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CN-122010685-A - Separation method and system of 1, 4-butanediol

CN122010685ACN 122010685 ACN122010685 ACN 122010685ACN-122010685-A

Abstract

The invention relates to the technical field of chemical industry and discloses a separation method and a separation system of 1, 4-butanediol, wherein the separation method comprises the following steps of concentrating and dehydrating a feed containing 1, 4-butanediol in a rectifying tower; introducing the concentrated solution at the bottom of the rectifying tower into a partition tower for refining, performing heat exchange between the gas phase component distilled out of the top of the partition tower and a heat exchanger at the bottom of the rectifying tower, and extracting 1, 4-butanediol from the discharge side of the partition tower. The invention utilizes the partition rectifying structure in the partition tower to realize effective flow division of light components and heavy components in the tower, the middle side line can directly extract high-purity 1, 4-butanediol, and simultaneously, the accumulation of near-boiling impurities in the side line area is reduced, the steam at the top of the partition tower is used for heating the tower kettle of the rectifying tower, thereby realizing the efficient coupling and recovery of heat between the towers, improving the heat transfer efficiency, obviously reducing the consumption of externally supplied steam, and further reducing the overall energy consumption in the separation process.

Inventors

  • LIANG XIAOQIANG
  • LIU CHUNDONG
  • ZHANG RONGGUANG
  • GAO XUESHUN
  • LIU PENG

Assignees

  • 万华化学(四川)有限公司

Dates

Publication Date
20260512
Application Date
20260105

Claims (10)

  1. 1. A separation method of 1, 4-butanediol is characterized by comprising the following steps: concentrating and dehydrating a feed containing 1, 4-butanediol in a rectifying tower; Introducing the concentrated solution at the bottom of the rectifying tower into a partition tower for refining, performing heat exchange between the gas phase component distilled out of the top of the partition tower and a heat exchanger at the bottom of the rectifying tower, and extracting 1, 4-butanediol from the discharge side of the partition tower.
  2. 2. A process for separating 1, 4-butanediol according to claim 1, wherein the operating pressure P1 at the top of the rectifying column, the pressure drop DeltaP of the rectifying column and the operating pressure P2 at the top of the dividing wall column are as follows 。
  3. 3. A process for the separation of 1, 4-butanediol according to claim 1 or 2, wherein the material fraction at the discharge side of the divided wall column is condensed by a condensing device and recycled to the discharge side; preferably, the materials below the discharge port on the discharge side of the dividing wall tower are introduced into a condensing device for condensation and then recycled to the position below the discharge port.
  4. 4. A process for the separation of 1, 4-butanediol according to any one of claims 1-3, characterized in that: The heat load Q 5 of the condensing device, the heat load Q 1 of the heat exchanger at the bottom of the rectifying tower, the reflux ratio R of the top of the partition tower, the discharge quantity D of the top of the partition tower and the vaporization enthalpy delta H of the top of the partition tower meet Q 5 ≤1.2×(R+1 )×D×ΔH-Q 1 .
  5. 5. A method for separating 1, 4-butanediol according to any one of claims 1-3, wherein the pressure at the top of the rectifying tower is 10-250 kPa, and/or the temperature at the top of the rectifying tower is 45-120 ℃, and/or the reflux ratio is 0.15-1, and/or the temperature at the bottom of the rectifying tower is 70-145 ℃.
  6. 6. A method for separating 1, 4-butanediol according to any one of claims 1-3, wherein the pressure at the top of the dividing wall column is 5-15 kPa, and/or the temperature at the top of the column is 146-170 ℃, and/or the reflux ratio at the top of the column is 10-50, and/or the temperature at the bottom of the column is 175-190 ℃, and/or the theoretical plate number is 30-100.
  7. 7. A separation system of 1, 4-butanediol is characterized by comprising: The rectifying tower and the tower bottom are connected with a heat exchanger; The feeding side of the dividing wall tower is connected with the discharge port of the tower kettle of the rectifying tower, and the discharge port of the top of the dividing wall tower is connected with the heat exchanger of the tower kettle of the rectifying tower and used for carrying out heat exchange with the heat exchanger.
  8. 8. The separation system of 1, 4-butanediol according to claim 7, wherein the discharging side of the dividing wall column is connected with a circulating pipeline, and the circulating pipeline is connected with a condensing device.
  9. 9. The separation system of 1, 4-butanediol according to claim 8, wherein a discharge port for extracting 1, 4-butanediol is formed on the discharge side of the dividing wall tower, and the circulating pipeline is connected below the discharge port.
  10. 10. The separation system of 1, 4-butanediol according to any one of claims 7-9, wherein the baffle plate in the baffle tower is arranged along the axial direction of the baffle plate, the upper end position of the baffle plate is positioned at 5% -30% of the tower plate from top to bottom of the baffle tower, and the lower end position of the baffle plate is positioned at 70% -95% of the tower plate from top to bottom of the baffle tower.

