WO2020155571A1 - Separation and recycle system for water-containing organic waste liquid and organic solvent, and recycle method - Google Patents

Abstract

The present invention provides a separation and recycle system for a water-containing organic waste liquid and an organic solvent, and a recycle method, wherein the separation and recycle system consists of a distillation system and a pervaporation membrane separation system by means of a process pipeline connection. A packed tower is used as a rectifying tower, and a material inlet of the packed tower is provided in the center of a packed tower liquid distributor; and a damping structure is provided in a pervaporation membrane unit of the pervaporation membrane separation system. The separation and recycle system provided in the present invention is suitable for online dehydration and recycle of multiple kinds of water-containing and two or more azeotropic or non-azeotropic organic solvents as well as for separation and reuse of the organic solvents.

Description

Aqueous organic waste liquid and organic solvent separation and recovery system and recovery method Technical field

The invention belongs to the field of organic waste liquid recovery, and specifically relates to a miniaturized solvent recovery device and method.

Background technique

At present, with the rapid development of the global economy and the continuous improvement of the degree of integration, scientific research activities in various scientific fields in China have also entered the fast lane of rapid development, and the number of scientific research units has also doubled, especially in the fields of chemistry and life sciences. Very quickly, it has put forward higher requirements for the basic raw material industry and the environmental protection industry. The quality requirements of the solvents used in the research process are getting higher and higher, the amount used is increasing, the types of solvents are many, and the needs of each unit are relatively scattered. The collection and processing work is tedious.

In the pharmaceutical industry, preparative liquid chromatography systems have become the mainstream technology for separation and purification of drugs due to their outstanding advantages such as wide versatility, ease of operation, and high efficiency of separation. However, the headache for many companies is the production process. If the waste solvent is directly discharged, it will not only cause environmental pollution but also cause the production cost to remain high; in addition, due to the high requirements of the solvent quality of the preparative chromatography system, it is impossible for the waste solvent to be reused after simple recycling.

Most of the existing solvent recovery systems are industrialized devices with large processing capacity. The device has the characteristics of high policy threshold, long construction period, high investment cost, large area, and high system safety and operability requirements. Most of the solvent recovery devices are composed of simple evaporation and distillation processes, which only simply concentrate the organic solvent and reuse it. When the impurities accumulate to a certain concentration, they still need to be discharged. In fact, it is only a reduction in solvent recovery. The role of chemistry. Therefore, most of the devices can only be counted as organic solvent concentrators, and the organic solvents recovered from them cannot be used directly. Especially for enterprises that use preparative chromatography, the purity requirements of organic solvents are relatively high, and the organic solvents recovered by existing equipment cannot be directly used for preparative chromatography. At present, there is no equipment that can re-purify the recovered solvents to reuse standards. However, there are a huge number of pharmaceutical companies and large and medium-sized drug research institutions that use preparative chromatography. If a solvent recovery system that meets GMP for laboratories and R&D institutions can be developed The use of required miniaturized devices, small footprint, and simple operation are of great significance to the long-term survival of the enterprise, reducing the impact on the environment, and reducing production costs.

Summary of the invention

The purpose of the present invention is to provide a water-containing organic solvent purification and organic solvent separation and recovery system and corresponding methods, which are suitable for on-line dehydration and recovery of a variety of water-containing and two or more azeotropic or non-azeotropic organic solvents, as well as the separation and application of organic solvents.

The separation and recovery system provided by the present invention is composed of a rectification system and a pervaporation membrane separation system connected through a process pipeline;

The rectification system includes a quenching and tempering kettle, a rectification tower, a partial condenser, a total condenser and a product receiving tank one. The outlet of the tempering kettle is connected with the inlet of the rectification tower. The total condenser is set in the top body of the rectification tower, and the total condenser is set at the top of the rectification tower to condense the low-boiling components that have not been condensed by the partial condenser. The condensed product enters the product receiving tank 1, and a part of it is refluxed into the rectification tower;

The pervaporation membrane separation system includes a vaporizer, a vapor-liquid separator, a reheater, a pervaporation membrane unit, a permeate condenser, a product condenser, and a product receiving tank; the feed port of the vaporizer and the product receiving tank Both are connected with the product receiving tank 1, the outlet of the vaporizer is connected with the inlet of the vapor-liquid separator, the outlet of the vapor-liquid separator is connected with the inlet of the reheater, and the outlet of the reheater Connecting the membrane modules, the pervaporation membrane group is composed of 1 to 6 stages (the number of stages of the pervaporation membrane and the number of pervaporation membranes set in each stage are determined according to the separation system) pervaporation membrane units in series, Each unit is composed of 2-6 modules in parallel or in series. Each pervaporation membrane unit is equipped with a permeate condenser and a permeate tank. The permeate tank is connected with the rectification tower feed port of the rectification system or directly discharges waste. , The discharge port of the membrane module is connected to the product condenser and the product receiving tank.

