A device and method for separating azeotropes by microwave-induced spray evaporation and its application

Abstract

The present invention discloses a device for separating azeotropes by microwave-induced spray evaporation, the device comprising a spray feeding system, a microwave evaporation cavity, a temperature measuring system, a microwave system, a waveguide, a vapor phase collection system, a liquid phase product tank, a vacuum pump and a three-pin dispenser, the feeding system, the microwave evaporation cavity, the vapor phase recovery system and the vacuum pump are tightly connected in sequence, the temperature measuring system is tightly connected to the inside of the microwave evaporation cavity, the microwave system is tightly connected to the inside of the microwave evaporation cavity through the three-pin dispenser and the waveguide, and the liquid phase product tank is tightly connected to the bottom of the microwave evaporation cavity. The device utilizes the selective heating characteristics of microwaves to achieve separation process enhancement based on the difference in dielectric properties to achieve separation of azeotropes, solves the problems of complex process and huge energy consumption of traditional distillation separation methods, and provides a new method for separation of near-boiling systems or azeotropic systems.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical separation and microwave heating, in particular to a device and method for separating azeotropes by microwave-induced spray evaporation and application. Background Art

[0002] Distillation is the most commonly used method for separating liquid mixtures in chemical production processes. Its principle is that according to the different relative volatilities of the components in the mixture, during the gas-liquid mass transfer process, the components with high relative volatility are enriched in the vapor phase, while the components with low relative volatility mainly remain in the liquid phase, thereby achieving the separation of the mixture liquid.

[0003] Since the relative volatility of azeotropes is 1, azeotropes cannot be separated using conventional distillation methods. Therefore, special distillation methods such as pressure swing distillation, extractive distillation, reactive distillation, etc. are required for the separation of azeotropes. However, the process flow of the above special distillation methods is complicated, the equipment investment is high, and the energy consumption is huge. Other separation methods for azeotropes, such as the pervaporation method in the membrane separation method, rely on the selective permeation of membrane components to different molecules to achieve the separation of azeotropes. However, due to the small flux of a single membrane component, multiple membrane components are usually required in parallel to increase the processing flux, which increases the equipment investment cost. At the same time, the thermodynamic and chemical stability of most membranes are poor. If the material to be separated contains impurities, membrane contamination problems will occur. These factors limit the service life of the membrane. Since the separation membrane needs to be replaced regularly, it is difficult for the membrane separation device to operate continuously for a long time.

[0004] Microwave heating, as an unconventional non-contact heating method, has been widely used in the fields of drying, metallurgy, chemical industry, and food due to its clean, efficient, and fast heating characteristics. Based on the dipole polarization theory, when polar molecules are repeatedly polarized under the action of an alternating electromagnetic field, they will collide violently with the surrounding molecules, causing their own temperature to rise, thereby rapidly increasing the overall temperature of the heated material. Since it does not rely on heat conduction and heat radiation, microwave heating exhibits the characteristics of "body heating" from the inside out compared to conventional heating. At the same time, since non-polar molecules do not absorb microwave energy, microwaves only heat polar molecules, that is, microwave heating has the characteristics of "selective heating" compared to conventional heating. The absorption of polar molecules in the microwave field is related to the dielectric loss of the substance itself. The absorption of high dielectric loss substances is greater than that of low dielectric loss substances, which makes the heating speed of microwaves for substances with different dielectric losses different. Microwave heating allows the high dielectric loss components in the mixture to absorb microwave energy and quickly heat up and evaporate to the vapor phase, promoting separation. The conventional method of separating azeotropes has a complex process flow and huge energy consumption, while microwave-assisted evaporation separation based on differences in dielectric properties may be the focus of future development.

[0005] Through searching, the following patent documents related to this application are found:

[0006] 1. Patent publication CN201658856U discloses a microwave field enhanced molecular distillation separation device, which uses a film scraper to generate a liquid film and enhances molecular evaporation by microwave heating. However, the liquid distribution of the device is single, and it needs to rely on an external mechanical structure to generate a liquid film. The continuity and stability of the liquid film are poor, and it needs a high vacuum to meet the requirements of molecular distillation, which places high restrictions on the strength of the equipment.

[0007] 2. Patent publication CN101342425A discloses a microwave separation method and a device used therein, which is characterized in that microwaves are used as a heat source to heat the separated substances with different dielectric constants under different vacuum degrees, and the distilled steam is cooled and collected through a cold end that is insensitive to microwaves to achieve the separation of high dielectric constant and low dielectric constant mixtures. The above operation belongs to an intermittent operation process, which requires that the solution to be separated is made into a liquid film each time and placed in a closed reagent bottle, and then molecular distillation is performed by microwave heating. The operation steps are cumbersome, and a high vacuum degree is required, which has high requirements for equipment manufacturing.

[0008] 3. Patent publication CN205461121U proposes a microwave separation and extraction device, which uses the rapid heating effect of microwaves to decompose the material to be heated, strengthen the extraction and separation process, and solve the problem of manual grinding of materials in traditional processing. However, the working principle of the device is not based on the difference in dielectric properties to strengthen the separation process, and the material to be heated is not evenly distributed in the microwave cavity, which reduces the efficiency of microwave utilization. At the same time, the device cannot achieve continuous operation and can only perform intermittent production.

[0009] 4. Patent publication CN206081661U proposes an evaporation device based on microwave heating, which uses absorbing materials to convert microwave energy into heat energy, and then uses heat conduction to heat the evaporated material, combining the basic principle of falling film evaporator to achieve evaporation operation. Although this device achieves evaporation separation, the microwave energy is completely absorbed by the absorbing heat exchange element inside the evaporator. It is not a separation process based on differences in dielectric properties, and the separation principle is no different from that of a traditional falling film evaporator.

