A device for separating diphenyl from a cyclohexane dehydrogenation product

Abstract

The application belongs to the technical field of chemical production, and particularly relates to a biphenyl separation device for cyclohexane dehydrogenation products. The application provides a biphenyl separation device for cyclohexane dehydrogenation products, which comprises a heavy component removal tower and a collection unit, and the overhead vapor phase discharge port of the heavy component removal tower is connected with the collection unit. In the technical scheme provided by the application, the heavy component removal tower is used to separate biphenyl from other components in the cyclohexane dehydrogenation products according to the difference in boiling points, and the remaining gaseous components are discharged from the overhead vapor phase discharge port of the heavy component removal tower into the collection unit. The heavy component removal tower can realize batch and large-scale separation of biphenyl in the cyclohexane dehydrogenation products, and has the advantages of low energy consumption and high separation precision. The biphenyl separation device for cyclohexane dehydrogenation products provided by the application solves the technical defects of high energy consumption and low separation precision in the cyclohexane dehydrogenation process.

Description

Technical Field

[0001] This application belongs to the field of chemical production technology, and in particular relates to a biphenyl separation device for cyclohexane dehydrogenation products. Background Technology

[0002] Cyclohexane, an important organic solvent and chemical raw material, is mainly produced through reactions such as partial dehydrogenation of benzene, hydration of cyclohexene, and dehydrogenation of cyclohexanol to produce the intermediate product cyclohexanone, which is then further reacted to obtain cyclohexane. During cyclohexanone production, 20-25% of the byproduct cyclohexane is generated, resulting in a benzene utilization rate of only 75-80%. To improve benzene utilization, a cyclohexane dehydrogenation process can directly convert the byproduct cyclohexane from the cyclohexanone unit into benzene and hydrogen. The benzene and hydrogen are then recycled as feedstock, effectively utilizing the byproduct cyclohexane. This achieves a closed-loop cycle of feedstock and product within the unit, resulting in a green, environmentally friendly, efficient, energy-saving, and waste-free process. Simultaneously, it reduces the cost of purchasing and transporting benzene and the load on the associated hydrogen production unit.

[0003] In the existing technology, the production equipment for cyclohexane dehydrogenation to benzene has problems such as insufficient heating of raw materials, small dehydrogenation benzene production per batch, and increased costs during the dehydrogenation to benzene production operation. This results in high separation energy consumption, low separation accuracy, and a large amount of high-quality steam used in the reboiler.

[0004] Therefore, the development of a biphenyl separation device for cyclohexane dehydrogenation products to address the technical shortcomings of high energy consumption and low separation accuracy in the existing cyclohexane dehydrogenation to benzene process has become an urgent problem for those skilled in the art. Utility Model Content

[0005] Therefore, it is necessary to address the technical shortcomings of the existing cyclohexane dehydrogenation to benzene process, which suffers from high energy consumption and low separation accuracy in product separation, and to provide a biphenyl separation device for the cyclohexane dehydrogenation product.

[0006] This application provides a biphenyl separation device for the dehydrogenation product of cyclohexane. The biphenyl separation device includes a de-heavy column and a collection unit. The top gas outlet of the de-heavy column is connected to the collection unit. The de-heavy column has a theoretical plate number of not less than 20. The de-heavy column includes a rectification section and a stripping section. The stripping section has a theoretical plate number of not less than 15. The rectification section of the de-heavy column includes structured packing, and the stripping section of the de-heavy column includes valve trays.

[0007] In one embodiment, the theoretical number of trays in the deweighting tower is not less than 25.

[0008] In one embodiment, the biphenyl separation device further includes: a distillation column, the feed inlet of which is connected to the liquid outlet of the bottom of the de-heavy column, the liquid phase at the top of the de-heavy column being connected to the collection unit, and the theoretical number of plates of the distillation column being not less than 10.

[0009] In one embodiment, the deweight removal tower includes a packed tower and / or a plate tower.

[0010] In one embodiment, the number of theoretical plates in the deweighting tower is not less than 30, and the number of theoretical plates in the stripping section of the deweighting tower is not less than 20.

[0011] In one embodiment, the distillation column includes structured packing.

[0012] In one embodiment, the deweight removal tower further includes a first reboiler, which is a thermosiphon reboiler and / or a forced circulation reboiler.

