A composite ethylene glycol hydrogenation reactor and ethylene glycol hydrogenation process

Abstract

The present application discloses a composite ethylene glycol hydrogenation reactor, which includes a shell having a radial reaction section and a pre-reaction section; a gas distribution pipe and an outer gas cylinder are arranged in the radial reaction section, and a heat exchange pipe is arranged in the main reaction chamber; the upper end and the lower end of the heat exchange pipe are respectively connected to the refrigerant outlet pipe and the refrigerant riser; a pre-reaction section including a shell and a reaction tube is arranged in the pre-reaction section, the lower end of the gas distribution pipe is connected to the gas guide pipe, the gas guide pipe is connected to the discharge end of the reaction tube, and the refrigerant riser is connected to the shell side of the pre-reaction section. The present application also discloses a hydrogenation process. The present application can avoid the problem of catalyst "powdering" caused by a series of reasons such as excessive flow rate or uneven distribution of inlet gas passing through the catalyst, excessive flow rate at the local catalyst, uneven distribution of reaction temperature, local "overheating", and too fast start or stop speed, resulting in a sudden increase or decrease in flow rate, a sharp rise or drop in temperature, etc.

Description

Technical Field

[0001] The invention relates to a composite ethylene glycol hydrogenation reactor and an ethylene glycol hydrogenation process. Background Art

[0002] At present, the reactors used for ethylene glycol hydrogenation include axial reactors and radial reactors. During production, the raw gas directly enters the catalyst bed outside the heat exchange tube. In order to allow the raw gas to enter the bed evenly for reaction, a gas distribution device is provided at the outlet of the inlet pipe so that the raw gas entering the reactor can enter the bed evenly for reaction. However, due to the high concentration of the effective components of the raw gas initially entering the reactor, the reaction speed is fast when it contacts the catalyst, resulting in excessively high local reaction temperature, especially when starting and stopping, which will cause a drastic change in the raw gas flow rate, resulting in a drastic change in the reaction temperature, and easily causing the catalyst "powdering" phenomenon, that is, part of the catalyst is powdered, causing the blockage of the gas flow channel in the bed, reducing the effective reaction area. At the same time, excessively high local reaction temperature is also easy to cause the catalyst "coking" problem, and thus lead to the increase of side reactions. Since the by-products generated by the side reactions will have an adverse effect on subsequent reactions, the reaction conditions will be further deteriorated. Summary of the invention

[0003] In order to solve the above problems, the present invention first proposes a composite ethylene glycol hydrogenation reactor, which includes a shell extending in the vertical direction, a partition head is arranged in the shell, and the partition head divides the inner cavity of the shell into a radial reaction section located on the upper side and a pre-reaction section located on the lower side; a refrigerant outlet pipe and a process gas outlet pipe are installed on the top of the shell;

[0004] A gas distribution pipe extending in the vertical direction is arranged at the center of the radial reaction section, an outer gas cylinder is arranged outside the gas distribution pipe, a main reaction chamber is formed between the gas distribution pipe and the outer gas cylinder, a heat exchange pipe is arranged in the main reaction chamber, and a first catalyst is loaded outside the heat exchange pipe; the upper end of the heat exchange pipe is connected to the refrigerant outlet pipe, and the lower end of the heat exchange pipe is connected to the refrigerant riser pipe; an annular gap connected only to the process gas outlet pipe is formed between the outer gas cylinder and the outer shell;

[0005] A first air hole connected to the main reaction chamber is provided on the air distribution pipe, and a second air hole connected to the annular gap and the main reaction chamber is provided on the outer air cylinder. The reaction gas can enter the main reaction chamber through the first air hole on the air distribution pipe, and then enter the annular gap through the second air hole.

[0006] A pre-reaction part is arranged in the pre-reaction section, and the pre-reaction part includes a shell, a reaction tube extending in a vertical direction is arranged in the shell, a second catalyst is loaded in the reaction tube, two ends of the reaction tube are respectively formed as a feed end and a discharge end, and a process gas inlet pipe connected to the feed end of the reaction tube and a refrigerant inlet pipe connected to the shell side of the pre-reaction part are installed on the shell;

[0007] The upper end of the gas distribution pipe is closed, and the lower end of the gas distribution pipe is sealed and connected to an air guide pipe, which is communicated with the gas distribution pipe. The air guide pipe seals downward through the partition head and then connects to the discharge end of the reaction tube. The refrigerant riser seals downward through the partition head and then connects to the shell side of the pre-reaction part.

