Low-temperature evaporation system

Abstract

The utility model discloses a low-temperature evaporation system which comprises a low-temperature evaporator, a spiral separator, a condenser, a vacuum pump and an evaporation water tank, the spiral separator is connected with a steam outlet of the low-temperature evaporator, and the spiral separator, the condenser, the vacuum pump and the evaporation water tank are sequentially connected. The utility model has the advantages of convenient operation, low operation cost, stable water outlet, low-temperature evaporation and difficult scale generation.

Description

Technical Field

[0001] The utility model relates to wastewater treatment equipment, in particular to a low-temperature evaporation system. Background Art

[0002] During the production of UV monomers, esterification water is produced in the esterification reaction process and contains a small amount of acrylic acid. At present, this part of the wastewater containing acrylic acid can only be treated as hazardous waste or by biochemical treatment in the industry, and the treatment cost exceeds 2000 yuan per ton.

[0003] Principle of esterification water generation:

[0004]

[0005] In addition, after the esterification reaction is completed, an aqueous sodium hydroxide solution is often added for neutralization. The main purpose is to neutralize the excessive acrylic acid and catalyst in the reaction, generating a large amount of waste alkali liquor. The main components of the esterification water are 95% water and 5% acrylic acid. The main components of the waste alkali liquor are mostly sodium acrylate and water, a small amount of sodium methylsulfonate, sodium hypophosphite, sodium hydroxide, etc., and the pH value is about 9-10. The solid content is about 15-18%. Usually, 1.3-2.5 tons of wastewater are produced simultaneously for each ton of acrylate monomer produced. This greatly restricts the development of the UV monomer industry and also generates a large amount of waste, causing resource waste and environmental pollution.

[0006] At present, the treatment of esterification wastewater mainly adopts triple-effect or double-effect evaporation. Although triple-effect or double-effect evaporation reduces energy consumption, at the same time, due to the high temperature, in the triple-effect system, sodium acrylate polymerization or scale formation is likely to occur during the cycle heating process, blocking the heater and evaporator and unable to achieve stable operation. Content of the Utility Model

[0007] The purpose of the utility model is to provide a low-temperature evaporation system.

[0008] Specifically, the low-temperature evaporation system includes a low-temperature evaporator, a spiral separator, a condenser, a vacuum pump and an evaporation water tank, wherein the spiral separator is connected to the steam outlet of the low-temperature evaporator, and the spiral separator, the condenser, the vacuum pump and the evaporation water tank are connected in sequence. The liquid in the low-temperature evaporator boils under negative pressure and low temperature, and the steam rises, and enters the spiral separator through the lower part of the spiral separator. Due to the large amount of steam, some small water droplets and impurities are entrained. According to the principle of centrifugal sedimentation and density difference, the rising steam entrains some small water droplets and enters the device from the air inlet of the filter tangentially, forming a spiral structure of airflow spiraling up. Due to the different density of steam and water, under the joint action of centrifugal force (the flow rate of the rotating airflow is not less than 800kg / h) and centripetal force, the water droplets and impurities with high density fall from the bottom and return to the low-temperature evaporator; the steam and impurities with low density continue to rise, and the clean secondary steam enters the condenser.

[0009] The low-temperature evaporator is a horizontal evaporator, including an evaporating kettle, a steam jacket is provided on the outer wall of the kettle, a discharge port is provided at one end of the kettle, a motor is provided at the other end, and a scraper device for stirring materials and pushing slag to the discharge port is provided inside the kettle. The motor is connected to the scraper device to drive it to work.

[0010] The scraper device is a spiral scraper device, which comprises a stirring shaft connected to the motor. The spiral scraper structure is arranged on the stirring shaft and extends along the length direction of the stirring shaft.

[0011] The scraper device is provided with at least one crushing tooth structure, and the crushing teeth of the crushing tooth structure are in contact with the inner wall of the evaporating kettle.

[0012] The scraper device is provided with more than two water-breaking tooth structures, which are arranged symmetrically at the center of the peripheral surface of the stirring shaft with the central axis of the stirring shaft as the symmetry axis. Each water-breaking tooth structure is fixed to the stirring shaft by a plurality of legs fixed to the stirring shaft and arranged along the axial direction. When working, the water-breaking tooth structure breaks the stubborn materials adhering to the kettle wall and cleans the debris by adhering to the wall.

[0013] The discharge port of the evaporator is provided with a discharge cylinder for automatic slag discharge.

[0014] The inner wall of the evaporator is coated with an anti-sticking material to prevent the concentrated liquid from sticking to the wall.

[0015] The spiral separator is provided with a multi-layer filter element. Steam enters the multi-layer hydrophobic filter element, and impurities with a particle size greater than 1 mm are intercepted.

