A belt vacuum filtration system

Abstract

The utility model relates to the technical field of filtering equipment, and specifically relates to a belt vacuum filtering system, which comprises a nitre precipitation tank, a sodium sulfate decahydrate slurry pump, a thickening chamber, a slurry pump, a belt vacuum filter, a clear liquid bucket and a clear liquid pump that are connected in sequence. It also includes a vacuum system and a backwashing system that are supporting the belt vacuum filtering system, as well as a nitre dissolving bucket, a nitre washing pump and a heating chamber that are connected to the discharging end of the belt vacuum filter. In this belt vacuum filtering system, the system adopts a process design of "temporary storage in the nitre precipitation tank - pretreatment in the thickening chamber - continuous filtration by the belt vacuum filter", breaking through the limitation of the intermittent operation of the traditional plate and frame filter press, and can continuously complete the feeding, filtering and cake discharging operations of the sodium sulfate decahydrate slurry without interruption. Among them, the pre-concentration treatment of the slurry in the thickening chamber can reduce the subsequent filtering load in advance, and the continuous operation mode of the belt vacuum filter can match the rhythm of large-scale industrial production, effectively solving the problem of efficiency attenuation caused by filter cloth blockage in the traditional drum filter.

Description

Technical Field

[0001] This utility model relates to the field of filtration equipment technology, and more specifically, to a belt vacuum filtration system. Background Technology

[0002] In industries such as chemical engineering, pharmaceuticals, food processing, and environmental protection, solid-liquid separation is a crucial step in the production process, directly impacting product quality, production efficiency, and resource recovery rates. However, traditional filtration equipment and processes commonly suffer from low separation efficiency, high energy consumption, low filtrate recovery rates, and high filter cake moisture content when separating high-solid-content slurries.

[0003] In the salt chemical industry, the treatment of decahydrate sodium sulfate slurry produced after brine freezing is a typical high-difficulty solid-liquid separation scenario. Decahydrate sodium sulfate (Na2SO4·10H2O) has fine crystal particles, high viscosity, and is prone to agglomeration and poor flowability. Traditional filtration equipment, such as plate and frame filter presses and rotary drum filters, often face the following technical bottlenecks when processing this type of slurry:

[0004] Low separation efficiency: Plate and frame filter presses are intermittently operated, requiring frequent start-ups and shutdowns for cake unloading and cleaning. The single batch processing capacity is limited, making it difficult to meet the needs of large-scale continuous production. Drum filters, on the other hand, are prone to filter cloth clogging due to the strong adsorption of decahydrate sodium granules, resulting in a continuous reduction in effective filtration area and a significant decrease in filtration efficiency over time.

[0005] High moisture content in filter cake: Traditional equipment has difficulty in forming a stable and uniform vacuum environment, resulting in insufficient dehydration of decahydrate Glauber's salt filter cake. The moisture content usually exceeds 30%, which not only increases the energy consumption of subsequent drying or nitrification processes, but may also cause secondary dissolution of crystals due to excessive moisture, affecting product purity.

[0006] Poor filter cloth cleaning effect: Fine particles in decahydrate sodium sulfate slurry are easily embedded in the pores of the filter cloth. Traditional rinsing methods are mostly single water spray cleaning, which is difficult to completely remove residual impurities, resulting in a shortened service life of the filter cloth and an increase in equipment maintenance costs.

[0007] Low resource recycling rate: The filtrate after separation often contains a high concentration of soluble salts. Traditional processes lack targeted recycling systems, and direct discharge not only wastes resources but also increases the pressure on environmental treatment.

[0008] Low level of automation: Existing equipment relies heavily on manual operation and control, making it difficult to accurately control filtration parameters (such as vacuum level, feed rate, rinsing frequency, etc.), resulting in poor separation effect stability and large fluctuations in product quality. Utility Model Content

[0009] The purpose of the present utility model is to provide a belt vacuum filtration system to solve the problems in the above-mentioned background technology, namely, the particles of mirabilite (Na2SO4·10H2O) are fine, the viscosity of the slurry is high, and it is easy to agglomerate and has poor fluidity. Traditional filtration equipment such as plate and frame filter presses and drum filters have poor effects when dealing with such slurries.

