Recovery device for solvent containing heat-sensitive material

Abstract

The utility model provides a heat-sensitive material-containing solvent recovery device, which comprises a first reduced pressure distillation device provided with a first feed end, a first gas phase discharge end and a first liquid phase discharge end; the first feeding end is used for feeding a mixed material, and the mixed material comprises a heat-sensitive material and at least one solvent; the second reduced pressure distillation device is provided with a second feeding end, a second gas phase discharging end and a second liquid phase discharging end; the second feeding end is connected with the first liquid phase discharging end, and the vacuum degree of the second reduced pressure distillation device is larger than that of the first reduced pressure distillation device; the second liquid phase discharge end is used for extracting a heat-sensitive material; the vacuum rectification device is provided with a third feeding end, a light component discharging end and a heavy component discharging end, and the third feeding end is connected with the first gas phase discharging end; and the light component discharge end is used for extracting the solvent. According to the utility model, the solvent is continuously concentrated and separated through distillation and rectification under the condition of pressure reduction, so that the decomposition of heat-sensitive materials in the solvent recovery process is reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of material separation, and in particular relates to a solvent recovery device containing heat-sensitive materials. Background Art

[0002] Heat-sensitive materials are unstable materials that are easily decomposed, polymerized, oxidized, and other deteriorative reactions when exposed to heat. Heat-sensitive materials are commonly found in the fields of medicine, food, spices, petrochemicals, and fine chemicals, such as 1,8-cineole and zedoary oil in the pharmaceutical industry; various heat-sensitive fruit and vegetable juices, citronellol, and citronellal in the food industry; rosemary essential oil, oregano essential oil, eugenol, and other essential oils in the spices industry; and ethanolamine and ethylene glycol in the petrochemical industry.

[0003] For heat-sensitive materials with high boiling points, it is very difficult to separate and recover the solvents containing heat-sensitive materials due to their easy deterioration when heated. If conventional distillation recovery equipment is used to recover the solvents containing heat-sensitive materials, if the heating temperature is too low, the solvent recovery will not be complete, resulting in solvent waste and environmental pollution. If the temperature rises, it is very easy to cause the high-boiling point heat-sensitive materials to deteriorate, resulting in material loss and safety hazards.

[0004] At present, the main technologies for separating solvents containing high-boiling-point heat-sensitive materials are cold separation, molecular distillation and vacuum distillation; among them, cold separation includes crystallization, chromatographic separation and supercritical extraction. Crystallization has high requirements on material composition, and one or more materials must be crystallized within a temperature range that is easier to achieve. It is difficult to meet this condition in practical applications; chromatographic separation is generally not suitable for large-scale industrial production; supercritical extraction uses CO2 as a solvent and can be carried out at room temperature, but its equipment investment is large and the process conditions are very demanding. It is difficult to meet the requirements of process conditions in actual production. Molecular distillation is a single-stage distillation process. Although it can avoid material decomposition, the equipment investment is very high and it is not suitable for large-scale industrial production.

[0005] Distillation is the most common method for purifying and separating multiple components in the prior art, but the conventional vacuum distillation material stays in the evaporator for a long time, and the heat-sensitive material is heated for a long time, which may not be able to effectively avoid the decomposition of the material. In order to ensure that the heat-sensitive material does not decompose during the distillation process, the distillation system requires a higher vacuum degree to control the tower bottom temperature, but at the same time, it will cause the boiling point of the high-purity light component extracted from the top of the tower to decrease, making it difficult to condense. Patent CN111514602A proposes a method and device for removing dichloromethane from high-boiling point heat-sensitive materials. This method is an intermittent operation, using a falling film evaporator and a distillation tower to separate heat-sensitive materials and dichloromethane. The tower bottom evaporation temperature is improved through system improvement, and the system vacuum is indirectly reduced. To a certain extent, the problem of the tower top steam boiling point being too low to condense under high vacuum is solved. However, this solution is to reflux the concentrated liquid back to the tower, which has certain requirements on the cleanliness of the concentrated liquid. If the cleanliness is not high, it is very easy to cause problems such as tower plugging and packing plugging.

[0006] Falling film evaporator and scraped film evaporator are also considered to be suitable for separating heat-sensitive materials. In addition to the aforementioned patent CN111514602A using a falling film evaporator, patent CN 102125770 A uses a combination of a scraped film evaporator and a distillation tower, which effectively solves the problem of coking and scaling of materials that are prone to occur during the separation of heat-sensitive materials. However, the overall energy utilization rate of this solution is low and the energy consumption is high during the treatment process. Patent CN 209934118 U invented a solvent recovery device containing heat-sensitive materials. This method is a continuous operation, using two-effect evaporation and two-effect distillation to achieve material separation, which can improve energy utilization, reduce energy consumption and save costs; but the increase in the number of multiple effects will lead to a smaller temperature difference between each effect, and the required equipment heat exchange area becomes very large. At the same time, the condensation temperature of the last effect is extremely low, and the requirements for the refrigerant are very high.

