Phosphoric acid waste liquid purification and concentration full-membrane system and process

Abstract

The invention relates to the technical field of phosphoric acid waste liquid purification, and particularly discloses a phosphoric acid waste liquid purification and concentration full-membrane system and process, and the system comprises an ultrafiltration system, a nanofiltration system and a membrane distillation system which are arranged in sequence. According to the ultrafiltration system disclosed by the invention, the water inlet amount is adjusted at normal temperature, so that a certain pressure is reached, and suspended solid particles contained in the phosphoric acid waste liquid are removed through the ultrafiltration membrane assembly; polyvalent ions (such as aluminum ions, zinc ions and iron ions) contained in the phosphoric acid waste liquid are removed through the nanofiltration membrane assembly, the nanofiltration produced water is subjected to water quantity adjustment through the membrane distillation system to reach a certain pressure, the nanofiltration produced water is heated to 85 DEG C through the heat exchanger, and then the nanofiltration produced water passes through the membrane system; according to the phosphoric acid waste liquid purification and concentration device, phosphoric acid waste liquid is purified and concentrated, the automation degree is high, and the occupied area is small.

Description

Technical Field

[0001] The invention relates to the technical field of phosphoric acid waste liquid purification, in particular to a phosphoric acid waste liquid purification and concentration full-membrane system and process. Background Art

[0002] Phosphoric acid is a common chemical used in production processes across a wide range of sectors, including electronics, agriculture, and biopharmaceuticals. Consequently, significant amounts of phosphoric acid wastewater are generated annually, containing numerous suspended solids and metal ion impurities. In recent years, with increasing environmental protection requirements, the resource utilization of phosphorus-containing wastewater has gained increasing attention. This technology not only reduces environmental pollution but also enables the effective recycling of resources, possessing significant research significance and broad application prospects.

[0003] In the past, various technical means were commonly used to treat phosphoric acid wastewater. For filtering suspended solids, some methods used traditional physical filtration equipment to perform preliminary filtration of the wastewater through devices such as filters to intercept larger particles of solid impurities. For removing metal ion impurities, a common practice is to use chemical precipitation, adding specific chemical agents to the wastewater to precipitate and separate the metal ions. In addition, there is also the method of using ion exchange resins to remove metal ions by taking advantage of the resin's adsorption characteristics for different ions. Some processes also combine evaporation and concentration to evaporate water by heating, thereby increasing the concentration of phosphoric acid.

[0004] However, these existing technologies have obvious drawbacks. Traditional physical filtration is difficult to completely remove tiny suspended solids, which limits the purity of the treated phosphoric acid. Chemical precipitation methods produce large amounts of chemical sludge, which not only increases the difficulty and cost of subsequent treatment but also may introduce new impurities. The use of ion exchange resins requires frequent regeneration, which is complex and costly. The evaporation and concentration process consumes a lot of energy, resulting in a significant increase in the cost of recovering phosphoric acid.

[0005] U.S. Patent Publication No. US06241888B1 discloses a method for controlling phosphorus concentration in a biological wastewater treatment plant. The method comprises aerating wastewater in an activation tank in the presence of activated sludge, and adding phosphorus at a controlled concentration to influence the properties of the activated sludge. The method includes measuring the phosphorus concentration in the activated sludge to control the phosphorus addition, and controlling the phosphorus addition in such a manner that the phosphorus concentration in the activated sludge is greater than or equal to a lower limit and less than or equal to an upper limit. The method according to the present invention can optimize the discharge value of biological wastewater purification equipment and better comply with the discharge value limits of wastewater purification equipment stipulated by the authorities than is currently possible. However, this method for controlling phosphorus concentration in a biological wastewater treatment plant primarily increases the phosphorus concentration by adding phosphorus, and does not purify the phosphorus content in the wastewater.

[0006] A nucleotide solution purification and concentration system based on scroll ultrafiltration and nanofiltration technology is disclosed in the Chinese patent document with publication number CN212881404U. The nucleotide solution purification and concentration system based on scroll ultrafiltration and nanofiltration technology includes an ultrafiltration stock liquid tank, an ultrafiltration feed pump, a first security filter, a first circulation pump, an ultrafiltration membrane, an organic matter tank, a first nanofiltration stock liquid tank, a first nanofiltration feed pump, a second security filter, a second circulation pump, a first nanofiltration membrane, a second nanofiltration stock liquid tank, a second nanofiltration feed pump, a third security filter, a third circulation pump, a second nanofiltration membrane, a permeation The ultrafiltration tank and the finished product tank, the discharge port of the ultrafiltration raw liquid tank is connected to the inlet end of the ultrafiltration feed pump through a conduit, the outlet end of the ultrafiltration feed pump is connected to the feed port of the first security filter through a conduit, and the discharge port of the first security filter is connected to the inlet end of the first circulation pump through a conduit, thereby achieving improvements in the nucleotide hydrolysis rate and product yield, and is relatively easy to separate during the separation process, and has certain use value and promotion value. However, the nucleotide solution purification and concentration system based on scroll ultrafiltration and nanofiltration technology only uses nanofiltration technology for purification, and the upper limit of the purification concentration is relatively low.

[0007] A waste liquid recovery device for electrode foil is disclosed in the Chinese patent document with the announcement number CN210885551U. The waste liquid recovery device for electrode foil includes: a raw liquid water tank, a booster pump, a safety filter, a high-pressure pump, a nanofiltration membrane tank, and a water production tank; wherein the raw liquid water tank is connected to the booster pump to boost the raw liquid flowing through the booster pump in the raw liquid water tank; the booster pump is connected to the safety filter to filter the pressurized raw liquid through the safety filter; the safety filter is connected to the high-pressure pump to process the filtered raw liquid through the high-pressure pump; the high-pressure pump is connected to the nanofiltration membrane tank to perform reverse osmosis treatment on the raw liquid processed by the high-pressure pump through the nanofiltration membrane; the nanofiltration membrane tank is connected to the water production tank to flow the phosphoric acid solution that meets the preset standards after the reverse osmosis treatment into the water production tank. This solution can recover the phosphoric acid solution in the waste liquid of the electrode foil, so that the phosphoric acid solution can be reused, saving the cost of phosphoric acid reagents. In addition, the concentration of other impurities in the waste liquid is increased, and the volume occupied is reduced, saving processing costs. However, the waste liquid recovery device of the electrode foil adopts a single filtration method to recover the waste liquid, and the purification effect is poor.

[0008] A membrane distillation system for desulfurization wastewater concentration treatment disclosed in Chinese patent document with publication number CN204981458U provides a membrane distillation system for desulfurization wastewater concentration treatment with the characteristics of simple structure, easy installation and maintenance, safe operation, small footprint, low operating cost, and full utilization of low-temperature waste heat resources. The system includes a desulfurization wastewater storage tank, a sand filter, a safety filter, an ultrafiltration membrane tank, an ultrafiltration water production tank, a plate preheater and a membrane distillation component connected in sequence; the water production side outlet of the membrane distillation component is connected to the membrane distillation water production tank, the concentrated water side outlet of the membrane distillation component is connected to the membrane distillation concentrated water tank, and the gas outlet of the membrane distillation component is connected to the atmosphere, but the membrane components of the membrane distillation system for desulfurization wastewater concentration treatment are inconvenient to replace and clean.

[0009] In order to solve the above-mentioned deficiencies in the prior art, it is worthwhile to provide a full-membrane system and process for purifying and concentrating phosphoric acid waste liquid. Summary of the Invention

[0010] The purpose of the present invention is to overcome the disadvantage of poor single-layer filtration effect and provide a full-membrane system and process for purifying and concentrating phosphoric acid waste liquid, which realizes the technical effect of freely adding or reducing the number of membrane components to achieve different required concentrations.

[0011] The purpose of the present invention is achieved through the following technical solutions:

[0012] A full-membrane system for purifying and concentrating phosphoric acid waste liquid comprises an ultrafiltration system, a nanofiltration system, and a membrane distillation system arranged in sequence. The ultrafiltration system comprises an ultrafiltration raw water tank, an ultrafiltration booster pump connected to a water outlet of the ultrafiltration raw water tank, an ultrafiltration filter connected to a water outlet of the ultrafiltration booster pump, an ultrafiltration circulation pump connected to a water outlet of the ultrafiltration filter, an ultrafiltration membrane box connected to a water outlet of the ultrafiltration circulation pump, and an ultrafiltration produced water tank connected to a produced water outlet of the ultrafiltration membrane box. The water outlet of the ultrafiltration produced water tank is connected to the nanofiltration system, and the pure water outlet of the ultrafiltration membrane box is connected to an external water tank. The ultrafiltration system removes suspended solid particles contained in the phosphoric acid waste liquid through the ultrafiltration membrane assembly at room temperature by adjusting the water inlet to achieve a certain pressure.

[0013] The nanofiltration system includes a nanofiltration raw water tank connected to the water outlet of the ultrafiltration water production tank, a nanofiltration booster pump connected to the water outlet of the nanofiltration raw water tank, a nanofiltration filter connected to the water outlet of the nanofiltration booster pump, a nanofiltration high-pressure pump connected to the water outlet of the nanofiltration filter, a nanofiltration membrane box connected to the water outlet of the nanofiltration high-pressure pump, and a nanofiltration water production tank connected to the water outlet of the nanofiltration membrane box. The water outlet of the nanofiltration water production tank is connected to the membrane distillation system, and the pure water outlet of the nanofiltration membrane box is connected to the external water discharge tank. The nanofiltration system removes polyvalent ions (such as aluminum ions, zinc ions, and iron ions) contained in the phosphoric acid waste liquid through the nanofiltration membrane assembly by adjusting the water inlet at room temperature to achieve a certain pressure;

[0014] The membrane distillation system includes a membrane distillation raw water tank connected to the water outlet of the nanofiltration water production tank, a first heat exchanger connected to the water outlet of the membrane distillation raw water tank, a second heat exchanger connected to the water outlet of the first heat exchanger, a membrane distillation tank connected to the water outlet of the second heat exchanger, a condenser connected to the steam outlet of the first heat exchanger, and a cold water tower circulatedly connected to the condenser. The membrane distillation system adjusts the water volume of the nanofiltration water to a certain pressure, heats the nanofiltration water to 85°C through the heat exchanger, and then passes through the membrane system. The generated steam is condensed into condensed water through the condenser and enters the condensed water tank, and the phosphoric acid is refluxed to the raw water tank.

[0015] Preferably, the membrane distillation tank includes a membrane distillation tank body, a steam input port arranged on one side of the membrane distillation tank body, a steam exhaust port arranged on the other side of the membrane distillation tank body, a pure water outlet arranged on the top of the membrane distillation tank body, a produced water inlet arranged on one side of the bottom of the membrane distillation tank body, a produced water outlet arranged on the other side of the bottom of the membrane distillation tank body, a distillation component arranged inside the membrane distillation tank body, and a membrane cleaning component arranged on the top of the membrane distillation tank body, which work together to improve the purification and concentration effect of phosphoric acid waste liquid.

[0016] Preferably, the distillation assembly includes several heating tubes fixedly connected to the inside of the membrane distillation tank, an extraction pump arranged at the bottom of the heating tube, and a reflux pipe arranged at the top of the heating tube, which effectively concentrates the phosphoric acid waste liquid and cooperates with the ultrafiltration part and the nanofiltration part to achieve the purpose of purifying and concentrating the phosphoric acid waste liquid.

[0017] Preferably, the bottom of the heating tube is connected to the extraction pump, the top of the heating tube is bent toward the center and connected, the lower end of the heating tube is connected to the reflux pipe, and the upper end of the heating tube is connected to the bottom of the pure water outlet. The upper end of the heating tube is connected to the bottom of the pure water outlet to facilitate the discharge of the separated pure water, which helps to improve the working efficiency and effect of the membrane distillation link in the purification and concentration process of phosphoric acid waste liquid.

