Dedicated lower staggered gas disc for phosphoric acid semi-hydrate-dihydrate process

Abstract

The invention relates to the technical field of semi-hydrated material scaling treatment, and discloses a lower staggered gas disc special for a phosphoric acid semi-hydrated-dihydrated process, the lower staggered gas disc mainly solves the problem of semi-hydrated material scaling through structural innovation, the structure of the lower staggered gas disc comprises a lower staggered gas disc, a lower base plate and a lower flange are fastened and connected together through an inner hexagon screw, and the lower base plate is fixedly connected with the lower flange through an outer hexagon screw. Sealing is carried out through an ultra-high molecular weight polyethylene screw plug; the lower base plate and the lower flange are sealed through an O-shaped sealing ring; an outer collecting tank sealing strip and the outer collecting tank are connected with the lower flange through a fastener to form a sealed filtrate collecting device; the outer collecting tank is connected with an outer ring collecting tank pipe orifice, the inner collecting tank is directly welded on the lower flange, and the inner collecting tank is connected with an inner ring collecting tank pipe orifice. According to the utility model, the problems of easy scaling, difficult cleaning, easy corrosion, low driving efficiency and the like due to blockage of the gas distribution disc in the semi-water and two-water method are effectively solved.

Description

Technical Field

[0001] This invention relates to the field of scaling treatment technology for hemihydrate process materials, specifically to a special lower air plate for the phosphoric acid hemihydrate-dihydrate process. Background Technology

[0002] The domestic phosphate compound fertilizer industry conventionally adopts the dihydrate wet phosphoric acid process. In recent years, the domestic phosphate compound fertilizer industry has been in a period of transformation and upgrading. The hemihydrate-dihydrate wet phosphoric acid process has the advantages of lower energy consumption, higher phosphorus recovery rate and better quality phosphogypsum compared with the traditional dihydrate process. It is the direction for the transformation and upgrading of wet phosphoric acid production. More and more phosphoric acid companies are investing in the construction of new production lines or upgrading the existing dihydrate process. As a result, the hemihydrate rotary vacuum filter has emerged.

[0003] A rotary table filter is a continuous filtration device capable of rapidly separating solids and liquids. Under vacuum, the filtrate passes through the filter cloth, filter discs, liquid guide pipes, vacuum hoses, and upper and lower air discs into the gas-liquid separation system. In hemihydrate-dihydrate wet-process phosphoric acid plants, the filtrate from the hemihydrate unit has high temperature, high acid concentration, high viscosity, and a large amount of fluorine release. Under vacuum, the sudden cooling effect causes a large amount of cold air to enter the equipment, rapidly lowering the filtrate temperature. This easily leads to the precipitation of fluorosilicates NaSiF6 and K2SiF6, which, together with fine gypsum crystals and dispersed mud passing through the filter, form a dense scale. Especially with low- and medium-grade phosphate rock, due to its high impurity content, scaling easily occurs during long-term operation, affecting filtration. In severe cases, it can completely block the lower air disc cavity, resulting in long maintenance and cleaning cycles and low start-up efficiency. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by designing a dedicated gas separator for the hemihydrate-dihydrate phosphoric acid process. This gas separator, through structural innovation, effectively solves problems such as clogging, scaling, difficulty in cleaning, corrosion, and low start-up efficiency associated with the hemihydrate-dihydrate process's gas separator. The specific technical solution is as follows: A special lower gas tray for the phosphoric acid hemihydrate-dihydrate process includes a lower gas tray, a lower gasket plate and a lower flange fastened together by hexagonal socket screws and sealed by polyethylene plugs; the lower gasket plate and the lower flange are sealed by an O-ring seal, and the outer collection tank sealing strip and the outer collection tank are connected to the lower flange by fasteners to form a sealed filtrate collection device; the outer collection tank is located on the lower plane of the lower flange and is connected to an outer ring collection tank port, and the inner collection tank is directly welded to the lower flange and is connected to an inner ring collection tank port; The steam ring pipe is fixed together with the U-bolt and the lower steam plate by an internal steam ring pipe bracket welded to the outer collection tank; the steam ring pipe, clamps and clamp sealing rings, internal steam short pipe, cleaning hole cover and internal steam ring pipe inlet form an internal steam channel; The jacketed insulation water outlet is located 13° counterclockwise directly above the jacketed insulation hot water inlet, and a baffle is installed between the jacketed insulation water outlet and the inlet to ensure that the insulation hot water forms a complete loop; the connecting support is the mounting support of the lower air plate, which is fixed together with the cantilever beam on the circumference of the central column by fasteners; the inner and outer adjusting ring plates are welded to the inner and outer rings of the filtrate straight section. Connecting plate I is welded to the bottom of the lower air plate, and connecting plate II is welded to the drain ring pipe. They are fixed together with the lower air plate by fasteners. The cone hopper drain elbow is the drain pipe below each cone hopper jacket. One end of the wide-style internal thread ball valve is connected to the cone hopper drain elbow, and the other end is connected to the drain short connector. The drain ring pipe is connected to the outlet of each cone bucket jacket via acid-resistant rubber tubing and European-style high-strength clamps.

