A method for modeling and optimization of double-cone sedimentation tank for kitchen wastewater treatment

Abstract

The application discloses a kind of modeling and optimization method for kitchen wastewater treatment of double-cone sedimentation tank, the sedimentation tank includes rectangular pool body, two big lower small frustum pool bottom are arranged at the bottom of the rectangular pool body left and right interval, the middle part of the rectangular pool body is inclinedly provided with several baffles, and the upper end of each baffle is coincident with the lower end of adjacent baffle, the lower end of each baffle is coincident with the upper end of adjacent baffle on the same vertical plane, the position of the rectangular pool body is close to the bottom and is provided with water inlet, and the top of the rectangular pool body is outlet;It also includes the following steps: S1 global definition;S2 build model;S3 fluid setting;S4 carry out the simulation of fluid;S5 comparison simulation.By computer software, the sedimentation tank is simulated, the structure of the sedimentation tank is adjusted, the sedimentation efficiency of the optimized sedimentation tank and the utilization rate of the sedimentation tank are realized;Using double-cone sedimentation tank can effectively prevent sludge from overflowing or sludge from reducing drug utilization rate.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wastewater treatment, and particularly relates to a modeling and optimization method of a double-cone sedimentation tank for kitchen wastewater treatment. BACKGROUND

[0002] In a conventional kitchen wastewater treatment process, coagulation, sedimentation and filtration are key steps, wherein the sedimentation tank is a structure used in sedimentation, and the quality of the sedimentation process directly relates to the quality of the entire water treatment process, which is specifically manifested as that the turbidity of effluent after sedimentation greatly influences the subsequent filtration process. In order to increase the sedimentation effect, structures are added in the sedimentation tank, but the accurate positions of the structures cannot be determined, for example, if the optimal position is to be found, multiple actual simulations need to be performed, and then the optimal structure scheme is obtained by comparison, which not only consumes a long time, but also has a high cost. SUMMARY

[0003] The application provides a modeling and optimization method of a double-cone sedimentation tank for kitchen wastewater treatment, which simulates the sedimentation tank by using a computer software, adjusts the structure of the sedimentation tank, and achieves the purposes of optimizing the sedimentation efficiency of the sedimentation tank and the utilization rate of the sedimentation tank, and simultaneously speeds up and reduces the cost.

[0004] Therefore, the application adopts the following technical scheme: a modeling and optimization method of a double-cone sedimentation tank for kitchen wastewater treatment, wherein the sedimentation tank comprises a rectangular tank body, two upper-large-and-lower-small frustum tank bottoms are arranged at the bottom of the rectangular tank body in a left-right interval, a plurality of baffles are arranged at the middle part of the rectangular tank body in an inclined manner, the upper end of each baffle and the lower end of the adjacent baffle, and the lower end of each baffle and the upper end of the adjacent baffle are coincident on the same vertical plane, a water inlet is arranged at the position close to the bottom of the rectangular tank body, and the top of the rectangular tank body is an outlet.

[0005] Further comprising the following steps: S1 global definition; selecting a turbulent flow and fluid flow particle tracking physical field in the COMSOL MultiPhysics software, selecting parameters, inputting the parameters, and performing global definition; S2 model building; selecting modeling in the COMSOL MultiPhysics software, building a model of the sedimentation tank, and setting the position of the water inlet; S3 fluid setting: first adding fluid water as a physical material in the entire sedimentation tank, then selecting the turbulent flow and fluid flow particle tracking physical field to the entire sedimentation tank, and then setting the water inlet velocity, particle tracking velocity and the number of released particles; S4 fluid simulation; first adding a multi-physical field coupling, then automatically performing mesh division, and then performing solving to obtain a simulation result; S5 simulation comparison; changing any one of the structure of the sedimentation tank or the water inlet velocity, repeating the simulation, and obtaining a conclusion according to the simulation result.

[0006] As a preferred solution of the above, in S2, the model built is a two-dimensional model.

[0007] Further preferably, in S1, the parameters include particle diameter, particle density, buoyancy, water density, gravity.

[0008] Further preferably, in S4, a study needs to be added before solving, and the study includes steady-state and transient-state studies.

[0009] Further preferably, the integrated wastewater treatment device comprises a housing with an open top surface, a support assembly arranged below the housing, and a degassing tank, a coagulation tank, and a sedimentation tank arranged in sequence from left to right in the housing and through which wastewater passes in sequence, and the wastewater can be discharged after passing through the degassing tank, the coagulation tank, and the sedimentation tank in sequence.

[0010] Further preferably, the sedimentation tank comprises a separation tank arranged in the middle, the baffle is arranged in the separation tank, water distribution tanks are arranged at both ends of the separation tank, the water distribution tanks are located on the two inclined surfaces of the conical platform, and a second pipeline is arranged in the water distribution tank close to the lower end and communicates with the separation tank; a water collecting tank is arranged on one side of the upper end of each water distribution tank close to the separation tank, the top surface of the partition plate between the water collecting tank and the water distribution tank is not lower than the top surface of the housing, the top surface of the partition plate between the water collecting tank and the separation tank is lower than the top surface of the partition plate between the separation tank and the other adjacent tanks, and the bottom surface of the water collecting tank is lower than the top surface of the partition plate between the water collecting tank and the separation tank.