Description

Separation method and system of 1, 4-butanediol Technical Field The invention relates to the technical field of chemical industry, in particular to a method and a system for separating 1, 4-butanediol. Background 1, 4-Butanediol is an important basic organic chemical raw material, and is widely used for preparing degradable plastics such as thermoplastic elastic polyurethane (TPU), polytetrahydrofuran (PTMEG), spandex, polybutylene terephthalate (PBAT), polybutylene adipate (PBS) and the like. With the increasingly strict environmental protection requirements, the replacement of the traditional non-degradable plastics with the degradable plastics has become an industry development trend. However, the cost of the degradable material is high, wherein the high energy consumption in the 1, 4-butanediol production process is one of important factors for limiting the cost reduction and the scale popularization and application. Even in the process route of the alkynal method with relatively low cost at the present stage, the energy consumption of the refining link of the 1, 4-butanediol is still high, and the dual reduction of the energy consumption and the cost is realized through a new process and a new flow. In the prior art, various improvements are proposed for purifying the 1, 4-butanediol, for example, a technology is provided for improving the relative volatility between the near-boiling byproducts such as the 1, 4-butanediol and the 2- (4-hydroxybutoxy) tetrahydrofuran by introducing a compound extractant, so that a1, 4-butanediol product with extremely high purity is obtained, the loss of the 1, 4-butanediol is reduced, and the separation efficiency is higher. However, the technology needs to be provided with a special extraction tower and an extractant recovery and regeneration unit, the system flow is complex, the equipment investment is large, and the extractant circulation regeneration itself needs to consume a large amount of energy, so that the overall energy efficiency still has a space for improvement. The technical scheme also discloses a multi-effect rectification process, which connects a plurality of units of dehydration, desalination, residue removal, product purification and the like of the 1, 4-butanediol in series, optimizes heat to a certain extent in the system, and improves the recovery rate and purity of the 1, 4-butanediol by means of n-butanol recovery, residual liquid 1, 4-butanediol recovery and other measures. However, such systems typically include multiple rectifying columns, are complex in structure, and are relatively expensive in equipment investment and operation. Particularly, the towers such as dehydration and concentration are often arranged in parallel by adopting a pressurized dehydration tower and a reduced pressure dehydration tower, and meanwhile, the respective tower top condensers and tower kettle reboilers of the normal pressure concentration tower and the reduced pressure concentration tower are reserved, so that the high-efficiency matching of the condensation heat of the normal pressure tower top and the heat required by the reduced pressure tower is difficult to realize, and the heat cascade utilization is insufficient. In the alkynal method process, 1, 4-butanediol accounts for only about half of the 1, 4-butanediol mixture obtained by the reaction, and the rest is mainly water, n-butanol, hydroxybutanal, pentanediol, methyl-butanediol and other low-boiling-point substances, 2- (4-hydroxybutoxy) tetrahydrofuran, sodium formate, tar and other high-boiling-point substances. In the existing production, the conventional rectification process is adopted for refining, and the conventional rectification process generally comprises a concentration tower, a salt tower, a high-boiling tower, a low-boiling tower and other rectification towers, wherein water and butanol are separated in the concentration tower, and tar, high-boiling matters and low-boiling matters are removed in sequence. The content of1, 4-butanediol in the raw materials is only half, so that the evaporation capacity required by rectification is large, meanwhile, the boiling point of1, 4-butanediol is high, the boiling point of the 1, 4-butanediol is close to that of key impurities such as 2- (4-hydroxy butoxy) tetrahydrofuran, methyl-butanediol and the like, the separation difficulty is high, and the requirement of the product purity can be met by adopting a high reflux ratio, so that a large amount of steam is required to be consumed, the energy consumption of a rectification unit is often more than half of the energy consumption of the whole production process, and the production cost of the 1, 4-butanediol product is high. Disclosure of Invention The invention provides a method and a system for separating 1, 4-butanediol, which are used for solving the problems of high steam consumption, high energy consumption and high equipment investment caused by the fact that the refining flow of the 1, 4-buta