Further, the rectification tower is a highly efficient and multifunctional packed tower. The tower is provided with a feed port at the top and the middle of the tower body, which can realize special rectification operations such as extractive distillation or azeotropic distillation. The rectification tower adopts side-line feed, and a feed port is set at the top and the middle of the tower body. The feed port is located above the center of the liquid distributor of the packed tower, and the liquid distributor is uniformly arranged on the disc by a disc The disc surface is provided with a groove connecting the diversion hole and the center point of the disc, and the path of the groove meets the requirement that the distance between each diversion hole and the center point of the disc is equal. Preferably, the diverting holes are cylindrical holes, and a top cap is provided on the top of each diverging hole, and the top cap is supported and fixed by a support column provided at the diverging orifice, so as to maintain a gap with the diverging orifice for ascending. The vapor phase passes. The top of the rectification tower is equipped with a built-in condenser, which can realize the gas phase discharge of the rectification tower. The condensation adopts 0～12℃ low temperature water, and the low temperature water is provided by the chiller; the tower body is made of 304 stainless steel, which can realize the addition of the rectification tower. Pressure, normal pressure and reduced pressure operation; the volume of the rectification tower bottom is 0.5-50L (set according to the processing capacity). At the same time, the feed port is set, and the third substance can be added to the tower kettle to realize the function of reactive distillation. In summary, the rectification tower has multi-functional characteristics, and its rectification process can realize different functions such as pressurized, normal pressure, vacuum rectification, extractive distillation, azeotropic distillation, and reactive distillation.

Preferably, the packing of the rectification tower is a high-efficiency bulk packing, which may be, but not limited to, theta-type or triangular spring packing formed by stainless steel wire mesh, glass ceramics and plastic materials.

Further, the rectification tower bottom adopts electricity, steam or heat conduction oil heating mode.

Further, a preheater for preheating materials is provided on the feed line of the rectification tower.

Further, the rectification system also includes an extraction/azeotroping agent storage tank for storing the extractant or azeotroping agent, and a feed pump for feeding the extractant or azeotroping agent into the rectification tower. By adding a third-party solvent (extractant/azeotroping agent), the relative volatility of the separated solvent can be changed and increased, so as to achieve the purpose of separation through rectification.

Further, an extraction/azeotroping agent cooler is provided on the pipeline between the extraction/azeotroping agent storage tank and the rectification tower feed port.

Further, the conditioning tank is a reaction tank with a stirring structure, which is used to initially separate the aqueous organic waste liquid by adding a chelating agent, so that the impurities and heavy components therein form a chelate, which is easier to separate during rectification .

Further, each membrane module of the pervaporation membrane unit is composed of several pervaporation membrane tubes (such as molecular sieve ceramic membrane tubes), cylindrical membrane shells and membrane partitions, and the membrane tubes are uniformly fixed in a plurality of On the fixed plate of the fixed hole, the fixed plate is located on the top of the membrane shell, one end of the membrane partition is fixed on the fixed plate, and the other end extends to the bottom of the membrane shell to evenly divide the space in the membrane shell into two communicating parts.

Further, in order to increase the permeation flux of the membrane tube, one of the following two settings can be selected:

(1) In the pervaporation membrane separation system, each pervaporation membrane tube is sheathed with a damping spring made of corrosion-resistant material (such as tetrafluoroethylene). Preferably, the length of the damping spring is equal to the length of the membrane tube. equal.

The function of the spring is embodied in the following two points. On the one hand, the spring increases the turbulence of the medium in the pervaporation membrane shell, so that the material is distributed in the radial direction of the membrane shell more uniformly, and backmixing is avoided as much as possible; on the other hand, Due to the disturbing action of the spring, the concentration polarization layer on the surface of the pervaporation membrane is greatly thinned, which greatly increases the mass transfer rate of the material. Therefore, the flux and separation efficiency of the pervaporation membrane are greatly improved through this damping setting.

(2) A plurality of damping strips are provided on the inner wall of the membrane shell and the surface of the diaphragm. The damping strip is composed of a mounting strip and a damping block uniformly arranged on the mounting strip at a certain distance. The inner wall of the membrane shell is provided with a mounting strip. The mounting groove of matching size, the mounting bar is embedded in the mounting groove to realize the fixation of the damping block. Preferably, the resistance block is shaped like a wedge, and the damping block protrudes in the direction of the airflow toward the inner space of the membrane shell. The function of the resistance block is to increase the resistance in the direction of the vapor flow, increase the turbulence of the vapor flow in the membrane shell, effectively reduce the influence of concentration polarization, and increase the residence time of the vapor in the membrane shell, thereby effectively increasing The flux of pervaporation membrane modules reduces the number of membrane modules and reduces the investment cost of membrane modules.

