Heating unit for heating a heat transfer fluid

Abstract

The invention relates to a heating unit (1) for heating a heat transfer fluid, comprising at least one heating tube (10, 11, 12) having a double-walled tube wall (13) through which the heat transfer fluid flows, and a burner (14) arranged inside the at least one heating tube (10, 11, 12), wherein the heating tube (10, 11, 12) is bent from a flat body into a tube body such that two longitudinal edges (L1, L2) of the heating tube (10, 11, 12) run parallel to each other. According to the invention, a receiving device (15) is provided, wherein the at least one heating tube (10, 11, 12) is suspended from the receiving device (15) by its longitudinal edges (L1, L2).

Description

[0001] The invention relates to a heating unit for heating a heat transfer fluid, comprising at least one heating tube having a double-walled tube wall through which the heat transfer fluid flows, and a burner arranged inside the at least one heating tube, wherein the heating tube is bent from a flat body to a tube body, such that two longitudinal edges of the heating tube run parallel to each other. STATE OF THE ART

[0002] From DE 10 2012 000 302 B4, a heating unit for heating a heat transfer fluid is known. Such heating units serve, for example, to provide a heated heat transfer fluid for laundry machines, such as mangles or the like, which are operated with thermal oil that should, for example, have a temperature of 150°C to 200°C. The tube wall is generally constructed from so-called pillow plates, which consist of two sheet metal elements tacked together, wherein at least one sheet metal element or both sheet metal elements are formed equally by an internal high-pressure forming process such that a cavity is created between the two sheet metal elements through which the heat transfer fluid can flow.The sheet metal elements are tacked together at approximately equal intervals across the surface using a multitude of tack points, for example by means of laser welding, so that after internal high-pressure forming the shape of a quilted pillow is created, which gives the pillow panels their name.

[0003] When the burner of the heating unit is operated and the walls of the heating tubes heat up accordingly, the heat can be transferred to the heat transfer fluid flowing through the tube walls. It is also known that several heating tubes are arranged concentrically within one another, and the hot gas from the burner flows around the heating tubes according to a gas flow pattern, for example, in a meandering direction. Consequently, the heat transfer fluid can be supplied to the heating tube(s) in a cold state, and after flowing through the heating tubes, the heat transfer fluid can be heated to, for example, 150°C to 200°C or even significantly higher.

[0004] In addition to numerous local weld points, pillow plates, which are typically rectangular in shape, feature a circumferential weld seam. This seam creates a flow-through inner space between the two sheet metal elements after the internal high-pressure forming process. This inner space is sealed at the edges, thus forming a closed system. The two longitudinal edges, which run parallel to each other after the plate has been formed into the tube body and are, for example, opposite each other, generally require further welding. This results in a concentration of weld seams and can lead to thermal stresses. Over extended operation of the heater unit, these stresses can damage the heater tubes, particularly in the area of ​​the multiple weld seams.Particularly when the heater tubes have a longitudinal weld, increased thermal stresses can occur, and if the tubes are attached to a flange or housing base, for example, via their lateral annular surfaces, an additional weld is often required. This, together with the sealing weld for joining the two sheets, can also lead to a weld seam accumulation, which is usually to be avoided. REVELATION OF THE INVENTION

[0005] The object of the invention is therefore to improve the technical design of a heater unit, in which, in particular, the longitudinal weld between the parallel longitudinal edges of the heater tube is avoided in order to join them. Furthermore, the heater unit with the heater tubes should be designed in such a way that the tube wall of the heater tubes can be accommodated with as little stress as possible.

[0006] This problem is solved starting from a heating unit according to the preamble of claim 1 in conjunction with the characterizing features. Advantageous embodiments of the invention are specified in the dependent claims.

[0007] The invention includes the technical teaching that a receiving device is provided, wherein the at least one heater tube is arranged to hang over the longitudinal edges of the receiving device.

[0008] The core concept of the invention is the complete avoidance of a longitudinal weld seam for welding the two opposing longitudinal edges of the tube wall bent from a flat body, by using a receiving device as part of the heater unit to hold the at least one heater tube or the several nested heater tubes suspended by their longitudinal edges. The suspended holding means that the heater tubes are positioned on the receiving device by gravity, and thus hang downwards, with the longitudinal edges being positively engaged in the receiving device, so that despite the freely suspended arrangement, a stable position of the heater tubes on or under the receiving device is ensured.

[0009] The receiving device is preferably arranged at a 12 o'clock position with respect to gravity, and thus "above" with respect to gravity. The longitudinal edges running towards each other on the receiving device may also be spaced apart, thus forming an opening in the otherwise sleeve-like heater tube. This opening may comprise, for example, up to 2%, 5%, 10%, and / or, in particular, up to 15% or 20% of the tube's circumference. The receiving device can be designed such that, after the longitudinal edges of the tube body are engaged, the hot gas generated by the burner cannot pass through this opening in the sleeve-like heater tube, as the receiving device closes the opening between the two spaced-apart longitudinal edges.Thus, the hot gas flows almost completely along the meandering path from the inside of the inner heater tube to the inside or even the outside of the outer heater tube between them.