[0010] 5. Patent publication CN104857734A proposes a microwave-evaporation device, application and application method, which can be used for evaporation and recycling of seawater and evaporation and concentration of mother liquor obtained after decomposition of Bayer process seed liquor. Although the device uses spray evaporation, it still belongs to a flash evaporation system, which mainly relies on the reduction of vacuum degree to make the water in the material evaporate quickly, and the role of microwaves is only to supplement the heat consumed by the droplets during the evaporation process. The main working principle of the device does not rely on the difference in dielectric properties between components to strengthen the separation process.

[0011] In summary, the microwave-assisted evaporation device in the existing azeotropic separation technology has some defects and cannot fully meet the use requirements. Therefore, one or more new related equipment and methods are urgently needed. Summary of the invention

[0012] The purpose of the present invention is to overcome the problems existing in the prior art and to provide a device, method and application for separating azeotropes by microwave-induced spray evaporation.

[0013] The technical solution adopted by the present invention to solve the technical problem is:

[0014] A device for separating azeotropes by microwave-induced spray evaporation, comprising a spray feeding system, a microwave evaporation cavity, a temperature measuring system, a microwave system, a waveguide, a vapor phase collection system, a liquid phase product tank, a vacuum pump and a three-pin dispenser. The feeding system, the microwave evaporation cavity, the vapor phase recovery system and the vacuum pump are tightly connected in sequence, the temperature measuring system is tightly connected to the inside of the microwave evaporation cavity, the microwave system is tightly connected to the inside of the microwave evaporation cavity through the three-pin dispenser and the waveguide, and the liquid phase product tank is tightly connected to the bottom of the microwave evaporation cavity.

[0015] Furthermore, the spray feeding system can input the azeotropic material liquid to be evaporated and separated into the microwave evaporation cavity, the microwave evaporation cavity can contain the material liquid to be separated, the temperature measuring system can measure the temperature of the droplets in the spray evaporation cavity, the microwave system can input microwaves into the microwave evaporation cavity through the three-pin dispenser and the waveguide, the vapor phase collection system can condense and collect the vapor phase evaporated and separated in the microwave evaporation cavity, and the liquid phase product tank can collect the liquid phase material liquid evaporated and separated in the microwave evaporation cavity;

[0016] The microwave evaporation cavity, and the connections between the microwave evaporation cavity and the spray feeding system, the temperature measuring system, the waveguide, the liquid product tank and the vapor collection system all meet the microwave shielding requirements to ensure that no wave leakage occurs.

[0017] Further, the spray feeding system comprises a raw material tank, a first feeding valve, a gear pump, a first mass flowmeter, a first control valve and a high-pressure atomizing nozzle which are tightly connected in sequence, a first discharge valve is tightly connected to the output end pipeline of the raw material tank, a first thermometer is tightly connected to the raw material tank, the raw material tank can contain azeotropic material liquid to be evaporated and separated, the high-pressure atomizing nozzle is connected to the microwave evaporation cavity, the high-pressure atomizing nozzle can spray the azeotropic material liquid to be evaporated and separated into the microwave evaporation cavity, and the first mass flowmeter can realize flow control;

[0018] The vapor phase collection system comprises a demister, a second thermometer, a condenser, a second mass flowmeter, a vapor phase product tank and a second discharge valve which are closely connected in sequence, and the vapor phase product tank can contain the vapor phase azeotropic material liquid that has been evaporated and separated;

[0019] The vacuum pump is also closely connected to the vapor phase product tank, and the vacuum pump can evacuate the vapor phase product tank;

[0020] The microwave evaporation cavity comprises an evaporation cavity and a flange plate arranged in the evaporation cavity. The evaporation cavity is in a sealed hollow shape. The hollow inner bottom of the evaporation cavity is tightly connected to the input end of the liquid product tank through a third thermometer, a third mass flowmeter, and a second control valve in sequence. A third discharge valve is tightly connected to the output end pipeline of the liquid product tank to control the discharge of the liquid product tank at the output end. The high-pressure atomization nozzle comprises a first high-pressure atomization nozzle and a second high-pressure atomization nozzle. The first high-pressure atomization nozzle is tightly connected to the top of the evaporation cavity, and the second high-pressure atomization nozzle is tightly connected to the flange plate. The liquid to be evaporated and separated can maintain one or two spraying states from top to bottom and from bottom to top through the raw material tank, the gear pump, the first control valve, the first high-pressure atomization nozzle, and the second high-pressure atomization nozzle. The demister and the pressure gauge are tightly connected to the upper part of the evaporation cavity, and are tightly connected to the hollow inner part of the evaporation cavity.

[0021] The temperature measurement system comprises an optical fiber thermometer and an optical fiber temperature measurement terminal which are closely connected and arranged, the optical fiber thermometer is extended and closely arranged in the hollow interior of the evaporation cavity, and the optical fiber temperature measurement terminal can display the temperature measured by the optical fiber thermometer;

[0022] The waveguides are connected and arranged on the outer surface of the side wall of the evaporation chamber;

[0023] The microwave system comprises a microwave power supply and a microwave generator which are connected to each other. The microwave generator can be connected to the waveguide through a three-pin adapter.

[0024] Furthermore, the microwave system also includes a control terminal, which is connected to the microwave power supply and the microwave generator, and the control terminal can adjust the power of the microwave generator.

[0025] Furthermore, the evaporation chamber also includes a chamber body, an upper head and a lower head. The chamber body is arranged in a vertical direction, the upper head is tightly and detachably coaxially arranged on the top of the chamber body, the lower head is tightly and detachably coaxially arranged on the bottom of the chamber body, and the flange is detachably coaxially arranged on the chamber body.

