Organic hydride dehydrogenation reaction systems and methods

Abstract

The application discloses an organic hydrogen compound dehydrogenation reaction system and method, and belongs to the technical field of chemical engineering. The system comprises N-stage tubular reactors which are sequentially connected in series in the form of pipe layers and shells, and N is greater than or equal to 2. The heat carrier is divided into three streams, two of which enter the shell of the n-stage tubular reactor to provide heat for the dehydrogenation reaction in the pipe layer. The third stream is used to control the temperature of the outlet product of the pipe layer of the n-stage tubular reactor in series, so that the problem of excessively high and uneven bed layer temperature of the reactor, which leads to catalyst coking and deactivation and difficulty in steady-state operation, is solved.

Description

Technical Field

[0001] This invention belongs to the field of chemical processes, and particularly relates to dehydrogenation methods, specifically to dehydrogenation reaction systems and methods for organic hydrides. Background Technology

[0002] Hydrogen energy is a promising green and sustainable new energy source, but hydrogen storage and transportation are key challenges in its application. In recent years, liquid organic hydride hydrogen storage technology based on chemical reactions has attracted increasing attention due to its advantages such as large hydrogen storage capacity, high energy density, and safe and convenient liquid storage and transportation. This method allows hydrogen to undergo a hydrogenation reaction with unsaturated hydrocarbons at the production site, converting it into liquid organic hydrides for transportation. At hydrogen refueling stations or factories, the organic hydrides undergo a dehydrogenation reaction to yield hydrogen and unsaturated hydrocarbons, which are then transported back to the hydrogen production site.

[0003] Dehydrogenation is a strongly endothermic reaction, requiring a large amount of heat from the outside. This is especially true for organic hydrides with high hydrogen density, where the heat required for the reaction is even higher. For example, the heat of dehydrogenation of methylcyclohexane reaches 250 kJ / mol. Therefore, heat supply is crucial in dehydrogenation processes. In most known dehydrogenation processes and production units, the heat required for the dehydrogenation reaction is carried into the reactor by the reactants before the reactor and the heat carrier entering the reactor shell. This requires the heat carrier temperature to be higher than the temperature inside the tube to provide heat for the reaction. However, high temperatures can easily cause catalyst coking and deactivation. Furthermore, at the reactor inlet, the reaction rate is relatively fast, absorbing a large amount of heat. If external heat cannot be supplied in time, the system temperature drops rapidly. As the reaction proceeds, the reaction rate slows down, and the heat supply rate and reaction rate maintain a relatively balanced state. At this point, the system temperature gradually increases again. This initial decrease followed by an increase in system temperature can also have an adverse effect on the catalyst.

[0004] US20170015553A1 utilizes a portion of the hydrogen produced by a circulating organic liquid dehydrogenation reaction to prevent carbon deposition on the dehydrogenation catalyst, thereby inhibiting the reduction of catalyst activity. Specifically, the hydrogen production system includes a first dehydrogenation reaction unit for generating hydrogen through the dehydrogenation reaction of an organic liquid in the presence of a first catalyst, and a second dehydrogenation reaction unit for receiving the products from the first dehydrogenation reaction unit and generating hydrogen by dehydrogenating the organic liquid remaining in the products in the presence of a second catalyst.

[0005] CN112707368A avoids catalyst coking by cooling the reaction products from the first reactor and then separating them into hydrogen and unreacted products in a gas phase separator. The unreacted products are then heated and enter the second reactor to undergo a dehydrogenation reaction.

[0006] CN215464287U discloses a tubular fixed-bed reactor for dehydrogenation of low-carbon alkane, which provides heat for the dehydrogenation reaction inside the tubes through molten salt, so that the catalyst bed is in the optimal reaction range and the catalyst service time is extended.

[0007] In the above process, the heat carrier enters the tubular reactor at a certain temperature and flow rate at a specific location. This makes it difficult to adjust the inlet and outlet temperatures of the tube layer, resulting in limited operational flexibility. Under conditions such as uneven catalyst loading or partial catalyst deactivation, it is difficult to ensure that each section of the reactor is at a reasonable conversion rate and reaction rate. Summary of the Invention

[0008] To address the problems of excessively high and uneven reactor bed temperatures in current dehydrogenation processes, which lead to catalyst coking and deactivation, and difficulty in steady-state operation, this invention provides a tubular reactor system and its method and application for dehydrogenation of organic hydrides. This system offers advantages such as long catalyst lifespan, high operational flexibility, and stable operation.

[0009] On one hand, the present invention provides an organic hydride dehydrogenation reaction system, comprising an N-stage tubular reactor with tube layers connected in series and shell layers connected in series, where N≥2; the outlet of the tube layer of the nth stage tubular reactor is equipped with a temperature control element Tn; the nth stage tubular reactor has a shell-side feed manifold P. n Shell feed branch pipe B n The P n Connecting shell feed branch pipe B n The shell feed branch pipe B n It includes at least three parallel branches: branch n1, branch n2, and branch n3; branch n1 and branch n2 are respectively connected to the shell of the nth stage tubular reactor; branch n3 is equipped with a flow control element F. n Furthermore, branch n3 connects to the shell of the nth stage tubular reactor or to the shell of the (n+1)th stage tubular reactor; the temperature control element Tn and the flow control element F n Cascade control; n = 1 to N, any integer.

[0010] The cascade configuration described in this invention refers to the temperature sensor of the temperature control element Tn and the flow control element F. n The flow sensor is used for cascade control.

[0011] When branch n3 connects to the shell of the nth stage tube reactor, the interface position should preferably not be higher than 100mm above the lower tube sheet to avoid overheating of the material inside the tube and making it difficult to control the temperature.

[0012] The N (N≥2)-stage tubular reactors of this invention are connected in series, meaning that the tube layers of the first-stage tubular reactor, the second-stage tubular reactor, ..., the nth-stage tubular reactor, the (n+1)th-stage tubular reactor, the (n+2)th-stage tubular reactor, ..., the (N-1)th-stage tubular reactor, and the Nth-stage tubular reactor are sequentially connected by pipelines. Preferably, the outlet of the first-stage tubular reactor is connected to the inlet of the second-stage tubular reactor via a pipeline, ... the outlet of the nth-stage tubular reactor is connected to the inlet of the (n+1)th-stage tubular reactor via a pipeline, the outlet of the (n+1)th-stage tubular reactor is connected to the inlet of the (n+2)th-stage tubular reactor via a pipeline, ... and the outlet of the (N-1)th-stage tubular reactor is connected to the inlet of the Nth-stage tubular reactor via a pipeline.

