Ethyl acetate recovery device in adhesive production process

Abstract

The utility model discloses a device for recovering ethyl acetate in an adhesive production process, which comprises a dehydrating tower, a drying tower, a gas-liquid separation tower, a gas-liquid separation tower, a gas-liquid separation tower and a gas-liquid separation tower, the layering device is connected with the top of the dehydrating tower and is used for layering condensate of tower top components of the dehydrating tower; the deacidification tower is connected with a discharge hole in the bottom of the layering device and is used for removing the layered oil phase component and acetic acid in the oil phase feed liquid; the membrane component is connected with the top of the deacidification tower and is used for carrying out dehydration treatment; and the refining tower is connected with the top of the membrane component and is used for removing an ethanol light component in the feed liquid to obtain an ethyl acetate product. According to the device disclosed by the utility model, the layering pretreatment is combined with the multi-stage rectification, membrane separation and energy collaborative optimization technology, so that efficient recovery of ethyl acetate and green collaboration of waste liquid treatment are realized; the whole process adopts a multi-stage energy recovery design, so that the steam consumption and energy consumption cost are remarkably reduced, and meanwhile, the organic waste liquid discharge is reduced.

Description

Technical Field

[0001] This utility model belongs to the field of chemical technology, specifically relating to an ethyl acetate recovery device in the adhesive production process. Background Technology

[0002] In the production of adhesives, ethyl acetate is widely used as a highly efficient solvent in the preparation of various adhesives, including polyurethane adhesives, acrylate adhesives, rubber-based adhesives, and some epoxy resin-modified adhesives. For example, in the preparation of polyurethane adhesives, ethyl acetate is often added to adjust the viscosity and dispersibility of the system; in the preparation of acrylate adhesives, ethyl acetate is often added as a solvent to promote the homogeneous reaction of monomers; and rubber-based adhesives rely on ethyl acetate to dissolve rubber particles to form a homogeneous adhesive solution. However, ethyl acetate not recovered during the production process is emitted as volatile organic compounds (VOCs), causing environmental pollution, wasting raw materials, increasing production costs, and posing flammable and explosive safety hazards.

[0003] Currently, industrial recovery of ethyl acetate mainly relies on distillation, adsorption, and condensation methods. Distillation separates ethyl acetate from a mixture through heating, but it is energy-intensive, and if the system contains azeotropes (such as water or alcohols), a third component must be introduced to break the azeotropic reaction, resulting in a complex process and low efficiency. Adsorption uses activated carbon or molecular sieves to adsorb ethyl acetate from waste gas, but the adsorbent is easily saturated, requiring frequent regeneration or replacement, leading to high operating costs and difficulty in handling high-flow-rate waste gas. Condensation recovers gaseous ethyl acetate through low-temperature condensation, but the recovery rate drops sharply at low concentrations or high temperatures, and the equipment is prone to frost and blockage. These methods generally suffer from high energy consumption, low efficiency, poor adaptability, and high maintenance costs, and are particularly difficult to adapt to the composition of waste liquids containing multiple solvents in adhesive production. Therefore, there is an urgent need to develop an efficient, economical, and adaptable ethyl acetate recovery device and method to achieve resource recycling and meet environmental protection and safe production requirements. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a device for recovering ethyl acetate during the adhesive production process. By combining layered pretreatment with multi-stage distillation, membrane separation, and energy synergistic optimization technologies, it achieves efficient recovery of ethyl acetate and green synergistic treatment of waste liquid.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for recovering ethyl acetate during adhesive production includes the following steps:

[0007] S1. The waste liquid containing ethyl acetate is subjected to layer pretreatment to obtain an aqueous phase liquid and an oil phase liquid;

[0008] S2. The aqueous feed liquid is dehydrated by continuous atmospheric distillation.

[0009] S3. After cooling, the dehydrated components are separated into layers. The aqueous phase is used as reflux liquid, and the oil phase and oil liquid are treated by continuous atmospheric distillation to remove acetic acid.

