A flotation multi-point reagent addition system and method based on feedforward control

Abstract

The present invention discloses a flotation multi-point reagent adding system and method based on feedforward control, the adding system comprising: a reagent barrel; a multi-stage centrifugal pump and a mechanical diaphragm pump, the multi-stage centrifugal pump and the mechanical diaphragm pump being connected in parallel and forming a first common node and a second common node at their two ends respectively, the first common node being connected to the reagent barrel, wherein the multi-stage centrifugal pump is configured to pump the reagent from the first common node to the second common node, and the mechanical diaphragm pump is configured to generate negative pressure and simultaneously pressurize the reagent; a pressure-maintaining tank having an input end and an output end, the input end being connected to the second common node, and being configured to store the reagent input via the input end and output a stable reagent via the output end; a plurality of dosing assemblies, the plurality of dosing assemblies being connected in parallel and connected to the output end, wherein each of the dosing assemblies comprises an electric needle valve.

Description

Technical Field

[0001] The present invention relates to the field of coal slime flotation reagent adding equipment, and in particular to a flotation multi-point reagent adding system and method based on feedforward control. Background Art

[0002] Flotation is currently the most widely used and effective coal preparation method. Based on the surface characteristics of the minerals—that is, the interactions of the minerals with water, bubbles, and reagents—and through the use of reagents and mechanical adjustments, flotation can flexibly and efficiently separate useful minerals from undesirable gangue minerals. The method, accuracy, and dosage of flotation reagents directly impact production indicators and profitability.

[0003] Coal preparation plants often rely on manual control of flotation reagent dosage. The most important operation is to adjust the flotation reagent dosage based on on-site conditions to achieve the required clean coal grade for flotation production. Most coal preparation plants use gravity-based flotation dosing, relying on manual visual measurement of reagent usage. This can lead to inaccuracies, high reagent consumption, and frequent fluctuations in ash content. The labor intensity is high, leading to fatigue and poor flotation results. Furthermore, this extensive manual dosing method does not meet the current automation and intelligent requirements of coal preparation plants.

[0004] The flotation dosing process involves adding reagents in the pulp preparation device and each chamber of the flotation machine, so it is necessary to control the flow rate of multi-point reagents. Currently, multi-point automatic dosing often first emulsifies the reagent with water, and then achieves flow control through conventional water supply flow distribution. This method can achieve better control effects by controlling the opening of each valve. However, the current reagent emulsification stability is poor, and the emulsification situation worsens with the increase of the length of the conveying pipeline. There is often an imbalance between the overall liquid volume and the reagent dosage between each dosing point. However, due to the small flow rate of directly adding flotation reagents and the difficulty in controlling the viscosity of the reagent flow, there is currently no effective small flow multi-point flotation direct dosing mechanism. Currently, metering and peristaltic pumps are the primary low-flow pumps commonly used both domestically and internationally. Metering pumps are expensive and produce pulsed flow. The viscosity of the medium can prevent the return valve ball from resetting in time, resulting in varying degrees of backflow. This results in low precision control of low-flow rates. They often rely on a single metering pump and single instrument design, making it difficult to maintain dosing accuracy over a wide range and often lacking troubleshooting methods such as flow rate verification. While peristaltic pumps can achieve stable control of small amounts of reagents, they suffer from the short lifespan of peristaltic hoses for highly corrosive flotation reagents and are unsuitable for the 10-hour-plus continuous operation required in coal preparation plants. Furthermore, current dosing control systems suffer from unstable feed pressure, low impurity removal efficiency, and reagent pipe clogging, resulting in suboptimal control performance in coal preparation plants that have implemented automated flotation control. Therefore, addressing these challenges by optimizing control strategies, rationalizing dosing device structural design, and refining dosing actuators can improve dosing accuracy, rationality, and reliability. This can reduce the workload of workers, reduce personnel, and lower reagent consumption, ultimately bringing significant economic and social benefits to factories and enterprises. Summary of the Invention

[0005] In response to the problems and needs raised above, this solution proposes a flotation multi-point reagent addition system and method based on feedforward control. Due to the adoption of the following technical features, it can achieve the above technical objectives and bring about many other technical effects.

[0006] One object of the present invention is to provide a flotation multi-point reagent addition system based on feedforward control, comprising:

[0007] Medicine barrels;

[0008] a multi-stage centrifugal pump and a mechanical diaphragm pump, wherein the multi-stage centrifugal pump and the mechanical diaphragm pump are connected in parallel and form a first common node and a second common node at their ends, respectively, the first common node being in communication with the medicine barrel, wherein the multi-stage centrifugal pump is configured to pump the medicine from the first common node to the second common node, and the mechanical diaphragm pump is configured to generate negative pressure so that the medicine is pumped from the first common node to the second common node while pressurizing the medicine;

[0009] a pressure-maintaining tank having an input end and an output end, wherein the input end is connected to the second common node and is configured to store medicine inputted through the input end and output a stable medicine through the output end;

[0010] A plurality of dosing components are connected in parallel and communicated with the output end, wherein each dosing component includes an electric needle valve configured to control the opening and closing degree to adjust the flow rate of the added agent.

[0011] In addition, the flotation multi-point reagent addition system based on feedforward control according to the present invention may also have the following technical features:

[0012] In one example of the present invention, it further includes: a buffer component,

[0013] are respectively provided between the multi-stage centrifugal pump and the second common node and between the mechanical diaphragm pump and the second common node, and are configured to stabilize the medicament with pulsed fluidity pumped out by the multi-stage centrifugal pump or the mechanical diaphragm pump;

[0014] Wherein, the buffer assembly includes a buffer chamber and a damping pulse shock absorber connected thereto.

