Pre-hydrogenation feeding heat exchanger set

Abstract

The utility model relates to a pre-hydrogenation feeding heat exchanger group which comprises pre-hydrogenation feeding heat exchangers which are mutually cascaded, a tube plate, a conical structural member and a wound tube of a first-stage pre-hydrogenation feeding heat exchanger are all made of duplex stainless steel, and a tube plate, a conical structural member and a wound tube of a second-stage pre-hydrogenation feeding heat exchanger are all made of austenitic stainless steel. Materials pass through the first-stage pre-hydrogenation feeding heat exchanger and then enter the conical structural part of the second-stage pre-hydrogenation feeding heat exchanger, and a high-temperature medium enters the second-stage pre-hydrogenation feeding heat exchanger and then enters the first-stage pre-hydrogenation feeding heat exchanger. According to the pre-hydrogenation feeding heat exchanger set, a conventional in-line heat exchanger is replaced with the two wound tube type heat exchanger sets, heat exchange tubes of the two heat exchangers are made of duplex stainless steel and austenitic stainless steel respectively, corrosion resistance and high temperature resistance are achieved, and manufacturing and using cost of the pre-hydrogenation feeding heat exchanger set is effectively reduced.

Description

Technical Field

[0001] The utility model relates to a pre-hydrogenation feed heat exchanger group, belonging to the technical field of heat exchangers. Background Art

[0002] At present, after the pre-hydrogenation feed comes out of the raw material buffer tank, it is pressurized by the pre-hydrogenation feed pump and mixed with the hydrogen-containing gas from the outlet of the pre-hydrogenation circulating hydrogen compressor. It is then heat exchanged in the shell-and-tube pre-hydrogenation feed heat exchanger, and then enters the pre-hydrogenation feed heating furnace to be heated to the reaction temperature and then enters the pre-hydrogenation reactor R101A / B and the dechlorination reactor R102 for reaction.

[0003] In the above process, the shell-and-tube pre-hydrogenation feed heat exchanger is used to heat the material. Since the discharge temperature is as high as 300~350℃, the heat exchanger generally uses austenitic stainless steel with excellent heat resistance. However, the material will form crystalline ammonium salts at the initial low temperature (170~190℃) when heated. This type of ammonium salt will cause more serious corrosion to austenitic stainless steel, thereby increasing the maintenance frequency and reducing its service life.

[0004] At the same time, since the material is mixed with hydrogen-containing gas, the mixed gas pressure is high, and the heat exchanger needs to have a higher pressure resistance, especially in the high-temperature section (300~350℃) at the discharge point. As the temperature increases, the pressure is greater, so the heat exchanger needs to have a higher pressure resistance.

[0005] In summary, conventional shell-and-tube heat exchangers must simultaneously meet the functions of corrosion resistance, high temperature resistance, and high pressure resistance, which means that they have extremely high requirements for materials and processes, which will undoubtedly greatly increase customers' usage costs. Summary of the invention

[0006] The purpose of the utility model is to overcome the above-mentioned shortcomings and provide a pre-hydrogenation feed heat exchanger group, which replaces the conventional in-line heat exchanger with two coiled heat exchanger groups. The heat exchange tubes of the two heat exchangers are made of duplex stainless steel (S22053) and austenitic stainless steel (S32168), respectively. The duplex stainless steel (S22053) is used to achieve corrosion resistance in the low temperature section, and the high temperature resistance of austenitic stainless steel (S32168) is used in the high temperature section. The coiled heat exchanger (high temperature section) adopts a new design structure, which makes it have better pressure resistance, increases its service life, and is conducive to reducing its manufacturing and use costs.

[0007] The purpose of the utility model is achieved in this way:

[0008] A pre-hydrogenation feed heat exchanger comprises a cylinder, tube sheets are arranged at both ends of the cylinder, a central cylinder is connected between the two tube sheets, two ends of a winding tube wound around the central cylinder are respectively plugged into the two tube sheets, and a tube box is installed on the tube sheets;

[0009] The upper surface of the tube sheet is provided with a tube sheet tube side boss, the bottom of the tube box is welded to the tube sheet tube side boss around, a tube sheet bottom boss is provided at the center of the bottom surface of the tube sheet, and the inner and outer tube walls of the tube sheet bottom boss are connected to the bottom surface of the tube sheet through an arc transition structure.

