WO2022021667A1

WO2022021667A1 - Welding and assembling process for plate heat exchanger unit

Info

Publication number: WO2022021667A1
Application number: PCT/CN2020/128249
Authority: WO
Inventors: 陈明; 陈庚; 高健; 徐殿国
Original assignee: 扬州派斯特换热设备有限公司
Priority date: 2020-07-29
Filing date: 2020-11-12
Publication date: 2022-02-03
Also published as: CN111981879A; CN111981879B

Abstract

A welding and assembling process for a plate heat exchanger unit, comprising the following steps: 1) the plate heat exchanger unit comprises a cylindrical barrel-shaped housing (1) having two open ends, a cylindrical barrel-shaped inner cylinder (4), a spiral inner heat exchange plate I (2) wound by a metal plate, a spiral inner heat exchange plate II (3) wound by a metal plate, and two end flanges (9); and 2) two strip-shaped welding slots (6) symmetrically arranged are provided on each of the inner surface of the housing (1) and the outer surface of the inner cylinder (4), and the length extension direction of the strip-shaped welding slots (6) is arranged in parallel to cylindrical axes of the housing (1) and the inner cylinder (4). The spiral plate heat exchanger unit is welded by using a brazing process, so that the welding and assembling difficulty of the spiral plate heat exchanger unit is reduced, and it can be ensured that the assembled spiral plate heat exchanger unit has a good connection strength.

Description

Welding and assembling process of a plate heat exchanger unit

technical field

The invention relates to a welding and assembling process of a plate heat exchange unit, and belongs to the field of heat exchange unit manufacturing.

Background technique

Spiral plate heat exchange unit is a new type of heat exchanger with good heat transfer efficiency and high operating stability, and can work together with multiple units. Spiral plate heat exchanger is a high-efficiency heat exchanger equipment, suitable for steam-vapor, vapor-liquid, liquid-liquid, and heat transfer to liquid. It is suitable for chemical, petroleum, solvent, medicine, food, light industry, textile, metallurgy, steel rolling, coking and other industries. According to the structure, it can be divided into non-detachable (type I) spiral plate heat exchanger units and detachable (type II, type III) spiral plate heat exchange units.

The spiral plate heat exchange unit is rolled by two spiral plate heat exchangers, forming two uniform spiral channels, and the two heat transfer media can flow in full countercurrent, which greatly enhances the heat exchange effect, even if there is a small temperature difference between the two The medium can also achieve the ideal heat exchange effect. The nozzle on the shell adopts a tangential structure, and the local resistance is small. Because the curvature of the spiral channel is uniform, the liquid flow in the equipment does not have a large turn, and the total resistance is small, so the design flow rate can be increased to have a higher flow rate. heat transfer capacity.

In the prior art, the non-detachable spiral plate heat exchange unit is basically assembled and fixed in the form of welding, but because the two rolled internal heat exchange plates are inside the shell, it is difficult to manually weld and fix, and the two coils are made of two. The cross-sectional size of the spiral channel formed by the internal heat exchange plate is small, which is inconvenient for internal welding, resulting in problems such as difficult welding, low welding firmness, and uneven welding seam at the connection between the internal heat exchange plate and the shell.

SUMMARY OF THE INVENTION

In view of the existing technology: "The non-detachable spiral plate heat exchange unit is basically assembled and fixed in the form of welding, but because the two rolled internal heat exchange plates are inside the shell, it is difficult to manually weld and fix it. , and the cross-sectional size of the spiral channel formed by the two internal heat exchange plates is small, which is inconvenient for internal welding, resulting in difficult welding, low welding firmness, and poor welding at the connection between the internal heat exchange plate and the shell. Uniformity and other problems", the technical solution of the present invention provides a welding assembly process for a plate heat exchange unit.