[0010] S4. After deacidification, the solution is vaporized and then separated by a membrane module for dehydration.

[0011] S5. The dehydrated organic gas phase is subjected to continuous atmospheric distillation to remove the light ethanol component, yielding ethyl acetate product.

[0012] Preferably, in step S1, the ethyl acetate-containing liquid is an adhesive produced during the production process of one of the following: polyurethane adhesive, acrylate adhesive, and rubber-based adhesive.

[0013] Preferably, in step S2, the dehydration tower has 30-35 trays, a reflux ratio of 3-5, and a top temperature of 70-75°C; in step S3, the deacidification tower for removing acetic acid has 20-25 trays, a reflux ratio of 2-3, and a top temperature of 70-80°C.

[0014] Preferably, in step S4, the operating pressure of the membrane module is 0.8~1.0 MPa, and the water content of the organic phase after dehydration is <0.1%; in step S5, the number of trays of the purification column for removing ethanol is 25~30, the reflux ratio is 4~5, and the top temperature of the column is 75~78℃.

[0015] An ethyl acetate recovery device for adhesive production process, comprising:

[0016] A dehydration tower is used to dehydrate aqueous liquid feed.

[0017] A separator, connected to the top of the dehydration tower, is used to separate the condensate from the top components of the dehydration tower into layers.

[0018] The deacidification tower, connected to the bottom outlet of the separator, is used to remove acetic acid from the oil phase components and the oil phase feed liquid after separation.

[0019] Membrane module, connected to the top of the deacidification tower, is used for dehydration treatment;

[0020] The purification column, connected to the top of the membrane module, is used to remove the light ethanol component from the feed solution to obtain the ethyl acetate product.

[0021] Preferably, it also includes an aqueous phase feed pipeline connected to the feed inlet of the dehydration tower for conveying the aqueous phase feed to the dehydration tower.

[0022] Preferably, it also includes a preheater connected between the aqueous phase feed pipeline and the dehydration tower for preheating the aqueous phase feed.

[0023] Preferably, it also includes an oil phase feed pipeline connected to the feed inlet of the deacidification tower for conveying the oil phase feed to the deacidification tower.

[0024] Preferably, it also includes an evaporator connected between the deacidification tower and the membrane module for vaporizing the solution at the top of the deacidification tower.

[0025] Preferably, it also includes a membrane module condenser connected to the bottom of the membrane module for condensing the water that has permeated through the membrane into regenerated water, which is then returned to the dehydration tower for further dehydration.

[0026] Preferably, it further includes an acetic acid treatment unit connected to the bottom of the deacidification tower for recovering acetic acid; the acetic acid treatment unit includes:

[0027] A cooler, connected to the bottom outlet of the deacidification tower, is used to cool the waste liquid at the bottom of the deacidification tower;

[0028] The neutralization reactor, connected to the outlet of the cooler, is used to neutralize the waste liquid and alkaline solution at the bottom of the deacidification tower to produce an acetate solution.

[0029] An evaporator, connected to the outlet of the neutralization reactor, is used for vacuum evaporation and concentration of acetate solutions.

[0030] The crystallization kettle, connected to the concentrated liquid outlet of the evaporator, is used to cool the concentrated liquid and precipitate acetate crystals;

[0031] A centrifuge, connected to the bottom of a crystallization vessel, is used to separate acetate crystals from the mother liquor to obtain a solid acetate product.

[0032] Preferably, the centrifuge is connected to the neutralization reactor via a reflux pipeline to send the mother liquor separated by centrifugation to the neutralization reactor, so as to realize the recycling of the mother liquor.

