An integrated device of THF recovery system in PBT production process

Abstract

This utility model relates to the field of PBT production and discloses an integrated device for a THF recovery system in the PBT production process. It includes an integrated distillation column, a cyclone separator, and a reboiler. The integrated distillation column has a feed inlet in the middle, and its interior has a vertically connected azeotropic distillation dehydration chamber and a de-heavy component chamber. The cyclone separator is installed inside the integrated distillation column, connected to the feed inlet, and located between the azeotropic distillation dehydration chamber and the de-heavy component chamber. The reboiler is connected to the de-heavy component chamber. The liquid phase separated by the cyclone separator flows to the de-heavy component chamber to remove heavy component impurities with boiling points higher than THF, while the gas phase flows to the azeotropic distillation dehydration chamber to separate water azeotropes from THF. This utility model integrates a dehydration column and a pre-distillation column into a single distillation column, reducing the space occupied by the dehydration column and increasing the utilization rate of the plant space. The dual separation steps of the cyclone separator and the distillation column improve the dehydration and de-heavy component effects, reducing energy consumption.

Description

Technical Field

[0001] This utility model relates to the field of PBT production technology, and more specifically, to an integrated device for a THF recovery system in the PBT production process. Background Technology

[0002] In PBT production, THF (tetrahydrofuran) is the main byproduct generated during the esterification / polymerization stage. Therefore, a THF recovery system is established to recover and treat THF, thereby improving raw material utilization, reducing environmental pollution, and ensuring safety. Existing THF recovery systems include multiple devices such as dehydration towers, distillation towers, and reboilers. Mixtures containing THF first enter the dehydration tower to remove light components, and then enter the distillation tower to remove heavy components. The reboiler provides heat to the distillation tower. However, both the dehydration tower and the distillation tower are large and separate units. Some small to medium-sized PBT plants have limited space; to accommodate the installation of these towers, some factory or warehouse space is sacrificed, resulting in low plant space utilization and difficulty in deploying other supporting equipment. Utility Model Content

[0003] To address at least one of the aforementioned problems, this utility model provides an integrated device for a THF recovery system in PBT production, comprising an integrated distillation column, a cyclone separator, and a reboiler. The integrated distillation column has a feed inlet in its center. Inside the integrated distillation column, a vertically connected azeotropic distillation dehydration chamber and a de-heavy component chamber are arranged. The cyclone separator is installed inside the integrated distillation column and located between the azeotropic distillation dehydration chamber and the de-heavy component chamber. The cyclone separator is connected to the feed inlet for preliminary separation of the liquid and gas phases of the THF mixture. The reboiler is connected to the de-heavy component chamber to supply heat to the de-heavy component chamber, where the temperature is higher than that of the azeotropic distillation dehydration chamber. The liquid phase separated by the cyclone separator flows to the de-heavy component chamber to remove heavy component impurities with boiling points higher than that of THF, while the gas phase flows to the azeotropic distillation dehydration chamber to separate water azeotropes from the THF.

[0004] Optionally, the azeotropic distillation dehydration chamber is provided with a liquid collection tray and a bubble cap tray spaced apart in the vertical direction, with the bubble cap tray located above the liquid collection tray.

[0005] Optionally, the debinding and separating chamber is provided with multiple cross-flow trays at intervals along the vertical direction.

[0006] Optionally, the integrated device of the THF recovery system in the PBT production process also includes a molecular sieve adsorber, and the top of the integrated distillation column is provided with a dry steam outlet, which is connected to the molecular sieve adsorber.

[0007] Optionally, the integrated device of the THF recovery system in the PBT production process also includes the MVR steam compressor. The inlet of the MVR steam compressor is connected to the molecular sieve adsorber, and the outlet of the MVR steam compressor is connected to the reboiler. After separation and purification by the molecular sieve adsorber, the gas is pressurized and heated by the MVR steam compressor and then sent to the reboiler for condensation.

[0008] Optionally, the reboiler is connected to a gas-liquid separator, and the condensed liquid THF enters the gas-liquid separator. The gas-liquid separator is connected to the inlet of the MVR steam compressor, and the uncondensed gas re-enters the MVR steam compressor.

[0009] Optionally, the reboiler, the molecular sieve adsorber, and the MVR steam compressor are all located on the same side of the integrated distillation column and are arranged at intervals along the vertical direction.