[0013] The N (N≥3)-stage tubular reactors of this invention are shells connected in series, meaning that the shells of the first-stage tubular reactor, the second-stage tubular reactor, ..., the nth-stage tubular reactor, the (n+1)th-stage tubular reactor, the (n+2)th-stage tubular reactor, ..., the (N-1)th-stage tubular reactor, and the Nth-stage tubular reactor are sequentially connected by pipelines. Preferably, the outlet of the shell of the first-stage tubular reactor is connected to the inlet of the shell of the second-stage tubular reactor by pipelines; the outlet of the shell of the nth-stage tubular reactor and the inlet of the (n+1)th-stage tubular reactor are connected by pipelines; the outlet of the shell of the (n+1)th-stage tubular reactor and the inlet of the shell of the (n+2)th-stage tubular reactor are connected by pipelines; ..., the outlet of the shell of the (N-1)th-stage tubular reactor and the inlet of the shell of the Nth-stage tubular reactor are connected by pipelines.

[0014] Optionally, branches n1 and n2 connect to the shell of the nth stage tubular reactor and are arranged sequentially from the top to the bottom of the tubes.

[0015] Optionally, n1 is located near the top of the shell of the nth stage tubular reactor.

[0016] Optionally, the position of n2 connecting the shell of the nth stage tubular reactor is close to 1 / 4 to 1 / 6 of the distance from the top of the tube.

[0017] Optionally, in the tubes of the nth stage tubular reactor, catalyst and ceramic balls are sequentially filled from the bottom to the top of the tubes.

[0018] Optionally, the ratio of the filling height of the catalyst to the filling height of the ceramic balls is 1:1 to 5:1, preferably 3:1 to 4:1.

[0019] The catalyst used in the tubular organic hydride dehydrogenation reaction system and method of the present invention is a catalyst commonly used in the dehydrogenation reaction of organic liquid hydrogen storage materials, such as a Pt / Al2O3 composite catalyst, preferably with the addition of Fe and lanthanide elements, and preferably the catalyst prepared by Chinese invention patent application publication CN111054383A.

[0020] Optionally, the ratio of the catalyst loading amount of the (n+1)th stage tubular reactor to the catalyst loading amount of the nth stage tubular reactor is 0.5 to 1.5, preferably 0.9 to 1.1.

[0021] Optionally, the catalyst has a particle size of 1.8 to 2 mm and is packed into a cylinder with a height of 3 to 8 mm.

[0022] Optionally, the specifications of the ceramic balls are as follows: One of them.

[0023] Optionally, the catalyst and the ceramic balls are separated by a 12-mesh wire mesh.

[0024] Optionally, the nth stage tubular reactor is further equipped with a heater H. n The heater H n Located in the shell feed manifold P n and shell feed branch pipe B n between.

[0025] Optionally, the organic hydride dehydrogenation reaction system further includes a first heat exchanger E1; the first heat exchanger E1 consists of heat exchange pipe I and heat exchange pipe I' capable of heat exchange; the organic hydride source, heat exchange pipe I, and the tube inlet of the first-stage tubular reactor are sequentially connected via pipes; the shell of the nth-stage tubular reactor has a shell outlet pipe Q. n When n = 1 to N-1, branch n3 and Qn are combined to form the shell feed manifold P of the (n+1)th stage tubular reactor. n+1 When n = N, branch n3 and Q n After merging, connect the heat exchange pipeline I'.

[0026] Preferably, the organic hydride dehydrogenation reaction system is further provided with a second heat exchanger E2, which is composed of heat exchange pipeline II and heat exchange pipeline II' capable of heat exchange; the organic hydride source, heat exchange pipeline II, heat exchange pipeline I, and the tube inlet of the first-stage tube reactor are sequentially connected by pipelines; the outlet of the tube layer of the Nth-stage tube reactor is connected to the heat exchange pipeline II'.

[0027] Preferably, when n = N, branch n3 and shell outlet pipe Qn are merged and connected to two parallel branches, branch (N+1)1 and branch (N+1)2; branch (N+1)1 is connected to the heat exchange pipe I'; branch (N+1)2 is equipped with a flow control element F. N+1 The inlet of the first-stage tubular reactor is equipped with a temperature control element T. N+1 The F N+1 With the T N+1 Cascade control.

[0028] In one embodiment, when N=2, the organic hydride dehydrogenation reaction system includes a two-stage tubular reactor with sequentially connected tube layers and sequentially connected shell layers, a first heat exchanger E1, a second heat exchanger E2, a heater H1, and a heater H2. The first heat exchanger E1 consists of heat exchange pipes I and I' capable of heat exchange; the second heat exchanger E2 consists of heat exchange pipes II and II' capable of heat exchange. The organic hydride source, heat exchange pipes II, I, and the tube layer inlet of the first-stage tubular reactor are sequentially connected; the tube layer outlet of the second-stage tubular reactor is connected to the heat exchange pipe II'; the tube layer outlets of the first-stage tubular reactor and the second-stage tubular reactor are respectively equipped with temperature control elements T1 and T2; the shell layer of the first-stage tubular reactor is equipped with a shell layer. The first-stage tubular reactor has a main feed pipe P1, a branch feed pipe B1, and a discharge pipe Q1. The second-stage tubular reactor has a main feed pipe P2, a branch feed pipe B2, and a discharge pipe Q2. P1 is connected to the branch feed pipe B1 via heater H1. The branch feed pipe B1 is composed of parallel branches 11, 12, and 13. Branches 11 and 12 are connected to the shell of the first-stage tubular reactor. Branches 13 and Q1 are combined to form the main feed pipe P2 of the second-stage tubular reactor. P2 is connected to the branch feed pipe B2 via heater H2. The branch feed pipe B2 is composed of parallel branches 21, 22, and 23. Branches 21 and 22 are connected to the shell of the second-stage tubular reactor. Branches 23 and Q2 are combined to connect to the heat exchange pipe I' of the first heat exchanger E1. Branches 13 and 23 are respectively equipped with flow control elements F1 and F2. F1 is cascaded with T1; F2 is cascaded with T2. Preferably, branch 23 and Q2 are merged and then connected to parallel branches 31 and 32. Branch 32 is connected to heat exchange pipe I' of the first heat exchanger E1, and after heat exchange with heat exchange pipe I in E1, it is merged with the inlet pipe 31. The inlet pipe 31 is equipped with a flow control element F3. The tube inlet of the first-stage tube reactor is equipped with a temperature control element T3; F3 and T3 are cascaded.

