Cyclic testing device for cyclohexane dehydrogenation benzene preparation process

Abstract

The invention relates to the technical field of cyclohexane dehydrogenation, in particular to a cyclic test device for a cyclohexane dehydrogenation benzene preparation process, and aims to solve the technical problems of low raw material utilization efficiency and increased test cost caused by incapability of realizing internal cyclic utilization of raw materials in related technologies. The cyclic testing device for the cyclohexane dehydrogenation benzene preparation process comprises a dehydrogenation reaction unit and a hydrogenation reaction unit. The dehydrogenation reaction unit is used for converting cyclohexane into benzene and hydrogen, and the hydrogenation reaction unit is used for converting benzene and hydrogen into cyclohexane. According to the cyclic test device for the cyclohexane dehydrogenation benzene preparation process, materials are recycled through material closed-loop circulation of the dehydrogenation reaction unit and the hydrogenation reaction unit, so that the utilization efficiency of the raw materials is improved, the consumption of the raw materials is reduced, the dependence on external raw materials is reduced, and the test cost is further reduced. The technical problems that the raw material utilization efficiency is low and the testing cost is increased due to the fact that an existing testing device for preparing benzene through cyclohexane dehydrogenation cannot achieve internal recycling of raw materials are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of cyclohexane dehydrogenation, and particularly to a cyclic test device for the process of dehydrogenating cyclohexane to benzene. Background Art

[0002] The cyclohexane market is in oversupply and faces great sales pressure. To solve this problem, the cyclohexane dehydrogenation process has been developed. By converting cyclohexane back into benzene and hydrogen, the procurement cost and storage cost of benzene can be reduced, and at the same time, the hydrogen can be reused in the hydrogenation unit of the cyclohexanone plant. To optimize this process and develop more efficient cyclohexane dehydrogenation technology, a test device for dehydrogenating cyclohexane to benzene has been designed for experimental research and process improvement. However, the existing test devices for dehydrogenating cyclohexane to benzene need to continuously consume external raw materials for multiple tests in actual applications and have not formed a closed-loop cycle. This testing method cannot achieve the internal recycling of raw materials, resulting in low raw material utilization efficiency and increased testing costs.

[0003] The existing test devices for dehydrogenating cyclohexane to benzene have technical problems of low raw material utilization efficiency and increased testing costs due to the inability to achieve the internal recycling of raw materials. Summary of the Invention

[0004] The purpose of the present invention is to provide a cyclic test device for the process of dehydrogenating cyclohexane to benzene, so as to solve the technical problems in the related art of low raw material utilization efficiency and increased testing costs due to the inability to achieve the internal recycling of raw materials.

[0005] To solve the above technical problems, the technical solution provided by the present invention is as follows:

[0006] The cyclic test device for the process of dehydrogenating cyclohexane to benzene provided by the present invention includes:

[0007] A dehydrogenation reaction unit and a hydrogenation reaction unit. The dehydrogenation reaction unit is used to convert cyclohexane into benzene and hydrogen, and the benzene is transported to the hydrogenation reaction unit through a compound pump. The hydrogenation reaction unit is used to convert the benzene and hydrogen into cyclohexane, and the cyclohexane is transported to the dehydrogenation reaction unit through a compound pump.

[0008] Specifically, it further includes a flare emission unit. The dehydrogenation reaction unit includes a cyclohexane raw material tank, a cyclohexane vaporizer, a cyclohexane superheater, a dehydrogenation reactor, a first cooler, a first gas-liquid separation tank, and a heavy component collection tank that are connected in sequence. The heavy component collection tank is connected to the cyclohexane vaporizer. Cyclohexane enters the cyclohexane vaporizer for heating and vaporization. The unvaporized cyclohexane enters the heavy component collection tank, and the vaporized cyclohexane enters the cyclohexane superheater for further superheating and then enters the dehydrogenation reactor, where a dehydrogenation reaction occurs under the action of a catalyst. The mixed gas generated in the dehydrogenation reactor is cooled by the first cooler and then separated into liquid benzene and gaseous hydrogen in the first gas-liquid separation tank. The hydrogen enters the flare emission unit for combustion, and the benzene is transported to the hydrogenation reaction unit through a compound pump.