[0010] Compared with the prior art, the beneficial technical effects of this utility model are as follows:

[0011] 1. The dehydration tower and the pre-distillation tower are integrated into a single integrated distillation tower. After the THF mixture enters the tower, it first passes through a cyclone separator for centrifugal separation, which can initially separate the liquid phase and the gas phase, as well as the heavy components and the light components. Then, the liquid phase and the gas phase, as well as the heavy components and the light components, are separated into the upper and lower sides of the tower. The upper and lower parts of the tower are respectively set as the azeotropic distillation dehydration chamber and the heavy component removal chamber, which further removes the light components and heavy components and performs deep dehydration. This reduces the space occupied by the dehydration tower, increases the utilization rate of the plant site, and ensures the dehydration and heavy component removal processes. The dual separation steps improve the dehydration and heavy component removal effect, reduce the number of cycles, and can reduce energy consumption to a certain extent.

[0012] 2. Molecular sieve adsorbers can further separate and purify impurities from the steam at the top of the distillation column. They have a strong adsorption capacity for polarized molecules (such as water and carbon dioxide) and a weaker adsorption capacity for non-polar molecules. This characteristic allows them to specifically remove harmful components and dehydrate. In addition, the adsorption process can be restored by heating or depressurization, allowing for recycling.

[0013] 3. The gas treated by the molecular sieve adsorber has a high THF purity. After being heated and pressurized by the MVR steam compressor, it enters the reboiler. Since there is a temperature difference between the reboiler and the heated and pressurized gas, the gas will condense into a liquid. During this process, the gas releases heat to provide some heat to the reboiler, thereby achieving the effect of energy saving. Attached Figure Description

[0014] Figure 1 This is a process flow diagram of the integrated device in the embodiments of this utility model;

[0015] Figure 2This is a cross-sectional view of the integrated distillation column in an embodiment of this utility model.

[0016] Explanation of reference numerals in the attached diagram: 1. Integrated distillation column; 11. Feed inlet; 12. Azeotropic distillation dehydration chamber; 13. De-weighting chamber; 14. Liquid collection tray; 15. Bubble cap tray; 16. Cross-flow tray; 17. Dry steam outlet; 2. Cyclone separator; 3. Reboiler; 4. Molecular sieve adsorber; 5. MVR steam compressor. Detailed Implementation

[0017] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the following description is provided in conjunction with the appendix. Figure 1-2 This application will be described in further detail.

[0018] This utility model embodiment provides an integrated device for a THF recovery system in the PBT production process, referring to... Figure 1 and Figure 2 The integrated THF recovery system in the PBT production process includes an integrated distillation column 1, a cyclone separator 2, and a reboiler 3. The integrated distillation column 1 has a feed inlet 11 in its middle. The cyclone separator 2 is installed inside the distillation column via a support frame, and is located at and connected to the feed inlet 11. Inside the integrated distillation column 1, a vertically connected azeotropic distillation dehydration chamber 12 and a de-heavy component chamber 13 are located on the upper and lower sides of the cyclone separator 2, respectively. The reboiler 3 is located on one side outside the integrated distillation column 1 and is connected to the de-heavy component chamber 13. The reboiler 3 provides heat to the integrated distillation column 1, and the temperature in the de-heavy component chamber 13 is higher than the temperature in the azeotropic distillation dehydration chamber 12. In the PBT production process, a solution containing a THF mixture is conveyed to inlet 11 via a pipeline, and then enters hydrocyclone 2. Hydrocyclone 2 utilizes the centrifugal force generated by the rotation of the fluid within a conical container to cause the heavy liquid components to move outwards and deposit along the wall, while the light gas components are discharged through the top, achieving preliminary separation of the liquid and gas phases of the THF mixture. The liquid phase after separation by hydrocyclone 2 flows to de-heavy component chamber 13 to remove heavy impurities with boiling points above THF, while the gas phase flows to azeotropic distillation and dehydration chamber 12 to separate water azeotropes from the THF. This dual separation process improves the efficiency of dehydration and de-heavy component removal, reduces the number of cycles, and lowers energy consumption.

