Method and device for producing cyclohexane by using light naphtha

Abstract

The invention relates to the field of oil refining and chemical engineering, and particularly provides a method and a device for producing cyclohexane by using light naphtha, the method comprises the following steps: carrying out crystallization separation on the light naphtha through a process of crystallization separation, hydrogenation reaction and gas-liquid separation to obtain high-purity cyclohexane; the residual light naphtha is subjected to hydrogenation reaction, and the yield of cyclohexane is increased through C6 alkane cyclization, methyl cyclopentane isomerization, saturation of a small amount of benzene and other reactions; and the cyclohexane-rich fraction of the reaction product is subjected to crystallization separation through a stable part to be further recovered, and the cyclohexane is concentrated. According to the method for producing cyclohexane by using light naphtha disclosed by the invention, the purity and recovery rate of obtained cyclohexane are high, the operation energy consumption in the cyclohexane production process is reduced, the occupied area of the device is small, the investment is saved, the operation is flexible, related equipment and pipelines are not easy to block, and long-period stable operation can be realized.

Description

Technical Field

[0001] The invention relates to the field of oil refining and chemical industry, and in particular to a method and a device for producing cyclohexane by utilizing light naphtha. Background Art

[0002] Benzene is an important product of petroleum refining and an important basic raw material for petrochemical industry. Benzene can be divided into petroleum benzene and coking benzene according to its source. At present, there are six main processes for producing benzene in the world: first, naphtha in the refinery is obtained through catalytic reforming process, which is the largest source of benzene; second, benzene is produced as a by-product in the high-temperature cracking process to produce ethylene; third, benzene is produced by the aromatization process of light hydrocarbons, that is, low-carbon hydrocarbons or liquefied petroleum gas are converted into benzene. Fourth, benzene is produced as a by-product when toluene and C9+ heavy aromatics undergo disproportionation and alkyl transfer reactions to produce mixed xylenes; fifth, ethylbenzene in mixed xylenes undergoes dealkylation to produce benzene; sixth, benzene is produced in the coal chemical industry. Among the above six processes, the benzene produced by the first five processes is called "petroleum benzene", and the benzene produced by coal chemical industry is called "coking benzene".

[0003] As an important chemical intermediate, benzene has a wide variety of downstream products, mainly used in the production of chemical products such as ethylbenzene and cyclohexane. In 2021, the global benzene production was about 53.294 million tons, and the benzene used to produce cyclohexane accounted for about 14.1% of the total, that is, about 7.51 million tons / year of benzene was used for the production of cyclohexane after dehydrogenation. In 2021, China's benzene production was 13.823 million tons, and the benzene used to produce cyclohexane accounted for about 27% of the total, that is, about 3.73 million tons / year of benzene was used for the production of cyclohexane after dehydrogenation. In 2021, the average price of domestic benzene was about 6,100 yuan, and the price in 2022 was significantly higher.

[0004] Cyclohexane is an important organic chemical raw material, mainly used to produce cyclohexanol, cyclohexanone, and products such as caprolactam and hexamethylenediamine, which are monomers for making nylon 66 and nylon 6. It can also be used as an excellent solvent. The main industrial production methods of cyclohexane are petroleum fraction separation and benzene hydrogenation saturation. The cyclohexane obtained by the petroleum fraction separation method has low purity and high energy consumption, and does not meet the requirements of downstream deep processing. At present, at least 85% of cyclohexane is obtained from the benzene hydrogenation saturation process, and the product purity is very high, which can meet the requirements of industrial applications. In 2021, the average price of cyclohexane is about 7,400 yuan / ton, which is significantly higher than the price of light naphtha of 4,100 yuan / ton, and is also nearly 1,300 yuan higher than the price of benzene.

[0005] As the largest source of benzene, the catalytic reforming process mainly produces benzene by dehydrogenating cyclohexane in naphtha. At present, most of the cyclohexane sold on the market is obtained by hydrogenation of benzene. Therefore, it is very meaningful to seek a low-cost, low-energy consumption, short-process process to produce cyclohexane. That is, this patent intends to invent a method and system for producing cyclohexane using light naphtha to avoid the phenomenon of "repeated" dehydrogenation and hydrogenation of cyclohexane in light naphtha, in which cyclohexane in light naphtha is first dehydrogenated to produce benzene and then benzene is hydrogenated to produce cyclohexane. At the same time, the production of cyclohexane is increased by cyclization of C6 alkanes in light naphtha, isomerization of methylcyclopentane, saturation of a small amount of benzene, etc. The light naphtha described in this patent mainly refers to straight-run naphtha, diesel hydrocracking naphtha, wax oil hydrocracking naphtha, catalytic cracking aromatic raffinate, ethylene cracking aromatic raffinate, and 50-85°C fractions in coal-based naphtha, mainly C6 alkanes and cycloalkanes. The cyclohexane produced by this patent will have obvious product competitiveness than the cyclohexane produced by benzene dehydrogenation.

[0006] Based on this background, the present invention studies a method and device for producing cyclohexane using light naphtha. Summary of the invention

[0007] The present invention aims at the deficiencies in the prior art and provides a method and device for producing cyclohexane by using light naphtha, so as to solve the problems of long process, large investment, high energy consumption and large land occupation in the prior cyclohexane production technology.

[0008] In order to achieve the above object, the first aspect of the present invention provides a method for producing cyclohexane using light naphtha, wherein the method comprises the following steps:

[0009] Crystallization separation: The light naphtha is sent to the crystallization separation system for cooling and crystallization, and heating and dissolving to obtain cyclohexane-depleted light naphtha and high-purity cyclohexane;

[0010] Hydrogenation reaction: mixing the cyclohexane-poor light naphtha with hydrogen, heating and then performing a hydrogenation reaction to obtain a reaction product;

[0011] Gas-liquid separation: cooling the reaction product and performing product separation to obtain hydrogen-containing gas, C2-C5 light hydrocarbons and rich cyclohexane; the hydrogen-containing gas is pressurized and then recycled as hydrogen; the rich cyclohexane is mixed with the light naphtha and then subjected to the crystallization separation;

[0012] The crystallization separation system includes at least one crystallization separator; when the number of the at least one crystallization separator is more than one, each crystallization separator is connected in parallel, in series, or in a combination of series and parallel.