[0010] Preferably, the pipe box is a conical structural member.

[0011] Preferably, the bottom surface of the tube sheet is provided with arc-shaped shell side bosses around the tube sheet, the end of the cylinder is provided with a shell side head docked with the shell side boss of the tube sheet, and the shell side head and the shell side boss of the tube sheet are welded together by butt welding.

[0012] Implementation method 1:

[0013] A pre-hydrogenation feed heat exchanger group comprises mutually cascaded pre-hydrogenation feed heat exchangers, wherein the winding pipes of the first-stage pre-hydrogenation feed heat exchanger are made of duplex stainless steel, the tube sheet is made of low alloy steel forgings and is welded with a corrosion-resistant layer, and the conical structural member is a composite plate structure; the winding pipes of the second-stage pre-hydrogenation feed heat exchanger are made of austenitic stainless steel, the tube sheet is made of low alloy steel forgings and is welded with a corrosion-resistant layer, and the conical structural member is a composite plate structure; the material enters the conical structural member of the second-stage pre-hydrogenation feed heat exchanger after being fed in and out through the two conical structural members of the first-stage pre-hydrogenation feed heat exchanger, and the high-temperature medium enters the first-stage pre-hydrogenation feed heat exchanger after entering the second-stage pre-hydrogenation feed heat exchanger.

[0014] Implementation method 2:

[0015] A pre-hydrogenation feed heat exchanger group comprises two groups of pre-hydrogenation feed heat exchangers cascaded with each other, wherein the winding pipe of the first-stage pre-hydrogenation feed heat exchanger is made of duplex stainless steel, the tube sheet is made of low alloy steel forgings and is welded with a corrosion-resistant layer, and the conical structure and the cylinder are of a composite plate structure; the winding pipe of the second-stage pre-hydrogenation feed heat exchanger is made of austenitic stainless steel, the tube sheet is made of low alloy steel forgings and is welded with a corrosion-resistant layer, and the conical structure and the cylinder are of a composite plate structure; after the material medium enters and exits the shell side of the first-stage pre-hydrogenation feed heat exchanger, it enters the conical structure of the second-stage coil heat exchanger, and after the high-temperature medium enters the shell side of the second-stage pre-hydrogenation feed heat exchanger, it enters the conical structure of the first-stage pre-hydrogenation feed heat exchanger.

[0016] Implementation method three:

[0017] A pre-hydrogenation feed heat exchanger group comprises two groups of pre-hydrogenation feed heat exchangers cascaded with each other, wherein the winding pipe of the first-stage pre-hydrogenation feed heat exchanger is made of duplex stainless steel, the tube sheet is made of low-alloy steel forgings and is welded with a corrosion-resistant layer, and the conical structure and the cylinder are of a composite plate structure; the winding pipe of the second-stage pre-hydrogenation feed heat exchanger is made of austenitic stainless steel, the tube sheet is made of low-alloy steel forgings and is welded with a corrosion-resistant layer, and the conical structure and the cylinder are of a composite plate structure; after the material medium enters and exits the shell side of the first-stage pre-hydrogenation feed heat exchanger, it enters the shell side of the second-stage coil heat exchanger, and the high-temperature medium enters and exits the conical structure of the second-stage pre-hydrogenation feed heat exchanger and then enters the conical structure of the first-stage pre-hydrogenation feed heat exchanger.

[0018] In the above three implementations, the shell side head provided at the end of the cylinder of the first stage pre-hydrogenation feed heat exchanger is welded around the side wall of the tube sheet;

[0019] The bottom surface of the tube sheet of the second-stage pre-hydrogenation feed heat exchanger is provided with arc-shaped tube sheet shell side bosses around, and the end of the cylinder is provided with a shell side head that is connected to the tube sheet shell side bosses. The shell side head and the tube sheet shell side bosses are welded together.

