Efficient grit chamber structure before sand retention and after water flow

Abstract

The invention belongs to the technical field of grit chambers, and particularly relates to a high-efficiency grit chamber structure before sand retention and after water flow, the high-efficiency grit chamber structure comprises a water inlet channel and a chamber body, the front short side slope of the chamber body is provided with a water inlet groove, one side, close to the chamber body, of the water inlet groove is provided with a comb tooth type water inlet, and the rear short side slope of the chamber body is provided with a clean water tank; a desilting channel is arranged in the middle of one side of the long side slope of the pond body, the water inlet channel is communicated with the water inlet groove, and a water distribution gate is arranged at the front end of the water inlet channel. The hydraulic structure with the comb tooth type water inlet is arranged in the sand setting front pond, and the mechanical desilting ramp is arranged on the side slope of the sand setting pond, so that the efficient sand setting effect before sand retention and after water flow can be achieved, and silt cleaning is facilitated.

Description

Technical Field

[0001] The present invention belongs to the technical field of grit chambers, and particularly relates to a high-efficiency grit chamber structure with sand remaining in the front and water flowing in the rear. Background Art

[0002] The grit chamber at the drip irrigation head is the first line of defense in the drip irrigation pipe network project. The treatment of sediment in surface water sources has always been the primary task in the research of drip irrigation projects. The commonly used grit chamber at the drip irrigation head is a strip-shaped grit chamber, which directly introduces water into the grit chamber through a rectangular or trapezoidal cross-section channel. However, when the water depth in the grit chamber is small, the flow velocity of the incoming water is much greater than the flow velocity in the chamber. The water flow carries the suspended sediment to the end of the grit chamber and enters the drip irrigation pipe network system, resulting in an unclear sedimentation effect, serious wear of the water pump impeller, and a high backwashing frequency of the filter after the pump. In the application of the grit chamber in drip irrigation projects, various solutions such as side inlet of the channel and segmented sand retaining dams added to the bottom of the grit chamber have also been considered, but the sedimentation effects are not obvious. More sediment still enters the rear section of the grit chamber and then enters the drip irrigation system, causing blockage of the drip irrigation belt.

[0003] Therefore, how to provide a high-efficiency grit chamber structure that can improve the sediment deposition position and facilitate sediment cleaning has become a problem that needs to be considered by those skilled in the art. Summary of the Invention

[0004] In view of the problems existing in the above-mentioned prior art, a high-efficiency grit chamber structure with sand remaining in the front and water flowing in the rear is disclosed in the present invention. By setting a comb-tooth type water inlet structure in the pre-sedimentation tank of the grit chamber and setting a mechanical dredging ramp on the slope of the grit chamber, the present invention can achieve the high-efficiency sedimentation effect of "sand remaining in the front and water flowing in the rear" and facilitate the cleaning of sediment. The present invention specifically discloses the following technical solutions:

[0005] A high-efficiency grit chamber structure with sand remaining in the front and water flowing in the rear, an inlet channel is arranged on the front short slope of the tank body, a comb-tooth type water inlet is arranged on one side of the inlet channel close to the tank body, a clear water tank is arranged on the rear short slope of the tank body, a dredging channel is arranged in the middle of one side of the long slope of the tank body, the inlet channel is communicated with the inlet channel, and a dividing gate is arranged at the front end of the inlet channel.

[0006] Further, the comb-tooth type water inlet includes a number of overflow slots arranged at equal intervals, and the bottom end of the overflow slot is exactly located at the top of the front short slope of the tank body.

[0007] Further, concave grooves are arranged on both sides of the overflow slot, and a primary filter grille is inserted into the concave groove.

[0008] Further, it further includes a secondary sewage cleaning mechanism, and the secondary sewage cleaning mechanism is arranged above the clear water tank.

