Double-pipe-wall-surface efficient strip falling and devolatilization device and equipment applying same

Abstract

The utility model relates to a double-pipe wall surface high-efficiency strip-falling devolatilization device and equipment applying the same, the device comprises a gas-liquid separation chamber and a heat exchanger, the heat exchanger comprises a shell and a plurality of inner pipes arranged in the shell, the inner pipes are sleeved with outer pipes, annular gaps between the inner pipes and the outer pipes are open, the annular gaps are used for circulation of polymer materials, and the inner pipes are arranged in the shell. The first heating medium flows back in the inner pipe, the second heating medium is arranged between the outer pipe and the shell, and the annular space is communicated with the gas-liquid separation chamber. The device is not only suitable for the devolatilization working condition of polymers with small capacity or in a laboratory, but also can be used for the devolatilization working condition of large polymers.

Description

Technical Field

[0001] This utility model relates to the field of high-efficiency heat transfer technology, and in particular to a dual-tube wall high-efficiency strip devolve device and heat transfer method. This device is suitable for the devolve process of polymers with high thermal resistance and high viscosity. Background Technology

[0002] Heat transfer in high-viscosity, high-thermal-resistance systems has always been a challenge. For example, in the production of polymers, whether resins or polymeric plastics, devolatilization is generally involved. However, the devolatilization process is difficult to transfer heat to, and the high content of the light phase in the product has long constrained the development of similar processes.

[0003] Currently, there are generally two types of heat transfer equipment and methods used in the devolatilization process. One is static devolatilization, which mainly increases the heat transfer driving force by increasing the heat transfer temperature difference of the heat transfer equipment, such as flash devolatilization and traditional tube-and-tube devolatilization. Although increasing the heat transfer driving force alone can enhance heat transfer to a certain extent, it is limited by the high thermal resistance and high viscosity of the polymer itself. If the heat transfer distance is large, taking tube-and-tube heat transfer as an example, the heat is still difficult to reach the center of the fluid inside the tube, which is far from the heating wall. Chinese Patent CN116753750B discloses a preheating device and method for devolatilization of high-viscosity polymers. It is based on the traditional finned devolatilizer. The heat transfer method of this type of devolatilizer is to use the heating medium inside the tube as the primary indirect heat source and the fins as the secondary direct heat source to heat the polymer. Its heat transfer distance is only half the thickness of the fins, which effectively solves the drawback of the long heat transfer distance of traditional tube-and-tube heat transfer. However, the prerequisite for the normal operation of this type of devolatilizer is that the central chamber of the devolatilizer must be completely filled. This requires strict matching between the temperature of the heating medium and the viscosity of the material. Therefore, it is generally only used for devolatilization of systems containing less than 15% light content. Moreover, due to the influence of finned heat transfer efficiency, the central chamber of traditional finned strip devolatilizers is generally large, which also has the disadvantage of being difficult to clean due to blockage. Another method to enhance heat transfer for devolatilization is dynamic devolatilization, which uses agitation components, such as impellers, scrapers, and screws, to forcibly disturb the high-viscosity fluid. Although this heat transfer method increases heat transfer efficiency to a certain extent, it has many disadvantages, such as polymer adhesion to the walls, localized high-temperature thermoplasticization, small processing capacity during application, high manufacturing and maintenance costs, and difficulty in scaling up the processing capacity. It still fails to fundamentally solve the problem of polymer heat transfer.

[0004] Therefore, developing a new structure of a simple and efficient strip devolatilizer is crucial for polymer production. Utility Model Content

[0005] The purpose of this invention is to propose a high-efficiency stripping and devolve device with dual-tube walls and the equipment using it, in order to solve the problems of complex structure, limited adaptability and low devolve efficiency of existing polymer devolvers.

