A multi-loop variable flow pattern mixing system and its engraving design and performance evaluation method

Abstract

The present invention discloses a multi-circuit variable flow state mixing system and a method for engraving design and performance evaluation, which relates to the field of mixing technology. The system includes a tank body, a liquid inlet is provided at the front end of the tank body, a liquid discharge port is provided at the rear end of the tank body, and at least one circuit mixing module is provided in the tank body between the liquid inlet and the liquid discharge port; the circuit mixing module includes an upper baffle, a lower baffle, and a base; an arc groove is provided at the upper end of the base, and a flow pattern engraving is provided on the surface of the arc groove; the upper end of the upper baffle is connected to the upper wall of the inner cavity of the tank body, the frontmost upper baffle is behind the liquid inlet, and the lower end of the upper baffle is inserted into the arc groove; the lower baffle is fixedly arranged at the rear end of the base. The present invention achieves full mixing when the acid solution flows through the system by strengthening the rotating flow state, and realizes the online preparation of gelled acid solution.

Description

Technical Field

[0001] The invention relates to the field of mixing technology, in particular to a multi-loop variable flow state mixing system and a carving design and performance evaluation method. Background Art

[0002] The exploration and development of carbonate oil and gas reservoirs in my country is gradually moving towards ultra-deep layers, ultra-high temperatures and ultra-high pressures. It has become a hot spot for deep oil and gas exploration and the main body of oil and gas reserve growth, showing huge potential for oil and gas resource replacement. The engineering geological characteristics of deep marine carbonate oil and gas reservoirs in Sichuan are extremely complex. In recent years, the large-scale acid fracturing process based on gelled acid has been used with good results, and it is expected to further achieve breakthroughs in the exploration and development of deep-layer deep-earth engineering.

[0003] The core of large-scale acid fracturing process lies in the preparation of large amounts of gelling acid. To achieve rapid preparation of large amounts of gelling acid, the acid preparation process must be improved, and the traditional acid preparation machine must be upgraded to a large-scale acid mixing skid / truck. However, the acid mixing truck still fails to solve the problems of uniform mixing, foaming and metering of gelling powder and liquid. As a result, the acid preparation efficiency has not been greatly improved and the acid preparation quality does not meet the design requirements. Therefore, the acid mixing skid / truck has not yet replaced the traditional acid preparation machine.

[0004] The key to solving the problem lies in the design of the buffer tank. Currently, the buffer tanks widely used on site are only designed with stirring function. However, since the agitator is located in the middle of the tank and due to the viscosity of the acid, the rotation flow of the acid in the tank is very uneven, and it is impossible to achieve uniform mixing through one cycle. The time for multiple cycles is not much different from other mixing methods, and the efficiency and quality have not met expectations.

[0005] Publication No.: CN107261975A, discloses a continuous acid mixing equipment, which realizes continuous mixing of acid solution by combining a continuous acid mixing vehicle and a skid-mounted buffer tank. At the same time, by configuring an acid mist removal device in the acid mixing tank, a large amount of acid mist and foam generated during the acid mixing process can be effectively removed, making the operating performance of the whole machine safer.

[0006] This prior art uses a double-chamber double-agitator for mixing, but still has the problem of not being able to achieve uniform mixing through one cycle.

[0007] Announcement No.: CN106246157B, discloses a skid-mounted acid preparation device and an acid preparation method thereof. The vacuum pumping system uses a vacuum pump to evacuate the buffer tank so that the buffer tank is under negative pressure for a long time during the acid preparation operation, providing power for the acid absorption system.

[0008] The purpose of the buffer tank in the prior art is inconsistent with the present invention.

[0009] Publication No.: CN115872504A, discloses an integrated magnetic coagulation and sedimentation device for sewage treatment. When in use, sewage is introduced into a reaction tank, and the sewage passes through a first reaction chamber and a second reaction chamber in sequence. A flocculant is added to the first reaction chamber, and magnetic powder is added to the second reaction chamber. The first stirring mechanism and the second stirring mechanism are continuously used for stirring to fully mix the flocculant and sewage as well as the magnetic powder and sewage.

[0010] This prior art belongs to a similar field and uses multiple circuits and multiple agitators for mixing, but still has the problem of not being able to achieve uniform mixing through one cycle.

[0011] In summary, the technical solutions of the above-disclosed technologies, the technical problems to be solved, and the beneficial effects produced are all different from the present invention. Regarding more technical features, technical problems to be solved, and beneficial effects of the present invention, the above-disclosed technical documents do not provide any technical inspiration. Summary of the invention

[0012] In view of the above-mentioned defects in the prior art, the purpose of the present invention is to provide a multi-loop variable flow state mixing system and a carving design and performance evaluation method, which can realize the output of finished acid after one cycle of acid liquid and solve the acid mist and foaming problems in the acid preparation process.