[0009] Specifically, it further includes a hydrogen supply unit. The hydrogenation reaction unit includes a benzene preheater, a hydrogen-oil mixer, a hydrogenation reactor, a second cooler, a second gas-liquid separation tank, and a hydrogen preheater that are connected in sequence. The benzene separated from the first gas-liquid separation tank is heated by the benzene preheater and then introduced into the hydrogen-oil mixer. The hydrogen from the hydrogen supply unit is heated by the hydrogen preheater and then introduced into the hydrogen-oil mixer. The heated benzene and hydrogen are mixed in the hydrogen-oil mixer and then enter the hydrogenation reactor, where a hydrogenation reaction occurs under the action of a catalyst. The mixed gas generated in the hydrogenation reactor is cooled by the second cooler and then separated into liquid cyclohexane and gaseous hydrogen in the second gas-liquid separation tank. The hydrogen enters the flare emission unit for combustion, and the cyclohexane is transported to the cyclohexane raw material tank through a compound pump, thus realizing a closed-loop cycle of dehydrogenation and hydrogenation.

[0010] Specifically, the dehydrogenation catalyst in the dehydrogenation reactor is composed of an active component and a carrier. Among them, the active component is set as Pt, and the carrier is set as MgAl 2 O 4 spheres, and the Pt is distributed in a shell-like layer on the surface of the MgAl 2 O 4 spheres. The spinel structure of the MgAl 2 O 4 spheres can inhibit the aggregation of the Pt particles, enabling them to form highly dispersed ultra-small particles on the surface of the MgAl 2 O 4 spheres, so that the Pt has good sintering resistance, thereby significantly enhancing the stability of the catalyst.

[0011] Specifically, the Pt and the MgAl 2 O 4The strong electronic interaction between oxygen atoms on the surface of the sphere keeps the Pt in a slightly positive valence state. The Pt in the slightly positive valence state carries a positive charge, which changes its electronic structure and weakens the adsorption strength between the benzene molecule and the active site of the Pt, so that the benzene product can be desorbed more quickly, avoiding dehydrogenation reaction to form coke due to staying on the catalyst surface for a long time.

[0012] Specifically, the composite pump includes a motor, a pump housing, a screw group, a synchronous gear group and a fluid pipeline. The pump housing is provided with a cavity. The screw group includes a driving screw and a driven screw with opposite helix directions. The driving screw and the driven screw are respectively rotationally fixed in the pump housing, and the motor is power-connected to the driving screw. The synchronous gear group includes a first gear and a second gear sleeved on the driving screw and the driven screw respectively. The driving screw and the driven screw are meshed through the first gear and the second gear. The fluid pipeline includes a suction pipe and a discharge pipe, and the suction pipe and the discharge pipe are respectively communicated with the cavity. The motor drives the screw group to rotate to drive the fluid to flow through the suction pipe and the cavity in sequence and then to the discharge pipe.

[0013] Specifically, the composite pump further includes a slide plate group, and the slide plate group includes a first slide plate and a second slide plate. The fluid pipeline further includes a check valve, and the check valve is installed on the suction pipe and the discharge pipe to limit the flow of the fluid from the discharge pipe to the suction pipe direction. The first slide plate and the second slide plate are respectively installed at both ends of the driving screw. The driving screw, the driven screw, the first slide plate and the second slide plate form a piston. The driving screw and the first gear, and the driven screw and the second gear are both set to be key-connected. Taking the axial direction of the driving screw as the first direction, the piston slides in the cavity along the first direction and divides the cavity into non-communicating first volume cavity and second volume cavity. The reciprocating movement of the driving screw along the first direction is used to drive the piston to slide along the first direction, so that the volumes of the first volume cavity and the second volume cavity change alternately. When the volume of the first volume cavity or the second volume cavity increases, the fluid can be sucked in from the suction pipe. When the volume of the first volume cavity or the second volume cavity decreases, the fluid can be discharged from the discharge pipe.

[0014] Specifically, the motor includes a motor shaft and a plug rod. One end of the driving screw is inserted into the motor shaft. A cam groove is formed on the driving screw. The plug rod is installed on the motor shaft and inserted into the cam groove. The rotation of the motor shaft drives the plug rod to rotate around the axis of the motor shaft, so that the plug rod slides relative to the cam groove, and further drives the driving screw to reciprocate in the first direction. The reciprocating movement of the driving screw in the first direction can drive the first slide plate and the second slide plate to slide, so that the volumes of the first volume chamber and the second volume chamber change alternately.

[0015] Specifically, the compound pump further includes a locking assembly. The locking assembly includes a locking rod, a conical cover, a first cylinder, a clamping block and a second cylinder. The conical cover is sleeved on the motor shaft. The locking rod slides radially on the motor shaft. The locking rod is magnetically attracted to the conical cover. One end of the locking rod is provided with a ball and abuts against the conical inner wall of the conical cover through the ball. The first cylinder is used to drive the conical cover to slide axially along the motor shaft, so as to drive the locking rod to slide radially inward along the motor shaft and press the driving screw, and further lock the driving screw and the motor shaft together. The second cylinder is used to drive the clamping block to be clamped with the teeth of the synchronous gear set, so as to lock the clamping block and the synchronous gear set together, and further limit the rotation of the driving screw.

