[0036] In the following, the present invention will be further clarified with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. After reading the present invention, those skilled in the art have a great understanding of the present invention. Various equivalent modifications fall within the scope defined by the appended claims of this application.
[0037] In the synthesis product of polymethoxy dimethyl ether, there will always be a certain amount of formaldehyde, and the aldehyde-containing gas phase material flow is prone to formaldehyde self-polymerization during the atmospheric pressure condensation process to form paraformaldehyde. The inner walls of equipment and pipelines block the pipelines, forcing the distillation process to be unable to continue. For materials with higher aldehyde content, a little formaldehyde polymerization will occur in the first step of the separation process in the demethylalization process. The present invention is mainly a process device used for the refining and separation of formaldehyde-containing polymethoxy dimethyl ether. The process device is used to separate aldehyde-containing polymethoxy dimethyl ether materials, completely solving the problem of formaldehyde polymerization during the separation process. . And can get pure DMM3-6 products completely free of formaldehyde.
[0038] Such as figure 1 As shown, the outlet of the reaction unit (I) is connected to the inlet of the deacidification device (II), and the outlet of the deacidification device (II) is connected to the first normal pressure distillation column feed pipe 1 The inlet of the pressure fractionation tower (Ⅲ) is connected, the first atmospheric fractionation tower (Ⅲ) has no condensation equipment at the top of the tower, and the outlet of the gas phase material flow at the top of the tower is connected to the second tower through the first top gas phase material flow conveying pipe 2 A leaching absorption tower (Ⅴ) is connected to the gas-phase material flow inlet, and the first atmospheric fractionation tower (Ⅲ) tower kettle outlet is connected to the second atmospheric pressure fractionation tower (Ⅳ) through the second atmospheric pressure fractionation tower feed pipe 6 The feed port is connected, the second atmospheric fractionation tower (IV) has no condensation equipment at the top of the tower, and the gas phase material flow outlet at the top of the tower is connected to the second leaching absorption tower (VI) through the second top gas phase material flow conveying pipe 7 The gas-phase material inlet of the second normal pressure fractionation tower (IV) is connected with the inlet of the vacuum distillation tower (IX) through the feed pipe 13 of the vacuum distillation tower. The outlet at the top of the vacuum distillation tower (IX) is connected to the dehydration device (VII) through the outlet pipe 14 at the top of the vacuum distillation tower, and the outlet at the bottom of the vacuum distillation tower (IX) is through the vacuum rectification tower The feed pipe 15 is connected to the vacuum distillation column (X). The dehydration device (VII) is connected with the reaction unit.
[0039] The first leaching absorption tower (V) has a built-in packing layer, and the top of the tower is equipped with spray equipment, and is equipped with a tower top leaching liquid inlet, a tower top discharge outlet, a tower kettle leaching liquid outlet, and a tower kettle gas phase material Inflow. The outlet at the top of the tower is connected to the condensing device, and is connected to the inlet of the dehydration device through the outlet pipe 16 at the top of the leaching absorption tower. The outlet of the tower kettle eluent is connected to the first leaching absorption tower kettle thermostatic elution liquid delivery pipe 3, and the first leaching absorption tower kettle thermostatic leaching liquid delivery pipe 3 is divided into the first constant temperature eluent delivery pipe 3 Two pipes 4 and 5 for extraction of eluent. The first constant-temperature leaching liquid delivery pipe 4 is connected to the tower top leaching liquid inlet through the first constant-temperature leaching liquid feed pipe 12 to form a loop. The eluent extraction pipe 5 is connected to the inlet of the dehydration device.
[0040] The second leaching absorption tower (VI) has a built-in packing layer, and the top of the tower is provided with a spray device, and is provided with an inlet for the leaching liquid at the top of the tower, an outlet for the leaching liquid in the tower bottom, and an inlet for gas phase material in the tower bottom. The top of the tower eluent inlet is connected to the second constant temperature eluent feed pipe 10. The eluent outlet of the tower kettle is connected with the eluent inlet of the eluent storage tank (VIII) through the constant temperature eluent delivery pipe 8 of the second leaching absorption tower kettle. The eluent storage tank (VIII) is provided with an eluent inlet, a eluent outlet and a side eluent replenishment port. The eluent outlet of the eluent storage tank (Ⅷ) is connected with a constant temperature eluent storage tank delivery pipe 9, and the constant temperature eluent storage tank delivery pipe 9 is divided into a second constant temperature eluent feed at the end There are two pipes 10 and two second constant temperature leaching liquid delivery pipes 11, wherein the pipe 10 is connected with the tower top leaching liquid inlet to form a circulation loop. The second constant temperature washing liquid delivery pipe 11 and the first constant temperature washing liquid delivery pipe 4 are merged into the first constant temperature washing liquid feeding pipe 12.