[0019] Reference Figure 1 and Figure 2The cyclone separator 2 includes a cylindrical cylinder and a conical cylinder. The conical cylinder is located below and communicates with the cylindrical cylinder, and the cylindrical cylinder and the conical cylinder are welded together. An opening communicating with the feed inlet 11 is provided on the side wall of the cylindrical cylinder. When the THF mixture enters the cyclone separator at a certain pressure, the mixture enters tangentially from the cylinder, forming a rotating airflow. Within the cone, the airflow accelerates due to space contraction and rotation. The cylindrical cylinder, as the core area of ​​the airflow rotation, induces rotational motion through the tangential inlet, initially generating centrifugal force. The conical cylinder, through its contraction structure, enhances the airflow rotation speed and centrifugal force, while simultaneously extending the gas residence time to improve separation efficiency. Lighter gas components rise from the space in the middle of the cylindrical cylinder. The cyclone separator 2 has outlets at both the top and bottom, thus achieving a preliminary separation effect on the THF mixture. Since the cyclone separator 2 only achieves a preliminary separation effect through centrifugal force, the integrated distillation column 1 forms a high-temperature chamber through the reboiler 3, ensuring that the temperature in the de-heavy component chamber 13 is higher than the temperature in the azeotropic distillation dehydration chamber 12. After separation by cyclone separator 2, the light components have low boiling points and will volatilize in the azeotropic distillation dehydration chamber 12 due to azeotropic properties, thus achieving dehydration. The heavy components have high boiling points, so the temperature in the de-heavy component chamber 13 is also high. Cyclone separator 2 is installed inside the integrated distillation column 1 and does not occupy external space, therefore it does not affect the volume of the integrated distillation column 1.

[0020] Reference Figure 1 and Figure 2 Within the azeotropic distillation dehydration chamber 12, a liquid collection tray 14 (existing technology) and a bubble cap tray 15 (existing technology) are bolted together. The liquid collection tray 14 and bubble cap tray 15 are arranged vertically at intervals, with the bubble cap tray 15 positioned above the liquid collection tray 14. Two bubble cap trays 15 are arranged vertically at intervals. The light components separated by the cyclone separator 2 still contain a small amount of liquid phase (such as water vapor). Therefore, during the ascent, they first pass through the liquid collection tray 14, which provides a sufficient contact area for the gas and liquid phases. This promotes mass transfer (component exchange and heat transfer) to achieve the separation of the mixture, allowing any remaining liquid phase in the light components to be collected and condensed into water droplets, which finally drip into the dehydrated component chamber 13. The bubble cap tray 15 mainly consists of a riser pipe and a bubble cap. The bubble cap has serrations around its perimeter, allowing the gas to disperse into tiny bubbles, making it easier to separate the trace amounts of liquid phase in the light component gas, thus achieving the dehydration effect.

[0021] The de-weighting chamber 13 is vertically spaced with multiple cross-flow trays 16 (existing technology). The heavy liquid components drip under gravity, sequentially passing through the multiple cross-flow trays 16, while the heat generated by the reboiler 3 rises. During this process, the gas and liquid phases undergo counter-current cross-flow contact on the trays, achieving mass transfer (such as component exchange) and heat transfer. Simultaneously, the tray structure enhances the separation effect, ensuring thorough gas-liquid separation without entrainment, thus achieving the separation of substances with different boiling points from the heavy components. The separated liquid flows into the bottom of the integrated distillation column 1 and is then discharged for unified collection.

[0022] Reference Figure 1 and Figure 2 The integrated THF recovery system in the PBT production process also includes a molecular sieve adsorber 4 (existing technology, specific structure not described in detail), an MVR steam compressor 5 (existing technology, specific structure not described in detail), and a gas-liquid separator (not shown in the figure). The side wall at the top of the integrated distillation column 1 is provided with a dry steam outlet 17, which is connected to the azeotropic distillation dehydration chamber 12. The dry steam outlet 17 is also connected to the molecular sieve adsorber 4 via a pipe. The molecular sieve adsorber 4 can further separate and purify impurities from the steam at the top of the distillation column. The inlet of the MVR steam compressor 5 is connected to the molecular sieve adsorber 4 via a pipe, and the outlet of the MVR steam compressor 5 is connected to the reboiler 3 via a pipe. After separation and purification by the molecular sieve adsorber 4, the gas is pressurized and heated by the MVR steam compressor 5 and then transported to the reboiler 3 via a pipe to condense into liquid THF, which is then transported to the gas-liquid separator.

