A gas pressurized rotary drum filter

Abstract

The application discloses a gas pressurizing rotary drum filter, which is characterized in that a distribution head rotor is connected to a rotary drum, a distribution head is arranged outside the distribution head rotor, the rotary drum is divided into a plurality of working zones according to the rotating direction, an annular cavity between the distribution head rotor and the distribution head is divided into independent mother liquor discharge cavities, dry gas discharge cavities and washing liquid discharge cavities according to the working function zones of the rotary drum along the circumferential direction, filtered mother liquor in the filtering zone, washed washing liquid in the washing zone and dried water-containing gas in the drying zone are respectively introduced into corresponding zones of the annular cavity through connecting pipes in the respective zones, and finally discharged through the mother liquor discharge outlets, the washing liquid discharge outlets and the dry gas discharge outlets on the distribution head; unloading back-blowing gas and filter cloth backwashing liquid with certain pressure are respectively introduced into the connecting pipes through back-blowing gas inlets and washing liquid inlets on the distribution head, and then introduced into the rotary drum, so as to realize unloading by blowing gas to the filter cake and backwashing to the filter cloth, and thus high-efficiency separation of the mother liquor and the washing liquid is realized.

Description

Technical Field

[0001] This invention relates to a gas pressurized rotary drum filter, belonging to the technical field of rotary drum pressurized filtration equipment. Background Technology

[0002] Currently, there are many types of rotary drum pressure filtration equipment, and the pressure application methods are usually either liquid pressure or gas pressure.

[0003] A typical example of a liquid-pressurized filter is a product of the German company BHS. Its drum has several filter unit chambers, which, together with the outer casing and seals, form several independent pressurized chambers in a circumferential direction. The filter cake and washing liquid are directly pumped into these independent chambers, achieving pressure filtration through liquid pressure. Filtration, multi-stage washing, and drying are achieved within these independent chambers, maximizing the removal of impurities carried in the filter cake while performing filtration, and achieving an extremely low washing ratio through multi-stage washing. However, its disadvantages are also obvious: the seal at the drum end is prone to leakage; the seals between chambers and the drum surface are easily worn, leading to internal leakage between different chambers; and the operating and maintenance costs are extremely high.

[0004] Gas-pressurized rotary drum filters, such as those with announcement numbers CN107510980B ("A Multi-Purpose Continuous Positive Pressure Filtration Equipment") and CN109316813A ("Pressurized Rotary Drum Filter"), both involve installing a filter drum within a pressure vessel. Pressurized gas is introduced into the vessel to pressurize the slurry and filter cake. The lower part of the drum is submerged in the slurry. Under pressure, the solid phase in the slurry is adsorbed onto the drum surface, forming a filter cake. A washing device is located above the drum, and the washing liquid washes the filter cake from the drum surface. A central tube is located inside the drum. Its main characteristic is that the mother liquor, washing liquid, and pressurized gas are mixed inside the filter drum before being discharged together. The disadvantage of this existing gas-pressurized filter press is that the filtered mother liquor and washing liquid mix inside the drum, making efficient separation of the mother liquor and washing liquid impossible. For processes with high washing ratios, the efficiency is very low, and may even fail to meet requirements. Summary of the Invention

[0005] The purpose of this invention is to provide a gas-pressurized rotary drum filter capable of independently discharging mother liquor and multi-stage washing liquid, thereby solving the technical problem that existing gas-pressurized filter presses cannot achieve efficient separation of mother liquor and washing liquid.