[0026] Furthermore, the upper end cover of the evaporation chamber is configured as an ellipsoidal, spherical or planar end cover, and the lower end cover is configured as an ellipsoidal or spherical end cover;

[0027] Alternatively, the evaporation chamber is made of a wave-proof material;

[0028] Alternatively, the flange is made of a wave-proof material;

[0029] Alternatively, the flange includes a flange body and holes, and a plurality of holes are evenly distributed on the flange body along the circumferential direction, and the holes are arranged along the vertical direction.

[0030] Further, the operating frequency of the microwave generator is 2450MHz or 915MHz, and the output power is 0-15KW;

[0031] Alternatively, the high-pressure atomizing nozzle is wrapped and packaged by a stainless steel wire mesh with a pore size of 3 mm for electromagnetic shielding;

[0032] Alternatively, the operating pressure of the microwave evaporation cavity is 0 to 100 KPa (absolute pressure).

[0033] Furthermore, the waveguide is a rectangular waveguide, which is arranged on two opposite side walls outside the evaporation cavity. When the rectangular waveguide is used as a microwave feed inlet, a plurality of adjustable opening slots are opened on the rectangular waveguide, and the electric field strength at different heights of the evaporation cavity is adjusted by changing the size of the opening slots of the rectangular waveguide;

[0034] Alternatively, a plurality of waveguides are arranged at intervals along the vertical direction, and the waveguides are fed in a multi-port microwave feeding manner, and the electric field intensity at different heights of the evaporation cavity is adjusted by controlling the input power of each port;

[0035] Alternatively, the optical fiber thermometer comprises a temperature measuring optical fiber and a catheter which are connected to each other, the temperature measuring optical fiber is coaxially arranged in the catheter, and the catheter is made of polytetrafluoroethylene, nylon or quartz;

[0036] Alternatively, the microwave evaporation cavity is tightly connected to the waveguide via a sealing baffle made of quartz or polytetrafluoroethylene.

[0037] The separation method of the device for separating azeotropes by microwave-induced spray evaporation as described above comprises the following steps:

[0038] (1) First, add a binary saturated solution of a certain composition into the raw material tank, turn all discharge valves to the closed state before starting the device, and then start the vacuum pump to adjust the pressure in the evaporation chamber to the set value;

[0039] (2) The feed liquid is preheated to a set temperature in the raw material tank, and the temperature in the raw material tank is displayed by a first thermometer; when the temperature of the feed liquid rises to the set temperature, the preheating is completed;

[0040] (3) opening the first feed valve, the first control valve and the second control valve and starting the gear pump, adjusting the feed flow rate to the set value, sending the feed liquid to the high-pressure atomizing nozzle for pressure atomization, and then spraying it into the evaporation chamber in the form of droplets;

[0041] (4) Turn on the power of the microwave system and adjust the microwave output power of the microwave generator to the set value through the control terminal and the three-pin adjuster;

[0042] (5) Observe the reading of the optical fiber temperature measurement terminal. When the reading is stable, it indicates that the evaporation process has reached a steady state. The vapor phase produced by evaporation is condensed by the condenser and enters the vapor phase product tank. The droplets that are not completely evaporated settle to the bottom of the evaporation chamber and enter the liquid phase product tank through the liquid phase discharge pipe.

[0043] (6) When steady-state evaporation is achieved, the reading of the second thermometer is recorded as the vapor phase temperature, the microwave input power value displayed on the control terminal, the feed flow rate displayed by the first mass flow meter and the vapor phase discharge flow rate displayed by the third mass flow meter are recorded, and samples are taken from the vapor phase product tank and the liquid phase product tank for analysis to obtain the gas-liquid phase composition of the evaporation separation under microwave radiation.

[0044] The application of the device for separating azeotropes by microwave-induced spray evaporation as described above in the separation of azeotropes and near-boiling systems.

[0045] The beneficial effects achieved by the present invention are:

[0046] 1. The device includes a spray feeding system, a microwave evaporation cavity, a temperature measurement system, a microwave system, a waveguide, a vapor phase collection system, a liquid phase product tank, a vacuum pump and a three-pin dispenser. The device utilizes the selective heating characteristics of microwaves to realize the separation process based on the difference in dielectric properties to achieve the separation of azeotropes, solves the problems of complex process and huge energy consumption of traditional distillation separation methods, and provides a new method for the separation of near-boiling systems or azeotropic systems. In the process of separating azeotropes by microwave-induced spray evaporation, it is a microwave-enhanced separation process based on the difference in dielectric properties. Components with high dielectric loss can be quickly heated and evaporated to the vapor phase in the microwave field, so that the content of low dielectric loss components in the liquid phase increases, thereby effectively separating near-boiling or azeotropic systems. Compared with falling film evaporation or scraped film evaporation, the feed in spray evaporation is tiny droplets, which can effectively increase the evaporation area of ​​the feed per unit volume, provide more gas-liquid interfaces, and increase the evaporation amount while strengthening gas-liquid mass transfer. In addition, when the device is in operation, the operator can continuously adjust the output power of the microwave system in real time according to the temperature signal of the droplets in the spray evaporation chamber detected by the temperature measurement system to avoid overheating.

[0047] The device of the invention is a microwave-assisted evaporation device based on the difference of dielectric properties, with simple structure, controllable process, easy manufacturing and continuous operation, which is used to strengthen the separation of azeotropes.

[0048] 2. The spray direction of the high-pressure atomizing nozzle in this device is from top to bottom and from bottom to top to meet the different requirements of different feed liquids for residence time. Compared with falling film evaporation or scraping film evaporation, the feed in spray evaporation is tiny droplets, which can effectively increase the evaporation area per unit volume of feed, provide more gas-liquid interface, strengthen gas-liquid mass transfer and increase evaporation amount. The tiny droplets can effectively reduce the thickness of the liquid layer, inhibit molecular heat transfer between components in the liquid phase, ensure that the temperature of the high dielectric loss component is always higher than that of the low dielectric loss component, and promote the evaporation and separation of the high dielectric loss component.

