A continuous separation method for precipitating oligomers from ammonium sulfate polymer waste liquid in an acrylonitrile ammonium sulfate device

Abstract

A method for continuously separating oligomers precipitated from ammonium sulfate polymer waste liquid of an acrylonitrile ammonium sulfate unit relates to a method for separating oligomers precipitated from ammonium sulfate polymer waste liquid of an acrylonitrile ammonium sulfate unit. The present invention aims to solve the technical problem of the impact of the ammonium sulfate polymer waste liquid of the current acrylonitrile ammonium sulfate unit on the long-term stable operation of the incinerator. The process of the method of the present invention includes two processing units: a dilution-cooling unit and an adsorption filtration-filter material regeneration and reuse unit. The method of the present invention solves the problem of separating heavy components from the ammonium sulfate polymer waste liquid of an acrylonitrile ammonium sulfate unit, and has the advantages of fast separation speed, high separation efficiency, good separation effect, simple filter material regeneration, low operating cost and continuous operation. It provides strong support for improving the ammonium sulfate production capacity of the original ammonium sulfate unit and resource utilization of heavy components. It can also provide a useful reference for the resource recovery of ammonium sulfate and heavy components in the bottom liquid of the lower section of the acrylonitrile quenching tower and the bottom liquid of the first section of the tower.

Description

Technical Field

[0001] The invention relates to a method for separating oligomers precipitated from ammonium sulfate polymer waste liquid of an acrylonitrile ammonium sulfate device. Background Art

[0002] Acrylonitrile is an important organic synthetic raw material and a fundamental raw material for the production of three major synthetic materials: plastics, synthetic rubber, and synthetic fibers. my country is the world's largest producer and user of acrylonitrile, having led the world in production for many years. Production capacity has increased significantly annually, reaching 3.8 million tons / year in 2022 and projected to exceed 5 million tons / year in the future. Currently, over 95% of acrylonitrile producers worldwide use BP's propylene ammoxidation process (known as the Sohio process, 1960), which produces acrylonitrile from propylene, ammonia, and air. All established acrylonitrile plants in my country employ this production method.

[0003] The production of acrylonitrile by the propylene ammoxidation method generates a large amount of quench tower bottoms wastewater. There are two types of acrylonitrile quench towers: two-stage quench towers and single-stage quench towers, each producing corresponding bottoms wastewater (or waste liquid). A two-stage quench tower consists of an upper and lower tower connected together, and the bottoms produced are referred to as upper and lower bottoms respectively. A single-stage quench tower has only one section, and the bottoms produced are referred to as single-stage bottoms.

[0004] The quenching tower bottoms contain ammonium sulfate and organic oligomers (also known as heavy components). The heavy component content is higher in the lower and first-stage bottoms, and is currently incinerated (or incinerated to produce sulfuric acid). The upper tower bottoms contain a relatively low content of heavy components. Currently, solid ammonium sulfate fertilizer is produced through evaporation and crystallization in an ammonium sulfate unit. However, this also produces a concentrated waste liquid discharged from the crystallizer—ammonium sulfate polymer waste liquid. This waste liquid is a saturated ammonium sulfate liquid containing precipitated heavy components (organic oligomers) (ammonium sulfate is in a saturated state, and the saturated liquid also contains dissolved heavy components). The precipitated heavy components are also called insoluble heavy components. Because the ammonium sulfate polymer waste liquid contains a high concentration of heavy components (including precipitated and unprecipitated, or insoluble and dissolved states), it has a certain viscosity, and is currently also treated by incineration.

[0005] Among the three waste liquids in the above-mentioned incineration treatment (lower tower bottom liquid, first tower bottom liquid and ammonium sulfate polymer waste liquid), the ammonium sulfate polymer waste liquid often causes blockage of pipeline conveyor pumps, blockage of incineration nozzles and other conditions (due to the presence of viscous heavy components or oligomers), and can also cause blockage of bag purification facilities (bag dust collectors) (due to the high concentration of ammonium sulfate incineration and decomposition and cooling and salt formation at the dust bag, causing blockage). The high ammonium sulfate content of this ammonium sulfate polymer waste liquid has become an important factor affecting the instability of the incinerator of the environmental protection device. Therefore, how to separate (especially continuously and quickly separate) the organic oligomers in the ammonium sulfate polymer waste liquid of the acrylonitrile ammonium sulfate plant, reduce the amount of incineration waste liquid and reduce the ammonium sulfate content in the incineration waste liquid has become an urgent technology to ensure the long-term stable operation of the incinerator of the acrylonitrile enterprise, and also an urgent technology to improve the ammonium sulfate production capacity of the ammonium sulfate plant and realize the resource recovery of ammonium sulfate in the waste liquid. It is also an urgent technology to effectively recover the heavy components (oligomers) and then realize the resource utilization of the heavy components (oligomers). However, there is currently a lack of a rapid, continuous and effective separation method for precipitating heavy components (non-soluble oligomers) from the ammonium sulfate polymer wastewater of an acrylonitrile ammonium sulfate plant. Summary of the Invention

[0006] The present invention aims to solve the technical problem that the waste liquid of ammonium sulfate polymer in an acrylonitrile ammonium sulfate unit has an impact on the long-term stable operation of an incinerator, and provides a continuous separation method for precipitated oligomers in the waste liquid of ammonium sulfate polymer in an acrylonitrile ammonium sulfate unit.

[0007] The continuous separation method of oligomers precipitated from the ammonium sulfate polymer waste liquid of an acrylonitrile ammonium sulfate device of the present invention is carried out by the following steps:

[0008] The method of the present invention comprises two processing units: a dilution-cooling unit 101 and an adsorption filtration-filter material regeneration and reuse unit 102;

[0009] (1) The ammonium sulfate polymer waste liquid material from the ammonium sulfate device (temperature 80°C to 82°C, containing saturated ammonium sulfate liquid, dissolved heavy components and undissolved heavy components) first enters the dilution-cooling unit 101. The dilution-cooling unit 101 includes two subunits (or two process steps) of dilution and stirring and cooling. Both subunits adopt conventional methods and equipment. The dilution and stirring subunit reduces the ammonium sulfate concentration to 94% to 99% of the saturation concentration at room temperature by adding diluent (water or dilute ammonium sulfate liquid) (this ammonium sulfate liquid is called near-saturated ammonium sulfate liquid). The diluent comes from the diluent storage tank 103. The diluent is water or the incoming material of the ammonium sulfate device - dilute ammonium sulfate liquid (the bottom liquid of the upper section of the quenching tower); the cooling subunit reduces the temperature of the material diluted with the incoming liquid from 80°C to 82°C to 27°C to 32°C through a heat exchanger and circulating cooling water.

[0010] Cooling can reduce the solubility of heavy components in water, reduce the content of dissolved heavy components in the nearly saturated ammonium sulfate solution, and increase the amount of heavy components precipitated. Lowering the temperature can also increase the viscosity of the precipitated heavy components. The precipitated heavy components (viscous liquid) partially aggregate and float on the surface of the nearly saturated ammonium sulfate solution, and partially suspend in the liquid below the surface of the nearly saturated ammonium sulfate solution in the form of fine liquid droplets. The diluted and cooled material liquid (including the nearly saturated ammonium sulfate solution and the heavy components (dissolved and undissolved) therein) enters the adsorption filtration-filter material regeneration and reuse unit 102 to separate the precipitated heavy components (from the nearly saturated ammonium sulfate solution).

