Novel waste organic solvent recovery treatment method

Abstract

The present invention relates to the technical field of solvent recovery, and discloses a novel waste organic solvent recovery treatment method, which comprises: S1, feeding a waste liquid containing 50% of benzene, 15% of tetrahydrofuran, 12% of tert-butyl acetate, 10% of tert-butanol, 8% of water and 5% of ethanol into a fractionating tower to separate; s2, mixing the mixture of tetrahydrofuran and tert-butyl acetate collected at the top of the rectifying tower with pure water in proportion, and extracting through a separating funnel; s3, feeding a mixed solution of tetrahydrofuran and tert-butyl acetate separated in S2 into a reduced pressure rectifying tower for further separation; s4, rectifying and separating the mixture of the tert-butyl alcohol and the ethanol; s5, all the components are treated through an adsorption dehydration technology; s6, solvent steam generated in the rectifying tower and the adsorption dehydration process is condensed and recycled through a condenser. According to the invention, through multi-stage fractionation, extraction, adsorption dehydration and other processes, the recovery rate and purity of the waste organic solvent are effectively improved, and the waste of the solvent is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of solvent recovery, and in particular to a novel method for recovering and treating waste organic solvents. Background Art

[0002] With the acceleration of industrialization, especially the rapid development of chemical, pharmaceutical, petrochemical, electronic manufacturing and other industries, the current recycling and treatment technologies of waste organic solvents mainly include distillation, adsorption, condensation, liquid-liquid extraction and membrane separation. Although these traditional technologies have certain recycling effects in some occasions, there are still some shortcomings and they cannot meet the needs of modern industry for recycling efficiency, environmental protection requirements and cost control.

[0003] Distillation: Distillation is one of the most commonly used methods for recycling waste organic solvents. By taking advantage of the difference in boiling points between the solvent and the pollutant, the solvent is evaporated by heating, and the vapor is condensed into liquid by a condensing device. The distillation process usually requires high temperatures and a large amount of heat energy when recovering solvents, resulting in high energy consumption. In addition, the design of the distillation tower is complex, and the control requirements for temperature and reflux ratio during operation are high. Especially when dealing with waste liquid containing multiple solvents, the distillation effect is not ideal.

[0004] Adsorption method: Adsorption is the process of adsorbing solvents and pollutants in waste liquids through solid adsorbents (such as activated carbon, silica gel, molecular sieves, etc.). During the adsorption process, the solvent will be captured by the surface of the adsorbent to achieve the purpose of removing impurities. Although the adsorption method is simple to operate and can treat more complex waste liquids, the saturation of the adsorbent limits its application cycle, and the adsorption process often cannot completely remove all pollutants at one time, and the adsorbent needs to be replaced multiple times, resulting in high operating costs.

[0005] Condensation method: The condensation method is suitable for treating waste gas or waste solvents containing volatile organic compounds (VOCs). The steam is cooled to a liquid state through a condensation device to separate the solvent. However, the condensation method has strict requirements on temperature control, and its effect is significantly reduced when the concentration of organic matter in the waste gas is low. It also has high energy consumption, which limits its application in the treatment of certain waste liquids.

[0006] Liquid-liquid extraction: Liquid-liquid extraction technology uses two immiscible liquid solvents to distribute the target solute from the waste liquid by virtue of the difference in the solvent's affinity for certain chemical substances. This method is applicable to a variety of solvents and waste liquid types, but the solvent selection is often limited, and the solvent regeneration process is relatively complex, with high requirements for equipment and operating conditions.

[0007] Membrane separation method: Membrane separation technology (such as ultrafiltration, reverse osmosis, nanofiltration, etc.) separates the solvent and pollutants in the waste liquid by selectively permeating the membrane material. The membrane separation method has high separation accuracy and low energy consumption, but the pollution and clogging of the membrane often limit its application. Especially when treating high-concentration organic waste liquid, the durability and selectivity of the membrane material are still the bottleneck of the development of this technology.

[0008] To this end, we propose a new method for recycling and treating waste organic solvents. Summary of the invention

[0009] The present invention mainly solves the technical problems existing in the above-mentioned prior art and provides a novel method for recovering and treating waste organic solvents.