Further, the rectification tower and the vaporizer are both provided with a feed pump, and the rectification tower bottom is provided with a discharge pump.

Further, in the pervaporation membrane separation system, a back pressure valve is provided between the last-stage pervaporation membrane unit of the pervaporation membrane group and the product condenser (material vapor outlet).

The main driving force of pervaporation membrane separation is the pressure difference between the inside and outside of the membrane. The function of setting the back pressure valve is to increase the pressure of the material to be separated outside the membrane tube, increase the pressure difference between the inside and outside of the pervaporation membrane, and increase the permeation of moisture. The flux of vaporization membrane components to achieve fast and efficient separation. The molecular sieve membrane tube of the pervaporation membrane is operated in a vacuum state. During actual use, the membrane device is equipped with a vacuum pump to realize the vacuum operation in the membrane tube. The vacuum pump frequency conversion and the vacuum pump air inlet are equipped with a regulating valve to achieve vacuum adjustment and control. .

Further, a heat supplement is provided between the upper stage and the lower stage of the separation membrane of the pervaporation membrane module.

Further, in the pervaporation membrane separation system, the permeate tank is connected to a vacuum pump at the same time to keep the permeate condenser and the inner side of the membrane tube with a large and stable vacuum to ensure that the pervaporation membrane maintains a large pressure difference between the inside and the outside. Further increase the driving force of the pervaporation membrane separation process, so that the pervaporation membrane has a higher flux and separation efficiency.

Further, the vaporizer and the reheater are heating devices, so that the liquid can be vaporized into vapor to enter the pervaporation membrane module for separation operation.

Preferably, the recovery and separation system of the present invention is made of corrosion-resistant 304 material or 316L material.

The present invention provides a separation and recovery system based on the above that can be applied to a variety of water-containing and two or more azeotropic or non-azeotropic organic solvents on-line dehydration recovery and solvent separation and reuse (recovered organic solvents are used as new solvents and returned to the production section for use ), especially for systems that are azeotropic with water. The system is small in size, with a length of 1 to 5 meters, a width of 1 to 3 meters, and a height of 1.5 to 4 meters, saving space and the equipment is fully enclosed. The overall system is enclosed in a cabinet, and a very small amount of organic solvent that may escape can be drawn out in time by setting up an exhaust device to avoid the accumulation of organic solvents and improve the safety of the device. The entire device is made of stainless steel, and the connection between the device and the pipeline is flanged or quick-release clamp to ensure the sealing performance of the device. The operation process of the system is controlled by PLC to control the actions of relevant inlet and outlet valves, feeding pumps, and vacuum pumps, and adjust parameters such as temperature, pressure, and flow. If the PLC controller sends a control signal to the feed control valve, the control valve as an actuator will have a different opening according to the change of the controller signal. After the control valve, a flowmeter is set to measure the flow in real time, and the flow signal is sent to the controller According to the flow signal returned by the flowmeter, the controller sends the control signal to the regulating valve again after calculation, until the flowmeter measured by the flowmeter reaches the preset flow. The entire system is fully automated by PLC programming control, without manual operation.

The separation and recovery system of the present invention can be widely used but not limited to the polypeptide industry (acetonitrile, tetrahydrofuran, ethanol, methyl tert-butyl ether dehydration, methylene chloride, methanol recovery, etc.), electronics industry (isopropanol, butanone dehydration , Acetone recovery, etc.) and online recovery and application of laboratory waste organic solvents. The water content of acetonitrile, tetrahydrofuran, ethanol, isopropanol, methyl ethyl ketone, methanol, dichloromethane, and methyl tert-butyl involved in the above industries is suitable for this device, and two or more mixed solvents. Separation. After passing through the device, the content of organic solvent in wastewater is less than 0.1%.

The device can be widely used but not limited to the polypeptide industry (acetonitrile, methanol, DMF, tetrahydrofuran, ethanol dehydration, etc.), the electronics industry (isopropanol dehydration, etc.) and the online recovery and application of laboratory waste organic solvents, greatly reducing corporate solvents The amount of outsourcing and the amount of hazardous waste generated greatly reduce the production cost and environmental protection cost of the enterprise.

The separation and recovery method based on the above-mentioned separation and recovery system provided by the present invention includes the following steps: the water-containing organic solvent, or two azeotropic or non-azeotropic mixed solvents are tempered and then continuously enter the rectification tower through a pump to control the rectification tower The feed rate is 10-300L/h, the bottom temperature is 60-300℃, the top temperature is 40-200℃, the operating pressure of the tower is 10-300kPa, and the reflux ratio is 0.5-5. Through rectification, the solvent is Purify to more than 80wt%, enter the pervaporation membrane module for deep separation. The feed temperature of the pervaporation membrane module is 80～150℃, the feed volume is 0.5～50L/h, the operating pressure is 100～600kPa, and it is purified to the purity of organic solvent. ≥99.9% (wt).