In order to solve the above-mentioned technical problems, the technical solution adopted in the present invention is, a welding and assembling process of a plate heat exchange unit, comprising the following steps:

1) The plate heat exchange unit includes a cylindrical shell with openings at both ends, a cylindrical inner tube, and an internal heat exchange plate wound from a metal plate into a spiral shape. One, from a metal plate wound into a spiral shape The internal heat exchange plate two and two end flanges;

2) Two symmetrically arranged strip welding grooves are respectively arranged on the inner surface of the casing and the outer surface of the inner cylinder, and the length extending direction of the strip welding grooves is arranged parallel to the cylindrical axis of the casing and the inner cylinder; After the brazing material is filled in the bar-shaped welding groove, a U-shaped bending strip of the same material as the shell and the inner cylinder is placed. One of the U-shaped side surfaces of the U-shaped bending strip is connected to the cylindrical axis of the shell and the inner cylinder. Set in parallel and fit the inner bottom end face of the strip welding groove;

3) placing the shell and inner cylinder after the completion of step 2) into a sealed heating furnace for heating for a period of time, taking out and cooling, and filling the U-shaped bending bars on the shell and inner cylinder with brazing filler metal after cooling;

4) Wind the inner heat exchange plate 1 and the inner heat exchange plate 2 into a spiral shape from a metal plate, and bend an L-shaped welding head at the two ends of the inner heat exchange plate 1 and the inner heat exchange plate 2 respectively. bend;

5) The inner cylinder is placed in the casing, so that the inner cylinder and the casing are arranged coaxially; the inner heat exchange plate 1 and the inner heat exchange plate 2 are placed in the cavity between the inner cylinder and the casing, so that the inner heat exchange plate is A spiral-shaped cold-side flow channel and a hot-side flow channel are formed between the first plate and the second inner heat exchange plate; the welding heads at both ends of the inner heat exchange plate 1 and the inner heat exchange plate 2 are bent and inserted into the shell and the inner heat exchange plate respectively. In the U-shaped opening of the U-shaped bending strip on the cylinder;

6) place the part completed in step 5) in a sealed heating furnace and take out and cool it after heating for a period of time;

7) Milling the flange welding groove on the surface of the end flange, the shape of the flange welding groove matches the shape of the shell, inner heat exchange plate 1, inner heat exchange plate 2, and inner cylinder after step 6) is completed. Set; fill the brazing material in the flange welding groove, insert the shell, the inner heat exchange plate 1, the inner heat exchange plate 2, and the two ends of the inner cylinder into the flange welding grooves of the two end flanges respectively. inside, and use clamps to clamp the two end flanges to both ends of the shell;

8) The assembly completed in step 7) is placed in a sealed heating furnace and heated for a period of time, taken out and cooled; the fixture is removed to obtain a plate heat exchange unit.

In the technical solution of the present application, a strip-shaped welding groove is arranged on the shell and the inner cylinder, and a U-shaped bending strip is fixed in the strip-shaped welding groove by brazing, so that the first inner heat exchange plate and the second inner heat exchange plate are formed. The welding head bending at the end can be inserted into the U-shaped bending strip and fixed by brazing, which is convenient for the fixing of the inner heat exchange plate 1 and the two ends of the inner heat exchange plate to the shell and the inner cylinder, and due to the welding fixed The larger the surface, the better the welding fixing effect.

The flange welding groove on the end flange is convenient for accommodating the brazing material during welding, and it is convenient for positioning when the end flange is installed with the shell, the inner cylinder, the inner heat exchange plate 1 and the inner heat exchange plate 2. The ends of the shell, the inner cylinder, the inner heat exchange plate 1 and the inner heat exchange plate 2 can all be welded and fixed with the end flanges to improve the gap between the shell, the inner cylinder, the inner heat exchange plate 1 and the inner heat exchange plate 2. The position is fixed firmly, and the internal sealing can be improved.

Optimized, in the above-mentioned welding and assembling process of the plate heat exchange unit, in step 2), the surface of the strip welding groove and the U-shaped bending strip is pretreated; in step 5), the first inner heat exchange plate and the second inner heat exchange plate are The bending surfaces of the welding heads at both ends are pretreated; before step 8), the flange welding groove, the end of the shell, the end of the inner heat exchange plate 1, the end of the inner heat exchange plate 2, The end of the inner cylinder is pretreated.

In the present application, before brazing, each brazing part is pretreated to ensure the cleanliness of the brazing surface, thereby ensuring the effect of brazing and improving the overall fixing firmness.

Optimized, the above-mentioned welding and assembling process of the plate heat exchange unit, the pretreatment process includes: using a degreasing agent to remove oil stains on the surface, using alkaline washing to remove surface oxides, and using acid washing to remove surface oxides.

