Serial pipe reactor with segmented jackets

Abstract

The utility model relates to the technical field of petrochemical equipment, in particular to a serial pipe reactor with segmented jackets, which comprises a plurality of straight casing pipes, a plurality of bent pipes and jacket communicating pipes, each straight casing pipe comprises an inner pipe and an outer pipe, and the inner pipe is arranged in the outer pipe in a penetrating manner to form an annular straight jacket runner; and the inner pipes of the plurality of straight sleeves are connected in series through a bent pipe to form a medium flow channel for conveying and reacting reaction materials. The outer pipe of each straight sleeve is divided into more than two outer pipe sections, and a sealing structure is formed between the two end parts of each outer pipe section and the inner pipe, so that the straight jacket flow channel is divided into more than two independent jacket sections, and the jacket communicating pipe is used for connecting the transversely corresponding jacket sections of the plurality of straight sleeves in series. As the height of the jacket is reduced, the pressure loss of a fluid medium in the jacket is reduced, and the energy consumption is reduced; the structure stress is reduced, the purpose of lightweight design is achieved, timely and accurate regulation and control are facilitated, the balance of fluid flowing through the jacket is guaranteed, and the purpose of stable reaction of media in the inner pipe is achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of petrochemical equipment, and particularly relates to a string tube reactor with a segmented jacket. Background Art

[0002] In the prior art, polyolefins (such as polypropylene and polyethylene) are the varieties with the largest production and consumption in general synthetic resins. The common production technologies of polyolefins usually include three types: slurry process, gas phase process, and solution process. The so-called slurry process (Slurry Process), also known as the slurry method or solvent process method, is the earliest process technology used to produce polypropylene in the world. The slurry process technology is the main method for producing HDPE. The production process is as follows: propylene or ethylene is mixed with a hydrocarbon solvent, and the produced polymer is suspended in the solvent. The industrial application time of the slurry method is earlier, the process technology is mature, and the pressure and temperature during the production process are relatively low. According to the reactor form, the reaction equipment used in the slurry process can be divided into two types: stirred tank reactor and string tube reactor.

[0003] In the prior art, a common string tube reactor generally includes several straight sleeve pipes set according to production capacity, as well as corresponding jacket connecting pipes, elbows, mounting supports, connecting beams, etc. The straight sleeve pipes include an inner pipe and an outer pipe. The ends of the elbows are connected in series with the ends of the inner pipe in sequence to form a communicating flow channel for the transportation and reaction of reaction materials. Since heat is generated during the polymerization reaction, a jacket flow channel is formed between the inner pipe and the outer pipe of the straight sleeve pipe. The jacket connecting pipe is connected to the outer pipe to connect the jacket flow channels in series to form a communicating flow channel for transporting the cooling medium. The reaction heat is carried away by the cooling medium in the jacket flow channel. A corrugated expansion joint, a mounting support, and a support beam seat are arranged on the outer pipe of the straight sleeve pipe. The connecting beam is connected to the support beam seat by bolts to combine the straight sleeve pipes into a three-dimensional framework. Since the string tube reactor is supported by multiple bases, that is, each straight sleeve pipe is provided with a corresponding mounting support for support, errors in the length, axial position, orientation, elevation, spacing, etc. of the straight sleeve pipes, as well as many factors such as the parallelism of the straight sleeve pipes, the perpendicularity of the flanges, and the manufacturing errors of the elbows, will all affect the installation and sealing performance of the loop pipe at the same time; moreover, the string tube reactor is made of low-temperature steel, and has high requirements for manufacturing, welding, and heat treatment. In order to make the material flow smoothly in the straight sleeve pipe, the inner wall of the inner pipe must be polished multiple times to be close to a mirror surface to prevent the reactants from sticking to the wall and causing explosion polymerization.

