Fine grid based on fixed pore plate self-cleaning coupling screw extrusion deslagging

Abstract

The invention discloses a fine grid based on fixed pore plate self-cleaning coupling screw extrusion deslagging, and belongs to the field of sewage and wastewater treatment. The driving gear is fixed above the water surface, the driven gear is fixed below the water surface, the driving gear and the driven gear are provided with a driving chain and a chain supporting plate, and the outer surface of the driving chain is provided with a plurality of brushing and scraping plate arrays; a grating plate is fixed under the water surface, a brushing and scraping plate array is tightly attached to the grating plate, a baffle plate wraps and seals brushing and scraping plates to form a conveying channel, a grating slag removing comb is fixed to an upper end opening of the baffle plate, a grating slag removing hopper groove and a spiral propeller are arranged below the grating slag removing comb, and a variable-diameter spiral discharging extrusion section is arranged at the rear end of the spiral propeller. The spiral propeller motor is fixedly connected with the spiral propeller and used for driving the spiral propeller to work; the fine grid has an excellent overall cleaning effect, the overall occupied space is small, the whole fine grid can be arranged underground, and a better choice is brought to engineering application in the field.

Description

Technical Field

[0001] The invention belongs to the field of sewage and wastewater treatment, and particularly relates to a fine grid sewage and wastewater pretreatment technology based on fixed orifice plate self-cleaning coupling screw extrusion slag removal. Background Art

[0002] In sewage treatment systems (including in front of water pumps), screens must be installed to intercept larger solid pollutants in suspended or floating state. According to the net gap between the bars, they can be divided into three types: coarse screens (50-100mm), medium screens (16-40mm) and fine screens (3-10mm); according to the slag cleaning method, they can be divided into two types: manual slag cleaning screens and mechanical slag cleaning screens. In actual practice, two screens are often set up, that is, a coarse screen is set up in front of the water pump to ensure that the water pump is not blocked, and a fine screen is set up after the water pump to prevent a large number of small particles of dirt from entering the treatment system. With the improvement of sewage and wastewater treatment standards, the minimum bar gap of fine screens has been set to 1mm. In order to intercept hair, fibers, etc. in sewage, some screen screens with a 1mm aperture or perforated plate screens with a 1mm aperture are set up. However, due to the small thickness of the perforated plate, a large amount of fiber entanglement effect occurs under the action of water flow, making it difficult to remove the screen residue.

[0003] The structure of these fine screens can be divided into two types: a rotating drum with a cylindrical screen or perforated plates, and a vertically rotating, serially connected perforated plates with internal water intake. Currently, because fine screens intercept relatively small amounts of waste, sometimes mixed with large amounts of flocculent material, the separation process of the intercepted waste (hereinafter referred to as screens) from the screens is accomplished by backwashing the screens with high-pressure water from the outside of the screens to separate the screens from the screens and complete the cleaning of the screens and screen holes. This results in the screens being mixed with a large amount of water, necessitating a subsequent screens removal step to ultimately separate the screens from the water. This process results in the screen and screens washing process becoming a concentration process, and the screens-water separation process requires a large-volume screens separation tank to accommodate the high water content. This arrangement requires the screens removal section to be located high above the working water surface of the sewage treatment system, which also requires a large surface area. This creates significant vertical and horizontal space requirements for sewage treatment systems, creating significant challenges for integrated systems, particularly those requiring strict landscape and spatial requirements, and for systems where the entire treatment unit is located entirely underground. Often, the entire integrated system is located underground at great expense, and the fine screens must protrude high above the ground. This not only compromises the overall landscape design, but also hinders the collection of odors generated by the screen removal process into the deodorization system, significantly impacting the overall aesthetics and integrity of the treatment system. Summary of the Invention

[0004] The present invention is based on a large number of experiments. Through the changes in the grid plate setting, grid plate cleaning, screen residue separation, screen residue discharge and other forms and the organic combination of multiple links, the fine grid has an excellent overall removal effect, especially for fibrous dirt that is the most difficult to intercept and remove. In addition, the overall space occupied is small, and it is easy to integrate with the water treatment process. The space occupied above the water surface is small. Under the premise of achieving fully automatic residue discharge, the entire system can be set below the ground, providing a better choice for engineering applications in this field. The concept of technical establishment:

[0005] (1) The main problem addressed by the fine grid is the fibrous grid residue, which solves or weakens the problem of entanglement between adjacent holes in the grid and the pinching of existing woven mesh wires;