[0011] (2) The adsorption filtration-filter material regeneration and reuse unit 102 includes four subunits: an adsorption filtration unit 102-1, a centrifugal separation unit 102-2, a heavy component collection tank 102-3, and a filter material conveying unit 102-4. The centrifugal separation subunit 102-2 is also a filter material regeneration subunit. The filter material conveying subunit 102-4 adds the regenerated filter material after centrifugation of the centrifugal separation subunit 102-2 to the adsorption filtration unit 102-1 so that the regenerated filter material is recycled. The heavy components separated by the centrifugal separation unit 102-2 are collected in a tank. in the heavy component collection tank 102-3; the liquid material produced by the dilution-cooling unit 101 (including ammonium sulfate liquid and organic oligomers therein (organic oligomers include precipitated and unprecipitated, or non-dissolved and dissolved)) enters the subsequent adsorption filtration-filter material regeneration and reuse unit 102 for continuous separation of the precipitated heavy components (from the soluble liquid); the heavy components separated by the 102 unit are discharged into the heavy component collection tank 102-3, and the separated liquid (nearly saturated ammonium sulfate liquid) is returned to the ammonium sulfate device feed tank 104;

[0012] like Figure 2As shown, the adsorption filtration unit 102-1 is a U-shaped moving bed filter material adsorption tower, which is a U-shaped structure consisting of an adsorption cylinder 1 and a push cylinder 2 connected at the bottom, and the moving bed filter material adsorption tower is filled with filter cage balls 21; the adsorption cylinder 1 is composed of a water distribution-air collection part 31, a filter material part 29 and an aeration part 30 from top to bottom; the water distribution-air collection part 31 and the filter material part 29 are separated by an upper arc net 24, and the aeration part 30 and the filter material part 29 are separated by a bottom arc net 23; the peripheral edges of the bottom arc net 23 and the upper arc net 24 are closely connected with the cylinder wall, and the top projections of the bottom arc net 23 and the upper arc net 24 are circular with the same inner diameter as the cylinder; the filter material part 29 is The upper part is bent outward to extend a filter material drain pipe 3, and the outer end of the filter material drain pipe 3 is a filter material discharge port 4; the filter material drain pipe 3 is a ridge-shaped structure, and the angle β between the lower edge of the filter material drain pipe 3 and the side wall of the adsorption cylinder 1 is 120 degrees to 150 degrees, and the angle γ at the lower end of the filter material drain pipe 3 is 105 degrees to 135 degrees. The length of the upward inclined portion of the filter material drain pipe 3 is 0.5 times to 1.5 times the inner diameter of the adsorption cylinder 1; the liquid inlet pipe 5 and the water distribution pipe 6 on the water distribution-gas collecting part 31 are connected, and the exhaust pipe 28 is arranged at the top of the water distribution-gas collecting part 31. An aeration pipe 13 is provided in the aeration part 30, and the air outlet of the aeration pipe 13 is facing upward. An aeration pipe valve 12 is provided on the aeration pipe 13, and the inlet of the aeration pipe 13 is connected to the The air outlet of the external air compressor 11 is connected; the inlet 10 of the drain pipe 7 is arranged at the lower part of the aeration pipe 13 and on the central axis of the adsorption cylinder 1, the liquid outlet 8 of the drain pipe 7 is arranged below the bending point 25 of the lower edge of the filter material drain pipe 3, and a drain pipe valve 9 is provided on the drain pipe 7; a vent 15 and a vent valve 16 are provided at the bottom of the aeration part 30; a telescopic pusher 18 is provided at the top of the pushing cylinder 2, and the lower end of the telescopic pusher 18 is connected to the telescopic rod 20 and the pushing plate 19, and the telescopic rod 20 and the pushing plate 19 are in the inner cavity of the pushing cylinder 2; the filter material feed pipe 17 is provided on the upper side wall of the pushing cylinder 2, and the vertical angle α of the lower edge of the filter material feed pipe 17 is 120 degrees to 150 degrees; A support frame 27 is provided at the bottom of the moving bed filter adsorption tower; the inner diameters of the filter feed pipe 17, the adsorption cylinder 1, the push cylinder 2 and the filter drain pipe 3 are equal and the inner walls are smooth to ensure smooth movement of the filter material; the lowest point 26 of the lower edge of the filter feed pipe 17 is 1m to 2m higher than the liquid outlet 8, and the liquid outlet 8 is 10cm to 20cm lower than the lowest point 25 of the lower edge of the filter drain pipe 3; the filter cage ball 21 is composed of a rigid mesh spherical shell and a filter material filled inside; the spherical shell needs to have greater strength, does not undergo obvious deformation during centrifugation, and quickly returns to its original shape after centrifugation; the filter material filled inside is a porous filter material and a hard material, the filter material is granular, and the density is less than 1.0g / cm 3 The density of the filter material cage ball 21 after the combination of the filter material and the spherical cage is 1.10g / cm 3 ~1.20g / cm 3Preferably, the diameter of the filter cage ball 21 is 5cm to 20cm;

[0013] Adsorption filtration: Adsorption filtration is completed in a moving bed filter media adsorption tower, including two steps: liquid injection start-up and feed operation:

[0014] 1. Liquid injection start: Close the drain pipe valve 9, aeration pipe valve 12 and vent valve 16, start the telescopic pusher 18 and raise the push plate 19 to above the upper edge 17-1 of the filter material feed pipe 17 via the telescopic rod 20; add filter material cage balls 21 of different diameters into the push tower 2 through the filter material feed pipe 17, and ensure that the difference between the height of the filter material cage balls 21 in the adsorption cylinder 1 and the drainage outlet 8 is within the range of ±15 cm; inject pre-prepared nearly saturated ammonium sulfate solution (which can be obtained by mixing liquid from the ammonium sulfate device with solid ammonium sulfate product, with a concentration of 94% to 99% of the saturation concentration at room temperature; the liquid in this step can also be replaced by dilute ammonium sulfate solution) into the adsorption cylinder 1 through the liquid inlet pipe 5. The nearly saturated ammonium sulfate solution flows down through the water distribution pipe 6. When the height of the nearly saturated ammonium sulfate solution level 22 in the adsorption cylinder 1 is 5 cm to 15 cm lower than the drainage outlet 8, the liquid injection is completed, and the inlet of the liquid inlet pipe 5 is switched to communicate with the liquid outlet of the front-stage dilution-cooling unit 101;

[0015] 2. Adsorption operation: Open the drain pipe valve 9, start the aeration air compressor 11 and open the aeration pipe valve 12. Air (or dissolved liquid, if dissolved air flotation is used) is injected into the aeration section 30 through the aeration pipe 13. Air bubbles float up and pass through the curved mesh 23 at the bottom of the adsorption cylinder 1 into the filter material section 29. The bubbles continue to float to the liquid surface and escape from the filter material section 29 and are discharged from the exhaust pipe 28. The liquid discharged from the dilution-cooling unit 101 flows down through the water distribution pipe 6 and enters the tower.

[0016] In the adsorption cylinder 1, the aeration (flotation) gas moves from bottom to top and collides with the incoming liquid material, forming a collision between gas, liquid, precipitated heavy components and filter material on the filter surface. The heavy component particles (or liquid droplets) gather and quickly adhere to the filter surface in the filter cage ball 21. Since the precipitated heavy component particles have strong contact and aggregation, the material with oligomers adhered to the surface can continue to adhere to and gather the non-dissolved heavy components in the liquid, so that the thickness of the adsorption layer on the surface of the material continues to increase. Since both the filter material and the heavy component aggregates have strong adhesion and adsorption forces to the non-dissolved heavy component particles, the heavy component polymer microparticles (or liquid droplets) gathered by the bubble disturbance will quickly adhere to the filter material that is in contact with it. Or on the aggregate, the heavy components adsorbed or adhered to the filter material will not (or are difficult to) be brought up again by the bubbles, thus forming a situation where the heavy components are adhered and adsorbed at each height layer of the filter material adsorption tower, but the higher the filter material layer is, the more the adhesion and adsorption amount is, and the adhesion and adsorption amount gradually decreases as the height layer goes down (this is related to the top-down liquid inlet and discharge method); in the adsorption cylinder 1, an adhesion saturated layer, a near-saturated layer, an unsaturated layer, a less adsorbed layer and a non-adsorbed layer are formed from top to bottom in the height direction of the filter material layer; this distribution pattern (or condition) is consistent with the adsorption pattern of each height of the adsorption layer of the downward flow filter tank, so the present invention calls this process adsorption filtration; there is no fixed interface between the adsorption layers, but the adsorption stratification trend is obvious;

[0017] The feed liquid is added from the top of the filter layer. As the liquid flows downward, the insoluble heavy components (oligomers) are adsorbed and filtered layer by layer by the filter material. At the same time, the nearly saturated ammonium sulfate solution (containing dissolved heavy components) is gradually purified in this process.

