High-efficiency and low-energy-consumption device for preparing benzene from cyclohexane

Abstract

The utility model provides a high-efficiency and low-energy-consumption device for preparing benzene from cyclohexane. The device comprises a pretreatment unit, wherein a refrigerant channel is sequentially connected with a preheater, an evaporator and a superheater; wherein a refrigerant inlet of the preheater is connected with a cyclohexane input pipe; a refrigerant outlet of the superheater is connected with a feeding hole of the reactor; a discharge port of the reactor is connected with a feed port of the degassing tower through heating medium channels of the superheater and the preheater; the top of the degassing tower is connected with a first condenser; a liquid-phase outlet of the first condenser is used for extracting benzene, and a gas-phase outlet of the first condenser is connected with an inlet of the first compressor; an outlet of the first compressor is connected with the evaporator through a first branch, and the first compressor is used for inputting part of compressed gas-phase materials into the evaporator; and the outlet is connected with a subsequent treatment process through a second branch. The device disclosed by the utility model can obviously improve the conversion rate of raw materials and the selectivity of benzene and reduce the energy consumption of an evaporation process, and has extremely high economic value and strong industrial practicability.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of chemical synthesis, specifically relates to a kind of high efficiency low energy consumption's device of preparing benzene of cyclohexane. BACKGROUND

[0002] Cyclohexanol (C6H 12 O) and cyclohexanone (C6H 10 O) as important chemical raw materials, is the main intermediate of manufacturing nylon product, caprolactam and adipic acid etc., is also important industrial solvent.Cyclohexanol production method mainly has phenol hydrogenation method, cyclohexane oxidation method and cyclohexene hydration method.Among them, cyclohexene hydration method is prepared cyclohexanone process first with benzene as raw material under catalyst incomplete hydrogenation reaction and is prepared cyclohexene, cyclohexene is hydrated under the action of high-silica zeolite catalyst and is produced cyclohexanol, and cyclohexanol is dehydrogenated and is prepared cyclohexanone;Overall reaction condition is mild, and process flow is simple, and it is the mainstream cyclohexanone preparation method at present.

[0003] Cyclohexene hydration method produces cyclohexanone while by-product cyclohexane, specifically, in benzene hydrogenation reaction stage, benzene is about 15%~20% complete hydrogenation and is generated cyclohexane under the action of catalyst.At present, the main use of cyclohexane is prepared cyclohexanone through oxidation, but due to the problems such as serious pollution, poor safety, high cost in cyclohexane oxidation method synthesis cyclohexanone, has gradually been replaced, with the large-scale production of cyclohexene hydration method process device, leading to cyclohexane production capacity increasing to excess.

[0004] Therefore, in the process route of cyclohexene hydration preparation cyclohexanone, the conversion efficiency of benzene partial hydrogenation and the effective use of by-product cyclohexane directly affect the raw material consumption cost of cyclohexanone production process, and it is the key factor restricting process economy.

[0005] Patent CN218741894U discloses a kind of low-temperature low-pressure cyclohexane dehydrogenation preparation benzene production system, for the by-product cyclohexane of cyclohexanone production device is converted into benzene and hydrogen by dehydrogenation reaction, then benzene and hydrogen are recycled to cyclohexanone device as raw material.The conversion rate of cyclohexane in this patent is only 90%, and there is 10% of cyclohexane in the reaction material, and a large amount of recycling back to cyclohexanone device will increase operating energy consumption, and the system also has the problem of high energy consumption of deheavy rectification column. UTILITY MODEL CONTENT

[0006] In view of the deficiencies in the prior art, the utility model discloses a kind of high efficiency low energy consumption's device of preparing benzene of cyclohexane, to solve the technical problems of low conversion rate and selectivity, high energy consumption in the existing cyclohexane dehydrogenation preparation benzene technology.