[0006] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0007] In a first aspect, this utility model provides a dual-tube wall high-efficiency strip desorption and devolatilization device, including a gas-liquid separation chamber and a heat exchanger. The heat exchanger includes a shell and a number of inner tubes disposed inside the shell. An outer tube is disposed outside the inner tubes. The annular gap between the inner and outer tubes is open and is used for the flow of polymer materials. A first heating medium refluxes in the inner tubes. A second heating medium is disposed between the outer tubes and the shell. The annular gap is connected to the gas-liquid separation chamber.

[0008] Furthermore, the heat exchanger also includes an upper tube sheet, a middle tube sheet, and a lower tube sheet arranged from top to bottom. The upper end of the inner tube is fixed on the upper tube sheet. A head is provided above the upper tube sheet. The space between the head and the upper tube sheet is the inner tube compartment. A baffle is provided in the inner tube compartment. An inlet and outlet of the first heating medium are respectively provided on both sides of the baffle. The first heating medium in the inner tube enters from its inlet and flows out from its outlet after heat exchange in the inner tube.

[0009] An outer tube is installed between the middle tube sheet and the lower tube sheet, and the area between the middle tube sheet and the upper tube sheet is the outer tube compartment.

[0010] A raw material inlet is installed on the side wall of the outer pipe compartment;

[0011] A shell-side inlet and a shell-side outlet for the second heating medium are provided on the shell in the area where the outer tube is located.

[0012] The lower tube sheet is fixedly connected to the gas-liquid separation chamber, which is provided with a polymer outlet d and a light phase outlet e.

[0013] Furthermore, the height of the outer tube chamber is 0.5-1.5 times the overall diameter of the heat exchanger; the polymer is at least one of polyolefin elastomer POE, polystyrene butadiene SBR, thermoplastic elastomer SEBS, ethylene-vinyl acetate copolymer EVA, or polypropylene PP.

[0014] Furthermore, baffles are installed within the space where the outer pipe is located.

[0015] Furthermore, the inner tube is a U-shaped tube or a tube with a cap at one end.

[0016] Furthermore, the annular gap width is 2-10mm, and there are no turbulent components within the annular gap.

[0017] Furthermore, the first heating medium and the second heating medium may be the same or different, preferably the first heating medium is heat transfer oil and the second heating medium is steam.

[0018] The heat transfer process of the device is as follows:

[0019] The first heating medium A, with a certain temperature and pressure, enters the inner tube chamber on one side from the inlet on the inner tube chamber, flows downward along the inner tube, turns around and flows upward into the inner tube chamber on the other side, and flows out from the outlet on the inner tube chamber.

[0020] The second heating medium B, with a certain temperature and pressure, enters from the shell-side inlet, flows around the material, and transfers heat to the material in the annular gap. The condensed second heating medium is then discharged from the shell-side outlet.

[0021] The polymer material to be heated enters from the raw material inlet on the side wall of the outer tube and undergoes initial liquid phase distribution under the disturbance of the inner tube. Then it enters the annular space between the inner and outer tubes, moves downward, and finally enters the gas-liquid separation chamber.

[0022] As the material moves downward along the annular gap, due to the annular gap design, the second heating medium on the outer tube side and the first heating medium on the inner tube side heat the material in the annular gap from both the outside and inside directions, making it easier to reach the center of the material. This provides the heat required for the vaporization of a large amount of light phase substances in the material, making it possible for the light phase liquid to completely vaporize. When the liquid material enters the gas-liquid separation chamber from the annular gap, the space suddenly expands, the gas phase separates from the liquid phase matrix and flows out from the light phase outlet, while the liquid phase falls to the bottom of the gas-liquid separation chamber under the action of gravity and is discharged from the material outlet.

[0023] Preferably, when the light phase content in the feed is less than 10 wt%, the annular gap width is 2-6 mm;

[0024] When the light phase content in the feed is greater than 10wt%, an annular gap width of 6-10mm is adopted.

[0025] Secondly, this utility model provides a devolatilization device, which uses the aforementioned apparatus. Preferably, it employs a multi-stage devolatilization process, comprising three stages: pre-devolatilization, primary devolatilization, and final devolatilization.

