Structure and assembly method of magnesium reducing slag heat recovery heat exchanger

Abstract

The invention relates to the technical field of magnesium reducing slag heat recovery, in particular to a magnesium reducing slag heat recovery heat exchanger structure and an assembly method. The magnesium reducing slag heat recovery heat exchanger structure comprises an economizer layer, a low-temperature evaporator layer, a high-temperature evaporator layer, multiple layers of expansion joints, multiple bearing girders and a discharging bin. First heat exchange units, second heat exchange units and third heat exchange units are manufactured in a factory, in a magnesium reducing slag heat recovery factory, the multiple first heat exchange units are assembled between two bearing girders through trunnions, and installation of an economizer layer is completed; a plurality of second heat exchange units are assembled between two bearing girders above a coal economizer layer through trunnions to complete installation of a low-temperature evaporator layer, and a plurality of third heat exchange units are assembled between two bearing girders above the low-temperature evaporator layer through trunnions to complete installation of a high-temperature evaporator layer. The whole heat exchange structure is composed of modular structures and is convenient to manufacture, transport and install, and therefore the cost of the whole system is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of heat recovery of magnesium reduction slag, and in particular to a structure and an assembly method of a heat exchanger for heat recovery of magnesium reduction slag. Background Art

[0002] There are two main methods for producing magnesium metal: thermal reduction and electrolysis. Currently, the vast majority of magnesium smelting companies use thermal reduction to produce magnesium, accounting for more than 90% of magnesium production. Since thermal magnesium production produces an average of 6 tons of magnesium reduction slag for every ton of magnesium produced, and the temperature of the reduction slag discharged from the reduction tank after the reaction is generally 1000°C, the reduction slag contains a large amount of heat. Therefore, some magnesium smelters have gradually developed processes and equipment for applying the waste heat of the reduction slag to complete the heat recovery of the magnesium reduction slag.

[0003] However, the existing magnesium reduction slag heat recovery equipment has two types: one is simple in structure, using a water-cooled slag cooler, and the heat is discharged to the environment through a heat dissipation tower, and the heat energy is not effectively utilized; the other is highly efficient in utilizing heat energy, but the structure is relatively complex, and the manufacturing and installation costs are relatively high. Summary of the invention

[0004] The purpose of the present invention is to provide a structure and assembly method of a heat recovery heat exchanger for magnesium reduction slag, so as to solve the problem of high cost of existing heat recovery equipment for magnesium reduction slag. One is simple in structure, using a water-cooled slag cooler, and the heat is discharged to the environment through a heat dissipation tower, and the heat energy is not effectively utilized; the other is efficient in utilizing heat energy, but the structure is relatively complex, and the manufacturing and installation costs are high.

[0005] To achieve the above-mentioned objectives, the present invention provides a structure of a magnesium reducing slag heat recovery heat exchanger, the structure of the magnesium reducing slag heat recovery heat exchanger includes an economizer layer, a low-temperature evaporator layer, a high-temperature evaporator layer, multi-layer expansion joints, multiple bearing beams and a discharge bin, the economizer layer is installed above the discharge bin, the low-temperature evaporator layer is installed above the economizer layer through the expansion joint, the high-temperature evaporator layer is installed above the low-temperature evaporator layer through the expansion joint, the bearing beams are arranged on both sides of the economizer layer, the low-temperature evaporator layer and the high-temperature evaporator layer, and the economizer layer, the low-temperature evaporator layer and the high-temperature evaporator layer are all installed on the bearing beams through ear shafts.

[0006] The economizer layer is composed of one or more first heat exchange units, the low-temperature evaporator layer is composed of one or more second heat exchange units, and the high-temperature evaporator layer is composed of one or more third heat exchange units.

[0007] Wherein, the number of layers of the economizer layer is one or more layers. When the number of layers of the economizer layer is multiple layers, the expansion joint is arranged between each two adjacent economizer layers;

[0008] The number of layers of the low-temperature evaporator layer is one or more layers. When the number of layers of the low-temperature evaporator layer is multiple layers, the expansion joint is arranged between each two adjacent low-temperature evaporator layers;

[0009] The number of layers of the high-temperature evaporator layer is one or more layers. When the number of layers of the high-temperature evaporator layer is multiple layers, the expansion joint is arranged between every two adjacent high-temperature evaporator layers.

