A reaction heat utilization device and method for the process of preparing 1,2-dichloroethane by ethylene oxychlorination

Abstract

The application provides a reaction heat utilization device and method for preparing 1,2-dichloroethane through ethylene oxychlorination, the device comprises a fluidized bed reactor, which is divided into a dense phase zone and a dilute phase zone; the dilute phase zone is provided with a heat exchange tube bundle; the dense phase zone is provided with a raw material gas secondary adding pipe, a hot extraction flow guide device and a heat removal tube bundle, the hot extraction flow guide device comprises a circular truncated cone shaped reduced port and a flow guide vertical pipe, the raw material gas secondary adding pipe is connected to the flow guide vertical pipe, and the heat removal tube bundle is located at an outlet end of the flow guide vertical pipe. The application preheats the raw material gas by using the reaction gas and the waste heat of the gas phase product, reduces the catalyst entrainment loss, does not need to additionally set a preheating unit, reduces equipment investment and lowers energy consumption by setting the heat exchange tube bundle in the dilute phase zone. The raw material gas is added separately by the raw material gas secondary adding and the hot extraction flow guide, the bottom reaction heat is guided to the heat removal tube bundle, the hot spot at the bottom of the reactor is eliminated, and the 1,2-dichloroethane selectivity and purity are improved.

Description

Technical Field

[0001] This invention belongs to the technical field of fluidized bed reaction equipment, and relates to a device and method for utilizing the heat of reaction in the process of preparing 1,2-dichloroethane by oxychlorination of ethylene. Background Technology

[0002] A fluidized bed reactor is a gas-solid reaction device that allows chemical reactions to occur within a boiling bed of solid materials or catalysts. It is one of the most widely used reaction devices in numerous industrial sectors, such as chemical, petroleum, and metallurgy. Oxychlorination typically refers to the chlorination reaction that uses a mixture of hydrogen chloride and oxygen as the chlorine source in the presence of a catalyst. The raw materials are usually hydrocarbons, producing chloroalkanes. Depending on the type of raw materials, a fluidized bed reactor is commonly used for this reaction.

[0003] Taking the oxychlorination reaction of ethylene as an example, this reaction mainly involves the reaction of ethylene with oxygen and HCl to produce dichloroethane. It is usually carried out in a fluidized bed reactor. Based on the accumulation of catalyst particles and the fluidization of the gas in the reactor, it can be divided into a dilute phase zone and a dense phase zone. The high-temperature reaction gas generated by the reaction contains not only the product dichloroethane and water, but also unreacted HCl gas and entrained fine catalyst powder. Generally, it is cooled by rapid cooling and further condensation. However, this process has the following drawbacks: First, the high-temperature reaction gas is not cooled in the dilute phase zone of the reactor. The gas volume expansion leads to a high flow rate, resulting in a large amount of catalyst entrainment and increased catalyst loss. Second, the high-temperature reaction gas is cooled by rapid cooling and condensation, resulting in a large amount of reaction heat being wasted.

[0004] Meanwhile, based on the structural characteristics of fluidized bed reactors, the feed gas is fed from the bottom of the reactor. The partial pressures of ethylene and oxygen are the highest at the bottom of the reactor, resulting in the highest reaction rate and the greatest heat release. However, considering the convenience of maintenance and the fluidization state, heat exchange tubes are usually not installed at the bottom of the reactor, forming a hot spot area. The reaction temperature is high in the hot spot area, which makes it easy for side reactions to occur, resulting in reduced reaction selectivity, increased feed consumption, and is not conducive to the economic efficiency of the reaction.

[0005] CN 102159526A discloses a method for utilizing the reaction heat generated during the preparation of 1,2-dichloroethane from ethylene in a fluidized bed reactor. The method includes: extracting the reaction heat through a cooling tube bundle located within the fluidized bed inside the reactor; and extracting a portion of the reaction heat by heating boiler feedwater, wherein the heated boiler feedwater is used to heat the endothermic equipment used in the preparation process. This method can only partially utilize the reaction heat in the dense phase region, while the high-temperature gas reaction heat in the dilute phase region cannot be utilized. Furthermore, it requires heat load matching with other towers through corresponding heat exchange pipelines, resulting in unsatisfactory operational stability and process economy.

[0006] CN 101165032A discloses an oxychlorination apparatus and method for a reaction process in which at least one olefin is oxychlorinated to at least one chloroalkane using hydrogen chloride and oxygen or an oxygen-containing gas. The apparatus includes a gas inlet comprising a fluidized bed containing catalyst particles extending into a fluidized bed reactor and at least one reaction gas outlet located above the fluidized bed. It also includes a cooling arrangement for thermal control of the oxychlorination reaction, wherein multiple gas inlets are arranged vertically along the fluidized bed, and the cooling arrangement has cooling loops arranged vertically to each other and extending into the fluidized bed. While this apparatus also involves the control of the heat of reaction in a fluidized bed reactor, it primarily focuses on removing heat from the dense phase region via the cooling loops, without utilizing the heat of the reaction gas in the dilute phase region, and the multiple gas inlets are not structurally modified.

[0007] In summary, for the oxychlorination process of ethylene using a fluidized bed reactor, it is necessary to improve the internal structure of the fluidized bed reactor to enhance the extraction and recovery of reaction heat in different zones, ensure stable reaction, and reduce equipment and raw material costs. Summary of the Invention

[0008] To address the problems existing in the prior art, the present invention aims to provide a device and method for utilizing the reaction heat in the process of oxychlorination of ethylene to prepare 1,2-dichloroethane. The device preheats the feed gas by setting up a heat exchange tube bundle in the dilute phase zone of a fluidized bed reactor, thereby extracting the residual heat of the reaction products, eliminating the need for a separate feed gas preheating unit. Simultaneously, by setting up a secondary feed gas inlet pipe and a thermal extraction and guiding device in the dense phase zone of the fluidized bed reactor, the feed gas is added separately, and the bottom reaction heat is guided to the heat removal tube bundle in the dense phase zone, eliminating hot spots at the bottom of the reactor and improving the selectivity and purity of the target product 1,2-dichloroethane.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] On one hand, the present invention provides a reaction heat utilization device for the process of preparing 1,2-dichloroethane by oxychlorination of ethylene. The reaction heat utilization device includes a fluidized bed reactor, which is divided into a dense phase zone and a dilute phase zone, with the dense phase zone located below the dilute phase zone.

[0011] The dilute phase region is equipped with a heat exchange tube bundle, the outlet of which is connected to the bottom inlet of the fluidized bed reactor. The dense phase region is equipped with a secondary feed gas inlet pipe, a thermal extraction guide device, and a heat removal tube bundle. The thermal extraction guide device includes a frustum-shaped constricted orifice and a vertical guide pipe. The frustum-shaped constricted orifice is located below the vertical guide pipe and connected to it. The outlet of the secondary feed gas inlet pipe is connected to the side wall of the vertical guide pipe. The heat removal tube bundle is located at the outlet end of the vertical guide pipe.

[0012] In this invention, for the oxychlorination reaction of ethylene with oxygen and hydrogen chloride carried out in a fluidized bed reactor, the structure of the fluidized bed reactor is improved. Based on the division of the dilute phase zone and the dense phase zone in the fluidized bed reactor, a heat exchange tube bundle is set in the dilute phase zone to preheat the feed gas with high-temperature reaction gas, extract the waste heat of the gaseous products, reduce the flow rate of the gaseous products in the dilute phase zone, reduce catalyst entrainment and loss, and eliminate the need for additional external preheating units, thereby reducing equipment investment and energy consumption.