[0010] To achieve the above purpose, the present utility model provides a belt vacuum filtration system, which includes a mirabilite settling tank, a mirabilite slurry pump, a thickening chamber, a slurry pump, a belt vacuum filter, a clear liquid tank and a clear liquid pump connected in sequence. It also includes a vacuum system and a backwashing system supporting the belt vacuum filtration system, as well as a salt dissolving tank, a salt flushing pump and a heating chamber connected to the discharging end of the belt vacuum filter.

[0011] The mirabilite settling tank is used to temporarily store the mirabilite slurry generated after the brine is frozen. The input end of the mirabilite slurry pump is connected to the mirabilite settling tank, and the output end is connected to the thickening chamber, and it is used to transport the mirabilite slurry in the mirabilite settling tank to the thickening chamber. The thickening chamber is used to conduct concentration and thickening treatment on the mirabilite slurry, and its output end is connected to the feeding end of the belt vacuum filter through a slurry pump. The belt vacuum filter is used to conduct solid-liquid separation on the thickened mirabilite slurry, and its filtrate outlet is connected to the clear liquid tank, and the filter cake outlet is connected to the salt dissolving tank. The clear liquid tank is used to temporarily store the filtrate separated by the belt vacuum filter, and the output end of the clear liquid tank is connected to the secondary brine process pipeline and the salt production process pipeline through a clear liquid pump respectively.

[0012] This setting follows the full-process closed-loop design of "temporary storage - pretreatment - separation - recovery - subsequent treatment". Aiming at the characteristics of mirabilite slurry (the product after brine freezing, containing fine particles and easy to agglomerate), through the sequential connection of each device, directional treatment is achieved. The mirabilite settling tank first buffers and temporarily stores the slurry to avoid fluctuations in the feeding of subsequent equipment. The mirabilite slurry pump and the slurry pump serve as power units to achieve stable transportation of the slurry in each link. The thickening chamber reduces the water content of the slurry through concentration pretreatment and improves the subsequent filtration efficiency. The belt vacuum filter uses vacuum suction and the interception effect of the filter cloth to complete solid-liquid separation, splitting the slurry into filtrate (containing soluble salts) and filter cake (mirabilite). The clear liquid tank and the clear liquid pump form a recovery unit, which directionally transports the qualified filtrate to the secondary brine or salt production process. The salt dissolving tank, the salt flushing pump and the heating chamber conduct subsequent dissolution treatment on the filter cake to provide raw materials for the production of anhydrous sodium sulfate. Through the series connection of equipment, a continuous processing link is formed, breaking the limitations of traditional segmented operations. At the same time, through "separation and classification treatment" (filtrate recovery, filter cake salt dissolution), the maximum utilization of resources is achieved, and the waste of effective components in the slurry is avoided.

[0013] Preferably, the vacuum system includes two water ring vacuum pumps, which are connected to the vacuum chamber of the belt vacuum filter to provide a stable vacuum environment for the belt vacuum filter. The vacuum level can be precisely controlled through an external control system.

[0014] This setup employs a parallel design of two water ring vacuum pumps. This redundancy avoids system downtime due to single-pump failure and allows for coordinated vacuum adjustment between the two pumps. The water ring vacuum pumps create a negative pressure environment by drawing air from the vacuum chamber of the belt vacuum filter. This negative pressure suction accelerates the passage of water from the slurry through the filter cloth into the filtrate, while simultaneously enhancing the filter cloth's retention of decahydrate sodium sulfate particles. An external control system precisely adjusts the vacuum pump's operating power based on real-time parameters such as slurry concentration and filter cake thickness, thereby maintaining a stable vacuum within the appropriate range. This stable negative pressure environment enhances solid-liquid separation efficiency, while the dual-pump design and precise control ensure the continuity and adaptability of the vacuum, preventing issues such as excessively high filter cake moisture content or excessive solids content in the filtrate caused by vacuum fluctuations.

[0015] Preferably, the nitrification tank is used to receive the sodium sulfate filter cake separated by the belt vacuum filter. The input end of the nitrification tank is also connected to the output end of the nitrification pump, which is used to deliver nitrification water into the nitrification tank. The heating chamber is connected to the nitrification tank and is used to heat and melt the material in the nitrification tank. The heat exchange area of ​​the heating chamber is 200㎡. After heating, the material is sent to the sodium sulfate production process through the conveying pipeline.