[0010] Among them, each of the first heat exchange unit, each of the second heat exchange unit and each of the third heat exchange unit is provided with a box body, the box body is surrounded by four membrane water-cooled walls, each of the membrane water-cooled walls is composed of a plurality of vertically arranged first steel pipes, a first steel plate is welded between every two adjacent first steel pipes, a water inlet header is provided at the bottom of each of the boxes, and a water outlet header is provided at the top of each of the boxes, the water inlet header is connected with the bottom of the plurality of corresponding first steel pipes, and the water outlet header is connected with the upper ends of the plurality of corresponding first steel pipes.

[0011] Among them, each of the first heat exchange units is also provided with multiple layers of first membrane walls, a first water inlet header and a water outlet header. The multiple layers of the first membrane walls are evenly distributed inside the box body of the first heat exchange unit. The first water inlet header and the water outlet header are arranged on the same side of the box body of the first heat exchange unit. The water inlet of each layer of the first membrane wall is connected to the first water inlet header, and the water outlet of each layer of the first membrane wall is evenly connected to the water outlet header.

[0012] Among them, each of the second heat exchange units is also provided with multiple layers of second membrane walls, a second water inlet header and a first water vapor outlet header. The multiple layers of the second membrane walls are evenly distributed inside the box body of the second heat exchange unit. The second water inlet header and the first water vapor outlet header are respectively provided on both sides of the box body of the second heat exchange unit. The water inlet of each layer of the second membrane wall is connected to the second water inlet header, and the water outlet of each layer of the second membrane wall is evenly connected to the first water vapor outlet header.

[0013] Among them, each of the third heat exchange units is also provided with a plurality of layers of heat exchange tubes, a third water inlet header and a second water vapor outlet header. The plurality of layers of heat exchange tubes are evenly distributed inside the box body of the third heat exchange unit. The third water inlet header and the second water vapor outlet header are respectively provided on both sides of the box body of the third heat exchange unit. The water inlet of each layer of the heat exchange tubes is connected to the third water inlet header, and the water outlet of each layer of the heat exchange tubes is evenly connected to the second water vapor outlet header.

[0014] Among them, the spacing between each two adjacent layers of the first membrane wall is 75mm-125mm, the spacing between each two adjacent layers of the second membrane wall is 75mm-125mm, and the spacing between each two adjacent layers of the heat exchange tubes is 75mm-125mm.

[0015] Among them, each layer of the first membrane wall and each layer of the second membrane wall includes multiple second steel tubes and multiple second steel plates, the second steel plate is welded between every two adjacent second steel tubes, and the ends of every two adjacent second steel tubes on the first membrane wall away from the water inlet header are connected by a connecting elbow, and each layer of the heat exchange tubes is composed of multiple evenly arranged third steel tubes.

[0016] Among them, the second steel tubes between every two adjacent layers of the first membrane walls are arranged in a staggered structure, the second steel tubes between every two adjacent layers of the second membrane walls are arranged in a staggered structure, and the third steel tubes between every two adjacent layers of the heat exchange tubes are arranged in a staggered structure.

[0017] The present invention also provides an assembly method of a magnesium reduction slag heat recovery heat exchanger, which is applied to the structure of the magnesium reduction slag heat recovery heat exchanger as described above, and comprises the following steps:

[0018] completing the manufacturing of a plurality of the first heat exchange units, the second heat exchange units, and the third heat exchange units in a factory;

[0019] In the magnesium reduction slag heat recovery plant, a plurality of the first heat exchange units are assembled between the two bearing beams through the trunnions to complete the installation of the economizer layer;

[0020] After installing the expansion joint above the economizer layer, a plurality of the second heat exchange units are assembled between the two bearing beams through the trunnions above the expansion joint to complete the installation of the low-temperature evaporator layer;

[0021] The expansion joint is installed above the low-temperature evaporator layer, and above the expansion joint, a plurality of the third heat exchange units are installed between the two load-bearing beams through the trunnions to complete the installation of the high-temperature evaporator layer;

[0022] A feed bin and a distributor are installed above the high-temperature evaporator layer, a discharge bin is installed below the economizer layer, and a spiral discharger is installed below the discharge bin to complete the assembly of the entire magnesium reduction slag heat recovery heat exchanger.

