A tubular reactor for polyethylene high pressure reaction

Abstract

The utility model relates to a kind of tubular reactor for polyethylene high pressure reaction, belong to industrial reactor technical field.The reactor includes reaction tube, and the inner wall of reaction tube is coated with nano coating, and the pipe wall of reaction tube is equipped with perspective window.By coating nano coating on the inner wall of reaction tube, nano coating hardness is extremely high, surface is fine and smooth, with good thermal stability, the effect of high temperature and high pressure resistance is good, can exist stably under ethylene polymerization reaction condition, and molten polyethylene is not easy to adhere to the surface of nano coating, so that the probability of molten state polyethylene adhering on the inner wall of reaction tube is lower, with the perspective window on the pipe wall of reaction tube, staff can directly view polyethylene adhesion condition of reaction tube inner section, to directly judge whether polyethylene adhesion fouling occurs in reaction tube.

Description

Technical Field

[0001] This utility model belongs to the field of industrial reactor technology, and specifically relates to a tubular reactor for high-pressure polyethylene reaction. Background Technology

[0002] Industrially, high-pressure polyethylene reactors are mainly divided into tubular reactors and batch reactors. Tubular reactors are more commonly used; they consist of multiple seamless steel pipes connected in series, with a total length reaching hundreds of meters (typically 100-300 meters). The inner diameter is usually 20-100 mm. The reactor is divided into a preheating section, a reaction section, and a cooling section, and is externally jacketed (or shell-side), using heat exchange through heat transfer oil, water, or steam. The pipe sections are connected by elbows. There is no internal stirring device; the material is propelled by a high-pressure pump, flowing at a high speed of 5-20 m / s, approaching a plug flow state.

[0003] High-pressure polyethylene tubular reactors offer advantages such as high single-pass conversion rates, suitability for large-scale production, and lower equipment investment and maintenance costs. However, in existing tubular reactors, polyethylene easily adheres to the tube walls, forming scale, which reduces heat transfer efficiency and tube diameter. Several methods have been developed to prevent polyethylene adhesion to the tube walls, including: 1. minimizing the time to reach peak temperature; 2. adding sufficient modifiers; 3. maintaining normal air injection volume and reducing the switching time of the standby air compressor; 4. switching to a product with a relatively high melt index; 5. increasing the hot water temperature in the reaction section; 6. increasing the pulse depth of the reactor discharge pulse valve to flush out more ethylene and polyethylene; and 7. precision machining the inner wall of the high-pressure polyethylene reactor to a surface roughness Ra of 0.15 μm.

[0004] However, all of the above methods are not ideal in solving the problem of molten polyethylene sticking to the wall. Moreover, existing high-pressure polyethylene tubular reactors can only indirectly determine whether molten polyethylene sticks to the wall and the degree of sticking by monitoring temperature, pressure and flow rate, and by using some acoustic or vibration sensors during the production process. They cannot directly determine the sticking situation. Utility Model Content

[0005] This invention provides a tubular reactor for high-pressure polyethylene reaction, which solves the technical problem that existing methods are not effective in dealing with molten polyethylene sticking to the reactor walls and cannot directly determine the degree of polyethylene sticking to the reactor walls.

[0006] This utility model is achieved through the following technical solution: a tubular reactor for high-pressure reaction of polyethylene, comprising a reaction tube, the inner wall of the reaction tube being coated with a nano-coating, and a viewing window being installed on the wall of the reaction tube.

[0007] Furthermore, in order to better realize this utility model, the nano-coating is nano-ceramic.

[0008] Furthermore, in order to better realize this utility model, an external protrusion is fixed on the outer wall of the reaction tube, and a straight through hole communicating with the reaction tube is opened on the end face of the external protrusion away from the reaction tube.

[0009] It also includes a pressure cap, which is detachably and fixedly connected to the outer protrusion, and the pressure cap has a viewing hole corresponding to the through hole;

[0010] The viewing window is press-fitted between the pressure cap and the outer protrusion, and the viewing window covers the through hole.

[0011] Furthermore, in order to better realize this utility model, the pressure cap is fixed to the outer protrusion by bolts.

[0012] Furthermore, to better realize this utility model, the perspective window includes:

[0013] The mounting base is attached to and covers the end face of the outer protrusion away from the reaction tube. The center of the end of the mounting base away from the outer protrusion is provided with a mounting groove, and the bottom of the mounting groove is provided with a through hole corresponding to the straight hole.