[0005] Preferably, the outer collection tank is also equipped with an outer collection tank connector, which is a short connector of the outer collection tank. The outlets of the inner collection tank and the outer collection tank are combined into one pipe through the outer collection tank connector. After scale buildup occurs, the interior can be cleaned by disassembling the transparent PVC steel wire hose, German-style hose clamp and outer collection tank connector.

[0006] Preferably, the adjustable partition includes an adjustable partition fixing plate, fasteners, a left adjustable partition, and a right adjustable partition. The adjustable partition fixing plate is fixed to the inner and outer adjusting ring plates with hexagonal bolts. The left and right adjustable partitions are connected to the adjustable partition fixing plate as a whole with fasteners, used to adjust the angle of each zone. The lower air plate is divided into a slag flushing water zone, a primary filtrate zone, a filtrate zone, a first wash water zone, and a second wash water zone. The adjustment angle for the primary filtrate zone is 8°, and the adjustment angle for the other zones is 20°.

[0007] Preferably, the height of the inner collection tank is 10mm lower than the upper plane of the lower flange, and the stainless steel wire and acid-resistant rubber plate are both raised by 120mm.

[0008] Preferably, the cleaning hole cover and the lower air plate are sealed with an acid-resistant rubber gasket; the cleaning hole cover adopts a square box shape with an 8° taper.

[0009] Preferably, the filtrate straight section is the straight section of the lower air disc filtration channel, the filtrate cone section is the cone body section of the lower air disc filtration channel, and the outer ring insulation jacket, inner ring insulation spacer, jacket insulation base plate and cone side insulation jacket plate constitute the insulation jacket of the filtrate channel; the outer ring aluminum foil composite heat insulation cotton and the inner ring aluminum foil composite heat insulation cotton are fixed to the jacket by heat dry adhesive and insulation nails.

[0010] Preferably, the filtrate outlet is the outlet of the filtrate channel, and the shape of the filtrate outlet is set as a trumpet shape; the PTFE liner is a PTFE plate lining the filtrate channel with a thickness of about 5mm.

[0011] Preferably, the hot water inlet of the jacket is equipped with an electric contact pressure gauge to detect the pressure inside the jacket and transmit it to the control unit.

[0012] Preferably, the inner and outer adjusting ring plates are annular plates with a ring of holes for adjusting the adjustable partition. The connecting plate II has elongated holes to facilitate adjustment during installation and compensate for errors caused by manufacturing precision. Compared with the closest existing technology, the technical solution provided by the present invention has the following beneficial effects: 1. The lower air plate of the present invention is equipped with a heat preservation device; (1) a fully enclosed jacket is set in the straight section and the cone part of the lower air plate, and 95°C hot water is introduced into the jacket, and heat preservation cotton is filled between the cones; (2) a layer of 40mm thick single-sided adhesive aluminum foil composite heat insulation cotton is attached to the inner and outer layers of the jacket, and heat preservation nails are used for reinforcement and fixation; (3) steam is introduced into the filtrate flow channel; through the above three heat preservation measures, the heat loss of the filtrate is greatly reduced, the solid precipitation is reduced, and the formation of scale is greatly reduced.