[0010] The heating unit, for example, has a housing in which the receiving device is preferably arranged at the 12 o'clock position. Alternatively, the receiving device can also be arranged on a separate, i.e., peripheral, bracket, particularly if an outer heating tube simultaneously forms the outer surface or housing of the heating unit.

[0011] The heater unit can have a substantially circular cross-section; however, it is also conceivable that the heater unit forms at least oval or polygonal shaped tube bodies. Particularly when the heater tubes are suspended from the upper mounting device by gravity, the actual shape of the tube bodies may deviate from a circular cross-sectional shape and, for example, form an olive or teardrop shape.

[0012] Advantageously, the longitudinal edges feature an inwardly folded retaining section that engages in a receiving groove of the holding device. The retaining sections are folded, for example, at a 90° angle into the inside of the heater tubes, so that when the tube bodies are inserted, their end faces engage in the receiving groove. The weld seam required to create a fluid-tight weld between the two sheets forming the heater tubes can be positioned in front of the retaining section, so that the folding of the retaining section occurs outside the weld seam. Small folded retaining sections, for example, one or a few centimeters long, are sufficient for inserting the tube bodies, so that the receiving groove in the holding device is designed to complement the geometric shape of the retaining sections.The design of the receiving device may incorporate additional means to clamp or positively engage the holding sections of the pipe bodies in the receiving grooves, for example, by means of clamping strips or retaining strips that are clamped or screwed in place. However, the fundamental principle of the invention is to achieve the most stress-free and force-free possible mounting of the pipe bodies on the receiving device, thus allowing for longitudinal expansion of the pipe bodies, particularly when they undergo significant temperature changes.

[0013] Furthermore, it is conceivable that the receiving device has an anchor rail into which suspension elements are inserted and from which at least one heater tube is suspended. Alternatively, instead of multiple suspension elements distributed along the length of the tube body and thus the receiving device, a single suspension element can be designed to extend along the length of the heater tube and support it in a suspended position. The anchor rail advantageously has a length corresponding to the length of the heater tube. The length of the heater tube is defined by the length of its longitudinal edges and therefore also by the length of the heater tubes along their longitudinal axis. The anchor rail is usually also referred to as a so-called...Halfen rail is designated, and the anchor rail is formed by a profile element with a corresponding C-shaped grip, so that the opening side faces downwards and the hanging elements can include mushroom heads or T-nuts that are threaded into the profile rail.

[0014] It is possible to remove at least one heater tube, or several heater tubes, from the heater unit by pulling the suspension elements out of the anchor rail. Alternatively, individual heater tubes can be removed by pulling the retaining sections out of the receiving grooves on the longitudinal edges of the tube bodies. The heater tubes are removed along the longitudinal direction of the heater unit, where "longitudinal direction" refers to its length. The receiving grooves are preferably located on the underside of the suspension elements, and support plates are arranged on the suspension elements, so that the support plates and suspension elements have an inverted T-shape in cross-section. The receiving grooves for the retaining sections on the heater tubes are formed on the upper side of the T-beam.

[0015] The multiple heater tubes are preferably mounted concentrically on the receiving device, for example, by arranging several support plates at different heights on the at least one suspension element of the receiving device. Regarding the design of the heater tubes, it is advantageous if the double-walled tube wall, through which the heat transfer fluid flows, is formed with a heat exchanger plate that is itself permeable to the heat transfer fluid. Pillow plates, as described above, are known as an advantageous embodiment of such heat exchanger plates. These plates have a structure similar to a pillow or quilted blanket, with a multitude of weld points distributed over their surface. The two sheets are pressed together using an internal high-pressure forming process, allowing the heat transfer fluid to flow through the resulting interior space.This allows for direct heat transfer from the burner's hot gas to the heat transfer fluid. It has proven advantageous for the double-walled pipe, through which the heat transfer fluid flows, to be made of structural steel, particularly a metallic material other than stainless steel. Low-alloy steels are especially suitable due to their higher thermal conductivity.

[0016] To ensure that the same heat transfer fluid flows through the multiple nested heater tubes, either sequentially or in parallel, pipes are installed between them. The inner heater tube can have an inlet line, and the outer heater tube a drain line, through which cold heat transfer fluid is supplied and heated heat transfer fluid is discharged. These pipes are typically made of corrugated metal tubing, allowing them to be flexible and preventing them from exerting stress on the heater tubes. The inlet and drain lines can also be made of corrugated tubing.

