A double-wall heat exchanger plate and its manufacturing method

Abstract

The present invention relates to the technical field of plate heat exchangers, and particularly to a double-wall heat exchanger plate and a manufacturing method thereof. The heat exchanger plate includes a plate body composed of plate A and plate B. Through holes for fluid to pass through the plate body are provided on the plate body. An annular brazing strip is arranged around the through holes. A filling layer in close contact with both of them is filled between plate A and plate B. The materials of plate A and plate B are stainless steel, and the material of the filling layer is tin. The heat exchanger plate of the present invention is manufactured through processes such as stamping, brazing, and tin dipping. The heat exchanger plate of the present invention has higher heat exchange efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of plate heat exchangers, and in particular to a double-wall heat exchanger plate and a manufacturing method thereof. Background Art

[0002] A double-wall plate heat exchanger is a heat exchanger that can prevent reactions or mutual contamination from occurring when the heat exchange medium comes into contact after the heat exchange plates of the heat exchanger leak. Its plates are composed of plate A and plate B that are closely attached together. Even if one of plate A and plate B has cracks or perforations, the fluids flowing on both sides of the plates in the plate heat exchanger will not mix together. In this case, the fluid leaking through the cracks or perforations will enter the gap between plate A and plate B and finally flow to the edges of both, so that the leakage can be detected and measures can be taken.

[0003] The patent with the patent number US4976313 records a double-wall structure of a plate heat exchanger. The alternating plates 6 and the intermediate plate 5 that form the double-wall unit are mutually extruded through the plastic metal deformation of the plates, so that the ridges of the corrugations on the front surface of one plate will fall into the corresponding valleys of the corrugations on the opposite back surface of the adjacent plate, and vice versa, thereby establishing surface-to-surface contact between the plates, and further improving the heat exchange efficiency between the alternating plates 6 and the intermediate plate 5, making the plate heat exchanger using this kind of double-wall unit have higher heat exchange efficiency. However, when the alternating plates 6 and the intermediate plate 5 are made of stainless steel, although they are easy to bend, their plastic deformation ability is not very good. Restricted by the surface roughness (the surface is uneven on a smaller scale, and when the protruding parts of the two come into contact, it will prevent the sunken parts from coming into contact) and actual conditions, the alternating plates 6 and the intermediate plate 5 cannot be fully attached, and the attachment rate can be further improved. Summary of the Invention

[0004] The technical problem to be solved by the present invention is, aiming at the above-mentioned existing technical deficiencies, to provide a double-wall heat exchanger plate and a manufacturing method thereof.

[0005] To solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A double-wall heat exchanger plate includes a plate body composed of plate A and plate B. Through holes for fluids to pass through the plate body are provided on the plate body. An annular brazing belt is provided around the through holes. A filling layer that is closely attached to both is filled between plate A and plate B. The materials of plate A and plate B are stainless steel, and the material of the filling layer is tin.

[0007] To further optimize the technical solution, a nickel layer is provided on the inner side surface of one of plate A and plate B. The filling layer is brazed together with the nickel layer, and the filling layer is not brazed together with plate A and plate B without the nickel layer.

[0008] To further optimize this technical solution, nickel layers are provided on the inner sides of both the sheet A and the sheet B. The nickel layers are narrow strips. The nickel layer on the sheet A partially overlaps with the nickel layer on the sheet B. The part of the filling layer that is not brazed to the nickel layer communicates with the outside.

[0009] The manufacturing method of the double-wall heat exchanger sheet is as follows:

[0010] The first step: Stamping the sheet A and the sheet B into shape.

[0011] The second step: Overlapping the sheet A and the sheet B obtained in the first step and performing brazing to form an annular brazing belt around the through holes to obtain a plate body.

[0012] The third step: Filling molten tin into the gap between the sheet A and the sheet B of the plate body obtained in the second step, and then cooling to solidify the molten tin into a filling layer to obtain the double-wall heat exchanger sheet.