[0020] Preferably, the upper surface of the tube sheet of the first-stage pre-hydrogenation feed heat exchanger is formed with a corrosion-resistant layer by surfacing, and the material of the corrosion-resistant layer is the same as that of the heat exchange tube;

[0021] Likewise, the inner wall of the conical structure of the second-stage pre-hydrogenation feed heat exchanger, the upper and lower surfaces of the tube sheet, and the inner wall of the cylinder are provided with a corrosion-resistant layer.

[0022] Compared with the prior art, the beneficial effects of the utility model are:

[0023] The utility model replaces the conventional in-line shell-and-tube heat exchanger with a coiled tube heat exchanger, thereby greatly reducing the volume of the heat exchanger group; and adopts a heat exchanger group consisting of two groups of coiled tube heat exchangers to replace a conventional group of straight tube heat exchangers, which not only further reduces its volume, but also the heat exchange tubes of the two groups of heat exchanger groups are made of low-temperature corrosion-resistant materials and high-temperature resistant materials respectively, thereby meeting the low-temperature corrosion and high-temperature characteristics of the feed and ensuring the reliability and continuity of production.

[0024] In addition, the coiled tube heat exchanger adopted by the utility model adopts a brand-new connection structure, which adopts a welded corrosion-resistant layer structure on the upper surface of the tube sheet; a boss is processed on the tube side, and the boss is connected to the tube box by butt welding; a boss is welded on the bottom surface of the tube sheet, the boss is rounded inside and outside, and the transition is smooth, and the boss is butt welded to the center tube; a boss is processed on the shell side of the tube sheet, and the boss is connected to the shell head by butt welding, etc., so that its connection has better pressure resistance, making it more suitable for pre-hydrogenation feed applications, able to cope with higher pressures, so that it has a longer service life, reduces the frequency of maintenance and replacement, and is conducive to increasing the service life of the equipment and improving its market competitiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The utility model is a schematic structural diagram of a pre-hydrogenation feed heat exchanger group.

[0026] Figure 2 It is a structural schematic diagram of the first-stage coiled tube heat exchanger in the utility model.

[0027] Figure 3 For this utility model Figure 2 A partial enlarged view of .

[0028] Figure 4 It is a structural schematic diagram of the second-stage coiled tube heat exchanger in the utility model.

[0029] Figure 5 For this utility model Figure 4 A partial enlarged view of .

[0030] in:

[0031] Cylinder 1, tube sheet 2, conical structure 3, winding tube 4, center tube 5, corrosion-resistant layer 6;

[0032] Shell side head 1.1;

[0033] The tube sheet bottom shoulder 2.1, the tube sheet shell side shoulder 2.2, the tube sheet tube side shoulder 2.3. DETAILED DESCRIPTION

[0034] See also Figures 1 to 5The utility model relates to a pre-hydrogenation feed heat exchanger group, which includes two groups of cascaded coiled tube heat exchangers. The coiled tube heat exchanger includes a cylinder 1, and tube sheets 2 are arranged at both ends of the cylinder 1. The tube box installed on the tube sheet 2 is a conical structure 3. The conical structure 3 is used to replace the conventional elliptical official box and the pipe connection form (whose fluid distribution effect is poor). Not only is the structure simpler, but the conical structure makes its stress release more sufficient, making its pressure resistance better. The pre-hydrogenation feed occasion applied in this patent has higher pressure resistance requirements. Therefore, after using the conical structure 3, its pressure resistance performance is improved. It is more reliable and has better comprehensive safety performance; further, in order to increase the connection firmness between the conical structural member 3 and the tube sheet 2, the upper surface of the tube sheet 2 is provided with tube sheet tube side convex shoulders 2.3, and the bottom of the conical structural member 3 is welded to the tube sheet tube side convex shoulders 2.3. Through the design of the tube sheet tube side convex shoulders 2.3, the connection has a larger operating space when butt welding. Compared with the conventional tube sheet with a flat top surface, welding grooves can be set inside and outside the welded connection for butt welding, thereby improving the strength of the welding and further improving its compressive resistance.