[0006] This invention adopts the following technical solution: a gas-pressurized rotary drum filter includes a housing and a rotary drum disposed within the housing. The rotary drum has a filter screen and a filter cloth covering the filter screen circumferentially. A motor driving the rotary drum to rotate is disposed outside the housing. A slurry feeding area and a filter cake discharging area are disposed below the rotary drum within the housing. One end face of the rotary drum is sealed, and a distribution head rotor is fixedly connected to the other end face. One end of the distribution head rotor is closed, and the other end communicates with the interior of the rotary drum. A distribution head is disposed outside the distribution head rotor. An annular cavity exists between the distribution head rotor and the distribution head. Sealing components are respectively disposed at both ends of the annular cavity. The distribution head and the sealing components are fixedly connected, and the distribution head rotor and the sealing components are rotatably engaged. Connecting pipes distributed circumferentially between the distribution head rotor and the rotary drum are provided, with one end of each connecting pipe fixed to the rotary drum. The inner and outer ends are respectively fixed on the rotor of the distribution head, and each connecting pipe is connected to the annular cavity; the drum is provided with a filtration zone, a first drying zone, a discharge zone and a filter cloth backwashing zone in sequence along the rotation direction. The filtration zone is used to contact the slurry in the slurry feeding zone. The filter cloth backwashing zone is adjacent to the filtration zone and located above the slurry zone; the annular cavity is provided with a mother liquor discharge chamber and a primary drying gas discharge chamber corresponding to the filtration zone and the first drying zone, respectively. The mother liquor discharge chamber and the primary drying gas discharge chamber are separated by a partition block. The outside of the distribution head is connected with a mother liquor outlet and a primary drying gas outlet that are connected to the mother liquor discharge chamber and the primary drying gas discharge chamber, respectively. The distribution head is provided with a backflush air inlet and a washing liquid inlet. The backflush air inlet and the washing liquid inlet are connected to the discharge zone and the filter cloth backwashing zone of the drum, respectively, through connecting pipes.

[0007] Along the rotation direction of the drum, a washing zone and a second drying zone are arranged sequentially between the first drying zone and the unloading zone on the drum. A spraying device fixed in the housing is provided above the washing zone. The annular cavity is provided with a washing liquid discharge chamber and a secondary drying gas discharge chamber corresponding to the washing zone and the second drying zone of the drum, respectively. The distributor head is externally connected to a washing liquid outlet and a secondary drying gas outlet that are respectively connected to the washing liquid discharge chamber and the secondary drying gas discharge chamber.

[0008] The drum is further provided with an N-stage washing zone and an N-stage drying zone between the secondary drying zone and the unloading zone; correspondingly, the annular cavity is provided with an N-stage washing liquid discharge chamber and an N-stage drying gas discharge chamber between the washing liquid discharge chamber and the secondary drying gas discharge chamber, and the distribution head is connected to an N-stage washing liquid outlet and an N-stage drying gas outlet that are respectively connected to the N-stage washing liquid discharge chamber and the N-stage drying gas discharge chamber.

[0009] The filter screen includes a bridge frame arranged sequentially along the circumference of the drum. The bridge frame is an arched perforated mesh plate. Each bridge frame is evenly distributed along the circumference of the drum. The filter cloth covers the outside of the bridge frame. The end of the connecting pipe inside the drum is located near the inside of the bridge frame.

[0010] There is an inverted "Ω" groove between adjacent cable trays. The "Ω" groove is equipped with a clamping element, and the filter cloth located between adjacent cable trays is clamped in the "Ω" groove by the clamping element.

[0011] The sealing assembly includes a compression cap and packing. The packing is located between the distributor rotor and the distributor. The compression cap includes an annular compression part and an annular ring that are fixedly connected together. The annular ring and the annular compression part are arranged perpendicularly. The annular compression part is used to compress the packing. The annular ring and the distributor are connected together.

[0012] The annular ring and the dispensing head are connected together by a stud, and a compression spring and an adjusting nut are provided on the side of the stud away from the dispensing head.

[0013] The isolation block includes a sealing block and a pressure cap fixed to the distribution head. The sealing block is pressed between the distribution head and the distribution head rotor by the pressure cap, and the pressure cap is fixed to the outer peripheral surface of the distribution head by bolts. The backflush air inlet and the washing liquid inlet both pass through the isolation block.

[0014] The housing is provided with supports for supporting the drum and the distributor rotor, and the supports are provided with bearing seats, and bearings are provided in the bearing seats; a coupling is connected to the rotating shaft connected to the drum; a reducer is connected to the motor outside the housing, and the reducer is connected to the coupling; a sealing mechanism is provided on the inner and outer sides of the coupling on the housing.