[0013] The second aspect of the present invention provides a device for producing cyclohexane using light naphtha in the above method, the device comprising a light naphtha feed pipeline, a multi-stage series-connected crystallization separation system, a reaction system and a separation system, as well as a heat exchanger and a compressor;

[0014] The multi-stage series crystallization separation system is provided with a high-purity cyclohexane discharge pipeline;

[0015] The separation system is provided with a hydrogen-containing gas discharge pipeline, a C2-C5 light hydrocarbon production pipeline and a cyclohexane-rich discharge pipeline;

[0016] The discharge pipeline of the multi-stage series-connected crystallization separation system is connected to the refrigerant inlet of the heat exchanger, and the refrigerant outlet of the heat exchanger is connected to the reaction system;

[0017] A hydrogen inlet is provided on the pipeline between the discharge port of the multi-stage series crystallization separation system and the refrigerant inlet of the heat exchanger;

[0018] The hydrogen-containing gas discharge pipeline is connected to the hydrogen inlet via a compressor;

[0019] The cyclohexane-rich discharge pipeline is connected to the light naphtha feed pipeline;

[0020] The reaction system discharge pipeline is connected to the heat medium inlet of the heat exchanger, and the heat medium outlet of the heat exchanger is connected to the separation system;

[0021] The crystallization separation system includes at least one crystallization separator; when the number of the at least one crystallization separator is more than one, each crystallization separator is connected in parallel, in series, or in a combination of series and parallel.

[0022] The effects of the present invention are:

[0023] (1) The method and device for producing cyclohexane from light naphtha proposed in the present invention utilize the difference in crystallization temperature between cyclohexane and other alkanes and cycloalkanes to achieve separation, and adopt a combination of crystallization + dissolution process, which greatly reduces the operating energy consumption of the separation process. The obtained cyclohexane has high purity, flexible process operation, and can achieve long-term stable operation.

[0024] (2) The method and apparatus for producing cyclohexane from light naphtha proposed in the present invention use a crystallizer connected to a refrigeration system to provide cooling capacity, so that cyclohexane is crystallized and precipitated preferentially, thereby obtaining high-purity cyclohexane and achieving efficient separation of cyclohexane from other components in light naphtha.

[0025] (3) The method and apparatus for producing cyclohexane from light naphtha proposed in the present invention comprises a plurality of crystallizers in a crystallization separation system, the crystallization separators are arranged in parallel, one part of the crystallization separators realizes the crystallization of cyclohexane, and the other part realizes the dissolution of cyclohexane.

[0026] (4) The method and apparatus for producing cyclohexane from light naphtha proposed in the present invention are provided with multiple crystallization separation systems in order to obtain cyclohexane with higher purity. The crude cyclohexane separated by the previous crystallization separation system is crystallized and dissolved multiple times by the subsequent multiple crystallization separation systems, thereby ensuring the purity of the cyclohexane. At the same time, in order to improve the energy utilization efficiency, an energy recovery system is provided.

[0027] (5) The method and apparatus for producing cyclohexane from light naphtha proposed in the present invention include a stirrer in the crystallizer, and a cooling medium is introduced to provide cooling, thereby achieving uniform crystallization of cyclohexane, preventing blockage of the crystallizer, and further improving the recovery rate of cyclohexane.

[0028] (6) The method and apparatus for producing cyclohexane from light naphtha proposed in the present invention adopt a gas-solid hydrogenation catalytic method, which greatly increases the proportion of cyclohexane in the reaction product and has a significant effect on increasing the yield of cyclohexane.

[0029] (7) The method and device for producing cyclohexane from light naphtha proposed in the present invention adopt a crystallization separation + reaction method, which has a low hydrogen-to-oil molar ratio, a short process, a small footprint, low operating costs, and high cyclohexane purity.

[0030] (8) The method and apparatus for producing cyclohexane from light naphtha proposed in the present invention adopt a gas-solid hydrogenation catalytic method and a downward reactor; a feed distributor is provided at the inlet of the reactor and an outlet collector is provided at the bottom, thereby improving the reaction efficiency of producing cyclohexane.

[0031] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0033] Figure 1 The present invention provides a schematic flow chart of a method for producing cyclohexane by utilizing light naphtha.

[0034] Figure 2 It is a schematic flow chart of another method for producing cyclohexane by utilizing light naphtha proposed by the present invention.

[0035] Figure 3 It is a schematic diagram of a crystallization separation process of a specific implementation method of the method for producing cyclohexane by utilizing light naphtha proposed by the present invention.

[0036] Figure 4It is a schematic diagram of the crystallization separation process of another specific implementation method of the present invention for producing cyclohexane using light naphtha.

[0037] Description of reference numerals:

[0038] 1—light naphtha, 2—cyclohexane-poor light naphtha, 3—cyclohexane, 4—hydrogen, 5—hydrogen-mixed light naphtha, 6—preheated light naphtha, 7—reaction feed, 8—reaction product, 9—cooling product 1, 10—cooling product 2, 11—cooling product 3, 12—gas phase product, 13—liquid phase product, 14—stabilization tower feed, 15—stabilization tower top gas product, 16—stabilization tower top liquid product, 17—stabilization tower bottom product, 18—cyclohexane-rich, 20—cooling refrigerant, 21—refrigerant after heat exchange, 22—heating heating agent, 23—heating agent after heat exchange, 26—precooling light naphtha, 27—preheating cyclohexane-poor light naphtha;

[0039] JJ—crystallization separation, FY—hydrogenation reaction, FL—gas-liquid separation;

[0040] 101—refrigeration system, 102—1# crystallization separation system, 103—heating system, 104—2# crystallization separation system;

[0041] 201 - crystallizer separator, 202 - cold exchange component, 203 - stirrer, 204 - feed heat exchanger;

[0042] 301 - reactor, 302 - heat exchanger, 303 - 1# heater, 304 - air cooler, 305 - 1# cooler, 306 - 1# gas-liquid separation tank, 307 - stabilization tower, 308 - 2# cooler, 309 - 3# cooler, 310 - 2# heater, 311 - 2# gas-liquid separation tank, 312 - compressor;

[0043] 401—feed distributor, 402—catalyst bed, 403—outlet collector. DETAILED DESCRIPTION

[0044] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0045] In the present disclosure, unless otherwise stated, directional words such as "upper" and "lower" generally refer to upper and lower in normal use. Figure 1In the drawing direction, "inside" and "outside" refer to the outline of the device. In addition, the terms "first, second, third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first, second, third" may explicitly or implicitly include one or more of the features. In the description of the present disclosure, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0046] The present invention provides a method for producing cyclohexane by utilizing light naphtha. Figure 1 , Figure 2 As shown, the method comprises the following steps:

[0047] Crystallization separation: the light naphtha 1 is sent to the crystallization separation system 102 for cooling crystallization and heating dissolution to obtain cyclohexane-poor light naphtha 2 and high-purity cyclohexane 3;

[0048] Hydrogenation reaction: mixing cyclohexane-poor light naphtha 2 with hydrogen 4, heating and then performing hydrogenation reaction to obtain reaction product 8;

[0049] Gas-liquid separation: the reaction product 8 is cooled and then separated into hydrogen-containing gas, C2-C5 light hydrocarbons and cyclohexane-rich 18. The hydrogen-containing gas is pressurized and then recycled as hydrogen 4. The cyclohexane-rich 18 is mixed with light naphtha 1 and then crystallized and separated together.