[0016] The multi-layer filter element is formed by stacking and staggered installation of a plurality of PP filter cottons, and the stacking and staggered installation increases the contact area while avoiding gas segmentation, thereby achieving defoaming and separation.

[0017] Beneficial effects of the utility model:

[0018] 1. The utility model is convenient to operate and run, has low operation cost, and stable water outlet.

[0019] 2. The utility model can perform low-temperature evaporation. The low-temperature concentrator can realize low-temperature evaporation, avoiding the problems of polymerization and scale formation. Even if a small amount of micro-polymers precipitate, it is not easy to form scale and will not affect the operation of the screw evaporation agitator.

[0020] 3. The utility model is provided with a spiral separator, which can remove more than 95% of free organic matter and free water. The heavy metals in the water outlet are zero, and the COD content in the water outlet is within 1000 mg / L, which is 70% higher than that of the traditional low-temperature evaporator before iteration. The water quality of the water outlet is better and more transparent.

[0021] 4. The low-temperature evaporator of the utility model is provided with a spiral scraper device. The spiral scraper stirs the liquid during evaporation, making the raw liquid evenly heated and the components in the raw liquid uniform, which is beneficial to the evaporation process. After the water evaporation is completed, the materials remaining in the kettle are pushed to the discharge port for discharging. The three-row crushing teeth structure on the stirring shaft crushes the stubborn materials adhering to the kettle wall, sweeps the debris adhering to the wall, and is pushed to the discharge port by the scraper shaft with a spiral structure, enabling deep crystallization and discharging dry solid materials.

[0022] 5. The utility model is used for treating high-concentration mother liquor for low-temperature vacuum crystallization and drying, and is internally provided with a spiral scraper device and an anti-sticking coating, which has a particularly good effect on treating concentrated liquid that is easy to stick to the wall. It is particularly recommended for treating sticky or crystallized fluids, such as high-concentration oily wastewater, pharmaceutical industry wastewater, coal chemical industry wastewater, heavy metal wastewater, printing industry wastewater, high-salt water, brackish water, reverse osmosis concentrate, etc. Description of the Drawings

[0023] Figure 1 It is a schematic structural diagram of the low-temperature evaporation system of the embodiment of the utility model.

[0024] Figure 2 It is a perspective view of the spiral scraper device of the embodiment of the utility model. Detailed Embodiments

[0025] The following further elaborates on the utility model through the following specific embodiments, but the content of the utility model is not limited thereto at all.

[0026] Figure 1-2 The shown low-temperature evaporation system is an embodiment of the utility model. As Figure 1 shown, the low-temperature evaporation system includes a low-temperature evaporator 1, a spiral separator 9, a condenser 6, a vacuum pump 7, and an evaporation water tank 8. The spiral separator 9 is connected to the steam outlet of the low-temperature evaporator 1, and the spiral separator 9, the condenser 6, the vacuum pump 7, and the evaporation water tank 8 are connected in sequence.

[0027] The low-temperature evaporator 1 is a horizontal evaporator, including an evaporation kettle, a steam jacket 3 is provided on the outer wall of the kettle, a discharge port 2 is provided at one end of the kettle, a motor 5 is provided at the other end, and a scraper device 4 is provided in the kettle for stirring materials and pushing the slag to the discharge port 2. The motor 5 is connected to the scraper device 4 to drive it to work.

[0028] like Figure 2 As shown, the scraper device 4 is a spiral scraper device, including a stirring shaft 42 connected to a motor 5, and a spiral scraper 41 is arranged on the stirring shaft 42 and extends along the length direction of the stirring shaft 42. The scraper device 4 is provided with three crushing tooth structures 44. The crushing teeth of the crushing tooth structure 44 are in contact with the inner wall of the evaporator. The three crushing tooth structures 44 are arranged symmetrically on the circumference of the stirring shaft 42 with the central axis of the stirring shaft 42 as the symmetry axis. Each crushing tooth structure 44 is fixed to the stirring shaft 42 by a number of legs 43 fixed to the stirring shaft 42 and arranged along the axial direction. When working, the crushing tooth structure 44 crushes the stubborn materials adhering to the wall of the kettle and cleans the debris with the wall. When working, the motor 5 drives the stirring shaft to rotate, driving the spiral scraper 41 and the three rows of crushing tooth structures 44 to rotate. The spiral scraper 41 stirs the liquid during evaporation, so that the original liquid is heated evenly and the components in the original liquid are uniform, which is conducive to evaporation; after the water evaporation is completed, the residual materials in the kettle are pushed to the discharge port 2 for discharge. The three rows of crushing teeth 44 on the stirring shaft 41 crush the stubborn materials adhering to the kettle wall, clean the debris with the wall, and push it to the discharge port 2 with the spiral scraper shaft. Mixing, crushing and slag discharge are completed automatically without manual intervention.