[0009] Furthermore, the secondary cleaning mechanism includes a diversion low wall, a bracket, an inclined diversion mechanism, and a V-shaped floating debris trough. The diversion low wall is arranged at the connection between the clear water tank and the tank body. The height difference between the top of the diversion low wall and the overflow trough opening is 10 cm. A water passing trough is arranged below the diversion low wall, and the height of the water passing trough is one-third of the depth of the tank body. The bracket is installed in the clear water tank, and both the inclined diversion mechanism and the V-shaped floating debris trough are arranged on the bracket. The inclined diversion mechanism is arranged on the back of the diversion low wall, and the V-shaped floating debris trough is arranged below the end of the inclined diversion mechanism.

[0010] Furthermore, it also includes a sand retaining weir located in the water passing trough. The height of the inclined slope on the back of the tank body is one-fourth of the depth of the tank body, and the sand retaining weir is arranged at the top of the back slope.

[0011] Furthermore, the inclined diversion mechanism is a diversion plate placed obliquely, and baffles are arranged on both sides of the diversion plate.

[0012] Furthermore, the inclined diversion mechanism is a conveyor belt arranged obliquely.

[0013] Furthermore, a filtering fine grid is installed in the V-shaped floating debris trough.

[0014] Furthermore, a trash rack is arranged between the sand retaining weir and the diversion low wall.

[0015] The beneficial effects of the present invention are as follows:

[0016] 1. By adjusting the structure of the water inlet, the flow pattern of the water flowing into the tank is completely changed, and the sand sedimentation effect is significantly improved. The comb-tooth type water inlet effectively reduces the flow velocity of the incoming water flow, realizes the physical sedimentation of suspended matter in the form of an "inverted parabola" under the action of hydraulics, realizes sedimentation in the upper 2 / 3 section of the grit chamber, forms an efficient sedimentation effect of "sand remains in the front and water flows in the back", effectively precipitates the sediment in the water to the upstream section of the grit chamber, processes the suspended matter with a particle size of more than 0.05 mm in the water, reduces the wear of the water pump caused by sediment, reduces the probability of filter blockage caused by sediment, reduces pipeline siltation, and extends the service life of drip irrigation facilities;

[0017] 2. The present invention fully considers the influence of the size of the grit chamber and the guardrail, and does not directly carry out dredging or hydraulic sand washing on the top of the tank by machinery. Instead, a mechanical dredging ramp is set on the slope, and a loader enters the bottom of the tank for dredging treatment. The dredging efficiency is high, and the dredging treatment is clean and fast;

[0018] 3. The setting of the primary filtering grid in the present invention can conduct primary filtering on the floating objects in the river water. The setting of the secondary cleaning mechanism can divert the water flow and conduct secondary collection on the floating objects on the water surface. The setting of the detachable fine grid can make the intercepted floating impurities adhere to the surface of the fine grid, which is convenient for cleaning. Description of the Drawings

[0019] Figure 1 This is the top view of the present invention;

[0020] Figure 2 This is the schematic structural view of the water inlet tank part of the present invention;

[0021] Figure 3 This is the schematic installation view of the primary filter grille in Embodiment 2 of the present invention;

[0022] Figure 4 This is the schematic structural view of the clear water tank and the secondary sewage cleaning mechanism in Embodiment 3 of the present invention;

[0023] Figure 5 This is the schematic installation view of the trash rack in Embodiment 5 of the present invention.

[0024] Among them, 1, water inlet channel; 2, tank body; 3, water inlet tank; 4, overflow tank opening; 5, clear water tank; 6, diversion sluice; 7, concave groove; 8, primary filter grille; 9, sand retaining weir; 10, diversion low wall; 11, support; 12, inclined diversion mechanism; 13, V-shaped floating debris collecting tank; 14, detachable fine mesh grille; 15, silt cleaning channel; 16, trash rack. Specific embodiments

[0025] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0026] Embodiment 1

[0027] Referring to the attached Figure 1-2 , this embodiment discloses a high-efficiency grit chamber structure with sand remaining in front and water flowing behind, including a water inlet channel 1 and a tank body 2. A water inlet tank 3 is arranged on the front short slope of the tank body 2 for energy dissipation of water flow. A comb-tooth type water inlet is arranged on one side of the water inlet tank 3 close to the tank body 2. The comb-tooth type water inlet is provided with a number of overflow tank openings 4 at equal intervals. The bottom end of the overflow tank opening 4 is exactly located at the top of the front short slope of the tank body, for dispersing concentrated water flow and flowing into the grit chamber through weir flow, so as to achieve the purpose of reducing the inlet flow velocity. A clear water tank 5 is arranged on the rear short slope of the tank body 2. A silt cleaning channel is arranged in the middle of one side of the long slope of the tank body 2. The water inlet channel 1 is communicated with the water inlet tank 3. A diversion sluice 6 is arranged at the front end of the water inlet channel 1 for controlling the inlet water flow.

