阅读说明：本技术 一种连续萃取精馏分离二甲基硫醚、甲醇水溶液的方法 (Method for separating dimethyl sulfide and methanol aqueous solution by continuous extractive distillation ) 是由 杨金杯 王杨 程锦添 余美琼 陈玉成 王兆宇 张明文 于 2020-07-16 设计创作，主要内容包括：本发明涉及一种连续萃取精馏分离二甲基硫醚、甲醇水溶液的方法,其具体如下：以待分离溶液中已有的组分水作为萃取剂,与含二甲基硫醚、甲醇和水的待分离溶液分别从萃取精馏塔的萃取剂进料口和萃取精馏塔的待分离溶液进料口进入萃取精馏塔内；萃取精馏塔塔釜的含甲醇的萃取剂溶液从甲醇精馏塔的进料口进入甲醇精馏塔内,进行萃取剂回收,甲醇精馏塔的塔顶分离出纯度99.9wt％以上的甲醇产品,本发明利用待分离溶液中已存在的组分水为萃取剂,有效地避免传统萃取精馏引入额外组分而影响产品质量的弊端,是一种高效节能的分离装置,该装置具有分离效率高、选择性高、能耗低和设备投资少等优点。(The invention relates to a method for separating dimethyl sulfide and methanol aqueous solution by continuous extractive distillation, which comprises the following steps: taking the existing component water in the solution to be separated as an extracting agent, and respectively feeding the component water and the solution to be separated containing dimethyl sulfide, methanol and water into an extractive distillation tower from an extracting agent feeding port of the extractive distillation tower and a solution to be separated feeding port of the extractive distillation tower; the invention uses the existing component water in the solution to be separated as the extractant, effectively avoids the defect that the product quality is influenced by introducing additional components in the traditional extractive distillation, is a high-efficiency and energy-saving separation device, and has the advantages of high separation efficiency, high selectivity, low energy consumption, low equipment investment and the like.)

1. A method for separating dimethyl sulfide and methanol aqueous solution by continuous extractive distillation is characterized by comprising the following steps: step S1: raw materials to be separated enter a feeding preheater (E1) for preheating through a raw material feeding pipe (PL1) to be separated, the preheated materials enter the lower part of an extraction rectifying tower (T1) through a solution feeding pipe (PL2) to be separated, extractant water enters the upper part of the extraction rectifying tower (T1) from an extractant circulating pipe (PL14) for extraction, rectification and separation are carried out, steam rising from the top of the extraction rectifying tower (T1) realizes phase change through an extraction rectifying tower condenser (E3), the condensed materials are dimethyl sulfide products, one part of the dimethyl sulfide products flow back into the extraction rectifying tower (T1) from an extraction rectifying tower return pipe (PL4) at the top of the extraction rectifying tower (T1), the other part of the dimethyl sulfide products flow out through a dimethyl sulfide product discharging pipe (PL5), liquid falling from the bottom of the extraction rectifying tower (T1) is methanol water solution, one part of the methanol water flows into an extraction rectifying tower reboiler (E2) from an extraction rectifying tower reboiler inlet pipeline (PL6) and returns to the bottom of the extraction rectifying tower (1) for vaporization and distillation, providing energy for the rectification and separation of the extractive distillation tower (T1), and enabling the other part of the energy to enter a methanol rectification tower (T2) from a discharge pipe (PL7) of the extractive distillation tower kettle;

step S2: the methanol water solution descending at the bottom of the extraction rectifying tower (T1) enters a methanol rectifying tower (T2) for rectification through an extraction rectifying tower kettle discharge pipe (PL7), the steam ascending at the top of the methanol rectifying tower (T2) realizes phase change through a methanol rectifying tower condenser (E5), the condensed material methanol product is obtained, one part of the methanol product reflows into the tower from a methanol rectifying tower return pipe (PL9) at the top of the methanol rectifying tower (T2), the other part of the methanol product is extracted through a methanol product discharge pipe (PL10), the liquid descending at the bottom of the methanol rectifying tower (T2) is extractant water, one part of the liquid enters the methanol rectifying tower (E4) from a methanol rectifying tower reboiler inlet pipeline (PL11) to be heated and vaporized and then returns to the bottom of the methanol rectifying tower (T2) to provide energy for the rectification separation of the methanol rectifying tower (T2), and the other part of the methanol rectifying tower discharge pipe (PL12) is discharged to a feed preheater (E1), the material in the bottom of the methanol rectifying tower cooled by the raw material to be separated in the feed preheater (E1) flows out through a cooled discharge pipe (PL13), part of the material enters the upper part of the extractive rectifying tower (T1) through an extractant circulating pipe (PL14), and the other part of the material is discharged through a waste water discharge pipe (PL 15).