[0029] The discharge port 2 of the evaporator is provided with a discharge cylinder for automatic slag discharge.

[0030] The inner wall of the evaporator is coated with anti-stick material to prevent the concentrate from sticking to the wall.

[0031] A multi-layer filter element is arranged in the spiral separator 9. Steam enters the multi-layer hydrophobic filter element, and impurities with a particle size greater than 1 mm are intercepted.

[0032] The multi-layer filter element is formed by stacking and staggered installation of a plurality of PP filter cottons, and the stacking and staggered installation increases the contact area while avoiding gas segmentation, thereby achieving defoaming and separation.

[0033] In this embodiment, the liquid in the low-temperature evaporator 1 boils under negative pressure and at a relatively low temperature, generating steam that rises and enters the spiral separator 9 through the lower part of the spiral separator 9. Since the amount of steam is large, it will entrain some small water droplets and impurities. According to the principles of centrifugal sedimentation and density difference, the rising steam with some entrained small water droplets tangentially enters from the air inlet of the spiral separator 9, forming a spiral airflow that spirals upward. Due to the different densities of steam and water, under the combined action of centrifugal force (the flow rate of the rotating airflow is not less than 800 kg / h), centripetal force, etc., the water droplets and impurities with a large density descend and return to the low-temperature evaporator 1 from the bottom; the steam and impurities with a low density continue to rise, and the clean secondary steam enters the condenser 6. The condensed water is then input into the evaporation water tank 8 through the vacuum pump 7.

[0034] The esterification water is taken for low-temperature evaporation treatment, and the water quality is shown in Table 1. The main components are sodium acrylate (salt), sodium methyl sulfonate (salt), and acrylate 1-2% (boiling point above 300 °C), and 80% is water. Sodium acrylate and acrylate are thermosensitive substances and are prone to polymerization.

[0035] Table 1 Water quality table of organic base water

[0036]

[0037]

[0038] The waste alkali liquid generated from the production of UV monomers is mixed with the esterification water and adjusted to a solution pH of 7-8. Then it is sent to the low-temperature evaporation system for low-temperature evaporation and concentration to a concentrated solution with a solid content of 40-45%, and the discharged steam is condensed and recovered. After the acrylic acid wastewater is concentrated into a concentrated solution with a solid content of 40-45%, it can be used as a raw material for the production of sodium polyacrylate, and no longer be treated as hazardous waste. The sodium polyacrylate produced downstream can be used as a sewage treatment flocculant. Thus, waste is turned into treasure.

[0039] Table 2 Low-temperature evaporation and concentration conditions of steam

[0040]

[0041] Table 3 Effluent requirements

[0042] Serial number Item Data Unit 1 Chemical Oxygen Demand (COD) 1000 mg / L 2 Concentration ratio 50 ％ 3 pH 6-8 Dimensionless

Claims

1. A low-temperature evaporation system, characterized in that, It comprises a low-temperature evaporator, a spiral separator, a condenser, a vacuum pump and an evaporation water tank. The spiral separator is connected to the steam outlet of the low-temperature evaporator, and the spiral separator, condenser, vacuum pump and evaporation water tank are connected in sequence.

2. The low-temperature evaporation system according to claim 1, wherein The low-temperature evaporator is a horizontal evaporator, including an evaporating kettle, a steam jacket is provided on the outer wall of the kettle, a discharge port is provided at one end of the kettle, a motor is provided at the other end, and a scraper device for stirring materials and pushing slag to the discharge port is provided inside the kettle. The motor is connected to the scraper device to drive it to work.

3. The low-temperature evaporation system according to claim 2, characterized in that, The scraper device is a spiral scraper device, which comprises a stirring shaft connected to the motor. The spiral scraper structure is arranged on the stirring shaft and extends along the length direction of the stirring shaft.

4. The low-temperature evaporation system according to claim 2 or 3, characterized in that, The scraper device is provided with at least one crushing tooth structure, and the crushing teeth of the crushing tooth structure are in contact with the inner wall of the evaporating kettle.

5. The low-temperature evaporation system according to claim 3, characterized in that, The scraper device is provided with more than two rows of water-breaking teeth, which are symmetrically arranged around the center of the circumference of the stirring shaft with the central axis of the stirring shaft as the axis of symmetry.

6. The low-temperature evaporation system according to claim 2, characterized in that The discharging port is provided with a discharging cylinder.

7. The low-temperature evaporation system according to claim 2, characterized in that, The inner wall of the evaporating kettle is coated with an anti-sticking material.

8. The low-temperature evaporation system according to claim 1, characterized in that, A multi-layer filter element is arranged in the spiral separator.

9. The low-temperature evaporation system according to claim 8, characterized in that, The multi-layer filter element is formed by stacking and interlacing a plurality of PP filter cottons.

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