[0033] The advantages of this utility model are:

[0034] (1) This utility model achieves efficient recovery of ethyl acetate and green synergy of waste liquid treatment by combining layered pretreatment with multi-stage distillation, membrane separation and energy synergy optimization technology; the whole process significantly reduces steam consumption and energy cost through multi-stage energy recovery design, while reducing organic waste liquid discharge. The overall process has the technical advantages of high resource recovery efficiency, strong environmental friendliness and low energy consumption, providing an economical and feasible solution for the recycling of organic solvents in adhesive production.

[0035] (2) The process of this utility model separates the waste liquid into an aqueous phase and an oil phase through layered pretreatment. The aqueous phase is dehydrated first to efficiently remove a large amount of water and low-boiling-point azeotropes, thereby avoiding the problem of increased energy consumption caused by the interference of the aqueous phase in the dehydration stage of high-concentration organic matter in the oil phase. At the same time, it reduces the material handling load of the subsequent deacidification tower. The light organic components separated in the aqueous phase pretreatment stage work synergistically with the azeotropic effect of the subsequent deacidification tower to make acetic acid directionally enriched in the waste liquid at the bottom of the tower, reducing the interference with the purity of the product.

[0036] (3) The membrane dehydration process of this utility model deeply dehydrates the light component organic phase, breaks through the limitation of water residue in traditional distillation, and achieves the dual effect of recycling reclaimed water and purifying organic phase.

[0037] (4) The present invention sets up an acetic acid treatment unit at the bottom of the deacidification tower to convert the high-concentration acetic acid waste liquid discharged from the bottom of the deacidification tower into acetic acid crystals, thereby realizing resource utilization and reducing the difficulty of treating acidic waste liquid and environmental pollution. Attached Figure Description

[0038] Figure 1 This is a process flow diagram of this utility model.

[0039] The meanings of the labels in the attached diagram are as follows: 1. Dehydration tower, 2. Separator, 3. Deacidification tower, 4. Membrane module, 5. Refining tower, 6. Preheater, 7. Aqueous phase feed line, 8. Oil phase feed line, 9. Evaporator, 10. Membrane module condenser, 11. Cooler, 12. Neutralization reactor, 13. Evaporator concentrator, 14. Crystallizer, 15. Centrifuge, 16. Reflux line. Detailed Implementation

[0040] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0041] See Figure 1 This utility model discloses an ethyl acetate recovery device in the production process of adhesives, comprising: a dehydration tower 1 for dehydrating the aqueous phase feed liquid; a separator 2 connected to the top of the dehydration tower 1 for separating the condensate from the top component of the dehydration tower 1; a deacidification tower 3 connected to the bottom outlet of the separator 2 for removing the oil phase component and acetic acid from the oil phase feed liquid after separation; a membrane module 4 connected to the top of the deacidification tower 3 for dehydration treatment; and a purification tower 5 connected to the top of the membrane module 4 for removing the light ethanol component from the feed liquid to obtain the ethyl acetate product.

[0042] It also includes an aqueous feed line 7, connected to the inlet of dehydration tower 1, for conveying the aqueous feed to dehydration tower 1. It also includes a preheater 6, connected between the aqueous feed line 7 and dehydration tower 1, for preheating the aqueous feed. It also includes an oil feed line 8, connected to the inlet of deacidification tower 3, for conveying the oil feed to deacidification tower 3. It also includes an evaporator 9, connected between deacidification tower 3 and membrane module 4, for vaporizing the solution at the top of deacidification tower 3. Finally, it includes a membrane module condenser 10, connected to the bottom of membrane module 4, for condensing the water that has permeated through the membrane into regenerated water, which is then returned to dehydration tower 1 for further dehydration.