[0008] The pre-reaction section in the present application is actually formed into an axial reaction section with the function of a tubular heat exchanger, so that the present reactor includes an axial reaction section and a water-bed-type radial reaction section. In the axial reaction section, the refrigerant runs outside the tube, and in the radial reaction section, the refrigerant runs inside the tube. The refrigerant used in the present reactor is a steam-water mixture, in which the water can not only absorb the reaction heat when evaporating, but also maintain the temperature of the steam-water mixture, so that the reactor in the present application can be operated with uniform temperature during production, and the temperature adjustment "dead zone" is eliminated, so that the temperature distribution of the reactor is more uniform. During production, the raw gas first passes through the axial reaction section, and then enters the radial reaction bed upward. When the raw gas passes through the reaction tube, it will undergo a pre-reaction. By adjusting the temperature and flow of the refrigerant, the temperature in the pre-reaction section can be better controlled, thereby controlling the inlet temperature of the radial reaction section. The pre-reaction section in the present application is mainly used to remove toxic and harmful substances in the raw gas and retain the components that are prone to coking in the reaction tube. Since the place where coking is most likely to occur in the hydrogenation reaction is located at the reaction inlet of the raw gas, in the present application, an axial reaction section is specially set up, and the reaction tube is used as the reaction area. Even if coking occurs, the coke blocks produced will be located in the reaction tube, which can protect the radial reaction section, avoid large-scale replacement of the first catalyst, reduce production costs, and the coke blocks in the reaction tube can be cleaned more conveniently to quickly resume production and improve production efficiency.

[0009] In this reactor, a pre-reaction section is provided and the pre-reaction section is made the starting stage of the reaction, so the coking problem of the reaction is kept in the pre-reaction section, and the gas discharged from the pre-reaction section can enter the first catalyst area through the gas distribution pipe for reaction. This avoids the problem of catalyst "powdering" caused by a series of reasons such as excessive flow rate or uneven distribution of inlet gas passing through the catalyst, excessive flow rate at local catalyst, uneven distribution of reaction temperature, local "overheating", and too fast start or stop speed, which causes the flow rate to suddenly increase or decrease, and the temperature to rise or fall sharply.

[0010] At the same time, it can also eliminate the problem of increased side reactions and coking caused by inappropriate hydrogen-ester ratio and inappropriate raw gas composition, which leads to the inability to continue production.

[0011] Furthermore, a catalyst support is detachably mounted at the lower end of the reaction tube, an air flow channel is arranged on the catalyst support, and a discharge pipe is mounted on the outer shell, and the discharge pipe is used to discharge the second catalyst in the reaction tube. The catalyst support can specifically be a spring bracket, a threaded pipe cap with holes, and other components.

[0012] This design makes it easier to replace the second catalyst in the reaction tube. When the second catalyst becomes clogged due to coking or the like, or the catalytic effect is reduced due to poisoning or the like, the catalyst support can be removed from the reaction tube, and then the catalyst in the reaction tube can be discharged and replaced.

[0013] Furthermore, in order to provide good support for the catalyst, ceramic balls are stacked on the catalyst support, and the ceramic balls are used to support the second catalyst.

[0014] Specifically, the shell of the pre-reaction part includes an outer sleeve, an upper annular tube sheet and a lower annular tube sheet. The outer sleeve is sleeved on one end of the air guide pipe that passes downward through the partition head. The upper annular tube sheet is installed at the upper end of the outer sleeve, and the lower annular tube sheet is installed at the lower end of the outer sleeve. The upper annular tube sheet and the lower annular tube sheet are both sealed and connected to the air guide pipe, so that the space surrounded by the upper annular tube sheet, the lower annular tube sheet, the outer sleeve and the air guide pipe forms an annular pre-reaction chamber.

[0015] The shell is sealed and connected to the outer shell, so that an air inlet cavity is formed between the shell and the partition head, and a return air cavity is formed between the shell and the bottom of the outer shell; the process gas inlet pipe is installed in the outer shell area corresponding to the air inlet cavity; the upper end of the reaction tube is installed on the upper annular tube plate and connected to the air inlet cavity, the lower end of the reaction tube is installed on the lower annular tube plate and connected to the return air cavity, and the lower end of the air guide pipe is downwardly connected to the return air cavity.

[0016] In the pre-reaction section, the upper side of the shell is formed as an air inlet chamber, and the lower side of the shell is formed as a return air chamber. When the raw gas enters the air inlet chamber, it will evenly enter each reaction tube, and after a pre-reaction, it will enter the return air chamber. In the return air chamber, the gas discharged from each reaction tube is remixed to form a gas with relatively uniform temperature and composition, and then enters the radial reaction section upward through the air guide pipe for reaction.