[0018] Preferably, the heating tubes are distributed in a multi-layer ring shape inside the membrane distillation tank body, and the minimum spacing between the heating tubes is greater than one millimeter. By arranging the heating tubes so that the gaps between the heating tubes are S-shaped, the hot steam flows in an S-shape inside the membrane distillation tank body, extending the flow time of the hot steam in the membrane distillation tank body, allowing the hot steam to fully heat the heating tubes and the internal phosphoric acid liquid, thereby improving the heat utilization rate of the hot steam.

[0019] Preferably, the material of the heating tube is duplex stainless steel or nickel-based alloy, and the inner surface of the heating tube is coated with a corrosion-resistant coating. Applying the corrosion-resistant coating on the inside of the heating tube can protect the inner wall of the heating tube, reduce the damage of the phosphoric acid liquid to the inner wall of the heating tube, and avoid the situation where the highly corrosive phosphoric acid liquid after purification damages the heating tube.

[0020] Preferably, the cross-section of the heating tube is rhombus-shaped, and the edges and corners of the heating tube are rounded.

[0021] Preferably, the distance between the bottom of the extraction pump and the bottom of the inner wall of the membrane distillation tank is less than five centimeters, which is beneficial to improving the efficiency and quality of phosphoric acid concentration.

[0022] Preferably, the membrane cleaning assembly includes a servo motor fixedly connected to one side of the top of the membrane distillation tank body, and two steam filtration membranes fixedly connected to the output end of the servo motor.

[0023] Preferably, the two steam filter membranes are located on the outside of the steam outlet and the pure water outlet respectively, so as to realize the replacement and automatic cleaning of the two steam filter membranes, extend the service life of the steam filter membranes, reduce the frequency of staff cleaning and replacing the steam filter membranes, and reduce manpower investment.

[0024] Preferably, the membrane cleaning assembly further comprises a pure water discharge pipe provided at the top of the pure water outlet and a steam discharge pipe provided outside the steam discharge outlet;

[0025] Preferably, the end of the pure water discharge pipe is connected to the external water discharge tank, and the end of the steam discharge pipe is connected to the first heat exchanger, so as to fully utilize the heat of the hot steam, and the fully utilized hot steam is then returned to the condenser for condensation recovery, thereby reducing the water consumption of the equipment.

[0026] Preferably, the shape of the gap between the pure water discharge pipe and the pure water outlet is adapted to the shape of the steam filter membrane, and the shape of the gap between the steam discharge outlet and the steam discharge pipe is adapted to the shape of the steam filter membrane. After rotation, the steam filter membrane can perfectly enter the gap between the two to complete the assembly, so that the steam filter membrane can maintain good sealing during the process of filtering or self-cleaning steam.

[0027] Preferably, the ends of the pure water discharge pipe, pure water outlet, steam discharge outlet and steam discharge pipe are all arc-shaped, and the docking interface of the steam filter membrane is arc-shaped. The arcs of the docking interfaces of the pure water discharge pipe, pure water outlet, steam discharge outlet, steam discharge pipe and steam filter membrane all take the output end shaft of the servo motor as the center of the circle. The steam filter membrane can be docked with the pipeline in a relatively fitting manner during rotation, avoiding the situation where the straight-mouth pipeline hinders the rotation of the steam filter membrane or the docking is not tight.

[0028] Preferably, the condenser includes a condenser tank body, a cooling water inlet opened at one end of the condenser tank body, a steam recovery port opened at the top of the other end of the condenser tank body, a condensed water outlet opened at the bottom of the other end of the condenser tank body, a cooling water outlet opened at the top of the condenser tank body, a condensation assembly arranged inside the condenser tank body, and a support assembly arranged at the bottom of the condenser tank body. The support assembly facilitates the installation and movement of the condenser, and as a whole ensures the smooth progress of the process of cooling the steam into water in the membrane distillation part, which is conducive to the stable operation of the full membrane system for purification and concentration of phosphoric acid waste liquid.

[0029] Preferably, the condensation assembly includes a plurality of condensation tubes fixedly connected to the inside of the condenser tank, a plurality of baffles arranged on the outside of the condensation tubes, and a partition plate arranged at the end of the condensation tubes. The condensation assembly consisting of the condensation tubes, baffles and partition plates is arranged in the condenser, which can effectively improve the condensation effect of the steam and enhance the device's treatment capacity and efficiency for phosphoric acid waste liquid.

[0030] Preferably, the condenser tubes are all U-shaped, and the partition plate separates the spaces at both ends of the condenser tubes, thereby increasing the steam flow path and time, allowing the steam to fully contact the cooling water, and improving the condensation efficiency.

[0031] Preferably, the baffles are evenly spaced inside the condenser tank, and notches are provided at the top or bottom of the baffles. The notches are staggered on the baffles to increase the flow distance of cooling water in the condenser tank and improve the heat exchange efficiency of the condenser.

[0032] Preferably, the edges of the deflectors are provided with arc-shaped plates, so that the cooling water can flow more smoothly during the deflection process, thereby reducing the noise generated during the deflection process of the cooling water.

[0033] Preferably, the support assembly includes a plurality of support legs fixedly connected to the bottom of the condenser tank body, and movable wheels rotatably connected to both sides of the support legs. The support legs are isosceles trapezoids, which support the condenser and improve the stability of the condenser.

[0034] Preferably, the bottom height of the supporting legs is higher than the bottom height of the moving wheels, and pull rods are provided on both sides of the condenser tank.

[0035] Preferably, the cooling water inlet and the cooling water outlet are communicated with the water outlet and the water inlet of the cooling tower respectively, and the steam recovery port is communicated with the steam outlet of the first heat exchanger.

[0036] Preferably, the condensed water outlet is connected to a condensed water tank, the top gas phase space of the condensed water tank is connected to a vacuum pump, and the bottom water phase space of the condensed water tank is connected to a self-priming pump. The vacuum pump ensures a stable negative pressure environment in the system by sucking non-condensable gases (such as air and volatile organic compounds) in the condensed water tank, lowers the boiling point to improve evaporation efficiency, and the self-priming pump can efficiently discharge condensed water under negative pressure through a special structure (such as a gas-liquid separation chamber) to avoid the liquid level in the tank being too high and affecting the vacuum degree. The flow rate of the self-priming pump of the membrane distillation system is higher than the flow rate of the water inlet pump so that the condensed water in the condensed water tank can be discharged in time.

[0037] Preferably, the cooling water tower includes a cooling water tower body, a cooling water tower water outlet arranged on one side of the bottom of the cooling water tower body, a cooling water tower air inlet arranged on the other side of the bottom of the cooling water tower body, a spray assembly arranged on the upper half of the inner wall of the cooling water tower body, a cooling assembly arranged on the lower half of the inner wall of the cooling water tower body, and a heat dissipation assembly arranged on the top of the cooling water tower body.

[0038] Preferably, the spray assembly includes an input pipe fixedly connected to the upper half of the inner wall of the cooling water tower body, a plurality of water distribution pipes fixedly connected to the input pipe, and a plurality of spiral nozzles rotatably connected to the bottom of the water distribution pipes.

[0039] Preferably, the water delivery pipe is connected to the condensed water outlet, the water distribution pipes are connected to the water delivery pipe, the spiral nozzles are connected to the water distribution pipes, and the spiral nozzles are provided with a plurality of water outlet holes;

[0040] Preferably, a plurality of drive motors are fixedly connected to the top of the water distribution pipe, and the output ends of the drive motors are respectively fixedly connected to the top rotating shafts of the spiral nozzles. The rotating spiral nozzles spray water to form a water curtain with a larger coverage area, and improve the uniformity of the condensed water spraying, so that the water curtain is fully in contact with the cold air, thereby improving the heat exchange efficiency between the condensed water and the cold air, and accelerating the cooling efficiency of the condensed water.

[0041] Preferably, the cooling component includes a heat dissipation filler fixedly connected to the lower half of the inner wall of the cooling tower body, and an injection pipe fixedly connected below the heat dissipation filler. The injection pipe helps to evenly disperse the gas, enhance the heat exchange effect with water, and cooperate with the heat dissipation filler to further improve the cooling efficiency.

[0042] Preferably, the jet pipe is a vortex line, one end of the jet pipe is connected to the air inlet of the cooling tower, the end of the air inlet of the cooling tower is connected to a fan, and a plurality of air outlet holes are opened on the top of the jet pipe. The filler disperses the water flow into a thin film or fine water droplets through its complex geometric structure (such as corrugated plate, honeycomb or grid design), significantly increasing the contact area between water and air, promoting heat exchange and evaporative heat dissipation, and the filler layer can slow down the water flow rate.

[0043] Preferably, the heat dissipation assembly includes exhaust pipes arranged on both sides of the top of the cooling tower body, a heat dissipation fan arranged inside the exhaust pipe, and a water eliminator arranged inside the exhaust pipe.

[0044] Preferably, the drain pipe is bent to both sides respectively, and the dehydrator is located at the end of the drain pipe. The water collected by the dehydrator flows back to the cooling water tower body. Bending the end of the drain pipe can reduce the dust and garbage above from entering the cooling water tower body through the drain pipe. The dehydrator reduces the drift loss of cooling water by physically intercepting and separating the water droplets entrained in the air flow, thereby improving the utilization rate of cooling water and reducing the water consumption of the equipment.

[0045] Preferably, a plurality of V-shaped plates are fixedly connected to the top of the inner wall of the cooling water tower body, and the height of the V-shaped plates gradually decreases from the middle to the two ends. The V-shaped plates are evenly distributed inside the cooling water tower body, and the V-shaped plates are located above the spray assembly.

[0046] Preferably, the condensed water of the membrane distillation system is returned to the ultrafiltration membrane raw water tank to dilute the feed phosphoric acid and adjust its concentration, thereby saving water.

[0047] Preferably, the steam generated by the membrane distillation system exchanges heat with the nanofiltration water, preheating the nanofiltration water before entering the membrane distillation system, and at the same time reducing the temperature of the steam, which helps to improve the subsequent concentration efficiency, while reducing the steam temperature and saving energy consumption of the membrane distillation system.

[0048] Preferably, the membrane distillation system is arranged in two sections according to the different concentrations. The first section concentrates the phosphoric acid to 60%, and the second section concentrates the phosphoric acid to more than 60%. This can achieve more accurate and efficient phosphoric acid concentration and meet the use requirements of different concentrations of phosphoric acid.

[0049] Preferably, the ultrafiltration system, nanofiltration system and membrane distillation system are all equipped with monitoring devices for various indicators such as flow rate, temperature, pressure, conductivity and pH, so as to perform online monitoring of various parameters of the concentrated full membrane system, provide timely feedback on the system operation status and ensure the stability of the process;

[0050] Preferably, the ultrafiltration system and the nanofiltration system each have a set of independent cleaning systems.

[0051] Preferably, the ultrafiltration membrane box includes an ultrafiltration membrane box body, a transmission screw rotatably connected to the four corners of the inner wall of the ultrafiltration box body, a sealing mechanism threadedly connected to the transmission screw, a connecting rod opening and closing mechanism arranged at one end of the ultrafiltration membrane box body, and an ultrafiltration membrane arranged between the sealing mechanisms.

[0052] Preferably, the sealing mechanism includes several sealing plates slidably connected to the inside of the ultrafiltration membrane box, the four corners of the sealing plates are respectively threadedly connected to the transmission screw, the sealing plates are grouped into two, and the ultrafiltration membrane is respectively arranged between the two sealing plates in the same group. The thread directions on the two sealing plates in the same group are opposite, thereby realizing rapid assembly and removal of the ultrafiltration membrane inside the ultrafiltration membrane box and improving the sealing and stability of the ultrafiltration membrane assembly.