[0010] In order to achieve the above object, the present invention adopts the following technical scheme, a novel method for recovering and treating waste organic solvents, comprising the following steps:

[0011] S1: sending the waste liquid containing 50% benzene, 15% tetrahydrofuran (THF), 12% tert-butyl acetate (TBA), 10% tert-butyl alcohol, 8% water and 5% ethanol into a fractionation tower for separation;

[0012] S2: The mixture of tetrahydrofuran (THF) and tert-butyl acetate (TBA) collected from the top of the distillation tower is mixed with pure water in proportion to form a two-phase liquid, and extraction is performed through a separatory funnel;

[0013] S3: The mixed solution of tetrahydrofuran (THF) and tert-butyl acetate (TBA) separated in S2 is sent to a vacuum distillation tower for further separation;

[0014] S4: The mixture of tert-butyl alcohol and ethanol is separated by distillation. First, the mixture entering this step is dried to remove the water therein, and the dried mixture is sent to a distillation tower;

[0015] S5: Treat each component through an adsorption dehydration process. Tetrahydrofuran (THF) and tert-butyl acetate (TBA) are usually dehydrated using activated alumina as an adsorbent to ensure that the moisture content is controlled below 0.05%;

[0016] S6: The solvent vapor generated in the distillation tower and adsorption dehydration process will be condensed and recovered through the condenser. The condenser is set at 30°C. The recovered solvents such as benzene, tetrahydrofuran, tert-butyl acetate, etc. can be recycled after further filtration and purification.

[0017] Preferably, in S1, the feed rate of the waste liquid is 0.6L / h-1.0L / h, the bottom temperature is set to 135°C-140°C, the top temperature is 105°C-110°C, the operating pressure is normal pressure of 101.3kPa, and the reflux ratio is set to 4-6.

[0018] Preferably, in S2, a mixture of tetrahydrofuran (THF) and tert-butyl acetate (TBA) is mixed with pure water in a volume ratio of 1:0.5-1:0.7, the temperature of the separation process is maintained at room temperature 30°C, and the extraction time is 15 minutes to 20 minutes.

[0019] Preferably, in S3, the operating pressure is set to 20 kPa-35 kPa, the tower bottom temperature is 90°C-95°C, the tower top temperature is 80°C-85°C, and the reflux ratio is set to 3-5.

[0020] Preferably, in S4, the operating pressure is maintained at 101.3 kPa at normal pressure, the tower bottom temperature is set to 65°C-75°C, the tower top temperature is set to 60°C-70°C, and the reflux ratio is set to 2-3.

[0021] Preferably, in S5, tetrahydrofuran (THF) and tert-butyl acetate (TBA) are usually dehydrated using activated alumina as an adsorbent to ensure that the moisture content is controlled below 0.1%-0.05%, and tert-butyl alcohol and ethanol are dehydrated using molecular sieves to ensure that the moisture content of the final product is extremely low. The adsorption process is carried out at room temperature and the adsorption time is usually 2-4 hours.

[0022] Preferably, in S6, the condenser is set at a temperature of 25°C-30°C.

[0023] The present invention provides a novel method for recycling and treating waste organic solvents. It has the following beneficial effects:

[0024] 1. This novel method for recovering and treating waste organic solvents effectively improves the recovery rate and purity of waste organic solvents (such as benzene, tetrahydrofuran, tert-butyl acetate, etc.) through multi-stage fractionation, extraction and adsorption dehydration processes. The distillation and vacuum distillation operations can achieve efficient separation, and the recovered solvent can reach a high purity, which is suitable for further industrial applications, reducing the waste of solvents.

[0025] 2. This is a new method for recycling and treating waste organic solvents. Compared with traditional recycling methods, this process optimizes energy consumption through low-temperature operations such as distillation and adsorption, especially in the design of distillation towers and condensers. By setting appropriate operating temperature and pressure, the energy loss in the distillation process is reduced, which helps to reduce overall energy consumption.