[0018] (3) Filter material discharge and filter bed movement: When the surface adhering heavy component aggregates of the filter material in the top filter material cage ball 21 in the adsorption cylinder 1 reach adsorption saturation, the telescopic pusher 18 is started to make the telescopic rod 20 drive the push plate 19 to move downward, so that the filter material cage ball 21 in the push cylinder 2 moves downward, passes through the bottom and enters the adsorption cylinder 1, and the filter material cage ball 21 in the adsorption cylinder 1 moves upward; due to the transmission and squeezing effect between the filter material cage balls 21, as the push plate 19 on the push cylinder 2 moves downward, the adsorption saturation layer on the surface of the adsorption cylinder 1 is gradually squeezed out and moved out through the filter material discharge port 4 with the side opening; in this process, the filter material cage ball 21 in the adsorption cylinder 1 always keeps the bottom "new" (or regenerated) The filter material) and the upper layer adsorption is saturated (or nearly saturated), this "dynamic filter material moving bed" form is very beneficial to improving the adsorption and removal (adsorption filtration) effect of the precipitated heavy components, and at the same time, the non-dissolved heavy component content in the liquid (discharge No. 8) (nearly saturated ammonium sulfate liquid) discharged from the bottom of the adsorption cylinder 1 is reduced to an extremely low content (content 0.001% to 0.005% (w / w)), and the heavy component content (2.0% to 4.0% (w / w) (mainly dissolved)) in the discharged liquid (nearly saturated ammonium sulfate liquid) is consistent with the content level of the liquid from the ammonium sulfate device (the bottom liquid of the upper section of the quench tower), and all the liquid discharged from the discharge port 8 is returned to the ammonium sulfate device feed tank 104 for reuse;

[0019] (4) Filling and adding filter media: When the telescopic push plate 19 moves down to the bottom of the push cylinder 2, the push plate 19 is quickly moved up to above the upper edge 17-1 of the filter media feed pipe 17, and new filter media (or regenerated filter media) 21 is added from the filter media feed pipe 17. When the amount of filter media is equal to the upper edge 17-1 of the filter media feed pipe 17, the addition is stopped, and the telescopic pusher 18 drives the push plate 19 to move down again to push the filter media cage balls 21 in the push cylinder 2 toward the adsorption cylinder 1 and squeeze out the adsorption saturated filter media cage balls 21 in the adsorption part 29, and discharge them through the filter media discharge port 4;

[0020] When the incoming liquid flows from the water distribution pipe 6 into the adsorption cylinder 1, the filter cage balls 21 from the upper curved mesh 24 to the liquid surface 22 are continuously drenched with liquid, causing more water (or liquid) to be adsorbed into the heavy components of this section of saturated filter media. When this section of saturated adsorption filter cage balls 21 with a higher water content enters the filter media drain pipe 3, the liquid water (nearly saturated ammonium sulfate solution) adsorbed or attached to the filter cage balls 21 is drained out along the filter media drain pipe 3 and flows back into the adsorption cylinder 1. This can significantly reduce the water (and ammonium sulfate) content in the heavy component aggregates (oligomers) of the saturated adsorption filter media, thereby improving the purity (concentration) of the heavy components adsorbed by the filter media.

[0021] (5) Solid-liquid separation of adsorbed filter media - filter media regeneration: The adsorbed saturated filter media cage balls 21 squeezed out of the adsorption cylinder 1 (discharged through the filter media outlet 4) are sent to the centrifugal separation unit 102-2 for centrifugal separation between the filter media and the adsorbate; the heavy components (oligomers) adsorbed by the filter media have high viscosity but are fluid and have a relatively high density (1.25 g / cm 3 ~1.27g / cm 3 ), 30℃ (viscosity at 2×10 4 mPa.s~3×10 4 mPa.s) can drip from the surface of the filter material by gravity in the air, and can be effectively separated from the adsorbent heavy components and the filter material by centrifugation in a common low-speed centrifuge (speed of 3000-5000 rpm) for 10-20 minutes. This process is also the process of filter material regeneration; the heavy component (oligomer) content in the centrifuge liquid (the separated heavy component phase) can reach 90%-95% (w / w) and is collected in the heavy component collection tank 102-3 for future use (for incineration or resource utilization);

[0022] If the centrifugal environment temperature is low, the material temperature in the centrifugal separation unit 102-2 can be maintained at 30°C to 60°C by heating methods such as introducing hot air; when the centrifugal temperature is lower than 30°C, the separation effect is reduced, and when the temperature is too high (higher than 60°C), the surface active functional groups of the heavy components are easily oxidized (by oxygen in the air), which is not conducive to the subsequent resource utilization of the oligomers (such as modification, etc.); centrifugation can separate 80% to 90% (w / w) of the adsorbent (oligomer) of the saturated adsorption capacity of the filter material. The filter material after centrifugation is the regenerated filter material. The internal pores of the regenerated filter material can be seen to the naked eye as transparent as before, and the surface of the filter material can show the original color of the material. After centrifugal separation, a small amount of oligomers will still be uniformly attached to the surface of the filter material to form a basement membrane layer. The basement membrane layer can improve the wettability of the regenerated filter material, which is beneficial to the adhesion and adsorption of heavy components when the regenerated filter material is recycled. After the filter material is regenerated 2 to 4 times, the amount of the basement membrane layer of the regenerated filter material is basically maintained in a certain range (10% to 20% (w / w) of the saturated adsorption capacity), and the saturated adsorption capacity of the filter material is also basically stable.

[0023] The regenerated filter material is added to the filter material feed pipe 17 of the push cylinder 2 through the filter material conveying unit 102-4 for recycling;