2. The method for continuous extractive distillation separation of dimethyl sulfide and aqueous methanol solution as claimed in claim 1, wherein the internal components of the extractive distillation column (T1) are trays or packing, the number of theoretical plates is 32-45, the operating pressure is 100-400 kPa, the reflux ratio at the top of the column is 1.2-4.8, the volume ratio of the feed of the extractant to the solution to be separated is 0.1-1.5, the temperature at the top of the column is 37-85 ℃, and the temperature at the bottom of the column is 80-125 ℃.

3. The method for continuous extractive distillation separation of dimethyl sulfide and methanol aqueous solution as claimed in claim 1, wherein the methanol distillation column (T2) has column plate or packing as internal parts, theoretical plate number of 22-42, operation pressure of 100-150 kPa, overhead reflux ratio of 1.8-6.5, overhead temperature of 64-76 ℃ and bottom temperature of 100-115 ℃.

Technical Field

The invention relates to the field of solvent recovery, in particular to a method for separating dimethyl sulfide and methanol aqueous solution by continuous extractive distillation.

Background

2- (4-chlorophenyl) -3-cyclopropyl-1, 2-epoxybutane was a yellow oily liquid with CAS number: 94301-26-9, formula: c₁₃H₁₅ClO, molecular weight: 222.72, it is mainly used as an intermediate for synthesizing cyproconazole which is an agricultural bactericide; in the production process of 2- (4-chlorphenyl) -3-cyclopropyl-1, 2-epoxybutane, p-chlorobenzaldehyde, ethylene glycol monomethyl ether, triethyl phosphite, trimethyl orthoformate, dimethyl sulfoxide, dimethyl sulfide and the like are used as raw materials, the reaction process is accompanied with the generation of water, methanol and the like, after the reaction is finished, light fractions are distilled out, and the distilled mixed solution comprises the following components: 16-32 wt% of dimethyl sulfide, 22-34 wt% of methanol and 34-62 wt% of water; the mixed solution is required to be separated, so that the content of dimethyl sulfide is more than 99.9 wt%, and the content of methanol is more than 99.9 wt%, so as to meet the requirements of recycling and selling.

For the mixed liquid generated, the boiling points of dimethyl sulfide (the boiling point is 37.3 ℃), methanol (the boiling point is 64.7 ℃) and water (the boiling point is 100 ℃) have large difference, the separation of the three substances can be realized by common rectification of two towers, but the dimethyl sulfide and the methanol can form a homogeneous minimum azeotrope under normal pressure, the azeotropic point is 35.0 ℃, and the content of the methanol in the azeotropic composition is 9.1% (mass fraction, the same below), therefore, the separation of the dimethyl sulfide, the methanol and the water can not be carried out by the conventional rectification, various technologies for separating the azeotropic mixture, such as azeotropic rectification or extractive distillation, are required, however, the azeotropic rectification or the extractive distillation needs to introduce a third component as an entrainer or an extractant, so that the dimethyl sulfide can not avoid introducing other impurities when being recycled, and further influences the intermediate 2- (4-chlorophenyl) -3-cyclopropyl-1, quality of 2-epoxybutane.

Disclosure of Invention

Technical problem to be solved

In order to solve the problems in the prior art, the invention provides a method for separating dimethyl sulfide and methanol aqueous solution by continuous extractive distillation, which selects the existing component water in the solution to be separated as an extracting agent, and separates the dimethyl sulfide and the methanol in the solvent by extractive distillation, so that the purity of the dimethyl sulfide and the methanol is respectively more than 99.9 wt%, and the purposes of recycling the dimethyl sulfide and selling the methanol are realized.

(II) technical scheme

In order to achieve the purpose, the invention adopts the main technical scheme that:

a method for separating dimethyl sulfide and methanol aqueous solution by continuous extractive distillation comprises the following steps: step S1: the method comprises the following steps that raw materials to be separated enter a feeding preheater through a raw material feeding pipe to be separated for preheating, the preheated materials enter the lower part of an extraction rectifying tower through a solution to be separated feeding pipe, extractant water enters the upper part of the extraction rectifying tower from an extractant circulating pipe for extraction, rectification and separation, steam rising from the top of the extraction rectifying tower realizes phase change through a condenser of the extraction rectifying tower, the condensed materials are dimethyl sulfide products, one part of the condensed materials flow back into the extraction rectifying tower from a reflux pipe of the extraction rectifying tower at the top of the extraction rectifying tower, the other part of the condensed materials is extracted through a dimethyl sulfide product discharging pipe, descending liquid at the bottom of the extraction rectifying tower is methanol aqueous solution, one part of the condensed materials enters the bottom of the extraction rectifying tower from an inlet pipeline of a reboiler of the extraction rectifying tower, is heated and vaporized and then returns to the bottom of the extraction rectifying tower to provide energy for the rectification and separation of the extraction rectifying tower, and;