[0026] 3. This new method for recycling and treating waste organic solvents simplifies the traditional complex treatment process into several key steps, including fractionation, liquid separation, vacuum distillation and adsorption dehydration. By optimizing the process flow, the operation is simpler, automatic control can be achieved, manual intervention can be reduced, and production efficiency is improved.

[0027] 4. This novel method for recycling and treating waste organic solvents adopts low-energy consumption and low-emission processes during operation, especially through effective extraction and adsorption dehydration technology, which reduces the emission of wastewater and waste gas, meets the requirements of modern industry for environmental protection, and helps to reduce environmental pollution.

[0028] 5. This new method for recycling and treating waste organic solvents not only reduces the cost of solvent procurement, but also reduces the cost of waste treatment by recycling and reusing waste organic solvents. By improving the recovery rate and recycling of solvents, the economic benefits of enterprises have been improved. It is especially suitable for the recycling of waste solvents in large-scale industrial production and has strong market competitiveness. DETAILED DESCRIPTION

[0029] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Embodiment 1: A novel method for recovering and treating waste organic solvents comprises the following steps:

[0031] S1: The waste liquid containing 50% benzene, 15% tetrahydrofuran (THF), 12% tert-butyl acetate (TBA), 10% tert-butyl alcohol, 8% water and 5% ethanol is fed into a fractionation tower for separation. The feed rate of the waste liquid is 1.0L / h, the tower bottom temperature is set to 140°C, the tower top temperature is 110°C, the operating pressure is 101.3kPa at normal pressure, and the reflux ratio is set to 4. Through this distillation process, benzene is collected at the bottom of the tower as a heavy component, while tetrahydrofuran (THF), tert-butyl acetate (TBA) and other light components evaporate to the top of the tower. The recovery rate of benzene is about 65%, and the benzene can be used for industrial applications;

[0032] S2: The mixture of tetrahydrofuran (THF) and tert-butyl acetate (TBA) collected from the top of the distillation tower is mixed with pure water at a volume ratio of 1:0.6 to form a two-phase liquid. The mixed liquid is extracted through a separatory funnel, gently shaken and allowed to stand to separate the two phases. The aqueous phase and the organic phase are separated during the extraction process, wherein the upper layer contains a mixture of tetrahydrofuran and tert-butyl acetate, and the lower layer contains a mixture of tert-butyl alcohol and ethanol. The temperature of this separation process is maintained at room temperature (30° C.), and the extraction time is 20 minutes to ensure efficient stratification. Through this process, tetrahydrofuran and tert-butyl acetate are effectively separated, providing a pure organic solvent for subsequent treatment;

[0033] S3: The tetrahydrofuran (THF) and tert-butyl acetate (TBA) mixture separated in S2 is sent to a vacuum distillation tower for further separation. The operating pressure is set to 35 kPa, the tower bottom temperature is 95 ° C, the tower top temperature is 85 ° C, and the reflux ratio is set to 3. Through this fractionation operation, tetrahydrofuran is evaporated first and collected as the tower top product, while tert-butyl acetate is collected as the tower bottom product. The recovery rate of tetrahydrofuran can reach 85%, and the purity of tert-butyl acetate can also be increased to more than 98%;

[0034] S4: The mixture of tert-butanol and ethanol will be separated by distillation. First, the mixture entering this step is dried to remove the moisture therein. The dried mixture is sent to a distillation tower. The operating pressure is maintained at 101.3 kPa at normal pressure. The tower bottom temperature is set to 65°C, the tower top temperature is 60°C, and the reflux ratio is set to 3. After this distillation process, ethanol evaporates from the tower top as a light component, and finally high-purity ethanol is obtained. Tert-butanol is collected as the tower bottom product and further dried to obtain industrial-grade tert-butanol.