[0053] Preferably, the shape of the sealing plate is adapted to the cross-sectional shape of the inner wall of the ultrafiltration membrane box, the friction coefficient between the sealing plate and the inner wall of the ultrafiltration membrane box is less than 0.5, and a sealing ring is provided at the contact position between the sealing plate and the ultrafiltration membrane. The sealing plate can slide smoothly inside the ultrafiltration membrane box to complete the clamping or loosening of the ultrafiltration membrane.

[0054] Preferably, a telescopic sealing sleeve is fixedly connected between two adjacent sealing plates that are not in the same group. The cross-sectional shape of the telescopic sealing sleeve is adapted to the shape of the sealing plate, and the telescopic stroke of the telescopic sealing sleeve is twice the sliding stroke of the sealing plate, thereby avoiding the situation where phosphoric acid waste liquid accumulates between the gaps between adjacent sealing plates without sufficient ultrafiltration treatment.

[0055] Preferably, the connecting rod opening and closing mechanism includes three groups of transmission connecting rods respectively connected to the transmission screw, a telescopic cylinder rotatably connected to one end of the ultrafiltration membrane box, and a connecting rod provided between the end of the transmission screw and the output end of the telescopic cylinder;

[0056] A group of transmission connecting rods consists of three transmission rods, the ends of which are rotatably connected to two transmission screws. The longest transmission rod length of the transmission connecting rod is equal to the distance between two adjacent transmission screws. The three transmission rods of a group of transmission connecting rods form an equilateral quadrilateral, so that one telescopic cylinder controls the rotation of the four transmission screws, and then one telescopic cylinder controls the opening and closing of all sealing components, thereby realizing rapid assembly, clamping and limiting of the ultrafiltration membrane.

[0057] Preferably, an ultrafiltration water inlet pipe is provided at the bottom of the ultrafiltration membrane box body, and the water distribution pipes of the ultrafiltration water inlet pipe are respectively located below each sealing mechanism; a filtrate collecting pipe is provided on one side of the ultrafiltration box body, and the ends of the filtrate collecting pipe are respectively connected to each ultrafiltration membrane; an ultrafiltration water outlet pipe is provided on the other side of the ultrafiltration membrane box body, and the ultrafiltration water outlet pipe is connected to the ultrafiltration membrane box body.

[0058] The full membrane process for purifying and concentrating phosphoric acid waste liquid includes the following steps:

[0059] The phosphoric acid waste liquid enters the ultrafiltration filter through the ultrafiltration booster pump from the ultrafiltration raw water tank, and the ultrafiltration filter removes impurities such as particulate matter in the liquid to prevent it from entering the circulation pump and ultrafiltration membrane assembly;

[0060] After the water exits the ultrafiltration filter, it enters the ultrafiltration circulation pump, which pressurizes it again and then enters the ultrafiltration membrane box. Under high pressure, the produced water enters the ultrafiltration water tank through the produced water pipeline, and the concentrated water carries the filtered solid suspended matter and is discharged to the external drainage tank.

[0061] The ultrafiltration produced water enters the nanofiltration raw water tank through the booster pump, and the nanofiltration raw water enters the nanofiltration membrane box from the nanofiltration raw water tank. The concentrated water carries the filtered metal ions and is discharged to the external drainage box. The produced water is transported from the nanofiltration produced water tank to the membrane distillation raw water tank;

[0062] The membrane distillation raw water tank transports the membrane distillation raw water, which is heated to 85°C through the first heat exchanger and the second heat exchanger in turn. The heated membrane distillation raw water is then transported into the membrane distillation tank for membrane distillation treatment.

[0063] The water produced after the membrane distillation tank is distilled is the concentrated product of phosphoric acid, and the pure water produced by the membrane distillation tank flows back to the membrane distillation raw water tank;

[0064] The steam discharged from the membrane distillation tank is condensed into water through the condenser and enters the condensate tank. The condenser is connected to the cooling tower, which provides circulating cold water for the condenser. This system purifies and concentrates phosphoric acid waste liquid. It has a high degree of automation and a small footprint. At the same time, the number of membrane modules can be freely increased or decreased to achieve different required concentrations. Phosphoric acid of various concentration levels has different uses. Real-time online data monitoring can promptly reflect the operating status of the entire system and ensure process stability.

[0065] Preferably, the flow rate of the self-priming pump of the membrane distillation system is higher than the flow rate of the water inlet pump, so that the condensed water in the condensed water tank can be discharged in time.

[0066] Positive beneficial effects:

[0067] 1. The ultrafiltration system removes suspended solid particles in the phosphoric acid waste liquid through the ultrafiltration membrane assembly by adjusting the water inlet at room temperature to reach a certain pressure. The nanofiltration system removes multivalent ions (such as aluminum ions, zinc ions, and iron ions) in the phosphoric acid waste liquid through the nanofiltration membrane assembly by adjusting the water inlet at room temperature to reach a certain pressure. The membrane distillation system adjusts the nanofiltration water volume to a certain pressure, heats the nanofiltration water to 85°C through a heat exchanger, and then passes through the membrane system. The steam generated is condensed into condensed water through the condenser and enters the condensation water tank, and the phosphoric acid returns to the raw water tank.

[0068] 2. A servo motor-driven steam filter membrane is set on the top of the membrane distillation tank. The two steam filter membranes are located on the outside of the steam outlet and the pure water outlet respectively. After a period of purification, the servo motor is started to rotate the two steam filter membranes to replace positions. The clean steam filter membrane performs filtering and purification work, while the steam filter membrane that has been filtering for a period of time is replaced to the outside of the steam outlet for steam self-cleaning, thereby realizing the replacement and automatic cleaning of the two steam filter membranes.

[0069] 3. The pure water discharge pipe inputs the pure water generated by the membrane distillation tank into the external drainage box, and is discharged to the external water body after purification, or recycled and returned to the water-using equipment for repeated use, thereby reducing the water consumption of the equipment. The steam discharge pipe is connected to the first heat exchanger, and the heat of the hot steam is used to perform the initial heating of the phosphate raw water, making full use of the heat of the hot steam. The fully utilized hot steam is then returned to the condenser for condensation recovery, thereby reducing the water consumption of the equipment.

[0070] 4. A sealing plate controlled by a transmission screw thread is set inside the ultrafiltration membrane box. After the ultrafiltration membrane is assembled into the ultrafiltration membrane box, the transmission screw is rotated. Through the thread transmission of the transmission screw and the sealing plate, the two sealing plates in the same group move toward each other to clamp the ultrafiltration membrane, thereby achieving the limitation of the ultrafiltration membrane, improving the stability of the ultrafiltration membrane assembly, and improving the sealing between the ultrafiltration membranes. When the ultrafiltration membrane needs to be removed, the transmission screw is rotated in the opposite direction to separate the two sealing plates in the same group, thereby realizing the rapid assembly and removal of the ultrafiltration membrane inside the ultrafiltration membrane box, and improving the sealing and stability of the ultrafiltration membrane assembly.

[0071] 5. It is used to purify and concentrate phosphoric acid waste liquid. It has a high degree of automation and occupies a small area. At the same time, the number of membrane components can be freely added or reduced to achieve the required concentration. Phosphoric acid of various concentration levels has different uses.

[0072] 6. Real-time online data monitoring can promptly reflect the operating status of the entire system and ensure the stability of the process.

[0073] 7. Preheating the nanofiltration water before entering the membrane distillation system and reducing the temperature of the steam will help improve the subsequent concentration efficiency, while reducing the steam temperature and saving energy consumption of the membrane distillation system. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] Figure 1 Schematic diagram of the structure of the ultrafiltration system and nanofiltration system of the present invention;

[0075] Figure 2 Schematic diagram of the structure of the membrane distillation system of the present invention;

[0076] Figure 3 It is a structural schematic diagram of the membrane distillation tank of the present invention;

[0077] Figure 4 Schematic diagram of the front cross-sectional structure of the membrane distillation tank of the present invention;

[0078] Figure 5 For the present invention Figure 4 Schematic diagram of the enlarged structure at A in the middle;

[0079] Figure 6 For the present invention Figure 4 Schematic diagram of the enlarged structure at B in the middle;

[0080] Figure 7 Schematic diagram of the top cross-sectional structure of the membrane distillation tank of the present invention;

[0081] Figure 8 This is a schematic structural diagram of the membrane distillation tank of the present invention in a disassembled state;

[0082] Figure 9 For the present invention Figure 8 Schematic diagram of the enlarged structure at C in the middle;

[0083] Figure 10 Schematic diagram of the cross-sectional structure of the membrane distillation tank of the present invention in a disassembled state;

[0084] Figure 11 It is a structural schematic diagram of the condenser of the present invention;

[0085] Figure 12 Schematic diagram of the cross-sectional structure of the condenser of the present invention;

[0086] Figure 13 For the present invention Figure 12 Schematic diagram of the enlarged structure at D in the middle;

[0087] Figure 14 It is a rear structural schematic diagram of the condenser of the present invention;

[0088] Figure 15 For the present invention Figure 14 Schematic diagram of the enlarged structure at E in the middle;

[0089] Figure 16 It is a structural schematic diagram of the condensation component of the present invention;

[0090] Figure 17 Schematic diagram of the cross-sectional structure of the condensing component of the present invention;

[0091] Figure 18 For the present invention Figure 17 Schematic diagram of the enlarged structure at F in the middle;

[0092] Figure 19 It is a structural schematic diagram of the cooling tower of the present invention;

[0093] Figure 20It is a schematic diagram of the front cross-sectional structure of the cooling tower of the present invention;

[0094] Figure 21 For the present invention Figure 20 Schematic diagram of the enlarged structure at G in the middle;

[0095] Figure 22 For the present invention Figure 20 Schematic diagram of the enlarged structure at H in the middle;

[0096] Figure 23 It is a schematic diagram of the side cross-sectional structure of the present invention;

[0097] Figure 24 For the present invention Figure 23 Schematic diagram of the enlarged structure at I in the middle;

[0098] Figure 25 A schematic diagram of the structure of the ultrafiltration box of the present invention;

[0099] Figure 26 For the present invention Figure 25 Schematic diagram of the enlarged structure at J in the middle;

[0100] Figure 27 A schematic side view of the structure of the ultrafiltration box of the present invention;

[0101] Figure 28 A schematic cross-sectional view of the ultrafiltration box of the present invention;

[0102] Figure 29 For the present invention Figure 28 Schematic diagram of the enlarged structure at K in the middle;

[0103] Figure 30 For the present invention Figure 28 Schematic diagram of the enlarged structure at L in the middle;

[0104] Figure 31 A schematic structural diagram of the sealing mechanism and the connecting rod opening and closing mechanism of the present invention;

[0105] Figure 32 The present invention is a schematic diagram of the front side cross-sectional structure of the sealing mechanism and the connecting rod opening and closing mechanism;

[0106] Figure 33 For the present invention Figure 32 Schematic diagram of the enlarged structure at M;

[0107] Figure 34 A schematic diagram of the center cross-sectional structure of the sealing mechanism and the connecting rod opening and closing mechanism of the present invention;

[0108] Figure 35 Schematic diagram of the structure of the ultrafiltration membrane separation state of the present invention;

[0109] Figure 36is a process flow chart of the ultrafiltration system of the present invention;

[0110] Figure 37 This is a process flow chart of the nanofiltration system of the present invention;

[0111] Figure 38 1 is a process flow chart of the membrane distillation system of the present invention.