[0017] A separate outer sleeve is provided in the pre-reaction section, and the outer sleeve is not regarded as a part of the shell. When the reaction tube is heated, it can drive the upper annular tube sheet or the lower annular tube sheet to freely extend to a certain extent, thereby avoiding being restricted by the outer shell. Moreover, the outer sleeve will also extend synchronously with the reaction at high temperature, thereby reducing the internal stress generated by the high temperature in various components of the pre-reaction section.

[0018] Furthermore, the refrigerant inlet pipe is connected to the upper end of the outer sleeve.

[0019] Since the raw gas enters the reaction tube from top to bottom, the reaction is most intense and the reaction heat is the greatest when it just enters the reaction tube. By connecting the refrigerant inlet pipe to the upper end of the outer sleeve, the refrigerant just entering the reaction tube can immediately absorb the reaction heat at the inlet of the reaction tube, thereby avoiding excessive reaction temperature, reducing or even eliminating the formation of coking, and strictly controlling the reaction temperature from the initial stage of the reaction, thereby reducing the fluctuation range of the reaction temperature in the reactor.

[0020] Further, only the upper annular tube sheet is sealingly connected to the outer shell.

[0021] The pre-reaction section can be partitioned by only sealingly connecting the upper annular tube sheet to the shell to form the air inlet chamber and the air return chamber. Since the reaction is carried out at high temperature, the reaction tube will expand to a certain extent. This design enables the reaction tube to drive the lower annular tube sheet to move downward. At the same time, since part of the air guide pipe is also part of the shell, the air guide pipe will also extend downward synchronously during the reaction, so that there is minimal internal stress between the reaction tube, the upper annular tube sheet, the lower annular tube sheet and the air guide pipe, ensuring safe connection between the various parts.

[0022] However, if the upper annular tube sheet and the lower annular tube sheet seals are connected to the outer shell, the free expansion and contraction of the reaction tube will be restricted, and stress will be generated in the reaction tube. When the stress is large, it will cause the reaction tube to bend, which is easy to cause cracks in the welding places between the reaction tube and the upper annular tube sheet and the lower annular tube sheet, which is not conducive to the safe operation of the equipment.

[0023] Even if only the lower annular tube sheet is connected to the outer shell, the free downward extension of the air duct when heated will be hindered, resulting in unnecessary internal stress between the air duct and the lower annular tube sheet.

[0024] Specifically, the height of the reaction tube is 2-3 meters.

[0025] Since the reaction tube is mainly used as the inlet reaction place of the raw gas, so that the raw gas can smoothly pass through the initial reaction which is most likely to form coke, the reaction tube should not be set too long, and it is sufficient to allow the raw gas to smoothly pass through the initial reaction. Within the above height range, it is possible to ensure that the raw gas can smoothly pass through the initial reaction section which is most likely to form coke, and within the above height range, it is also easy to clean and dredge the coke blocks generated in the reaction tube.

[0026] Secondly, the present application also discloses an ethylene glycol hydrogenation process. The ethylene glycol hydrogenation process in the present application refers to a production process for producing ethylene glycol by hydrogenating dimethyl oxalate.

[0027] The ethylene glycol hydrogenation process is carried out using any of the above-mentioned composite ethylene glycol hydrogenation reactors. The specific process of the ethylene glycol hydrogenation process is as follows:

[0028] The raw gas enters the reaction tube through the process gas inlet pipe for pre-reaction, and is discharged from the reaction tube to become pre-reaction gas;

[0029] The pre-reaction gas enters the gas distribution pipe through the gas guide pipe, and enters the main reaction chamber through the first gas hole to undergo the main reaction to form a reaction mixture. The reaction mixture enters the annular gap through the second gas hole, and is discharged through the process gas outlet pipe to enter the next process.

[0030] The refrigerant enters the shell side of the pre-reaction section through the refrigerant inlet pipe, absorbs the reaction heat of the pre-reaction through the reaction tube, and then enters the heat exchange tube through the refrigerant riser pipe, absorbs the reaction heat of the main reaction, and is discharged through the refrigerant outlet pipe.