[0013] Meanwhile, a secondary feed gas injection pipe and a thermal extraction and diversion device are installed in the dense phase zone of the fluidized bed reactor to control the separate injection of feed gas, avoid excessive concentration of feed gas, and help control the state of feed gas. According to the structural characteristics of the thermal extraction and diversion device, the reaction heat at the bottom of the reactor is guided to the heat removal tube bundle in the dense phase zone through the airflow, which helps to eliminate hot spots at the bottom of the reactor, reduce the occurrence of side reactions, and improve the selectivity and purity of the target product 1,2-dichloroethane. The reaction heat utilization device has a simple structure and high operational flexibility, which helps to improve heat utilization and reduce energy consumption, reduce catalyst loss, and has strong operational stability, which helps to improve the economy of the reaction.

[0014] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The technical objectives and beneficial effects of the present invention can be better achieved and realized through the following technical solutions.

[0015] As a preferred embodiment of the present invention, the top outlet of the fluidized bed reactor is connected to a product separation unit, and the product separation unit separates a portion of the gas and returns it to the fluidized bed reactor.

[0016] Preferably, the product separation unit separates a portion of the gas as recirculated gas, which is then compressed and mixed with the ethylene feed gas before being added to the fluidized bed reactor.

[0017] Preferably, the dilute phase zone of the fluidized bed reactor is further provided with a gas-solid separator, such as a cyclone separator.

[0018] In this invention, based on the characteristics of ethylene oxychlorination reaction and fluidized bed reactor, it usually also includes auxiliary supporting equipment to ensure the integrity of the device and to separate, recover and recycle the reaction products.

[0019] As a preferred technical solution of the present invention, the heat exchange tube bundle in the dilute phase region includes at least three sets of serpentine heat exchange tube bundles, and each set of serpentine heat exchange tube bundles includes multiple serpentine heat exchange tubes.

[0020] Preferably, the inner diameter of the serpentine heat exchange tube is 20 to 200 mm, such as 20 mm, 40 mm, 60 mm, 80 mm, 100 mm, 120 mm, 150 mm, 180 mm or 200 mm, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 40 to 105 mm.

[0021] In this invention, the structural dimensions of the serpentine heat exchange tubes in the heat exchange tube bundle, such as the selection of the inner diameter, help to obtain higher heat exchange efficiency and improve the space utilization rate inside the reactor. If the inner diameter of the serpentine heat exchange tube is too small, it will cause the pressure drop on the feed gas side of the heat exchange tube bundle to be too large, thus failing to meet the reactor's requirements for feed flow rate. If the inner diameter of the serpentine heat exchange tube is too large, it will result in the heat exchange area per unit volume of the serpentine heat exchange tube in the dilute phase region being too small, making it impossible to achieve effective recovery of reaction heat.

[0022] Preferably, the wall thickness of the serpentine heat exchange tube is 2 to 10 mm, such as 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm or 10 mm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 5 to 8 mm.

[0023] In this invention, the selection of the wall thickness of the serpentine heat exchange tube can ensure the mechanical strength of the serpentine heat exchange tube and obtain a high heat transfer coefficient. If the wall thickness is too large, the heat transfer coefficient will be too small and the heat transfer efficiency will decrease.

[0024] Preferably, the ratio of the straight section length of the serpentine heat exchange tube to the inner diameter of the dilute phase region where the serpentine heat exchange tube is located is 0.5 to 2.2, such as 0.5, 0.8, 1.0, 1.2, 1.5, 1.8, 2.0 or 2.2, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 1.5 to 2.

[0025] In this invention, controlling the ratio of the straight section length of the serpentine heat exchange tube to the inner diameter of the dilute phase region ensures that the high-temperature reaction products in the dilute phase region are in full contact with the serpentine heat exchange tube, achieving sufficient heat exchange. The high-temperature product gas is cooled in the dilute phase region of the reactor, and its volume gradually shrinks, thereby reducing the product gas flow rate. Some of the catalyst entrained by the gas is deposited and returned to the reactor due to the decrease in gas velocity, thus avoiding a large amount of catalyst entering the cyclone separator and being damaged by high-speed friction and collision of particles, resulting in fine catalyst powder, thereby reducing the amount of catalyst loss.

[0026] Preferably, the serpentine heat exchange tube is made of any one of titanium alloy, stainless steel, or nickel-chromium-iron alloy.

[0027] In this invention, the serpentine heat exchange tube is made of a material resistant to chloride ion corrosion, such as TA2, S22053 or INCONEL, which can achieve a high heat transfer coefficient and effectively prevent heat exchange tube corrosion and leakage.

[0028] As a preferred embodiment of the present invention, the heat exchange tube bundle includes an ethylene and circulating gas mixture preheating tube bundle, a hydrogen chloride preheating tube bundle, and an oxygen preheating tube bundle.

[0029] Preferably, the ethylene and circulating gas mixture preheating tube bundle, the hydrogen chloride preheating tube bundle, and the oxygen preheating tube bundle are arranged in parallel.

[0030] Preferably, the ethylene and circulating gas mixture, hydrogen chloride and oxygen are preheated separately and then connected to the gas distributor at the bottom of the fluidized bed reactor via a bottom feed pipeline.

[0031] Preferably, a branch line is connected to the feed line of the ethylene and circulating gas mixture and oxygen to the secondary feed gas injection line.

[0032] In this invention, based on the structure of a traditional fluidized bed reactor, the raw material gas is usually added entirely from the bottom feed line, resulting in a high concentration of raw material gas at the bottom. Due to the structural characteristics of the bottom of the reactor, it is difficult to directly arrange heat exchange tubes, which can easily lead to the formation of hot spots in the reaction. Therefore, this invention designs a secondary raw material gas addition pipe to add part of the raw material gas from the dense phase region, which helps to control the uniformity of the reaction.

[0033] Preferably, the secondary feed gas injection pipe includes a secondary injection pipe for a mixture of ethylene and circulating gas and a secondary injection pipe for oxygen.

[0034] In this invention, the secondary feed gas is selected as a mixture of ethylene and circulating gas and oxygen. The secondary introduction can adjust the local oxygen and ethylene partial pressure and the ethylene-oxygen partial pressure ratio in the dense phase region, so as to eliminate hot spots in the reactor as much as possible.

[0035] Preferably, the ratio of the distance between the secondary feed gas inlet pipe and the gas distributor at the bottom of the fluidized bed reactor to the inner diameter of the dense phase zone of the fluidized bed reactor is 0.3 to 1.2, for example, 0.3, 0.5, 0.6, 0.8, 1.0, or 1.2, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 0.5 to 0.8.

[0036] In this invention, the distance control between the secondary feed gas injection pipe and the bottom gas distributor ensures that the area where the secondary feed gas is injected is sufficiently far away from the hot spot area at the bottom of the reactor without heat exchange pipes, thus achieving effective control of the reaction hot spot. If the ratio of the secondary feed gas injection pipe to the inner diameter of the dense phase zone is too small, the partial pressure of oxygen and ethylene in the area at the bottom of the reactor without heat exchange pipes cannot be effectively reduced, and the reaction rate cannot be reduced. If the ratio is too large, the residence time of the secondary injected feed gas in the dense phase zone of the reactor will be insufficient, and the reaction conversion rate will be reduced.

