Organic hydride dehydrogenation reaction system and method

Abstract

This invention relates to an organic hydride dehydrogenation reaction system and method, belonging to the field of chemical processes. The system comprises an N-stage tubular reactor with sequentially connected tube sides and sequentially connected shell sides, where N≥2. The organic hydride dehydrogenation reaction system also includes a second heat exchanger E2 and a third heat exchanger E3. The second heat exchanger E2 consists of heat exchange pipes II and II' capable of heat exchange; the third heat exchanger E2 consists of heat exchange pipes III and III' capable of heat exchange. The organic hydride source, heat exchange pipes II and III, and the tube side inlet of the first-stage tubular reactor are sequentially connected. The tube side outlet of the Nth-stage tubular reactor is connected to heat exchange pipe II'; the shell side outlet of the Nth-stage tubular reactor is connected to heat exchange pipe III'. This invention mainly solves the problems of easy coking and deactivation of dehydrogenation catalysts, insufficient process energy utilization, and low product hydrogen concentration in current technologies.

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 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. At the reactor inlet, the heat from the shell-side heat carrier has not yet been transferred to the inside of the tubes. At this point, the heat required for the dehydrogenation reaction is mainly provided by the reactants themselves. Under the action of the catalyst, the reaction rate is fast, the endothermic reaction is large, and the system temperature drops rapidly. As the reaction proceeds, the reaction rate slows down, and the heat carried by the shell-side heat carrier can be supplied to the inside of the tubes for the dehydrogenation reaction in a timely manner. The heating rate and the reaction rate maintain a relatively balanced state. At this time, the system temperature gradually rises again. Therefore, the catalyst temperature inside the tubes experiences a process of steep drop followed by slow rise. Near the temperature inflection point, the catalyst is prone to coking and deactivation.

[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] Most of the above processes maintain catalyst performance stability by sacrificing some catalyst or at the cost of energy consumption. They fail to effectively match reaction rate and heating rate, shorten catalyst life, and result in insufficient utilization of system heat, thus increasing hydrogen storage costs. Summary of the Invention

[0007] To address the aforementioned problems, this invention provides an organic hydride dehydrogenation system and method, which mainly solves the current issues of easy coking and deactivation of dehydrogenation catalysts, insufficient process energy utilization, and low product hydrogen concentration. It has the advantages of long catalyst life, sufficient system energy utilization, high product hydrogen purity, and low total cost.

[0008] On one hand, the present invention provides an organic hydride dehydrogenation reaction system, comprising an N-stage tubular reactor with tubes connected in series and shells connected in series, where N≥2; the organic hydride dehydrogenation reaction system further comprises a second heat exchanger E2 and a third heat exchanger E3; the second heat exchanger E2 is composed of heat exchange pipes II and II' capable of heat exchange; the third heat exchanger E2 is composed of heat exchange pipes III and III' capable of heat exchange; the organic hydride source, heat exchange pipes II, III, and the tube inlet of the first-stage tubular reactor are connected in sequence; the tube outlet of the Nth-stage tubular reactor is connected to heat exchange pipe II'; the shell outlet of the Nth-stage tubular reactor is connected to heat exchange pipe III'.

[0009] The N (N≥2) stage tubular reactors described in this invention are connected in series, meaning that the tubes 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 connected sequentially via pipelines. Preferably, the outlet of the tube side of the first-stage tubular reactor is connected to the inlet of the tube side of the second-stage tubular reactor via a pipeline, ..., the outlet of the tube side of the nth-stage tubular reactor is connected to the inlet of the tube side of the (n+1)th-stage tubular reactor via a pipeline, the outlet of the tube side of the (n+1)th-stage tubular reactor is connected to the inlet of the tube side of the (n+2)th-stage tubular reactor via a pipeline, ..., the outlet of the tube side of the (N-1)th-stage tubular reactor is connected to the inlet of the tube side of the Nth-stage tubular reactor via a pipeline.

[0010] The N (N≥3) stage tubular reactors described in this invention are connected in series in shell-side configuration, meaning that the shell-sides 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 via pipelines. Preferably, the shell-side outlet of the first-stage tubular reactor is connected to the shell-side inlet of the second-stage tubular reactor via a pipeline; the shell-side outlet of the nth-stage tubular reactor and the shell-side inlet of the (n+1)th-stage tubular reactor are connected via a pipeline; the shell-side outlet of the (n+1)th-stage tubular reactor and the shell-side inlet of the (n+2)th-stage tubular reactor are connected via a pipeline... and the shell-side outlet of the (N-1)th-stage tubular reactor is connected to the shell-side inlet of the Nth-stage tubular reactor via a pipeline.

[0011] Optionally, the shell-side inlet of the nth stage tubular reactor is equipped with a heater H. n n = any integer from 1 to N.

[0012] Preferably, the organic hydride dehydrogenation reaction system further includes 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; when n=1, the heat carrier source, heat exchange pipeline I, heater H1, and shell-side inlet of the first-stage tube reactor are connected in sequence; the heat exchange pipeline III' is connected to the heat exchange pipeline I'.

[0013] Preferably, the organic hydride dehydrogenation reaction system further includes a cooler and a gas-liquid separator; the tube-side outlet of the Nth stage tubular reactor is sequentially connected to heat exchange pipeline II', the cooler and the gas-liquid separator; preferably, the gas phase outlet of the gas-liquid separator is connected to the tube-side inlet of the first stage tubular reactor; preferably, the gas phase outlet of the gas-liquid separator has multiple branches, of which at least one branch is connected to the tube-side inlet of the first stage tubular reactor.

