CN115231762A - Control method based on magnetic coagulation water treatment system - Google Patents
Control method based on magnetic coagulation water treatment system Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/48—Treatment of water, waste water, or sewage with magnetic or electric fields
- C02F1/488—Treatment of water, waste water, or sewage with magnetic or electric fields for separation of magnetic materials, e.g. magnetic flocculation
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F27/00—Mixers with rotary stirring devices in fixed receptacles; Kneaders
- B01F27/80—Mixers with rotary stirring devices in fixed receptacles; Kneaders with stirrers rotating about a substantially vertical axis
- B01F27/85—Mixers with rotary stirring devices in fixed receptacles; Kneaders with stirrers rotating about a substantially vertical axis with two or more stirrers on separate shafts
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F27/00—Mixers with rotary stirring devices in fixed receptacles; Kneaders
- B01F27/80—Mixers with rotary stirring devices in fixed receptacles; Kneaders with stirrers rotating about a substantially vertical axis
- B01F27/90—Mixers with rotary stirring devices in fixed receptacles; Kneaders with stirrers rotating about a substantially vertical axis with paddles or arms
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F35/00—Accessories for mixers; Auxiliary operations or auxiliary devices; Parts or details of general application
- B01F35/20—Measuring; Control or regulation
- B01F35/22—Control or regulation
- B01F35/221—Control or regulation of operational parameters, e.g. level of material in the mixer, temperature or pressure
- B01F35/2211—Amount of delivered fluid during a period
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F35/00—Accessories for mixers; Auxiliary operations or auxiliary devices; Parts or details of general application
- B01F35/20—Measuring; Control or regulation
- B01F35/22—Control or regulation
- B01F35/221—Control or regulation of operational parameters, e.g. level of material in the mixer, temperature or pressure
- B01F35/2214—Speed during the operation
- B01F35/22142—Speed of the mixing device during the operation
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F2101/00—Mixing characterised by the nature of the mixed materials or by the application field
- B01F2101/305—Treatment of water, waste water or sewage
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F2001/007—Processes including a sedimentation step
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W10/00—Technologies for wastewater treatment
- Y02W10/10—Biological treatment of water, waste water, or sewage
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- Chemical Kinetics & Catalysis (AREA)
- Analytical Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
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- Separation Of Suspended Particles By Flocculating Agents (AREA)
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Abstract
The invention relates to a control method based on a magnetic coagulation water treatment system, which comprises the following steps: step 2, calculating the optimal stirring intensity G of the mixing and stirring tank 0 And calculating the optimal rotating speed of the stirrer according to the optimal stirring intensity; step 3, in the optimal stirring intensity G 0 In the case of (2) calculating the optimum solid content range [ a, b ] of the system](ii) a Step 4, controlling the stirrer to operate at the optimal rotating speed, and monitoring the system solid content H in the mixing and stirring tank; the system solid content in the mixing and stirring tank is adjusted by changing the reflux amount of the magnetic mud, so that the system solid content H is in the optimal solid content range. Method for producing a composite materialThe design of the magnetic coagulation water treatment system is closely associated with the control process in actual operation, so that the designed magnetic coagulation water treatment system can operate in a mode most beneficial to improving the sewage treatment effect under various water quality conditions, the actual operation process can be controlled very conveniently and accurately, and the effluent is ensured to reach the standard.
Description
Technical Field
The invention relates to the technical field of magnetic coagulation water treatment, in particular to a control method based on a magnetic coagulation water treatment system.
Background
As an advanced water purification technology, the magnetic coagulation water treatment technology has the characteristics of simple process, small occupied area of equipment, large treatment capacity, strong impact load resistance, low operation cost, long service life of the equipment, stable effluent of 1 grade A or higher standard and the like, is receiving wide attention in the industry day by day, and is increasingly applied to the fields of sewage treatment plant upgrading and reconstruction, advanced wastewater dephosphorization, heavy metal wastewater treatment, black foul river treatment and the like.
The existing magnetic coagulation water treatment process is usually implemented in a magnetic coagulation water treatment system, and the magnetic coagulation water treatment usually comprises three links of magnetic medium coagulation stirring, magnetic medium precipitation and magnetic medium recovery, wherein the magnetic medium coagulation stirring link refers to a process of aggregating colloidal particles and tiny suspended matters in sewage by adding a medicament and a magnetic medium (or called magnetic particles) so as to form flocs (or called flocs) with higher density and stronger strength for subsequent rapid sedimentation; it can be decomposed into two stages of coagulation and flocculation. The magnetic medium precipitation link is used for separating suspended matters such as floccules, sludge and the like in the sewage in a gravity precipitation mode, so that the solid-liquid rapid separation is realized, the sewage is purified, and the aim of purifying the sewage is fulfilled. And in the separated magnetic mud, a part of the magnetic mud can flow back to the magnetic medium coagulation stirring link to realize sludge backflow, the rest sludge can enter the magnetic medium recovery link, and the magnetic medium recovery link is mainly used for recovering the magnetic medium in the magnetic mud, so that the magnetic medium can be recycled, and the economic efficiency is improved.
The greatest difference between the magnetic coagulation water treatment process and the traditional coagulation precipitation process is as follows: the magnetic coagulation water treatment process is a magnetic precipitation water treatment process, and needs to continuously add magnetic particles into sewage in the running process(i.e., magnetic media) without the need to add magnetic media to the wastewater as in conventional coagulative precipitation processes. On the one hand, however, the design and operation and maintenance of the equipment (especially the equipment in the magnetic medium coagulation stirring link) in the existing magnetic coagulation water treatment system still use the theoretical system of the traditional coagulation sedimentation, and neglects the key factor that the magnetic medium with large specific gravity is introduced in the process of magnetically adding sedimentation water treatment, so that the density of the formed flocs is large. On the other hand, in the magnetic coagulation water treatment system, the magnetic medium coagulation stirring link is the core of the whole system, and in order to control the sewage treatment effect, the prior art generally adopts a G value and a GT value as coagulation control indexes, wherein G represents the velocity gradient of the motion of two particles in two adjacent water layers, and means that the particle collision frequency is reflected due to the velocity difference (also called as the stirring strength) of stirring in the distance of vertical water flow; the GT value corresponds to the total number of particle collisions per unit volume of water. Because the G value is obtained when the water flow is in a laminar flow state, actually, in a flocculation stage, the water flow is not laminar flow but always in a turbulent flow state, and vortices with different sizes exist in the fluid, and besides the advancing speed, longitudinal and transverse pulsating speeds also exist, namely the G value only can represent the spatial average dissipation rate of energy and cannot reflect the dissipation rate of each local energy; GT value is too large (10) 4 ～10 5 ) The requirements can be met frequently, and the actual control significance is lost; and the G value and the GT value can only be measured in a laboratory generally and cannot be measured on line in the sewage treatment process, so that the actual operation process of the magnetic coagulation water treatment system is difficult to control through the G value and the GT value. Based on the above two reasons, the existing magnetic coagulation water treatment system is disconnected from the control in the actual operation process, so that the designed magnetic coagulation water treatment system is difficult to operate in a mode most beneficial to improving the sewage treatment effect under various water quality conditions, and a proper control index is lacked, so that the problems that the accurate control is inconvenient, and the water outlet effect cannot keep stable and high-quality water outlet along with the fluctuation of water quality exist in the actual operation process, and the urgent need to be solved is high.
