DMMn production equipment
By designing DMMn production equipment and utilizing formaldehyde concentrators, formaldehyde absorption towers, and reactive distillation towers, the problem of reactor blockage was solved, enabling the efficient production of high-purity DMM3~DMM6 products.
Patent Information
- Application Number
- CN202423142215.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-19
- Publication Date
- 2025-12-02
- Estimated Expiration
- 2034-12-19
AI Technical Summary
Existing DMMn production equipment is prone to reactor blockage when producing polyoxymethylene dimethyl ether, mainly because the high concentration of formaldehyde self-polymerization is difficult to remove.
A DMMn production device was designed, including a formaldehyde concentration separator, a formaldehyde absorption tower, a pre-reactor, and a reactive distillation tower. By separating and controlling the formaldehyde concentration, catalytic distillation technology is used to separate and react in different reaction sections, reducing the influence of water and avoiding formaldehyde self-polymerization.
It improved the formaldehyde conversion rate, avoided reactor blockage, obtained high-purity DMM3~DMM6 products, and enhanced the stability and efficiency of the production equipment.
Smart Images
Figure CN223615862U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of chemical production equipment technology, and in particular to a DMMn production equipment. Background Technology
[0002] Polyoxymethylene dimethyl ether, abbreviated as DMMn, is a new type of clean fuel additive with advantages such as reducing combustion smoke generation, improving combustion performance, and reducing exhaust emissions, and has broad application prospects in the energy and environmental protection fields.
[0003] Among them, polyoxymethylene dimethyl ether (DMM3~DMM6) with a degree of polymerization of 3~6 has similar physical properties to diesel fuel, and has a high oxygen content (mass fraction of 47%~50%) and a high cetane number (greater than 78). It can improve the combustion state of diesel fuel in the engine and effectively reduce the emission of particulate matter in the exhaust gas. At the same time, no modifications are required to the diesel engine, so it is recognized as a relatively ideal diesel fuel additive.
[0004] Formaldehyde is the main raw material for the synthesis of DMMn. The existing reaction system for synthesizing DMMn is greatly affected by water. Increasing the formaldehyde concentration is beneficial to reducing the influence of water on the reaction system and obtaining DMMn products with higher purity (n=3~6). However, high concentrations of formaldehyde are prone to self-polymerization, and the generated paraformaldehyde adheres to the reactor and is difficult to remove, which can easily cause serious blockage of the reactor. Utility Model Content
[0005] The main purpose of this invention is to propose a DMMn production equipment that aims to solve the problem of reactor blockage that easily occurs in existing DMMn production equipment when producing polyoxymethylene dimethyl ether.
[0006] To achieve the above objectives, the present invention provides a DMMn production equipment comprising:
[0007] A formaldehyde concentration separator has a formaldehyde solution inlet in the middle, a flash vapor discharge pipe in the upper part, and a concentrated formaldehyde solution discharge pipe in the lower part.
[0008] The formaldehyde absorption tower has a water inlet at the top, an air inlet connected to the flash vapor discharge pipe at the bottom, and a dilute formaldehyde solution discharge pipe at the bottom.
[0009] The pre-reactor has a dilute formaldehyde inlet connected to the dilute formaldehyde solution discharge pipe and a methanol inlet, and a pre-reacted material discharge pipe is provided at the bottom of the pre-reactor.
[0010] A reactive distillation column includes a column body, an upper reaction section and a lower reaction section located below the upper reaction section, a water collection pipe located on the column body between the upper and lower reaction sections, a pre-reactant inlet on the column body corresponding to the upper reaction section and connected to a pre-reactant discharge pipe, and a concentrated formaldehyde inlet on the column body corresponding to the lower reaction section and connected to a concentrated formaldehyde solution discharge pipe.
[0011] In one embodiment, the DMMn production equipment further includes a light-light distillation column;
[0012] The reactive distillation column further includes a first condensation section, which includes a first condenser, a first reflux tank, a first reflux pump, and a first reflux pipe connected in sequence. The inlet of the first condenser is connected to the vapor outlet at the top of the column through a pipe, and the outlet of the first reflux pipe is connected to the first liquid return port at the top of the column.