[0015] The housing includes an upper housing and a lower housing connected by a flange. A partition is provided between the slurry feeding area and the filter cake discharge area. An overflow area is provided on one side of the slurry feeding area, and the filter cake discharge area is located on the other side of the slurry feeding area.

[0016] The beneficial effects of this invention are as follows: A distribution head rotor is connected to the drum, and a distribution head is set outside the distribution head rotor. The drum is divided into multiple working zones (filtration zone, first drying zone, washing zone, second drying zone, unloading zone, and filter cloth backwashing zone) according to the rotation direction. The annular cavity between the distribution head rotor and the distribution head is divided into independent mother liquor discharge chamber, primary drying gas discharge chamber, washing liquid discharge chamber, and secondary drying gas discharge chamber along the circumferential direction according to the working functional zones of the drum. The filtered mother liquor after filtration in the filtration zone, the washing liquid after washing in the washing zone, and the water-containing gas after drying in each drying zone enter the corresponding area of ​​the annular cavity through the connecting pipes in their respective areas, and are finally discharged from the mother liquor outlet, washing liquid outlet, and each level of drying gas outlet on the distribution head. Unloading backflushing air and filter cloth backwashing liquid with a certain pressure enter the connecting pipes through the backflushing air inlet and washing liquid inlet on the distribution head, and then enter the drum. The unloading backflushing air blows air onto the filter cake inside the drum to achieve unloading, and the filter cloth backwashing liquid backwashes the filter cloth inside the drum.

[0017] The specific working process of this invention is as follows: (1) In the washing zone, the suspension in the slurry passes through the filter cloth and filter screen into the drum. After the drum rotates, the filter material forms a filter cake on the outside of the drum; (2) In the drying zone, the gas in the shell passes through the filter cake under pressure and absorbs the moisture in the filter cake. The gas after absorbing water exits from the drying gas discharge chamber of the annular cavity of the connecting pipe in the drying zone and then exits from the drying gas outlet; (3) In the washing zone, the filter cake is washed by spraying spray liquid onto the filter cake using a spraying device. The washing wastewater passes through the filter cloth and filter screen and enters the washing liquid discharge chamber through the connecting pipe in the washing zone. (4) After multiple washing and drying, the filter cake enters the unloading area. Pressurized back-blowing air enters the drum through the connecting pipe and back-blowing the filter cake from the back of the filter cloth, causing the filter cake to detach from the filter cloth and fall into the filter cake discharge area, and be discharged from the shell through the discharge port. (5) In the filter cloth backwashing area, pressurized washing liquid enters from the distribution head and then enters the drum through the connecting pipe. The filter cloth is cleaned on the inside of the drum. The washing liquid after cleaning the filter cloth is directly discharged into the slurry feeding area and used as slurry mother liquor for recycling. (6) After the filter cloth is cleaned, the drum re-enters the slurry feeding area to start the next filtration cycle.

[0018] This invention utilizes independently connected pipes within each region of the drum, and a distribution head to independently discharge or introduce the medium from each region into the drum. This enables highly efficient separation of the mother liquor and the washing liquid, thereby maximizing the utilization of both the mother liquor and the washing liquid, improving washing efficiency, and reducing energy consumption and equipment investment in subsequent mother liquor and washing liquid separation processes. During operation, the gas-pressurized drum filter of this invention exhibits no wear on the drum surface, requires no maintenance, and the distribution head is located inside the casing, eliminating external leakage issues.

[0019] Preferably, the filter screen uses multiple bridges, each of which can serve as a filter unit, facilitating partitioning during drum operation and corresponding to the connecting pipes in its respective area.

[0020] Preferably, the filter cloth is tightly fixed by using a connector and an "Ω" groove, so that the filter cloth is always taut on the bridge frame and the filter cloth is not easy to separate from the bridge frame when backflushing and backwashing.