Disclosure of Invention
The invention solves the problems that the existing magnetic coagulation water treatment system is disconnected from the control in the actual operation process, so that the designed magnetic coagulation water treatment system is difficult to operate in a mode most beneficial to improving the sewage treatment effect under various water quality conditions, and the actual operation process is inconvenient to control accurately, and the main conception is as follows:
a control method based on a magnetic coagulation water treatment system is applied to the magnetic coagulation water treatment system, the magnetic coagulation water treatment system comprises a coagulation device for conditioning sewage and a precipitation device for separating magnetic mud, the coagulation device is provided with a mixing and stirring tank, and a stirrer is arranged in the mixing and stirring tank; the mixing and stirring tank is communicated with the sedimentation device, and a sludge discharge port of the sedimentation device is communicated with the mixing and stirring tank and used for refluxing the magnetic sludge; the method comprises the following steps:
2. calculating the optimal stirring intensity G of the mixing and stirring tank 0 And calculating the optimal rotating speed of the stirrer according to the optimal stirring intensity;
3. at the optimum stirring intensity G 0 In the case of (2) calculating the optimum solid content range [ a, b ] of the system]；
4. Controlling the stirrer to operate at the optimal rotating speed, and monitoring the system solid content H in the mixing and stirring tank; the system solid content in the mixing and stirring tank is adjusted by changing the reflux amount of the magnetic mud, so that the system solid content H is in the optimal solid content range. In the method, the stirring strength is used as a coagulation stirring control index instead of a coagulation effect control index, so that the limitation of adopting a G value and a GT value as coagulation effect control indexes in the design and operation of the existing mixing stirring tank is solved; in the operation process of the mixing and stirring tank, the mixing intensity is not larger, the coagulation effect is better, therefore, in step 2, the optimal mixing intensity of the mixing and stirring tank is calculated based on the actual mixing and stirring tank, and the optimal rotating speed of the stirrer can be calculated according to the optimal mixing intensity in order to substantially find the optimal mixing intensity corresponding to the optimal coagulation effect of the mixing and stirring tank, so that in the actual operation process, the rotating speed of the stirrer only needs to be controlled to be the optimal rotating speed, and the optimal rotating speed of the stirrer can be in the mixing and stirring tankThe optimal coagulation effect is obtained, and by adopting the mode, the design and the operation of the mixing and stirring tank are related, and the whole system is conveniently controlled to operate in a mode which is most beneficial to improving the sewage treatment effect. Because the treatment effect of the whole system can have larger fluctuation and difference under different water quality conditions, in the method, the solid content of the system is creatively used as the control index of the coagulation effect, and the optimal stirring intensity G is achieved 0 In the case of (2) calculating the optimum solid content range [ a, b ] of the system]The system can effectively represent the coagulation effect of the whole system and is convenient to control the coagulation effect of the system by utilizing the optimal solid content range, so that the stirrer can run at the optimal rotating speed in the actual running process, and the system solid content H in the mixing and stirring tank can be synchronously monitored; when the solid content of the system exceeds the optimal solid content range [ a, b ]]During the time, can adjust the system solid content in mixing the stirring pond through changing the magnetic mud backward flow volume for system solid content H is in best solid content within range, is convenient for not only realize the accurate control of magnetism water treatment process that thoughtlessly congeals, can ensure moreover that the magnetism water treatment system that thoughtlessly congeals that designs can all be in order to improve the mode operation of sewage treatment effect under various quality of water conditions most, can show improvement play water quality of water.
In order to solve the problems associated with the design and operation of the system, the method further comprises the step 1 of determining pool shape parameters of a mixing and stirring pool in the coagulation device, and determining the size structural parameters of the stirrer according to the pool shape parameters and the design specifications, wherein the size structural parameters at least comprise the diameter of the blades, the number of the blades and the width of the blades. In this scheme, confirm earlier that mix the pond shape parameter in stirring the pond, confirm the size structure parameter of agitator through pond shape parameter, not only make the agitator more adapt mix the stirring pond, under the condition that pond shape parameter and size structure parameter all match best moreover, can also obtain best stirring intensity through the rotational speed that changes the agitator for the design of system is in the same place with the accurate relevance of operation effect.
The second aspect of the present invention is to solve the problem of calculating the optimum stirring strength of a mixing tank in a magnetic coagulation water treatment system, and further, the stepsIn step 2, a G-df fitting curve is calculated first, and the optimal stirring intensity G is obtained through the G-df fitting curve 0 And df represents a two-dimensional fractal dimension of a flocculating constituent in the sewage. Under the condition that the stirring strength is used as a coagulation stirring control index but not as a coagulation effect control index, the method further introduces the concept of 'fractal dimension' containing information such as the size, the density and the like of the flocculating constituent by analyzing a coagulation morphological theory, and the change of the concept can more accurately reflect the forming process and the rule of the flocculating constituent under certain stirring conditions as the coagulation effect control index, thereby being more beneficial to accurately calculating the optimal stirring strength of each mixing and stirring tank; meanwhile, the method utilizes the G-df fitting curve to obtain the optimal stirring strength, can avoid the interference of other factors, and is very convenient, accurate and efficient.