[0013] 2. The present invention extends the service life of the equipment; (1) By changing the original horizontal flow channel of the lower air plate to a cone shape, the service life is greatly extended and the start-up rate of the equipment is improved; (2) A drain port with a valve is configured at the lowest point of the insulation jacket at the bottom of each cone, which can drain the sewage separately. At the same time, a circular pipe is used to connect the drain ports into a main pipe, which makes it easy to drain the internal insulation water when the equipment is stopped for a long time, thus extending the service life of the equipment.

[0014] 3. The present invention improves maintenance efficiency; (1) The filtrate outlet is set in the form of a funnel, which makes it easier to clean the internal cavity from the bottom during the overhaul; (2) A detachable cleaning hole is opened for each outlet on the straight section of the lower air plate, which makes it easier to clean online when the machine is stopped, and greatly improves the speed of equipment maintenance and cleaning.

[0015] 4. This invention facilitates customer piping; (1) By configuring an internal steam inlet at each cleaning port, the internal channel temperature is further increased, and a circular pipe is used to connect each steam inlet into a main pipe, which is convenient for customers to install piping on site; (2) The inner and outer collection tanks are connected by pipes, and only one drain port is set, which greatly facilitates customer piping.

[0016] 5. This invention reduces scaling and improves corrosion resistance; the entire lower air plate is lined with 5mm thick PTFE, which further reduces scaling inside the lower air plate and improves corrosion resistance.

[0017] 6. The process scheme of this invention maintains a high consistency rate; it employs a specially designed adjustable baffle to adjust the angle of each area of ​​the lower air plate, ensuring consistency with the on-site process scheme. Maintain consistency. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the main structure of the lower gas tray for the phosphoric acid hemihydrate-dihydrate process of the present invention. Figure 2 This is a top view schematic diagram of the overall structure of the lower gas tray for the phosphoric acid hemihydrate-dihydrate process of the present invention; Figure 3 This is a side view of the lower gas tray specifically designed for the phosphoric acid hemihydrate-dihydrate process of the present invention. Figure 4 This is a schematic diagram of the internal and external collection tank structure of the present invention; Figure 5 This is a schematic diagram of the connecting plate structure of the present invention; Figure 6 This is a schematic diagram of the adjustable partition structure of the present invention.

[0019] The components include: 1. Lower gasket; 2. Lower flange; 3. Collection tank sealing strip; 4. Outer collection tank; 5. O-ring seal; 6. Ultra-high molecular weight polyethylene screw plug; 7. Inner collection tank; 8. Stainless steel wire; 9. Acid-resistant rubber sheet; 10. U-bolt; 11. Steam ring pipe; 12. Internal steam ring pipe support; 13. Clamp; 14. Internal steam short pipe; 15. Acid-resistant rubber gasket; 16. Cleaning hole cover; 17. Filtrate straight section; 18. Outer ring aluminum foil composite thermal insulation cotton; 19. Outer ring thermal insulation jacket; 20. Filtrate conical section; 21. Insulated hot water discharge port; 22. Filtrate outlet; 23. Jacketed insulation base plate; 24. Inner ring thermal insulation spacer; 25. Inner ring aluminum foil composite thermal insulation cotton; 26. Jacketed insulation water outlet; 27. Pressure gauge with live contact; 28. Jacketed insulation hot water inlet; 29. ​​Connecting support; 30. Internal and external adjustment. 31. Adjustable baffle plate; 32. Outer ring collection tank inlet; 33. Inner ring collection tank inlet; 34. Outer collection tank connecting pipe; 35. Transparent PVC steel wire hose; 36. German-style hose clamp; 37. Connecting plate I; 38. Connecting plate II; 39. Conical hopper drain elbow; 40. Guangdong-style internal thread ball valve; 41. Acid-resistant rubber hose; 42. European-style strong clamp; 43. Drainage ring pipe; 44. Conical side insulation jacket plate; 45. Jacket bottom plate; 46. Internal steam ring pipe inlet; 47. PTFE bushing; 48. Drainage short connector; 31-1. Adjustable baffle plate fixing plate; 31-2. Fastener; 31-3. Adjustable baffle left baffle plate; 31-4. Adjustable baffle right baffle plate. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Please see Figure 1-3 This invention provides a technical solution: a dedicated flow channel for the phosphoric acid hemihydrate-dihydrate process, comprising a flow channel with a conical hopper-shaped horizontal flow path, the hopper being integrally formed from stainless steel plate. Traditional dihydrate flow channel flow channels are rectangular in cross-section with a horizontal base. Horizontal flow channels result in slow filtrate flow and are prone to scaling at right angles, making cleaning difficult. This invention features a conical hopper with rounded edges, eliminating dead corners, allowing for faster filtrate flow and shorter residence time. The angle of the conical hopper is designed based on factors such as the material's angle of repose, flow rate, and ease of manufacturing. Another advantage of the conical hopper is its larger internal storage space, which significantly extends its service life and increases equipment uptime.