[0037] As a preferred technical solution of the present invention, the number of the thermal extraction and diversion devices is at least 3, such as 3, 4, 6, 8, 10, 15, 20, 25 or 30, etc., but is not limited to the listed values. Other unlisted integer values ​​within this range are also applicable, preferably 4 to 30.

[0038] Preferably, the thermal extraction guiding device is equidistantly and radially symmetrically distributed around the axis of the fluidized bed reactor.

[0039] Preferably, the secondary feed gas inlet pipe is divided into a main secondary feed gas inlet pipe and secondary feed gas inlet branch pipes, and the main secondary feed gas inlet pipe branches out into multiple secondary feed gas inlet branch pipes which are respectively connected to each hot extraction guide device.

[0040] Preferably, the secondary feed gas inlet main includes a secondary feed gas inlet main for ethylene and circulating gas mixture and a secondary feed gas inlet main, and the secondary feed gas inlet branch includes a secondary feed gas inlet branch for ethylene and circulating gas mixture and a secondary feed gas inlet branch.

[0041] In this invention, based on the structural design of the hot extraction and guiding device, after the raw material gas is injected into the guiding vertical pipe, a high-speed airflow low-pressure zone is formed inside the pipe. The hot and high-temperature reaction gas in the lower part of the frustum-shaped constricted orifice is drawn from the low-pressure zone, and the hot airflow is guided to the heat removal tube bundle in the dense phase zone for heat exchange, thereby eliminating the local hot spots at the bottom of the reactor.

[0042] As a preferred technical solution of the present invention, the diameter of the frustum-shaped constricted orifice in the hot extraction and guiding device gradually decreases from bottom to top.

[0043] Preferably, the maximum diameter of the frustum-shaped constricted orifice is 150-300mm, such as 150mm, 180mm, 200mm, 220mm, 250mm, 270mm or 300mm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable. The minimum diameter is the same as the diameter of the guide vertical pipe.

[0044] Preferably, the angle between the smaller diameter surface in the frustum-shaped reduced-diameter opening and the generatrix is ​​90-120°, such as 90°, 95°, 100°, 105°, 110°, 115° or 120°, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0045] Preferably, the diameter of the vertical guide tube is 80-200mm, such as 80mm, 100mm, 120mm, 150mm, 180mm or 200mm, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable. The length is 300-500mm, such as 300mm, 350mm, 400mm, 550mm or 500mm, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0046] Preferably, the secondary feed gas inlet branch pipe is inclined and connected to the guide vertical pipe from bottom to top.

[0047] Preferably, the secondary injection branch pipe for the ethylene and circulating gas mixture and the secondary injection branch pipe for oxygen are symmetrically arranged on both sides of the guide vertical pipe.

[0048] Preferably, the angle between the secondary injection branch pipe for the ethylene and circulating gas mixture and the secondary injection branch pipe for oxygen and the vertical guide pipe is independently 45° to 75°, such as 45°, 50°, 55°, 60°, 65°, 70° or 75°, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0049] Preferably, the distance between the secondary inlet branch pipe for the ethylene and circulating gas mixture and the secondary inlet branch pipe for the oxygen and the vertical guide pipe is 40-60 mm, for example, 40 mm, 45 mm, 50 mm, 55 mm or 60 mm, but not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0050] In this invention, the structural dimensions of the thermal extraction and diversion device can ensure effective control of the reaction hotspots. If it deviates from the above-mentioned preferred range, the heat at the bottom of the reactor may not be effectively diverted to the heat removal tube bundle in the dense phase region, and the reaction hotspots may not be effectively eliminated.

[0051] Preferably, the heat-relieving tube bundle has the same structure as the heat-exchange tube bundle.

[0052] On the other hand, the present invention provides a method for utilizing the reaction heat in the process of preparing 1,2-dichloroethane by oxychlorination of ethylene using the above-mentioned reaction heat utilization device, the method comprising the following steps:

[0053] (1) Heat exchange tube bundles are installed in the dilute phase zone of the fluidized bed reactor to extract part of the reaction heat by preheating the raw gas.

[0054] (2) A secondary feed gas inlet pipe, a thermal extraction guide device and a heat removal tube bundle are set in the dense phase zone of the fluidized bed reactor. A portion of the feed gas that has been preheated in step (1) is introduced from the bottom of the fluidized bed reactor, and another portion is introduced from the secondary feed gas inlet pipe. The gas is guided by the thermal extraction guide device to the heat removal tube bundle for heat exchange, so as to realize the utilization of the reaction waste heat.

[0055] As a preferred technical solution of the present invention, the reaction in the fluidized bed reactor in step (1) is to prepare 1,2-dichloroethane by oxychlorination of ethylene with oxygen and hydrogen chloride.

[0056] Preferably, the raw material gas in step (1) includes a mixture of ethylene and recycled gas, hydrogen chloride, and oxygen.

[0057] Preferably, the circulating gas comprises ethylene, nitrogen, carbon dioxide, oxygen, and carbon monoxide.

[0058] Preferably, the temperature of the raw material gas before preheating in step (1) is 75-100°C, such as 75°C, 80°C, 85°C, 90°C, 95°C or 100°C, but not limited to the listed values. Other unlisted values ​​within this range are also applicable. The temperature after preheating is 160-180°C, such as 160°C, 165°C, 170°C, 175°C or 180°C, but not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0059] As a preferred technical solution of the present invention, in step (2), a portion of the mixture of ethylene and circulating gas and oxygen in the raw material gas is introduced through the secondary raw material gas inlet pipe.

[0060] Preferably, the oxygen introduced from the secondary feed gas inlet pipe accounts for 0 to 15% of the total oxygen added, such as 1%, 3%, 5%, 7%, 9%, 10%, 12%, or 15%, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 5 to 7%.

[0061] Preferably, the ethylene and circulating gas mixture introduced from the secondary feed gas inlet pipe accounts for 0-15% of the total mixed gas volume, such as 1%, 3%, 5%, 7%, 9%, 10%, 12%, or 15%, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 5-7%.

[0062] In this invention, controlling the proportion of feed gas added from the secondary feed gas injection pipe in the dense phase zone can ensure effective control of reaction hot spots. If the ratio is too small, the partial pressure of oxygen and ethylene in the area without heat exchange pipe at the bottom of the reactor cannot be effectively reduced, and hot spots cannot be eliminated. If the ratio is too large, the secondary injected feed gas will not stay in the dense phase zone of the reactor for a sufficient time, and the reaction conversion rate will decrease.

[0063] Preferably, after the ethylene and circulating gas mixture and oxygen are introduced from the secondary feed gas inlet pipe, the pressure ratio of ethylene and oxygen in the dense phase region is 1.67 to 1.76, such as 1.67, 1.68, 1.69, 1.70, 1.71, 1.72, 1.74 or 1.76, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0064] As a preferred technical solution of the present invention, the reaction pressure in the fluidized bed reactor is 0.3 to 0.6 MPa, for example, 0.3 MPa, 0.35 MPa, 0.4 MPa, 0.45 MPa, 0.5 MPa, 0.55 MPa or 0.6 MPa, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0065] Preferably, the reaction temperature in the fluidized bed reactor is 220–250°C, such as 220°C, 225°C, 230°C, 235°C, 240°C, 245°C, or 250°C, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0066] Preferably, the heat exchange medium in the heat removal tube bundle is boiler water.