[0035] At the same time, in order to further improve the pressure resistance, a tube sheet bottom surface boss 2.1 is provided at the center of the bottom surface of the tube sheet 2. The tube sheet bottom surface boss 2.1 and the tube sheet 2 are an integral structure (that is, the two are formed in one piece), and the inner and outer tube walls of the tube sheet bottom surface boss 2.1 and the bottom surface of the tube sheet 2 are an arc transition connection structure, so that it has better pressure resistance. Subsequently, the central tube 5 is welded to the tube sheet bottom surface bosses 2.1 on the two tube sheets 2, and the winding tube 4 is arranged around the central tube 5, and the two ends of the winding tube 4 are respectively connected to the two tube sheets 2, and the conical structural members 3 at the two ends are connected. In addition, the bottom surface of the tube sheet 2 is provided with a tube sheet shell side boss 2.2 with an arc structure (and the tube sheet 2 and the tube sheet shell side boss 2.2 are also an integral structure formed in one piece), and the end of the cylinder 1 is provided with a shell side head 1.1 that is butted with the tube sheet shell side boss 2.2, and then the shell side head 1.1 and the tube sheet shell side boss 2.2 are welded together by internal and external butt welding. Through the arc transition mode of the butt section 1.1 and the tube sheet shell side boss 2.2, the connection has a better stress release ability, avoiding leakage in a high-pressure use environment, and ensuring its reliability and service life.

[0036] Embodiment 1: Two groups of coiled heat exchangers are cascaded to form a pre-hydrogenation feed heat exchanger group. The first-stage coiled heat exchanger is used in a low-temperature application environment. The materials of the tube sheet 2, the conical structure 3 and the coil 4 are all austenitic stainless steel (S32168). The coil 4 of the first-stage pre-hydrogenation feed heat exchanger is made of duplex stainless steel, the tube sheet 2 is made of low-alloy steel forgings and is welded with a corrosion-resistant layer, and the conical structure 3 is a composite plate structure. The second-stage coiled heat exchanger is used in a high-temperature application environment. The coil 4 of the second-stage pre-hydrogenation feed heat exchanger is made of austenitic stainless steel, the tube sheet 2 is made of low-alloy steel forgings and is welded with a corrosion-resistant layer, and the conical structure 3 is a composite plate structure.

[0037] The material medium enters the shell side inlet at the bottom of the first-stage coiled heat exchanger, and then is discharged from the shell side outlet at the top of the first-stage coiled heat exchanger, and enters the bottom tube side inlet of the second-stage coiled heat exchanger. The top tube side inlet of the second-stage coiled heat exchanger is connected to the next process; at the same time, the high-temperature heating medium enters through the upper shell side inlet of the second-stage coiled heat exchanger, and is discharged through the lower shell side outlet of the second-stage coiled heat exchanger, and enters the top tube side inlet of the first-stage coiled heat exchanger, and then flows out through the bottom tube side outlet of the first-stage coiled heat exchanger.

[0038] During the whole process, the first-stage coiled heat exchanger is in a low-temperature environment (the high-temperature heating medium has been cooled down during the process of passing through the second-stage coiled heat exchanger). At this time, the material of the first-stage coiled heat exchanger is duplex stainless steel that can resist sodium salt corrosion, so that it has corrosion resistance and high tolerance. Then the second-stage coiled heat exchanger is in a high-temperature application environment, but at this time, the ammonium salt inside the material has been crystallized in the first-stage coiled heat exchanger, and the remaining small amount will not crystallize again in a high-temperature environment, so it will not cause any corrosion to the austenitic stainless steel of the second-stage coiled heat exchanger.