[0050] The crystallization separation system 102 includes at least one crystallization separator 201. When the number of the at least one crystallization separator 201 is more than one, each crystallization separator 201 is connected in parallel, in series, or in a combination of series and parallel.

[0051] In the present invention, the difference in crystallization temperature between cyclohexane and other alkanes and cycloalkanes is utilized to achieve separation, and a crystallization + dissolution process is combined, which greatly reduces the operating energy consumption of the separation process. The obtained cyclohexane has high purity, flexible process operation, and can achieve long-term stable operation.

[0052] According to the present invention, at least one crystallization separator 201 is at least two in parallel;

[0053] Each crystallizer 201 is provided with a cold exchange component 202, a stirrer 203 and an optional electric heater;

[0054] The cold exchange component 202 is used to cool the cyclohexane in the crystallizer 201, or to heat and melt the crystallized cyclohexane in the crystallizer 201;

[0055] The optional electric heater is used to heat and melt the crystallized cyclohexane in the crystallizer 201;

[0056] The stirrer 203 is used to stir the cyclohexane in the cooling crystallization process in the crystallizer separator 201 to achieve uniform crystallization of the cyclohexane;

[0057] Light naphtha is fed into at least two parallel crystallization separators 201 in a stream to be cooled, crystallized, and heated to be dissolved independently;

[0058] The cyclohexane obtained by heating and dissolving in the crystallization separation system 102 is extracted as high-purity cyclohexane 3;

[0059] The cold exchange component 202 is preferably a U-shaped tube.

[0060] Preferably, the cyclohexane-depleted light naphtha 2 obtained by cooling and crystallizing the light naphtha 1 in the crystallization separation system 102 is heat exchanged with the light naphtha 1 to obtain preheated cyclohexane-depleted light naphtha 27, and the preheated cyclohexane-depleted light naphtha 27 is mixed with hydrogen 4, heated, and then subjected to hydrogenation reaction to obtain a reaction product 8;

[0061] The cold exchange component 202 is provided with an outlet and an inlet, the inlet is used to receive the cooling refrigerant 20 injected by the refrigeration system 101, or to receive the heating heating agent 21 injected by the heating system 103; the outlet is used to output the refrigerant 22 after heat exchange to the refrigeration system 101, or to output the heating agent 23 after heat exchange to the heating system 103.

[0062] According to a preferred embodiment of the present invention, in the hydrogenation reaction step, the cyclohexane-poor light naphtha 3 is mixed with hydrogen 4 to obtain a hydrogenated light naphtha 5, and the hydrogenated light naphtha 5 is successively subjected to heat exchange and heating to obtain a reaction product 8.

[0063] In the gas-liquid separation step, the reaction product 8 is subjected to heat exchange cooling, air cooling and cooling in sequence, and then product separation is performed to obtain hydrogen-containing gas and liquid product 13. The liquid product 13 is heated and sent to a stabilization tower for gas-liquid separation to obtain a stabilization tower top product and a stabilization tower bottom product. The stabilization tower top product is cooled and gas-liquid separated in sequence to obtain gas-phase C2-C5 light hydrocarbons and liquid-phase C2-C5 light hydrocarbons, respectively. The stabilization tower bottom product is subjected to heat exchange cooling with the liquid product 13 to obtain cyclohexane-rich 18;

[0064] The hydrogen-mixed light naphtha 5 is heated by heat exchange with the reaction product 8 to obtain the preheated light naphtha 6.

[0065] In the present invention, the crystallizer is connected to a refrigeration system to provide cooling capacity, so that cyclohexane is crystallized and precipitated preferentially, thereby obtaining high-purity cyclohexane and realizing efficient separation of cyclohexane from other components in light naphtha.

[0066] In the present invention, a plurality of crystallizers are arranged in the crystallization separation system, and the crystallization separators are arranged in parallel, one part of which realizes the crystallization of cyclohexane, and the other part realizes the dissolution of cyclohexane.

[0067] In the present invention, in order to obtain cyclohexane with higher purity, multiple crystallization separation systems are provided, and the crude cyclohexane separated by the previous crystallization separation system is crystallized and dissolved multiple times by the subsequent multiple crystallization separation systems, thereby ensuring the purity of the cyclohexane. At the same time, in order to improve the energy utilization efficiency, an energy recovery system is provided.

[0068] In the present invention, stirring and introducing cooling medium into the crystallizer to provide cooling capacity can achieve uniform crystallization of cyclohexane, prevent blockage of the crystallizer, and further improve the recovery rate of cyclohexane.

[0069] In the present invention, when it is detected that cyclohexane in the crystallizer is crystallized to a certain extent, the uncrystallized crude cyclohexane is discharged from the bottom of the crystallizer. When the crude cyclohexane is completely discharged, the refrigeration system stops providing cold to the crystallization separation system, and switches to the heating system to provide heat to the crystallization separation system, so that the crystallized cyclohexane in the crystallizer is redissolved, thereby achieving complete separation of cyclohexane from other components in light naphtha.

[0070] According to the present invention, the hydrogenation reaction is carried out in at least one reactor 301, each reactor 301 is provided with a feed port at the top, a feed distributor, a catalyst bed, an outlet collector are arranged in sequence from top to bottom inside, and a discharge port is arranged at the bottom;

[0071] The number of at least one reactor 301 is 1-8, preferably 1-4;

[0072] When the number of at least one reactor 301 is more than one, at least one reactor 301 is connected in series, in parallel, or in a combination of series and parallel.