[0016] Specifically, the compound pump further includes an electric piston cylinder. The first cylinder and the second cylinder are respectively communicated with the electric piston cylinder through air pipes. The fluid pipeline further includes a flow meter. The flow meter is installed on the discharge pipe and is connected to the electric piston cylinder for control. The expansion and contraction of the electric piston cylinder is used to generate gas exchange between the first cylinder and the electric piston cylinder, and between the second cylinder and the electric piston cylinder, so as to trigger the expansion and contraction of the first cylinder and the second cylinder at the same time. When the driving screw is locked with the motor shaft and the clamping block is unlocked from the synchronous gear set, the rotation of the motor shaft is used to drive the driving screw to rotate. When the clamping block is locked with the synchronous gear set and the driving screw is unlocked from the motor shaft, the rotation of the motor shaft is used to drive the driving screw to reciprocate in the first direction.

[0017] Based on the above technical solutions, the beneficial effects of the present invention are analyzed as follows:

[0018] The present invention provides a cyclic test device for the process of dehydrogenating cyclohexane to benzene, including:

[0019] A dehydrogenation reaction unit and a hydrogenation reaction unit. The dehydrogenation reaction unit is used to convert cyclohexane into benzene and hydrogen, and the benzene is transported to the hydrogenation reaction unit through a compound pump. The hydrogenation reaction unit is used to convert the benzene and hydrogen into cyclohexane, and the cyclohexane is transported to the dehydrogenation reaction unit through a compound pump.

[0020] In specific applications, the cyclohexane undergoes a dehydrogenation reaction in the dehydrogenation reaction unit to test the process of dehydrogenating cyclohexane to produce benzene. The generated benzene is transported to the hydrogenation reaction unit through a compound pump. The benzene undergoes a hydrogenation reaction with hydrogen in the hydrogenation reaction unit to regenerate cyclohexane, and is transported back to the dehydrogenation reaction unit through a compound pump. That is, the dehydrogenation and hydrogenation system forms a closed loop. By recycling the materials, the utilization efficiency of the raw materials is improved, the consumption of raw materials is reduced, thereby reducing the dependence on external raw materials, and further reducing the testing cost.

[0021] It can be seen that compared with the prior art, the cyclic testing device for the process of dehydrogenating cyclohexane to produce benzene recycles the materials through the closed-loop circulation of the materials in the dehydrogenation reaction unit and the hydrogenation reaction unit, improves the utilization efficiency of the raw materials, reduces the consumption of raw materials, thereby reducing the dependence on external raw materials, and further reducing the testing cost. It overcomes the technical problems existing in the existing testing devices for dehydrogenating cyclohexane to produce benzene, such as the low utilization efficiency of raw materials and the increase in testing cost due to the inability to achieve internal recycling of raw materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0023] Figure 1 It is a schematic diagram of the cyclic testing device for the process of dehydrogenating cyclohexane to produce benzene provided by the embodiment of the present invention;

[0024] Figure 2 It is a schematic diagram of the overall structure of the compound pump;

[0025] Figure 3 It is a schematic sectional structure of the compound pump Figure 1 ;

[0026] Figure 4 It is a schematic sectional structure of the compound pump Figure 2 ;

[0027] Figure 5 It is a schematic sectional structure of the compound pump Figure 3。

[0028] Icon:

[0029] 100, dehydrogenation reaction unit; 110, cyclohexane raw material tank; 120, cyclohexane vaporizer; 130, cyclohexane superheater; 140, dehydrogenation reactor; 150, first cooler; 160, first gas-liquid separation tank; 170, heavy component collection tank;

[0030] 200, hydrogenation reaction unit; 210, benzene preheater; 220, hydrogen-oil mixer; 230, hydrogenation reactor; 240, second cooler; 250, second gas-liquid separation tank; 260, hydrogen preheater;

[0031] 300, composite pump; 310, motor; 311, motor shaft; 312, insertion rod; 320, pump casing; 301, cavity; 330, screw group; 331, driving screw; 302, cam groove; 332, driven screw; 340, synchronous gear group; 341, first gear; 342, second gear; 350, fluid pipeline; 351, extraction pipe; 3511, main extraction pipe; 3512, branch extraction pipe; 352, discharge pipe; 3521, main discharge pipe; 3522, branch discharge pipe; 353, check valve; 360, slide plate group; 361, first slide plate; 362, second slide plate; 370, locking component; 371, locking rod; 372, conical cover; 373, first cylinder; 374, block; 375, second cylinder; 380, electric piston cylinder;

[0032] 400, flare emission unit;

[0033] 500, hydrogen supply unit. Detailed implementation manners

[0034] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. Generally, the components of the embodiments of the present invention described and illustrated herein can be arranged and designed in various different configurations.