[0013] In one embodiment, the deweight removal column further includes a first reboiler, and the distillation column further includes a second reboiler;

[0014] The first reboiler is a thermosiphon reboiler and / or a forced circulation reboiler, and the second reboiler is a forced circulation reboiler.

[0015] In one embodiment, the biphenyl separation device further includes a condenser disposed between the top gas outlet of the deweighting tower and the collection unit.

[0016] In one embodiment, the packing of the deweight removal column includes any one or more of MELLAPAK 250Y, 350Y, 500Y, and 750Y, and the packing of the distillation column includes any one or more of MELLAPAK 250Y, 350Y, 500Y, and 750Y.

[0017] In one embodiment, the biphenyl separation device further includes a biphenyl detection component, which is disposed at the outlet of the liquid phase at the top of the de-weighting tower, and the outlet of the liquid phase at the top of the de-weighting tower is connected to the inlet of the de-weighting tower.

[0018] In summary, this application provides a biphenyl separation device for cyclohexane dehydrogenation products. The biphenyl separation device includes a de-heavy phase tower and a collection unit, with the top gaseous outlet of the de-heavy phase tower connected to the collection unit. In the technical solution provided by this application, the boiling point difference between biphenyl (the impurity to be removed) and other components in the cyclohexane dehydrogenation products is utilized. The de-heavy phase tower separates the biphenyl from the top gaseous outlet of the de-heavy phase tower into the collection unit. The de-heavy phase tower can achieve batch and large-scale separation of biphenyl from cyclohexane dehydrogenation products, offering advantages such as low separation energy consumption and high separation accuracy. The biphenyl separation device for cyclohexane dehydrogenation products provided by this application solves the technical defects of high product separation energy consumption and low separation accuracy in the existing cyclohexane dehydrogenation to benzene process. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application 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 embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0020] Figure 1 A schematic diagram of the structure of a biphenyl separation device for cyclohexane dehydrogenation products provided in the embodiments of this application;

[0021] Figure 2 A schematic diagram of the structure of a biphenyl separation device for cyclohexane dehydrogenation products provided in the embodiments of this application;

[0022] Figure 3 A schematic diagram of the structure of a biphenyl separation device for cyclohexane dehydrogenation products provided in the embodiments of this application;

[0023] The components include a deweighting tower T1, a distillation tower T2, a first reboiler E1, a second reboiler E2, and a condenser E3. Detailed Implementation

[0024] This application provides a biphenyl separation device for cyclohexane dehydrogenation products, which solves the technical defects of high energy consumption and low separation accuracy in the existing cyclohexane dehydrogenation to benzene process.

[0025] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0026] In the description of this application, 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", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application 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, and therefore should not be construed as a limitation of this application.

[0027] Furthermore, the terms "first" and "second" 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 as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0028] In this application, 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 application according to the specific circumstances.

[0029] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature 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.

[0030] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0031] In the technical solutions provided in this application, the cyclohexane dehydrogenation product specifically refers to a liquid phase product containing the main product benzene and impurities cyclohexane and biphenyl. The biphenyl separation device provided in this application is for removing biphenyl from the aforementioned liquid phase product to obtain the main product benzene.

[0032] Specifically, the process for producing benzene from cyclohexane via dehydrogenation is as follows: Under a certain reaction temperature (280–330°C), pressure (slight positive pressure 10–100 kPaG), and catalyst (supported Pt or other noble metal catalyst), the cyclohexane dehydrogenation reaction to produce benzene occurs in a cyclohexane dehydrogenation reactor, directly converting cyclohexane into benzene and hydrogen. The product from the cyclohexane dehydrogenation reactor is flash-evaporated and condensed. The gaseous hydrogen is collected separately after compression, and the liquid phase component is processed by the biphenyl separation device provided in the embodiments of this application. The liquid phase components in the embodiments of this application are all obtained from the above-described cyclohexane dehydrogenation process for producing benzene, and will not be described further hereafter.