[0073] According to the present invention, the molar ratio of cyclohexane-poor light naphtha 3 to hydrogen 4 is 0.1:99.9 to 90:10;

[0074] The temperature of the hydrogenation reaction is 100-400°C, the pressure is 0.1-1.0MPaG, and the weight space velocity is 0.1-10h -1 ;

[0075] The cooling crystallization temperature is -20~6.5℃, and the heating dissolution temperature is 40~100℃;

[0076] Light naphtha 1 is a fraction at 50-85° C. of at least one of straight-run naphtha, diesel hydrocracked naphtha, wax oil hydrocracked naphtha, catalytic cracking aromatic raffinate, ethylene cracking aromatic raffinate, and coal-based naphtha, wherein the main components of the fraction are C6 alkanes and / or cycloalkanes;

[0077] The cooling refrigerant 20 is selected from at least one of chilled water, cryogenic materials, propane and propylene;

[0078] The heat exchange heating agent 22 is selected from at least one of hot water, fuel gas, steam, and a heat-conducting medium, and is preferably at least one of hot water and a heat-conducting medium.

[0079] In the present invention, the gas-solid hydrogenation catalytic method is adopted, which greatly increases the proportion of cyclohexane in the reaction product and has a significant effect on increasing the yield of cyclohexane.

[0080] In the present invention, a method of crystallization separation+reaction+gas-liquid separation is adopted, which has a low hydrogen-oil molar ratio, a short process, a small device footprint, a low operating cost and a high cyclohexane purity.

[0081] In the present invention, a gas-solid hydrogenation catalytic method and a descending reactor are adopted; a feed distributor is arranged at the inlet of the reactor and an outlet collector is arranged at the bottom, thereby improving the reaction efficiency of generating cyclohexane.

[0082] In the present invention, according to the different crystallization temperatures of light naphtha, the higher the crystallization temperature, the easier it is to crystallize. As can be seen from the table below, the crystallization temperature of cyclohexane is at least 30°C higher than that of several other components with similar boiling points. The difference in crystallization temperature between cyclohexane and other alkanes and cycloalkanes with similar boiling points can be used to separate cyclohexane. At a certain temperature, such as 6°C, cyclohexane crystallizes in a solid form, while other alkanes and cycloalkanes still remain in liquid form, so that the separation of cyclohexane can be easily achieved.

[0083] name Boiling point℃ Crystallization point, ℃ Cyclopentane 49.3 -93.8 22-Dimethylbutane 49.7 -99.8 23-Dimethylbutane 58.0 -128.5 2-Methylpentane 60.3 -153.7 n-Hexane 68.7 -95.3 Methylcyclopentane 71.8 -142.5 2,2-Dimethylpentane 79.2 -123.8 benzene 80.1 5.45 2,4-Dimethylpentane 80.5 -119.2 Cyclohexane 80.7 6.5 2,2,3-Trimethylbutane 80.9 -24.9 3,3-Dimethylpentane 86.1 -134.5 Dimethylcyclopentane 87.8 -69.8

[0084] In the present invention, it should be noted that although the crystallization points of benzene and cyclohexane are very close, the content of benzene in the light naphtha fraction is very small, and cyclohexane and benzene can be separated by a mature solvent extraction process. Therefore, the present invention only considers the separation of cyclohexane from other alkanes and cycloalkanes in light naphtha.

[0085] In the present invention, the light naphtha referred to mainly refers to straight-run naphtha, diesel hydrocracking naphtha, wax oil hydrocracking naphtha, catalytic cracking aromatic raffinate, ethylene cracking aromatic raffinate, and the 50-85°C fraction in coal-based naphtha, mainly C6 alkanes and cycloalkanes.

[0086] The present invention also provides a device for producing cyclohexane using light naphtha in the above method, such as Figure 2 As shown, the device includes a light naphtha feed pipeline, a crystallization separation system 102, a reaction system and a separation system, as well as a heat exchanger 302 and a compressor 312 connected in sequence;

[0087] The crystallization separation system 102 is provided with a high-purity cyclohexane discharge pipeline;

[0088] The separation system is provided with a hydrogen-containing gas discharge pipeline, a C2-C5 light hydrocarbon production pipeline and a cyclohexane-rich discharge pipeline;

[0089] The discharge pipeline of the crystallization separation system 102 is connected to the refrigerant inlet of the heat exchanger 302, and the refrigerant outlet of the heat exchanger 302 is connected to the reaction system;

[0090] A hydrogen inlet is provided on the pipeline between the discharge port of the crystallization separation system 102 and the refrigerant inlet of the heat exchanger 302;

[0091] The hydrogen-containing gas discharge pipeline is connected to the hydrogen inlet via the compressor 312;

[0092] The cyclohexane-rich discharge pipeline is connected to the light naphtha feed pipeline;

[0093] The discharge pipeline of the reaction system is connected to the heat medium inlet of the heat exchanger 302, and the heat medium outlet of the heat exchanger 302 is connected to the separation system;

[0094] The crystallization separation system 102 includes at least one crystallization separator 201. When the number of the at least one crystallization separator 201 is more than one, each crystallization separator 201 is connected in parallel, in series, or in a combination of series and parallel.

[0095] Preferably, at least one crystallization separator 201 is at least two in parallel;

[0096] Each crystallizer 201 is provided with a cold exchange component 202, a stirrer 203 and an optional electric heater;

[0097] The cold exchange component 202 is used to cool the cyclohexane in the crystallizer 201, or to heat and melt the crystallized cyclohexane in the crystallizer 201;

[0098] The optional electric heater is used to heat and melt the crystallized cyclohexane in the crystallizer 201;

[0099] The stirrer 203 is used to stir the cyclohexane in the cooling crystallization process in the crystallizer separator 201 to achieve uniform crystallization of the cyclohexane;

[0100] The cyclohexane-poor light naphtha outlets of each crystallizer separator 201 are commonly connected to the refrigerant inlet of the heat exchanger (302);

[0101] Light naphtha 1 is connected to the light naphtha feed port of each crystallizer separator 201;

[0102] The cyclohexane outlets of each crystallization separator 201 are connected to a high-purity cyclohexane outlet pipeline;

[0103] The cold exchange component 202 is preferably a U-shaped tube.

[0104] In the present invention, in order to prevent cyclohexane from crystallizing too quickly locally, which may easily wrap non-cyclohexane hydrocarbons in the crystals and reduce the cyclohexane separation efficiency, an agitator 203 is provided in the crystallizer to achieve uniform crystallization in the crystallizer.

[0105] Preferably, the device further comprises a refrigeration system 101 and a heating system 103;

[0106] Light naphtha 1 is connected to the light naphtha feed ports of each crystallizer separator 201 via a feed heat exchanger 204;

[0107] The cyclohexane-poor light naphtha outlets of each crystallizer separator 201 are commonly connected to the refrigerant inlet of the feed heat exchanger 204, and the refrigerant outlet of the feed heat exchanger 204 is connected to the refrigerant inlet of the heat exchanger 302;

[0108] The cold exchange component 202 is provided with an outlet and an inlet, and the outlet and the inlet are respectively connected to the refrigeration system 101 or respectively connected to the heating system 103.