[0014] Preferably, the organic hydride dehydrogenation reaction system further includes a cooler, a first gas-liquid separator, a compressor, and a second gas-liquid separator; the tube-side outlet of the Nth stage tubular reactor is sequentially connected to heat exchange pipeline II', the cooler, and the first gas-liquid separator; the gas phase outlet of the first gas-liquid separator is sequentially connected to the compressor and the second gas-liquid separator; the gas phase outlet of the second gas-liquid separator is connected to the tube-side inlet of the first stage tubular reactor; preferably, the gas phase outlet of the second gas-liquid separator has multiple branch pipes, of which at least one branch pipe is connected to the tube-side inlet of the first stage tubular reactor.

[0015] Preferably, 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, and more preferably, the ratio is 0.9 to 1.1.

[0016] 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.

[0017] On the other hand, the present invention also provides a method for dehydrogenating organic hydrides using the aforementioned organic hydride dehydrogenation reaction system, comprising: each tube of the N-stage tubular reactor is loaded with a catalyst and inert ceramic elements; the tubes in the first-stage tubular reactor are axially divided into M equal segments, where M is an integer, 5≤M≤20, and the volume ratio of the catalyst in the M-th segment to the catalyst in the (M-1)-th segment is R, 1.05≤R≤1.5; each segment of catalyst is uniformly mixed with the inert ceramic elements; in the second to N-stage tubular reactors, the volume ratio of the catalyst to the inert ceramic elements is 1 / Y, 1≤Y≤4, and the catalyst is uniformly mixed with the inert ceramic elements; the catalyst loading amount is the same in each stage of the tubular reactor; organic hydride dehydrogenation... The chemical is first vaporized in the second heat exchanger E2, then heated to the initial reaction temperature in the third heat exchanger E3, and then enters the tube side of the first-stage tubular reactor R1, which contains the catalyst and inert ceramic parts, to undergo a dehydrogenation reaction. The nth-stage reaction product enters the (n+1)th-stage tubular reactor to undergo the nth-stage reaction. The Nth-stage reaction product flows through the second heat exchanger E2 as the heat source for E2. The heat carrier enters the shell side of the nth-stage tubular reactor to provide heat for the dehydrogenation reaction in the nth-stage tube side. It then enters the shell side of the (n+1)th-stage tubular reactor to provide heat for the dehydrogenation reaction in the (n+1)th-stage tube side. The heat carrier exiting the shell side of the Nth-stage reactor flows through the third heat exchanger E3 as the heat source for E3.

[0018] Optionally, the ceramic component is a ceramic ring or ceramic granule;

[0019] Preferably, 9 ≤ M ≤ 12;

[0020] Preferably, 1.05 ≤ R ≤ 1.3, more preferably 1.2 ≤ R ≤ 1.4

[0021] Preferably, Y = 3;

[0022] Optionally, the catalyst has a particle size of 1.8–2 mm, and the inert ceramic rings have a particle size of 2–5 mm and are filled into a cylinder with a height of 3–8 mm.

[0023] Optionally, the heat carrier is first preheated by the first heat exchanger E1, and then heated by the first-stage heater H1 before entering the shell side of the first-stage tubular reactor to provide heat for the dehydrogenation reaction in the tube side.

[0024] Optionally, after the Nth stage reaction product flows out of E2, it passes through a cooler to form a gas-liquid mixture; the gas-liquid mixture is then separated to obtain a gas phase and a liquid phase.

[0025] Optionally, the gas-liquid mixture flows through the first gas-liquid separator V1 for gas-liquid separation I to obtain crude hydrogen and toluene, with a separation pressure of 0.02 MPaA to 1.0 MPaA at the cooler outlet pressure. The separation temperature of gas-liquid separation I is 5 to 60°C, preferably 35 to 45°C. The crude hydrogen is then compressed at least once and then passed through the second gas-liquid separator V2 for gas-liquid separation II to obtain high-purity product hydrogen and toluene. The separation pressure is 0.4 MPaA to 3 MPaA at the compressor outlet pressure connected to the gas-liquid separator. The separation temperature of gas-liquid separation II is 5 to 60°C, preferably 35 to 45°C. The high-purity product hydrogen is divided into two streams, one of which is used as circulating hydrogen and returned to the tube side of the first-stage reactor.

[0026] Optionally, the compressor outlet pressure is 0.4 MPaA to 3 MPaA, and preferably, the pressure is 1.0 MPaA to 2.0 MPaA.

[0027] Optionally, the circulating hydrogen is first combined with the organic hydride and then returned to the tube side of the first-stage reactor; the combination point is before the second heat exchanger E2, or before the third heat exchanger E3, or before the first-stage reactor.

[0028] Optionally, the temperature of the heat transfer fluid at the inlet of the shell side of the nth stage tubular reactor is 350–500°C, preferably 400°C.

[0029] Optionally, the temperature of the reactant at the inlet of the tube side 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 side of the nth stage tubular reactor, preferably 15°C to 35°C, and more preferably 20°C.

[0030] Optionally, the temperature of the reactants at the tube inlet of the first-stage tubular reactor is 280–320°C, preferably 300°C.

[0031] Optionally, the temperature of the reactants at the tube inlet of the second-stage tubular reactor is 280–340°C, preferably 320°C.

[0032] Optionally, the temperature of the organic hydride at the tube inlet of the nth stage tubular reactor is 280–380 °C.

[0033] Optionally, the temperature of the heat carrier at the inlet of the shell side 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 side, preferably 50°C to 120°C.

[0034] 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.

[0035] Optionally, the substituted or unsubstituted alkane is selected from at least one of C1-C6 alkanes; preferably propane or butane.

[0036] Optionally, the substituted or unsubstituted cycloalkane is selected from at least one of C3-C6 alkanes; preferably cyclohexane or methylcyclohexane.

[0037] Optionally, the substituted or unsubstituted olefin is selected from at least one of C2-C6 olefin hydrocarbons; preferably butene.