In this application, through pretreatment, the oil stain and oxide layer on the surface of the brazing surface are removed to ensure good connection firmness after brazing, and prevent internal leakage caused by weak brazing or internal outlet pores.

Optimized, the above-mentioned welding and assembling process of the plate heat exchange unit, the brazing material includes copper-based solder M0 and a vacuum additive, and the vacuum additive uses a mixed powder of manganese and chromium, step 2), step 6) and step 8) In the process of heating in a sealed heating furnace, heat up to 1100 degrees Celsius at a temperature rise rate of 70 degrees Celsius per minute, and maintain 1100 degrees Celsius for 2 minutes.

In this application, copper-based solder M0 is used as the main solder, and mixed powder of manganese and chromium is used as a vacuum aid. In this application, a sealed heating furnace is used for brazing heating. During the brazing heating process, the vacuum aid is oxidized at high temperature. During the oxidation of the vacuum aid, oxygen, nitrogen and other gases in the sealed heating furnace are adsorbed, so that the sealing A self-vacuum is formed in the heating furnace. In a self-vacuum environment, the surface of the brazing material can be prevented from being oxidized. Compared with the use of vacuum equipment for brazing, the solution of the present application does not use vacuum equipment, which reduces equipment costs; compared with the use of inert gas protection, the solution of the present application is easy to operate, does not use protective gas, and can reduce processing costs. The copper-based solder M0 is mixed with a vacuum additive, and during the heating process, the vacuum additive can absorb the oxygen around the copper-based solder M0 to prevent the surface of the copper-based solder M0 from being oxidized during the brazing process.

Titanium, vanadium, chromium, manganese, zirconium, niobium, molybdenum, etc. can be used as vacuum additives, but due to the high cost of other materials, they are not suitable for large-scale industrial production, so the mixed powder of manganese and chromium is used in this application. Vacuum aid.

In the present application, when kept at a temperature of 1100 degrees Celsius for two minutes, the mixed powder of manganese and chromium can completely adsorb oxygen, so that there is no oxygen in the residual gas phase in the sealed heating furnace.

In order to ensure the anti-rust performance of the plate heat exchange unit, the plate heat exchange unit is generally made of rust-proof high alloy steel. In this application, copper-based brazing filler metal M0 is used. The copper-based brazing filler metal M0 can better wet the steel in a vacuum. Especially the high-alloy steel and copper-based brazing filler metal M0 used in the plate heat exchange unit can be well wetted, and it has a good cleaning effect on the brazing part of the plate heat exchange unit, which can ensure the firmness of the brazing.

Under the condition of 1100 degrees Celsius, brazing for two minutes can make the copper-based solder M0 better melt brazing, and make the oxidation process of the mixed powder of manganese and chromium more complete, ensuring a better self-vacuum effect.

Optimized, in the above-mentioned welding and assembling process of the plate heat exchange unit, in step 2), step 6) and step 8), after heating in a sealed heating furnace, the workpiece is normalized, and the normalizing temperature is 920 degrees Celsius.

In the present application, the normalizing operation is performed after brazing, so that the overall strength of the plate heat exchange unit is relatively good. The normalizing temperature of 920 degrees Celsius can prevent the welded seam filled with copper-based solder M0 from being damaged, and prevent bad conditions at the brazing place after normalizing. After experiments, 920 degrees Celsius has the best effect.

Optimized, in the above-mentioned welding and assembling process of the plate heat exchange unit, in step 2), step 6) and step 8), the sealed heating furnace is heated by means of heat radiation, and during the heating process, the sealing of the sealed heating furnace is ensured, and the vacuum The oxygen depletion of the additive keeps a vacuum in the sealed furnace until the welding is complete.

Preferably, in the above-mentioned welding and assembling process of the plate heat exchange unit, the particle size of the vacuum additive is 50-100 microns, and the vacuum additive is heated at a temperature of 600 degrees Celsius in a vacuum furnace before use.