[0035] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0036] The following will describe in detail some embodiments of the present invention with reference to the accompanying drawings. Without conflict, the following embodiments and the features in the embodiments may be combined with each other.

[0037] The existing test device for dehydrogenating cyclohexane to benzene has technical problems that the internal recycling of raw materials cannot be achieved, resulting in low raw material utilization efficiency and increased test costs.

[0038] In view of this, the present invention provides a cyclic test device for the process of dehydrogenating cyclohexane to benzene, including:

[0039] A dehydrogenation reaction unit 100 and a hydrogenation reaction unit 200. The dehydrogenation reaction unit 100 is used to convert cyclohexane into benzene and hydrogen, and convey benzene to the hydrogenation reaction unit 200 through a composite pump 300. The hydrogenation reaction unit 200 is used to convert benzene and hydrogen into cyclohexane, and convey cyclohexane to the dehydrogenation reaction unit 100 through the composite pump 300.

[0040] Based on the above technical solutions, the cyclic test device for the process of dehydrogenating cyclohexane to benzene provided by the present invention can achieve the following technical effects:

[0041] The cyclic test device for the process of dehydrogenating cyclohexane to benzene repeats the use of materials through the closed-loop circulation of materials in the dehydrogenation reaction unit 100 and the hydrogenation reaction unit 200, improves the utilization efficiency of raw materials, reduces the consumption of raw materials, thereby reducing the dependence on external raw materials, and further reducing the test costs. It overcomes the technical problems existing in the existing test device for dehydrogenating cyclohexane to benzene, that is, the internal recycling of raw materials cannot be achieved, resulting in low raw material utilization efficiency and increased test costs.

[0042] The following will describe in detail Figures 1 to 5 the structure and shape of the cyclic test device for the process of dehydrogenating cyclohexane to benzene provided in this embodiment:

[0043] Specifically, regarding the composition of the dehydrogenation reaction unit 100:

[0044] It further includes a flare discharge unit 400, and the flare discharge unit 400 includes a hydrogen pipeline network and a burner. The dehydrogenation reaction unit 100 includes a cyclohexane raw material tank 110, a cyclohexane vaporizer 120, a cyclohexane superheater 130, a dehydrogenation reactor 140, a first cooler 150, a first gas-liquid separation tank 160, and a heavy component collection tank 170 that are connected in sequence. The heavy component collection tank 170 is connected to the cyclohexane vaporizer 120. Cyclohexane enters the cyclohexane vaporizer 120 and is indirectly heated and vaporized by 1.3 MPaG saturated steam. The unvaporized cyclohexane enters the heavy component collection tank 170, and the vaporized cyclohexane enters the cyclohexane superheater 130 for further superheating and then enters the dehydrogenation reactor 140, where a dehydrogenation reaction occurs under the action of a catalyst. The mixed gas generated in the dehydrogenation reactor 140 enters the first cooler 150 and is cooled by circulating water. The cooled material enters the first gas-liquid separation tank 160, and liquid benzene and gaseous hydrogen are separated in the first gas-liquid separation tank 160. The hydrogen enters the burner through the hydrogen pipeline network for combustion, and the benzene is transported to the hydrogenation reaction unit 200 by the composite pump 300.

[0045] Regarding the composition of the hydrogenation reaction unit 200, specifically:

[0046] It further includes a hydrogen supply unit 500. The hydrogenation reaction unit 200 includes a benzene preheater 210, a hydrogen-oil mixer 220, a hydrogenation reactor 230, a second cooler 240, a second gas-liquid separation tank 250, and a hydrogen preheater 260 that are connected in sequence. The benzene separated from the first gas-liquid separation tank 160 is heated by the benzene preheater 210 and then introduced into the hydrogen-oil mixer 220. The hydrogen from the hydrogen supply unit 500 is heated by the hydrogen preheater 260 and then introduced into the hydrogen-oil mixer 220. The heated benzene and hydrogen are mixed in the hydrogen-oil mixer 220 and then enter the hydrogenation reactor 230, where a hydrogenation reaction occurs under the action of a catalyst. The mixed gas generated in the hydrogenation reactor 230 enters the second cooler 240 and is cooled by circulating water. The cooled cyclohexane material enters the gas-liquid separation tank, and liquid cyclohexane and gaseous hydrogen are separated in the second gas-liquid separation tank 250. The hydrogen enters the burner through the hydrogen pipeline network for combustion, and the cyclohexane is transported to the cyclohexane raw material tank 110 by the composite pump 300, thus realizing a closed-loop cycle of dehydrogenation and hydrogenation. Among them, the hydrogen supply unit 500 is set as a high-pressure gas tank.