[0016] This system uses a dissolving tank as a filter cake receiving and dissolving container, first receiving the decahydrate Glauber's salt filter cake produced by a belt vacuum filter. A flushing pump delivers flushing water to the dissolving tank, achieving initial dissolution through mixing the water with the filter cake. A heating chamber, using heat exchange elements with a 200㎡ heat exchange area, transfers heat to the material inside the dissolving tank, accelerating the dissolution of the decahydrate Glauber's salt crystals while simultaneously controlling the temperature and concentration of the dissolved material. The dissolved material (containing sodium sulfate solution) is then directed through a pipeline to the sodium sulfate production process for direct use as raw material. This combination of "flushing water dilution + accelerated dissolution by heating" achieves efficient conversion of the decahydrate Glauber's salt filter cake, while the large heat exchange area design ensures heating efficiency, guaranteeing complete dissolution and achieving the required concentration.

[0017] Preferably, the system also includes two preheaters. The input end of each preheater is connected to an external heat source, and the output end is connected to the jacket of the nitrification tank. These preheaters are used to preheat the nitrification water or materials inside the nitrification tank.

[0018] This system features two preheaters connected in parallel. This redundancy design ensures continuous and stable preheating, and allows for adjustment of the preheating load based on nitrification requirements. The preheater input connects to an external heat source (such as steam or high-temperature water), transferring heat to the nitrification water or the nitrification tank jacket at the output via heat exchange elements. The heat is then transferred through the jacket to the material inside the nitrification tank, preheating it before the nitrification water enters the tank or during the material dissolution process. This proactive approach raises the material temperature, reducing the subsequent heating load on the heating chamber. This staged heating method of "preheating + main heating" utilizes the preheater to raise the material temperature in advance, reducing the heat load on the heating chamber and preventing a sudden temperature drop caused by cold nitrification water directly entering the nitrification tank, thus ensuring a stable dissolution process.

[0019] Preferably, the thickening chamber is equipped with a stirring mechanism, the stirring mechanism having an adjustable rotation speed, to prevent the decahydrate Glauber's salt slurry from settling and clumping during the thickening process.

[0020] This thickening chamber features an adjustable-speed stirring mechanism. The rotating blades shear and mix the decahydrate sodium sulfate slurry. This stirring breaks up the agglomeration tendency of the decahydrate sodium sulfate particles, preventing sedimentation and clumping. It also promotes uniform water distribution, avoiding uneven thickening caused by excessively high local concentrations. The speed adjustment function adjusts the stirring intensity according to changes in slurry concentration; higher concentrations result in increased speed for enhanced dispersion, while lower concentrations reduce speed to decrease energy consumption. Mechanical stirring inhibits particle sedimentation and agglomeration, ensuring the uniformity of the slurry during thickening and preventing pipe blockage or uneven feeding into subsequent filtration equipment due to clumping.

[0021] Preferably, the backwashing system includes two backwashing water pumps with a flow rate of 12.5 m³ / h, and the output end of the backwashing water pumps is connected to a flushing nozzle through a flushing pipeline.

[0022] This system utilizes two backwash water pumps operating in parallel, each with a flow rate of 12.5 m³ / h. This redundancy ensures a stable supply of backwash water and allows for coordinated flow rate adjustment. The backwash pumps pressurize clean water and deliver it to the backwash nozzles via the backwash pipeline. The nozzles then spray high-pressure water onto the surface of the filter cloth in the belt vacuum filter. The high-pressure water flow removes fine particles of sodium sulfate decahydrate embedded in the filter cloth pores, restoring its filtration performance. The 12.5 m³ / h flow rate balances backwash intensity and water consumption, preventing incomplete rinsing due to insufficient flow or damage to the filter cloth due to excessive flow. Through the physical scouring action of the high-pressure water flow, residual impurities on the filter cloth surface and within the pores are removed, restoring the filter cloth's permeability and filtration accuracy, and preventing filter cloth clogging that leads to decreased separation efficiency.

[0023] Preferably, a filter cloth cleaning scraper is installed on one side of the rinsing pipeline for scraping and cleaning impurities on the filter cloth, and the rinsing nozzle is aligned with the filter cloth cleaning scraper for online cleaning of the filter cloth.