[0038] Optionally, the substituted or unsubstituted monocyclic aromatic hydrocarbon is selected from at least one of ethylbenzene, dibenzyltoluene, cyclohexylbenzene, and dicyclohexylbenzene.

[0039] Optionally, the substituted or unsubstituted fused-ring aromatic hydrocarbon is selected from at least one of tetrahydronaphthalene and decahydronaphthalene.

[0040] Optionally, the heat transfer medium is selected from steam or molten salt;

[0041] Optionally, the molten salt is selected from at least one of potassium nitrate, sodium nitrite, and sodium nitrate;

[0042] 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);

[0043] Optionally, the molten salt is preferably composed of 53% potassium nitrate, 40% sodium nitrite and 7% sodium nitrate.

[0044] Optionally, the flow direction of organic hydrides in the tube side of the nth stage tubular reactor is parallel to the flow direction of the heat carrier in the shell side.

[0045] Alternatively, the cooling medium for the reaction products may be air or water.

[0046] Optionally, within the tube side of the nth stage tubular reactor, the dehydrogenation reaction conditions include: a reaction temperature of 200℃~500℃, preferably 250℃~400℃; a reaction pressure of 0.02MPaA~1.0MPaA, preferably 0.1MPaA~0.4MPaA; and a total mass hourly space velocity (WHSV) of 0.5h⁻¹ for the organic hydrides. -1 ~5h -1 2h preferred -1 ~4h -1The ratio of the flow rate of the heat carrier at the shell-side inlet of the first-stage tubular reactor to the flow rate of the organic hydride at the tube-side inlet of the first-stage tubular reactor is 2–5; the total mass hourly space velocity (MSV) of the organic hydride at the tube-side inlet of the first-stage tubular reactor is 4–20 h⁻¹. -1 .

[0047] Optionally, the content of recycled hydrogen in the total gas phase is 5% to 50%, preferably 10% to 20%.

[0048] This invention optimizes the catalyst loading in the first reactor by introducing inert ceramic balls, allowing the catalyst loading to gradually increase from the inlet to the outlet. This reduces the degree of dehydrogenation reaction and slows the reaction rate due to the lower catalyst loading at the inlet, preventing a sudden drop in catalyst temperature. Subsequently, as the reaction rate and heating rate are matched, the catalyst temperature distribution throughout the entire tube is uniform, ensuring that the reaction rate and conversion rate of each reactor are within a reasonable range, significantly improving catalyst lifespan. Furthermore, by recovering heat from the reaction products and heat carrier, the energy utilization rate of the entire device is greatly increased, and the purity of the product hydrogen is significantly improved through staged compression of the crude hydrogen.

[0049] By adopting the technical solution of this invention, for devices using methylcyclohexane as dehydrogenation feedstock, the catalyst life is increased by 1 to 2 times, the hydrogen purity is higher than 99.9 vol%, and the dehydrogenation cost is reduced by 10%, achieving good technical results. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the organic hydride dehydrogenation system in Example 1.

[0051] Figure 1 In the middle, 1 is the first-stage tubular reactor R1, 2 is the second-stage tubular reactor R2, 3 is the first heat exchanger E1 (preheater), 4 is the first-stage heater H1, 5 is the second-stage heater H2, 6 is the second heat exchanger E2 (vaporizer), 7 is the third heat exchanger E3 (superheater), 8 is the cooler, 9 is the first gas-liquid separator V1, 10 is the compressor, and 11 is the second gas-liquid separator V2;

[0052] 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 Reaction product at the outlet of the first-stage tubular reactor, 105 Reaction product at the outlet of the second-stage tubular reactor; 106 Crude hydrogen, 107 Toluene, 108 High-purity product hydrogen, 109 High-purity product hydrogen as recycled hydrogen.

[0053] 111 Heat carrier source, 112 Heat carrier at the outlet of the first-stage tubular reactor, 113 Heat carrier at the outlet of the second-stage tubular reactor; 114 Heat carrier to the outside of the boundary.

[0054] Figure 2 This is a temperature distribution diagram of the R1 tube side in Example 2. Figure 2 In this context, T represents temperature, and L represents the tube length.

[0055] Figure 3 This is a temperature distribution diagram of the R1 tube side in Example 3. Figure 3 In this context, T represents temperature, and L represents the tube length.

[0056] Figure 4 This is a temperature distribution diagram of the R1 tube side in Example 4. Figure 4 In this context, T represents temperature, and L represents the tube length.

[0057] Figure 5 This is a temperature distribution diagram of the R1 tube side in Example 5. Figure 5 In this context, T represents temperature, and L represents the tube length. Detailed Implementation

[0058] This invention addresses the problem by employing a heated heat carrier that enters the shell side of a multi-stage tubular reactor to provide heat for the dehydrogenation reaction in the tube side. It also controls the dehydrogenation conversion rate and reaction rate of each stage reactor by controlling the inlet temperature of the first-stage reactor tube side and the inlet temperature of the heat carrier in each stage reactor. The reaction products, after vaporizing the raw materials, undergo cooling, gas-liquid separation, pressurization, and further gas-liquid separation to obtain high-purity hydrogen. This technical solution effectively solves the problem and can be used in the industrial production of organic hydride hydrogen storage.

[0059] 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:

[0060] The tubular reactor is filled with catalyst and inert ceramic rings in the tube side;

[0061] Each stage of the N-stage tubular reactor contains a catalyst and inert ceramic components.

[0062] In the first-stage tubular reactor, the tubes are divided into M equal segments along the axial direction, where M is 5.

[0063] The volume ratio of the catalyst in section M to the catalyst in section M-1 is R, where R is 1.05.