[0023] Specifically, the gas containing THF collects at the top of the azeotropic distillation dehydration chamber 12 and enters the molecular sieve adsorber 4 through the dry steam outlet 17. The molecular sieve adsorber 4 can further separate and purify impurities from the steam at the top of the distillation column. It has a strong adsorption capacity for polarized molecules (such as water and carbon dioxide) and a weak adsorption capacity for non-polar molecules. This characteristic allows it to specifically remove harmful components and dehydrate, further improving the purity of THF in the separated gas. In addition, the adsorption process of the molecular sieve adsorber 4 restores its adsorption capacity by heating or depressurization. The regeneration cycle of the molecular sieve adsorber 4 is 30-90 minutes, allowing for recycling. In this embodiment, the preferred regeneration cycle of the molecular sieve adsorber 4 is 45 minutes.

[0024] Reference Figure 1 and Figure 2The THF gas treated by the molecular sieve adsorber 4 has a high purity. The gas then enters the MVR steam compressor 5 through its inlet. The MVR steam compressor 5 pressurizes and heats the gas, raising its temperature above that of the reboiler 3. The MVR steam compressor 5 then delivers the pressurized and heated gas to the reboiler 3. At this point, the temperature difference between the reboiler 3 and the pressurized and heated gas causes the gas to condense into liquid THF, making it easier to store. During the condensation process of the THF gas in the reboiler 3, heat is released, thus providing some heat to the reboiler 3 and achieving energy savings.

[0025] Reference Figure 1 and Figure 2 The gas-liquid separator is connected to reboiler 3 via a pipe and is internally connected to reboiler 3. Therefore, the condensed THF enters the gas-liquid separator through the pipe. The gas-liquid separator is connected to the inlet of MVR steam compressor 5 via a pipe, and is also connected to a product storage tank (not shown in the figure) via another pipe. When liquid THF enters the gas-liquid separator, some of the uncondensed gas also enters the gas-liquid separator. The gas that is not condensed into liquid will be recirculated through the pipe to the inlet of MVR steam compressor 5 under the action of the gas-liquid separator; the condensed liquid flows into the product storage tank through the corresponding pipe for use.

[0026] It is worth noting that the reboiler 3, molecular sieve adsorber 4, and MVR steam compressor 5 are all located on the same side of the integrated distillation column 1. The molecular sieve adsorber 4 is located above the MVR steam compressor 5, and the reboiler 3 is located below the MVR steam compressor 5. The reboiler 3, molecular sieve adsorber 4, and MVR steam compressor 5 are all connected to the same steel frame. In this way, multiple devices are arranged and integrated together in the vertical direction through a compact layout, which can reduce the land area occupied by the factory and increase the utilization rate of the factory site.

[0027] The hydrocyclone separator 2, molecular sieve adsorber 4, MVR steam compressor 5, and gas-liquid separator are all existing technologies, so their specific structures will not be described further.

[0028] The implementation principle of the integrated device for THF recovery system in PBT production according to an embodiment of this application is as follows: the dehydration tower and the pre-distillation tower are integrated into an integrated distillation tower 1. The volume of the molecular sieve adsorber 4 is much smaller than that of the dehydration tower. The reboiler 3, the molecular sieve adsorber 4, and the MVR steam compressor 5 are all connected and integrated on the same steel frame and arranged vertically, reducing the space occupied by the dehydration tower and the corresponding connecting pipes, and reducing the horizontal space occupied by the corresponding equipment. After the THF mixture enters the tower, it will first pass through the cyclone separator 2 for preliminary separation, and then be separated again under the action of the temperature difference between the azeotropic distillation dehydration chamber 12 and the de-weighting chamber 13, the liquid collection tray 14, the bubble cap tray 15, and the cross-flow tray 16. The de-heavy component chamber 13 is used to remove heavy component impurities with a boiling point higher than that of THF. The gas phase flows to the azeotropic distillation dehydration chamber 12 to separate water azeotropes from THF. Then, the gas in the molecular sieve adsorber 4 adsorbs moisture and impurities again, improving the purity of the gas THF. After being heated and pressurized by the MVR steam compressor 5, the gas enters the reboiler 3. Since there is a temperature difference between the reboiler 3 and the heated and pressurized gas, the gas will condense into a liquid. During this process, the gas releases heat to provide some heat to the reboiler 3, thus achieving an energy-saving effect.