[0013] In order to achieve the above object, the present invention adopts the following technical solutions:

[0014] On the one hand, the present invention provides a multi-loop variable flow state mixing system, including a tank body, wherein a liquid inlet is provided at the front end of the tank body, a liquid discharge port is provided at the rear end of the tank body, and at least one loop mixing module is provided inside the tank body between the liquid inlet and the liquid discharge port; the loop mixing module includes an upper baffle, a lower baffle, and a base; an arc groove is provided at the upper end of the base, and flow pattern engravings are provided on the surface of the arc groove; the upper end of the upper baffle is connected to the upper wall of the tank body cavity, the frontmost upper baffle is behind the liquid inlet, and the lower end of the upper baffle is inserted into the arc groove; the lower baffle is fixedly arranged at the rear end of the base.

[0015] Furthermore, the total height of the flow pattern pattern surface is h, the flow pattern pattern has N patterns, h / a0<N<h / 2a0, and the pattern spacing is a n , a0 is a constant, n is a coefficient, then the groove spacing conforms to the following formula:

[0016] ;

[0017] .

[0018] Furthermore, the arc groove includes two front and rear semicircles, and the carving height of the flow carving is equal to the carving depth, which is 1% of the tank wall thickness; a0=0.05r0, r0 is the ring radius of the two front and rear semicircles of the arc groove.

[0019] Furthermore, the surface of the lower baffle plate facing the liquid inlet is provided with flow pattern grooves;

[0020] Specifically, the arc groove includes two front and rear semicircles, a separation groove is arranged between the front and rear semicircles, and the separation groove is parallel to the lower baffle; the flow pattern carvings in front of the separation groove in the arc groove rotate downward, and the flow pattern carvings in the arc groove behind the separation groove rotate upward.

[0021] Furthermore, the loop mixing module further comprises a stirrer, which is arranged on the top of the tank body, the rotating shaft of the stirrer is inserted into the tank body and points to the arc groove, and a stirring paddle is arranged at the bottom of the rotating shaft;

[0022] Specifically, the stirring blade of the stirring paddle has two average flow velocity points on the left and right, and the average flow velocity points satisfy:

[0023] ;

[0024] In the formula, L0 is the total length of a single stirring blade, and L1 is the length of the average flow velocity point of a single stirring blade;

[0025] Specifically, two spherical surfaces are formed with two average flow velocity points of the stirring blade as the center of the circle, and the union of the two spherical surfaces at the base is an arc groove.

[0026] Furthermore, the loop mixing module also includes a defoaming device, which is arranged on the top of the tank body, the defoaming device is located directly above the lower baffle, the output shaft of the defoaming device is inserted into the tank body, and a first defoaming impeller is arranged at the bottom of the output shaft.

[0027] Furthermore, the tank body is provided with a liquid level control system, which includes an external liquid level gauge and a built-in radar liquid level gauge, and the built-in radar liquid level gauge is electrically connected to the acid dispensing system;

[0028] Specifically, the tank body is rectangular in shape as a whole; the liquid inlet is arranged at the front end of the upper wall of the tank body; the liquid discharge port is arranged at the lower rear end of the side wall of the tank body; and an acid mist neutralization port is arranged at the top of the tank body;

[0029] Specifically, the upper baffle is in a straight upper and curved lower state, and the curvature of the lower part of the upper baffle is the same as the curvature of the front arc on the central surface of the arc groove;

[0030] Specifically, the lower baffle is in a vertical state, and the height of the lower baffle is 2 / 3 of the height of the tank body;

[0031] Specifically, the stirring paddle is flush with the upper end surface of the base, and the stirring paddle is arranged at the 1 / 2 position of the tank body;

[0032] Specifically, the base is provided with an emptying port at the bottom of the separation groove.

[0033] In another aspect, the present invention provides a method for designing a flow pattern pattern in a multi-circuit variable flow pattern mixing system. The method for designing a flow pattern pattern in a multi-circuit variable flow pattern mixing system comprises the following steps:

[0034] S1. Establishment of basic physical model:

[0035] The kinetic model was established using the following basic formula:

[0036] ;

[0037] P is the stirring power, W;

[0038] N p is a dimensionless power number that depends on the type of stirring and the fluid properties;

[0039] ρ is the fluid density, kg / m 3 ;

[0040] N is the stirrer speed, rps;

[0041] D is the stirrer diameter, m;

[0042] S2. Geometric parameters of flow pattern:

[0043] Engraving depth, engraving width, engraving spacing;

[0044] S3, shear stress formula, fluid velocity field:

[0045] The geometric parameters of flow pattern sculpture affect the shear stress τ:

[0046] ;

[0047] τ is the shear stress, Pa;

[0048] μ is the dynamic viscosity of the fluid, Pa·s;

[0049] is the velocity gradient, which is determined by the geometric parameters of the flow pattern;

[0050] Model fluid flow using the Navier-Stokes equations:

[0051] ;

[0052] is the fluid velocity vector, m / s;

[0053] P is the fluid pressure, Pa;

[0054] μ is the dynamic viscosity in Pa·s;

[0055] is an external force, such as gravity, kg;

[0056] S4. Simulation design steps:

[0057] Establish a model and use simulation software to establish a geometric model of the flow pattern carving on the inner wall of the mixing tank, set the carving depth, width and spacing, and define the material and physical properties of the agitator, tank body, flow pattern carving and liquid;

[0058] Divide the mesh in the fluid domain to capture the disturbance of the fluid at the flow pattern grooves;

[0059] Set the stirrer speed N, the density ρ and viscosity μ of the liquid, and the boundary conditions of the stirring tank. The geometry of the flow pattern will serve as the wall boundary conditions to affect the fluid flow.