[0064] In the tubular reactors of stages 2 to N, the volume ratio of the catalyst to the inert ceramic element is 1 / Y, where Y = 3, and the catalyst loading is the same in each stage of the tubular reactor.

[0065] Organic hydride 101 is first vaporized in the second heat exchanger E2 (vaporizer), then heated to the initial reaction temperature in the third heat exchanger E3 (superheater), and then enters the tube side of the first-stage tubular reactor R1 containing the catalyst to undergo a dehydrogenation reaction until it flows out from the tube side of the Nth-stage tubular reactor, yielding a reaction product containing hydrogen, where N≥2; the reaction product containing hydrogen flows through the second heat exchanger E2 (vaporizer) as the heat source for E2, and after flowing out from E2, it passes through a cooler to form a gas-liquid mixture; the gas-liquid mixture flows through the first gas-liquid separator V1 to obtain crude hydrogen 106 and toluene respectively; the crude hydrogen 106 is compressed at least once and then separated by the gas-liquid separator V2 to obtain high-purity product hydrogen (108, 109) and toluene; the high-purity product hydrogen is divided into two streams, one of which, 109, is used as circulating hydrogen and mixed with organic hydride 103 before returning to the tube side of the first-stage reactor;

[0066] Heat carrier 111 is first preheated by the first heat exchanger E1 (preheater), then heated by the first stage heater H1, and enters the shell side of the first-stage tubular reactor 100mm below the top of the tubes to provide heat for the dehydrogenation reaction in the tubes. After flowing out of the shell side outlet of the first-stage tubular reactor, it enters the second stage heater H2 for heating, and then enters the shell side of the second-stage tubular reactor until it flows out of the shell side of the Nth-stage tubular reactor. The heat carrier at the shell side outlet of the Nth-stage tubular reactor first serves as the heat source for the third heat exchanger E3 (superheater) in step 3, then as the heat source for the first heat exchanger E1 (preheater), and finally is connected to the steam network.

[0067] d controls the temperature at the outlet of the first-stage heater H1 (the temperature of the heat carrier at the inlet of the shell side of the first-stage tubular reactor); controls the temperature of the mixture of 109 and 103 (the temperature of the tube side of the first-stage tubular reactor).

[0068] Example 1: Tubular Organic Hydrogen Dehydrogenation System (Taking a Two-Stage Tubular Reactor as an Example)

[0069] The tubular organic hydride dehydrogenation reaction system mainly consists of a first-stage tubular reactor R1, a second-stage tubular reactor R2, a first heat exchanger E1 (preheater), a first-stage heater H1, a second-stage heater H2, a second heat exchanger E2, a third heat exchanger E3, a cooler, a first gas-liquid separator V1, a compressor, and a second gas-liquid separator V2.

[0070] R1 and R2 have the same tube specifications, which are The tubes are 4 meters long and consist of 1000 tubes. The diameter of the shell side (reactor body) is 1200 mm. The tubes of R1 and R2 are filled with catalyst and inert ceramic rings.

[0071] The first heat exchanger E1 consists of heat exchange pipe I and heat exchange pipe I' capable of heat exchange; the second heat exchanger E2 consists of heat exchange pipe II and heat exchange pipe II' capable of heat exchange; and the third heat exchanger E3 consists of heat exchange pipe III and heat exchange pipe III' capable of heat exchange.

[0072] The heat carrier source 111 is connected to heat exchange pipe I of the first heat exchanger E1 (preheater), and then connected to the inlet of the first heater H1. The outlet of H1 is connected to the shell side of R1 100 mm below the top of the tubes of R1. The shell side outlet of R1 (located at the lower part of R1, specifically 100 mm above the bottom of the tubes) is connected to the inlet of the second heater H2. The outlet of H2 is connected to the shell side of R2 100 mm below the top of the tubes of R2. The shell side outlet of R2 (located at the lower part of R2, specifically 100 mm above the bottom of the tubes) is connected to heat exchange pipe III' of the third heat exchanger E3, where heat exchange occurs with heat exchange pipe III, and then connected to heat exchange pipe I' of the first heat exchanger E1, where heat exchange occurs with heat exchange pipe I.

[0073] Organic hydride source 101 is sequentially connected to heat exchange pipe II of the second heat exchanger E2 (vaporizer) and heat exchange pipe III of the third heat exchanger E3 (superheater). Heat exchange pipe III is connected to the tube-side inlet of R1 (located at the top of R1) via a pipe; the tube-side outlet of R1 (located at the bottom of R1) is connected to the tube-side inlet of R2 (located at the top of R2); the tube-side outlet of R2 (located at the bottom of R2) is connected to heat exchange pipe II' of the second heat exchanger E2, where heat exchange occurs, and then... The secondary cooler and the first gas-liquid separator V1 are connected. The gas phase outlet of the first gas-liquid separator V1 (located at the top of the first gas-liquid separator V1) is connected to the second gas-liquid separator V2 via the compressor. The gas phase outlet of the second gas-liquid separator V1 (located at the top of the second gas-liquid separator V2) is connected to two parallel streams, one of which is connected to the tube inlet of R1. The liquid phase outlet of the first gas-liquid separator V1 (located at the bottom of the first gas-liquid separator V1) is connected to the liquid phase outlet of the second gas-liquid separator V2 (located at the bottom of the second gas-liquid separator V2).

[0074] Example 2: Dehydrogenation reaction method for organic hydrides

[0075] A hydrogen production plant with an annual capacity of 1000 tons uses methylcyclohexane as a dehydrogenation feedstock, employing the system described in Example 1. Figure 1 The process technology shown uses saturated steam at 1.0 MPaA as the heat transfer medium and employs a two-stage compression process. Figure 1 The diagram only shows the first-level compression; the main operating conditions and running status are shown in Table 1.