[0014] A transparent plate is placed in the mounting slot and covers the through hole;

[0015] The pressure block is provided with an insertion head adapted to the mounting groove. The insertion head is inserted into the mounting groove and abuts against the transparent plate. The pressure block is pressed against the mounting base by the pressure cover. The pressure block has a through hole that penetrates the insertion head. The through hole, the through hole and the viewing hole are coaxially arranged.

[0016] Furthermore, in order to better realize this utility model, the transparent plate includes a flat plate area and a spherical area located in the middle of the flat plate area. The flat plate area is pressed against the bottom of the mounting groove by the pressure block, and the spherical area protrudes towards the pressure block and extends into the through hole.

[0017] Furthermore, in order to better realize this utility model, a first sealing ring is installed between the flat plate area and the bottom of the mounting groove.

[0018] Furthermore, in order to better realize this utility model, a positioning ring is provided on the end face of the outer protrusion away from the reaction tube, and a positioning protrusion is provided on the outer wall of the mounting base, and the positioning protrusion is inserted into the positioning ring.

[0019] Furthermore, in order to better realize this utility model, a second sealing ring is installed between the positioning convex ring and the outer convex block.

[0020] Furthermore, in order to better realize this utility model, a positioning groove adapted to the pressure block is provided on the end face of the pressure cap near the reaction tube;

[0021] The end of the pressure block opposite to the reaction tube is inserted into the positioning groove.

[0022] Compared with the prior art, this utility model has the following advantages:

[0023] The tubular reactor for high-pressure polyethylene reaction provided by this utility model has a nano-coating on the inner wall of the reaction tube. The nano-coating has extremely high hardness, a delicate and smooth surface, good thermal stability, and good resistance to high temperature and high pressure. It can exist stably under the conditions of ethylene polymerization reaction, and molten polyethylene does not easily adhere to the surface of the nano-coating, thus reducing the probability of molten polyethylene adhering to the inner wall of the reaction tube. With the help of the viewing window on the wall of the reaction tube, the staff can directly observe the polyethylene adhesion in the internal sections of the reaction tube, thereby directly determining whether polyethylene adhesion and scaling have occurred inside the reaction tube. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the structure of a tubular reactor section for high-pressure polyethylene reaction provided in this embodiment of the utility model;

[0026] Figure 2 yes Figure 1 A cross-sectional view of the structure shown;

[0027] Figure 3 yes Figure 2 The local square of region A in the middle is the same;

[0028] Figure 4 yes Figure 1 The exploded view of the structure shown is without the first and second sealing rings assembled.

[0029] Figure 5 This is a schematic diagram of the mounting base in an embodiment of the present utility model;

[0030] Figure 6This is a schematic diagram of the structure of the transparent plate in an embodiment of this utility model;

[0031] Figure 7 This is a schematic diagram of the structure of the pressure plate in an embodiment of this utility model;

[0032] Figure 8 This is a schematic diagram of the structure of the pressure cap in an embodiment of this utility model.

[0033] In the picture:

[0034] 100 - Reaction tube, 200 - Nano coating, 300 - Viewing window, 310 - Mounting base, 311 - Positioning ring, 320 - Transparent plate, 321 - Flat plate area, 322 - Spherical area, 330 - Pressure block, 331 - Insertion head, 400 - Outer protrusion, 410 - Positioning ring, 500 - Pressure cap, 510 - Positioning groove, 600 - Bolt, 700 - First sealing ring, 800 - Second sealing ring. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be described in detail below. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0036] Example:

[0037] like Figures 1-8 As shown, the tubular reactor for high-pressure polyethylene reaction provided in this embodiment includes a reaction tube 100 (the reaction tube 100 is composed of several tube sections spliced ​​together; it should be noted that...). Figure 1The diagram shows a schematic of the tube section. The inner wall of the reaction tube 100 is coated with a nano-coating 200, and a viewing window 300 is installed on the tube wall. The nano-coating 200 has extremely high hardness, a smooth and delicate surface, good thermal stability, and excellent resistance to high temperature and pressure. It can exist stably under the conditions of ethylene polymerization reaction, and molten polyethylene does not easily adhere to the surface of the nano-coating 200, thus reducing the probability of molten polyethylene adhering to the inner wall of the reaction tube 100. In particular, when combined with the method mentioned in the background art, the problem of polyethylene adhesion inside the reaction tube 100 can be solved more thoroughly. With the help of the viewing window 300 on the tube wall of the reaction tube 100, the operator can directly observe the polyethylene adhesion in the internal sections of the reaction tube 100, thereby directly determining whether polyethylene adhesion and scaling have occurred inside the reaction tube 100. It should be noted that multiple viewing windows 300 are provided along the length of the reaction tube 100. Specifically, based on experience, the locations in the reaction tube 100 where polyethylene adhesion is likely to occur are first located, and one viewing window 300 is provided at each location.