[0007] It can be seen that in the prior art, the main problems in the separation and recovery of heat-sensitive materials include: 1. Energy utilization problem; 2. Condensation of materials at the top of the tower under high vacuum conditions; 3. The problem that heat-sensitive substances are easily decomposed at high temperatures. Summary of the invention

[0008] In order to solve the problems existing in the above-mentioned prior art, the utility model proposes a solvent recovery device containing heat-sensitive materials, which comprises: a first vacuum distillation device, provided with a first feed end, a first gas phase discharge end and a first liquid phase discharge end; the first feed end is used to input a mixed material, and the mixed material includes a heat-sensitive material and at least one solvent; a second vacuum distillation device, provided with a second feed end, a second gas phase discharge end and a second liquid phase discharge end; wherein the second feed end is connected to the first liquid phase discharge end, and the vacuum degree of the second vacuum distillation device is greater than the vacuum degree of the first vacuum distillation device; the second liquid phase discharge end is used to extract the heat-sensitive material; a vacuum distillation device, provided with a third feed end, a light component discharge end and a heavy component discharge end, wherein the third feed end is connected to the first gas phase discharge end; the light component discharge end is used to extract the solvent.

[0009] Preferably, the first vacuum distillation device comprises a first vacuum distillation device and a second vacuum distillation device connected in series, the liquid phase discharge end of the first vacuum distillation device is connected to the feed end of the second vacuum distillation device, and the vacuum degree of the second vacuum distillation device is greater than the vacuum degree of the first vacuum distillation device. Two-stage evaporation is provided, and vacuum conditions are independently set between the evaporation devices at each stage, so that pressure matching of raw materials at different concentrations can be achieved, and heat-sensitive materials are protected from decomposition.

[0010] Preferably, the first vacuum distillation device comprises a falling film evaporator. Using the falling film evaporator as an evaporation device for vacuum distillation and operating it under reduced pressure to achieve the concentration of high-boiling-point heat-sensitive materials can shorten the residence time of the materials in the high-temperature zone and reduce the possibility of decomposition of heat-sensitive substances.

[0011] Preferably, the second reduced pressure distillation apparatus comprises a wiped film evaporator.

[0012] Preferably, the vacuum distillation device comprises a distillation tower.

[0013] Preferably, a compressor is provided at the light component discharge end, and the first vacuum distillation device is provided with a first heating component. The solvent extracted from the light component discharge end is compressed by the compressor and then sent to the first heating component as a heat source.

[0014] Preferably, the first vacuum distillation apparatus is further provided with an independent heating component parallel to the first heating component, and the independent heating component uses external steam as a heat source. The independent heating component can be provided to maintain the operation of the entire system by externally supplementing steam when the amount of light components in the raw material is small and the compressor is insufficiently heated.

[0015] Preferably, part of the solvent is retained in the bottom of the distillation tower. Retaining the solvent in the bottom of the tower can control the bottom temperature to be below the decomposition temperature of the heat-sensitive material under the condition of relatively mild vacuum degree in the tower, thereby reducing the decomposition of the heat-sensitive material in the whole system (including the falling film evaporation part) by controlling the bottom temperature, and at the same time, better matching the compressed secondary steam with the bottom of the tower to have a sufficient heat exchange temperature difference.

[0016] Preferably, the mixed material includes two solvents with different boiling points, the distillation tower is provided with a top discharge end and a side discharge end, and the solvents are respectively taken out from the top discharge end and the side discharge end after separation.

[0017] Preferably, a compressor is provided at the side discharge end of the tower, and the second vacuum distillation device and the vacuum rectification device are provided with a second heating component and a third heating component respectively. The solvent extracted from the side discharge end of the tower is compressed by the compressor and sent to at least one of the second heating component and the third heating component for recovery as heat source steam. In this preferred solution, a heat pump distillation process is selected in the rectification section, a certain amount of mechanical work is added to the system, and the low-temperature tower top and side line steam are pressurized and heated to be used as the heat source of the evaporator. On the one hand, it solves the problem of low steam temperature and difficult temperature matching under vacuum distillation conditions, and also improves energy utilization.

[0018] The utility model contains a solvent recovery device for heat-sensitive materials.

[0019] The first vacuum distillation device comprises a primary falling film evaporation and a secondary falling film evaporation part, the second vacuum distillation device comprises a scraped film evaporation part, and the vacuum rectification device comprises a rectification tower, wherein:

[0020] The first-stage falling film evaporator includes: two first-stage falling film evaporators arranged in parallel, a first gas-liquid separation tank, a first condensate receiving tank and a centrifugal pump;

[0021] The two-stage falling film evaporation includes: a two-stage falling film evaporator, a second gas-liquid separation tank, a second condensate receiving tank, a centrifugal pump, a first condenser and a vacuum device;

[0022] The distillation tower part includes: distillation tower, tower kettle reboiler, compressor and centrifugal pump;

[0023] The scraped film evaporation part includes: a first scraped film evaporator, a second condenser, a third condensate receiving tank and a vacuum device;

[0024] The first output end of the primary falling film evaporator is connected to the input end of the first gas-liquid separation tank, the gas output end of the first gas-liquid separation tank is connected to the first inlet end of the distillation tower, the liquid output end of the first gas-liquid separation tank is connected to the inlet end of the first centrifugal pump, and the output end of the first centrifugal pump is connected to the input end of the primary falling film evaporator and the input end of the secondary falling film evaporator respectively.

