Device and method for convectively cooling hot rolled products

Abstract

The invention relates to a device (1) and a method for convectively cooling hot steel products, in particular hot rolled products (5) in a rolling mill. The device (1) comprises at least one cooling bed which comprises at least one first and at least one second vertically extending cooling bed plane (2, 3), wherein the cooling bed planes (2, 3) are formed by at least one transport device which has at least one vertical conveyor means (4) that is designed to receive a rolled product (5) from a first horizontal conveyor means (6), raise the rolled product via a first vertical conveyor section, and deposit the rolled product on a second horizontal conveyor means (4) via a second vertical conveyor section. The circulating transport device is arranged in a substantially closed housing (7) which comprises means for producing a flow of air and / or gas, as a cooling medium, through the volume enclosed by the housing (7) and means for recovering energy from the air flow and / or gas flow which is guided through the housing and which is loaded with heat of the rolled product.

Description

[0001] Device and method for convective cooling of hot rolled stock

[0002] The invention relates to a device and a method for convective

[0003] Cooling of hot steel products, especially hot rolled stock.

[0004] In various processes for the production of steel products and pre-products, such as billets, slabs, beam blanks, I-beams, double I-beams, I-profiles, rails, pipes, bars, plates, steel strip, wire, or the like, the steel product is heated to temperatures sometimes exceeding 1000°C before forming. After the forming steps have been completed, the pre-products or final products are then cooled on an open cooling bed. Air flows around the steel products in the bed as a cooling medium. Conventional cooling beds are designed so that the individual steel products are transported along a cooling section. For example, in chain or rake cooling beds, these products are removed from a roller conveyor using a suitably designed horizontal conveyor, transported along a horizontal cooling bed plane, and then individually transferred to a second roller conveyor arranged parallel to the first roller conveyor.

[0005] CN 101797592 A discloses a cooling bed in which coils and steel plates are conveyed vertically upwards and downwards on shelves arranged vertically one above the other, in two passes. To utilize some of the thermal energy of the products to be cooled, CN 101797592 A proposes providing heat exchangers in the side walls of the conveyor system arranged beneath a steelworks floor, through which a cooling medium flows.

[0006] Another device for controlled air cooling and heat recovery for rolled stock is known, for example, from DD 231 746 A1. The aim of the invention described therein is to create a device that accelerates or retards the cooling rate for different types of rolled stock and utilizes the heat released for energy recovery. This is achieved by providing several angle-adjustable heat exchangers directly below or next to the cooling bed on the outlet side.

[0007] The existing solutions suffer from the disadvantage that both cooling and heat recovery are ineffective. Furthermore, the conventional, flat-area chain or rake cooling beds require a large amount of space.

[0008] For example, the arrangement of heat exchangers directly next to the cooling bed, as described in DD 231 746 A1, has the disadvantage that a relatively large amount of energy is dissipated unused into the environment.

[0009] The invention is therefore based on the object of providing a device for the convective cooling of hot steel products, in particular of hot rolled stock in a rolling mill, which is characterized by a small space requirement and by a high effective energy recovery.

[0010] The object is achieved by providing a device having the features of claim 1 and by providing a method for convective cooling of hot steel products having the features of claim 14.

[0011] Advantageous embodiments of the invention result from the features of the subclaims.

[0012] According to one aspect of the invention, a device for the collective cooling of hot steel products, in particular hot rolled stock in a rolling mill, is provided, which comprises at least one cooling bed that comprises at least a first and a second vertically extending cooling bed level, wherein the cooling bed levels are formed by at least one transport device that has at least one vertical conveyor, which is designed to receive a rolled stock from a first horizontal conveyor, to lift it via a first vertical conveyor line and to deposit it again via a second vertical conveyor line onto a second horizontal conveyor, wherein the at least one transport device is arranged in a substantially closed housing,which comprises means for flowing air and / or gas as a cooling medium through the volume enclosed by the housing and further comprises means for energy recovery from the air flow and / or gas flow charged with the heat of the rolling stock, which is guided through the housing.