[0060] Through CFD simulation, the Navier-Stokes equations are solved, the fluid velocity field, shear stress distribution, and fluid disturbance are analyzed, and the optimal flow pattern geometry parameters are found through the flow field distribution.

[0061] In a third aspect, the present invention provides a method for evaluating flow pattern carving in a multi-loop variable flow pattern mixing system, which evaluates the performance of the flow pattern carving obtained by the design method described in the second aspect, comprising the following steps:

[0062] F1. Calculate the effect of flow pattern on shear stress:

[0063] ;

[0064] τ w is the wall shear stress, Pa;

[0065] C f is the wall friction coefficient;

[0066] ρ is the fluid density, kg / m³;

[0067] v is the flow velocity in the engraved area, m / s;

[0068] F2. The effect of the carving on turbulence is measured by the turbulence intensity I:

[0069] ;

[0070] u′ is the RMS value of velocity fluctuation;

[0071] U is the average flow velocity, m / s;

[0072] F3, using particle settling velocity v s Compare with the fluid flow rate to determine whether the groove depth design is appropriate:

[0073] ;

[0074] r is the particle radius, m;

[0075] ρ p is the particle density, kg / m³;

[0076] ρ is the liquid density, kg / m³;

[0077] g is the acceleration due to gravity;

[0078] μ is the fluid viscosity, Pa·s;

[0079] F4. The overall mixing power of the mixing tank is calculated by increasing the shear stress. The total mixing power P can be expressed as:

[0080] ;

[0081] A is the cross-sectional area, m 2 .

[0082] Compared with the prior art, the present invention has the following beneficial effects:

[0083] 1. The present invention strengthens the rotational flow state so that the acid solution is fully mixed when it flows through the system, thereby realizing the online preparation of the gelled acid solution.

[0084] 2. The present invention reduces sedimentation through the design of a stirrer and an arc-shaped trough, prolongs the maintenance interval of the system, and improves the working time rate.

[0085] 3. The present invention realizes the prevention and treatment of foam and acid mist by arranging a defoaming device and an acid mist neutralization port.

[0086] 4. The present invention can design flow patterns with excellent performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0087] Figure 1 It is a structural schematic diagram of a multi-circuit variable flow state mixing system of the present invention;

[0088] Figure 2 It is a schematic diagram of the liquid flow direction of a multi-circuit variable flow state mixing system of the present invention;

[0089] Figure 3 It is a schematic diagram of the structure of the flow pattern in the present invention;

[0090] Figure 4 It is a schematic diagram of the dimensions of the stirring blade of the present invention.

[0091] In the figure: 1, liquid inlet; 2, first upper baffle; 3, first agitator; 4, first defoaming device; 5, second upper baffle; 6, second agitator; 7, second defoaming device; 8, acid mist neutralization port; 9, first lower baffle; 10, second lower baffle; 11, first base; 12, second base; 13, liquid discharge port; 14, first dividing groove; 15, second dividing groove; 16, first emptying port; 17, second emptying port; 18, first arc groove; 19, second arc groove. DETAILED DESCRIPTION

[0092] 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.

[0093] Embodiment 1:

[0094] See also Figures 1 to 3 The present invention provides a multi-circuit variable flow state mixing system, comprising a tank body, wherein the front end of the tank body is provided with a liquid inlet 1, the rear end of the tank body is provided with a liquid discharge port 13, the top of the tank body is provided with an acid mist neutralization port 8, and the tank body is provided with a first circuit mixing module and a second circuit mixing module between the liquid inlet 1 and the liquid discharge port 13.

[0095] The first circuit mixing module includes a first upper baffle plate 2, a first lower baffle plate 9, and a first base 11. The upper end of the first base 11 is provided with a first arc groove 18, and the surface of the first arc groove 18 is provided with flow pattern grooves. The first lower baffle plate 9 is provided with flow pattern grooves on the side facing the liquid inlet 1; the upper end of the first upper baffle plate 2 is connected to the upper wall of the inner cavity of the tank body, the first upper baffle plate 2 is behind the liquid inlet 1, the lower end of the first upper baffle plate 2 is inserted into the first arc groove 18, and the first lower baffle plate 9 is fixedly arranged at the rear end of the first base 11.

