through a heat transfer medium. The respective device for convective heat transfer 20 in this case comprises a heating device 21 and a fan 22. The device for convective heat transfer 20 will be discussed in detail subsequently.

(6) The furnace housing 10 is configured to be hollow cylindrical, wherein a housing part 10a according to FIG. 1 is arranged in each case at an axial end of the furnace housing 10. Furthermore, the furnace housing 10 can also be formed by another furnace shape. For example, the furnace housing 10 has a rectangular furnace shape, in particular a box-shaped furnace shape. The furnace housing 10 can also have only one housing part 10a, for example, at an axial end of the furnace housing 10. The furnace housing 10 comprises a steel construction for stiffening the housing which is arranged on an outer surface of the furnace housing 10.

(7) The housing part 10a has a circumferential shape contour in a circumferential region on a front side of the housing part 10a. The shape contour engages in the closed state of the furnace housing 10, in particular during operation of the batch furnace, in a complementary shape contour of a further housing part not shown, in particular a housing central part. The circumferential shape contour makes it possible to achieve a tight connection, for example, of the housing part 10a with the housing central part. The housing part 10a has two cylinders on the shape contour for securing the tight connection between the housing part 10a and the housing central part. The housing part 10a can also have a plurality of cylinders on the shape contour. The cylinders can in this case each be formed by a securing cylinder, in particular closure cylinder and/or locking cylinder. Furthermore, the housing part 10a has an inlet for an externally heated heat transfer medium. Likewise the housing part 10a has an outlet 12 for removal of burner gases into an exhaust gas line.

(8) Furthermore, the furnace housing 10 has a thermal insulation which is arranged internally on the furnace housing 10. The thermal insulation protects the furnace housing 10 from damage due to impermissible effect of temperature during the heat treatment of the furnace material. Furthermore, energy losses during the heat treatment are reduced by the thermal insulation.

(9) The furnace housing 10 can be formed in different variants which are not shown. In a first variant the furnace housing can be formed in three parts with an exchangeable housing central part, in particular a central piece. In this case, the housing central part is separated from the two lateral housing parts 10a so that the housing central part can be exchanged. The batch furnace can therefore be adapted according to length to different annealing material parts, in particular different coils.

(10) In a second variant the furnace housing 10 can also be formed in three parts. Unlike the first variant, in the second variant the housing central part can be formed by a bottom piece. The bottom piece can have transport means, in particular rollers so that it is possible to move the housing central part transversely to the longitudinal direction of the batch furnace. The lateral housing parts 10a each have a housing extension in the longitudinal direction of the batch furnace. The housing extensions extend in this case in the direction of the receiving chamber 11. In the closed state of the batch furnace the housing extensions with the bottom piece form the receiving chamber 11, wherein the receiving chamber 11 is delimited laterally by the housing parts 10a. The furnace housing 10 can furthermore also be formed in a divided manner in another variant or in one piece.

(11) The furnace housing 10 according to FIG. 1 therefore limits the receiving chamber 11 in which the furnace material or the annealing material is arranged during operation of the batch furnace. This is a single receiving chamber 11. In the batch furnace with the furnace housing 10, the receiving chamber 11 can be loaded with a coil, in particular an aluminium coil. To this end, the receiving chamber 11 can have a bearing device for the furnace material, in particular for the aluminium coil. For example the bearing device is formed by a bearing block or a bearing linkage. The bearing device can be connected to the bottom of the receiving chamber 11. For example, the coil can also be laid on its lateral surface. The coil can also be stored differently in the receiving chamber 11. The receiving chamber 11 is configured to be substantially hollow cylindrical and therefore approximately adapted to the shape of the coil to be heated. The receiving chamber 11 forms an empty free space in the unloaded state of the batch furnace. The receiving chamber 11 is in this case accessible through a closable loading opening not shown.

(12) The loading opening can be opened or closed by a cover which can be pivoted about a longitudinal axis of rotation running in the longitudinal direction of the furnace housing 10. Here a coil gripper can be used for loading the receiving chamber 11. This design is particularly suitable for cylindrical furnace housings. Furthermore the loading opening can be opened or closed by an axial displacement of the lateral housing parts 10a so that the receiving chamber 11 can be loaded by a C hook or a fork lift truck. For example, in a further design of the furnace housing 10 a lateral housing part 10a or both lateral housing parts 10a are pivotable about a transverse axis of rotation running transversely to the longitudinal direction of the furnace housing 10. The loading opening can also be opened or closed by another non-specified design of a cover or a housing element.