[0013] The first reflux pipe is branched off and connected to the feed inlet of the light component removal distillation column, and the bottom of the light component removal distillation column is provided with a material reflux pipe connected to the first reflux tank.
[0014] In one embodiment, a third light component collection pipe is provided at the top of the light component removal distillation column.
[0015] In one embodiment, the first reflux pipe is further branched with a second reflux port connected to the lower part of the tower body, and the second reflux port is correspondingly provided with the lower reaction section.
[0016] In one embodiment, a crude DMMn product collection pipe is provided at the bottom of the column; the DMMn production equipment further includes a reactive distillation unit, which includes a first hydrogenation reactor and a separation distillation column;
[0017] The first hydrogenation reactor is provided with a reaction material inlet at the top, which is connected to the crude DMMn product outlet pipe. The first hydrogenation reactor is provided with a first hydrogen inlet at the top, a copper-based catalyst in the middle, and a first hydrogenation reaction material outlet pipe at the bottom.
[0018] The feed inlet of the separation distillation column is connected to the discharge pipe of the first hydrogenation reaction material.
[0019] In one embodiment, a first cooler and a first gas-liquid separator are sequentially arranged between the first hydrogenation reaction material discharge pipe and the feed inlet of the separation distillation column. The gas outlet of the first gas-liquid separator is connected to the first hydrogen inlet through a first connecting pipe. A first compressor is installed on the first connecting pipe. The liquid outlet of the first gas-liquid separator is connected to the feed inlet of the separation distillation column through a pipe.
[0020] In one embodiment, the separation distillation column is provided with a second light component outflow pipe at the top, a DMM2 side-stream outflow pipe at the bottom, and a DMMn product outflow pipe at the bottom.
[0021] In one embodiment, the discharge end of the second light component collection pipe is connected to the concentrated formaldehyde inlet.
[0022] In one embodiment, the reactive distillation apparatus further includes a converter connected to the side line outlet pipe of the DMM2, and a second hydrogenation reactor connected to the outlet end of the converter. The upper part of the second hydrogenation reactor is provided with a second hydrogen inlet, and the bottom part is provided with a second hydrogenation reaction material discharge pipe connected to the feed inlet of the separation distillation column.
[0023] In one embodiment, a second cooler and a second gas-liquid separator are sequentially arranged between the second hydrogenation reaction material discharge pipe and the feed inlet of the separation distillation column. The gas outlet of the second gas-liquid separator is connected to the second hydrogen inlet through a second connecting pipe. A second compressor is installed on the second connecting pipe. The liquid outlet of the second gas-liquid separator is connected to the feed inlet of the separation distillation column through a pipe.
[0024] In the technical solution of this utility model, a 50-55 wt% formaldehyde aqueous solution is sent into a formaldehyde concentrator and separator, the concentrate is a 70-80 wt% concentrated formaldehyde solution, and the resulting flash vapor is sent to a formaldehyde absorption tower.
[0025] Flash vapor and water (temperature can be 25℃) are fed into the formaldehyde absorption tower. After the flash vapor and water are mixed, a dilute formaldehyde solution is sent to the pre-reactor.
[0026] A 15-25 wt% dilute formaldehyde solution and a methanol concentration of 95 wt% or higher are fed into a pre-reactor, with the temperature controlled at 50-80℃. Some of the methanol and formaldehyde react to form methylal. The pre-reacted material is then sent to the upper reaction section of the reactive distillation column, while a 70-80 wt% concentrated formaldehyde solution is sent to the lower reaction section of the reactive distillation column.
[0027] Both the upper and lower reaction sections of the reactive distillation column are filled with solid acid catalysts. Under the action of catalytic distillation, the materials in the upper reaction section react to generate methyl acetal, DMM2, and DMM3.
