High-purity methylal production equipment
By using a multi-stage distillation tower system and thermal coupling technology, the problem of low purity in existing methylal production equipment has been solved, resulting in high-purity methylal products that meet the needs of high-purity applications and save energy consumption.
Patent Information
- Application Number
- CN202422931993.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-29
- Publication Date
- 2025-10-17
- Estimated Expiration
- 2034-11-29
AI Technical Summary
The methylal products produced by existing methylal production equipment have low purity, which limits their application in many industries.
A multi-stage distillation column system is adopted, including an atmospheric pressure catalytic distillation column, a first-stage pressurized distillation column, and a second-stage pressurized distillation column. Combined with solid acid catalysts and thermal coupling technology, the purity of methylal is improved through multi-stage distillation and dehydration processes.
The production of methylal with a purity of over 99.95% meets the high purity requirements for electronic and chromatographic grades, saves energy consumption, and realizes the production of high-purity methylal.
Smart Images
Figure CN223439797U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to the field of chemical production technology, especially to a high purity methylal production equipment. BACKGROUND
[0002] Methylal is also called dimethyloxymethane, and its molecular formula is CH3OCH2OCH3. It is a colorless, non-toxic and environmentally friendly chemical product, which can be used as an organic synthesis intermediate, a solvent and a diesel additive. It is an environmentally friendly product that can replace toxic and harmful solvents and reduce air pollution.
[0003] In industry, methylal is usually obtained by the reaction of methanol and formaldehyde aqueous solution catalyzed by an acidic catalyst. Since methylal and methanol can form azeotrope, theoretically, only methylal with a mass fraction of about 92-93% can be obtained by conventional rectification separation at normal pressure. The high content of methanol as an impurity and its relatively high toxicity limit the application of methylal in many industries. UTILITY MODEL CONTENT
[0004] The main purpose of the utility model is to provide a high purity methylal production equipment, which aims to solve the problem of low purity of methylal products produced by the existing methylal production equipment.
[0005] To achieve the above-mentioned purpose, the high purity methylal production equipment provided by the utility model comprises:
[0006] The atmospheric catalytic rectification tower has a first feed inlet, a first reflux pipe is arranged at the top of the atmospheric catalytic rectification tower, a first reboiler is arranged at the bottom of the atmospheric catalytic rectification tower, and a first discharge pipe is branched from the first reflux pipe;
[0007] The first-stage pressurized rectification tower has a second feed inlet connected with the discharge end of the first discharge pipe, a second gas discharge pipe and a second reflux pipe are arranged at the top of the first-stage pressurized rectification tower, and a second methylal solution discharge pipe is arranged at the bottom of the first-stage pressurized rectification tower, the discharge end of the second gas discharge pipe is connected with the heat exchange medium inlet of the first reboiler, and the second reflux pipe is connected with the heat exchange medium outlet of the first reboiler;
[0008] The second-stage pressurized rectification tower has a third feed inlet connected with the discharge end of the second methylal solution discharge pipe, and a third methylal solution discharge pipe is arranged at the bottom of the second-stage pressurized rectification tower.
[0009] In an embodiment, the high purity methylal production equipment further comprises an atmospheric recovery rectification tower, a second discharge pipe is branched from the second reflux pipe, the atmospheric recovery rectification tower has a fourth feed inlet connected with the discharge end of the second discharge pipe, a methanol discharge pipe is arranged at the bottom of the atmospheric recovery rectification tower, and the discharge end of the methanol discharge pipe is connected with the first feed inlet.
[0010] In an embodiment, the top of the secondary pressurized rectifying column is provided with a third gas outlet pipe and a third reflux pipe, the bottom of the atmospheric recovery rectifying column is provided with a fourth reboiler, the discharge end of the third gas outlet pipe is connected with the heat exchange medium inlet of the fourth reboiler, and the third reflux pipe is connected with the heat exchange medium outlet of the fourth reboiler.
[0011] In an embodiment, a third discharge pipe is arranged on the third reflux pipe, and the discharge end of the third discharge pipe is connected with the fourth feed inlet.
[0012] In an embodiment, a third reflux tank and a third reflux pump are sequentially arranged between the heat exchange medium outlet of the fourth reboiler and the third reflux pipe.
[0013] In an embodiment, the top of the atmospheric recovery rectifying column is provided with a fourth condensing section, the fourth condensing section comprises a fourth condenser, a fourth reflux tank, a fourth reflux pump and a fourth reflux pipe arranged sequentially, the gas inlet end of the fourth condensing tank is connected with the steam outlet at the top of the atmospheric recovery rectifying column, and the liquid outlet end of the fourth reflux pipe is connected with the liquid return port at the top of the atmospheric recovery rectifying column.
[0014] In an embodiment, the atmospheric catalytic rectifying column is a plate column, and the number of effective plates is 60-100; and / or,
[0015] The primary pressurized rectifying column and the secondary pressurized rectifying column are plate columns or packed columns.