[0022] The lower gasket 1 and the lower flange 2 are fastened together by hexagon socket screws and sealed by ultra-high molecular weight polyethylene plugs 6 to prevent scale from clogging the fasteners and making it impossible to remove the lower gasket 1.

[0023] The lower gasket 1 and the lower flange 2 are sealed by an O-ring 5. The outer collection tank sealing strip 3 and the outer collection tank 4 are connected to the lower flange 2 by fasteners to form a sealed filtrate collection device for collecting leaked filtrate.

[0024] The outer collection tank 4 is located on the lower plane of the lower flange 2. The outer collection tank 4 is connected to the outer ring collection tank port 32. The inner collection tank 7 is directly welded to the lower flange 2. The inner collection tank 7 is connected to the inner ring collection tank port 33. The steam ring pipe 11 is fixed together with the lower steam plate by the internal steam ring pipe support 12 welded to the outer collection tank 4 and the U-bolt 10; the steam ring pipe 11, the clamp 13 and the clamp sealing ring, the internal steam short pipe 14, the cleaning hole cover 16 and the internal steam ring pipe inlet 44 form an internal steam channel.

[0025] The jacketed insulated water outlet 26 is positioned 13° counterclockwise directly above the jacketed insulated hot water inlet 28, and a baffle is installed between the jacketed insulated water outlets 26 and 28 to ensure that the insulated hot water forms a complete loop. The connecting support 29 is the mounting support for the lower air plate and is fixed together with the cantilever beam on the circumference of the central column by fasteners; the inner and outer adjusting ring plates 30 are welded to the inner and outer rings of the filtrate straight section 17; the jacketed insulated water outlet 26 is positioned directly above the jacketed insulated water inlet 28 to ensure that the hot water fills each conical jacket before being discharged. A baffle is installed between the jacketed insulated water outlet 26 and the jacketed insulated water inlet 28 to ensure that the hot water enters from the inlet and circles the lower air plate before being discharged from the outlet.

[0026] Connecting plate I 37 is welded to the bottom of the lower air plate, and connecting plate II 38 is welded to the drain ring pipe 43. They are fixed together with the lower air plate by fasteners. The cone hopper drain elbow 39 is the drain pipe below each cone hopper jacket. One end of the wide-type internal thread ball valve 40 is connected to the cone hopper drain elbow 39, and the other end is connected to the drain short connector 48. It is used to control the discharge of heat preservation water in the jacket when the machine is stopped for a long time.

[0027] The drain ring pipe 43 is connected to the outlet of each cone bucket jacket through the acid-resistant rubber tube 41 and the European-style strong clamp 42 to reduce the difficulty of alignment during assembly.

[0028] Furthermore, the outer collection tank 4 is also equipped with an outer collection tank connector 34, which is a short connector of the outer collection tank 4. The outlets of the inner collection tank 7 and the outer collection tank 4 are combined into one pipe through the outer collection tank connector 34. At the same time, after scaling occurs, the transparent PVC steel wire hose 35, German-style hose clamp 36 and outer collection tank connector 34 can be disassembled to clean the inside and connect the pipes of the inner and outer collection tanks to one pipe, which greatly facilitates the on-site piping.