[0026] Compared with the prior art, the beneficial effects of this utility model are:

[0027] This utility model allows for the use of different heating media based on material properties, resulting in greater energy savings. When the outer tube is heated by steam, the heat transfer coefficient of the equipment is higher, the temperature is easier to control, and the cost of steam can be significantly reduced. The inner tube is heated by heat transfer oil at a higher temperature, requiring less oil and better preventing blockage of materials inside and outside the tube at the end of the inner tube.

[0028] 2. High applicability; the annular gap thickness can be adjusted by setting the inner and outer tube dimensions.

[0029] When the light phase content in the feed is low and the material viscosity is high, a small annular gap thickness can be used. At this time, the ultra-thin polymer annular liquid film provides a guarantee for more efficient devolatilization. Under certain operating conditions, the light phase in the final product can be reduced to below 200 PPM.

[0030] When the feed contains a high amount of light phase, the material viscosity is low, allowing for a large annular gap thickness. The liquid can then flow along the inner and outer pipe walls in a falling film manner, ensuring normal operation of the equipment and resulting in better heat transfer. However, the finned strip devolatilizer cannot function properly under these conditions.

[0031] 3. Low manufacturing cost. The heat transfer effect of this invention is not directly related to the diameter of the inner tube, but only to the thickness of the annular gap. Traditional shell-and-tube strip heat exchangers generally require small-diameter heat exchange tubes and internal inserts, resulting in high manufacturing costs and susceptibility to clogging.

[0032] 4. Minimal scale-up effect. This invention is suitable not only for small-scale or laboratory-scale polymer devolatilization but also for large-scale polymer devolatilization. This is because the tubular double-wall heating system allows for controllable tube count, a larger heat transfer area, a more compact size, and no scale-up effect. Traditional tubular strip devolatilizers are generally more suitable for small-scale production, while finned strip devolatilizers, due to the need for finned tubes to enclose the material space, are less suitable for laboratory or small-scale applications. Attached Figure Description

[0033] Figure 1 This is a cross-sectional structural schematic diagram of a dual-tube wall high-efficiency strip-falling and devolatilization device according to an embodiment of the present invention.

[0034] Figure 2 This is a partially enlarged schematic diagram of the inner and outer tubes.

[0035] In the diagram, 1 is the inner tube chamber, 2 is the outer tube chamber, 3 is the inner tube, 4 is the outer tube, 5 is the annular gap, 6 is the baffle plate, 7 is the upper tube sheet, 8 is the middle tube sheet, 9 is the lower tube sheet, 10 is the gas-liquid separation chamber, 11 is the baffle plate, a is the heat transfer oil inlet, b is the heat transfer oil outlet, c is the raw material inlet, d is the polymer outlet, e is the light phase outlet, f is the steam inlet, and g is the condensate outlet. Detailed Implementation

[0036] The present invention will be further explained below with reference to the embodiments and accompanying drawings, but this is not intended to limit the scope of protection of this application.

[0037] Example 1

[0038] This embodiment describes a dual-tube wall high-efficiency strip removal and devolatilization device (see...). Figure 1 The device includes a heat exchanger and a gas-liquid separation chamber;

[0039] The heat exchanger includes an inner tube chamber, an outer tube chamber, and inner and outer tubes for heat transfer, as well as an upper tube sheet, a middle tube sheet, and a lower tube sheet.

[0040] The inner tube is preferably a U-shaped tube, with its upper end connected to the upper tube plate 7. The outer diameter of the inner tube is slightly smaller than the inner diameter of the outer tube and is embedded in the outer tube 4. The two ends of the outer tube 4 are respectively connected to the middle tube plate 8 and the lower tube plate 9. Its inner diameter is slightly larger than the outer diameter of the inner tube and is fitted outside the inner tube.