The separation and recovery system of the present invention can be selected and used according to the components of the separated waste liquid and the need for separation purity.

1. The water-containing organic solvent is purified to more than 80% (wt), and then enters the pervaporation membrane module for deep dehydration. The purity of the dehydrated organic solvent is ≥99.9% (wt), and the organic solvent content of the discharged waste water is ≤0.1% after passing through the device.

2. Two solvents that do not azeotrope, the top of the high-efficiency rectification tower will get a lower boiling point organic solvent content ≥99% (wt), the bottom of the tower will get a second higher boiling point organic solvent content ≥ 99% (wt) ).

3. Two azeotropic organic solvents are added with extractant to obtain organic solvent with water content less than 20% at the top of the high-efficiency rectification tower, and the second organic solvent content at the bottom of the tower is ≥99% (wt).

According to the different processing capacity of the small solvent recovery device, the feed rate of the rectification device is 10 to 300 L/h, and the feed rate of the pervaporation membrane module is 0.5 to 50 L/h. In the recovery and separation system of the present invention, the waste gas generated in the recovery process is discharged to the treatment system through a pipeline through a negative pressure fan, and is discharged up to the standard through deep condensation, spray absorption and activated carbon adsorption.

Compared with the prior art, the present invention has the following beneficial effects:

1. In the recovery and separation system of the present invention, the entire recovery process is controlled by PLC. The recovery device is placed in a cabinet, and the cabinet is equipped with a ventilation device to draw out the very small amount of organic solvent that may escape in time to avoid the accumulation of organic solvent and improve the safety of the device Sex.

2. The recovery and separation system of the present invention realizes the closed operation of the device. The whole device is made of stainless steel, and the connection between the equipment and the pipeline adopts a flange or a quick-release clamp to ensure the sealing performance of the device. The rectification tower adopts advanced high Specification packing has the characteristics of high number of trays, large load, and high tray efficiency, which shortens the operation time and reduces the possibility of solvent volatilization and exposure.

3. In the recovery and separation system of the present invention, the condenser at the top of the rectification tower adopts negative pressure cryogenic operation to ensure maximum recovery of organic solvents and can reduce the outlet temperature of the product during the rectification process.

4. In the separation and recovery system of the present invention, the liquid distributor in the packed rectification tower solves the problem of uneven liquid flow distribution caused by side feeding. The vapor and liquid two-phase fluids on the horizontal section of the packed tower are evenly distributed, fully contacted, and transmitted. The mass and heat transfer efficiency is high, the pressure drop is small, it is not blocked, it is not easy to cause liquid foam entrainment and foaming, and the distillation efficiency is high.

5. In the separation and recovery system of the present invention, a damping spring is designed in the membrane module to increase the resistance in the direction of the steam flow, increase the turbulence of the steam flow in the membrane shell, and effectively reduce the influence of concentration polarization, and extend The residence time of the vapor in the membrane shell effectively increases the flux of the pervaporation membrane module, and reducing the number of membrane modules reduces the investment cost of the membrane modules. At the same time, the structure is simple, easy to manufacture, and low processing cost.

6. In the separation and recovery system of the present invention, the organic waste liquid first undergoes rectification, then passes through the pervaporation membrane, removes most of the water through rectification, and is further separated by the pervaporation membrane, which is beneficial to protect the pervaporation membrane and prolong its use. life.

7. The system of the present invention realizes the separation and purification of water-containing, azeotropic or non-azeotropic organic mixed solvent waste liquid. After purification, the purity of the organic solvent is ≥99.9% (wt), and the obtained organic solvent can be used directly. In particular, it meets the high purity requirements of organic solvents by enterprises that use preparative chromatography, and the system is small in size and space-saving. It is a miniaturized device suitable for laboratories, research and development institutions and GMP solvent reuse requirements, covering an area It is small, simple to operate, and saves a lot of solvent outsourcing costs, which is of great significance to the long-term survival of enterprises, reducing the impact on the environment, and reducing production costs.

Description of the drawings

Figure 1 is a schematic diagram of the overall structure of the separation and recovery system of the present invention;

Figure 2 is a cross-sectional view of the rectification tower of the present invention;

Figure 3 is a top view of the liquid distributor of the rectification column of the present invention.

Fig. 4 is a bottom view of the liquid distributor of the rectification tower of the present invention.

Fig. 5 is a schematic diagram of the split hole and the top cap on the liquid distributor of the rectification column of the present invention (only one split hole is shown in the figure).

Figure 6 is a top view of the membrane module of the present invention;

Figure 7 is a front view of the membrane module of the present invention;

Fig. 8 is a schematic diagram of the membrane of the set damping spring of the present invention.