[0033] In the technical solution provided in this application embodiment, the liquid phase component of the cyclohexane dehydrogenation product mainly includes: benzene, the main product after dehydrogenation, unreacted cyclohexane, and biphenyl, a dehydrogenation byproduct. If the liquid phase component obtained from cyclohexane dehydrogenation is directly reused as a raw material, the biphenyl byproduct will reduce the catalytic conversion rate and selectivity of the cyclohexanone preparation process, and will not improve the conversion rate of benzene.

[0034] Please see here. Figure 1 This application provides a biphenyl separation device for cyclohexane dehydrogenation products, including: a de-heavy column T1 and a collection unit. The top gas outlet of the de-heavy column T1 is connected to the collection unit. The de-heavy column T1 has a theoretical plate number of not less than 20. The de-heavy column T1 includes a rectification section and a stripping section, wherein the stripping section has a theoretical plate number of not less than 15. The rectification section of the de-heavy column T1 includes structured packing, and the stripping section of the de-heavy column T1 includes valve trays.

[0035] In the technical solution provided in this application embodiment, the liquid phase component of the cyclohexane dehydrogenation product passes through the de-weighting tower T1. Taking advantage of the fact that the boiling point of biphenyl in the liquid phase component is significantly higher than that of benzene and cyclohexane, the de-weighting tower T1 can efficiently remove biphenyl from the liquid phase component. At this time, the benzene and cyclohexane that have been de-biphenyl removed escape from the gas phase outlet at the top of the de-weighting tower T1 and enter the collection unit for collection.

[0036] At this point, the benzene (containing a small amount of cyclohexane) in the collection unit can be directly utilized as a raw material, effectively improving the conversion and utilization rate of benzene in the cyclohexane synthesis route from benzene. Testing shows that the benzene content in the collection unit can reach over 92% using the biphenyl separation device provided in this application embodiment. The technical solution provided in this application embodiment, utilizing the boiling point difference to achieve separation in the heavy metal removal tower T1, effectively ensures high separation accuracy while also having the advantage of low separation energy consumption, thus solving the technical defects of high product separation energy consumption and low separation accuracy in the cyclohexane dehydrogenation to benzene process.

[0037] exist Figure 1 In this process, stream 1 is the liquid phase component of the cyclohexane dehydrogenation product. After weight removal, the collected overhead gas stream 3 is the benzene-cyclohexane mixture after biphenyl removal. Stream 2 is the heavy liquid phase component in the bottom of the column after weight removal, mainly composed of biphenyl. Stream 3 can be reused as a raw material for the preparation of cyclohexane from benzene, or it can be used for other purposes; no restrictions are placed here.

[0038] Please refer to this section for further information. Figure 2 The biphenyl separation device for cyclohexane dehydrogenation products provided in this application embodiment further includes: a distillation column T2, the inlet of which is connected to the liquid outlet of the bottom of the de-heavy phase removal column T1, and the top liquid phase of the de-heavy phase removal column T1 is connected to a collection unit. The theoretical plate number of the distillation column T2 is not less than 10. In the distillation column T2, the liquid phase components collected in the de-heavy phase removal column T1 are further purified, and the unseparated benzene in the bottom liquid phase after de-heavy phase removal is further collected. The top liquid phase collected after distillation and the top gas phase collected after de-heavy phase removal together complete the recovery and reuse of benzene. Testing shows that the top liquid phase after distillation can reach a benzene content of over 96%.

[0039] This section further combines Figure 2 To explain, Figure 2 In the process, stream 1 is the liquid phase component of the cyclohexane dehydrogenation product. After weight removal, the collected overhead gas stream 3 is the light component purge gas from the top of the column after weight removal. Stream 4 is a benzene-cyclohexane mixture after biphenyl removal (mainly benzene). Stream 2 is the heavy liquid phase component (biphenyl, benzene, etc.) from the bottom of the column after weight removal. Stream 2 is further distilled. The overhead liquid stream 6 after distillation is benzene, and the bottom liquid stream 5 is a heavy component mainly composed of biphenyl. Figure 1Logistics 6 and 4 can be reused as raw materials for the preparation of cyclohexane from benzene, or they can be used for other purposes, without any restrictions.

[0040] From the above Figure 1 and Figure 2 It can be concluded that the biphenyl separation device provided in the embodiments of this application can be a single-tower separation structure including only the heavy removal tower T1, or a dual-tower separation structure of heavy removal tower T1 + distillation tower T2, which can be adjusted according to actual production needs.

