A method and apparatus for producing dimethyl ether

Abstract

The application relates to the technical field of dimethyl ether preparation, and provides a dimethyl ether production method, which comprises the following steps: S1, raw material methanol vaporization; S2, methanol dehydration to prepare dimethyl ether; S3, dimethyl ether separation and rectification; S4, tail gas treatment; and S5, methanol recovery. Based on this, the high-temperature reaction gas generated in the reaction is sent back to a heat exchanger through heat exchange pipe one and sent back to a preheater through heat exchange pipe two, so that the temperature of the unreacted methanol steam in the front end is increased, the use power of a reboiler one in a methanol tower and the use power of the preheater are reduced, and the effect of saving electric energy can be achieved. In addition, a device applied to the dimethyl ether production method is also provided, which is mainly used for the dehydration reaction of methanol steam in the step S2.

Description

Technical Field

[0001] This application relates to the field of dimethyl ether preparation technology, and in particular to a method and apparatus for producing dimethyl ether. Background Technology

[0002] Dimethyl ether, commonly known as methyl ether or oxydimethyl ether, has the structural formula CH3OCH3. Dimethyl ether is a low-boiling-point compound, mainly used as a raw material for organic synthesis. It can also be used as a solvent, aerosol, refrigerant, and anesthetic, or as a substitute for civilian compound ethanol and Freon aerosol. Its uses are wide-ranging.

[0003] The production methods of dimethyl ether mainly fall into two categories: one-step synthesis gas extraction and the methanol process. The methanol process is further divided into the methanol gas-phase method and the methanol liquid-phase method. Industrial production typically uses the methanol gas-phase dehydration method to prepare dimethyl ether. This process includes several steps such as methanol vaporization, dehydration reaction, product separation, distillation, and tail gas treatment. The reaction equipment involved includes methanol towers, dimethyl ether towers, flash stripping towers, dehydration reactors, and alcohol washing towers. Because the production process requires frequent heating and vaporization of liquid methanol and liquid reactants, multiple reaction units are equipped with reboilers. However, the continuous operation of multiple reboilers for extended periods consumes a large amount of electricity, which is inconsistent with the energy-saving and environmentally friendly principles of modern construction and therefore requires improvement. Summary of the Invention

[0004] To reduce the electrical energy consumed in the preparation of dimethyl ether, this application provides a method and apparatus for producing dimethyl ether.

[0005] Firstly, the dimethyl ether production method provided in this application adopts the following technical solution: A method for producing dimethyl ether includes the following steps: Step S1, methanol vaporization: The methanol raw material is stored in a methanol storage tank. During production, the methanol raw material is preheated by a preheater and then sent to the methanol tower. The reboiler in the bottom of the methanol tower heats and vaporizes the methanol raw material to form methanol vapor. Step S2, methanol dehydration to dimethyl ether; the methanol vapor discharged from the methanol tower is sent to the reactor after passing through the heat exchanger, where a dehydration reaction occurs to generate dimethyl ether; the high-temperature reaction gas generated after the reaction is sent to heat exchange tube 1 inside the heat exchanger to exchange heat with the methanol vapor, and to heat exchange tube 2 inside the preheater to exchange heat with the methanol feedstock, and then sent to the dimethyl ether tower. Step S3, dimethyl ether separation and distillation; the high-temperature reaction gas includes dimethyl ether, methanol, water and a small amount of non-condensable gas. After entering the dimethyl ether tower, the high-temperature reaction gas is heated by the reboiler 2 in the bottom of the dimethyl ether tower. The dimethyl ether vapor and a small amount of non-condensable gas rise along the tower and enter the condenser at the top of the tower for condensation. The dimethyl ether formed by condensation is collected as a product. The high-temperature bottom liquid of the dimethyl ether tower is discharged to the flash stripper for methanol recovery, while the methanol collected from the middle of the dimethyl ether tower is transported back to the methanol storage tank. Step S4, tail gas treatment: Dimethyl ether vapor and non-condensable gases rise along the tower and are discharged to the alcohol washing tower through the condenser. Dimethyl ether is recovered by washing with methanol in the alcohol washing tower. The tail gas produced by the alcohol washing tower is discharged outside the tower, and the alcohol washing liquid that has absorbed dimethyl ether is sent back to the dimethyl ether tower for treatment. Step S5, methanol recovery: The high-temperature bottom liquid discharged from the methanol tower bottom and the dimethyl ether tower bottom is sent to the flash stripper. The reboiler three of the flash stripper bottom heats the high-temperature bottom liquid. The methanol contained in the high-temperature bottom liquid rises along the tower through flash vaporization, is condensed by the condenser, and is then sent back to the methanol storage tank.