[0007] In order to realize the above technical purposes, the utility model provides a kind of high efficient low energy consumption's cyclohexane preparation benzene device, and the device includes preprocessing unit, reactor, degassing tower, first compressor, wherein,

[0008] Preprocessing unit: for gradually heating reactant material, and the material after reaction is cooled by heat exchange;Including the preheater, evaporator and superheater of refrigerant passage are connected in turn;Wherein, the refrigerant inlet of preheater is connected cyclohexane input pipe;The refrigerant outlet of superheater is connected the feed inlet of reactor;

[0009] Reactor: for cyclohexane dehydrogenation preparation benzene;The discharge port of reactor is connected the feed inlet of degassing tower through the heat medium passage of superheater and preheater;

[0010] Degassing tower: for separating the material after reaction;The top of degassing tower is connected first condenser;The liquid phase outlet of first condenser is extracted product benzene, and gas phase outlet is connected the inlet of first compressor;

[0011] First compressor: for compressing gas phase material containing hydrogen and benzene;The outlet of first compressor is connected evaporator through first branch, for inputting part of compressed gas phase material into evaporator;The compressor outlet is connected subsequent processing process through second branch.

[0012] Cyclohexane hydrogenation preparation benzene reaction formula is as follows:

[0013] ,

[0014] Understandably, in dehydrogenation reaction system, the existence of product hydrogen and benzene will inhibit the forward reaction to proceed.The utility model research and development team accidentally found through exploration experiment that after adding part of gas phase material containing hydrogen and benzene in the material after raw material cyclohexane vaporization, then passing into reactor and reacting, not only does not inhibit the occurrence of dehydrogenation reaction, but also effectively improves reaction conversion rate and selectivity at relatively low reaction temperature, based on which the above technical scheme of returning gas phase material containing hydrogen, benzene to evaporator and mixing with cyclohexane is proposed.Development team speculates that using hydrogen or benzene as auxiliary gas can control the contact time of raw material cyclohexane and catalyst, promote the effective contact of raw material and catalyst, make dehydrogenation reaction proceed efficiently, thereby prevent catalyst from carbon deposition, improve raw material conversion rate and benzene selectivity, and improve the service life of catalyst.In addition, the above technical scheme returns compressed and heated gas phase material to evaporator, which can provide part of heat energy for cyclohexane evaporation, thereby reducing steam consumption and reducing energy consumption.

[0015] In the further example of the utility model, the structure and connection mode of the evaporator are optimized.

[0016] According to the second law of thermodynamics, heat always spontaneously transfers from a high-temperature object to a low-temperature object and cannot spontaneously transfer in the reverse direction, and therefore it is understandable that the temperature of the to-be-reacted material after the post-reaction material is overheated will be lower than the reaction temperature, and when the overheated material is input into the reactor, it needs to be heated first to reach the reaction temperature, and then can effectively contact the catalyst for reaction, and such a heating operation will cause the catalyst loaded in the inlet section of the reactor to be unable to fully play a catalytic activity due to insufficient temperature.

[0017] In a further example of the present application, the pre-treatment unit further comprises a temperature regulator, which is used to adjust the temperature of the to-be-reacted material to not higher than the reaction temperature and the difference ΔT from the reaction temperature satisfies ΔT≤3℃; the feed inlet of the temperature regulator is connected to the coolant outlet of the overheater, and the discharge outlet of the temperature regulator is connected to the feed inlet of the reactor. By arranging the temperature regulator, the temperature of the to-be-reacted material can be adjusted to not higher than the reaction temperature and the difference from the reaction temperature is not greater than 3℃, so that the to-be-reacted material can be quickly and efficiently reacted after being input into the reactor, thereby improving the reaction efficiency and the effective utilization rate of the catalyst.

[0018] In a further example of the present application, the structure of the temperature regulator, the pre-heater and the overheater is optimized.

[0019] In a further example of the present application, the device used in the post-treatment process is optimized.