[0025] The second output end of the first falling film evaporator is connected to an input end of the second falling film evaporator, the output end of the second falling film evaporator is connected to the second gas-liquid separation tank, the gas output end of the second gas-liquid separation tank is connected to the first condenser, an output end of the first condenser is connected to an input end of the distillation tower after passing through the second condensate receiving tank and the fourth centrifugal pump, and the liquid output end of the second gas-liquid separation tank is connected to the scraped film evaporator through the third centrifugal pump;

[0026] The output end of the scraped film evaporator is connected to the input end of the secondary falling film evaporator after passing through the second condenser, the third condensate receiving tank, and the seventh centrifugal pump in sequence, and the unevaporated sample is collected from the bottom of the scraped film evaporator tower as product 3;

[0027] The feed of the distillation tower includes a gaseous feed from the primary falling film evaporation and a liquid feed from the secondary falling film evaporation. The top output end of the distillation tower is connected to the primary falling film evaporator and the secondary falling film evaporator via a first compressor, so that the top steam output from the distillation tower is compressed and heated by the first compressor as a heat source for the primary falling film evaporator and the secondary falling film evaporator. The output ends of the primary falling film evaporator and the secondary falling film evaporator are connected to a first condensate receiving tank so that the used steam is temporarily stored in the first condensate receiving tank. The output end of the first condensate receiving tank is connected to a second centrifugal pump so that product 1 is extracted at the output end of the second centrifugal pump.

[0028] The output end of the tower side of the distillation tower is connected to the input end of the second compressor, and the output end of the second compressor is respectively connected to the tower bottom reboiler and the scraped film evaporator, so that the steam extracted from the tower side of the distillation tower is compressed and heated by the second compressor, and used as the heat source of the tower bottom reboiler and the scraped film evaporator. The output end of the tower bottom reboiler is connected to the fourth condensate receiving tank and the sixth centrifugal pump in sequence, and product 2 is extracted at the output end of the sixth centrifugal pump.

[0029] The process flow of the solvent recovery device containing heat-sensitive materials in the utility model is as follows:

[0030] The raw material is a three-component mixed solution, wherein the components are defined as component 1, component 2, and component 3 according to their boiling points from low to high. Component 3 is a high-boiling-point heat-sensitive material, and its boiling point is much higher than that of components 1 and 2. There is no azeotropic phenomenon among the three components. The raw material is pumped to a first-stage falling film evaporator, and steam and a first-stage concentrated liquid are obtained after evaporation, which are sent to a first gas-liquid separation tank for gas-liquid separation. The main components of the separated steam are component 1 and component 2, which enter the distillation tower for further distillation. The separated first-stage concentrated liquid is taken out to a second-stage falling film evaporator.

[0031] The primary concentrated liquid entering the secondary falling film evaporator is evaporated again to produce steam and secondary concentrated liquid, which enter the second gas-liquid separation tank for gas-liquid separation. The separated steam mainly contains component 2 and a small amount of component 3. The steam is condensed into liquid by the first condenser and then enters the distillation tower for further distillation. The secondary concentrated liquid is extracted to the first scraped film evaporator.

[0032] After the secondary concentrate is evaporated in the scraped film evaporator, steam and tertiary concentrate are generated. The main components of the steam are component 2 and component 3. After condensation in the second condenser, it flows back to the secondary falling film evaporator. The tertiary concentrate is component 3, which is discharged from the bottom of the scraped film evaporator.

[0033] The utility model proposes a solvent recovery device containing heat-sensitive materials, and adopts a two-stage vacuum distillation, vacuum rectification, and scraped film distillation design, which continuously concentrates and separates solvents by distillation and rectification under reduced pressure. The falling film evaporator is used as an evaporation device for two-stage vacuum distillation, and is operated under reduced pressure to achieve the concentration of high-boiling point heat-sensitive materials, shorten the residence time of the materials in the high temperature zone, and reduce the possibility of decomposition of heat-sensitive substances; a scraped film distillation device is set after the falling film evaporation device to achieve separation and purification of heat-sensitive materials; a heat pump distillation process is used in the rectification section to achieve temperature matching of evaporation and rectification, while improving energy utilization. The above scheme proposes a comprehensive solution to the recovery of solvents containing heat-sensitive materials, with a simple process design, while solving multiple problems in the prior art such as the difficulty of condensing the top tower material under high vacuum conditions, low energy utilization, and easy decomposition of heat-sensitive substances at high temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a principle block diagram of the utility model;

[0035] Figure 2 It is a schematic diagram of a solvent recovery device containing heat-sensitive materials in a specific embodiment of the utility model;

[0036] Figure 3 for Figure 2 Partial view of K1;

[0037] Figure 4 for Figure 2 Partial view of K2;

[0038] Figure 5 for Figure 2 Partial view of K3;

[0039] Figure 6 for Figure 2 Partial view of K4. DETAILED DESCRIPTION

[0040] The utility model is further described below in conjunction with the accompanying drawings and specific implementation methods.