[0004] For example, the structure of a string tube reactor for producing 300,000 tons / year of polypropylene is as Figure 1As shown in the figure, it is mainly composed of six straight sleeves (the first straight sleeve R1, the second straight sleeve R2, the third straight sleeve R3, the fourth straight sleeve R4, the fifth straight sleeve R5, and the sixth straight sleeve R6) each with a length of 50m and an outer diameter of φ609.6×16mm, five 180° large elbows (the first elbow A1, the second elbow A2, the third elbow A3, and two elbows at the bottom), and a 90° elbow connected in sequence to form a circular whole. And through five outer elbows connected to the outer pipe at the inner elbow, it is located on a higher platform foundation. An axial flow pump is provided at the inner elbow at the bottom of the string of pipes. The reaction material enters the string reactor from the reaction material inlet 1A, is stirred and circulated in the pipe driven by the axial flow pump, and reacts under the action of the catalyst to form polypropylene in slurry form, which is discharged from the reaction material outlet 1B and enters the granulation system; the cooling medium enters from the cooling medium inlet of the jacket flow channel and flows out from the cooling medium outlet of the jacket flow channel. Six mounting supports are located at the lower parts of the straight sleeves R1, R2, R3, R4, R5, and R6. There are five jacket connecting pipes connecting the jackets to each other. The cooling water in the jacket takes away the heat released by the reaction in the inner pipe through the partition wall to maintain the normal operation of the reaction process. This string reactor is located on a platform foundation 11m high, and the whole equipment weighs about 210 tons. In order to coordinate the difference in thermal expansion displacement caused by different temperatures between the inner pipe and the outer pipe, expansion joints are attached to the jacket; expansion joints, support beam seats and supports are also attached to the jacket. Adjacent jackets are connected by steel sections to form eight space platforms.

[0005] With the depletion of petroleum resources, in order to meet the huge demand and development of the market for ethylene special materials, new and more stringent requirements have been put forward for the structure, production capacity and quality of the string reactor equipment. With the further expansion of the production capacity scale, the body structure of the string reactor in the above-mentioned existing technology is getting higher and higher, and the latitude of the location where the reactor is installed and operated is also getting higher. Due to the integral slender vertical structure of the straight sleeves, when these factors are combined, the following deficiencies will occur:

[0006] At present, the production capacity of a single polyethylene and polypropylene string reactor has been increased to 300,000 tons / year and 350,000 tons / year, and higher production capacity process technologies are under research and development. This large-scale competition method has faced two development bottlenecks. One is the transformation from the incremental market to the stock market, and the other is the energy conservation and environmental protection applicability of the original technology. Reflected in the main structural dimensions, the lengths of the straight pipes with jackets of polypropylene and polyethylene string reactors have been extended to more than 60 meters and 70 meters respectively, as Figure 2 shown in the schematic diagram of two straight sleeves, elbows and a jacket connecting pipe. The inner pipes of the two jacket pipes are connected in series through the elbows at the top. The cooling water in the jacket is as Figure 2As shown by the solid arrow, the cooling water enters from the jacket inlet C1, flows upward from one of the straight sleeves C4, passes through the flow path of the jacket connecting pipe C3 into the jacket of the other straight sleeve C5, and flows out from the jacket outlet C2. It can be seen that the travel of the cooling water almost covers the sum of the lengths of all the straight sleeves, and the rising height of the cooling water is approximately equal to the overall height of the straight sleeves. Although continuously developing a higher multi-tube reactor is beneficial to increasing the production capacity of the inner tube and achieving a more complete reaction, the energy consumption of the jacket water is higher, and the increase in static water pressure leads to new problems such as seal maintenance. Therefore, the multi-tube reactor requires technological innovation to meet the engineering requirements. Summary of the Invention

[0007] In view of all or part of the above technical problems existing in the prior art, the present utility model provides a multi-tube reactor with a segmented jacket.

[0008] To achieve the above object, the present utility model provides the following technical solutions:

[0009] Provided is a multi-tube reactor with a segmented jacket, including a plurality of straight sleeves, a plurality of bent pipes, and a jacket connecting pipe. Each straight sleeve includes an inner tube and an outer tube, and the inner tube is disposed through the outer tube to form an annular straight jacket flow path; the inner tubes of the plurality of straight sleeves are connected in series via the bent pipes to form a medium flow path for conveying reaction materials and carrying out reactions; the characteristics are:

[0010] The outer tubes of each straight sleeve are separated into two or more outer tube segments, and sealing structures are formed between the two ends of each outer tube segment and the inner tube, thereby partitioning the straight jacket flow path into two or more jacket segments. Jacket inlets and outlets are provided at the ends of each jacket segment, and the jacket connecting pipe connects the horizontally corresponding jacket segments of the plurality of straight sleeves in series to form two or more cooling flow paths for conveying cooling media.

[0011] As a further optional solution, the number of outer tube segments of each straight sleeve is two, corresponding to an upper jacket segment and a lower jacket segment. Between two adjacent straight sleeves: the upper jacket segments of each other and the lower jacket segments of each other are respectively connected in series via the jacket connecting pipe.