[0011] Further preferably, the coagulation zone is divided into a rapid coagulation tank and a slow flocculation tank arranged in sequence by a partition plate, a first flow guide tank is arranged on the side of the slow flocculation tank away from the rapid coagulation tank, a first through hole is arranged at the lower end of the first flow guide tank and the lower end of the degassing tank, a first pipeline is arranged in the first flow guide tank close to the lower end and communicates with the rapid coagulation tank, and the top surface of the partition plate between the slow flocculation tank and the rapid coagulation tank is lower than the top surface of the partition plate between the rapid coagulation tank and the other adjacent tanks.

[0012] Further preferably, stirring assemblies for accelerating dissolution are arranged in the rapid coagulation tank and the slow flocculation tank, an air pump for inflating air is arranged at the bottom of the degassing tank, and an adding assembly for automatically adding alkali, coagulant, or flocculant is arranged on the degassing tank, the rapid coagulation tank, and the slow flocculation tank.

[0013] In a further preferred embodiment, a second diversion tank is provided between the sedimentation tank and the coagulation tank. The second diversion tank has a second through hole near its lower end that communicates with the slow flocculation tank, and a third through hole near its lower end that communicates with the sedimentation tank.

[0014] The beneficial effects of this invention are as follows: Optimization of the sedimentation tank is achieved through computer software simulation, which is more convenient and faster than physical experiments, while also being less costly. In this application, the software simulation not only has a high degree of fit with the actual situation of the sedimentation tank but also allows for intuitive results from the simulation. The sedimentation tank is designed as a double cone with baffles inside, causing the fluid flowing into the sedimentation tank to form a backflow in the middle section. This facilitates the subsequent entry of precipitate into the baffle area, thereby improving the utilization rate of the baffles. Furthermore, the double cone sedimentation tank is more conducive to sludge discharge than the single cone sedimentation tank, effectively preventing sludge rise and overflow or sludge backflow that reduces the utilization rate of pharmaceuticals. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the process of the present invention.

[0016] Figure 2 The interface after modeling is selected in this invention.

[0017] Figure 3 This is the interface for selecting the model wizard in this invention.

[0018] Figure 4 This is the interface selected after two dimensions in this invention.

[0019] Figure 5 This is the interface for selecting research topics within the software.

[0020] Figure 6 This is a schematic diagram of the parameters input in an embodiment of the present invention.

[0021] Figure 7 This is the main model of the sedimentation tank built in the software.

[0022] Figure 8 This is a sedimentation tank model built in the software.

[0023] Figure 9 This is a sedimentation tank model after adding liquid water as the physical material in the software.

[0024] Figure 10 This is a sedimentation tank model after the particle release quantity is determined in the software.

[0025] Figure 11 This is a sedimentation tank model after mesh generation in the software.

[0026] Figures 12-18The simulation result diagram when the baffle bottom is 1.9m away from the rectangular body bottom, the angle between the baffle and the vertical direction is 30°, and the inlet bottom is 1.5m, 1.6m, 1.7m, 1.55m, 1.65m away from the rectangular body in sequence for the double-cone sedimentation tank with an inlet flow rate of 0.02m / s.

[0027] Figures 19-23 The simulation result diagram when the baffle bottom is 1.9m away from the rectangular body bottom, the angle between the baffle and the vertical direction is 30°, and the inlet bottom is 1.5m, 1.6m, 1.7m, 1.55m, 1.65m away from the rectangular body in sequence for the double-cone sedimentation tank with an inlet flow rate of 0.02m / s.

[0028] Figures 24-28 The simulation result diagram when the baffle bottom is 1.8m away from the rectangular body bottom, the angle between the baffle and the vertical direction is 30°, and the inlet bottom is 1.4m, 1.5m, 1.6m, 1.45m, 1.55m away from the rectangular body in sequence for the double-cone sedimentation tank with an inlet flow rate of 0.02m / s.

[0029] Figures 29-34 The simulation result diagram when the baffle bottom is 1.9m away from the rectangular body bottom, the angle between the baffle and the vertical direction is 30°, and the inlet bottom is 1.5m, 1.6m, 1.7m, 1.55m, 1.65m away from the rectangular body in sequence for the double-cone sedimentation tank with an inlet flow rate of 0.02m / s.

[0030] Figures 35-40 The simulation result diagram when the baffle bottom is 1.9m away from the rectangular body bottom, the angle between the baffle and the vertical direction is 30°, and the inlet bottom is 1.5m, 1.6m, 1.7m, 1.55m, 1.65m away from the rectangular body in sequence for the double-cone sedimentation tank with an inlet flow rate of 0.02m / s.

[0031] Figures 41-44 The simulation result diagram when the baffle bottom is 1.9m away from the rectangular body bottom, the angle between the baffle and the vertical direction is 30°, and the inlet bottom is 1.5m, 1.6m, 1.7m, 1.55m, 1.65m away from the rectangular body in sequence for the double-cone sedimentation tank with an inlet flow rate of 0.02m / s.

[0032] Figure 45 The simulation result diagram when the baffle bottom is 1.9m away from the rectangular body bottom, the angle between the baffle and the vertical direction is 30°, and the inlet bottom is 1.5m, 1.6m, 1.7m, 1.55m, 1.65m away from the rectangular body in sequence for the double-cone sedimentation tank with an inlet flow rate of 0.02m / s.

[0033] Figure 46 The simulation result diagram when the baffle bottom is 1.9m away from the rectangular body bottom, the angle between the baffle and the vertical direction is 30°, and the inlet bottom is 1.5m, 1.6m, 1.7m, 1.55m, 1.65m away from the rectangular body in sequence for the double-cone sedimentation tank with an inlet flow rate of 0.02m / s. Figure 45 The simulation result diagram when the baffle bottom is 1.9m away from the rectangular body bottom, the angle between the baffle and the vertical direction is 30°, and the inlet bottom is 1.5m, 1.6m, 1.7m, 1.55m, 1.65m away from the rectangular body in sequence for the double-cone sedimentation tank with an inlet flow rate of 0.02m / s.