[0024] This system features a filter cloth cleaning scraper installed on one side of the flushing pipeline. The scraper makes slight contact with the filter cloth surface, mechanically scraping away large impurities and thick filter cake residue during operation. The flushing nozzle is then aimed at the scraped area, immediately flushing with high-pressure water to remove any remaining fine particles and prevent secondary adhesion of the scraped-off impurities. This synergistic effect of "mechanical scraping + high-pressure flushing" achieves deep cleaning of the filter cloth. First, stubborn, large impurities are removed mechanically, then fine particles are removed with high-pressure water, creating a tiered cleaning mode of "coarse cleaning + fine cleaning," solving the problem of traditional single-flushing methods failing to thoroughly clean stubborn impurities.

[0025] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0026] This belt vacuum filtration system adopts a process design of "temporary storage in the settling tank - pretreatment in the thickening chamber - continuous filtration in the belt vacuum filter," breaking through the limitations of the intermittent operation of traditional plate and frame filter presses. It can complete the feeding, filtration, and cake discharge of decahydrate Glauber's salt slurry without interruption. Among them, the pre-concentration treatment of the slurry in the thickening chamber can reduce the load on subsequent filtration in advance, and the continuous operation mode of the belt vacuum filter can match the pace of large-scale industrial production, effectively solving the efficiency reduction problem caused by filter cloth clogging in traditional drum filters, and significantly improving the overall processing capacity.

[0027] The vacuum system creates a stable vacuum environment through a dual-water-ring vacuum pump. Combined with the uniform slurry distribution structure of the belt filter, it can fully dehydrate the thickened decahydrate sodium sulfate slurry, keeping the moisture content of the sodium sulfate filter cake at a low level. The low-moisture filter cake, after entering the nitrification tank, directly reduces the heat consumption of the heating chamber, lowering the energy input for subsequent sodium sulfate production processes and achieving energy conservation and consumption reduction goals.

[0028] The backwashing system innovatively adopts a combined cleaning method of "mechanical scraper + precision water spray": the filter cloth cleaning scraper first actively scrapes off large particles of impurities attached to the surface of the filter cloth, and then the backwash water pump drives the flushing nozzles to perform targeted flushing of the area cleaned by the scraper. This design can deeply remove fine particles of impurities embedded in the pores of the filter cloth, avoid filter cloth clogging, extend the filter cloth replacement cycle, and reduce downtime and costs caused by frequent maintenance.

[0029] The system utilizes a design that temporarily stores the clarified liquid in a tank and uses a clarified liquid pump for directional delivery to separate the filtrate (SO4). 2-(The filtrate, meeting reuse standards), is precisely delivered to the secondary brine process or salt production process, replacing fresh raw materials. This not only avoids the waste of salt resources caused by the direct discharge of filtrate in traditional processes, but also reduces the consumption of fresh water and raw materials, lowers environmental protection pressure, and forms a closed loop for resource recycling.

[0030] The system is equipped with monitoring elements at key nodes such as the precipitation tank, thickening chamber, and clear liquid tank, which can collect parameters such as liquid level, concentration, and temperature in real time. These parameters can be adjusted in conjunction with an external control system to regulate operating indicators such as vacuum level, feed rate, and rinsing frequency. Compared to traditional manual operation, automated control effectively avoids parameter fluctuations, ensures stable separation of decahydrate sodium sulfate, reduces product quality fluctuations caused by human error, and guarantees the purity of raw materials for subsequent sodium sulfate production. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0032] Figure 2 This is a schematic diagram of the thickening chamber in this utility model;

[0033] Figure 3 This is a schematic diagram of the vacuum system in this utility model;

[0034] Figure 4 This is a schematic diagram of the backwashing system in this utility model;

[0035] The meanings of the labels in the diagram are as follows:

[0036] 1. Precipitation tank; 2. Decahydrate nitrification slurry pump; 3. Thickening chamber; 31. Stirring mechanism; 4. Nitrogen slurry pump; 5. Belt vacuum filter; 51. Filtrate outlet; 52. Filter cake outlet; 6. Clarified liquid tank; 7. Clarified liquid pump; 8. Vacuum system; 81. Water ring vacuum pump; 9. Backwashing system; 91. Backwash water pump; 92. Flushing pipeline; 93. Flushing nozzle; 94. Filter cloth cleaning scraper; 10. Nitrogenation tank; 11. Nitrogenation pump; 12. Heating chamber; 13. Preheater. Detailed Implementation

[0037] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0038] This utility model provides a belt vacuum filtration system, such as Figures 1-4As shown, it includes a settling tank 1, a decahydrate nitrate slurry pump 2, a thickening chamber 3, a nitrate slurry pump 4, a belt vacuum filter 5, a clear liquid tank 6, and a clear liquid pump 7 connected in sequence. It also includes a vacuum system 8 and a backwashing system 9 that are matched with the belt vacuum filter system, as well as a dissolving tank 10, a flushing pump 11, and a heating chamber 12 connected to the discharge end of the belt vacuum filter 5.