In this application, the vacuum aid is used to adsorb oxygen after being heated. If the particles of the vacuum aid are too large, the effect of adsorbing gas will be poor. If the particles are too fine, the gas will pass through the outer layer of the vacuum aid and enter the inner layer of the vacuum aid. The passage is obstructed, so the particle size of the vacuum aid used in this application is 50-100 microns, which can not only maintain a good gas adsorption effect, but also will not hinder the passage of the gas through the outer layer of the vacuum aid into the inner layer of the vacuum aid . The vacuum additives cannot contain organic impurities, otherwise the oxidation of the vacuum additives will be affected. In this application, the vacuum additives are heated at a temperature of 600 degrees Celsius in a vacuum furnace before use to remove organic impurities in the vacuum additives.

In the optimized welding assembly process of the plate heat exchange unit, 0.4-0.6 grams of vacuum additive is added per cubic centimeter to the volume of the gap to be welded, and other gaps in the volume of the gap to be welded are filled with brazing material.

In the present application, the dosage of the vacuum aid used affects the effect of the self-vacuum. If too much vacuum aid is added, the economic benefit will be poor and the cost will be high. If less vacuum aid is added, the effect of self-vacuum cannot be achieved. Choose to add 0.4-0.6 grams of vacuum additive per cubic centimeter in the volume of the welded gap. When heated to 600 degrees Celsius, there is no oxygen in the residual gas phase around the welded gap. The heating process from 600 degrees Celsius to 1100 degrees Celsius and During the 2-minute brazing process at 1100 degrees Celsius, it can be kept in a vacuum environment. If less vacuum additives are added, during the heating process from 600 degrees Celsius to 1100 degrees Celsius, the copper-based solder M0 has reacted and formed surface oxidation, which affects the brazing process.

Optimized, in the above-mentioned welding and assembling process of the plate heat exchange unit, in step 5), the distance between the inner heat exchange plate 1 and the inner heat exchange plate 2 is made of the same material as the inner heat exchange plate 1 and the inner heat exchange plate 2. After step 5) is completed, take out the bar.

In this application, strip rods are used to support the distance between the inner heat exchange plate 1 and the inner heat exchange plate 2, so that the gap formed between the inner heat exchange plate 1 and the inner heat exchange plate 2 is as uniform as possible to ensure the cold flow channel. And the volume of the hot flow channel is uniform, preventing the deformation of the inner heat exchange plate 1 and the inner heat exchange plate 2 due to the excessive impact of the water flow on the inner heat exchange plate 1 and the inner heat exchange plate 2 due to the uneven volume.

Description of drawings

Fig. 1 is the structural representation of the plate heat exchange unit of the present invention;

Fig. 2 is the A-A sectional view of Fig. 1;

Fig. 3 is the structural representation of the end flange of the present invention;

Fig. 4 is the enlarged view at B of Fig. 2;

FIG. 5 is an enlarged view of C in FIG. 2 .

detailed description

The technical features of the present invention are further described below in conjunction with the accompanying drawings and specific embodiments.

Example 1

As shown in the figure, the present invention is a welding assembly process of a plate heat exchange unit, comprising the following steps:

1) The plate heat exchange unit includes a cylindrical shell 1 with openings at both ends, a cylindrical inner cylinder 4, an internal heat exchange plate 1 wound from a metal plate into a spiral shape, and a metal plate wound. A spiral inner heat exchange plate 2 3 and two end flanges 9;

2) There are two symmetrically arranged strip welding grooves 6 on the inner surface of the shell 1 and the outer surface of the inner cylinder 4 respectively. The shape axes are arranged in parallel; after the brazing material is filled in the bar-shaped welding groove 6, a U-shaped bending strip 7 of the same material as the shell 1 and the inner cylinder 4 is placed, and one of the U-shaped sides of the U-shaped bending strip 7 is placed. The surface is arranged parallel to the cylindrical axis of the shell 1 and the inner cylinder 4 and fits the inner bottom end face of the strip welding groove 6;

3) The shell 1 and the inner cylinder 4 after step 2) are placed in a sealed heating furnace for heating for a period of time, then taken out and cooled, and then filled in the U-shaped bending strips 7 on the shell 1 and the inner cylinder 4 after cooling. brazing material;

4) The inner heat exchange plate 1 2 and the inner heat exchange plate 2 3 are wound from metal plates into a spiral shape, and an L is respectively bent at both ends of the inner heat exchange plate 1 2 and the inner heat exchange plate 2 3. Type of welding head bending 5;