[0021] Preferably, the clamping cover and packing can effectively achieve a seal between the distributor head and the distributor head rotor; the clamping cover is fixed by a clamping spring and an adjusting nut to ensure that while sealing is achieved, the clamping cover has a certain amount of room for movement. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a gas pressurized rotary drum filter according to an embodiment of the present invention; Figure 2 yes Figure 1 External view of a gas pressurized rotary drum filter; Figure 3 yes Figure 1 Top view of the lower and middle shell; Figure 4 yes Figure 1 Schematic diagram of the intermediate drum partitioning; Figure 5 yes Figure 1 A schematic diagram showing the connection between the transfer drum and the distributor head rotor; Figure 6 yes Figure 1 Plan view of the rotary drum and spray system; Figure 7 yes Figure 6 A magnified view of a section of the rotary drum; Figure 8 yes Figure 1 Radial sectional view of the distribution head and the distribution head rotor; Figure 9 yes Figure 1 A schematic diagram of the connection between the distribution head and the distribution head rotor.

[0023] In the diagram: 1-Upper shell; 2-Lower shell; 3-Support; 4-Sealing mechanism; 5-Reducer; 6-Motor; 7-Drum; 7.1-Filtration zone; 7.2-First drying zone; 7.3-Washing zone; 7.4-Second drying zone; 7.5-Discharge zone; 7.6-Filter cloth backwashing zone; 8-Distribution head; 8.1-Mother liquor outlet; 8.2-First-stage drying gas outlet; 8.3-Washing liquid outlet; 8.4-Second-stage drying gas outlet; 8.5-Backflush gas inlet; 8.6-Washing liquid inlet; 9-Shaft; 10-Bearing seat; 11- 12-Bearing; 13-Coupling; 14-Filter cake discharge area; 15-Discharge scraper; 16-Slurry feed area; 17-Overflow plate; 18-Overflow area; 19-Distributor rotor; 20-Connecting pipe; 21-Protective cover; 22-Spraying device; 23-Bridge frame; 24-Clamping component; 25-“Ω” groove; 26-Filter cloth; 27-Isolation block; 27-Annular cavity; 27.1-Mother liquor discharge cavity; 27.2-Primary drying gas discharge cavity; 27.3-Washing liquid discharge cavity; 27.4-Secondary drying gas discharge cavity; 28-Clamping cover; 29-Packaging. Detailed Implementation

[0024] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0025] like Figures 1 to 9 As shown, an embodiment of the gas pressurized rotary drum filter of the present invention includes a housing and a rotary drum 7 disposed in the housing. The rotary drum 7 has a filter screen and a filter cloth 25 covering the filter screen in the circumferential direction. A spray device 21 fixed in the housing is provided above the rotary drum 7. A motor 6 is provided outside the housing to drive the rotary drum 7 to rotate. A slurry feeding area 15 and a filter cake discharge area 13 are provided below the rotary drum 7 in the housing.

[0026] One end face of the drum 7 is sealed, and a distribution head rotor 18 is fixedly connected to the other end face. One end of the distribution head rotor 18 is closed, and the other end is connected to the inside of the drum 7. A distribution head 8 is provided outside the distribution head rotor 18. An annular cavity 27 is provided between the distribution head rotor 18 and the distribution head 8. Sealing components 4 are respectively provided at both ends of the annular cavity 27. The distribution head 8 and the sealing components are fixedly connected, and the distribution head rotor 18 and the sealing components are rotatably engaged. A connecting pipe 19 distributed along the circumference of the drum is provided between the distribution head rotor 18 and the drum 7. Each connecting pipe 19 has one end fixed inside the rotating drum 7 and the other end fixed to the distributing head rotor 18, and each connecting pipe 19 communicates with the annular cavity. The rotating drum 7 is sequentially provided with a filtration zone 7.1, a first drying zone 7.2, a washing zone 7.3, a second drying zone 7.4, a discharge zone 7.5, and a filter cloth backwashing zone 7.6 along the rotation direction. The filtration zone 7.1 is used to contact the slurry in the slurry feeding zone 15. The washing zone 7.2 is located below the spray device 21, and the filter cloth backwashing zone 7.6 is adjacent to the filtration zone 7.1. It is located adjacent to and above the slurry feeding area 15; the annular cavity 27 is provided with a mother liquor discharge chamber 27.1, a primary drying gas discharge chamber 27.2, a washing liquid discharge chamber 27.3, and a secondary drying gas discharge chamber 27.4, respectively corresponding to the filtration area 7.1, the first drying area 7.2, the washing area 7.3, and the second drying area 7.4. The mother liquor discharge chamber 27.1, the primary drying gas discharge chamber 27.2, the washing liquid discharge chamber 27.3, and the secondary drying gas discharge chamber 27.4 are separated by a partition block 26. The distributor 8 is externally connected to a mother liquor outlet 8.1, a primary drying gas outlet 8.2, a washing liquid outlet 8.3, and a secondary drying gas outlet 8.4, which are respectively connected to the mother liquor outlet chamber 27.1, the primary drying gas outlet chamber 27.2, the washing liquid outlet chamber 27.3, and the secondary drying gas outlet chamber 27.4. A backflush gas inlet 8.5 and a washing liquid inlet 8.6, which pass through the distributor 8, are provided in the annular cavity between the secondary drying gas outlet chamber 27.4 and the mother liquor outlet chamber 27.1.

