Does anyone have any information on Chengdu Tianbao vacuum alkali filtration machines?
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Does anyone have any information on Chengdu Tianbao vacuum alkali filtration machines?
Product Introduction: The TB series vacuum drum filter, also known as a soda ash filter, is one of the key equipment in soda ash plants. Its performance has a crucial impact on both the quality of soda ash and the economic efficiency of the enterprise. Based on in-depth research into China’s first and second-generation products, our company incorporated the useful elements from advanced imported equipment, visited numerous leading enterprises to gather first-hand information, and on this basis successfully developed the third-generation vacuum drum filter series. This series has been widely used and highly praised by large and medium-sized enterprises in the soda ash industry. 1. Working principle of the alkali filtration machine: A vacuum pump is used to create a negative pressure inside the machine, thereby generating a pressure difference between the two sides of the filtering medium (filter screen). This pressure difference draws out the liquid from the suspension, while the solid particles remain on the filter screen, allowing for the separation of solids and liquids. At the same time, the solid particles are washed and dried so that their salt and water content meet the specified standards. 2. Product Specifications
Based on the actual conditions of various manufacturers, our company has designed and produced alkali filtration machines in seven different sizes: 6.5 m2, 8 m2, 10 m2, 13.5 m2, 17 m2, 20 m2, and 23 m2. The models and technical parameters of the vacuum drum filtration machines produced by our company are shown in the table below:
| Specification | Characteristics |
|--------------|-----------------|
| 6.5 m2 | |
| 8 m2 | |
| 10 m2 | |
| 13.5 m2 | |
| 17 m2 | |
| 20 m2 | |
| 23 m2 | |
**Filtering area:** m2 – 6.5, 8, 10, 13.5, 17, 20, 23
**Production capacity:** t/day – 170, 240, 280, 360, 450–540, 550–650, 620–740
**Vacuum level:** MPa – ≥400, ≥400, ≥400, ≥400, ≥400, ≥400, ≥400
**Material moisture content:** % – ≤18%, ≤18%, ≤18%, ≤18%, ≤18%, ≤18%, ≤18%
**Drum rotation speed:** rpm – 1.1–3.6, 1.1–3.6, 1.1–3.6, 1.1–3.6, 1.1–3.3, 1.1–3.3, 1.1–3.57
**Stirring speed:** rpm – 33.7, 33.7, 33.7, 33.7, 33.7, 33.7, 23.8
**Drum diameter:** mm – Φ2250, Φ2250, Φ2250, Φ2250, Φ2600, Φ2600, Φ2600
**Drum length:** mm – 930, 1150, 1420, 1910, 2080, 2420, 2820
**Main material:** 316L/HT200
3. Product Features
3.1 The drum features a hollow structure, which effectively eliminates the dead zones that existed in previous designs. This increases the cross-sectional area of the gas channels, reduces gas resistance within these channels, thereby ensuring smoother flow and more uniform alkali absorption. Thus, **the production capacity of the alkali filtration machine was increased, and the washing water equivalent was reduced. 3.2 The distribution head is made of 316L ultra-low carbon stainless steel, offering significant improvements over the original HT200 distribution head in terms of corrosion resistance, weight, and maintenance. A rational arrangement of the fixed air-blocking zone, blowing zone, blowing and discharging zone, filtration zone, dehydration and drying zone, washing zone, etc., has a significant impact on increasing productivity and reducing moisture content. In this regard, we have accumulated extensive experience in optimizing the allocation of various areas to achieve the best results. By improving the internal structure of the drum and enlarging the diameter of the shafts responsible for air flow, we ensure more uniform alkali absorption and smoother flow pathways. 3.3 To meet the special needs of users, we adjust the material of the fixed air-shifting disc according to their requirements; the current materials for such discs include polytetrafluoroethylene, graphite, and modified nylon. Three different materials can be selected according to the user’s needs to suit various operating conditions. 3.4 A two-roller system was adopted to modify the original structure, and by improving the design of the rollers, the moisture content of the heavy alkali was effectively reduced. The pressure roller adjustment spring is placed within the sealing structure, making it both simple and practical; this completely solves the major problems of complex design, poor performance, and frequent failures that existed in previous designs. 3.5 Uses a spray device instead of a washing tank to achieve more even washing. The cleaning effect is significant, water usage is **reduced**, and the salt content is improved. In the design of the spraying system, 5 spraying units are typically installed. Each of these units can be adjusted up, down, forward, and backward, and they can also be turned on or off as needed. Depending on the conditions of the filter cake, the distance at which water is sprayed onto the filter cake can be adjusted in order to reduce the generation of water vapor. It is also very convenient to adjust by turning on or off the number of spray nozzles, depending on the salt and moisture content of the filter cake. 3.6 To improve the working environment and prevent liquid splashing, an all-round liquid barrier has been installed between the side frame and the drum. 3.7 The stirring mechanism of the original alkali filtration machine was one that featured an eccentric wheel structure mounted on the alkali solution tank. The most significant drawback of this design was that the grease used to lubricate the eccentric wheel components would fall into the alkali solution tank, contaminating the quality of the mother liquor and thus affecting the quality of the caustic soda. The traditional approach to solving this problem is to add a skeleton seal to the eccentric wheel assembly, but this method does not completely resolve the issue of grease contamination in the mother liquor. The external mixing device we used completely solved the problem of oil contamination in the mother liquor. 3.8 The main body of the equipment is entirely made of ultra-low carbon stainless steel, which enhances its corrosion resistance and is highly beneficial for ensuring the quality of the alkali cake. 3.9 The main drive has been changed from a conventional speed-regulating motor to one controlled by an inverter; various parameters related to the motor’s operation can be displayed clearly, making operation more convenient. 3.10 Thanks to mass production, aside from the 16.5 m2 and 20 m2 soda ash filters which form a series that can be interchanged, the spare parts and replacement components for the other models of soda ash filters can almost all be replaced, which provides great convenience for manufacturers. Adhering to the principle of \"quality first, optimized management, technological innovation, and customer satisfaction,\" our company upholds the corporate philosophy of \"putting people first, pursuing innovation, expanding into both domestic and international markets, and creating high-quality brands.