To solve the problem of facilitating the achievement of the optimum stirring intensity, it is preferable that the optimum stirring intensity G is calculated in step 2 0 The method comprises the following steps:
2.1, taking the rotating speed of the stirrer as a variable, inspecting the two-dimensional fractal dimension df of the flocculating constituent in the sewage under different G values by changing the rotating speed of the stirrer, and obtaining at least three groups of measurement data taking the G value as a horizontal coordinate and the df as a vertical coordinate;
2.2, marking each group of measurement data in a plane rectangular coordinate system, and obtaining a G-df fitting curve through data fitting;
2.3 obtaining the optimal stirring intensity G according to the G-df fitting curve 0 。
In order to solve the problem of calculating the optimal rotating speed of the stirrer, further, in step 2, according to the optimal stirring intensity G 0 The formula for calculating the optimum rotational speed of the agitator is:
in the formula: q t Mixing pool flow (m) 3 /s)；
The viscosity (Pa · s) of μ -water may be set to μ =1.14 × 10 in practical use -3 Pa·s；
K g The working condition coefficient of the motor in the stirrer can be 1.2 when the motor continuously runs for 24 hours every day;
eta-the total efficiency of mechanical transmission, which can be 0.92 in practical application;
c-drag coefficient, C = 0.2-0.5, and in practical application, C =0.5 may be selected;
the density of the rho-mixed liquid can be 1150kg/m in practical application 3 ；
ω -stirrer rotational speed, ω =2 × (π n/60), rad/s, n is stirrer rotational speed;
z represents the number of the stirring blades;
e-the number of layers of the stirrer, C = H/D, C > 1.3, and when the stirrer is actually applied, e =2 can be taken; c is less than or equal to 1.3, e =1, D is taken as the equivalent diameter of the cross section of the tank body, and H is the height of the tank;
b-width of stirring blade, b = (0.1-0.25) d (m), d is diameter of stirrer;
r-stirring blade radius, R = (1/6-1/3) D (m);
the mounting angle of the stirring blade is theta, and the angle can be 45 degrees in practical application;
g-acceleration of gravity, typically 9.8m/s 2 。
In order to solve the problem of conveniently measuring the two-dimensional fractal dimension of the flocculating constituent in the sewage, further, the method for measuring the two-dimensional fractal dimension df of the flocculating constituent in the sewage comprises the following steps: firstly, taking a proper amount of coagulated turbid liquid from a mixing and stirring tank on a glass slide;
measuring L and A of at least two flocculants under a microscope to obtain at least two groups of data points with lnL as a horizontal coordinate and lnA as a vertical coordinate, wherein A is a projection plane of the flocculants, and L is the maximum circumference of projection;
and finally, performing linear fitting on each group of data points, wherein the slope of the fitted linear is the two-dimensional fractal dimension df.
In order to solve the problem of calculating the optimal solid content range of the magnetic coagulation water treatment system in the third aspect of the present invention, further, in step 3, an H-df fitted curve is calculated first, and the optimal solid content range [ a, b ] is obtained through the H-df fitted curve, wherein H represents the solid content of the system. In the method, the optimal solid content range [ a, b ] of the system is calculated by an H-df fitting curve, so that the solid content H of the system and the two-dimensional fractal dimension df can be associated together, the relationship between the solid content and the coagulation effect can be intuitively and accurately reflected by using the two-dimensional fractal dimension df, and the optimal solid content range can be obtained more conveniently. And the method can be matched with the optimal stirring intensity to obtain the optimal solid content range of the system under the optimal stirring intensity condition, so that the whole system can operate in a mode most beneficial to improving the sewage treatment effect under various water quality conditions, and the effluent quality can be obviously improved.
To solve the problem of easy calculation of the optimum solid content range, preferably, the method for calculating the optimum solid content range [ a, b ] in step 3 is:
3.1 maintaining the stirring intensity of the mixing and stirring tank at G 0 Taking the system solid content H in the mixing and stirring tank as a variable, investigating the two-dimensional fractal dimension df of a flocculating constituent in sewage under the condition of the same stirring strength by changing the system solid content H in the mixing and stirring tank, and obtaining at least three groups of measurement data with H as a horizontal coordinate and df as a vertical coordinate;
3.2, marking each group of measurement data in a plane rectangular coordinate system, and obtaining an H-df fitting curve through data fitting;
3.3, obtaining the optimal solid content range [ a, b ] of the system according to the H-df fitting curve.
Preferably, in step 3.3, the method for calculating the lower limit a of the optimum solid content is as follows: setting a two-dimensional fractal dimension lower limit df0, and calculating the corresponding system solid content H by using a fitting formula corresponding to an H-df fitting curve or an H-df fitting curve 0 And let a = H 0 ；
And/or the method for calculating the upper limit b of the optimal solid content is as follows: setting two-dimensional fractal dimension upper limit df1, and calculating corresponding system solid content H by using a fitting formula corresponding to an H-df fitting curve or an H-df fitting curve 1 And let b = H 1 。
Preferably, the lower fractal dimension limit df0=2; and/or, the upper fractal dimension limit df1=3.
In order to solve the problem of convenience in measuring multiple groups of measurement data, further, in step 3.1, the system solid content H in the mixing and stirring pool is changed by changing the reflux amount of the magnetic mud. The solid content H of the system in the mixing and stirring tank is changed in such a way, so that the operation is simple and convenient, and a group of measurement data can be measured under the working condition of each solid content H of the system, so that a plurality of groups of measurement data can be conveniently obtained, and an H-df fitting curve can be conveniently calculated.
In order to solve the problem of accurately controlling the return flow of the magnetic sludge on line in the operation process of the magnetic coagulation water treatment system, the magnetic coagulation water treatment system is further provided with a controller, a sensor and a flow control device, wherein the controller is electrically connected with the sensor, the stirrer and the flow control device respectively, and the flow control device is arranged on a communication path between the sludge discharge port and the coagulation device;
in the step 4, the stirrer is controlled by the controller to operate at the optimal rotating speed, and the solid content H of the system in the mixing and stirring tank is monitored by the sensor; when the solid content H of the system is larger than the upper limit b of the optimal solid content, the controller reduces the reflux amount of the magnetic mud by controlling the flow control device, so that the solid content of the system in the mixing and stirring tank is reduced, and the solid content H of the system is in the optimal solid content range; when the solid content H of the system is smaller than the lower limit a of the optimal solid content, the controller controls the flow control device to improve the reflux amount of the magnetic mud, so that the solid content of the system in the mixing and stirring pool is increased, and the solid content H of the system is in the optimal solid content range. The scheme detects and controls the solid content of the system, so that the system can operate in the optimal solid content range under any water quality condition, and the effluent quality can be ensured to reach the standard.
Preferably, the flow control device adopts a control valve. The controller valve comprises a two-way control valve, a three-way control valve and the like.
Preferably, the controller is a PC, a singlechip or a PLC.