[0049] 3. The evaporation chamber in the device also includes a chamber body, an upper head and a lower head, and the flange is detachably coaxially arranged on the chamber body. The upper head and the lower head of the device are detachable and can be quickly disassembled and easily installed, and are also convenient for replacement and maintenance of the evaporation chamber, high-pressure atomizing nozzle, etc. In addition, there is no wave-absorbing sieve plate in the evaporation chamber, and the microwave energy input from the waveguide is completely absorbed by the liquid in the evaporation chamber, which greatly improves the utilization rate of microwaves.

[0050] The upper head of the evaporation chamber is set to an ellipsoidal, spherical or flat head, and the lower head is set to an ellipsoidal or spherical head, so that the liquid on the bottom of the evaporation chamber can quickly gather and flow into the liquid product tank, avoiding the accumulation of liquid at the bottom of the evaporation chamber; the evaporation chamber and the flange are made of stainless steel, iron, aluminum and other non-wave-transparent materials, which can effectively prevent microwaves from penetrating the evaporation chamber and effectively prevent microwaves from entering the lower head and damaging the feed pipe.

[0051] 4. The waveguide in the device is a rectangular waveguide. When the rectangular waveguide is used as a microwave feed port, a plurality of adjustable opening slots are opened on the rectangular waveguide. The electric field strength at different heights of the evaporation cavity is adjusted by changing the size, position and number of the opening slots of the rectangular waveguide; or, a plurality of waveguides are arranged at intervals along the vertical direction, and the waveguide is fed in a multi-port microwave feeding mode. The electric field strength at different heights of the evaporation cavity is adjusted by controlling the input power of each port, so that the microwave distribution in the cavity can be appropriately adjusted according to the distribution of the feed liquid, which greatly improves the utilization rate of the microwave and saves microwave energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 A schematic diagram of a structural connection main view of the device of the present invention;

[0053] Figure 2 for Figure 1 A side view of the evaporation cavity; Figure A is a side view when the waveguide is a rectangular waveguide, and Figure B is a side view when the waveguide is fed in a multi-port microwave feeding manner;

[0054] Figure 3 for Figure 1 An enlarged top view of the flange in FIG.

[0055] Figure 4 The present invention is a process flow chart of the evaporation separation using the device. DETAILED DESCRIPTION

[0056] For a better understanding of the present invention, the present invention is further described in detail below in conjunction with embodiments, but the scope of protection claimed by the present invention is not limited to the scope represented by the embodiments.

[0057] The raw materials used in the present invention, unless otherwise specified, are all conventional commercially available products. The methods used in the present invention, unless otherwise specified, are all conventional methods in the art. The quality of each substance used in the present invention is the conventional quality.

[0058] A device for separating azeotropes by microwave-induced spray evaporation, such as Figure 1 to Figure 2As shown, the device includes a spray feeding system, a microwave evaporation cavity, a temperature measuring system, a microwave system, a waveguide 6, a vapor phase collection system, a liquid phase product tank 24, a vacuum pump 16 and a three-pin dispenser 4. The feeding system, the microwave evaporation cavity, the vapor phase recovery system and the vacuum pump are tightly connected in sequence, the temperature measuring system is tightly connected to the interior of the microwave evaporation cavity, the microwave system is tightly connected to the interior of the microwave evaporation cavity through the three-pin dispenser and the waveguide, and the liquid phase product tank is tightly connected to the bottom of the microwave evaporation cavity.

[0059] The device includes a spray feeding system, a microwave evaporation cavity, a temperature measurement system, a microwave system, a waveguide, a vapor phase collection system, a liquid phase product tank, a vacuum pump and a three-pin dispenser. The device utilizes the selective heating characteristics of microwaves to realize the separation process based on the difference in dielectric properties to achieve the separation of azeotropes, solves the problems of complex process and huge energy consumption of traditional distillation separation methods, and provides a new device and method for the separation of near-boiling systems or azeotropic systems. In the process of separating azeotropes by microwave-induced spray evaporation, it is a microwave-enhanced separation process based on the difference in dielectric properties. Components with high dielectric loss can be quickly heated and evaporated to the vapor phase in the microwave field, so that the content of low dielectric loss components in the liquid phase increases, thereby effectively separating near-boiling or azeotropic systems. Compared with falling film evaporation or scraped film evaporation, the feed in spray evaporation is tiny droplets, which can effectively increase the evaporation area of ​​the feed per unit volume, provide more gas-liquid interfaces, and increase the evaporation amount while strengthening gas-liquid mass transfer. In addition, when the device is in operation, the operator can continuously adjust the output power of the microwave system in real time according to the temperature signal of the droplets in the spray evaporation chamber detected by the temperature measurement system to avoid overheating.

[0060] In this embodiment, the spray feeding system can input the azeotropic material liquid to be evaporated and separated into the microwave evaporation cavity, the microwave evaporation cavity can contain the material liquid to be separated, the temperature measurement system can measure the temperature of the droplets in the spray evaporation cavity, the microwave system can input microwaves into the microwave evaporation cavity through a three-pin dispenser and a waveguide, the vapor phase collection system can condense and collect the vapor phase evaporated and separated in the microwave evaporation cavity, and the liquid phase product tank can collect the liquid phase material liquid evaporated and separated in the microwave evaporation cavity;

[0061] The microwave evaporation cavity, and the connections between the microwave evaporation cavity and the spray feeding system, the temperature measuring system, the waveguide, the liquid product tank and the vapor collection system all meet the microwave shielding requirements to ensure that no wave leakage occurs.