[0047] In the solution of this embodiment, the dehydrogenation catalyst in the dehydrogenation reactor 140 is composed of an active component and a carrier. Among them, the active component is set as Pt, and the carrier is set as MgAl 2 O 4 spheres, and Pt is distributed in a layer-like shell on the surface of the MgAl 2 O 4 spheres. MgAl 2 O 4The spherical shape helps with the mechanical strength and mass transfer efficiency of the catalyst, while enhancing the catalyst's anti-cracking property and operation stability. MgAl 2 O 4 The spinel structure of the sphere can inhibit the aggregation of Pt particles, enabling the Pt particles to maintain high dispersion under high-temperature conditions, so as to form highly dispersed ultra-small particles on the surface of the MgAl 2 O 4 sphere surface, significantly enhancing the sintering resistance of the Pt particles, and thus enhancing the stability of the catalyst. At the same time, the highly dispersed ultra-small Pt particles increase the number of active sites and relatively increase the surface area, thereby improving the specific activity of the catalyst.

[0048] In the solution of this embodiment, the strong electronic interaction between Pt and the oxygen atoms on the surface of the MgAl 2 O 4 sphere makes Pt in a slightly positive valence state. The slightly positive valence Pt carries a positive charge, which changes its electronic structure and weakens the adsorption strength between the benzene molecule and the active site of Pt, so that the benzene product can desorb more quickly, avoiding dehydrogenation reaction to form coke during long-term stay on the catalyst surface, thus ensuring the long-term stability of the catalyst and reducing the need for catalyst regeneration operations.

[0049] Regarding the composition of the composite pump 300, specifically:

[0050] The composite pump 300 includes a motor 310, a pump housing 320, a screw group 330, a synchronous gear group 340, and a fluid pipeline 350. The pump housing 320 is provided with a cavity 301. The screw group 330 includes a driving screw 331 and a driven screw 332 with opposite rotation directions. The driving screw 331 and the driven screw 332 are respectively rotationally fixed in the pump housing 320, and the motor 310 is power-connected to the driving screw 331. The synchronous gear group 340 includes a first gear 341 and a second gear 342 sleeved on the driving screw 331 and the driven screw 332 respectively. The driving screw 331 and the driven screw 332 are meshed through the first gear 341 and the second gear 342. The fluid pipeline 350 includes a suction pipe 351 and a discharge pipe 352. The suction pipe 351 and the discharge pipe 352 are respectively communicated with the cavity 301. The motor 310 drives the screw group 330 to rotate to drive the fluid to flow through the suction pipe 351 and the cavity 301 to the discharge pipe 352 in sequence.

[0051] In the solution of this embodiment, the composite pump 300 further includes a slide plate group 360, and the slide plate group 360 includes a first slide plate 361 and a second slide plate 362. The fluid pipeline 350 further includes a check valve 353, and the check valve 353 is installed on the extraction pipe 351 and the discharge pipe 352 to restrict the flow of fluid from the discharge pipe 352 to the extraction pipe 351. The first slide plate 361 and the second slide plate 362 are respectively installed at both ends of the driving screw 331, and the driving screw 331, the driven screw 332, the first slide plate 361 and the second slide plate 362 form a piston. The driving screw 331 and the first gear 341, and the driven screw 332 and the second gear 342 are both arranged in a key connection. Taking the axial direction of the driving screw 331 as the first direction, the piston slides in the cavity 301 along the first direction and divides the cavity 301 into a non-connected first volume chamber and a second volume chamber. The reciprocating movement of the driving screw 331 along the first direction is used to drive the piston to slide along the first direction, so that the volumes of the first volume chamber and the second volume chamber change alternately. When the volume of the first volume chamber or the second volume chamber increases, fluid can be sucked from the extraction pipe 351. When the volume of the first volume chamber or the second volume chamber decreases, fluid can be discharged from the discharge pipe 352.