[0041] In a specific embodiment, a solvent recovery device containing heat-sensitive materials is provided, which is used to separate and recover the solvent containing heat-sensitive materials. The device includes: a first vacuum distillation device A1, a second vacuum distillation device A5 and a vacuum rectification device A9, wherein the first and second vacuum distillation devices are independently set with vacuum conditions, and the vacuum degree increases gradually. The raw material is pumped into the first vacuum distillation device, and after preliminary separation, the heavy phase of the heat-sensitive material is sent to the second vacuum distillation device for further separation, and the light phase of the solvent is sent to the vacuum rectification device.

[0042] In order to solve the problem that heat-sensitive materials are easy to decompose at high temperatures, in addition to the method of reducing the boiling point of the material by reducing pressure in the above-mentioned embodiment, shortening the residence time of the material in the high temperature zone is also an important solution. In the selection of the evaporation device, it is necessary to select an evaporation device that can shorten the residence time of the material as much as possible to further reduce the possibility of decomposition of the heat-sensitive material. Based on this standard, in the preferred embodiment, falling film evaporation and scraped film evaporation devices are selected as the first vacuum distillation device evaporator and the second vacuum distillation device evaporator. Both evaporators have the advantage of short residence time. The difference is that the falling film evaporator has a larger heat transfer area under the same volume, less investment, and is more suitable for industrial processing of large quantities of materials. The scraped film evaporator is more suitable for materials with high viscosity and easy scaling. Combined with its characteristics, the design of this preferred embodiment shortens the residence time of heat-sensitive materials in the high temperature section to the greatest extent.

[0043] In another preferred embodiment, for the recovery of multi-component solvents, a side-line extraction scheme of a distillation tower is proposed. In the conventional distillation process, the light component product is extracted from the top of the distillation tower, and the heavy component product is extracted from the bottom of the tower, which can only achieve the separation of two components. If the three-component system is separated, it needs to be achieved through two distillation towers. The side-line extraction scheme adopted in this embodiment can achieve the separation of the three-component system through a distillation tower, which can reduce equipment investment, simplify the separation system, and greatly reduce the equipment footprint in industrial applications.

[0044] Figure 1 The schematic diagram of a solvent recovery device containing heat-sensitive materials in a specific embodiment of the utility model is shown in FIG. In the system of the present embodiment, the first vacuum distillation device A1 includes a primary falling film evaporation and a secondary falling film evaporation part, the second vacuum distillation device A5 includes a scraped film evaporation part, and the vacuum rectification device A9 includes a rectification tower (i.e., including a primary falling film evaporation, a secondary falling film evaporation, a rectification tower, and a scraped film evaporation four parts), wherein:

[0045] The first-stage falling film evaporation part includes: two first-stage falling film evaporators E-101A / B arranged in parallel, the first gas-liquid separation tank V-101, the first condensate receiving tank V-102 and a centrifugal pump, etc.;

[0046] The secondary falling film evaporation part includes: secondary falling film evaporator E-102, second gas-liquid separation tank V-103, second condensate receiving tank V-104, centrifugal pump, first condenser E-103 and vacuum device, etc.;

[0047] The distillation tower part includes: distillation tower T-101, tower kettle reboiler E-104, compressor and centrifugal pump, etc.;

[0048] The scraped film evaporation part includes: the first scraped film evaporator E-106, the second condenser E-107, the third condensate receiving tank V-106 and the vacuum device, etc.;

[0049] The first output end of the first falling film evaporator E-101 is connected to the input end of the first gas-liquid separation tank V-101, the gas output end of the first gas-liquid separation tank V-101 is connected to the first inlet end of the distillation tower T-101, the liquid output end of the first gas-liquid separation tank V-101 is connected to the inlet end of the first centrifugal pump P-101, and the output end of the first centrifugal pump P-101 is respectively connected to the input end of the first falling film evaporator E-101 and the input end of the second falling film evaporator E-102.

[0050] The second output end of the first-stage falling film evaporator E-101 is connected to an input end of the second-stage falling film evaporator E-102, the output end of the second-stage falling film evaporator E-102 is connected to the second gas-liquid separation tank V-103, the gas output end of the second gas-liquid separation tank V-103 is connected to the first condenser E-103, an output end of the first condenser E-103 is connected to an input end of the distillation tower T-101 after passing through the second condensate receiving tank V-104 and the fourth centrifugal pump P-104, and the liquid output end of the second gas-liquid separation tank V-103 is connected to the scraped film evaporator E-106 through the third centrifugal pump P-103;

[0051] The output end of the scraped film evaporator E-106 is connected to the input end of the secondary falling film evaporator E-102 after passing through the second condenser E-107, the third condensate receiving tank V-106, and the seventh centrifugal pump P-107 in sequence. The unevaporated sample is collected from the bottom of the scraped film evaporator E-106 tower as product 3;