[0013] To further optimize this technical solution, when nickel layers are provided on the sheet A and the sheet B, it is also necessary to coat nickel layers on both of them after they are pressed into shape, or coat nickel layers on the stainless steel used for pressing both of them.

[0014] Compared with the prior art, the present invention has the following advantages: 1. A filling layer that is in close contact with both is filled between the sheet A and the sheet B. Since the molten tin is filled between the sheet A and the sheet B when it is in a liquid state, its fluidity is very good, and it can fill most of the gaps, so that the filling layer is in very good contact with the sheet A and the sheet B, and the heat exchange efficiency is higher; 2. A nickel layer is provided on the inner side of one of the sheet A and the sheet B, and the filling layer can be combined with the nickel layer, further improving the heat exchange efficiency between the two. The leaked fluid can flow out from between the side without the nickel layer of the two and the filling layer; 3. The narrow strip-shaped nickel layer on the sheet A and the narrow strip-shaped nickel layer on the sheet B are staggered from each other and partially overlap at the edges. The filling layer at the overlapping part is combined with the sheet A and the sheet B at this place at the same time, making it more difficult for gaps to appear between the sheet A and the sheet B under the action of other factors, and it can avoid the decrease in heat exchange efficiency caused by the appearance of gaps between the two to a certain extent. Description of the Drawings

[0015] Figure 1 It is the front view of the sheet in Embodiment 1.

[0016] Figure 2 It is the top view of the sheet in Embodiment 1.

[0017] Figure 3 It is the structural schematic diagram of the nickel layer coated on the sheet A in Embodiment 2.

[0018] Figure 4 Schematic structural diagram of nickel layer plating on sheet B in Example 2.

[0019] Figure 5 Front view of the sheet in Example 3.

[0020] In the figure: 1, sheet A; 2, sheet B; 3, filling layer; 4, through hole. Specific embodiments

[0021] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention.

[0022] Example 1

[0023] A double-wall heat exchanger sheet, as Figure 1-2 shown, includes a plate body composed of sheet A1 and sheet B2. A through hole 4 for fluid to pass through the plate body is provided on the plate body. An annular brazing belt is provided around the through hole 4. The common plate body is rectangular, and through holes 4 are respectively provided at its four corners. A corrugated pattern or ridges and valleys are also provided in the middle of the plate body. Grooves or planes for placing sealing rings are also provided on the plate body. A filling layer 3 that is in close contact with both is filled between the sheet A1 and the sheet B2. The materials of the sheet A1 and the sheet B2 are stainless steel, and the grades are generally 304 or 316. The material of the filling layer 3 is tin, and the filling layer 3 is not combined with the sheet A1 and the sheet B2.

[0024] The manufacturing method of this double-wall heat exchanger sheet is as follows:

[0025] The first step: Stamp the sheet A1 and the sheet B2 into shape, and the same stamping method as the patent mentioned in the background technology can be used;

[0026] The second step: Overlap the sheet A1 and the sheet B2 obtained in the first step and perform brazing. Before brazing, the surfaces of both need to be cleaned. Copper-based brazing filler metal can be used, and vacuum brazing technology is used for brazing to form an annular brazing belt around the through hole, obtaining a plate body. The obtained plate body is basically the same as the double-wall unit mentioned in the background technology;

[0027] Step 3: Fill the gap between the plate A1 and the plate B2 of the plate obtained in the second step with molten tin, and then cool it to solidify the molten tin into the filling layer 3 to obtain the double-wall heat exchanger plate. In this step, the plate can be vertically and slowly immersed in the tin bath. After soaking for a period of time, the plate is taken out in a horizontal posture, and then the tin liquid inside is solidified by means of progressive solidification. It can be gradually cooled from one end to the other (the method of spraying water can be used for cooling) for solidification. After solidification is completed, the residual tin on the surface of the plate is removed. Since tin will not combine with stainless steel, it can also be understood that the two will not adhere or be brazed together, so the filling layer 3 is not combined with the plate A1 and the plate B2. When there are holes in the plate A1 or the plate B2, the fluid can flow out along the filling layer 3 and between them so that the leakage can be detected.