[0109] According to the present invention, the reaction system includes at least one reactor 301 and a 1# heater 303; the separation system includes an air cooler 304, a 1# cooler 305, a 1# gas-liquid separation tank 306, a stabilization tower 307, a 2# cooler 308, a 3# cooler 309, a 2# heater 310 and a 2# gas-liquid separation tank 311;

[0110] The refrigerant outlet of the heat exchanger 302 is connected to the feed port of at least one reactor 301 via the 1# heater 303, and the discharge pipeline of at least one reactor 301 is connected to the heat medium inlet of the heat exchanger 302. The heat medium outlet of the heat exchanger 302 is connected to the 1# gas-liquid separation tank 306 via the air cooler 304 and the 1# cooler 305 in sequence;

[0111] The gas phase outlet at the top of the 1# gas-liquid separation tank 306 is connected to the hydrogen inlet via the compressor 312, and the liquid phase outlet at the bottom of the tank is connected to the stabilization tower 307 via the 2# cooler 308;

[0112] The gas phase outlet at the top of the stabilization tower 307 is connected to the reflux inlet at the top of the stabilization tower 307 via the 3# cooler 309 and the 2# gas-liquid separation tank 311 in sequence, and the liquid phase outlet at the bottom of the stabilization tower 307 is connected to the heat medium inlet of the 2# cooler 308 and the refrigerant inlet of the 2# heater 310 respectively, the heat medium outlet of the 2# cooler 308 is connected to the light naphtha feed pipeline, and the refrigerant outlet of the 2# heater 310 is connected to the reflux inlet at the bottom of the stabilization tower 307;

[0113] The 2# gas-liquid separation tank 311 is provided with a gas-phase C2-C5 light hydrocarbon production pipeline, and a branch of the pipeline between the 2# gas-liquid separation tank 311 and the top reflux inlet of the stabilization tower 307 is separated as a liquid-phase C2-C5 light hydrocarbon production pipeline;

[0114] Each reactor 301 is provided with a feed inlet at the top, a feed distributor, a catalyst bed, an outlet collector are arranged in sequence from top to bottom inside, and a discharge port is arranged at the bottom;

[0115] The number of at least one reactor 301 is 1-8, preferably 1-4;

[0116] When the number of at least one reactor 301 is greater than one, at least one reactor 301 is connected in series, in parallel, or in a combination of series and parallel.

[0117] In the present invention, in order to be used for different processing scales, combined with the current equipment processing level and the actual situation of the engineering construction project, the most preferred number of reactors 301 is 1-2. When the number of selected reactors is not less than 2, a parallel arrangement is preferably adopted, and the most preferred method is a symmetrical parallel arrangement.

[0118] In the present invention, the reactor 101 is of a downward type, the feed port of the reactor is arranged at the upper part of the reactor, and the reaction raw materials flow out from the bottom outlet of the reactor after passing through the feed distributor, the catalyst bed, and the outlet collector in sequence from the reactor inlet.

[0119] In the present invention, a catalyst bed 202 is provided in the reactor 101, and the reaction disclosed in the present invention is a gas-solid catalytic reaction. The reaction resistance comes from three aspects: the mass transfer diffusion of the reaction raw materials into the active center of the catalyst, the diffusion process of the reaction products from the catalyst surface into the main body of the reaction product flow, and the reaction process. The intrinsic activity of the reaction process is determined by the catalyst itself, and to increase the catalytic reaction rate, it is necessary to increase the rate of the rate-controlling step. After the gas-liquid distribution effect, the hydrogen is evenly distributed in the main body of the light naphtha flow, which can effectively increase the mass transfer coefficient and thus accelerate the reaction rate.

[0120] In the present invention, in order to reduce equipment investment and increase the space utilization efficiency in the crystallizer, the present invention preferably adopts that the refrigeration system 101 and the heating system 103 can be connected to the cold exchange component 202 inside the crystallization separation system, and the refrigeration system 101 and the heating system share a set of heat exchange components.

[0121] In the present invention, a downward reactor is adopted, a feed distributor is arranged at the inlet of the reactor, and an outlet collector is arranged at the bottom, so that the reaction efficiency of generating cyclohexane is improved.

[0122] In the present invention, according to different raw material compositions and heat exchange processes, the light naphtha and hydrogen mixture 5 can be sent to the 1# heater for heating after heat exchange with the outlet product of the reactor 301 in the heat exchanger; the outlet product of the reactor 301 can also be sent to the gas-liquid separation tank for separation after heat exchange with the reaction feed, and the separated gas product is sent to the downstream for treatment, and the separated liquid product is sent to the downstream for treatment; the outlet product of the reactor 301 can also be sent to the gas-liquid separation tank after heat exchange with the reaction feed and further cooled, and the gas product and the liquid product are separated and then sent to the downstream for treatment; the outlet product of the reactor 301 can also be sent to the gas-liquid separation tank after heat exchange with the reaction feed and further cooled, and after the gas product and the liquid product are separated, the gas product is sent to the compressor for pressurization and recycling, and the liquid product is sent to the stabilization tower, and the gas product and the C2-C5-rich component are separated from the top of the tower, and the cyclohexane-rich fraction is separated from the bottom of the tower.

[0123] The present invention will be described in more detail below by way of examples.

[0124] Example 1

[0125] like Figure 2 , Figure 3 As shown, this embodiment provides a device for producing cyclohexane using light naphtha, and the device includes a light naphtha feed pipeline, a crystallization separation system 102, a reaction system and a separation system, as well as a heat exchanger 302 and a compressor 312 connected in sequence;

[0126] The crystallization separation system 102 is provided with a high-purity cyclohexane discharge pipeline;

[0127] The separation system is provided with a hydrogen-containing gas discharge pipeline, a C2-C5 light hydrocarbon production pipeline and a cyclohexane-rich discharge pipeline;

[0128] The discharge pipeline of the crystallization separation system 102 is connected to the refrigerant inlet of the heat exchanger 302, and the refrigerant outlet of the heat exchanger 302 is connected to the reaction system;

[0129] A hydrogen inlet is provided on the pipeline between the discharge port of the crystallization separation system 102 and the refrigerant inlet of the heat exchanger 302;

[0130] The hydrogen-containing gas discharge pipeline is connected to the hydrogen inlet via the compressor 312;