[0112] In the figure: 1000 - ultrafiltration system, 1100 - ultrafiltration raw water tank, 1200 - ultrafiltration booster pump, 1300 - ultrafiltration filter, 1400 - ultrafiltration circulation pump, 1500 - ultrafiltration membrane box, 1501 - ultrafiltration membrane box body, 1502 - transmission screw, 1503 - ultrafiltration membrane, 1504 - sealing plate, 1505 - telescopic sealing sleeve, 1506 - transmission connecting rod, 1507 - telescopic cylinder, 1508 - connecting rod, 1509 - ultrafiltration water inlet pipe, 1510 - filtrate collection pipe, 1511 - ultrafiltration water outlet pipe, 1600 - ultrafiltration water tank;

[0113] 2000-nanofiltration system, 2100-nanofiltration raw water tank, 2200-nanofiltration booster pump, 2300-nanofiltration filter, 2400-nanofiltration high-pressure pump, 2500-nanofiltration membrane box, 2600-nanofiltration produced water tank;

[0114] 3000-membrane distillation system, 3100-membrane distillation raw water tank, 3200-first heat exchanger, 3300-second heat exchanger;

[0115] 3400 - membrane distillation tank, 3401 - membrane distillation tank body, 3402 - steam inlet, 3403 - steam outlet, 3404 - pure water outlet, 3405 - produced water inlet, 3406 - produced water outlet, 3407 - heating pipe, 3408 - extraction pump, 3409 - reflux pipe, 3410 - servo motor, 3411 - steam filter membrane, 3412 - pure water outlet pipe, 3413 - steam outlet pipe;

[0116] 3500 - condenser, 3501 - condenser tank, 3502 - cooling water inlet, 3503 - steam recovery port, 3504 - condensed water outlet, 3505 - cooling water outlet, 3506 - condenser pipe, 3507 - baffle, 3508 - partition plate, 3509 - curved plate, 3510 - support leg, 3511 - moving wheel, 3512 - pull rod;

[0117] 3600-cooling tower, 3601-cooling tower body, 3602-cooling tower water outlet, 3603-cooling tower air inlet, 3604-input pipe, 3605-water distribution pipe, 3606-spiral nozzle, 3607-drive motor, 3608-heat dissipation filler, 3609-jet pipe, 3610-exhaust pipe, 3611-cooling fan, 3612-water eliminator, 3613-V-plate. DETAILED DESCRIPTION

[0118] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0119] The full membrane system for purifying and concentrating phosphoric acid waste liquid includes an ultrafiltration system 1000, a nanofiltration system 2000, and a membrane distillation system 3000, which are arranged in sequence;

[0120] The membrane distillation system 3000 includes a membrane distillation raw water tank 3100 connected to the water outlet of the nanofiltration water production tank 2600 of the nanofiltration system 2000, a first heat exchanger 3200 connected to the water outlet of the membrane distillation raw water tank 3100, a second heat exchanger 3300 connected to the water outlet of the first heat exchanger 3200, a membrane distillation tank 3400 connected to the water outlet of the second heat exchanger 3300, a condenser 3500 connected to the steam outlet of the first heat exchanger 3200, and a cooling water tower 3600 in circular communication with the condenser 3500.

[0121] The membrane distillation tank 3400 includes a membrane distillation tank body 3401, a distillation assembly disposed inside the membrane distillation tank body 3401, and a membrane cleaning assembly disposed on the top of the membrane distillation tank body 3401;

[0122] The distillation assembly includes a plurality of heating tubes 3407 fixedly connected to the interior of the membrane distillation tank 3400, an extraction pump 3408 disposed at the bottom of the heating tubes 3407, and a reflux tube 3409 disposed at the top of the heating tubes 3407;

[0123] The membrane cleaning assembly includes a servo motor 3410 fixedly connected to one side of the top of the membrane distillation tank 3401 and two steam filter membranes 3411 fixedly connected to the output end of the servo motor 3410;

[0124] The condenser 3500 includes a condenser tank 3501 and a condensation assembly disposed inside the condenser tank 3501. The condensation assembly includes a plurality of condensation tubes 3506 fixedly connected to the interior of the condenser tank 3501, a plurality of baffles 3507 disposed outside the condensation tubes 3506, and a partition plate 3508 disposed at the end of the condensation tubes 3506.

[0125] The cooling water tower 3600 includes a cooling water tower body 3601 and a cooling component arranged on the lower half of the inner wall of the cooling water tower body 3601; the cooling component includes a heat dissipation filler 3608 fixedly connected to the lower half of the inner wall of the cooling water tower body 3601 and an injection pipe 3609 fixedly connected below the heat dissipation filler 3608.

[0126] The ultrafiltration system 1000 includes an ultrafiltration raw water tank 1100, an ultrafiltration booster pump 1200 connected to the water outlet of the ultrafiltration raw water tank 1100, an ultrafiltration filter 1300 connected to the water outlet of the ultrafiltration booster pump 1200, an ultrafiltration circulation pump 1400 connected to the water outlet of the ultrafiltration filter 1300, an ultrafiltration membrane tank 1500 connected to the water outlet of the ultrafiltration circulation pump 1400, and an ultrafiltration produced water tank 1600 connected to the produced water outlet of the ultrafiltration membrane tank 1500. The water outlet of the ultrafiltration produced water tank 1600 is connected to the nanofiltration system 2000, and the pure water outlet of the ultrafiltration membrane tank 1500 is connected to the external water tank.

[0127] The nanofiltration system 2000 includes a nanofiltration raw water tank 2100 connected to the water outlet of the ultrafiltration water production tank 1600, a nanofiltration booster pump 2200 connected to the water outlet of the nanofiltration raw water tank 2100, a nanofiltration filter 2300 connected to the water outlet of the nanofiltration booster pump 2200, a nanofiltration high-pressure pump 2400 connected to the water outlet of the nanofiltration filter 2300, a nanofiltration membrane tank 2500 connected to the water outlet of the nanofiltration high-pressure pump 2400, and a nanofiltration water production tank 2600 connected to the water production outlet of the nanofiltration membrane tank 2500. The water outlet of the nanofiltration water production tank 2600 is connected to the membrane distillation system 3000, and the pure water outlet of the nanofiltration membrane tank 2500 is connected to the external water drainage tank.

[0128] The membrane distillation tank 3400 includes a steam input port 3402 provided on one side of the membrane distillation tank body 3401, a steam exhaust port 3403 provided on the other side of the membrane distillation tank body 3401, a pure water outlet 3404 provided on the top of the membrane distillation tank body 3401, a produced water inlet 3405 provided on one side of the bottom of the membrane distillation tank body 3401, and a produced water outlet 3406 provided on the other side of the bottom of the membrane distillation tank body 3401.

[0129] Two steam filter membranes 3411 are located outside the steam outlet 3403 and the pure water outlet 3404 respectively;

[0130] The membrane cleaning assembly further includes a pure water discharge pipe 3412 disposed at the top of the pure water outlet 3404 and a steam discharge pipe 3413 disposed outside the steam discharge outlet 3403;

[0131] The end of the pure water discharge pipe 3412 is connected to the external water tank, and the end of the steam discharge pipe 3413 is connected to the first heat exchanger 3200;

[0132] The shape of the gap between the pure water discharge pipe 3412 and the pure water outlet 3404 matches the shape of the steam filter membrane 3411 , and the shape of the gap between the steam outlet 3403 and the steam discharge pipe 3413 matches the shape of the steam filter membrane 3411 .

[0133] The bottom of the heating tube 3407 is connected to the extraction pump 3408, the top of the heating tube 3407 is bent toward the center and connected, the bottom of the end of the heating tube 3407 is connected to the return pipe 3409, and the top of the end of the heating tube 3407 is connected to the bottom of the pure water outlet 3404;

[0134] The heating tubes 3407 are arranged in a multi-layered annular pattern inside the membrane distillation tank 3401, with the minimum spacing between the heating tubes 3407 being greater than one millimeter. The heating tubes 3407 are made of duplex stainless steel or nickel-based alloy, and the inner surface of the heating tubes 3407 is coated with a corrosion-resistant coating.

[0135] The cross-section of the heating tube 3407 is a diamond shape, and the edges and corners of the heating tube 3407 are rounded;

[0136] The distance between the bottom of the extraction pump 3408 and the bottom of the inner wall of the membrane distillation tank 3401 is less than five centimeters.

[0137] The condenser 3500 includes a cooling water inlet 3502 at one end of the condenser tank 3501, a steam recovery port 3503 at the top of the other end of the condenser tank 3501, a condensed water outlet 3504 at the bottom of the other end of the condenser tank 3501, a cooling water outlet 3505 at the top of the condenser tank 3501, and a support assembly disposed at the bottom of the condenser tank 3501.

[0138] The condenser tubes 3506 are all U-shaped, and the partition plate 3508 separates the spaces at both ends of the condenser tubes 3506;

[0139] The baffles 3507 are evenly spaced inside the condenser tank 3501. Notches are formed on the top or bottom of the baffles 3507. The notches are staggered on the baffles 3507.

[0140] Arc plates 3509 are provided at the edges of the deflector 3507.

[0141] The cooling tower 3600 includes a cooling tower water outlet 3602 provided on one side of the bottom of the cooling tower body 3601, a cooling tower air inlet 3603 provided on the other side of the bottom of the cooling tower body 3601, a spray assembly provided on the upper half of the inner wall of the cooling tower body 3601, and a heat dissipation assembly provided on the top of the cooling tower body 3601.

[0142] The spray assembly includes an input pipe 3604 fixedly connected to the upper half of the inner wall of the cooling tower body 3601, a plurality of water distribution pipes 3605 fixedly connected to the input pipe 3604, and a plurality of spiral nozzles 3606 rotatably connected to the bottom of the water distribution pipes 3605;

[0143] The water delivery pipe 3604 is connected to the condensate outlet 3504, the water distribution pipes 3605 are connected to the water delivery pipe 3604, and the spiral nozzles 3606 are connected to the water distribution pipe 3605. The spiral nozzles 3606 are provided with a plurality of water outlet holes.

[0144] A plurality of drive motors 3607 are fixedly connected to the top of the water distribution pipe 3605. The output ends of the drive motors 3607 are fixedly connected to the top rotating shafts of the spiral nozzles 3606.

[0145] The jet pipe 3609 is a vortex line. One end of the jet pipe 3609 is connected to the cooling tower air inlet 3603. The end of the cooling tower air inlet 3603 is connected to a fan. A plurality of air outlet holes are opened on the top of the jet pipe 3609.

[0146] The heat dissipation assembly includes exhaust pipes 3610 disposed on both sides of the top of the cooling tower 3601, a heat dissipation fan 3611 disposed inside the exhaust pipe 3610, and a water eliminator 3612 disposed inside the exhaust pipe 3610;

[0147] Exhaust pipe 3610 curves to either side, with dehumidifiers 3612 located at the ends. Water collected by dehumidifiers 3612 flows back into cooling tower 3601. Several V-shaped plates 3613 are fixedly attached to the top of the inner wall of cooling tower 3601. These plates gradually decrease in height from the middle to the ends, and are evenly spaced throughout cooling tower 3601. They are located above the spray assembly.

[0148] The full membrane process for purifying and concentrating phosphoric acid waste liquid includes the following steps:

[0149] The phosphoric acid waste liquid enters the ultrafiltration filter 1300 from the ultrafiltration raw water tank 1100 through the ultrafiltration booster pump 1200, and the ultrafiltration filter 1300 removes impurities such as particulate matter in the feed liquid;

[0150] After the water exits the ultrafiltration filter 1300, it enters the ultrafiltration circulation pump 1400, where it is pressurized again and then enters the ultrafiltration membrane tank 1500. Under high pressure, the produced water enters the ultrafiltration produced water tank 1600 through the produced water pipeline. The concentrated water, carrying the filtered suspended solids, is discharged to the external drainage tank.

[0151] The ultrafiltration produced water enters the nanofiltration raw water tank 2100 through the booster pump. The nanofiltration raw water enters the nanofiltration membrane tank 2500 from the nanofiltration raw water tank 2100. The concentrated water carries the filtered metal ions and is discharged to the external drainage tank. The produced water is transported from the nanofiltration produced water tank 2600 to the membrane distillation raw water tank 3100.