[0028] Since the molten tin is filled between the plate A1 and the plate B2 when it is in a liquid state, its fluidity is very good and it can fill most of the gaps, so that the filling layer 3 is in very good contact with the plate A1 and the plate B2, and the heat exchange efficiency is higher.

[0029] Embodiment 2

[0030] As Figure 3-4 shown, on the basis of Embodiment 1, a nickel layer is provided on the inner side of one of the plate A1 and the plate B2. The inner side of the plate A1 is the surface close to the plate B2, and the inner side of the plate B2 is the surface close to the plate A1. The filling layer 3 is brazed or combined with the nickel layer because tin can combine with the nickel layer. Figure 3 The thickened line in Figure 4 is the bonding surface between the tin layer and the nickel layer. Since the nickel layer is combined with the lower side of the plate A1, the heat exchange efficiency between the filling layer 3 and the plate A1 is higher than that between the two in Embodiment 1.

[0031] The manufacturing method of the double-wall heat exchanger plate in this embodiment includes the following steps:

[0032] Step 1: Stamp the plate A1 and the plate B2 into shape, and the same stamping method as the patent mentioned in the background technology can be used;

[0033] Step 2: Deposit a nickel layer (not deposited around the through holes 4) on the inner side of one of the two plate pieces A1 and B2 obtained in Step 1. Electroplating can be used, and the thickness of the nickel layer is preferably 0.01 - 0.02 mm.

[0034] Step 3: Overlap the plate pieces A1 and B2 obtained in Step 2 and perform brazing. Before brazing, clean the surfaces of both. Copper-based brazing filler metal can be used, and vacuum brazing technology is used for brazing to form an annular brazing zone around the through holes, obtaining a plate body. The obtained plate body is basically the same as the double-wall unit mentioned in the background art.

[0035] Step 4: Fill the gap between the plate pieces A1 and B2 of the plate body obtained in Step 3 with molten tin, and then cool to solidify the molten tin into the filling layer 3, obtaining the double-wall heat exchanger plate piece. This step can be carried out by slowly immersing the plate body vertically into the tin bath. After soaking for a period of time, it can be soaked at a temperature of 250°C - 280°C for 1 - 2 hours, and then the plate body is taken out in a horizontal posture. Then, the tin liquid inside is solidified by means of progressive solidification, and it can be cooled gradually from one end to the other (spraying water can be used for cooling) for solidification. After solidification is completed, the residual tin on the surface of the plate body is removed. The filling layer 3 will be tightly combined or adhered to the plate piece A1 or B2 provided with the nickel layer, and will not combine with the plate pieces A1 and B2 without the nickel layer.

[0036] When cracks or holes appear in the plate piece A1 provided with the nickel layer, the nickel layer and the filling layer 3 at the cracks or holes will also be damaged, and the fluid can flow out along the gap between the filling layer 3 and the plate piece B2 so that the leakage can be detected. When cracks or holes appear in the plate piece B2 provided with the nickel layer, the fluid can flow out along the gap between the filling layer 3 and the plate piece A1 so that the leakage can be detected.

[0037] When manufacturing the double-wall heat exchanger plate piece in this embodiment, a nickel layer can also be deposited on one side of the stainless steel plate used for stamping the plate piece A1 or B2 first, and then stamping, brazing, and obtaining the filling layer 3 are carried out.