[0028] Specifically, taking the water source of the Weigan River Irrigation Area in Shaya County - the water of the Weigan River as an example, a large amount of sediment will be brought to the drip irrigation water source during the sand flushing of the Kizil Reservoir in the upper reaches, the entry of wind and sand along the line into the water, the flood period of the river channel, and the water conveyance in the natural river channel. Therefore, how to set up a grit chamber, determine the size of the grit chamber, and control the sedimentation speed has become the primary task considered in the drip irrigation system.

[0029] The average annual total sediment transport volume of the Weigan River is 73.62×10 4 t, and the sediment transport volume in the continuous maximum four months (June - September) accounts for 92.45% of the suspended sediment transport volume. The annual total sediment transport volume is 68.06×10 4 t. The 50% guarantee rate is that the annual total water volume of the river channel is 2.96 billion m 3 , then the average sediment content in the river channel is 2.3 kg / m 3 .

[0030] According to the sediment content and sediment particle size analysis results of the Weigan River, the sedimentation calculation methods in the "Design Atlas of Drip Irrigation Projects" and "Design of Grit Chambers in Water Resources and Hydropower Projects" are respectively used for calculation. After comparison, the appropriate size of the grit chamber is determined to ensure a better sedimentation effect.

[0031] 1. Determination of grit chamber parameters

[0032] (1) Surface loading rate:

[0033] The surface loading rate refers to the water production per unit surface area of the grit chamber. It is calculated by the following formula:

[0034] V 0 = Q / A

[0035] Where: V 0 ——Surface loading rate, m / h;

[0036] Q——Design flow rate, m 3 / s;

[0037] Ac——Surface area of the grit chamber, m 2 .

[0038] The "Technical Specification for Micro - irrigation Projects" stipulates that the surface loading rate of the grit chamber should not be greater than 3.0 mm / s. The specific value should be selected according to the water quality of the canal water and the requirements of the drip irrigation system for water quality. Adopt V 0 = 0.72 - 7.2 m / h, and the value taken in this design is 0.72.

[0039] (2) Horizontal flow velocity: Increasing the horizontal flow velocity of the grit chamber, on the one hand, increases the Reynolds number Re, which is not conducive to the sedimentation of sediment particles. On the other hand, it increases the Froude number Fr, increasing the stability of the water flow and being conducive to improving the sedimentation effect. According to experience, the design value is 36 m / h.

[0040] (3) Retention time: The retention time of the grit chamber should consider the water quality of the canal water and the requirements of the drippers for water quality. According to operation experience, T 停留 = 1 - 3h. T 停留 is taken as 2.0h according to the flow rate.

[0041] 2. Calculation of grit chamber parameters

[0042] The grit chamber has a trapezoidal cross-section. The sediment content of the project water source is 2.3 kg / m 3 , mainly fine sand, and the organic matter content is average. The design of this grit chamber is divided into two types: double-system and single-system. Among them, the double-system has two heads sharing one grit chamber (the maximum flow rate is 790.27 m 3 / h), and the single-system has one head using one grit chamber (the maximum flow rate is 435.6 m 3 / h).

[0043] (1) Determination of grit chamber size

[0044] ① Surface area of the grit chamber

[0045] A 沉砂池 = Q / v 0

[0046] A 沉砂池 — Surface area of the grit chamber m 2 ,

[0047] Q 并 — Design flow rate 790.27 m 3 / h,

[0048] Q 单 — Design flow rate 435.6 m 3 / h,

[0049] v 0 — Surface loading rate, taken as 0.72 m / h

[0050] After calculation, the surface area of the grit chamber is A 并＝ 1094.22 m 2 ; A 单 = 603 m 2 .