[0023] The structure and assembly method of a magnesium reducing slag heat recovery heat exchanger of the present invention completes the manufacture of the first heat exchange unit, the second heat exchange unit and the third heat exchange unit in a factory. In a magnesium reducing slag heat recovery plant, multiple first heat exchange units are assembled between the two bearing beams through the ear shaft to complete the installation of the economizer layer. Above the economizer layer, multiple second heat exchange units are assembled between the two bearing beams through the ear shaft to complete the installation of the low-temperature evaporator layer. Above the low-temperature evaporator layer, multiple third heat exchange units are assembled between the two bearing beams through the ear shaft to complete the installation of the high-temperature evaporator layer. By adopting the technical solution, the entire heat exchange structure is composed of a modular structure, which is convenient for manufacturing, transportation and installation, thereby reducing system costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 It is a partial structural schematic diagram of the structure of the magnesium reduction slag heat recovery heat exchanger provided by the present invention.

[0026] Figure 2 It is a schematic diagram of the partial structure of the exterior of the first heat exchange unit provided by the present invention.

[0027] Figure 3 The present invention provides Figure 2 A schematic diagram of the structure from another perspective.

[0028] Figure 4 It is a schematic diagram of the partially disassembled structure of the first heat exchange unit provided by the present invention.

[0029] Figure 5 It is a schematic diagram of the partially disassembled structure of the second heat exchange unit provided by the present invention.

[0030] Figure 6 It is a schematic diagram of the partially disassembled structure of the third heat exchange unit provided by the present invention.

[0031] Figure 7 The present invention is a flowchart of the steps of assembling the heat recovery heat exchanger for magnesium reduction slag provided by the present invention.

[0032] 101-economizer layer, 102-low-temperature evaporator layer, 103-high-temperature evaporator layer, 104-expansion joint, 105-load-bearing beam, 106-discharging bin, 107-ear shaft, 108-pull rod, 109-box, 110-first steel pipe, 111-first steel plate, 112-first membrane wall, 113-first water inlet header, 114-water outlet header, 115-second membrane wall, 116-second water inlet header, 117-first water outlet steam header, 118-heat exchange tubes, 119-third water inlet header, 120-second water outlet steam header, 121-second steel pipe, 122-second steel plate, 123-connecting elbow, 124-third steel pipe, 125-water outlet header, 126-water inlet header. DETAILED DESCRIPTION

[0033] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0034] See also Figures 1 to 6 The present invention provides a structure of a heat recovery heat exchanger for magnesium reduction slag, the structure of the heat recovery heat exchanger for magnesium reduction slag comprising an economizer layer 101, a low-temperature evaporator layer 102, a high-temperature evaporator layer 103, a multi-layer expansion joint 104, a plurality of bearing beams 105 and a discharge bin 106, the economizer layer 101 is installed above the discharge bin 106, the low-temperature evaporator layer 102 is installed above the economizer layer 101 through the expansion joint 104, the high-temperature evaporator layer 103 is installed above the low-temperature evaporator layer 102 through the expansion joint 104, the bearing beams 105 are arranged on both sides of the economizer layer 101, the low-temperature evaporator layer 102 and the high-temperature evaporator layer 103, the economizer layer 101, the low-temperature evaporator layer 102 and the high-temperature evaporator layer 103 are all installed on the bearing beams 105 through tie rods 108 and 107 ear shafts (such as Figure 1 As shown, the trunnion 107 can be horizontally mounted on the weighing beam 105, such as Figures 2 to 6 As shown, the ear shaft 107 can also adopt a hanging installation structure, wherein the installation method of the ear shaft 107 is preferably as follows Figure 1 Horizontal mounting structure shown);

[0035] The economizer layer 101 is composed of one or more first heat exchange units, the low-temperature evaporator layer 102 is composed of one or more second heat exchange units, and the high-temperature evaporator layer 103 is composed of one or more third heat exchange units.

[0036] In this embodiment, the manufacture of the first heat exchange unit, the second heat exchange unit and the third heat exchange unit is completed in the factory. In the magnesium reduction slag heat recovery plant, multiple first heat exchange units are assembled between the two bearing beams 105 through the ear shaft 107 to complete the installation of the economizer layer 101. Above the economizer layer 101, multiple second heat exchange units are assembled between the two bearing beams 105 through the ear shaft 107 to complete the installation of the low-temperature evaporator layer 102. Above the low-temperature evaporator layer, multiple third heat exchange units are assembled between the two bearing beams 105 through the ear shaft 107 to complete the installation of the high-temperature evaporator layer 103. By adopting this technical solution, the entire heat exchange structure is composed of a modular structure, which is convenient for manufacturing and transportation, thereby reducing installation costs.