[0067] Compared with the prior art, the present invention has the following beneficial effects:

[0068] (1) The device described in this invention improves the structure of the fluidized bed reactor by setting up a heat exchange tube bundle in the dilute phase zone, using high-temperature reaction gas to preheat the raw material gas, extracting the waste heat of the gas phase product, reducing the flow rate of the gas phase product in the dilute phase zone, reducing the entrainment and loss of the catalyst, and eliminating the need for additional external preheating units, thereby reducing equipment investment and energy consumption.

[0069] (2) The present invention sets up a secondary feed gas inlet pipe and a hot extraction guide device in the dense phase zone of the fluidized bed reactor to separately add the feed gas and guide the bottom reaction heat to the heat removal tube bundle in the dense phase zone, thereby eliminating the hot spot at the bottom of the reactor and improving the selectivity and purity of the target product 1,2-dichloroethane, with a selectivity of over 98.5% and a purity of over 98.8 wt%.

[0070] (3) The device described in this invention has a simple structure, high operational flexibility, helps to improve heat utilization and reduce energy consumption, reduces catalyst loss, and has strong operational stability, which helps to improve the economy of the reaction. Attached Figure Description

[0071] Figure 1 This is a schematic diagram of the reaction heat utilization device for the process of preparing 1,2-dichloroethane by oxychlorination of ethylene provided in Embodiment 1 of the present invention;

[0072] Figure 2 This is a schematic diagram of the cross-sectional structure of the dense phase region in the reaction heat utilization device provided in Embodiment 1 of the present invention;

[0073] Figure 3 This is a schematic diagram of the thermal extraction and guiding device in the reaction heat utilization device provided in Embodiment 1 of the present invention;

[0074] Among them, 1-fluidized bed reactor, 2-cyclone separator, 3-dense phase zone, 4-product separation unit, 5-circulating gas compressor, 6-dilute phase zone, 7-heat removal tube bundle, 8-ethylene and circulating gas mixture preheating tube bundle, 9-hydrogen chloride preheating tube bundle, 10-oxygen preheating tube bundle, 11-oxygen secondary injection main pipe, 12-ethylene and circulating gas mixture secondary injection main pipe, 13-hot extraction guide device, 14-frustum-shaped constriction orifice, 15-guide vertical pipe, 16-oxygen secondary injection branch pipe, 17-ethylene and circulating gas mixture secondary injection branch pipe. Detailed Implementation

[0075] To better illustrate the present invention and facilitate understanding of its technical solutions, the present invention is further described in detail below. However, the following embodiments are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0076] The following are typical but non-limiting embodiments of the present invention:

[0077] Example 1:

[0078] This embodiment provides a reaction heat utilization device for the process of preparing 1,2-dichloroethane by oxychlorination of ethylene. A schematic diagram of the reaction heat utilization device is shown below. Figure 1 As shown, it includes a fluidized bed reactor 1, which is divided into a dense phase zone 3 and a dilute phase zone 6, with the dense phase zone 3 located below the dilute phase zone 6;

[0079] The dilute phase region 6 is equipped with a heat exchange tube bundle, the outlet of which is connected to the bottom inlet of the fluidized bed reactor 1; the cross-sectional structure of the dense phase region 3 is shown in the figure. Figure 2As shown, the dense phase region 3 is equipped with a secondary feed gas injection pipe, a thermal extraction flow guiding device 13, and a heat removal tube bundle 7. A schematic diagram of the thermal extraction flow guiding device 13 is shown below. Figure 3 As shown, it includes a frustum-shaped reduced diameter inlet 14 and a flow guiding vertical pipe 15. The frustum-shaped reduced diameter inlet 14 is located below the flow guiding vertical pipe 15 and is connected to the flow guiding vertical pipe 15. The outlet of the secondary feed gas inlet pipe is connected to the side wall of the flow guiding vertical pipe 15. The heat removal tube bundle 7 is located at the outlet end of the flow guiding vertical pipe 15.

[0080] The top outlet of the fluidized bed reactor 1 is connected to a product separation unit 4. The product separation unit 4 separates a portion of the gas and returns it to the fluidized bed reactor 1. The product separation unit 4 separates a portion of the gas as circulating gas. The circulating gas is compressed by the circulating gas compressor 5 and mixed with the ethylene feed gas before being added to the fluidized bed reactor 1.

[0081] The dilute phase zone 6 of the fluidized bed reactor 1 is also equipped with a cyclone separator 2.

[0082] The heat exchange tube bundle in the dilute phase region 6 includes multiple sets of serpentine heat exchange tube bundles, and each set of serpentine heat exchange tube bundles includes multiple serpentine heat exchange tubes.

[0083] The serpentine heat exchange tube has an inner diameter of 40 mm and a wall thickness of 5 mm.

[0084] The ratio of the straight section length of the serpentine heat exchange tube to the inner diameter of the dilute phase region 6 where the serpentine heat exchange tube is located is 1.86.

[0085] The serpentine heat exchange tube is made of S22053 stainless steel.

[0086] The heat exchange tube bundle includes an ethylene and circulating gas mixture preheating tube bundle 8, a hydrogen chloride preheating tube bundle 9, and an oxygen preheating tube bundle 10 arranged in parallel.

[0087] The mixture of ethylene and circulating gas, hydrogen chloride and oxygen are preheated separately and then connected to the gas distributor at the bottom of the fluidized bed reactor 1 via the bottom feed pipeline.

[0088] A branch line is branched off from the feed line for the ethylene and circulating gas mixture and oxygen, which is then connected to the secondary feed gas injection line.

[0089] The secondary feed gas injection pipe includes a secondary injection pipe for a mixture of ethylene and circulating gas and a secondary injection pipe for oxygen.

[0090] The ratio of the distance between the secondary feed gas inlet pipe and the gas distributor at the bottom of the fluidized bed reactor 1 to the inner diameter of the dense phase zone 3 of the fluidized bed reactor 1 is 0.7.

[0091] The number of the thermal extraction diversion devices 13 is 4.

[0092] The thermal extraction guiding device 13 is equidistantly distributed radially around the axis of the fluidized bed reactor 1.

[0093] The secondary raw gas inlet pipe is divided into a main secondary raw gas inlet pipe and a secondary raw gas inlet branch pipe. The main secondary raw gas inlet pipe branches out into multiple secondary raw gas inlet branch pipes, which are respectively connected to each of the hot extraction and guiding devices 13.

[0094] The secondary feed gas inlet main includes an ethylene and circulating gas mixture secondary inlet main 12 and an oxygen secondary inlet main 11, and the secondary feed gas inlet branch includes an ethylene and circulating gas mixture secondary inlet branch 17 and an oxygen secondary inlet branch 16.

[0095] The diameter of the frustum-shaped constricted orifice 14 in the hot extraction guide device 13 gradually decreases from bottom to top.

[0096] The maximum diameter of the frustum-shaped constricted orifice 14 is 250 mm, and the minimum diameter is the same as the diameter of the guide vertical pipe 15; the angle between the smaller diameter surface of the frustum-shaped constricted orifice 14 and the generatrix is ​​100°.