[0020] In a further example of the present application, the structure of the tower kettle of the degassing tower is optimized.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] The device for preparing benzene from cyclohexane with high efficiency and low energy consumption of the present application pressurizes the gaseous material comprising hydrogen and benzene obtained by rectifying and separating the post-reaction material, and returns a part of the gaseous material as circulating gas to the evaporator to mix with cyclohexane steam, and then inputs the gaseous material into the reaction process after being heated and temperature-regulated for dehydrogenation reaction, so that the raw material conversion rate and the selectivity of benzene can be significantly improved, and the energy consumption of the evaporation process can be reduced; the overall device runs stably and has good economic benefits, and can be used for the process of preparing benzene from cyclohexane with high efficiency and low energy consumption. BRIEF DESCRIPTION OF DRAWINGS

[0023] The drawings accompanying the specification of this application serve to provide further understanding of the present application, and the schematic embodiments of the present application and the description thereof serve to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0024] Figure 1 Fig. 1 shows a structure diagram of the device for preparing benzene from cyclohexane with high efficiency and low energy consumption of the present application.

[0025] Figure 2 Another structure diagram of the device for preparing benzene from cyclohexane with high efficiency and low energy consumption is shown.

[0026] Among them, the above drawings include the following reference signs:

[0027] 11-preheater, 12-evaporator, 13-superheater, 14-temperature regulator, 2-reactor, 3-degassing tower, 31-first condenser, 32-first compressor, 33-post-processing unit, 34-circulating pump, 35-reboiler, 41-cyclohexane input pipe, 42-first branch, 43-second branch. DETAILED DESCRIPTION

[0028] In order to facilitate the understanding of the present application, the present application will be described more comprehensively below, and the preferred embodiments of the present application are given. It should be understood that these embodiments are only used for more detailed description, and should not be understood as limiting the present application in any form, that is, it is not intended to limit the protection scope of the present application.

[0029] Unless otherwise defined, the technical terms used in the following examples have the same meaning as generally understood by those skilled in the art to which the present application belongs. The test reagents used in the following examples, unless otherwise specified, are conventional biochemical reagents; the experimental methods, unless otherwise specified, are conventional methods.

[0030] The terms "first", "second", "third" and the like are only used for description purposes and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second", "third" and the like can explicitly or implicitly include one or more of the features.

[0031] Exploration example

[0032] In the present exploration experiment, in order to improve the conversion rate and reaction efficiency of cyclohexane dehydrogenation reaction, the R&D team of the present application tried to add a small amount of gas phase material obtained by separating the post-reaction material to the reaction raw material cyclohexane steam, that is, to add hydrogen and part of benzene steam (hydrogen and benzene are the products of cyclohexane dehydrogenation reaction) to the reaction raw material. Surprisingly, the dehydrogenation reaction can be carried out at a lower temperature, and the conversion rate of the overall reaction process is significantly improved, and the process energy consumption is also reduced.

[0033] The specific exploration process is as follows:

[0034] Exploration example 1: The small test reactor is a fixed bed reactor, which is a gas-solid reaction. The raw material cyclohexane is transported by a plunger pump to a heater to heat to the reaction temperature, then enters from the upper end of the reactor, and the dehydrogenation reaction occurs in the catalyst bed. The product flows out from the lower part of the reactor. A Pt-based catalyst is used to catalyze the dehydrogenation reaction of cyclohexane. The mass space velocity of cyclohexane is 1h -1 , the catalyst loading is 1g, the reaction pressure is 30kPaG, and the reaction temperature is 400℃. The liquid phase composition of the cooled reaction product is analyzed by gas chromatography (GC), and the conversion rate of cyclohexane is 92%, and the selectivity of benzene is 99.4%.

[0035] Exploration example 2: The small test reactor is a fixed bed reactor, which is a gas-solid reaction. The raw material cyclohexane is transported by a plunger pump, and hydrogen is transported by a steel cylinder and mixed with cyclohexane. The hydrogen to oil ratio (molar ratio of hydrogen to cyclohexane) is 0.1, and then the mixture is sent to an electric heater to heat to the reaction temperature, then enters from the upper end of the reactor, and the dehydrogenation reaction occurs in the catalyst bed. The product flows out from the lower part of the reactor. A Pt-based catalyst is used to catalyze the dehydrogenation reaction of cyclohexane. The mass space velocity of cyclohexane is 1h -1 , the catalyst loading is 1g, the reaction pressure is 30kPaG, and the reaction temperature is 320℃. The liquid phase composition of the cooled reaction product is analyzed by gas chromatography (GC), and the conversion rate of cyclohexane is 96%, and the selectivity of benzene is 99.9%.