[0029] Furthermore, the adjustable partition 31 includes an adjustable partition fixing plate 31-1, fasteners 31-2, an adjustable left partition 31-3, and an adjustable right partition 31-4. The adjustable partition fixing plate 31-1 is fixed to the inner and outer adjusting ring plates 30 by hexagonal bolts. The adjustable left partition 31-3 and the adjustable right partition 31-4 are connected to the adjustable partition fixing plate 31-1 as a whole by fasteners 31-2, used to adjust the angle of each zone. The lower air plate is divided into a slag flushing water zone, a primary filtrate zone, a filtrate zone, a first wash water zone, and a second wash water zone. The adjustment angle of the primary filtrate zone is approximately 8 degrees, and the adjustment angle of the other zones is approximately 20 degrees. Specially designed adjustable partitions are used to adjust the angle of each zone of the lower air plate to ensure consistency with the on-site process plan.

[0030] Furthermore, the height of the inner collection tank 7 is a certain distance, about 10mm, lower than the upper plane of the lower flange 2, so that there will be no interference on site when the upper plane of the lower pad 1 and the upper air plate are planed together after the overall assembly is completed; in order to increase the collection capacity of the inner collection tank 7, the stainless steel wire 8 and the acid-resistant rubber plate 9 are both raised by about 120mm.

[0031] Furthermore, the cleaning hole cover 16 and the lower air plate are sealed by an acid-resistant rubber gasket 15; the cleaning hole cover 16 adopts a square box shape with a certain taper, about 8°, which can solve the problem that the cleaning hole cover 16 is difficult to disassemble due to the scale buildup around it.

[0032] Furthermore, the filtrate straight section 17 is the straight section of the lower air plate filtration channel, and the filtrate cone section 20 is the cone body section of the lower air plate filtration channel. The outer ring insulation jacket 19, the inner ring insulation spacer 24, the jacket insulation base plate 23, and the cone side insulation jacket plate 24 constitute the insulation jacket of the filtrate channel. The outer ring aluminum foil composite thermal insulation cotton 18 and the inner ring aluminum foil composite thermal insulation cotton 25 are fixed to the jacket with heat-drying adhesive and insulation nails. The thickness of the aluminum foil composite thermal insulation cotton is 40mm, further insulating the jacket.

[0033] The conventional two-water method's air-cooling plate lacks insulation. This invention optimizes the design of the air-cooling plate in the semi-water and two-water method: 1. A fully enclosed jacket is installed between the straight section and the conical hopper of the air-cooling plate, and 95℃ hot water is introduced into the jacket. Insulation cotton is filled between the conical hoppers. 2. A 40mm thick layer of single-sided adhesive aluminum foil composite thermal insulation cotton is applied to the inner and outer layers of the jacket, and reinforced with insulation nails. 3. Steam is introduced into the filtrate flow channel. Through these three insulation measures, heat loss from the filtrate is greatly reduced, solid precipitation is decreased, and scale formation is significantly reduced.

[0034] Furthermore, the filtrate outlet 22 is the outlet of the filtrate channel, and its shape is funnel-shaped to facilitate easy cleaning of the internal cavity from the bottom during major overhauls. The PTFE bushing 47 is a 5mm thick PTFE plate lining the filtrate channel. PTFE possesses extremely high chemical stability, strong corrosion resistance, low coefficient of friction, good non-adhesion, strong wear resistance, and high temperature resistance, further reducing scaling inside the lower air plate and improving corrosion resistance.

[0035] Furthermore, an electric contact pressure gauge 27 is installed on the jacketed hot water inlet 28 to detect the pressure inside the jacket and transmit it to the control unit, thereby controlling the hot water inside the jacket and ensuring safety.

[0036] Furthermore, the inner and outer adjusting ring plate 30 is an annular plate with a ring of holes. The adjustable partition plate 31 can be adjusted through the holes. Adjusting the adjustable partition plate 31 can adjust the angle of the primary filtration zone, the filtrate zone, and the washing water zone, so that the angle of each zone is more suitable for the process requirements on site.