In the picture, 1-conditioning kettle, 2-rectification tower, 3-condenser, 4-total condenser, 5-product receiving tank 1, 6-vapor-liquid separator, 7-vaporizer, 8-reheater , 9-pervaporation membrane group, 10-back pressure valve, 11-product condenser, 12-product receiving tank two, 13-permeate condenser, 14-permeate tank, 15-extraction/azeotrope tank, 16 -Extraction/azeotroping agent condenser, 17-preheater, 18-feed pump, 19-tower body, 20-tower kettle, 21-condenser, 22-liquid distributor, 22-1 disc, 22 -2 shunt hole, 22-3 groove, 22-4- top cap, 23-feed tube, 24-pervaporation membrane tube, 25-cylindrical membrane shell, 26-fixed disk, 27-partition, 28- Damping spring.

detailed description

The present invention will be further described in detail below through specific embodiments. However, those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. According to the technology or conditions described in the literature in the field or according to the product specification. The reagents or instruments used without the manufacturer's indication are all conventional products that are commercially available.

For the sake of simplicity of description, the term "rectification tower" in the present invention, without special instructions, on the basis of the improved structure of the present invention, can respectively refer to ordinary rectification towers, including pressurized rectification towers and atmospheric rectification towers. Tower, vacuum distillation tower, extractive distillation tower, azeotropic distillation tower, reactive distillation tower.

In the following embodiments, unless otherwise described, conventional equipment or components can be selected.

Example 1

The separation and recovery system is composed of a rectification system and a pervaporation membrane separation system connected through a process pipeline;

The rectification system includes a quenching and tempering reactor 1, a rectification tower 2, a partial condenser 3, a total condenser 4, and a product receiving tank 5. The outlet of the quenching and tempering reactor is connected with the inlet of the rectification tower The partial condenser is arranged in the top body of the rectification tower, and the total condenser is arranged at the top of the rectification tower to condense the low-boiling components that are not condensed by the partial condenser. The discharge port of the total condenser is arranged Split pipeline, make part of the condensed product enter the product receiving tank 1, and part of it will return to the rectification tower;

The pervaporation membrane separation system includes a vaporizer 7, a vapor-liquid separator 6, a reheater 8, a pervaporation membrane group 9, a permeate condenser 13, a product condenser 11, and a product receiving tank 12; Both the feed port and the product receiving tank two are connected with the product receiving tank one, the discharge port of the vaporizer is connected with the feed port of the vapor-liquid separator, and the discharge port of the vapor-liquid separator is connected with the feed port of the reheater. The discharge port of the reheater is connected to the membrane module. The pervaporation membrane group is composed of 1 to 6 pervaporation membrane units in series, each unit is composed of 2-6 modules in parallel, and each pervaporation membrane is configured with permeate condensation. The permeate tank is connected to the feed port of the rectification tower of the rectification system or is directly discharged, and the discharge port of the membrane module is connected to the product condenser and the product receiving tank.

The rectification tower is a packed tower. The rectification tower adopts side-line feed. A feed port is provided at the top and the middle of the tower body. The feed port is located above the center of the liquid distributor of the packed tower. The disc is composed of a plurality of diversion holes uniformly arranged on the disc, and the surface of the disc is provided with grooves connecting the diversion holes and the center point of the disc, and the path of the grooves meets that the distance between each diversion hole and the center point of the disc is equal. The splitting holes are cylindrical holes, and the top of each splitting hole is provided with a top cap, and the top cap is supported and fixed by a support column provided at the splitting orifice, so as to achieve a vapor phase that maintains a gap with the splitting orifice for rising. by. The packing of the rectification tower is θ-type packing formed by stainless steel wire mesh, triangular spring packing, glass ceramic or plastic material packing. The feed pipeline of the rectification tower is provided with a preheater for preheating materials; the tempering kettle is a reaction kettle with a stirring structure. The rectification system also includes an extraction/azeotroping agent storage tank 15 for storing an extractant or azeotroping agent, and a feed pump 18 for feeding the extractant or azeotroping agent into the rectification tower. An extraction/azeotroping agent cooler 16 is provided on the pipeline between the extraction/azeotroping agent storage tank and the feed port of the rectification tower. The rectification tower kettle adopts electricity, steam or heat conduction oil heating mode. A preheater 17 for preheating materials is provided on the feed line of the rectification tower.

In the pervaporation membrane separation system, the pervaporation membrane module is composed of a plurality of pervaporation membrane tubes, a cylindrical membrane shell and a membrane partition, and the membrane tubes are uniformly fixed on a fixed plate provided with a plurality of fixing holes The fixed disk is located on the top of the membrane shell, one end of the membrane partition is fixed on the fixed disk, and the other end extends to the bottom of the membrane shell to evenly divide the space in the membrane shell and the membrane tube into two communicating parts, the pervaporation In the membrane separation system, each pervaporation membrane tube is sheathed with a damping spring with an inner diameter of φ13 made of corrosion-resistant material (such as PTFE, etc.). The function of this spring is specifically reflected in the following two points. On the one hand, the spring is increased The turbulence of the medium in the pervaporation membrane shell makes the distribution of the material in the radial direction of the membrane shell more uniform, avoiding back mixing as much as possible; on the other hand, due to the disturbing action of the spring, the concentration of the pervaporation membrane surface is polarized The layer is greatly thinned, which greatly increases the mass transfer rate of the material. Therefore, the flux and separation efficiency of the pervaporation membrane are greatly improved through this damping setting.