Preferably, the sensor is an online suspended matter monitor.
Compared with the prior art, the control method based on the magnetic coagulation water treatment system provided by the invention has the advantages that the stirring strength is used as a coagulation stirring control index instead of a coagulation effect control index, the system solid content is used as a coagulation effect control index, the optimal solid content range of the system is matched, and the design of the magnetic coagulation water treatment system is closely related to the control process in actual operation, so that the designed magnetic coagulation water treatment system can operate in a mode most beneficial to improving the sewage treatment effect under various water quality conditions, the actual operation process is very convenient to accurately control, and the effluent is ensured to reach the standard.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
Fig. 1 is a block diagram of a control method based on a magnetic coagulation water treatment system provided in an embodiment of the present invention.
Fig. 2 is a schematic structural diagram of a first magnetic coagulation water treatment system provided in an embodiment of the present invention.
Fig. 3 is a schematic structural diagram of a second magnetic coagulation water treatment system provided in an embodiment of the present invention.
Fig. 4 is a schematic structural diagram of a third magnetic coagulation water treatment system provided in an embodiment of the present invention.
FIG. 5 is a graph of a G-df fit obtained using the control method provided by the present invention.
FIG. 6 is another graph of a G-df fit obtained using the control method provided by the present invention.
FIG. 7 is a graph of an H-df fit obtained using the control method provided by the present invention.
Description of the drawings
The coagulation device 200, a first mixing and stirring tank 201, a second mixing and stirring tank 202, a third mixing and stirring tank 203, a sensor 204, a stirrer 205, a baffle plate 206 and a guide cylinder 207
A sedimentation device 300, a sedimentation cavity 301, an inclined pipe 302, a reflux pump 303, a flow control device 304, a magnetic sludge pump 305, an excess sludge pump 306, a pipeline 307 and a stirring mechanism 308
The magnetic recovery device 400.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
The embodiment provides a control method based on a magnetic coagulation water treatment system, wherein,
as shown in fig. 2, the magnetic coagulation water treatment system includes a PAC production apparatus 101, a PAM production apparatus 103, a coagulation apparatus 200 for conditioning sewage, a precipitation apparatus 300 for separating magnetic sludge, a magnetic recovery apparatus 400, and a controller, wherein,
as shown in fig. 2, the coagulation apparatus 200 is constructed with a mixing and stirring tank to provide a space for the coagulation process and the flocculation process of the sewage, and a stirrer 205 is provided in the mixing and stirring tank to enhance the stirring strength. In practice, the number of mixing tanks constructed in the coagulation device 200 may be determined according to actual requirements, and preferably, at least two mixing tanks communicating with each other may be constructed in the coagulation device 200. For example, as shown in fig. 2, three mixing and stirring tanks are constructed in the coagulation apparatus 200, and the coagulation apparatus 200 is provided with a water inlet and a water outlet, which are respectively communicated with the mixing and stirring tanks located at the ends. For convenience of description, the three mixing and stirring tanks are respectively a first mixing and stirring tank 201, a second mixing and stirring tank 202 and a third mixing and stirring tank 203, the first mixing and stirring tank 201, the second mixing and stirring tank 202 and the third mixing and stirring tank 203 are sequentially communicated with each other, as shown in fig. 2, a water inlet is communicated with the first mixing and stirring tank 201, a water outlet is communicated with the third mixing and stirring tank 203, and a stirrer 205 may be disposed in the first mixing and stirring tank 201, and the stirrer 205 is mainly used for enhancing the stirring intensity in the first mixing and stirring tank 201, as shown in fig. 4; several static baffles 206 may also be provided, as shown in fig. 2 or fig. 3, the static baffles 206 are mainly used to make the flow path of the sewage more tortuous, so that the coagulant and the sewage can be sufficiently mixed in the first mixing stirring tank 201. An agitator 205 is arranged in the second mixing and stirring tank 202, and the added magnetic medium and the refluxed magnetic mud are generally added into the second mixing and stirring tank 202, as shown in fig. 2-4. A stirrer 205 is arranged in the third mixing and stirring tank 203, so that the sewage can be fully mixed with the added coagulant aid and can react.
In the present embodiment, the PAC preparation apparatus 101 is in communication with the water inlet, and as shown in fig. 2, the PAC preparation apparatus 101 is mainly used for preparing a medicament, such as a coagulant. In practice, PAC preparation apparatus 101 is further provided with a PAC metering pump 102 in communication with the water inlet, so that output of the medicament can be precisely controlled by PAC metering pump 102. As shown in fig. 2, the PAM preparation apparatus 103 may be in communication with the third mixing and stirring tank 203 through a pipe 307, so as to add the prepared coagulant aid into the third mixing and stirring tank 203, and similarly, in implementation, a PAM metering pump 104 is further disposed on a communication path between the PAM preparation apparatus 103 and the third mixing and stirring tank 203, so as to precisely control the output of the medicine by using the PAM metering pump 104.
In this embodiment, the sedimentation device 300 may be an existing sedimentation tank, and the sedimentation device 300 may implement separation of magnetic sludge from the water body in the sewage by using a sedimentation method. For example, as shown in fig. 2, the sedimentation device 300 is configured with a sedimentation chamber 301, a sludge discharge port and a water outlet, wherein the sludge discharge port and the water outlet are respectively communicated with the sedimentation chamber 301, the water discharge port of the coagulation device 200 is communicated with the sedimentation chamber 301 of the sedimentation device 300, and an inclined pipe 302 (or an inclined plate) for enhancing sedimentation, a stirring mechanism 308 (including a motor, a transmission shaft for driving and connecting the motor, a hanger mounted on the transmission shaft, etc.) and the like are generally arranged in the sedimentation chamber 301, as shown in fig. 2, and will not be described herein again. In the actual operation process, sewage is precipitated in the precipitation cavity 301 of the precipitation device 300, the precipitated magnetic mud is discharged out of the precipitation device 300 through the mud discharge port, and clear water after the magnetic mud is separated is discharged out through the water outlet.
In this embodiment, the magnetic recycling device 400 is mainly used for recycling the magnetic medium in the magnetic mud, and an existing magnetic disc type magnetic separator or a drum type magnetic separator or the like may be used to separate the magnetic medium from the mud in the magnetic mud by using the principle of magnetic adsorption. When the magnetic recovery device 400 is assembled, the magnetic recovery device is communicated with a sludge discharge port of the sedimentation device 300 so as to receive and separate magnetic media in magnetic sludge; the magnetic recycling device 400 is further communicated with the coagulation device 200, for example, as shown in fig. 2, the magnetic recycling device 400 is communicated with the second mixing and stirring tank 202 of the coagulation device 200, so that at least part of the recycled magnetic medium is thrown into the second mixing and stirring tank 202 to realize recycling of the magnetic medium.
