An optimization method for vertical flow folded plate flocculation tank

Abstract

The present invention discloses a method for optimizing a vertical flow folded plate flocculation tank, which belongs to the field of water treatment, including obtaining the flow field distribution at the bend of the folded plate through numerical simulation, selecting a streamline as a baseline in the flow field at the bend of the folded plate at each level of the flocculation tank, determining the water flow velocity at the inlet and determining the G value of each level of the flocculation tank; calculating the angle of the folded plate and the angle of the bending treatment according to the control equation, the standard turbulence model and the motion law of the micro-vortex; optimizing the angle of the folded plate and the bending treatment according to the calculated value in S2; observing the change of the G value when the angle of the folded plate and the bending treatment are differently matched in the numerical simulation experiment, and determining the final optimization of the folded plate and the pool wall. The present invention adopts the above-mentioned method for optimizing a vertical flow folded plate flocculation tank to optimize the flocculation effect of the flocculation tank, and has a good effect.

Description

Technical Field

[0001] The invention relates to the technical field of water treatment, and in particular to an optimization method for a vertical flow folded plate flocculation tank. Background Art

[0002] In the conventional water treatment process, flocculation is an indispensable link and plays a key role in the whole process. Flocculation is to add flocculants (mainly iron salts and aluminum salts) as electrolytes to raw water, and aggregate the impurity particles in the water body to form flocs with good sedimentation performance through particle adsorption bridging and sediment sweeping. The treatment facilities in the flocculation process include two categories: mechanical flocculation reaction facilities and hydraulic flocculation reaction facilities. The latter is generally used in water plants for flocculation treatment, that is, through the reasonable design of the facility structure, the raw water contacts and disturbs the facility during the flow process, and the raw water flow has turbulent kinetic energy under the action of shear force. The water flow itself is used as the flocculation power condition for hydraulic stirring, thereby promoting the flocculation reaction. The flocs formed in the flocculation stage should have a sufficiently large particle size and density to ensure that the flocs can settle quickly in the subsequent sedimentation link to achieve solid-liquid separation. In terms of the actual treatment effect of the water plant, there is a problem of low flocculation efficiency in some areas during the operation of the facility, resulting in a long overall reaction time, which restricts the progress of the entire water treatment. Reasonable optimization of flocculation facilities can not only improve the water quality of water plant effluent, but also reduce energy consumption, reduce chemical consumption, and reduce the cost of facility maintenance. Summary of the invention

[0003] The purpose of the present invention is to provide a method for optimizing a vertical flow folded plate flocculation tank to solve the problems mentioned in the above background technology.

[0004] To achieve the above-mentioned purpose, the present invention provides an optimization method for a vertical flow folded plate flocculation tank, wherein the flocculation tank comprises a flocculation tank body, a water blocking plate, a first partition plate, a second partition plate, a first folded plate, and a second folded plate, wherein the flocculation tank body comprises an inlet, an outlet, a primary flocculation section, a secondary flocculation section, and a tertiary flocculation section, wherein the water blocking plate is arranged on the pool wall of the primary flocculation section and the secondary flocculation section, the first partition plate, and the second partition plate, and the space between the water blocking plates and the pool wall bending parts of the flocculation tank are all subjected to bending treatment;

[0005] The specific steps are as follows:

[0006] S1. Obtain the flow field distribution at the bend of the folded plate through numerical simulation experiments, select a streamline in the flow field at the bend of the folded plate at each level of the flocculation tank as the baseline, determine the water flow velocity at the inlet and determine the G value of each level of the flocculation tank;

[0007] S2, according to the control equation, standard Turbulence model and the movement law of micro-vortices are used to calculate the angle of the folded plate and the angle of curvature treatment;

[0008] S3, optimizing the angles of the folding plate and the bending process according to the calculated values ​​in S2;

[0009] S4. Observe the changes in G value when the angles of the folding plate and the bending treatment are combined at different angles in the numerical simulation experiment, and determine the final optimization of the folding plate and the pool wall.