(13) In the perspective view according to FIG. 1, the fan 22 of the device for convective heat transfer 20 and a nozzle array 30 is further shown. The nozzle array 30 is arranged on a pressure side 24 of the fan 22 not shown. Furthermore, the nozzle array 30 has a central opening which forms an intake duct 31 of the fan 22. Here the fan 22 and the nozzle array 30 are arranged concentrically with respect to one another. The intake duct 31 is thus formed between the fan 22 and the receiving chamber 11 for circulation of the heat transfer medium. Furthermore, the intake duct 31 can also be formed by an opening which is formed at any position, in particular a decentralized position in the nozzle array 30. Furthermore, the fan 22 and the nozzle array 30 can also be arranged eccentrically with respect to one another. The nozzle array 30 projects radially beyond the fan 22. The nozzle array 30 is configured in such a manner that the nozzle array 30 terminates in a fluid-tight manner at the inner wall of the furnace housing 10. For example, the nozzle array 30 is configured in such a manner that a spacing is formed between a radial outer side, in particular a circumference, of the nozzle array 30 and the inner wall of the furnace housing 10. The spacing between the nozzle array 30 and the inner wall of the furnace housing 10 can be formed by an annular gap.

(14) The nozzle array 30 is arranged directly upstream of the suction side 23 of the fan 22. This allows a compact construction of the fan 22 with the nozzle array 30 in the furnace housing 10. Advantageously the receiving chamber 11 can thereby be enlarged with the same dimensions of the furnace housing 10 or the dimensions of the furnace housing can be reduced. Thus, the overall size of the batch furnace can be reduced.

(15) The fan 22 is in fluid communication with the receiving chamber 11 of the furnace material through the intake duct 31 of the nozzle array 30. The intake duct 31 of the nozzle array 30 is therefore arranged directly opposite the suction side 23 of the fan 22. The nozzle array 30 according to FIG. 1 has a funnel-shaped nozzle plate 32. The nozzle plate 32 is in this case configured to be circular. The nozzle plate 32 can also be formed by different geometrical shapes. Furthermore the nozzle plate 32 comprises a plurality of tubular nozzles 33. The tubular nozzles 33 are in this case arranged around a centre on an inner side of the nozzle plate 32. For example, the nozzles 33 also have a square or polygonal cross-sectional shape. In particular, the nozzles 33 can also be configured to be slot-shaped. The nozzles 33 can also have different cross-sectional shapes. Furthermore the nozzles 33 can be configured to be tapered towards one side. For example, the nozzle plate 32 has nozzles 33 with different cross-sectional shapes and/or nozzle lengths.

(16) In the following description, the nozzle circles 34a, 34b, 34c with identical or approximately identical properties are designated as nozzle circles 34.

(17) According to FIG. 1, a plurality of tubular nozzles 33 are arranged in a plurality of circular nozzle regions 35 on the inner side of the nozzle plate 32. The nozzle regions 35 can in this case also be configured differently. For example, the nozzle regions 35 can be configured to be star-shaped. In particular, the nozzle regions 35 can also be configured to be parallel to one another. The respective nozzles 33 can thus be arranged at different positions on the nozzle plate 32. As can be seen in FIG. 1, the nozzle regions 35 are formed by an inner nozzle circle 34a, a middle nozzle circle 34b and an outer nozzle circle 34c. The inner nozzle circle 34a is in this case arrange don the nozzle plate 32 adjacent to the intake duct 31 of the fan 22. The outer nozzle circle 34c is arranged on the nozzle plate 32 adjacent to the inner wall of the furnace housing 10. The middle nozzle circle 34b is arranged interposed between the inner nozzle circle 34a and the outer nozzle circle 34c on the nozzle plate 32. The nozzle circles 34 each have a spacing with respect to one another. In other words the nozzle circles 34 have different diameters.

(18) The inner side of the nozzle plate 32 is facing the receiving chamber 11. Thus, an outer side of the nozzle plate 32 is facing the pressure side of the fan 22. The nozzle plate 32 is configured to be funnel-shaped in such a manner that during the heat treatment of the furnace material the nozzles 33 of respectively one nozzle region are directed directly onto the furnace material. The respective nozzle circles 34 have nozzles 33 with an identical nozzle length. The nozzles 33 of the inner nozzle circle 34a are configured to be longer here than the nozzles 33 of the middle nozzle circle 34b. The nozzles 33 of the middle nozzle circle 34b are configured to be longer here than the nozzles of the outer nozzle circle 34c. In other words, the length of the nozzles 33 decreases starting from the centre of the nozzle plate 32 towards the outside towards the circumference of the nozzle plate 32. The lengths of the nozzles 33 of the nozzle circles 34 are configured in such a manner that the nozzles 33 in a side view of the nozzle array 30 not shown are configured to be vertically aligned with respect to one another with their free nozzle ends. In other words, the respective free ends of the nozzles 33 form a vertical alignment in the side view. The respective nozzle circles 34 can also comprise nozzles 33 with different nozzle lengths.