5) Place the inner cylinder 4 in the casing 1, so that the inner cylinder 4 and the casing 1 are arranged coaxially; the inner heat exchange plate 1 2 and the inner heat exchange plate 2 3 are placed between the inner cylinder 4 and the casing 1 In the cavity of the inner heat exchange plate 1 2 and the inner heat exchange plate 2 3, a spiral cold side flow channel and a hot side flow channel are formed; the inner heat exchange plate 1 2 and the inner heat exchange plate 2 3 The welding head bending 5 at the end is respectively inserted into the U-shaped opening of the U-shaped bending strip 7 on the shell 1 and the inner cylinder 4;

7) Milling the flange welding groove 8 on the surface of the end flange 9, the shape of the flange welding groove 8 is the same as that of step 6) the completed shell 1, internal heat exchange plate 1 2, and internal heat exchange plate 2 3 , The shape of the inner cylinder 4 is matched; the brazing material is filled in the flange welding groove 8, and the two ends of the shell 1, the inner heat exchange plate 1 2, the inner heat exchange plate 2 3 and the inner cylinder 4 are respectively inserted. in the flange welding grooves 8 of the two end flanges 9, and clamp the two end flanges 9 on both ends of the shell 1 using a clamp;

In the technical solution of the present application, a strip-shaped welding groove 6 is set on the shell 1 and the inner cylinder 4, and a U-shaped bending strip 7 is fixed in the strip-shaped welding groove 6 by brazing, so that the internal heat exchange plate 1 2 , The welding head bending 5 at the end of the inner heat exchange plate 23 can be inserted into the U-shaped bending strip 7 and fixed by brazing, which is convenient for the end of the inner heat exchange plate 1 2 and the inner heat exchange plate 2 and the shell. The body 1 and the inner cylinder 4 are fixed, and because the welding fixing surface is large, it has a better welding fixing effect.

The flange welding groove 8 on the end flange 9 is convenient to accommodate the brazing material during welding, and the end flange 9 is connected to the shell 1, the inner cylinder 4, the inner heat exchange plate 1 2, and the inner heat exchange plate 2 3. Easy positioning during installation. The ends of the shell 1 , the inner cylinder 4 , the inner heat exchange plate 1 2 and the inner heat exchange plate 2 3 can be welded and fixed with the end flange 9 , and the shell 1 , the inner cylinder 4 and the inner heat exchange plate 1 2 can be improved. . The position of the internal heat exchange plates 3 is fixed firmly, and the internal sealing performance can be improved.

In step 2), the surfaces of the strip welding groove 6 and the U-shaped bending strip 7 are pretreated; in step 5), the welding heads at both ends of the inner heat exchange plate 1 2 and the inner heat exchange plate 2 3 are folded. Bend the surface for pretreatment; before step 8), the flange welding groove 8, the end of the shell 1, the end of the inner heat exchange plate 1 2, the end of the inner heat exchange plate 2 3, the inner cylinder 4 preprocessed at the end.

The pretreatment process includes: removing oil stains on the surface with a degreasing agent, removing surface oxides with alkali washing, and removing surface oxides with acid washing.

The brazing filler metal includes copper-based brazing filler metal M0 and a vacuum additive, and the vacuum additive uses a mixed powder of manganese and chromium. In step 2), step 6) and step 8), in the process of heating in a sealed heating furnace, Heat to 1100 degrees Celsius at a rate of 70 degrees Celsius per minute and hold at 1100 degrees Celsius for 2 minutes.

Brazing for two minutes at 1100 degrees Celsius can make the copper-based solder M0 better melt brazing, and make the oxidation process of the mixed powder of manganese and chromium more complete, ensuring a better self-vacuum effect.

In step 2), step 6) and step 8), after heating in a sealed heating furnace, the workpiece is normalized, and the normalizing temperature is 920 degrees Celsius.

In the present application, the normalizing operation is performed after brazing, so that the overall strength of the plate heat exchange unit is relatively good. The normalizing temperature of 920 degrees Celsius can prevent the welded seam filled with copper-based solder M0 from being damaged, and prevent bad conditions at the brazing place after normalizing.

In step 2), step 6) and step 8), the sealed heating furnace is heated by means of heat radiation. During the heating process, the sealing of the sealed heating furnace is ensured, and the vacuum is maintained in the sealed heating furnace through the oxygen consumption of the vacuum aid. , until the welding is completed.