[0152] The membrane distillation raw water tank 3100 transports the membrane distillation raw water to be heated to 85° C. through the first heat exchanger 3200 and the second heat exchanger 3300 in sequence. The heated membrane distillation raw water is then transported to the membrane distillation tank 3400 for membrane distillation treatment.

[0153] The water produced after distillation in the membrane distillation tank 3400 is the concentrated phosphoric acid product, and the pure water produced in the membrane distillation tank 3400 flows back to the membrane distillation raw water tank 3100;

[0154] The steam discharged from the membrane distillation tank 3400 is condensed into water through the condenser 3500 and enters the condensation water tank. The condenser 3500 is connected to the cooling water tower 3600, and the cooling water tower 3600 provides circulating cold water for the condenser.

[0155] Example 1

[0156] like Figures 1 to 38 As shown, the full membrane system for purifying and concentrating phosphoric acid waste liquid includes an ultrafiltration system 1000, a nanofiltration system 2000, and a membrane distillation system 3000 arranged in sequence. The ultrafiltration system 1000 includes an ultrafiltration raw water tank 1100, an ultrafiltration booster pump 1200 connected to the outlet of the ultrafiltration raw water tank 1100, an ultrafiltration filter 1300 connected to the outlet of the ultrafiltration booster pump 1200, and an ultrafiltration circulation pump 140 connected to the outlet of the ultrafiltration filter 1300. 0. An ultrafiltration membrane box 1500 is connected to the water outlet of the ultrafiltration circulation pump 1400, and an ultrafiltration water production tank 1600 is connected to the water outlet of the ultrafiltration membrane box 1500. The water outlet of the ultrafiltration water production tank 1600 is connected to the nanofiltration system 2000, and the pure water outlet of the ultrafiltration membrane box 1500 is connected to the external water tank. The ultrafiltration system removes suspended solid particles contained in the phosphoric acid waste liquid through the ultrafiltration membrane assembly by adjusting the water inlet at room temperature to achieve a certain pressure.

[0157] The nanofiltration system 2000 includes a nanofiltration raw water tank 2100 connected to the outlet of the ultrafiltration produced water tank 1600, a nanofiltration booster pump 2200 connected to the outlet of the nanofiltration raw water tank 2100, a nanofiltration filter 2300 connected to the outlet of the nanofiltration booster pump 2200, a nanofiltration high-pressure pump 2400 connected to the outlet of the nanofiltration filter 2300, a nanofiltration membrane box 2500 connected to the outlet of the nanofiltration high-pressure pump 2400, and a nanofiltration produced water tank 2600 connected to the produced water outlet of the nanofiltration membrane box 2500. The outlet of the nanofiltration produced water tank 2600 is connected to the membrane distillation system 3000, and the pure water outlet of the nanofiltration membrane box 2500 is connected to the external water tank. The nanofiltration system removes polyvalent ions (such as aluminum ions, zinc ions, and iron ions) contained in the phosphoric acid waste liquid through the nanofiltration membrane assembly at room temperature by adjusting the water inlet to achieve a certain pressure.

[0158] The membrane distillation system 3000 includes a membrane distillation raw water tank 3100 connected to the water outlet of the nanofiltration water production tank 2600, a first heat exchanger 3200 connected to the water outlet of the membrane distillation raw water tank 3100, a second heat exchanger 3300 connected to the water outlet of the first heat exchanger 3200, a membrane distillation tank 3400 connected to the water outlet of the second heat exchanger 3300, a condenser 3500 connected to the steam outlet of the first heat exchanger 3200, and a cooling water tower 3600 in circulation communication with the condenser 3500; the membrane distillation system adjusts the water volume of the nanofiltration water to a certain pressure, heats the nanofiltration water to 85°C through the heat exchanger, and then passes through the membrane system. The generated steam is condensed into condensed water through the condenser and enters the condensed water tank, and the phosphoric acid flows back to the raw water tank.

[0159] like Figures 36 to 38 As shown, the present invention also discloses a full-membrane process for purifying and concentrating phosphoric acid waste liquid, which is applied to the above-mentioned full-membrane system for purifying and concentrating phosphoric acid waste liquid. The process includes the following steps:

[0160] Step 1: The phosphoric acid waste liquid enters the ultrafiltration filter 1300 from the ultrafiltration raw water tank 1100 through the ultrafiltration booster pump 1200. The ultrafiltration filter 1300 removes impurities such as particulate matter in the feed liquid and prevents it from entering the circulation pump and ultrafiltration membrane assembly;

[0161] Step 2: After the water exits the ultrafiltration filter 1300, it enters the ultrafiltration circulation pump 1400, which pressurizes it again before entering the ultrafiltration membrane box 1500. Under high pressure, the produced water enters the ultrafiltration produced water tank 1600 through the produced water pipeline. The concentrated water carries the filtered suspended solids and is discharged to the external drainage tank.

[0162] Step 3: The ultrafiltration produced water enters the nanofiltration raw water tank 2100 through the booster pump. The nanofiltration raw water enters the nanofiltration membrane box 2500 from the nanofiltration raw water tank 2100. The concentrated water carrying the filtered metal ions is discharged to the external drainage tank. The produced water is transported from the nanofiltration produced water tank 2600 to the membrane distillation raw water tank 3100.

[0163] Step 4: The membrane distillation raw water tank 3100 conveys the membrane distillation raw water to be heated to 85° C. through the first heat exchanger 3200 and the second heat exchanger 3300 in sequence. The heated membrane distillation raw water is then conveyed to the membrane distillation tank 3400 for membrane distillation treatment.

[0164] Step 5: The water produced after distillation in the membrane distillation tank 3400 is the concentrated phosphoric acid product, and the pure water produced in the membrane distillation tank 3400 flows back to the membrane distillation raw water tank 3100;

[0165] Step 6: The steam discharged from the membrane distillation tank 3400 is condensed into water through the condenser 3500 and enters the condensate tank. The condenser 3500 is connected to the cooling tower 3600, and the cooling tower 3600 provides circulating cold water for the condenser. The system purifies and concentrates phosphoric acid waste liquid, has a high degree of automation, and occupies a small area. At the same time, the number of membrane components can be freely increased or decreased to achieve the required different concentrations. Phosphoric acid of various concentration levels has different uses. Real-time online data monitoring can promptly reflect the operating status of the entire system to ensure the stability of the process.

[0166] like Figure 38 As shown in the figure, the self-priming pump flow rate of the membrane distillation system is higher than the water inlet pump flow rate, so that the condensed water in the condensed water tank can be discharged in time.

[0167] The implementation principle of this embodiment is as follows: the ultrafiltration system adjusts the water inlet at room temperature to achieve a certain pressure, thereby removing suspended solid particles contained in the phosphoric acid waste liquid through the ultrafiltration membrane assembly; the nanofiltration system adjusts the water inlet at room temperature to achieve a certain pressure, thereby removing multivalent ions (such as aluminum ions, zinc ions, and iron ions) contained in the phosphoric acid waste liquid through the nanofiltration membrane assembly; the membrane distillation system adjusts the water volume of the nanofiltration product to a certain pressure, heats the nanofiltration product water to 85°C through a heat exchanger, and then passes through the membrane system. The generated steam is condensed into condensed water through a condenser and enters the condensate tank, and the phosphoric acid is returned to the raw water tank.

[0168] Example 2

[0169] like Figures 3 to 10 As shown, the difference between this embodiment and the above embodiment is that the membrane distillation tank 3400 includes a membrane distillation tank body 3401, a steam input port 3402 arranged on one side of the membrane distillation tank body 3401, a steam exhaust port 3403 arranged on the other side of the membrane distillation tank body 3401, a pure water outlet 3404 arranged on the top of the membrane distillation tank body 3401, a water production inlet 3405 arranged on one side of the bottom of the membrane distillation tank body 3401, a water production outlet 3406 arranged on the other side of the bottom of the membrane distillation tank body 3401, and a membrane distillation tank 3401. The distillation component inside the body 3401 and the membrane cleaning component arranged on the top of the membrane distillation tank body 3401 first purify the phosphoric acid waste liquid through the ultrafiltration system and the nanofiltration system, and further concentrate it through the membrane distillation system; the steam input port, steam exhaust port, pure water outlet, produced water inlet and produced water outlet provided in the membrane distillation tank are convenient for steam and produced water to enter and exit the membrane distillation tank body; the internal distillation component can perform phosphoric acid concentration operation; the membrane cleaning component on the top can clean the membrane inside the membrane distillation tank, and the combined effect can improve the purification and concentration effect of the phosphoric acid waste liquid.

[0170] like Figures 4 to 10As shown, the distillation assembly includes several heating tubes 3407 fixedly connected to the inside of the membrane distillation tank 3400, an extraction pump 3408 arranged at the bottom of the heating tube 3407, and a reflux pipe 3409 arranged at the top of the heating tube 3407. The heating tubes, the extraction pump and the reflux pipe constitute a membrane distillation assembly, which can effectively concentrate the phosphoric acid waste liquid and cooperate with the ultrafiltration part and the nanofiltration part to achieve the purpose of purifying and concentrating the phosphoric acid waste liquid.

[0171] like Figures 4 to 7 As shown, the bottom of the heating tube 3407 is connected to the extraction pump 3408, the top of the heating tube 3407 is bent toward the center and connected, the bottom of the end of the heating tube 3407 is connected to the reflux pipe 3409, and the top of the end of the heating tube 3407 is connected to the bottom of the pure water outlet 3404. By arranging the heating tube 3407 with the extraction pump 3408 and the reflux pipe 3409 inside the membrane distillation tank body 3401, the extraction pump 3408 extracts the phosphoric acid liquid in the membrane distillation tank body 3401 into the heating tube 3407, so that the phosphoric acid liquid continues to flow in the heating tube 3407, and the hot steam entering the membrane distillation tank body 3401 irrigates the phosphoric acid liquid in the heating tube 3407. Heating converts the liquid water in the phosphoric acid liquid into water vapor and discharges it from the pure water outlet 3404, thereby achieving the purpose of distillation and purification. The purified phosphoric acid liquid then flows back into the membrane distillation tank body 3401 from the reflux pipe 3409 and continues to be distilled and purified until the concentration of the phosphoric acid liquid reaches the expected concentration target. The bottom of the heating tube is connected to the extraction pump to realize the extraction of the liquid. The top of the heating tube is bent toward the center and facilitates the centralized flow of the liquid. The bottom of the heating tube is connected to the reflux pipe to reflux the liquid for further treatment. The top of the heating tube is connected to the bottom of the pure water outlet to facilitate the discharge of the separated pure water, which helps to improve the working efficiency and effect of the membrane distillation link in the purification and concentration process of phosphoric acid waste liquid.

[0172] like Figure 7 As shown, the heating tubes 3407 are distributed in a multi-layered annular pattern inside the membrane distillation tank 3401, and the minimum spacing between the heating tubes 3407 is greater than one millimeter. By distributing the heating tubes 3407 in an annular pattern, the space inside the membrane distillation tank 3400 is fully utilized, allowing the hot steam to fully contact the heating tubes 3407, fully heating the phosphoric acid liquid and improving the heat exchange efficiency. The minimum spacing between the heating tubes 3407 is limited to allow the hot steam to pass smoothly, improving the fluidity of the hot steam and making the phosphoric acid waste liquid flow more evenly around the heating tubes, thereby enhancing the heating effect and improving the concentration efficiency. Problems such as local overheating or poor flow caused by too small spacing are avoided, thereby facilitating the stable and efficient concentration of the phosphoric acid waste liquid by the device.