[0097] The vertical guide tube 15 has a diameter of 100mm and a length of 400mm.

[0098] The secondary feed gas injection branch pipe is inclined and connects to the guide vertical pipe 15 from bottom to top.

[0099] The secondary injection branch pipe 17 for the ethylene and circulating gas mixture and the secondary injection branch pipe 16 for oxygen are symmetrically arranged on both sides of the guide vertical pipe 15.

[0100] The angle between the secondary injection branch pipe 17 for the ethylene and circulating gas mixture and the secondary injection branch pipe 16 for oxygen and the guide vertical pipe 15 is 60°.

[0101] The connection points of the secondary injection branch pipe 17 for the ethylene and circulating gas mixture and the secondary injection branch pipe 16 for oxygen with the guide vertical pipe 15 are both 50 mm above the lower inlet of the guide vertical pipe 15.

[0102] The heat-relief tube bundle 7 has the same structure as the heat exchange tube bundle.

[0103] Example 2:

[0104] This embodiment provides a reaction heat utilization device for the process of preparing 1,2-dichloroethane by oxychlorination of ethylene. The reaction heat utilization device includes a fluidized bed reactor 1, which is divided into a dense phase zone 3 and a dilute phase zone 6. The dense phase zone 3 is located below the dilute phase zone 6.

[0105] The dilute phase zone 6 is equipped with a heat exchange tube bundle, the outlet of which is connected to the bottom inlet of the fluidized bed reactor 1. The dense phase zone 3 is equipped with a secondary feed gas inlet pipe, a thermal extraction guide device 13, and a heat removal tube bundle 7. The thermal extraction guide device 13 includes a frustum-shaped constriction port 14 and a vertical guide pipe 15. The frustum-shaped constriction port 14 is located below the vertical guide pipe 15 and is connected to the vertical guide pipe 15. The outlet of the secondary feed gas inlet pipe is connected to the side wall of the vertical guide pipe 15. The heat removal tube bundle 7 is located at the outlet end of the vertical guide pipe 15.

[0106] The top outlet of the fluidized bed reactor 1 is connected to a product separation unit 4. The product separation unit 4 separates a portion of the gas and returns it to the fluidized bed reactor 1. The product separation unit 4 separates a portion of the gas as circulating gas. The circulating gas is compressed by the circulating gas compressor 5 and mixed with the ethylene feed gas before being added to the fluidized bed reactor 1.

[0107] The dilute phase zone 6 of the fluidized bed reactor 1 is also equipped with a cyclone separator 2.

[0108] The heat exchange tube bundle in the dilute phase region 6 includes multiple sets of serpentine heat exchange tube bundles, and each set of serpentine heat exchange tube bundles includes multiple serpentine heat exchange tubes.

[0109] The serpentine heat exchange tube has an inner diameter of 100 mm and a wall thickness of 8 mm.

[0110] The ratio of the straight section length of the serpentine heat exchange tube to the inner diameter of the dilute phase region 6 where the serpentine heat exchange tube is located is 1.0.

[0111] The serpentine heat exchange tube is made of TA2 titanium alloy.

[0112] The heat exchange tube bundle includes an ethylene and circulating gas mixture preheating tube bundle 8, a hydrogen chloride preheating tube bundle 9, and an oxygen preheating tube bundle 10 arranged in parallel.

[0113] The mixture of ethylene and circulating gas, hydrogen chloride and oxygen are preheated separately and then connected to the gas distributor at the bottom of the fluidized bed reactor 1 via the bottom feed pipeline.

[0114] A branch line is branched off from the feed line for the ethylene and circulating gas mixture and oxygen, which is then connected to the secondary feed gas injection line.

[0115] The secondary feed gas injection pipe includes a secondary injection pipe for a mixture of ethylene and circulating gas and a secondary injection pipe for oxygen.

[0116] The ratio of the distance between the secondary feed gas inlet pipe and the gas distributor at the bottom of the fluidized bed reactor 1 to the inner diameter of the dense phase zone 3 of the fluidized bed reactor 1 is 0.4.

[0117] The number of the thermal extraction diversion devices 13 is 10.

[0118] The thermal extraction guiding device 13 is equidistantly distributed radially around the axis of the fluidized bed reactor 1.

[0119] The secondary raw gas inlet pipe is divided into a main secondary raw gas inlet pipe and a secondary raw gas inlet branch pipe. The main secondary raw gas inlet pipe branches out into multiple secondary raw gas inlet branch pipes, which are respectively connected to each of the hot extraction and guiding devices 13.

[0120] The secondary feed gas inlet main includes an ethylene and circulating gas mixture secondary inlet main 12 and an oxygen secondary inlet main 11, and the secondary feed gas inlet branch includes an ethylene and circulating gas mixture secondary inlet branch 17 and an oxygen secondary inlet branch 16.

[0121] The diameter of the frustum-shaped constricted orifice 14 in the hot extraction guide device 13 gradually decreases from bottom to top.

[0122] The maximum diameter of the frustum-shaped constricted orifice 14 is 150 mm, and the minimum diameter is the same as the diameter of the vertical guide pipe 15; the angle between the smaller diameter surface of the frustum-shaped constricted orifice 14 and the generatrix is ​​120°.

[0123] The vertical guide tube 15 has a diameter of 150 mm and a length of 500 mm.

[0124] The secondary feed gas injection branch pipe is inclined and connects to the guide vertical pipe 15 from bottom to top.

[0125] The secondary injection branch pipe 17 for the ethylene and circulating gas mixture and the secondary injection branch pipe 16 for oxygen are symmetrically arranged on both sides of the guide vertical pipe 15.

[0126] The angle between the secondary injection branch pipe 17 for the ethylene and circulating gas mixture and the secondary injection branch pipe 16 for oxygen and the vertical guide pipe 15 is 45°.

[0127] The connection points of the secondary injection branch pipe 17 for the ethylene and circulating gas mixture and the secondary injection branch pipe 16 for oxygen to the vertical guide pipe 15 are both 60 mm above the lower inlet of the vertical guide pipe 15.

[0128] The heat-relief tube bundle 7 has the same structure as the heat exchange tube bundle.

[0129] Example 3:

[0130] This embodiment provides a reaction heat utilization device for the process of preparing 1,2-dichloroethane by oxychlorination of ethylene. The reaction heat utilization device includes a fluidized bed reactor 1, which is divided into a dense phase zone 3 and a dilute phase zone 6. The dense phase zone 3 is located below the dilute phase zone 6.

[0131] The dilute phase zone 6 is equipped with a heat exchange tube bundle, the outlet of which is connected to the bottom inlet of the fluidized bed reactor 1. The dense phase zone 3 is equipped with a secondary feed gas inlet pipe, a thermal extraction guide device 13, and a heat removal tube bundle 7. The thermal extraction guide device 13 includes a frustum-shaped constriction port 14 and a vertical guide pipe 15. The frustum-shaped constriction port 14 is located below the vertical guide pipe 15 and is connected to the vertical guide pipe 15. The outlet of the secondary feed gas inlet pipe is connected to the side wall of the vertical guide pipe 15. The heat removal tube bundle 7 is located at the outlet end of the vertical guide pipe 15.

[0132] The top outlet of the fluidized bed reactor 1 is connected to a product separation unit 4. The product separation unit 4 separates a portion of the gas and returns it to the fluidized bed reactor 1. The product separation unit 4 separates a portion of the gas as circulating gas. The circulating gas is compressed by the circulating gas compressor 5 and mixed with the ethylene feed gas before being added to the fluidized bed reactor 1.