[0051] ② Length of the grit chamber

[0052] L 沉砂池 = vT 停留

[0053] L 沉砂池 — Length of the grit chamber m;

[0054] v — Horizontal flow velocity 36 m / h;

[0055] T停留 — The retention time is taken as 2.0 h.

[0056] After calculation, the length of the grit chamber is 72 m. Since the flow rates of the single and double systems differ by about 1 time and the flow velocities also differ greatly, the lengths of the grit chambers are initially selected as L_double = 120 m and L_single = 70 m in this design.

[0057] ③ Average width of the grit chamber

[0058]

[0059] B 沉砂池 — Average width of the grit chamber;

[0060] A 沉砂池 — Surface area of the grit chamber, m 2 ;

[0061] L 沉砂池 — Length of the grit chamber, m;

[0062] After calculation, the width of the grit chamber is B 并 = 9.11 m, and 12 m is taken in the design; B 单 = 8.6 m, and 9 m is taken in the design.

[0063] ④ (Effective) water depth of the grit chamber

[0064]

[0065] H 1 — (Effective) water depth of the grit chamber, m,

[0066] Q — Design flow rate, m 3 / h;

[0067] T 停留 — Retention time, 2 h;

[0068] A 沉砂池 — Surface area of the grit chamber, m 2 ;

[0069] After calculation, the effective water depth of the grit chamber is 1.44 m.

[0070] ⑤ Depth of the sludge storage area

[0071]

[0072] H 2 — Depth of the sludge storage area, m;

[0073] Q — Design flow rate, m 3 / h;

[0074] C 0— The concentration of sediment with a particle size equal to or larger than the design standard in the water flow entering the grit chamber is 1 kg / m³. 3 ;

[0075] T — The irrigation cycle of drip irrigation is 100 h.

[0076] γ — The sediment specific gravity is 1780 kg / m³. 3 ;

[0077] A 沉砂池 — The surface area of the grit chamber is m². 2 ;

[0078] After calculation, the depth of the sludge storage area is H 并 = 0.041 m. Each sub - irrigation cycle is about 14 times, so the sludge storage depth during the irrigation cycle is 0.57 m.

[0079] ⑥ Depth of the grit chamber

[0080] H 3 = H 1 + H 2 + Δ

[0081] H 3 — The depth of the grit chamber is m.

[0082] H 1 — The (effective) water depth of the grit chamber is 1.44 m.

[0083] H 2 — The depth of the sludge storage area is 0.57 m.

[0084] Δ — The safety freeboard is 0.4 m.

[0085] After calculation, the depth of the grit chamber is 2.41 m, and the design value is taken as 2.5 m.

[0086] (2) Check the hydraulic conditions of the grit chamber

[0087] ① Cross - sectional area of the flow

[0088] ω = B 沉砂池 H1

[0089] B 沉砂池 — The average width of the grit chamber is m.

[0090] ω — The cross - sectional area of the flow is m². 2 ,

[0091] H1 — The (effective) water depth of the grit chamber is m.

[0092] The cross - sectional area of the flow is ω 并 = 17.33 m², ω 2 = 13 m². 单 2 .

[0093] ②Hydraulic wetted perimeter

[0094] The hydraulic wetted perimeter is X 并 = 17.05 m, X 单 = 14.05 m.

[0095] ③Hydraulic radius

[0096] R 水 = ω / X

[0097] The hydraulic radius is R 并 = 1.02 m, R 单 = 0.93 m.

[0098] The hydraulic condition is checked as follows:

[0099] ④Reynolds number

[0100] Re = vR / r

[0101] Re - Reynolds number

[0102] v - Horizontal flow velocity 0.001 m / s,

[0103] R - Hydraulic radius

[0104] r - Kinematic viscosity coefficient of water 1.01×10 -6 ,

[0105] After calculation, the Reynolds number is R e并 = 220986, R e单 = 110866, both are greater than 500, and it is turbulent flow.