\" We are committed to serving our customers wholeheartedly, constantly exploring new possibilities, and striving for improvement in order to make the TB-type alkali filter machines even better. Description of the process configuration for the fourth-generation vacuum drum filter. Thanks to the use of latest technologies in the field of filter design and manufacturing, such as air-blown unloading, separation of mother liquor from filtrate, spray washing, triple sealing at the air inlet, and fully sealed transmission systems, the fourth-generation vacuum drum filter features several changes and adjustments compared to traditional filtering processes. If properly configured, the technical advantages of the fourth-generation filter can be fully realized, resulting in significant improvements and enhancements in various technical parameters such as energy consumption, process costs, soda ash quality, and the capacity of subsequent production equipment. I. Requirements for process operation conditions 1. Since the blowing-unloading technology is employed, the same air source is used for both blowing regeneration and blowing unloading, which results in a certain consumption of air volume and pressure. Therefore, the selection of the blower requires a slight increase over the conventional standard flow rate of 50 Nm3/t of alkali; the gauge pressure in the main pipeline should be around 60 KPa. The head pressure of the vehicle in operation should not be lower than 25 KPa. 2. The mother liquor and filtrate separation technology enables a true separation between the alkali absorption zone and the washing and drying zone, with each going into its respective vacuum separator for mother liquor and filtrate. The third-generation filter does not have reverse flow recovery washing of the filtrate, nor does it have a filtrate vacuum separator. Therefore, the selection requirements for vacuum pumps generally require an increase from the conventional standard flow rate of 200 Nm3/t of alkali to around 250 Nm3/t of alkali. The inlet pressure should be ≥56 KPa, and the vacuum level at the locomotive during operation should be ≥40 KPa. 3. Difference between nozzle-based atomized washing and sink-based washing: First, the nozzle must have sufficient pressure; the height difference between the water tank and the alkali tank should be ≥10m to ensure an effective atomization effect ； Secondly, different types of nozzles can be selected to facilitate the spraying of various cleaning solutions. In a process where vacuum filters are followed by centrifuges to further reduce the moisture and salt content in the alkaline solution, the liquid resulting from the centrifuge can be used as a second cleaning solution; it can be recovered together with the liquid from the first filter using a pump (as shown in the diagram), and the flow rate can be adjusted via separate valves ； Thirdly, the installation positions of the five spray nozzles can be optimized and combined according to actual operating conditions in order to achieve the best process parameters; in particular, changes in aspects such as the concentration of the carbonization effluent, the quality of the crystals, and the rotation speed of the filter are directly related to the installation positions of these spray nozzles. The first and second nozzles use flat-mouthed fan-shaped nozzles that are resistant to clogging; it is required that the pressure at each nozzle be no less than 50 KPa, with the main pipe pressure being no lower than 1 bar. II. Requirements for the selection of supporting facilities 1. The structure of the new post-washing liquid separator should be the same as that of the mother liquor separator; if they are located on the same floor (the fourth floor), a separator with a larger capacity (around 3 m3) can be chosen and placed between the two mother liquor separators ； If installation is difficult, it can also be placed on the lower floor (the third floor), divided into two sections on the left and right, with each section having a volume of 1.5–2 m3. 2. The newly added post-washing liquid tank is a storage tank equipped with a stirrer; its capacity should be greater than 8 m3 and its height should be no less than 3 m. Water used for car washing with alkaline solutions or other mild liquids can also be recycled as washing fluid to maintain equilibrium in the mother liquor. 3. The newly added post-washing liquid pump should be selected appropriately based on the capacity of the post-washing liquid tank and the height difference of the alkali tank; a recommended flow rate is 8–10 m3/h, with a head of ≥30 m. 4. The existing mother liquor vacuum separator can still be used. III. Requirements for process piping: 1. The mother liquor vacuum pipes and the vacuum pipes for the washed liquid should be installed at an angle pointing toward the separator, as short as possible, to prevent blockages caused by the accumulation of alkali; valves should be installed on each of these pipes to control the amount of vacuum. If the vacuum tube for the left-side wash liquid runs towards the back of the alkali tank, it should pass between the drive base and the alkali tank in order to shorten the pipeline. 2. Five spray pipes: if there is only filtrate from the filter (i.e., the liquid after washing), it can be fed directly into the first pipe, while the second pipe shares both washing water and filtrate. Depending on changes in moisture and salt content, the third, fourth, or fifth rinsing cycle can be activated. Therefore, each spray must be equipped with its own valve for separate control, to ensure that the wash water equivalent remains within a reasonable range. 3. Regarding the position of the spray nozzles in each group, in principle, the liquid from the first wash should be sprayed at the central horizontal position of the drum, that is, at the 0° position. The first and second rows are arranged at an angle of 15°-20° apart, while the subsequent three rows are arranged at an angle of 10°-12° apart. If the drum speed is high, use the lower limit; if it is low, use the upper limit. Depending on the actual operating conditions, the final position must be adjusted multiple times to achieve a satisfactory result. 4. Configuration of the blowing duct: The same main duct is used for blowing regeneration and blowing discharge. Since the air volume and pressure required for unloading are lower than those for regeneration, separate valves should be used for control. Taking a 13.5 m2 filter as an example, a DN80 valve is sufficient for blowing air during regeneration, while a DN50 valve is appropriate for blowing air during unloading. 5. It should be particularly emphasized that in current caustic soda production plants, the overflow openings of the alkali tanks in the filters are generally not used; instead, they are sealed with plugs. To prevent excessive leakage of alkali solution when the liquid level is high, the liquid level is often kept at a moderate level during operation. As a result, the area available for alkali absorption decreases; therefore, increasing the speed of the drum is necessary to maintain compatibility with the alkali generation process during carbonization. This leads to losses due to vacuum exposure, thereby worsening the operational parameters. Therefore, it is required to be equipped with an overflow pipe that can quickly overflow into the alkali tank in case of an instantaneous overload. 