[0076] The conversion rate of methylcyclohexane is calculated using formula (1).

[0077]

[0078] 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.

[0079] 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 2.

[0080] 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.

[0081] The flow direction of the heat transfer fluid (water vapor) in the shell side of a tubular reactor:

[0082] After being heated by the first-stage heater H1, the heat carrier 108 (steam) enters the shell side of R1 100 mm below the top of the tubes, providing heat for the dehydrogenation reaction in the tube side of R1. Then, it flows out from the shell side outlet of R1 (located at the bottom of R1, specifically 100 mm above the bottom of the tubes) and is heated by the second-stage heater H2. It then enters the shell side of R2 100 mm below the top of the tubes and flows out from the shell side outlet of R2 (located at the bottom of R2, specifically 100 mm above the bottom of the tubes). After flowing out, it flows through the heat exchange tube III' of the third heat exchanger E3 (superheater), serving as the heat source for heat exchange tube III of E3. After flowing out of E3, it flows through the heat exchange tube I' of the first heat exchanger E1 (preheater), serving as the heat source for heat exchange tube I of E1. After flowing out of E1, it is connected to the steam network.

[0083] Flow direction of organic hydride (methylcyclohexane) in tubes R1 and R2:

[0084] Methylcyclohexane 101 first flows through heat exchange tube II of the second heat exchanger E2, where it is heated and vaporized by the R2 tube outlet product 105 in heat exchange tube II' (vaporization temperature is 145°C). Then it flows through heat exchange tube III of the third heat exchanger E3, where it is heated to the initial reaction temperature (320°C) by the heat carrier 113 in heat exchange tube III'. After merging with 109, it enters the R1 tube inlet (located at the top of R1) to undergo the first stage of dehydrogenation reaction. The R1 outlet product 104 is discharged from the R1 tube outlet (located at the bottom of R1). Then, the second-stage dehydrogenation reaction occurs in R2. The initial reaction temperature in R2 is 340°C. The hydrogen-containing product 105 flows out from the tube-side outlet of R2 (located at the bottom of R2) and flows through the heat exchange tube II' of the second heat exchanger E2, serving as the heat source for heat exchange tube II of the second heat exchanger E2. After flowing out of the second heat exchanger E2, it is cooled by a cooler and then enters the first gas-liquid separator V1. The separation pressure is the cooler outlet pressure of 0.28 MPaA, and the separation temperature of gas-liquid separation I is 35°C. The gas phase 106 is compressed by a compressor and then enters the second gas-liquid separator V2. The separation pressure is the compressor outlet pressure connected to the gas-liquid separator of 1.1 MPaA, and the separation temperature of gas-liquid separation II is 35°C. The gas phase in the second gas-liquid separator V1 splits into two streams, with 109 and 103 merging and entering the tube side of R1. The liquid phases in the first gas-liquid separator V1 and the second gas-liquid separator V2 merge.

[0085] Table 1

[0086] project Operating conditions <![CDATA[Reaction pressure in R1 and R2, MPaA]]> 0.3 <![CDATA[Loading ratio of the catalyst in R2 to the catalyst in R1]]> 1.1 (Height) <![CDATA[Number of segments M in R1]]> 5 <![CDATA[Volume ratio of the (M + 1)-th catalyst segment to the M-th catalyst segment in R1]]> 1.05 <![CDATA[Volume ratio of catalyst to inert porcelain rings in R2]]> 3 <![CDATA[The inlet temperature of the shell side of R1, °C]]> 440 <![CDATA[The inlet temperature of the shell side of R2, °C]]> 440 <![CDATA[Tube-side inlet temperature of R1, °C]]> 320 <![CDATA[Tube-side inlet temperature of R2, °C]]> 340 <![CDATA[Difference between the inlet temperature and the lowest temperature of the R1 tube side, °C]]> 50 <![CDATA[Conversion rate of methylcyclohexane of R1, %]]> 65.0 <![CDATA[Conversion rate of methylcyclohexane of R2, %]]> 86.0 Total conversion of methylcyclohexane, % 95.1 The percentage of recycled hydrogen to product hydrogen, %. 20 Steam (heat carrier) usage, kg / h 12000 Product hydrogen pressure, MPaA 1.1 Product hydrogen concentration, vol% 99.90 Catalyst regeneration cycle, month 24

[0087] Figure 2 This is the temperature distribution diagram of the R1 tube side. When the material enters the tube, it undergoes a rapid dehydrogenation reaction under the action of the catalyst, and the temperature inside the tube drops sharply, reaching a minimum of 270°C at 0.2m. Subsequently, as the reaction rate and heating rate are matched, the catalyst temperature throughout the tube side slowly increases.

[0088] Example 3

[0089] A hydrogen production plant with an annual capacity of 1000 tons uses methylcyclohexane as a dehydrogenation feedstock, employing the system described in Example 1. Figure 1 The process technology shown is the same as that of Example 2, but with the number of catalyst segments in R1 changed. The other process parameters are the same as those of Example 2. The equipment parameters are listed in Table 2.