[0173] Furthermore, by arranging the heating tubes 3407 so that the gaps between the heating tubes 3407 are S-shaped, the hot steam flows in an S-shape in the membrane distillation tank body 3401, thereby extending the flow time of the hot steam in the membrane distillation tank body 3401, so that the hot steam can fully heat the heating tubes 3407 and the phosphoric acid liquid inside, thereby improving the heat utilization rate of the hot steam.

[0174] The material of the heating tube 3407 is duplex stainless steel or nickel-based alloy, and the inner surface of the heating tube 3407 is coated with a corrosion-resistant coating. By using the heating tube 3407 made of duplex stainless steel or nickel-based alloy, the duplex stainless steel has the characteristics of low price, high mechanical properties, high pressure resistance and corrosion resistance, and is particularly suitable for moderately corrosive high-salt wastewater, and has good thermal conductivity, which can greatly improve the thermal conductivity of the heating tube 3407. The nickel-based alloy is resistant to high temperature and strong corrosion, and can maintain a stable state in a strong acid environment, thereby extending the service life. Applying the corrosion-resistant coating on the inside of the heating tube 3407 can protect the inner wall of the heating tube 3407, reduce the damage of the phosphoric acid liquid to the inner wall of the heating tube 3407, and avoid the situation where the corrosiveness of the purified phosphoric acid liquid is strong and damages the heating tube 3407.

[0175] like Figure 7 As shown, the cross-sectional shape of the heating tube 3407 is a diamond shape, and the corners of the heating tube 3407 are rounded. By setting the heating tube 3407 to be a diamond shape, the contact area between the heating tube 3407 and the external hot steam is increased, thereby improving the heating efficiency.

[0176] like Figures 4 and 5 As shown, the distance between the bottom of the extraction pump 3408 and the bottom of the inner wall of the membrane distillation tank body 3401 is less than five centimeters, so that the extraction pump can be closer to the bottom of the membrane distillation tank body, extract liquid more efficiently, reduce the amount of liquid remaining at the bottom of the membrane distillation tank body, and help improve the efficiency and quality of phosphoric acid concentration.

[0177] like Figures 3 to 10 As shown, the membrane cleaning assembly includes a servo motor 3410 fixedly connected to one side of the top of the membrane distillation tank body 3401, and two steam filtering membranes 3411 fixedly connected to the output end of the servo motor 3410.

[0178] like Figures 3 to 10As shown, two steam filter membranes 3411 are respectively located on the outside of the steam outlet 3403 and the pure water outlet 3404. By arranging a steam filter membrane 3411 driven by a servo motor 3410 on the top of the membrane distillation tank body 3401, the two steam filter membranes 3411 are respectively located on the outside of the steam outlet 3403 and the pure water outlet 3404. The steam filter membrane 3411 outside the pure water outlet 3404 filters the steam generated by heating, so that the steam passes through the steam filter membrane 3411, and the phosphoric acid is intercepted and purified. The steam filter membrane 3411 outside the steam outlet 3405 is The heated steam is continuously cleaned to realize automatic cleaning of the steam filter membrane 3411. After a period of purification, the servo motor 3410 is started to rotate the two steam filter membranes to replace positions. The clean steam filter membrane 3411 performs filtering and purification work, and the steam filter membrane 3411 that has been filtering for a period of time is replaced to the outside of the steam outlet 3403 for steam self-cleaning, thereby realizing the replacement and automatic cleaning of the two steam filter membranes 3411, extending the service life of the steam filter membrane 3411, reducing the frequency of staff cleaning and replacing the steam filter membrane, and reducing manpower investment.

[0179] like Figures 3 to 10 As shown, the membrane cleaning assembly further includes a pure water discharge pipe 3412 disposed on the top of the pure water outlet 3404 and a steam discharge pipe 3413 disposed outside the steam discharge outlet 3403;

[0180] The end of the pure water discharge pipe 3412 is connected to the external drainage tank, and the end of the steam discharge pipe 3413 is connected to the first heat exchanger 3200. The pure water generated by filtration in the membrane distillation tank is input into the external drainage tank through the pure water discharge pipe 3412, and discharged to the external water body after purification, or recycled and returned to the water-using equipment for repeated use, thereby reducing the water consumption of the equipment. The steam discharge pipe 3413 is connected to the first heat exchanger, and the heat of the hot steam is used to perform the initial heating of the phosphate raw water, making full use of the heat of the hot steam. The fully utilized hot steam is then returned to the condenser for condensation recovery, thereby reducing the water consumption of the equipment.

[0181] like Figures 8 and 9 As shown, the shape of the gap between the pure water discharge pipe 3412 and the pure water outlet 3404 is adapted to the shape of the steam filter membrane 3411, and the shape of the gap between the steam outlet 3403 and the steam discharge pipe 3413 is adapted to the shape of the steam filter membrane 3411. By defining the shapes of the gaps between the pure water discharge pipe 3412 and the pure water outlet 3404, and between the steam outlet 3403 and the steam discharge pipe 3413, the steam filter membrane 3411 can perfectly enter the gap between the two after rotation, completing the assembly, so that the steam filter membrane 3411 can maintain good sealing during the process of filtering or self-cleaning steam.

[0182] Furthermore, sealing gaskets are provided at the ends of the steam filtration membrane 3411, so that it can have good sealing performance during the process of docking with the pipeline.

[0183] like Figures 8 and 9 As shown, the ends of the pure water discharge pipe 3412, the pure water outlet 3404, the steam outlet 3403 and the steam discharge pipe 3413 are all arc-shaped, and the docking interface of the steam filter membrane 3411 is arc-shaped. The arcs of the docking interfaces of the pure water discharge pipe 3412, the pure water outlet 3404, the steam outlet 3403, the steam discharge pipe 3413 and the steam filter membrane 3411 all take the output end rotation shaft of the servo motor 3410 as the center of the circle. By setting the docking interfaces of the pure water discharge pipe 3412, the pure water outlet 3404, the steam outlet 3403, the steam discharge pipe 3413 and the steam filter membrane 3411 to be arc-shaped, the steam filter membrane 3411 can be more closely docked with the pipeline during rotation, thereby avoiding the situation where the straight pipeline hinders the rotation of the steam filter membrane 3411 or the docking is not tight.

[0184] The implementation principle of this embodiment is: the membrane distillation tank 3400 performs membrane distillation purification on the heated nanofiltration water. After a period of purification, the servo motor 3410 is started to rotate the two steam filter membranes to replace positions, and the clean steam filter membrane 3411 performs filtering and purification work, while the steam filter membrane 3411 that has been filtering for a period of time is replaced to the outside of the steam outlet 3403 for steam self-cleaning, thereby realizing the replacement and automatic cleaning of the two steam filter membranes 3411, extending the service life of the steam filter membrane 3411, reducing the frequency of staff cleaning and replacing the steam filter membrane, and reducing manpower investment.

[0185] Example 3

[0186] like Figures 11 to 18 As shown, the difference between this embodiment and the above embodiment is that the condenser 3500 includes a condenser tank body 3501, a cooling water inlet 3502 opened at one end of the condenser tank body 3501, a steam recovery port 3503 opened at the top of the other end of the condenser tank body 3501, a condensed water outlet 3504 opened at the bottom of the other end of the condenser tank body 3501, a cooling water outlet 3505 opened at the top of the condenser tank body 3501, a condensation component arranged inside the condenser tank body 3501, and a support component arranged at the bottom of the condenser tank body 3501. The specific structural design of the condenser enables it to receive steam from the first heat exchanger and cooling water from the cooling tower, and utilizes the condensation component to achieve effective condensation of steam to form condensed water and discharge it from the condensed water outlet. The support component facilitates the installation and movement of the condenser, and overall ensures the smooth cooling of the steam into water in the membrane distillation part, which is conducive to the stable operation of the full membrane system for purification and concentration of phosphoric acid waste liquid.

[0187] like Figures 12 to 18 As shown, the condensation assembly includes a plurality of condensation tubes 3506 fixedly connected to the inside of the condenser tank 3501, a plurality of baffles 3507 arranged on the outside of the condensation tubes 3506, and a partition plate 3508 arranged at the end of the condensation tubes 3506. The condensation assembly consisting of the condensation tubes, baffles and partition plates is arranged in the condenser, which can effectively improve the condensation effect of the steam and enhance the device's treatment capacity and efficiency for phosphoric acid waste liquid.

[0188] like Figures 16 to 18 As shown, the condenser tubes 3506 are all U-shaped, and the partition plate 3508 separates the spaces at both ends of the condenser tube 3506. By arranging the partition plate 3508 at the end of the condenser tank body 3501, the space at one end of the condenser tank body 3501 is separated, so that after the steam enters from the steam recovery port 3503, it all enters the condenser tube 3506 under the blocking and guidance of the partition plate 3508, and exchanges heat with the cooling water entering from the cooling water inlet 3502 in the condenser tube 3506, so that the steam is condensed into liquid, and then discharged from the condensation water outlet 3504, completing the condensation process of the recovered steam, increasing the steam flow path and time, making the steam fully contact with the cooling water, and improving the condensation efficiency.

[0189] like Figures 16 to 18 As shown, the baffles 3507 are evenly distributed inside the condenser tank 3501, and notches are provided on the top or bottom of the baffles 3507, and the notches are staggered on the baffles 3507. By arranging the baffles 3507 inside the condenser tank 3501, the cooling water entering the condenser tank 3501 is deflected and guided, and the flow distance of the cooling water in the condenser tank 3501 is increased, so that the cooling water and steam can fully exchange heat, thereby improving the heat exchange efficiency of the condenser.

[0190] like Figures 16 to 18 As shown, curved plates 3509 are provided at the edges of the deflector 3507. By providing the curved plates 3509 at the edges of the deflector 3507, the cooling water can flow more smoothly during the deflection process, the noise generated during the deflection process of the cooling water can be reduced, and the kinetic energy consumption of the cooling water flow process can be reduced, thereby reducing the energy consumption of the cooling water delivery pump.

[0191] like Figures 11 to 15 As shown, the support assembly includes a plurality of support legs 3510 fixedly connected to the bottom of the condenser tank body 3501, and moving wheels 3511 rotatably connected to both sides of the support legs 3510. The support legs 3510 are isosceles trapezoids. By arranging the support legs 3510 at the bottom of the condenser tank body 3501, the condenser is supported and the stability of the condenser is improved.

[0192] like Figures 14 and 15As shown, the bottom height of the support leg 3510 is higher than the bottom height of the moving wheel 3511, and pull rods 3512 are provided on both sides of the condenser tank body 3501. By arranging the moving wheels 3511 on both sides of the support leg 3510, when the condenser needs to be moved, it is tilted at a certain angle so that the moving wheels 3511 contact the ground, which can convert the sliding friction into rolling friction, making the transportation and movement of the condenser more labor-saving and efficient. The pull rods 3512 are provided on both sides of the condenser tank body 3501 to facilitate pulling the tank body for movement.

[0193] The cooling water inlet 3502 and the cooling water outlet 3505 are respectively connected to the water outlet and water inlet of the cooling tower 3600, and the steam recovery port 3503 is connected to the steam outlet of the first heat exchanger 3200, thereby realizing the recycling of cooling water and improving the utilization rate of water resources. It also allows the steam to effectively enter the condenser from the first heat exchanger for condensation, ensuring the normal operation of the device and realizing the purification and concentration treatment of the phosphoric acid waste liquid.

[0194] The condensed water outlet 3504 is connected to a condensed water tank, the top gas phase space of the condensed water tank is connected to a vacuum pump, and the bottom water phase space of the condensed water tank is connected to a self-priming pump. The condensed water at the condenser outlet may be discharged intermittently due to flow fluctuations or pressure changes. The condensed water tank serves as a buffer container to avoid direct discharge that causes system pressure fluctuations. The vacuum pump maintains the vacuum degree of the system. In membrane distillation or vacuum concentration processes, the vacuum pump ensures a stable negative pressure environment in the system by sucking non-condensable gases (such as air and volatile organic compounds) in the condensed water tank, lowering the boiling point to improve evaporation efficiency. The self-priming pump can efficiently discharge condensed water under negative pressure through a special structure (such as a gas-liquid separation chamber) to avoid the liquid level in the tank being too high and affecting the vacuum degree. The self-priming pump flow rate of the membrane distillation system is higher than the water inlet pump flow rate to facilitate timely discharge of condensed water from the condensed water tank.