[0131] The cyclohexane-rich discharge pipeline is connected to the light naphtha feed pipeline;

[0132] The discharge pipeline of the reaction system is connected to the heat medium inlet of the heat exchanger 302, and the heat medium outlet of the heat exchanger 302 is connected to the separation system;

[0133] The crystallization separation system 102 includes two parallel crystallization separators 201, each of which is provided with a cold exchange component 202 and a stirrer 203;

[0134] The cold exchange component 202 is used to cool the cyclohexane in the crystallizer 201, or to heat and melt the crystallized cyclohexane in the crystallizer 201;

[0135] The stirrer 203 is used to stir the cyclohexane in the cooling crystallization process in the crystallizer separator 201 to achieve uniform crystallization of the cyclohexane;

[0136] The cyclohexane-poor light naphtha outlets of each crystallizer separator 201 are commonly connected to the refrigerant inlet of the heat exchanger (302);

[0137] Light naphtha 1 is connected to the light naphtha feed port of each crystallizer separator 201;

[0138] The cyclohexane outlets of each crystallization separator 201 are connected to a high-purity cyclohexane outlet pipeline;

[0139] The cold exchange component 202 is a U-shaped tube;

[0140] The device also includes a refrigeration system 101 and a heating system 103;

[0141] The cold exchange component 202 is provided with an outlet and an inlet, and the outlet and the inlet are respectively connected to the refrigeration system 101, or respectively connected to the heating system 103;

[0142] The reaction system includes a reactor 301 and a 1# heater 303; the separation system includes an air cooler 304, a 1# cooler 305, a 1# gas-liquid separation tank 306, a stabilization tower 307, a 2# cooler 308, a 3# cooler 309, a 2# heater 310 and a 2# gas-liquid separation tank 311;

[0143] The refrigerant outlet of the heat exchanger 302 is connected to the feed port of the reactor 301 through the 1# heater 303, the discharge pipeline of the reactor 301 is connected to the heat medium inlet of the heat exchanger 302, and the heat medium outlet of the heat exchanger 302 is connected to the 1# gas-liquid separation tank 306 through the air cooler 304 and the 1# cooler 305 in sequence;

[0144] The gas phase outlet at the top of the 1# gas-liquid separation tank 306 is connected to the hydrogen inlet via the compressor 312, and the liquid phase outlet at the bottom of the tank is connected to the stabilization tower 307 via the 2# cooler 308;

[0145] The gas phase outlet at the top of the stabilization tower 307 is connected to the reflux inlet at the top of the stabilization tower 307 via the 3# cooler 309 and the 2# gas-liquid separation tank 311 in sequence, and the liquid phase outlet at the bottom of the stabilization tower 307 is connected to the heat medium inlet of the 2# cooler 308 and the refrigerant inlet of the 2# heater 310 respectively, the heat medium outlet of the 2# cooler 308 is connected to the light naphtha feed pipeline, and the refrigerant outlet of the 2# heater 310 is connected to the reflux inlet at the bottom of the stabilization tower 307;

[0146] The 2# gas-liquid separation tank 311 is provided with a gas-phase C2-C5 light hydrocarbon production pipeline, and a branch of the pipeline between the 2# gas-liquid separation tank 311 and the top reflux inlet of the stabilization tower 307 is separated as a liquid-phase C2-C5 light hydrocarbon production pipeline;

[0147] The reactor 301 is provided with a feed inlet at the top, a feed distributor, a catalyst bed, and an outlet collector are arranged in sequence from top to bottom inside, and a discharge port is provided at the bottom.

[0148] The process flow of producing cyclohexane from light naphtha in the above-mentioned device is as follows: Figure 1 , Figure 2 and Figure 3 As shown, the following steps are included:

[0149] Crystallization separation: the light naphtha 1 is sent to the crystallization separation system 102 for cooling crystallization and heating dissolution to obtain cyclohexane-poor light naphtha 2 and high-purity cyclohexane 3;

[0150] Hydrogenation reaction: mixing cyclohexane-poor light naphtha 2 with hydrogen 4, heating and then performing hydrogenation reaction to obtain reaction product 8;

[0151] Gas-liquid separation: the reaction product 8 is cooled and then separated into hydrogen-containing gas, C2-C5 light hydrocarbons and cyclohexane-rich 18. The hydrogen-containing gas is pressurized and then recycled as hydrogen 4. The cyclohexane-rich 18 is mixed with light naphtha 1 and then crystallized and separated together.

[0152] Light naphtha is fed into at least two parallel crystallization separators 201 in a stream to be cooled, crystallized, and heated to be dissolved independently;

[0153] The cyclohexane obtained by heating and dissolving in the crystallization separation system 102 is extracted as high-purity cyclohexane 3;

[0154] The inlet of the cold exchange component 202 is used to receive the cooling refrigerant 20 injected from the refrigeration system 101, or to receive the heating agent 21 injected from the heating system 103; the outlet is used to output the refrigerant 22 after heat exchange to the refrigeration system 101, or to output the heating agent 23 after heat exchange to the heating system 103;

[0155] In the hydrogenation reaction step, the cyclohexane-poor light naphtha 3 is mixed with hydrogen 4 to obtain hydrogenated light naphtha 5, and the hydrogenated light naphtha 5 is successively subjected to heat exchange and heating to obtain a reaction product 8.

[0156] In the gas-liquid separation step, the reaction product 8 is subjected to heat exchange cooling, air cooling and cooling in sequence, and then product separation is performed to obtain hydrogen-containing gas and liquid product 13. The liquid product 13 is heated and sent to a stabilization tower for gas-liquid separation to obtain a stabilization tower top product and a stabilization tower bottom product. The stabilization tower top product is cooled and gas-liquid separated in sequence to obtain gas-phase C2-C5 light hydrocarbons and liquid-phase C2-C5 light hydrocarbons, respectively. The stabilization tower bottom product is subjected to heat exchange cooling with the liquid product 13 to obtain cyclohexane-rich 18;

[0157] The hydrogen-mixed light naphtha 5 is heated by heat exchange with the reaction product 8 to obtain preheated light naphtha 6;

[0158] The hydrogenation reaction is carried out in the reactor 301;

[0159] The molar ratio of cyclohexane-poor light naphtha 3 to hydrogen 4 is 1;

[0160] The temperature of the hydrogenation reaction is 300°C, the pressure is 0.35MPaG, and the weight space velocity is 2;

[0161] The cooling crystallization temperature is 6.5°C, and the heating dissolution temperature is 60°C;