[0029] In one embodiment, when N=3, the organic hydride dehydrogenation reaction system includes a three-stage tubular reactor with sequentially connected tube layers and sequentially connected shell layers, a first heat exchanger E1, a second heat exchanger E2, heaters H1, H2, and H3; the first heat exchanger E1 consists of heat exchange pipes I and I' capable of heat exchange; the second heat exchanger E2 consists of heat exchange pipes II and II' capable of heat exchange; the organic hydride source, heat exchange pipes II, I, and the tube layer inlet of the first-stage tubular reactor are sequentially connected; the tube layer outlet of the third-stage tubular reactor is connected to the heat exchange pipe II'; the tube layer outlet of the first-stage tubular reactor, the tube layer outlet of the second-stage tubular reactor, and the third-stage tubular reactor... Temperature control elements T1, T2, and T3 are respectively installed at the outlets of the tube layers of the reactor. The shell layer of the first-stage tube reactor is equipped with a shell feed main pipe P1, a shell feed branch pipe B1, and a shell discharge pipe Q1. The shell layer of the second-stage tube reactor is equipped with a shell feed main pipe P2, a shell feed branch pipe B2, and a shell discharge pipe Q2. The shell layer of the third-stage tube reactor is equipped with a shell feed main pipe P3, a shell feed branch pipe B3, and a shell discharge pipe Q3. P1 is connected to the shell feed branch pipe B1 via heater H1. The shell feed branch pipe is composed of parallel branches 11, 12, and 13. Branches 11 and 12 are respectively connected to the shell layer of the first-stage tube reactor. Branches 13 and Q1 are combined to form the shell feed main pipe P2 of the shell layer of the second-stage tube reactor. P2 is connected to the shell feed branch pipe B2 via heater H2. Shell feed branch pipe B2 consists of parallel branches 21, 22, and 23. Branches 21 and 22 are respectively connected to the shell of the second-stage tubular reactor. Branches 23 and Q2 merge to form the main shell feed pipe P3 for the third-stage tubular reactor. P3 is connected to the shell feed branch pipe B3 via heater H3. Shell feed branch pipe B2 consists of parallel branches 31, 32, and 33. Branches 31 and 32 are respectively connected to the shell of the third-stage tubular reactor. Branches 33 and Q3 merge to connect to the heat exchange pipe I' of the first heat exchanger E1. Branches 13, 23, and 33 are equipped with flow control elements F1, F2, and F3, respectively. F1 is cascaded with T1; F2 is cascaded with T2; and F3 is cascaded with T3. Preferably, branch 33 and Q3 are merged and connected to parallel branches 41 and 42. Branch 42 is connected to heat exchange pipe I' of the first heat exchanger E1, and after heat exchange with heat exchange pipe I in E1, it is merged with the inlet pipe 41. The inlet pipe 41 is equipped with a flow control element F4. The tube inlet of the first-stage tube reactor is equipped with a temperature control element T4; F4 and T4 are controlled in series.

[0030] On the other hand, the present invention provides a method for dehydrogenating organic hydrides using any of the above-described organic hydride dehydrogenation reaction systems, comprising: the organic hydride entering the tube layer of the nth-stage tubular reactor, contacting the catalyst in the tube layer, and undergoing a dehydrogenation reaction; the nth-stage reaction product flowing out through the tube layer outlet of the nth-stage tubular reactor and entering the tube layer of the (n+1)th-stage tubular reactor; a heat carrier entering the shell layer of the nth-stage tubular reactor via branches n1 and n2 to provide heat for the dehydrogenation reaction in the tube layer; and the flow control element F through branch n3... n Adjust the flow rate of branch n3 to regulate the temperature of the nth stage reaction product at the outlet of the tube layer of the nth stage tubular reactor.

[0031] Optionally, the temperature of the first-stage reaction product at the tube outlet of the first-stage reactor is 250°C to 420°C, preferably 320°C.

[0032] Optionally, the temperature of the second-stage reaction product at the tube outlet of the second-stage reactor is 250–420°C, preferably 340°C.

[0033] Optionally, the temperature of the third-stage reaction product at the tube outlet of the third-stage reactor is 250–420°C, preferably 360°C.

[0034] Optionally, the organic hydride is first vaporized and / or superheated before entering the tube layer of the first-stage tubular reactor; when n = N; the flow control element F through branch (N+1)2 N+1 Adjust the flow rate of branch (N+1)2 to regulate the temperature of the organic hydride at the tube inlet of the first-stage tubular reactor.

[0035] Optionally, the temperature of the organic hydride at the inlet of the tube layer of the first-stage tubular reactor is 280–360°C, preferably 280–300°C.

[0036] Optionally, the temperature of the organic hydride at the inlet of the tube layer of the nth stage tubular reactor is 250–420 °C.

[0037] Optionally, the organic hydride is selected from at least one of substituted or unsubstituted alkanes, substituted or unsubstituted cycloalkanes, substituted or unsubstituted alkenes, substituted or unsubstituted monocyclic aromatics, and substituted or unsubstituted polycyclic aromatics.

[0038] Optionally, the substituted or unsubstituted alkane is selected from at least one of C1-C6 alkanes; preferably propane or butane.

[0039] Optionally, the substituted or unsubstituted cycloalkanes are selected from at least one of C3-C6 cycloalkanes; preferably cyclohexane or methylcyclohexane.

[0040] Optionally, the substituted or unsubstituted olefin is selected from at least one of C2-C6 olefin hydrocarbons; preferably butene.

[0041] Optionally, the substituted or unsubstituted monocyclic aromatic hydrocarbon is selected from at least one of ethylbenzene, dibenzyltoluene, cyclohexylbenzene, and dicyclohexylbenzene.

[0042] Optionally, the substituted or unsubstituted fused-ring aromatic hydrocarbon is selected from at least one of tetrahydronaphthalene and decahydronaphthalene.

[0043] Optionally, the heat transfer medium is selected from steam or molten salt.

[0044] Optionally, the molten salt is selected from at least one of potassium nitrate, sodium nitrite, and sodium nitrate.

[0045] Optionally, the molten salt is preferably composed of potassium nitrate, sodium nitrite and sodium nitrate in a weight ratio of (40-60):(30-50):(5-10).

[0046] Optionally, the molten salt is preferably composed of 53% potassium nitrate, 40% sodium nitrite and 7% sodium nitrate.