The particle size of the vacuum aid is 50-100 microns, and the vacuum aid is heated at a temperature of 600 degrees Celsius in a vacuum furnace before use.

In the gap volume to be welded, 0.4 grams of vacuum aid is added per cubic centimeter, and other voids in the gap volume to be welded are filled with brazing filler metal.

In the present application, the dosage of the vacuum aid used affects the effect of the self-vacuum. If too much vacuum aid is added, the economic benefit will be poor and the cost will be high. If less vacuum aid is added, the effect of self-vacuum cannot be achieved. Choose to add 0.4 grams of vacuum aid per cubic centimeter to the volume of the welded gap. When heated to 600 degrees Celsius, there is no oxygen in the residual gas phase around the welded gap. The heating process from 600 degrees Celsius to 1100 degrees Celsius and 1100 degrees Celsius The 2-minute brazing process can be kept in a vacuum environment. If less vacuum additives are added, during the heating process from 600 degrees Celsius to 1100 degrees Celsius, the copper-based solder M0 has reacted and formed surface oxidation, which affects the brazing process.

In step 5), the distance between the inner heat exchange plate 1 2 and the inner heat exchange plate 2 3 is supported by a bar of the same material as the inner heat exchange plate 1 2 and the inner heat exchange plate 2 3, in step 5) When done, take the bar out.

In this application, strip rods are used to support the distance between the inner heat exchange plate 1 2 and the inner heat exchange plate 2 3, so that the gap formed between the inner heat exchange plate 1 2 and the inner heat exchange plate 2 3 is as uniform as possible to ensure that The volume of the cold flow channel and the hot flow channel is uniform to prevent the excessive impact of the water flow on the inner heat exchange plate 1 2 and the inner heat exchange plate 23 due to the uneven volume, and the inner heat exchange plate 1 2 and the inner heat exchange plate 2 3 deformed.

Example 2

The difference between this embodiment and Embodiment 1 is that in the volume of the gap to be welded, 0.6 grams of vacuum additive is added per cubic centimeter, and other voids in the volume of the gap to be welded are filled with brazing filler metal.

In the present application, the dosage of the vacuum aid used affects the effect of the self-vacuum. If too much vacuum aid is added, the economic benefit will be poor and the cost will be high. If less vacuum aid is added, the effect of self-vacuum cannot be achieved. Choose to add 0.6 grams of vacuum aid per cubic centimeter in the volume of the welded seam. When heated to 500 degrees Celsius, there is no oxygen in the residual gas phase around the welded seam. The heating process from 500 degrees Celsius to 1100 degrees Celsius and 1100 degrees Celsius The 2-minute brazing process can be kept in a vacuum environment. If less vacuum additives are added, during the heating process from 600 degrees Celsius to 1100 degrees Celsius, the copper-based solder M0 has reacted and formed surface oxidation, which affects the brazing process.

Example 3

The difference between this embodiment and Embodiment 1 and Embodiment 2 is that 0.5 grams of vacuum additive is added per cubic centimeter in the volume of the gap to be welded, and other voids in the volume of the gap to be welded are filled with brazing filler metal.

In the present application, the dosage of the vacuum aid used affects the effect of the self-vacuum. If too much vacuum aid is added, the economic benefit will be poor and the cost will be high. If less vacuum aid is added, the effect of self-vacuum cannot be achieved. Choose to add 0.5 grams of vacuum aid per cubic centimeter to the volume of the welded seam. When heated to 570 degrees Celsius, there is no oxygen in the residual gas phase around the welded seam. The heating process from 570 degrees Celsius to 1100 degrees Celsius and 1100 degrees Celsius The 2-minute brazing process can be kept in a vacuum environment. If less vacuum additives are added, during the heating process from 600 degrees Celsius to 1100 degrees Celsius, the copper-based solder M0 has reacted and formed surface oxidation, which affects the brazing process.

Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the above examples. Those of ordinary skill in the art, within the essential scope of the present invention, make changes, modifications, additions or substitutions, all should belong to protection scope of the present invention.