(19) According to FIG. 2, a perspective longitudinal sectional view of the housing part 10a according to FIG. 1 is shown. The furnace housing 10, the housing part 10a and the nozzle array 30 are implemented as described previously in FIG. 1. Likewise the arrangement of the nozzle array 30 and the fan 22 in the furnace housing 10 or housing part 10a according to FIG. 2 corresponds to the arrangement of the nozzle array 30 and the fan 22 as described previously in FIG. 1.

(20) As shown in FIG. 2, the housing part 10a has a device for convective heat transfer 20. The device for convective heat transfer 20 here comprises a heating device 21 and a fan 22. For example, the device for convective heat transfer 20 also comprises a plurality of heating devices 21 and/or a plurality of fans 22.

(21) In the housing part 10a according to FIG. 2, the fan 22 has a drive, in particular an electric motor which is arranged outside the furnace housing 10. The drive is directly coupled in a known manner to the fan 22. For example, the drive is connected by a belt drive or by a transmission to the fan 22. A rotor of the fan 22 is arranged in the furnace housing 10. According to FIG. 2, the fan 22 is formed by a radial fan 27. The radial fan 27 has a plurality of flow ducts 26 which are arranged on the pressure side 24 of the radial fan 27. The flow ducts 26 are in this case arranged radially circumferentially directly on the radial fan 27. For example, the flow ducts 26 are arranged completely radially circumferentially on the radial fan 27. The flow ducts 26 can also be arranged partially radially circumferentially on the radial fan 27.

(22) The radial fan 27 is assigned the heating device 21. The radial fan 27 can be assigned a plurality of heating devices 21. The heating device 21 is arranged concentrically to the radial fan 27 in a pressure duct 25 between the furnace housing 10 and the radial fan 27. The heating device 21 is in this case arranged directly downstream of the flow ducts 26 on the pressure side 24 of the radial fan 27 in the pressure duct 25.

(23) As can be seen in FIG. 2, the heating device 21 is formed by a heating line 28 for gaseous heating medium. The heating line 28 is here arranged to run around the radial fan 27 in the pressure duct. Furthermore, the heating line 28 is formed by a tube, in particular by a steel tube. The tube can be configured as a segment pipeline. The heating line 28 can also be formed by a hose, in particular a flexible steel hose. Furthermore, the heating line 28 can also be formed by a different design and from different materials. The heating line 28 is connected to an inlet not shown for an externally heated heat transfer medium, in particular that for gaseous heating medium, which heats the heating line 28. For example, hot air and/or hot protective gas and/or also hot exhaust gases can also be used as externally heated heat transfer medium.

(24) The pressure duct 25 is formed on the pressure side 24 of the radial fan 27. The pressure duct 25 is formed by a rear wall, a radially circumferential side wall and the nozzle array 30. Furthermore the pressure duct 25 is in fluid communication with the receiving chamber 11 through the nozzles 33 of the nozzle array 30. The pressure duct 25 is thus delimited by the nozzle plate 32 of the nozzle array 30 on the side facing the receiving chamber 11. The nozzle array 30 is therefore also arranged on the pressure side 24 of the fan 27.

(25) During operation of the batch furnace for the heat treatment of furnace material, the heat transfer medium is sucked in through the intake duct 31 of the nozzle array 30 from the receiving chamber 11 through the radial fan 27. A front side of the radial fan 27 thereby forms the suction side 23. The heat transfer medium is then deflected in a radial direction to the intake direction of the heat transfer medium by the radial fan 27 and accelerated. Finally the heat transfer medium is guided through the flow ducts 26 directly to the heating device 21. Advantageously the efficiency of the heat absorption of the heat transfer medium from the heating device is thereby increased. The heat transfer medium is thus heated in the pressure duct 25 by the heating device 21. Likewise the heat transfer medium is compressed by the radial fan 27 in the pressure duct 25. The heat transfer medium is then passed through the nozzles of the nozzle array 30 for convective heat transfer to the furnace material.

REFERENCE LIST

(26) 10 Furnace housing 11 Receiving chamber 12 Outlet for removal of burner gases 20 Device for convective heat transfer 21 Heating device 22 Fan 23 Suction side 24 Pressure side 25 Pressure duct 26 Flow duct 27 Radial fan 28 Heating line 30 Nozzle array 31 Intake duct 32 Nozzle plate 33 Nozzle 34 Nozzle circle 34a Inner nozzle circle 34b Middle nozzle circle 34c Outer nozzle circle 35 Nozzle region