[0029] Similarly, the components included in the "components," "mechanisms," and "devices" of this disclosure can also be flexibly combined. They can be modularly produced according to actual needs and assembled as an independent module; or they can be assembled separately to form a module in this device. The division of the above-mentioned components in this disclosure is only one embodiment for ease of reading and is not intended to limit the scope of protection of this disclosure. Any technical solution that includes the above-mentioned components and has the same function should be understood as an equivalent technical solution of this disclosure.

[0030] In the description of this disclosure, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this disclosure.

[0031] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0032] In this disclosure, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this disclosure according to the specific circumstances.

[0033] In this disclosure, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0034] It should be noted that when a component is referred to as "fixed to," "set on," "fixed to," or "mounted on" another component, it can be directly on the other component or there may be an intervening component. When a component is considered to be "connected to another component," it can be directly connected to the other component or there may be an intervening component. Furthermore, when a component is considered to be "fixedly connected" to another component, the connection can be detachable or non-detachable, such as through socketing, snap-fitting, integral molding, welding, etc., which are achievable in conventional technologies and will not be elaborated upon here.

[0035] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0036] The above embodiments are merely illustrative of several implementation methods of this disclosure, and their descriptions are relatively specific and detailed. However, they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the inventive concept of this disclosure, and these modifications and improvements all fall within the protection scope of this disclosure.

Claims

1. An integrated device for a THF recovery system in the PBT production process, characterized in that: The system includes an integrated distillation column (1), a cyclone separator (2), and a reboiler (3). The integrated distillation column (1) has a feed inlet (11) in its middle section. The integrated distillation column (1) has a vertically connected azeotropic distillation dehydration chamber (12) and a deweighting chamber (13). The cyclone separator (2) is installed inside the integrated distillation column (1) and located between the azeotropic distillation dehydration chamber (12) and the deweighting chamber (13). The cyclone separator (2) is connected to the feed inlet (11) to facilitate distillation. The liquid and gas phases of the THF mixture are initially separated. The reboiler (3) is connected to the de-heavy component chamber (13) to supply heat to the de-heavy component chamber (13). The temperature in the de-heavy component chamber (13) is higher than the temperature in the azeotropic distillation dehydration chamber (12). The liquid phase after separation by the cyclone separator (2) flows to the de-heavy component chamber (13) to remove heavy component impurities with a boiling point higher than that of THF. The gas phase flows to the azeotropic distillation dehydration chamber (12) to separate water azeotropes in THF.

2. The integrated device for the THF recovery system in the PBT production process according to claim 1, characterized in that: The azeotropic distillation dehydration chamber (12) is provided with a liquid collection tray (14) and a bubble cap tray (15) spaced apart in the vertical direction, with the bubble cap tray (15) located above the liquid collection tray (14).

3. The integrated device for the THF recovery system in the PBT production process according to claim 1, characterized in that: The debinding and recombining chamber (13) is provided with multiple cross-flow trays (16) at intervals along the vertical direction.

4. The integrated device for the THF recovery system in the PBT production process according to claim 1, characterized in that: It also includes a molecular sieve adsorber (4), and the top of the integrated distillation column (1) is provided with a dry steam outlet (17), which is connected to the molecular sieve adsorber (4).

5. The integrated device for the THF recovery system in the PBT production process according to claim 4, characterized in that: It also includes an MVR steam compressor (5), the inlet of which is connected to the molecular sieve adsorber (4), and the outlet of which is connected to the reboiler (3). After being separated and purified by the molecular sieve adsorber (4), the gas is pressurized and heated by the MVR steam compressor (5) and then transported to the reboiler (3) for condensation.

6. The integrated device for the THF recovery system in the PBT production process according to claim 5, characterized in that: The reboiler (3) is connected to a gas-liquid separator. After condensation, the liquid THF enters the gas-liquid separator. The gas-liquid separator is connected to the inlet of the MVR steam compressor (5). The uncondensed gas re-enters the MVR steam compressor (5).

7. The integrated device for the THF recovery system in the PBT production process according to claim 5, characterized in that: The reboiler (3), the molecular sieve adsorber (4), and the MVR steam compressor (5) are all located on the same side of the integrated distillation column (1) and are arranged at intervals along the vertical direction.

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