[0010] Preferably, the G value in S1 is calculated as follows:

[0011] ;

[0012] in, Indicates the specific gravity of water in units of ; h represents the head loss, the unit is ; It represents the dynamic viscosity of water in units of ; T represents the reaction time, the unit is .

[0013] Preferably, the control equations in S2 include the mass conservation equation and the momentum conservation equation:

[0014] ;

[0015] in, , , are the scores of the velocity vector in the x, y, and z directions respectively;

[0016] ;

[0017] ;

[0018] ;

[0019] in, It represents the dynamic viscosity of water; Indicates static pressure in units of ; Indicates density in units of ; , Represents other related quantities related to the equation.

[0020] Preferably, the motion law of the micro-vortex in S2 is as follows:

[0021] ;

[0022] Among them, r is the distance from the calculation point to the center of the circle, that is, the vortex radius, in meters; U is the tangential velocity of the calculation point, in units ; K is a constant; n is an exponent.

[0023] Preferably, according to the law of micro-vortex motion, the G value is inversely proportional to r. The larger the vortex radius, the stronger the inertial effect, and the smaller the G value; the smaller the vortex radius, the opposite; when the minimum vortex characteristic scale is reached, the G value of the vortex is very large; on the other hand, the smaller the vortex, the smaller the rotation radius, and the stronger its centrifugal effect. Therefore, the large-scale vortex has a weak centrifugal effect and a small velocity gradient, and its flocculation condition is very poor. Therefore, if the large-scale vortex can be effectively eliminated in turbulent flow and the proportion of micro-vortices can be increased, the flocculation effect can be greatly improved.

[0024] Preferably, a plurality of water blocking plates are provided, and each of the water blocking plates is correspondingly arranged at the troughs of the first folding plate and the second folding plate.

[0025] Preferably, the interval between the water blocking plates at the primary flocculation section is smaller than the interval between the water blocking plates at the secondary flocculation section.

[0026] Preferably, the selected baseline passes through the highest flow velocity area at the bend of the folded plate.

[0027] Therefore, the present invention adopts the above-mentioned vertical flow folded plate flocculation tank optimization method, which has the following beneficial effects:

[0028] (1) There were problems such as dead water areas and excessive shear force of water flow at the crests and troughs of the folded plate corridor. By improving the right-angle structure of the pool wall, the dead water area at the troughs of the first and second flocculation stages was reduced, and the impact of water flow on the pool wall at the crest of the second flocculation stage was alleviated;

[0029] (2) The amount of flocs in the end gallery of the first flocculation stage is small and the density is low. The folded plates are reduced at the top of the wall at the turning point of the end gallery to prevent the flocs from being destroyed. Many flocs have been formed in the second flocculation stage. The folded plates at the top of the wall at the turning point of the gallery are reduced to protect the flocs. At the same time, folded plates are added at the top of the wall at the turning point of the gallery to prevent the flocs from settling.

[0030] (3) There is a lack of disturbance measures in the central area of ​​the front corridor. In order to improve the efficiency of the early reaction of flocculation, water-blocking plates are added in the first and second flocculation stages to form a flow phenomenon, strengthen the water flow disturbance, and generate a large number of micro-vortices, which are conducive to the formation and growth of flocs.

[0031] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a schematic diagram of an optimization process of an embodiment of the present invention;

[0033] Figure 2 This is a schematic diagram of the optimized flocculation tank structure of an embodiment of the present invention.

[0034] Reference numerals

[0035] 1. Flocculation tank body; 2. Water blocking plate; 3. First partition plate; 4. Second partition plate; 5. First folding plate; 6. Second folding plate; 7. Inlet; 8. Outlet; 9. Primary flocculation section; 10. Secondary flocculation section; 11. Tertiary flocculation section; 12. Third partition plate; 13. Fourth partition plate. DETAILED DESCRIPTION

[0036] Example

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] Reference Figure 1 The present invention discloses an optimization method for a vertical flow folded plate flocculation tank. The flocculation tank comprises a flocculation tank body 1, a water blocking plate 2, a first partition plate 3, a second partition plate 4, a first folded plate 5 and a second folded plate 6. The flocculation tank body 1 comprises an inlet 7, an outlet 8, a primary flocculation section 9, a secondary flocculation section 10 and a tertiary flocculation section 11. The water blocking plate 2 is arranged on the pool wall of the primary flocculation section 9 and the secondary flocculation section 10, the first partition plate 3 and the second partition plate 4. The space between the water blocking plates 2 and the bending part of the pool wall of the flocculation tank are curved. A third partition plate 12 and a fourth partition plate 13 are also arranged in the tertiary flocculation section 11.