[0052] The feed of the distillation tower T-101 includes a gaseous feed from the primary falling film evaporation and a liquid feed from the secondary falling film evaporation. The top output end of the distillation tower T-101 is connected to the primary falling film evaporator E-101 and the secondary falling film evaporator E-102 via the first compressor C-101, so that the top steam output from the distillation tower T-101 is compressed and heated by the first compressor C-101 as a heat source for the primary falling film evaporator E-101 and the secondary falling film evaporator E-102. The output ends of the primary falling film evaporator E-101 and the secondary falling film evaporator E-102 are connected to the first condensate receiving tank V-102, so that the used steam is temporarily stored by the first condensate receiving tank V-102. The output end of the first condensate receiving tank V-102 is connected to the second centrifugal pump P-102, so that the product is extracted at the output end of the second centrifugal pump P-102 as product 1;

[0053] The output end of the tower side of the distillation tower T-101 is connected to the input end of the second compressor C-102, and the output end of the second compressor C-102 is respectively connected to the tower bottom reboiler E-104 and the scraped film evaporator E-106, so that the steam extracted from the tower side of the distillation tower T-101 is compressed and heated by the second compressor C-102, and used as the heat source of the tower bottom reboiler E-104 and the scraped film evaporator E-106. The output end of the tower bottom reboiler E-104 is connected to the fourth condensate receiving tank V-105 and the sixth centrifugal pump P-106 in sequence, and product 2 is extracted at the output end of the sixth centrifugal pump P-106.

[0054] The input end of the first falling film evaporator E-101 connected to the output end of the first centrifugal pump P-101 serves as its raw material input end, the input end of the second falling film evaporator E-102 connected to the output end of the first centrifugal pump P-101 serves as its raw material input end, and is also connected to the output end of the third centrifugal pump P-103.

[0055] An output end of the first condenser E-103 is connected to the second vacuum device, and the first condenser E-103 is provided with a refrigerant inlet and outlet.

[0056] The bottom of the distillation tower T-101 is connected to the fifth centrifugal pump P-105, and the outlet of the fifth centrifugal pump P-105 is connected to the raw material input end of the secondary falling film evaporator E-102 to return the extracted heavy components to the secondary falling film evaporator E-102.

[0057] The fourth condensate receiver V-105 is connected in parallel with the fourth condenser E-105. The fourth condenser E-105 has a venting output terminal and a refrigerant inlet and outlet. The second condenser E-107 is connected to the third vacuum device and the third condenser E-107 has a refrigerant inlet and outlet.

[0058] If the compressor is not sufficiently heated due to a small amount of light components in the raw materials, a parallel evaporator similar to the primary falling film evaporation link can be set in the secondary falling film evaporation link, and external steam can be added to maintain the operation of the entire system.

[0059] If the heat exchange temperature difference is insufficient due to the limitation of the compressor compression capacity (insufficient compression ratio), additional compressors can be connected in series for multi-stage compression so that the steam meets the compression steam temperature requirement.

[0060] The vacuum condition of the first-stage falling film evaporator E-101 is the same as that of the distillation tower T-101, recorded as vacuum 1; the vacuum condition of the second-stage falling film evaporator E-102 is set separately, recorded as vacuum 2; the vacuum condition of the scraped film evaporator is set separately, recorded as vacuum 3, and the vacuum degree relationship is vacuum 1 < vacuum 2 < vacuum 3.

[0061] The following are applications Figure 1 The process description of the solvent recovery device shown in the figure is to separate the raw material of a ternary mixed solution containing a high-boiling-point heat-sensitive material. In this embodiment, the raw material is a three-component mixed solution, wherein each component is defined as component 1, component 2, and component 3 according to its boiling point from low to high, and component 3 is a high-boiling-point heat-sensitive material, and its boiling point is much higher than that of components 1 and 2, and there is no azeotropic phenomenon among the three components. In this embodiment, the raw material is pumped to the first-level falling film evaporator E-101A / B, and steam and a first-level concentrated liquid are obtained after evaporation, and are sent to the first gas-liquid separation tank V-101 for gas-liquid separation. The main components of the separated steam are component 1 and component 2, which enter the distillation tower T-101 for further distillation; the separated first-level concentrated liquid is extracted to the second-level falling film evaporator E-102.

[0062] The primary concentrated liquid entering the secondary falling film evaporator E-102 is evaporated again to produce steam and secondary concentrated liquid, which enter the second gas-liquid separation tank V-103 for gas-liquid separation. The separated steam mainly contains component 2 and a small amount of component 3. The steam is condensed into liquid by the first condenser E-103 and then enters the distillation tower T-101 for further distillation. The secondary concentrated liquid is extracted into the first scraped film evaporator E-106.

[0063] After the secondary concentrate is evaporated by the scraped film evaporator, steam and tertiary concentrate are generated. The main components of the steam are component 2 and component 3. After condensation by the second condenser E-107, it flows back to the secondary falling film evaporator E-102. The tertiary concentrate is component 3, which is discharged from the bottom of the scraped film evaporator E-106.