[0035] S5: In order to further remove the moisture in the distillation product, in S5, each component is treated by an adsorption dehydration process. Tetrahydrofuran (THF) and tert-butyl acetate (TBA) are usually dehydrated using activated alumina as an adsorbent to ensure that the moisture content is controlled below 0.05%. Tert-butyl alcohol and ethanol are dehydrated using molecular sieves to ensure that the moisture content of the final product is extremely low. The adsorption process is carried out at room temperature and the adsorption time is usually 2 hours. Each product can eventually reach the industrial purity standard;

[0036] S6: The solvent vapor generated in the distillation tower and adsorption dehydration process will be condensed and recovered through the condenser. The set temperature of the condenser is 30°C. The benzene, tetrahydrofuran, tert-butyl acetate, etc. contained in the condensate will be finely filtered and purified and reused in the production process. The recovery rate can reach more than 95%, which greatly reduces the waste of raw materials. The by-products and waste solvents are collected and sent to the treatment facility for harmless treatment to ensure that the production process meets environmental protection requirements.

[0037] Embodiment 2: A novel method for recycling waste organic solvents comprises the following steps:

[0038] S1: A mixture of 55% benzene, 15% tetrahydrofuran (THF), 12% tert-butyl acetate (TBA), 10% tert-butyl alcohol, 5% water and 3% ethanol in the waste liquid is fed into a distillation tower for separation, the feed rate of the waste liquid is 0.5 L / h, the tower bottom temperature is maintained at 140° C., the tower top temperature is controlled at 110° C., the operating pressure is 101.3 kPa at normal pressure, and the reflux ratio is set to 5. Through this process, benzene is collected as a heavy component at the bottom of the tower, while tetrahydrofuran (THF), tert-butyl acetate (TBA) and other light components evaporate to the top of the tower. The yield of benzene is about 65% of the benzene in the waste liquid, and the benzene can be used as an industrial-grade benzene product;

[0039] S2: The mixture of tetrahydrofuran (THF) and tert-butyl acetate (TBA) collected from the top of the distillation tower is mixed with pure water at a volume ratio of 1:0.7 to form a two-phase liquid. The mixed liquid is extracted through a separatory funnel, gently shaken and allowed to stand to separate the two phases. The aqueous phase and the organic phase are separated during the extraction process, wherein the upper layer contains a mixture of tetrahydrofuran and tert-butyl acetate, and the lower layer contains a mixture of tert-butyl alcohol and ethanol. The temperature of this separation process is maintained at room temperature (30° C.), and the extraction time is 20 minutes to ensure efficient stratification. Through this process, tetrahydrofuran and tert-butyl acetate are effectively separated, providing a pure organic solvent for subsequent treatment;

[0040] S3: The mixture of tetrahydrofuran (THF) and tert-butyl acetate (TBA) separated in S2 is sent to a vacuum distillation tower for further separation. The operating pressure of the vacuum distillation is set to 15kPa, the tower bottom temperature is controlled at 85°C, the tower top temperature is 75°C, and the reflux ratio is set to 4. This operating condition helps to reduce energy consumption and can effectively separate tetrahydrofuran and tert-butyl acetate. Tetrahydrofuran enters the top of the tower through evaporation and becomes the top product of the distillation tower, while tert-butyl acetate is collected as a heavy component at the bottom of the tower. Tetrahydrofuran and tert-butyl acetate can then be further purified by adsorption dehydration and other methods to obtain high-purity products;

[0041] S4: The mixture of tert-butanol and ethanol will be separated by distillation. First, the mixture entering this step is dried to remove the moisture therein. The dried mixture is sent to a distillation tower. The operating pressure is maintained at 101.3 kPa at normal pressure. The tower bottom temperature is set to 70°C, the tower top temperature is 65°C, and the reflux ratio is set to 3. After this distillation process, ethanol evaporates from the tower top as a light component, and finally high-purity ethanol is obtained. Tert-butanol is collected as the tower bottom product and further dried to obtain industrial-grade tert-butanol.

[0042] S5: In order to further remove moisture from the distillation product, in S5, each component is treated by an adsorption dehydration process. Tetrahydrofuran (THF) and tert-butyl acetate (TBA) are usually dehydrated using activated alumina as an adsorbent to ensure that the moisture content is controlled below 0.1%. Tert-butyl alcohol and ethanol are dehydrated using molecular sieves to ensure that the moisture content of the final product is extremely low. The adsorption process is carried out at room temperature and the adsorption time is usually 3 hours. Each product can eventually reach industrial-grade purity standards.