[0006] (2) Significantly reduce the space required above the working water surface, solve the problem of the height space required for separating the screen residue from the grid plate and the need to rely on pressure water flushing, which makes the subsequent screen residue separation process complicated and occupies a large space;

[0007] (3) Solve the problems of hard scraper jamming and mechanical wear when cleaning the intercepted objects, the performance of the scraper in retaining the scraper during the scraping process, and the problem of taking the scraper away from the water surface to achieve excellent water separation;

[0008] (4) Use the number of "scrapers" to increase the frequency of scraping the grid to avoid excessive accumulation of fiber grid residue, which makes it difficult to remove;

[0009] (5) Solve the problem of cleaning and separating the scraper residue in the "water-free" state;

[0010] (6) Solve the problem of further reducing the moisture content when discharging the screenings.

[0011] Solution:

[0012] Based on the ideas established by the above technologies, the following technical means are used to solve the existing problems.

[0013] (1) Using thick circular hole perforated plate to form a "long" hole channel form to abandon the woven mesh form and the fiber winding effect of thin circular hole perforated plate;

[0014] (2) The grid plate is fixed and the scraper movement is adopted to realize the removal of grid plate slag, and the reverse slag removal form of high-pressure water grid plate is abandoned to reduce the space required above the working water surface and the problem of setting up large grid slag mixed liquid containers;

[0015] (3) Use a high-bristle brush scraper to clean and remove the intercepted objects on the grid, avoid the hard scraper from getting stuck and mechanically wearing, and use the hard brush's ability to retain fibers and small particles of dirt to remove the fiber dirt and take it away from the water surface. When cleaning and removing the intercepted objects on the grid, the screen residue is taken away from the water surface to achieve excellent separation of screen residue from water;

[0016] (4) Use a multi-stage brush scraper setting to increase the frequency of grating cleaning and avoid excessive accumulation of fiber and other grating residues, which makes it difficult to remove;

[0017] (5) Using the cleaning ability of the brush scraper to solve the problem of cleaning and separating the scraping residue on the scraper in a relatively "water-free" state;

[0018] (6) When using the spiral discharging and slag discharging link, a variable diameter spiral discharging and water outlet channel is set up, and the diameter change process is used to further squeeze the screen slag to further reduce the moisture content, so that the screen slag is finally easy to remove.

[0019] The present invention is based on a screw-propelled self-cleaning coupled extrusion slag discharge fine grid, characterized in that it includes a grid plate (2), a brush scraper (3), a drive chain (4), a drive motor (5), a driving gear (6), a driven gear (7), a chain support plate (8), a slag removal comb (11), a slag discharge bucket (12), a screw propeller (13), a variable diameter screw discharge extrusion section (14), an extrusion water outlet trough (15), a drainage hole (16), a slag discharge pipe (17), and a screw propeller motor (18);

[0020] The driving gear (6) is fixed above the water surface, and the driven gear (7) is fixed below the water surface. A drive chain (4) capable of cyclic transmission is provided between the driving gear (6) and the driven gear (7). A chain support plate (8) is provided in the space between the driving gear (6) and the driven gear (7) for supporting the drive chain (4). An array of multiple brush scrapers (3) is provided on the outer surface of the drive chain (4). The multiple brush scrapers (3) are arranged along the length direction (transmission direction) of the drive chain (4). The water-removing device (10) is arranged evenly spaced in the direction of movement; a grid plate (2) is fixed under the water surface, the water-facing surface (i.e., the filtering surface) of the grid plate (2) is parallel to and close to the brush scraper (3) array, a fixed shielding plate (10) is provided above the grid plate (2), the shielding plate (10) encloses the brush scraper (3) to form a conveying channel, the lower end of the shielding plate (10) is connected to the upper end of the grid plate (2), the upper end of the shielding plate (10) is provided with a port, and a screen slag cleaning device is fixed at the upper port of the shielding plate (10). The slag removal comb (11) can contact the brush scraper (3) to comb off the filter residue brought by the brush scraper (3); a slag removal bucket (12) is provided below the slag removal comb (11); a screw propeller (13) is provided at the bottom of the slag removal bucket (12); the front end of the screw propeller (13) is connected to the bottom of the slag removal bucket (12); the rear end of the screw propeller (13) adopts a variable diameter spiral discharge extrusion section (14), wherein the variable diameter spiral discharge The diameter of the screw propeller (13) decreases as the extrusion section (14) moves toward the rear end. A plurality of extrusion water outlet grooves (15) are provided on the inner wall of the variable diameter spiral discharge extrusion section (14). The extrusion water outlet grooves (15) are in communication with the screen slag discharge bucket (12). The rear end outlet of the variable diameter spiral discharge extrusion section (14) is connected to the slag discharge pipe (17). The screw propeller motor (18) is fixedly connected to the screw propeller (13) for driving the screw propeller (13) to work.