[0031] In the ethylene glycol hydrogenation process, when the raw gas containing dimethyl oxalate and hydrogen first enters the reaction tube, a pre-reaction is carried out. Since coking is most likely to occur at the inlet of the reaction tube, the refrigerant entering the reactor first absorbs the pre-reaction heat through the reaction tube. The refrigerant can quickly absorb the reaction heat, so that the reaction temperature in the reaction tube can be within the set range, avoiding the occurrence of temperature runaway, thereby reducing or even avoiding the occurrence of coking.

[0032] At present, in order to ensure the temperature control effect, the refrigerant generally flows from bottom to top and the raw gas flows from top to bottom, that is, the refrigerant and the gas flow in the opposite direction. When the refrigerant reaches the inlet of the raw gas, it is already at the highest temperature, and the initial reaction temperature of the raw gas cannot be strictly controlled. This also makes it easier for the raw gas to produce a temperature runaway phenomenon at the inlet, leading to coking.

[0033] After the pre-reaction in the reaction tube, some impurity gases in the raw gas are retained in the reaction tube. After entering the main reaction chamber, the pre-reaction gas can react smoothly without coking. In this hydrogenation process, the pre-reaction gas enters the gas distribution pipe from bottom to top, and then enters the first catalyst radially for reaction. Although the refrigerant absorbs the reaction heat, the temperature in the catalyst bed will still rise slightly from bottom to top in the axial direction. The process gas outlet pipe is set at the top of the reactor. Due to the reduction in gas density, the reaction gas can naturally flow upward and discharge the reactor through the process gas outlet pipe, so that the temperature in the radial reaction section can be more evenly distributed.

[0034] Specifically, the inlet temperature of the raw gas at the process gas inlet pipe is 170-180°C, the reaction temperature in the reaction tube is 185-195°C, and the reaction pressure in the reaction tube is 1.0-3.2MPa; the reaction temperature of the main reaction chamber is 180-190°C, the reaction pressure in the reaction tube is 1.0-3.2MPa, and the outlet temperature of the reaction mixture at the process gas outlet pipe is 190-210°C;

[0035] The refrigerant is a steam-water mixture, the initial temperature of the steam-water mixture at the refrigerant inlet pipe is 155-165°C, the terminal temperature of the steam-water mixture at the refrigerant outlet pipe is 155-165°C, and the temperature difference between the initial temperature and the terminal temperature of the steam-water mixture is 0-5°C.

[0036] In the present application, within the above reaction temperature and pressure, under the premise of ensuring the reaction efficiency, the coking phenomenon can be minimized to the greatest extent. Since a soda-water mixture is used as a refrigerant to absorb the reaction heat, the water in the soda-water mixture can absorb a large amount of heat energy when vaporizing, and the temperature is kept stable, the reaction temperature can be controlled within a narrow range, so as to control the progress of the reaction and keep the temperature in the entire reactor in a relatively stable temperature environment. Since a soda-water mixture is used as a refrigerant, the side reaction caused by uneven temperature distribution is well solved. And under the above reaction conditions, the reaction can be carried out in a controllable manner.

[0037] The hydrogen-ester ratio of the feed gas is 40-120, and the hydrogen-ester ratio is further preferably 55-85. The hydrogen-ester ratio refers to the molar ratio of hydrogen and dimethyl oxalate. At present, a high hydrogen-ester ratio of 80-100 is generally used to improve the conversion rate of dimethyl oxalate and the yield of ethylene glycol, but high hydrogen-ester also leads to an increase in by-products. If the hydrogen-ester ratio is too low, incomplete hydrogenation will result, and if the hydrogen-ester ratio is too high, excessive hydrogenation will result, both of which will cause side reactions to occur, produce a large amount of by-products, affect the yield of the product, and also increase the difficulty of separation and purification of subsequent products.

[0038] In the present application, a wider range of hydrogen-ester ratios is adopted, which can not only adapt to high hydrogen-ester ratios, but also to low hydrogen-ester ratios, so as to adapt to a wider range of raw material fluctuations. However, since a pre-reaction section is provided, when the raw gas passes through the pre-reaction section, not only can the coke blocks that may be produced be retained in the reaction tube, but also after passing through the pre-reaction section, it is formed into pre-reaction gas. Since the process state of the pre-reaction gas has reached the conditions required for the reaction in the radial reaction section, the pre-reaction gas can immediately reach a normal reaction state after entering the radial reaction section. There is no longer a need to control the initial reaction temperature and pressure as in the prior art, and there is no need to worry about the occurrence of coking.