[0012] As a further optional solution, the diameters and wall thicknesses of the upper jacket segment and the lower jacket segment are the same or different.

[0013] As a further optional solution, the jacket inlets and outlets of each jacket segment are one or more than two, thereby forming single-in single-out interfaces, single-in double-out, single-in multi-out, double-in single-out, multi-in multi-out, or multi-in single-out interfaces.

[0014] As a further optional solution, for different jacket segments of the same straight sleeve, the flow directions of the cooling water therein are the same or different.

[0015] As a further optional solution, the cooling water in the jacket segment flows in the same direction as or countercurrently to the medium in the inner tube.

[0016] As a further optional solution, the jacket inlets and outlets of each jacket segment of the same straight casing are connected to a collecting pipe.

[0017] As a further optional solution, a normally closed spare connecting pipe is provided between adjacent jacket sections of the same straight casing, and the spare connecting pipe is provided with a stop valve.

[0018] As a further optional solution, the straight sleeve separates the straight jacket flow channel via the connecting pipe seat, and the jacket inlet and outlet are arranged at the connecting pipe seat.

[0019] As a further optional solution, the outer pipe of the jacket segment and / or the jacket connecting pipe are provided with an expansion joint.

[0020] Beneficial effects of the utility model:

[0021] Compared with the prior art, the utility model has the following advantages:

[0022] (1) The cooling water flow rate delivered to the upper jacket, especially the top jacket of the reactor, is reduced, which reduces the pressure loss of the fluid medium in the jacket, thereby reducing energy consumption and achieving the purpose of cost saving in long-term operation;

[0023] (2) As the jacket height is reduced, the cooling water static pressure borne by the sealing structure at the bottom of the upper jacket and the sealing structure at the bottom of the lower jacket is also reduced, thereby reducing the structural stress, thinning the jacket wall thickness and the thickness of the bottom sealing structure, and eliminating the reinforcement ribs of the bottom ring sealing plate, thereby achieving the purpose of lightweight design;

[0024] (3) Due to the reduction of the static pressure of the cooling water in the jacket, the sealing possibility of the jacket inlet and outlet connections is significantly improved, which facilitates maintenance work and achieves the purpose of reliable operation;

[0025] (4) Compared with the long jacket process, the thermal expansion difference between the inner tube and the jacket tube is reduced during operation in the short jacket process, and the thermal expansion stress between the two adjacent jacket sections can offset each other. The multi-wave expansion joints that must be set on the super-long jacket can be eliminated, or only a single-wave expansion joint is required, thereby achieving the purpose of simplifying the structure and reducing equipment costs;

[0026] (5) Compared with the long jacket process, the short jacket process is more convenient for timely and precise regulation, ensuring the balance of the fluid flowing through the jacket, and achieving the goal of stable reaction of the inner tube medium and uniform product quality.

[0027] Further:

[0028] A connecting pipe with a stop valve is arranged between the two disconnected sections of the jacket. When necessary, this valve can also be opened, and the original cooling water interface of the jacket at this place can be closed to achieve the series connection between the sections of the jacket, so as to achieve the purpose of flexible operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 FIG. is a schematic diagram of an existing string-tube reactor.

[0030] Figure 2 FIG. is a schematic connection diagram between two straight sleeve pipes of an existing string-tube reactor.

[0031] Figure 3 FIG. is a schematic connection structure diagram between two straight sleeve pipes of a string-tube reactor with a segmented jacket in an embodiment.

[0032] Figure 4 FIG. is a schematic diagram of the first embodiment of the upper jacket segmentation and the lower jacket segmentation.

[0033] Figure 5 FIG. is a schematic diagram of the second embodiment of the upper jacket segmentation and the lower jacket segmentation.

[0034] Figure 6 FIG. is a schematic diagram of the third embodiment of the upper jacket segmentation and the lower jacket segmentation.

[0035] Figure 7 FIG. is another schematic connection diagram between two straight sleeve pipes of a string-tube reactor with a segmented jacket in an embodiment.

[0036] Figure 8 FIG. is a schematic diagram of a nozzle seat in an embodiment.

[0037] Figure 9 FIG. is a perspective view of a nozzle seat in an embodiment.