In this embodiment, the coagulation device 200 is also connected to the sludge discharge port of the sedimentation device 300 to return the magnetic sludge, as shown in fig. 2. Because the magnetic recovery device 400 and the coagulation device 200 are respectively communicated with the sludge discharge port of the sedimentation device 300, the requirement of magnetic sludge backflow is met firstly during operation, and the residual sludge (called residual sludge for short) enters the magnetic recovery device 400. In order to shunt the magnetic sludge, various embodiments are provided, and in this embodiment, for example, a reflux pump 303 and a flow control device 304 for controlling the reflux amount are disposed on a communication path between the sludge discharge port of the settling device 300 and the coagulation device 200. In practice, the flow control device 304 may be a control valve, which may be a two-way control valve, a three-way control valve, etc. commonly used in the art, and in this embodiment, the flow control device 304 is a solenoid valve, for example. Of course, in a more sophisticated scheme, in order to monitor the backflow amount of the magnetic mud, a flow meter can be further disposed on the communication path between the mud discharge port of the sedimentation device 300 and the coagulation device 200. Meanwhile, an excess sludge pump 306 is disposed on a communication path between the magnetic recovery device 400 and the sedimentation device 300 so that excess magnetic sludge is input into the magnetic recovery device 400 by the excess sludge pump 306, as shown in fig. 2. In practice, the sludge discharge port and the coagulation device 200 may be communicated through a pipe 307 or a channel, and similarly, the sludge discharge port and the magnetic recovery device 400 may also be communicated through a pipe 307 or a channel.
In the actual operation process, the sewage enters the first mixing and stirring tank 201 of the coagulation device 200 through the water inlet, and is fully mixed with the coagulant in the first mixing and stirring tank 201; then, the sewage enters a second mixing and stirring tank 202, and under the action of a stirrer 205, the magnetic medium, the backflow magnetic mud and the sewage are fully mixed in the second mixing and stirring tank 202; then the sewage enters a third mixing and stirring tank 203, and is fully mixed with a coagulant in the third mixing and stirring tank 203, then enters the sedimentation device 300 through a water outlet, and is precipitated in the sedimentation device 300, the separated clear water is discharged through a water outlet of the sedimentation device 300, the precipitated magnetic mud is conveyed backwards through a mud outlet of the sedimentation device 300, and can flow part of the magnetic mud back to the coagulation device 200 according to the requirement, the residual mud is input into a magnetic recovery device 400 for recovering the magnetic medium, and the recovered magnetic medium can be conveyed into the coagulation device 200, so as to realize the recycling of the magnetic medium.
Based on the magnetic coagulation water treatment system with the structure, in order to make the design of the magnetic coagulation water treatment system and the control in the actual operation process closely related to each other, as shown in fig. 1, the control method provided by the embodiment comprises the following steps:
A＝αL df
in the formula: a-is a projection surface of the flocculating constituent;
l-is the maximum circumference of the projection;
alpha-is a proportionality constant;
df-is the two-dimensional fractal dimension of the floccule.
And solving the natural logarithm of the formula to obtain:
lnA＝lnα+dflnL
as can be seen from the above formula, lnL and lnA are in a linear relationship, and therefore, in this embodiment, the method for measuring the two-dimensional fractal dimension of the flocs in the sewage is as follows: firstly, taking out a proper amount of turbid liquid coagulated in the mixing and stirring tank by using a tripe pipette, and placing the turbid liquid on a glass slide; observing under a microscope, carrying out image processing on an electronic computer connected with an electronic microscope camera lens and a video image catcher, measuring L and A of different flocculi (at least two), and respectively calculating lnL and lnA, thereby obtaining at least two groups of data points with lnL as a horizontal coordinate and lnA as a vertical coordinate; and finally, performing straight line fitting on each group of data points by using data processing software (such as Excel, SPSS, MATLAB and the like), wherein the slope of the fitted straight line is the two-dimensional fractal dimension df of the flocculent in the sewage. In actual operation, in order to improve accuracy, at least two times of measurement can be carried out so as to obtain at least two fractal dimensions, and finally, the average value of the two fractal dimensions is obtained to be used as the final two fractal dimension df, so that the precision can be obviously improved, and the error can be obviously reduced.
For calculating the optimal stirring intensity G of a mixing and stirring tank in the magnetic coagulation water treatment system 0 In a preferred embodiment, in the step 2, a G-df fitting curve is first calculated, as shown in FIG. 5 and FIG. 6, and then the optimal stirring intensity G is calculated by the G-df fitting curve 0 And df represents a two-dimensional fractal dimension of a flocculating constituent in the sewage. For example, the optimum stirring intensity G is calculated in step 2 0 The method of (a) may comprise:
and 2.1, taking the rotating speed of the stirrer 205 as a variable, observing the two-dimensional fractal dimension df of the floccules in the sewage under different G values by changing the rotating speed of the stirrer 205, and obtaining at least three groups of measurement data with the G value as an abscissa and the df as an ordinate. Specifically, when the magnetic coagulation water treatment system is in operation, different stirring strengths G can be obtained by changing the rotation speed of the stirrer 205, and after each stirring strength G is stabilized, the two-dimensional fractal dimension df corresponding to the stirring strength G can be measured by using the method for measuring the two-dimensional fractal dimension, so that a set of measurement data can be obtained, and the above process can be repeated for 5 to 8 times, so as to obtain 5 to 8 sets of measurement data, as shown in fig. 5 and 6.
And 2.2, marking each group of measurement data in a plane rectangular coordinate system, and obtaining a G-df fitting curve through data fitting. In this step, the data fitting process may be calculated by using existing data processing software, or may be calculated manually by using an existing mathematical formula, which is not described herein again, for example, as shown in fig. 5, a G-df fitting curve is obtained under the condition that only the stirrer 205 is arranged in the first mixing and stirring tank 201, and the guide cylinder 207 is not arranged; as shown in fig. 6, the G-df fit curve is obtained in the case where the stirrer 205 is provided in the first mixing/stirring tank 201 and the guide cylinder 207 is provided.