[0096] The second circuit mixing module includes a second upper baffle plate 5, a second lower baffle plate 10, and a second base 12. A second arc groove 19 is provided at the upper end of the second base 12. The surface of the second arc groove 19 is provided with flow pattern grooves. The second lower baffle plate 10 is provided with flow pattern grooves on the side facing the liquid inlet 1. The upper end of the second upper baffle plate 5 is connected to the upper wall of the inner cavity of the tank body. The second upper baffle plate 5 is behind the first lower baffle plate 9. The lower end of the second upper baffle plate 5 is inserted into the second arc groove 19. The second lower baffle plate 10 is fixedly arranged at the rear end of the second base 12.

[0097] Streamlines in the tank: Liquid enters from the liquid inlet 1, flows downward in the space between the front wall of the tank cavity and the first upper baffle 2, and enters the first arc groove 18. In the first arc groove 18, the liquid is affected by the flow pattern and fully mixed; in the first arc groove 18, the liquid moving upward eventually leaves the first arc groove 18 and enters the space between the first upper baffle 2 and the first lower baffle 9; the liquid flows upward in the space between the first upper baffle 2 and the first lower baffle 9, passes through the first lower baffle 9, and enters the space between the first lower baffle 9 and the second upper baffle 5; the liquid flows upward in the space between the first upper baffle 2 and the first lower baffle 9, and enters the space between the first lower baffle 9 and the second upper baffle 5; The space between the baffle plate 9 and the second upper baffle plate 5 moves downward and enters the second arc groove 19, where the liquid is affected by the flow patterns and is fully mixed; the liquid moving upward in the second arc groove 19 eventually enters the space between the second upper baffle plate 5 and the second lower baffle plate 10; the liquid moves upward in the space between the second upper baffle plate 5 and the second lower baffle plate 10, passes through the second lower baffle plate 10, and enters the space between the second lower baffle plate 10 and the rear wall of the tank body cavity; the liquid moves downward in the space between the second lower baffle plate 10 and the rear wall of the tank body cavity, and is eventually discharged from the drain port 13.

[0098] The tank is rectangular in shape and has a volume no greater than 15m 3 , the inner wall and openings are treated with heavy anti-corrosion.

[0099] Among them, the liquid inlet 1 is arranged at the front end of the upper wall of the tank body, and is designed to be 6 in a single row; the discharge port 13 is arranged at the lower rear end of the side wall of the tank body, and 3 are arranged on each side wall, for a total of 6; the liquid inlet 1 and the discharge port 13 are opened or closed according to the acid preparation demand to control the acid preparation speed; the acid mist neutralization port 8 is connected to the acid mist removal device through a channel, and the acid mist neutralization port 8 plays a role in connecting with the atmosphere to balance the air pressure, which can ensure that the liquid enters the tank body smoothly and discharges the liquid from the tank.

[0100] The baffle and the stirring tank are combined to form a downward and upward circulation channel, two stirring tanks and four baffles form four circulation channels, and inspection holes are arranged on the upper wall of the tank body, and each channel corresponds to an inspection hole.

[0101] Among them, the first upper baffle plate 2 is in a state of being straight up and bent down, and the arc of the lower part of the first upper baffle plate 2 is the same as the curvature of the front arc on the center plane of the first arc groove 18; the second upper baffle plate 5 is in a state of being straight up and bent down, and the arc of the lower part of the second upper baffle plate 5 is the same as the curvature of the front arc on the center plane of the second arc groove 19.

[0102] Among them, the first lower baffle plate 9 and the second lower baffle plate 10 are in a vertical state, and the height of the first lower baffle plate 9 and the second lower baffle plate 10 is 2 / 3 to 5 / 6 of the height of the tank body.

[0103] Among them, the flow pattern carving plays a role in accelerating the flow of liquid. The flow pattern carving is a spiral pattern. The carving height and depth determine the coverage of the disturbance. The carving height can match the carving depth, that is, the two are equal, and the size is 1% of the tank wall thickness. The spacing of the carvings needs to be small enough to ensure the disturbance of the entire tank inner wall, but not too small to avoid fluid retention and dead zone. Therefore, the carving spacing is taken as 5%-10% of the radius of the circular ring at the top of the arc groove.

[0104] Specifically, the total height of the flow pattern pattern surface is h, the flow pattern pattern has N patterns, h / a0<N<h / 2a0, and the pattern spacing is a n , a0 is a constant, n is a coefficient, then the groove spacing conforms to the following formula:

[0105] ;

[0106] ;

[0107] Let a0=0.05r0, 5% of the radius of the circular ring at the upper end of the arc groove, then the following formula is satisfied:

[0108] .