[0006] By adopting the above technical solution, when preparing dimethyl ether using the dimethyl ether production method of this application, methanol is heated and vaporized in the methanol tower to form methanol vapor, which enters the heat exchanger. The methanol vapor inside the downstream reactor undergoes a dehydration reaction to form high-temperature reaction gas. The high-temperature reaction gas is sent back to the heat exchanger via heat exchange tube one and back to the preheater via heat exchange tube two. It can exchange heat with the unreacted methanol vapor at the front end, thereby increasing the temperature of the unreacted methanol vapor. This reduces the operating power of the reboiler in the methanol tower, the preheater, and the heating device in the reactor, thus saving energy.

[0007] In addition, after the high-temperature reaction gas enters the dimethyl ether tower, it is heated by the reboiler. The dimethyl ether vapor rises along the tower and is condensed by the condenser, where it can be collected as a product. The tail gas discharged from the condenser is sent to the alcohol washing tower to recover the dimethyl ether contained therein and to reheat the dimethyl ether tower for distillation separation, which is beneficial to improving the extraction and conversion rate of dimethyl ether. The high-temperature bottom liquid discharged from the methanol tower and the dimethyl ether tower bottom is sent to the flash vapor stripping tower, where the methanol vapor contained therein can be flash vaporized, condensed, and added back to the methanol storage tank for further production, which is beneficial to improving the methanol preparation conversion rate.

[0008] Optionally, in step S2, when methanol vapor is fed into the reactor, it first enters the heat exchange tube three inside the reactor, where the heat generated by the dehydration reaction exchanges heat with the methanol vapor inside the heat exchange tube three; the superheated methanol vapor then enters the catalyst bed inside the reactor for dehydration reaction.

[0009] By adopting the above technical solution, the methanol vapor generated by vaporization in the methanol tower is heated by a heat exchanger and then transported to heat exchange tube three inside the reactor. Since the dehydration reaction occurring in the reactor is an exothermic reaction, the heat generated by the reaction is stored in the reactor. After passing through heat exchange tube three, the methanol vapor can exchange heat with the air inside the reactor, thereby further increasing the temperature of the unreacted methanol vapor at the front end. By setting up heat exchange tube three to prolong the time that the methanol vapor stays in the reactor and exchanges heat with the internal air, there is no need to install a heating device inside the reactor, further saving energy. It also helps to reduce the power consumption of reboiler one and preheater in the methanol tower.

[0010] Optionally, in step S2, when methanol vapor passes through the heat exchanger, some of the methanol vapor enters the heat exchange tube four at the top of the heat exchanger. The end of the heat exchange tube four passes through the catalyst bed of the reactor and is connected to the methanol vapor inlet of the reactor. The methanol vapor through the heat exchange tube four absorbs the heat of the catalyst bed to regulate the temperature of the catalyst bed.

[0011] By adopting the above technical solution, when methanol vapor passes through the heat exchanger, a portion of the methanol vapor can travel along heat exchange tube 4 through the catalyst bed of the reactor. This portion of methanol vapor undergoes a shorter heat exchange time with heat exchange tube 1, and its temperature is lower than the temperature inside the reactor; this is called low-temperature methanol vapor. After entering the reactor, the low-temperature methanol vapor exchanges heat with the catalyst bed, carrying away heat from the catalyst bed and lowering its temperature. This allows the temperature of the catalyst bed to be controlled within a suitable range for the dehydration reaction. The heat exchange between methanol vapor and the catalyst bed eliminates the need for a separate condenser to cool the catalyst bed, also reducing energy consumption.

[0012] Secondly, the apparatus provided in this application for the above-mentioned dimethyl ether production method adopts the following technical solution: An apparatus includes a reactor tower, the interior of which is divided by a baffle to form a heat exchange chamber and a reaction chamber, and a heat exchange tube is coiled inside the heat exchange chamber; one end of the heat exchange tube passes through the reactor tower and is connected to a heat exchanger, and the other end of the heat exchange tube passes through the reactor tower and is connected to the reaction chamber. The catalyst bed is disposed inside the reaction chamber, and the heat exchange tube three is connected to the reaction chamber below the catalyst bed; the reaction chamber is also connected to a conveying pipe for conveying high-temperature reaction gas, the conveying pipe is located above the catalyst bed, and the end of the conveying pipe away from the reaction chamber is connected to the heat exchange tube one of the heat exchanger. The heat exchange tube four is disposed inside the catalyst bed. One end of the heat exchange tube four passes through the reactor tower and is connected to the top of the heat exchanger. The other end of the heat exchange tube four passes through the reactor tower and is connected to the end of the heat exchange tube three near the reaction chamber.

[0013] By adopting the above technical solution, and by setting heat exchange tube three coiled inside the heat exchange chamber, the residence time of unreacted methanol vapor in the heat exchange chamber can be extended, thereby improving the heat exchange effect between the methanol vapor and the internal space of the reactor. After the methanol vapor is heated, it enters the reaction chamber and undergoes a dehydration reaction with the catalyst bed. The generated high-temperature reaction gas can be transported from the reaction chamber to heat exchange tube one through a conveying pipe, so as to facilitate heat exchange between the high-temperature reaction gas and the methanol vapor in the heat exchanger. In addition, heat exchange tube four passes through the catalyst bed, which allows the low-temperature methanol vapor to absorb heat through the catalyst bed, thereby reducing the temperature of the catalyst bed.