[0028] Since the boiling point of water is lower than that of DMM2~DMM6 but higher than that of methanol, formaldehyde and methylal, most of the water accumulates between the upper and lower reaction sections. During reactive distillation, the water between the upper and lower reaction sections is extracted, which not only helps the reaction equilibrium to shift towards the direction of water consumption, but also helps to reduce the water content in the material entering the lower reaction section from the upper reaction section.
[0029] Under the action of catalytic distillation, the materials in the lower reaction section, including the materials leaving the upper reaction section and entering the lower reaction section, as well as the input concentrated formaldehyde solution with a concentration of 70~80wt%, have a low water content in the materials leaving the upper reaction section and entering the lower reaction section, and the input concentrated formaldehyde solution also has a low water content. Moreover, the boiling point of water is lower than that of DMM2~DMM6, so the water is basically concentrated between the upper and lower reaction sections. By extracting the water between the upper and lower reaction sections, the reaction in the lower reaction section is almost unaffected by water, and the formaldehyde has a high conversion rate. At the same time, it can further generate DMM3~DMM6 with a higher degree of polymerization.
[0030] In the lower reaction section, formaldehyde conversion is relatively high. Crude products DMM2-DMM6 are collected from the bottom of the reactive distillation column and further reactively distilled to obtain higher purity DMM3-DMM6 products. The azeotrope of methyl acetal and methanol is collected from the top of the reactive distillation column.
[0031] The DMMn production equipment provided by this utility model, through the combined use of a formaldehyde concentrator, a formaldehyde absorption tower, a pre-reactor, and a reactive distillation tower, helps to reduce the impact of water on the entire reaction system, improve the formaldehyde conversion rate, and avoid the self-polymerization of formaldehyde. Attached Figure Description
[0032] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.
[0033] Figure 1 A schematic diagram of an embodiment of the DMMn production equipment provided by this utility model.
[0034] Explanation of icon numbers:
[0035] 1. Formaldehyde Concentrator and Separator; 11. Formaldehyde Solution Inlet; 12. Flash Vapor Exhaust Pipe; 13. Concentrated Formaldehyde Solution Exhaust Pipe; 2. Formaldehyde Absorption Tower; 21. Water Inlet; 22. Gas Inlet; 23. Dilute Formaldehyde Solution Exhaust Pipe; 3. Pre-reactor; 31. Dilute Formaldehyde Inlet; 32. Methanol Inlet; 33. Pre-reactant Discharge Pipe; 4. Reactive Distillation Tower; 41. First Condenser; 42. First Reflux Tank; 43. First Reflux Pump; 44. First Reflux Pipe; 45. First Light Component Outlet Pipe; 46. First Return Liquid Inlet; 47. Second Return Liquid Inlet; 49. Upper Reaction Section; 410. Lower Reaction Section; 412. Water Outlet Pipe; 413. 5. DMMn crude product outlet pipe; 6. Light component removal distillation column; 7. Third light component outlet pipe; 8. First hydrogenation reactor; 9. First hydrogen inlet; 10. Reactant inlet; 11. First hydrogenation reactant outlet pipe; 12. First hydrogenation reactant outlet pipe; 13. First cooler; 14. First gas-liquid separator; 15. Separation distillation column; 16. Second light component outlet pipe; 17. DMM2 side stream outlet pipe; 18. DMMn product outlet pipe; 19. Converter; 20. Second hydrogenation reactor; 10. Second hydrogen inlet; 11. Reforming reactant inlet; 12. Second hydrogenation reactant outlet pipe; 13. Second cooler; 14. Second gas-liquid separator.
[0036] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation
[0037] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present utility model.
[0038] It should be noted that if the embodiments of this utility model involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.
[0039] Furthermore, if the embodiments of this utility model involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.
[0040] Formaldehyde is the main raw material for the synthesis of DMMn. The reaction system for synthesizing DMMn is greatly affected by water. Increasing the formaldehyde concentration is beneficial to reducing the influence of water on the reaction system and obtaining a higher yield of DMMn (n=3~6). However, high concentrations of formaldehyde are prone to self-polymerization, and the generated paraformaldehyde adheres to the reactor and is difficult to remove, which can easily cause serious blockage of the reactor.