[0037] Furthermore, the connecting plate II38 is provided with elongated holes to facilitate adjustment during installation and compensate for errors caused by manufacturing precision. Example 2 Example 2 is a simplified version of the lower air plate of the semi-water filter in Example 1. It is mainly used in the secondary water filter for phosphate ore with poor quality, and solves the problems of conventional flat-bottom lower air plate that are prone to clogging, scaling, difficult to clean, easy to corrode, and low start-up efficiency.

[0038] The main differences from Example 1 are as follows: 1. The flow channel still adopts a straight section plus bucket structure, but only the straight section of the flow channel is jacketed, eliminating the overall jacket enclosure method. Hot water at 95℃ is also introduced into the jacket. 2. The cleaning port size is reduced. For routine cleaning, only a stick or similar tool needs to be used to tap the scale inside the cleaning port, resulting in significantly less scale buildup compared to the semi-water process. The cleaning port of the semi-water filter allows the upper body to enter, enabling more thorough and effective cleaning. 3. The internal flow channel does not have a PTFE bushing. 4. The internal steam pipes in each area are independent steam pipes, not integrated into a single unit; the number of pipes is correspondingly increased. 5. The lower gas plate outlet flange adopts a straight section type.

[0039] The working principle of this invention is as follows: The circumferential surface of the filter is divided into a feeding zone, a primary washing zone, a secondary washing zone, a drying zone, a discharge zone, and a filter cloth regeneration zone. One rotation of the filter disc constitutes one cycle, and this cycle repeats under vacuum, achieving continuous solid-liquid separation. The filtrate passes through the filter cake and filter cloth, through the filter disc, the liquid guide pipe, the vacuum hose, the upper air plate, and then into the lower air plate. The lower air plate creates corresponding zones based on the partitions of the filter disc surface. The filtrate from different zones is then distributed to their respective storage tanks and pumped to the areas requiring specific process parameters. According to the filter's process, the filter generally uses counter-current washing. The filtrate from the secondary washing zone is used as the wash water for the primary washing zone (for acid concentration). The filtrate from the primary washing zone and the filtrate from the feeding zone (excluding the primary filtration zone) are used as the finished acid. The filtrate from the filter cloth regeneration zone is externally filtered and reused as cleaning water to achieve water balance, etc. The process details are not elaborated further.

[0040] The lower air plate is divided into several zones based on its circumferential surface: 1° initial filtrate zone and 2° filtrate zone (both corresponding to the feeding zone), 3° first washing liquid zone (corresponding to the first washing area), 4° second washing liquid zone (corresponding to the second washing area), 5° drying zone (corresponding to the second washing area), and 6° slag flushing water zone (corresponding to the unloading area and filter cloth regeneration area). Except for the slag flushing water zone (atmospheric pressure zone), the remaining zones are vacuum zones with a negative pressure of 0.2–0.6 MPa.

[0041] The working process of the special lower gas plate for the phosphoric acid hemihydrate-dihydrate process of the present invention is as follows: (1) When the slurry is added to the plate, a filter cake has not yet formed on the plate. Filtration is carried out solely by the filter cloth, resulting in a high impurity content in the filtrate (unsuitable as finished acid, referred to as waste acid). This filtrate enters the initial filtrate area of ​​the lower gas plate and is collected for use as one of the water sources for slurry preparation. Once a filter cake forms on the filter cloth, the filtrate filtered through the filter cake enters the filtrate area of ​​the lower gas plate and can be directly used as finished acid. Supplementary explanation: The solid-liquid separation of the filter mainly relies on the filter cake formed in the feeding zone for filtration. The filter cloth is only used as an initial auxiliary filter.

[0042] (2) The washing liquid in the first washing area is the filtrate of the second washing. After being filtered by the filter cake and filter cloth, it enters the first washing liquid area of ​​the lower gas plate to form the first washing filtrate, which can be used as finished acid and enters the finished acid storage tank together with the filtrate.

[0043] (3) The washing liquid in the second washing area (mostly clean water, rainwater, and water obtained from other places) enters the second washing liquid area of ​​the lower air plate after being filtered by filter cake and filter cloth, forming the second washing filtrate (as the washing liquid of the first washing area).

