A production device for preparing benzene by dehydrogenation of cyclohexane

Abstract

The utility model belongs to the field of chemical synthesis technology, specifically relates to a kind of cyclohexane dehydrogenation production device of benzene.The utility model discloses the production device of benzene of cyclohexane dehydrogenation, including the reaction unit and separation unit of sequential intercommunication;The reaction unit includes the feed evaporation tank (1) of sequential intercommunication, feed superheater (2), dehydrogenation reactor (3);The separation unit includes the heavy tower inlet and outlet heat exchanger (4) of sequential intercommunication, heavy tower (5), gas-liquid separation tank (6).The utility model discloses the production device of benzene of cyclohexane dehydrogenation, effectively solved the cyclohexane dehydrogenation reaction needs to be carried out under the condition of high temperature, low pressure, because excessively high reaction temperature can destroy the structure of catalyst, and make catalyst coking deactivation, and lower reaction temperature can reduce the conversion rate of the contradiction.

Description

Technical Field

[0001] This utility model belongs to the field of chemical synthesis technology, specifically relating to a production apparatus for the dehydrogenation of cyclohexane to produce benzene. Background Technology

[0002] Currently, the principle of cyclohexane dehydrogenation to benzene is to directly convert cyclohexane into benzene and hydrogen under certain reaction temperatures, pressures, and catalysts. Using the cyclohexane dehydrogenation process, cyclohexane, a byproduct of the cyclohexanone unit, can be directly converted into benzene and hydrogen. The benzene and hydrogen can then be recycled back to the cyclohexanone unit as feedstock, effectively utilizing the byproduct cyclohexane and achieving a closed-loop cycle of feedstock and product within the unit. This achieves the goals of being green, environmentally friendly, efficient, energy-saving, and generating no waste, while simultaneously reducing the need for external benzene procurement and the load on the associated hydrogen production unit.

[0003] However, since the dehydrogenation of cyclohexane is a strongly endothermic reaction, it requires high temperature and low pressure conditions. Excessively high reaction temperatures can damage the catalyst structure and cause it to coke and deactivate, while excessively low temperatures will reduce the conversion rate. Therefore, there is a need in the art to develop an apparatus capable of achieving the dehydrogenation of cyclohexane to benzene under relatively low to medium temperature conditions, effectively ensuring the stability of the catalyst and the reaction conversion efficiency, which is of positive significance for the green utilization of cyclohexane. Utility Model Content

[0004] The purpose of this invention is to provide a new type of production apparatus for the dehydrogenation of cyclohexane to benzene at medium temperature and low pressure. The apparatus ensures a high reaction conversion rate while greatly reducing the probability of damaging the catalyst structure.

[0005] To address the aforementioned technical problems, this invention provides a production apparatus for the dehydrogenation of cyclohexane to benzene, comprising a reaction unit and a separation unit connected in sequence; wherein... The reaction unit comprises sequentially connected components: The cyclohexane to be reacted is fed into the feed evaporator for evaporation to form cyclohexane vapor. The cyclohexane vapor is heated to a superheated state via the feed superheater to obtain superheated cyclohexane vapor; A dehydrogenation reactor, in the presence of a dehydrogenation catalyst, through which superheated cyclohexane vapor is dehydrogenated and the dehydrogenation products are collected; The separation unit comprises sequentially connected units: The dehydrogenation product enters the dehydrogenation tower feed heat exchanger for gas-liquid separation, and the gaseous product and liquid product are collected separately. The heavy component is connected to the inlet and outlet heat exchangers of the heavy component removal tower. The liquid product undergoes heavy component removal and separation through the heavy component removal tower. The heavy component is collected at the bottom of the tower and the light component is collected at the top of the tower. The gas-liquid separator is connected to the inlet and outlet heat exchangers of the deweighting tower. The gaseous product is cooled by the cooling components and then separated into gas and liquid fractions in the gas-liquid separator to collect the hydrogen and liquid fractions respectively.

[0006] Specifically, in the cyclohexane dehydrogenation to benzene production apparatus, the reaction unit further includes a first inlet / outlet heat exchanger and / or a second inlet / outlet heat exchanger; wherein, The first inlet and outlet heat exchanger is connected to the feed evaporator, the second inlet and outlet heat exchanger and the deweight removal tower inlet and outlet heat exchanger, respectively. The second feed heat exchanger is connected to the outlet end of the feed evaporator, the first feed heat exchanger, and the dehydrogenation reactor, respectively.

[0007] Specifically, in the cyclohexane dehydrogenation to benzene production apparatus, the reaction unit further includes a reaction electric heater for further heating the superheated cyclohexane steam; The reaction electric heater is connected to the inlet end of the dehydrogenation reactor and the second feed and discharge heat exchanger, respectively.

[0008] Specifically, in the cyclohexane dehydrogenation to benzene production apparatus, the reaction unit further includes a molten salt storage tank and a molten salt feed pump for heating the dehydrogenation reactor; The molten salt storage tank is connected to the molten salt inlet and outlet of the dehydrogenation reactor, respectively, to realize the circulating heating of molten salt.

[0009] Specifically, in the cyclohexane dehydrogenation to benzene production apparatus, the feed evaporator is further equipped with an evaporation heater to heat and evaporate the cyclohexane to be reacted.