[0036] Combining exploration example 1 and exploration example 2 can prove that by adding a small amount of hydrogen (reaction product) to the reaction raw material, the reaction conversion rate and benzene selectivity of the cyclohexane dehydrogenation reaction can be effectively improved, and the reaction temperature can be effectively reduced, promoting the efficient and low-energy consumption of the cyclohexane dehydrogenation reaction. Based on the discovery of the exploration example, the utility model provides a high-efficiency and low-energy-consumption device for preparing benzene from cyclohexane by returning the compressed gas phase material to the evaporation process.

[0037] Example 1

[0038] This embodiment shows a high-efficiency and low-energy-consumption device for preparing benzene from cyclohexane, which comprises a pretreatment unit, a reactor 2, a degassing tower 3, and a first compressor 32, wherein Figure 1

[0039] The pretreatment unit is used to gradually heat the reaction material and cool the material after reaction by heat exchange; it comprises a preheater 11, an evaporator 12 and a superheater 13 connected in turn; the coolant inlet of the preheater 11 is connected to the cyclohexane input pipe 41; the coolant outlet of the superheater 13 is connected to the feed inlet of the reactor 2;

[0040] The reactor 2 is used for dehydrogenation of cyclohexane to prepare benzene; the outlet of the reactor 2 is connected to the feed inlet of the degassing tower 3 through the heat medium channels of the superheater 13 and the preheater 11;​

[0041] Deaeration column 3: used for separating the reacted material; the top of the deaeration column 3 is connected with a first condenser 31; the liquid phase outlet of the first condenser 31 is used for collecting the product benzene, and the gas phase outlet is connected with the inlet of a first compressor 32;

[0042] The first compressor 32 is used for compressing the gas phase material containing hydrogen and benzene; the outlet of the first compressor 32 is connected with the evaporator 12 through a first branch 42, and is used for inputting part of the compressed gas phase material into the evaporator 12; the outlet of the first compressor 32 is connected with a subsequent treatment process through a second branch 43.

[0043] When the above technical scheme is used for the cyclohexane dehydrogenation reaction, the raw material cyclohexane (as a heat exchange refrigerant) input from the cyclohexane input pipe 41 first enters the refrigerant channel of the preheater 11, is further heated and vaporized after being heated by heat exchange in the refrigerant channel of the evaporator 12, and is mixed with the gas phase material returned from the first branch 42 to be input into the refrigerant channel of the superheater 13 as the material to be reacted, and is exchanged with the reacted material (as a heat exchange heat medium) output from the outlet of the reactor 2, so as to further increase the temperature of the material to be reacted, and further improve the dehydrogenation reaction efficiency in the reactor 2. The operating pressure of the reactor 2 can be selected as 0~300kpag, and the reaction temperature can be selected as 220~320℃. The reacted material collected from the outlet of the reactor 2 still has a high heat. The above technical scheme recycles the heat of the reacted material by sequentially inputting the reacted material into the heat medium channel of the superheater 13 and the heat medium channel of the preheater 11. The temperature of the reacted material output from the preheater 11 can be selected to be about 45~95℃, and the reacted material is in a gas phase or a gas-liquid two-phase state and enters the deaeration column 3 for rectification and separation. Therefore, the reacted material does not need to be cooled to room temperature, and the waste heat can be fully utilized, so that the energy operation efficiency in the whole process is improved. Through the rectification and separation of the deaeration column 3, the light component material containing hydrogen and benzene is collected from the top, and the liquid phase product benzene is obtained by condensing the light component material through the first condenser 31. The gas phase material (the temperature can be selected as 10~20℃) containing hydrogen and benzene is compressed and heated by the first compressor 32 (the pressure can be selected as 100~350kpag, and the temperature is controlled at 90~135℃), and is returned to the evaporator 12 to supplement part of the heat for the evaporation of cyclohexane, so as to improve the energy utilization efficiency of the whole device. Another compressed gas phase material is input into a subsequent treatment process.