[0062] In this embodiment, the spray feeding system includes a raw material tank 27, a first feeding valve 25, a gear pump 21, a first mass flowmeter 18, a first control valve (17, 22) and a high-pressure atomizing nozzle which are tightly connected in sequence. A first discharge valve 31 is tightly connected to the output end pipeline 272 of the raw material tank, and a first thermometer 26 is tightly connected to the raw material tank. The raw material tank can contain azeotropic material liquid to be evaporated and separated, and the high-pressure atomizing nozzle is connected to the microwave evaporation cavity. The high-pressure atomizing nozzle can spray the azeotropic material liquid to be evaporated and separated into the microwave evaporation cavity, and the first mass flowmeter can realize flow control;

[0063] The vapor phase collection system includes a demister 12, a second thermometer 13, a condenser 14, a second mass flowmeter 15, a vapor phase product tank 19 and a second discharge valve 20 which are closely connected in sequence. The vapor phase product tank can contain the vapor phase azeotropic material liquid that has been evaporated and separated. The demister can effectively filter out the droplets entrained in the rising gas to prevent the entrainment of mist and foam from interfering with the composition of the vapor phase product.

[0064] The vacuum pump is also closely connected to the vapor phase product tank, and the vacuum pump can evacuate the vapor phase product tank;

[0065] The microwave evaporation cavity comprises an evaporation cavity 9 and a flange plate arranged in the evaporation cavity. The evaporation cavity is in a sealed hollow shape. The hollow inner bottom of the evaporation cavity is tightly connected with the input end of the liquid product tank through the third thermometer 28, the third mass flowmeter 29, and the second control valve 23 in sequence. The third discharge valve 30 is tightly connected to the output end pipeline 242 of the liquid product tank to control the discharge of the liquid product tank. The high-pressure atomization nozzle comprises a first high-pressure atomization nozzle 11 and a second high-pressure atomization nozzle 5. The first high-pressure atomization nozzle is tightly connected and arranged at the top of the evaporation cavity. The second high-pressure atomization nozzle is tightly connected and arranged on the flange plate. The liquid to be evaporated and separated can maintain one or two spraying states from top to bottom and from bottom to top through the raw material tank, the gear pump, the first control valve and the first high-pressure atomization nozzle and the second high-pressure atomization nozzle to meet different usage requirements. The demister and the pressure gauge 10 are tightly connected and arranged at the upper part of the evaporation cavity, and are tightly connected and arranged with the hollow inner part of the evaporation cavity.

[0066] The temperature measurement system comprises an optical fiber thermometer and an optical fiber temperature measurement terminal 8 which are closely connected. The optical fiber thermometer is extended and closely arranged in the hollow interior of the evaporation cavity. The optical fiber temperature measurement terminal can display the temperature measured by the optical fiber thermometer.

[0067] The waveguides are connected and arranged on the outer surface of the side wall of the evaporation chamber;

[0068] The microwave system comprises a microwave power supply 2 and a microwave generator 3 which are connected to each other. The microwave generator can be connected to the waveguide via a three-pin adapter.

[0069] The spray direction of the high-pressure atomizing nozzle in this device is from top to bottom and from bottom to top, which meets the different requirements of different feed liquids for residence time. Compared with falling film evaporation or scraping film evaporation, the feed in spray evaporation is tiny droplets, which can effectively increase the evaporation area of ​​unit volume of feed, provide more gas-liquid interface, strengthen gas-liquid mass transfer and increase evaporation amount. The tiny droplets can effectively reduce the thickness of the liquid layer, inhibit molecular heat transfer between components in the liquid phase, ensure that the temperature of the high dielectric loss component is always higher than that of the low dielectric loss component, and promote the evaporation and separation of the high dielectric loss component.

[0070] In this embodiment, the evaporation cavity further includes a cavity body 902, an upper end cap 901 and a lower end cap 903. The cavity body is arranged in a vertical direction, the upper end cap is tightly and detachably coaxially arranged at the top of the cavity body, the lower end cap is tightly and detachably coaxially arranged at the bottom of the cavity body, and the flange is detachably coaxially arranged on the cavity body. The upper end cap and the lower end cap of the device are detachably installed, can be quickly disassembled and installed conveniently, and are also convenient for replacement and maintenance of the evaporation cavity, high-pressure atomizing nozzle, etc. In addition, no wave-absorbing sieve plate is arranged in the evaporation cavity, and the microwave energy input from the waveguide is completely absorbed by the liquid in the evaporation cavity, which greatly improves the utilization rate of the microwave.

[0071] Preferably, the upper head of the evaporation chamber is set to an ellipsoidal, spherical or planar head, and the lower head is set to an ellipsoidal or spherical head, so that the liquid on the bottom surface of the evaporation chamber quickly gathers and flows into the liquid product tank, avoiding the accumulation of liquid at the bottom of the evaporation chamber.

[0072] Preferably, the evaporation cavity is made of a wave-impermeable material such as stainless steel, iron, or aluminum, which can effectively prevent microwaves from penetrating the evaporation cavity.

[0073] In this embodiment, the flange is made of a wave-proof material such as stainless steel, iron, or aluminum alloy, which can effectively prevent microwaves from entering the lower head and causing damage to the feed pipe.

[0074] Preferably, if Figure 3 As shown, the flange includes a flange body 32 and holes 33. The flange body is evenly distributed with a plurality of holes along the circumferential direction. The holes are arranged along the vertical direction. The arrangement of the plurality of holes enables the droplets that are not completely evaporated to enter the lower head along the holes and enter the liquid product tank through the discharge pipe below.

[0075] In this embodiment, the microwave system further includes a control terminal 1, which is connected to the microwave power supply and the microwave generator. The control terminal can adjust the power of the microwave generator to expand the application range of the device.

[0076] In this embodiment, the operating frequency of the microwave generator is 2450MHz or 915MHz, and the output power is 0-15KW. When the device is running, the operator can cooperate with the adjustment of the control terminal to achieve constant microwave power mode or variable power mode output. When the device is running, the operator can continuously adjust the output power of the microwave source in real time according to the temperature signal received from the optical fiber thermometer to avoid overheating.