[0027] The structure of the distribution head is as follows Figures 8 to 9 As shown, several sets of isolation blocks 26 are provided in the annular cavity between the distributor head 8 and the distributor head rotor 18, dividing the annular cavity into several chambers along the circumference, corresponding to different functional zones on the drum 7. Mother liquor, washing liquid, and drying exhaust gas are discharged from the corresponding ports on the distributor head; backflushing air and filter cloth washing water enter the drum from the distributor head 8. Each outlet and inlet on the distributor head 8 is connected to the corresponding port on the housing through a hose, thereby discharging or introducing the corresponding medium outside the housing.

[0028] The sealing assembly includes a compression cap 28 and a packing 29. The packing 29 is located between the distributor rotor 18 and the distributor 8. The compression cap 28 includes an annular compression part and an annular ring fixedly connected together. The annular ring and the annular compression part are arranged perpendicularly. The annular compression part is used to compress the packing. The annular ring and the distributor 8 are connected together. The annular ring and the distributor 8 are connected together by a stud. A compression spring and an adjusting nut are provided on the side of the stud away from the distributor 8.

[0029] The isolation block 26 includes a sealing block and a pressure cap fixed to the distribution head. The sealing block is pressed between the distribution head 8 and the distribution head rotor 18 by the pressure cap, and the pressure cap is fixed to the outer peripheral surface of the distribution head 8 by bolts. The backflush air inlet 8.5 and the washing liquid inlet 8.6 both pass through the isolation block 26.

[0030] A spraying device 21 is provided on the upper part of the drum 7. The spraying device 21 consists of a support, a spray pipe and a nozzle. It is installed on the protective cover 20 above the drum on the housing through the support. Pressurized washing liquid washes the filter cake through the nozzle to wash the impurities contained in the filter cake.

[0031] The structure of the rotating drum 7 is as follows Figures 6 to 7 As shown, the filter screen in the drum 7 includes bridge frames 22 arranged sequentially along the circumference of the drum 7. The bridge frames 22 are arched perforated mesh plates, and each bridge frame 22 is evenly distributed along the circumference of the drum 7. The filter cloth 25 covers the outside of the bridge frames 22. The end of the connecting pipe 19 located inside the drum 7 is positioned near the inside of the bridge frame 22. The bridge frame 22 serves as a filtration unit, and has several densely packed Φ2 small holes. There are inverted "Ω" grooves 24 between adjacent bridge frames 22. A clamping member 23 is provided in the "Ω" groove 24, and the filter cloth located between adjacent bridge frames 22 is clamped in the "Ω" groove 24 by the clamping member 23. The filter cloth 25 is fixed to the outside of the drum 7 by several "Ω" grooves 24. The "Ω" grooves 24 are intermittently welded to the drum along the circumference of the drum 7. The bridge frame 22 is fixedly arranged between the "Ω" grooves 24. The filter cloth 25 is wrapped around the bridge frame 22 and the "Ω" grooves 24. The clamping member 23 adopts a pressure rod, which passes through the "Ω" groove to tension the filter cloth 25. The ends of both sides of the filter cloth 25 are fixed in the grooves on the edge of the drum with braided filler. Each bridge frame 22 is provided with several connecting pipes 19 on the inner side of the drum. The other end of the connecting pipe 19 is connected to the distribution head rotor 18 on the non-drive side of the drum.