[0041] In view of this, the present invention proposes a DMMn production equipment to solve the problem of reactor blockage that is easily caused by existing DMMn production equipment when producing polyoxymethylene dimethyl ether.
[0042] Please see Figure 1In one embodiment of this utility model, the DMMn production equipment includes a formaldehyde concentrator 1, a formaldehyde absorption tower 2, a pre-reactor 3, and a reactive distillation tower 4. The formaldehyde concentrator 1 has a formaldehyde solution inlet 11 in its middle section, a flash vapor discharge pipe 12 at its upper part, and a concentrated formaldehyde solution discharge pipe 13 at its lower part. The formaldehyde absorption tower 2 has a water inlet 21 at its upper part, an air inlet 22 connected to the flash vapor discharge pipe 12 at its lower part, and a dilute formaldehyde solution discharge pipe 23 at its bottom. The pre-reactor 3 has a dilute formaldehyde inlet connected to the dilute formaldehyde solution discharge pipe 23. 31, and methanol inlet 32, the bottom of the pre-reactor 3 is provided with a pre-reacted material discharge pipe 33; the reactive distillation column 4 includes a column body, the column body is provided with an upper reaction section 49 and a lower reaction section 410 located below the upper reaction section 49, a water collection pipe 412 is provided on the column body located between the upper reaction section 49 and the lower reaction section 410; a pre-reacted material inlet is provided on the column body corresponding to the upper reaction section 49, the pre-reacted material inlet is connected to the pre-reacted material discharge pipe 33; a concentrated formaldehyde inlet is provided on the column body corresponding to the lower reaction section 410, the concentrated formaldehyde inlet is connected to the concentrated formaldehyde solution discharge pipe 13.
[0043] In this invention, a 50-55 wt% formaldehyde aqueous solution enters the formaldehyde concentrator 1 through the formaldehyde solution inlet 11. After being pressurized (0.3 MPa) and vaporized, it undergoes vacuum (-90 kPa) flash evaporation, resulting in a 70-80 wt% concentrated formaldehyde solution. The resulting flash vapor is discharged through the flash vapor outlet pipe 12 and enters the formaldehyde absorption tower 2 through the inlet 22. Room temperature water (25°C) enters the formaldehyde absorption tower 2 through the water inlet 21 to form a 15-25 wt% dilute formaldehyde solution.
[0044] A 15-25 wt% dilute formaldehyde solution is discharged from the dilute formaldehyde solution discharge pipe 23 and enters the pre-reactor 3 through the dilute formaldehyde inlet 31. Methanol with a concentration of 95 wt% or higher enters the pre-reactor 3 through the methanol inlet 32. In the pre-reactor 3, the temperature is controlled at 50-80℃. Some methanol and formaldehyde react to form methylal. The pre-reacted material (8-10 wt% formaldehyde, 40-50 wt% water, 25-30 wt% methanol, and 5-10 wt% methylal) is sent to the upper reaction section 49 of the reactive distillation column 4 through the pre-reacted material discharge pipe 33. A 70-80 wt% concentrated formaldehyde solution is transported through the concentrated formaldehyde solution discharge pipe 13 and enters the lower reaction section 410 of the reactive distillation column 4 through the concentrated formaldehyde inlet.
[0045] Both the upper reaction section 49 and the lower reaction section 410 are packed with solid acid catalysts. Under the action of catalytic distillation, the material in the upper reaction section 49 reacts to generate methylal, DMM2, and DMM3. The reactions that occur are as follows:
[0046] 2CH3OH+HCHO⇌CH3OCH2OCH3+H2O,
[0047] CH3OCH2OCH3+HCHO⇌CH3O(CH2O)2CH3 (DMM2),
[0048] CH3O(CH2O)2CH3+HCHO⇌CH3O(CH2O)3CH3(DMM3);
[0049] Since the boiling point of water is lower than that of DMM2~DMM6 but higher than that of methanol, formaldehyde, and methylal, most of the water accumulates between the upper reaction section 49 and the lower reaction section 410. During reactive distillation, the water between the upper reaction section 49 and the lower reaction section 410 is extracted through the water extraction pipe 412. This not only helps the reaction equilibrium shift towards the direction of water consumption but also helps reduce the water content in the material entering the lower reaction section 410 from the upper reaction section 49.