[0195] The implementation principle of this embodiment is: cooling water enters from the cooling water inlet 3502, passes through the notches of multiple baffles 3507 and is discharged from the cooling water outlet 3505. Under the action of the baffle 3407, the cooling water flows in an S shape. Steam enters from the steam recovery port 3503, passes through the condenser 3506 and is discharged from the condensate outlet 3504. The U-shaped condenser 3506 makes the internal steam move back and forth, thereby increasing the heat exchange time between cooling water and steam, fully exchanging heat, and condensing the steam into condensed water. The arc plate 3509 on the baffle 3407 guides the flow of cooling water to improve the smoothness of the cooling water flow.

[0196] Example 4

[0197] like Figures 19 to 24As shown, the difference between this embodiment and the above embodiment is that the cooling tower 3600 includes a cooling tower body 3601, a cooling tower water outlet 3602 arranged on one side of the bottom of the cooling tower body 3601, a cooling tower air inlet 3603 arranged on the other side of the bottom of the cooling tower body 3601, a spray component arranged on the upper half of the inner wall of the cooling tower body 3601, a cooling component arranged on the lower half of the inner wall of the cooling tower body 3601, and a heat dissipation component arranged on the top of the cooling tower body 3601. The spray component, the cooling component and the heat dissipation component cooperate to effectively reduce the water temperature, provide low-temperature cooling water for the condenser, ensure the condensation effect of the condenser, and thereby ensure the stable operation of the entire full-membrane system for the purification and concentration process of phosphoric acid waste liquid.

[0198] like Figures 20 to 24 As shown, the spray assembly includes an input pipe 3604 fixedly connected to the upper half of the inner wall of the cooling water tower body 3601, a plurality of water distribution pipes 3605 fixedly connected to the input pipe 3604, and a plurality of spiral nozzles 3606 rotatably connected to the bottom of the water distribution pipe 3605.

[0199] like Figures 20 to 24 As shown, the water delivery pipe 3604 is connected to the condensate outlet 3504, the water distribution pipes 3605 are connected to the water delivery pipe 3604, the spiral nozzles 3606 are connected to the water distribution pipes 3605, and the spiral nozzles 3606 are provided with a plurality of water outlet holes;

[0200] A plurality of drive motors 3607 are fixedly connected to the top of the water distribution pipe 3605, and the output ends of the drive motors 3607 are respectively fixedly connected to the top rotating shafts of the spiral nozzles 3606. By arranging the spiral nozzles 3606 driven by the drive motors 3607 on the water distribution pipe 3605, water is sprayed by the rotating spiral nozzles 3606 to form a water curtain with a larger coverage area, and improve the uniformity of the condensed water spraying, so that the water curtain is fully in contact with the cold air, thereby improving the heat exchange efficiency between the condensed water and the cold air, and accelerating the cooling efficiency of the condensed water.

[0201] like Figures 20 to 22 As shown, the cooling component includes a heat dissipation filler 3608 fixedly connected to the lower half of the inner wall of the cooling tower body 3601, and a jet pipe 3609 fixedly connected below the heat dissipation filler 3608. The cooling component composed of the heat dissipation filler and the jet pipe can effectively cool the water in the cooling tower. The jet pipe helps to evenly disperse the gas, enhance the heat exchange effect with the water, and cooperate with the heat dissipation filler to further improve the cooling efficiency.

[0202] like Figures 10 to 23As shown, the jet pipe 3609 is a vortex line, one end of the jet pipe 3609 is connected to the air inlet 3603 of the cooling tower, and the end of the air inlet 3603 of the cooling tower is connected to a fan. A number of air outlet holes are opened on the top of the jet pipe 3609. A heat dissipation filler 3608 is arranged inside the cooling tower 3600. The heat dissipation filler is the core carrier of heat exchange, which improves the cooling efficiency by increasing the contact area and prolonging the contact time. The filler disperses the water flow into a thin film or fine water droplets through its complex geometric structure (such as corrugated plate, honeycomb or grid design), significantly increases the contact area between water and air, promotes heat exchange and evaporative heat dissipation, and the filler layer can slow down the water flow speed, prolong the contact time between water and air, and improve the cooling efficiency. The vortex line jet pipe 3609 pressurizes the external air and pushes it upward, forcing it to pass through the filler layer, thereby enhancing the air flow rate and flow.

[0203] like Figures 20 to 22 As shown, the heat dissipation assembly includes exhaust pipes 3610 arranged on both sides of the top of the cooling tower body 3601, a heat dissipation fan 3611 arranged inside the exhaust pipe 3610, and a water eliminator 3612 arranged inside the exhaust pipe 3610.

[0204] like Figures 19 to 23 As shown, the drain pipe 3610 is bent to both sides, and the dehumidifier 3612 is located at the end of the drain pipe 3610. The water collected by the dehumidifier 3612 flows back to the cooling water tower body 3601. Bending the end of the drain pipe 3610 can reduce the dust and garbage above from entering the cooling water tower body 3601 from the drain pipe 3610. The dehumidifier reduces the drift loss of cooling water by physically intercepting and separating the water droplets entrained in the air flow, thereby improving the utilization rate of cooling water and reducing the water consumption of the equipment.

[0205] like Figure 24 As shown, a number of V-shaped plates 3613 are fixedly connected to the top of the inner wall of the cooling water tower body 3601. The height of the V-shaped plates 3613 gradually decreases from the middle to the two ends. The V-shaped plates 3613 are evenly distributed inside the cooling water tower body 3601. The V-shaped plates 3613 are located above the spray assembly. By arranging the V-shaped plates 3613 above the spray assembly, water vapor in the exhaust gas is intercepted and refluxed along the inclined V-shaped plates 3613, thereby reducing the loss of cooling water and improving the utilization rate of cooling water.

[0206] The condensed water from the membrane distillation system 3000 is returned to the ultrafiltration membrane raw water tank to dilute the feed phosphoric acid and adjust its concentration, thus saving water.

[0207] The steam generated by the membrane distillation system 3000 exchanges heat with the nanofiltration water, preheating the nanofiltration water before entering the membrane distillation system and reducing the temperature of the steam, which helps to improve the subsequent concentration efficiency and reduce the steam temperature, saving energy consumption of the membrane distillation system.

[0208] The membrane distillation system 3000 is divided into two sections according to the concentration required. The first section concentrates phosphoric acid to 60%, and the second section concentrates phosphoric acid to more than 60%. This can achieve more accurate and efficient phosphoric acid concentration and meet the usage requirements of different phosphoric acid concentrations.

[0209] The ultrafiltration system 1000, nanofiltration system 2000 and membrane distillation system 3000 are all equipped with monitoring devices for various indicators such as flow rate, temperature, pressure, conductivity and pH. These devices monitor various parameters of the concentrated full membrane system online, providing timely feedback on system operating conditions and ensuring process stability.

[0210] Furthermore, the ultrafiltration system 1000 and the nanofiltration system 2000 each have a set of independent cleaning systems.

[0211] The implementation principle of this embodiment is: the cooling water tower 3600 sprays the water entering the cooling water tower, and the driving motor 3607 drives the spiral nozzle 3606 to rotate, so that the water mist is more uniform and has a larger range, and the jet pipe 3609 sprays low-temperature air from under the heat dissipation filler 3608. The low-temperature air and water mist exchange heat in the heat dissipation filler 3608 to achieve rapid cooling of the high-temperature water.

[0212] Example 5

[0213] like Figures 25 to 35 As shown, the ultrafiltration membrane box 1500 includes an ultrafiltration membrane box body 1501, a transmission screw 1502 rotatably connected to the four corners of the inner wall of the ultrafiltration box body 1501, a sealing mechanism threadedly connected to the transmission screw 1502, a connecting rod opening and closing mechanism arranged at one end of the ultrafiltration membrane box body 1501, and an ultrafiltration membrane 1503 arranged between the sealing mechanisms.

[0214] like Figures 28 to 35As shown, the sealing mechanism includes a plurality of sealing plates 1504 that are slidably connected to the interior of the ultrafiltration membrane box 1500. The four corners of the sealing plates 1504 are respectively threadedly connected to the transmission screw 1502. The sealing plates 1504 form a group of two, and the ultrafiltration membrane 1503 is respectively arranged between the two sealing plates 1504 in the same group. The thread directions of the two sealing plates 1504 in the same group are opposite. By arranging the sealing plates 1504 controlled by the thread of the transmission screw 1502 inside the ultrafiltration membrane box 1501, and then assembling the ultrafiltration membrane 1503 into the ultrafiltration membrane box 1501, the transmission screw is rotated. 1502 rotates, and through the threaded transmission of the transmission screw 1502 and the sealing plate 1504, the two sealing plates 1504 in the same group move toward each other to clamp the ultrafiltration membrane 1503, thereby realizing the limitation of the ultrafiltration membrane 1503, improving the stability of the assembly of the ultrafiltration membrane 1503, and at the same time improving the sealing between the ultrafiltration membranes 1503. When the ultrafiltration membrane 1503 needs to be removed, the transmission screw 1502 is rotated in the opposite direction to separate the two sealing plates 1504 in the same group, thereby realizing the rapid assembly and removal of the ultrafiltration membrane inside the ultrafiltration membrane box, and improving the sealing and stability of the ultrafiltration membrane assembly.

[0215] The shape of the sealing plate 1504 is adapted to the cross-sectional shape of the inner wall of the ultrafiltration membrane box 1501. The friction coefficient between the sealing plate 1504 and the inner wall of the ultrafiltration membrane box 1501 is less than 0.5. A sealing ring is provided at the contact position between the sealing plate 1504 and the ultrafiltration membrane 1503. By limiting the shape friction coefficient of the sealing plate 1504, etc., it can fully cooperate with the inner wall of the ultrafiltration membrane box 1501, ensuring the sealing performance while enabling the sealing plate 1504 to slide smoothly inside the ultrafiltration membrane box 1501 to complete the clamping or loosening of the ultrafiltration membrane 1503.

[0216] like Figures 28 to 34 As shown, a telescopic sealing sleeve 1505 is fixedly connected between two adjacent sealing plates 1504 that are not in the same group. The cross-sectional shape of the telescopic sealing sleeve 1505 is adapted to the shape of the sealing plate 1504. The telescopic stroke of the telescopic sealing sleeve 1505 is twice the sliding stroke of the sealing plate 1504. By providing the telescopic sealing sleeve 1505 between adjacent groups of sealing plates 1504, the gap between the two groups of sealing plates 1504 is sealed during the sliding process of the sealing plates 1504, thereby preventing the phosphoric acid waste liquid from accumulating in the gap between adjacent sealing plates 1504 without being fully ultrafiltered.

[0217] Furthermore, a wavy support bar is provided on the outside of the sealing plate 1504 to improve the compressive strength of the sealing plate 1504. At the same time, the support bar is made of heat-conducting material. When the temperature of the ultrafiltration membrane is too high, the support bar can improve the heat dissipation efficiency of the ultrafiltration membrane 1503.