[0016] In an embodiment, in the direction from top to bottom, the atmospheric catalytic rectifying column comprises a first rectifying section, a first reaction section and a first distillation section arranged sequentially, the first reaction section is provided with a solid acid catalyst, and the first feed inlet is located between the first rectifying section and the first reaction section.
[0017] In an embodiment, the top of the atmospheric catalytic rectifying column is provided with a first condensing section, the first condensing section comprises a first condenser, a first reflux tank, a first reflux pump and the first reflux pipe arranged sequentially, the gas inlet end of the first condenser is connected with the steam outlet at the top of the atmospheric catalytic rectifying column through a pipeline, and the liquid outlet end of the first reflux pipe is connected with the liquid return port at the top of the atmospheric catalytic rectifying column.
[0018] In an embodiment, a second reflux tank and a second reflux pump are sequentially arranged between the heat exchange medium outlet of the first reboiler and the second reflux pipe.
[0019] The technical scheme of the utility model discloses a methanol and formaldehyde aqueous solution as raw materials, reaction generates crude methylal product in the normal pressure catalytic rectifying tower, adopts primary pressurized rectifying tower and secondary pressurized rectifying tower to pressurized rectifying crude methylal product, can prepare the methylal product of the purity above 99.95%, after dehydration, can prepare the methylal product of the purity above 99.999%, to better satisfy the use demand of electronic grade and chromatographic grade product etc. BRIEF DESCRIPTION OF DRAWINGS
[0020] In order to more clearly illustrate the technical scheme in the embodiment of the utility model or prior art, the following will briefly introduce the drawing needed to be used in the embodiment or prior art description, obviously, the drawing in the following description only is some embodiments of the utility model, for ordinary skilled person in the art comes, under the premise of not paying the creative labor, still can obtain other drawings according to the structure shown by these drawings.
[0021] Figure 1 The structure diagram of one embodiment of the high-purity methylal production equipment provided by the utility model.
[0022] BRIEF DESCRIPTION OF DRAWINGS
[0023] 1, atmospheric catalytic rectifying column; 11, first condenser; 12, first reflux tank; 13, first reflux pump; 14, first reflux pipe; 15, first discharge pipe; 16, first rectifying section; 17, first reaction section; 18, first stripping section; 19, first reboiler; 110, waste water discharge pipe; 111, first feed inlet; 2, primary pressure rectifying column; 21, second gas outlet pipe; 22, second liquid inlet pipe; 23, second reflux tank; 24, second reflux pump; 25, second reflux pipe; 26, second discharge pipe; 27, second rectifying section; 28, second separation section; 29, second stripping section; 210, second feed inlet; 211, second reboiler; 212, second dimethylformamide solution discharge pipe; 3, secondary pressure rectifying column; 31, third gas outlet pipe; 32, third liquid inlet pipe; 33, third reflux tank; 34, third reflux pump; 35, third reflux pipe; 36, third discharge pipe; 37, third rectifying section; 38, third separation section; 39, third feed inlet; 310, third stripping section; 311, third reboiler; 312, third dimethylformamide solution discharge pipe; 313, dehydrator; 4, atmospheric recovery rectifying column; 41, fourth condenser; 42, fourth reflux tank; 43, fourth reflux pump; 44, fourth reflux pipe; 45, fourth discharge pipe; 46, fourth rectifying section; 47, fourth separation section; 48, fourth stripping section; 49, fourth reboiler; 410, methanol discharge pipe; 411, fourth feed inlet.
[0024] The implementation, functional features and advantages of the utility model will be further described with reference to the drawings in combination with embodiments. DETAILED DESCRIPTION
[0025] The technical solutions in the embodiments of the utility model will be clearly and completely described in combination with the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the utility model.
[0026] It should be noted that if the embodiments of the utility model involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement condition, etc. between components in a certain posture, and if the certain posture changes, the directional indications also change accordingly.
[0027] In addition, if the description of "first", "second" and the like is involved in the embodiments of the present application, the description of "first", "second" and the like is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can be explicitly or implicitly included at least one of the features. In addition, if "and / or" or "and / or" appears throughout the text, it means that the three parallel schemes are included, for example, "A and / or B" includes A scheme, or B scheme, or A and B scheme. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the realization of the ordinary skilled in the art, when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the protection scope required by the present application.
[0028] In industry, methylal is usually obtained by reacting methanol and formaldehyde aqueous solution with an acidic catalyst. Since methylal and methanol can form azeotrope, theoretically, only methylal with mass fraction of about 92-93% can be obtained by conventional rectification separation at normal pressure, and methanol as an impurity has relatively high toxicity, which limits the application of methylal in many industries. In view of this, the present application provides a high-purity methylal production equipment to solve the problem of low purity of methylal product produced by the existing methylal production equipment.