[0109] Specifically, a first dividing groove 14 is arranged at the center of the first arc groove 18, and a second dividing groove 15 is arranged at the center of the second arc groove 19, and the first dividing groove 14 and the second dividing groove 15 are parallel to the first lower baffle plate 9; the flow pattern engraving located in front of the first dividing groove 14 in the first arc groove 18 rotates downward, and the flow pattern engraving located in front of the second dividing groove 15 in the second arc groove 19 rotates downward, and the flow pattern is downward; the flow pattern engraving located behind the first dividing groove 14 in the first arc groove 18 rotates upward, and the flow pattern engraving located behind the second dividing groove 15 in the second arc groove 19 rotates upward, and the flow pattern is upward; the first base 11 is provided with a first drain port 16 at the bottom of the first dividing groove 14, and the second base 12 is provided with a second drain port 17 at the bottom of the second dividing groove 15.

[0110] More specifically, the first agitator 3, the second agitator 6, the upward swirling flow pattern carvings, and the downward swirling flow pattern carvings all rotate clockwise; when the liquid flow enters the separation groove from the downward swirling flow pattern carvings, a part of it moves upward through the separation groove, and a part of it moves upward through the upward swirling flow pattern carvings; when the liquid flow enters the separation groove from the upward swirling flow pattern carvings, a part of it moves upward, and a part of it moves downward. The downward moving liquid flow interferes with the upward moving liquid flow in the center of the arc groove, thereby enhancing the mixing effect. At the same time, the liquid flow at the bottom of the arc groove is rotated upward from the downward swirling flow pattern carvings. The rotational change can enhance the scouring effect of the liquid flow on the bottom of the groove and reduce precipitation; at the same time, the liquid that has not entered the flow pattern groove passes through the first arc groove 18 and the second arc groove 19 under the action of the first agitator 3 and the second agitator 6, and changes the direction of the liquid flow under the guidance of the first upper baffle plate 2, the first lower baffle plate 9, the second upper baffle plate 5, and the second lower baffle plate 10. The liquid flow direction is not exactly the same as the liquid flow direction in the flow pattern groove, forming shear turbulence and enhancing the mixing effect; the drain port is used to empty the arc groove and discharge the sediment in the arc groove during cleaning and maintenance.

[0111] Furthermore, the tank is provided with a liquid level control system, which includes an external liquid level gauge and a built-in radar liquid level gauge. The external liquid level gauge is used for on-site inspectors to directly see the liquid level, and the built-in radar liquid level gauge is electrically connected to the acid distribution system to send out liquid level information, which is convenient for the acid distribution system to control the overall displacement and set a safe liquid level position. It should be noted that the external liquid level gauge and radar liquid level gauge themselves belong to the prior art and can be purchased, and those skilled in the art are clear about this.

[0112] Embodiment 2:

[0113] The height, depth and spacing of the grooves will directly affect the fluid dynamics behavior near the tank wall. This embodiment provides a design method for the flow grooves:

[0114] S1. Establishment of basic physical model:

[0115] The dynamics of agitators are usually described by turbulence models. Combining parameters such as stirring speed, fluid viscosity, stirring power, etc., the following basic formula is used to establish the dynamic model:

[0116] ;

[0117] P is the stirring power, W;

[0118] N p is a dimensionless power number that depends on the type of stirring and the fluid properties;

[0119] ρ is the fluid density, kg / m 3 ;

[0120] N is the stirrer speed, rps;

[0121] D is the stirrer diameter, m;

[0122] S2. Geometric parameters of flow pattern:

[0123] Engraving depth: affects the intensity of fluid disturbance. Too large a depth may cause a dead zone, while too small a depth may not cause sufficient disturbance.

[0124] Engraving width: The width determines the size of the channel through which the fluid passes through the engraving, affecting the shear stress and flow velocity;

[0125] Engraving spacing: Too large a spacing may lead to uneven flow, while too small a spacing may increase manufacturing difficulty;

[0126] These parameters affect the stirring efficiency and the shear stress of the fluid; in order to find the best combination of parameters, the following formula is used.

[0127] S3, shear stress formula, fluid velocity field:

[0128] The geometric parameters of the flow pattern affect the shear stress τ, which can be estimated by the following formula:

[0129] ;

[0130] τ is the shear stress, Pa;

[0131] μ is the dynamic viscosity of the fluid, Pa·s;

[0132] is the velocity gradient, which is determined by the geometric parameters of the flow pattern;

[0133] The greater the shear stress, the easier it is to suspend solids and prevent the sedimentation of insoluble substances;

[0134] Fluid velocity field:

[0135] Model fluid flow using the Navier-Stokes equations:

[0136] ;

[0137] is the fluid velocity vector, m / s;

[0138] P is the fluid pressure, Pa;

[0139] μ is the dynamic viscosity in Pa·s;

[0140] is an external force, such as gravity, N.