[0050] Under the action of catalytic distillation, the material in the lower reaction section 410 includes the material leaving the upper reaction section 49 and entering the lower reaction section 410, as well as the input concentrated formaldehyde solution with a concentration of 70-80 wt%. Since the water content in the material leaving the upper reaction section 49 and entering the lower reaction section 410 is low, and the water content in the input 70-80 wt% concentrated formaldehyde solution is also low, and the boiling point of water is lower than that of DMM2-DMM6, the water is basically concentrated between the upper reaction section 49 and the lower reaction section 410. By extracting the water between the upper reaction section 49 and the lower reaction section 410, the reaction in the lower reaction section 410 is almost unaffected by water, resulting in a high conversion rate of formaldehyde. Simultaneously, it can further generate DMM3-DMM6 with higher polymerization degrees. The reactions occurring in the lower reaction section 410 are as follows:
[0051] CH3OCH2OCH3+HCHO⇌CH3O(CH2O)2CH3 (DMM2),
[0052] CH3O(CH2O)2CH3+HCHO⇌CH3O(CH2O)3CH3(DMM3),
[0053] CH3O(CH2O)3CH3+HCHO⇌CH3O(CH2O)4CH3 (DMM4),
[0054] CH3O(CH2O)4CH3+HCHO⇌CH3O(CH2O)5CH3 (DMM5),
[0055] CH3O(CH2O)5CH3+HCHO⇌CH3O(CH2O)6CH3(DMM6);
[0056] In the lower reaction section 410, formaldehyde conversion is relatively high. Crude products DMM2~DMM6 (formaldehyde concentration <1wt%, balance being methylal and DMM2~DMM6) are collected from the bottom of the reactive distillation column 4. The collected crude products DMM2~DMM6 are further reactively distilled to obtain DMM3~DMM6 products with higher purity. An azeotrope of methylal and methanol (methylal 92~93wt%, methanol 7~8wt%, water <0.5wt%) is collected from the top of the reactive distillation column 4.
[0057] The technical solution of this application concentrates a 50-55 wt% formaldehyde aqueous solution to obtain a formaldehyde solution with a higher concentration and a formaldehyde solution with a lower concentration. The two formaldehyde solutions react in different regions, and excess water is removed during the reaction process, which helps to reduce the impact of water on the entire reaction system, improve the formaldehyde conversion rate, and avoid the self-polymerization of formaldehyde.
[0058] It should be noted that DMM2~DMM6 includes DMM2, DMM3, DMM4, DMM5 and DMM6. In the 50~55wt% formaldehyde aqueous solution and the methanol feedstock of more than 95wt%, the feed molar ratio of methanol to formaldehyde is 1:(1.5~2.0).
[0059] Furthermore, the reactive distillation column 4 is a plate column or a packed column. The reflux ratio of the reactive distillation column 4 is 2~10, the operating pressure of the reactive distillation column 4 is 0~1.0 MPa, the top temperature is 43-120℃, and the bottom temperature is 80-150℃. The azeotrope collected from the top of the reactive distillation column 4 is condensed, with part of the condensate refluxed back to the reactive distillation column 4, and the remaining condensate sent to the light component removal distillation column 5. The light component removal distillation column 5 is a plate column or a packed column. The reflux ratio of the light component removal distillation column 5 is 1~5, the operating pressure of the light component removal distillation column 5 is 0.4~0.6 MPa, the bottom temperature is 95~100℃, and the top temperature is 65~70℃. After distillation, light components such as methyl formate are collected from the top of the light component removal distillation column 5, and the bottom material is refluxed back to the reactive distillation column 4 to improve the utilization rate of methylal.