[0010] Specifically, the cooling assembly of the separation unit in the cyclohexane dehydrogenation to benzene production apparatus includes the following sequentially connected components: A gas condenser is connected to the inlet and outlet heat exchangers of the deweight removal tower to condense the gaseous products. A primary cryocooler is connected to the outlet of the generated gas condenser to perform the first deep cryocooling of the gaseous products; A secondary cryostat is connected to the outlet of the primary cryostat to perform a second cryostating process on the gaseous product; the gaseous product after cryostating enters the gas-liquid separator.

[0011] Specifically, in the cyclohexane dehydrogenation to benzene production apparatus, the separation unit further includes a first de-weighting tower reflux tank and a de-weighting tower feed pump; The inlet of the first deweight removal tower reflux tank is connected to the outlet of the generated gas condenser, the primary cryostat, the secondary cryostat, and the gas-liquid separator, respectively. The outlet of the first deweight removal tower reflux tank is connected to the deweight removal tower inlet and outlet heat exchanger via the deweight removal tower feed pump.

[0012] Specifically, in the cyclohexane dehydrogenation to benzene production apparatus, the separation unit further includes a heavy weight separation tank and / or a heavy weight removal tower reboiler; The feed inlet of the recombinant fraction tank is connected to the bottom outlet of the decomposition tower, and the unreacted cyclohexane is discharged from the discharge outlet of the recombinant fraction tank via the recombinant fraction extraction pump. The reboiler for the deweight removal tower is connected to the bottom section of the deweight removal tower and is used to heat and reboil the bottom section of the deweight removal tower.

[0013] Specifically, in the cyclohexane dehydrogenation to benzene production apparatus, the separation unit further includes: The heavy removal tower condenser is connected to the top outlet of the heavy removal tower and performs condensation treatment on the light components; The second heavy-duty tower reflux tank is connected to the heavy-duty tower condenser, and the condensed light components enter the second heavy-duty tower reflux tank. The recooler of the de-weighting tower is connected to the reflux tank of the second de-weighting tower. The non-condensable gases in the light components are condensed in the recooler of the de-weighting tower and then discharged. The de-weighting tower reflux pump is connected to the second de-weighting tower reflux tank, and the benzene in the light component is refluxed back to the de-weighting tower or discharged through the de-weighting tower reflux pump.

[0014] Specifically, the cyclohexane dehydrogenation to benzene production apparatus further includes a compression unit and an adsorption unit that are sequentially connected to the gas outlet of the gas-liquid separator of the separation unit, and the separated hydrogen gas is processed sequentially through the compression unit and the adsorption unit. The outlets of the compression unit and the adsorption unit are respectively connected to the reflux tank of the first deweighting tower.

[0015] The cyclohexane dehydrogenation to benzene production apparatus of this invention enables the cyclohexane dehydrogenation to benzene production process under medium temperature and low pressure. It employs a tubular reactor, with a reaction temperature below 340℃ and a reaction pressure of 20-60 kPaG (slightly positive). The significantly lower reaction temperature and pressure facilitate long-term stable operation of the catalyst within the apparatus. This cyclohexane dehydrogenation to benzene production apparatus effectively solves the contradiction that the cyclohexane dehydrogenation reaction needs to be carried out under high temperature and low pressure conditions, as excessively high reaction temperatures can damage the catalyst structure and cause coking and deactivation, while lower reaction temperatures can reduce the conversion rate.

[0016] The cyclohexane dehydrogenation to benzene production apparatus of this invention has significant energy-saving features, a compact structure, a small footprint, and low investment, thereby achieving the goals of improving the economic efficiency of the apparatus and protecting the ecological environment.

[0017] The cyclohexane dehydrogenation to benzene production apparatus of this invention utilizes a lava system for heating, achieving highly stable, uniform, and precise temperature control. By adjusting the thermal coupling process, the reaction heat energy is fully recovered and utilized, and the investment in production equipment and process energy consumption are significantly reduced.

[0018] The cyclohexane dehydrogenation to benzene production apparatus of this invention uses both structured and bulk packing in the separation unit of the de-heavy component tower, which can achieve efficient separation and prevent coking and clogging of heavy components. The de-heavy component treatment process adopts low-pressure operation, which reduces the boiling point, reduces the heat grade requirement, increases the relative fermentation, reduces the reflux ratio, and improves the economic efficiency of the apparatus.

[0019] The cyclohexane dehydrogenation to benzene production apparatus of this invention adds a temperature-switching adsorption hydrogen purification device, which results in extremely low loss of organic matter entrained in the hydrogen and hydrogen purity greater than 99.9%. Attached Figure Description

[0020] To make the content of this utility model easier to understand, the present utility model will be further described in detail below with reference to specific embodiments and accompanying drawings. Figure 1 This is a schematic diagram of the reaction unit in the production device described in this utility model; Figure 2 This is a schematic diagram of the separation unit in the production apparatus of this utility model; Figure 3 This is a schematic diagram of the compression unit and the adsorption unit in the production apparatus. The reference numerals in the diagram are as follows: 1-Feed evaporator, 2-Feed superheater, 3-Dehydrogenation reactor, 4-Heat exchanger for feed to the heavy component removal tower, 5-Heavy component removal tower, 6-Gas-liquid separator, 7-Heavy component tank, 8-Molten salt storage tank, 9-First heavy component removal tower reflux tank, 10-First feed to discharge heat exchanger, 11-Second feed to discharge heat exchanger, 12-Reaction electric heater, 13-Evaporation heater, 14-Molten salt feed pump, 15-Heavy component removal tower feed pump, 16-Heavy component extraction pump, 17-Heavy component removal tower reboiler, 18-Heavy component removal tower reflux pump, 19-Second heavy component removal tower reflux tank, 20-Heavy component removal tower condenser, 21-Heavy component removal tower recooler, 22-Generated gas condenser, 23-Primary cryocooler, 24-Secondary cryocooler. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are also part of this utility model.