[0052] Specifically, regarding how the motor 310 drives the piston to slide along the first direction:

[0053] The motor 310 includes a motor shaft 311 and a plug rod 312. One end of the driving screw 331 is inserted into the motor shaft 311. A cam groove 302 is formed on the driving screw 331, and the plug rod 312 is installed on the motor shaft 311 and inserted into the cam groove 302. The rotation of the motor shaft 311 drives the plug rod 312 to rotate around the axis of the motor shaft 311, so that the plug rod 312 and the cam groove 302 slide relative to each other, and further drives the driving screw 331 to reciprocate along the first direction. The reciprocating movement of the driving screw 331 along the first direction can drive the first slide plate 361 and the second slide plate 362 to slide, so that the volumes of the first volume chamber and the second volume chamber change alternately.

[0054] Specifically, regarding how the two working modes avoid conflicts:

[0055] The compound pump 300 further includes a locking assembly 370, which includes a locking rod 371, a conical cover 372, a first cylinder 373, a clamping block 374, and a second cylinder 375. The conical cover 372 is sleeved on the motor shaft 311. The locking rod 371 slides radially on the motor shaft 311 and is magnetically attracted to the conical cover 372. One end of the locking rod 371 is provided with a ball and abuts against the conical inner wall of the conical cover 372 through the ball. The first cylinder 373 is used to drive the conical cover 372 to slide axially along the motor shaft 311, thereby driving the locking rod 371 to slide radially inward along the motor shaft 311 and pressing the driving screw 331, and then locking the driving screw 331 and the motor shaft 311 together. The second cylinder 375 is used to drive the clamping block 374 to engage with the teeth of the synchronous gear set 340, thereby locking the clamping block 374 and the synchronous gear set 340 together, and then restricting the rotation of the driving screw 331.

[0056] Regarding how the first cylinder 373 and the second cylinder 375 are controlled, specifically:

[0057] The compound pump 300 further includes an electric piston cylinder 380. The first cylinder 373 and the second cylinder 375 are respectively communicated with the electric piston cylinder 380 through air pipes. The fluid pipeline 350 further includes a flowmeter, and the flowmeter is installed on the discharge pipe 352 and is connected to the electric piston cylinder 380 for control. The expansion and contraction of the electric piston cylinder 380 are used to generate gas exchange between the first cylinder 373 and the electric piston cylinder 380, and between the second cylinder 375 and the electric piston cylinder 380, so as to simultaneously trigger the expansion and contraction of the first cylinder 373 and the second cylinder 375. When the driving screw 331 and the motor shaft 311 are locked and the clamping block 374 and the synchronous gear set 340 are unlocked, the rotation of the motor shaft 311 is used to drive the driving screw 331 to rotate. At this time, the compound pump 300 is in the screw pump working mode. When the clamping block 374 and the synchronous gear set 340 are locked and the driving screw 331 and the motor shaft 311 are unlocked, the rotation of the motor shaft 311 is used to drive the driving screw 331 to reciprocate in the first direction. At this time, the compound pump 300 is in the piston pump working mode. Under normal conditions, it is in the screw pump working mode. When the flowmeter detects a decrease in the discharge flow rate, that is, when the screw is corroded, the flowmeter triggers the electric piston cylinder 380 to simultaneously drive the first cylinder 373 and the second cylinder 375 to switch the working mode of the compound pump 300 from the screw pump working mode to the piston pump working mode.

[0058] In the solution of this embodiment, the extraction pipe 351 includes a main extraction pipe 3511 and a plurality of parallel branch extraction pipes 3512, the discharge pipe 352 includes a main discharge pipe 3521 and a plurality of parallel branch discharge pipes 3522, one-way valves 353 are installed on each branch extraction pipe 3512 and each branch discharge pipe 3522, and the flowmeter is installed on the main discharge pipe 3521 for detecting the effective discharge flow rate.

[0059] In the solution of this embodiment, a third volume chamber is formed between the first slide plate 361 and the second slide plate 362, and the first volume chamber, the second volume chamber, and the third volume are respectively connected to at least one branch extraction pipe 3512 and one branch discharge pipe 3522.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A circulation test device for a cyclohexane dehydrogenation benzene production process, characterized in that: include: A dehydrogenation reaction unit (100) and a hydrogenation reaction unit (200); The dehydrogenation reaction unit (100) is used to convert cyclohexane into benzene and hydrogen, and transport the benzene to the hydrogenation reaction unit (200) through a composite pump (300); The hydrogenation reaction unit (200) is used to convert the benzene and hydrogen into cyclohexane, and transport the cyclohexane to the dehydrogenation reaction unit (100) through a composite pump (300).