[0043] The system also includes an acetic acid treatment unit connected to the bottom of the deacidification tower 3 for recovering acetic acid. The acetic acid treatment unit includes: a cooler 11 connected to the outlet of the bottom of the deacidification tower 3 for cooling the waste liquid at the bottom of the tower; a neutralization reactor 12 connected to the outlet of the cooler 11 for neutralizing the waste liquid and alkali solution at the bottom of the deacidification tower 3 to generate an acetate solution; an evaporator 13 connected to the outlet of the neutralization reactor 12 for vacuum evaporation and concentration of the acetate solution; a crystallization kettle 14 connected to the outlet of the evaporator 13 for cooling the concentrate and precipitating acetate crystals; and a centrifuge 15 connected to the bottom of the crystallization kettle 14 for separating acetate crystals from the mother liquor to obtain a solid acetate product. The centrifuge 15 is connected to the neutralization reactor 12 via a reflux pipe 16 to send the centrifuged mother liquor back to the neutralization reactor 12 for mother liquor recycling.

[0044] A method for recovering ethyl acetate during adhesive production includes the following steps:

[0045] S1. The waste liquid containing ethyl acetate is subjected to layer pretreatment to obtain an aqueous phase liquid and an oil phase liquid;

[0046] S2. The aqueous feed liquid is fed into dehydration tower 1, which employs an azeotropic distillation process and continuous atmospheric pressure distillation to dehydrate the aqueous feed liquid. After heat exchange with the hot material at the bottom of dehydration tower 1 in preheater 6, the aqueous feed liquid is continuously pumped into dehydration tower 1. Ethyl acetate, ethanol, and water azeotropically to the top of the tower as a ternary azeotrope, where they are enriched as light components and enter the condenser in vapor form for condensation and cooling. The condensate overflows into separator 2. The condensate separates into layers in separator 2. The aqueous component is returned to dehydration tower 1 as reflux liquid; the oil component is discharged from the system and sent to deacidification tower 3. After organic matter removal, the water passes through preheater 6 and cooler sequentially from the bottom of the tower and is discharged from the system as wastewater.

[0047] S3. The separated oil phase components and oil phase feed liquid are continuously pumped into deacidification tower 3 for continuous deacidification. Deacidification tower 3 adopts a distillation process and continuous atmospheric pressure distillation operation to remove residual acetic acid from the feed liquid. Ethyl acetate and ethanol-water are enriched as light components at the top of the tower. Part of the condensate is returned to deacidification tower 3 as reflux liquid, and the remainder is sent to the subsequent evaporator 9.

[0048] High-boiling-point organic compounds such as acetic acid are cooled by cooler 11 at the bottom of the tower and then continuously added to neutralization reactor 12 with sodium hydroxide (NaOH) solution in stoichiometric ratio to produce sodium acetate aqueous solution. The solution is then sent to evaporator 13 to evaporate the sodium acetate solution under reduced pressure to remove water and concentrate it to a supersaturated state. The solution is then sent to crystallizer 14 to cool the concentrate to room temperature, precipitating sodium acetate crystals. After centrifugation, solid sodium acetate product is obtained. The mother liquor after separation is returned to neutralization reactor 12 for reuse, reducing raw material waste.

[0049] S4. The ethyl acetate solution from the top of the column is pressurized and vaporized in the evaporator 9 and then enters the membrane module 4 for vaporization membrane dehydration. Water permeates through the membrane and condenses into regenerated water, which is returned to the dehydration tower 1 for further dehydration. The dehydrated organic phase is sent to the purification tower 5 in gaseous form for one step of impurity removal.

[0050] S5. The dehydrated organic gas phase is fed into purification column 5. Purification column 5 adopts a continuous distillation process, operates at atmospheric pressure, and removes residual ethanol and other light components from the feed liquid. The organic gas phase from membrane module 4 exchanges heat with the feed liquid at the bottom of purification column 5 to cool it down before being continuously fed into purification column 5 for continuous removal of light components. Ethanol, water, and a small amount of ethyl acetate are enriched as light components at the top of the column. Part of the condensate is refluxed back to purification column 5, and part is discharged as waste liquid from the system. The high-concentration ethyl acetate product is discharged from the system at the bottom of the column.