[0047] Optionally, the flow direction of organic hydrides in the tube layer of the nth stage tubular reactor is parallel to the flow direction of the heat carrier in the shell layer.

[0048] Optionally, within the tube layer of the nth-stage tubular reactor, the dehydrogenation reaction conditions include: a reaction temperature of 250℃~420℃, preferably 280℃~400℃; a reaction pressure of 0.02MPaA~1.0MPaA, preferably 0.1MPaA~0.4MPaA; and a total mass hourly space velocity (MHV) of 0.5h⁻¹. -1 ~5h -1 2h preferred -1 ~4h -1 .

[0049] Optionally, the shell feed manifold P of the nth stage tubular reactor n In this process, the flow rate of the heat transfer fluid is 5000–10000 kg / h.

[0050] Optionally, the flow rate of branch n1 in the shell of the nth stage tubular reactor is 2000-3000 kg / h, preferably 1600-2400 kg / h.

[0051] Optionally, the flow rate of branch n2 in the shell of the nth stage tubular reactor is 1500-4000 kg / h, preferably 3000-3600 kg / h, and more preferably 2000 kg / h.

[0052] Optionally, the flow rate of the branch n3 in the shell of the first-stage tubular reactor is 1000–3000 kg / h, preferably 1200–1600 kg / h.

[0053] Optionally, the total mass hourly space velocity (MSV) of the organic hydrides at the inlet of the tube layer of the nth stage tubular reactor is 4–20 h⁻¹. -1 .

[0054] Optionally, the temperature of the heat carrier at the inlet of the shell of the nth stage tubular reactor is 40°C to 150°C higher than the temperature of the reactants at the inlet of the tube layer, preferably 50°C to 120°C.

[0055] Optionally, the temperature of the reactant at the inlet of the tube layer of the (n+1)th stage tubular reactor is 10°C to 60°C higher than the temperature of the reactant at the inlet of the tube layer of the nth stage tubular reactor, preferably 15°C to 35°C, and more preferably 20°C.

[0056] Optionally, the flow rate of branch n1 of the nth stage tubular reactor accounts for a portion of the flow rate of the shell feed main P. n The total flow rate is 10% to 50%, preferably 20% to 30%.

[0057] This invention divides the heat carrier into three streams after it is heated by the nth stage heater. Two streams enter the shell of the nth stage tubular reactor to provide heat for the dehydrogenation reaction in the tubes, and the third stream enters the (n+1)th stage heater. By adopting a technical solution of cascade control of the flow rate of the third stream and the outlet product temperature of the tubes of the nth stage tubular reactor, this invention effectively solves the problem of excessively high and uneven reactor bed temperature, which leads to catalyst coking and deactivation and difficulty in steady-state operation.

[0058] When the catalyst is unevenly packed or even deactivated by coking, the pressure drop and hydride flow rate distribution within the reactor tubes are uneven, resulting in different mass hourly space velocities, reaction pressures, and dehydrogenation degrees in different tubes. These uncertainties can lead to unstable operation of the device. However, in this invention, after the feed location of each heat carrier is determined, i.e., the heat exchange area is determined, the reaction rate and conversion rate of each stage reactor can still be reasonably adjusted by the inlet and outlet temperatures of each stage reactor tube layer. Furthermore, even when there is uneven packing or local deactivation of the catalyst, steady-state operation can still be maintained while ensuring the conversion rate. This is because the flow rate of the third heat carrier and the temperature of the shell-side reaction outlet are cascaded, thus enabling steady-state operation of the device under various uncertainties without increasing the temperature of the heat carrier entering the shell side, while ensuring the conversion rate. This invention can be used in the industrial production of organic hydride hydrogen storage. Attached Figure Description

[0059] Figure 1 This is a schematic diagram of the tubular organic hydride dehydrogenation reaction system of the present invention (taking a three-stage tubular reactor as an example);

[0060] Figure 2 for Figure 1 Enlarged schematic diagram of the first-stage tubular reactor R1;

[0061] In the figure, 1 is the first-stage tubular reactor R1, 2 is the second-stage tubular reactor R2, 3 is the third-stage tubular reactor R3, 4 is the first-stage heater H1, 5 is the second-stage heater H2, 6 is the third-stage heater H3, 7 is the first heat exchanger E1, and 8 is the second heat exchanger E2.

[0062] 101 Organic hydride source, 102 Organic hydride vaporized in the first stage heat exchanger, 103 Organic hydride superheated in the second stage heat exchanger, 104 First stage reaction product, 105 Second stage reaction product, 106 Third stage reaction product, 107 Third stage reaction product after cooling.

[0063] 108 Heat carrier source, 10 Shell feed manifold P1, 20 Shell feed manifold P2, 30 Shell feed manifold P3, 11 Heat inlet pipe 1-1, 12 Heat inlet pipe 1-2, 13 Heat inlet pipe 1-3, 21 Heat inlet pipe 2-1, 22 Heat inlet pipe 2-2, 23 Heat inlet pipe 2-3, 31 Heat inlet pipe 3-1, 32 Heat inlet pipe 3-2, 33 Heat inlet pipe 3-3, 41 Heat inlet pipe 4-1, 42 Heat inlet pipe 4-2, 109 Cooled heat carrier.

[0064] FC is a flow control element, and TC is a temperature control element. Detailed Implementation

[0065] As a preferred embodiment, the method for dehydrogenating organic hydrides using the tubular reactor organic hydride dehydrogenation system described in this invention includes the following steps:

[0066] In a tubular reactor, ceramic balls and catalyst are filled from top to bottom within the tubular layers.

[0067] b. The organic hydride is first vaporized in the second heat exchanger (vaporizer), then heated to the initial reaction temperature in the first heat exchanger (superheater), and then enters the tube layer of the first-stage tubular reactor containing the catalyst and ceramic balls to undergo a dehydrogenation reaction until it flows out from the tube layer of the Nth-stage tubular reactor to obtain the reaction product containing hydrogen, where N≥2.

[0068] After being heated by the first-stage heater, the heat carrier c is divided into three streams. The first stream enters the shell of the first-stage tubular reactor at the top of the ceramic ball to provide heat for the dehydrogenation reaction in the tube. The second stream enters the shell of the first-stage tubular reactor at the top of the catalyst to provide heat for the dehydrogenation reaction in the tube. The third stream mixes with the heat carrier at the outlet of the shell of the first-stage tubular reactor and then enters the second-stage heater for heating. It then enters the shell of the second-stage tubular reactor until it flows out from the shell of the Nth-stage tubular reactor.