2.3 obtaining the optimal stirring intensity G according to the G-df fitting curve 0 . In practice, a G-df fit curve can be plotted, as shown in FIG. 5 or FIG. 6, and the highest point is found on the graph, and the abscissa corresponding to the highest point is the optimal stirring intensity G 0 Of course, the best stirring intensity G can be obtained by directly calculating the abscissa corresponding to the maximum value by using a formula of a G-df fitting curve 0 . As shown in FIGS. 5 and 6, the optimum stirring intensity G of the magnetic coagulation water treatment system was obtained 0 Is 270s -1 。
When the optimum stirring intensity G 0 Once determined, the optimum stirring intensity G can be used 0 Calculating the optimum rotation speed of the agitator 205, specifically, according to the optimum agitation intensity G 0 The formula for calculating the optimal rotational speed of the agitator 205 is:
in the formula: q t Mixing pool flow (m) 3 /s)；
The viscosity (Pa · s) of μ -water may be set to μ =1.14 × 10 in practical use -3 Pa·s；
K g The working condition coefficient of the motor in the stirrer 205 can be 1.2 when the motor continuously runs for 24 hours every day;
eta-the total efficiency of mechanical transmission, which can be 0.92 in practical application;
c-drag coefficient, C = 0.2-0.5, and in practical application, C =0.5 may be selected;
the density of the rho-mixed liquid can be 1150kg/m in practical application 3 ；
ω -stirrer 205 rotational speed, ω =2 × (π n/60), rad/s, n is stirrer rotational speed;
z-number of stirring blades;
e-the number of layers of the stirrer 205, C = H/D, C > 1.3, and when the stirrer is actually applied, e =2 can be adopted; c is less than or equal to 1.3, e =1, D is the equivalent diameter of the cross section of the tank body, and H is the height of the tank;
b-stirring blade width, b = (0.1-0.25) d (m), d is the diameter of the stirrer 205;
r-stirring paddle radius, R = (1/6-1/3) D (m);
the mounting angle of the stirring blade is theta, and the angle can be 45 degrees in practical application;
g-gravitational acceleration, which may be generally 9.8m/s 2 。
It is understood that when the coagulation apparatus 200 includes a plurality of mixing tanks each provided with the stirrer 205, the optimum stirring intensity G of each mixing tank can be calculated in step 2 0 And an optimum rotational speed of each agitator 205, such that each agitator 205 operates at its respective optimum rotational speed during actual operation.
Step 3, stirring at the optimal stirring intensity G 0 In the case of (2) calculating the optimum solid content range [ a, b ] of the system]So as to optimize the solid content range [ a, b ]]The actual solid content of the system is controlled for reference, thereby achieving the purpose of effectively controlling the whole process. To facilitate calculation of the optimal solids content range for a magnetic coagulation water treatment system, in a preferred embodiment, an H-df fit curve is calculated, as shown in FIG. 7, and then the optimal solids content range [ a, b ] is obtained by the H-df fit curve]Wherein H represents the system solids content (which may also be referred to as suspended matter concentration, referring to the concentration of suspended matter in the water body, including suspended sludge, magnetic media, flocculants, etc.). Specifically, the optimal solid content range [ a, b ] is calculated in step 3]The method comprises the following steps:
3.1 controlling the rotation speed of the stirrer 205 to keep the stirring intensity of the mixing and stirring tank at G 0 I.e. so that the mixing and stirring tank has a stirring intensity G which is always at its optimum 0 Status. Meanwhile, the system solid content H in the mixing and stirring tank is used as a variable, the two-dimensional fractal dimension df of the flocculating constituent in the sewage under the condition of the same stirring strength is investigated by changing the system solid content H in the mixing and stirring tank, and at least three groups of measurement data with H as a horizontal coordinate and df as a vertical coordinate can be obtained. Specifically, the rotation speed of the stirrer 205 is first maintained so that the stirring intensity of the mixing and stirring tank is kept at G 0 To obtain the best stirring effect. Then changing the solid content H of the system in the mixing and stirring tank, sampling from the second mixing and stirring tank 202 or the third mixing and stirring tank 203 after the system is stable, and measuring the two-dimensional fractal dimension of the flocculating constituent in the sewage by using the method for measuring the two-dimensional fractal dimension of the flocculating constituent in the sewageThe system contains the two-dimensional fractal dimension df corresponding to the solid content H, so that one set of data can be obtained, and in this way, a plurality of sets of measurement data can be obtained, as shown in fig. 7, and in a preferred embodiment, 5-8 sets of measurement data can be obtained.
In the test process, in order to change the system solid content H in the mixing and stirring tank, various embodiments are provided, for example, sewage with different water qualities can be introduced into the system to achieve the purpose of changing the system solid content H in the mixing and stirring tank, but the problem of troublesome operation exists. In a preferred embodiment, the system solid content H in the mixing and stirring tank can be changed by changing the magnetic mud reflux amount under the condition that the quality of the sewage entering the system is not changed, for example, the system solid content H =2000mg/L in the current mixing and stirring tank, after the current two-dimensional fractal dimension df is measured, the magnetic mud reflux amount of the system can be increased, so that the system solid content H of the whole system can be increased to 3000mg/L and kept at the position of 3000mg/L, so as to measure the two-dimensional fractal dimension df at the moment, and then the system solid content H of the whole system can be increased to 4000mg/L, 5000mg/L, 6000mg/L, 7000mg/L and the like by increasing the magnetic mud reflux amount, as shown in fig. 7, so that a plurality of groups of measurement data can be conveniently and efficiently obtained, and the H-df curve fitting can be more conveniently calculated.
And 3.2, marking each group of measurement data in a plane rectangular coordinate system, and obtaining an H-df fitting curve through data fitting, thereby being very convenient. Similarly, in this step, the data fitting process may be calculated by using existing data processing software, or may be calculated manually by using an existing mathematical formula, which is not described herein again, for example, as shown in fig. 7, the fitting process is an H-df fitting curve obtained by using the water sample in the second mixing and stirring tank 202.
3.3 obtaining the optimal solid content range [ a, b ] of the system according to the H-df fitting curve]. Specifically, in one embodiment, the method for calculating the optimal lower limit a of solid content is: setting a two-dimensional fractal dimension lower limit df0, and calculating the corresponding system solid content H by using a fitting formula corresponding to an H-df fitting curve or an H-df fitting curve 0 And let a = H 0 . Similarly, calculate the bestThe method of the upper limit b of the solid content is as follows: setting two-dimensional fractal dimension upper limit df1, and calculating corresponding system solid content H by using a fitting formula corresponding to an H-df fitting curve or an H-df fitting curve 1 And let b = H 1 Thus, the method is very convenient. In implementation, a lower limit df0 of the two-dimensional fractal dimension and an upper limit df1 of the two-dimensional fractal dimension may be determined according to actual requirements, and preferably, the lower limit of the two-dimensional fractal dimension may be set to df0=2; and/or, an upper limit of the fractal dimension may be set to df1=3.