[0021] The slag removal bucket (12) and the screw propeller (13) are located on the water surface; the bottom of the slag removal bucket (12) is also provided with a drainage hole (16);

[0022] The front end of the screw propeller (13) spans the bottom of the slag discharge bucket (12);

[0023] The grating plate (2) can be inclined, and the angle between it and the vertical direction is 0-90 degrees and not 90 degrees (0 degrees is the vertical direction, 90 degrees is the horizontal direction), and the driving chain (4) in close contact with it is also inclined; the grating plate (2) can be set at any angle in the underwater part, and the driving chain (4) can be guided by multiple passive gears (7). This setting method allows the entire fine grid to adapt to almost any installation space, and the area of ​​the grating plate can be increased by changing the angle of rotation, thereby achieving any water flow capacity (see Figure 5 (indicated).

[0024] The driving gear (6), the driven gear (7) and the driving chain (4) divide the space into left and right sides, the grid plate (2) and the screen slag removal comb (11) are on the same side, or are located on both sides respectively, and the screen slag removal comb (11) is located on the side to which the gravity direction of the driving gear (6) points; if the grid plate (2) and the screen slag removal comb (11) are on the same side, the shielding plate (10) on the same side adopts a straight section structure; if the grid plate (2) and the screen slag removal comb (11) are located on both sides respectively, an arc-shaped shielding plate is additionally added outside the driving chain (4) portion outside the driving gear (6), and the upper end of the shielding plate (10) is located on the other side;

[0025] The driving chain (4) drives the brush scraper (3) to move in a transmission direction from bottom to top relative to the grid plate (2) to brush the grid plate (2);

[0026] Parameter optimization:

[0027] Grille plate (2): thickness and through-hole depth: 10-60 mm, hole diameter: 1-3 mm, opening rate: 18.00%-24.00%;

[0028] Brush scraper (3): The brush of the brush scraper (3) has elasticity and flexibility, bristle length: 25-60mm, moving speed: 5-50mm / s, and the scraper spacing is set in the range of 300-1000mm in combination with the raw water characteristics;

[0029] Support chain (4) moving speed: 5-50mm / s;

[0030] The cleaning comb (11) is a comb structure with a tooth spacing of 20-50 mm;

[0031] Variable diameter spiral discharge extrusion section (14): the diameter reduction rate is 0.4-0.6, the diameter of the small opening is not less than 200 mm, and the 1 / 4 length portion from the small opening to the large opening is not provided with spiral extrusion blades;

[0032] Extrusion water outlet trough (15): arranged in the lower 1 / 2 area of ​​the inner wall of the variable diameter spiral discharge extrusion section (14), with the number of troughs being greater than or equal to 3, one of which is arranged at the bottom;

[0033] Slag discharge pipe (17): can be set as a straight pipe or a curved pipe (45°-90°), and the outlet direction can be determined according to the installation conditions;

[0034] The fine grille can be tilted as a whole, please refer to the diagram for the setting;

[0035] When the fine screen water flow area is large and the water flow channel is shallow, it can be adjusted by changing the installation tilt angle. As shown in the figure, CC is a right tilt type. As shown in the figure, DD is a left tilt type. The left tilt type screen slag removal bucket (12) is set on the left side, and the screen slag removal comb (11) is a downward reverse cleaning comb setting (the tooth end is tilted downward) ( Figure 4 EE in the middle is an enlarged drawing of the E portion in the DD), and the shielding plate (10) does not need to be provided with an arc-shaped portion.