[0039] Since the pre-reaction gas can immediately enter the normal reaction state in the radial reaction section, the conversion rate of dimethyl oxalate and the yield of ethylene glycol can still be guaranteed after adopting a wide range of hydrogen-ester ratios in the present application. That is, in the case of low hydrogen-ester ratios and high hydrogen-ester ratios, the present application can still effectively improve the conversion rate of dimethyl oxalate and the yield of ethylene glycol, and can reduce side reactions and by-products.

[0040] In the present application, the conversion rate of dimethyl oxalate can reach more than 99% and the yield of ethylene glycol can reach more than 96%. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a structural schematic diagram of an embodiment of a composite ethylene glycol hydrogenation reactor.

[0042] Figure 2 This is a schematic diagram of the first installation of the catalyst support at the lower end of the reaction tube.

[0043] Figure 3 This is a schematic diagram of the second installation of the catalyst support at the lower end of the reaction tube. DETAILED DESCRIPTION

[0044] The composite ethylene glycol hydrogenation reactor is first described below.

[0045] Example 1

[0046] See also Figure 1 A composite ethylene glycol hydrogenation reactor comprises a shell 10 extending in a vertical direction, the shell 10 comprises an intermediate cylinder 11 extending in a vertical direction, an upper head 12 installed on the top of the intermediate cylinder 11, and a lower head 13 installed on the intermediate cylinder 11, a partition head 15 is arranged in the shell 10, and the partition head divides the inner cavity of the shell into a radial reaction section 100 located on the upper side and a pre-reaction section 200 located on the lower side.

[0047] A refrigerant outlet pipe 41 and a process gas outlet pipe 34 are installed on the upper cover of the shell.

[0048] A gas distribution pipe 33 extending in the vertical direction is arranged at the center of the radial reaction section 100, an outer gas cylinder 45 is arranged on the outer surface of the gas distribution pipe 33, and a main reaction chamber is formed between the gas distribution pipe 33 and the outer gas cylinder 45. An upper tube sheet 43 is arranged at the top of the main reaction chamber, an upper tube sheet head 42 is installed on the upper side of the upper tube sheet, and the lower end of the refrigerant outlet pipe 41 is welded to the upper tube sheet head 24. A lower tube sheet 53 is arranged at the bottom of the main reaction chamber, a lower tube sheet head 52 is installed on the lower side of the lower tube sheet, and a refrigerant riser 51 extending downward is installed on the lower tube sheet head 52. The two ends of the heat exchange tube 44 are respectively installed on the upper tube sheet 43 and the lower tube sheet 53. The first catalyst is filled outside the heat exchange tube 44.

[0049] An annular gap 46 communicating only with the process gas outlet pipe is formed between the outer gas cylinder 45 and the intermediate cylinder 11 of the outer shell 10 .

[0050] A first air hole connected to the main reaction chamber is provided on the air distribution pipe 33, and a second air hole connected to the annular gap 46 and the main reaction chamber is provided on the outer air cylinder 45. The reaction gas can enter the main reaction chamber through the first air hole on the air distribution pipe, and then enter the annular gap through the second air hole. In the drawings, the first air hole and the second air hole are not shown.

[0051] The upper end of the gas distribution pipe 33 is blocked with a blind plate 35, and an air guide pipe 32 is sealed and connected to the lower end of the gas distribution pipe 33. The air guide pipe 32 is connected to the gas distribution pipe 33, and the air guide pipe 32 seals downward through the partition head 15 and extends into the pre-reaction section 200.

[0052] A pre-reaction part 20 is arranged in the pre-reaction section 200, and the pre-reaction part includes a shell, and the shell includes an outer sleeve 23, an upper annular tube sheet 21 and a lower annular tube sheet 22. The upper annular tube sheet 21 and the lower annular tube sheet 22 are sleeved on the air guide tube 32 and are sealed and welded to the air guide tube 32. The outer peripheral surface of the upper annular tube sheet is sealed and welded to the intermediate cylinder 11. The upper end of the outer sleeve 23 is welded to the lower surface of the upper annular tube sheet 21, and the lower end is welded to the lower annular tube sheet 22, so that the space surrounded by the upper annular tube sheet 21, the lower annular tube sheet 22, the outer sleeve 23 and the air guide tube 23 forms an annular pre-reaction chamber. That is, the shell is sealedly connected to the outer shell, and an air inlet chamber 210 is formed between the shell and the partition head 15, and a return air chamber 220 is formed between the shell and the lower head 13 of the outer shell.

[0053] In this embodiment, only the outer peripheral surface of the upper annular tube sheet is sealed and welded to the intermediate cylinder 11 .