[0069] The hydrogen-containing reaction products flowing out of the tube layer of the Nth stage tubular reactor serve as the heat source for the second heat exchanger (vaporizer) in step a. The heat carrier at the outlet of the shell layer of the Nth stage tubular reactor is divided into two streams. The first stream serves as the heat source for the first heat exchanger (superheater) in step a, and then it is mixed with the second stream and connected to the steam network.

[0070] e. In step b, the outlet of the second heat exchanger (superheater) for organic hydrides is equipped with temperature control, and in step d, the first heat carrier is equipped with flow control. The two are cascaded, and the outlet temperature of the organic hydrides is controlled at 280℃~360℃ by the flow rate of the first heat carrier.

[0071] In step c, the first heat carrier is equipped with a constant flow control, the second heat carrier is not equipped with a flow control, and the third heat carrier is equipped with a flow control. The product outlet of the first-stage tubular reactor in step a is equipped with a temperature control, which is cascaded with the flow control of the third heat carrier in step c. The outlet temperature of the first-stage reactor is controlled between 250℃ and 420℃ by controlling the flow of the third heat carrier.

[0072] g repeats step f, so that the inlet temperature of the reactor from the second stage to the Nth stage is effectively controlled between 250℃ and 420℃.

[0073] Example 1: Tubular Organic Hydride Dehydrogenation Reaction System

[0074] like Figure 1 , Figure 2 As shown, the tubular organic hydride dehydrogenation reaction system mainly consists of a first-stage tubular reactor R1, a second-stage tubular reactor R2, a third-stage tubular reactor R3, a first-stage heater H1, a second-stage heater H2, a third-stage heater H3, a first heat exchanger E1, and a second heat exchanger E2. Heat exchanger E1 consists of heat exchange pipes I and I' capable of heat exchange; the second heat exchanger E2 consists of heat exchange pipes II and II' capable of heat exchange.

[0075] The tubes R1, R2, and R3 have the same specifications. The tube is 4 meters long, there are 1600 tubes, and the diameter of the shell (reactor cylinder) is 1500 mm.

[0076] In R1, the tubes are filled with catalyst and ceramic balls from bottom to top; the ratio of catalyst to ceramic ball height is 3:1; the catalyst is 3 meters high and the ceramic ball height is 1 meter high. In R2, the tubes are filled with catalyst and ceramic balls from bottom to top; the ratio of catalyst to ceramic ball height is 4:1; the catalyst is 3.2 meters high and the ceramic ball height is 0.8 meters high. In R3, the tubes are filled with catalyst and ceramic balls from bottom to top; the ratio of catalyst to ceramic ball height is 5:1; the catalyst is 3.34 meters high and the ceramic ball height is 0.66 meters high.

[0077] The outlet of tube layer R1 (located at the bottom of R1) is connected to the inlet of tube layer R2 (located at the top of R2); the outlet of tube layer R2 (located at the bottom of R2) is connected to the inlet of tube layer R3 (located at the top of R3); the outlet of tube layer R3 (located at the bottom of R3) is connected to the heat exchange pipe II' of the second heat exchanger E2, and heat exchange is performed with the heat exchange pipe II of E2.

[0078] The heat carrier source 108 is connected to the shell feed main P1 of the first-stage tubular reactor. P1 is connected to the inlet of the first heater H1, and the outlet of H1 is connected to the shell feed branch pipe. The shell feed branch pipe consists of parallel inlet pipes 1-1, 1-2, and 1-3. Inlet pipe 1-1 is connected to the shell of R1 at the position corresponding to the top of the ceramic ball in R1. Inlet pipe 1-2 is connected to the shell of R1 at the position corresponding to the top of the catalyst in R1. Inlet pipe 1-1 is equipped with a flow control element FC01, and inlet pipe 1-3 is equipped with a flow control element FC02.

[0079] The shell outlet of R1 (located at the bottom of R1) is connected to the shell discharge pipe Q1. The inlet pipes 1-3 and Q1 are combined to form the shell feed manifold P2 of the second-stage tubular reactor. P2 is connected to the inlet of the second heater H2. The outlet of H2 is connected to the parallel inlet pipes 2-1, 2-2, and 2-3. Inlet pipe 2-1 connects to the shell of R2 at the position corresponding to the top of the ceramic balls in R2. Inlet pipe 2-2 connects to the shell of R2 at the position corresponding to the top of the catalyst in R2. Inlet pipe 2-1 is equipped with a flow control element FC03, and inlet pipe 2-3 is equipped with a flow control element FC04.

[0080] The shell outlet of R2 (located at the bottom of R2) is connected to the shell discharge pipe Q2. The inlet pipe 2-3, combined with Q2, forms the shell feed manifold P3 of the third-stage tubular reactor. P3 is connected to the inlet of H3, and the outlet of H3 is connected to the parallel inlet pipes 3-1, 3-2, and 3-3. Inlet pipe 3-1 connects to the shell of R3 at the position corresponding to the top of the ceramic balls in R3; inlet pipe 3-2 connects to the shell of R3 at the position corresponding to the top of the catalyst in R3. Inlet pipe 3-1 is equipped with a flow control element FC05; inlet pipe 3-3 is equipped with a flow control element FC06.

[0081] The shell outlet of R3 (located at the bottom of R3) is connected to the shell discharge pipe Q3. Heat inlet pipe 3-3 merges with Q3 and connects to parallel heat inlet pipes 4-1 and 4-2. Heat inlet pipe 4-2 connects to heat exchange pipe I' of the first heat exchanger E1, where it exchanges heat with heat exchange pipe I before merging with heat inlet pipe 4-1. Heat inlet pipe 4-1 is equipped with a flow control element FC07.

[0082] Organic hydride source 101 is sequentially connected to heat exchange pipe II of the second heat exchanger E2 and heat exchange pipe I of the first heat exchanger E1; heat exchange pipe I is connected to the tube inlet of R1 (located at the top of R1) via a pipe, and the connected pipe or the tube inlet of R1 is equipped with a temperature control element TC07.

[0083] The tube layer outlet of R1 is equipped with a temperature control element TC02; the tube layer outlet of R2 is equipped with a temperature control element TC04; and the tube layer outlet of R3 is equipped with a temperature control element TC06.