[0060] Specifically, the bottom of the reactive distillation column 4 is equipped with a DMMn crude product outlet pipe 413. The bottom material (DMM2~DMM6 crude products) of the reactive distillation column 4 is collected through the DMMn crude product outlet pipe 413 for further reactive distillation to obtain DMM3~DMM6 products with higher purity. The reactive distillation column 4 also includes a first condensation section, which includes a first condenser 41, a first reflux tank 42, a first reflux pump 43, and a first reflux pipe 44 connected in sequence. The gas inlet of the first condenser 41 is connected to the vapor outlet at the top of the column through a pipe, and the liquid outlet of the first reflux pipe 44 is connected to the first liquid return port 46 at the top of the column. A branch of the first reflux pipe 44 is provided with a first light component outlet pipe 45 connected to the feed inlet of the light component removal distillation column 5. The bottom of the light component removal distillation column 5 is equipped with a material reflux pipe connected to the first reflux tank 42, and the top of the light component removal distillation column 5 is equipped with a third light component outlet pipe 51.
[0061] By adopting the above technical solution, after the azeotrope collected from the top of the reactive distillation column 4 is condensed, part of the condensate is returned to the reactive distillation column 4 through the first reflux pipe 44, and the remaining part of the condensate is sent to the light component removal distillation column 5 through the first light component collection pipe 45. The third light component collection pipe 51 collects light components such as methyl formate. The bottom material of the column after the light components have been removed is returned to the reactive distillation column 4 through the material reflux pipe to improve the utilization rate of methyl acetal.
[0062] In this embodiment of the invention, the first reflux pipe 44 is further branched with a branch reflux pipe connected to the second reflux port 47 at the lower part of the column body, and the second reflux port 47 is correspondingly provided with the lower reaction section 410. After the azeotrope collected from the top of the reactive distillation column 4 is condensed, the condensate in the reflux section is divided into two streams: one stream flows back to the top of the reactive distillation column 4 through the first reflux port 46, and the other stream flows back to the lower reaction section 410 through the second reflux port 47.
[0063] In an embodiment of this utility model, the DMMn production equipment further includes a reactive distillation device, which includes a first hydrogenation reactor 6 and a separation distillation column 7. The top of the first hydrogenation reactor 6 is provided with a reactant inlet 612 connected to the DMMn crude product outlet pipe 413. The upper part of the first hydrogenation reactor 6 is provided with a first hydrogen inlet 611, the middle part is provided with a copper-based catalyst, and the bottom is provided with a first hydrogenation reactant outlet pipe 62. The feed inlet of the separation distillation column 7 is connected to the first hydrogenation reactant outlet pipe 62.
[0064] Specifically, a first cooler 63 and a first gas-liquid separator 64 are sequentially arranged between the first hydrogenation reaction material discharge pipe 62 and the feed inlet of the separation distillation column 7. The gas outlet of the first gas-liquid separator 64 is connected to the first hydrogen inlet 611 through a first connecting pipe. A first compressor is installed on the first connecting pipe. The liquid outlet of the first gas-liquid separator 64 is connected to the feed inlet of the separation distillation column 7 through a pipe.
[0065] By adopting the above technical solution, the crude DMM2~DMM6 products contain a small amount of formaldehyde (formaldehyde <1wt%). The crude DMM2~DMM6 products and hydrogen are fed into the first hydrogenation reactor 6. Under the condition of copper-based catalyst, the pressure is controlled at 1.0~2.0MPa and the temperature at 100~150℃, so that the formaldehyde in the crude DMM2~DMM6 products reacts with hydrogen to produce methanol. After the hydrogenation reaction, the material is cooled by the first cooler 63 and then enters the first gas-liquid separator 64. The separated hydrogen is pressurized by the first compressor and returned to the first hydrogenation reactor 6 for recycling. The separated hydrogenation reaction liquid (0.5~2wt% methanol, 30~50wt% methylal, and 48~69wt% DMM2~DMM6) is sent to the separation distillation column 7.