2. The circulation test device for the cyclohexane dehydrogenation benzene production process according to claim 1, characterized in that: Also included is a flare discharge unit (400); The dehydrogenation reaction unit (100) comprises a cyclohexane raw material tank (110), a cyclohexane vaporizer (120), a cyclohexane superheater (130), a dehydrogenation reactor (140), a first cooler (150) and a first gas-liquid separation tank (160) which are connected in sequence; Cyclohexane enters the cyclohexane vaporizer (120) to be heated and vaporized, and the vaporized cyclohexane enters the cyclohexane superheater (130) to be further superheated before entering the dehydrogenation reactor (140) to undergo a dehydrogenation reaction under the action of a catalyst; The mixed gas generated by the reaction in the dehydrogenation reactor (140) is cooled by the first cooler (150) and then separated into liquid benzene and gaseous hydrogen in the first gas-liquid separation tank (160). The hydrogen enters the flare emission unit (400) for combustion, and the benzene is transported to the hydrogenation reaction unit (200) through the compound pump (300).

3. The circulation test device for the cyclohexane dehydrogenation benzene production process according to claim 2, characterized in that: Also included is a hydrogen supply unit (500); The hydrogenation reaction unit (200) comprises a benzene preheater (210), a hydrogen-oil mixer (220), a hydrogenation reactor (230), a second cooler (240), a second gas-liquid separation tank (250) and a hydrogen preheater (260) which are connected in sequence; The benzene separated by the first gas-liquid separation tank (160) is heated by the benzene preheater (210) and then introduced into the hydrogen-oil mixer (220); the hydrogen from the hydrogen supply unit (500) is heated by the hydrogen preheater (260) and then introduced into the hydrogen-oil mixer (220); The heated benzene and hydrogen are mixed in the hydrogen-oil mixer (220) and then enter the hydrogenation reactor (230) to undergo a hydrogenation reaction under the action of a catalyst; The mixed gas generated by the reaction in the hydrogenation reactor (230) is cooled by the second cooler (240) and then separated into liquid cyclohexane and gaseous hydrogen in the second gas-liquid separation tank (250). The hydrogen enters the flare emission unit (400) for combustion, and the cyclohexane is transported to the cyclohexane raw material tank (110) through the compound pump (300), thereby realizing a closed-loop cycle of dehydrogenation and hydrogenation.

4. The circulation test device for the cyclohexane dehydrogenation to benzene process according to claim 2, characterized in that: The dehydrogenation catalyst in the dehydrogenation reactor (140) is composed of an active component and a carrier, wherein the active component is Pt, the carrier is MgAl2O4 spheres, and the Pt is distributed in a layered shell shape on the surface of the MgAl2O4 spheres; The spinel structure of the MgAl2O4 sphere can inhibit the aggregation of the Pt particles, so that they form highly dispersed ultra-small particles on the surface of the MgAl2O4 sphere, so that the Pt has good sintering resistance, thereby significantly enhancing the stability of the catalyst.

5. The circulation test device for the process of preparing benzene by dehydrogenation of cyclohexane according to claim 4, characterized in that: The strong electronic interaction between the Pt and the oxygen atoms on the surface of the MgAl2O4 sphere puts the Pt in a slightly positive state; The slightly positively valenced Pt carries a positive charge, which changes its electronic structure and weakens the adsorption strength between the benzene molecules and the active sites of the Pt, thereby enabling the benzene product to be desorbed more quickly and avoiding a long stay on the catalyst surface to generate coke by dehydrogenation reaction.

6. The circulation test device for the cyclohexane dehydrogenation benzene production process according to claim 1, characterized in that: The compound pump (300) comprises a motor (310), a pump housing (320), a screw group (330), a synchronous gear group (340) and a fluid pipeline (350), and the pump housing (320) is provided with a cavity (301); The screw assembly (330) comprises a driving screw (331) and a driven screw (332) with opposite rotation directions, the driving screw (331) and the driven screw (332) are respectively fixedly rotated in the pump housing (320), and the motor (310) is dynamically connected to the driving screw (331); The synchronous gear set (340) comprises a first gear (341) and a second gear (342) which are respectively sleeved on the active screw (331) and the driven screw (332); the active screw (331) and the driven screw (332) are meshed through the first gear (341) and the second gear (342); The fluid pipeline (350) comprises an extraction pipe (351) and a discharge pipe (352), wherein the extraction pipe (351) and the discharge pipe (352) are respectively connected to the cavity (301), and the motor (310) drives the screw group (330) to rotate so as to drive the fluid to flow to the discharge pipe (352) through the extraction pipe (351) and the cavity (301) in sequence.