6. The water consumption for washing the filter in a car washer should not be underestimated. It is recommended that, during washing, the water be directed to the newly added tank for washed water, to be reused as the liquid for the first spray stage; this is also one of the effective measures for maintaining the balance of the mother liquor and reducing the water equivalent required for washing. Structural Features and Installation/Commissioning Instructions for the Fourth-Generation Vacuum Drum Filter I. Structural Features 1. Distribution Head Section In the improvements made to the fourth-generation design, the distribution head section is the part with the highest level of technical complexity. Key technical aspects such as blowing for unloading, separation of mother liquor from filtrate, and triple sealing of the air distribution disc are all incorporated into the distributor head. 1.1 There are two blowing interfaces on the outer end face of the housing: one is connected to the existing blowing and regeneration system, while the other branch pipe is connected to the blowing discharge port. A fan-shaped element on the drum is used in place of a scraper to remove almost all of the dried alkali cakes adhered to the filter screen. 1.2 The internal vacuum chamber of the distribution head effectively separates the mother liquor from the filtrate, and it corresponds to the five spray nozzles located above the drum. The filtrate and mother liquor with high salt content enter the mother liquor vacuum chamber, and are drawn into the mother liquor vacuum separator from the rear outer edge of the distribution head ； The filtrate with a lower salt content enters the filtrate vacuum chamber and is drawn into the filtrate vacuum separator from the front end of the outer circle of the distribution head. 1.3 A packing seal box is added to the outer circumference of the rotating and stationary misalignment disks. It is equipped with 5 layers of oil-impregnated asbestos packing, and the packing gland can be tightened at any time during operation to ensure no leaks at the gas seal area. 1.4 Three sets of pre-tensioning spring assemblies are added to the housing of the distribution head; their other ends are fixed to the side frame and the alkali tank. The external pre-tensioning, combined with the internal pre-tensioning provided by the existing central shaft springs, ensures that the sealing surfaces of the dynamic and static gas-displacement disks remain in close contact throughout operation, thus maintaining a tight seal. This forms a so-called \"triple seal\" structure with the stuffing box, known as a distribution head. 2. Washing device section: The traditional washing device is a watering trough. To separate the mother liquor from the filtrate, a spray device with grouped nozzles must be used. The spray devices that have become popular in recent years have poor atomization performance, a single structural design, and are unable to make extensive adjustments in position based on changes in crystallization conditions or rotation speed. The spray device of the fourth-generation vacuum drum filter allows for three-dimensional adjustment and positioning between each spray tube and between the nozzles and the alkali cakes; the support plate also serves as a splash guard. It is important to be able to select nozzles of different designs based on factors such as the cleanliness of the wash water, the height of the wash tank, the flow rates of the filtrate recovered by the filter and that recovered by the centrifuge, as well as the crystal content, so as to enable this spraying device, which is superior to traditional wash tanks, to perform a more effective cleaning function. 3. Transmission mechanism: Traditional large gears are required to drive the pressure rollers, whose outer diameter is larger than that of the drum. However, the fourth-generation filter takes advantage of a deeper understanding of the function of these pressure rollers by using passive pressure rollers that reduce weight. As a result, the large gears can be significantly reduced in size; together with the smaller gears, they are enclosed within a gear protection cover filled with oil, which keeps the meshing tooth surfaces lubricated with a thin layer of oil and prevents erosion by washing water, alkaline solutions, and alkaline dust. This also eliminates the need for separate pre-tensioning springs for the distribution head. It should be noted that, based on tests conducted at multiple renovation sites, the current consumption of the fourth-generation filter unit actually decreased by 1–2 A. 4. Mixing device section: An external curved-arm structure is adopted to avoid the drawback of the internal eccentric wheel structure, where the lubricating grease falls into the alkali tank. Moreover, by eliminating the vulnerable eccentric wheel mechanism, the operation becomes smoother and more reliable. It is highly praised by users. At the same time, the mixing device is equipped with variable-frequency speed control; during operation at high liquid levels, the mixing frequency is reduced, thereby eliminating fluctuations and splashing at the liquid surface. Not only was the alkali absorption area expanded and the rotation speed reduced, but the process parameters were also improved. 5. The drum and air distribution shaft section: The inclusion of functions such as air blowing for unloading material and the separation of mother liquor from filtrate necessarily occupies a portion of the dehydration and drying area. Therefore, it is necessary to redistribute the air flow; by increasing the number of fan-shaped sections while ensuring sufficient circulation area, the goal is to address the technical issue of reduced drying area caused by insufficient vacuum and air sealing areas. Another major change involves redesigning the drum channels, which have remained unchanged for decades; the slope of these channels is increased, the length of the flow path is reduced, and the surfaces of the channels as well as the welds are thoroughly polished. It prevents the accumulation of fine crystals, reduces the residence time of the mother liquor in the drum and the air-displacement shaft at high rotational speeds, thereby creating conditions for the effective separation of the mother liquor from the filtrate. 