[0024] Note: (1) Regarding the density, particle size, pore size and material of the filter cage ball and the internal filling filter material. The density of the heavy component of the material involved in the present invention is 1.25-1.27 g / cm 3 The density of nearly saturated ammonium sulfate solution is 1.22~1.25g / cm 3 The density of the filter cage ball is 1.1g / cm 3 ~1.2g / cm 3, the density of the filter cage balls is similar to the density of the liquid (the former is slightly lower), which is conducive to the movement of the filter cage balls in the tower, keeping the filter layer of the adsorption cylinder 1 dense and tight, and maintaining a stable adsorption and filtration effect. The density of the filter cage balls is slightly lower than the density of the liquid, and the filter layer in the adsorption cylinder 1 shows an upward floating trend (state), which can avoid the upper filter material in the adsorption cylinder 1 from settling significantly during the upward feeding process of the push plate 19 in the push cylinder 2, thereby affecting the adsorption and filtration effect. When selecting the material of the filter material for internal filling, it is more appropriate to choose plastic materials such as polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC), and polyvinylidene fluoride (PVDF) that have good wettability to medium polarity liquids. The filter material density is less than 1.0g / cm 3 The filter material is porous, and the internal pores need to be through-type (i.e. there are no dead ends). The filter material particle size should be 1cm to 2cm in length, and the narrow distance of the pores should be 2mm to 4mm. This can form adsorbed (wrapped, wrapped, and entrained, that is, the pores are filled with adsorbents) heavy components in the gaps of the filter material, which increases the heavy component of the filter material adsorption load, increases the specific adsorption capacity of the filter material (the adsorption capacity per unit volume or mass of the filter material), and improves the adsorption efficiency of the filter material. When using the filter material, a mesh spherical cage is used to load a number of filter material particles, which is conducive to pushing or moving the filter material in the tower. The spherical cage can effectively prevent the "caking" (increase in aggregate blocks) and fluid (gas and liquid) short-flow caused by saturated adsorption of the filter material in the cylinder, and is also convenient for conveying operations during filter material regeneration and filling. The filter material density is less than 1.0g / cm 3 The purpose is that: the filter material is affected by the buoyancy of the liquid, and the filter material in the filter material cage ball 21 in the adsorption part 29 is in a floating state in the cage and close to the upper space of the cage, and the lowermost part of the space in the cage is vacant (vacant here means there is no filter material), forming a "disconnected" state of the filter material between the upper and lower adjacent filter material layers (produced by the vacant space in the cage ball). This is conducive to the bubbles from bottom to top passing through the cage net into the cage, thereby improving the flotation separation and filter material adsorption effect of the filter material inside the cage ball, and can also effectively alleviate the "sticking" effect of the upper and lower adjacent layers of the filter material (sticking here means being stuck together by a large number of oligomer aggregates and affecting gas-liquid mass transfer), thereby improving the separation effect.

[0025] (2) Regarding the continuous pushing of the filter material in the pushing tube 2: When the filter material cage ball 21 of the pushing tube 2 is continuously pushed downward, the downward pushing speed of the telescopic pusher 18 is higher than the adsorption saturation speed of the surface filter material in the adsorption tube 1, and the speed is higher by 15% to 25%. This can ensure that the heavy components adsorbed by the filter material in the filter material part 29 are removed from the tower in time, improve the filtration efficiency of the adsorption filter layer, and continuously maintain a high adsorption filtration effect. It can also make up for the problem that during the process of adding regenerated filter material, the filter material push is interrupted due to the upward movement of the pushing plate 19 in the pushing tube 2, and the surface adsorption amount of the filter material part 29 is too much and cannot be removed in time, resulting in reduced adsorption efficiency.

[0026] In summary, the ammonium sulfate polymer wastewater from the acrylonitrile ammonium sulfate plant, after being treated by the method of the present invention, can recover 97% to 99% (w / w) of the ammonium sulfate in the wastewater (entering 104), and the heavy component (oligomer) content (or purity) in the separated oligomer phase (102-3) can reach 90% to 95% (w / w). If the separated heavy component liquid is treated by incineration, the amount of ammonium sulfate incinerated is only 0.5% to 1.5% of the original amount of ammonium sulfate incinerated (the inlet liquid 101), which can significantly alleviate or eliminate the impact of ammonium sulfate on the incinerator device, ensuring the long-term stable operation of the incinerator device.

[0027] The method of the present invention solves the problem of separating heavy components in ammonium sulfate polymer waste liquid of an acrylonitrile ammonium sulfate unit, and has the advantages of fast separation speed, high separation efficiency, good separation effect, simple filter material regeneration, low operating cost and continuous operation. It provides strong support for improving the ammonium sulfate production capacity of the original ammonium sulfate unit and resource utilization of heavy components (oligomers), and can also provide a useful reference for the resource recovery of ammonium sulfate and heavy components in the bottom liquid of the lower section of the acrylonitrile quench tower and the bottom liquid of the first section of the tower. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a flow chart of a method for continuously separating oligomers precipitated from ammonium sulfate polymer wastewater in an acrylonitrile ammonium sulfate unit according to a specific embodiment of the present invention;

[0029] Figure 2 Schematic diagram of a moving bed filter material adsorption tower according to a first embodiment. DETAILED DESCRIPTION

[0030] Specific embodiment 1: This embodiment is a continuous separation method for oligomers precipitated from ammonium sulfate polymer wastewater of an acrylonitrile ammonium sulfate device, which is specifically carried out according to the following steps:

[0031] The method of this embodiment includes two processing units: Figure 1 As shown, a dilution-cooling unit 101 and an adsorption filtration-filter material regeneration and reuse unit 102;

[0032] (1) The ammonium sulfate polymer waste liquid material (temperature 80°C to 82°C, containing saturated ammonium sulfate liquid, dissolved heavy components and undissolved heavy components) from the ammonium sulfate device first enters the dilution-cooling unit 101. The dilution-cooling unit 101 includes two subunits (or two process steps) of dilution and stirring and cooling. The dilution and stirring subunit reduces the ammonium sulfate concentration to 94% to 99% of the saturation concentration at room temperature by adding diluent (this ammonium sulfate liquid is called near-saturated ammonium sulfate liquid). The diluent comes from the diluent storage tank 103. The cooling subunit reduces the temperature of the material diluted with the diluent from 80°C to 82°C to 27°C to 32°C through a heat exchanger and circulating cooling water.

[0033] Cooling can reduce the solubility of heavy components in water, reduce the content of dissolved heavy components in the nearly saturated ammonium sulfate solution, and increase the amount of heavy components precipitated. Lowering the temperature can also increase the viscosity of the precipitated heavy components. The precipitated heavy components (viscous liquid) partially aggregate and float on the surface of the nearly saturated ammonium sulfate solution, and partially suspend in the liquid below the surface of the nearly saturated ammonium sulfate solution in the form of fine liquid droplets. The diluted and cooled material liquid (including the nearly saturated ammonium sulfate solution and the heavy components (dissolved and undissolved precipitated) therein) enters the adsorption filtration-filter material regeneration and reuse unit 102 to separate the precipitated heavy components (from the nearly saturated ammonium sulfate solution).

[0034] (2) The adsorption filtration-filter material regeneration and reuse unit 102 includes four subunits: an adsorption filtration unit 102-1, a centrifugal separation unit 102-2, a heavy component collection tank 102-3, and a filter material conveying unit 102-4. The centrifugal separation subunit 102-2 is also a filter material regeneration subunit. The filter material conveying subunit 102-4 adds the regenerated filter material after centrifugation of the centrifugal separation subunit 102-2 to the adsorption filtration unit 102-1 so that the regenerated filter material is recycled. The heavy components separated by the centrifugal separation unit 102-2 are collected in a tank. in the heavy component collection tank 102-3; the liquid material produced by the dilution-cooling unit 101 (including ammonium sulfate liquid and organic oligomers therein (organic oligomers include precipitated and unprecipitated, or non-dissolved and dissolved)) enters the subsequent adsorption filtration-filter material regeneration and reuse unit 102 for continuous separation of the precipitated heavy components (from the soluble liquid); the heavy components separated by the 102 unit are discharged into the heavy component collection tank 102-3, and the separated liquid (nearly saturated ammonium sulfate liquid) is returned to the ammonium sulfate device feed tank 104;