[0041] The outer tube 4 is concentric with the inner tube 3. The width of the annular gap 5 between the two concentric circles corresponding to the inner diameter of the outer tube and the outer diameter of the inner tube is controlled at about 2-5mm. The upper end of the annular gap is connected to the outer tube compartment 2, and the lower end of the annular gap is connected to the gas-liquid separation chamber 10, forming the main channel for polymer flow and heat transfer.

[0042] The upper tube sheet 7 and its upper end cap form an inner tube compartment 1; the inner tube compartment 1 is provided with a partition 11, which divides the inner tube compartment into two independent chambers, which are respectively connected to the heat transfer oil inlet a and the heat transfer oil outlet b.

[0043] The upper tube sheet 7 and the middle tube sheet 8 are at a certain distance apart, forming an outer tube compartment 2 with the heat exchanger shell; a raw material inlet c is provided on the side wall of the outer tube compartment.

[0044] The middle tube sheet 8 and the lower tube sheet 9 are separated by a certain distance, and together with the outer tube 4 and the shell, they form the shell side of the heat exchanger. The shell side side wall is provided with a steam inlet f and a condensate outlet g.

[0045] The lower tube sheet 9 is connected to the gas-liquid separation chamber 10 via a flange; the gas-liquid separation chamber is provided with a polymer outlet d and a light phase outlet e.

[0046] The heat transfer process is as follows:

[0047] A first heating medium A (preferably heat transfer oil) with a certain temperature and pressure enters the inner tube chamber on one side from the heat transfer oil inlet, flows downward along the inner tube, turns through the U-shaped tube, flows upward into the inner tube chamber on the other side, and flows out of the equipment from the heat transfer oil outlet.

[0048] A second heating medium B (preferably steam) with a certain temperature and pressure enters the devolatilizer from the steam inlet in the shell side, and after flowing around, transfers heat to the material in the annular gap, while the condensate is discharged from the condensate outlet.

[0049] The polymer material to be heated enters from the material inlet on the side wall of the outer tube chamber, and undergoes initial liquid phase distribution under the disturbance of the inner tube (because the inner tube is evenly distributed in the outer tube chamber, it plays a disturbing role). Then it enters the annular space between the inner and outer tubes, moves downward, and finally enters the gas-liquid separation chamber.

[0050] During the downward movement of the material along the annular gap, in this embodiment, because the width of the annular gap is controlled at 2-5 mm, the latent heat of vapor on the outer tube side and the sensible heat of the heat transfer oil on the inner tube side can more easily reach the center of the material, thereby obtaining the heat required for the vaporization of a large amount of light phase substances within the material, making it possible for the light phase liquid to completely vaporize. When the liquid enters the gas-liquid separation chamber from the annular gap, the space suddenly expands, the gas phase separates from the liquid phase matrix and flows out from the light phase outlet, while the liquid phase falls to the bottom of the gas-liquid separation chamber under the action of gravity and is discharged from the material outlet.

[0051] Example 2

[0052] In this embodiment, a baffle is provided in the space of the outer tube area, heat transfer oil flows in the inner tube, polymer raw material flows in the annular gap, and steam heating is provided between the outer tube and the shell. The material is heated and volatilized from both the inside and outside directions, and the steam flows around the baffle for heat exchange.

[0053] Example 3

[0054] In this embodiment, the inner and outer tubes can also use the same fluid at different temperatures for heat exchange; the specific temperature difference can be determined according to the actual situation. The height of the outer tube compartment can be determined according to the throughput, and the height of the outer tube compartment is 0.5-1.5 times the overall diameter of the heat exchanger, preferably 0.5-1.0 times.

[0055] Example 4

[0056] In this embodiment, the inner tube is a tube with a lower end cap. The lower end cap of the inner tube is placed under the lower tube sheet, and the upper end of the inner tube is fixed to the upper tube sheet. The heating medium entering one side of the inner tube compartment enters the lower end cap of the inner tube through the inner tube, and flows out from the outlet on the other side of the inner tube compartment after reversing direction.

