Process system for preparing cyclohexanol by partial hydrogenation of benzene

Abstract

The utility model provides a process system for preparing cyclohexanol by partial hydrogenation of benzene, which comprises a system for preparing cyclohexene by partial hydrogenation of benzene, the system comprises a benzene tank, a dehydration system and a benzene desulfurization system, the dehydration system comprises a water absorption device, a water absorption saturation feedback device and a dehydrating agent regeneration device, an outlet of the benzene tank is connected with a feed port pipeline of the water absorption device, and an outlet of the benzene tank is connected with a feed port pipeline of the benzene desulfurization system. A discharge port of the water absorption device is connected with an inlet pipeline of the benzene desulfurization system, and a water absorption saturation feedback device is arranged on the pipeline for connecting the discharge port and the inlet pipeline; and a regeneration port of the water absorption device is communicated with the dehydrating agent regeneration device. Before benzene enters the benzene desulfurization system, the raw material benzene is dehydrated through the water absorption device, so that the problems that the service cycle of a benzene desulfurization catalyst is influenced and a noble metal catalyst of a benzene partial hydrogenation system is poisoned due to the fact that a filter is blocked when water carried by benzene enters the benzene desulfurization system are effectively solved; therefore, indirect economic loss caused by output reduction and direct economic loss caused by inactivation of the noble metal catalyst are indirectly avoided.

Description

Technical Field

[0001] This utility model relates to the technical field of chemical production, and in particular to a process system for the partial hydrogenation of benzene to produce cyclohexanol. Background Technology

[0002] Cyclohexanol is an important chemical raw material, widely used in the manufacture of nylon, caprolactam, and adipic acid, and is also an important industrial solvent. Currently, the mainstream process for producing cyclohexanol in China is the partial hydrogenation of benzene to cyclohexene and the hydration of cyclohexene to cyclohexanol. (Refer to...) Figure 3 and Figure 4 It can be seen that the existing technology for the benzene hydrogenation to cyclohexene section in this process mainly includes the following steps:

[0003] (1) Benzene purification, impurity removal and desulfurization: After the fresh raw benzene in benzene tank 1 passes through the benzene desulfurization system 3, impurities and sulfides are removed to obtain desulfurized and impurity-removed benzene.

[0004] (2) Partial hydrogenation of benzene: After desulfurization, benzene enters the partial hydrogenation reaction system 6 through the benzene feed buffer tank 4, where a partial hydrogenation reaction occurs to produce a mixed oil of benzene, cyclohexene and cyclohexane.

[0005] (3) Crude oil post-treatment: The mixed oil enters the crude oil post-treatment system 8 for degassing and dehydration treatment to obtain crude oil suitable for entering the distillation system.

[0006] (4) Distillation and separation: The treated crude oil enters the refining and separation system 9, where high-purity benzene, cyclohexene and cyclohexane are separated. The cyclohexane is then sent to the first downstream unit 11 after passing through the second water washing device 10, and the cyclohexene is sent to the second downstream unit 13 after passing through the third water washing device 12.

[0007] (5) Benzene recycling: After the separated high-purity benzene passes through the first water washing device 7, it is mixed with the benzene after desulfurization and impurity removal in the benzene feed buffer tank 4 and enters the benzene partial hydrogenation reaction system 6 together to realize the recycling of benzene.

[0008] However, the existing process has the following drawbacks:

[0009] Issues with free water at the bottom of the benzene tank: During shutdown, free water will precipitate at the bottom of the benzene tank. When restarting, this free water will be rapidly and significantly pumped out, entering the benzene desulfurization system. This causes a significant increase in the differential pressure of the benzene desulfurization system's outlet filter, potentially leading to blockage and affecting the output. Furthermore, when a large amount of water enters the benzene desulfurization system, it not only affects the service life of the benzene desulfurization catalyst but also poisons the precious metal catalyst in the benzene partial hydrogenation reaction system, impacting production stability.