[0013] A "substantially" closed enclosure within the meaning of the present invention means that the enclosure is not hermetically sealed. A closed enclosure within the meaning of the present invention includes an enclosure that has air intake and exhaust openings, as well as openings for the introduction and discharge of material and for personnel access.

[0014] The housing of the device according to the invention preferably forms a volume that is 70%, more preferably 80% and particularly preferably at least 90% enclosed.

[0015] According to the invention, the energy recovery means can be designed such that both thermal energy and the flow energy of the cooling medium are recovered. Air at ambient temperature is provided as the cooling medium. For example, several endlessly rotating chains can be provided as the circulating endless conveyor. These chains have horizontally extending carriers. These carriers lift the rolled stock from a horizontal conveyor, for example, a roller table, in the manner of a rake cooling bed. After circulating the rolled stock over an upper deflection point of the vertical conveyor, they deposit it again on another horizontal conveyor.

[0016] Preferably, the transport device is designed as a circulating transport device with at least one vertically circulating endless conveyor.

[0017] Alternatively, two conveyors can be provided, each transporting the rolled material upwards and downwards.

[0018] At least one rake can be provided as a conveying means, which gradually raises and lowers the rolling stock and places it on consoles or fixed rakes provided for this purpose.

[0019] The circulating endless conveyor can be designed as a conveyor constructed according to the paternoster principle. The endless conveyor can form stacked compartments, each arranged one above the other in at least two trains on vertically extending circulating chains, which are, for example, motor-driven and circulate endlessly over upper and lower deflection rollers. For this purpose, the carriers for the rolled material can each be attached to an articulated gear, so that the carriers can be guided around an upper and lower dead center of the endless conveyor while maintaining a horizontal alignment.

[0020] In particular, the fact that the circulating transport device is arranged in a substantially closed housing ensures that the cooling medium flowing through the housing is particularly effectively charged with the heat of the rolled stock. By arranging the cooling bed over vertically extending cooling bed levels formed by the vertical conveyor line, the device according to the invention advantageously has a particularly small footprint. The enclosed volume can be minimized, thus avoiding the dissipation of energy to the environment as much as possible.

[0021] A further advantage of the device according to the invention is that the trains or strands formed by the vertically rotating endless conveyor can be balanced with respect to the mass to be lifted and lowered, so that essentially only the friction losses for the circulation of the conveyor need to be used as transport energy. This allows cooling with the lowest possible energy consumption for conveying the rolled stock. Electric drives are preferably used as drives for the endless conveyor, which can be operated as generators when the device is running empty.

[0022] In a particularly preferred embodiment of the invention, the enclosure has at least one lower air supply opening and at least one upper air exhaust opening, and the enclosure is designed such that a preferably natural convection flow can be generated within the enclosure via an effective differential pressure in the enclosure. A natural convection flow within the meaning of the present invention is also referred to as natural draft, i.e. the flow of the cooling medium can be maintained in the manner of a chimney effect without a fan. The convection flow is generated in particular by the density difference between the heat-laden cooling medium within the closed volume and the ambient air outside the enclosure.

[0023] By appropriately designing the enclosure, the heat absorbed by the cooling medium, as well as its kinetic energy, can be utilized at a few locations near one or more of the device's upper exhaust air openings. This energy can be utilized by heat exchangers and / or turbines. The latter utilize the kinetic energy of the cooling medium. The thermal energy can also be used, for example, to preheat air for furnaces provided in the rolling mill.

[0024] A preferred variant of the device according to the invention is characterized by means for controlling and / or preferably temperature-controlled regulation of the air and / or gas supply or discharge.

[0025] The device can, for example, comprise sensors for detecting the temperature and / or volume flow of the cooling medium, as well as sensors for detecting the temperature of the rolling stock to be cooled at at least one point along the circulation path, preferably at multiple points along the circulation path of the rolling stock on the circulating transport device. The temperature of the rolling stock can be detected, for example, by infrared sensors that can non-contact capture a thermal image and / or a thermal profile of the vertically extending cooling bed levels. The air supply and / or exhaust can then be controlled, for example, depending on the temperature of the rolling stock as a reference variable, for example via flaps or diaphragms that can be controlled via actuators.