[0077] In this embodiment, the waveguide is a rectangular waveguide, which is arranged on two opposite side walls outside the evaporation cavity, and can convert the microwave output by the microwave generator from one path into two incoherent microwaves, which are respectively input into the evaporation cavity; when the rectangular waveguide is used as a microwave feed inlet, a plurality of adjustable opening slots 601 are opened on the rectangular waveguide, and the electric field strength at different heights of the evaporation cavity is adjusted by changing the size of the opening slots of the rectangular waveguide;

[0078] Alternatively, a plurality of waveguides are arranged at intervals along the vertical direction, and the waveguides are fed in a multi-port microwave feeding manner. The electric field intensity at different heights of the evaporation cavity is adjusted by controlling the input power of each port, so that the microwave distribution in the cavity can be appropriately adjusted according to the distribution of the feed liquid, thereby greatly improving the utilization rate of the microwaves and saving microwave energy.

[0079] In this embodiment, the high-pressure atomizing nozzle is wrapped and packaged by a stainless steel wire mesh with a pore size of 3 mm for electromagnetic shielding to prevent microwave damage to the nozzle and the occurrence of two-way liquid phase feeding.

[0080] Preferably, the fiber optic thermometer includes a temperature measuring optical fiber and a catheter 7 that are connected to each other. The temperature measuring optical fiber is coaxially arranged in the catheter. The catheter is made of polytetrafluoroethylene, nylon 6 or quartz material to ensure that microwaves can effectively penetrate the catheter without heating the catheter.

[0081] Preferably, the operating pressure of the microwave evaporation cavity is 0-100 Kpa (absolute pressure), and the microwave evaporation cavity is tightly connected to the waveguide through a sealing baffle 602 made of quartz or polytetrafluoroethylene.

[0082] The separation method of the microwave induced spray evaporation separation device is as follows: Figure 4 As shown, the method comprises the following steps:

[0083] (1) First, add a binary saturated solution of a certain composition into the raw material tank, turn all discharge valves to the closed state before starting the device, and then start the vacuum pump to adjust the pressure in the evaporation chamber to the set value;

[0084] (2) The feed liquid is preheated to a set temperature in the raw material tank, and the temperature in the raw material tank is displayed by a first thermometer; when the temperature of the feed liquid rises to the set temperature, the preheating is completed;

[0085] (3) opening the first feed valve, the first control valve and the second control valve and starting the gear pump, adjusting the feed flow rate to the set value, sending the feed liquid to the high-pressure atomizing nozzle for pressure atomization, and then spraying it into the evaporation chamber in the form of droplets;

[0086] (4) Turn on the power of the microwave system and adjust the microwave output power of the microwave generator to the set value through the control terminal and the three-pin adjuster;

[0087] (5) Observe the reading of the optical fiber temperature measurement terminal. When the reading is stable, it indicates that the evaporation process has reached a steady state. The vapor phase produced by evaporation is condensed by the condenser and enters the vapor phase product tank. The droplets that are not completely evaporated settle to the bottom of the evaporation chamber and enter the liquid phase product tank through the liquid phase discharge pipe.

[0088] (6) When steady-state evaporation is achieved, the reading of the second thermometer is recorded as the vapor phase temperature, the microwave input power value displayed on the control terminal, the feed flow rate displayed by the first mass flow meter and the vapor phase discharge flow rate displayed by the third mass flow meter are recorded, and samples are taken from the vapor phase product tank and the liquid phase product tank for analysis to obtain the gas-liquid phase composition of the evaporation separation under microwave radiation.

[0089] When the device is started, in order to prevent microwaves from being empty, the microwave evaporation cavity is first filled with droplets, and then microwaves are input. In addition, during actual operation, the separation effect under different conditions can be obtained by changing the microwave input power, adjusting the electric field distribution, changing the feed temperature, feed composition and feed flow rate, and repeating the above steps.

[0090] The microwave-induced spray evaporation separation device can be used in the field of separation of azeotropic systems and near-boiling systems.

[0091] Specifically, the relevant preparation and detection are as follows:

[0092] Example 1

[0093] The method for separating azeotropes using the microwave-induced spray evaporation separation device as described above, the device and method steps are the same as above, and the detailed parameters are as follows:

[0094] The spraying method was adopted from top to bottom. Under normal pressure, a water-ethanol system was selected, and the feed temperature was controlled to be 30 °C, the feed flow rate was 20 L / h, the microwave power density was set to 0.75 kW / kg·h, and the feed concentration of ethanol was 0.2 mol·mol -1 , 0.3 mol·mol -1 , 0.4 mol·mol -1 and 0.47 mol·mol -1 , and obtained the experimental data of spray evaporation of water-ethanol system at different feed concentrations. Where x and y are the liquid phase and vapor phase molar compositions of ethanol, respectively.

[0095]

[0096] The results of microwave-induced spray evaporation show that for the water-ethanol system, since ethanol molecules have greater dielectric loss, the selective heating effect of microwaves will cause the high dielectric loss component ethanol to overheat, increase the evaporation kinetic energy of ethanol molecules, and cause more ethanol molecules to evaporate into the gas phase. Therefore, through microwave-induced evaporation separation, the ethanol content in the liquid phase decreases, while the ethanol content in the gas phase increases. And as the concentration of ethanol molecules in the feed increases, the ethanol content in the gas phase also gradually increases, indicating that more ethanol molecules are evaporated into the gas phase.