[0090] Table 2

[0091] project Operating conditions <![CDATA[Reaction pressure in R1 and R2, MPaA]]> 0.3 <![CDATA[Number of segments M in R1]]> 20 <![CDATA[Volume ratio of the (M + 1)-th stage catalyst to the M-th stage catalyst in R1]]> 1.05 <![CDATA[Volume ratio of catalyst to inert porcelain rings in R2]]> 3 <![CDATA[The inlet temperature of the shell side of R1, °C]]> 440 <![CDATA[The inlet temperature of the shell side of R2, °C]]> 440 <![CDATA[Tube-side inlet temperature of R1, °C]]> 320 <![CDATA[Tube-side inlet temperature of R2, °C]]> 340 <![CDATA[The temperature difference between the inlet temperature and the lowest temperature of the R1 tube side, °C]]> 40 <![CDATA[Conversion rate of methylcyclohexane of R1, %]]> 68.0 <![CDATA[Conversion rate of methylcyclohexane of R2, %]]> 88.0 Total conversion of methylcyclohexane, % 96.1 The percentage of recycled hydrogen to product hydrogen, %. 20 Steam (heat carrier) usage, kg / h 12000 Product hydrogen pressure, MPaA 1.1 Product hydrogen concentration, vol% 99.92 Catalyst regeneration cycle, month 28

[0092] Figure 3This is the temperature distribution diagram of the R1 tube. The material enters the tube and undergoes a rapid dehydrogenation reaction under the action of the catalyst, causing the temperature inside the tube to drop sharply. However, since the number of segments in R1 is greater than that in Example 2, the amount of catalyst loaded at the inlet is reduced, and the temperature drops to a minimum of 280°C at 0.2m, which is 10°C higher than the minimum temperature in Example 1. Subsequently, as the reaction rate and heating rate are matched, the catalyst temperature throughout the tube slowly increases.

[0093] Example 4

[0094] A hydrogen production plant with an annual capacity of 1000 tons uses methylcyclohexane as a dehydrogenation feedstock, employing the system described in Example 1. Figure 1 The process technology shown is the same as that of Example 2 for the dehydrogenation reaction of organic hydrides. The number of catalyst segments in R1 and the volume ratio of the catalyst in the (M+1)th segment to the Mth segment in R1 are changed. The other process parameters are the same as those in Example 2. The equipment parameters are listed in Table 3.

[0095] Table 3

[0096] project Operating conditions <![CDATA[Reaction pressure in R1 and R2, MPaA]]> 0.3 <![CDATA[Number of segments M in R1]]> 10 <![CDATA[Volume ratio of the (M + 1)-th stage catalyst to the M-th stage catalyst in R1]]> 1.3 <![CDATA[Volume ratio of catalyst to inert porcelain rings in R2]]> 3 <![CDATA[The inlet temperature of the shell side of R1, °C]]> 440 <![CDATA[The inlet temperature of the shell side of R2, °C]]> 440 <![CDATA[Tube-side inlet temperature of R1, °C]]> 320 <![CDATA[Tube-side inlet temperature of R2, °C]]> 340 <![CDATA[Difference between the inlet temperature and the lowest temperature of the R1 tube side, °C]]> 5 <![CDATA[Conversion rate of methylcyclohexane of R1, %]]> 69.0 <![CDATA[Conversion rate of methylcyclohexane of R2, %]]> 91.0 Total conversion of methylcyclohexane, % 97.2 The percentage of recycled hydrogen to product hydrogen, %. 20 Steam (heat carrier) usage, kg / h 12000 Product hydrogen pressure, MPaA 1.1 Product hydrogen concentration, vol% 99.98 Catalyst regeneration cycle, month 40

[0097] Figure 4 This is the temperature distribution diagram of the R1 tube. After the volume ratio of catalyst in section M+1 to section M is increased from 1.05 to 1.3, the amount of catalyst loaded at the inlet is further reduced. At this time, the reaction at the inlet is mild, the reaction rate and the heating rate can be well matched, and the lowest temperature is only 315℃. The temperature distribution of the entire tube is uniform.

[0098] Comparative Example

[0099] A hydrogen production plant with an annual capacity of 1000 tons uses methylcyclohexane as a dehydrogenation feedstock, employing the system described in Example 1. Figure 1 The process technology shown differs from the dehydrogenation reaction method of the organic hydride in Example 2 only in that the catalyst in R1 is not segmented, the heat carrier is saturated water vapor at 1.0 MPaA, and a two-stage compression is used. Figure 1 The diagram only shows the first-level compression; the main operating conditions and running status are shown in Table 4.

[0100] Table 4

[0101] project Operating conditions <![CDATA[Reaction pressure in R1 and R2, MPaA]]> 0.3 <![CDATA[Volume ratio of catalyst to inert porcelain rings in R1 and R2]]> 3 <![CDATA[The inlet temperature of the shell side of R1, °C]]> 440 <![CDATA[The inlet temperature of the shell side of R2, °C]]> 440 <![CDATA[Tube-side inlet temperature of R1, °C]]> 320 <![CDATA[Tube-side inlet temperature of R2, °C]]> 340 <![CDATA[Difference between the inlet temperature and the lowest temperature of the R1 tube side, °C]]> 70 <![CDATA[Conversion rate of methylcyclohexane of R1, %]]> 63.0 <![CDATA[Conversion rate of methylcyclohexane of R2, %]]> 85.0 Total conversion of methylcyclohexane, % 94.4 The percentage of recycled hydrogen to product hydrogen, %. 20 Steam (heat carrier) usage, kg / h 13000 Product hydrogen pressure, MPaA 1.1 Product hydrogen concentration, vol% 99.85 Catalyst regeneration cycle, month 20

[0102] Figure 5 This is the temperature distribution diagram of the R1 tube. Due to the lack of segmented filling, the catalyst loading at the inlet is relatively high. As the material enters the tube, it undergoes a rapid dehydrogenation reaction under the action of the catalyst, causing the temperature inside the tube to drop sharply. It drops to 290℃ at 0.1m and to a minimum of 250℃ at 0.2m, which is extremely detrimental to the stability of the catalyst.

[0103] By comparing with Example 3 and Comparative Example 1, it can be seen that when the technical solution provided by the present invention is adopted, the difference between the inlet temperature and the lowest temperature of the first-stage tubular reactor R1 is reduced from 70°C to 5°C, the catalyst regeneration cycle is increased by 2 times, the steam consumption is reduced by 8%, and the concentration of hydrogen in the product is greater than 99.98 vol%, achieving better technical results.