[0029] Please refer to Figure 1 In an embodiment of the present application, the methylal production equipment comprises: a normal-pressure catalytic rectification tower 1, a first-stage pressurized rectification tower 2, and a second-stage pressurized rectification tower 3. The normal-pressure catalytic rectification tower 1 has a first feed inlet 111. The top of the normal-pressure catalytic rectification tower 1 is provided with a first reflux pipe 14, and the bottom is provided with a first reboiler 19. A first discharge pipe 15 is branched and arranged on the first reflux pipe 14. The first-stage pressurized rectification tower 2 has a second feed inlet 210 connected with the discharge end of the first discharge pipe 15. The top of the first-stage pressurized rectification tower 2 is provided with a second gas outlet pipe 21 and a second reflux pipe 25, and the bottom is provided with a second methylal solution outlet pipe 212. The discharge end of the second gas outlet pipe 21 is connected with the heat exchange medium inlet of the first reboiler 19, and the second reflux pipe 25 is connected with the heat exchange medium outlet of the first reboiler 19. The second-stage pressurized rectification tower 3 has a third feed inlet 39 connected with the discharge end of the second methylal solution outlet pipe 212. The bottom of the second-stage pressurized rectification tower 3 is provided with a third methylal solution outlet pipe 312.
[0030] The technical scheme of the utility model discloses, methanol and formaldehyde aqueous solution enter the atmospheric catalytic rectifying tower 1 from the first feed port 111, in the atmospheric catalytic rectifying tower 1, methanol and formaldehyde aqueous solution are under the action of catalyst and generate methylal through alcohol aldehyde condensation reaction, are handled through rectification, and the methylal-methanol azeotrope of atmospheric pressure is adopted from the top of atmospheric catalytic rectifying tower 1, after condensation, the atmospheric methylal-methanol blend is formed, part methylal-methanol blend is returned to the top of atmospheric catalytic rectifying tower 1 through the first reflux pipe 14, the rest part methylal-methanol blend is transported to the primary pressurized rectifying tower 2 in through the first discharge pipe 15. And the water of reaction generation and the water of formaldehyde aqueous solution bring in gather in the tower bottom, are adopted from the bottom of atmospheric catalytic rectifying tower 1, and are discharged as process waste water. Among them, the reflux ratio of atmospheric catalytic rectifying tower 1 is 1~5;The operating pressure of atmospheric catalytic rectifying tower 1 is atmospheric pressure, and the top temperature is 40~50 DEG C, and the kettle temperature is 100~110 DEG C.
[0031] The first discharge pipe 15 transports the rest part methylal-methanol blend to the second feed port 210, and enters the primary pressurized rectifying tower 2 in through the second feed port 210, and the methylal-methanol blend transported to the primary pressurized rectifying tower 2 is under the pressurized operation and carries out pressurized rectification. The methylal-methanol azeotrope of pressure is adopted from the top of primary pressurized rectifying tower 2, and the methylal solution is adopted from the bottom of primary pressurized rectifying tower 2, and the methylal solution is transported to the secondary pressurized rectifying tower 3 in through the second methylal solution extraction pipe 212. The methylal-methanol azeotrope of pressure is transported to the heat exchange medium inlet of first reboiler 19 through the second gas outlet pipe 21, and then enters the first reboiler 19, to provide heat source for the first reboiler 19, and the methylal-methanol azeotrope is condensed to form methylal-methanol blend after heat exchange, and the methylal-methanol blend flows out from the heat exchange medium outlet of first reboiler 19, and part of the methylal-methanol blend flows back to the top of primary pressurized rectifying tower 2 through the second reflux pipe 25. The high-temperature high-pressure gas phase adopted from the top of primary pressurized rectifying tower 2 is used as the heat source of first reboiler 19, and exchanges heat with the material in first reboiler 19, to form thermal coupling, to save the steam consumption of first reboiler 19 and the circulating water consumption of the corresponding condensation section of primary pressurized rectifying tower 2. Among them, the reflux ratio of primary pressurized rectifying tower 2 is 1~5;The operating pressure of primary pressurized rectifying tower 2 is 0.7~1.5MPa, and the top temperature is 110~120 DEG C, and the kettle temperature is 120~130 DEG C.
[0032] The methylal solution at the bottom of the first pressurized rectifying column 2 is taken out through the second methylal solution outlet pipe 212 and enters the second pressurized rectifying column 3 through the third feed port 39, and the methylal solution in the second pressurized rectifying column 3 is further subjected to pressurized rectification under further pressurization. The pressurized methylal-methanol azeotrope is taken out from the top of the second pressurized rectifying column 3, and the methylal solution with higher purity is taken out from the bottom of the second pressurized rectifying column 3, and the methylal solution with higher purity is subjected to dehydration to obtain high-purity methylal, and the pressurized methylal-methanol azeotrope is condensed to form a methylal-methanol mixture, and part of the methylal-methanol mixture is refluxed into the second pressurized rectifying column 3. The reflux ratio of the second pressurized rectifying column 3 is 1-5; the operating pressure of the second pressurized rectifying column 3 is 1.0-2.0 MPa, the top temperature is 125-150 DEG C, and the bottom temperature is 135-160 DEG C.