[0097] Example 2

[0098] The method for separating azeotropes using the microwave-induced spray evaporation separation device as described above, the device and method steps are the same as above, and the detailed parameters are as follows:

[0099] The spraying method was adopted from bottom to top. Under normal pressure, a water-n-propanol system was selected, and the feed temperature was controlled to be 30 °C, the feed flow rate was 15 L / h, the microwave power density was set to 1.0 kW / kg·h, and the feed concentration of n-propanol was 0.35 mol·mol -1 , 0.40mol·mol -1 , 0.45mol·mol -1 and 0.50 mol·mol -1 , the experimental data of spray evaporation of water-n-propanol system at different feed concentrations were obtained, where x and y are the liquid phase and vapor phase molar compositions of n-propanol, respectively.

[0100]

[0101] The results of microwave-induced spray evaporation show that for the water-n-propanol system, since the n-propanol molecule has a larger dielectric loss, the selective heating effect of microwaves will cause the n-propanol component with high dielectric loss to overheat, increase the evaporation kinetic energy of the n-propanol molecule, and make more n-propanol molecules evaporate into the gas phase. At the same time, microwave-induced evaporation separation can also break the azeotropic composition limitation in traditional thermodynamics and achieve the separation of azeotropes. For example, when the feed concentration is 0.48 mol·mol -1 Under normal heating conditions, the concentration of n-propanol in the liquid product can only be reduced to 0.44 mol·mol due to the limitation of the azeotropic composition. -1 Through the microwave-induced spray evaporation process, the concentration of n-propanol in the liquid phase product is lower than the azeotropic composition of 0.44 mol·mol-1 due to the selective heating of microwaves, while the n-propanol content in the gas phase is increased to 0.5086 mol·mol -1 .

[0102] Example 3

[0103] The method for separating azeotropes using the microwave-induced spray evaporation separation device as described above, the device and method steps are the same as above, and the detailed parameters are as follows:

[0104] The spraying method was from top to bottom. Under normal pressure, a water-ethanol system was selected, and the feed temperature was controlled to be 30°C, the feed flow rate was 10L / h, and the ethanol feed concentration was 0.40mol·mol -1 The microwave power densities were set to 1.00 kW / kg·h, 1.25 kW / kg·h and 1.5 kW / kg·h, respectively, to obtain the spray evaporation experimental data of the water-ethanol system under different microwave power densities.

[0105] Where x and y are the molar compositions of ethanol in the liquid and vapor phases, respectively.

[0106]

[0107] It can be seen from the experimental results that for the water-ethanol system, as the microwave power density increases, the ethanol content in the gas phase gradually decreases. This is because, on the one hand, the increase in microwave power density can make the high dielectric loss component ethanol absorb more microwave energy, thereby transferring more heat to water molecules through intermolecular heat transfer. On the other hand, the increase in microwave power density will also make water molecules absorb more microwave energy and promote the evaporation of water molecules. Therefore, increasing the microwave power will cause more low dielectric loss component water to enter the gas phase. Therefore, for the microwave-induced spray evaporation process, increasing the microwave power density will reduce the effect of microwave-enhanced separation. Therefore, in practical applications, the appropriate microwave input power should be selected according to the separation task requirements.

[0108] Although the embodiments of the present invention are disclosed for illustrative purposes, those skilled in the art will appreciate that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments.

Claims

1. A device for separating azeotropes by microwave-induced spray evaporation, characterized in that: The device comprises a spray feeding system, a microwave evaporation cavity, a temperature measuring system, a microwave system, a waveguide, a vapor phase collection system, a liquid phase product tank, a vacuum pump and a three-pin dispenser. The feeding system, the microwave evaporation cavity, the vapor phase recovery system and the vacuum pump are tightly connected in sequence. The temperature measuring system is tightly connected to the interior of the microwave evaporation cavity. The microwave system is tightly connected to the interior of the microwave evaporation cavity through the three-pin dispenser and the waveguide. The liquid phase product tank is tightly connected to the bottom of the microwave evaporation cavity. The spray feeding system can input the azeotropic material liquid to be evaporated and separated into the microwave evaporation cavity, the microwave evaporation cavity can contain the material liquid to be separated, the temperature measuring system can measure the temperature of the droplets in the spray evaporation cavity, the microwave system can input microwaves into the microwave evaporation cavity through a three-pin dispenser and a waveguide, the vapor phase collection system can condense and collect the vapor phase evaporated and separated in the microwave evaporation cavity, and the liquid phase product tank can collect the liquid phase material liquid evaporated and separated in the microwave evaporation cavity; The microwave evaporation cavity, and the connections between the microwave evaporation cavity and the spray feeding system, the temperature measuring system, the waveguide, the liquid product tank, and the vapor collection system all meet the microwave shielding requirements to ensure that no wave leakage occurs; The spray feeding system comprises a raw material tank, a first feeding valve, a gear pump, a first mass flowmeter, a first control valve and a high-pressure atomizing nozzle which are tightly connected in sequence. The first discharge valve is tightly connected to the output end pipeline of the raw material tank, and the first thermometer is tightly connected to the raw material tank. The raw material tank can contain azeotropic material liquid to be evaporated and separated, and the high-pressure atomizing nozzle is connected to the microwave evaporation cavity. The high-pressure atomizing nozzle can spray the azeotropic material liquid to be evaporated and separated into the microwave evaporation cavity in an atomized manner, and the first mass flowmeter can realize flow control; The vapor phase collection system comprises a demister, a second thermometer, a condenser, a second mass flowmeter, a vapor phase product tank and a second discharge valve which are closely connected in sequence, and the vapor phase product tank can contain the vapor phase azeotropic material liquid that has been evaporated and separated; The vacuum pump is also closely connected to the vapor phase product tank, and the vacuum pump can evacuate the vapor phase product tank; The microwave evaporation cavity comprises an evaporation cavity and a flange plate arranged in the evaporation cavity. The evaporation cavity is in a sealed hollow shape. The hollow inner bottom of the evaporation cavity is tightly connected to the input end of the liquid product tank through a third thermometer, a third mass flowmeter, and a second control valve in sequence. A third discharge valve is tightly connected to the output end pipeline of the liquid product tank to control the discharge of the liquid product tank at the output end. The high-pressure atomization nozzle comprises a first high-pressure atomization nozzle and a second high-pressure atomization nozzle. The first high-pressure atomization nozzle is tightly connected to the top of the evaporation cavity, and the second high-pressure atomization nozzle is tightly connected to the flange plate. The liquid to be evaporated and separated can maintain one or two spraying states from top to bottom and from bottom to top through the raw material tank, the gear pump, the first control valve, the first high-pressure atomization nozzle, and the second high-pressure atomization nozzle. The demister and the pressure gauge are tightly connected to the upper part of the evaporation cavity, and are tightly connected to the hollow inner part of the evaporation cavity. The temperature measurement system comprises an optical fiber thermometer and an optical fiber temperature measurement terminal which are closely connected and arranged, the optical fiber thermometer is extended and closely arranged in the hollow interior of the evaporation cavity, and the optical fiber temperature measurement terminal can display the temperature measured by the optical fiber thermometer; The waveguides are connected and arranged on the outer surface of the side wall of the evaporation chamber; The microwave system comprises a microwave power supply and a microwave generator which are connected to each other. The microwave generator can be connected to the waveguide through a three-pin adapter.