[0014] Optionally, the catalyst bed includes multiple annular cylinders disposed in the reaction chamber, all annular cylinders being nested sequentially from the inside out, adjacent annular cylinders being interconnected, and the outermost annular cylinder being fixed to the inner peripheral wall of the reaction chamber; each annular cylinder is filled with catalyst, the bottom of the annular cylinder is provided with a gas inlet, and the top of the annular cylinder is provided with a gas outlet; a gas filter for intercepting catalyst is installed at one end of the delivery pipe near the reactor.

[0015] By adopting the above technical solution, multiple annular cylinders are set up, each filled with a catalyst, so that each annular cylinder can serve as a site for the dehydration reaction of methanol vapor. A storage space is formed between the upper surface of all annular cylinders and the baffle. The high-temperature reaction gas generated by the reaction enters the storage space and can be discharged to the heat exchange tube one through the conveying pipe. The setting of the gas filter can reduce the interception of catalyst powder carried out by the high-temperature reaction gas and reduce the possibility of catalyst mixing into the subsequent process.

[0016] Optionally, each of the annular cylinders is provided with multiple baffles inside, and a reaction zone or a heat dissipation zone is formed between every two adjacent baffles. All reaction zones and heat dissipation zones are staggered around the central axis of the annular cylinder; the catalyst is disposed inside the reaction zone. The heat dissipation area extends through both the inner and outer sides of the annular cylinder, and the heat dissipation areas of adjacent annular cylinders are interconnected. The heat exchange tube four includes a first tube section connected to the heat exchanger and a second tube section connected to the heat exchange tube three. The end of the first tube section away from the heat exchanger is connected to one of the heat dissipation areas of the outermost annular cylinder, and the end of the second tube section away from the heat exchange tube three is connected to another heat dissipation area of ​​the outermost annular cylinder.

[0017] By adopting the above technical solution, the interior of the annular cylinder is divided into multiple heat dissipation areas and multiple reaction areas by setting up baffles. Each heat dissipation area is interconnected. After the low-temperature methanol vapor enters the heat dissipation area through the first pipe section, it can fully contact the outer wall of the reaction area to remove the temperature inside the reaction area, so that the temperature around the catalyst is kept within a suitable range for the catalytic reaction to proceed.

[0018] Optionally, adjacent annular cylinders are rotatably connected; a telescopic component is connected between every two adjacent annular cylinders, the telescopic component is located at the bottom of the annular cylinder, the fixed end of the telescopic component is hinged to one of the annular cylinders, and the movable end of the telescopic component is hinged to another adjacent annular cylinder; the telescopic direction of the telescopic component is normally set at an angle to the radial direction of the annular cylinder.

[0019] By adopting the above technical solution, by connecting adjacent annular cylinders to each other by rotation, and by setting telescopic components to adjust the angle of the heat dissipation area between adjacent annular cylinders, the contact area between low-temperature methanol vapor and the outer wall of the reaction area when it enters the heat dissipation area can be changed, thereby changing the temperature control effect of low-temperature methanol vapor in the catalyst bed, which is more conducive to keeping the temperature around the catalyst within a suitable range for the catalytic reaction to proceed.

[0020] Optionally, each of the partitions is provided with an integrally formed extension cylinder, which has an internal hollow structure. One end of the extension cylinder extends to the heat dissipation area, and the end of the extension cylinder near the partition is connected to the reaction area.

[0021] By adopting the above technical solution and setting an extension cylinder to extend it locally into the heat dissipation area, the contact area between the low-temperature methanol vapor and the outer wall of the reaction area can be further increased, thereby further improving the cooling effect of the low-temperature methanol vapor on the catalyst bed.

[0022] Optionally, the partition is made of aluminum alloy.

[0023] By adopting the above technical solution and using aluminum alloy material to make the partition, when low-temperature methanol vapor enters the heat dissipation area, it can more quickly remove the heat inside the reaction area when it comes into contact with the partition with good thermal conductivity, which makes it easier to adjust the temperature of the catalyst bed.

[0024] Optionally, a storage space for storing high-temperature reaction gas is formed between the catalyst bed and the baffle; a heat exchange cylinder is embedded at the bottom of the baffle, and the top of the heat exchange cylinder extends to the top of the heat exchange chamber; the heat exchange cylinder has an internal hollow structure, and the bottom of the heat exchange cylinder is connected to the storage space.