[0032] The housing comprises an upper housing 1 and a lower housing 2 connected by flanges. The upper housing 1 can be easily removed for installation and maintenance of the internal components. The upper housing 1 has an air inlet for introducing pressurized gas to pressurize the interior. The lower housing 2 has an external support structure to support the entire device. Within the housing, a partition is provided between the slurry feeding area 15 and the filter cake discharge area 13. An overflow area 17 is located on one side of the slurry feeding area 15, and the filter cake discharge area 13 is located on the other side of the slurry feeding area 15. Figure 3 As shown, the lower housing 2 is divided into three parts by a partition. The slurry feeding area 15 is located in the middle, and the filter cake discharge area 13 and the overflow area 17 are located on both sides of the slurry feeding area 15. The bottom of the slurry feeding area 15 is provided with a feed pipe; an adjustable overflow plate 16 is provided between the slurry feeding area 15 and the overflow area 17 to adjust the slurry level; an overflow pipe is provided at the bottom of the overflow area 17 to discharge the overflow liquid; a discharge scraper 14 is provided between the slurry feeding area 15 and the filter cake discharge area 13 to unload the filtered, washed and dried filter cake from the drum 7, and the filter cake is discharged from the outlet located at the bottom of the filter cake discharge area 13.

[0033] The housing contains supports 3 for supporting the drum 7 and the distributor rotor, respectively, located within the lower housing 2. The supports 3 are equipped with bearing seats 10, and bearings 11 are housed within the bearing seats 10. The assembly consisting of the drum 7 and the distributor rotor 18 is mounted within the bearing seats 10 via a rotating shaft 9. A coupling 12 is connected to the rotating shaft 9 connected to the drum 7. A reducer 5 is connected to the motor 6 outside the housing, and the reducer 5 is connected to the coupling 12. Sealing mechanisms 4 are located on the inner and outer sides of the coupling 12 on the housing. The sealing mechanisms 4 employ double-end mechanical seals and are equipped with liquid sealing devices, offering advantages such as small size, low cost, and high reliability.

[0034] The working process and principle of the gas-pressurized rotary drum filter of the present invention are as follows: By filling the shell with pressurized gas, the slurry from the previous process is pressurized by the feed pump and enters the slurry feed zone 15 inside the shell. The principle of the rotary drum 7 is as follows: Figure 4As shown, specifically: (1) Under the pressure of the gas inside the shell, the suspension in the slurry is squeezed on the drum 7, and the filtrate passes through the filter cloth 25 and the filter screen in the filtration zone 7.1 of the drum and enters the drum 7. The intercepted solid material accumulates outside the drum to form a filter cake; the filtrate is discharged from the connecting pipe 19 of the filtration zone 7.1 into the mother liquor discharge chamber 27.1 of the annular cavity, and then discharged from the mother liquor discharge port 8.1 to the distribution head 8; (2) The filter cake formed in the filtration zone 7.1 rotates out from the slurry feed zone 15 and enters the first drying zone 7.2. The filter cake contains material and water. The gas inside the shell passes through the filter cake under pressure, replacing some of the moisture and reducing the moisture content of the filter cake. The gas that has absorbed the moisture enters the primary drying gas discharge chamber 27.2 from the connecting pipe 19 of the first drying zone 7.2 and is discharged from the distribution head 8 through the primary drying gas discharge port 8.2. (3) The filter cake that has passed through the primary drying enters the washing zone 7.3 under the rotation of the drum 7. The spray device 21 above the washing zone 7.3 sprays spray liquid onto the filter cake to wash it. The washing wastewater passes through the filter cloth 25 and the filter screen and exits from the washing zone 7.3. (3) The filter cake after primary drying and washing enters the washing liquid discharge chamber 27.3 through the connecting pipe 19 and is discharged to the outside of the distribution head 8 through the washing liquid discharge outlet 8.3; (4) After primary drying and washing, the filter cake enters the second drying zone 7.4 and is further dried by the gas in the shell. The gas after absorbing moisture enters the secondary drying gas discharge chamber 27.4 through the connecting pipe 19 of the second drying zone 7.4 and is discharged to the distribution head 8 through the secondary drying gas discharge outlet 8.4; (5) After drying, the filter cake enters the unloading zone 7.5 as the drum rotates. The pressurized backflush gas from the distribution head 8 enters the drum 7 through the connecting pipe 19. The filter cake is back-blown from the back of the filter cloth 25, causing it to detach from the filter cloth 25 and fall into the filter cake discharge area 13, and then discharged from the shell through the discharge port; (6) After being discharged through the unloading area 7.5, the drum rotates into the filter cloth backwashing area 7.6. The pressurized washing liquid enters from the distribution head 8 and enters the drum 7 through the connecting pipe 19. The washing liquid cleans the filter cloth 25 inside the drum 7. After cleaning, the filter cloth 25 rotates into the slurry feeding area 15 to start the next filtration cycle. The washing liquid after cleaning the filter cloth 25 is directly discharged into the slurry feeding area 15 and used as slurry mother liquor for recycling.