Claims

A welding and assembling process for a plate heat exchange unit, characterized in that it comprises the following steps:

1) The plate heat exchange unit includes a cylindrical shell (1) open at both ends, a cylindrical inner tube (4), and an internal heat exchange plate one (2) wound from a metal plate into a spiral shape. 2. Two (3) internal heat exchange plates (3) and two end flanges (9) wound from metal plates into a spiral shape;

2) Two symmetrically arranged bar-shaped welding grooves (6) are respectively provided on the inner surface of the shell (1) and the outer surface of the inner cylinder (4). The cylindrical axes of the body (1) and the inner cylinder (4) are arranged in parallel; after the brazing material is filled in the strip-shaped welding groove (6), a U of the same material as the casing (1) and the inner cylinder (4) is placed. The U-shaped bending strip (7), one of the U-shaped side surfaces of the U-shaped bending strip (7) is arranged in parallel with the cylindrical axis of the casing (1) and the inner cylinder (4) and fits into the strip welding groove (6). ) inner bottom end face;

3) The shell (1) and the inner cylinder (4) after step 2) are placed in a sealed heating furnace for heating for a period of time, then taken out and cooled. Brazing material is filled in the U-shaped bending strip (7);

4) The inner heat exchange plate 1 (2) and the inner heat exchange plate 2 (3) are wound from metal plates into a spiral shape, and the two ends of the inner heat exchange plate 1 (2) and the inner heat exchange plate 2 (3) are wound. The ends are respectively bent to form an L-shaped welding head bend (5);

5) Place the inner cylinder (4) in the casing (1), so that the inner cylinder (4) and the casing (1) are arranged coaxially; ) is placed in the cavity between the inner cylinder (4) and the shell (1), so that a helical cold-side flow channel and Hot side flow channel; Bend the welding heads (5) at both ends of the inner heat exchange plate 1 (2) and the inner heat exchange plate 2 (3) and insert them into the U on the shell (1) and the inner cylinder (4) respectively. in the U-shaped opening of the bending strip (7);

6) place the part completed in step 5) in a sealed heating furnace and take out and cool it after heating for a period of time;

7) Mill the flange welding groove (8) on the surface of the end flange (9). The shape of the flange welding groove (8) is the same as that of the shell (1) and the internal heat exchange plate after step 6). (2) The shape of the second inner heat exchange plate (3) and the inner cylinder (4) is matched; the brazing material is filled in the flange welding groove (8), and the shell (1) and the inner heat exchange plate (2) The two ends of the inner heat exchange plate (3) and the inner cylinder (4) are respectively inserted into the flange welding grooves (8) of the two end flanges (9), and a clamp is used to connect the two The end flanges (9) are clamped on both ends of the shell (1);

8) The assembly completed in step 7) is placed in a sealed heating furnace and heated for a period of time, taken out and cooled; the fixture is removed to obtain a plate heat exchange unit.
The welding and assembling process of the plate heat exchanger unit according to claim 1, characterized in that: in step 2), the surfaces of the strip welding groove (6) and the U-shaped bending strip (7) are pretreated; in step 5) , preprocess the surfaces of the welding head bending (5) at both ends of the inner heat exchange plate one (2) and the inner heat exchange plate two (3); before step 8), the flange welding groove (8) , The end of the shell (1), the end of the inner heat exchange plate one (2), the end of the inner heat exchange plate two (3), and the end of the inner cylinder (4) are pretreated.
The welding and assembling process of the plate heat exchange unit according to claim 2, wherein the pretreatment process includes: removing oil stains on the surface with a degreasing agent, removing surface oxides with alkali washing, and removing surface oxides with acid washing.
The welding and assembling process of the plate heat exchange unit according to claim 1, characterized in that: in step 2), step 6) and step 8), the sealed heating furnace is heated by means of heat radiation, and during the heating process, the sealing is ensured. For the sealing of the heating furnace, the oxygen consumption of the vacuum aids keeps the vacuum in the sealing heating furnace until the welding is completed.
The welding and assembling process of the plate heat exchange unit according to claim 1, characterized in that: in step 5), the distance between the first inner heat exchange plate (2) and the second inner heat exchange plate (3) is the same as that of the inner heat exchange plate. Hot plate one (2) and inner heat exchange plate two (3) are supported by strip rods of the same material, and after step 5) is completed, the strip rods are taken out.