[0025] By adopting the above technical solution, and by setting up a heat exchange cylinder that extends locally into the heat exchange chamber, the area at the junction of the storage space and the heat exchange chamber can be increased. The heat of the high-temperature reaction gas generated by the methanol vapor reaction can be conducted to the heat exchange chamber through the baffle, so that the unreacted methanol vapor can enter the heat exchange tube 1 and exchange heat with the air inside the heat exchange chamber, thereby raising the temperature.

[0026] In summary, this application includes at least one of the following beneficial technical effects: 1. By sending the high-temperature reaction gas generated by the reaction back to the heat exchanger via heat exchange tube 1 and back to the preheater via heat exchange tube 2, the temperature of the unreacted methanol vapor at the front end can be increased, thereby reducing the power consumption of reboiler 1 and preheater in the methanol tower, thus saving energy. 2. By setting up heat exchange tube three to extend the residence time of methanol vapor in the reactor, the time for heat exchange between methanol vapor and the air inside the reactor can be extended, making it easier for methanol vapor to absorb heat and heat up before entering the reaction chamber for dehydration reaction; 3. By setting heat exchange tube four, some methanol vapor can pass through the catalyst bed along heat exchange tube four. The temperature of this methanol vapor is lower than the temperature inside the reactor. After the low-temperature methanol vapor enters the reactor, it can reduce the temperature of the catalyst bed, so as to control the temperature of the catalyst bed within a suitable range for the dehydration reaction to proceed. Attached Figure Description

[0027] Figure 1 This is a schematic flow diagram of the dimethyl ether production method in Example 1; Figure 2 This is a cross-sectional view of the reactor tower in Example 2; Figure 3 This is a schematic diagram of the overall structure of the catalyst bed in Example 2; Figure 4 This is a schematic diagram of the bottom structure of the catalyst bed in Example 2.

[0028] Explanation of reference numerals in the attached drawings: 1. Methanol storage tank; 2. Preheater; 21. Heat exchanger tube 2; 3. Methanol tower; 31. Reboiler 1; 4. Heat exchanger; 41. Heat exchanger tube 1; 42. Heat exchanger tube 4; 421. First tube section; 422. Second tube section; 5. Reactor; 51. Heat exchanger tube 3; 52. Catalyst bed; 53. Annular cylinder; 531. Baffle; 532. Extension cylinder; 54. Heat dissipation area; 55. Reaction zone Domain; 551, Gas Inlet; 952, Gas Outlet; 56, Expansion Joint; 6, Dimethyl Ether Tower; 61, Condenser; 62, Reboiler II; 7, Alcohol Washing Tower; 8, Flash Stripping Tower; 81, Reboiler III; 9, Reactor Tower Body; 91, Heat Exchange Chamber; 92, Reaction Chamber; 921, Storage Space; 93, Baffle; 931, Heat Exchange Cylinder; 932, Heat Exchange Tank; 94, Delivery Pipe; 95, Gas Filter. Detailed Implementation

[0029] The following is in conjunction with the appendix Figure 1-4 This application will be described in further detail.

[0030] Example 1 This application discloses a method for producing dimethyl ether.

[0031] Reference Figure 1 A method for producing dimethyl ether specifically includes the following steps: Step S1, raw material methanol vaporization; purchased methanol is first stored in methanol storage tank 1. During production, the methanol in methanol storage tank 1 is preheated by preheater 2 and then sent to methanol tower 3. The reboiler 31 of the bottom of methanol tower 3 heats and vaporizes the methanol raw material to form methanol vapor. In addition, there is high temperature bottom liquid remaining in the bottom of methanol tower 3.

[0032] Step S2, methanol dehydration to dimethyl ether; methanol vapor discharged from methanol tower 3 is sent to reactor 5 after passing through heat exchanger 4, where a dehydration reaction occurs to produce dimethyl ether; since the dehydration reaction is exothermic, the heat generated after the reaction is stored in reactor 5, causing the temperature inside reactor 5 to rise; when the unreacted methanol vapor enters reactor 5, it first enters heat exchange tube 3 51 inside reactor 5. At this time, the temperature of methanol vapor is lower than the temperature inside reactor 5. Methanol vapor exchanges heat with the air inside reactor 5 in heat exchange tube 3 51, and after being superheated, it enters the catalyst bed 52 inside reactor 5 for dehydration reaction.

[0033] After the methanol vapor undergoes a dehydration reaction, it forms a high-temperature reaction gas. This high-temperature reaction gas leaves reactor 5 and is first transported to heat exchange tube 41 inside heat exchanger 4. The temperature of the high-temperature reaction gas is higher than that of the methanol vapor inside heat exchanger 4. The high-temperature reaction gas exchanges heat with the methanol vapor, raising its temperature. This reduces the heating power required by reboiler 31 for the methanol vapor, resulting in energy savings. Then, the heat-exchanged high-temperature reaction gas is transported to heat exchange tube 21 inside preheater 2, where it exchanges heat with the methanol vapor to preheat it. Finally, the high-temperature reaction gas is transported to the dimethyl ether tower 6.