In the pervaporation membrane separation system, a back pressure valve 10 is provided between the last group of pervaporation membrane units of the pervaporation membrane module and the product condenser. A heat supplement is arranged between the upper stage and the lower stage of the separation membrane of the pervaporation membrane module.

Example 2 Acetonitrile-water separation

Take the acetonitrile waste liquid in the polypeptide industry as an example to illustrate the operation method of a small solvent recovery device. The acetonitrile waste liquid (mixed solvent) of the polypeptide industry contains about 10-15% wt. acetonitrile and 85-90% wt. water (in this example, 15% wt. acetonitrile and 85% wt. water are used as an example), and also contains A small amount of high boiling point substances. The mixed solvent enters the rectification tower continuously at a flow rate of 100L/h (mass flow rate of 90.73kg/h) through the pump. The top of the rectification tower uses a built-in condenser to control the feed volume of circulating water according to the temperature at the top of the tower. The control is 88.4℃, the pressure control is 0.15MPa, the mass flow of gas phase produced at the top of the tower is 17kg/h, the mass composition of acetonitrile is 80.1%wt., the mass composition of water is 19.9%wt.; the control temperature of the tower kettle is 111.4℃, continuous The produced wastewater has a flow rate of 73.73 kg/h, and the content of acetonitrile in the wastewater is not higher than 500 ppm. In addition, some high-boiling impurity liquids are discharged from the device along with the wastewater for subsequent treatment.

The acetonitrile-water gas mixture from the top of the tower enters the first-stage pervaporation membrane (area about 1.5m ² ). The permeate side of the first-stage pervaporation membrane controls the vacuum to 10kPa, and the permeate passes through low-temperature water (7℃) The two-stage condensate cooling with chilled water (-20℃) is discharged into the first-stage permeate storage tank. The feed control temperature of the pervaporation membrane is 88.4℃, and the feed pressure is 0.15MPa. After the separation of the primary pervaporation membrane, the flow rate of the permeate is 3.09kg/h, and the content of acetonitrile is less than 500ppm. The excess liquid is discharged from the device as waste water; the mass composition of acetonitrile in the material passing through the first-stage pervaporation membrane is 98.7%, and the flow rate is 13.91 kg/h. After the acetonitrile-water mixed solvent is preheated to 100°C by the heater, it enters the second-stage pervaporation membrane (area about 2.5m ² ). The permeate side of the second-stage pervaporation membrane controls the vacuum degree of 10kPa, and the permeate passes through low temperature. The two-stage condensation cooling of water (7℃) and chilled water (-20℃) is discharged into the secondary permeate storage tank. After the separation of the secondary pervaporation membrane, the permeate flow rate is 0.3kg/h, Among them, the mass composition of acetonitrile is about 1%. After the permeate accumulates for a period of time, it is discharged into the permeate tank to further recover acetonitrile; the mass composition of acetonitrile in the material passing through the second-stage pervaporation membrane is 99.99%, and the flow rate is 13.61kg/ h. The obtained high-purity acetonitrile steam is condensed and cooled and then enters the acetonitrile product tank. The overall recovery rate of acetonitrile is ≥98%, and the recovered acetonitrile can fully meet the requirements for reuse. The acetonitrile content in the wastewater is less than or equal to 0.1%, which minimizes the amount of hazardous waste generated by the enterprise, and the amount of solvent recovered per year is 10 to 900 tons.