[0039] The settling tank 1 is used to temporarily store the decahydrate Glauber's salt slurry produced after the brine is frozen; the input end of the decahydrate Glauber's salt slurry pump 2 is connected to the settling tank 1, and the output end is connected to the thickening chamber 3, which is used to transport the decahydrate Glauber's salt slurry in the settling tank 1 to the thickening chamber 3; the thickening chamber 3 is used to concentrate and thicken the decahydrate Glauber's salt slurry, and its output end is connected to the feed end of the belt vacuum filter 5 through the slurry pump 4; the belt vacuum filter 5 is used to perform solid-liquid separation on the thickened decahydrate Glauber's salt slurry, and its filtrate outlet 51 is connected to the clear liquid tank 6, and its filter cake outlet 52 is connected to the nitrification tank 10; the clear liquid tank 6 is used to temporarily store the filtrate separated by the belt vacuum filter 5, and the output end of the clear liquid tank 6 is connected to the secondary brine process pipeline and the salt production process pipeline through the clear liquid pump 7 respectively.

[0040] This system enables continuous operation of decahydrate Glauber's salt slurry from the settling tank 1 to the heating chamber 12 for nitration, eliminating the need for frequent equipment start-ups and shutdowns. It solves the problems of low efficiency and poor adaptability of traditional intermittent filtration methods such as plate and frame filter presses, meeting the needs of large-scale industrial production. The clarified liquid pump 7 reuses the filtrate in secondary brine or salt production processes, replacing fresh raw materials, reducing salt resource waste and fresh water consumption, and lowering raw material costs. The filter cake, after treatment in the nitration tank 10 and heating chamber 12, provides a stable raw material for downstream sodium sulfate production, forming a synergistic industrial chain. The settling tank 1 acts as a buffer to balance fluctuations in the upstream slurry output, preventing separation deviations in equipment such as the belt vacuum filter 5 due to unstable feed. The thickening chamber 3 pretreatment reduces the load on the belt vacuum filter 5, minimizing the risk of equipment blockage and ensuring overall process stability.

[0041] In this embodiment, the vacuum system 8 includes two water ring vacuum pumps 81, which are connected to the vacuum chamber of the belt vacuum filter 5 to provide a stable vacuum environment for the belt vacuum filter 5. The vacuum level can be precisely controlled through an external control system.

[0042] A stable vacuum environment ensures efficient separation of slurry moisture, reduces filter cake moisture content, and decreases energy consumption in the nitration process of heating chamber 12. Simultaneously, it reduces the content of decahydrate sodium sulfate particles in the filtrate, ensuring the quality of the filtrate delivered by the clarifying pump 7 for reuse and preventing interference with secondary brine or salt production processes. Two water ring vacuum pumps 81 are connected in parallel with redundancy backup; when one pump is under maintenance, the other maintains system operation, reducing production interruptions caused by equipment failure and improving continuous operation capability. An external control system can adjust the vacuum level of the water ring vacuum pumps 81 in real time according to operating conditions, adapting to the separation requirements under different slurry solid contents, solving the problem of insufficient adaptability in traditional fixed vacuum level designs.

[0043] Specifically, the nitrification tank 10 is used to receive the sodium sulfate filter cake separated by the belt vacuum filter 5. The input end of the nitrification tank 10 is also connected to the output end of the nitrification pump 11, which is used to deliver nitrification water into the nitrification tank 10. The heating chamber 12 is connected to the nitrification tank 10 and is used to heat and melt the material in the nitrification tank 10. The heat exchange area of ​​the heating chamber 12 is 200㎡. After heating, the material is sent to the sodium sulfate production process through the conveying pipeline.