[0141] S4. Simulation design steps:

[0142] The geometry of the flow pattern will change the fluid velocity field, so the velocity gradient and shear stress distribution need to be analyzed through simulation tools;

[0143] Build a model and use simulation software (such as Ansys Fluent) to build a geometric model of the flow pattern grooves on the inner wall of the mixing tank, set the groove depth, width and spacing, and define the material and physical properties of the agitator, tank body, grooves and liquid;

[0144] Meshing: Meshing in the fluid domain to ensure that the mesh in the flow pattern carving area is fine enough to capture the disturbance of the fluid at the flow pattern carving area;

[0145] Set boundary conditions, set the stirrer speed N, the density ρ and viscosity μ of the liquid, and the boundary conditions of the mixing tank. The geometric shape of the flow pattern will serve as the wall boundary condition to affect the fluid flow;

[0146] Run the simulation, solve the Navier-Stokes equations through CFD simulation, analyze the fluid velocity field, shear stress distribution, and fluid disturbance, and find the optimal flow pattern geometry parameters through flow field distribution;

[0147] Optimization design,The geometric parameters of the flow pattern are optimized according to the simulation results.,The goal is to ensure uniform flow, sufficient shear stress to suspend insoluble substances, and no obvious dead zone in the flow field.

[0148] Embodiment 3:

[0149] This embodiment provides a method for evaluating the contribution of flow pattern carving to mixing:

[0150] F1. Flow pattern carving increases the shear stress of the liquid near the tank wall. The wall friction coefficient C can be used to calculate the effect of flow pattern carving on shear stress. f and the flow gradient:

[0151] ;

[0152] τ w is the wall shear stress, Pa;

[0153] C f is the wall friction coefficient, which is related to the geometry, depth, width and other parameters of the flow pattern;

[0154] ρ is the fluid density, kg / m³;

[0155] v is the flow velocity in the flow pattern engraving area, m / s;

[0156] The greater the depth and width of the groove, the greater the wall friction coefficient C f The larger it is, the greater the shear stress is, which means that more energy is consumed in the flow pattern area and the liquid mixing effect is enhanced.

[0157] F2. The influence of flow pattern carving on turbulence can be measured by introducing turbulence intensity I:

[0158] ;

[0159] u′ is the RMS value of velocity fluctuation, which is proportional to the depth and width of the groove;

[0160] U is the average flow velocity, m / s;

[0161] The increase in turbulence intensity indicates that the liquid mixing effect is enhanced and can effectively prevent particle deposition; the depth and width of the grooves directly affect the length scale of turbulence. t , l t ∝ Engraving depth × Engraving width;

[0162] The increase in turbulence scale means an increase in the degree of fluid mixing, but it also increases energy loss. Therefore, a balance needs to be struck between turbulence enhancement and energy consumption when designing the geometric parameters of flow patterns.

[0163] F4. In order to prevent particles from settling in the flow pattern, the particle settling velocity v s The engraving depth design is appropriate by comparing it with the fluid flow rate. The particle settling velocity can be estimated using the Stokes formula:

[0164] ;

[0165] r is the particle radius, m;

[0166] ρ p is the particle density, kg / m³;

[0167] ρ is the liquid density, kg / m³;

[0168] g is the acceleration due to gravity;

[0169] μ is the fluid viscosity, Pa·s.

[0170] F4. After the flow pattern is introduced, the increase in the overall mixing power of the mixing tank can be calculated by the increased shear stress. The total mixing power P can be expressed as:

[0171] ;

[0172] A is the cross-sectional area, m 2 ;

[0173] Among them, the flow pattern increases the local wall shear stress τ w Thereby improving the overall stirring power.

[0174] Embodiment 4:

[0175] Based on Example 1 Figure 4 .

[0176] The first loop mixing module further comprises a first agitator 3, which is arranged on the top of the tank body. A first rotating shaft of the first agitator 3 is inserted into the tank body and points to the first arc-shaped groove 18, and a first stirring paddle is arranged at the bottom of the first rotating shaft.

[0177] The second loop mixing module further comprises a second agitator 6, which is arranged on the top of the tank body. A second rotating shaft of the second agitator 6 is inserted into the tank body and points to the second arc groove 19, and a second stirring paddle is arranged at the bottom of the second rotating shaft.

[0178] The stirring blade in the first stirring paddle or the second stirring paddle has two average flow velocity points on the left and right. The average flow velocity point is on the stirring blade. The speed of this point is the average of the sum of the speeds of all points on the stirring blade, calculated by the integration method.

[0179] The formula for calculating the stirring linear velocity is:

[0180] ;

[0181] The average flow velocity point satisfies the following formula:

[0182] ;

[0183] The calculation can be obtained:

[0184] ;

[0185] In the formula, L0 is the total length of a single stirring blade, L is the length of any point of a single stirring blade, L1 is the length of the single stirring blade at the average flow velocity point, ω is the angular velocity of the stirring blade, υ L is the speed of the stirring blade at point L.

[0186] Specifically, the first stirring paddle is flush with the upper end surface of the first base 11 , and the second stirring paddle is flush with the upper end surface of the second base 12 . The first stirring paddle and the second stirring paddle are arranged at the 1 / 2 position of the tank body.

[0187] Two spheres are formed with the two average flow velocity points of the stirring blade as the center of the circle. The union of the two spheres at the base is an arc groove, which ensures that the distance between the left side of the groove bottom and the left average flow velocity point is equal, and the distance between the right side of the groove bottom and the right average flow velocity point is equal, thereby ensuring uniform flow velocity and no sedimentation. At this time, r0 is the radius of the sphere.