[0034] Figure 47 The simulation result diagram when the baffle bottom is 1.9m away from the rectangular body bottom, the angle between the baffle and the vertical direction is 30°, and the inlet bottom is 1.5m, 1.6m, 1.7m, 1.55m, 1.65m away from the rectangular body in sequence for the double-cone sedimentation tank with an inlet flow rate of 0.02m / s. Figure 45 The simulation result diagram when the baffle bottom is 1.9m away from the rectangular body bottom, the angle between the baffle and the vertical direction is 30°, and the inlet bottom is 1.5m, 1.6m, 1.7m, 1.55m, 1.65m away from the rectangular body in sequence for the double-cone sedimentation tank with an inlet flow rate of 0.02m / s. DETAILED DESCRIPTION

[0035] The application will be further described below by way of examples and with reference to the drawings:

[0036] As Figure 1 shown, a modeling and optimization method for a double-cone sedimentation tank for kitchen wastewater treatment mainly comprises the following steps:

[0037] Step 1: Global definition. In the COMSOL MultiPhysics software, select the turbulent flow and fluid flow particle tracking physical field, then select the parameters and input the parameters for global definition. The parameters include particle diameter, particle density, buoyancy, water density, gravity, etc., and the above parameters are obtained according to actual investigation.

[0038] Step 2: Build a model. After selecting modeling in the COMSOL MultiPhysics software, build the model of the sedimentation tank and set the water inlet position. When building, in order to get accurate results, a three-dimensional model can be built first, because a two-dimensional model can also be built according to computer configuration and other factors to reduce the amount of calculation.

[0039] The structure of the built sedimentation tank is as follows. The sedimentation tank comprises a rectangular tank body, two large-small taper tank bottoms are arranged at the bottom of the rectangular tank body in an interval manner, a plurality of baffles are arranged in the middle of the rectangular tank body in an inclined manner, the upper end of each baffle and the lower end of the adjacent baffle, and the lower end of each baffle and the upper end of the adjacent baffle are coincided on the same vertical plane, a water inlet is arranged at a position close to the bottom of the rectangular tank body, i.e. the water inlet is below the baffle, and the top of the rectangular tank body is an outlet.

[0040] Step 3: Fluid setting. First, add fluid water as a physical material in the entire sedimentation tank, then select the turbulent flow and fluid flow particle tracking physical field to the entire sedimentation tank, and then set the water inlet velocity, particle tracking velocity and the number of released particles.

[0041] Step 4: Perform fluid simulation. First, add multi-physics coupling and then automatically perform mesh division, and then solve to obtain the simulation results. Before solving in step 4, a study needs to be added, which includes steady-state and transient-state studies, and the study settings can be selected after selecting the physical field in step 1 or before solving in step 4.

[0042] Step 5: Compare simulation. After changing any of the structure of the sedimentation tank or the water inlet velocity, repeat the simulation, and draw conclusions according to the simulation results. The structure of the sedimentation tank that can be changed includes the position of the water inlet (the position includes the distance between the water inlet and the bottom and the width of the water inlet, of course, the width of the water inlet does not exist in the two-dimensional model), the height of the baffle and the angle of the baffle.

[0043] The sedimentation tank modeled and optimized in the present application is arranged in an integrated wastewater treatment device, as shown in Figures 45-47 The integrated wastewater treatment device mainly consists of a shell 1 with an unsealed top surface and a support assembly for supporting the shell 1, wherein the support assembly is a prior art, which can be in the form of a column and a foot pad, or a column and a universal wheel with a locking structure, or a single column structure. The shell 1 is divided into a deaeration tank 3, a coagulation tank 4 and a sedimentation tank 5 arranged in sequence from left to right by a partition plate, and the wastewater sequentially passes through the deaeration tank 3, the coagulation tank 4 and the sedimentation tank 5, and is discharged after passing through the deaeration tank 3, the coagulation tank 4 and the sedimentation tank 5.

[0044] To improve the treatment efficiency and the sedimentation rate, the coagulation zone 4 is divided into a fast coagulation tank 4a and a slow flocculation tank 4b arranged in sequence by a partition plate 2, and a first flow guide tank 4c is arranged on the side of the slow flocculation tank 4b away from the fast coagulation tank 4a. To realize the flow of wastewater, a first through hole is arranged at the lower end of the first flow guide tank 4c and the lower end of the deaeration tank 3, and a first pipeline in communication with the fast coagulation tank 4a is arranged at a position close to the lower end of the first flow guide tank 4c, so that the liquid in the first flow guide tank can smoothly enter the fast coagulation tank. The top surface of the partition plate between the slow flocculation tank 4b and the fast coagulation tank 4a is lower than the top surface of the partition plate between the fast coagulation tank 4a and the adjacent tanks, so that the liquid in the fast coagulation tank can enter the slow flocculation tank from above.

[0045] The sedimentation tank 5 includes a separation tank 5a arranged in the middle, and water distribution tanks 5c arranged at both ends of the separation tank 5a, wherein the water distribution tanks 5c are located on the two inclined surfaces of the conical platform, and a second pipeline in communication with the separation tank 5a is arranged at a position close to the lower end of the water distribution tank 5c. The water distribution tanks are arranged on both sides of the separation tank, so that the water can enter through the uniform water inlet at both ends, so that the overall high-speed water flow is closest to the bottom of the baffle, thereby more uniformly entering the flow area of each sedimentation baffle, improving the utilization rate of the sedimentation baffle, changing the rising flow rate, accelerating the settling speed of suspended substances, and achieving the purpose of increasing the SS removal rate.