[0035] The above embodiment shows a dryer with a single-stage spray and two-stage drying. In actual use, if the filter cake does not require spray washing, the spray equipment can be left off; if the single-stage drying can meet the drying requirements, the second-stage drying can be left off. When spray washing of the filter cake is not required, the drum can also be configured with only four areas: a filtration zone, a first drying zone, a discharge zone, and a filter cloth backwashing zone. The annular cavity between the corresponding distribution head and the distribution head rotor is only divided into a mother liquor discharge chamber and a first-stage drying gas discharge chamber.

[0036] In practical use, several washing zones and several drying zones can be set inside the drum. The impurities in the filter cake are washed multiple times through the washing zones, and the washed filter cake is dried through the drying zones. The filter cake is dried again in the drying zones after each washing, and the washing-drying process can be repeated several times. When the drum uses multi-stage drying and filtration, N washing zones and N drying zones (N being an integer greater than 1) are set between the secondary drying zone and the discharge zone. Correspondingly, N washing liquid discharge chambers and N drying gas discharge chambers are set within the annular cavity between the washing liquid discharge chamber and the secondary drying gas discharge chamber. The distribution head is connected to N-stage washing liquid outlets and N-stage drying gas outlets, respectively connected to the N-stage washing liquid outlets and N-stage drying gas outlets. Generally, the total number of washing zones on the drum is at most four.

[0037] The embodiments and descriptions above are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A gas-pressurized rotary drum filter, comprising a housing and a rotary drum disposed within the housing, the rotary drum having a filter screen and a filter cloth covering the filter screen in its circumferential direction, a motor for driving the rotary drum to rotate being disposed outside the housing, and a slurry feeding area and a filter cake discharging area being disposed below the rotary drum within the housing, characterized in that: One end face of the drum is sealed, and a distribution head rotor is fixedly connected to the other end face. One end of the distribution head rotor is closed, and the other end communicates with the inside of the drum. A distribution head is provided outside the distribution head rotor. An annular cavity exists between the distribution head rotor and the distribution head. Sealing components are provided at both ends of the annular cavity. The distribution head and the sealing components are fixedly connected, and the distribution head rotor and the sealing components rotate in cooperation. Connecting pipes are provided between the distribution head rotor and the drum, distributed circumferentially around the drum. One end of each connecting pipe is fixed inside the drum, and the other end is fixed to the distribution head rotor. Each connecting pipe communicates with the annular cavity. The drum has a filtration zone, a first drying zone, a discharge zone, and a filter cloth backwashing zone arranged sequentially along the rotation direction. The filtration zone is used to contact the slurry in the slurry feeding zone. The filter cloth backwashing zone is adjacent to the filtration zone and located above the slurry zone. The annular cavity contains components connecting to the filtration zone and the first drying zone, respectively. The distribution head has a corresponding mother liquor discharge chamber and a primary drying gas discharge chamber, which are separated by an isolation block. The external part of the distribution head is connected to a mother liquor outlet and a primary drying gas outlet, which are respectively connected to the mother liquor discharge chamber and the primary drying gas discharge chamber. The distribution head is provided with a backflush air inlet and a washing liquid inlet, which are respectively connected to the unloading area of ​​the drum and the backwashing area of ​​the filter cloth through connecting pipes. The sealing assembly includes a pressure cover and a packing. The packing is located between the distribution head rotor and the distribution head. The pressure cover includes an annular pressure part and an annular ring that are fixedly connected together. The annular ring and the annular pressure part are arranged vertically. The annular pressure part is used to press the packing. The annular ring and the distribution head are connected together by a stud. A pressure spring and an adjusting nut are provided on the side of the stud away from the distribution head.