[0036] The operation mode of the fine screen based on screw propulsion, self-cleaning and coupling extrusion slag discharge:

[0037] Raw water (1) containing small suspended solids and fibrous dirt flows through a grid plate (2) with circular perforations. The grid plate (2) intercepts the dirt to be removed (hereinafter referred to as screen residue) on the water-facing surface of the grid plate (2) through a sieving action, and the dirt is removed by the raw water of the grid plate. The brush scraper (3) is driven upward from bottom to top by a driving chain (4) (as shown in the figure), and the brush end of the brush scraper (3) is pressed against the grid plate (2) and moves upward to remove the screen residue intercepted on the grid plate (2). During this cleaning process, the multiple-stage brush scraper (3) is provided to achieve a short-time frequent cleaning action, so as to prevent the formation of more and larger screen residue accumulation and larger entangled balls of fibrous matter on the surface of the grid plate (2).

[0038] The driving chain (4) for driving the brush scraper (3) to move is composed of a driving gear (6) driven by a driving motor (5) arranged above the water surface and a passive gear (7) arranged below the water surface. The chain support plate (8) arranged between the driving gear (6) and the passive gear (7) ensures that the brush scraper (3) arranged on the chain (4) maintains a stable and accurate relative position with the surface of the grid plate (2), thereby ensuring that the brush scraper (3) has a certain stable cleaning force on the surface of the grid plate (2). The hairs of the brush scraper (3) have a certain elasticity and flexibility, which prevents the brush scraper (3) from being stuck when encountering a hard object stuck on the grid plate (2), thereby forming a certain redundancy performance. Only the space required for the driving gear (6) and the driving motor (5) needs to be reserved above the working water surface (9), and the vertical space occupied is relatively small.

[0039] Driven by the driving chain (4), the brush scraper (3) slowly moves from below the working water surface (9) to above the working water surface (9). When the brush scraper (3) and the screen residue remaining on the brush scraper (3) are lifted up to above the working water surface (9), the screen residue is separated from the vast majority of the flowing water due to the drainage effect of the brush scraper (3); the brush scraper (3) continues to move upward, and is synchronously conveyed to the screen residue removal comb (11) through the chain in combination with the conveying channel formed by the shielding plate (10) on the water surface. At this position, the brush scraper (3) intersects with the screen residue removal comb (11). The brush scraper (3) continues to move to complete the screen residue removal process on the brush scraper (3). The removed screen residue falls to the screen residue collection area by gravity. The screens fall into the bottom of the discharge hopper (12) and are pushed to the variable diameter spiral discharge extrusion section (14) by a screw propeller (13) driven by a screw propeller motor (18) for further dehydration by extrusion. Multiple extrusion water outlet grooves (15) are evenly arranged on the inner wall of the variable diameter pipe (14) of the variable diameter extrusion section along the longitudinal direction. The extruded water flows back along the outlet grooves (15) to the screens discharge hopper (12) and then flows back to the original sewage pool through the drainage hole (16) arranged at the bottom of the screens discharge hopper (12). After being squeezed and dehydrated, the screens with low water content are discharged out of the system through the slag discharge pipe (17) arranged at the rear end of the variable diameter spiral discharge extrusion section (14).

[0040] Comprehensive feature description:

[0041] 1. The grid plate is fixed (immovable), so the water has no washing effect on the grid plate, so the intercepted screen residue will not fall back into the water when the grid plate rotates and moves out of the water. The grid plate has a greatly improved removal rate of screen residue;

[0042] 2. The use of brush scrapers takes advantage of the brush's strong ability to retain screen debris, especially the retention effect on fibrous screen debris. Combined with the multi-level setting of the brush scrapers, the screen's water flow capacity is always kept in a relatively clean and high water flow state, thereby enhancing the screen's overall water flow and interception performance;

[0043] 3. Due to the use of brush scrapers and screenings removal combs, screenings separation is no longer dependent on high-pressure water, which greatly reduces the moisture content of the screenings, eliminating the need for a separate screenings removal process that takes up a large amount of volume and space.

[0044] 4. Since the screens collected in the screens discharge hopper have a low moisture content, they can be moved and pushed directly by the screw propeller. Therefore, the screw propeller blade thrust can be combined with the setting of the reducer to achieve the squeezing and dehydration of the screens, further reducing the moisture content for easy removal.

[0045] 5. Due to the effective arrangement of the above-mentioned links, the overall space requirement of the entire grid for the part above the working water surface is greatly reduced, so that the grid established by the present invention has a wider adaptability in use, especially for the form of water treatment equipment completely set underground, which provides better selection conditions.