6. Selection and fixation of the filter mesh: Three types of meshes with different mesh sizes – 316L stainless steel backing mesh, filter mesh, and protective mesh – are woven together to form a \"three-in-one\" long mesh, and the number of times it needs to be fixed onto the drum is reduced from 6 to 2. Ensure the net is always laid evenly and tightly. Softer stainless steel wire after \"hydro-quenching\" is used, and the flange surfaces that protrude on both sides of the drum are removed and replaced with grooves. The steel wire mesh does not accumulate when inserted into the groove. The steel wires at the start and end of the winding are both secured using a \"double safety\" method. Ensure it does not loosen during long-term operation, and prevent axial sliding and tearing of the filter screen. 7. Selection of the structure and material for the alkali tank: The fourth-generation vacuum drum filter replaces the cast-iron alkali tanks that have been in use for decades with fully welded stainless steel tanks, thereby eliminating the problems associated with severe rust and aging of the bolts and gaskets used to connect the side panels and frames, as well as the risk of leaks. There is also no accumulation of large amounts of rust debris in the alkali tank; not only is the operating environment improved, but the impurity content in the alkali cake is also significantly reduced. In addition, an anti-splash baffle with a slope and widened to fit closely against the drum has been installed beneath the scraper seat; the drum itself has been further widened to prevent the splashing of alkaline solution at the discharge point. The overflow port located at the back of the alkali tank has been raised and widened horizontally, which allows for stable operation at a high liquid level while ensuring rapid overflow. II. Several issues to note during installation and commissioning The requirements for the installation and commissioning of the fourth-generation vacuum drum filter are outlined in the software materials provided with the equipment; here, the following points are particularly emphasized: 1. Regarding the setting of the air-blowing unloading function, it is essential to ensure that the installation angles of the left and right air nozzles are correct and consistent. If the load test can be verified from two aspects: ① If the filter cake in a single sector begins to blow off and detach exactly as it reaches the scraper, it indicates that the installation angle is correct ； ②If the filter cakes on the left and right sides of the drum fall off simultaneously along the same line, it indicates that the installation angles of the air nozzles on the left and right are identical. Therefore, the pipe connected to the wrong air header can be fixed only after confirmation. 2. After confirming the angles of the left and right air-displacement nozzles, a bracket that allows for slight upward and downward adjustment should be installed. This bracket should be mounted on the rigid pipe adjacent to the vacuum separator for the wash liquid downstream of the air-displacement nozzles, in order to prevent the nozzles from rotating during operation and to support their weight. 3. Five sets of washing pipes should be installed at the upper part or on one side of the drum; each set must be equipped with its own valve for separate control. When connected to the pressure-resistant rubber hoses that come as part of the setup, the rubber hoses need to have sufficient length to move along with the position of the spraying pipes. 4. To prevent overflow due to a sudden rise in the liquid level, or failures caused by an excessively low liquid level that increases the stirring load, it is recommended to install devices for monitoring the liquid level in the alkali tank and for providing automatic alarms at the filtration station, such as ultrasonic level sensors, in order to adjust the liquid level to an appropriate range in a timely manner. 5. Before the load test, all newly installed equipment and pipelines such as the drum flow channels, washing pipes, vacuum pipes, blowing pipes, and separators in the alkali treatment system must be thoroughly flushed. Filters should then be installed. In particular, when using nozzles, the washing pipes, water tanks, and filtrate tanks need to be flushed repeatedly for an extended period of time; only after it is confirmed that there are no residues, rust, or impurities can the spray pipes be connected. It is necessary to enter the bottom of the alkali tank for a thorough inspection and remove all impurities. 6. Blowing for unloading and blowing for regeneration must be equipped with separate valves to individually control the air volume and air pressure. 7. The area around the platform at the back of the alkali tank should be widened to provide an operating platform, along with staircases that facilitate workers’ access up and down. This makes it easier to adjust the amount of washing fluid used, and it also helps workers to detect clogged nozzles more promptly. It is recommended to have spare nozzles available at the filtration station, as well as simple acid cleaning facilities, so that clogged nozzles can be quickly replaced and cleaned for use later. This is the key to whether the spraying device can operate effectively over the long term. 8. In principle, the first fan-shaped nozzle should be positioned at the horizontal position (0°) of the drum or slightly higher, with the jet flowing at an upward angle relative to the surface of the alkali cake, in order to prevent splashing and facilitate absorption. The spacing between the second nozzle and the others should be slightly larger, while the remaining three nozzles can be arranged at equal intervals. It is advisable to keep the distance between the nozzle and the alkali cake at around 100 mm. 9. During the load test, if lumps appear on the surface of the filter cake, it indicates that the seal of the air distribution disc is not tight; attention should be paid to grinding the sealing surfaces as required. 10. The commissioning and operation of the lubricating oil pump must be carried out strictly in accordance with the instructions; the oil must be clean, the oil level in the tank must not be lower than 1/2, and attention should be paid to the direction of rotation. 11. The high yield achieved by simply increasing the rotation speed is achieved at the expense of process parameters; it not only shortens the drying time but also results in an increased amount of washed liquid being recovered, along with a sharp rise in Cl_ content, thereby reducing the quality of the recovered product. Therefore, it is recommended that the maximum rotation speed be ≤2.2 r/min. 12. The rotation speed of the stirring device should also be adjusted in line with the speed of the main machine, by modifying the stirring frequency as needed based on variations in liquid level, concentration, and crystal quality. When operating at a high liquid level, to maintain stability of the liquid level and prevent splashing of alkaline solution at the scraper, the frequency should be reduced promptly. At low liquid levels, it should be increased to prevent sediment accumulation. 13. To prevent poor sealing of the air distribution disc from blocking the air outlets, it is recommended to install water pipes at the bends of the two air outlet connections, equipped with valves for control, so that water can be used for flushing when necessary.