2. The gas pressurized rotary drum filter according to claim 1, characterized in that: Along the rotation direction of the drum, a washing zone and a second drying zone are arranged sequentially between the first drying zone and the unloading zone on the drum. A spraying device fixed in the housing is provided above the washing zone. The annular cavity is provided with a washing liquid discharge chamber and a secondary drying gas discharge chamber corresponding to the washing zone and the second drying zone of the drum, respectively. The distributor head is externally connected to a washing liquid outlet and a secondary drying gas outlet that are respectively connected to the washing liquid discharge chamber and the secondary drying gas discharge chamber.

3. The gas pressurized rotary drum filter according to claim 2, characterized in that: The drum is further provided with an N-stage washing zone and an N-stage drying zone between the secondary drying zone and the unloading zone; correspondingly, the annular cavity is provided with an N-stage washing liquid discharge chamber and an N-stage drying gas discharge chamber between the washing liquid discharge chamber and the secondary drying gas discharge chamber, and the distribution head is connected to an N-stage washing liquid outlet and an N-stage drying gas outlet that are respectively connected to the N-stage washing liquid discharge chamber and the N-stage drying gas discharge chamber.

4. The gas pressurized rotary drum filter according to claim 1, characterized in that: The filter screen includes a bridge frame arranged sequentially along the circumference of the drum. The bridge frame is an arched perforated mesh plate. Each bridge frame is evenly distributed along the circumference of the drum. The filter cloth covers the outside of the bridge frame. The end of the connecting pipe inside the drum is located near the inside of the bridge frame.

5. The gas pressurized rotary drum filter according to claim 4, characterized in that: There is an inverted "Ω" groove between adjacent cable trays. The "Ω" groove is equipped with a clamping element, and the filter cloth located between adjacent cable trays is clamped in the "Ω" groove by the clamping element.

6. The gas pressurized rotary drum filter according to claim 1, characterized in that: The isolation block includes a sealing block and a pressure cap fixed to the distribution head. The sealing block is pressed between the distribution head and the distribution head rotor by the pressure cap, and the pressure cap is fixed to the outer peripheral surface of the distribution head by bolts. The backflush air inlet and the washing liquid inlet both pass through the isolation block.

7. The gas pressurized rotary drum filter according to claim 1, characterized in that: The housing is provided with supports for supporting the drum and the distributor rotor, and the supports are provided with bearing seats, and bearings are provided in the bearing seats; a coupling is connected to the rotating shaft connected to the drum; a reducer is connected to the motor outside the housing, and the reducer is connected to the coupling; a sealing mechanism is provided on the inner and outer sides of the coupling on the housing.

8. The gas pressurized rotary drum filter according to claim 1, characterized in that: The housing includes an upper housing and a lower housing connected by a flange. A partition is provided between the slurry feeding area and the filter cake discharge area. An overflow area is provided on one side of the slurry feeding area, and the filter cake discharge area is located on the other side of the slurry feeding area.

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