[0051] Example 1: A method for recovering ethyl acetate during adhesive production, comprising the following steps:

[0052] After the ethyl acetate-containing waste liquid is allowed to settle and separate into layers, the aqueous phase feed liquid (90 wt% water, 9 wt% ethanol, 0.5 wt% ethyl acetate, and 0.5 wt% acetic acid) exchanges heat with the hot material at the bottom of the dehydration tower 1 through the preheater 6, and then enters the dehydration tower 1 with 30 trays for azeotropic distillation. At the top temperature of 75℃ (composition of ternary azeotrope), the light components (75% ethyl acetate, 22% ethanol, 2% water, and 1% acetic acid) are condensed at a reflux ratio of 3 and enter the separator 2, while the oil phase components are discharged to the deacidification tower 3. The wastewater at the bottom of the tower is cooled to a water content >99.5% and then discharged from the system. The oil phase feed (water 2% wt, ethanol 97.5% wt, ethyl acetate 0.25% wt, acetic acid 0.25% wt) is mixed with the dehydrated oil phase components from the aqueous phase and fed into a deacidification tower 3 with 20 trays. At a top temperature of 77°C and a reflux ratio of 2, a light component (ethyl acetate 82%, ethanol 16%, water 2%) is separated. The bottom waste liquid contains >98% acetic acid and is sent to the acetic acid treatment unit for neutralization and crystallization to obtain solid acetate product. The light component is dehydrated by membrane module 4 at a pressure of 0.8 MPa, and the water content of the organic phase is <0.1%. The organic phase enters the purification tower 5, where residual ethanol and light impurities are removed at a top temperature of 78°C and a reflux ratio of 4. Finally, an ethyl acetate product with a purity >99.8%, a water content <0.05%, and a yield of 98% is obtained at the bottom of the tower.

[0053] Example 2: This example uses the same method for recovering ethyl acetate during the adhesive production process as in Example 1, including the following steps:

[0054] After the ethyl acetate-containing waste liquid is allowed to settle and separate into layers, the aqueous phase feed liquid (90 wt% water, 9 wt% ethanol, 0.5 wt% ethyl acetate, and 0.5 wt% acetic acid) exchanges heat with the hot material at the bottom of the dehydration tower 1 via preheater 6, and then enters the dehydration tower 1 with 35 trays for azeotropic distillation. At a top temperature of 73℃ (composition of ternary azeotrope), the light components (78% ethyl acetate, 20% ethanol, 1.5% water, and 0.5% acetic acid) are condensed at a reflux ratio of 4 and enter the separator 2. The oil phase components are discharged to the deacidification tower 3. The wastewater at the bottom of the tower is cooled to a water content >99.6% and is discharged from the system. The oil phase feed (1.5 wt% water, 97.8 wt% ethanol, 0.3 wt% ethyl acetate, and 0.4 wt% acetic acid) is mixed with the dehydrated oil phase components and fed into a 25-plate deacidification tower 3. At a top temperature of 76°C and a reflux ratio of 2.5, a light component (85% ethyl acetate, 13.5% ethanol, and 1.5% water) is separated. The bottom waste liquid contains >98.5% acetic acid and is sent to the acetic acid treatment unit for neutralization and crystallization to obtain solid acetate product. The light component is dehydrated by membrane module 4 at a pressure of 1.0 MPa, resulting in an organic phase water content of <0.05%. The organic phase then enters purification tower 5, where residual ethanol and light impurities are removed at a top temperature of 75°C and a reflux ratio of 5. Finally, an ethyl acetate product with a purity >99.85%, a water content <0.03%, and a yield of 98.5% is obtained at the bottom of the tower.