[0035] like Figure 2As shown, the adsorption filtration unit 102-1 is a U-shaped moving bed filter material adsorption tower, which is a U-shaped structure consisting of an adsorption cylinder 1 and a push cylinder 2 connected at the bottom, and the moving bed filter material adsorption tower is filled with filter cage balls 21; the adsorption cylinder 1 is composed of a water distribution-air collection part 31, a filter material part 29 and an aeration part 30 from top to bottom; the water distribution-air collection part 31 and the filter material part 29 are separated by an upper arc net 24, and the aeration part 30 and the filter material part 29 are separated by a bottom arc net 23; the peripheral edges of the bottom arc net 23 and the upper arc net 24 are closely connected with the cylinder wall, and the top projections of the bottom arc net 23 and the upper arc net 24 are circular with the same inner diameter as the cylinder; the filter material part 29 is The upper part is bent outward to extend a filter material drain pipe 3, and the outer end of the filter material drain pipe 3 is a filter material discharge port 4; the filter material drain pipe 3 is a ridge-shaped structure, and the angle β between the lower edge of the filter material drain pipe 3 and the side wall of the adsorption cylinder 1 is 120 degrees to 150 degrees, and the angle γ at the lower end of the filter material drain pipe 3 is 105 degrees to 135 degrees. The length of the upward inclined portion of the filter material drain pipe 3 is 0.5 times to 1.5 times the inner diameter of the adsorption cylinder 1; the liquid inlet pipe 5 and the water distribution pipe 6 on the water distribution-gas collecting part 31 are connected, and the exhaust pipe 28 is arranged at the top of the water distribution-gas collecting part 31. An aeration pipe 13 is provided in the aeration part 30, and the air outlet of the aeration pipe 13 is facing upward. An aeration pipe valve 12 is provided on the aeration pipe 13, and the inlet of the aeration pipe 13 is connected to the The air outlet of the external air compressor 11 is connected; the inlet 10 of the drain pipe 7 is arranged at the lower part of the aeration pipe 13 and on the central axis of the adsorption cylinder 1, the liquid outlet 8 of the drain pipe 7 is arranged below the bending point 25 of the lower edge of the filter material drain pipe 3, and a drain pipe valve 9 is provided on the drain pipe 7; a vent 15 and a vent valve 16 are provided at the bottom of the aeration part 30; a telescopic pusher 18 is provided at the top of the pushing cylinder 2, and the lower end of the telescopic pusher 18 is connected to the telescopic rod 20 and the pushing plate 19, and the telescopic rod 20 and the pushing plate 19 are in the inner cavity of the pushing cylinder 2; the filter material feed pipe 17 is provided on the upper side wall of the pushing cylinder 2, and the vertical angle α of the lower edge of the filter material feed pipe 17 is 120 degrees to 150 degrees; A support frame 27 is provided at the bottom of the moving bed filter adsorption tower; the inner diameters of the filter feed pipe 17, the adsorption cylinder 1, the push cylinder 2 and the filter drain pipe 3 are equal and the inner walls are smooth to ensure smooth movement of the filter material; the lowest point 26 of the lower edge of the filter feed pipe 17 is 1m to 2m higher than the liquid outlet 8, and the liquid outlet 8 is 10cm to 20cm lower than the lowest point 25 of the lower edge of the filter drain pipe 3; the filter cage ball 21 is composed of a rigid mesh spherical shell and a filter material filled inside; the spherical shell needs to have greater strength, does not undergo obvious deformation during centrifugation, and quickly returns to its original shape after centrifugation; the filter material filled inside is a porous filter material and a hard material, the filter material is granular, and the density is less than 1.0g / cm 3 The density of the filter material cage ball 21 after the combination of the filter material and the spherical cage is 1.10g / cm 3 ~1.20g / cm 3Preferably, the diameter of the filter cage ball 21 is 5cm to 20cm;

[0036] Adsorption filtration: Adsorption filtration is completed in a moving bed filter media adsorption tower, including two steps: liquid injection start-up and feed operation:

[0037] 1. Liquid injection start: Close the drain pipe valve 9, the aeration pipe valve 12 and the vent valve 16, start the telescopic pusher 18 and raise the push plate 19 to above the upper edge 17-1 of the filter material feed pipe 17 through the telescopic rod 20; add filter cage balls 21 of different diameters into the push tower 2 from the filter material feed pipe 17 and make the difference between the height of the filter cage balls 21 in the adsorption cylinder 1 and the drain outlet 8 within the range of ±15cm; inject the pre-prepared liquid into the adsorption cylinder 1 from the liquid inlet pipe 5. Nearly saturated ammonium sulfate liquid (which can be prepared by mixing liquid from an ammonium sulfate device (i.e., dilute ammonium sulfate liquid) with a solid ammonium sulfate product, with a concentration of 94% to 99% of the saturated concentration at room temperature; the liquid in this step can also be replaced by dilute ammonium sulfate liquid), the nearly saturated ammonium sulfate liquid flows down through the water distribution pipe 6, and the injection is completed when the height of the nearly saturated ammonium sulfate liquid level 22 in the adsorption cylinder 1 is 5 to 15 cm lower than the drainage outlet 8, and the inlet of the liquid inlet pipe 5 is switched to be connected to the liquid outlet of the front-stage dilution-cooling unit 101;

[0038] 2. Adsorption operation: Open the drain pipe valve 9, start the aeration air compressor 11 and open the aeration pipe valve 12. Air (or dissolved liquid, if dissolved air flotation is used) is injected into the aeration section 30 through the aeration pipe 13. Air bubbles float up and pass through the curved mesh 23 at the bottom of the adsorption cylinder 1 into the filter material section 29. The bubbles continue to float to the liquid surface and escape from the filter material section 29 and are discharged from the exhaust pipe 28. The liquid discharged from the dilution-cooling unit 101 flows down through the water distribution pipe 6 and enters the tower.

[0039] In the adsorption cylinder 1, the aeration (flotation) gas moves from bottom to top and contacts the incoming liquid material, forming a collision between gas, liquid, precipitated heavy components and filter material on the filter surface. The heavy component particles (or liquid droplets) gather and quickly adhere to the surface of the filter material in the filter cage ball 21. Since the precipitated heavy component particles have strong contact aggregation, the material with oligomers adhered to the surface can continue to adhere to the non-dissolved heavy components in the aggregated liquid, so that the thickness of the adsorption layer on the surface of the material continues to increase. Since both the filter material and the heavy component aggregates have strong adhesion and adsorption force to the non-dissolved heavy component particles, the heavy component polymer microparticles (or liquid droplets) gathered by the bubble disturbance will quickly adhere to the filter material or filter material that is in contact nearby. On the aggregate, the heavy components adsorbed or adhered to the filter material will not (or are difficult to) be re-entrained by the bubbles, resulting in a situation where the heavy components are adhered and adsorbed at each height layer of the filter material adsorption tower, but the amount of adhesion and adsorption increases as the filter material layer is closer to the top, and the amount of adhesion and adsorption gradually decreases as the height layer goes down (this is related to the top-down liquid inlet and discharge method); in the adsorption cylinder 1, an adhesion saturated layer, a near-saturated layer, an unsaturated layer, a less adsorbed layer and an unadsorbed layer are formed from top to bottom in the height direction of the filter material layer; this distribution pattern (or condition) is consistent with the adsorption pattern of each height of the adsorption layer of the downward flow filter tank, so the present invention calls this process adsorption filtration; there is no fixed interface between the adsorption layers, but the adsorption stratification trend is obvious;

[0040] The feed liquid is added from the top of the filter layer. As the liquid flows downward, the insoluble heavy components (oligomers) are adsorbed and filtered layer by layer by the filter material. At the same time, the nearly saturated ammonium sulfate solution (containing dissolved heavy components) is gradually purified in this process.