[0010] In summary, existing processes are prone to problems such as filter clogging, catalyst deactivation, and catalyst poisoning, affecting production stability and catalyst lifespan. Therefore, it is necessary to control the water in the benzene feed buffer tank. Utility Model Content

[0011] To address the aforementioned problems in the prior art, this invention provides a process system for the partial hydrogenation of benzene to produce cyclohexanol, avoiding problems caused by excessive water in the benzene desulfurization system.

[0012] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0013] In a first aspect, this utility model provides a process system for the partial hydrogenation of benzene to cyclohexanol, including a system for the partial hydrogenation of benzene to cyclohexene. The system for the partial hydrogenation of benzene to cyclohexene includes a benzene tank, a dehydration system, and a benzene desulfurization system. The dehydration system includes a water absorption device, a water absorption saturation feedback device, and a dehydrating agent regeneration device. The outlet of the benzene tank is connected to the inlet pipe of the water absorption device, and the outlet of the water absorption device is connected to the inlet pipe of the benzene desulfurization system. The water absorption saturation feedback device is installed on the pipe connecting the two.

[0014] The regeneration port of the water absorption device is connected to the dehydrating agent regeneration device.

[0015] The beneficial effects of this invention are as follows: before benzene enters the benzene desulfurization system, the raw benzene is dehydrated by a water absorption device, which effectively solves the problems of filter blockage, impact on the service life of benzene desulfurization catalyst, and poisoning of precious metal catalyst in the benzene partial hydrogenation system caused by benzene carrying water into the benzene desulfurization system. This indirectly avoids the indirect economic losses caused by reduced production and the direct economic losses caused by the deactivation of precious metal catalyst.

[0016] Optionally, two sets of the water absorption device, the water absorption saturation feedback device, and the dehydrating agent regeneration device are provided. The two sets of water absorption devices are connected in parallel between the benzene tank and the benzene desulfurization system, and each set of water absorption devices is equipped with a control valve on the pipeline connected to the benzene tank and the benzene desulfurization system.

[0017] As described above, the stable production of the benzene hydrogenation to cyclohexene section is ensured by using two reusable dehydration systems in a master-slave backup configuration.

[0018] Optionally, it also includes a benzene feed buffer tank, a circulating pump, a benzene partial hydrogenation reaction system, and a first water washing device. The outlet of the benzene desulfurization system is connected to the inlet pipe of the benzene feed buffer tank, the outlet of the benzene feed buffer tank is connected to the pipe of the benzene partial hydrogenation reaction system, the circulating outlet of the benzene feed buffer tank is connected to the inlet of the circulating pump, the outlet of the circulating pump is connected to the inlet of the water suction device, and the reflux port of the benzene feed buffer tank is connected to the pipe of the first water washing device.

[0019] The bottom of the benzene feed buffer tank is provided with a baffle that divides the benzene feed buffer tank into a feed side and a discharge side. The feed inlet, circulation outlet and reflux outlet of the benzene feed buffer tank are all located on the feed side, and the discharge outlet of the benzene feed buffer tank is located on the discharge side.

[0020] Optionally, the benzene feed buffer tank is provided with a downwardly protruding water bag at the bottom between the circulation outlet and the feed inlet.

[0021] Optionally, the reflux port of the benzene feed buffer tank is located directly above the opening of the water jacket.

[0022] Optionally, a boundary display feedback structure is provided on the top of the water bag, and a drain pipe is connected to the bottom of the water bag. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall process of the benzene-to-cyclohexene system in a benzene-to-cyclohexanol process according to an embodiment of the present invention.

[0024] Figure 2 This is a partial process diagram of the benzene-to-cyclohexene system in a benzene-to-cyclohexanol process according to an embodiment of the present invention.