[0039] The specific steps are as follows:

[0040] S1. The flow field distribution at the bend of the folded plate is obtained through numerical simulation experiments. A streamline is selected as the baseline in the flow field at the bend of the folded plate at each level of the flocculation tank to determine the water flow velocity at the inlet 7 and the G value of each level of the flocculation tank; the vertical flow folded plate flocculation tank uses the high daily average water volume Q of the water plant as the design water volume, and the flow channel size and inter-plate flow velocity are calculated and determined according to Q. The G value of each section can reach the optimal design value recommended by the "Water Supply and Drainage Design Manual", that is: the G value of the first section is 80-100s -1 The second section G value is 50-60s -1 The third section G value is 20-25s -1 .

[0041] The G value in S1 is calculated as follows:

[0042] ;

[0043] in, Indicates the specific gravity of water in units of ; h represents the head loss, the unit is ; It represents the dynamic viscosity of water in units of ; T represents the reaction time, the unit is .

[0044] The head loss h in the relative folded plate area is proportional to the square of the peak velocity and valley velocity between the plates; the head loss h in the parallel folded plate area and the parallel straight area is proportional to the square of the flow velocity v between the plates. When the installation size of the folded plate is determined, the above flow rates are proportional to the treated water volume Q, that is, the head loss is proportional to the square of the treated water volume Q. When the size of each section of the flocculation tank is determined, the residence time T of each section of the flocculation zone is inversely proportional to the treated water volume Q. Combining the formula of formula G, it can be deduced that:

[0045] When Q1 / Q=a, G1=a 1.5 ×G;

[0046] Where: Q and G represent the design flow rate and design G value respectively;

[0047] Q1 and G1 represent the actual operating flow and actual G value respectively;

[0048] When the water plant operates at the average daily average water volume (the high day coefficient is calculated as 1.3), the operating water volume is Q1=0.769Q, and the actual G1 value of each section of the reaction zone in the flocculation zone is reduced to 0.67 times the designed G value. It can be seen that when the actual water volume treated by the water plant is less than the designed water volume, the G value of each section of the traditional flocculation tank cannot reach the designed optimal G value, which affects the flocculation effect to varying degrees, so it is necessary to improve the structure of the flocculation tank.

[0049] S2, according to the control equation, standard The turbulence model and the movement law of the micro-vortex are used to calculate the angle of the folded plate and the angle of the curvature treatment; when the fluid passes through the arc path, due to the characteristics of the arc, the flow of the fluid on the arc path will be smoother, reducing the obstruction of the fluid, thereby accelerating the flow rate. In contrast, a right-angle turn will cause the fluid to generate greater resistance at the turn, resulting in a slower flow rate, so the water blocking plate 2 is curved.

[0050] S3, optimizing the angles of the folding plate and the bending process according to the calculated values ​​in S2;

[0051] The governing equations in S3 include the mass conservation equation and the momentum conservation equation:

[0052] ;

[0053] in, , , are the scores of the velocity vector in the x, y, and z directions respectively;

[0054] ;

[0055] ;

[0056] ;

[0057] in, It represents the dynamic viscosity of water; Indicates static pressure in units of ; Indicates density in units of ; , Represents other related quantities related to the equation.

[0058] The motion law of the micro-vortex in S3 is as follows:

[0059] ;

[0060] Among them, r is the distance from the calculation point to the center of the circle, in meters; U is the tangential velocity of the calculation point, in units ; K is a constant; n is an exponent.