[0022] To address the problems of catalyst instability and low reaction efficiency caused by high temperatures in the cyclohexane dehydrogenation to benzene process, the present invention provides a production apparatus for cyclohexane dehydrogenation to benzene, comprising a reaction unit and a separation unit connected in sequence, as described in the following embodiments; wherein... The reaction unit comprises sequentially connected components: The cyclohexane to be reacted enters the feed evaporator 1 for evaporation to form cyclohexane vapor. The cyclohexane vapor is heated to a superheated state via the feed superheater 2 to obtain superheated cyclohexane vapor. In the presence of a dehydrogenation catalyst, the superheated cyclohexane vapor is dehydrogenated via the dehydrogenation reactor 3, and the dehydrogenation products are collected. The separation unit comprises sequentially connected units: The dehydrogenation product enters the dehydrogenation tower inlet and outlet heat exchanger 4 for gas-liquid separation, and the gaseous product and liquid product are collected respectively. The heavy component removal tower 5 is connected to the inlet and outlet heat exchanger 4 of the heavy component removal tower. The liquid product undergoes heavy component removal and separation through the heavy component removal tower 5. The heavy component is collected at the bottom of the tower and the light component is collected at the top of the tower. The gas-liquid separator 6 is connected to the feed heat exchanger 4 of the de-weighting tower. The gaseous product is cooled by the cooling components and then separated into gas and liquid by the gas-liquid separator 6, and the hydrogen and liquid fractions are collected respectively.

[0023] In some specific embodiments, the reaction unit further includes a first inlet / outlet heat exchanger 10 and / or a second inlet / outlet heat exchanger 11; wherein, The first inlet and outlet heat exchanger 10 is connected to the feed evaporator 1, the second inlet and outlet heat exchanger 11 and the deweight removal tower inlet and outlet heat exchanger 4, respectively. The second feed heat exchanger 11 is connected to the outlet end of the feed evaporator 1, the first feed heat exchanger 10, and the dehydrogenation reactor 3, respectively.

[0024] In some specific embodiments, the reaction unit further includes a reaction electric heater 12 for further heating the cyclohexane superheated vapor; The reaction electric heater 12 is connected to the inlet end and the second feed and discharge heat exchanger 11, respectively.

[0025] In some specific embodiments, the reaction unit further includes a molten salt storage tank 8 and a molten salt feed pump 14 for heating the dehydrogenation reactor 3; The molten salt storage tank 8 is connected to the molten salt inlet and outlet of the dehydrogenation reactor 3 respectively, so as to realize the molten salt circulation heating.

[0026] In some specific embodiments, the dehydrogenation reactor 3 adopts a conventional tubular reactor structure, which consists of multiple sets of reactant channels arranged in parallel. The reactants undergo dehydrogenation reactions in the channel, and molten salt channels are formed between the reactant channels. Molten salt used to supply heat to the dehydrogenation reactor 3 flows in the molten salt channels to achieve circulating heat supply.

[0027] In some specific embodiments, the molten salt is selected as a mixed system of 55% sodium nitrate and 45% potassium nitrate.

[0028] In some specific embodiments, the feed evaporator 1 is further provided with an evaporation heater 13 to heat and evaporate the cyclohexane to be reacted.

[0029] In some specific embodiments, the cooling assembly of the separation unit includes sequentially connected components: The generated gas condenser 22 is connected to the feed heat exchanger 4 of the deweight removal tower to condense the gas products. A primary cryocooler 23 is connected to the outlet of the generated gas condenser 22 to perform a first cryocooling on the gaseous product. The secondary cryostat 24 is connected to the outlet of the primary cryostat 23 to perform a second cryostating on the gaseous product; the gaseous product after cryostating enters the gas-liquid separator 6.

[0030] In some specific embodiments, the separation unit further includes a first deweighting tower reflux tank 9 and a deweighting tower feed pump 15; The inlet of the first deweight removal tower reflux tank 9 is connected to the outlet of the generated gas condenser 22, the primary cryocooler 23, the secondary cryocooler 24 and the gas-liquid separator 6, respectively. The discharge port of the first deweight tower reflux tank 9 is connected to the deweight tower inlet and outlet heat exchanger 4 via the deweight tower feed pump 15.

[0031] In some specific embodiments, the separation unit further includes a heavy weight separation tank 7 and / or a heavy weight removal tower reboiler 17; The feed inlet of the heavy component tank 7 is connected to the bottom outlet of the heavy component removal tower 5, and the unreacted cyclohexane is discharged from the discharge outlet of the heavy component tank 7 via the heavy component extraction pump 16. The reboiler 17 of the deweight removal tower is connected to the bottom part of the deweight removal tower 5 and is used to heat and reboil the bottom part of the deweight removal tower 5.