[0033] In the technical scheme of the utility model, methanol and formaldehyde aqueous solution are used as raw materials, methylal crude product is generated in the normal-pressure catalytic rectifying column 1, the first pressurized rectifying column 2 and the second pressurized rectifying column 3 are used to purify the methylal crude product, and the methylal product with purity above 99.95% can be prepared, and after dehydration, the methylal product with purity above 99.999% can be prepared, so that the use requirement of electronic-grade and chromatographic-grade products can be better satisfied. The high-temperature and high-pressure gas phase taken out from the top of the first pressurized rectifying column 2 is used as the heat source of the first reboiler 19, exchanges heat with the material in the first reboiler 19, forms heat coupling, and the steam consumption of the first reboiler 19 and the circulating water consumption of the corresponding condensing section of the first pressurized rectifying column 2 are saved.
[0034] Further, the atmospheric catalytic rectifying column 1 is a plate column, and the effective plate number is 60-100. In the direction from top to bottom, the atmospheric catalytic rectifying column 1 comprises a first overhead condensing section, a first rectifying section 16, a first reaction section 17, a first stripping section 18, and a first reboiler 19. The first overhead condensing section comprises a first condenser 11, a first reflux tank 12, a first reflux pump 13 and a first reflux pipe 14 connected in sequence by pipes, the first condenser 11 is connected to the vapor outlet at the top of the atmospheric catalytic rectifying column 1 by a pipe, and the liquid outlet of the first reflux pipe 14 is connected to the liquid return port at the top of the atmospheric catalytic rectifying column 1. The feed inlet of the first reboiler 19 is connected to the outlet at the bottom of the atmospheric catalytic rectifying column 1 by a pipe, and the outlet of the first reboiler 19 is connected to the material return port at the bottom of the atmospheric catalytic rectifying column 1 by a pipe. The first feed inlet 111 is located at the middle position between the first rectifying section 16 and the first reaction section 17, and the methanol and the aqueous formaldehyde solution enter the atmospheric catalytic rectifying column 1 through the first feed inlet 111. The fresh aqueous formaldehyde solution and the fresh methanol in the raw material entering through the first feed inlet 111 have a molar ratio of methanol to formaldehyde of (2-2.5):1, the mass fraction of formaldehyde in the fresh aqueous formaldehyde solution is 20-50% (purity is 20-50%), and the purity of the fresh methanol is 99.9%. The first reaction section 17 is provided with a solid acid catalyst. The bottom of the atmospheric catalytic rectifying column 1 is also provided with a waste water outlet pipe 110, and a first water pump is arranged on the waste water outlet pipe 110, and the waste water at the bottom of the atmospheric catalytic rectifying column 1 is discharged through the waste water outlet pipe 110.
[0035] It can be understood that the atmospheric methylal-methanol azeotrope is discharged from the top of the atmospheric catalytic rectifying column 1, condensed through the first overhead condensing section, and forms a methylal-methanol mixture. The solid acid catalyst is selected from at least one of Amberstly-70 sulfonic acid resin solid acid catalyst, HZSM-5 molecular sieve, HBeta zeolite molecular sieve and HMCM-22 zeolite molecular sieve.
[0036] Further, the primary pressurized rectifying column 2 is a plate column, and the effective plate number is 30-50. The primary pressurized rectifying column 2 comprises a second overhead condensing section, a second rectifying section 27, a second separation section 28, a second stripping section 29, and a second reboiler 211 arranged in sequence. The second overhead condensing section comprises a second gas outlet pipe 21, a second liquid inlet pipe 22, a second reflux tank 23, a second reflux pump 24, and a second reflux pipe 25 connected in sequence, one end of the second gas outlet pipe 21 is connected with the steam outlet at the top of the primary pressurized rectifying column 2, the other end of the second gas outlet pipe 21 is connected with the heat exchange medium inlet of the first reboiler 19, one end of the second liquid inlet pipe 22 is connected with the heat exchange medium outlet of the first reboiler 19, the other end of the second liquid inlet pipe 22 is connected with the second reflux tank 23, the liquid outlet end of the second reflux pipe 25 is connected with the liquid return port at the top of the primary pressurized rectifying column 2. The feed inlet of the second reboiler 211 is connected with the material outlet at the bottom of the primary pressurized rectifying column 2 through a pipeline, the material outlet of the second reboiler 211 is connected with the material return port at the bottom of the primary pressurized rectifying column 2 through a pipeline; the second reboiler 211 is further provided with a heat exchange medium inlet and a heat exchange medium outlet, heating steam enters the second reboiler 211 through the heat exchange medium inlet to exchange heat with the material in the second reboiler 211, and then flows out through the heat exchange medium outlet. The second feed inlet 210 is located at the middle position between the second rectifying section 27 and the second separation section 28, and is connected with the first material outlet pipe 15. The second reflux pipe 25 is branched to be provided with a second material outlet pipe 26, and the second material outlet pipe 26 is connected with the fourth feed inlet 411 on the atmospheric recovery rectifying column 4. The bottom of the primary pressurized rectifying column 2 is further provided with a second methylal solution outlet pipe 212, the second methylal solution outlet pipe 212 is provided with a second water pump, and the second methylal solution outlet pipe 212 is connected with the third feed inlet 39 on the secondary pressurized rectifying column 3.