[0061] According to the law of micro-vortex motion, the larger the vortex radius, the stronger the inertia effect and the smaller the G value; the smaller the vortex radius, the opposite is true; when the minimum vortex characteristic scale is reached, the G value of the vortex is very large; on the other hand, the smaller the vortex, the smaller the rotation radius, and the stronger its centrifugal effect. Therefore, due to the weak centrifugal effect and small velocity gradient of large-scale vortices, their flocculation conditions are very poor. Therefore, if large-scale vortices can be effectively eliminated and the proportion of micro-vortices can be increased in turbulent flow, the flocculation effect can be greatly improved.

[0062] S4. Observe the changes in G value when the angles of the folding plate and the bending treatment are combined at different angles in the numerical simulation experiment, and determine the final optimization of the folding plate and the pool wall.

[0063] There are several water blocking plates 2, all correspondingly arranged at the troughs of the first folded plate 5 and the second folded plate 6. The interval of the water blocking plates 2 at the primary flocculation section 9 is smaller than the interval of the water blocking plates 2 at the secondary flocculation section 10. The selected baseline passes through the highest flow velocity area at the folded plate bend.

[0064] Therefore, the present invention adopts the above-mentioned vertical flow folded plate flocculation tank optimization method to optimize the flocculation effect of the flocculation tank, and has a good effect.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for optimizing a vertical flow folded plate flocculation tank, characterized in that: The adopted flocculation tank comprises a flocculation tank body, a water blocking plate, a first partition plate, a second partition plate, a first folding plate and a second folding plate. The flocculation tank body comprises an inlet, an outlet, a primary flocculation section, a secondary flocculation section and a tertiary flocculation section. The water blocking plates are arranged on the tank walls of the primary flocculation section and the secondary flocculation section, the first partition plate and the second partition plate. The areas between the water blocking plates and the bends of the tank wall of the flocculation tank are all subjected to bending treatment. The specific steps are as follows: S1. Obtain the flow field distribution at the bend of the folded plate through numerical simulation experiments, select a streamline in the flow field at the bend of the folded plate at each level of the flocculation tank as the baseline, determine the water flow velocity at the inlet and determine the G value of each level of the flocculation tank; S2, according to the control equation, standard Turbulence model and the movement law of micro-vortices are used to calculate the angle of the folded plate and the angle of curvature treatment; S3, optimizing the angles of the folding plate and the bending process according to the calculated values ​​in S2; S4. Observe the changes in G value when the angles of the folding plate and the bending treatment are combined at different angles in the numerical simulation experiment, and determine the final optimization of the folding plate and the pool wall.

2. A vertical flow folded plate flocculation tank optimization method according to claim 1, characterized in that: The G value in S1 is calculated as follows: ； in, Indicates the specific gravity of water in units of ; h represents the head loss, the unit is ; It represents the dynamic viscosity of water in units of ; T represents the reaction time, the unit is .

3. A vertical flow folded plate flocculation tank optimization method according to claim 1, characterized in that: The governing equations in S2 include the mass conservation equation and the momentum conservation equation: ； in, , , are the scores of the velocity vector in the x, y, and z directions respectively; ； ； ； in, It represents the dynamic viscosity of water; Indicates static pressure in units of ; Indicates density in units of ; , , Represents other related quantities related to the equation.

4. A vertical flow folded plate flocculation tank optimization method according to claim 1, characterized in that: The motion law of the micro-vortex in S2 is as follows: ； Among them, r is the distance from the calculation point to the center of the circle, in meters; U is the tangential velocity of the calculation point, in units ; K is a constant; n is an exponent.

5. A method for optimizing a vertical flow folded plate flocculation tank according to claim 4, characterized in that: According to the law of micro-vortex motion, the G value is inversely proportional to r.

6. The method for optimizing a vertical flow folded plate flocculation tank according to claim 1, characterized in that: A plurality of water blocking plates are provided, and all are correspondingly arranged at the troughs of the first folding plate and the second folding plate.

7. The method for optimizing a vertical flow folded plate flocculation tank according to claim 1, characterized in that: The interval of the water blocking plates at the primary flocculation section is smaller than the interval of the water blocking plates at the secondary flocculation section.

8. The method for optimizing a vertical flow folded plate flocculation tank according to claim 1, characterized in that: The selected baseline passes through the highest flow velocity area at the bend of the folded plate.

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