[0044] Optionally, the first branch 42 is connected to the gas phase space within the evaporation zone of the evaporator 12. It is understood that the evaporator 12 can be divided into an evaporation zone for evaporating cyclohexane and a heating zone for providing heat to the evaporation zone. During operation, the internal space of the evaporation zone of the evaporator 12 is divided into a gas phase space and a liquid phase space. Connecting the first branch 42 to the gas phase space of the evaporator 12 allows the compressed gas phase material to be mixed with the vaporized cyclohexane. This not only utilizes the heat in the compressed and heated gas phase material to heat the evaporator 12, but also effectively reduces the partial pressure of the cyclohexane vapor in the evaporator 12, thereby lowering the operating temperature of the evaporator 12 and further saving energy.

[0045] The operating pressure of the evaporator 12 of the present invention can be selected from 0 to 360 kPag, and the operating temperature can be selected from 60 to 130°C. As is well known, the vaporization temperature of cyclohexane at 70 kPag is 180°C. However, by adding recycled gas to the evaporation process of the present invention, the vaporization temperature of cyclohexane at the same pressure (70 kPag) is reduced to approximately 94°C, significantly reducing the heat consumption of the evaporator 12.

[0046] Optionally, the evaporator 12 is a BKU type heat exchanger or an insertion type heat exchanger.

[0047] Optionally, combined Figure 2 The pretreatment unit also includes a thermostat 14, which is used to adjust the temperature of the material to be reacted to a temperature not higher than the reaction temperature and the difference ΔT with the reaction temperature satisfies ΔT≤3°C; the feed port of the thermostat 14 is connected to the refrigerant outlet of the superheater 13, and the discharge port of the thermostat 14 is connected to the feed port of the reactor 2.

[0048] Optionally, the thermostat 14 is a shell and tube heat exchanger or an electric heater.

[0049] This embodiment does not limit the specific structure and number of preheaters 11. Preheaters 11 may be heat exchangers that heat the raw cyclohexane by exchanging heat with the reacted material output from evaporator 12. For example, preheater 11 may include several shell-and-tube heat exchangers connected in series. Preheater 11 may further include several shell-and-tube heat exchangers connected in series, such as two shell-and-tube heat exchangers connected in series. Optionally, the outlet temperature of preheater 11 is 55-110°C, and the cyclohexane input to the apparatus of the present invention is raised to a temperature of 55-110°C after heat exchange.

[0050] This embodiment does not limit the specific structure and number of superheaters 13. Several shell-and-tube heat exchangers, or even two shell-and-tube heat exchangers, may be connected in series. The outlet temperature of superheater 13 is preferably 200-300°C. The temperature of the reaction mixture discharged from evaporator 12 is raised to 200-300°C in superheater 13.

[0051] Optionally, the subsequent processing procedure is carried out in the post-treatment unit 33 (the specific structure of the post-treatment unit 33 is not shown in the figure for the purpose of simplicity, Figure 1 、 Figure 2 the post-treatment unit 33 includes a first-stage compression device and a second condenser connected in sequence, for taking out product hydrogen from the gas phase outlet of the second condenser, and taking out product benzene from the liquid phase outlet of the second condenser; or the post-treatment unit 33 includes a multi-stage compression device, an inter-stage condenser and a final-stage condenser, for taking out product hydrogen from the gas phase outlet of the final-stage condenser, and taking out product benzene from the liquid phase outlets of the inter-stage condenser and the final-stage condenser.