[0025] Figure 3 This is a schematic diagram of the overall process of the benzene-to-cyclohexene production system in the prior art;

[0026] Figure 4 This is a partial process diagram of a benzene-to-cyclohexene hydrogenation system in the prior art;

[0027] Explanation of reference numerals in the attached figures:

[0028] 1. Benzene container;

[0029] 2. Dehydration system; 21. Water absorption device; 22. Dehydrating agent regeneration device;

[0030] 3. Benzene desulfurization system;

[0031] 4. Benzene feed buffer tank; 41. Baffle; 42. Water tank; 43. Interface position display feedback structure; 44. Drain pipe;

[0032] 5. Circulating pump; 6. Benzene partial hydrogenation reaction system; 7. First water washing unit; 8. Post-treatment system; 9. Purification and separation system; 10. Second water washing unit; 11. First downstream unit; 12. Third water washing unit; 13. Second downstream unit. Detailed Implementation

[0033] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present invention can be understood more clearly and thoroughly, and that the scope of the present invention can be fully conveyed to those skilled in the art.

[0034] Example 1

[0035] Please refer to Figure 1 and Figure 2 This embodiment provides a process system for the partial hydrogenation of benzene to cyclohexanol, including a system for the partial hydrogenation of benzene to cyclohexene and a system for the hydration of cyclohexene to cyclohexanol. Since the improvement in this embodiment does not involve the hydration of cyclohexene to cyclohexanol system, the hydration of cyclohexene to cyclohexanol system can refer to the existing technology.

[0036] like Figure 1 As shown, the benzene partial hydrogenation to cyclohexene system in this embodiment includes a benzene tank 1, a dehydration system 2, a benzene desulfurization system 3, a benzene feed buffer tank 4, a circulating pump 5, a benzene partial hydrogenation reaction system 6, a first water washing device 7, a post-treatment system 8, a refining and separation system 9, a second water washing device 10, a first downstream device 11, a third water washing device 12, and a second downstream device 13.

[0037] like Figure 2 It is known that the dehydration system 2 includes a water absorption device 21, a water absorption saturation feedback device, and a dehydrating agent regeneration device 22. The outlet of the benzene tank 1 is connected to the inlet pipe of the water absorption device 21, and the outlet of the water absorption device 21 is connected to the inlet pipe of the benzene desulfurization system 3. The water absorption saturation feedback device is installed on the pipe connecting the two. The regeneration port of the water absorption device 21 is connected to the dehydrating agent regeneration device 22.

[0038] like Figure 2 It can be seen that two sets of the water absorption device 21, the water absorption saturation feedback device, and the dehydrating agent regeneration device 22 are provided. The two sets of water absorption devices 21 are connected in parallel between the benzene tank 1 and the benzene desulfurization system 3, and each set of water absorption devices 21 is equipped with a control valve on the pipeline connecting to the benzene tank 1 and the benzene desulfurization system 3. The control valve and the water absorption saturation feedback device are not shown in the figure.

[0039] like Figure 1 It can be seen that the outlet of the benzene desulfurization system 3 is connected to the inlet pipe of the benzene feed buffer tank 4, the outlet of the benzene feed buffer tank 4 is connected to the pipe of the benzene partial hydrogenation reaction system 6, the circulation outlet of the benzene feed buffer tank 4 is connected to the inlet of the circulation pump 5, the outlet of the circulation pump 5 is connected to the inlet of the water suction device 21, and the return port of the benzene feed buffer tank 4 is connected to the pipe of the first water washing device 7.

[0040] Reference Figure 2 It is known that the bottom of the benzene feed buffer tank 4 is provided with a baffle 41 that divides the benzene feed buffer tank 4 into a feed side and a discharge side. A downwardly protruding water tank 42 is provided on the bottom between the circulation outlet and the feed inlet on the feed side. A boundary display feedback structure 43 is provided on the top of the water tank 42, and a drain pipe 44 is connected to the bottom of the water tank 42. The feed inlet, circulation outlet, and reflux outlet of the benzene feed buffer tank 4 are all located on the feed side, and the discharge outlet of the benzene feed buffer tank 4 is located on the discharge side. In this embodiment, the water tank 42 is a U-shaped groove, and the reflux outlet of the benzene feed buffer tank 4 is located directly above the opening of the water tank 42.