[0041] In the technical solution provided in this application embodiment, the heavy removal tower T1 includes a packed tower and / or a plate tower. The packed tower provides a gas-liquid mass transfer interface through the packing material (such as structured packing or random packing) inside the tower, and is suitable for the separation of high-precision, heat-sensitive materials or low-load conditions. It has the advantages of high separation efficiency, large operational flexibility, small liquid holdup, and simple structure and convenient maintenance. The plate tower achieves mass transfer through gas-liquid bubbling or jet contact on the tower plate, and is suitable for high-flow-rate, high-load conditions or conditions containing suspended solids. It has the advantages of large processing capacity suitable for high-load conditions, good stability and strong adaptability, low cost, and strong controllability of heat and mass transfer.

[0042] Furthermore, the rectification section of the heavy removal tower T1 includes structured packing, and the stripping section of the heavy removal tower T1 includes floating valve trays, which effectively improves the separation effect of the heavy removal tower T1 on biphenyl.

[0043] To better optimize the separation effect of the heavy removal tower T1, in the technical solution provided in this application embodiment, the theoretical number of trays of the heavy removal tower T1 is not less than 30, and the theoretical number of trays of the stripping section of the heavy removal tower T1 is not less than 20.

[0044] In the technical solution provided in this application embodiment, the distillation column T2 includes structured packing. The structured design of the structured packing in distillation column T2 significantly improves the separation efficiency and operational performance of distillation column T2 through an ordered gas-liquid contact interface, a low-resistance mass transfer path, and flexible parameter adjustability. It can effectively improve separation efficiency to a very high degree, better adapt to wide load fluctuations, reduce the risk of material retention, and has a compact structure, saving space and reducing investment.

[0045] In order to provide the heat required for vaporization to the bottom liquid of the deweight removal tower T1 and maintain the mass and heat transfer balance between the gas and liquid phases in the tower, the deweight removal tower T1 further includes a first reboiler E1 in the technical solution provided in the embodiments of this application. The first reboiler E1 is a thermosiphon reboiler and / or a forced circulation reboiler.

[0046] Similarly, in order to provide the heat required for vaporization to the bottom liquid of the de-weighting tower T1 and the distillation tower T2 respectively, and to maintain the mass and heat transfer balance between the gas and liquid phases in the tower, the technical solution provided in the embodiments of this application further includes a first reboiler E1 for the de-weighting tower T1 and a second reboiler E2 for the distillation tower T2; the first reboiler E1 is a thermosiphon reboiler and / or a forced circulation reboiler, and the second reboiler E2 is a forced circulation reboiler.

[0047] Specifically, please refer to this link. Figure 1 and Figure 2 , Figure 1 and Figure 2 The diagram illustrates the feed streams processed by the first reboiler E1 and the second reboiler E2. In the deweighting column T1, the feed stream 11 from the reboiler is processed by the first reboiler E1 to obtain the reboiler output stream 12, which then re-enters the deweighting step to provide heat. Similarly, in the distillation step, the feed stream 13 from the reboiler is processed by the second reboiler E2 to obtain the reboiler output stream 14, which then re-enters the distillation step to provide heat.

[0048] To further optimize the technical solution, the biphenyl separation device provided in this application embodiment also includes a condenser E3, which is located between the top gaseous outlet of the de-weighing tower T1 and the collection unit. The top gaseous stream of the de-weighing tower T1 can be condensed by the condenser 3 and enter the collection unit in a liquid state. The resulting liquid stream has a small volume, which facilitates collection by the collection unit and improves the safety and stability of the biphenyl separation device operation.

[0049] To further optimize the technical solution, while ensuring good separation effect of the deweight removal tower T1 and the distillation tower T2, the preparation cost economy of the deweight removal tower T1 and the distillation tower T2 and the convenience of daily maintenance of the packing are considered. In the technical solution provided in the embodiments of this application, the packing of the deweight removal tower T1 includes any one or more of MELLAPAK 250Y, 350Y, 500Y and 750Y, and the packing of the distillation tower T2 includes any one or more of MELLAPAK 250Y, 350Y, 500Y and 750Y.