[0037] Furthermore, the number of layers of the economizer layer 101 is one or more layers. When the number of layers of the economizer layer 101 is multiple layers, the expansion joint 104 is provided between each two adjacent economizer layers 101;

[0038] The number of layers of the low-temperature evaporator layer 102 is one or more layers. When the number of layers of the low-temperature evaporator layer 102 is multiple layers, the expansion joint 104 is disposed between each two adjacent low-temperature evaporator layers 102;

[0039] The number of layers of the high-temperature evaporator layer 103 is one or more layers. When the number of layers of the high-temperature evaporator layer 103 is multiple layers, the expansion joint 104 is disposed between every two adjacent high-temperature evaporator layers 103 .

[0040] In this embodiment, the number of the low-temperature evaporator layer 102 and the high-temperature evaporator layer 103 can be determined according to the heat exchange characteristics of the material, which has stronger adaptability.

[0041] Furthermore, each of the first heat exchange units, each of the second heat exchange units and each of the third heat exchange units is provided with a box body 109, and the box body 109 is formed by enclosing four membrane water-cooled walls, and each of the membrane water-cooled walls is formed by a plurality of vertically arranged first steel tubes 110, and a first steel plate 111 is welded between every two adjacent first steel tubes 110, and a water inlet header 126 is provided at the bottom of each of the boxes 109, and a water outlet header 125 is provided at the top of each of the boxes 109, and the water inlet header 126 is connected with the bottom of the plurality of corresponding first steel tubes 110, and the water outlet header 125 is connected with the upper ends of the plurality of corresponding first steel tubes 110.

[0042] Preferably, each of the first heat exchange units is also provided with a plurality of first membrane walls 112, a first water inlet header 113 and a water outlet header 114, the plurality of first membrane walls 112 are evenly distributed inside the box body 109 of the first heat exchange unit, the first water inlet header 113 and the water outlet header 114 are provided on the same side of the box body 109 of the first heat exchange unit, the water inlet of each layer of the first membrane wall 112 is connected to the first water inlet header, and the water outlet of each layer of the first membrane wall 112 is evenly connected to the water outlet header 114.

[0043] Preferably, each of the second heat exchange units is also provided with a plurality of layers of second membrane walls 115, a second water inlet header 116 and a first water vapor outlet header 117, and the plurality of layers of the second membrane walls 115 are evenly distributed inside the box body 109 of the second heat exchange unit, and a second water inlet header 116 and the first water vapor outlet header 117 are respectively provided on both sides of the box body 109 of the second heat exchange unit, and the water inlet of each layer of the second membrane wall 115 is connected to the second water inlet header 116, and the water outlet of each layer of the second membrane wall 115 is evenly connected to the first water vapor outlet header 117.

[0044] Preferably, each of the third heat exchange units is also provided with a plurality of layers of heat exchange tubes 118, a third water inlet header 119 and a second water vapor outlet header 120, and the plurality of layers of heat exchange tubes 118 are evenly distributed inside the box body 109 of the third heat exchange unit, and a third water inlet header 119 and a second water vapor outlet header 120 are respectively provided on both sides of the box body 109 of the third heat exchange unit, and the water inlet of each layer of the heat exchange tubes 118 is connected to the third water inlet header 119, and the water outlet of each layer of the heat exchange tubes 118 is evenly connected to the second water vapor outlet header 120.

[0045] Furthermore, the spacing between each two adjacent layers of the first membrane walls 112 is 75 mm-125 mm, the spacing between each two adjacent layers of the second membrane walls 115 is 75 mm-125 mm, and the spacing between each two adjacent layers of the heat exchange tubes 118 is 75 mm-125 mm.

[0046] Furthermore, each layer of the first membrane wall 112 and each layer of the second membrane wall 115 includes a plurality of second steel tubes 121 and a plurality of second steel plates 122, and a second steel plate 122 is welded between each adjacent two second steel tubes 121, and each adjacent two second steel tubes 121 on the first membrane wall 112 are connected at one end away from the water inlet manifold through a connecting elbow 123, and each layer of the heat exchange tubes 118 is composed of a plurality of evenly arranged third steel tubes 124.

[0047] Furthermore, the second steel tubes 121 between every two adjacent layers of the first membrane walls 112 are arranged in a staggered structure, the second steel tubes 121 between every two adjacent layers of the second membrane walls 115 are arranged in a staggered structure, and the third steel tubes 124 between every two adjacent layers of the heat exchange tubes 118 are arranged in a staggered structure.