[0044] The heating chamber 12, with its large heat exchange area, rapidly increases the material temperature and shortens the nitration time. The nitration pump 11 precisely delivers nitration water, preventing insufficient dissolution due to insufficient water or excessive water resulting in too low a concentration, ensuring nitration efficiency and quality. The dissolved material has a stable concentration and can be directly used as a raw material for sodium sulfate production, reducing downstream pretreatment costs. The directional conveying design avoids material transfer losses and contamination, ensuring stable sodium sulfate product quality. The heating chamber 12 uses centralized heating instead of decentralized heating, combined with the high-efficiency heat exchange characteristics of its large heat exchange area, reducing the energy consumption per unit of material and minimizing heat waste.

[0045] Furthermore, it also includes two preheaters 13. The input end of the preheater 13 is connected to an external heat source, and the output end is connected to the jacket of the nitrification tank 10. It is used to preheat the nitrification water or materials in the nitrification tank 10.

[0046] Preheater 13 preheats the material temperature, reducing the need for additional heat in heating chamber 12, especially significantly reducing the heating load in low-temperature environments, thus achieving energy savings. It prevents temperature fluctuations within the nitration tank 10 caused by cold-flushing nitrate water, preventing the precipitation of decahydrate Glauber's salt crystals, ensuring continuous and stable dissolution, and reducing incomplete dissolution issues. The number of preheaters 13 can be adjusted according to the nitration volume; one preheater can be started at low loads to reduce no-load energy consumption, while both preheaters can operate at high loads to ensure preheating capacity, adapting to different production scales.

[0047] Furthermore, the thickening chamber 3 is equipped with a stirring mechanism 31, the stirring mechanism 31 has an adjustable speed, which is used to prevent the decahydrate Glauber's salt slurry from settling and clumping during the thickening process.

[0048] The stirring mechanism 31 ensures uniform slurry concentration, prevents localized lumps from forming, guarantees the fluidity of the thickened slurry, facilitates delivery by the nitric acid slurry pump 4 and filtration by the belt vacuum filter 5, and improves process smoothness. It also prevents decahydrate sodium sulfate particles from settling and agglomerating at the bottom of the thickening chamber 3, reducing wear and blockage on the impellers and pipes of the decahydrate nitric acid slurry pump 2 and nitric acid slurry pump 4, thus lowering equipment maintenance frequency and costs. The stirring mechanism 31 has an adjustable speed, avoiding insufficient stirring of high-concentration slurry or excessive stirring of low-concentration slurry at a fixed speed, ensuring effective dispersion while reducing energy waste.

[0049] Furthermore, the backwashing system 9 includes two backwashing water pumps 91 with a flow rate of 12.5 m³ / h, and the output end of the backwashing water pumps 91 is connected to a flushing nozzle 93 through a flushing pipeline 92.

[0050] The regular high-pressure rinsing nozzle 93 effectively removes impurities from the filter cloth, preventing long-term impurity adhesion that can lead to filter cloth aging and damage, extending the replacement cycle, and reducing filter cloth consumable costs. It also prevents filter cloth clogging, which could reduce the effective filtration area of ​​the belt vacuum filter 5, ensuring continuous and efficient equipment operation and avoiding excessive solids content in the filtrate or increased moisture content in the filter cake. The 12.5 m³ / h flow rate design ensures effective rinsing while minimizing water waste; the dual backwash pumps 91 allow for flow rate adjustment based on the degree of filter cloth contamination, further optimizing water resource utilization efficiency.

[0051] Furthermore, a filter cloth cleaning scraper 94 is installed on the outside of one side of the flushing pipe 92 for scraping and cleaning impurities on the filter cloth. The flushing nozzle 93 is aligned with the filter cloth cleaning scraper 94 for online cleaning of the filter cloth.

[0052] The filter cloth cleaning scraper 94 removes a thick layer of impurities from the filter cloth surface, avoiding the limitation of high-pressure water flow only rinsing the surface. The subsequent rinsing nozzle 93 further removes fine particles, significantly improving filter cloth cleanliness and restoring filtration accuracy better than traditional single rinsing. The filter cloth cleaning scraper 94 removes large impurities first, reducing the thickness of impurities that the high-pressure water flow from the rinsing nozzle 93 needs to impact, thus reducing the risk of water damage to the filter cloth fibers. It also prevents stubborn impurities from causing long-term compression and deformation of the filter cloth, extending its service life. Thorough cleaning ensures the belt vacuum filter 5 maintains a consistently stable separation efficiency, reducing frequent downtime for cleaning due to incomplete filter cloth cleaning, improving the overall system's continuous operation capability, and reducing operation and maintenance workload.