Based on the actual conditions of various manufacturers, our company has designed and produced alkali filtration machines in seven different sizes: 6.5 m2, 8 m2, 10 m2, 13.5 m2, 17 m2, 20 m2, and 23 m2. The models and technical parameters of the vacuum drum filtration machines produced by our company are shown in the table below:
| Specification | Characteristics |
|--------------|-----------------|
| 6.5 m2 | |
| 8 m2 | |
| 10 m2 | |
| 13.5 m2 | |
| 17 m2 | |
| 20 m2 | |
| 23 m2 | |
**Filtering area:** m2 – 6.5, 8, 10, 13.5, 17, 20, 23
**Production capacity:** t/day – 170, 240, 280, 360, 450–540, 550–650, 620–740
**Vacuum level:** MPa – ≥400, ≥400, ≥400, ≥400, ≥400, ≥400, ≥400
**Material moisture content:** % – ≤18%, ≤18%, ≤18%, ≤18%, ≤18%, ≤18%, ≤18%
**Drum rotation speed:** rpm – 1.1–3.6, 1.1–3.6, 1.1–3.6, 1.1–3.6, 1.1–3.3, 1.1–3.3, 1.1–3.57
**Stirring speed:** rpm – 33.7, 33.7, 33.7, 33.7, 33.7, 33.7, 23.8
**Drum diameter:** mm – Φ2250, Φ2250, Φ2250, Φ2250, Φ2600, Φ2600, Φ2600
**Drum length:** mm – 930, 1150, 1420, 1910, 2080, 2420, 2820
**Main material:** 316L/HT200
3. Product Features
3.1 The drum features a hollow structure, which effectively eliminates the dead zones that existed in previous designs. This increases the cross-sectional area of the gas channels, reduces gas resistance within these channels, thereby ensuring smoother flow and more uniform alkali absorption. Thus, **the production capacity of the alkali filtration machine was increased, and the washing water equivalent was reduced. 3.2 The distribution head is made of 316L ultra-low carbon stainless steel, offering significant improvements over the original HT200 distribution head in terms of corrosion resistance, weight, and maintenance. A rational arrangement of the fixed air-blocking zone, blowing zone, blowing and discharging zone, filtration zone, dehydration and drying zone, washing zone, etc., has a significant impact on increasing productivity and reducing moisture content. In this regard, we have accumulated extensive experience in optimizing the allocation of various areas to achieve the best results. By improving the internal structure of the drum and enlarging the diameter of the shafts responsible for air flow, we ensure more uniform alkali absorption and smoother flow pathways. 3.3 To meet the special needs of users, we adjust the material of the fixed air-shifting disc according to their requirements; the current materials for such discs include polytetrafluoroethylene, graphite, and modified nylon. Three different materials can be selected according to the user’s needs to suit various operating conditions. 3.4 A two-roller system was adopted to modify the original structure, and by improving the design of the rollers, the moisture content of the heavy alkali was effectively reduced. The pressure roller adjustment spring is placed within the sealing structure, making it both simple and practical; this completely solves the major problems of complex design, poor performance, and frequent failures that existed in previous designs. 3.5 Uses a spray device instead of a washing tank to achieve more even washing. The cleaning effect is significant, water usage is **reduced**, and the salt content is improved. In the design of the spraying system, 5 spraying units are typically installed. Each of these units can be adjusted up, down, forward, and backward, and they can also be turned on or off as needed. Depending on the conditions of the filter cake, the distance at which water is sprayed onto the filter cake can be adjusted in order to reduce the generation of water vapor. It is also very convenient to adjust by turning on or off the number of spray nozzles, depending on the salt and moisture content of the filter cake. 3.6 To improve the working environment and prevent liquid splashing, an all-round liquid barrier has been installed between the side frame and the drum. 3.7 The stirring mechanism of the original alkali filtration machine was one that featured an eccentric wheel structure mounted on the alkali solution tank. The most significant drawback of this design was that the grease used to lubricate the eccentric wheel components would fall into the alkali solution tank, contaminating the quality of the mother liquor and thus affecting the quality of the caustic soda. The traditional approach to solving this problem is to add a skeleton seal to the eccentric wheel assembly, but this method does not completely resolve the issue of grease contamination in the mother liquor. The external mixing device we used completely solved the problem of oil contamination in the mother liquor. 3.8 The main body of the equipment is entirely made of ultra-low carbon stainless steel, which enhances its corrosion resistance and is highly beneficial for ensuring the quality of the alkali cake. 3.9 The main drive has been changed from a conventional speed-regulating motor to one controlled by an inverter; various parameters related to the motor’s operation can be displayed clearly, making operation more convenient. 3.10 Thanks to mass production, aside from the 16.5 m2 and 20 m2 soda ash filters which form a series that can be interchanged, the spare parts and replacement components for the other models of soda ash filters can almost all be replaced, which provides great convenience for manufacturers. Adhering to the principle of \"quality first, optimized management, technological innovation, and customer satisfaction,\" our company upholds the corporate philosophy of \"putting people first, pursuing innovation, expanding into both domestic and international markets, and creating high-quality brands.\" We are committed to serving our customers wholeheartedly, constantly exploring new possibilities, and striving for improvement in order to make the TB-type alkali filter machines even better. Description of the process configuration for the fourth-generation vacuum drum filter. Thanks to the use of latest technologies in the field of filter design and manufacturing, such as air-blown unloading, separation of mother liquor from filtrate, spray washing, triple sealing at the air inlet, and fully sealed transmission systems, the fourth-generation vacuum drum filter features several changes and adjustments compared to traditional filtering processes. If properly configured, the technical advantages of the fourth-generation filter can be fully realized, resulting in significant improvements and enhancements in various technical parameters such as energy consumption, process costs, soda ash quality, and the capacity of subsequent production equipment. I. Requirements for process operation conditions 1. Since the blowing-unloading technology is employed, the same air source is used for