[0054] A reaction tube 24 is installed in the pre-reaction chamber. The reaction tube 24 extends in the vertical direction. The upper end of the reaction tube 24 is welded to the upper annular tube sheet 21 and connected to the air inlet chamber 210. The lower end of the reaction tube 24 is welded to the lower annular tube sheet 22 and connected to the return air chamber 220. The lower end of the air guide pipe 32 is downwardly connected to the return air chamber 220. The upper end of the reaction tube 24 is formed as a feed end, and the lower end of the reaction tube is formed as a discharge end. That is, the air guide pipe passes through the partition head downward in a sealed manner and is connected to the discharge end of the reaction tube. A plurality of baffles 25 are arranged in the pre-reaction chamber. The baffles are arranged at intervals in the height direction, and each baffle extends in the horizontal direction.

[0055] In the embodiment, the height of the reaction tube is 2.5 meters. It is understood that in other embodiments, the height of the reaction tube can also be 2 meters, 2.3 meters, 2.8 meters or 3 meters. The second catalyst is filled in the reaction tube.

[0056] A process gas inlet pipe 31 is installed in the outer shell area corresponding to the air inlet chamber 210. In the pre-reaction chamber, the outer space of the reaction tube forms the shell side of the pre-reaction part. The refrigerant inlet pipe 26 is installed on the intermediate cylinder 11, and penetrates the outer sleeve 23 inwardly and is connected to the shell side of the pre-reaction part. In this embodiment, the refrigerant inlet pipe 26 is connected to the upper end of the outer sleeve 23.

[0057] The refrigerant riser pipe passes through the partition head downward in a sealed manner and is welded to the upper annular tube sheet 21, and then passes through the upper annular tube sheet 21 to connect to the shell side of the pre-reaction part.

[0058] Please also see Figure 2 A spring bracket 241 is inserted at the lower end of the reaction tube, and a ceramic ball 242 is loaded on the top of the spring bracket 241. The ceramic ball is used to support the second catalyst. The spring bracket serves as a catalyst support. The gap between the spring wires of the spring bracket forms an airflow channel. In this embodiment, the spring bracket 241 used includes a tapered portion 2411 extending into the interior of the reaction tube and a cylindrical portion 2412 facing the exterior of the reaction tube, wherein the cylindrical portion is held in the reaction tube by elasticity, and the tapered portion is provided for inserting into the reaction tube. In this embodiment, the tapered portion 2411 of the spring bracket 241 is inserted upward into the lower end of the reaction tube.

[0059] It can be understood that in another embodiment, please refer to Figure 3 A threaded pipe cap 244 with a through hole 2441 can also be used as a catalyst support. The threaded pipe cap 244 is screwed onto the inner wall thread or the outer wall thread of the reaction tube, and the through hole 2441 forms an air flow channel.

[0060] A lower manhole 132 is installed on the lower end cap 13, and the lower end cap is located at the lower side of the reaction tube. The lower manhole also serves as a discharge pipe for discharging the catalyst in the reaction tube. An intermediate manhole 14 is installed in the shell area corresponding to the air inlet cavity 210, and an upper manhole 16 is installed on the top of the shell.

[0061] The following is an explanation of the ethylene glycol hydrogenation process, which is carried out using the above-mentioned composite ethylene glycol hydrogenation reactor, and the specific steps are as follows:

[0062] The raw gas from the process gas inlet pipe refrigerant inlet pipe 26 enters the gas inlet chamber 210 through the process gas inlet pipe 31, and then disperses into each reaction tube 24 to undergo a pre-reaction to become a pre-reaction gas.

[0063] After the pre-reaction gas is discharged from the reaction tube 24, it enters the return air chamber 220, then goes up through the air guide pipe 32 into the air distribution pipe 33, and enters the main reaction chamber through the first air hole to carry out the main reaction to form a reaction mixture. The reaction mixture enters the annular gap 46 through the second air hole. After entering the annular gap 46, the reaction mixture goes up into the process gas outlet pipe 34, and then is discharged from the reactor to enter the next process.

[0064] The refrigerant enters the shell side of the pre-reaction section through the refrigerant inlet pipe 26, absorbs the reaction heat of the pre-reaction through the reaction tube, and then enters the heat exchange tube 44 upward through the refrigerant riser 51, absorbs the reaction heat of the main reaction, and is discharged through the refrigerant outlet pipe 41.

[0065] The ethylene glycol hydrogenation process is described below.