[0039] Embodiment 2: Two groups of coiled heat exchangers are cascaded to form a pre-hydrogenation feed heat exchanger group. The first-stage coiled heat exchanger is for a low-temperature application environment. The material of the coil 4 is duplex stainless steel (S22053). The tube sheet 2 is made of low-alloy steel forgings and is welded with a corrosion-resistant layer. The conical structure 3 and the cylinder 1 are of a composite plate structure. The corrosion resistance is utilized, and the heat exchange temperature range in the low-temperature section is 170~190°C. Then the preheated feed enters the second-stage coiled heat exchanger. At this time, the material of the second-stage coiled heat exchanger is austenitic stainless steel (S32168). The tube sheet 2 is made of low-alloy steel forgings and is welded with a corrosion-resistant layer. The conical structure 3 and the cylinder 1 are of a composite plate structure. The heat exchange temperature range of the second-stage coiled heat exchanger is 300~350°C, and the high temperature resistance of austenitic stainless steel is utilized to protect the temperature rise of the pre-hydrogenation feed. At the same time, the advantage of using two groups of coiled heat exchangers is that maintenance is more convenient, especially two groups of coiled heat exchangers in the first stage low temperature section can be set in parallel, one for use and one for backup, so that when one group needs to clean the coil 4, it can be easily operated.

[0040] Preferably, on the basis of the parallel arrangement of the two groups of coil-wound heat exchangers of the first-stage low-temperature section, the coil-wound heat exchangers of the second-stage high-temperature section are also arranged in two parallel ways, and then the conical structural members 3 of the top discharge of the two parallel coil-wound heat exchangers of the first-stage low-temperature section are connected, and then connected to the conical structural members 3 of the bottom feed of the two parallel coil-wound heat exchangers of the second-stage high-temperature section. In this way, online maintenance and replacement without stopping can be achieved. When a group of coil-wound heat exchangers of the first-stage low-temperature section is maintained or replaced, the coil-wound heat exchanger is turned off, and then only the flow rate of the second stage needs to be slowed down to perform maintenance and replacement without stopping, thereby ensuring the continuity of the operation. More importantly, compared with the in-line heat exchanger, under the same heat exchange requirements and the same flow channels, the floor area of ​​the four coil-wound heat exchangers constituting the above-mentioned pre-hydrogenation feed heat exchanger group is slightly smaller than the floor area of ​​one in-line heat exchanger, which is conducive to the layout of more production lines in the workshop.

[0041] Embodiment 3: Two groups of coiled heat exchangers are cascaded to form a pre-hydrogenation feed heat exchanger group. The first-stage coiled heat exchanger is used in a low-temperature application environment. Its coiled tube 4 is made of duplex stainless steel, and the tube sheet 2 is made of low-alloy steel forgings and welded with a corrosion-resistant layer. The conical structure 3 and the cylinder 1 are of a composite plate structure. The second-stage coiled heat exchanger is used in a high-temperature application environment. Its coiled tube 4 is made of austenitic stainless steel, and the tube sheet 2 is made of low-alloy steel forgings and welded with a corrosion-resistant layer. The conical structure 3 and the cylinder 1 are of a composite plate structure. The material medium enters the shell side inlet at the bottom of the first-stage coiled heat exchanger, and then enters the first-stage After being discharged from the shell side outlet at the top of the coiled heat exchanger, the material enters the shell side of the second-stage coiled heat exchanger for heating, and is connected to the next process through the shell side outlet of the second-stage coiled heat exchanger; at the same time, the high-temperature heating medium enters through the upper conical structure 3 inlet of the second-stage coiled heat exchanger, undergoes high-temperature heat exchange in the second-stage coiled heat exchanger, and is discharged through the lower conical structure 3 outlet, and enters the top conical structure 3 inlet of the first-stage coiled heat exchanger, and then undergoes low-temperature heat exchange on the material in the shell side through the first-stage coiled heat exchanger, and then flows out through the bottom conical structure 3.

[0042] In addition: It should be noted that the above specific implementation is only an optimization scheme of this patent. Any changes or improvements made by technicians in this field based on the above concept are within the scope of protection of this patent.

Claims

1. A pre-hydrogenation feed heat exchanger, comprising a cylinder (1), tube sheets (2) are arranged at both ends of the cylinder (1), a central cylinder (5) is connected between the two tube sheets (2), both ends of a winding tube (4) wound around the central cylinder (5) are respectively plugged into the two tube sheets (2), and a tube box is installed on the tube sheet (2), characterized in that: Tube sheet tube side bosses (2.3) are arranged around the upper surface of the tube sheet (2); the bottom of the tube box is welded to the tube sheet tube side bosses (2.3); a tube sheet bottom boss (2.1) is arranged at the center of the bottom surface of the tube sheet (2); and the inner and outer tube walls of the tube sheet bottom boss (2.1) are connected to the bottom surface of the tube sheet (2) via a circular arc transition structure.