[0026] According to the invention, means for accelerating the flow velocity of the cooling medium can also be provided, for example in the form of nozzles in the region of exhaust air openings of the housing.

[0027] In addition, the flow of the cooling medium can be supported by means of a fan.

[0028] However, the device according to the invention is preferably designed so that the volume flow of the cooling medium can be maintained even without a fan. An acceleration of the flow velocity of the cooling medium can be achieved, for example, by exhaust air ducts that have a cross-section tapered like a Venturi nozzle.

[0029] Additionally or alternatively, the housing may have a cross-section that tapers downstream of the cooling medium, preferably upwards.

[0030] Advantageously, at least one exhaust air duct and / or exhaust gas duct is provided, which causes an increase in the flow velocity of the exhaust air and / or the exhaust gases by at least a partial cross-sectional narrowing.

[0031] It is particularly advantageous if the enclosure is thermally insulated. This maintains the density difference between the volume inside the enclosure and the ambient air, thus driving natural draft, and also reduces energy loss.

[0032] Preferably, flaps or panels controlled by actuators are provided in a surrounding wall of the enclosure to control the air and / or gas supply and / or discharge.

[0033] In an advantageous embodiment of the device according to the invention, it is provided that it comprises at least a first and a second cooling area which are divided vertically, wherein the first vertical conveying path extends within a first cooling area and the second vertical conveying path extends within a second cooling area.

[0034] Dividing the cooling area into at least two zones has the advantage that various parameters such as air flow and air volume can be controlled separately. If multiple cooling zones are provided, several specific exhaust air openings can also be provided to avoid disruption of the individual airflows. For example, flaps integrated into a wall of the enclosure can be designed in such a way that the cooling effect can be specifically adjusted across the height of the cooling zone using Venturi effects, thus enabling targeted cooling of the rolled stock.

[0035] The first and second cooling zones are expediently divided spatially, structurally, and / or fluidically. A flow-dynamic division can be achieved, for example, using an air curtain.

[0036] The cooling areas can, for example, be formed by an air curtain extending vertically in a central longitudinal plane of the volume enclosed by the enclosure.

[0037] Within the enclosure, for example, devices for emergency emptying of material can be provided on both sides of the circulating conveyor. For example, forklifts that can be operated automatically can be installed on vertically movable maintenance platforms.

[0038] In addition, the device can include aerosol cooling, which further increases the cooling performance.

[0039] Below the cooling bed, i.e. outside the volume enclosed by the enclosure, access to a conveyor drive for inspection and maintenance work can be provided without operating personnel having to enter the enclosure volume.

[0040] A further aspect of the invention relates to a method for the convective cooling of hot steel products, in particular of hot rolled stock in a rolling mill, wherein the method comprises vertical conveyance of the rolled stock over at least one first and at least one second vertically extending cooling bed level within a substantially closed housing, further comprising a flow through the volume enclosed by the housing with air and / or gas as a cooling medium and the generation and maintenance of a preferably natural convection flow within the housing via an effective pressure difference height of the housing and the step of energy recovery from the air flow and / or gas flow charged with the heat of the rolled stock that is discharged from the housing.

[0041] Particularly preferably, the method comprises controlling and / or regulating the convection flow, preferably temperature-controlled control of the convection flow. The temperature-controlled control of the convection flow can be achieved using sensors that generate a thermal image of the cooling bed levels. The thermal images can be evaluated automatically, whereby a higher-level computer-implemented cooling model can be used to adjust the cooling rate across the height of the cooling beds in relation to a specific rolled stock, thus enabling targeted heat treatment.

[0042] The method and device according to the invention enable effective energy recovery as well as targeted adjustment of the cooling rates of the rolling stock by controlling the supply and exhaust air, air flow and the amount of cooling medium.

[0043] The outer shell of the enclosure can, for example, also be at least partially an outer wall of the hall surrounding the rolling mill, thus saving corresponding construction costs.

[0044] The device according to the invention has the advantage of a reduced footprint for the layout of the plant. The drag length of the rolled stock is generated by the height, not the overall length, of the cooling bed.