[0046] A second flow guide tank 10 is arranged between the sedimentation tank 5 and the coagulation tank 4, and a second through hole in communication with the slow flocculation tank is arranged at a position close to the lower end of the second flow guide tank 10, and a third through hole for communication with the sedimentation tank is arranged at a position close to the lower end of the second flow guide tank 10, and the third through hole is arranged on the left side wall of the water distribution tank. A flow guide tank is arranged in front of the sedimentation tank and in front of the beginning coagulation zone, which can directly sediment large particles and prevent sludge backflow, and the second flow guide tank facilitates effective water distribution at both ends.

[0047] The sedimentation tank 5 comprises a separation tank 5a arranged in the middle, a baffle 9 arranged in the separation tank, a water collecting tank 5b arranged at the front and back ends of the separation tank 5a, a water distribution tank 5c arranged at the front and back outer sides of each water collecting tank 5b, and the height of the partition plate between the separation tank 5a and the water collecting tank is lower than the height of the partition plate between the separation tank and the adjacent tank, so that the liquid above the separation tank flows into the water collecting tank through the partition plate. The second pipeline is arranged in the water distribution tank 5c near the lower end and communicates with the separation tank 5a, and the third through hole is arranged at the left side of the two water distribution tanks, so that the liquid in the second flow guide tank can enter the separation tank. The baffle is arranged in the separation tank, and the double cone is arranged at the lower end of the separation tank, which not only facilitates the discharge of sludge and effectively prevents the overflow of sludge sedimentation and backflow of sludge, but also reduces the utilization rate of drugs, and also makes the fluid produce backflow in the middle section, so that the subsequent entering of the sedimentation liquid is more easily entered into the baffle area, thereby improving the utilization rate of the baffle.

[0048] In order to facilitate the collection of the liquid without sediment after sedimentation, the upper end of each water distribution tank 5c is arranged on one side close to the separation tank, and the top surface of the partition plate between the water collecting tank 5b and the water distribution tank 5c is not lower than the top surface of the shell, and the top surface of the partition plate between the water collecting tank 5b and the separation tank 5a is lower than the top surface of the partition plate between the separation tank and the adjacent tank, and the bottom surface of the water collecting tank 5b is lower than the top surface of the partition plate between the water collecting tank 5b and the separation tank 5a. At the same time, the water outlet tank 6 is arranged at the upper end of the right side of the sedimentation tank 5, the water outlet tank 6 and the sedimentation tank 5 are separated by a partition plate, and the top surface of the partition plate between the water collecting tank 5b and the water outlet tank 6 is lower than the top surface of the partition plate between the water collecting tank 5b and the adjacent tank, and the bottom of the water outlet tank 6 is lower than the top surface of the water collecting tank 5b. By arranging the water collecting tank and the water outlet tank, two sedimentation tanks are equivalent, which can further improve the water quality. In order to prevent larger particles from entering the water collecting tank, the upper end of the partition plate between the separation tank 5a and the water collecting tank 5b is arranged in a zigzag shape, thereby further improving the water quality.

[0049] In order to realize the wastewater entering and the discharge of the treated water of the treatment equipment, the water inlet pipe 7 for the wastewater entering is arranged at the upper end of the left side of the degassing tank 3, and the water outlet pipe 8 for the flow of the purified water is arranged at the upper end of the right side of the water outlet tank 6. In order to facilitate the cleaning of the equipment, the deslagging port 11 is arranged at the lower end of the double cone of the sedimentation tank 5, and the emptying port 12 is arranged at the bottom of the coagulation tank 4 and the degassing tank 3.

[0050] Generally, the wastewater is stored in a tank in advance, and hydrogen peroxide is added during storage for Fenton treatment, so a separate degassing tank is arranged, and a gas pump is arranged at the bottom of the degassing tank, which is used to charge air into the wastewater to remove residual hydrogen peroxide, so that it can solve the influence of hydrogen peroxide on the subsequent addition of coagulant and high molecular flocculant.

[0051] In order to accelerate the dissolution of coagulant and flocculant, stirring assemblies are arranged on the coagulation tank and the degassing tank, and the stirring assembly is a prior art, which can adopt the structure of motor and stirring shaft. The degassing tank 3, the rapid coagulation tank 4a and the slow flocculation tank 4b are equipped with adding assemblies for automatically adding alkali liquor, coagulant or flocculant. When the added substance is liquid, the adding assembly can adopt the form of metering pump. When the added substance is solid, since it needs to be continuously added, a screw conveyor is adopted to realize the adding, and a control system for controlling the work of the stirring assembly and the adding assembly is also equipped.

[0052] Preferably, the first through hole, the second through hole, the third through hole, the first pipeline and the second pipeline are all arranged to be inclined along the water flow direction and arranged at the lower middle position of the corresponding tank, and the first through hole is higher than the first pipeline, and the second through hole, the third through hole and the second pipeline are arranged to be gradually lowered in height, so as to facilitate the reaction and the preliminary sedimentation and filtration.