[0034] Furthermore, when the methanol vapor generated from the methanol tower 3 enters the heat exchanger 4, some of the methanol vapor does not undergo sufficient heat exchange with the heat exchange tube 51 before entering the heat exchange tube 42 at the top of the heat exchanger 4. The end of the heat exchange tube 42 away from the heat exchanger 4 passes through the catalyst bed 52 of the reactor 5 and is ultimately connected to the methanol vapor inlet of the reactor 5. Since the methanol vapor entering the heat exchange tube 42 is at a low temperature, it is called low-temperature methanol vapor. As the low-temperature methanol vapor flows through the catalyst bed 52 inside the heat exchange tube 42, it can absorb heat from the catalyst bed 52 to regulate the temperature of the catalyst bed 52 and keep it within a suitable range for the catalytic reaction to proceed.

[0035] Step S3, dimethyl ether separation and distillation; the high-temperature reaction gas produced by the dehydration reaction includes the dimethyl ether generated in the reaction, the water generated in the reaction, the unreacted methanol, and a small amount of non-condensable gas. The high-temperature reaction gas enters the dimethyl ether tower 6 and is heated by the reboiler 62 in the bottom of the dimethyl ether tower 6. The dimethyl ether vapor and a small amount of non-condensable gas rise along the tower and enter the condenser 61 at the top of the tower for condensation. The dimethyl ether formed by condensation is collected as a product. The high-temperature bottom liquid of the dimethyl ether tower 6 is discharged to the flash vapor stripper 8 for methanol recovery, while the methanol collected from the middle of the dimethyl ether tower 6 is transported back to the methanol storage tank 1.

[0036] Step S4, tail gas treatment; dimethyl ether vapor and non-condensable gases rise along the tower and are discharged to the alcohol washing tower 7 through the condenser 61. The alcohol washing tower 7 uses methanol to wash and recover dimethyl ether; the tail gas produced by the alcohol washing tower 7 is discharged outside the tower, and the alcohol washing liquid that has absorbed dimethyl ether is sent back to the dimethyl ether tower 6 for treatment. Step S5, methanol recovery; the high-temperature bottom liquid discharged from the bottom of methanol tower 3 and dimethyl ether tower 6 is sent to flash stripper 8. The reboiler 3 81 of flash stripper 8 heats the high-temperature bottom liquid. The methanol contained in the high-temperature bottom liquid rises along the tower through flash vaporization, is condensed by condenser 61, and is then sent back to methanol storage tank 1.

[0037] The implementation principle of a dimethyl ether production method according to an embodiment of this application is as follows: In the production process of dimethyl ether, the high-temperature reaction gas generated is used to heat the methanol vapor inside heat exchanger 4 and the methanol inside preheater 2. This reduces the power consumption of reboiler 31 in methanol tower 3 and methanol preheater 2, thus saving energy. Furthermore, the heat generated by the dehydration reaction is used to heat the methanol vapor entering reactor 5. The residence time of the methanol vapor in reactor 5 is extended through heat exchange tube 3 51, increasing the temperature of the entering methanol vapor. By allowing the low-temperature methanol vapor to pass through heat exchange tube 42, the temperature of the catalyst bed 52 is reduced. This allows for self-regulation of the reactor 5 temperature without the need for additional heating or cooling devices, further saving energy and aligning with the energy-saving and environmentally friendly principles of modern construction.

[0038] Example 2 This application also discloses an apparatus used in the dimethyl ether production method disclosed in Example 1, which is essentially the reactor 5 mentioned in step 2.

[0039] Reference Figure 2 An apparatus includes a reactor tower 9, inside which a horizontally arranged baffle 93 is provided. In this embodiment, the baffle 93 is made of aluminum alloy material, which gives it good thermal conductivity. The reactor tower 9 is divided by the baffle 93 to form a heat exchange chamber 91 and a reaction chamber 92, wherein the heat exchange chamber 91 is located above the reaction chamber 92.

[0040] Heat exchange tube 3 51 is coiled inside heat exchange chamber 91. One end of heat exchange tube 3 51 passes through reactor tower 9 and is connected to heat exchanger 4. The other end of heat exchange tube 3 51 passes through outside reactor tower 9 and is connected to reaction chamber 92. Catalyst bed 52 is set inside reaction chamber 92. The connection between heat exchange tube 3 51 and reaction chamber 92 is located below catalyst bed 52.

[0041] The catalyst bed 52 and the baffle 93 are spaced apart to form a storage space 921. After methanol vapor enters the catalyst bed 52, it undergoes a dehydration reaction and the generated high-temperature reaction gas can be stored in the storage space 921. Since the temperature of the high-temperature reaction gas is high, the heat of the high-temperature reaction gas can be transferred to the heat exchange chamber 91 through the baffle 93, so that the temperature inside the heat exchange chamber 91 is close to the temperature of the high-temperature reaction gas. When methanol vapor enters the heat exchange tube 51, it can exchange heat with the air inside the heat exchange chamber 91, thereby increasing the temperature of the methanol vapor.