[0084] The flow control element FC02 and the temperature control element TC02 are cascaded together; the flow control element FC04 and the temperature control element TC04 are cascaded together; the flow control element FC06 and the temperature control element TC06 are cascaded together; and the flow control element FC07 and the temperature control element TC07 are cascaded together.

[0085] Example 2: Dehydrogenation reaction method for organic hydrides

[0086] A certain thousand-ton-scale hydrogen plant uses methylcyclohexane as a dehydrogenation feedstock and employs the tubular organic hydride dehydrogenation reaction system of Example 1. Figure 1 , Figure 2 The dehydrogenation reaction process technology (shown in Table 1) uses saturated steam at 1.0 MPaA as the heat transfer medium. The main operating conditions and running status are shown in Table 1.

[0087] The conversion rate of methylcyclohexane is calculated using formula (1).

[0088]

[0089] When calculating the conversion rate of methylcyclohexane in the nth stage reactor, it is calculated according to formula (1), where m1 is the mass of methylcyclohexane at the inlet of the nth stage reactor, m2 is the mass of methylcyclohexane at the outlet of the nth stage reactor, and n = 1 to N.

[0090] When calculating the total conversion rate of methylcyclohexane in a tubular organic hydride dehydrogenation reaction system, it is calculated according to formula (1). In formula (1), m1 is the mass of methylcyclohexane at the inlet of the first-stage reactor and m2 is the mass of methylcyclohexane at the outlet of the Nth-stage reactor. In Example 2, N is 3.

[0091] In this embodiment of the invention, the catalyst used is the catalyst prepared in Example 1 of Chinese Invention Patent Application Publication CN111054383A; the ceramic balls are composed of inert alumina, and the particle size is... Purchased from Xiangdong Petrochemical Packing Factory in Pingxiang City, Jiangxi Province.

[0092] The flow direction of the heat transfer fluid (water vapor) in the shell of a tubular reactor:

[0093] After being heated by the first-stage heater H1, heat carrier 108 (water vapor) is divided into three streams via inlet pipes 1-1, 1-2, and 1-3: heat carrier 1-1, heat carrier 1-2, and heat carrier 1-3, respectively. The flow rate of heat carrier 1-1 accounts for 30% of the total flow rate of heat carrier (heat carrier 108). Among them, heat carrier 1-1 and heat carrier 1-2 enter the shell of R1 to provide heat for the dehydrogenation reaction in the R1 tube layer. Heat carrier 1-1 enters the shell of R1 at the position corresponding to the top of the ceramic ball, and heat carrier 1-2 enters the shell of R1 at the position corresponding to the top of the catalyst. After both heat carrier 1-1 and heat carrier 1-2 flow out of the shell outlet of R1 (located at the bottom of R1), they mix with heat carrier 1-3 and enter the second-stage heater H2 for heating. After heating, the heat is divided into three streams through heat inlet pipe 2-1, heat inlet pipe 2-2, and heat inlet pipe 2-3, which are heat carrier 2-1, heat carrier 2-2, and heat carrier 2-3, respectively, with heat carrier 2-1 accounting for 25% of the total flow.

[0094] Heat carriers 2-1 and 2-2 enter the shell of R2 and flow out from the shell outlet of R2 (located at the bottom of R2). They then mix with heat carrier 2-3 and enter the third-stage heater H3 for heating. After heating, they are divided into three streams through heat inlet pipes 3-1, 3-2, and 3-3, which are heat carriers 3-1, 3-2, and 3-3, respectively. Heat carrier 3-1 accounts for 20% of the total flow.

[0095] Heat carriers 3-1 and 3-2 enter the shell of R3 and flow out from the shell outlet of R3 (located at the bottom of R3). They mix with heat carrier 3-3 and are divided into two streams by heat inlet pipes 4-1 and 4-2, namely heat carrier 4-1 and heat carrier 4-2. Heat carrier 4-2 flows through the heat exchange pipe I' of the first heat exchanger E1 and serves as the heat source for heat exchange pipe I of E1. After flowing out of E1, it mixes with heat carrier 4-1 and is then incorporated into the steam network.

[0096] The flow direction of the organic hydride (methylcyclohexane) in the R1, R2, and R3 pipe layers:

[0097] Methylcyclohexane 101 first flows through heat exchange pipe II of the second heat exchanger E2, where it is heated and vaporized by the product 106 at the outlet of the R3 tube layer in heat exchange pipe II' (vaporization temperature is 145°C). Then it flows through heat exchange pipe I of the first heat exchanger E1, where it is heated to the initial reaction temperature (i.e., the temperature of TC07, which is 300°C) by the heat carrier 4-2 in heat exchange pipe I'. Then it enters the R1 tube layer from the inlet (located at the top of R1) to undergo the first-stage dehydrogenation reaction. The product 104 at the outlet of R1 is discharged from the outlet of the R1 tube layer (located at the bottom of R1). Then, the hydrogen enters R2 and R3 sequentially (the flow direction inside R2 and R3 is the same as the flow direction inside R1) to undergo the second-stage dehydrogenation reaction and the third-stage dehydrogenation reaction, respectively. The initial reaction temperature entering R2 is 320℃, and the initial reaction temperature entering R3 is 340℃. The final product flows out from the tube outlet of R3 (located at the bottom of R3), resulting in R3 outlet product 106 containing hydrogen. R3 outlet product 106 flows through the heat exchange pipe II' of the second heat exchanger E2, serving as the heat source for heat exchange pipe II of the second heat exchanger E2.

[0098] Because FC02 and TC02 are cascaded, the heat inside the reactor will change during the reaction. In order to maintain TC02 at a constant value, the flow rate of FC02 will fluctuate with the reaction performance inside the reactor. Therefore, the second and third streams are fluctuating values.

[0099] Temperature control:

[0100] The R1 pipe inlet is equipped with a temperature control TC07. The temperature of the R1 pipe inlet TC07 is adjusted by controlling the flow rate of FC07. The temperature of TC07 is controlled at 300℃.

[0101] The outlet of R1 is equipped with a temperature control TC02. Heat carrier 1-1 is controlled by a constant flow rate, i.e., FC01, which accounts for 30% of the total heat carrier flow rate P1. There is no flow control on the heat carrier 1-2 pipeline, which is a free pipeline. Heat carrier 1-3 is equipped with a flow control FC02. FC02 and TC02 are cascaded. The flow rate of heat carrier 1-3 is controlled by FC02 to adjust the temperature TC02 at the outlet of R1. The temperature of TC02 is controlled at 320℃.

[0102] The inlet temperature control of R2 is the outlet temperature TC02 of R1.