[0038] Optionally, the aforementioned nano-coating 200 is a nano-ceramic. It is worth noting that nano-ceramics are existing technology. Of course, without considering cost, the aforementioned nano-coating 200 can also be a silicon-based nano-coating or a fluorine-based nano-coating.

[0039] Optionally, an external protrusion 400 is integrally formed on the outer wall of the reaction tube 100. The end face of the external protrusion 400 facing away from the reaction tube 100 has a through hole communicating with the reaction tube 100. A pressure cap 500 is detachably and fixedly connected to the external protrusion 400. The pressure cap 500 has a viewing hole corresponding to the through hole. The viewing window 300 is press-fitted between the pressure cap 500 and the external protrusion 400, and the viewing window 300 covers the through hole. When the pressure cap 500 is removed from the external protrusion 400, the viewing window 300 can be easily disassembled and assembled. As another embodiment of this invention, in this embodiment, an opening is made in the tube wall of the reaction tube 100, and a transparent plate is embedded in the opening.

[0040] The aforementioned external protrusion 400 is actually an external flange, while the aforementioned gland 500 is a flange cover. The gland 500 is bolted and fixed to the external protrusion 400 by bolts 600. Of course, if the external protrusion 400 is not an external flange, but a round pipe, then the gland 500 is not a flange cover, but a round cover, and the gland 500 is connected to the external protrusion 400 by screwing.

[0041] Optionally, the aforementioned viewing window 300 includes a mounting base 310, a transparent plate 320, and a pressure block 330, wherein:

[0042] The mounting base 310 is attached to and covers the end face of the outer protrusion 400 opposite to the reaction tube 100, forming a through hole. A mounting groove is formed at the center of the end of the mounting base 310 opposite to the outer protrusion 400, and a through hole corresponding to the through hole is formed at the bottom of the groove. The transparent plate 320 is placed in the mounting groove and covers the through hole. The pressure block 330 is provided with an insertion head 331 adapted to the mounting groove. The insertion head 331 is inserted into the mounting groove and abuts against the transparent plate 320. The pressure block 330 is pressed against the mounting base 310 by the pressure cap 500, and the pressure block 330 has a through hole penetrating the insertion head 331. The through hole, the through hole, and the viewing hole are coaxially arranged.

[0043] In this way, the cap 500, the pressure block 330, the transparent plate 320, the mounting base 310, and the outer protrusion 400 are stacked together, and the insertion head 331 of the viewing window 300 and the pressure block 330 is embedded in the mounting base 310. The cap 500, which is bolted to the outer protrusion 400 by bolts 600, presses the pressure block 330 tightly against the transparent plate 320, so that the transparent plate 320 is pressed tightly against the bottom of the mounting groove of the mounting base 310, and the mounting base 310 is pressed tightly against the outer protrusion 400, thereby ensuring the stable installation of the transparent plate 320. Moreover, the side wall of the mounting groove also provides protection for the transparent plate 320. Through the viewing hole, the transparent plate 320, and the through hole, a portion of the area inside the reaction tube 100 can be seen.

[0044] Of course, the aforementioned viewing window 300 can also be simply a transparent plate. In this case, the aforementioned cover 500 directly presses the transparent plate onto the aforementioned outer protrusion 400 and covers the through hole of the aforementioned outer protrusion 400.

[0045] To better observe the situation inside the reaction tube 100, in this embodiment, the transparent plate 320 includes a flat plate area 321 and a spherical area 322 located in the middle of the flat plate area 321. The flat plate area 321 is pressed against the bottom of the mounting groove by a pressure block 330, thereby achieving better compression. The spherical area 322 protrudes towards the pressure block 330 and extends into the through hole, forming a convex lens, thus making it easier for staff to observe the situation inside the reaction tube 100.

[0046] Of course, the aforementioned transparent panel 320 can also be a flat sheet of material.

[0047] In order to prevent leakage from the gap between the transparent plate 320 and the bottom of the mounting groove of the mounting base 310, in this embodiment, a first sealing ring 700 is installed between the plate area 321 and the bottom of the mounting groove.