[0041] In this embodiment, the water absorption device 21 can be a molecular sieve adsorption tower filled with molecular sieves to selectively adsorb trace amounts of moisture in benzene. The water absorption saturation feedback device can be a capacitive trace moisture sensor, which directly measures the moisture content in the benzene phase by utilizing the difference in dielectric constants between benzene and water. The dehydrating agent regeneration device 22 can be a hot nitrogen regeneration system, which regenerates the water absorption device 21 by purging the moisture from the dehydrating agent in the water absorption device 21. The interface display feedback structure 43 can be a differential pressure interface meter, with high and low pressure taps located at the top of the water tank 42 and the top of the baffle 41, respectively. The latter is used as pressure feedback for the benzene layer. Since there is a pressure difference between the aqueous phase and the benzene phase, once the water layer reaches the top of the water tank 42, the pressure difference is obtained, and automatic drainage is achieved. This embodiment is only for illustrative purposes; other embodiments that can achieve equivalent functions are considered equivalent embodiments of this embodiment.

[0042] Therefore, the working principle of this embodiment is explained as follows:

[0043] (1) Benzene purification, impurity removal and desulfurization: Fresh raw benzene in benzene tank 1 enters water absorption device 21 through pipeline. Water absorption device 21 adsorbs water from the raw benzene. After adsorbing water, the raw benzene passes through benzene desulfurization system 3 to remove impurities and sulfides, and obtains desulfurized and impurity-removed benzene.

[0044] The water absorption saturation feedback device monitors the moisture content of benzene at the discharge port in real time to determine whether the desiccant in the water absorption device 21 is saturated. If the desiccant is not saturated, the current water absorption device 21 continues to operate. If the desiccant is saturated, the current water absorption device 21 is switched to the standby water absorption device 21 for continued operation. At this time, the corresponding dehydrating agent regeneration device 22 on the saturated water absorption device 21 is started to regenerate the desiccant. After regeneration, the water absorption device 21 enters the standby state. Thus, by using two reusable dehydration systems 2 in a master-slave standby configuration, the stable production of the benzene hydrogenation to cyclohexene section is ensured.

[0045] (2) Partial hydrogenation of benzene: After desulfurization, benzene enters the partial hydrogenation reaction system 6 through the benzene feed buffer tank 4, where a partial hydrogenation reaction occurs to produce a mixed oil of benzene, cyclohexene and cyclohexane.

[0046] Among them, such as Figure 4 It is known that the raw benzene entering the benzene feed buffer tank 4, or the washed benzene returning to the benzene feed buffer tank 4, will remain on the feed side of the baffle 41 where the water tank 42 is located for a period of time as a buffer. Due to the different densities of benzene and water, they will settle and separate. The water at the bottom accumulates in the water tank 42, while the benzene at the top enters the benzene partial hydrogenation reaction system 6. When the interface level display feedback structure 43 detects a rise in the interface level of the water tank 42, the water in the water tank 42 is discharged through the drain pipe 44. Compared to Figure 2 The improvements in this embodiment, as shown in the prior art, can prevent a large amount of water from entering the benzene partial hydrogenation reaction system 6 when the water washing tower interface in the first water washing device 7 is out of control or the control is unstable. This avoids the problems of filter blockage, affecting the service life of the benzene desulfurization catalyst, and poisoning of the precious metal catalyst in the benzene partial hydrogenation system.

[0047] When abnormal moisture content, production fluctuations, or changes in benzene content occur in the benzene feed buffer tank 4, the feed is returned to the dehydration system 2 and the benzene desulfurization system 3 via the circulation pump 5 for water absorption, impurity removal, and desulfurization.

[0048] (3) Crude oil post-treatment: The mixed oil enters the crude oil post-treatment system 8 for degassing and dehydration treatment to obtain crude oil suitable for entering the distillation system.