[0041] (3) Filter material discharge and filter bed movement: When the adhered heavy component aggregates of the filter material in the top filter material cage ball 21 in the adsorption cylinder 1 reach adsorption saturation, the telescopic pusher 18 is started to make the telescopic rod 20 drive the push plate 19 to move downward, so that the filter material cage ball 21 in the push cylinder 2 moves downward, passes through the bottom and enters the adsorption cylinder 1, and the filter material cage ball 21 in the adsorption cylinder 1 moves upward; due to the transmission and squeezing effect between the filter material cage balls, as the push plate 19 on the push cylinder 2 moves downward, the adsorption saturation layer on the surface of the adsorption cylinder 1 is gradually squeezed out and moved out through the filter material discharge port 4 with the side opening; in this process, the filter material cage ball 21 in the adsorption cylinder 1 always keeps the bottom layer "new" (or regenerated filter material) The upper layer is in a saturated (or nearly saturated) adsorption state. This "dynamic filter material moving bed" form is very beneficial to improving the adsorption removal (adsorption filtration) effect of the precipitated heavy components. At the same time, the non-dissolved heavy component content in the liquid (discharge No. 8) (nearly saturated ammonium sulfate liquid) discharged from the bottom of the adsorption cylinder 1 is reduced to an extremely low level (content 0.001% to 0.005% (w / w)). The heavy component content in the discharged liquid (nearly saturated ammonium sulfate liquid) (2.0% to 4.0% (w / w) (mainly dissolved)) is consistent with the heavy component content level of the liquid from the ammonium sulfate device (the bottom liquid of the upper section of the quench tower). All the liquid discharged from the discharge port 8 is returned to the ammonium sulfate device feed tank 104 for reuse.

[0042] (4) Filling and adding filter media: When the telescopic push plate 19 moves down to the bottom of the push cylinder 2, the push plate 19 is quickly moved up to above the upper edge 17-1 of the filter media feed pipe 17, and new filter media (or regenerated filter media) 21 is added from the filter media feed pipe 17. When the amount of filter media is equal to the upper edge 17-1 of the filter media feed pipe 17, the addition is stopped, and the telescopic pusher 18 drives the push plate 19 to move down again to push the filter media cage balls 21 in the push cylinder 2 toward the adsorption cylinder 1 and squeeze out the adsorption saturated filter media cage balls 21 in the adsorption cylinder 29, and discharge them through the filter media discharge port 4;

[0043] When the incoming liquid flows from the water distribution pipe 6 into the adsorption cylinder 1, the filter cage balls 21 from the upper curved mesh 24 to the liquid surface 22 are continuously drenched with liquid, causing more water (or liquid) to be adsorbed into the heavy components of this section of saturated filter media. When this section of saturated adsorption filter cage balls 21 with a higher water content enters the filter media drain pipe 3, the liquid water (nearly saturated ammonium sulfate solution) adsorbed or attached to the filter cage balls 21 is drained out along the filter media drain pipe 3 and flows back into the adsorption cylinder 1. This can significantly reduce the water (and ammonium sulfate) content in the heavy component aggregates (oligomers) of the saturated adsorption filter media, thereby improving the purity (concentration) of the heavy components adsorbed by the filter media.

[0044] (5) Solid-liquid separation of adsorbed filter media - filter media regeneration: The adsorbed saturated filter media cage balls 21 squeezed out of the adsorption cylinder 1 (discharged through the filter media outlet 4) are sent to the centrifugal separation unit 102-2 for centrifugal separation between the filter media and the adsorbate; the heavy components (oligomers) adsorbed by the filter media have high viscosity but are fluid and have a relatively high density (1.25 g / cm 3 ~1.27g / cm 3 ), 30℃ (viscosity at 2×10 4 mPa.s~3×10 4 mPa.s) can drip from the surface of the filter material by gravity in the air, and can be effectively separated from the adsorbent heavy components and the filter material by centrifugation in a common low-speed centrifuge (speed of 3000-5000 rpm) for 10-20 minutes. This process is also the process of filter material regeneration; the heavy component (oligomer) content in the centrifuge liquid (the separated heavy component phase) can reach 90%-95% (w / w) and is collected in the heavy component collection tank 102-3 for future use (for incineration or resource utilization);

[0045] If the centrifugal environment temperature is low, the material temperature in the centrifugal separation unit 102-2 can be kept at 30°C to 60°C by introducing hot air or other heating methods; when the centrifugal temperature is lower than 30°C, the separation effect is reduced, and when the temperature is too high (higher than 60°C), the surface active functional groups of the heavy components are easily oxidized (oxygen in the air), which is not conducive to the resource utilization (such as modification) of the oligomers in the future; centrifugation can separate 80% to 90% (w / w) of the saturated adsorption capacity of the filter material (oligomers), and the filter material after centrifugation is Regenerated filter media: The internal pores of the regenerated filter media are as transparent as before, and the surface of the filter media can show the original color of the material. After centrifugal separation, a small amount of oligomers will still be evenly attached to the surface of the filter media to form a basement membrane layer. The basement membrane layer can improve the wettability of the regenerated filter media, which is beneficial to the adhesion and adsorption of heavy components when the regenerated filter media is recycled. After the filter media is regenerated 2 to 4 times, the amount of the basement membrane layer of the regenerated filter media is basically maintained in a certain range (10% to 20% (w / w) of the saturated adsorption capacity), and the saturated adsorption capacity of the filter media is also basically stable.

[0046] The regenerated filter material is added to the filter material feed pipe 17 of the push cylinder 2 through the filter material conveying unit 102-4 for recycling;

[0047] In summary, the ammonium sulfate polymer wastewater from the acrylonitrile ammonium sulfate plant, after being treated by the method of the present invention, can recover 97% to 99% (w / w) of the ammonium sulfate in the wastewater (entering 104), and the heavy component (oligomer) content (or purity) in the separated oligomer phase (102-3) can reach 90% to 95% (w / w). If the separated heavy component liquid is treated by incineration, the amount of ammonium sulfate incinerated is only 0.5% to 1.5% of the original amount of ammonium sulfate incinerated (the inlet liquid 101), which can significantly alleviate or eliminate the impact of ammonium sulfate on the incinerator device, ensuring the long-term stable operation of the incinerator device.

[0048] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that the diluent described in (1) is water or the incoming material of the ammonium sulfate device - dilute ammonium sulfate solution. Other aspects are the same as specific embodiment 1.

[0049] Specific embodiment 3: This embodiment differs from specific embodiment 1 or 2 in that: the filter cage ball 21 described in (2) is composed of a rigid mesh spherical shell and a filter material filled inside; the spherical shell needs to be relatively strong, does not undergo significant deformation during centrifugation, and quickly returns to its original shape after centrifugation; the diameter of the filter cage ball 21 is 5cm to 20cm; the filter material filled inside is made of particles formed from hard polymer materials, and the particle volume is 1cm 3 ~5cm 3 The shape is spherical, cylindrical, or blocky. The surface and interior of the particles need to be hollow (i.e., multi-pore). The narrowest distance between the pores is 2mm to 4mm. The filter material is plastic material, including polyethylene (PE), polypropylene (PP), reinforced polypropylene, polyvinyl chloride, chlorinated polyvinyl chloride, polyvinylidene fluoride or ethylene-propylene copolymer. The shape is completed by injection molding. The filter material density is less than 1.0g / cm 3 The density of the filter cage ball 21 after the filter material and the spherical cage shell combination is 1.10g / cm 3 ~1.20g / cm 3 Others are the same as the specific implementation method one or two.

[0050] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that the centrifugal separation unit 102-2 described in (2) is a centrifuge. Other aspects are the same as specific embodiments 1 to 3.

[0051] Specific embodiment 5: This embodiment differs from specific embodiment 4 in that the filter material conveying unit 102-4 described in (2) is a belt conveyor. Other aspects are the same as specific embodiment 4.