[0133] The dilute phase zone 6 of the fluidized bed reactor 1 is also equipped with a cyclone separator 2.

[0134] The heat exchange tube bundle in the dilute phase region 6 includes multiple sets of serpentine heat exchange tube bundles, and each set of serpentine heat exchange tube bundles includes multiple serpentine heat exchange tubes.

[0135] The serpentine heat exchange tube has an inner diameter of 200 mm and a wall thickness of 10 mm.

[0136] The ratio of the straight section length of the serpentine heat exchange tube to the inner diameter of the dilute phase region 6 where the serpentine heat exchange tube is located is 2.0.

[0137] The serpentine heat exchange tube is made of nickel-chromium-iron alloy.

[0138] The heat exchange tube bundle includes an ethylene and circulating gas mixture preheating tube bundle 8, a hydrogen chloride preheating tube bundle 9, and an oxygen preheating tube bundle 10 arranged in parallel.

[0139] The mixture of ethylene and circulating gas, hydrogen chloride and oxygen are preheated separately and then connected to the gas distributor at the bottom of the fluidized bed reactor 1 via the bottom feed pipeline.

[0140] A branch line is branched off from the feed line for the ethylene and circulating gas mixture and oxygen, which is then connected to the secondary feed gas injection line.

[0141] The secondary feed gas injection pipe includes a secondary injection pipe for a mixture of ethylene and circulating gas and a secondary injection pipe for oxygen.

[0142] The ratio of the distance between the secondary feed gas inlet pipe and the gas distributor at the bottom of the fluidized bed reactor 1 to the inner diameter of the dense phase zone 3 of the fluidized bed reactor 1 is 1.2.

[0143] The number of the thermal extraction diversion devices 13 is 20.

[0144] The thermal extraction guiding device 13 is equidistantly distributed radially around the axis of the fluidized bed reactor 1.

[0145] The secondary raw gas inlet pipe is divided into a main secondary raw gas inlet pipe and a secondary raw gas inlet branch pipe. The main secondary raw gas inlet pipe branches out into multiple secondary raw gas inlet branch pipes, which are respectively connected to each of the hot extraction and guiding devices 13.

[0146] The secondary feed gas inlet main includes an ethylene and circulating gas mixture secondary inlet main 12 and an oxygen secondary inlet main 11, and the secondary feed gas inlet branch includes an ethylene and circulating gas mixture secondary inlet branch 17 and an oxygen secondary inlet branch 16.

[0147] The diameter of the frustum-shaped constricted orifice 14 in the hot extraction guide device 13 gradually decreases from bottom to top.

[0148] The maximum diameter of the frustum-shaped constricted orifice 14 is 300 mm, and the minimum diameter is the same as the diameter of the guide vertical pipe 15; the angle between the smaller diameter surface of the frustum-shaped constricted orifice 14 and the generatrix is ​​110°.

[0149] The vertical guide tube 15 has a diameter of 200 mm and a length of 300 mm.

[0150] The secondary feed gas injection branch pipe is inclined and connects to the guide vertical pipe 15 from bottom to top.

[0151] The secondary injection branch pipe 17 for the ethylene and circulating gas mixture and the secondary injection branch pipe 16 for oxygen are symmetrically arranged on both sides of the guide vertical pipe 15.

[0152] The angle between the secondary injection branch pipe 17 for the ethylene and circulating gas mixture and the secondary injection branch pipe 16 for oxygen and the vertical guide pipe 15 is 75°.

[0153] The connection points of the secondary injection branch pipe 17 for the ethylene and circulating gas mixture and the secondary injection branch pipe 16 for oxygen with the guide vertical pipe 15 are both 40 mm above the lower inlet of the guide vertical pipe 15.

[0154] The heat-relief tube bundle 7 has the same structure as the heat exchange tube bundle.

[0155] Example 4:

[0156] This embodiment provides a method for utilizing the heat of reaction in the process of preparing 1,2-dichloroethane by oxychlorination of ethylene. The method is carried out using the apparatus in Example 1 and includes the following steps:

[0157] (1) A heat exchange tube bundle is set in the dilute phase zone 6 of the fluidized bed reactor 1 to extract part of the reaction heat by preheating the raw gas. The raw gas includes a mixture of ethylene and circulating gas, hydrogen chloride and oxygen. The circulating gas consists of ethylene, nitrogen, carbon dioxide, oxygen and carbon monoxide. The temperature of the raw gas before preheating is 90°C and the temperature after preheating is 170°C.

[0158] (2) A secondary feed gas inlet pipe, a hot extraction and flow guiding device 13, and a heat removal tube bundle 7 are installed in the dense phase zone 3 of the fluidized bed reactor 1. The hydrogen chloride preheated in step (1), a portion of the ethylene and circulating gas mixture, and oxygen are introduced from the bottom of the fluidized bed reactor 1. Another portion of the ethylene and circulating gas mixture, accounting for 7% of their respective totals, and oxygen are introduced from the secondary feed gas inlet pipe. The pressure ratio of ethylene to oxygen in the dense phase zone 3 is 1.68. The reaction pressure in the fluidized bed reactor 1 is 0.3 MPa, and the average reaction temperature is 235°C. The gas is guided by the hot extraction and flow guiding device 13 to the heat removal tube bundle 7 for heat exchange. The heat exchange medium in the heat removal tube bundle 7 is boiler water, so as to realize the utilization of the reaction waste heat.

[0159] In this embodiment, the heat of ethylene oxychlorination reaction is utilized using the above-mentioned device and method. The fluidized bed reactor can operate continuously for more than 300 days, and the bed temperature does not fluctuate significantly during the process. The selectivity for producing 1,2-dichloroethane, measured in ethylene, reaches 98.8%, the purity of 1,2-dichloroethane reaches 99.2%, and the average catalyst loss is 5 kg / d.

[0160] Example 5:

[0161] This embodiment provides a method for utilizing the heat of reaction in the process of preparing 1,2-dichloroethane by oxychlorination of ethylene. The method is carried out using the apparatus in Example 1 and includes the following steps:

[0162] (1) A heat exchange tube bundle is set in the dilute phase zone 6 of the fluidized bed reactor 1 to extract part of the reaction heat by preheating the raw gas. The raw gas includes a mixture of ethylene and circulating gas, hydrogen chloride and oxygen. The circulating gas consists of ethylene, nitrogen, carbon dioxide, oxygen and carbon monoxide. The temperature of the raw gas before preheating is 75°C and the temperature after preheating is 160°C.

[0163] (2) A secondary feed gas inlet pipe, a hot extraction and flow guiding device 13, and a heat removal tube bundle 7 are installed in the dense phase zone 3 of the fluidized bed reactor 1. The hydrogen chloride, which was preheated in step (1), a portion of the ethylene and circulating gas mixture, and oxygen are introduced from the bottom of the fluidized bed reactor 1. Another portion of the ethylene and circulating gas mixture, which accounts for 15% of their respective totals, and oxygen are introduced from the secondary feed gas inlet pipe. The pressure ratio of ethylene to oxygen in the dense phase zone 3 is 1.75. The reaction pressure in the fluidized bed reactor 1 is 0.5 MPa, and the average reaction temperature is 220°C. The gas is guided by the hot extraction and flow guiding device 13 to the heat removal tube bundle 7 for heat exchange. The heat exchange medium in the heat removal tube bundle 7 is boiler water, so as to realize the utilization of the reaction waste heat.