[0032] In some specific embodiments, the separation unit further includes: The heavy component removal tower condenser 20 is connected to the top outlet of the heavy component removal tower 5 and performs condensation treatment on the light component; The second deweight removal tower reflux tank 19 is connected to the deweight removal tower condenser 20, and the condensed light components enter the second deweight removal tower reflux tank 19. The recooler 21 of the de-weighting tower is connected to the reflux tank 19 of the second de-weighting tower. The non-condensable gas in the light component is condensed by the recooler 21 of the de-weighting tower and then discharged. The de-weighting tower reflux pump 18 is connected to the second de-weighting tower reflux tank 19, and the benzene in the light component is refluxed back to the de-weighting tower 5 or discharged via the de-weighting tower reflux pump 18.

[0033] In some specific embodiments, the device further includes a compression unit and an adsorption unit that are sequentially connected to the gas outlet of the gas-liquid separation tank 6 of the separation unit, and the separated hydrogen gas is processed sequentially through the compression unit and the adsorption unit. The outlets of the compression unit and the adsorption unit are respectively connected to the first deweighting tower reflux tank 9.

[0034] In the following embodiments of this invention, the production process of cyclohexane dehydrogenation to benzene is carried out based on the production apparatus.

[0035] Example 1 As attached Figure 1-3 The structure shown in this embodiment, the cyclohexane dehydrogenation to benzene production apparatus, includes a reaction unit, a separation unit, a compression unit, and an adsorption unit connected in sequence; wherein, The reaction unit is used for the dehydrogenation reaction of cyclohexane, that is, in the presence of a selected catalyst, the dehydrogenation reaction is carried out and the dehydrogenation products are collected, the dehydrogenation products include benzene, hydrogen, unreacted cyclohexane, and other gaseous or liquid components. The separation unit is used to effectively separate and collect the various components of the dehydrogenation product. The compression unit is used to compress the hydrogen gas produced by the reaction; The adsorption unit is used to adsorb compressed hydrogen gas.

[0036] As attached Figure 1 The structure shown in this embodiment, the reaction unit of the cyclohexane dehydrogenation to benzene production apparatus, includes a first feed heat exchanger 10, a feed evaporator 1, a feed superheater 2, a second feed heat exchanger 11, a reaction electric heater 12, a dehydrogenation reactor 3, and a catalyst storage tank 8 arranged sequentially; the feed evaporator 1 is also provided with an evaporation heater 13 for heating it.

[0037] As attached Figure 1 In the structure shown, in the reaction unit, the first feed heat exchanger 10 is connected to the cyclohexane feed channel, the feed evaporator 1, the second feed heat exchanger 11, and the dehydrogenation tower feed heat exchanger 4, respectively. The feed inlet and outlet of the feed evaporator 1 are connected to the feed evaporator 1 and the feed superheater 2, respectively, and the feed evaporator 1 itself is equipped with an evaporation heater 13. The feed inlet and outlet of the feed superheater 2 are connected to the feed evaporator 1 and the second feed heat exchanger 11, respectively. The second feed heat exchanger 11 is connected to the outlet of the feed superheater 2, the inlet of the reaction electric heater 12, the outlet of the dehydrogenation reactor 3, and the first feed heat exchanger 10, respectively. The feed inlet and outlet of the reaction electric heater 12 are connected to the second feed heat exchanger 11 and the inlet of the dehydrogenation reactor 3, respectively. The inlet and outlet of the dehydrogenation reactor 3 are connected to the reaction electric heater 12 and the second inlet / outlet heat exchanger 11, respectively. The molten salt storage tank 8 is connected to the molten salt inlet and outlet of the dehydrogenation reactor 3 via a molten salt pump 14.

[0038] The dehydrogenation reactor 3 adopts a tubular reactor structure, which consists of multiple sets of reactant channels arranged in parallel. The reactants undergo dehydrogenation reactions in the channel, and molten salt channels are formed between the reactant channels. Molten salt used to supply heat to the dehydrogenation reactor 3 flows in the molten salt channels to achieve circulating heat supply.

[0039] As attached Figure 1In the structure shown, in the reaction unit, the cyclohexane to be reacted is heat-treated by the first feed heat exchanger 10 and then enters the feed evaporator 1. The evaporation heater 13 heats the cyclohexane to a vapor state by heating the feed evaporator 1. The resulting cyclohexane vapor further enters the feed superheater 2 and is further heated to a superheated state to form cyclohexane superheated vapor. The cyclohexane superheated vapor undergoes heat exchange by the second feed heat exchanger 11 and is further heated by the reaction electric heater 12 before entering the dehydrogenation reactor 3 for dehydrogenation reaction. The catalyst required for the dehydrogenation reaction is controlled by the catalyst pump 14 to enter the dehydrogenation reactor 3 to realize the dehydrogenation reaction of cyclohexane. The dehydrogenation products generated in the dehydrogenation reactor 3 are then sequentially heat-treated by the second feed heat exchanger 11 and the first feed heat exchanger 10 before entering the subsequent separation unit.