[0188] Furthermore, the first loop mixing module also includes a first defoaming device 4, which is arranged on the top of the tank body, and the first defoaming device 4 is located directly above the first lower baffle 9. The first output shaft of the first defoaming device 4 is inserted into the tank body, and a first defoaming impeller is arranged at the bottom of the first output shaft.

[0189] Furthermore, the second circuit mixing module also includes a second defoaming device 7, which is arranged on the top of the tank body, and the second defoaming device 7 is located directly above the second lower baffle 10. The second output shaft of the second defoaming device 7 is inserted into the tank body, and a second defoaming impeller is arranged at the bottom of the second output shaft.

[0190] Specifically, the driving part in the first agitator 3 or the second agitator 6 is a stirring motor, and the driving part in the first defoaming device 4 or the second defoaming device 7 is a defoaming motor. Electric drive is easy to control and electricity is easy to obtain.

[0191] Embodiment 5:

[0192] Based on Example 4, this embodiment provides a method for using a multi-circuit variable flow state mixing system, comprising the following steps:

[0193] High-viscosity premixed acid, clean water and additives enter the tank from the liquid inlet 1 through the mixing pipe;

[0194] The mixed liquid is affected by the downward swirling grooves in the space between the front wall of the inner cavity of the tank body and the first upper baffle plate 2, and is sucked by the first stirrer 3, so that the mixed liquid accelerates the downward swirling motion;

[0195] The mixed liquid in the space between the first upper baffle plate 2 and the first lower baffle plate 9 is partially affected by the upward swirl pattern, partially affected by the downward swirl pattern, and partially affected by the lifting effect of the first agitator 3. The mixed liquid with different flow directions generates turbulence, thereby enhancing the mixing effect.

[0196] The mixed liquid is affected by the downward swirling grooves in the space between the second upper baffle plate 5 and the second lower baffle plate 10, and is sucked by the second agitator 6, so that the mixed liquid accelerates the downward swirling motion;

[0197] The mixed liquid in the space between the second upper baffle plate 5 and the second lower baffle plate 10 is partially affected by the upper swirl flow grooves, partially affected by the lower swirl flow grooves, and partially affected by the suction of the second agitator 6. The mixed liquid with different flow directions generates turbulence, thereby enhancing the mixing effect.

[0198] The mixed liquid is discharged from the liquid discharge port 13 after passing through the second lower baffle 10. During the movement of the mixed liquid, the high-viscosity pre-mixed acid, clean water and additives are fully mixed;

[0199] When the acid liquid discharge volume is too large, adjust the parameters of the acid dispensing system to control the discharge volume. During the acid dispensing period, the liquid level control system continuously sends the liquid level information to the acid dispensing system to avoid acid liquid overflow.

[0200] After the acid preparation is completed, the system is emptied through the first drain port 16 and the second drain port 17 to discharge the sediment and perform maintenance and cleaning.

[0201] All components and connection methods of components not discussed in this application belong to the known technologies in this technical field and can be directly applied without further explanation.

[0202] In the present invention, the term "plurality" refers to two or more than two, unless otherwise clearly defined. The terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; "connected" can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0203] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by terms such as “upper”, “lower”, “left”, “right”, “front” and “back” are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or unit referred to must have a specific direction, be constructed and operated in a specific orientation, and therefore, cannot be understood as a limitation on the present invention.

[0204] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "specific embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0205] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A multi-circuit variable flow state mixing system, comprising a tank body, wherein the front end of the tank body is provided with a liquid inlet, and the rear end of the tank body is provided with a liquid discharge port, characterized in that: At least one loop mixing module is arranged in the tank between the liquid inlet and the liquid outlet; The loop mixing module includes an upper baffle, a lower baffle, and a base; The upper end of the base is provided with an arc groove, and the surface of the arc groove is provided with flow patterns; The upper end of the upper baffle is connected to the upper wall of the tank body cavity, the front upper baffle is behind the liquid inlet, and the lower end of the upper baffle is inserted into the arc groove; The lower baffle is fixedly arranged at the rear end of the base; The surface of the lower baffle plate facing the liquid inlet is provided with flow pattern grooves; The arc groove includes two front and rear semicircles, a separation groove is arranged between the front and rear semicircles, and the separation groove is parallel to the lower baffle; the flow pattern carvings in front of the separation groove in the arc groove rotate downward, and the flow pattern carvings in the arc groove behind the separation groove rotate upward.

2. A multi-circuit variable flow state mixing system according to claim 1, characterized in that: The total height of the flow pattern surface is h, the flow pattern has N patterns, h / a0<N<h / 2a0, and the pattern spacing is a n , a0=0.05r0, r0 is the radius of the two semicircles before and after the arc groove, n is the number of grooves, then the groove spacing conforms to the following formula: ； 。 3. A multi-circuit variable flow state mixing system according to claim 2, characterized in that: The groove height of the flow groove is equal to the groove depth, which is 1% of the tank wall thickness.