[0053] After the wastewater is treated by Fenton, it enters the raw water tank, and then enters the degassing tank through the water pump from the water inlet. The pH value is adjusted by continuously adding alkali liquor in the dehydration tank, and the residual hydrogen peroxide is removed by continuously flushing air through the air pump. Then, the wastewater reaches the first flow guide tank through the first through hole, and then reaches the rapid coagulation tank through the first pipeline. The coagulant is added in the rapid coagulation tank, and the rapid stirring of the stirring assembly can make the coagulant quickly contact and react with the water-soluble pollutants to form small insoluble substances. When the liquid level in the rapid coagulation tank is higher than the height of the partition plate between the rapid coagulation tank and the slow flocculation tank, the liquid enters the slow flocculation tank. By continuously adding flocculant and slow stirring of the stirring assembly in the slow flocculation tank, the flocculant can improve the structure of the flocculation body by using its strong adsorption bridging effect, so that the small and loose fine particles become large and tight alum flowers. Then, the wastewater enters the second flow guide tank through the second through hole, and enters the two water distribution tanks through the third through hole respectively, and then enters the separation tank through the second pipeline. When the liquid level in the separation tank is higher than the height of the separation tank and the water collection tank, the wastewater can flow uniformly into the two water collection tanks. When it reaches a certain height in the water collection tank, it enters the effluent tank, and finally the treated liquid is discharged through the water outlet of the effluent tank. After a period of treatment, the machine needs to be stopped, and the sludge is cleaned through the emptying port and the sewage port.

[0054] Embodiment

[0055] The modeling and optimization method of the double-cone sedimentation tank for kitchen wastewater treatment comprises the following steps:

[0056] 1. Open the COMSOL MultiPhysics software, then click New Model as shown in the interface Figure 2 , click Model Wizard as shown in the interface Figure 3 , and then click Two-dimensional as shown in the interface Figure 4Click the physical field, then select the turbulent flow and particle tracking physical field, click research, and then click the parameters as shown in the interface Figure 5 shown in the interface, select transient, then click parameters, and then output the parameters obtained according to the actual research, input parameters as shown in the interface Figure 6

[0057] 2, click geometry to start modeling, first build the main body of the sedimentation tank, that is, first build a rectangular main body and then build a conical bottom, after construction, as shown in the interface Figure 7 shown; then build the baffle, when building, first build a baffle and then copy multiple baffles using the array method, and then use the difference set to remove the baffle position from the pool to achieve the effect of the baffle, after construction, as shown in the interface Figure 8 shown; finally, add points with a height difference of 20 cm on the right side as the water inlet.

[0058] The data of the sedimentation tank built in this embodiment are as follows: the rectangular main body data is 3.2 m long and 3.12 m high, the lower conical sedimentation tank is 1 m high, the bottom edge is 0.8 m long, the baffle in the pool is 1 m long, the thickness is 0.13 m, the distance from the bottom of the rectangular sedimentation tank is 2 m, and the angle with the vertical direction is 30°, the water inlet of the sedimentation tank is arranged at a position with a height of 1.7 m from the bottom of the separation tank on the right side, the inlet length is 0.2 m, and the outlet is the top edge of the rectangular main body.

[0059] 3, add liquid water as a physical material and select the entire sedimentation tank, as shown in the interface Figure 9 shown; select the turbulent flow and particle tracking physical field to the entire sedimentation tank, and then add the water inlet to select the interval between the two points on the right side as the water inlet and set the initial velocity, and the particle tracking is the same, only need to add the number of released particles, as shown in the interface Figure 10

[0060] 4, first add multi-physical coupling, then automatically perform mesh division, the division result is shown in the interface Figure 11 shown, the mesh division is to determine the division calculation area. Then add research 2: steady state, realize the result and dynamic simulation east, and need to select the step in transient. Finally, solve to get the simulation result, the simulation result includes velocity division and particle trajectory, since the particle trajectory is an animation, for the convenience of subsequent comparison, the result of the particle trajectory is kept, and the velocity division graph is also saved.

[0061] 5, change any one of the water inlet height, baffle height, baffle angle and water inlet velocity, repeat the solution, get the simulation result as shown in the interface Figures 12-40 shown, wherein the left graph is a velocity distribution graph, and the right graph is a particle trajectory graph, and the analysis in the entire simulation process is as follows:

[0062] Figures 12-18 ​​The image shows the simulation results of a double-cone sedimentation tank with an inlet flow velocity of 0.02 m / s, a baffle bottom distance of 2 m from the bottom of the rectangular main body, and the baffle at a 30° angle to the vertical direction. The inlet height was adjusted in 0.1 m increments starting from 1.5 m from the bottom of the rectangular main body. Specifically... Figure 12 The simulation results are at an inlet height of 1.5m. In this state, 11 out of 28 baffles are effective, accounting for 39%. Figure 13 The simulation results are at an inlet height of 1.6m. In this state, 14 out of the 28 baffles are effective, accounting for 50%. Figure 14 The simulation results are at an inlet height of 1.7m. In this state, 19 out of 28 baffles are effective, accounting for 68%. Figure 15 The simulation results are at an inlet height of 1.8m. In this state, 16 out of the 28 baffles are effective, accounting for 57%. Figure 16 The simulation results are at an inlet height of 1.9m. In this state, 9 out of the 28 baffles are effective, accounting for 25%.

[0063] The peak values ​​have been obtained using the above data, and the image also indicates that the optimal values ​​exist between 1.6m and 1.8m. Therefore, two additional sets of refinement parameters are added for comparison. Figure 17 and 18 As shown, where Figure 17 The simulation results are shown at an inlet height of 1.65m. In this state, 17 out of the 28 baffles are effective, accounting for 60%. Figure 18 The simulation results are based on an inlet height of 1.75m. Under this condition, 20 out of the 28 baffles are effective, accounting for 71%. Therefore, for a double-cone sedimentation tank, based on the indicator of maximum baffle utilization, the optimal inlet position is 1.75m away from the bottom of the rectangular sedimentation tank.