[0040] As attached Figure 2 The structure shown in this embodiment, the separation unit of the cyclohexane dehydrogenation to benzene production apparatus, includes, in sequence, a de-heavy tower feed heat exchanger 4, a first de-heavy tower reflux tank 9, a de-heavy tower feed pump 15, a product gas condenser 22, a primary cryocooler 23, a secondary cryocooler 24, a gas-liquid separator 6, a de-heavy tower 5, a de-heavy tower reboiler 17, a heavy component tank 7, a heavy component extraction pump 16, a de-heavy tower condenser 20, a second de-heavy tower reflux tank 19, a de-heavy tower recooler 21, and a de-heavy tower reflux pump 18.

[0041] As attached Figure 2 In the structure shown, in the separation unit, the feed heat exchanger 4 of the heavy-duty removal tower is connected to the first feed heat exchanger 10, the first heavy-duty removal tower reflux tank 9, the heavy-duty removal tower 5, and the product gas condenser 22 of the reaction unit, respectively. The product gas condenser 22, the primary cryostat 23, the secondary cryostat 24, and the gas-liquid separator 6 are connected sequentially, and the product gas condenser 22, the primary cryostat 23, the secondary cryostat 24, and the gas-liquid separator 6 are connected to the first heavy-duty removal tower reflux tank 9, respectively. The gas outlet of the gas-liquid separator 6 is connected to the subsequent compression unit and adsorption unit. The feed inlet of the heavy-duty removal tower 5 is connected to the feed heat exchanger 4 of the heavy-duty removal tower, and the bottom heavy component outlet of the heavy-duty removal tower 5 is connected sequentially to the heavy component tank 7 and the heavy component extraction pump 16. A heavy-duty removal tower reboiler 17 is provided at the bottom of the heavy-duty removal tower 5. The light component outlet at the top of the heavy removal tower 5 is sequentially connected to the heavy removal tower condenser 20, the second heavy removal tower reflux tank 19, and the heavy removal tower recooler 21. The heavy removal tower reflux pump 18 is connected to the second heavy removal tower reflux tank 19 and the feed inlet at the top of the heavy removal tower 5, respectively.

[0042] As attached Figure 2As shown in the structure, in the separation unit, the dehydrogenation products obtained from the reaction unit are heat-treated by the feed heat exchanger 4 of the de-heavy tower, forming gaseous and liquid products respectively. The gaseous products (mainly hydrogen, carrying organic compounds such as benzene and cyclohexane in gaseous form) are sequentially cooled multiple times by the generator gas condenser 22, the primary cryostat 23, and the secondary cryostat 24 before entering the gas-liquid separator 6 for further gas-liquid separation. The hydrogen separated by the gas-liquid separator 6 enters the subsequent compression and adsorption units. The materials separated by compression and cooling in the generator gas condenser 22, the primary cryostat 23, the secondary cryostat 24, and the gas-liquid separator 6, as well as the organic matter adsorbed by temperature change, are returned to the preceding tanks. The condensed organic matter is collected in the first de-heavy tower reflux tank 9 and then re-enters the de-heavy tower feed heat exchanger 4 via the de-heavy tower feed pump 15 for circulation. The liquid product processed by the feed heat exchanger 4 of the heavy removal tower is then fed into the heavy removal tower 5 for component separation. In the heavy removal tower 5, the separated heavy components (mainly byproducts such as biphenyl) are heated and controlled by the reboiler 17 and then enter the heavy component tank 7, where they are recovered or discharged by the heavy component collection pump 16. The light components obtained from the separation of the heavy removal tower 5 (mainly benzene and cyclohexane) are sequentially fed into the heavy removal tower condenser 20 and the second heavy removal tower reflux tank 19 via the top outlet of the tower. After condensation treatment by the heavy removal tower recooler 21, the separated non-condensable gases and other components can be discharged, while the separated product benzene is either reintroduced into the heavy removal tower 5 via the heavy removal tower reflux pump 18 or discharged and collected.

[0043] As attached Figure 3 In the structure shown, in the compression unit and the adsorption unit, the gas outlet of the gas-liquid separator of the separation unit is connected to the compression unit and the adsorption unit in sequence. The compression unit and the adsorption unit are also connected to the first de-weighting tower reflux tank 9 of the separation unit. The gas can enter the de-weighting tower inlet and outlet heat exchanger 4 for energy heat exchange via the de-weighting tower feed pump 15.

[0044] The present invention relates to a production process for the dehydrogenation preparation of cyclohexane as described in Examples 1-3 below, based on the process disclosed in Example 1 above. Figure 1-3 The production unit shown is undergoing a reaction.

[0045] In the following Examples 1-3 of this invention, the production process for the dehydrogenation of cyclohexane uses cyclohexane as a raw material for the dehydrogenation reaction. The catalyst used in the dehydrogenation process is a conventional dehydrogenation catalyst in the art. For example, the active component of the catalyst is a noble metal such as platinum, the acidic component is mainly a halogen (chlorine or fluorine), the support is alumina, and the noble metal constitutes the dehydrogenation active center. Raney nickel or other non-noble metal catalysts can also be used. The amount of catalyst used is simply the working dosage of the catalyst described above, and an appropriate amount of catalyst can be selected according to different production levels.

[0046] In the following Examples 1-3 of this utility model, the catalyst type (Raney nickel catalyst) and dosage are the same for each process route.