[0046] 6. Due to the small vertical space occupied, the odor collection system is easier to set up for projects with deodorization requirements for the overall water treatment system. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a vertical installation diagram of the present invention:

[0048] Figure 2 for Figure 1 AA section view in;

[0049] Figure 3 for Figure 1 BB cross-sectional view in;

[0050] Figure 4 Schematic diagram of two other structural devices of the present invention;

[0051] Figure 5 A fourth structural device of the present invention is shown;

[0052] Raw water containing small suspended solids and fibrous dirt (1), a circular perforated grating plate (2), a brush scraper (3), a rotating drive chain (4), a chain drive motor (5), a chain drive active gear (6), a chain drive passive gear (7), a chain support plate (8), a working water surface (9), vertical and upper semicircular shielding plates (10), a screen slag removal comb (11), a screen slag removal bucket (12), a screw propeller (13), a variable diameter screw discharge extrusion section (14), an extruded water outlet trough (15), a drainage hole at the bottom (16), a slag discharge pipe (17), and a screw propeller motor (18). DETAILED DESCRIPTION

[0053] The present invention will be further described below with reference to the examples, but the present invention is not limited to the following examples.

[0054] Example 1

[0055] Fine screen water flow: 50m 3 / h; Raw sewage contains a lot of hair (school bathing drainage); Circular perforated grating plate (2) thickness: 50mm, width 0.9m, height 1.2m, perforated plate perforation area: 1m 2; Aperture 1mm; Opening rate: 17.69%; Brush scraper (3) hair length: 30mm; Brush scraper (3) spacing: 500mm; Chain moving speed: 5mm / s; Cleaning comb (11) tooth spacing: 30mm; Screw propeller spiral horizontal propulsion speed: 300mm / min; Variable diameter spiral discharge extrusion section (14): Variable diameter rate 0.4, small mouth end diameter: 200mm; Extrusion water outlet trough (15): 3 drainage troughs are set, one of which is set at the bottom; Slag discharge pipe (17): composed of two 45° elbows to form a 90° angle for downward slag discharge; The grid is set vertically.

[0056] The fine screen only needed to extend 600mm above the working water surface, eliminating the need for a bulky slag-water separation tank. After continuous operation, the screen plates were virtually free of hair entanglement. Sampling tests revealed an average hair pass rate of only 0.6%, while the screen residue had a moisture content of 54%.

[0057] Implementation Example 2

[0058] The sewage is from a rural village, with a volume of 53m 3 / d, there is no coarse screen in front of the fine screen device, and the raw sewage is pretreated only by the first-level fine screen.

[0059] The grating is a circular perforated grating with a 3mm aperture, a width of 0.4m, a height of 0.8m, and an open area ratio of 24%. The brush scraper (3) has a bristle length of 45mm and a spacing of 500mm between the brush scrapers (3). The chain travel speed is 50mm / s. The cleaning comb (11) has a tooth spacing of 20mm. The screw propeller has a horizontal propulsion speed of 300mm / min. The variable diameter screw discharge extrusion section (14) has a variable diameter ratio of 0.4 and a small end diameter of 200mm. The extrusion water outlet trough (15) has three drainage troughs, one of which is located at the bottom. The slag discharge pipe (17) consists of a single 45° elbow, forming a 45° angle to discharge slag downward to the slag bucket. The fine grating is vertically arranged. The fine grating is set 600mm above the working water surface, and no large slag-water separation tank is installed. The equipment has been in continuous operation for 18 months, and the average moisture content of the slag is 82%.