both blowing regeneration and blowing unloading, which results in a certain consumption of air volume and pressure. Therefore, the selection of the blower requires a slight increase over the conventional standard flow rate of 50 Nm3/t of alkali; the gauge pressure in the main pipeline should be around 60 KPa. The head pressure of the vehicle in operation should not be lower than 25 KPa. 2. The mother liquor and filtrate separation technology enables a true separation between the alkali absorption zone and the washing and drying zone, with each going into its respective vacuum separator for mother liquor and filtrate. The third-generation filter does not have reverse flow recovery washing of the filtrate, nor does it have a filtrate vacuum separator. Therefore, the selection requirements for vacuum pumps generally require an increase from the conventional standard flow rate of 200 Nm3/t of alkali to around 250 Nm3/t of alkali. The inlet pressure should be ≥56 KPa, and the vacuum level at the locomotive during operation should be ≥40 KPa. 3. Difference between nozzle-based atomized washing and sink-based washing: First, the nozzle must have sufficient pressure; the height difference between the water tank and the alkali tank should be ≥10m to ensure an effective atomization effect ； Secondly, different types of nozzles can be selected to facilitate the spraying of various cleaning solutions. In a process where vacuum filters are followed by centrifuges to further reduce the moisture and salt content in the alkaline solution, the liquid resulting from the centrifuge can be used as a second cleaning solution; it can be recovered together with the liquid from the first filter using a pump (as shown in the diagram), and the flow rate can be adjusted via separate valves ； Thirdly, the installation positions of the five spray nozzles can be optimized and combined according to actual operating conditions in order to achieve the best process parameters; in particular, changes in aspects such as the concentration of the carbonization effluent, the quality of the crystals, and the rotation speed of the filter are directly related to the installation positions of these spray nozzles. The first and second nozzles use flat-mouthed fan-shaped nozzles that are resistant to clogging; it is required that the pressure at each nozzle be no less than 50 KPa, with the main pipe pressure being no lower than 1 bar. II. Requirements for the selection of supporting facilities 1. The structure of the new post-washing liquid separator should be the same as that of the mother liquor separator; if they are located on the same floor (the fourth floor), a separator with a larger capacity (around 3 m3) can be chosen and placed between the two mother liquor separators ； If installation is difficult, it can also be placed on the lower floor (the third floor), divided into two sections on the left and right, with each section having a volume of 1.5–2 m3. 2. The newly added post-washing liquid tank is a storage tank equipped with a stirrer; its capacity should be greater than 8 m3 and its height should be no less than 3 m. Water used for car washing with alkaline solutions or other mild liquids can also be recycled as washing fluid to maintain equilibrium in the mother liquor. 3. The newly added post-washing liquid pump should be selected appropriately based on the capacity of the post-washing liquid tank and the height difference of the alkali tank; a recommended flow rate is 8–10 m3/h, with a head of ≥30 m. 4. The existing mother liquor vacuum separator can still be used. III. Requirements for process piping: 1. The mother liquor vacuum pipes and the vacuum pipes for the washed liquid should be installed at an angle pointing toward the separator, as short as possible, to prevent blockages caused by the accumulation of alkali; valves should be installed on each of these pipes to control the amount of vacuum. If the vacuum tube for the left-side wash liquid runs towards the back of the alkali tank, it should pass between the drive base and the alkali tank in order to shorten the pipeline. 2. Five spray pipes: if there is only filtrate from the filter (i.e., the liquid after washing), it can be fed directly into the first pipe, while the second pipe shares both washing water and filtrate. Depending on changes in moisture and salt content, the third, fourth, or fifth rinsing cycle can be activated. Therefore, each spray must be equipped with its own valve for separate control, to ensure that the wash water equivalent remains within a reasonable range. 3. Regarding the position of the spray nozzles in each group, in principle, the liquid from the first wash should be sprayed at the central horizontal position of the drum, that is, at the 0° position. The first and second rows are arranged at an angle of 15°-20° apart, while the subsequent three rows are arranged at an angle of 10°-12° apart. If the drum speed is high, use the lower limit; if it is low, use the upper limit. Depending on the actual operating conditions, the final position must be adjusted multiple times to achieve a satisfactory result. 4. Configuration of the blowing duct: The same main duct is used for blowing regeneration and blowing discharge. Since the air volume and pressure required for unloading are lower than those for regeneration, separate valves should be used for control. Taking a 13.5 m2 filter as an example, a DN80 valve is sufficient for blowing air during regeneration, while a DN50 valve is appropriate for blowing air during unloading. 5. It should be particularly emphasized that in current caustic soda production plants, the overflow openings of the alkali tanks in the filters are generally not used; instead, they are sealed with plugs. To prevent excessive leakage of alkali solution when the liquid level is high, the liquid level is often kept at a moderate level during operation. As a result, the area available for alkali absorption decreases; therefore, increasing the speed of the drum is necessary to maintain compatibility with the alkali generation process during carbonization. This leads to losses due to vacuum exposure, thereby worsening the operational parameters. Therefore, it is required to be equipped with an overflow pipe that can quickly overflow into the alkali tank in case of an instantaneous overload. 