[0064] In this embodiment, the feed in the distillation tower T-101 includes the gas phase feed from the first-stage falling film evaporator E-101 and the steam condensate from the second-stage falling film evaporator E-102. After two-stage vacuum distillation, the heat-sensitive materials in the solvent have been quickly separated, and the materials entering the distillation tower T-101 are mainly component 1 and component 2. They can be separated by simple distillation purification, and component 1 is extracted from the top of the tower and component 2 is extracted from the side line of the tower. In other embodiments, if it is a single-component solvent, the side line extraction can be cancelled.

[0065] In a preferred embodiment, based on the coupling of the aforementioned two-stage vacuum distillation and vacuum rectification, a heat pump distillation process is selected in the rectification process to add a certain amount of mechanical work to the system, pressurize and heat the lower temperature tower top and side line steam, and use them as the heat source of the evaporator. The tower top steam can be used as a heat source for the first-stage falling film evaporator and the second-stage falling film evaporator after compression, and the side line steam can be used as a heat source for the tower bottom and the scraped film evaporation device after compression. On the one hand, this solution can solve the problem of low steam temperature and difficult temperature matching under vacuum distillation conditions, and also improve energy utilization. In conventional distillation, the condensation temperature of the tower top is low under high vacuum, and it is difficult to match the condensation temperature by circulating cooling water (normal temperature) for heat exchange, while the heat pump distillation designed in this solution can solve the problem of temperature matching. Specifically, after distillation and purification, the top vapor is component 1, which is compressed and heated by the first compressor C-101 and used as the heat source for the first-stage falling film evaporator E-101 and the second-stage falling film evaporator E-102. After use, the steam is temporarily stored in the first condensate receiving tank V-102 and extracted by the second centrifugal pump P-102; component 2 is extracted from the side line of the tower, which is compressed and heated by the second compressor C-102 and used as the heat source for the bottom reboiler and the scraped film evaporator. After use, the steam is temporarily stored in the fourth condensate receiving tank V-105 and extracted by the sixth centrifugal pump P-106.

[0066] In another preferred embodiment, when component 2 is extracted from the side line of distillation tower T-101, part of component 2 is retained in the distillation tower to ensure that the bottom temperature is not too high, thereby reducing the decomposition of heat-sensitive substances and better matching the temperature of the compressed secondary steam with the bottom temperature to ensure sufficient heat exchange temperature difference.

[0067] This embodiment uses vacuum distillation and rectification process to separate raw materials mixed with components 1, 2, and 3, wherein the boiling points of the three components are ranked from low to high. The light and heavy components in the mixed solution are initially separated by distillation, and during the rectification process, the light component 1 product is extracted from the top of the tower, part of the component 2 is extracted from the side line, and the mixed liquid of component 2 and component 3 is extracted from the bottom of the tower for the next stage of separation. Due to the presence of component 2 in the mixed liquid, the tower vacuum does not need to be too high and the bottom temperature can be controlled below the decomposition temperature of component 3; in addition, the steam from the top of the tower and the side line is also utilized by increasing the pressure of the compressor, which also makes the light component steam easier to condense; the above design is combined to solve the problem that the top material is difficult to condense under high vacuum conditions.

[0068] In another specific embodiment, the solvent recovery device containing heat-sensitive materials proposed in the utility model is used to separate and recover the solvent of a mixture containing three substances: water, acetic acid and carveol. In the mixture, carveol is a high-boiling-point, heat-sensitive material. Specifically, the raw material is put into the primary falling film evaporator E-101, and the vacuum pump of the primary falling film evaporator E-101 is turned on to draw the vacuum to -50kPa~-60kPa. After the vacuum is reached, the primary falling film evaporator E-101 is heated by steam, and after separation by the first gas-liquid separation tank V-101, the gas phase enters the distillation tower T-101, and the liquid phase is partially cyclically evaporated, that is, the primary falling film concentrate enters the secondary falling film evaporator E-102 for heating and evaporation. After the top steam of the distillation tower T-101 is compressed by the first compressor C-101, part of it is sent to the primary falling film evaporator E-101 as a heat source, and the other part is sent to the secondary falling film evaporator E-102 as a heat source.

[0069] After the first-stage falling film concentrated liquid is drawn out to the second-stage falling film evaporator, the vacuum pump of the second-stage falling film evaporator E-102 is turned on to evacuate the system to -70kPa~-80kPa. After the vacuum is reached, the secondary steam compressed at the top of the tower is introduced for heating and evaporation. After the gas and liquid produced by evaporation in the second-stage falling film evaporator E-102 are separated, the gas phase is condensed and enters the distillation tower T-101, and the liquid phase enters the first scraped film evaporator E-106 for re-concentration.

[0070] When the secondary falling film reaches the concentrated concentration, it is necessary to open the vacuum pump of the scraped film evaporator before discharging the material to the scraped film evaporator, and draw the vacuum to -80kPa~-90kPa. At this time, the second compressor C-102 on the side line of the distillation tower is started to compress the steam in the tower and use it as the heat source for the tower kettle reboiler E-104 and the scraped film evaporator E-106.