[0037] It can be understood that the methylal-methanol azeotrope taken from the top of the primary pressurized rectifying column 2 is transported to the heat exchange medium inlet of the first reboiler 19 through the second gas outlet pipe 21, and then enters the first reboiler 19 to provide heat source for the first reboiler 19, the methylal-methanol azeotrope is condensed to form a methylal-methanol mixture after heat exchange, the methylal-methanol mixture flows out from the heat exchange medium outlet of the first reboiler 19, flows through the second reflux tank 23, and then part of the methylal-methanol mixture is refluxed to the top of the primary pressurized rectifying column 2 through the second reflux pipe 25, and the rest of the methylal-methanol mixture is transported into the atmospheric recovery rectifying column 4 through the second material outlet pipe 26.
[0038] The methylal solution deposited at the bottom of the primary pressurized rectifying column 2 is taken out through the second methylal solution outlet pipe 212 and transported into the secondary pressurized rectifying column 3 for further pressurized rectification to obtain high-purity methylal product.
[0039] Further, the secondary pressurized rectifying column 3 is a plate column, and the effective plate number is 30-50. The secondary pressurized rectifying column 3 comprises a third overhead condensing section, a third rectifying section 37, a third separation section 38, a third stripping section 310, and a third reboiler 311 arranged in sequence. The third overhead condensing section comprises a third gas outlet pipe 31, a third liquid inlet pipe 32, a third reflux tank 33, a third reflux pump 34, and a third reflux pipe 35 connected in sequence, one end of the third gas outlet pipe 31 is connected with the steam outlet at the top of the secondary pressurized rectifying column 3, the other end of the third gas outlet pipe 31 is connected with the heat exchange medium inlet of the fourth reboiler 49 at the bottom of the normal pressure recovery rectifying column 4, one end of the third liquid inlet pipe 32 is connected with the heat exchange medium outlet of the fourth reboiler 49, the other end of the third liquid inlet pipe 32 is connected with the third reflux tank 33, and the liquid outlet end of the third reflux pipe 35 is connected with the liquid return port at the top of the secondary pressurized rectifying column 3. The feed inlet of the third reboiler 311 is connected with the material outlet at the bottom of the secondary pressurized rectifying column 3 through a pipeline, and the material outlet of the third reboiler 311 is connected with the material return port at the bottom of the secondary pressurized rectifying column 3 through a pipeline; the third reboiler 311 is further provided with a heat exchange medium inlet and a heat exchange medium outlet, heating steam enters the third reboiler 311 through the heat exchange medium inlet to exchange heat with the material in the third reboiler 311, and then flows out through the heat exchange medium outlet. The third feed inlet 39 is located at the middle position between the third stripping section 310 and the third separation section 38, and the third feed inlet 39 is connected with the second methylal solution extraction pipe 212. The third reflux pipe 35 is branched to be provided with a third material outlet pipe 36, and the material outlet end of the third material outlet pipe 36 is connected with the fourth feed inlet 411 on the normal pressure recovery rectifying column 4. The bottom of the secondary pressurized rectifying column 3 is further provided with a third methylal solution extraction pipe 312, the third methylal solution extraction pipe 312 is provided with a third water pump, and the liquid outlet end of the third methylal solution extraction pipe 312 is connected with a dehydrator 313. The methylal solution extracted from the bottom of the secondary pressurized rectifying column 3 is dehydrated by the dehydrator 313, and a methylal product with a purity of more than 99.999% can be obtained.
[0040] It can be understood that the pressurized methylal-methanol azeotrope extracted from the top of the secondary pressurized rectifying column 3 is transported to the heat exchange medium inlet of the fourth reboiler 49 through the third gas outlet pipe 31, and then enters the fourth reboiler 49 to provide heat source for the fourth reboiler 49. The methylal-methanol azeotrope is condensed to form a methylal-methanol blend after heat exchange, the methylal-methanol blend flows out from the heat exchange medium outlet of the fourth reboiler 49, flows through the third reflux tank 33, part of the methylal-methanol blend is returned to the top of the secondary pressurized rectifying column 3 through the third reflux pipe 35, and the rest of the methylal-methanol blend is transported into the normal pressure recovery rectifying column 4 through the third material outlet pipe 36.
[0041] The inside of the dehydrator 313 is provided with molecular sieve which can adsorb water in the methylal solution to further purify the methylal, so as to obtain methylal product with purity of more than 99.999%.