[0038] Reference Signs:

[0039] Straight sleeve pipe 1, elbow 2, jacket connecting pipe 3, expansion joint 4, spare connecting pipe 5, stop valve 6, manifold 7;

[0040] Inner pipe 11, outer pipe 12, outer pipe segment 121, ring plate 122, upper jacket segment 13, lower jacket segment 14, jacket inlet 15, jacket outlet 16. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0042] A string-tube reactor with a segmented jacket in this embodiment is combined with Figure 1、 Figure 3 and Figure 4 As shown, it includes multiple straight sleeves 1, multiple bent pipes 2 and jacket connecting pipes 3. Each straight sleeve 1 includes an inner pipe 11 and an outer pipe 12. The inner pipe 11 is inserted into the outer pipe 12 to form an annular straight jacket flow channel; the inner pipes 11 of the multiple straight sleeves 1 are connected in series through the bent pipes 2 to form a medium flow channel for transporting reaction materials and reacting.

[0043] The above is the basic structure of the existing series-tube reactor. The series-tube reactor of this embodiment also has these basic structures, and the following improvements are made:

[0044] The outer tube 12 of each straight casing 1 is divided into two outer tube segments 121, and a sealing structure is formed between the two ends of each outer tube segment 121 and the inner tube 11 ( Figure 4 Specifically, the ring plate 122 is welded and sealed), thereby dividing the straight jacket flow channel into two independent jacket segments, which correspond to the upper jacket segment 13 and the lower jacket segment 14 in the figure. The upper and lower ends of each jacket segment are provided with a jacket inlet 15 and a jacket outlet 16. The jacket connecting pipe 3 connects the corresponding jacket segments of different straight pipes in series to form two or more cooling flow channels for conveying cooling medium. That is, between two adjacent straight pipes 1: the upper jacket segment 13 is connected in series via the jacket connecting pipe 3. The lower jacket segment 14 is connected in series via another jacket connecting pipe 3.

[0045] like Figure 3 As shown, for the lower jacket sections 14 of the two straight sleeves 1, the cooling medium enters from the jacket inlet 15 of the right lower jacket section 14, passes from bottom to top through the middle jacket connecting pipe 3 into the left lower jacket section 14, and then flows out from the left jacket outlet 16. Similarly, for the upper jacket sections 13 of the two straight sleeves 1, the cooling medium flows in the direction of the solid arrow.

[0046] Figure 4 The inner tube 11 of the straight jacket 1 is also divided into two parts, which are sealed by flanges. Figure 5 As shown, the difference is that the inner tube 11 is a continuous integral structure.

[0047] Specifically, the diameter and wall thickness of the upper jacket segment 13 and the lower jacket segment 14 may be the same or different. The number and location of the jacket segments of each straight jacket tube 1 in the same reactor can be the same to ensure that the cooling water is pumped to the same height and a water pump with appropriate power can be selected. However, the number and location of the jacket segments may be different if necessary.

[0048] Specifically, each jacket segment has one or more jacket inlet 15 and jacket outlet 16, thereby forming a single-inlet-single-outlet interface, a single-inlet-double-outlet interface, a single-inlet-multiple-outlet interface, a double-inlet-single-outlet interface, a multiple-inlet-multiple-outlet interface or a multiple-inlet-single-outlet interface.

[0049] Specifically, for different jacket segments of the same straight sleeve, the flow direction of the cooling water inside them can be the same or different. The cooling water in the jacket segments flows in the same direction as or countercurrently to the medium in the inner pipe.

[0050] Specifically, the outer pipe 12 of the jacket segment and / or the jacket connecting pipe 3 are provided with expansion joints 4, preferably single-wave expansion joints. Compared with the long jacket process, for the short jacket process, the thermal expansion difference between the inner pipe 11 and the outer pipe 12 during operation is reduced, and the thermal expansion stresses between adjacent two jacket segments can cancel each other out. The multi-wave expansion joints that must be provided on the ultra-long jacket can be cancelled, or only single-wave expansion joints need to be provided, so as to achieve the purpose of simplifying the structure and reducing the equipment cost.

[0051] As Figure 6 In the illustrated embodiment, a normally closed standby connecting pipe 5 is provided between adjacent jacket segments of the same straight sleeve 1. The joints of the standby connecting pipe 5 should be staggered from the jacket inlet 15 and the jacket outlet 16. The standby connecting pipe 5 is provided with a stop valve 6. Generally, the standby connecting pipe 6 is cut off during normal operation, and it can also be used to achieve the series connection of different jacket segments of the same straight sleeve when necessary, such as draining water during the parking process, cleaning the impurities and dirt in the jacket, purging and protection, etc., to achieve flexibility.