[0042] In addition, multiple heat exchange cylinders 931 are embedded in the bottom of the baffle 93, and all heat exchange cylinders 931 are evenly distributed on the baffle 93. Each heat exchange cylinder 931 extends upward into the interior of the heat exchange chamber 91, and each heat exchange cylinder 931 is partially located outside the heat exchange tube 51. The heat exchange cylinder 931 has a hollow internal structure, and the bottom of the heat exchange cylinder 931 is provided with a heat exchange groove 932 that communicates with the interior. The heat exchange groove 932 is connected to the storage space 921. The arrangement of the heat exchange cylinder 931 can increase the contact area between the reaction chamber 92 and the heat exchange chamber 91, so as to facilitate the rapid transfer of heat from the high-temperature reaction gas in the storage space 921 to the heat exchange chamber 91.

[0043] A conveying pipe 94 is connected to the outside of the storage space 921. The conveying pipe 94 is used to convey the high-temperature reaction gas generated after the methanol vapor dehydration reaction. The end of the conveying pipe 94 away from the storage space 921 is connected to the heat exchange tube 41 of the heat exchanger 4. After the high-temperature reaction gas is conveyed to the heat exchange tube 41 through the conveying pipe 94, it can exchange heat with the unreacted methanol vapor inside the heat exchanger 4, thereby increasing the temperature of the methanol vapor.

[0044] The catalyst bed 52 includes a plurality of annular cylinders 53 disposed in the reaction chamber 92, all annular cylinders 53 being nested sequentially from the inside to the outside; the inner diameter of the outer annular cylinder 53 in two adjacent annular cylinders 53 is set to be equal to the outer diameter of the inner annular cylinder 53, and every two adjacent annular cylinders 53 are rotatably connected to each other; in addition, the outermost annular cylinder 53 is fixed to the inner peripheral wall of the reaction chamber 92. The specific number of annular cylinders 53 can be selectively set according to actual needs. In this embodiment, the number of annular cylinders 53 is set to three, but in other embodiments, the number of annular cylinders 53 can also be four, five or six.

[0045] Reference Figure 3 Each annular cylinder 53 has multiple baffles 531 inside, and the extension direction of each baffle 531 is in the same direction as the axis of the annular cylinder 53. All baffles 531 are arranged equidistantly around the central axis of the annular cylinder 53. The interior of the annular cylinder 53 is divided into multiple reaction zones 55 and multiple heat dissipation zones 54 by the baffles 531. All reaction zones 55 and heat dissipation zones 54 are arranged alternately around the central axis of the annular cylinder 53. Each reaction zone 55 is filled with a catalyst, which is in powder form.

[0046] Back Figure 2Each reaction zone 55 has a gas inlet 551 at the bottom for methanol vapor to enter, and a gas outlet 952 at the top for methanol vapor to enter. In order to reduce the situation where methanol vapor carries out the catalyst inside the reaction zone 55 when it enters the reaction zone 55, a gas filter 95 for blocking the catalyst is installed at one end of the delivery pipe 94 near the storage space 921.

[0047] Back Figure 3 Each heat dissipation area 54 extends through both the inner and outer sides of the annular cylinder 53, while the top and top of the heat dissipation area 54 are sealed structures; adjacent heat dissipation areas 54 of adjacent annular cylinders 53 are interconnected. (See also...) Figure 4 A telescopic component 56 is connected between each two adjacent annular cylinders 53. The telescopic component 56 is used to drive the adjacent annular cylinders 53 to rotate relative to each other. The telescopic component 56 is located at the bottom of the annular cylinder 53. The fixed end of the telescopic component 56 is hinged to the outer annular cylinder 53 of the two adjacent annular cylinders 53, and the movable end of the telescopic component 56 is hinged to the inner annular cylinder 53 of the two adjacent annular cylinders 53. The telescopic direction of the telescopic component 56 is normally set at an angle to the radial direction of the annular cylinder 53.

[0048] The telescopic component 56 is configured as a hydraulic cylinder. The piston rod of the hydraulic cylinder is normally in the extended state, at which time the heat dissipation areas 54 of each annular cylinder 53 are arranged opposite each other. When the piston rod of the hydraulic cylinder retracts inward, the hydraulic cylinder can drive the annular cylinder 53 to rotate relative to the adjacent annular cylinder 53, so as to change the area of ​​the outer wall of the reaction area 55 within the heat dissipation area 54.