[0057] Example 5

[0058] In this embodiment, the polymer is polyolefin elastomer POE (or any of the high-viscosity systems such as polystyrene butadiene SBR, thermoplastic elastomer SEBS, ethylene-vinyl acetate copolymer EVA, and polypropylene PP). The POE high-efficiency devolatilization equipment includes three stages: pre-devolatilization, primary devolatilization, and fine devolatilization. The primary devolatilization and fine devolatilization stages can both be performed using the device described in Example 1.

[0059] Example 6

[0060] In this embodiment, the heat exchanger shell has a diameter of 200mm, an outer tube box height of 100mm, an outer tube inner diameter of 38mm, an inner tube inner diameter of 32mm, and an annular gap width of 3mm, enabling efficient polymer devolatilization at a rate of 1-5 kg / hour in the laboratory.

[0061] In the description of this specification, the specific features, structures, materials, or characteristics described in the embodiments are included in at least one embodiment of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiments. Furthermore, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments described in this specification and the features of the different embodiments.

[0062] The accompanying drawings of the embodiments disclosed in this utility model only involve the structures involved in the embodiments disclosed in this utility model. Other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of this utility model can be combined with each other.

[0063] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0064] Any aspects not covered in this utility model are applicable to the prior art.

Claims

1. A high-efficiency strip removal and devolatilization device with dual-tube walls, comprising a gas-liquid separation chamber and a heat exchanger, wherein the heat exchanger comprises a shell and a plurality of inner tubes disposed within the shell, characterized in that, An outer tube is fitted over an inner tube, and the annular gap between the inner and outer tubes is open. The annular gap is used for the flow of polymer materials. The first heating medium refluxes in the inner tube, and a second heating medium is provided between the outer tube and the shell. The annular gap is connected to the gas-liquid separation chamber.

2. The apparatus according to claim 1, characterized in that, The heat exchanger also includes an upper tube sheet, a middle tube sheet and a lower tube sheet arranged from top to bottom. The upper end of the inner tube is fixed on the upper tube sheet. A head is provided above the upper tube sheet. The space between the head and the upper tube sheet is the inner tube compartment. A partition is provided in the inner tube compartment. The inlet and outlet of the first heating medium are respectively provided on both sides of the partition. An outer tube is installed between the middle tube sheet and the lower tube sheet, and the area between the middle tube sheet and the upper tube sheet is the outer tube compartment. A raw material inlet is installed on the side wall of the outer pipe compartment; A shell-side inlet and a shell-side outlet for the second heating medium are provided on the shell in the area where the outer tube is located. The lower tube sheet is fixedly connected to the gas-liquid separation chamber, which is provided with a polymer outlet and a light phase outlet.

3. The apparatus according to claim 2, characterized in that, The height of the outer tube box is 0.5-1.5 times the overall diameter of the heat exchanger.

4. The apparatus according to claim 2, characterized in that, Baffles are installed in the space where the outer pipe is located.

5. The apparatus according to claim 1, characterized in that, The inner tube is a U-shaped tube or a tube with a cap at one end.

6. The apparatus according to claim 1, characterized in that, The annular gap width is 2-10mm, and there are no turbulent components inside the annular gap.

7. The apparatus according to claim 1, characterized in that, The first heating medium may be the same as or different from the second heating medium.

8. The apparatus according to claim 1, characterized in that, The polymer is at least one of the following: polyolefin elastomer POE, polystyrene butadiene SBR, thermoplastic elastomer SEBS, ethylene-vinyl acetate copolymer EVA, or polypropylene PP.

9. The apparatus according to claim 1, characterized in that, When the light phase content in the polymer feed is less than 10 wt%, the annular gap width is 2-6 mm; when the light phase content in the polymer feed is greater than 10 wt%, the annular gap width is 6-10 mm.

10. A devouring device, characterized in that, The device uses the apparatus described in any one of claims 1-7.

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