[0047] Example 2 In this embodiment, the cyclohexane to be reacted is heat-treated by the first feed heat exchanger 10 and then enters the feed evaporator 1. The feed evaporator 1 is heated to 100°C to heat the cyclohexane to a vapor state. The cyclohexane vapor further enters the feed superheater 2, where the heating temperature is controlled at 180°C to further heat it to a superheated state, forming superheated cyclohexane vapor. The superheated cyclohexane vapor is then heat-treated by the second feed heat exchanger 11 and further heated to 320°C by the reaction electric heater 12 before entering the dehydrogenation reactor 3 for dehydrogenation reaction. In the dehydrogenation reactor 3, the heating temperature is controlled at 340°C and the pressure at 40 kPaG for the dehydrogenation reaction of cyclohexane. The dehydrogenation products generated in the dehydrogenation reactor 3 are then sequentially heat-treated by the second feed heat exchanger 11 and the first feed heat exchanger 10, and then by the de-heavy tower feed heat exchanger 4, forming gaseous and liquid products respectively. The gaseous products (mainly hydrogen, carrying organic compounds such as benzene and cyclohexane in gaseous form) are sequentially cooled multiple times by the generated gas condenser 22 (with a controlled condensation temperature of 40°C), the primary cryostat 23 (with a controlled condensation temperature of 15°C), and the secondary cryostat 24 (with a controlled condensation temperature of 10°C) before entering the gas-liquid separator 6 (with a controlled pressure of 11 kPaG) for further gas-liquid separation.

[0048] The hydrogen separated by the gas-liquid separator 6 enters the subsequent compression and adsorption units. The materials separated by compression and cooling in the generator gas condenser 22, primary cryostat 23, secondary cryostat 24, and gas-liquid separator 6, as well as the organic matter adsorbed by temperature variation, all return to the preceding tanks. The condensed organic matter is collected in the first deweighting tower reflux tank 9 and then recirculated through the deweighting tower feed pump 15 into the deweighting tower inlet / outlet heat exchanger 4. The liquid product collected by the deweighting tower inlet / outlet heat exchanger 4 is then fed into the deweighting tower 5 (with the top pressure controlled at 10 kPaG) for component separation.

[0049] In the heavy component removal tower 5, the separated heavy components (mainly byproducts such as biphenyl) are heated and controlled by the reboiler 17 (bottom temperature, 120°C) and then enter the heavy component tank 7, where they are recovered or discharged by the heavy component collection pump 16. The light components (mainly benzene and cyclohexane) obtained from the separation in the heavy component removal tower 5 enter the heavy component removal tower condenser 20 (top temperature, 85°C) and the second heavy component removal tower reflux tank 19 sequentially through the top outlet. After condensation treatment by the heavy component removal tower recooler 21 (condensation temperature, 15°C), the separated non-condensable gases and other components can be discharged, while the separated product benzene is either reintroduced into the heavy component removal tower 5 via the heavy component removal tower reflux pump 18 or discharged and collected.

[0050] In this embodiment, in the production process of cyclohexane dehydrogenation, the conversion rate of cyclohexane reaches over 90%, and the hydrogen concentration obtained through the adsorption system reaches 99.9%.

[0051] Example 3 In this embodiment, the cyclohexane to be reacted is heat-treated by the first feed heat exchanger 10 and then enters the feed evaporator 1. The feed evaporator 1 is heated to 90°C to reach a vapor state. The cyclohexane vapor further enters the feed superheater 2, where the heating temperature is controlled at 160°C to further heat it to a superheated state, forming superheated cyclohexane vapor. The superheated cyclohexane vapor is then heat-treated by the second feed heat exchanger 11 and further heated to 310°C by the reaction electric heater 12 before entering the dehydrogenation reactor 3 for dehydrogenation reaction. In the dehydrogenation reactor 3, the heating temperature is controlled at 320°C and the pressure at 60 kPaG for the dehydrogenation reaction of cyclohexane. The dehydrogenation products generated in the dehydrogenation reactor 3 are then sequentially heat-treated by the second feed heat exchanger 11 and the first feed heat exchanger 10, and then by the de-heavy tower feed heat exchanger 4, forming gaseous and liquid products respectively. The gaseous products (mainly hydrogen, carrying organic compounds such as benzene and cyclohexane) are sequentially cooled multiple times by the generated gas condenser 22 (with a controlled condensation temperature of 30°C), the primary cryocooler 23 (with a controlled condensation temperature of 10°C), and the secondary cryocooler 24 (with a controlled condensation temperature of 5°C) before entering the gas-liquid separator 6 (with a controlled pressure of 5 kPaG) for further gas-liquid separation.

[0052] The hydrogen separated by the gas-liquid separator 6 enters the subsequent compression and adsorption units. The materials separated by compression and cooling in the generator gas condenser 22, primary cryostat 23, secondary cryostat 24, and gas-liquid separator 6, as well as the organic matter adsorbed by temperature variation, all return to the preceding tanks. The condensed organic matter is collected in the first deweighting tower reflux tank 9 and then recirculated through the deweighting tower feed pump 15 into the deweighting tower inlet / outlet heat exchanger 4. The liquid product collected by the deweighting tower inlet / outlet heat exchanger 4 is then fed into the deweighting tower 5 (with the top pressure controlled at 5 kPaG) for component separation.