[0162] Light naphtha 1 is a fraction at 50-85° C. of at least one of straight-run naphtha, diesel hydrocracked naphtha, wax oil hydrocracked naphtha, catalytic cracking aromatic raffinate, ethylene cracking aromatic raffinate, and coal-based naphtha, wherein the main components of the fraction are C6 alkanes and / or cycloalkanes;

[0163] The cooling refrigerant 20 is chilled water;

[0164] The heat exchange heating medium 22 is 100°C;

[0165] Table 1 shows the composition of light naphtha of a certain enterprise. The method of producing cyclohexane by utilizing light naphtha in this embodiment is compared with the existing method of producing cyclohexane by hydrogenation and saturation of benzene. As shown in Table 2, the purity of cyclohexane obtained by the method of producing cyclohexane by utilizing light naphtha in this embodiment can reach the purity of cyclohexane obtained by the benzene hydrogenation and saturation technology, and the operating conditions are much more relaxed than the technology of producing benzene by dehydrogenation of cyclohexane + producing cyclohexane by hydrogenation and saturation of benzene. In addition, the technology of producing cyclohexane by utilizing light naphtha in this embodiment occupies 30% less space and consumes 20% less energy than the conventional technology of the same scale.

[0166] Table 1 Composition of light naphtha of a certain enterprise

[0167]

[0168]

[0169] Table 2 Performance comparison table

[0170]

[0171] Example 2

[0172] like Figure 2 , Figure 4 As shown, the reaction process conditions of this embodiment are the same as those of embodiment 1, except that the light naphtha 1 is connected to the light naphtha feed ports of each crystallizer separator 201 through the feed heat exchanger 204, the cyclohexane-poor light naphtha discharge ports of each crystallizer separator 201 are commonly connected to the refrigerant inlet of the feed heat exchanger 204, and the refrigerant outlet of the feed heat exchanger 204 is connected to the refrigerant inlet of the heat exchanger 302; the cyclohexane-poor light naphtha 2 obtained by cooling and crystallizing the crystallization separation system at about 6.5°C is fed for heat exchange with the light naphtha 1, and the cold in the cyclohexane-poor light naphtha 2 is recovered, which can further reduce the supply of refrigerant in the refrigeration system. Compared with embodiment 1, the energy consumption in this embodiment is reduced by about 10%, which has a significant energy-saving effect.

[0173] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for producing cyclohexane using light naphtha, characterized in that: The method comprises the following steps: Crystallization separation: The light naphtha (1) is sent to the crystallization separation system (102) for cooling and crystallization, and heating and dissolving to obtain cyclohexane-poor light naphtha (2) and high-purity cyclohexane (3); Hydrogenation reaction: mixing the cyclohexane-poor light naphtha (2) with hydrogen (4), heating and then performing a hydrogenation reaction to obtain a reaction product (8); Gas-liquid separation: the reaction product (8) is cooled and then subjected to gas-liquid separation to obtain hydrogen-containing gas, C2-C5 light hydrocarbons and rich cyclohexane (18); the hydrogen-containing gas is pressurized and recycled as hydrogen (4); the rich cyclohexane (18) is mixed with the light naphtha (1) and then subjected to the crystallization separation; The crystallization separation system (102) comprises at least one crystallization separator (201); when the number of the at least one crystallization separator (201) is more than one, each crystallization separator (201) is connected in parallel, in series, or in a combination of series and parallel.

2. The method according to claim 1, characterized in that The at least one crystallization separator (201) is at least two connected in parallel; Each crystallization separator (201) is provided with a cold exchange component (202), a stirrer (203) and an optional electric heater; The cold exchange component (202) is used to cool the cyclohexane in the crystallization separator (201) where the crystallization is taking place, or to heat and melt the cyclohexane that has been crystallized in the crystallization separator (201); An optional electric heater is used to heat and melt the crystallized cyclohexane in the crystallization separator (201); The stirrer (203) is used to stir the cyclohexane in the cooling crystallization process in the crystallization separator (201) to achieve uniform crystallization of the cyclohexane; The light naphtha (1) is fed into at least two parallel crystallization separators (201) in batches to be cooled, crystallized, and heated to be dissolved independently; The cyclohexane obtained by heating and dissolving in the crystallization separation system (102) is extracted as high-purity cyclohexane (3); The cold exchange component (202) is preferably a U-shaped tube.

3. The method according to claim 2, characterized in that The cyclohexane-depleted light naphtha (2) obtained by cooling and crystallizing the light naphtha (1) in the crystallization separation system (102) is heat exchanged with the light naphtha (1) to obtain preheated cyclohexane-depleted light naphtha (27), and the preheated cyclohexane-depleted light naphtha (27) is mixed with hydrogen (4), heated, and then subjected to hydrogenation reaction to obtain a reaction product (8); The cold exchange component (202) is provided with an outlet and an inlet, the inlet is used to receive the cooling refrigerant (20) injected from the refrigeration system (101), or to receive the heating agent (21) injected from the heating system (103); the outlet is used to output the refrigerant (22) after heat exchange to the refrigeration system (101), or to output the heating agent (23) after heat exchange to the heating system (103).

4. The method according to claim 3, characterized in that In the hydrogenation reaction step, the cyclohexane-poor light naphtha (3) is mixed with hydrogen (4) to obtain hydrogenated light naphtha (5), and the hydrogenated light naphtha (5) is subjected to heat exchange and heating in sequence to undergo hydrogenation to obtain a reaction product (8); In the gas-liquid separation step, the reaction product (8) is subjected to heat exchange cooling, air cooling and cooling in sequence, and then subjected to gas-liquid separation to obtain hydrogen-containing gas and liquid phase product (13). The liquid phase product (13) is subjected to heat exchange heating and then sent to a stabilization tower for product separation to obtain a stabilization tower top product and a stabilization tower bottom product. The stabilization tower top product is subjected to cooling and gas-liquid separation in sequence to obtain gas-phase C2-C5 light hydrocarbons and liquid-phase C2-C5 light hydrocarbons, respectively. The stabilization tower bottom product is subjected to heat exchange cooling with the liquid phase product (13) to obtain the cyclohexane-rich (18); The hydrogen-mixed light naphtha (5) and the reaction product (8) are subjected to heat exchange to increase the temperature so as to obtain preheated light naphtha (6).

5. The method according to claim 4, characterized in that The hydrogenation reaction is carried out in at least one reactor (301), each reactor (301) is provided with a feed inlet at the top, a feed distributor, a catalyst bed, an outlet collector are arranged in sequence from top to bottom inside, and a discharge port is arranged at the bottom; The number of the at least one reactor (301) is 1-8, preferably 1-4; When the number of the at least one reactor (301) is more than one, the at least one reactor (301) is connected in series, in parallel, or in a combination of series and parallel.