[0044] (4) In the drying zone, the filter cake is moistened to meet the process requirements by the negative pressure. The filtered (i.e., sucked-out) water liquid also enters the second washing liquid zone (which also serves as the washing liquid for the first washing zone).

[0045] (5) Discharge area: The filter cake is discharged from the inside to the outside of the slag hopper through the spiral discharger on the disc. This area is the atmospheric pressure area.

[0046] (6) The slag flushing water area, that is, after the disc screw unloader discharges the material, a thin layer of filter cake will remain. At this time, it is flushed by high pressure water from the slag flushing water device to achieve the functions of slag removal and filter cloth regeneration. This area is also a normal pressure area. The filter cake remaining on the disc is also flushed into the slag hopper, while the high pressure water passing through the filter cloth enters the slag flushing water area of ​​the lower air plate. After being discharged, it is filtered by the outside (sedimentation tank and pipeline filter, etc.) and then used as the water source for the filter cloth regeneration area (that is, the high pressure water source of the slag flushing water device. At the same time, according to the loss, some clean water is added to ensure the amount of flushing water).

[0047] (7) The above is a description of each section of the lower air plate. The sections are carried out in sequence, which is one cycle of filtration. According to this cycle, the process is repeated to achieve continuous filtration and separation of solid and liquid.

[0048] (8) The angle of each area of ​​the lower gas plate can be adjusted so that the filtrate in the lower gas plate can meet the process requirements.

[0049] (9) The channels of each section of the lower gas plate are equipped with a full-coverage jacket inside and out, and hot water at 95°C is introduced into the jacket (the hot water in the jacket is constantly circulating and kept at 95°C) to provide all-round heat preservation for the channels of each section. In order to further insulate the channels of each section (except for the slag flushing water area, which is a normal pressure area), pipes leading into the interior are installed on the cleaning holes of each channel to allow the introduction of internal steam.

[0050] (10) The inner surface of each partition channel is equipped with PTFE plate, which not only prevents corrosion but also greatly reduces internal scaling.

[0051] In summary, this invention optimizes the structure of the lower air disc, making its operation more reliable and minimizing the possibility of scaling. It has already been applied and verified by dozens of users employing the semi-water / dual-water process, resulting in significantly improved equipment filtration and operational efficiency, and has received unanimous praise from users. The above embodiments are merely illustrative of the technical solution of this invention and not intended to limit it. Although the invention has been described in detail with reference to the above embodiments, those skilled in the art can still make modifications or equivalent substitutions to the specific embodiments of this invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of this invention are within the protection scope of the pending claims of this invention.

Claims

1. A special gas-discharging plate for the phosphoric acid hemihydrate-dihydrate process, comprising a gas-discharging plate, characterized in that: The lower gasket (1) and the lower flange (2) are fastened together by hexagonal screws and sealed by polyethylene plugs (6); the lower gasket (1) and the lower flange (2) are sealed by O-rings (5); the outer collection groove sealing strip (3) and the outer collection groove (4) are connected to the lower flange (2) by fasteners to form a sealed filtrate collection device; the outer collection groove (4) is located on the lower plane of the lower flange (2), the outer collection groove (4) is connected to the outer ring collection groove port (32), the inner collection groove (7) is directly welded to the lower flange (2), and the inner collection groove (7) is connected to the inner ring collection groove port (33). The steam ring pipe (11) is fixed to the lower steam plate by the internal steam ring pipe bracket (12) welded to the outer collection tank (4) and the U-bolt (10); the steam ring pipe (11), the clamp (13) and the clamp sealing ring, the internal steam short pipe (14), the cleaning hole cover (16) and the internal steam ring pipe inlet (44) form an internal steam channel; The jacketed insulated water outlet (26) is located 13° counterclockwise above the jacketed insulated hot water inlet (28), and a partition is provided between the jacketed insulated water outlet (26) and (28) to ensure that the insulated hot water forms a complete circuit; the connecting support (29) is the mounting support for the lower air plate, and is fixed together with the cantilever beam on the circumference of the central column by fasteners; the inner and outer adjusting ring plates (30) are welded to the inner and outer rings of the filtrate straight section (17); The connecting plate I (37) is welded to the bottom of the lower gas plate, and the connecting plate II (38) is welded to the drain ring pipe (43) and fixed together with the lower gas plate by fasteners; the cone bucket drain elbow (39) is the drain pipe below each cone bucket jacket, and one end of the wide-type internal thread ball valve (40) is connected to the cone bucket drain elbow (39), and the other end is connected to the drain short connector (48); The drain ring pipe (43) is connected to the outlet of each cone bucket jacket through an acid-resistant rubber tube (41) and a European-style strong clamp (42).