[0053] In the heavy component removal tower 5, the separated heavy components (mainly byproducts such as biphenyl) are heated and controlled by the reboiler 17 (bottom temperature, 100°C) and then enter the heavy component tank 7, where they are recovered or discharged by the heavy component collection pump 16. The light components (mainly benzene and cyclohexane) obtained from the separation in the heavy component removal tower 5 enter the heavy component removal tower condenser 20 (top temperature, 80°C) and the second heavy component removal tower reflux tank 19 sequentially through the top outlet. After condensation treatment by the heavy component removal tower recooler 21 (condensation temperature, 10°C), the separated non-condensable gases and other components can be discharged, while the separated product benzene is either reintroduced into the heavy component removal tower 5 via the heavy component removal tower reflux pump 18 or discharged and collected.

[0054] In this embodiment, in the production process of cyclohexane dehydrogenation, the conversion rate of cyclohexane reaches over 90%, and the hydrogen concentration obtained through the adsorption system reaches 99.9%.

[0055] Example 4 In this embodiment, the cyclohexane to be reacted is heat-treated by the first feed heat exchanger 10 and then enters the feed evaporator 1. The feed evaporator 1 is heated to 120°C to heat the cyclohexane to a vapor state. The cyclohexane vapor further enters the feed superheater 2, where the heating temperature is controlled at 190°C to further heat it to a superheated state, forming superheated cyclohexane vapor. The superheated cyclohexane vapor is then heated to 340°C by the reaction electric heater 12 after heat exchange by the second feed heat exchanger 11, and then enters the dehydrogenation reactor 3 for dehydrogenation reaction. In the dehydrogenation reactor 3, the heating temperature is controlled at 360°C and the pressure at 20 kPaG for the dehydrogenation reaction of cyclohexane. The dehydrogenation products generated in the dehydrogenation reactor 3 are then sequentially heat-treated by the second feed heat exchanger 11 and the first feed heat exchanger 10, and then by the de-heavy tower feed heat exchanger 4, forming gaseous and liquid products respectively. The gaseous products (mainly hydrogen, carrying organic compounds such as benzene and cyclohexane in gaseous form) are sequentially cooled multiple times by the generated gas condenser 22 (with a controlled condensation temperature of 50°C), the primary cryocooler 23 (with a controlled condensation temperature of 20°C), and the secondary cryocooler 24 (with a controlled condensation temperature of 15°C) before entering the gas-liquid separator 6 (with a controlled pressure of 15 kPaG) for further gas-liquid separation.

[0056] The hydrogen separated by the gas-liquid separator 6 enters the subsequent compression and adsorption units. The materials separated by compression and cooling in the generator gas condenser 22, primary cryostat 23, secondary cryostat 24, and gas-liquid separator 6, as well as the organic matter adsorbed by temperature variation, all return to the preceding tanks. The condensed organic matter is collected in the first deweighting tower reflux tank 9 and then recirculated through the deweighting tower feed pump 15 into the deweighting tower inlet / outlet heat exchanger 4. The liquid product collected by the deweighting tower inlet / outlet heat exchanger 4 is then fed into the deweighting tower 5 (with the top pressure controlled at 15 kPaG) for component separation.

[0057] In the heavy component removal tower 5, the separated heavy components (mainly byproducts such as biphenyl) are heated and controlled by the reboiler 17 (bottom temperature, 110°C) and then enter the heavy component tank 7, where they are recovered or discharged by the heavy component collection pump 16. The light components (mainly benzene and cyclohexane) obtained from the separation in the heavy component removal tower 5 enter the heavy component removal tower condenser 20 (top temperature, 85°C) and the second heavy component removal tower reflux tank 19 sequentially through the top outlet. After condensation treatment by the heavy component removal tower recooler 21 (condensation temperature 20°C), the separated non-condensable gases and other components can be discharged, while the separated product benzene is either reintroduced into the heavy component removal tower 5 via the heavy component removal tower reflux pump 18 or discharged and collected.

[0058] In this embodiment, in the production process of cyclohexane dehydrogenation, the conversion rate of cyclohexane reaches over 90%, and the hydrogen concentration obtained through the adsorption system reaches 99.9%.

[0059] In summary, the cyclohexane dehydrogenation production apparatus of this invention can realize the cyclohexane dehydrogenation to benzene process under medium temperature and low pressure. The reaction temperature is below 340℃ and the reaction pressure is a slight positive pressure of 20-60 kPaG. The reaction temperature and reaction pressure are significantly lower, which is more conducive to the long-term stable operation of the catalyst in the apparatus.

[0060] The embodiments of this utility model have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this utility model. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this utility model. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this utility model. Therefore, the content of this specification should not be construed as a limitation of this utility model.