[0103] The outlet of the R2 pipe layer is equipped with a temperature control TC04. The heat carrier 2-1 is controlled by a constant flow rate, i.e., FC03, which accounts for 25% of the total heat carrier flow rate P2 (P2 and P1 have the same flow rate). There is no flow control on the heat carrier 2-2 pipeline, which is a free pipeline. The heat carrier 2-3 is equipped with a flow control FC04. FC04 and TC04 are cascaded. The temperature TC04 at the outlet of the R2 pipe layer is adjusted by controlling the flow rate FC04 of the heat carrier 2-3. The temperature of TC04 is controlled at 340℃.

[0104] The inlet temperature control of R3 is the outlet temperature TC04 of R1.

[0105] The outlet of R3 is equipped with a temperature control TC06. Heat carrier 3-1 is controlled by a constant flow rate, i.e., FC05, which accounts for 20% of the total heat carrier flow rate. There is no flow control on the heat carrier 3-2 pipeline, which is a free pipeline. Heat carrier 3-3 is equipped with a flow control FC06. FC06 and TC06 are cascaded. The temperature TC06 at the outlet of R3 is adjusted by controlling the flow rate FC06 of heat carrier 3-3. The temperature of TC06 is controlled at 360℃.

[0106] The outlet temperature of the organic hydride in superheater E4, i.e., the inlet temperature of the tube layer of R1, is TC07.

[0107] Table 1

[0108]

Claims

1. An organic hydride dehydrogenation reaction system, characterized in that, Including N-stage tubular reactors with tube layers connected in series and shell layers connected in series, where N≥2; The outlet of the tube layer of the nth stage tubular reactor is equipped with a temperature control element Tn; The nth stage tubular reactor has a shell-and-feed header P. n Shell feed branch pipe B n ; The P n Connecting shell feed branch pipe B n The shell feed branch pipe B n It includes at least three branches connected in parallel: branch n1, branch n2, and branch n3; Branch n1 and branch n2 are respectively connected to the shell of the nth stage tubular reactor; Branch n3 connects to the shell of the nth stage tubular reactor or to the shell of the (n+1)th stage tubular reactor; Branch line n3 is equipped with a flow control element F n ; The temperature control element Tn and the flow control element F n Cascade control; n = any integer from 1 to N; The organic hydride dehydrogenation reaction system is further provided with a first heat exchanger E1; the first heat exchanger E1 is composed of heat exchange pipeline I and heat exchange pipeline I' capable of heat exchange; the organic hydride source, heat exchange pipeline I, and the tube inlet of the first-stage tube reactor are connected in sequence. The nth stage tubular reactor has a shell discharge pipe Q. n ; When n = any integer from 1 to N-1, branch n3 and shell discharge pipe Qn are combined to form the shell feed main P of the (n+1)th stage tubular reactor. n+1 ; When n=N, branch n3 and shell discharge pipe Q n After merging, connect the heat exchange pipeline I'.

2. The organic hydride dehydrogenation reaction system according to claim 1, characterized in that, Branches n1 and n2 connect to the shell of the nth stage tubular reactor and are arranged sequentially from the top to the bottom of the tubes.

3. The organic hydride dehydrogenation reaction system according to claim 2, characterized in that, The n1 is located near the top of the shell of the nth stage tubular reactor. And / or, the location of n2 connecting the shell of the nth stage tubular reactor is approximately 1 / 4 of the distance from the top of the tubes. 1 / 6 of the way.

4. The organohydride dehydrogenation reaction system according to any one of claims 1-3, characterized in that, In the tubes of the nth stage tubular reactor, catalyst and ceramic balls are sequentially filled from the bottom to the top of the tubes.

5. The organic hydride dehydrogenation reaction system according to claim 4, characterized in that, The ratio of the catalyst loading amount of the (n+1)th stage tubular reactor to the catalyst loading amount of the nth stage tubular reactor is 0.5~1.5; And / or, the ratio of the catalyst filling height to the ceramic ball filling height is 1:1 to 5:1; And / or, the particle size of the catalyst is 1.8~2 mm.

6. The organic hydride dehydrogenation reaction system according to claim 5, characterized in that, The ratio of the catalyst loading amount of the (n+1)th stage tubular reactor to the catalyst loading amount of the nth stage tubular reactor is 0.9~1.1; And / or, the ratio of the catalyst filling height to the ceramic ball filling height is 3:1 to 4:

1.

7. The organohydride dehydrogenation reaction system according to any one of claims 1-3, characterized in that, The nth stage tubular reactor is also equipped with a heater H. n The heater H n Located in the shell feed manifold P n and shell feed branch pipe B n between; And / or, the organic hydride dehydrogenation reaction system is further provided with a second heat exchanger E2; the second heat exchanger E2 is composed of heat exchange pipes II and II' capable of heat exchange; the organic hydride source, heat exchange pipes II, heat exchange pipes I, and the tube inlet of the first-stage tube reactor are sequentially connected; the outlet of the tube layer of the Nth-stage tube reactor is connected to the heat exchange pipes II'; And / or, when n=N; branch n3 and shell outlet pipe Qn are merged and connected to two parallel branches, branch (N+1)1 and branch (N+1)2; branch (N+1)1 is connected to the heat exchange pipe I'; branch (N+1)2 is equipped with a flow control element F N+1 The inlet of the first-stage tubular reactor is equipped with a temperature control element T. N+1 The F N+1 With the T N+1 Cascade control.

8. A method for dehydrogenating organic hydrides using the organic hydride dehydrogenation reaction system according to any one of claims 1-7, characterized in that, include: Organic hydrides enter the tube layer of the nth-stage tubular reactor, where they contact the catalyst and undergo a dehydrogenation reaction. The products of the nth-stage reaction flow out through the tube layer outlet of the nth-stage tubular reactor and enter the tube layer of the (n+1)th-stage tubular reactor. The heat carrier enters the shell layer of the nth-stage tubular reactor via branches n1 and n2, providing heat for the dehydrogenation reaction in the tube layer. The flow control element F in branch n3... n Adjust the flow rate of branch n3 to regulate the temperature of the nth stage reaction product at the outlet of the tube layer of the nth stage tubular reactor.