[0038] Example 3

[0039] As Figure 5As shown, based on Embodiment 1, nickel layers are provided on the inner sides of both the plate A1 and the plate B2. The nickel layers are narrow strips. The nickel layer on the plate A1 and the nickel layer on the plate B2 are staggered with each other and partially overlap at the edges. The filling layer 3 at the overlapping part is combined or bonded with the plate A1 and the plate B2 at this part simultaneously (the thickened parts at the upper and lower edges of the filling layer 3 in the figure), making it more difficult for gaps to appear between the plate A1 and the plate B2 under the action of other factors, and can avoid the decrease in heat transfer rate caused by the appearance of gaps between the two to a certain extent. However, if the plate A1 or the plate B2 is damaged at the overlapping part, the fluid is not easy to leak and flow to the outside. The filling layer 3 at the non-overlapping part is combined with only one of the plate A1 and the plate B2. The part of the filling layer 3 that is not brazed to the nickel layer communicates with the outside, and the leaked fluid can finally flow to the outside along the area where the nickel layer is not provided.

[0040] The manufacturing method of the double-wall heat exchanger plates in this embodiment is basically the same as that in Embodiment 2, except that narrow strip nickel layers are electroplated on the inner sides of the plate A1 and the plate B2.

Claims

1. A double-wall heat exchanger plate, comprising a plate body composed of plate A (1) and plate B (2), wherein through holes (4) for fluid to pass through the plate body are arranged on the plate body, and an annular brazing strip is arranged around the through holes (4), characterized in that: A filling layer (3) in close contact with both is filled between the plate A (1) and the plate B (2). The materials of the plate A (1) and the plate B (2) are stainless steel, and the material of the filling layer (3) is tin.

2. The double-wall heat exchanger plate according to claim 1, wherein: A nickel layer is provided on the inner side of one of the plate A (1) and the plate B (2). The filling layer (3) is brazed to the nickel layer, and the filling layer (3) is not brazed to the plate A (1) and the plate B (2) without the nickel layer.

3. The double-wall heat exchanger plate according to claim 1, characterized in that: Nickel layers are provided on the inner sides of both the plate A (1) and the plate B (2). The nickel layers are narrow strips. The nickel layer on the plate A (1) partially overlaps with the nickel layer on the plate B (2). The part of the filling layer (3) that is not brazed to the nickel layer communicates with the outside.

4. The manufacturing method of a double-wall heat exchanger plate according to claim 1, characterized in that It includes the following steps: The first step: Stamping the plate A (1) and the plate B (2) into shape. The second step: Overlapping the plate A (1) and the plate B (2) obtained in the first step and performing brazing to form an annular brazing zone around the through-hole (4) to obtain a plate body. The third step: Filling molten tin into the gap between the plate A (1) and the plate B (2) of the plate body obtained in the second step, and then cooling to solidify the molten tin into the filling layer (3) to obtain a double-wall heat exchanger plate.

5. The manufacturing method of a double-wall heat exchanger plate according to any one of claims 2-3, characterized in that It includes the following steps: The first step: Stamping the plate A (1) and the plate B (2) into shape. The second step: Plating a nickel layer on the inner side of one or both of the plate A (1) and the plate B (2) obtained in the first step. The third step: Overlapping the plate A (1) and the plate B (2) obtained in the second step and performing brazing to form an annular brazing zone around the through-hole (4) to obtain a plate body. The fourth step: Filling molten tin into the gap between the plate A (1) and the plate B (2) of the plate body obtained in the third step, and then cooling to solidify the molten tin into the filling layer (3) to obtain a double-wall heat exchanger plate.

6. The manufacturing method of a double-wall heat exchanger plate according to any one of claims 2-3, characterized in that It includes the following steps: The first step: Plating a nickel layer on one side of the stainless steel plate for stamping the plate A (1) and / or the plate B (2). The second step: Stamping the stainless steel plate obtained in the first step into the plate A (1) and the plate B (2). The third step: Overlapping the plate A (1) and the plate B (2) obtained in the second step with the side having the nickel layer facing inward and performing brazing to form an annular brazing zone around the through-hole (4) to obtain a plate body. The fourth step: Filling molten tin into the gap between the plate A (1) and the plate B (2) of the plate body obtained in the third step, and then cooling to solidify the molten tin into the filling layer (3) to obtain a double-wall heat exchanger plate.

Images