[0106] ⑤Froude number

[0107] Fr = v 2 / √(Rg)

[0108] Fr - Froude number,

[0109] v - Horizontal flow velocity 0.001 m / s,

[0110] R - Hydraulic radius, m,

[0111] g - Acceleration due to gravity 9.8 m / s 2 ,

[0112] After calculation, the Froude number is Fr 并 = 4.8×10 -3 , Fr 单 = 1.6×10 -4 , greater than 10 -5 , meeting the requirement of stable water flow.

[0113] (3) Calculation conclusion

[0114] After trial calculation, the lengths of the grit chamber body are taken as L 并 = 120m, L 单 = 70m, the average bottom width of the tank is taken as B 并 = 12m, B 单 = 9m, the slope coefficient is 1:1.75, and the depth of the tank is 2.5m.

[0115] The designed grit chamber adopts a concrete trapezoidal cross-section structure. The size of the grit chamber is selected according to the flow rate of the drip irrigation system. Among them: the size of the grit chamber for the combined system is length × width × height = 120 × 12 × 2.5m, and the size of the single system is 70 × 9 × 2.5m.

[0116] 3. Analyze using the relevant methods of "Design Code for Sedimentation Tanks in Water Resources and Hydropower Projects" (SL / T 269-2019)

[0117] According to the relevant calculation methods and formulas of this code, combined with the actual situation of this project, the sedimentation rate of the sediment particles with a diameter greater than 0.05mm in the designed grit chamber is not less than 85%. The sediment parameters are the same as before.

[0118] (1) Water depth at the inlet of the working section

[0119]

[0120] In the formula: H — water depth at the inlet of the working section (m);

[0121] Z — water level difference between the inlet of the working section and the natural river water level at the outlet of the sediment drainage channel (m);

[0122] q — scouring velocity at the scouring outlet of the sediment drainage channel (m / s);

[0123] υc — scouring velocity at the outlet of the sediment drainage channel (m / s);

[0124] i — bottom slope of the working section of the grit chamber;

[0125] Lw — length of the working section of the grit chamber (m), and the sedimentation tank with regular flushing in water conservancy projects includes the length of the overflow weir area;

[0126] io — bottom slope of the sediment drainage channel;

[0127] Lo — length of the sediment drainage channel;

[0128] (2) The working depth at the inlet of the working section is calculated according to the following formula:

[0129] H e = H - △H k

[0130] In the formula: He — working depth at the inlet of the working section (m);

[0131] Hk — The designed sediment deposition thickness at the inlet of the working section (m). When initially formulating the plan, for the regular flushing type grit chamber of the hydraulic project, it can be selected as (0.5 - 0.6)H; in this case, 0.5H is taken.

[0132] (3) Calculation of the working width

[0133] The working width is calculated by the following formula:

[0134]

[0135] In the formula: Q — The working flow rate (m 3 / s);

[0136] v — The average flow velocity in the working section (m / s). When initially formulating the plan, when the minimum sediment settling particle size in the grit chamber is 0.05 mm, the average flow velocity is taken as 0.05 m / s;

[0137] Hw — The average working depth (m);

[0138] (4) Calculation of the settling velocity of suspended sediment

[0139] For the part with a particle size less than 0.062 mm, the sedimentation analysis method is adopted; for the part with a particle size greater than 0.062 mm, the particle size distribution of the suspended sediment obtained by the sieve analysis method is used, and the settling velocity of the particle size class is calculated using the following formula.

[0140] When the particle size is equal to or less than 0.062 mm, Stokes' formula is used for calculation:

[0141]

[0142] When the particle size is 0.062 - 2.0 mm, Sha Yuqing's formula for the settling velocity of natural sand is used for calculation:

[0143]

[0144] (lgSa + 3.790) 2 +(lgψ - 5.777) 2 =39.0

[0145] When the particle size is greater than 2.0 mm, Sha Yuqing's formula for the settling velocity in the turbulent flow region is used for calculation:

[0146]

[0147] In the above formulas, υ — The kinematic viscosity of water (cm 2 / s);

[0148] t — The water temperature (°C);

[0149] d — The sediment particle size (mm);

[0150] ρ s — Sediment density (g / cm 3 )

[0151] ρ w — Density of clear water (g / cm 3 );