[0052] The present invention is verified by the following test:

[0053] Experiment 1: A northern refining and chemical company has an acrylonitrile production capacity of 80,000 tons / year. The properties of the incoming dilute ammonium sulfate liquid and the ammonium sulfate polymer waste liquid discharged from the crystallizer of the company's ammonium sulfate unit are as follows:

[0054] (1) The temperature of the ammonium sulfate polymer wastewater in the ammonium sulfate unit is 81.2°C and the density is 1.27 g / cm 3 When the temperature drops to room temperature, a large amount of ammonium sulfate solid will precipitate, and a large amount of brown-black oligomers can be clearly seen precipitating on the surface and inside of the liquid, making the liquid turbid;

[0055] (2) The temperature of the incoming dilute ammonium sulfate solution of the ammonium sulfate unit is room temperature and the density is 1.14 g / cm 3 The ammonium sulfate content in the dilute ammonium sulfate solution is 17.9% (w / w), and the liquid is brown and transparent; (01 unit dilution)

[0056] Dilution and cooling: 6.265 kg of the ammonium sulfate polymer waste liquid from the ammonium sulfate device described in (1) was taken into a 10 L barrel, stirred, and 1.61 kg of the dilute ammonium sulfate solution described in (2) was added. After continuing to stir for 10 minutes, the mixture was cooled by heat exchange in a tubular heat exchanger (using tap water as circulating cooling water). When the temperature dropped to 25.8°C, the dilution and cooling was completed. During the cooling process, no ammonium sulfate solid crystals were precipitated, brown-black oligomers floated on the liquid surface, and brown-black fine liquid droplets (precipitated oligomers) were clearly seen inside the liquid. The liquid was brown-yellow and turbid. The lower aqueous phase of the mixed solution was taken and the ammonium sulfate content was measured to be 41.7% (w / w), which was 95.9% (times) of the saturated ammonium sulfate concentration (43.5% (w / w)) at room temperature (25.0°C).

[0057] Adsorption and centrifugal separation: The U-shaped moving bed filter adsorption tower in the specific embodiment 1 is used, and a cylindrical hollow hard filter material made of polyvinyl chloride (particle length of about 1 cm and diameter of about 1 cm) is added through the filter material feed pipe 17. Aeration is performed by the air compressor 11, and the cooled mixed liquid is added to the adsorption cylinder 1 through a peristaltic pump. The liquid inlet flow rate is 16 mL / min to 19 mL / min. According to the continuous liquid inlet and outlet of the present invention, the precipitated heavy components quickly adhere to the surface of the surface filter material and form aggregate blocks. The bottom liquid is clear and transparent and flows out continuously. When the liquid inlet is At 5.7 L, a large amount of adherent matter was present within the filter material layer at a height of approximately 6.2 cm (from the surface layer), and liquid feeding was stopped. The adsorbent filter material was removed from filter material outlet 4 and loaded several times into 50 mL centrifuge tubes (with a metal mesh filled within the approximately 15 mL mark at the bottom of the centrifuge tube). The mixture was centrifuged at 3000 rpm for 10 minutes, and the heavy components (oligomers) obtained by centrifugation were combined. The heavy components were centrifuged again for 10 minutes, and a small amount of transparent water layer was visible. After separation and weighing, the heavy component (oligomer) content was calculated to be 92.5% (w / w), and the density of the heavy component was measured to be 1.272 g / cm. 3The viscosity of the heavy component at room temperature (29°C) was 2.27×10 4 mPa.s.

[0058] The total organic carbon (TOC) content of the clear and transparent nearly saturated ammonium sulfate liquid obtained by separation is 2.01% (w / w). If calculated as polyacrylonitrile as the oligomer, the oligomer content in the transparent nearly saturated ammonium sulfate liquid after aeration flotation separation is equivalent to about 2.96% (w / w). This value is consistent with the heavy component concentration level range of 2% to 4% (w / w) in the liquid from the ammonium sulfate device.

[0059] Evaporation and crystallization of a near-saturated ammonium sulfate solution after separation and removal of precipitated heavy oligomers: 200 mL of the diluted and cooled solution and 200 mL of the clear, transparent solution obtained by adsorption filtration were each subjected to reduced-pressure evaporation and crystallization. The crystals were then dried at 120°C for 2 hours. The ammonium sulfate salt obtained from the near-saturated ammonium sulfate solution without separation and removal of heavy components (dilution and cooling) was a pale yellow solid with an organic content of 4.50% (w / w) (based on TOC). The ammonium sulfate salt obtained from the near-saturated ammonium sulfate solution after separation and removal of heavy oligomers (adsorption and centrifugation) was white with an organic content of 1.05% (w / w) (based on TOC). The salt obtained from the near-saturated ammonium sulfate solution after separation and removal of heavy components was significantly superior to the salt obtained from the near-saturated ammonium sulfate solution without separation and removal of heavy components.

Claims

1. A continuous separation method for heavy oligomers precipitated from ammonium sulfate polymer wastewater produced by an acrylonitrile ammonium sulfate device, characterized in that: The method comprises two processing units: a dilution-cooling unit (101) and an adsorption filtration-filter material regeneration and reuse unit (102); (1) The ammonium sulfate polymer waste liquid material from the ammonium sulfate device first enters the dilution-cooling unit (101). The dilution-cooling unit (101) includes two sub-units: dilution stirring and cooling. The dilution stirring sub-unit reduces the ammonium sulfate concentration to 94%~99% of the saturation concentration at room temperature by adding diluent. The diluent comes from the dilution liquid storage tank (103); the cooling sub-unit reduces the temperature of the diluted material from 80℃~82℃ to 27℃~32℃ through a heat exchanger and circulating cooling water. (2) The adsorption filtration-filter material regeneration and reuse unit (102) includes four subunits, namely, an adsorption filtration unit (102-1), a centrifugal separation unit (102-2), a heavy component collection tank (102-3), and a filter material conveying unit (102-4); the centrifugal separation unit (102-2) is also a filter material regeneration unit, and the filter material conveying unit (102-4) adds the regenerated filter material after centrifugation of the centrifugal separation unit (102-2) to the adsorption filtration unit (102-1) so that the regenerated filter material can be recycled, and the heavy components after being processed by the centrifugal separation unit (102-2) are collected in the heavy component collection tank (102-3); The liquid material generated by the dilution-cooling unit (101) enters the subsequent adsorption filtration-filter material regeneration and reuse unit (102) for continuous separation of heavy components; the heavy components separated by the adsorption filtration-filter material regeneration and reuse unit (102) are discharged into the heavy component collection tank (102-3), and the separated liquid is returned to the ammonium sulfate device feed tank (104); The adsorption filtration unit (102-1) is a U-shaped moving bed filter material adsorption tower. The moving bed filter material adsorption tower is a U-shaped structure composed of an adsorption cylinder (1) and a push cylinder (2) connected at the bottom. The moving bed filter material adsorption tower is filled with filter material cage balls (21). The adsorption cylinder (1) is composed of a water distribution-air collection part (31), a filter material part (29) and an aeration part (30) from top to bottom. The water distribution-air collection part (31) and the filter material part (29) are separated by an upper arc net (24), and the aeration part (30) and the filter material part (29) are separated by a bottom arc net (23). The bottom arc net (23) and the upper arc net (24) are separated. The peripheral edge is closely connected with the cylinder wall, and the top projection of the bottom arc-shaped net (23) and the upper arc-shaped net (24) is a circle with the same inner diameter as the cylinder; the upper part of the filter material part (29) is bent outward to extend the filter material drain pipe (3), and the outer end of the filter material drain pipe (3) is the filter material discharge port (4); the filter material drain pipe (3) is a ridge-shaped structure, and the angle β between the lower edge of the filter material drain pipe (3) and the side wall of the adsorption cylinder (1) is 120 degrees to 150 degrees, and the angle γ at the lower end of the ridge-shaped structure of the filter material drain pipe (3) is 105 degrees to 135 degrees. The length of the upward inclined part of the filter material drain pipe (3) is 0.5 times to 1.5 times; the liquid inlet pipe (5) on the water distribution-gas collection part (31) is connected to the water distribution pipe (6); the exhaust pipe (28) is arranged at the top of the water distribution-gas collection part (31); an aeration pipe (13) is provided in the aeration part (30); the air outlet of the aeration pipe (13) faces upward; an aeration pipe valve (12) is provided on the aeration pipe (13); the inlet of the aeration pipe (13) is connected to the air outlet of the air compressor (11) arranged outside; the inlet (10) of the discharge pipe (7) is arranged The liquid outlet (8) of the drainage pipe (7) is arranged below the bending point (25) of the lower edge of the filter material drain pipe (3) at the lower part of the aeration pipe (13) and on the central axis of the adsorption cylinder (1). The drainage pipe valve (9) is arranged on the drainage pipe (7); the bottom of the aeration part (30) is provided with a vent (15) and a vent valve (16); the top of the pushing cylinder (2) is provided with a telescopic pusher (18), and the lower end of the telescopic pusher (18) is connected to the telescopic rod (20) and the pushing plate ( 19) are connected, the telescopic rod (20) and the pushing plate (19) are in the inner cavity of the pushing cylinder (2); the filter material feeding pipe (17) is arranged on the upper side wall of the pushing cylinder (2), and the angle α between the lower edge of the filter material feeding pipe (17) and the vertical direction is 120 degrees to 150 degrees; a support frame (27) is arranged at the bottom of the moving bed filter material adsorption tower; the inner diameters of the filter material feeding pipe (17), the adsorption cylinder (1), the pushing cylinder (2) and the filter material draining pipe (3) are equal and the inner walls are smooth. Ensure smooth movement of the filter material; the lowest point (26) of the lower edge of the filter material feed pipe (17) is 1m~2m higher than the liquid outlet (8), and the liquid outlet (8) is 10cm~20cm lower than the bending point (25) of the lower edge of the filter material drain pipe (3); the filter material cage ball (21) is composed of a rigid mesh spherical shell and a filter material filled inside; the filter material filled inside is a porous filter material and a hard material, the filter material is granular, and the density is less than 1g / cm. 3 The density of the filter cage ball (21) after the filter material and the rigid mesh spherical shell are combined is 1.1g / cm 3 ~1.20g / cm 3 , the diameter of the filter cage ball (21) is 5cm~20cm; Adsorption filtration: Adsorption filtration is completed in a moving bed filter media adsorption tower, including two steps: liquid injection start-up and feed operation:

1. Liquid injection start: close the drain pipe valve (9), the aeration pipe valve (12) and the vent valve (16), start the telescopic pusher (18) and raise the push plate (19) to a position higher than the upper edge (17-1) of the filter material feed pipe (17) through the telescopic rod (20); add filter material cage balls (21) of mixed diameters into the push cylinder (2) from the filter material feed pipe (17) and make the difference between the height of the filter material cage balls (21) in the adsorption cylinder (1) and the height of the liquid outlet (8) within the range of ±15 cm; inject pre-prepared nearly saturated ammonium sulfate solution into the adsorption cylinder 1 from the liquid inlet pipe (5), and the nearly saturated ammonium sulfate solution flows down through the water distribution pipe (6). When the height of the nearly saturated ammonium sulfate solution level (22) in the adsorption cylinder (1) is 5 cm to 15 cm lower than the liquid outlet (8), the liquid injection is completed, and the inlet of the liquid inlet pipe (5) is switched to be connected to the liquid outlet of the front-stage dilution-cooling unit (101); 2. Adsorption operation: Open the drain pipe valve (9), start the aeration air compressor (11) and open the aeration pipe valve (12), and inject air into the aeration part (30) through the aeration pipe (13). Air bubbles float up and enter the filter material part (29) through the bottom arc net (23) of the adsorption cylinder (1). The bubbles continue to float to the liquid surface and escape from the filter material and are discharged from the exhaust pipe (28); the liquid discharged from the dilution-cooling unit (101) flows into the tower through the water distribution pipe (6); in the adsorption cylinder (1), an adhesion saturated layer, a near-saturated layer, an unsaturated layer, a less-adsorbed layer and a non-adsorbed layer are formed from top to bottom in the height direction of the filter material layer; (3) Filter material discharge and filter bed movement: When the heavy component aggregates adhered to the surface of the top filter material cage ball (21) in the adsorption cylinder (1) reach adsorption saturation, the telescopic pusher (18) is started, and the telescopic rod (20) drives the push plate (19) to move downward, so that the filter material cage ball (21) in the push cylinder (2) moves downward, enters the adsorption cylinder (1) after passing through the bottom, and the filter material cage ball (21) in the adsorption cylinder (1) moves upward; due to the pushing effect between the filter material cage balls (21), as the push plate (19) on the push cylinder (2) moves downward, the adsorption saturation layer adhered to the surface of the adsorption cylinder (1) is gradually squeezed out and moved out through the filter material discharge port (4) with the side opening; all the liquid discharged from the liquid outlet (8) is returned to the ammonium sulfate device feed tank (104) for reuse; (4) Filling and adding filter material: When the telescopic push plate (19) moves down to the bottom of the push cylinder (2), the push plate (19) is quickly moved up to a position higher than the upper edge (17-1) of the filter material feed pipe (17), and new filter material is added from the filter material feed pipe (17). When the amount of filter material is equal to the upper edge (17-1) of the filter material feed pipe (17), the addition is stopped, and the telescopic pusher (18) drives the push plate (19) to move down again to push the filter material cage ball (21) in the push cylinder (2) toward the adsorption cylinder (1) and squeeze out the adsorption-saturated filter material cage ball (21) in the filter material portion (29), and discharge it through the filter material discharge port (4); (5) Solid-liquid separation of adsorbent filter media - filter media regeneration: The adsorbent saturated filter media cage balls (21) squeezed out from the adsorption cylinder (1) are sent to the centrifugal separation unit (102-2) for separation. The centrifugal speed is 3000-5000 rpm. Centrifugation for 10-20 minutes can effectively separate the heavy components of the adsorbent from the filter media. This process is also the process of filter media regeneration. If the centrifugal environment temperature is low, hot air is introduced to keep the material temperature in the centrifugal separation unit (102-2) at 30°C-60°C. The regenerated filter material is fed into the filter material feed pipe (17) of the push cylinder (2) through the filter material conveying unit (102-4) for recycling.

2. The method for continuously separating heavy oligomers precipitated from ammonium sulfate polymer wastewater produced by an acrylonitrile ammonium sulfate device according to claim 1, characterized in that: The diluent mentioned in (1) is water or the incoming material of the ammonium sulfate device - dilute ammonium sulfate liquid.

3. The method for continuously separating heavy oligomers precipitated from ammonium sulfate polymer wastewater produced by an acrylonitrile ammonium sulfate device according to claim 1, characterized in that: The filter material filled inside the filter cage ball (21) described in (2) is a particle formed by a hard polymer material, and the particle volume is 1cm 3 ~5cm 3 The shape is spherical, cylindrical or blocky, and the surface and interior of the particles are hollowed out to form multiple channels; the filter material is made of plastic material, specifically polyethylene, polypropylene, polyvinyl chloride, chlorinated polyvinyl chloride or polyvinylidene fluoride, all of which are completed by injection molding, and the filter material density is less than 1g / cm 3 .

4. The method for continuously separating heavy oligomers precipitated from ammonium sulfate polymer wastewater produced by an acrylonitrile ammonium sulfate device according to claim 1, characterized in that: The centrifugal separation unit (102-2) described in (2) is a centrifuge.

5. The method for continuously separating heavy oligomers precipitated from ammonium sulfate polymer wastewater produced by an acrylonitrile ammonium sulfate device according to claim 1, characterized in that: The filter material conveying unit (102-4) described in (2) is a belt conveyor.

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