[0048] See also Figure 7 The present invention also provides an assembly method of a magnesium reduction slag heat recovery heat exchanger, which is applied to the structure of the magnesium reduction slag heat recovery heat exchanger as described above, and comprises the following steps:

[0049] S1: completing the manufacturing of a plurality of the first heat exchange units, the second heat exchange units and the third heat exchange units in a factory;

[0050] S2: In the magnesium reduction slag heat recovery plant, multiple first heat exchange units are assembled between two bearing beams 105 through the trunnions 107 to complete the installation of the economizer layer 101;

[0051] S3: After installing the expansion joint 104 above the economizer layer 101, a plurality of the second heat exchange units are assembled between the two bearing beams 105 above the expansion joint 104 through the trunnions 107 to complete the installation of the low-temperature evaporator layer 102;

[0052] S4: assembling the expansion joint 104 above the low-temperature evaporator layer 102, and assembling the plurality of third heat exchange units between the two bearing beams 105 through the ear shaft 107 above the expansion joint 104, thereby completing the installation of the high-temperature evaporator layer 103;

[0053] S5: Assemble a feed bin and a distributor above the high-temperature evaporator layer 103, assemble a discharge bin 106 below the economizer layer 101, and assemble a spiral discharger below the discharge bin 106 to complete the assembly of the entire magnesium reduction slag heat recovery heat exchanger.

[0054] In this embodiment, first, the manufacture of the plurality of the first heat exchange units, the second heat exchange units and the third heat exchange units is completed in the factory. Then, in the magnesium reduction slag heat recovery plant, the plurality of the first heat exchange units are assembled between the two bearing beams 105 through the ear shaft 107 to complete the installation of the economizer layer 101. After the expansion joint 104 is installed above the economizer layer 101, the plurality of the second heat exchange units are assembled between the two bearing beams 105 through the ear shaft 107 above the expansion joint 104 to complete the installation of the low-temperature evaporator layer 102 (the number of layers of the low-temperature evaporator layer 102 can be assembled into multiple layers). The expansion joint 104 is assembled above the economizer layer 102, and above the expansion joint 104, a plurality of the third heat exchange units are assembled between the two load-bearing beams 105 through the ear shaft 107 to complete the installation of the high-temperature evaporator layer 103 (the number of layers of the high-temperature evaporator layer 103 can be assembled into multiple layers), and finally, a feed bin and a distributor are assembled above the high-temperature evaporator layer 103, a discharge bin 106 is assembled below the economizer layer 101, and a spiral discharger is assembled below the discharge bin 106 to complete the assembly of the entire magnesium reduction slag heat recovery heat exchanger. By adopting the present technical solution, the entire heat exchange structure is composed of a modular structure, which is convenient for manufacturing and transportation, thereby reducing the installation cost.

[0055] What is disclosed above is only a preferred embodiment of the present invention, and it certainly cannot be used to limit the scope of rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of the above embodiment and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.

Claims

1. A structure of a magnesium reduction slag heat recovery heat exchanger, characterized in that: It includes an economizer layer, a low-temperature evaporator layer, a high-temperature evaporator layer, multi-layer expansion joints, multiple load-bearing beams and a discharge bin, the economizer layer is installed above the discharge bin, the low-temperature evaporator layer is installed above the economizer layer through the expansion joint, the high-temperature evaporator layer is installed above the low-temperature evaporator layer through the expansion joint, the load-bearing beams are arranged on both sides of the economizer layer, the low-temperature evaporator layer and the high-temperature evaporator layer, and the economizer layer, the low-temperature evaporator layer and the high-temperature evaporator layer are all installed on the load-bearing beams through ear shafts. The economizer layer is composed of one or more first heat exchange units, the low-temperature evaporator layer is composed of one or more second heat exchange units, and the high-temperature evaporator layer is composed of one or more third heat exchange units.

2. The structure of the magnesium reduction slag heat recovery heat exchanger according to claim 1, characterized in that: The number of layers of the economizer layer is one or more layers. When the number of layers of the economizer layer is multiple layers, the expansion joint is arranged between each two adjacent economizer layers; The number of layers of the low-temperature evaporator layer is one or more layers. When the number of layers of the low-temperature evaporator layer is multiple layers, the expansion joint is arranged between each two adjacent low-temperature evaporator layers; The number of layers of the high-temperature evaporator layer is one or more layers. When the number of layers of the high-temperature evaporator layer is multiple layers, the expansion joint is arranged between every two adjacent high-temperature evaporator layers.