Example 3 THF-water separation

Take the tetrahydrofuran (THF) waste liquid of a pharmaceutical company as an example to illustrate the operation method of a small solvent recovery device. The THF waste liquid contains about 20-25%wt.THF and 75-80%wt. water (in this example, 20%wt. THF, 80%wt. water as an example), in addition, it also contains a small amount of high boiling point substances and a small amount of insoluble impurities. After the THF waste liquid is filtered to remove insoluble impurities, it is continuously fed into the rectification tower through a pump at a flow rate of 100L/h (mass flow rate of 98.78kg/h). The top of the rectification tower adopts a built-in condenser, and the circulation is controlled according to the top temperature. For the feed volume of water, the temperature at the top of the tower is controlled to 97.8°C, the pressure is controlled to 0.3MPa, the mass flow of gas phase produced at the top of the tower is 22kg/h, the mass composition of THF is 89.81%wt., and the mass composition of water is 10.19%wt.; The tower kettle has a controlled temperature of 133.6°C and continuously produces wastewater with a flow rate of 76.79kg/h. The content of THF in the wastewater is not higher than 500ppm. In addition, some high-boiling impurities are also discharged from the device along with the wastewater for subsequent treatment. The THF-water gas mixture produced at the top of the tower enters the first-stage pervaporation membrane (area about 1.0m ² ). The permeate side of the first-stage pervaporation membrane controls the vacuum to 10kPa, and the permeate passes through low-temperature water (7℃) The two-stage condensing and cooling of chilled water (-20°C) is discharged into the first-stage permeate storage tank. The feed control temperature of the pervaporation membrane is 97.8°C, the feed pressure is 0.3MPa, and it is separated by the first-stage pervaporation membrane. After the action, the flow rate of the permeate is 1.79kg/h, and the content of THF is less than 500ppm. The permeate is discharged from the device as waste water; the mass composition of THF in the material passing through the first-stage pervaporation membrane is 97.78%. It is 20.21kg/h. After the THF-water mixed solvent is preheated to 100°C by the heater, it enters the second-stage pervaporation membrane (area about 2.0m ² ). The permeate side of the second-stage pervaporation membrane controls the vacuum degree of 10kPa, and the permeate passes through low temperature. The two-stage condensation cooling of water (7℃) and chilled water (-20℃) is discharged into the secondary permeate storage tank. After the separation of the secondary pervaporation membrane, the permeate flow rate is 0.45kg/h, The mass composition of THF is about 1%. The permeate accumulates for a period of time and then is discharged into the permeate tank to further recover THF; the mass composition of THF in the material passing through the second-stage pervaporation membrane is 99.99%, and the flow rate is 19.75kg/ h. The obtained high-purity THF vapor is condensed and cooled and then enters the product tank. The overall recovery rate of THF is ≥98%, and the recovered THF can fully meet the requirements for reuse.

Example 4 Acetone-methanol separation

Take the acetone-methanol waste liquid of a pharmaceutical company as an example to illustrate the operation method of a small solvent recovery device. The waste liquid contains about 25-30% wt. acetone and 70-75% wt. water (in this example, 25% wt. acetone). , 75%wt. methanol as an example), and also contains a small amount of insoluble impurities. After the acetone-methanol waste liquid is filtered to remove insoluble impurities, it is continuously fed into the rectification tower through a pump at a flow rate of 100L/h (mass flow rate of 79.4kg/h). The top of the rectification tower adopts a built-in condenser. The temperature controls the feed volume of circulating water. Because the boiling points of methanol and acetone are close, water should be added as the extractant during the distillation process for extractive distillation. The feed volume of the extractant water is controlled to 60L/h. Feed from the upper feed port of the tower. The temperature at the top of the rectification tower is controlled at 89.3℃, the pressure is controlled at 0.3MPa, the mass flow rate of the gas phase produced at the top of the tower is 20kg/h, the mass composition of acetone is 94.2%wt., the mass composition of water is 5.8%wt., the content of methanol is not Greater than 500ppm; the tower reactor control temperature is 105.8℃, the water, methanol and acetone are continuously produced, the flow rate is 109.13kg/h, the mass composition of water-methanol-acetone in the tower reactor output is 44.48%-54.54%-0.93%, respectively. In addition, some high-boiling impurities are also discharged from the device along with the wastewater for subsequent treatment. The acetone-water gas mixture extracted from the top of the tower enters the first-stage pervaporation membrane (area about 1.0m ² ). The permeate side of the first-stage pervaporation membrane controls the vacuum to 10kPa, and the permeate passes through low-temperature water (7℃) The two-stage condensing and cooling of chilled water (-20℃) is discharged into the primary permeate storage tank. The feed control temperature of the pervaporation membrane is 89.3℃, the feed pressure is 0.3MPa, and it is separated by the primary pervaporation membrane. After the action, the flow rate of the permeate is 0.93kg/h, and the content of acetone is less than 500ppm. This permeate is discharged from the device as waste water; the mass composition of THF in the material passing through the first-stage pervaporation membrane is 98.78%, and the flow rate It is 19.07kg/h. After the acetone-water mixed solvent is preheated to 100℃ by the heater, it enters the second-stage pervaporation membrane (with an area of about 2.0m ² ). The permeate side of the second-stage pervaporation membrane controls the vacuum degree of 10kPa, and the permeate passes through low temperature. The two-stage condensation cooling of water (7℃) and chilled water (-20℃) is discharged into the secondary permeate storage tank. After the separation of the secondary pervaporation membrane, the permeate flow rate is 0.23kg/h, The mass composition of acetone is about 1%, and the permeate is discharged into the permeate tank after accumulating for a period of time for further recovery of acetone; the mass composition of acetone in the material passing through the second-stage pervaporation membrane is 99.99%, and the flow rate is 18.84kg/ h. The obtained high-purity acetone vapor enters the product tank after being condensed and cooled. The overall recovery rate of acetone is about 95%, and the recovered acetone can fully meet the requirements for reuse.