[0164] In this embodiment, the heat of ethylene oxychlorination reaction is utilized using the above-mentioned device and method. The fluidized bed reactor can operate continuously for more than 300 days, and the bed temperature does not fluctuate significantly during the process. The selectivity for producing 1,2-dichloroethane, measured in ethylene, reaches 98.6%, the purity of 1,2-dichloroethane reaches 99.0%, and the average catalyst loss is 4 kg / d.

[0165] Comparative Example 1:

[0166] This comparative example provides a device and method for utilizing the reaction heat in the process of preparing 1,2-dichloroethane by oxychlorination of ethylene. The device is the same as that in Example 1, except that the dilute phase zone 6 of the fluidized bed reactor 1 is not equipped with heat exchange tube bundles, and saturated steam is used to preheat the raw material gas.

[0167] The method is the same as that in Example 4, except that in step (1), the raw material gas is preheated by steam and the reaction product in the dilute phase region is discharged directly without cooling.

[0168] In this comparative example, since the fluidized bed reactor does not have a heat exchange tube bundle, the high-temperature reaction products are discharged directly without cooling treatment, resulting in low reaction heat utilization rate and a large amount of catalyst entrainment, with an average catalyst loss of 15 kg / d. Furthermore, the preheating of the raw gas requires an additional preheating unit, resulting in high steam consumption, equipment cost, and energy consumption.

[0169] Comparative Example 2:

[0170] This comparative example provides a device and method for utilizing the heat of reaction in the process of preparing 1,2-dichloroethane by oxychlorination of ethylene. The device is the same as that in Example 1, except that the dense phase zone 3 of the fluidized bed reactor 1 is not equipped with a secondary feed gas inlet pipe and a thermal extraction and guiding device 13.

[0171] The method is the same as that in Example 4, except that: in step (2), the preheated raw material gas is introduced from the bottom of the fluidized bed reactor 1, and there is no heat extraction and guiding device.

[0172] In this comparative example, since no secondary feed gas inlet pipe was installed, all feed gas was fed into the reactor from the bottom of the fluidized bed heat exchanger. Without the guiding effect of the heat extraction and diversion device, the hot spot problem at the bottom of the fluidized bed was more serious, and the temperature in some areas was too high, exceeding the average temperature by 6°C. This easily led to side reactions, resulting in a decrease in the selectivity and purity of 1,2-dichloroethane. Measured by ethylene, the selectivity for producing 1,2-dichloroethane was 97.0%, and the purity of 1,2-dichloroethane was 98.0%.

[0173] As can be seen from the above embodiments and comparative examples, the device of the present invention improves the structure of the fluidized bed reactor by setting a heat exchange tube bundle in the dilute phase zone, using high-temperature reaction gas to preheat the feed gas, extracting the waste heat of the gaseous products, reducing the flow rate of the gaseous products in the dilute phase zone, reducing catalyst entrainment and loss, and eliminating the need for an additional external preheating unit, thus reducing equipment investment and energy consumption. By setting a secondary feed gas inlet pipe and a hot extraction and guiding device in the dense phase zone of the fluidized bed reactor, the feed gas is added separately, and the bottom reaction heat is guided to the heat removal tube bundle in the dense phase zone, eliminating hot spots at the bottom of the reactor, improving the selectivity and purity of the target product 1,2-dichloroethane, with a selectivity of over 98.5% and a purity of over 98.8 wt%. The device has a simple structure, high operational flexibility, helps to improve heat utilization and reduce energy consumption, reduces catalyst loss, and has strong operational stability, which helps to improve the economy of the reaction.

[0174] The present invention has been illustrated with the above embodiments to describe the detailed apparatus and method of the present invention. However, the present invention is not limited to the detailed apparatus and method described above, that is, it does not mean that the present invention must rely on the detailed apparatus and method described above to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the apparatus of the present invention, additions of auxiliary devices, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A device for utilizing the reaction heat in the process of oxychlorination of ethylene to prepare 1,2-dichloroethane, characterized in that, The reaction heat utilization device includes a fluidized bed reactor, which is divided into a dense phase zone and a dilute phase zone, with the dense phase zone located below the dilute phase zone. The dilute phase region is equipped with a heat exchange tube bundle, the outlet of which is connected to the bottom inlet of the fluidized bed reactor. The dense phase region is equipped with a secondary feed gas inlet pipe, a thermal extraction guide device, and a heat removal tube bundle. The thermal extraction guide device includes a frustum-shaped constricted orifice and a vertical guide pipe. The frustum-shaped constricted orifice is located below the vertical guide pipe and connected to it. The outlet of the secondary feed gas inlet pipe is connected to the side wall of the vertical guide pipe. The heat removal tube bundle is located at the outlet end of the vertical guide pipe.

2. The reaction heat utilization device according to claim 1, characterized in that, The top outlet of the fluidized bed reactor is connected to a product separation unit, which separates a portion of the gas and returns it to the fluidized bed reactor.

3. The reaction heat utilization device according to claim 2, characterized in that, The product separation unit separates a portion of the gas into recirculating gas, which is then compressed and mixed with the ethylene feed gas before being added to the fluidized bed reactor.

4. The reaction heat utilization device according to claim 1, characterized in that, The fluidized bed reactor is also equipped with a gas-solid separator in the dilute phase zone.

5. The reaction heat utilization device according to claim 1, characterized in that, The heat exchange tube bundle in the dilute phase region includes at least three sets of serpentine heat exchange tube bundles, and each set of serpentine heat exchange tube bundles includes multiple serpentine heat exchange tubes.

6. The reaction heat utilization device according to claim 5, characterized in that, The inner diameter of the serpentine heat exchange tube is 20~200mm.

7. The reaction heat utilization device according to claim 6, characterized in that, The inner diameter of the serpentine heat exchange tube is 40~105mm.

8. The reaction heat utilization device according to claim 5, characterized in that, The wall thickness of the serpentine heat exchange tube is 2~10mm.

9. The reaction heat utilization device according to claim 8, characterized in that, The wall thickness of the serpentine heat exchange tube is 5~8mm.

10. The reaction heat utilization device according to claim 5, characterized in that, The ratio of the straight section length of the serpentine heat exchanger to the inner diameter of the dilute phase region where the serpentine heat exchanger is located is 0.5 to 2.

2.

11. The reaction heat utilization device according to claim 10, characterized in that, The ratio of the straight section length of the serpentine heat exchange tube to the inner diameter of the dilute phase region where the serpentine heat exchange tube is located is 1.5~2.

12. The reaction heat utilization device according to claim 5, characterized in that, The serpentine heat exchange tube is made of any one of titanium alloy, stainless steel, or nickel-chromium-iron alloy.

13. The reaction heat utilization device according to claim 1, characterized in that, The heat exchange tube bundle includes an ethylene and circulating gas mixture preheating tube bundle, a hydrogen chloride preheating tube bundle, and an oxygen preheating tube bundle.

14. The reaction heat utilization device according to claim 13, characterized in that, The ethylene and circulating gas mixture preheating tube bundle, the hydrogen chloride preheating tube bundle, and the oxygen preheating tube bundle are arranged in parallel.