[0218] like Figures 25 to 27As shown, the connecting rod opening and closing mechanism includes three groups of transmission connecting rods 1506 respectively connected to the transmission screw 1502, a telescopic cylinder 1507 rotatably connected to one end of the ultrafiltration membrane box 1501, and a connecting rod 158 provided between the end of the transmission screw 1502 and the output end of the telescopic cylinder 1507;

[0219] A group of transmission links 1506 consists of three transmission rods, and the ends of a group of transmission links 1506 are rotatably connected to two transmission screws 1502. The longest transmission rod length of the transmission link 1506 is equal to the distance between two adjacent transmission screws 1502. The three transmission rods of a group of transmission links 1506 form an equilateral quadrilateral. By arranging a transmission link 1502 at the end of the ultrafiltration membrane box 1501, the rotation of one of the transmission screws 1502 is controlled by the cooperation of the telescopic cylinder 1507 and the connecting rod 1508, and then the other three transmission screws 1502 are driven to rotate by the three groups of transmission links 1506, so that one telescopic cylinder 1507 controls the rotation of the four transmission screws 1502, and then one telescopic cylinder 1507 controls the opening and closing of all sealing components, thereby realizing rapid assembly, clamping and limiting of the ultrafiltration membrane 1503.

[0220] like Figures 25 to 29 As shown, an ultrafiltration water inlet pipe 1509 is provided at the bottom of the ultrafiltration membrane box 1501, and the water distribution pipes of the ultrafiltration water inlet pipe 1509 are respectively located under each sealing mechanism; a filtrate collecting pipe 1510 is provided on one side of the ultrafiltration box 1501, and the end of the filtrate collecting pipe 1510 is respectively connected to each ultrafiltration membrane 1503; an ultrafiltration water outlet pipe 1511 is provided on the other side of the ultrafiltration membrane box 1501, and the ultrafiltration water outlet pipe 1511 is connected to the ultrafiltration membrane box 1501.

[0221] The implementation principle of this embodiment is: a sealing plate 1504 controlled by a transmission screw 1502 thread is set inside the ultrafiltration membrane box 1501, and then the ultrafiltration membrane 1503 is assembled into the ultrafiltration membrane box 1501, and the transmission screw 1502 is rotated. Through the threaded transmission of the transmission screw 1502 and the sealing plate 1504, the two sealing plates 1504 in the same group move toward each other to clamp the ultrafiltration membrane 1503, thereby realizing the limitation of the ultrafiltration membrane 1503, improving the stability of the assembly of the ultrafiltration membrane 1503, and at the same time improving the sealing between the ultrafiltration membranes 1503, and the expansion and contraction of the telescopic cylinder 1507 controls the opening and closing of multiple groups of sealing plates 1504.

[0222] The above description is only used to illustrate the technical solution of the present invention and is not intended to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in this field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. Phosphoric acid waste liquid purification and concentration full membrane system, its characteristics are: It includes an ultrafiltration system, a nanofiltration system, and a membrane distillation system which are arranged in sequence; The membrane distillation system includes a membrane distillation raw water tank connected to the water outlet of the nanofiltration water production tank of the nanofiltration system, a first heat exchanger connected to the water outlet of the membrane distillation raw water tank, a second heat exchanger connected to the water outlet of the first heat exchanger, a membrane distillation tank connected to the water outlet of the second heat exchanger, a condenser connected to the steam outlet of the first heat exchanger, and a cooling water tower in circular communication with the condenser; The membrane distillation tank comprises a membrane distillation tank body, a distillation assembly arranged inside the membrane distillation tank body, and a membrane cleaning assembly arranged on the top of the membrane distillation tank body; The distillation assembly includes a plurality of heating tubes fixedly connected to the interior of the membrane distillation tank, an extraction pump arranged at the bottom of the heating tubes, and a reflux tube arranged at the top of the heating tubes; The membrane cleaning assembly includes a servo motor fixedly connected to one side of the top of the membrane distillation tank body and two steam filtering membranes fixedly connected to the output end of the servo motor; The condenser includes a condenser tank body and a condensation assembly arranged inside the condenser tank body; the condensation assembly includes a plurality of condensation tubes fixedly connected to the inside of the condenser tank body, a plurality of baffles arranged outside the condensation tubes, and a partition plate arranged at the end of the condensation tubes; The cooling water tower includes a cooling water tower body and a cooling component arranged on the lower half of the inner wall of the cooling water tower body; the cooling component includes a heat dissipation filler fixedly connected to the lower half of the inner wall of the cooling water tower body and an air injection pipe fixedly connected below the heat dissipation filler.

2. The phosphoric acid waste liquid purification and concentration full membrane system according to claim 1, characterized in that: The ultrafiltration system includes an ultrafiltration raw water tank, an ultrafiltration booster pump connected to the water outlet of the ultrafiltration raw water tank, an ultrafiltration filter connected to the water outlet of the ultrafiltration booster pump, an ultrafiltration circulation pump connected to the water outlet of the ultrafiltration filter, an ultrafiltration membrane tank connected to the water outlet of the ultrafiltration circulation pump, and an ultrafiltration water production tank connected to the water outlet of the ultrafiltration membrane tank. The water outlet of the ultrafiltration water production tank is connected to the nanofiltration system, and the pure water outlet of the ultrafiltration membrane tank is connected to the external water tank. The nanofiltration system includes a nanofiltration raw water tank connected to the water outlet of the ultrafiltration water production tank, a nanofiltration booster pump connected to the water outlet of the nanofiltration raw water tank, a nanofiltration filter connected to the water outlet of the nanofiltration booster pump, a nanofiltration high-pressure pump connected to the water outlet of the nanofiltration filter, a nanofiltration membrane tank connected to the water outlet of the nanofiltration high-pressure pump, and a nanofiltration water production tank connected to the water outlet of the nanofiltration membrane tank. The water outlet of the nanofiltration water production tank is connected to the membrane distillation system, and the pure water outlet of the nanofiltration membrane tank is connected to the external drainage tank.

3. The phosphoric acid waste liquid purification and concentration full membrane system according to claim 1 is characterized in that: The membrane distillation tank comprises a steam input port provided on one side of the membrane distillation tank body, a steam exhaust port provided on the other side of the membrane distillation tank body, a pure water outlet provided on the top of the membrane distillation tank body, a produced water inlet provided on one side of the bottom of the membrane distillation tank body, and a produced water outlet provided on the other side of the bottom of the membrane distillation tank body; The two steam filter membranes are respectively located outside the steam outlet and the pure water outlet; The membrane cleaning assembly further includes a pure water discharge pipe arranged at the top of the pure water outlet and a steam discharge pipe arranged outside the steam discharge outlet; The end of the pure water discharge pipe is connected to the external water discharge tank, and the end of the steam discharge pipe is connected to the first heat exchanger; The shape of the gap between the pure water discharge pipe and the pure water outlet is adapted to the shape of the steam filter membrane, and the shape of the gap between the steam discharge outlet and the steam discharge pipe is adapted to the shape of the steam filter membrane.

4. The phosphoric acid waste liquid purification and concentration full membrane system according to claim 1, characterized in that: The bottom of each heating tube is connected to the extraction pump, the top of each heating tube is bent toward the center and connected, the bottom of each heating tube end is connected to the return pipe, and the top of each heating tube end is connected to the bottom of the pure water outlet; The heating tubes are distributed in a multi-layered annular pattern inside the membrane distillation tank, and the minimum spacing between the heating tubes is greater than one millimeter.

5. The phosphoric acid waste liquid purification and concentration full membrane system according to claim 1 is characterized in that: The heating tube is made of duplex stainless steel or nickel-based alloy, and the inner surface of the heating tube is coated with a corrosion-resistant coating; The cross-section of the heating tube is a rhombus, and the edges and corners of the heating tube are rounded; The distance between the bottom of the extraction pump and the bottom of the inner wall of the membrane distillation tank is less than five centimeters.

6. The phosphoric acid waste liquid purification and concentration full membrane system according to claim 1 is characterized by: The condenser includes a cooling water inlet at one end of the condenser tank, a steam recovery port at the top of the other end of the condenser tank, a condensed water outlet at the bottom of the other end of the condenser tank, a cooling water outlet at the top of the condenser tank, and a support assembly arranged at the bottom of the condenser tank; The condensing tubes are all U-shaped, and the partition plate separates the spaces at the two ends of the condensing tubes; The baffles are evenly spaced inside the condenser tank, and notches are provided on the top or bottom of the baffles, and the notches are staggered on the baffles; Arc plates are provided at the edges of the baffles.

7. The phosphoric acid waste liquid purification and concentration full membrane system according to claim 1 is characterized by: The cooling tower comprises a cooling tower water outlet arranged on one side of the bottom of the cooling tower body, a cooling tower air inlet arranged on the other side of the bottom of the cooling tower body, a spray assembly arranged on the upper half of the inner wall of the cooling tower body, and a heat dissipation assembly arranged on the top of the cooling tower body; The spray assembly includes an input pipe fixedly connected to the upper half of the inner wall of the cooling tower body, a plurality of water distribution pipes fixedly connected to the input pipe, and a plurality of spiral spray pipes rotatably connected to the bottom of the water distribution pipe. The water delivery pipe is connected to the condensed water outlet, the water distribution pipes are connected to the water delivery pipe, the spiral nozzles are connected to the water distribution pipe, and the spiral nozzles are provided with a plurality of water outlet holes; A plurality of drive motors are fixedly connected to the top of the water distribution pipe, and the output ends of the drive motors are fixedly connected to the top rotating shafts of the spiral nozzles respectively; The jet pipe is a vortex line, one end of the jet pipe is connected to the air inlet of the cooling water tower, the end of the air inlet of the cooling water tower is connected to a fan, and a plurality of air outlet holes are opened on the top of the jet pipe.

8. The phosphoric acid waste liquid purification and concentration full membrane system according to claim 7, characterized in that: The heat dissipation assembly includes exhaust pipes arranged on both sides of the top of the cooling tower body, a heat dissipation fan arranged inside the exhaust pipes, and a water eliminator arranged inside the exhaust pipes; The exhaust pipe is bent to both sides respectively. The water eliminator is located at the end of the exhaust pipe. The water collected by the water eliminator flows back to the cooling water tower body.

9. The full membrane system for purifying and concentrating phosphoric acid waste liquid according to claim 7, characterized in that: A plurality of V-shaped plates are fixedly connected to the top of the inner wall of the cooling water tower body. The height of the V-shaped plates gradually decreases from the middle to the two ends. The V-shaped plates are evenly distributed inside the cooling water tower body and are located above the spray assembly.

10. A full membrane process for the purification and concentration of phosphoric acid wastewater, characterized by: Applied to the full membrane system for purifying and concentrating phosphoric acid waste liquid according to any one of claims 1 to 9, the process comprises the following steps: The phosphoric acid waste liquid enters the ultrafiltration filter through the ultrafiltration booster pump from the ultrafiltration raw water tank, and the ultrafiltration filter removes impurities such as particulate matter in the liquid; After the water exits the ultrafiltration filter, it enters the ultrafiltration circulation pump, which pressurizes it again and then enters the ultrafiltration membrane tank. Under high pressure, the produced water enters the ultrafiltration water tank through the produced water pipeline, and the concentrated water carries the filtered solid suspended matter and is discharged to the external drainage tank. The ultrafiltration produced water enters the nanofiltration raw water tank through the booster pump, and the nanofiltration raw water enters the nanofiltration membrane tank from the nanofiltration raw water tank. The concentrated water carries the filtered metal ions and is discharged to the external drainage tank. The produced water is transported from the nanofiltration produced water tank to the membrane distillation raw water tank; The membrane distillation raw water tank transports the membrane distillation raw water, which is heated to 85°C through the first heat exchanger and the second heat exchanger in turn. The heated membrane distillation raw water is then transported into the membrane distillation tank for membrane distillation treatment. The water produced after the membrane distillation tank is distilled is the concentrated product of phosphoric acid, and the pure water produced by the membrane distillation tank flows back to the membrane distillation raw water tank; The steam discharged from the membrane distillation tank is condensed into water through the condenser and enters the condensation water tank. The condenser is connected to the cooling water tower, and the cooling water tower provides circulating cold water for the condenser.

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