[0042] Further, the atmospheric recovery rectifying tower 4 is a plate tower with effective plate number of 30-50. In the direction from top to bottom, the atmospheric recovery rectifying tower 4 comprises a fourth top condensing section, a fourth rectifying section 46, a fourth separation section 47, a fourth stripping section 48, and a fourth reboiler 49. The fourth top condensing section comprises a fourth condenser 41, a fourth reflux tank 42, a fourth reflux pump 43 and a fourth reflux pipe 44 connected in sequence by pipes, the fourth condenser 41 is connected with the steam outlet at the top of the atmospheric recovery rectifying tower 4 by a pipe, and the liquid outlet of the fourth reflux pipe 44 is connected with the liquid return port at the top of the atmospheric recovery rectifying tower 4. The fourth reflux pipe 44 is provided with a fourth discharge pipe 45 at a branch, and the fourth discharge pipe 45 is connected with the second feed inlet 210 of the primary pressurized rectifying tower 2. The feed inlet of the fourth reboiler 49 is connected with the discharge port at the bottom of the atmospheric recovery rectifying tower 4 by a pipe, and the discharge port of the fourth reboiler 49 is connected with the material return port at the bottom of the atmospheric recovery rectifying tower 4 by a pipe. The atmospheric recovery rectifying tower 4 is provided with a fourth feed inlet 411 which is located at the middle part between the fourth rectifying section 46 and the fourth separation section 47, and the discharge end of the second discharge pipe 26 and the discharge end of the third discharge pipe 36 are both connected with the fourth feed inlet 411. The bottom of the atmospheric recovery rectifying tower 4 is further provided with a methanol discharge pipe 410, the methanol discharge pipe 410 is provided with a fourth water pump, and the discharge end of the methanol discharge pipe 410 is connected with the first feed inlet 111. The operating pressure of the atmospheric recovery rectifying tower 4 is atmospheric pressure, the top temperature is 40-45℃, and the bottom temperature is 60-65℃. The reflux ratio of the atmospheric recovery rectifying tower 4 is 1-5.
[0043] It can be understood that the remaining part of the methylal-methanol mixture extracted from the primary pressurized rectifying tower 2 and the secondary pressurized rectifying tower 3 is transported into the atmospheric recovery rectifying tower 4 through the fourth feed inlet 411, the atmospheric recovery rectifying tower 4 is operated under atmospheric pressure rectification, the atmospheric methylal-methanol azeotrope is extracted from the top of the atmospheric recovery rectifying tower 4, the methanol solution is extracted from the bottom of the atmospheric recovery rectifying tower 4, the atmospheric methylal-methanol azeotrope forms the methylal-methanol mixture after condensation, part of the methylal-methanol mixture is refluxed to the atmospheric recovery rectifying tower 4, and the remaining part of the methylal-methanol mixture is transported into the primary pressurized rectifying tower 2 to be further separated. The methanol solution extracted from the bottom is transported to the first feed inlet 111 to be used as the raw material source of the atmospheric catalytic rectifying tower 1, so as to achieve the purpose of material recycling.
[0044] Application Example 1
[0045] Combination Figure 1The utility model discloses a high purity methylal production equipment, which comprises the following steps:
[0046] S10, the fresh formaldehyde aqueous solution (feed 1) with 40% of the mass fraction of formaldehyde, the fresh methanol (feed 2) with 99.9% of the purity, and feed 3 (the methanol solution recovered from the normal pressure recovery rectification tower 4, see step S40) are input into the normal pressure catalytic rectification tower 1 from the first feed port 111, wherein the flow rate of the fresh formaldehyde aqueous solution is 1757.812 kg / h, the flow rate of the fresh methanol is 1500 kg / h, and the flow rate of feed 3 is 181.422 kg / h. 3 The normal pressure catalytic rectification tower 1 is filled with 2m Amberstly-70 sulfonic resin solid acid catalyst in the first reaction section 17. The inner diameter of the normal pressure catalytic rectification tower 1 is 1000 mm, the effective number of plates is 60, the spacing between two adjacent plates is 300 mm, the number of plates in the first rectification section 16 is 16, the number of plates in the first reaction section 17 is 25, and the number of plates in the first stripping section 18 is 19. The operating pressure of the normal pressure catalytic rectification tower 1 is normal pressure, the reflux ratio is 1.8, the top temperature is 42 DEG C, and the bottom temperature is 100 DEG C. After the catalytic rectification of the normal pressure catalytic rectification tower 1, the generated methylal-methanol azeotrope is collected from the top, and after condensation, the methylal-methanol mixture (in the methylal-methanol mixture, the methylal is 90.6wt%) is formed. Part of the methylal-methanol mixture refluxes, and the rest of the methylal-methanol mixture is transported to the primary pressurized rectification tower 2 through the first discharge pipe 15 to perform pressurized rectification, wherein the top discharge (the methylal is 90.6wt%) of the normal pressure catalytic rectification tower 1 is collected at a flow rate of 1962.673 kg / h, and then pumped to the primary pressurized rectification tower 2. The water generated in the reaction and the water brought in by the formaldehyde aqueous solution are collected at the bottom and discharged from the bottom of the first catalytic rectification tower at a flow rate of 1476.561 kg / h as process waste water.