[0066] Example 2

[0067] In this embodiment, the hydrogen-ester ratio of the raw gas is 80, the inlet temperature of the raw gas at the process gas inlet pipe is 170-175°C, the reaction temperature in the reaction tube is 186-191°C, and the reaction pressure in the reaction tube is 1.0-2.8MPa. The reaction temperature of the main reaction chamber is 180-185°C, the reaction pressure of the main reaction chamber is 1.0-2.8MPa, and the outlet temperature of the reaction mixture at the process gas outlet pipe is 190-200°C.

[0068] The refrigerant is a steam-water mixture, the initial temperature of the steam-water mixture at the refrigerant inlet pipe is 158-161°C, the terminal temperature of the steam-water mixture at the refrigerant outlet pipe is 158-161°C, and the temperature difference between the initial temperature and the terminal temperature of the steam-water mixture is 0-2°C.

[0069] The conversion rate of dimethyl oxalate can reach 99.7% and the yield of ethylene glycol can reach 96.4%.

[0070] During the operation of the ethylene glycol hydrogenation reactor, coke masses were found at the inlet of the reaction tube 24, but no coke masses were found in the middle part of the reaction tube to the lower end of the reaction tube, and no coke masses were found in the radial reaction section, indicating that the use of the reaction tube can effectively avoid the coking phenomenon in the radial reaction section which serves as the main reaction area.

[0071] When cleaning the coke blocks in the reaction tube, just pull out the spring bracket 241 under the reaction tube to discharge the second catalyst therein. For the coke blocks partially adhering to the inner wall of the reaction tube, just use a steel chisel or other rod-shaped basis to clear them to clean the coke blocks. Then insert the spring bracket into the lower end of the reaction tube and pour the second catalyst into it from the upper end of the reaction tube.

[0072] Example 3

[0073] In this embodiment, the hydrogen-ester ratio of the raw gas is 50, the inlet temperature of the raw gas at the process gas inlet pipe is 175-180°C, the reaction temperature in the reaction tube is 190-195°C, and the reaction pressure in the reaction tube is 1.0-2.6MPa. The reaction temperature of the main reaction chamber is 185-190°C, the reaction pressure of the main reaction chamber is 1.0-2.6MPa, and the outlet temperature of the reaction mixture at the process gas outlet pipe is 205-210°C.

[0074] The refrigerant is a steam-water mixture, the initial temperature of the steam-water mixture at the refrigerant inlet pipe is 160-165°C, the terminal temperature of the steam-water mixture at the refrigerant outlet pipe is 160-165°C, and the temperature difference between the initial temperature and the terminal temperature of the steam-water mixture is 1-4°C.

[0075] In this embodiment, the conversion rate of dimethyl oxalate can reach 99.5% and the yield of ethylene glycol can reach 96.1%.

[0076] No coke was found in the reaction tube and the radial reaction section, indicating that the composite ethylene glycol hydrogenation reactor and ethylene glycol hydrogenation process in the present application can effectively avoid large-scale coking in the radial reaction section, the reaction runs smoothly, and the conversion rate of dimethyl oxalate and the yield of ethylene glycol can reach a high level.