[0050] Please refer to this section for further information. Figure 3 In the technical solution provided in this application embodiment, the biphenyl separation device further includes a biphenyl detection component, which is disposed at the outlet of the liquid phase at the top of the deweighting tower T1, and the outlet of the liquid phase at the top of the deweighting tower T1 is connected to the inlet of the deweighting tower T1. The biphenyl detection component detects whether the liquid phase at the top of the tower contains biphenyl; if it does, the deweighting process is repeated. Figure 3 All logistics in the process are related to Figure 2 The agreement is consistent and will not be elaborated upon here. Figure 3In the process, the biphenyl monitoring component detects biphenyl in stream 6. If stream 6 contains biphenyl, it is mixed with stream 1 and then re-entered into the deweighting tower T1 for deweighting treatment.

[0051] In summary, this application provides a biphenyl separation device for cyclohexane dehydrogenation products. The biphenyl separation device includes a de-heavy phase tower and a collection unit, with the top gaseous outlet of the de-heavy phase tower connected to the collection unit. In the technical solution provided by this application, the boiling point difference between biphenyl (the impurity to be removed) and other components in the cyclohexane dehydrogenation products is utilized. The de-heavy phase tower separates the biphenyl from the top gaseous outlet of the de-heavy phase tower into the collection unit. The de-heavy phase tower can achieve batch and large-scale separation of biphenyl from cyclohexane dehydrogenation products, offering advantages such as low separation energy consumption and high separation accuracy. The biphenyl separation device for cyclohexane dehydrogenation products provided by this application solves the technical defects of high product separation energy consumption and low separation accuracy in the existing cyclohexane dehydrogenation to benzene process.

[0052] The technical features of the embodiments described above can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. Furthermore, other implementation methods can be derived from the above embodiments, allowing for structural and logical substitutions and changes without departing from the scope of this disclosure.

[0053] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A biphenyl separation device for cyclohexane dehydrogenation products, characterized in that, The biphenyl separation unit includes a de-weighting tower and a collection unit. The top gas outlet of the de-weighting tower is connected to the collection unit. The de-weighting tower has a theoretical plate number of not less than 20. The de-weighting tower includes a rectification section and a stripping section, wherein the stripping section has a theoretical plate number of not less than 15. The rectification section of the de-weighting tower includes structured packing, and the stripping section of the de-weighting tower includes valve trays.

2. The biphenyl separation device according to claim 1, characterized in that, The biphenyl separation device further includes: a distillation column, the feed inlet of which is connected to the liquid outlet of the bottom of the heavy phase removal column, the liquid phase at the top of the heavy phase removal column being connected to the collection unit, and the theoretical plate number of the distillation column being not less than 10.

3. The biphenyl separation device according to claim 1 or 2, characterized in that, The deweight removal tower includes: packed tower and / or plate tower.

4. The biphenyl separation device according to claim 1, characterized in that, The theoretical number of plates in the deweight removal column is not less than 30, and the theoretical number of plates in the stripping section of the deweight removal column is not less than 20.

5. The biphenyl separation device according to claim 2, characterized in that, The distillation column includes structured packing.

6. The biphenyl separation device according to claim 1, characterized in that, The deweight removal tower also includes a first reboiler, which is a thermosiphon reboiler and / or a forced circulation reboiler.

7. The biphenyl separation device according to claim 2, characterized in that, The deweight removal column further includes a first reboiler, and the distillation column further includes a second reboiler; The first reboiler is a thermosiphon reboiler and / or a forced circulation reboiler, and the second reboiler is a forced circulation reboiler.

8. The biphenyl separation device according to claim 1, characterized in that, The biphenyl separation device further includes a condenser, which is located between the top gas outlet of the de-weighting tower and the collection unit.

9. The biphenyl separation device according to claim 2, characterized in that, The packing material of the deweight removal column includes any one or more of MELLAPAK250Y, 350Y, 500Y, and 750Y, and the packing material of the distillation column includes any one or more of MELLAPAK250Y, 350Y, 500Y, and 750Y.

10. The biphenyl separation device according to claim 2, characterized in that, The biphenyl separation device further includes a biphenyl detection component, which is disposed at the outlet of the liquid phase at the top of the de-weighting tower, and the outlet of the liquid phase at the top of the de-weighting tower is connected to the inlet of the de-weighting tower.

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