[0047] S20, the methylal-methanol blend delivered by the first discharge pipe 15 and the methylal-methanol blend delivered by the fourth discharge pipe 45 are introduced into the first pressurized rectifying column 2 through the second feed inlet 210, wherein the flow rate of the methylal-methanol blend delivered by the first discharge pipe 15 is as described in step S10, and the flow rate of the methylal-methanol blend delivered by the fourth discharge pipe 45 is as described in step S40. The first pressurized rectifying column 2 has an inner diameter of 800 mm, an effective number of plates of 30, a spacing between adjacent plates of 300 mm, a number of plates in the second rectifying section 27 of 9, a number of plates in the second separation section 28 of 11, and a number of plates in the second stripping section 29 of 10. The first pressurized rectifying column 2 is operated at a pressure of 0.8 MPa, a reflux ratio of 2, a top temperature of 110°C, and a bottom temperature of 120°C. The methylal-methanol azeotrope is generated by the pressurized rectification of the first pressurized rectifying column 2, and the generated methylal-methanol azeotrope is collected from the top of the column, condensed to form the methylal-methanol blend (methylal 81.9 wt%), part of which is returned to the column as reflux, and the rest of which is pumped out of the column by the second discharge pipe 26 to the atmospheric recovery rectifying column 4 for rectification. The top discharge (methylal 81.9 wt%) of the first pressurized rectifying column 2 is collected at a flow rate of 1733.505 kg / h and then pumped into the atmospheric recovery rectifying column 4. The methylal solution (methylal 99.9 wt%) generated by the pressurized rectification is collected at the bottom of the column, and the methylal solution at the bottom is collected from the second methylal solution discharge pipe 212 at a flow rate of 1788.831 kg / h and then delivered to the second pressurized rectifying column 3.
[0048] S30, the methylal-methanol blend delivered by the second methylal solution take-out pipe 212 enters the second pressurized rectification column 3 through the third feed inlet 39, wherein the flow rate of the methylal-methanol blend delivered by the second methylal solution take-out pipe 212 is as described in step S20. The second pressurized rectification column 3 has an inner diameter of 800 mm, an effective number of plates of 35, a spacing between adjacent plates of 500 mm, a number of plates in the third rectification section 37 of 10, a number of plates in the third separation section 38 of 13, and a number of plates in the third stripping section 310 of 12. The second pressurized rectification column 33 operates at a pressure of 1.5 MPa, a reflux ratio of 2.6, a top temperature of 130°C, and a bottom temperature of 140°C. The methylal-methanol azeotrope generated by the pressurized rectification of the second pressurized rectification column 3 is taken out from the top, and after condensation, forms a methylal-methanol blend (in the methylal-methanol blend, methylal 76.4 wt%). Part of the methylal-methanol blend is refluxed, and the rest of the methylal-methanol blend is pumped by the third take-out pipe 36 into the atmospheric recovery rectification column 4 for rectification. The top take-out of the second pressurized rectification column 3 (methylal 76.4 wt%) is taken out at a flow rate of 7.58 kg / h, and then delivered into the atmospheric recovery rectification column 4. The methylal solution (in the methylal solution, methylal 99.99 wt%) generated after pressurized rectification is accumulated at the bottom, and the bottom methylal solution is taken out by the third methylal solution take-out pipe 312 at a flow rate of 1781.251 kg / h, and then delivered into the dehydrator 313 containing molecular sieves, which can absorb water to produce high-purity methylal products.
[0049] S40, the methylal-methanol blend delivered through the second discharge pipe 26 and the methylal-methanol blend delivered through the third discharge pipe 36 are fed into the atmospheric recovery rectification column 4 through the fourth feed port 411, wherein the flow rate of the methylal-methanol blend delivered through the second discharge pipe 26 is as described in step S20, and the flow rate of the methylal-methanol blend delivered through the third discharge pipe 36 is as described in step S30. The atmospheric recovery rectification column 4 has an inner diameter of 800 mm, an effective number of plates of 30, a spacing between adjacent plates of 350 mm, a number of plates in the fourth rectification section 46 of 9, a number of plates in the fourth separation section 47 of 12, and a number of plates in the fourth stripping section 48 of 9. The atmospheric recovery rectification column 4 operates at an atmospheric pressure, a reflux ratio of 1.8, a top temperature of 43℃, and a bottom temperature of 62℃. Through the rectification of the atmospheric recovery rectification column 4, a methylal-methanol azeotrope is generated, the generated methylal-methanol azeotrope is collected from the top of the column, and after condensation, a methylal-methanol blend (containing 91.4 wt% of methylal) is formed. Part of the methylal-methanol blend is refluxed, and the rest of the methylal-methanol blend is pumped out through the fourth discharge pipe 45 to the primary pressurized rectification column 2 for rectification. The overhead of the atmospheric recovery rectification column 4 (containing 91.4 wt% of methylal) is collected at a flow rate of 1559.663 kg / h and then delivered into the primary pressurized rectification column 2. After rectification, a methanol solution is generated at the bottom of the column, and the methanol solution at the bottom is collected from the methanol collection pipe 410 at a flow rate of 181.422 kg / h and then delivered into the first feed port 111.