6. The method according to claim 5, characterized in that The molar ratio of the cyclohexane-poor light naphtha (3) to the hydrogen (4) is 0.1:99.9 to 90:10; The temperature of the hydrogenation reaction is 100-400°C, the pressure is 0.1-1.0MPaG, and the weight space velocity is 0.1-10h -1 ; The cooling crystallization temperature is -20 to 6.5°C, and the heating dissolution temperature is 40 to 100°C; The light naphtha (1) is a fraction at a temperature of 50 to 85° C. of at least one of straight-run naphtha, diesel hydrocracked naphtha, wax oil hydrocracked naphtha, catalytic cracking aromatic raffinate, ethylene cracking aromatic raffinate, and coal-based naphtha, wherein the main components of the fraction are C6 alkanes and / or cycloalkanes; The cooling refrigerant (20) is selected from at least one of chilled water, cryogenic materials, propane and propylene; The heat exchange heating agent (22) is selected from at least one of hot water, fuel gas, steam, and a heat-conducting medium, and is preferably at least one of hot water and a heat-conducting medium.

7. A device for producing cyclohexane using light naphtha, characterized in that: The system comprises a light naphtha feed pipeline, a crystallization separation system (102), a reaction system and a separation system, as well as a heat exchanger (302) and a compressor (312) connected in sequence; The crystallization separation system (102) is provided with a high-purity cyclohexane discharge pipeline; The separation system is provided with a hydrogen-containing gas discharge pipeline, a C2-C5 light hydrocarbon production pipeline and a cyclohexane-rich discharge pipeline; The discharge pipeline of the crystallization separation system (102) is connected to the refrigerant inlet of the heat exchanger (302), and the refrigerant outlet of the heat exchanger (302) is connected to the reaction system; A hydrogen inlet is provided on the pipeline between the material outlet of the crystallization separation system (102) and the refrigerant inlet of the heat exchanger (302); The hydrogen-containing gas discharge pipeline is connected to the hydrogen inlet via a compressor (312); The cyclohexane-rich discharge pipeline is connected to the light naphtha feed pipeline; The reaction system discharge pipeline is connected to the heat medium inlet of the heat exchanger (302), and the heat medium outlet of the heat exchanger (302) is connected to the separation system; The crystallization separation system (102) comprises at least one crystallization separator (201); when the number of the at least one crystallization separator (201) is more than one, each crystallization separator (201) is connected in parallel, in series, or in a combination of series and parallel.

8. The device according to claim 7, characterized in that The at least one crystallization separator (201) is at least two connected in parallel; Each crystallization separator (201) is provided with a cold exchange component (202), a stirrer (203) and an optional electric heater; The cold exchange component (202) is used to cool the cyclohexane in the crystallization separator (201) where the crystallization is taking place, or to heat and melt the cyclohexane that has been crystallized in the crystallization separator (201); An optional electric heater is used to heat and melt the crystallized cyclohexane in the crystallization separator (201); The stirrer (203) is used to stir the cyclohexane in the cooling crystallization process in the crystallization separator (201) to achieve uniform crystallization of the cyclohexane; The cyclohexane-poor light naphtha outlet of the crystallizer separator (201) is connected to the refrigerant inlet of the heat exchanger (302); The light naphtha (1) is connected to the light naphtha feed port of the crystallizer separator (201); The cyclohexane discharge port of the crystallization separator (201) is connected to a high-purity cyclohexane discharge pipeline; The cold exchange component (202) is preferably a U-shaped tube.

9. The device according to claim 8, characterized in that The device also includes a refrigeration system (101) and a heating system (103); The light naphtha (1) is connected to the light naphtha feed ports of each crystallizer (201) via a feed heat exchanger (204); The cyclohexane-poor light naphtha outlets of each crystallizer separator (201) are commonly connected to the refrigerant inlet of the feed heat exchanger (204), and the refrigerant outlet of the feed heat exchanger (204) is connected to the refrigerant inlet of the heat exchanger (302); The cold exchange component (202) is provided with an outlet and an inlet, and the outlet and the inlet are respectively connected to the refrigeration system (101) or respectively connected to the heating system (103).

10. The device according to claim 9, characterized in that The reaction system comprises at least one reactor (301) and a 1# heater (303); the separation system comprises an air cooler (304), a 1# cooler (305), a 1# gas-liquid separation tank (306), a stabilization tower (307), a 2# cooler (308), a 3# cooler (309), a 2# heater (310) and a 2# gas-liquid separation tank (311); The refrigerant outlet of the heat exchanger (302) is connected to the feed port of the at least one reactor (301) via the 1# heater (303); the discharge pipeline of the at least one reactor (301) is connected to the heat medium inlet of the heat exchanger (302); the heat medium outlet of the heat exchanger (302) is connected to the 1# gas-liquid separation tank (306) via the air cooler (304) and the 1# cooler (305) in sequence; The gas phase outlet at the top of the 1# gas-liquid separation tank (306) is connected to the hydrogen inlet via the compressor (312), and the liquid phase outlet at the bottom of the tank is connected to the stabilization tower (307) via the 2# cooler (308); The gas phase outlet at the top of the stabilization tower (307) is connected to the reflux inlet at the top of the stabilization tower (307) through the 3# cooler (309) and the 2# gas-liquid separation tank (311) in sequence, and the liquid phase outlet at the bottom of the stabilization tower (307) is connected to the heat medium inlet of the 2# cooler (308) and the refrigerant inlet of the 2# heater (310) respectively, the heat medium outlet of the 2# cooler (308) is connected to the light naphtha feed pipeline, and the refrigerant outlet of the 2# heater (310) is connected to the reflux inlet at the bottom of the stabilization tower (307); The 2# gas-liquid separation tank (311) is provided with a gas-phase C2-C5 light hydrocarbon production pipeline, and a branch of the pipeline between the 2# gas-liquid separation tank (311) and the top reflux inlet of the stabilization tower (307) is separated as a liquid-phase C2-C5 light hydrocarbon production pipeline; Each reactor (301) is provided with a feed inlet at the top, a feed distributor, a catalyst bed, and an outlet collector are arranged in sequence from top to bottom inside, and a discharge port is provided at the bottom; The number of the at least one reactor (301) is 1-8, preferably 1-4; When the number of the at least one reactor (301) is greater than one, the at least one reactor (301) is connected in series, in parallel, or in a combination of series and parallel.

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