[0052] Optionally, the operating pressure of the degassing tower 3 is 0-300 kPaG, the tower top temperature is 45-90℃, the tower bottom temperature is 100-180℃, the reflux ratio is 0.1-5, and the theoretical plate number is 3-15.

[0053] Optionally, fuel oil (including benzene and diphenyl) is taken out from the tower bottom discharge port of the degassing tower 3. The product benzene and product hydrogen obtained by the device for preparing benzene from cyclohexane according to the present application can be sent to a cyclohexanone device to produce cyclohexene, and the byproduct fuel oil can be sold as fuel, so that the process of the overall device not only realizes the in-device closed-loop circulation of raw materials and products, but also realizes zero-three-waste emission, which has important significance for reducing the raw material cost of the cyclohexanone process and driving the development of the high-value-added hydrocarbon dehydrogenation industry, and has strong industrial practicability.

[0054] Optionally, a circulating pump 34 is arranged on the pipeline connected with the tower bottom discharge port of the degassing tower 3, so as to control the taking-out process of the fuel oil.

[0055] Optionally, the tower bottom of the degassing tower 3 is provided with a reboiler 35.

[0056] Embodiment 2

[0057] A high-efficiency and low-energy-consumption method for preparing benzene from cyclohexane, which is combined with the device shown in Embodiment 1, and takes a 60,000 tons / year cyclohexane dehydrogenation device as an example:

[0058] The normal-temperature cyclohexane (normal temperature refers to the temperature range under normal environmental conditions without special heating or cooling treatment) from the boundary zone is preheated to 70℃ by the preheater 11 and then enters the evaporator 12. The cyclohexane is evaporated in the evaporator 12 and mixed with the circulating gas to obtain a first material; wherein the molar ratio of the circulating gas to the feed cyclohexane is 0.5, and the evaporation temperature of the evaporator 12 is controlled at 94℃.

[0059] The first material is heated to about 300°C by heat exchange with the reaction product (dehydrogenation product) output from the reactor 2, and then enters the cyclohexane temperature controller 14. The temperature of the first material is raised to 320°C by the action of the temperature controller 14, and then the first material is input into the reactor 2.

[0060] The reactor 2 is a fixed bed reactor with tubes, and the catalyst is a ruthenium-based catalyst. The cyclohexane input into the reactor 2 is dehydrogenated to produce benzene and hydrogen under the action of the catalyst at 320°C and 200 kPaG.

[0061] The second material output from the reactor 2 at 320°C is cooled to about 167°C by heat exchange with the first material in the heat medium channel of the superheater 13, and then continues to enter the heat medium channel of the preheater 11 to exchange heat with the input cyclohexane and is cooled to about 94°C. After cooling, the second material enters the degassing tower 3 in the form of a gas phase.

[0062] The overhead gas of the degassing tower 3 is condensed by the first condenser 31 to obtain a condensed liquid and a first gas phase in a gas phase. One of the condensed liquid is returned to the degassing tower 3 as reflux, and the other is output as product benzene to the cyclohexanone device. The first gas phase is compressed by a compressor, and the first gas phase is compressed to 360 kpag and about 96°C. A part of the first gas phase is transported to the gas phase space of the evaporator 12 as a circulating gas (hydrogen about 93 vol%, benzene about 7 vol%), and the remaining part is condensed to 15°C by the post-processing unit 33 to obtain product benzene condensate. The condensed liquid is combined with the condensed liquid of the first condenser 31 and is output as product benzene to the benzene hydrogenation process of the cyclohexanone device. The gas phase outlet of the second cooler outputs high-purity hydrogen gas as a product to the benzene hydrogenation process of the cyclohexanone device. The tower kettle of the degassing tower 3 is provided with a heat source by the reboiler 35, and the fuel oil is extracted from the tower kettle as a byproduct.

[0063] The operating parameters of the degassing tower 3 in this embodiment are shown in Table 1.