[0152] ω — Settling velocity of sediment (cm / s);

[0153] g — Acceleration due to gravity (cm / s 2 );

[0154] S a — Settling velocity criterion;

[0155] ψ — Particle size criterion;

[0156] The average settling velocity of the particle size group uses the geometric mean of the settling velocities of the upper and lower limit particle sizes:

[0157]

[0158] Where — Average settling velocity of the particle size group (cm / s);

[0159] ω i — Settling velocity of the lower limit particle size of the particle size group (cm / s);

[0160] ω i+1 — Settling velocity of the upper limit particle size of the particle size group (cm / s);

[0161] (5) Sediment settlement calculation

[0162] The working depth and siltation thickness of the grit chamber vary along the way. The grit chamber should be divided into n calculation sections, and the water surface line should be calculated from downstream to upstream according to the following formula:

[0163]

[0164] Where: L k — Length of the k section (m);

[0165] H k 、H k+1—k Water depths of the upper and lower sections of the section (m);

[0166] v k 、v k+1—k Flow velocities of the upper and lower sections of the section (m);

[0167] i k — Longitudinal slope of the k section bed;

[0168] — Average hydraulic gradient of the k section;

[0169] g — acceleration due to gravity (m / s 2 );

[0170] — average flow velocity in the k-th pond section (m / s);

[0171] R k 、R k+1 — hydraulic radius of the upper and lower cross-sections of the k-th pond section (m);

[0172] — average hydraulic radius of the k-th pond section (m);

[0173] — average Chezy coefficient of the k-th pond section;

[0174] n — roughness coefficient, generally the same for each pond section, taken as 0.025 in the design.

[0175] k — pond section number, sorted from the inlet of the working section to the end of the pond or the beginning of the overflow weir area, k = 1, 2, …, n.

[0176] (6) Sedimentation rate calculation

[0177] Calculate the change in the sediment concentration of each calculation section group, the sedimentation rate of each pond section group, the sedimentation rate of the whole pond group, and the sedimentation rate greater than a certain particle size class from the upstream to the downstream for each pond section.

[0178] ① The change in the sediment concentration of the lower cross-section of the pond section is calculated as follows

[0179]

[0180] Where S ik 、S i(k+1) — sediment concentration of the upper and lower cross-sections of the k-th pond section group (kg / m 3 );

[0181] α ik — recovery saturation coefficient of the particle size group in the k-th pond section;

[0182] — average settling velocity of the particle size group (m / s);

[0183] q k — unit width flow rate in the k-th pond section [m 3 / (s·m)];

[0184] i — particle size group number, sorted from small to large by particle size, i = 1, 2, …, m.

[0185] ② The sedimentation rate of the pond section group is calculated as follows:

[0186]

[0187] where η ik — sedimentation rate of particle size group i in k cell section.

[0188] ③ The sedimentation rate of the whole pond by groups is calculated according to the following formula:

[0189] When there is no inlet flume (overflow weir area) in the working section

[0190]

[0191] where η i — sedimentation rate of particle size group i in the whole pond.

[0192] ④ Percentage (%) of sediment weight of particle size group i in the sediment deposited in the grit chamber.

[0193]

[0194] where △P di — percentage (%) of sediment weight of particle size group i in the sediment deposited in the grit chamber or in the flow of the corridor and sediment discharge hole.

[0195] ⑤ Calculation results

[0196] According to the above formulas, the grit chamber is calculated section by section, and the design parameters and results are as follows.

[0197] Design parameter table

[0198]

[0199]

[0200] Grit removal effect table

[0201] Project Common grit chamber Single pond Sediment content out of the pond is 0.008131 0.003926 Total sediment settlement rate of the whole pond 0.996465 0.998293 Settlement rate of particles larger than 0.05mm 0.988741 0.994564

[0202] Grit removal volume and thickness at different cross-sections

[0203]

[0204] This method is used to check the grit removal effect of the determined grit chamber size. The sedimentation rate of sediment with a particle size of 0.05 mm in the grit chamber is 99.4%, the sedimentation rate of total sediment is 99.8%, and the sediment concentration at the outlet of the pond is 0.0081 kg / m 3 , meeting the requirements of the drip irrigation equipment for sediment particle size.