2. A pre-hydrogenation feed heat exchanger according to claim 1, characterized in that: The pipe box is a conical structural member (3).

3. A pre-hydrogenation feed heat exchanger according to claim 1, characterized in that: The bottom surface of the tube sheet (2) is provided with a tube sheet shell side boss (2.2) with an arc structure around its periphery, and the end of the cylinder (1) is provided with a shell side head (1.1) that is butted against the tube sheet shell side boss (2.2), and the shell side head (1.1) and the tube sheet shell side boss (2.2) are connected by welding.

4. A pre-hydrogenation feed heat exchanger group, characterized in that: A pre-hydrogenation feed heat exchanger as claimed in claim 2 is provided, comprising two groups of cascaded pre-hydrogenation feed heat exchangers, wherein the material of the winding pipe (4) of the first-stage pre-hydrogenation feed heat exchanger is duplex stainless steel, and the material of the winding pipe (4) of the second-stage pre-hydrogenation feed heat exchanger is austenitic stainless steel. The material enters the conical structure (3) of the second-stage pre-hydrogenation feed heat exchanger after entering and exiting the two conical structures (3) of the first-stage pre-hydrogenation feed heat exchanger. The high-temperature medium enters the first-stage pre-hydrogenation feed heat exchanger after entering the second-stage pre-hydrogenation feed heat exchanger.

5. A pre-hydrogenation feed heat exchanger group according to claim 4, characterized in that: The shell side head (1.1) provided at the end of the cylinder (1) of the first stage pre-hydrogenation feed heat exchanger is welded to the side wall of the tube sheet (2); The bottom surface of the tube sheet (2) of the second-stage pre-hydrogenation feed heat exchanger is provided with a tube sheet shell side boss (2.2) with an arc structure around it, and the end of the cylinder (1) is provided with a shell side head (1.1) that is butted with the tube sheet shell side boss (2.2), and the shell side head (1.1) and the tube sheet shell side boss (2.2) are welded together.

6. A pre-hydrogenation feed heat exchanger group according to claim 5, characterized in that: A corrosion-resistant layer (6) is provided on the upper surface of the tube sheet (2) of the first-stage pre-hydrogenation feed heat exchanger; A corrosion-resistant layer (6) is provided on the inner wall of the conical structural member (3) of the second-stage pre-hydrogenation feed heat exchanger, the upper and lower surfaces of the tube sheet (2), and the inner wall of the cylinder (1).

7. A pre-hydrogenation feed heat exchanger group, characterized in that: A pre-hydrogenation feed heat exchanger as claimed in claim 2 comprising two groups cascaded with each other, wherein the material of the coils (4) of the first-stage pre-hydrogenation feed heat exchanger is duplex stainless steel, the material of the coils (4) of the second-stage pre-hydrogenation feed heat exchanger is austenitic stainless steel, the material medium enters the conical structure (3) of the second-stage coil heat exchanger after entering and exiting the shell side of the first-stage pre-hydrogenation feed heat exchanger, and the high-temperature medium enters the conical structure (3) of the first-stage pre-hydrogenation feed heat exchanger after entering the shell side of the second-stage pre-hydrogenation feed heat exchanger.

8. A pre-hydrogenation feed heat exchanger group, characterized in that: The invention comprises two groups of pre-hydrogenation feed heat exchangers as claimed in claim 2 which are cascaded to each other, the coils (4) of the first-stage pre-hydrogenation feed heat exchanger are made of duplex stainless steel, the coils (4) of the second-stage pre-hydrogenation feed heat exchanger are made of austenitic stainless steel, the material medium enters the shell side of the second-stage coil heat exchanger after entering and exiting the shell side of the first-stage pre-hydrogenation feed heat exchanger, and the high-temperature medium enters the conical structure (3) of the first-stage pre-hydrogenation feed heat exchanger after entering and exiting the conical structure (3) of the second-stage pre-hydrogenation feed heat exchanger.

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