[0043] S6: The by-products and solvent vapors generated during the distillation process are recovered through the condensation recovery system. The condenser cools the vapor to room temperature and separates the solvent and by-products. The condensation temperature is usually set at 30°C. The recovered solvents such as benzene, tetrahydrofuran, tert-butyl acetate, etc. can be recycled after further filtration and purification to reduce the consumption of raw materials in the production process. The by-products are safely disposed of through appropriate treatment or used in other process flows when possible. Through this recovery process, the solvent recovery rate can usually reach more than 95%, which greatly reduces waste emissions and improves resource utilization efficiency.

[0044] Embodiment 3: A novel method for recycling waste organic solvents, comprising the following steps:

[0045] S1: A mixture of 60% benzene, 12% tetrahydrofuran (THF), 10% tert-butyl acetate (TBA), 8% tert-butyl alcohol, 5% water and 5% ethanol in the waste liquid is fed into a distillation tower for separation. The feed rate of the waste liquid is 0.6 L / h, the tower bottom temperature is maintained at 135° C., the tower top temperature is controlled at 105° C., the operating pressure is 101.3 kPa at normal pressure, and the reflux ratio is set to 6. Through this process, benzene is collected as a heavy component at the bottom of the tower, while tetrahydrofuran (THF), tert-butyl acetate (TBA) and other light components evaporate to the top of the tower. The yield of benzene is about 65% of the benzene in the waste liquid, and the benzene can be used as an industrial-grade benzene product;

[0046] S2: The mixture of tetrahydrofuran (THF) and tert-butyl acetate (TBA) collected from the top of the distillation tower is mixed with pure water at a volume ratio of 1:0.5 to form a two-phase liquid. The mixed liquid is extracted through a separatory funnel, gently shaken and allowed to stand to separate the two phases. The aqueous phase and the organic phase are separated during the extraction process, wherein the upper layer contains a mixture of tetrahydrofuran and tert-butyl acetate, and the lower layer contains a mixture of tert-butyl alcohol and ethanol. The temperature of this separation process is maintained at room temperature (30° C.), and the extraction time is 15 minutes to ensure efficient stratification. Through this process, tetrahydrofuran and tert-butyl acetate are effectively separated, providing a pure organic solvent for subsequent treatment;

[0047] S3: The mixture of tetrahydrofuran (THF) and tert-butyl acetate (TBA) separated in S2 is sent to a vacuum distillation tower for further separation. The operating pressure of the vacuum distillation is set to 20 kPa, the tower bottom temperature is controlled at 90 ° C, the tower top temperature is 80 ° C, and the reflux ratio is set to 5. This operating condition helps to reduce energy consumption and can effectively separate tetrahydrofuran and tert-butyl acetate. Tetrahydrofuran enters the top of the tower through evaporation and becomes the top product of the distillation tower, while tert-butyl acetate is collected as a heavy component at the bottom of the tower. Tetrahydrofuran and tert-butyl acetate can then be further purified by adsorption dehydration and other methods to obtain high-purity products;

[0048] S4: The mixture of tert-butanol and ethanol will be separated by distillation. First, the mixture entering this step is dried to remove the moisture therein. The dried mixture is sent to a distillation tower. The operating pressure is maintained at 101.3 kPa at normal pressure. The tower bottom temperature is set to 75°C, the tower top temperature is 70°C, and the reflux ratio is set to 2. After this distillation process, ethanol evaporates from the tower top as a light component, and finally high-purity ethanol is obtained. Tert-butanol is collected as a bottom product, and industrial-grade tert-butanol is further obtained by drying.