2. The special lower gas plate for the phosphoric acid hemihydrate-dihydrate process according to claim 1, characterized in that: The outer collection tank (4) is also provided with an outer collection tank connector (34). The outer collection tank connector (34) is a short connector of the outer collection tank (4). The outlets of the inner collection tank (7) and the outer collection tank (4) are combined into one pipe through the outer collection tank connector (34). After scaling occurs, the interior is cleaned by disassembling the transparent PVC steel wire hose (35), the German hose clamp (36) and the outer collection tank connector (34).

3. The special lower gas plate for the phosphoric acid hemihydrate-dihydrate process according to claim 1, characterized in that: The adjustable partition (31) includes an adjustable partition fixing plate (31-1), a fastener (31-2), an adjustable partition left partition (31-3), and an adjustable partition right partition (31-4). The adjustable partition fixing plate (31-1) is fixed to the inner and outer adjusting ring plates (30) by hexagonal bolts. The adjustable partition left partition (31-3) and the adjustable partition right partition (31-4) are connected to the adjustable partition fixing plate (31-1) as a whole by the fastener (31-2) to adjust the angle of each partition.

4. The special lower gas plate for the phosphoric acid hemihydrate-dihydrate process according to claim 3, characterized in that: The lower air plate is divided into a slag flushing water area, a primary filtrate area, a filtrate area, a first wash water area, and a second wash water area. The primary filtrate area has an adjustment angle of 8°, while the other areas have an adjustment angle of 20°.

5. The special lower gas plate for the phosphoric acid hemihydrate-dihydrate process according to claim 1, characterized in that: The height of the inner collection tank (7) is 10mm lower than the upper plane of the lower flange (2). The stainless steel wire (8) and the acid-resistant rubber plate (9) are both raised by 120mm.

6. The special lower gas plate for the phosphoric acid hemihydrate-dihydrate process according to claim 1, characterized in that: The cleaning hole cover (16) and the lower air plate are sealed by an acid-resistant rubber gasket (15); the cleaning hole cover (16) adopts a square box shape with an 8° taper.

7. The special lower gas plate for the phosphoric acid hemihydrate-dihydrate process according to claim 1, characterized in that: The filtrate straight section (17) is the straight section of the lower gas plate filtration channel, the filtrate cone section (20) is the cone section of the lower gas plate filtration channel, the outer ring insulation jacket (19), the inner ring insulation spacer (24), the jacket insulation base plate (23) and the cone side insulation jacket plate (24) form the insulation jacket of the filtrate channel; the outer ring aluminum foil composite heat insulation cotton (18) and the inner ring aluminum foil composite heat insulation cotton (25) are fixed to the jacket by hot dry glue and insulation nails.

8. The special lower gas plate for the phosphoric acid hemihydrate-dihydrate process according to claim 1, characterized in that: The filtrate outlet (22) is the outlet of the filtrate channel, and the shape of the filtrate outlet (22) is set as a horn shape; the PTFE bushing (47) is a PTFE plate lining the filtrate channel with a thickness of 5mm.

9. A special lower gas-displacement plate for the phosphoric acid hemihydrate-dihydrate process according to claim 1, characterized in that: The jacketed insulated hot water inlet (28) is equipped with an electric contact pressure gauge (27) to detect the pressure inside the jacket and transmit it to the control unit.

10. A special lower gas-displacement plate for the phosphoric acid hemihydrate-dihydrate process according to claim 1, characterized in that: The inner and outer adjusting ring plate (30) is an annular plate, and the inner and outer adjusting ring plate (30) is provided with a ring of holes, through which the adjustable partition plate (31) is adjusted; the connecting plate II (38) is provided with elongated holes.

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