7. The circulation test device for the process of preparing benzene by dehydrogenation of cyclohexane according to claim 6, characterized in that: The compound pump (300) further comprises a slide plate group (360), wherein the slide plate group (360) comprises a first slide plate (361) and a second slide plate (362); The fluid pipeline (350) further comprises a one-way valve (353), wherein the one-way valve (353) is installed on the extraction pipe (351) and the discharge pipe (352) and is used to limit the flow of the fluid from the discharge pipe (352) to the extraction pipe (351); The first slide plate (361) and the second slide plate (362) are respectively installed at two ends of the active screw rod (331), and the active screw rod (331), the driven screw rod (332), the first slide plate (361) and the second slide plate (362) form a piston; The active screw rod (331) and the first gear (341), and the driven screw rod (332) and the second gear (342) are all configured to be key-connected; Taking the axial direction of the active screw (331) as a first direction, the piston slides in the cavity (301) along the first direction and divides the cavity (301) into a first volume cavity and a second volume cavity that are not connected; The reciprocating motion of the active screw (331) along the first direction is used to drive the piston to slide along the first direction, thereby causing the volumes of the first volume chamber and the second volume chamber to change alternately; When the volume of the first volume chamber or the second volume chamber increases, fluid can be sucked in from the extraction tube (351); When the volume of the first volume chamber or the second volume chamber is reduced, fluid can be discharged from the discharge pipe (352).

8. The circulation test device for the process of preparing benzene by dehydrogenation of cyclohexane according to claim 7, characterized in that: The motor (310) comprises a motor shaft (311) and an insertion rod (312); one end of the active screw rod (331) is inserted into the motor shaft (311); a cam groove (302) is provided on the active screw rod (331); and the insertion rod (312) is installed on the motor shaft (311) and inserted into the cam groove (302); The rotation of the motor shaft (311) drives the insertion rod (312) to rotate around the axis of the motor shaft (311), thereby causing the insertion rod (312) and the cam groove (302) to slide relative to each other, thereby driving the active screw rod (331) to reciprocate along the first direction; The reciprocating motion of the active screw (331) along the first direction can drive the first slide plate (361) and the second slide plate (362) to slide, thereby causing the volumes of the first volume chamber and the second volume chamber to change alternately.

9. The circulation test device for the process of preparing benzene by dehydrogenation of cyclohexane according to claim 8, characterized in that: The compound pump (300) further comprises a locking assembly (370), wherein the locking assembly (370) comprises a locking rod (371), a conical cover (372), a first cylinder (373), a clamping block (374) and a second cylinder (375); The conical cover (372) is sleeved on the motor shaft (311), the locking rod (371) slides radially on the motor shaft (311), and the locking rod (371) is magnetically attracted to the conical cover (372); A ball is provided at one end of the locking rod (371) and abuts against the conical inner wall of the conical cover (372) through the ball. The first cylinder (373) is used to drive the conical cover (372) to slide along the axial direction of the motor shaft (311), thereby driving the locking rod (371) to slide radially inward along the motor shaft (311) and press the active screw (331), thereby locking the active screw (331) and the motor shaft (311) together; The second cylinder (375) is used to drive the clamping block (374) to clamp onto the teeth of the synchronous gear set (340), thereby locking the clamping block (374) and the synchronous gear set (340) together, thereby limiting the rotation of the active screw (331).

10. The circulation test device for the process of preparing benzene by dehydrogenation of cyclohexane according to claim 9, characterized in that: The compound pump (300) further comprises an electric piston cylinder (380); The first cylinder (373) and the second cylinder (375) are respectively connected to the electric piston cylinder (380) through air pipes; The fluid pipeline (350) further includes a flow meter, which is installed on the discharge pipe (352) and is controllably connected to the electric piston cylinder (380); The expansion and contraction of the electric piston cylinder (380) is used to generate gas exchange between the first cylinder (373) and the electric piston cylinder (380), and between the second cylinder (375) and the electric piston cylinder (380), thereby triggering the expansion and contraction of the first cylinder (373) and the second cylinder (375) at the same time; When the active screw (331) is locked with the motor shaft (311) and the clamping block (374) is unlocked with the synchronous gear set (340), the rotation of the motor shaft (311) is used to drive the active screw (331) to rotate; When the block (374) is locked with the synchronous gear set (340) and the active screw (331) is unlocked with the motor shaft (311), the rotation of the motor shaft (311) is used to drive the active screw (331) to reciprocate along the first direction.

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