[0064] Meanwhile, under the same control of other conditions, it can be found that the baffle utilization rate of the double-cone sedimentation tank is slightly higher than that of the single-cone sedimentation tank. The reason for this can be found in the flow velocity diagrams of the various single-cone and double-cone sedimentation tanks. The main reason is that the conical sedimentation tank following the double-cone sedimentation tank causes fluid backflow in the middle section, which makes it easier for the subsequently entering sediment to enter the baffle area in the middle section, thus improving the baffle utilization rate.

[0065] When the height of the bottom of the baffle in the double-cone sedimentation tank from the bottom of the rectangular main body is adjusted to 1.9m, the inlet flow velocity is maintained at 0.02m / s, and the baffle is maintained at a 30-degree angle to the vertical direction. With the baffles at the same height, the inlet height is adjusted at intervals of 0.1m to obtain the following result: Figures 19-23 The results are shown below. Specifically: Figure 19 The simulation results are shown at the bottom of the inlet 1.5m away from the bottom of the rectangular main body. In this state, 15 of the 28 baffles are effective, accounting for 54%.Figure 20 The simulation result of the inlet bottom being 1.6m from the bottom of the rectangular body, in which 20 of the 28 baffles are effective, accounting for 71%; Figure 21 The simulation result of the inlet bottom being 1.7m from the bottom of the rectangular body, in which 16 of the 28 baffles are effective, accounting for 57%.

[0066] Therefore, when the height of the baffle bottom from the bottom of the rectangular body is adjusted to 1.9m, the inlet flow rate is 0.02m / s, and the peak utilization of the baffle is between 1.5m and 1.7m, so two additional parameters are simulated, as shown in Figures 22-23 , and specifically: Figure 22 The simulation result of the inlet bottom being 1.55m from the bottom of the rectangular body, in which 14 of the 28 baffles are effective, accounting for 50%; Figure 23 The simulation result of the inlet bottom being 1.65m from the bottom of the rectangular body, in which 19 of the 28 baffles are effective, accounting for 50%. By comparing the above data, when the height of the baffle bottom from the bottom of the rectangular body is adjusted to 1.9m, the inlet flow rate is 0.02m / s, and the best inlet position is at the inlet bottom being 1.6m from the bottom of the rectangular body, i.e. 0.3m below the baffle, which is different from when the baffle height is 2m.

[0067] When the height of the baffle bottom from the bottom of the rectangular body in the double-cone sedimentation tank is adjusted to 1.8m, and the inlet flow rate is 0.02m / s, and the baffle is kept at a 30-degree angle with the vertical direction, the results obtained by adjusting the inlet height at intervals of 0.1m are shown in Figures 24-28 , and specifically: Figure 24 The simulation result of the inlet bottom being 1.4m from the bottom of the rectangular body, in which 16 of the 28 baffles are effective, accounting for 57%; Figure 25 The simulation result of the inlet bottom being 1.5m from the bottom of the rectangular body, in which 19 of the 28 baffles are effective, accounting for 68%; Figure 26 The simulation result of the inlet bottom being 1.6m from the bottom of the rectangular body, in which 16 of the 28 baffles are effective, accounting for 57%.

[0068] Therefore, when the height of the baffle bottom from the bottom of the rectangular body is adjusted to 1.8m, the inlet flow rate is 0.02m / s, and the peak utilization of the baffle is between 1.4m and 1.6m, so two additional parameters are simulated, as shown in Figures 27-28 , and specifically: Figure 27 The simulation result of the inlet bottom being 1.45m from the bottom of the rectangular body, in which 18 of the 28 baffles are effective, accounting for 64%; Figure 28The simulation result of the distance between the bottom of the inlet and the bottom of the rectangular body being 1.55 m is shown in Table 2, in which 18 of the 28 baffles are effective, accounting for 64%. Therefore, when the height of the bottom of the baffle from the bottom of the rectangular body is adjusted to 1.8 m, the flow rate of the inlet is 0.02 m / s, and the optimal position of the inlet is at a distance of 1.5 m from the bottom of the rectangular body, i.e., 0.3 m below the baffle, which is different from the height of 2 m but the same as that of 1.9 m, indicating that the height of the baffle has little effect on the position of the inlet.

[0069] When the flow rate of the inlet is changed to 0.015 m / s, and the height of the bottom of the baffle from the bottom of the rectangular body is kept at 2 m and the angle between the baffle and the vertical direction is kept at 30 degrees, the simulation result of adjusting the height of the inlet at intervals of 0.1 m is shown in Table 3. Figures 29-34 Figure 29 The simulation result of the distance between the bottom of the inlet and the bottom of the rectangular body being 1.5 m is shown in Table 3, in which 12 of the 28 baffles are effective, accounting for 43%. Figure 30 The simulation result of the distance between the bottom of the inlet and the bottom of the rectangular body being 1.6 m is shown in Table 3, in which 12 of the 28 baffles are effective, accounting for 43%. Figure 31 The simulation result of the distance between the bottom of the inlet and the bottom of the rectangular body being 1.7 m is shown in Table 3, in which 18 of the 28 baffles are effective, accounting for 64%. Figure 32 The simulation result of the distance between the bottom of the inlet and the bottom of the rectangular body being 1.8 m is shown in Table 3, in which 16 of the 28 baffles are effective, accounting for 57%.