[0048] Optionally, a positioning ring 410 is provided on the end face of the outer protrusion 400 away from the reaction tube 100, and a positioning protrusion 311 is provided on the outer wall of the mounting base 310. The positioning protrusion 311 is inserted into the positioning ring 410, so that the mounting base 310 is positioned on the outer protrusion 400, so that the entire viewing window 300 is more securely connected to the reaction tube 100.

[0049] To better prevent leakage, in this embodiment, a second sealing ring 800 is installed between the positioning protrusion 311 and the outer wall of the outer protrusion 400.

[0050] Optionally, a positioning groove 510 adapted to the pressure block 330 is provided on the end face of the pressure cap 500 near the reaction tube 100. The end of the pressure block 330 away from the reaction tube 100 is inserted into the positioning groove 510, thereby positioning the pressure block 330 on the pressure cap 500. In this way, the connection between the viewing window 300 and the reaction tube 100 can be made more secure.

[0051] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope described in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the protection scope of the claims.

Claims

1. A tubular reactor for high-pressure reaction of polyethylene, comprising a reaction tube (100), characterized in that, The inner wall of the reaction tube (100) is coated with a nano-coating (200), and a viewing window (300) is installed on the wall of the reaction tube (100).

2. The tubular reactor for high-pressure polyethylene reaction according to claim 1, characterized in that: The nano-coating (200) is a nano-ceramic.

3. The tubular reactor for high-pressure reaction of polyethylene according to claim 1 or 2, characterized in that: An external protrusion (400) is fixed on the outer wall of the reaction tube (100), and a through hole communicating with the reaction tube (100) is opened on the end face of the external protrusion (400) away from the reaction tube (100). It also includes a pressure cap (500), which is detachably and fixedly connected to the outer protrusion (400), and the pressure cap (500) has a viewing hole corresponding to the through hole; The viewing window (300) is press-fitted between the cover (500) and the outer protrusion (400), and the viewing window (300) covers the through hole.

4. The tubular reactor for high-pressure reaction of polyethylene according to claim 3, characterized in that: The pressure cap (500) is bolted to the outer protrusion (400) by bolts (600).

5. The tubular reactor for high-pressure reaction of polyethylene according to claim 3, characterized in that, The perspective window (300) includes: The mounting base (310) is attached to and covers the straight hole at the end face of the outer protrusion (400) away from the reaction tube (100). The center of the end of the mounting base (310) away from the outer protrusion (400) is provided with a mounting groove, and the bottom of the mounting groove is provided with a through hole corresponding to the straight hole. A transparent plate (320) is placed in the mounting slot and covers the through hole; The pressure block (330) is provided with an insertion head (331) adapted to the mounting groove. The insertion head (331) is inserted into the mounting groove and abuts against the transparent plate (320). The pressure block (330) is pressed against the mounting base (310) by the pressure cover (500). The pressure block (330) has a through hole that penetrates the insertion head (331). The through hole, the through hole and the viewing hole are coaxially arranged.

6. The tubular reactor for high-pressure polyethylene reaction according to claim 5, characterized in that: The transparent plate (320) includes a flat plate area (321) and a spherical area (322) located in the middle of the flat plate area (321). The flat plate area (321) is pressed against the bottom of the mounting groove by the pressure block (330). The spherical area (322) protrudes towards the pressure block (330) and extends into the through hole.

7. The tubular reactor for high-pressure reaction of polyethylene according to claim 6, characterized in that: A first sealing ring (700) is installed between the flat plate area (321) and the bottom of the mounting groove.

8. The tubular reactor for high-pressure reaction of polyethylene according to claim 7, characterized in that: The outer protrusion (400) has a positioning ring (410) protruding on one end face away from the reaction tube (100), and a positioning protrusion (311) is provided on the outer wall of the mounting base (310), and the positioning protrusion (311) is inserted into the positioning ring (410).

9. The tubular reactor for high-pressure reaction of polyethylene according to claim 8, characterized in that: A second sealing ring (800) is installed between the positioning convex ring (311) and the outer protrusion (400).

10. The tubular reactor for high-pressure reaction of polyethylene according to claim 5, characterized in that: The end face of the cap (500) near the reaction tube (100) is provided with a positioning groove (510) that is adapted to the pressure block (330); The end of the pressure block (330) facing away from the reaction tube (100) is inserted into the positioning groove (510).

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