step S2: the descending methanol water solution at the bottom of the extraction rectifying tower enters a methanol rectifying tower for rectification through a discharging pipe at the bottom of the extraction rectifying tower, the steam ascending at the top of the methanol rectifying tower realizes phase change through a condenser of the methanol rectifying tower, a material methanol product obtained by condensation flows back into the tower from a return pipe of the methanol rectifying tower at the top of the methanol rectifying tower, the other part is extracted through the discharging pipe of the methanol product, the descending liquid at the bottom of the methanol rectifying tower is extractant water, one part enters a reboiler of the methanol rectifying tower from an inlet pipeline of the reboiler of the methanol rectifying tower to be heated and vaporized and then returns to the bottom of the methanol rectifying tower to provide energy for the rectifying and separating of the methanol rectifying tower, the other part is discharged to a feeding preheater from the discharging pipe at the bottom of the methanol rectifying tower, the material at the bottom of the methanol rectifying tower cooled by the raw material to be separated in the feeding preheater flows out through the discharging pipe after being cooled, and the other part, the other part is discharged through a waste water discharge pipe.

Furthermore, the internal part type of the extraction and rectification tower is a tower plate or a filler, the number of theoretical plates is 32-45, the operation pressure is 100-400 kPa, the reflux ratio of the tower top is 1.2-4.8, the feeding volume ratio of the extracting agent to the solution to be separated is 0.1-1.5, the temperature of the tower top is 37-85 ℃, and the temperature of the tower kettle is 80-125 ℃.

Furthermore, the methanol rectifying tower has internal parts of tower plates or fillers, the number of theoretical plates is 22-42, the operating pressure is 100-150 kPa, the reflux ratio at the top of the tower is 1.8-6.5, the temperature at the top of the tower is 64-76 ℃, and the temperature at the bottom of the tower is 100-115 ℃.

(III) advantageous effects

The invention has the beneficial effects that: 1. the existing component water in the solution to be separated is selected as an extracting agent, the separation of dimethyl sulfide, methanol and water in the solution is effectively realized by adopting an extraction rectification process, the problem of azeotropic separation of dimethyl sulfide and methanol in a separation system is solved, and the influence of other components on the purity of dimethyl sulfide and methanol is avoided.

2. Compared with the traditional process for removing alcohol by intermittent extraction with a large amount of water, the device for separating dimethyl sulfide and methanol aqueous solution by adopting the extractive distillation process can save the energy consumption by 32-48%, the equipment investment by 22-35% and the wastewater discharge by 85%.

3. By adopting the device, the purity of the dimethyl sulfide and the methanol can be respectively more than 99.9 wt%.

Drawings

Fig. 1 is a schematic overall structure diagram of an embodiment of the present invention.

Detailed Description

For the purpose of better explaining the present invention and to facilitate understanding, the present invention will be described in detail by way of specific embodiments with reference to the accompanying drawings.

The method for separating dimethyl sulfide and methanol aqueous solution by continuous extractive distillation of one embodiment of the invention is shown in figure 1, and comprises the following separation steps: taking the existing component water (water is a specific component) in the solution to be separated as an extracting agent, respectively feeding the extracting agent and the solution to be separated containing dimethyl sulfide, methanol and water into an extraction rectifying tower T1 from an extracting agent feeding hole of the extraction rectifying tower T1 and a solution to be separated feeding hole of the extraction rectifying tower T1, separating a dimethyl sulfide product with the purity of more than 99.9 wt% at the top of the extraction rectifying tower T1, and obtaining an extracting agent solution containing methanol at the bottom of the extraction rectifying tower T1; the extractant solution containing methanol in the bottom of the extraction rectifying tower T1 enters a methanol rectifying tower T2 from a feed inlet of the methanol rectifying tower T2 for extractant recovery, methanol products with the purity of more than 99.9 wt% are separated from the top of the methanol rectifying tower T2, and the extractant water separated from the bottom of the methanol rectifying tower T2 is cooled, part of the extractant water returns to the extraction rectifying tower T1 for recycling and part of the extractant water is extracted.