Claims

1. An organic hydride dehydrogenation reaction system, characterized in that, Including N-stage tubular reactors with tubes connected in series and shells connected in series, where N≥2; The organic hydride dehydrogenation reaction system also includes a second heat exchanger E2 and a third heat exchanger E3; the second heat exchanger E2 is composed of heat exchange pipes II and II' capable of heat exchange; the third heat exchanger E3 is composed of heat exchange pipes III and III' capable of heat exchange. The organic hydride source, heat exchange line II, heat exchange line III, and the tube-side inlet of the first-stage tubular reactor are connected sequentially. The tube side outlet of the Nth stage tubular reactor is connected to heat exchange line II'; The shell-side outlet of the Nth stage tubular reactor is connected to heat exchange line III'. The nth stage tubular reactor has a heater H at the shell-side inlet. n n = any integer from 1 to N; The organic hydride dehydrogenation reaction system also includes a first heat exchanger E1; The first heat exchanger E1 consists of heat exchange pipe I and heat exchange pipe I', which are capable of heat exchange. When n=1, the heat carrier source, heat exchange pipeline I, heater H1, and shell-side inlet of the first-stage tube reactor are connected in sequence. The heat exchange pipeline III' is connected to the heat exchange pipeline I'.

2. The organic hydride dehydrogenation reaction system according to claim 1, characterized in that, The organic hydride dehydrogenation reaction system also includes a cooler and a gas-liquid separator; The tube side outlet of the Nth stage tubular reactor is sequentially connected to heat exchange line II', cooler and gas-liquid separator.

3. The organic hydride dehydrogenation reaction system according to claim 2, characterized in that, The gas phase outlet of the gas-liquid separator is connected to the tube inlet of the first-stage tubular reactor; And / or, the ratio of the catalyst loading of the (n+1)th stage tubular reactor to the catalyst loading of the nth stage tubular reactor is 0.5 to 1.

5.

4. The organic hydride dehydrogenation reaction system according to claim 2, characterized in that, The gas phase outlet of the gas-liquid separator has multiple branches, at least one of which is connected to the tube-side inlet of the first-stage tubular reactor. And / or, the ratio of the catalyst loading of the (n+1)th stage tubular reactor to the catalyst loading of the nth stage tubular reactor is 0.9 to 1.

1.

5. The dehydrogenation reaction system for organic hydrides according to any one of claims 1-4, characterized in that, The organic hydride dehydrogenation reaction system also includes a cooler, a first gas-liquid separator, a compressor, and a second gas-liquid separator; The tube side outlet of the Nth stage tubular reactor is sequentially connected to heat exchange line II', cooler and first gas-liquid separator; The gas phase outlet of the first gas-liquid separator is sequentially connected to the compressor and the second gas-liquid separator; The gas phase outlet of the second gas-liquid separator is connected to the tube inlet of the first-stage tubular reactor.

6. The organic hydride dehydrogenation reaction system according to claim 5, characterized in that, The gas phase outlet of the second gas-liquid separator has multiple branches, at least one of which is connected to the tube-side inlet of the first-stage tubular reactor.

7. A method for dehydrogenating organic hydrides using the organic hydride dehydrogenation reaction system according to any one of claims 1-6, characterized in that, include: Each tube of the N-stage tubular reactor is filled with a catalyst and inert ceramic components. In the first-stage tubular reactor, the tubes are divided into M equal segments along the axial direction, where M is an integer, 5 ≤ M ≤ 20. The volume ratio of the catalyst in section M to the catalyst in section M-1 is R, where 1.05 ≤ R ≤ 1.5; In the tubular reactors of stages 2 to N, the volume ratio of the catalyst to the inert ceramic element is 1 / Y, where 1≤Y≤4; The catalyst loading is the same in each stage of the tubular reactor; The organic hydride is first vaporized in the second heat exchanger E2, then heated to the initial reaction temperature in the third heat exchanger E3, and then enters the tube side of the first-stage tubular reactor R1, which is filled with catalyst and inert ceramic parts, to undergo a dehydrogenation reaction; the nth stage reaction product enters the (n+1)th stage tubular reactor to undergo the nth stage reaction; the Nth stage reaction product flows through the second heat exchanger E2 as the heat source for E2. The heat carrier enters the shell side of the nth stage tubular reactor to provide heat for the dehydrogenation reaction in the nth stage; then it enters the shell side of the (n+1)th stage tubular reactor to provide heat for the dehydrogenation reaction in the (n+1)th stage; the heat carrier exiting the shell side of the Nth stage flows through the third heat exchanger E3 as the heat source for E3.

8. The method for dehydrogenating organic hydrides according to claim 7, characterized in that, The ceramic component is a ceramic ring or ceramic granule; And / or, 9≤M≤12; And / or, 1.05 ≤ R ≤ 1.3; And / or, Y=3; And / or, the particle size of the catalyst is 1.8~2 mm; And / or, the particle size of inert ceramic parts is 2~5 mm; The heat carrier is first preheated by the first heat exchanger E1, and then heated by the first stage heater H1 before entering the shell side of the first stage tubular reactor to provide heat for the dehydrogenation reaction in the tube side. And / or, the temperature of the heat transfer fluid at the inlet of the shell side of the nth stage tubular reactor is 350~500℃; And / or, the temperature of the reactant at the inlet of the tube side 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 side of the nth stage tubular reactor; And / or, the temperature of the reactants at the tube inlet of the first-stage tubular reactor is 280~320℃; And / or, the temperature of the reactants at the tube inlet of the second-stage tubular reactor is 280~340℃; And / or, the temperature of the organic hydride at the tube inlet of the nth stage tubular reactor is 280~380℃; And / or, the temperature of the heat carrier at the inlet of the shell side 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 side.