[0049] (4) Distillation and separation: The treated crude oil enters the refining and separation system 9, where high-purity benzene, cyclohexene and cyclohexane are separated. The cyclohexane is then sent to the first downstream unit 11 after passing through the second water washing device 10, and the cyclohexene is sent to the second downstream unit 13 after passing through the third water washing device 12.

[0050] (5) Benzene recycling: After the separated high-purity benzene passes through the first water washing device 7, it is mixed with the benzene after desulfurization and impurity removal in the benzene feed buffer tank 4 and enters the benzene partial hydrogenation reaction system 6 together to realize the recycling of benzene.

[0051] Therefore, this embodiment can effectively solve the problems of filter blockage, impact on the service life of benzene desulfurization catalyst, and poisoning of precious metal catalyst in benzene partial hydrogenation system caused by benzene carrying water into benzene desulfurization system 3, thereby indirectly avoiding indirect economic losses caused by reduced production and direct economic losses caused by deactivation of precious metal catalyst.

[0052] Therefore, it should be noted that the specific selection of each module in this embodiment is a specific example. In other equivalent embodiments, models that can meet the corresponding functions can be used for replacement.

[0053] In the description of this utility model, it should be understood that 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 indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0054] In this utility model, unless otherwise explicitly 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. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances.

[0055] In this utility model, unless otherwise explicitly 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 indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "beneath" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0056] In the description of this specification, the terms "one embodiment," "some embodiments," "embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0057] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make modifications, alterations, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A process system for the partial hydrogenation of benzene to cyclohexanol, characterized in that, The system includes a benzene partial hydrogenation to cyclohexene production system, which comprises a benzene tank, a dehydration system, and a benzene desulfurization system. The dehydration system includes a water absorption device, a water absorption saturation feedback device, and a dehydrating agent regeneration device. The outlet of the benzene tank is connected to the inlet pipe of the water absorption device, and the outlet of the water absorption device is connected to the inlet pipe of the benzene desulfurization system. The water absorption saturation feedback device is installed on the pipe connecting the two. The regeneration port of the water absorption device is connected to the dehydrating agent regeneration device.

2. The process system for partial hydrogenation of benzene to cyclohexanol according to claim 1, characterized in that, Two sets of the water absorption device, the water absorption saturation feedback device, and the dehydrating agent regeneration device are provided. The two sets of water absorption devices are connected in parallel between the benzene tank and the benzene desulfurization system, and each set of water absorption devices is equipped with a control valve on the pipeline connected to the benzene tank and the benzene desulfurization system.

3. The process system for partial hydrogenation of benzene to cyclohexanol according to claim 1, characterized in that, It also includes a benzene feed buffer tank, a circulating pump, a benzene partial hydrogenation reaction system, and a first water washing device. The outlet of the benzene desulfurization system is connected to the inlet pipe of the benzene feed buffer tank, the outlet of the benzene feed buffer tank is connected to the pipe of the benzene partial hydrogenation reaction system, the circulating outlet of the benzene feed buffer tank is connected to the inlet of the circulating pump, the outlet of the circulating pump is connected to the inlet of the water suction device, and the return port of the benzene feed buffer tank is connected to the pipe of the first water washing device. The bottom of the benzene feed buffer tank is provided with a baffle that divides the benzene feed buffer tank into a feed side and a discharge side. The feed inlet, circulation outlet and reflux outlet of the benzene feed buffer tank are all located on the feed side, and the discharge outlet of the benzene feed buffer tank is located on the discharge side.

4. The process system for partial hydrogenation of benzene to cyclohexanol according to claim 3, characterized in that, The benzene feed buffer tank has a downward-protruding water bag at the bottom between the circulation outlet and the feed inlet.

5. The process system for the partial hydrogenation of benzene to cyclohexanol according to claim 4, characterized in that, The reflux port of the benzene feed buffer tank is located directly above the opening of the water tank.

6. The process system for partial hydrogenation of benzene to cyclohexanol according to claim 4, wherein, The water tank is equipped with a boundary display feedback structure on its top, and a drain pipe is connected to the bottom of the water tank.

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