[0045] Temperature sensors at each transport location and in the various cooling areas provide additional information with which cooling curves can be set specifically.

[0046] The invention is explained below using an embodiment shown in the drawings.

[0047] They show:

[0048] Figure 1 is a sectional view through the device according to the invention,

[0049] Figure 2 is a perspective view of the device according to Figure 1,

[0050] Figure 3 is a perspective view of an endless conveyor in partial section along the section line AA in Figure 5, which forms part of the cooling bed, and

[0051] Figure 4 is a front view of the endless conveyor shown in Figure 3 and

[0052] Figure 5 is a front view of the endless conveyor according to Figures 3 and 4.

[0053] The device 1 shown in Figure 1 comprises a cooling bed arranged in a substantially closed housing 7, which forms two approximately vertically extending cooling bed levels 2, 3.

[0054] The cooling bed levels 2, 3 are formed by the vertical transport of a rolled stock 5, for example in the form of rolled profiles, with several endless conveyors 4, each running vertically around a horizontal conveying direction in a line parallel to the plane of the mill floor 10, which endless conveyors have several endlessly circulating conveyor chains 40 and rake-shaped carriers 41 arranged on the conveyor chains, which take over the rolled stock 5 from a first roller table 6 and convey it upwards via the first vertically extending cooling bed level 2. Via the first roller table 6, the rolled stock 5 is transported horizontally in the longitudinal direction in the pass line parallel to the plane of a mill floor 10 into the device 1 and, if necessary, displaced transversely in the direction of the endless conveyor 4 at the level of an endless conveyor 4.Carriers 41 of an endless conveyor 4 engage underneath the rolling stock 5 and lift it vertically upwards in the first cooling bed level 2 via a first vertical conveyor section.

[0055] The conveyor chains 40 of the endless conveyors 4 are each guided over upper and lower deflection rollers 8, which are held at an adjustable distance from one another, for example by means of a tensioning device 9. The carriers 41 are designed as rake tines and engage underneath the rolled stock 5 located on the first roller table 6, conveying it vertically upwards via the first cooling bed level 2 and downwards again via the second cooling bed level 3, where the rolled stock 5 is deposited again on a second roller table 12 and conveyed horizontally out of the device or housing 7 in the pass line parallel to the level of the mill floor 10.For this purpose, the carriers 41 can each be fastened to a linkage (not shown), which ensures a horizontal alignment of the carriers over the entire conveying path, i.e. also during a revolution over a top dead center of the conveyor chain 40, so that the conveying takes place in the same position all the way around according to the paternoster principle.

[0056] The enclosure 7 is designed as a vertically extending, closed housing except for openings for the supply and removal of material and a cooling medium. The housing has air inlets 11 approximately at the level of the mill floor 10 and exhaust air inlets 13 in an upper roof area. The exhaust air inlets are provided in funnel-shaped, tapered gable roof domes 14 of the enclosure, which accelerate the exhaust air flow. The gable roof domes also spatially separate the volume enclosed by the enclosure 7 into a first and second cooling zone 18, 19. The exhaust air, loaded with the heat from the rolled stock, is fed to exhaust air heat exchangers 16 via exhaust air ducts 15 for heat recovery. The housing 7 is designed in such a way that a chimney draught develops within it via the heat introduced by the rolling stock 5, which drives the cooling medium in the form of ambient air (at normal temperature under atmospheric pressure).

[0057] Vertically movable maintenance platforms 17 are provided on both sides of the cooling bed levels 2, 3. These platforms can accommodate, for example, lifting devices and / or hoists that can be operated automatically and enable unmanned, automated removal of rolling stock 5 in the event of a malfunction.

[0058] In the supply air openings 11 and / or the exhaust air openings 13 and / or in the exhaust air ducts, unspecified flaps, panels or valves are provided which can be actuated by actuators and with which the flow of cooling air through the enclosure can be regulated.