Claims

1. A fine grid based on fixed orifice plate self-cleaning coupled screw extrusion slag, characterized in that: It comprises a grid plate (2), a brush scraper (3), a driving chain (4), a driving motor (5), a driving gear (6), a driven gear (7), a chain support plate (8), a screen slag removal comb (11), a screen slag removal bucket (12), a screw propeller (13), a variable diameter screw discharge extrusion section (14), an extrusion water outlet trough (15), a drainage hole (16), a slag discharge pipe (17), and a screw propeller motor (18); The driving gear (6) is fixed above the water surface, and the driven gear (7) is fixed below the water surface. A drive chain (4) capable of cyclic transmission is provided between the driving gear (6) and the driven gear (7). A chain support plate (8) is provided in the space between the driving gear (6) and the driven gear (7) for supporting the drive chain (4). An array of multiple brush scrapers (3) is provided on the outer surface of the drive chain (4). The multiple brush scrapers (3) transmit the drive chain (4) along the length direction. The conveying direction is evenly spaced; a grid plate (2) is fixed under the water surface, the water-facing surface of the grid plate (2), i.e., the filtering surface, is parallel to and closely attached to the brush scraper (3) array; a fixed shielding plate (10) is provided above the grid plate (2); the shielding plate (10) encloses the brush scraper (3) to form a conveying channel; the lower end of the shielding plate (10) is connected to the upper end of the grid plate (2); a port is left at the upper end of the shielding plate (10); a screen slag removal device is fixed at the upper port of the shielding plate (10) The comb (11) can contact the scraper (3) to comb out the filter residue brought by the scraper (3); a scraper removal hopper (12) is provided below the scraper removal comb (11); a screw propeller (13) is provided at the bottom of the scraper removal hopper (12); the front end of the screw propeller (13) is connected to the bottom of the scraper removal hopper (12); the rear end of the screw propeller (13) adopts a variable diameter screw discharge extrusion section (14), wherein the variable diameter screw discharge The diameter of the screw propeller (13) decreases as the extrusion section (14) moves toward the rear end. A plurality of extrusion water outlet grooves (15) are provided on the inner wall of the variable diameter spiral discharge extrusion section (14). The extrusion water outlet grooves (15) are in communication with the screen slag discharge bucket (12). The rear end outlet of the variable diameter spiral discharge extrusion section (14) is connected to the slag discharge pipe (17). The screw propeller motor (18) is fixedly connected to the screw propeller (13) for driving the screw propeller (13) to work. The slag removal bucket trough (12) and the screw propeller (13) are located on the water surface; the bottom of the slag removal bucket trough (12) is also provided with a drainage hole (16).

2. A fine grid based on fixed orifice plate self-cleaning coupled screw extrusion slag removal according to claim 1, characterized in that: The front end of the screw propeller (13) spans the bottom of the screening slag discharge bucket (12).

3. A fine grid based on fixed orifice plate self-cleaning coupled screw extrusion slag removal according to claim 1, characterized in that: The grid plate (2) is inclined, and the angle between the grid plate and the vertical direction is 0-90 degrees and is not 90 degrees, 0 degrees is the vertical direction, and 90 degrees is the horizontal direction. The driving chain (4) in close contact with the grid plate (2) is also inclined.

4. A fine grid based on fixed orifice plate self-cleaning coupled screw extrusion slag removal according to claim 3, characterized in that: The grid plate (2) can be set at any angle in the underwater part, and the driving chain (4) can be guided by multiple passive gears (7). This setting method allows the entire fine grid to adapt to almost any installation space, and the grid plate area can be increased by changing the angle of rotation, thereby achieving any water flow capacity.

5. A fine grid based on fixed orifice plate self-cleaning coupled screw extrusion slag removal according to claim 1, characterized in that: The driving gear (6), the driven gear (7) and the driving chain (4) divide the space into left and right sides, the grid plate (2) and the screen slag removal comb (11) are on the same side, or are located on both sides respectively, and the screen slag removal comb (11) is located on the side to which the gravity direction of the driving gear (6) points; if the grid plate (2) and the screen slag removal comb (11) are on the same side, the shielding plate (10) on the same side adopts a straight section structure; if the grid plate (2) and the screen slag removal comb (11) are located on both sides respectively, an arc-shaped shielding plate is additionally added outside the driving chain (4) portion outside the driving gear (6), and the upper end of the shielding plate (10) is located on the other side.

6. A fine grid based on screw-propelled self-cleaning coupling extrusion slag removal according to claim 1, characterized in that: It is a right-side inclined type or a left-side inclined type. The left-side inclined screen slag removal bucket (12) is arranged on the left side, and the screen slag removal comb (11) is arranged to be obliquely downward and reversely combed. At the same time, the shielding plate (10) does not need to be provided with an arc-shaped part.

7. A fine grid based on fixed orifice plate self-cleaning coupled screw extrusion slag removal according to claim 1, characterized in that: The driving chain (4) drives the brush scraper (3) in a transmission direction: relative to the grid plate (2), the brush scraper (3) is transmitted from bottom to top to brush the grid plate (2).