4. A multi-circuit variable flow state mixing system according to claim 1, characterized in that: The loop mixing module also includes a stirrer, which is arranged on the top of the tank body, the rotating shaft of the stirrer is inserted into the tank body and points to the arc groove, and a stirring paddle is arranged at the bottom of the rotating shaft; The stirring blade of the stirring paddle has two average flow velocity points on the left and right, and the average flow velocity points satisfy: ； In the formula, L0 is the total length of a single stirring blade, and L1 is the length of the average flow velocity point of a single stirring blade; Two spherical surfaces are formed with two average flow velocity points of the stirring blade as the center of the circle, and the union of the two spherical surfaces at the base is an arc groove.

5. A multi-circuit variable flow state mixing system according to claim 4, characterized in that: The loop mixing module also includes a defoaming device, which is arranged on the top of the tank body and directly above the lower baffle. The output shaft of the defoaming device is inserted into the tank body, and a first defoaming impeller is arranged at the bottom of the output shaft.

6. A multi-circuit variable flow state mixing system according to claim 4, characterized in that: The tank body is provided with a liquid level control system, which includes an external liquid level meter and a built-in radar liquid level meter, and the built-in radar liquid level meter is electrically connected to the acid dispensing system; The tank body is rectangular in shape as a whole; the liquid inlet is arranged at the front end of the upper wall of the tank body; the liquid discharge port is arranged at the lower rear end of the side wall of the tank body; and an acid mist neutralization port is arranged at the top of the tank body; The upper baffle is in a straight upper and curved lower state, and the curvature of the lower part of the upper baffle is the same as the curvature of the front arc on the central surface of the arc groove; The lower baffle is in a vertical state, and the height of the lower baffle is 2 / 3 of the height of the tank body; The stirring paddle is flush with the upper end surface of the base, and the stirring paddle is arranged at the 1 / 2 position of the tank body; The base is provided with an emptying port at the bottom of the separation groove.

7. A design method for flow pattern carving in a multi-circuit variable flow pattern mixing system, characterized in that: Designing a flow pattern carving in a multi-circuit variable flow pattern mixing system as described in claim 4 comprises the following steps: S1. Establishment of basic physical model: The kinetic model was established using the following basic formula: ； P is the stirring power, W; N p is a dimensionless power number that depends on the type of stirring and the fluid properties; ρ is the fluid density, kg / m 3 ; N is the stirrer speed, rps; D is the stirrer diameter, m; S2. Geometric parameters of flow pattern: Engraving depth, engraving width, engraving spacing; S3, shear stress formula, fluid velocity field: The geometric parameters of flow pattern sculpture affect the shear stress τ: ； τ is the shear stress, Pa; μ is the dynamic viscosity of the fluid, Pa·s; is the velocity gradient, which is determined by the geometric parameters of the flow pattern; Model fluid flow using the Navier-Stokes equations: ； is the fluid velocity vector, m / s; P is the fluid pressure, Pa; μ is the dynamic viscosity in Pa·s; is an external force, such as gravity, kg; S4. Simulation design steps: Establish a model and use simulation software to establish a geometric model of the flow pattern carving on the inner wall of the mixing tank, set the carving depth, width and spacing, and define the material and physical properties of the agitator, tank body, flow pattern carving and liquid; Divide the mesh in the fluid domain to capture the disturbance of the fluid at the flow pattern grooves; Set the stirrer speed N, the density ρ and viscosity μ of the liquid, and the boundary conditions of the stirring tank. The geometry of the flow pattern will serve as the wall boundary conditions to affect the fluid flow. Through CFD simulation, the Navier-Stokes equations are solved, the fluid velocity field, shear stress distribution, and fluid disturbance are analyzed, and the optimal flow pattern geometry parameters are found through the flow field distribution.

8. A method for evaluating flow pattern carving performance in a multi-loop variable flow pattern mixing system, characterized in that: Evaluating the performance of the flow pattern obtained by the design method of claim 7 comprises the following steps: F1. Calculate the effect of flow pattern on shear stress: ； τ w is the wall shear stress, Pa; C f is the wall friction coefficient; ρ is the fluid density, kg / m³; v is the flow velocity in the engraved area, m / s; F2. The effect of the carving on turbulence is measured by the turbulence intensity I: ； u′ is the RMS value of velocity fluctuation; U is the average flow velocity, m / s; F3, using particle settling velocity v s Compare with the fluid flow rate to determine whether the groove depth design is appropriate: ； r is the particle radius, m; ρ p is the particle density, kg / m³; ρ is the liquid density, kg / m³; g is the acceleration due to gravity; μ is the fluid viscosity, Pa·s; F4. The overall mixing power of the mixing tank is calculated by increasing the shear stress. The total mixing power P is expressed as: ； A is the cross-sectional area, m 2 .

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