[0071] At this point, all the equipment has been started and operated. After the parameters are adjusted and the logistics flow rate is stabilized, water with qualified purity is produced from the top of the distillation tower, acetic acid with qualified purity is produced from the side line of the distillation tower, and light components entrained with qualified carveol products are produced from the concentrated liquid of the wiped film evaporator. After the operation is stable, each product outlet stably produces products.

[0072] This embodiment achieves the separation of water, acetic acid and carveol, wherein the purity of each product is greater than 99%. In addition, compressors are arranged at the top and side of the distillation tower, and the latent heat energy of the steam produced by the distillation tower is fully utilized through the heat pump. During stable operation, only a certain amount of steam needs to be added in the first-stage falling film evaporation link to maintain the operation of the entire system. At the same time, relying on the effect of the heat pump, the problem of the difficulty in condensing the top material is solved. The use of a heat pump can save the condensation device at the top and side line of the distillation tower, saving equipment investment and cooling water operation costs. In this embodiment, the material temperature of each link is controlled below 120°C. After material balance, the loss of carveol due to thermal decomposition is less than 0.5%.

[0073] The utility model adopts the scheme of two-stage vacuum distillation, vacuum rectification and scraped film distillation, uses the falling film evaporator as the evaporation device of the two-stage vacuum distillation, operates under reduced pressure conditions to achieve the concentration of high-boiling point heat-sensitive materials, shorten the residence time of the materials in the high temperature zone, and reduce the decomposition possibility of heat-sensitive substances; sets two-stage falling film evaporation, and sets independent vacuum conditions between each stage of falling film evaporation devices to achieve pressure matching of raw materials at different concentrations, protecting heat-sensitive materials from decomposition; sets a scraped film distillation device after the falling film evaporation device to achieve separation and purification of heat-sensitive materials; adopts a heat pump distillation process in the rectification section to improve energy utilization. This scheme is a comprehensive process for solvent recovery of high-boiling point heat-sensitive materials, which can be applied to the synthesis and separation processes of various heat-sensitive materials and has broad application prospects.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model rather than to limit it. Although the utility model has been described in detail with reference to the preferred embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the utility model can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solution of the utility model, which should be included in the scope of the technical solution for protection of the utility model.

Claims

1. A solvent recovery device containing heat-sensitive materials, characterized in that: The device comprises: The first vacuum distillation device (A1) is provided with a first feed end (A2), a first gas phase discharge end (A3) and a first liquid phase discharge end (A4); the first feed end is used for feeding the mixed material; A second vacuum distillation device (A5) is provided with a second feed end (A6), a second gas phase discharge end (A7) and a second liquid phase discharge end (A8); wherein the second feed end (A6) is connected to the first liquid phase discharge end (A4); the vacuum degree of the second vacuum distillation device is greater than the vacuum degree of the first vacuum distillation device; and the second liquid phase discharge end is used to extract the heat-sensitive material; A vacuum distillation device (A9) is provided with a third feed end (A10), a light component discharge end (A11) and a heavy component discharge end (A12), wherein the third feed end (A10) is connected to the first gas phase discharge end (A3); and the light component discharge end is used to extract the solvent.

2. The solvent recovery device containing heat-sensitive materials according to claim 1, characterized in that: The first vacuum distillation device (A1) comprises a first vacuum distillation device (A13) and a second vacuum distillation device (A14) connected in series, wherein the liquid phase discharge end of the first vacuum distillation device is connected to the feed end of the second vacuum distillation device, and the vacuum degree of the second vacuum distillation device is greater than the vacuum degree of the first vacuum distillation device.

3. The solvent recovery device containing heat-sensitive materials according to claim 1, characterized in that: The first vacuum distillation apparatus comprises a falling film evaporator; the second vacuum distillation apparatus comprises a wiped film evaporator; and the vacuum rectification apparatus comprises a rectification tower.

4. The solvent recovery device containing heat-sensitive materials according to claim 3, characterized in that: The light component discharge end is provided with a compressor, and the first vacuum distillation device is provided with a first heating component. The solvent extracted from the light component discharge end is compressed by the compressor and then sent to the first heating component as a heat source.

5. The solvent recovery device containing heat-sensitive materials according to claim 4, characterized in that: The first vacuum distillation device is also provided with an independent heating component parallel to the first heating component, and the independent heating component uses external steam as a heat source.

6. The solvent recovery device containing heat-sensitive materials according to claim 3, characterized in that: The mixed material includes two solvents with different boiling points. The distillation tower is provided with a tower top discharge end and a tower side discharge end. The solvents are respectively extracted from the tower top discharge end and the tower side discharge end after separation.

7. The solvent recovery device containing heat-sensitive materials according to claim 6, characterized in that: The side discharge end of the tower is provided with a compressor, and the second vacuum distillation device and the vacuum rectification device are respectively provided with a second heating component and a third heating component. The solvent extracted from the side discharge end of the tower is compressed by the compressor and then sent to at least one of the second heating component and the third heating component as a heat source.