[0070] Therefore, when the flow rate of the inlet is 0.015 m / s and the height of the bottom of the baffle from the bottom of the rectangular body is 2 m, the utilization peak of the baffle is between 1.6 m and 1.8 m, and thus two sets of parameters are additionally simulated, as shown in Table 4. Figures 33-34 Figure 33 The simulation result of the distance between the bottom of the inlet and the bottom of the rectangular body being 1.65 m is shown in Table 4, in which 12 of the 28 baffles are effective, accounting for 43%. Figure 34 The simulation result of the distance between the bottom of the inlet and the bottom of the rectangular body being 1.75 m is shown in Table 4, in which 20 of the 28 baffles are effective, accounting for 71%. Therefore, when the flow rate of the inlet is 0.015 m / s and the height of the bottom of the baffle from the bottom of the rectangular body is 2 m, the optimal position of the inlet is at a distance of 1.75 m from the bottom of the rectangular body, which is the same as that when the flow rate is 0.02 m / s.

[0071] When the flow rate is further reduced to 0.01 m / s, the simulation result is shown in Table 5. Figures 35-40 Figure 35 The simulation result of the distance between the bottom of the inlet and the bottom of the rectangular body being 1.5 m is shown in Table 5, in which 12 of the 28 baffles are effective, accounting for 43%. Figure 36 ​​​The simulation results are shown at the bottom of the inlet 1.6m from the bottom of the rectangular main body. In this state, 14 out of the 28 baffles are effective, accounting for 50%. Figure 37 The simulation results are shown at the bottom of the inlet 1.7m from the bottom of the rectangular main body. In this state, 18 out of the 28 baffles are effective, accounting for 64%. Figure 38 The simulation results are shown at the bottom of the inlet, which is 1.8m from the bottom of the rectangular main body. In this state, 17 out of the 28 baffles are effective, accounting for 61%.

[0072] Therefore, when the inlet flow velocity is 0.01 m / s and the height of the bottom of the baffle from the bottom of the rectangular main body is 2 m, the peak utilization of the baffle is between 1.6 m and 1.8 m. Therefore, two additional sets of parameters are added for further simulation, as follows... Figures 39-40 As shown, specifically: Figure 39 The simulation results are shown at the bottom of the inlet 1.65m from the bottom of the rectangular main body. In this state, 15 of the 28 baffles are effective, accounting for 54%. Figure 40 The simulation results show the inlet bottom being 1.75m from the bottom of the rectangular main body. In this state, 20 out of the 28 baffles are effective, accounting for 71%. The data shows that when the inlet flow velocity is 0.01m / s and the height of the baffle bottom from the bottom of the rectangular main body is 2m, the optimal inlet position is 1.75m from the bottom of the rectangular main body, the same as when the flow velocity is 0.02m / s and 0.015m / s. Therefore, it can be concluded that for a double-cone sedimentation tank, changes in the conventional flow velocity have almost no effect on the optimal inlet position. It can be basically determined that the optimal inlet position for a double-cone sedimentation tank should be such that the bottom of the inlet is 0.25m below the bottom of the baffle, maximizing baffle utilization.

[0073] Regarding the relationship between sedimentation conditions and baffle angle in a double-cone sedimentation tank, the inlet flow velocity was set to 0.02 m / s, the bottom of the baffle was 2 m from the bottom of the rectangle, and the bottom of the inlet was 1.7 m from the bottom of the rectangle. Coarse adjustments were made starting at a 25° angle between the baffle and the vertical direction, increasing by 10° each time. The results are as follows. Figures 41-44 As shown, where Figure 41 This is a particle trajectory diagram when the baffle angle is 25°. Figure 42 This is a particle trajectory diagram when the baffle angle is 35°. Figure 43 This is a particle trajectory diagram when the baffle angle is 40°. Figure 44 The above figure shows the particle trajectory when the baffle angle is 55°. The results shown in Table 1 can be obtained from the figure above.

[0074] Table 1. Results of the Influence of Baffle Angle on Single-Cone Sedimentation Tank

[0075] Baffle angle Settling rate Baffle utilization 25° 75.6％ 60.7％ 35° 88％ 65.3％ 45° 92％ 88％ 55° 96.4％ 83.3％

[0076] The optimal baffle inclination angle cannot be obtained from Table 1, and actual adjustment analysis is required.

[0077] For the simulated sedimentation tank of the present embodiment, the following results are obtained:

[0078] 1. The optimal inlet position is between 1.25-0.3 m above the bottom of the baffle, which makes the utilization rate of the baffle high, i.e. the utilization rate of the sedimentation tank is high; 2. Adjusting the baffle at a position about 2 m above the bottom of the rectangular main body has little effect on the utilization rate of the baffle; 3. The inlet flow rate between 0.01 m / s and 0.02 m / s has no effect on the optimal inlet position and has little effect on the utilization rate of the baffle; 4. The baffle utilization rate and the sedimentation rate of the double-cone sedimentation tank are higher than those of the single-cone sedimentation tank in most cases, i.e. the double-cone sedimentation tank is superior to the single-cone sedimentation tank.

[0079] When the main body specifications of the sedimentation tank are different from those of the present embodiment, or the inlet flow rate is significantly different from that of the present embodiment, or the parameters are different from those input in the simulation of the present application, the above results may not be applicable, and re-simulation according to the above steps is required.