9. The method for dehydrogenating organic hydrides according to claim 8, characterized in that, 1.2≤R≤1.4。 10. The method for dehydrogenating organic hydrides according to claim 8, characterized in that, After the Nth stage reaction product flows out of E2, it passes through a cooler to form a gas-liquid mixture; the gas-liquid mixture is then separated to obtain a gas phase and a liquid phase.

11. The method for dehydrogenating organic hydrides according to claim 8, characterized in that, The gas-liquid mixture flows through the first gas-liquid separator V1, where gas-liquid separation I yields crude hydrogen and toluene, with a separation temperature of 5-60°C. The crude hydrogen undergoes at least one stage of compression before passing through the second gas-liquid separator V2, where gas-liquid separation II yields high-purity hydrogen and toluene, with a separation temperature of 5-60°C. The high-purity hydrogen is split into two streams, one of which is used as recycled hydrogen and returned to the tube side of the first-stage reactor.

12. The method for dehydrogenating organic hydrides according to claim 11, characterized in that, The gas-liquid mixture flows through the first gas-liquid separator V1, where gas-liquid separation I yields crude hydrogen and toluene, with a separation temperature of 35~45℃. The crude hydrogen is then compressed at least once before passing through the second gas-liquid separator V2, where gas-liquid separation II yields high-purity hydrogen and toluene, with a separation temperature of 35~45℃.

13. The method for dehydrogenating organic hydrides according to claim 8, characterized in that, The compressor outlet pressure is 0.4 MPaA~3 MPaA.

14. The method for dehydrogenating organic hydrides according to claim 13, characterized in that, The compressor outlet pressure is 1.0 MPaA~2.0 MPaA.

15. The method for dehydrogenating organic hydrides according to claim 8, characterized in that, The circulating hydrogen first combines with the organic hydride and then returns to the tube side of the first-stage reactor; the combination point is before the second heat exchanger E2, or before the third heat exchanger E3, or before the first-stage reactor.

16. The method for dehydrogenating organic hydrides according to claim 8, characterized in that, The temperature of the heat transfer fluid at the inlet of the shell side of the nth stage tubular reactor is 400℃.

17. The method for dehydrogenating organic hydrides according to claim 8, characterized in that, The temperature of the reactants at the inlet of the tube side of the (n+1)th stage tubular reactor is 15℃~35℃ higher than the temperature of the reactants at the inlet of the tube side of the nth stage tubular reactor. And / or, the temperature of the reactants at the tube inlet of the first-stage tubular reactor is 300°C; And / or, the temperature of the reactants at the tube inlet of the second-stage tubular reactor is 320°C; And / or, the temperature of the heat carrier at the inlet of the shell side 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 side.

18. The method for dehydrogenating organic hydrides according to claim 17, 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.

19. The method for dehydrogenating organic hydrides according to any one of claims 7-18, 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. And / or, the substituted or unsubstituted cycloalkanes are selected from at least one of C3-C6 alkanes; And / or, the substituted or unsubstituted olefin is selected from at least one of C2-C6 olefins; And / or, the substituted or unsubstituted monocyclic aromatic hydrocarbon is 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; And / or, the heat transfer medium is selected from steam or molten salt.

20. The method for dehydrogenating organic hydrides according to claim 19, characterized in that, The substituted or unsubstituted alkanes are selected from at least one of C1-C6 alkanes; And / or, the substituted or unsubstituted cycloalkane is cyclohexane or methylcyclohexane; And / or, the substituted or unsubstituted olefin is butene; And / or, the molten salt is selected from at least one of potassium nitrate, sodium nitrite, and sodium nitrate.

21. The method for dehydrogenating organic hydrides according to claim 19, characterized in that, The substituted or unsubstituted alkane is propane or butane; 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).

22. The method for dehydrogenating organic hydrides according to claim 21, characterized in that, The molten salt consists of 53% potassium nitrate, 40% sodium nitrite and 7% sodium nitrate.

23. The method for dehydrogenating organic hydrides according to any one of claims 7-18, characterized in that, In the nth stage tubular reactor, the flow direction of organic hydrides in the tube side is parallel to the flow direction of the heat carrier in the shell side. And / or, the cooling medium for the reaction products is air or water.

24. The method for dehydrogenating organic hydrides according to any one of claims 7-18, characterized in that, In the tube side of the nth stage tubular reactor, the conditions for the dehydrogenation reaction include: The reaction temperature is 200℃~500℃; The reaction pressure is 0.02 MPaA to 1.0 MPaA; The total mass hourly space velocity (GHSV) of the organic hydride is 0.5 h⁻¹. -1 ~5 h -1 ; The ratio of the flow rate of the heat carrier at the shell-side inlet of the first-stage tubular reactor to the flow rate of the organic hydride at the tube-side inlet of the first-stage tubular reactor is 2 to 5. The total mass hourly space velocity (GHSV) of the organic hydrides at the inlet of the first-stage tubular reactor is 4–20 h⁻¹. -1 .

25. The method for dehydrogenating organic hydrides according to claim 24, characterized in that, The reaction temperature is 250℃~400℃; The reaction pressure is 0.1 MPaA to 0.4 MPaA; The total mass hourly space velocity of the organic hydride is 2 h⁻¹. -1 ~4 h -1 .

26. The method for dehydrogenating organic hydrides according to any one of claims 7-18, characterized in that, The content of recycled hydrogen in the total gas phase is 5% to 50%.

27. The method for dehydrogenating organic hydrides according to claim 26, characterized in that, The content of recycled hydrogen in the total gas phase is 10% to 20%.

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