[0017] Finally, a casing tube can form the housing of the heater unit, in which at least one heater tube is suspended. Alternatively, it is also conceivable that the casing tube itself is designed as a heater tube and, in particular, has a pillow plate formed into a tube body. The anchor rail can therefore be located on the inside of the casing tube forming the housing or on the outer heater tube. A further advantage is that the burner can be arranged on the casing tube, particularly via a flange. PREFERRED EXAMPLE OF THE INVENTION

[0018] Further measures improving the invention are described in more detail below, together with a description of a preferred embodiment of the invention, with reference to the figures. The figures show: Fig. 1 a cross-sectional view through the heater unit with a housing-forming casing tube and three heater tubes arranged concentrically inside one another, Fig. 2 a cross-sectional view of the heater unit according to Fig. 1 with a cross-sectional profile to which the longitudinal direction of the heater unit is perpendicular, Fig. 3 a detailed view of the recording device with an example of a heater pipe suspended from it, Fig. 4 an exemplary design of the receiving device with an anchor rail and, by way of example, three hanging elements and Fig. 5 another embodiment of a heater unit with three heater tubes, wherein the outer heater tube also forms the casing tube and thus a housing.

[0019] Fig. Figure 1 shows a cross-sectional view of a heater unit 1, with the section plane such that the longitudinal direction 20 of the heater unit 1 lies in the section plane. The heater unit 1 has, by way of example, three heater tubes 10, 11, 12, with heater tube 10 forming an outer heater tube, heater tube 11 a middle heater tube, and heater tube 12 an inner heater tube. A burner 14 is located centrally in the inner heater tube 12, through which hot gas is injected into the inner heater tube 12. The indicated arrows describe the direction of hot gas flow, from which it follows that the hot gas flows around the heater tubes 10, 11, 12 in a meandering pattern, so that a heat transfer fluid flowing through the heater tubes 10, 11, 12 can be heated. The supply and removal of the heat transfer fluid are not shown in detail in this view.However, the heater tubes 10, 11, 12 are equipped with tube walls 13 formed by pillow plates, through which the heat transfer fluid itself can flow. A sheathing tube 22 is arranged externally around the heater tubes 10, 11, 12, forming a housing for the three-stage heater unit 1.

[0020] The burner 14 is mounted via a flange 23, which is connected to the casing tube 22. The connection can be designed such that a gas outlet is formed via an annular cross-section, as indicated by the arrows. On the right side, the casing tube 22 is closed at the bottom by a housing base 24.

[0021] A receiving device 15 serves to hold the heater tubes 10, 11, 12, wherein the heater tubes 10, 11, 12 are suspended from the receiving device 15. For this purpose, the receiving device 15 has an anchor rail 18, also called a Halfen rail, which is arranged at a 12 o'clock position, i.e., on the upper side, on the inside of the casing tube 22. Several suspension elements 19 are suspended from the anchor rail 18, on which the respective heater tube 10, 11, 12 is arranged. Due to the triple arrangement of the heater tubes 10, 11, 12, several successive suspension elements 19 are provided, which receive the respective heater tube 10, 11, 12 via intermediately arranged support plates 25.

[0022] By using the anchor rail 18, the suspension elements 19 can be moved longitudinally 20, allowing each of the heater tubes 10, 11, 12 to be removed individually and independently of the other heater tubes 10, 11, 12 in the longitudinal direction 20. The heater tubes 10, 11, 12 can also be removed from the support plates 25, so that they can be inserted into the casing 22 during the assembly of the heater unit 1 and removed again as needed. The design of the receiving device 15 with the anchor rail 18 and the suspension elements 19 allows the heater tubes 10, 11, 12, with their respective tube walls 13, to be suspended in the casing 22 without stress. The detailed design of the receiving device 15 is shown below. Fig. 2.

[0023] Fig. Figure 2 shows a cross-section of the heater unit 1 with a cross-sectional profile perpendicular to the longitudinal direction 20 and therefore perpendicular to the cross-sectional profile according to Fig. 1. The figure shows the three heater tubes 10, 11, 12, which are arranged concentrically around the longitudinal direction 20 and suspended from the receiving device 15. The receiving device 15 has an anchor rail 18 for this purpose and, in the figure, a suspension element 19, shown simply. Several support plates 25 are arranged on the suspension element 19 in a successive sequence, so that the heater tubes 10, 11, 12 can be arranged concentrically to each other on the receiving device 15.

[0024] The illustration further shows pipes 21 for the inlet and outlet of the heat transfer fluid, with additional pipes 21 between the individual heater tubes 10, 11, 12. Thus, when the heat transfer fluid flows in via the support-like pipe 21 shown on the left, the heater tubes 10, 11, 12 can flow through sequentially, first through the cooler outer heater tube 10, then through the warmer central heater tube 11, and finally through the innermost heater tube 12, which is the hottest and directly surrounds the burner flame of the burner 14. The heat transfer fluid is then carried out from the inner heater tube 12 via the pipe 21, which is shown as a support on the right.