[0064] Table 1

[0065]

[0066] In this embodiment, the conversion rate of cyclohexane is ≥98%, the selectivity of benzene is ≥99.9%, and the purity of product benzene can reach ≥98%wt. The specific consumption (the amount of energy consumed per unit of product produced) is shown in Table 2. Among them, the low-pressure steam includes the low-pressure steam used for heating the cyclohexane evaporator 12 and the reboiler 35, the circulating water includes the circulating water used for the inter-stage cooling device between the multi-stage compression devices in the post-processing unit 33, and the chilled water includes the chilled water used for the final stage cooler at the outlet of the first condenser 31 and the multi-stage compression devices in the post-processing unit 33.

[0067] Table 2

[0068]

[0069] Comparative Example 1

[0070] A production method for preparing benzene by low-temperature and low-pressure cyclohexane dehydrogenation, which uses the system disclosed in patent CN218741894U to prepare. Taking a 60,000 tons / year cyclohexane dehydrogenation device as an example:

[0071] The cyclohexane from the boundary zone is preheated by the cyclohexane preheater and then sent to the cyclohexane evaporator to completely evaporate the cyclohexane into a gas phase at 150-180°C. After that, the reaction feed heat exchanger exchanges heat with the reaction products from the outlet of the cyclohexane dehydrogenation reactor, and the temperature is raised to the reaction temperature of 240-310°C. After that, the reaction feed is sent to the cyclohexane dehydrogenation reactor to carry out the dehydrogenation reaction under the action of the catalyst at 10-100 kPaG and 320°C. The reaction products from the cyclohexane dehydrogenation reactor are gradually cooled by the reaction feed heat exchanger and the cyclohexane preheater, and finally cooled to room temperature by the reaction material condenser.

[0072] The reaction material cooled to room temperature is then separated into gas and liquid phases in the gas-liquid separator. The hydrogen gas is cooled to 15°C by the hydrogen gas deep cooler to recover as much organic material entrained by the hydrogen gas as possible, and then pressurized to the appropriate pressure by the hydrogen gas compressor and sent to the hydrogen gas purification or the hydrogen gas pipeline network. The liquid phase obtained from the gas-liquid separator enters the heavy component removal rectification separation system, and is separated by the heavy component removal rectification column. The final product benzene is collected from the top of the column and sent to the raw material benzene storage tank. The heavy components such as benzene byproduct polymers are removed from the column and collected intermittently from the column bottom.

[0073] According to the comparative example, the cyclohexane conversion rate is ≥90%, the benzene selectivity is ≥99%, and the product benzene purity reaches 90%wt. or more. The specific consumption is shown in Table 3. Among them, the low-pressure steam includes the low-pressure steam used in the evaporator and the heavy component removal rectification separation system, the circulating water includes the circulating water used in the condenser, the heavy component removal rectification separation system, and the hydrogen gas compressor interstage cooler, and the chilled water includes the chilled water used in the heavy component removal rectification separation system and the hydrogen gas deep cooler.

[0074] Table 3

[0075]

[0076] It can be proved by combining example 2 with comparative example 1 that the part of gas phase material is returned to the cyclohexane evaporation process, which can promote the conversion rate of cyclohexane and the selectivity of benzene, compared with comparative example 1 without setting circulating gas, the conversion rate of cyclohexane is increased by about 8.9%, the selectivity of benzene is increased by about 0.9%, and the product purity is increased by about 8.9%. By combining table 2 and table 3, the example 2 of the utility model saves 68.8% of low-pressure steam, 58% of circulating water and 10.6% of refrigerated water compared with comparative example 1, the total unit consumption is saved by 42.7%, the utility model saves such a large amount of energy consumption, which will produce considerable economic benefits in large-scale industrial production. In addition, the conversion rate in comparative example 1 is only 90%, and a large amount of cyclohexane exists in the product benzene, and the circulating back to the cyclohexanone device increases the energy consumption of the separation of benzene, cyclohexene and cyclohexane in the cyclohexanone device, further increasing the overall process cost.