6. The water consumption for washing the filter in a car washer should not be underestimated. It is recommended that, during washing, the water be directed to the newly added tank for washed water, to be reused as the liquid for the first spray stage; this is also one of the effective measures for maintaining the balance of the mother liquor and reducing the water equivalent required for washing. Structural Features and Installation/Commissioning Instructions for the Fourth-Generation Vacuum Drum Filter I. Structural Features 1. Distribution Head Section In the improvements made to the fourth-generation design, the distribution head section is the part with the highest level of technical complexity. Key technical aspects such as blowing for unloading, separation of mother liquor from filtrate, and triple sealing of the air distribution disc are all incorporated into the distributor head. 1.1 There are two blowing interfaces on the outer end face of the housing: one is connected to the existing blowing and regeneration system, while the other branch pipe is connected to the blowing discharge port. A fan-shaped element on the drum is used in place of a scraper to remove almost all of the dried alkali cakes adhered to the filter screen. 1.2 The internal vacuum chamber of the distribution head effectively separates the mother liquor from the filtrate, and it corresponds to the five spray nozzles located above the drum. The filtrate and mother liquor with high salt content enter the mother liquor vacuum chamber, and are drawn into the mother liquor vacuum separator from the rear outer edge of the distribution head ； The filtrate with a lower salt content enters the filtrate vacuum chamber and is drawn into the filtrate vacuum separator from the front end of the outer circle of the distribution head. 1.3 A packing seal box is added to the outer circumference of the rotating and stationary misalignment disks. It is equipped with 5 layers of oil-impregnated asbestos packing, and the packing gland can be tightened at any time during operation to ensure no leaks at the gas seal area. 1.4 Three sets of pre-tensioning spring assemblies are added to the housing of the distribution head; their other ends are fixed to the side frame and the alkali tank. The external pre-tensioning, combined with the internal pre-tensioning provided by the existing central shaft springs, ensures that the sealing surfaces of the dynamic and static gas-displacement disks remain in close contact throughout operation, thus maintaining a tight seal. This forms a so-called \"triple seal\" structure with the stuffing box, known as a distribution head. 2. Washing device section: The traditional washing device is a watering trough. To separate the mother liquor from the filtrate, a spray device with grouped nozzles must be used. The spray devices that have become popular in recent years have poor atomization performance, a single structural design, and are unable to make extensive adjustments in position based on changes in crystallization conditions or rotation speed. The spray device of the fourth-generation vacuum drum filter allows for three-dimensional adjustment and positioning between each spray tube and between the nozzles and the alkali cakes; the support plate also serves as a splash guard. It is important to be able to select nozzles of different designs based on factors such as the cleanliness of the wash water, the height of the wash tank, the flow rates of the filtrate recovered by the filter and that recovered by the centrifuge, as well as the crystal content, so as to enable this spraying device, which is superior to traditional wash tanks, to perform a more effective cleaning function. 3. Transmission mechanism: Traditional large gears are required to drive the pressure rollers, whose outer diameter is larger than that of the drum. However, the fourth-generation filter takes advantage of a deeper understanding of the function of these pressure rollers by using passive pressure rollers that reduce weight. As a result, the large gears can be significantly reduced in size; together with the smaller gears, they are enclosed within a gear protection cover filled with oil, which keeps the meshing tooth surfaces lubricated with a thin layer of oil and prevents erosion by washing water, alkaline solutions, and alkaline dust. This also eliminates the need for separate pre-tensioning springs for the distribution head. It should be noted that, based on tests conducted at multiple renovation sites, the current consumption of the fourth-generation filter unit actually decreased by 1–2 A. 4. Mixing device section: An external curved-arm structure is adopted to avoid the drawback of the internal eccentric wheel structure, where the lubricating grease falls into the alkali tank. Moreover, by eliminating the vulnerable eccentric wheel mechanism, the operation becomes smoother and more reliable. It is highly praised by users. At the same time, the mixing device is equipped with variable-frequency speed control; during operation at high liquid levels, the mixing frequency is reduced, thereby eliminating fluctuations and splashing at the liquid surface. Not only was the alkali absorption area expanded and the rotation speed reduced, but the process parameters were also improved. 5. The drum and air distribution shaft section: The inclusion of functions such as air blowing for unloading material and the separation of mother liquor from filtrate necessarily occupies a portion of the dehydration and drying area. Therefore, it is necessary to redistribute the air flow; by increasing the number of fan-shaped sections while ensuring sufficient circulation area, the goal is to address the technical issue of reduced drying area caused by insufficient vacuum and air sealing areas. Another major change involves redesigning the drum channels, which have remained unchanged for decades; the slope of these channels is increased, the length of the flow path is reduced, and the surfaces of the channels as well as the welds are thoroughly polished. It prevents the accumulation of fine crystals, reduces the residence time of the mother liquor in the drum and the air-displacement shaft at high rotational speeds, thereby creating conditions for the effective separation of the mother liquor from the filtrate. 6. Selection and fixation of the filter mesh: Three types of meshes with different mesh sizes – 316L stainless steel backing mesh, filter mesh, and protective mesh – are woven together to form a \"three-in-one\" long mesh, and the number of times it needs to be fixed onto the drum is reduced from 6 to 2. Ensure the net is always laid evenly and tightly. Softer stainless steel wire after \"hydro-quenching\" is used, and the flange surfaces that protrude on both sides of the drum are removed and replaced with grooves. The steel wire mesh does not accumulate when inserted into the groove. The steel wires at the start and end of the winding are both secured using a \"double safety\" method. Ensure it does not loosen during long-term operation, and prevent axial sliding and tearing of the filter screen. 