The solid content of the system is a crucial influence factor for the magnetic-based synergistic water treatment technology, and the optimal solid content range of any magnetic coagulation water treatment system can be effectively determined by adopting the method, for example, as shown in the figure, the solid content range is an H-df fitting curve of the magnetic coagulation water treatment system, and as can be seen from FIG. 7: the solid content of the system in the system is less than 3000mg/L, the df value is less than 2, the coagulation effect is poor, and most of the coagulation effect is fine floccules, the reason for the coagulation effect is that the particle collision probability is low in the coagulation process, which is not beneficial to the coagulation among particles and the growth of particles, and the fine floccules are easily carried out by the overflow effluent of the sedimentation cavity 301, so that the effluent quality is influenced. When the solid content of the system is higher than 6000mg/L, the coagulation effect also tends to be poor, the solid content of the sedimentation cavity 301 is higher, the outlet water of the sedimentation cavity 301 runs out of flocs, the quality of the outlet water is influenced, and the impact resistance of the system is reduced. The reason for this is probably that when the solid content of the system is too high, the formed flocs are too much, and then the hydraulic action is influenced, so that part of the flocs have a descending trend, and the flocs which have an ascending trend are collided and broken up in the process. In conclusion, in the embodiment, the system solid content in the magnetic coagulation water treatment system is preferably controlled to be 3000-6000 mg/L, and the best effect can be obtained.
And 4, controlling the stirrer 205 to operate at the optimal rotating speed to obtain the optimal stirring effect, monitoring the system solid content H in the mixing and stirring tank, wherein the system solid content H in the second mixing and stirring tank 202 is generally equal to the system solid content H in the third mixing and stirring tank 203 because the materials in the second mixing and stirring tank 202 and the third mixing and stirring tank 203 are balanced, and monitoring the system solid content H in the final-stage mixing and stirring tank (the third mixing and stirring tank 203 in the embodiment) in actual operation. In the operation process, when the system solid content H in the mixing and stirring tank fluctuates, the system solid content in the mixing and stirring tank can be adjusted by changing the magnetic mud reflux amount, so that the system solid content H is in the optimal solid content range, and the whole system can operate in a state which is most favorable for improving the sewage treatment effect.
In an application scenario of the method, a worker may obtain the current system solid content H of the system by periodically and manually monitoring the system solid content H in the mixing and stirring tank, and may compare the current system solid content H of the system with the optimal solid content range of the system, and when the current system solid content H of the system is found to be greater than the optimal solid content upper limit b, the worker may manually adjust the flow control device 304 to reduce the backflow amount of the magnetic sludge, and at this time, the flow control device 304 may adopt a manual valve. Similarly, when the current system solid content H of the system is found to be less than the optimal solid content lower limit a, the worker can manually adjust the flow control device 304 to increase the reflux amount of the magnetic mud, so that the system can always keep continuous operation in a mode most beneficial to improving the sewage treatment effect, and the system is particularly suitable for occasions with small sewage quality fluctuation.
In another application scenario of the method, in order to accurately control the return flow of the magnetic cement during the operation of the magnetic coagulation water treatment system, further, the magnetic coagulation water treatment system is further provided with a controller and a sensor 204, the controller is electrically connected with the sensor 204, the stirrer 205 and the flow control device 304 respectively, and the sensor 204 is used for monitoring the system solid content H in the mixing and stirring tank and sending the system solid content H to the controller, as shown in fig. 2 to 4. The controller may control the amount of return of the magnetic slurry by controlling the flow control device 304, and in this case, the flow control device 304 may preferably employ an electric controller valve, a solenoid valve, a pneumatic valve, or the like. The controller can not only control the rotating speed of the stirrer 205, but also store the optimal solid content range [ a, b ] (can be stored in the controller or a storage device connected with the controller) of the system in advance, so that the controller can be used for controlling the rotating speed of the stirrer 205 in the actual operation process of the system, the stirrer 205 is ensured to operate at the optimal rotating speed, and the sensor 204 can be used for monitoring the system solid content H in the mixing and stirring pool so as to be compared with the optimal solid content range of the system; when the solid content H of the system is larger than the upper limit b of the optimal solid content, the controller can reduce the reflux amount of the magnetic mud through the flow control device 304, so that the solid content of the system in the mixing and stirring tank is reduced, and the solid content H of the system is in the optimal solid content range; when the solid content H of the system is less than the lower limit a of the optimal solid content, the controller can increase the reflux amount of the magnetic mud through the flow control device 304, so that the solid content of the system in the mixing and stirring tank is increased, and the solid content H of the system is in the optimal solid content range.
In implementation, the controller may preferably be a PC, a single chip, or a PLC, or the like, and of course, the controller may also be a DSP, an embedded chip, or the like. The sensor 204 may preferably be an online suspended matter monitor (or called online suspended matter monitor), and for example, an SIN-PSS100 suspended matter analyzer, a ZWYG-2088T online sludge concentration meter, a ZWYG-2087A suspended matter online analyzer, or the like may be used. Of course, a turbidity meter and the like can be adopted, and only the concentration of suspended matters in the sewage can be monitored.
Example 2
The main difference between the embodiment 2 and the above embodiment 1 is that in the magnetic coagulation water treatment system provided in this embodiment, only one magnetic mud pump 305 may be disposed downstream of the mud discharge port of the sedimentation device 300, specifically, as shown in fig. 3 or fig. 4, the mud discharge port of the sedimentation device 300 is communicated with the magnetic mud pump 305, the magnetic mud pump 305 is communicated with the flow control device 304, the flow control device 304 is respectively communicated with the coagulation device 200 and the magnetic recovery device 400, and the controller is electrically connected with the flow control device 304 for distributing the backflow amount of the magnetic mud under the control of the controller. The purpose of accurately controlling the return flow of the magnetic mud is achieved. Because the coagulation device 200 and the magnetic recovery device 400 are respectively communicated with the sludge discharge port of the sedimentation device 300 through the flow control device 304, the flow control device 304 is configured with an input end and two output ends, wherein the magnetic sludge pump 305 is communicated with the input end, and the two output ends are respectively communicated with the coagulation device 200 and the magnetic recovery device 400.