9. The method for dehydrogenating organic hydrides according to claim 8, characterized in that, The temperature of the first-stage reaction product at the outlet of the first-stage reactor tube layer is 250℃~420℃; And / or, the temperature of the second-stage reaction product at the outlet of the second-stage reactor tube layer is 250~420℃; And / or, the temperature of the third-stage reaction product at the outlet of the third-stage reactor tube layer is 250~420℃; And / or, the organic hydride is first vaporized and / or superheated before entering the tube layer of the first-stage tubular reactor; And / or, the flow direction of organic hydrides in the tube layer of the nth stage tubular reactor is parallel to the flow direction of the heat carrier in the shell layer; And / or, when n=N; the flow control element F through branch (N+1)2 N+1 Adjust the flow rate of branch (N+1)2 to regulate the temperature of the organic hydride at the tube inlet of the first-stage tubular reactor; And / or, the temperature of the organic hydride at the inlet of the tube layer of the first-stage tubular reactor is 280–360 °C.

10. The method for dehydrogenating organic hydrides according to claim 9, characterized in that, The temperature of the first-stage reaction product at the outlet of the first-stage reactor tube layer is 320℃; And / or, the temperature of the second-stage reaction product at the outlet of the second-stage reactor tube layer is 340°C; And / or, the temperature of the third-stage reaction product at the outlet of the third-stage reactor tube layer is 360°C; And / or, the temperature of the organic hydride at the inlet of the tube layer of the first-stage tubular reactor is 280–300°C; And / or, the temperature of the organic hydride at the inlet of the tube layer of the nth stage tubular reactor is 250–420 °C.

11. The method for dehydrogenating organic hydrides according to claim 9 or 10, characterized in that, The organic hydride is selected from at least one of substituted or unsubstituted alkanes, substituted or unsubstituted cycloalkanes, substituted or unsubstituted alkenes, substituted or unsubstituted monocyclic aromatics, and substituted or unsubstituted polycyclic aromatics.

12. The method for dehydrogenating organic hydrides according to claim 11, characterized in that, The substituted or unsubstituted alkanes are selected from at least one of C1-C6 alkanes; and / or, the substituted or unsubstituted cycloalkanes are selected from at least one of C3-C6 cycloalkanes; and / or, the substituted or unsubstituted olefins are selected from at least one of C2-C6 olefins; and / or, the substituted or unsubstituted monocyclic aromatic hydrocarbons are selected from at least one of ethylbenzene, dibenzyltoluene, cyclohexylbenzene, and dicyclohexylbenzene; and / or, the substituted or unsubstituted polycyclic aromatic hydrocarbons are selected from at least one of tetrahydronaphthalene and decahydronaphthalene.

13. The method for dehydrogenating organic hydrides according to claim 12, characterized in that, The substituted or unsubstituted alkane is selected from propane or butane; and / or, the substituted or unsubstituted cycloalkane is selected from cyclohexane or methylcyclohexane; and / or, the substituted or unsubstituted olefin is selected from butene.

14. The method for dehydrogenating organic hydrides according to claim 9 or 10, characterized in that, The heat transfer medium is selected from steam or molten salt.

15. The method for dehydrogenating organic hydrides according to claim 14, characterized in that, The molten salt is selected from at least one of potassium nitrate, sodium nitrite, and sodium nitrate. And / or, the molten salt is composed of potassium nitrate, sodium nitrite and sodium nitrate in a weight ratio of (40-60):(30-50):(5-10); And / or, the molten salt is composed of 53% potassium nitrate, 40% sodium nitrite and 7% sodium nitrate.

16. The method for dehydrogenating organic hydrides according to claim 9 or 10, characterized in that, Within the tubes of the nth-stage tubular reactor, the dehydrogenation reaction conditions include: a reaction temperature of 250℃~420℃; a reaction pressure of 0.02 MPaA~1.0 MPaA; and a total mass hourly space velocity (GHSV) of 0.5 h⁻¹. 1 ~5 h 1 ; And / or, the shell feed manifold P of the nth stage tubular reactor. n In this case, the flow rate of the heat transfer fluid is 5000~10000 kg / h; The flow rate of the branch n1 in the shell of the nth stage tubular reactor is 2000 ~ 3000 kg / h; The flow rate of the shell branch n2 of the nth stage tubular reactor is 1500~4000 kg / h; The flow velocity in the shell branch n3 of the nth stage tubular reactor is 1000~3000 kg / h; The total mass hourly space velocity (GSLV) of the organohydrides at the inlet of the nth stage tubular reactor is 4–20 h⁻¹. -1 .

17. The method for dehydrogenating organic hydrides according to claim 16, characterized in that, Within the tube layer of the nth-stage tubular reactor, the dehydrogenation reaction conditions include: a reaction temperature of 280℃~400℃; a reaction pressure of 0.1 MPaA~0.4 MPaA; and a total mass hourly space velocity (GHSV) of 2 h⁻¹. 1 ~4 h 1 ; The flow rate of the shell branch n1 of the nth stage tubular reactor is 1600 ~ 2400 kg / h; The flow rate of the shell branch n2 of the nth stage tubular reactor is 3000~3600 kg / h; The flow velocity in the shell branch n3 of the nth stage tubular reactor is 1200~1600 kg / h.

18. The method for dehydrogenating organic hydrides according to claim 9 or 10, characterized in that, The temperature of the heat carrier at the inlet of the shell layer of the nth stage tubular reactor is 40°C to 150°C higher than the temperature of the reactants at the inlet of the tube layer. And / or, the temperature of the reactants at the inlet of the tube layer of the (n+1)th stage tubular reactor is 10°C to 60°C higher than the temperature of the reactants at the inlet of the tube layer of the nth stage tubular reactor; And / or, the flow rate of branch n1 of the nth stage tubular reactor accounts for a portion of the total feed pipe P of the shell. n 10% to 50% of the total flow.

19. The method for dehydrogenating organic hydrides according to claim 18, characterized in that, The temperature of the heat carrier at the inlet of the shell layer of the nth stage tubular reactor is 50°C to 120°C higher than the temperature of the reactants at the inlet of the tube layer. And / or, the temperature of the reactants at the inlet of the tube layer of the (n+1)th stage tubular reactor is 15°C to 35°C higher than the temperature of the reactants at the inlet of the tube layer of the nth stage tubular reactor; And / or, the flow rate of branch n1 of the nth stage tubular reactor accounts for a portion of the total feed pipe P of the shell. n It accounts for 20% to 30% of the total flow.

20. The method for dehydrogenating organic hydrides according to claim 19, characterized in that, The temperature of the reactants at the inlet of the (n+1)th stage tubular reactor is 20°C higher than the temperature of the reactants at the inlet of the nth stage tubular reactor.

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