7. Selection of the structure and material for the alkali tank: The fourth-generation vacuum drum filter replaces the cast-iron alkali tanks that have been in use for decades with fully welded stainless steel tanks, thereby eliminating the problems associated with severe rust and aging of the bolts and gaskets used to connect the side panels and frames, as well as the risk of leaks. There is also no accumulation of large amounts of rust debris in the alkali tank; not only is the operating environment improved, but the impurity content in the alkali cake is also significantly reduced. In addition, an anti-splash baffle with a slope and widened to fit closely against the drum has been installed beneath the scraper seat; the drum itself has been further widened to prevent the splashing of alkaline solution at the discharge point. The overflow port located at the back of the alkali tank has been raised and widened horizontally, which allows for stable operation at a high liquid level while ensuring rapid overflow. II. Several issues to note during installation and commissioning The requirements for the installation and commissioning of the fourth-generation vacuum drum filter are outlined in the software materials provided with the equipment; here, the following points are particularly emphasized: 1. Regarding the setting of the air-blowing unloading function, it is essential to ensure that the installation angles of the left and right air nozzles are correct and consistent. If the load test can be verified from two aspects: ① If the filter cake in a single sector begins to blow off and detach exactly as it reaches the scraper, it indicates that the installation angle is correct ； ②If the filter cakes on the left and right sides of the drum fall off simultaneously along the same line, it indicates that the installation angles of the air nozzles on the left and right are identical. Therefore, the pipe connected to the wrong air header can be fixed only after confirmation. 2. After confirming the angles of the left and right air-displacement nozzles, a bracket that allows for slight upward and downward adjustment should be installed. This bracket should be mounted on the rigid pipe adjacent to the vacuum separator for the wash liquid downstream of the air-displacement nozzles, in order to prevent the nozzles from rotating during operation and to support their weight. 3. Five sets of washing pipes should be installed at the upper part or on one side of the drum; each set must be equipped with its own valve for separate control. When connected to the pressure-resistant rubber hoses that come as part of the setup, the rubber hoses need to have sufficient length to move along with the position of the spraying pipes. 4. To prevent overflow due to a sudden rise in the liquid level, or failures caused by an excessively low liquid level that increases the stirring load, it is recommended to install devices for monitoring the liquid level in the alkali tank and for providing automatic alarms at the filtration station, such as ultrasonic level sensors, in order to adjust the liquid level to an appropriate range in a timely manner. 5. Before the load test, all newly installed equipment and pipelines such as the drum flow channels, washing pipes, vacuum pipes, blowing pipes, and separators in the alkali treatment system must be thoroughly flushed. Filters should then be installed. In particular, when using nozzles, the washing pipes, water tanks, and filtrate tanks need to be flushed repeatedly for an extended period of time; only after it is confirmed that there are no residues, rust, or impurities can the spray pipes be connected. It is necessary to enter the bottom of the alkali tank for a thorough inspection and remove all impurities. 6. Blowing for unloading and blowing for regeneration must be equipped with separate valves to individually control the air volume and air pressure. 7. The area around the platform at the back of the alkali tank should be widened to provide an operating platform, along with staircases that facilitate workers’ access up and down. This makes it easier to adjust the amount of washing fluid used, and it also helps workers to detect clogged nozzles more promptly. It is recommended to have spare nozzles available at the filtration station, as well as simple acid cleaning facilities, so that clogged nozzles can be quickly replaced and cleaned for use later. This is the key to whether the spraying device can operate effectively over the long term. 8. In principle, the first fan-shaped nozzle should be positioned at the horizontal position (0°) of the drum or slightly higher, with the jet flowing at an upward angle relative to the surface of the alkali cake, in order to prevent splashing and facilitate absorption. The spacing between the second nozzle and the others should be slightly larger, while the remaining three nozzles can be arranged at equal intervals. It is advisable to keep the distance between the nozzle and the alkali cake at around 100 mm. 9. During the load test, if lumps appear on the surface of the filter cake, it indicates that the seal of the air distribution disc is not tight; attention should be paid to grinding the sealing surfaces as required. 10. The commissioning and operation of the lubricating oil pump must be carried out strictly in accordance with the instructions; the oil must be clean, the oil level in the tank must not be lower than 1/2, and attention should be paid to the direction of rotation. 11. The high yield achieved by simply increasing the rotation speed is achieved at the expense of process parameters; it not only shortens the drying time but also results in an increased amount of washed liquid being recovered, along with a sharp rise in Cl_ content, thereby reducing the quality of the recovered product. Therefore, it is recommended that the maximum rotation speed be ≤2.2 r/min. 12. The rotation speed of the stirring device should also be adjusted in line with the speed of the main machine, by modifying the stirring frequency as needed based on variations in liquid level, concentration, and crystal quality. When operating at a high liquid level, to maintain stability of the liquid level and prevent splashing of alkaline solution at the scraper, the frequency should be reduced promptly. At low liquid levels, it should be increased to prevent sediment accumulation. 13. To prevent poor sealing of the air distribution disc from blocking the air outlets, it is recommended to install water pipes at the bends of the two air outlet connections, equipped with valves for control, so that water can be used for flushing when necessary.
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