Claims

1. A composite ethylene glycol hydrogenation reactor, characterized in that: The invention comprises a shell extending in a vertical direction, wherein a partition head is arranged in the shell, and the partition head divides the inner cavity of the shell into a radial reaction section located at the upper side and a pre-reaction section located at the lower side; a refrigerant outlet pipe and a process gas outlet pipe are installed at the top of the shell; A gas distribution pipe extending in the vertical direction is arranged at the center of the radial reaction section, an outer gas cylinder is arranged outside the gas distribution pipe, a main reaction chamber is formed between the gas distribution pipe and the outer gas cylinder, a heat exchange pipe is arranged in the main reaction chamber, and a first catalyst is loaded outside the heat exchange pipe; the upper end of the heat exchange pipe is connected to the refrigerant outlet pipe, and the lower end of the heat exchange pipe is connected to the refrigerant riser pipe; an annular gap connected only to the process gas outlet pipe is formed between the outer gas cylinder and the outer shell; A first air hole connected to the main reaction chamber is provided on the air distribution pipe, and a second air hole connected to the annular gap and the main reaction chamber is provided on the outer air cylinder. The reaction gas can enter the main reaction chamber through the first air hole on the air distribution pipe, and then enter the annular gap through the second air hole. A pre-reaction part is arranged in the pre-reaction section, and the pre-reaction part includes a shell, a reaction tube extending in a vertical direction is arranged in the shell, a second catalyst is loaded in the reaction tube, two ends of the reaction tube are respectively formed as a feed end and a discharge end, and a process gas inlet pipe connected to the feed end of the reaction tube and a refrigerant inlet pipe connected to the shell side of the pre-reaction part are installed on the shell; The upper end of the gas distribution pipe is closed, and the lower end of the gas distribution pipe is sealed and connected to an air guide pipe, which is connected to the gas distribution pipe, and the air guide pipe is sealed downward through the partition head and connected to the discharge end of the reaction tube, and the refrigerant riser is sealed downward through the partition head and connected to the shell side of the pre-reaction part; The shell of the pre-reaction part includes an outer sleeve, an upper annular tube sheet and a lower annular tube sheet. The outer sleeve is sleeved on one end of the air guide pipe passing downward through the partition head. The upper annular tube sheet is installed on the upper end of the outer sleeve, and the lower annular tube sheet is installed on the lower end of the outer sleeve. The upper annular tube sheet and the lower annular tube sheet are both sealedly connected to the air guide pipe, so that the space surrounded by the upper annular tube sheet, the lower annular tube sheet, the outer sleeve and the air guide pipe forms an annular pre-reaction chamber. The shell is sealedly connected to the outer shell, so that an air inlet cavity is formed between the shell and the bulkhead, and an air return cavity is formed between the shell and the bottom of the outer shell; The process gas inlet pipe is installed in the shell area corresponding to the air inlet cavity; the upper end of the reaction tube is installed on the upper annular tube plate and connected to the air inlet cavity, the lower end of the reaction tube is installed on the lower annular tube plate and connected to the return air cavity, and the lower end of the air guide pipe is downwardly connected to the return air cavity.

2. The composite ethylene glycol hydrogenation reactor according to claim 1, characterized in that: A catalyst support is detachably mounted at the lower end of the reaction tube, an air flow channel is arranged on the catalyst support, and a discharge pipe is mounted on the outer shell, the discharge pipe is used to discharge the second catalyst in the reaction tube.

3. The composite ethylene glycol hydrogenation reactor according to claim 2, characterized in that: Ceramic balls are stacked on the catalyst support and are used to support the second catalyst.

4. The composite ethylene glycol hydrogenation reactor according to claim 3, characterized in that: The refrigerant inlet pipe is connected to the upper end of the outer sleeve.

5. The composite ethylene glycol hydrogenation reactor according to claim 3, characterized in that: Only the upper annular tube sheet is sealingly connected to the outer shell.

6. The composite ethylene glycol hydrogenation reactor according to claim 1, characterized in that: The height of the reaction tube is 2-3 meters.

7. An ethylene glycol hydrogenation process, which is carried out using the composite ethylene glycol hydrogenation reactor according to any one of claims 1 to 6, characterized in that: The raw gas enters the reaction tube through the process gas inlet pipe for pre-reaction, and is discharged from the reaction tube to become pre-reaction gas; The pre-reaction gas enters the gas distribution pipe through the gas guide pipe, and enters the main reaction chamber through the first gas hole to undergo the main reaction to form a reaction mixture. The reaction mixture enters the annular gap through the second gas hole, and is discharged through the process gas outlet pipe to enter the next process. The refrigerant enters the shell side of the pre-reaction section through the refrigerant inlet pipe, absorbs the reaction heat of the pre-reaction through the reaction tube, and then enters the heat exchange tube through the refrigerant riser pipe, absorbs the reaction heat of the main reaction, and is discharged through the refrigerant outlet pipe.

8. The ethylene glycol hydrogenation process according to claim 7, characterized in that: The inlet temperature of the raw gas at the process gas inlet pipe is 170-180°C, the reaction temperature in the reaction tube is 185-195°C, and the reaction pressure in the reaction tube is 1.0-3.2MPa; the reaction temperature of the main reaction chamber is 180-190°C, the reaction pressure of the main reaction chamber is 1.0-3.2MPa, and the outlet temperature of the reaction mixture at the process gas outlet pipe is 190-210°C; The refrigerant is a steam-water mixture, the initial temperature of the steam-water mixture at the refrigerant inlet pipe is 155-165°C, the terminal temperature of the steam-water mixture at the refrigerant outlet pipe is 155-165°C, and the temperature difference between the initial temperature and the terminal temperature of the steam-water mixture is 0-5°C.

9. The ethylene glycol hydrogenation process according to claim 7, characterized in that: The hydrogen-ester ratio of the raw gas is 40-120.

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