8. The solvent recovery device containing heat-sensitive materials according to any one of claims 1 to 7, characterized in that: The first vacuum distillation apparatus (A1) comprises a primary falling film evaporation part and a secondary falling film evaporation part, the second vacuum distillation apparatus (A5) comprises a scraped film evaporation part, and the vacuum rectification apparatus (A9) comprises a rectification tower, wherein: The first-stage falling film evaporation part includes: two first-stage falling film evaporators (E-101A / B) arranged in parallel, the first gas-liquid separation tank (V-101), the first condensate receiving tank (V-102) and a centrifugal pump; The secondary falling film evaporation part includes: a secondary falling film evaporator (E-102), a second gas-liquid separation tank (V-103), a second condensate receiving tank (V-104), a centrifugal pump, a first condenser (E-103) and a vacuum device; The distillation tower part includes: distillation tower (T-101), tower kettle reboiler (E-104), compressor and centrifugal pump; The scraped film evaporation part includes: a first scraped film evaporator (E-106), a second condenser (E-107), a third condensate receiving tank (V-106) and a vacuum device; The first output end of the first falling film evaporator (E-101) is connected to the input end of the first gas-liquid separation tank (V-101), the gas output end of the first gas-liquid separation tank (V-101) is connected to the first inlet end of the distillation tower (T-101), the liquid output end of the first gas-liquid separation tank (V-101) is connected to the inlet end of the first centrifugal pump (P-101), and the output end of the first centrifugal pump (P-101) is respectively connected to the input end of the first falling film evaporator (E-101) and the input end of the second falling film evaporator (E-102). The second output end of the first falling film evaporator (E-101) is connected to an input end of the second falling film evaporator (E-102), the output end of the second falling film evaporator (E-102) is connected to the second gas-liquid separation tank (V-103), the gas output end of the second gas-liquid separation tank (V-103) is connected to the first condenser (E-103), an output end of the first condenser (E-103) is connected to an input end of the distillation tower (T-101) after passing through the second condensate receiving tank (V-104) and the fourth centrifugal pump (P-104), and the liquid output end of the second gas-liquid separation tank (V-103) is connected to the scraped film evaporator (E-106) through the third centrifugal pump (P-103); The output end of the scraped film evaporator (E-106) is connected to the input end of the secondary falling film evaporator (E-102) after passing through the second condenser (E-107), the third condensate receiving tank (V-106), and the seventh centrifugal pump (P-107) in sequence, and the unevaporated sample is collected from the bottom of the scraped film evaporator (E-106); The feed of the distillation tower (T-101) includes a gaseous feed from the primary falling film evaporator and a liquid feed from the secondary falling film evaporator. The top output end of the distillation tower (T-101) is connected to the primary falling film evaporator (E-101) and the secondary falling film evaporator (E-102) via the first compressor (C-101), so that the top vapor output from the distillation tower (T-101) is compressed and heated by the first compressor (C-101) as the primary falling film evaporator (E-102). 1) and the heat source of the secondary falling film evaporator (E-102), the output ends of the primary falling film evaporator (E-101) and the secondary falling film evaporator (E-102) are connected to the first condensate receiving tank (V-102), so that the used steam is temporarily stored by the first condensate receiving tank (V-102), and the output end of the first condensate receiving tank (V-102) is connected to the second centrifugal pump (P-102) to extract the product at the output end of the second centrifugal pump (P-102); The output end of the tower side of the distillation tower (T-101) is connected to the input end of the second compressor (C-102), and the output end of the second compressor (C-102) is respectively connected to the tower bottom reboiler (E-104) and the scraped film evaporator (E-106), so that the steam extracted from the tower side of the distillation tower (T-101) is compressed and heated by the second compressor (C-102) and used as the heat source of the tower bottom reboiler (E-104) and the scraped film evaporator (E-106). The output end of the tower bottom reboiler (E-104) is connected to the fourth condensate receiving tank (V-105) and the sixth centrifugal pump (P-106) in turn, and is extracted at the output end of the sixth centrifugal pump (P-106).

9. The solvent recovery device containing heat-sensitive materials according to claim 8, characterized in that: The input end of the first falling film evaporator (E-101) connected to the output end of the first centrifugal pump (P-101) serves as its raw material input end, the input end of the second falling film evaporator (E-102) connected to the output end of the first centrifugal pump (P-101) serves as its raw material input end, and is also connected to the output end of the third centrifugal pump (P-103).

10. The solvent recovery device containing heat-sensitive materials according to claim 9, characterized in that: An output end of the first condenser (E-103) is connected to the second vacuum device, and the first condenser (E-103) is provided with a refrigerant inlet and outlet; the bottom of the distillation tower (T-101) is connected to the fifth centrifugal pump (P-105), and the output end of the fifth centrifugal pump (P-105) is connected to the raw material input end of the secondary falling film evaporator (E-102) to return the extracted heavy components to the secondary falling film evaporator (E-102); the fourth condensate receiving tank (V-105) is connected in parallel with the fourth condenser (E-105), and the fourth condenser (E-105) has a venting output end, and the fourth condenser (E-105) is provided with a refrigerant inlet and outlet; the above-mentioned second condenser (E-107) is connected to the third vacuum device, and the second condenser (E-107) is provided with a refrigerant inlet and outlet.

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