[0053] The belt vacuum filtration system of this utility model is used in the following steps:

[0054] (I) Slurry Pretreatment Stage

[0055] The decahydrate Glauber's salt slurry produced after the brine is frozen first enters the settling tank 1 for temporary storage and buffering to balance the fluctuations in the output of the slurry produced at the front end, and to avoid the subsequent equipment from being unstable due to the large or small amount of feed.

[0056] Start the decahydrate nitrate slurry pump 2 to transport the slurry in the settling tank 1 to the thickening chamber 3; at the same time, turn on the stirring mechanism 31 in the thickening chamber 3 and adjust the stirring speed according to the slurry concentration (increase the speed when the concentration is high and decrease the speed when the concentration is low). During the stirring process, the slurry is concentrated and thickened, the water content is reduced, and the particles are prevented from settling and clumping.

[0057] (II) Vacuum Filtration and Separation Stage

[0058] The thickened slurry is pumped by the nitric acid slurry pump 4 to the feed end of the belt vacuum filter 5, and the slurry is evenly distributed on the filter cloth. The two water ring vacuum pumps 81 of the vacuum system 8 are started, and the vacuum degree is adjusted to the appropriate range (such as -0.06MPa~-0.08MPa) through the external control system to form a stable negative pressure.

[0059] Under negative pressure, the water in the slurry quickly passes through the filter cloth and enters the filtrate channel of the belt vacuum filter 5, and flows into the clear liquid tank 6 for temporary storage through the filtrate outlet 51; the decahydrate sodium granules are intercepted by the filter cloth and form a continuous sodium nitrate filter cake on the filter cloth, which moves with the filter cloth to the filter cake outlet 52 and finally falls into the nitrification tank 10.

[0060] During the filtration process, the backwashing system 9 is started simultaneously: the filter cloth cleaning scraper 94 adheres to the surface of the filter cloth and scrapes away large impurities and filter cake remaining on the surface as the filter cloth moves; the backwash water pump 91 draws clean water, pressurizes it, and delivers it to the flushing nozzle 93 through the flushing pipeline 92. The nozzle sprays high-pressure water at the area scraped by the scraper to complete the online cleaning of the filter cloth. The cleaned filter cloth is then circulated into the next filtration cycle.

[0061] (III) Filtrate recovery and filter cake nitrification stage

[0062] The filtrate (SO4) temporarily stored in the clear liquid tank 6 2- Once the concentration (≤7g / L) reaches a certain level, the clear liquid pump 7 is started. According to the needs of the secondary brine and salt production processes, the filtrate is directed to the corresponding process pipeline to replace fresh raw materials in production, thereby realizing the recycling of salt and water resources.

[0063] For the sodium sulfate filter cake in the nitrification tank 10, the nitrification pump 11 is started to deliver a certain amount of nitrification water into the nitrification tank 10 to initially dilute the filter cake; at the same time, two preheaters 13 are turned on to transfer the heat from the external heat source (such as steam) to the internal material through the jacket of the nitrification tank 10 to preheat the mixture of nitrification water and filter cake and increase the initial temperature of the material.

[0064] The heating chamber 12 is started, and its heat exchange elements with a heat exchange area of ​​200㎡ continuously transfer heat to the material in the nitration tank 10, controlling the material temperature in the range of 40℃~60℃, and accelerating the complete dissolution of the sodium sulfate filter cake. During the dissolution process, the material concentration is monitored in real time to ensure that the NaCl content is <50g / L and the Na2SO4 content is 300g / L~350g / L. Finally, the qualified material is sent to the sodium sulfate production process through the conveying pipeline.

[0065] (iv) System Coordination and Control Phase

[0066] Throughout the entire process, sensors on various devices monitor parameters in real time, including the liquid level in the settling tank 1, the slurry concentration in the thickening chamber 3, the vacuum level in the belt vacuum filter 5, the filtrate concentration in the clear liquid tank 6, and the material temperature and concentration in the nitrification tank 10. If any parameter deviates from the set value, the external control system automatically adjusts the operating status of the corresponding equipment (such as adjusting the power of the water ring vacuum pump 81, the speed of the stirring mechanism 31, and the backwashing frequency) to ensure stable operation of the entire process and continuous output of qualified filtrate and nitrified materials.