[0059] List of reference symbols

[0060] 1 device

[0061] 2 first cooling bed level

[0062] 3 second cooling bed level

[0063] 4 endless conveyors

[0064] 40 conveyor chains

[0065] 41 drivers

[0066] 5 Rolled goods

[0067] 6 first roller conveyor

[0068] 7 Enclosure

[0069] 8 pulleys

[0070] 9 Clamping device

[0071] 10 Hut corridor

[0072] 11 air supply openings

[0073] 12 second roller conveyor

[0074] 13 exhaust air openings

[0075] 14 gable roof domes

[0076] 15 exhaust air ducts

[0077] 16 exhaust air heat exchangers

[0078] 17 maintenance platforms

[0079] 18 first cooling area

[0080] 19 second cooling area

Claims

Patent claims 1. Device (1) for the convective cooling of hot steel products, in particular of hot rolled stock (5) in a rolling mill, comprising at least one cooling bed that comprises at least a first and at least one second vertically extending cooling bed level (2, 3), wherein the cooling bed levels (2, 3) are formed by at least one transport device that has at least one vertical conveyor (4) designed to receive a rolled stock (5) from a first horizontal conveyor (6), to lift it via a first vertical conveyor line and to deposit it again via a second vertical conveyor line onto a second horizontal conveyor (12), wherein the at least one transport device is arranged in a substantially closed housing (7),the means for flowing air and / or gas as a cooling medium through the volume enclosed by the housing (7) and further comprising means for energy recovery from the air flow and / or gas flow charged with the heat of the rolling stock, which is guided through the housing.

2. Device according to claim 1, characterized in that the transport device is designed as a circulating transport device with at least one vertically rotating endless conveyor means (4).

3. Device according to claim 1 or 2, characterized in that the housing has at least one lower supply air opening (11) and at least one upper exhaust air opening (13) and that the housing (7) is designed such that a preferably natural convection flow can be generated within the housing (7) via an effective differential pressure of the housing (7).

4. Device according to one of claims 1 to 3, characterized by means for controlling and / or preferably temperature-controlled regulation of the air and / or gas supply and / or discharge.

5. Device according to one of claims 1 to 4, characterized in that the device comprises sensors for detecting the temperature and / or volume flow of the cooling medium and sensors for detecting the temperature of the rolling stock (5) to be cooled at at least one point of circulation, preferably at several points of circulation of the rolling stock (5) on the circulating transport device.

6. Device according to one of claims 1 to 5, characterized by means for accelerating the flow velocity of the cooling medium.

7. Device according to one of claims 1 to 6, characterized in that the housing (7) has at least one cross-section tapering downstream of the cooling medium.

8. Device according to one of claims 1 to 7, characterized in that at least one exhaust air duct and / or exhaust gas duct is provided, which causes an increase in the flow velocity of the exhaust air and / or the exhaust gas by an at least partial cross-sectional narrowing.

9. Device according to one of claims 1 to 8, characterized by at least one fan to support natural convection of the cooling medium.

10. Device according to one of claims 1 to 9, characterized in that the housing (7) is thermally insulated.

11. Device according to one of claims 1 to 10, characterized in that flaps or diaphragms controlled by actuators are provided to control the air and / or gas supply and / or discharge.

12. Device according to one of claims 1 to 11, comprising at least a first and a second cooling area which are divided vertically, wherein the first vertical conveyor line extends within a first cooling area (18) and the second vertical conveyor line extends within a second cooling area (19).

13. Device according to claim 12, characterized in that the first and the second cooling area (18, 19) are spatially structurally and / or fluidically divided.

14. A method for the convective cooling of hot steel products, in particular of hot rolled stock in a rolling mill, comprising vertically conveying the rolled stock over at least one first and at least one second vertically extending cooling bed level within a substantially closed housing, flowing air and / or gas as a cooling medium through the volume enclosed by the housing, generating and maintaining a preferably natural convection flow within the housing via an effective differential pressure of the housing and further comprising the step of recovering energy from the air flow and / or gas flow charged with the heat of the rolled stock which is discharged from the housing.

15. Method according to claim 14, characterized by a control and / or, preferably temperature-controlled, regulation of the convection flow.

16. A method according to one of claims 14 or 15, characterized in that the natural convection flow (natural draft) is supported by at least one fan.

17. A method according to one of claims 14 to 16, characterized by the Use of a device according to one of claims 1 to 13.

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