Claims

1. A production apparatus for the dehydrogenation of cyclohexane to benzene, characterized in that, It includes sequentially connected reaction units and separation units; wherein, The reaction unit comprises sequentially connected components: The cyclohexane to be reacted enters the feed evaporator (1) for evaporation to form cyclohexane vapor; The cyclohexane vapor is heated to a superheated state by the feed superheater (2) to obtain cyclohexane superheated vapor; In the presence of a dehydrogenation catalyst, the superheated cyclohexane vapor is dehydrogenated via the dehydrogenation reactor (3), and the dehydrogenation products are collected. The separation unit comprises sequentially connected units: The dehydrogenation product enters the dehydrogenation tower feed heat exchanger (4) for gas-liquid separation, and the gaseous product and liquid product are collected respectively. The heavy component removal tower (5) is connected to the inlet and outlet heat exchanger (4) of the heavy component removal tower. The liquid product undergoes heavy component removal and separation through the heavy component removal tower (5). The bottom part of the tower collects the heavy component, and the top part of the tower collects the light component. The gas-liquid separator (6) is connected to the feed heat exchanger (4) of the de-weighting tower. The gaseous product is cooled by the cooling components and then separated into gas and liquid by the gas-liquid separator (6), and the hydrogen and liquid fractions are collected respectively.

2. The cyclohexane dehydrogenation to benzene production apparatus according to claim 1, characterized in that, The reaction unit further includes a first inlet / outlet heat exchanger (10) and / or a second inlet / outlet heat exchanger (11); wherein, The first feed heat exchanger (10) is connected to the feed evaporator (1), the second feed heat exchanger (11) and the feed heat exchanger (4) of the de-weighting tower, respectively; The second feed heat exchanger (11) is connected to the outlet end of the feed evaporator (1), the first feed heat exchanger (10) and the dehydrogenation reactor (3), respectively.

3. The cyclohexane dehydrogenation to benzene production apparatus according to claim 2, characterized in that, The reaction unit also includes a reaction electric heater (12) for further heating the cyclohexane superheated steam. The reaction electric heater (12) is connected to the inlet end of the dehydrogenation reactor (3) and the second feed heat exchanger (11), respectively.

4. The cyclohexane dehydrogenation to benzene production apparatus according to claim 3, characterized in that, The reaction unit also includes a molten salt storage tank (8) and a molten salt feed pump (14) for heating the dehydrogenation reactor (3). The molten salt storage tank (8) is connected to the molten salt inlet and outlet of the dehydrogenation reactor (3) respectively, so as to realize the molten salt circulation heating.

5. The cyclohexane dehydrogenation to benzene production apparatus according to claim 4, characterized in that, The feed evaporator (1) is also equipped with an evaporation heater (13) to heat and evaporate the cyclohexane to be reacted.

6. The apparatus for producing benzene from cyclohexane by dehydrogenation according to any one of claims 1-5, characterized in that, The cooling assembly of the separation unit includes sequentially connected components: A gas condenser (22) is connected to the feed heat exchanger (4) of the deweight removal tower to condense the gas products. A primary cryocooler (23) is connected to the outlet of the generated gas condenser (22) to perform the first cryocooling on the gaseous products; The secondary cryogenic reactor (24) is connected to the outlet of the primary cryogenic reactor (23) to perform a second cryogenic treatment on the gaseous product; the gaseous product after cryogenic treatment enters the gas-liquid separator (6).

7. The apparatus for producing benzene from cyclohexane dehydrogenation according to claim 6, characterized in that, The separation unit also includes a first deweighting tower reflux tank (9) and a deweighting tower feed pump (15). The inlet of the first de-weighting tower reflux tank (9) is connected to the outlet of the generated gas condenser (22), the primary cryocooler (23), the secondary cryocooler (24) and the gas-liquid separator (6); The outlet of the first deweight tower reflux tank (9) is connected to the deweight tower feed heat exchanger (4) via the deweight tower feed pump (15).

8. The apparatus for producing benzene from cyclohexane dehydrogenation according to claim 7, characterized in that, The separation unit also includes a recombination tank (7) and / or a decomposition tower reboiler (17). The feed inlet of the recombinant fraction tank (7) is connected to the bottom outlet of the decomposition tower (5), and the unreacted cyclohexane is discharged from the discharge outlet of the recombinant fraction tank (7) via the recombinant fraction extraction pump (16). The reboiler (17) of the deweight removal tower is connected to the bottom part of the deweight removal tower (5) and is used to heat and reboil the bottom part of the deweight removal tower (5).

9. The apparatus for producing benzene from cyclohexane dehydrogenation according to claim 8, characterized in that, The separation unit further includes: The heavy removal tower condenser (20) is connected to the top outlet of the heavy removal tower (5) to condense the light components; The second de-weighting tower reflux tank (19) is connected to the de-weighting tower condenser (20), and the condensed light components enter the second de-weighting tower reflux tank (19). The recooler (21) of the de-weighting tower is connected to the reflux tank (19) of the second de-weighting tower. The non-condensable gas in the light component is condensed and discharged after being discharged by the recooler (21). The de-weighting tower reflux pump (18) is connected to the second de-weighting tower reflux tank (19), and the benzene in the light component is refluxed back to the de-weighting tower (5) or discharged via the de-weighting tower reflux pump (18).

10. The apparatus for producing benzene from cyclohexane dehydrogenation according to claim 8, characterized in that, The device also includes a compression unit and an adsorption unit that are sequentially connected to the gas outlet of the gas-liquid separator (6) of the separation unit, and the separated hydrogen is processed sequentially through the compression unit and the adsorption unit. The outlets of the compression unit and the adsorption unit are respectively connected to the first deweight tower reflux tank (9).

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