[0049] S5: In order to further remove the moisture in the distillation product, in S5, each component is treated by an adsorption dehydration process. Tetrahydrofuran (THF) and tert-butyl acetate (TBA) are usually dehydrated using activated alumina as an adsorbent to ensure that the moisture content is controlled below 0.05%. Tert-butyl alcohol and ethanol are dehydrated using molecular sieves to ensure that the moisture content of the final product is extremely low. The adsorption process is carried out at room temperature and the adsorption time is usually 4 hours. Each product can eventually reach the industrial grade purity standard;

[0050] S6: The by-products and solvent vapors generated during the distillation process are recovered through the condensation recovery system. The condenser cools the vapor to room temperature and separates the solvent and by-products. The condensation temperature is usually set at 25°C. The recovered solvents such as benzene, tetrahydrofuran, tert-butyl acetate, etc. can be recycled after further filtration and purification to reduce the consumption of raw materials in the production process. The by-products are safely disposed of through appropriate treatment or used in other process flows when possible. Through this recovery process, the solvent recovery rate can usually reach more than 95%, which greatly reduces waste emissions and improves resource utilization efficiency.

[0051] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A novel method for recovering and treating waste organic solvents, characterized in that: The following steps are involved: S1: sending the waste liquid containing 50% benzene, 15% tetrahydrofuran (THF), 12% tert-butyl acetate (TBA), 10% tert-butyl alcohol, 8% water and 5% ethanol into a fractionation tower for separation; S2: The mixture of tetrahydrofuran (THF) and tert-butyl acetate (TBA) collected from the top of the distillation tower is mixed with pure water in proportion to form a two-phase liquid, and extraction is performed through a separatory funnel; S3: The mixed solution of tetrahydrofuran (THF) and tert-butyl acetate (TBA) separated in S2 is sent to a vacuum distillation tower for further separation; S4: The mixture of tert-butyl alcohol and ethanol is separated by distillation. First, the mixture entering this step is dried to remove the water therein, and the dried mixture is sent to a distillation tower; S5: Treat each component through an adsorption dehydration process. Tetrahydrofuran (THF) and tert-butyl acetate (TBA) are usually dehydrated using activated alumina as an adsorbent to ensure that the moisture content is controlled below 0.05%; S6: The solvent vapor generated in the distillation tower and adsorption dehydration process will be condensed and recovered through the condenser. The condenser is set at 30°C. The recovered solvents such as benzene, tetrahydrofuran, tert-butyl acetate, etc. can be recycled after further filtration and purification.

2. The novel method for recycling waste organic solvent according to claim 1, characterized in that: In the S1, the feed rate of the waste liquid is 0.6L / h-1.0L / h, the tower bottom temperature is set to 135°C-140°C, the tower top temperature is 105°C-110°C, the operating pressure is normal pressure of 101.3kPa, and the reflux ratio is set to 4-6.

3. The novel method for recycling waste organic solvent according to claim 1, characterized in that: In S2, a mixture of tetrahydrofuran (THF) and tert-butyl acetate (TBA) is mixed with pure water in a volume ratio of 1:0.5-1:0.7, the temperature of the separation process is maintained at room temperature 30°C, and the extraction time is 15 minutes to 20 minutes.

4. The novel method for recycling waste organic solvent according to claim 1, characterized in that: In the S3, the operating pressure is set to 20 kPa-35 kPa, the tower bottom temperature is 90°C-95°C, the tower top temperature is 80°C-85°C, and the reflux ratio is set to 3-5.

5. The novel method for recycling waste organic solvent according to claim 1, characterized in that: In the S4, the operating pressure is maintained at 101.3 kPa at normal pressure, the tower bottom temperature is set to 65°C-75°C, the tower top temperature is set to 60°C-70°C, and the reflux ratio is set to 2-3.

6. The novel method for recycling waste organic solvent according to claim 1, characterized in that: In the S5, tetrahydrofuran (THF) and tert-butyl acetate (TBA) are usually dehydrated using activated alumina as an adsorbent to ensure that the moisture content is controlled below 0.1%-0.05%, and tert-butyl alcohol and ethanol are dehydrated using molecular sieves to ensure that the moisture content of the final product is extremely low. The adsorption process is carried out at room temperature and the adsorption time is usually 2-4 hours.

7. The novel method for recycling waste organic solvent according to claim 1, characterized in that: In S6, the condenser is set at a temperature of 25°C-30°C.