15. The reaction heat utilization device according to claim 13, characterized in that, The mixture of ethylene and circulating gas, hydrogen chloride, and oxygen are preheated separately and then connected to the gas distributor at the bottom of the fluidized bed reactor via the bottom feed pipeline.

16. The reaction heat utilization device according to claim 15, characterized in that, A branch line is branched off from the feed line for the ethylene and circulating gas mixture and oxygen, which is then connected to the secondary feed gas injection line.

17. The reaction heat utilization device according to claim 16, characterized in that, The secondary feed gas injection pipe includes a secondary injection pipe for a mixture of ethylene and circulating gas and a secondary injection pipe for oxygen.

18. The reaction heat utilization device according to claim 17, characterized in that, The ratio of the distance between the secondary feed gas inlet pipe and the gas distributor at the bottom of the fluidized bed reactor to the inner diameter of the dense phase zone of the fluidized bed reactor is 0.3 to 1.

2.

19. The reaction heat utilization device according to claim 18, characterized in that, The ratio of the distance between the secondary feed gas inlet pipe and the gas distributor at the bottom of the fluidized bed reactor to the inner diameter of the dense phase zone of the fluidized bed reactor is 0.5 to 0.

8.

20. The reaction heat utilization device according to claim 1, characterized in that, The number of the thermal extraction diversion devices is at least three.

21. The reaction heat utilization device according to claim 20, characterized in that, The number of the thermal extraction diversion devices is 4 to 30.

22. The reaction heat utilization device according to claim 20, characterized in that, The thermal extraction guiding devices are equidistantly distributed radially around the axis of the fluidized bed reactor.

23. The reaction heat utilization device according to claim 20, characterized in that, The secondary feed gas inlet pipe is divided into a main secondary feed gas inlet pipe and secondary feed gas inlet branch pipes. The main secondary feed gas inlet pipe branches out into multiple secondary feed gas inlet branch pipes, which are respectively connected to each hot extraction guide device.

24. The reaction heat utilization device according to claim 23, characterized in that, The secondary feed gas inlet main includes a secondary feed gas inlet main for ethylene and circulating gas mixture and a secondary feed gas inlet main for oxygen. The secondary feed gas inlet branch includes a secondary feed gas inlet branch for ethylene and circulating gas mixture and a secondary feed gas inlet branch.

25. The reaction heat utilization device according to claim 1, characterized in that, The diameter of the frustum-shaped constricted orifice in the hot extraction guide device gradually decreases from bottom to top.

26. The reaction heat utilization device according to claim 1, characterized in that, The maximum diameter of the frustum-shaped constricted orifice is 150-300 mm, and the minimum diameter is the same as the diameter of the vertical guide pipe.

27. The reaction heat utilization device according to claim 25, characterized in that, The angle between the smaller diameter surface of the truncated cone-shaped nozzle and the generatrix is ​​90° to 120°, and the angle is not 90°.

28. The reaction heat utilization device according to claim 1, characterized in that, The diameter of the vertical guide tube is 80~200mm and the length is 300~500mm.

29. The reaction heat utilization device according to claim 23, characterized in that, The secondary feed gas inlet branch pipe is inclined and connects to the guide vertical pipe from bottom to top.

30. The reaction heat utilization device according to claim 24, characterized in that, The secondary injection branch pipes for the ethylene and circulating gas mixture and the secondary injection branch pipes for oxygen are symmetrically arranged on both sides of the guide vertical pipe.

31. The reaction heat utilization device according to claim 30, characterized in that, The angle between the secondary injection branch pipe for the ethylene and circulating gas mixture and the secondary injection branch pipe for oxygen and the vertical guide pipe is independently 45~75°.

32. The reaction heat utilization device according to claim 30, characterized in that, The distance between the secondary injection branch pipe for the ethylene and circulating gas mixture and the secondary injection branch pipe for oxygen and the vertical guide pipe is 40~60mm.

33. The reaction heat utilization device according to claim 1, characterized in that, The heat removal tube bundle has the same structure as the heat exchange tube bundle.

34. A method for utilizing the reaction heat in the process of preparing 1,2-dichloroethane by oxychlorination of ethylene using the apparatus described in any one of claims 1-33, characterized in that, The method for utilizing the heat of reaction includes the following steps: (1) Heat exchange tube bundles are installed in the dilute phase zone of the fluidized bed reactor to extract part of the reaction heat by preheating the raw gas; (2) A secondary feed gas inlet pipe, a thermal extraction and flow guiding device and a heat removal tube bundle are set in the dense phase zone of the fluidized bed reactor. A portion of the feed gas that has been preheated in step (1) is introduced from the bottom of the fluidized bed reactor, and another portion is introduced from the secondary feed gas inlet pipe. After being guided by the thermal extraction and flow guiding device, the reaction gas is guided to the heat removal tube bundle for heat exchange, so as to realize the utilization of the reaction waste heat.

35. The method for utilizing the heat of reaction according to claim 34, characterized in that, The reaction in the fluidized bed reactor in step (1) is to prepare 1,2-dichloroethane by oxychlorination of ethylene with oxygen and hydrogen chloride.

36. The method for utilizing the heat of reaction according to claim 34, characterized in that, The raw material gas in step (1) includes a mixture of ethylene and recycled gas, hydrogen chloride and oxygen.

37. The method for utilizing the heat of reaction according to claim 36, characterized in that, The circulating gas consists of ethylene, nitrogen, carbon dioxide, oxygen, and carbon monoxide.

38. The method for utilizing the heat of reaction according to claim 34, characterized in that, The temperature of the raw gas before preheating in step (1) is 75~100℃, and the temperature after preheating is 160~180℃.

39. The method for utilizing the heat of reaction according to claim 36, characterized in that, In step (2), a portion of the mixture of ethylene and circulating gas and oxygen in the raw material gas is introduced through the secondary raw material gas inlet pipe.

40. The method for utilizing the heat of reaction according to claim 39, characterized in that, The oxygen introduced through the secondary feed gas injection pipe accounts for 0-15% of the total oxygen injection.

41. The method for utilizing the heat of reaction according to claim 40, characterized in that, The oxygen introduced through the secondary feed gas injection pipe accounts for 5-7% of the total oxygen injection.

42. The method for utilizing the heat of reaction according to claim 39, characterized in that, The ethylene and recycle gas mixture introduced through the secondary feed gas injection pipe accounts for 0-15% of the total mixture.

43. The method for utilizing the heat of reaction according to claim 42, characterized in that, The ethylene and recycle gas mixture introduced through the secondary feed gas injection pipe accounts for 5-7% of the total mixture.

44. The method for utilizing the heat of reaction according to claim 36, characterized in that, After the ethylene and circulating gas mixture and oxygen are introduced through the secondary feed gas inlet pipe, the pressure ratio of ethylene and oxygen in the dense phase region is 1.67~1.

76.

45. The method for utilizing the heat of reaction according to claim 34, characterized in that, The reaction pressure inside the fluidized bed reactor is 0.3~0.6 MPa.

46. ​​The method for utilizing the heat of reaction according to claim 34, characterized in that, The average reaction temperature in the fluidized bed reactor is 220~250℃.

47. The method for utilizing the heat of reaction according to claim 34, characterized in that, The heat exchange medium in the heat removal tube bundle is boiler water.

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