[0066] The separation distillation column 7 is a plate column or a packed column. The top of the separation distillation column 7 is provided with a second light component outlet pipe 71, the bottom of the column is provided with a DMM2 side line outlet pipe 72, and the bottom of the column is provided with a DMMn product outlet pipe 73. The outlet end of the second light component outlet pipe 71 is connected to the concentrated formaldehyde inlet. The reflux ratio of the separation distillation column 7 is 1~3, the operating pressure of the separation distillation column 7 is atmospheric pressure, the bottom temperature is 160-180℃, and the top temperature is 42-43℃. The azeotrope at the top of the separation distillation column 7 (containing light components of methyl acetal and methanol) is collected through the second light component collection pipe 71 and sent to the lower reaction section 410 of the reactive distillation column 4. The lower material of the separation distillation column 7 (DMM2 solution) is collected through the DMM2 side line collection pipe 72. The bottom material of the separation distillation column 7 (DMM3~DMM6 products) is collected through the DMMn product collection pipe 73.
[0067] In an embodiment of this utility model, the reactive distillation apparatus further includes a converter 8 and a second hydrogenation reactor 9; the feed inlet of the converter 8 is connected to the discharge end of the DMM2 side line outlet pipe 72, the top of the second hydrogenation reactor 9 is provided with a reforming reaction material inlet 912 connected to the discharge outlet of the converter 8, the upper part of the second hydrogenation reactor 9 is provided with a second hydrogen inlet 911, and the bottom of the second hydrogenation reactor 9 is provided with a second hydrogenation reaction material discharge pipe 92 connected to the feed inlet of the separation distillation column 7.
[0068] Specifically, a second cooler 93 and a second gas-liquid separator 94 are sequentially arranged between the second hydrogenation reaction material discharge pipe 92 and the feed inlet of the separation distillation column 7. The gas outlet of the second gas-liquid separator 94 is connected to the second hydrogen inlet 911 through a second connecting pipe. A second compressor is installed on the second connecting pipe. The liquid outlet of the second gas-liquid separator 94 is connected to the feed inlet of the separation distillation column 7 through a pipe.
[0069] By adopting the above technical solution, the DMM2 solution collected from the side stream is sent into converter 8. Converter 8 is filled with acidic resin catalyst, and the pressure is controlled at 0.6~1.0MPa and the temperature at 60~100℃, so that DMM2 undergoes a reforming reaction to generate DMM3~DMM6 with higher degree of polymerization. At the same time, methyl acetal, methanol and formaldehyde are produced. The composition of the material after the reforming reaction is: methyl acetal 40~55wt%, DMM2 20~30wt%, DMM3-5 20~25wt%, and a small amount of methanol and formaldehyde.
[0070] The reformed material and hydrogen are fed into the second hydrogenation reactor 9. Under the condition of copper-based catalyst, the pressure is controlled at 1.0~2.0MPa and the temperature at 100~150℃, so that the formaldehyde in the material undergoes a hydrogenation reaction to produce methanol. After being cooled by the second cooler 93, the material enters the second gas-liquid separator 94. The separated hydrogen is pressurized by the second compressor and returned to the second hydrogenation reactor 9 for recycling. The separated hydrogenated reaction liquid is sent to the separation distillation column 7.
[0071] The above description is merely an exemplary embodiment of the present utility model and does not limit the patent scope of the present utility model. Any equivalent structural transformations made based on the technical concept of the present utility model and the contents of the present utility model specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present utility model.