The control method based on the magnetic coagulation water treatment system is the same as that in the embodiment 1, and the details are not repeated.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily think of the changes or substitutions within the technical scope of the present invention, and shall cover the scope of the present invention.
Claims (10)
1. A control method based on a magnetic coagulation water treatment system is characterized in that the magnetic coagulation water treatment system comprises a coagulation device for conditioning sewage and a precipitation device for separating magnetic mud, wherein the coagulation device is provided with a mixing and stirring tank, and a stirrer is arranged in the mixing and stirring tank; the mixing and stirring tank is communicated with the sedimentation device, and a sludge discharge port of the sedimentation device is communicated with the mixing and stirring tank and used for refluxing the magnetic sludge; the method comprises the following steps:
step 2, calculating the optimal stirring intensity G of the mixing and stirring tank 0 And calculating the optimal rotating speed of the stirrer according to the optimal stirring intensity;
step 3, in the optimal stirring intensity G 0 In the case of (2) calculating the optimum solid content range [ a, b ] of the system]；
Step 4, controlling the stirrer to operate at the optimal rotating speed, and monitoring the system solid content H in the mixing and stirring tank; the system solid content in the mixing and stirring tank is adjusted by changing the reflux amount of the magnetic mud, so that the system solid content H is in the optimal solid content range.
2. The control method of the magnetic coagulation-based water treatment system according to claim 1, further comprising the steps of 1, determining pool shape parameters of a mixing and stirring pool in the coagulation device, and determining size and structure parameters of the stirrer according to the pool shape parameters and design specifications, wherein the size and structure parameters at least comprise the diameter of the blades, the number of the blades and the width of the blades.
3. The control method of claim 1, wherein in step 2, a G-df fitting curve is calculated, and the optimal stirring intensity G is obtained by the G-df fitting curve 0 And df represents a two-dimensional fractal dimension of a flocculating constituent in the sewage.
4. The control method of claim 3, wherein the optimal stirring intensity G is calculated in step 2 0 The method comprises the following steps:
step 2.1, taking the rotating speed of the stirrer as a variable, inspecting the two-dimensional fractal dimension df of the flocculating constituent in the sewage under different G values by changing the rotating speed of the stirrer, and obtaining at least three groups of measurement data taking the G value as a horizontal coordinate and the df as a vertical coordinate;
step 2.2, marking each group of measured data in a plane rectangular coordinate system, and obtaining a G-df fitting curve through data fitting;
step 2.3, obtaining the optimal stirring intensity G according to the G-df fitting curve 0 。
5. The control method of claim 1 to 4, wherein in the step 3, an H-df fitted curve is calculated, and an optimal solid content range [ a, b ] is obtained by the H-df fitted curve, wherein H represents the solid content of the system, and df represents the two-dimensional fractal dimension of the flocculent in the sewage.
6. The control method of claim 5, wherein the method for calculating the optimal solid content range [ a, b ] in step 3 comprises:
step 3.1, maintaining the stirring intensity of the mixing and stirring tankIs G 0 Taking the system solid content H in the mixing and stirring tank as a variable, investigating the two-dimensional fractal dimension df of a flocculating constituent in sewage under the condition of the same stirring strength by changing the system solid content H in the mixing and stirring tank, and obtaining at least three groups of measurement data with H as a horizontal coordinate and df as a vertical coordinate;
step 3.2, marking each group of measurement data in a plane rectangular coordinate system, and obtaining an H-df fitting curve through data fitting;
and 3.3, obtaining the optimal solid content range [ a, b ] of the system according to the H-df fitting curve.
7. The control method of claim 6, wherein in step 3.3, the method for calculating the lower limit a of the optimal solid content is as follows: setting a two-dimensional fractal dimension lower limit df0, and calculating the corresponding system solid content H by using a fitting formula corresponding to an H-df fitting curve or an H-df fitting curve 0 And let a = H 0 ；
And/or the method for calculating the optimal solid content upper limit b is as follows: setting two-dimensional fractal dimension upper limit df1, and calculating corresponding system solid content H by using a fitting formula corresponding to an H-df fitting curve or an H-df fitting curve 1 And let b = H 1 。
8. The control method of claim 5, wherein the magnetic coagulation water treatment system is further provided with a controller, a sensor and a flow control device, the controller is electrically connected with the sensor, the stirrer and the flow control device, and the flow control device is arranged on a communication path between the sludge discharge port and the coagulation device;
in the step 4, the stirrer is controlled by the controller to operate at the optimal rotating speed, and the solid content H of the system in the mixing and stirring tank is monitored by the sensor; when the solid content H of the system is larger than the upper limit b of the optimal solid content, the controller reduces the reflux amount of the magnetic mud by controlling the flow control device so as to reduce the solid content of the system in the mixing and stirring tank and ensure that the solid content H of the system is in the optimal solid content range; when the solid content H of the system is less than the lower limit a of the optimal solid content, the controller increases the reflux quantity of the magnetic mud by controlling the flow control device so as to increase the solid content of the system in the mixing and stirring tank and ensure that the solid content H of the system is in the optimal solid content range.
9. The control method of claim 8, wherein the flow control device is a control valve;
and/or the controller is a PC, a singlechip or a PLC;
and/or the sensor adopts an online suspended matter monitor.
10. The control method based on the magnetic coagulation water treatment system as claimed in claim 5, wherein the method for measuring the two-dimensional fractal dimension df of the flocculent in the sewage is as follows: firstly, taking a proper amount of coagulated turbid liquid from a mixing and stirring tank on a glass slide;
measuring L and A of at least two flocculants under a microscope to obtain at least two groups of data points with lnL as a horizontal coordinate and lnA as a vertical coordinate, wherein A is a projection plane of the flocculants, and L is the maximum circumference of projection;
and finally, performing linear fitting on each group of data points, wherein the slope of the fitted linear is the two-dimensional fractal dimension df.
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| KR20140042975A (en) * | 2012-09-28 | 2014-04-08 | (주)비드앤마이크로 | Method and apparatus for high-rate coagulative precipitation using polymer beads containing magnetic material |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117463237A (en) * | 2023-12-27 | 2024-01-30 | 河北建投水务投资有限公司 | Coagulation stirring control method and device, stirrer controller and storage medium |
| CN117463237B (en) * | 2023-12-27 | 2024-03-12 | 河北建投水务投资有限公司 | Coagulation stirring control method and device, stirrer controller and storage medium |
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| CN115231762B (en) | 2024-01-16 |
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