8. A fine grid based on fixed orifice plate self-cleaning coupled screw extrusion slag removal according to claim 1, characterized in that: Grille plate (2): thickness and through-hole depth: 10-60 mm, hole diameter: 1-3 mm, opening rate: 18.00%-24.00%; Brush scraper (3): The brush of the brush scraper (3) has elasticity and flexibility, bristle length: 25-60mm, moving speed: 5-50mm / s, and the scraper spacing is set in the range of 300-1000mm in combination with the raw water characteristics; Support chain (4) moving speed: 5-50mm / s; The cleaning comb (11) is a comb structure with a tooth spacing of 20-50 mm; The variable diameter spiral discharging extrusion section (14) has a diameter change rate of 0.4-0.6, a diameter of the small end is not less than 200 mm, and no spiral extrusion blades are provided in the 1 / 4 length portion from the small end to the large end.

9. A fine grid based on fixed orifice plate self-cleaning coupled screw extrusion slag removal according to claim 1, characterized in that: Extrusion water outlet trough (15): arranged in the lower 1 / 2 area of ​​the inner wall of the variable diameter spiral discharge extrusion section (14), with the number of troughs being greater than or equal to 3, one of which is arranged at the bottom. Slag discharge pipe (17): can be set as a straight pipe or a 45°-90° bend, and the outlet direction can be determined according to the installation conditions.

10. The operating mode of the fine grid based on the fixed orifice plate self-cleaning coupled screw extrusion slag removal according to any one of claims 1 to 9, characterized in that: Raw water (1) containing small suspended solids and fibrous dirt flows through a grid plate (2) with circular perforations. The grid plate (2) intercepts the dirt to be removed (hereinafter referred to as screen residue) on the water-facing surface of the grid plate (2) through a sieving action, and the dirt is removed by the raw water of the grid plate. The brush scraper (3) is driven upward from bottom to top by a driving chain (4) (as shown in the figure), and the brush end of the brush scraper (3) is pressed against the grid plate (2) and moves upward to remove the screen residue intercepted on the grid plate (2). During this cleaning process, the multiple-stage brush scraper (3) is provided to achieve a short-time frequent cleaning action, so as to prevent the formation of more and larger screen residue accumulation and larger entangled balls of fibrous matter on the surface of the grid plate (2). The driving chain (4) for driving the brush scraper (3) to move is composed of a driving gear (6) driven by a driving motor (5) arranged above the water surface and a passive gear (7) arranged below the water surface. The chain support plate (8) arranged between the driving gear (6) and the passive gear (7) ensures that the brush scraper (3) arranged on the chain (4) maintains a stable and accurate relative position with the surface of the grid plate (2), thereby ensuring that the brush scraper (3) has a certain stable cleaning force on the surface of the grid plate (2). The hairs of the brush scraper (3) have a certain elasticity and flexibility, which prevents the brush scraper (3) from being stuck when encountering a hard object stuck on the grid plate (2), thereby forming a certain redundancy performance. Only the space required for the driving gear (6) and the driving motor (5) needs to be reserved above the working water surface (9), and the vertical space occupied is relatively small. Driven by the driving chain (4), the brush scraper (3) slowly moves from below the working water surface (9) to above the working water surface (9). When the brush scraper (3) and the screen residue remaining on the brush scraper (3) are lifted up to above the working water surface (9), the screen residue is separated from the vast majority of the flowing water due to the drainage effect of the brush scraper (3); the brush scraper (3) continues to move upward, and is synchronously conveyed to the screen residue removal comb (11) through the chain in combination with the conveying channel formed by the shielding plate (10) on the water surface. At this position, the brush scraper (3) intersects with the screen residue removal comb (11). The brush scraper (3) continues to move to complete the screen residue removal process on the brush scraper (3). The removed screen residue falls to the screen residue collection area by gravity. The screens fall into the bottom of the discharge hopper (12) and are pushed to the variable diameter spiral discharge extrusion section (14) by a screw propeller (13) driven by a screw propeller motor (18) for further dehydration by extrusion. Multiple extrusion water outlet grooves (15) are evenly arranged on the inner wall of the variable diameter pipe (14) of the variable diameter extrusion section along the longitudinal direction. The extruded water flows back along the outlet grooves (15) to the screens discharge hopper (12) and then flows back to the original sewage pool through the drainage hole (16) arranged at the bottom of the screens discharge hopper (12). After being squeezed and dehydrated, the screens with low water content are discharged out of the system through the slag discharge pipe (17) arranged at the rear end of the variable diameter spiral discharge extrusion section (14).

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