[0205] Conclusion

[0206] 1. Through calculation, analysis, comparison and verification by two methods, when the design flow rate of the grit chamber is 0.22 m 3 / s, the size of the grit chamber is: length × width × height = 120 × 12 × 2.5 m; when the design flow rate of the grit chamber is 0.12 m 3When the flow rate is [X] m³ / s, the size of the grit chamber is: length × width × height = 70 × 9 × 2.5 m.

[0207] 2. When the water flow velocity in the grit chamber is controlled at 36 m / h, it has a better grit removal effect.

[0208] 3. The comb-tooth structure of the present invention increases the inlet width from about 50 cm in the conventional case to about 9.5 m, reduces the water depth from 26 cm to 6 cm, reduces the flow velocity to about 0.33 m / s. The inlet flow velocity and the grit removal flow velocity are perfectly combined, and the sediment in the water settles and accumulates in a parabolic shape, realizing the sedimentation of sediment in the first 2 / 3 section of the grit chamber. The clear water enters the drip irrigation system through the last 1 / 3 section of the grit chamber, achieving an effective grit removal effect.

[0209] Example 2

[0210] Referring to the appendix Figure 2-3 , in order to clean the floating objects in the water flow, concave grooves 7 are provided on both sides of the overflow slot 4, and a primary filter grille 8 is inserted into the concave grooves 7. Through the primary filter grille 8, aquatic plants, organic matter or other suspended impurities in the water flow can be filtered to avoid blocking the outlet pipe of the clear water tank 5.

[0211] Example 3

[0212] Referring to the appendix Figure 4 , since the primary filter grille 8 can only clean large-sized organic matter and impurities, and if the primary filter grille 8 is set too dense, it will not only easily cause blockage of the overflow slot 4 but also affect the sedimentation of sediment. Therefore, in order to further clean the floating objects on the river surface, a secondary cleaning mechanism is also included in this embodiment.

[0213] Specifically, the secondary cleaning mechanism is arranged above the clear water tank 5. The secondary cleaning mechanism includes a diversion low wall 10, a support 11, an inclined diversion mechanism 12 and a V-shaped floating object collecting trough 13. The height difference between the top of the diversion low wall 10 and the overflow slot 4 is 10 cm. A water passing trough is arranged below the diversion low wall 10, and the height of the water passing trough is one-third of the depth of the tank body. A sand retaining dam 9 is also arranged in the water passing trough. The height of the rear slope inclined surface of the tank body 2 is one-fourth of the depth of the tank body, and the sand retaining dam 9 is arranged at the top of the rear slope.

[0214] The bracket 11 is installed in the clean water tank 5. The inclined diversion mechanism 12 and the V-shaped floating debris trough 13 are both arranged on the bracket 11. The inclined diversion mechanism 12 is arranged on the back of the diversion low wall 10. In this embodiment, the inclined diversion mechanism 12 is a diversion plate placed obliquely. Baffles are arranged on both sides of the diversion plate. The V-shaped floating debris trough 13 is arranged below the end of the inclined diversion mechanism 12. Plug holes are arranged on both side edges of the V-shaped floating debris trough 13, and a detachable fine grid 14 is inserted into the plug holes. In the present invention, a handle is arranged on the surface of the detachable fine grid 14, and it can be taken out by pulling it outwards.

[0215] The inclined diversion mechanism 12 and the V-shaped floating debris trough 13 of the present invention can basically cover the upper part of the clean water tank, preventing impurities blown by the wind from falling into the clean water tank. When the water flow passes through the diversion low wall 10, the bottom clean water flows from the water passing trough to the clean water tank 5, and the floating objects pass over the diversion low wall 10 along with the surface water. When flowing through the diversion plate, under the push of the water flow, the floating objects are pushed by the diversion plate to the V-shaped floating debris trough 13 and are intercepted on the detachable fine grid 14 on the surface of the V-shaped floating debris trough 13. The water flow flows into the clean water tank 5 along the V-shaped floating debris trough 13. The detachable fine grid 14 facilitates the drying and cleaning of the floating objects.