3. The structure of the magnesium reduction slag heat recovery heat exchanger according to claim 1, characterized in that: Each of the first heat exchange units, each of the second heat exchange units and each of the third heat exchange units is provided with a box body, the box body is surrounded by four membrane water-cooled walls, each of the membrane water-cooled walls is composed of a plurality of vertically arranged first steel pipes, a first steel plate is welded between every two adjacent first steel pipes, a water inlet header is provided at the bottom of each of the boxes, a water outlet header is provided at the top of each of the boxes, the water inlet header is communicated with the lower ends of the plurality of corresponding first steel pipes, and the water outlet header is communicated with the upper parts of the plurality of corresponding first steel pipes.

4. The structure of the magnesium reduction slag heat recovery heat exchanger according to claim 3, characterized in that: Each of the first heat exchange units is also provided with multiple layers of first membrane walls, a first water inlet header and a water outlet header. The multiple layers of the first membrane walls are evenly distributed inside the box body of the first heat exchange unit. The first water inlet header and the water outlet header are provided on the same side of the box body of the first heat exchange unit. The water inlet of each layer of the first membrane wall is connected to the first water inlet header, and the water outlet of each layer of the first membrane wall is evenly connected to the water outlet header.

5. The structure of the magnesium reduction slag heat recovery heat exchanger according to claim 4, characterized in that: Each of the second heat exchange units is also provided with a plurality of second membrane walls, a second water inlet header and a first water vapor outlet header. The plurality of second membrane walls are evenly distributed inside the box body of the second heat exchange unit. A second water inlet header and the first water vapor outlet header are respectively provided on both sides of the box body of the second heat exchange unit. The water inlet of each layer of the second membrane wall is connected to the second water inlet header, and the water outlet of each layer of the second membrane wall is evenly connected to the first water vapor outlet header.

6. The structure of the magnesium reduction slag heat recovery heat exchanger according to claim 5, characterized in that: Each of the third heat exchange units is further provided with a plurality of layers of heat exchange tubes, a third water inlet header and a second water vapor outlet header. The plurality of layers of heat exchange tubes are evenly distributed inside the box body of the third heat exchange unit. A third water inlet header and a second water vapor outlet header are respectively provided on both sides of the box body of the third heat exchange unit. The water inlet of each layer of the heat exchange tubes is connected to the third water inlet header, and the water outlet of each layer of the heat exchange tubes is evenly connected to the second water vapor outlet header.

7. The structure of the magnesium reduction slag heat recovery heat exchanger according to claim 6, characterized in that: The spacing between each two adjacent layers of the first membrane wall is 75mm-125mm, the spacing between each two adjacent layers of the second membrane wall is 75mm-125mm, and the spacing between each two adjacent layers of the heat exchange tubes is 75mm-125mm.

8. The structure of the magnesium reduction slag heat recovery heat exchanger according to claim 7, characterized in that: Each layer of the first membrane wall and each layer of the second membrane wall includes a plurality of second steel tubes and a plurality of second steel plates, the second steel plate is welded between each adjacent two second steel tubes, the ends of each adjacent two second steel tubes on the first membrane wall away from the water inlet header are connected by a connecting elbow, and each layer of the heat exchange tubes is composed of a plurality of evenly arranged third steel tubes.

9. The structure of the magnesium reduction slag heat recovery heat exchanger according to claim 9, characterized in that: The second steel tubes between every two adjacent layers of the first membrane walls are arranged in a staggered structure, the second steel tubes between every two adjacent layers of the second membrane walls are arranged in a staggered structure, and the third steel tubes between every two adjacent layers of the heat exchange tubes are arranged in a staggered structure.

10. An assembly method of a magnesium reduction slag heat recovery heat exchanger, applied to the structure of the magnesium reduction slag heat recovery heat exchanger according to claim 1, characterized in that: The steps include: completing the manufacturing of a plurality of the first heat exchange units, the second heat exchange units, and the third heat exchange units in a factory; In the magnesium reduction slag heat recovery plant, a plurality of the first heat exchange units are assembled between the two bearing beams through the trunnions to complete the installation of the economizer layer; After installing the expansion joint above the economizer layer, a plurality of the second heat exchange units are assembled between the two bearing beams through the trunnions above the expansion joint to complete the installation of the low-temperature evaporator layer; The expansion joint is installed above the low-temperature evaporator layer, and above the expansion joint, a plurality of the third heat exchange units are installed between the two load-bearing beams through the trunnions to complete the installation of the high-temperature evaporator layer; A feed bin and a distributor are installed above the high-temperature evaporator layer, a discharge bin is installed below the economizer layer, and a spiral discharger is installed below the discharge bin to complete the assembly of the entire magnesium reduction slag heat recovery heat exchanger.

Images