[0041] The formaldehyde-containing polymethoxy dimethyl ether material obtained in the reaction unit is simply filtered to remove the solid catalyst and residual paraformaldehyde to obtain a clear material. Due to the high acid value of the material in the separation process, it is easy to cause product decomposition and polymerization in the tower, so the material is first subjected to the deacidification unit II for deacidification treatment, and the acid value of the material is controlled within 0-0.2mgKOH/g. The acidic material enters the first atmospheric fractionation tower Ⅲ through the feed pipe 1 of the first atmospheric fractionation tower (theoretical plate number is 20-40, the packing height is 10-30 meters) for light removal operation, and the tower top is 30-60 Obtain a formaldehyde-based gas-phase material stream mainly containing methylal at °C. The gas-phase material stream enters the first leaching absorption tower V (filling layer height 5-30 meters) through the first tower top gas-phase material stream conveying pipe 2 for leaching Condensation dealdehyde operation, a small amount of formaldehyde in the material stream is absorbed and dispersed in the eluent, thus effectively avoiding the cold polymerization problem of gas-phase formaldehyde in the direct condensation process. At the same time, the temperature of the leaching absorption tower V is controlled at 40-80℃ by controlling the temperature of the eluent. A large amount of methylal in the gas phase material flow will still maintain the gas phase through the first leaching absorption tower V at this temperature, and be condensed at the top of the tower. The condenser is condensed to obtain a methylal product without formaldehyde. The methylal is recycled to the dehydration unit VII through the discharge pipe 16 at the top of the leaching absorption tower for treatment and then returned to the reaction unit I as a raw material for reuse. The reactor of the first atmospheric fractionation tower III obtains mainly aldehyde-containing DMM2-8 products, and enters the second atmospheric fractionation tower IV (theoretical plate number 10-40, packing height 10-30 meters), at the top of the tower 70-110 A gas phase material stream containing a large amount of formaldehyde, mainly DMM2 and water, is obtained at ℃. The gas phase material flows through the second tower top gas phase material stream conveying pipe 7 and enters the second leaching absorption tower VI (packing layer height 5-30m) for leaching. In the condensation operation, all the formaldehyde in the gas phase material stream is absorbed and dispersed into the eluent by controlling the temperature of the eluent, so that the problem of cold polymerization of high-concentration formaldehyde gas can be effectively avoided. At the same time, all DMM2 and water are condensed into a liquid phase. Because DMM2 and water have a high capacity to dissolve formaldehyde, the separated DMM2 and water can be used as eluent to participate in the entire leaching cycle. The crude product of DMM3-8 containing a small amount of light components such as DMM2, water, paraformaldehyde, formaldehyde and trace formic acid is obtained from the fourth bottom of the second atmospheric fractionation tower. The product of the bottom of the column enters the feed pipe 13 of the vacuum distillation tower Vacuum distillation column Ⅸ (theoretical plate number 5-20, packing height 5-20 meters) at the top of the tower at an operating pressure of 0-30Kp to quickly separate residual DMM2, triformaldehyde, water, formaldehyde, formic acid and other light components, After being condensed, the top component of the tower enters the dehydration unit VII through the discharge pipe 14 at the top of the vacuum distillation tower, and then returns to the reaction unit as raw materials for reuse. Vacuum distillation tower Ⅸ tower kettle to obtain the crude product of DMM3-8 without formaldehyde, and enter the vacuum rectification tower Ⅹ through the feed pipe 15 of the vacuum distillation tower (theoretical plate number is 5-30, and the filler height is 10-30 meters ), further separation is carried out under the operating pressure of 0-15Kp, the pure DMM3-6 product is obtained at the top of the tower at 70-150℃, and the DMMn is obtained from the tower bottom> 6 products. The bottom product can also be recycled back to the reaction unit for reuse.
[0042] The leaching and condensing circulation system is mainly composed of leaching liquid transport pipelines 3-5, 8-12, the first leaching absorption tower V, the second leaching absorption tower VI, and the eluent storage tank Ⅷ. Among them, the second leaching absorption tower VI, the eluent storage tank Ⅷ, and the eluent delivery pipeline 8-10 constitute the first leaching condensation circulation system. The first leaching absorption tower V and the eluent delivery pipeline 3, 4 and 12 constitute the second rinsing condensation circulation system, and the two are connected by the second constant temperature rinsing liquid delivery pipe 11. The DMM2, which enters the first eluent circulation system through the second tower overhead gas-phase material flow delivery pipe 7, is used as a new eluent after water is condensed. The first leaching condensing cycle system is collected through the second constant temperature eluent delivery pipe 11. Part of the eluate enters the second circulation system for reuse, and finally the final aldehyde-containing eluate is sent to the dehydration device VII through the eluate extraction pipe 5 and then returned to the reaction unit for raw material utilization. At the same time, add new eluent to the eluent replenishment port on the side of the eluent storage tank Ⅷ to maintain the stability of the entire leaching condensing cycle system. The entire leaching and condensing circulation system effectively solves the problem of formaldehyde polymerization blocking the pipeline during the condensation of the aldehyde-containing gas phase material stream in the continuous separation process. The continuous operation of the entire production process is ensured, and at the same time, the substance in the polymethoxy dimethyl ether itself is used as the eluent, so that the final aldehyde-containing eluent can be used as a raw material to return to the reaction unit. At the same time, the organic combination of separation-rinsing system is realized, no other substances are introduced, and the formaldehyde in the product is 100% recycled, which is energy-saving and economical.