[0216] Embodiment 4

[0217] The difference between this embodiment and Embodiment 3 is that in this embodiment, the inclined diversion mechanism 12 is an inclined conveyor belt. Through the arrangement of the conveyor belt, the floating impurities are actively conveyed into the V-shaped floating debris trough 13, further improving the collection speed of the floating objects.

[0218] Embodiment 5

[0219] Refer to the attached Figure 5 , when the water flow velocity is too slow, in order to prevent sediment and floating objects from the river water from accumulating in the water inlet trough 3, and the water level in the pool body 2 cannot reach the upper surface of the diversion low wall 10 so that diversion cannot be carried out (for example, only half of the water flow in the pool body), in this embodiment, the primary filter grille 8 is no longer provided, but a trash rack 16 is vertically established between the diversion low wall 10 and the sand retaining dam 9 in Embodiment 3, which plays a role in preventing larger impurities in the water from entering the clean water tank.

[0220] The above is only a preferred embodiment of the present invention, and does not impose any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still belong to the scope of the technical solution of the present invention.

Claims

1. An efficient grit chamber structure with sand retention in front and water flow behind, characterized in that: It includes an inlet channel and a pool body, wherein the front short side slope of the pool body is provided with an inlet trough, the side of the inlet trough close to the pool body is provided with a comb-tooth water inlet, the rear short side slope of the pool body is provided with a clear water tank, a dredging channel is provided in the middle of one side of the long slope of the pool body, the inlet channel is connected with the inlet trough, and a water diversion gate is provided at the front end of the inlet channel.

2. The high-efficiency grit chamber structure with sand retention before and water flow after according to claim 1 is characterized in that: The comb-tooth type water inlet comprises a plurality of overflow slots arranged at equal intervals, and the bottom ends of the overflow slots are just located at the top of the short side slope in front of the pool body.

3. The high-efficiency grit chamber structure with sand retention before and water flow after according to claim 2 is characterized in that: Concave grooves are arranged on both sides of the overflow notch, and primary filtering grilles are inserted into the concave grooves.

4. The high-efficiency grit chamber structure with sand retention before and water flow after according to claim 1 is characterized in that: It also includes a secondary cleaning mechanism, which is arranged above the clean water tank.

5. The high-efficiency grit chamber structure with sand retention before and water flow after according to claim 4 is characterized in that: The secondary sewage cleaning mechanism includes a diversion low wall, a bracket, an inclined flow guiding mechanism and a V-shaped drift collecting trough. The diversion low wall is arranged at the connection between the clean water tank and the tank body. The height difference between the top of the diversion low wall and the overflow slot is 10 cm. A water trough is arranged below the diversion low wall. The height of the water trough is one-third of the depth of the tank body. The bracket is installed in the clean water tank. The inclined flow guiding mechanism and the V-shaped drift collecting trough are both arranged on the bracket. The inclined flow guiding mechanism is arranged on the back of the diversion low wall. The V-shaped drift collecting trough is arranged below the end of the inclined flow guiding mechanism.

6. The high-efficiency grit chamber structure with sand retention before and water flow after according to claim 5 is characterized in that: It also includes a sand retaining embankment located in the water channel, the height of the inclined surface of the rear slope of the pool body is one quarter of the depth of the pool body, and the sand retaining embankment is arranged on the top of the rear slope.

7. The high-efficiency grit chamber structure with sand retention before and water flow after according to claim 5 is characterized in that: The inclined flow guide mechanism is an inclined flow guide plate, and baffles are arranged on both sides of the flow guide plate.

8. The high-efficiency grit chamber structure with sand retention before and water flow after according to claim 5 is characterized in that: The inclined flow guiding mechanism is an inclined conveyor belt.

9. The high-efficiency grit chamber structure with sand retention before and water flow after according to claim 5 is characterized in that: A detachable fine grid is installed in the V-shaped drift collecting trough.

10. The high-efficiency grit chamber structure with sand retention before and water flow after according to claim 6 is characterized in that: A trash rack is arranged between the sand retaining bank and the diversion low wall.

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