Claims (10)

The separation and recovery system for aqueous organic waste liquid and organic solvent is characterized in that it is composed of a rectification system and a pervaporation membrane separation system connected through a process pipeline; The rectification system includes a quenching and tempering kettle, a rectification tower, a partial condenser, a total condenser and a product receiving tank one. The outlet of the tempering kettle is connected with the inlet of the rectification tower. The total condenser is set in the top of the rectification tower, and the total condenser is set at the top of the rectification tower to condense the low-boiling components that have not been condensed by the partial condenser. The condensed product enters the product receiving tank 1, and a part of it is refluxed into the rectification tower; The pervaporation membrane separation system includes a vaporizer, a vapor-liquid separator, a reheater, a pervaporation membrane unit, a permeate condenser, a product condenser, and a product receiving tank; the feed port of the vaporizer and the product receiving tank Both are connected with the product receiving tank 1, the outlet of the vaporizer is connected with the inlet of the vapor-liquid separator, the outlet of the vapor-liquid separator is connected with the inlet of the reheater, and the outlet of the reheater Connecting the membrane modules, the pervaporation membrane group is composed of 1 to 6 pervaporation membrane units in series, each unit is composed of 2-6 membrane modules in series or in parallel, and each pervaporation membrane unit is equipped with permeate condenser and permeate respectively Liquid tank, the permeate tank is connected with the rectification tower feed port of the rectification system or directly discharged, and the discharge port of the pervaporation membrane group is connected with the product condenser and the product receiving tank. The separation and recovery system according to claim 1, characterized in that the rectification tower is a packed tower, and the rectification tower adopts side-line feed, and a feed port is provided at the top and the middle of the tower body, and the feed port is located in the filler. Above the center of the tower liquid distributor, the liquid distributor is composed of a disc and a number of split holes evenly arranged on the disc. The surface of the disc is provided with a groove connecting the split hole and the center point of the disc, and the path of the groove It is satisfied that the distance between each split hole and the center point of the disc is equal. The separation and recovery system according to claim 2, wherein the diverging holes are cylindrical holes, and a top cap is provided on the top of each diverging hole, and the top cap is supported and fixed by a support column provided at the diverging orifice, It is realized to maintain a gap with the shunt orifice for the rising vapor to pass through. The separation and recovery system according to any one of claims 1 to 3, wherein in the pervaporation membrane separation system, the pervaporation membrane module is composed of a plurality of pervaporation membrane tubes, a cylindrical membrane shell and a membrane partition. The membrane tube is uniformly fixed on a fixed plate provided with a plurality of fixing holes, the fixed plate is located on the top of the membrane shell, one end of the membrane partition is fixed on the fixed plate, and the other end extends to the bottom of the membrane shell, The space in the membrane shell and the membrane tube are evenly divided into two communicating parts, and the membrane tube is sheathed with a damping spring made of corrosion-resistant material. The separation and recovery system according to claim 3, wherein in the pervaporation membrane separation system, a back pressure valve is provided between the last group of pervaporation membrane units of the pervaporation membrane module and the product condenser. The separation and recovery system according to claim 3, wherein a heat supplement is provided between the upper and lower separation membranes of the pervaporation membrane module. The separation and recovery system according to claim 2, wherein the packing of the rectification tower is θ-type packing formed by stainless steel wire mesh, triangular spring packing, glass ceramic or plastic packing. The separation and recovery system according to claim 2, characterized in that a preheater for preheating materials is arranged on the feed line of the rectification tower; and the tempering tank is a reaction tank with a stirring structure. The separation and recovery system according to claim 2, characterized in that, the rectification system further comprises an extraction/azeotrope storage tank for storing the extractant or azeotrope, and a storage tank for the extractant or azeotrope into the rectification tower The feed pump of the agent. The method for solvent separation and recovery using the separation and recovery system of any one of claims 1-9 is characterized in that it comprises the following steps: The water-containing organic solvent, or two azeotropic or non-azeotropic mixed solvents, after conditioning, are continuously fed into the rectification tower through a pump, and the feed rate of the rectification tower is controlled to be 10-300L/h, and the temperature of the tower bottom is 60-300℃ , The top temperature of the tower is 40～200℃, the operating pressure of the tower is 10～300kPa, and the reflux ratio is 0.5～5. After rectification, after the recovered solvent is purified to more than 80wt%, it enters the pervaporation membrane group for further separation and permeation The feed temperature of the vaporization membrane unit is 80-150°C, the feed amount is 0.5-50L/h, and the operating pressure is 100-600kPa. After separation by the pervaporation membrane, the organic solvent is purified to a purity of ≥99.9wt%.

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