[0067] Finally, it should be noted that the electronic components in the preheater 13 and other components in this embodiment are all general standard parts or parts known to those skilled in the art. Their structure and principle can be learned by those skilled in the art through technical manuals or conventional experimental methods. In the idle part of this device, all the above-mentioned electrical components are connected by wires. The specific connection method should refer to the working order between the electrical components in the above working principle to complete the electrical connection. All of these are technologies known in the art.

[0068] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A belt vacuum filtration system, characterized in that: It includes a settling tank (1), a decahydrate nitrate slurry pump (2), a thickening chamber (3), a nitrate slurry pump (4), a belt vacuum filter (5), a clear liquid tank (6) and a clear liquid pump (7) connected in sequence, as well as a vacuum system (8) and a backwashing system (9) that are matched with the belt vacuum filter system, and a nitrification tank (10), a nitrification pump (11) and a heating chamber (12) connected to the discharge end of the belt vacuum filter (5); The settling tank (1) is used to temporarily store the decahydrate Glauber's salt slurry produced after the brine is frozen; the input end of the decahydrate Glauber's salt slurry pump (2) is connected to the settling tank (1), and the output end is connected to the thickening chamber (3), which is used to transport the decahydrate Glauber's salt slurry in the settling tank (1) to the thickening chamber (3); the thickening chamber (3) is used to concentrate and thicken the decahydrate Glauber's salt slurry, and its output end is connected to the feed end of the belt vacuum filter (5) through the slurry pump (4); the belt vacuum filter (5) is used to perform solid-liquid separation on the thickened decahydrate Glauber's salt slurry, and its filtrate outlet (51) is connected to the clear liquid tank (6), and the filter cake outlet (52) is connected to the nitrification tank (10); the clear liquid tank (6) is used to temporarily store the filtrate separated by the belt vacuum filter (5), and the output end of the clear liquid tank (6) is connected to the secondary brine process pipeline and the salt production process pipeline through the clear liquid pump (7).

2. The belt vacuum filtration system according to claim 1, characterized in that: The vacuum system (8) includes two water ring vacuum pumps (81), which are connected to the vacuum chamber of the belt vacuum filter (5) to provide a stable vacuum environment for the belt vacuum filter (5). The vacuum level can be precisely controlled by an external control system.

3. The belt vacuum filtration system according to claim 1, characterized in that: The nitrification tank (10) is used to receive the sodium sulfate filter cake separated by the belt vacuum filter (5). The input end of the nitrification tank (10) is also connected to the output end of the nitrification pump (11). The nitrification pump (11) is used to deliver nitrification water into the nitrification tank (10). The heating chamber (12) is connected to the nitrification tank (10) and is used to heat and melt the material in the nitrification tank (10). The heat exchange area of ​​the heating chamber (12) is 200㎡. After heating, the material is sent to the sodium sulfate production process through the conveying pipeline.

4. The belt vacuum filtration system according to claim 1, characterized in that: It also includes a preheater (13), of which there are two preheaters (13). The input end of the preheater (13) is connected to an external heat source, and the output end is connected to the jacket of the nitrification tank (10). It is used to preheat the nitrification water or materials in the nitrification tank (10).

5. The belt vacuum filtration system according to claim 1, characterized in that: The thickening chamber (3) is equipped with a stirring mechanism (31), the stirring mechanism (31) has an adjustable speed, and is used to prevent the decahydrate Glauber's salt slurry from settling and clumping during the thickening process.

6. The belt vacuum filtration system according to claim 1, characterized in that: The backwashing system (9) includes two backwashing water pumps (91) with a flow rate of 12.5 m³ / h. The output end of the backwashing water pumps (91) is connected to a flushing nozzle (93) through a flushing pipeline (92).

7. The belt vacuum filtration system according to claim 6, characterized in that: A filter cloth cleaning scraper (94) is installed on one side of the flushing pipe (92) for scraping and cleaning impurities on the filter cloth. The flushing nozzle (93) is aligned with the filter cloth cleaning scraper (94) for online cleaning of the filter cloth.

Images