Claims

1. A method for modeling and optimization of a double cone sedimentation tank for treatment of kitchen wastewater, characterized in that, The precipitation tank comprises a rectangular tank body, two upper-large-and-lower-small frustum tank bottoms are arranged at the bottom of the rectangular tank body in left and right intervals, a plurality of baffles are arranged at the middle part of the rectangular tank body in an inclined manner, the upper end of each baffle coincides with the lower end of the adjacent baffle, and the lower end of each baffle coincides with the upper end of the adjacent baffle on the same vertical plane, a water inlet is arranged at the position close to the bottom of the rectangular tank body, and the top of the rectangular tank body is an outlet, comprising the following steps: S1 global definition; in the COMSOL MultiPhysics software, select the turbulent flow and fluid flow particle tracking physical field, then select the parameters and input the parameters for global definition; S2 build model; in the COMSOL MultiPhysics software, select modeling, build the model of the precipitation tank, and set the position of the water inlet; S3 fluid setting: first, add fluid water as a physical material in the entire precipitation tank, then select the turbulent flow and fluid flow particle tracking physical field to the entire precipitation tank, and then set the water inlet velocity, particle tracking velocity and the number of released particles; S4 simulate the fluid; first, add multi-physical field coupling, then automatically divide the grid, and then solve to obtain the simulation result; S5 compare the simulation; change any one of the structure of the precipitation tank or the water inlet velocity, repeat the simulation, and draw a conclusion according to the simulation result.

2. The method for modeling and optimization of double cone sedimentation tank for treatment of kitchen wastewater as claimed in claim 1 wherein: In S2, the model built is a two-dimensional model.

3. The method for modeling and optimization of double cone sedimentation tank for treatment of kitchen wastewater as claimed in claim 1 wherein: In S1, the parameters include particle diameter, particle density, buoyancy, water density and gravity.

4. The method for modeling and optimization of double cone sedimentation tank for treatment of kitchen wastewater as claimed in claim 1 wherein: Before solving in S4, research needs to be added, and the research includes steady-state and transient research.

5. The method for modeling and optimization of double cone sedimentation tank for treatment of kitchen wastewater as claimed in claim 1 wherein: The precipitation tank is arranged in an integrated wastewater treatment equipment, the integrated wastewater treatment equipment comprises a shell (1) with an unsealed top surface, a supporting assembly is arranged below the shell (1), the shell (1) is divided into a deaeration tank (3), a coagulation tank (4) and a precipitation tank (5) arranged in sequence from left to right and through which wastewater passes in sequence by a partition (2), and the wastewater can be discharged after sequentially passing through the deaeration tank (3), the coagulation tank (4) and the precipitation tank (5).

6. The method for modeling and optimization of double cone sedimentation tank for treatment of kitchen wastewater as claimed in claim 5 wherein: The sedimentation tank (5) comprises a separation tank (5a) arranged in the middle, the baffle (9) is arranged in the separation tank (5a), and water distribution tanks (5c) are arranged at the front and rear ends of the separation tank (5a) and are located on the two inclined surfaces of the conical table, and the second pipeline in communication with the separation tank (5a) is arranged at the position close to the lower end of the water distribution tank (5c); the upper end of each water distribution tank (5c) is close to one side of the separation tank (5a), and the top surface of the partition plate between the water collection tank (5b) and the water distribution tank (5c) is not lower than the top surface of the shell, and the top surface of the partition plate between the water collection tank (5b) and the separation tank (5a) is lower than the top surface of the partition plate between the separation tank and the remaining adjacent tanks, and the bottom surface of the water collection tank (5b) is lower than the top surface of the partition plate between the water collection tank (5b) and the separation tank (5a); the water outlet tank (6) is arranged at the upper end of the right side of the sedimentation tank (5), the water outlet tank (6) and the sedimentation tank (5) are separated by a partition plate, and the top surface of the partition plate between the water collection tank (5b) and the water outlet tank (6) is lower than the top surface of the partition plate between the water collection tank (5b) and the remaining adjacent tanks, and the bottom of the water outlet tank (6) is lower than the top surface of the water collection tank (5b).

7. The method for modeling and optimization of double cone sedimentation tank for treatment of kitchen wastewater as claimed in claim 5 wherein: The coagulation tank (4) is divided into a rapid coagulation tank (4a) and a slow flocculation tank (4b) arranged in front and back by a partition plate (2), the slow flocculation tank (4b) is provided with a first flow guide tank (4c) away from one side of the rapid coagulation tank (4a), the lower end of the first flow guide tank (4c) and the lower end of the degassing tank (3) are provided with a first through hole, and the first pipeline in communication with the rapid coagulation tank (4a) is arranged at the position close to the lower end of the first flow guide tank (4c), and the top surface of the partition plate between the slow flocculation tank (4b) and the rapid coagulation tank (4a) is lower than the top surface of the partition plate between the rapid coagulation tank (4a) and the remaining adjacent tanks.

8. The method for modeling and optimization of double cone sedimentation tank for treatment of kitchen wastewater as claimed in claim 7 wherein: The rapid coagulation tank (4a) and the slow flocculation tank (4b) are both provided with a stirring assembly for accelerating dissolution, the degassing tank (3) is provided with an air pump for filling air, and the degassing tank (3), the rapid coagulation tank (4a) and the slow flocculation tank (4b) are provided with an adding assembly for automatically adding alkali, coagulant or flocculant.

9. The method for modeling and optimization of double cone sedimentation tank for treatment of kitchen wastewater as claimed in claim 7 wherein: The second flow guide tank (10) is arranged between the sedimentation tank (5) and the coagulation tank (4), the second flow guide tank (10) is provided with a second through hole in communication with the slow flocculation tank at the position close to the lower end, and the second flow guide tank (10) is provided with a third through hole for communication with the sedimentation tank at the position close to the lower end.

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