[0049] Heat exchange tube 42 is disposed inside reaction chamber 92. In this embodiment, heat exchange tube 42 includes a first tube segment 421 and a second tube segment 422. One end of the first tube segment 421 is connected to one of the heat dissipation areas 54 of the outermost annular cylinder 53, and the end of the first tube segment 421 away from the annular cylinder 53 passes through the reactor tower 9 and is connected to the top of the heat exchanger 4. One end of the second tube segment 422 is connected to another heat dissipation area 54 of the outermost annular cylinder 53, and the end of the second tube segment 422 away from the annular cylinder 53 passes through the end connected to the reactor tower 9 and to the end of heat exchange tube 421 near the reaction chamber 92.

[0050] Back Figure 3In this embodiment, the partition 531 is also made of aluminum alloy, which gives the partition 531 good thermal conductivity. When the low-temperature methanol vapor enters the heat dissipation area 54 through the first pipe section 421 at the top of the heat exchanger 4, it can fully contact the outer wall of the reaction area 55. The temperature of the low-temperature methanol vapor increases through the heat exchange chamber 91, while the temperature inside the reaction area 55 decreases. This helps to adjust the temperature of the catalyst bed 52 so that it is kept within a suitable range for the catalytic reaction to proceed.

[0051] In addition, each partition 531 is provided with multiple integrally formed extension cylinders 532, and the end of each extension cylinder 532 away from the partition 531 extends into the heat dissipation area 54; wherein, the extension cylinder 532 has an internal hollow structure, and the end of the extension cylinder 532 near the reaction area 55 is also provided with a connecting groove that communicates with the interior. The connecting groove is connected to the reaction area 55, and the catalyst is also placed in the connecting groove. The extension cylinder 532 can further increase the contact area between the low-temperature methanol vapor and the outer wall of the reaction area 55, so as to improve the efficiency of the low-temperature methanol vapor absorbing the heat of the catalyst bed 52 per unit time.

[0052] The implementation principle of a device according to an embodiment of this application is as follows: The reactor tower 9 of this application serves as the site for the methanol vapor dehydration reaction. By extending the time for methanol vapor to enter the reaction chamber 92 through the heat exchange tube 51 coiled around the heat exchange chamber 91, the methanol vapor can absorb heat and rise in temperature, so that the methanol vapor can reach the temperature at which the catalytic reaction occurs. In addition, low-temperature methanol vapor is transported into the heat dissipation zone 54 through the heat exchange tube 42 to absorb the temperature around the catalyst, and the operation of the telescopic component 56 is controlled to adaptively adjust the temperature of the heat dissipation zone 54, so that the temperature around the catalyst can be maintained within a suitable range for the catalytic reaction to proceed smoothly.