[0025] Fig. Figure 3 shows an enlarged view of the receiving device 15 with the anchor rail 18, the suspension element 19, and the support plate 25. Receipt grooves 17 are shown on the upper side of the support plate 25, on both sides of the suspension element 19. Inwardly bent or folded retaining sections 16 are inserted into these grooves. These retaining sections 16 are formed at their ends on the longitudinal edges L1, L2 of the heater tube 10. The retaining sections 16 thus fit snugly into the receiving recesses 17 at the longitudinal edges L1, L2 and are held by the support plate 25. The heater tube 10 is therefore suspended from the receiving device 15 without any force being applied.

[0026] Fig. Figure 4 shows, by way of example, the receiving device 15 as anchor rail 18, with associated suspension elements 19, wherein the anchor rail 18 extends in the longitudinal direction 20, and the anchor rail 18 is also referred to as the so-called Halfen rail.

[0027] Finally, it shows Fig.Figure 5 shows a further embodiment of a heater unit 1 with three heater tubes 10, 11, 12 and a receiving device 15 comprising an anchor rail 18 and several suspension elements 19. In this embodiment, the receiving device 15 is attached to the inside of the heater tube 10 by means of the anchor rail 18, with this outer heater tube 10 simultaneously forming the outer casing 22. The flange 23 for receiving the burner 14 is connected to the outer casing 22. The middle heater tube 11 is connected to a housing base 24 on the right side, with the heater tubes 10, 11, 12 being nested within each other in such a way that the hot gas flow from the burner 14 meanders through the spaces between the heater tubes 10, 11, 12. In this way, the pipe walls 13 of the heater pipes 10, 11, 12, through which the heat transfer fluid flows, can be heated. Reference symbol list: 1 heater unit 10 heater tube 11 Heater tube 12 heater tube 13 Pipe wall 14 burners 15 Reception facility 16 Stop section 17 recordings 18 Anchor rail 19 hanging elements 20 Longitudinal direction 21 Pipeline 22 Sheathing tube 23 flange 24 Case base 25 Carrier plate L1 Long edge L2 Long edge QUOTES INCLUDED IN THE DESCRIPTION

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

[0000] DE 10 2012 000 302 B4

[0002]

Claims

[1] Heater unit (1) for heating a heat transfer fluid, comprising at least one heater tube (10, 11, 12) having a double-walled tube wall (13) through which the heat transfer fluid flows, and comprising a burner (14) which is arranged inside the at least one heater tube (10, 11, 12), wherein the heater tube (10, 11, 12) is bent from a flat body to a tube body such that two longitudinal edges (L1, L2) of the heater tube (10, 11, 12) run parallel to each other, characterized by , that a receiving device (15) is provided, wherein the at least one heater tube (10, 11, 12) is arranged to hang over the longitudinal edges (L1, L2) on the receiving device (15). [2] Heater unit (1) according to claim 1, characterized by , that the longitudinal edges (L1, L2) have an inwardly folded retaining section (16) which engages in a receiving groove (17) of the receiving device (15). [3] Heater unit (1) according to claim 1 or 2, characterized by, that the receiving device (15) has an anchor rail (18) into which suspension elements (19) are inserted and on which at least one heater tube (10, 11, 12) is suspended. [4] Heater unit (1) according to claim 3, characterized by , that the anchor rail (18) is arranged in such a way that the at least one heater tube (10, 11, 12) is movable in its longitudinal direction (20) and in particular can be removed from the heater unit (1). [5] Heater unit (1) according to any one of the preceding claims, characterized by , that several heater tubes (10, 11, 12) are mounted concentrically inside one another on the receiving device (15). [6] Heater unit (1) according to any of the preceding claims, characterized by , that the double-walled pipe wall (13) through which the heat transfer fluid flows is formed with a heat exchanger plate which is constructed as a so-called pillow plate. [7] Heater unit (1) according to any of the preceding claims, characterized by , that the double-walled pipe wall (13) through which the heat transfer fluid flows is made of structural steel and / or is free of stainless steel. [8] Heater unit (1) according to any of the preceding claims, characterized by , that several nested heater tubes (10, 11, 12) are connected to each other via pipes (21). [9] Heater unit (1) according to any one of the preceding claims, characterized by , that a sheath tube (22) forms a housing of the heater unit (1) in which the at least one heater tube (10, 11, 12) is suspended. [10] Heater unit (1) according to any one of claims 6 to 9, characterized by that the anchor rail (18) is arranged on the inside of the sheathing tube (22) and / or wherein the sheathing tube (22) also forms a heater tube (10). [11] Heater unit (1) according to claim 9 or 10, characterized by, that the burner (14) is arranged on the casing tube (22) by means of a flange (23).

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