Claims
1. A DMMn production equipment, characterized in that, include: A formaldehyde concentration separator has a formaldehyde solution inlet in the middle, a flash vapor discharge pipe in the upper part, and a concentrated formaldehyde solution discharge pipe in the lower part. The formaldehyde absorption tower has a water inlet at the top, an air inlet connected to the flash vapor discharge pipe at the bottom, and a dilute formaldehyde solution discharge pipe at the bottom. The pre-reactor has a dilute formaldehyde inlet connected to the dilute formaldehyde solution discharge pipe and a methanol inlet, and a pre-reacted material discharge pipe is provided at the bottom of the pre-reactor. A reactive distillation column includes a column body, an upper reaction section and a lower reaction section located below the upper reaction section, a water collection pipe located on the column body between the upper and lower reaction sections, a pre-reactant inlet on the column body corresponding to the upper reaction section and connected to a pre-reactant discharge pipe, and a concentrated formaldehyde inlet on the column body corresponding to the lower reaction section and connected to a concentrated formaldehyde solution discharge pipe.
2. The DMMn production equipment as described in claim 1, characterized in that, The DMMn production equipment also includes a light-light distillation column; The reactive distillation column further includes a first condensation section, which includes a first condenser, a first reflux tank, a first reflux pump, and a first reflux pipe connected in sequence. The inlet of the first condenser is connected to the vapor outlet at the top of the column through a pipe, and the outlet of the first reflux pipe is connected to the first liquid return port at the top of the column. The first reflux pipe is branched off and connected to the feed inlet of the light component removal distillation column, and the bottom of the light component removal distillation column is provided with a material reflux pipe connected to the first reflux tank.
3. The DMMn production equipment as described in claim 2, characterized in that, The top of the light component removal distillation column is equipped with a third light component collection pipe.
4. The DMMn production equipment as described in claim 2, characterized in that, The first reflux pipe is also branched off and connected to the second reflux port at the bottom of the tower body, and the second reflux port is correspondingly provided to the lower reaction section.
5. The DMMn production equipment as described in claim 1, characterized in that, The bottom of the column is provided with a crude DMMn product collection pipe; the DMMn production equipment also includes a reactive distillation unit, which includes a first hydrogenation reactor and a separation distillation column. The first hydrogenation reactor is provided with a reaction material inlet at the top, which is connected to the crude DMMn product outlet pipe. The first hydrogenation reactor is provided with a first hydrogen inlet at the top, a copper-based catalyst in the middle, and a first hydrogenation reaction material outlet pipe at the bottom. The feed inlet of the separation distillation column is connected to the discharge pipe of the first hydrogenation reaction material.
6. The DMMn production equipment as described in claim 5, characterized in that, A first cooler and a first gas-liquid separator are sequentially arranged between the first hydrogenation reaction material discharge pipe and the feed inlet of the separation distillation column. The gas outlet of the first gas-liquid separator is connected to the first hydrogen inlet through a first connecting pipe. A first compressor is installed on the first connecting pipe. The liquid outlet of the first gas-liquid separator is connected to the feed inlet of the separation distillation column through a pipe.
7. The DMMn production equipment as described in claim 5, characterized in that, The separation distillation column is equipped with a second light component outlet pipe at the top, a DMM2 side outlet pipe at the bottom, and a DMMn product outlet pipe at the bottom.
8. The DMMn production equipment as described in claim 7, characterized in that, The discharge end of the second light component collection pipe is connected to the concentrated formaldehyde inlet.
9. The DMMn production equipment as described in claim 7, characterized in that, The reactive distillation apparatus further includes a converter connected to the side line outlet pipe of the DMM2, and a second hydrogenation reactor connected to the outlet end of the converter. The upper part of the second hydrogenation reactor is provided with a second hydrogen inlet, and the bottom part is provided with a second hydrogenation reaction material discharge pipe connected to the feed inlet of the separation distillation column.
10. The DMMn production equipment as described in claim 9, characterized in that, A second cooler and a second gas-liquid separator are sequentially installed between the second hydrogenation reaction material discharge pipe and the feed inlet of the separation distillation column. The gas outlet of the second gas-liquid separator is connected to the second hydrogen inlet through a second connecting pipe. A second compressor is installed on the second connecting pipe. The liquid outlet of the second gas-liquid separator is connected to the feed inlet of the separation distillation column through a pipeline.