[0053] The above are preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made to the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. An apparatus for use in a dimethyl ether production method, characterized in that: The system includes a methanol storage tank (1), a preheater (2), a methanol tower (3), a heat exchanger (4), a reactor (5), a dimethyl ether tower (6), an alcohol washing tower (7), and a flash stripper (8). The methanol feedstock is stored in the methanol storage tank (1). During production, the methanol feedstock is preheated by the preheater (2) and then fed into the methanol tower (3). The reboiler (31) at the bottom of the methanol tower (3) heats and vaporizes the methanol feedstock to form methanol vapor. The methanol vapor discharged from the methanol tower (3) is sent to the reactor (8) after passing through the heat exchanger (4). 5) A dehydration reaction occurs in reactor (5) to generate dimethyl ether; the high-temperature reaction gas generated after the reaction is sent to heat exchange tube 1 (41) inside heat exchanger (4) to exchange heat with methanol vapor, and then to heat exchange tube 2 (21) inside preheater (2) to exchange heat with methanol feedstock, and then sent to the dimethyl ether tower (6); the high-temperature reaction gas includes dimethyl ether, methanol, water and a small amount of non-condensable gas. After the high-temperature reaction gas enters the dimethyl ether tower (6), it passes through the bottom of the dimethyl ether tower (6). The reboiler (62) is heated, and the dimethyl ether vapor and a small amount of non-condensable gas rise along the column and enter the condenser (61) at the top of the column for condensation. The dimethyl ether formed by condensation is collected as a product. The high-temperature bottom liquid of the dimethyl ether column (6) is discharged to the flash stripper (8) for methanol recovery, while the methanol collected from the middle of the dimethyl ether column (6) is transported back to the methanol storage tank (1). The dimethyl ether vapor and non-condensable gas rise along the column and are discharged through the condenser (61) to the alcohol washing column (7). Methanol is used to wash and recover dimethyl ether; the tail gas produced by the alcohol washing tower (7) is discharged outside the tower, and the alcohol washing liquid that has absorbed dimethyl ether is sent back to the dimethyl ether tower (6) for treatment; the high-temperature bottom liquid discharged from the bottom of the methanol tower (3) and the bottom of the dimethyl ether tower (6) is sent to the flash stripper (8), and the reboiler three (81) of the bottom of the flash stripper (8) heats the high-temperature bottom liquid. The methanol contained in the high-temperature bottom liquid rises along the tower through flash vaporization, is condensed by the condenser (61), and is then sent back to the methanol storage tank (1). The reactor (5) includes a reactor tower (9), which is divided into a heat exchange chamber (91) and a reaction chamber (92) by a baffle (93). A heat exchange tube (51) is coiled inside the heat exchange chamber (91). One end of the heat exchange tube (51) passes through the reactor tower (9) and is used to connect to the lower part of the heat exchanger (4). The heat exchange tube (41) is located at the lower part of the heat exchanger (4). The other end of the heat exchange tube (51) passes through the reactor tower (9) and is connected to the reaction chamber. (92) A catalyst bed (52) is provided inside the reaction chamber (92). The connection between the heat exchange tube three (51) and the reaction chamber (92) is located below the catalyst bed (52). When the methanol vapor in the heat exchanger (4) is sent into the reactor (5), it first enters the heat exchange tube three (51) inside the reactor (5). The heat generated by the dehydration reaction exchanges heat with the methanol vapor inside the heat exchange tube three (51). The superheated methanol vapor then enters the catalyst bed (52) inside the reactor (5) for dehydration reaction. The reaction chamber (92) is also connected to a conveying pipe (94) for conveying high-temperature reaction gas. The conveying pipe (94) is located above the catalyst bed (52). The end of the conveying pipe (94) away from the reaction chamber (92) is used to connect to the heat exchange tube (41) inside the heat exchanger (4). The high-temperature reaction gas obtained after the methanol vapor in the reaction chamber is dehydrated by the catalyst bed passes through the heat exchange tube (41) to exchange heat with the methanol vapor in the heat exchanger (4). The catalyst bed (52) includes multiple annular cylinders (53) disposed in the reaction chamber (92). All annular cylinders (53) are nested from the inside to the outside, and adjacent annular cylinders (53) are connected to each other. The outermost annular cylinder (53) is fixed to the inner circumferential wall of the reaction chamber (92). Each annular cylinder (53) is filled with catalyst. The bottom of the annular cylinder (53) is provided with a gas inlet (551), and the top of the annular cylinder (53) is provided with a gas outlet (952). A gas filter (95) for intercepting catalyst is installed at the end of the delivery pipe (94) near the reactor (5). Each of the annular cylinders (53) is provided with multiple partitions (531), and a reaction zone (55) or a heat dissipation zone (54) is formed between each pair of adjacent partitions (531). All reaction zones (55) and heat dissipation zones (54) are arranged alternately around the central axis of the annular cylinder (53). The catalyst is disposed inside the reaction zone (55), and the gas inlet (551) and the gas outlet (952) are located in the reaction zone. The heat dissipation zone (54) extends through the inner and outer sides of the annular cylinder (53), and the adjacent heat dissipation zones (54) of adjacent annular cylinders (53) are interconnected. It also includes heat exchange tube four (42), which includes a first tube section (421) connected to the top of the heat exchanger (4) and a second tube section (422) connected to the end of heat exchange tube three (51) near the reaction chamber. The end of the first tube section (421) away from the heat exchanger (4) is connected to one of the heat dissipation areas (54) of the outermost annular cylinder (53), and the end of the second tube section (422) away from the heat exchange tube three (51) is connected to another heat dissipation area (54) of the outermost annular cylinder (53). After the methanol vapor passes through the heat exchanger (4), some of the methanol vapor enters the heat exchange tube four (42) at the top of the heat exchanger (4). The other end of the heat exchange tube four (42) passes through the catalyst bed (52) of the reactor (5) and is connected to the methanol vapor inlet of the reactor (5). The methanol vapor in the heat exchange tube four (42) absorbs the heat of the catalyst bed (52) to regulate the temperature of the catalyst bed (52). The adjacent annular cylinders (53) are rotatably connected; a telescopic component (56) is connected between each pair of adjacent annular cylinders (53), the telescopic component (56) is located at the bottom of the annular cylinder (53), the fixed end of the telescopic component (56) is hinged to one of the annular cylinders (53), and the movable end of the telescopic component (56) is hinged to the other adjacent annular cylinder (53); the telescopic direction of the telescopic component (56) is normally set at an angle to the radial direction of the annular cylinder (53); Each of the partitions (531) is provided with an integrally formed extension tube (532). The extension tube (532) has an internal hollow structure. One end of the extension tube (532) extends to the heat dissipation area (54). The end of the extension tube (532) near the partition (531) is connected to the reaction area (55). A storage space (921) for storing high-temperature reaction gas is formed between the catalyst bed (52) and the baffle (93); a heat exchange cylinder (931) is embedded at the bottom of the baffle (93), and the top of the heat exchange cylinder (931) extends to the top of the heat exchange chamber (91); the heat exchange cylinder (931) has an internal hollow structure, the bottom of the heat exchange cylinder (931) is connected to the storage space (921), and the conveying pipe (94) is connected to the storage space (921).

2. The apparatus according to claim 1, characterized in that: The partition (531) is made of aluminum alloy.

Images