[0055] Comparative example: Direct treatment of waste liquid using a single distillation column, including the following steps:

[0056] The waste liquid (45 wt% water, 48 wt% ethanol, 5 wt% ethyl acetate, and 2 wt% acetic acid) enters a distillation column with 40 trays and a reflux ratio of 5. Crude ethyl acetate (88% purity, 3% water, 7% ethanol, and 2% acetic acid) is collected at the top of the column at 80°C, and waste liquid containing 75% acetic acid, 20% water, and 5% other organic matter is discharged at the bottom of the column at 115°C. Due to the azeotropic effect and impurity interference, the ethyl acetate product yield is 70%, and steam consumption is 60% higher than in Example 1. The equipment lifespan is shortened by 40% due to high-temperature acid corrosion.

[0057] Compared to the conventional distillation method in comparison, Example 1 of this patent uses a synergistic process of layered pretreatment-stepwise distillation-membrane dehydration to increase the purity of ethyl acetate from 88% to 99.8%, the yield from 70% to 98%, reduce steam consumption by 60%, and reduce the residual organic matter in wastewater from 5% to below 0.5%, while extending equipment life by 40%. This significantly solves the defects of traditional processes, such as low separation efficiency, high energy consumption, and easy corrosion of equipment.

[0058] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the present invention in any way, and all technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A device for recovering ethyl acetate during the production of adhesives, characterized in that, include: A dehydration tower is used to dehydrate aqueous liquid feed. A separator, connected to the top of the dehydration tower, is used to separate the condensate from the top components of the dehydration tower into layers. The deacidification tower, connected to the separator, has a bottom outlet for removing acetic acid from the oil phase components and the oil phase liquid after separation. Membrane module, connected to the top of the deacidification tower, is used for dehydration treatment; The purification column, connected to the top of the membrane module, is used to remove the light ethanol component from the feed solution to obtain the ethyl acetate product.

2. The ethyl acetate recovery device in the adhesive production process according to claim 1, characterized in that, It also includes an aqueous feed pipeline, which connects to the feed inlet of the dehydration tower and is used to transport the aqueous feed to the dehydration tower.

3. The ethyl acetate recovery device in the adhesive production process according to claim 2, characterized in that, It also includes a preheater, which is connected between the aqueous feed liquid pipeline and the dehydration tower, and is used to preheat the aqueous feed liquid.

4. The ethyl acetate recovery device in the adhesive production process according to claim 1, characterized in that, It also includes an oil phase feed pipeline, which connects to the feed inlet of the deacidification tower and is used to transport the oil phase feed to the deacidification tower.

5. The ethyl acetate recovery device in the adhesive production process according to claim 1, characterized in that, It also includes an evaporator, connected between the deacidification tower and the membrane module, for vaporizing the solution at the top of the deacidification tower.

6. The ethyl acetate recovery device in the adhesive production process according to claim 1, characterized in that, It also includes a membrane module condenser, connected to the bottom of the membrane module, used to condense the water that has permeated through the membrane into regenerated water, which is then returned to the dehydration tower for further dehydration.

7. The ethyl acetate recovery device in the adhesive production process according to claim 1, characterized in that, It also includes an acetic acid treatment unit, connected to the bottom of the deacidification tower, for recovering acetic acid; the acetic acid treatment unit includes: A cooler, connected to the bottom outlet of the deacidification tower, is used to cool the waste liquid at the bottom of the deacidification tower; The neutralization reactor, connected to the outlet of the cooler, is used to neutralize the waste liquid and alkaline solution at the bottom of the deacidification tower to produce an acetate solution. An evaporator, connected to the outlet of the neutralization reactor, is used for vacuum evaporation and concentration of acetate solutions. The crystallization kettle, connected to the concentrated liquid outlet of the evaporator, is used to cool the concentrated liquid and precipitate acetate crystals; A centrifuge, connected to the bottom of a crystallization vessel, is used to separate acetate crystals from the mother liquor to obtain a solid acetate product.

8. The ethyl acetate recovery device in the adhesive production process according to claim 7, characterized in that, The centrifuge is connected to the neutralization reactor via a reflux line to send the mother liquor separated by centrifugation to the neutralization reactor, so as to realize the recycling of the mother liquor.

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