[0052] As Figure 7 In the illustrated embodiment, the jacket inlets and outlets of each jacket segment of the same straight sleeve 1 are connected in a converging manner to a collecting pipe 7. The jacket inlet 15 at the bottom of the lower jacket segment 14 and the bottom of the upper jacket segment 13 is bifurcated and connected by the same collecting pipe 7, and the jacket outlet 16 at the bottom of the lower jacket segment 14 and the bottom of the upper jacket segment 13 is also connected by another collecting pipe 7 respectively.

[0053] For the sealing of the end of the outer pipe segment 121, adjacent jacket segments of the same straight sleeve 1 can be connected through a nozzle seat as shown in Figure 8 and Figure 9 The structure of the nozzle seat can specifically refer to the technology disclosed in the Chinese patent document with the publication number CN117781739A to realize the independent segmentation of the outer pipe while the inner pipes are connected. The jacket inlets and outlets are arranged on the nozzle seat.

[0054] In the description of the present utility model, obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all embodiments. The components of the embodiments of the present utility model described and illustrated herein can be arranged and designed in various different configurations.

[0055] Therefore, the detailed description of the embodiments of the present invention provided in the drawings above is not intended to limit the scope of the present invention claimed, but merely represents selected embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0056] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "inside", "upper", "lower", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the inventive product is customarily placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive distinction and should not be construed as indicating or implying relative importance.

[0057] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "arranged", "connected", "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection. It can be a mechanical connection or an electrical connection. It can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

Claims

1. A string tube reactor with a segmented jacket, comprising a plurality of straight tubes, a plurality of bent tubes and jacket connecting pipes. Each straight tube includes an inner tube and an outer tube, and the inner tube is inserted through the outer tube to form an annular straight jacket flow channel; the inner tubes of the plurality of straight tubes are connected in series via the bent tubes to form a medium flow channel for conveying reaction materials and carrying out reactions; characterized in that: The outer tubes of each straight tube are separated into two or more outer tube segments, and sealing structures are formed between the two ends of each outer tube segment and the inner tube, so as to partition the straight jacket flow channel into two or more jacket segments. Jacket inlets and outlets are provided at the ends of each jacket segment, and the jacket connecting pipes connect the horizontally corresponding jacket segments of the plurality of straight tubes in series to form two or more cooling flow channels for conveying cooling medium.

2. The string tube reactor with a segmented jacket according to claim 1, wherein: The number of outer tube segments of each straight tube is two, corresponding to the upper jacket segment and the lower jacket segment. Between two adjacent straight tubes: the upper jacket segments of each other and the lower jacket segments of each other are connected in series via the jacket connecting pipes respectively.

3. A string tube reactor with a segmented jacket according to claim 2, characterized in that: The diameters and wall thicknesses of the upper jacket segment and the lower jacket segment are the same or different.

4. A string tube reactor with a segmented jacket according to claim 1, characterized in that: The jacket inlets and outlets of each jacket segment are one or more than two, so as to form single-in single-out interfaces, single-in double-out, single-in multi-out, double-in single-out, multi-in multi-out or multi-in single-out interfaces.

5. A string tube reactor with a segmented jacket according to claim 1, characterized in that: For different jacket segments of the same straight tube, the flow directions of the cooling water inside are the same or different.

6. The string tube reactor with a segmented jacket according to claim 1, characterized in that: The cooling water in the jacket segment flows in the same direction as or counterflows to the medium in the inner tube.

7. A tube-in-tube reactor with a segmented jacket according to claim 1, characterized in that: The jacket inlets and outlets of each jacket segment of the same straight tube are connected in a converging manner to a collecting pipe.

8. A string tube reactor with a segmented jacket according to claim 1, characterized in that: Normally closed standby connecting pipes are provided between adjacent jacket segments of the same straight tube, and stop valves are provided on the standby connecting pipes.

9. A tube-in-tube reactor with a segmented jacket according to claim 1, characterized in that: The straight jacket flow channel is partitioned by the straight tube via a nozzle seat, and the jacket inlets and outlets are provided on the nozzle seat.

10. A string tube reactor with a segmented jacket according to claim 1, characterized in that: Expansion joints are provided on the outer tube and / or the jacket connecting pipe of the jacket segment.

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