[0077] It should be noted that the above is a further detailed description of the utility model in combination with specific embodiments, and the specific implementation of the utility model cannot be limited to these descriptions. For ordinary skilled persons in the technical field to which the utility model belongs, without departing from the concept of the utility model, a number of simple improvements can be made, which should be regarded as belonging to the scope of protection of the utility model.

Claims

1. A device for the preparation of benzene from cyclohexane with high efficiency and low energy consumption, characterized in that, It comprises a pretreatment unit, a reactor (2), a degassing column (3), and a first compressor (32), wherein, The pretreatment unit is used for gradually heating the reactant and cooling the reacted material through heat exchange; it comprises a preheater (11), an evaporator (12), and a superheater (13) connected in sequence; the preheater (11) is connected with the cyclohexane input pipe (41) at the coolant inlet; the superheater (13) is connected with the reactor (2) at the coolant outlet; The reactor (2) is used for the dehydrogenation of cyclohexane to produce benzene; the outlet of the reactor (2) is connected with the inlet of the degassing column (3) through the heat medium channels of the superheater (13) and the preheater (11); The degassing column (3) is used for separating the reacted material; the top of the degassing column (3) is connected with the first condenser (31); the liquid phase outlet of the first condenser (31) is used for collecting the product benzene, and the gas phase outlet is connected with the inlet of the first compressor (32); The first compressor (32) is used for compressing the gas phase material containing hydrogen and benzene; the outlet of the first compressor (32) is connected with the evaporator (12) through the first branch (42) to input part of the compressed gas phase material into the evaporator (12); the outlet of the first compressor (32) is connected with the subsequent treatment process through the second branch (43).

2. The apparatus for efficient and low energy consumption production of benzene from cyclohexane as claimed in claim 1 wherein, The first branch (42) is connected with the gas phase space in the evaporation zone of the evaporator (12).

3. The apparatus for producing benzene from cyclohexane with high efficiency and low energy consumption according to claim 1 or 2, characterized in that, The evaporator (12) is a BKU type heat exchanger or an inserted heat exchanger.

4. The apparatus for efficient and low energy consumption production of benzene from cyclohexane as claimed in claim 1 wherein, The pretreatment unit further comprises a temperature regulator (14) used for adjusting the temperature of the reactant to be no higher than the reaction temperature and the difference ΔT between the temperature of the reactant to be and the reaction temperature satisfying ΔT≤3℃; The inlet of the temperature regulator (14) is connected with the coolant outlet of the superheater (13), and the outlet of the temperature regulator (14) is connected with the inlet of the reactor (2).

5. The apparatus for efficient and low energy consumption production of benzene from cyclohexane as claimed in claim 4 wherein, The temperature regulator (14) is a tube-shell heat exchanger or an electric heater.

6. The apparatus for efficient and low energy consumption production of benzene from cyclohexane as claimed in claim 1 wherein, The preheater (11) comprises several tube-shell heat exchangers connected in series.

7. The apparatus for efficient and low energy consumption production of benzene from cyclohexane as claimed in claim 1 wherein, The superheater (13) comprises several tube-shell heat exchangers connected in series.

8. The apparatus for efficient and low energy consumption production of benzene from cyclohexane as claimed in claim 1 wherein, The subsequent treatment process is carried out in a post-treatment unit (33) comprising a first-stage compression device and a second condenser connected in sequence, which is used for collecting the product hydrogen from the gas phase outlet of the second condenser and the product benzene from the liquid phase outlet of the second condenser; or comprising a multi-stage compression device, an inter-stage condenser, and a final-stage condenser, which is used for collecting the product hydrogen from the gas phase outlet of the final-stage condenser and the product benzene from the liquid phase outlets of the inter-stage condenser and the final-stage condenser.

9. The apparatus for efficient and low energy consumption production of benzene from cyclohexane as claimed in claim 1 wherein, Fuel oil is collected from the outlet of the column bottom of the degassing column (3).

10. The apparatus for efficient and low energy consumption production of benzene from cyclohexane as claimed in claim 1 wherein, A circulating pump (34) is arranged on the pipeline connected with the outlet of the column bottom of the degassing column (3).

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