2. The device for separating azeotropes by microwave-induced spray evaporation according to claim 1, characterized in that: The microwave system also includes a control terminal, which is connected to the microwave power supply and the microwave generator, and the control terminal can adjust the power of the microwave generator.

3. The device for separating azeotropes by microwave-induced spray evaporation according to claim 1, characterized in that: The evaporation chamber also includes a chamber body, an upper head and a lower head. The chamber body is arranged in a vertical direction. The upper head is tightly and detachably coaxially arranged on the top of the chamber body. The lower head is tightly and detachably coaxially arranged on the bottom of the chamber body. The flange is detachably coaxially arranged on the chamber body.

4. The device for separating azeotropes by microwave-induced spray evaporation according to claim 3, characterized in that: The upper end cover of the evaporation chamber is configured as an ellipsoidal, spherical or planar end cover, and the lower end cover is configured as an ellipsoidal or spherical end cover; Alternatively, the evaporation chamber is made of a wave-proof material; Alternatively, the flange is made of a wave-proof material; Alternatively, the flange includes a flange body and holes, and a plurality of holes are evenly distributed on the flange body along the circumferential direction, and the holes are arranged along the vertical direction.

5. The device for separating azeotropes by microwave-induced spray evaporation according to claim 1, characterized in that: The operating frequency of the microwave generator is 2450MHz or 915MHz, and the output power is 0~15KW; Alternatively, the high-pressure atomizing nozzle is wrapped and packaged by a stainless steel wire mesh with a pore size of 3 mm for electromagnetic shielding; Alternatively, the operating pressure of the microwave evaporation cavity is 0-100 KPa (absolute pressure).

6. The device for separating azeotropes by microwave-induced spray evaporation according to any one of claims 1 to 5, characterized in that: The waveguide is a rectangular waveguide, which is arranged on two opposite side walls outside the evaporation cavity. When the rectangular waveguide is used as a microwave feed inlet, a plurality of adjustable opening slots are opened on the rectangular waveguide, and the electric field strength at different heights of the evaporation cavity is adjusted by changing the size of the opening slots of the rectangular waveguide; Alternatively, a plurality of waveguides are arranged at intervals along the vertical direction, and the waveguides are fed in a multi-port microwave feeding manner, and the electric field intensity at different heights of the evaporation cavity is adjusted by controlling the input power of each port; Alternatively, the optical fiber thermometer comprises a temperature measuring optical fiber and a catheter which are connected to each other, the temperature measuring optical fiber is coaxially arranged in the catheter, and the catheter is made of polytetrafluoroethylene, nylon or quartz; Alternatively, the microwave evaporation cavity is tightly connected to the waveguide via a sealing baffle made of quartz or polytetrafluoroethylene.

7. The separation method of the device for separating azeotropes by microwave-induced spray evaporation according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: (1) First, add a binary saturated solution of a certain composition into the raw material tank. Before starting the device, turn all discharge valves to the closed state, then start the vacuum pump and adjust the pressure in the evaporation chamber to the set value; (2) The feed liquid is preheated to a set temperature in the raw material tank, and the temperature in the raw material tank is displayed by a first thermometer; when the temperature of the feed liquid rises to the set temperature, the preheating is completed; (3) Open the first feed valve, the first control valve and the second control valve and start the gear pump to adjust the feed flow rate to the set value, send the feed liquid to the high-pressure atomizing nozzle for pressure atomization, and then spray it into the evaporation chamber in the form of droplets; (4) Turn on the power of the microwave system and adjust the microwave output power of the microwave generator to the set value through the control terminal and the three-pin adjuster; (5) Observe the reading of the optical fiber temperature measurement terminal. When the reading is stable, it indicates that the evaporation process has reached a steady state. The vapor phase produced by evaporation is condensed by the condenser and enters the vapor phase product tank. The droplets that are not completely evaporated settle to the bottom of the evaporation chamber and enter the liquid phase product tank through the liquid phase discharge pipe. (6) When steady-state evaporation is achieved, the reading of the second thermometer is recorded as the vapor phase temperature, the microwave input power value displayed on the control terminal, the feed flow rate displayed by the first mass flow meter and the vapor phase discharge flow rate displayed by the third mass flow meter are recorded, and samples are taken from the vapor phase product tank and the liquid phase product tank for analysis to obtain the gas-liquid phase composition of the evaporation separation under microwave radiation.

8. Use of the device for separating azeotropes by microwave-induced spray evaporation as claimed in any one of claims 1 to 6 in the separation of azeotropic systems and near-boiling systems.

Images