[0050] It is measured that the mass fraction of methylal in the high-purity methylal product prepared in step S30 is ≥99.999%, and the mass fractions of water and methanol are both less than 10 ppm.
[0051] The above merely illustrates the exemplary embodiments of the present application, and does not limit the patent scope of the present application. Any equivalent structural transformation or direct / indirect application in other related technical fields within the technical concept of the present application and the content of the present application specification and drawings are included in the patent protection scope of the present application.
Claims
1. A high-purity methylal production equipment, characterized in that, include: An atmospheric catalytic distillation tower having a first feed inlet, a first reflux pipe provided at the top of the atmospheric catalytic distillation tower, a first reboiler provided at the bottom of the tower, and a first discharge pipe provided on a branch of the first reflux pipe; a first-stage pressurized distillation tower having a second feed port connected to the discharge end of the first discharge pipe, a second gas outlet pipe and a second reflux pipe provided at the top of the first-stage pressurized distillation tower, a second methylal solution extraction pipe provided at the bottom of the tower, the discharge end of the second gas outlet pipe connected to the heat exchange medium inlet of the first reboiler, and the second reflux pipe connected to the heat exchange medium outlet of the first reboiler; The two-stage pressurized distillation tower has a third feed port connected to the discharge end of the second methylal solution extraction pipe, and a third methylal solution extraction pipe is provided at the bottom of the two-stage pressurized distillation tower.
2. The high-purity methylal production equipment according to claim 1, wherein The high-purity methylal production equipment also includes a normal pressure recovery distillation tower, a second discharge pipe is provided on the branch of the second reflux pipe, the normal pressure recovery distillation tower has a fourth feed port connected to the discharge end of the second discharge pipe, and a methanol production pipe is provided at the bottom of the normal pressure recovery distillation tower, and the discharge end of the methanol production pipe is connected to the first feed port.
3. The high-purity methylal production equipment according to claim 2, wherein The top of the secondary pressurized distillation tower is provided with a third gas outlet pipe and a third reflux pipe, and the bottom of the atmospheric recovery distillation tower is provided with a fourth reboiler, the discharge end of the third gas outlet pipe is connected to the heat exchange medium inlet of the fourth reboiler, and the third reflux pipe is connected to the heat exchange medium outlet of the fourth reboiler.
4. The high-purity methylal production equipment according to claim 3, characterized in that: The third reflux pipe is branched onto a third discharge pipe, and a discharge end of the third discharge pipe is connected to the fourth feed port.
5. The high-purity methylal production equipment according to claim 3, characterized in that: A third reflux tank and a third reflux pump are sequentially arranged between the heat exchange medium outlet of the fourth reboiler and the third reflux pipe.
6. The high-purity methylal production equipment according to claim 2, characterized in that: The top of the atmospheric pressure recovery distillation tower is provided with a fourth condensing section, and the fourth condensing section includes a fourth condenser, a fourth reflux tank, a fourth reflux pump, and a fourth reflux pipe arranged in sequence. The air inlet end of the fourth condenser is connected to the steam outlet at the top of the atmospheric pressure recovery distillation tower, and the liquid outlet end of the fourth reflux pipe is connected to the liquid return port at the top of the atmospheric pressure recovery distillation tower.
7. The high-purity methylal production equipment according to claim 1, characterized in that: The atmospheric catalytic distillation tower is a plate tower with 60 to 100 effective plates; and / or The first-stage pressure distillation tower and the second-stage pressure distillation tower are plate towers or packed towers.
8. The high-purity methylal production equipment according to claim 1, characterized in that: From top to bottom, the atmospheric catalytic distillation tower includes a first distillation section, a first reaction section, and a first stripping section arranged in sequence, the first reaction section is provided with a solid acid catalyst; the first feed port is located between the first distillation section and the first reaction section.
9. The high-purity methylal production equipment according to claim 1, characterized in that: The top of the atmospheric pressure catalytic distillation tower is provided with a first condensing section, which includes a first condenser, a first reflux tank, a first reflux pump, and the first reflux pipe arranged in sequence. The air inlet end of the first condenser is connected to the steam outlet at the top of the atmospheric pressure catalytic distillation tower through a pipeline, and the liquid outlet end of the first reflux pipe is connected to the liquid return port at the top of the atmospheric pressure catalytic distillation tower.
10. The high-purity methylal production equipment according to claim 1, characterized in that: A second reflux tank and a second reflux pump are sequentially arranged between the heat exchange medium outlet of the first reboiler and the second reflux pipe.