[0015] In one example of the present invention, the present invention further includes: a first filter and a second filter,

[0016] The first filter is provided between the medicine barrel and the first public node and is configured to filter the medicine flowing through the medicine barrel to the first public node;

[0017] The second filter is disposed between the output end and the medicated assembly, and is configured to filter the medicament flowing to the medicated assembly through the pressure-maintaining tank.

[0018] In one example of the present invention, the present invention further includes: a first check valve,

[0019] It is arranged between the medicine barrel and the first public node, and is configured so that the medicine in the medicine barrel can only flow through the medicine barrel toward the first public node.

[0020] In one example of the present invention, the present invention further includes: a controller,

[0021] It is coupled to the multi-stage centrifugal pump and the mechanical diaphragm pump, and is configured to control the motor speed of the mechanical diaphragm pump to reach a target speed so that the pipeline pressure reaches near the target pipeline pressure; obtain the actual pipeline pressure value and calculate the difference between the actual pipeline pressure and the target pipeline pressure, and then control the multi-stage centrifugal pump to perform residual compensation on the target pipeline pressure to achieve the target dosage;

[0022] It is coupled to the dosing assembly and configured to control the electric needle valve to compensate for the residual error of the target dosing amount to achieve the addition of the target drug flow rate.

[0023] Another object of the present invention is to provide a method for adding reagents to a flotation multi-point reagent addition system based on feedforward control as described above, comprising the following steps:

[0024] A mechanical diaphragm pump motor-maximum flow characteristic model is established, and based on the mechanical diaphragm pump characteristic model, the motor speed of the mechanical diaphragm pump is controlled to reach a target speed so that the pipe pressure reaches near the target pipe pressure; the actual pipe pressure value is obtained and the difference between the actual pipe pressure and the target pipe pressure is calculated, and then the multi-stage centrifugal pump performs residual compensation on the target pipe pressure to achieve the target dosage;

[0025] A flow-electric needle valve model is established, and the electric needle valve compensates for the residual of the target dosage based on the flow-electric needle valve model to achieve the addition of the target agent flow.

[0026] In one example of the present invention, establishing a mechanical diaphragm pump motor-maximum flow characteristic model includes the following steps:

[0027] First, through preliminary experiments, the corresponding relationship between the maximum flow rate and the speed of the mechanical diaphragm pump motor is obtained, the function type of the corresponding relationship between the two is analyzed, and a mathematical model is used to fit the relationship between the two. The fitted relationship is analyzed and verified. Once it is proved that the relationship is accurate, it is the mechanical diaphragm pump motor-maximum flow characteristic model.

[0028] In one example of the present invention, the relationship between the motor speed and the maximum flow rate of the mechanical diaphragm pump is:

[0029] Y=a1X 3 -a2X 2 +a3X-a4,

[0030] Among them, Y is the speed of the mechanical diaphragm pump motor in r / min, X is the maximum flow rate of the addition system in L / h, and a1, a2, a3, and a4 are model parameters.

[0031] In one example of the present invention, establishing a flow-electric needle valve model includes the following steps:

[0032] First, a one-to-one correspondence between the reagent flow rate and the electric needle valve opening is obtained through preliminary experiments. Then, the type of the corresponding relationship between the two is analyzed. Then, a mathematical model of this type is used to fit the relationship between the two. The fitted relationship is analyzed and verified. Once the relationship is proven to be accurate, it becomes the flow-needle valve opening model.

[0033] In one example of the present invention, the relationship between the flow rate of the agent and the opening of the electric needle valve is:

[0034]

[0035] Where Y is the flow rate in L / h, X is the needle valve opening in %, and b1, b2, and b3 are model parameters.

[0036] Hereinafter, the best embodiment of the present invention will be described in more detail with reference to the accompanying drawings so that the features and advantages of the present invention can be easily understood. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings of the embodiments of the present invention. The drawings are only used to illustrate some embodiments of the present invention, but not to limit all embodiments of the present invention thereto.

[0038] Figure 1 Schematic diagram of the structure of a flotation multi-point reagent addition system based on feedforward control according to an embodiment of the present invention;

[0039] Figure 2 is a fitting diagram of the relationship between pipe pressure and maximum flow according to an embodiment of the present invention;

[0040] Figure 3 is a fitting diagram of the relationship between the inverter speed and the maximum flow rate according to an embodiment of the present invention;

[0041] Figure 4 is a fitting diagram of the relationship between the needle valve opening and the flow rate according to an embodiment of the present invention;

[0042] Figure 5 Schematic diagram of a multi-point traffic interaction model according to an embodiment of the present invention;

[0043] Figure 6 FIG. 4 is a schematic diagram of a return error compensation algorithm according to an embodiment of the present invention.

[0044] List of reference numerals:

[0045] Add system 100;

[0046] Medicine barrel 10;

[0047] Multistage centrifugal pump 20;

[0048] Mechanical diaphragm pump 30;

[0049] Pressure holding tank 40;

[0050] Input terminal 41;

[0051] Output terminal 42;

[0052] Observation tank 43;

[0053] Dosing component 50;

[0054] Electric needle valve 51;

[0055] First rotor flowmeter 52;

[0056] Buffer assembly 60;

[0057] buffer bin and 61;

[0058] Damping pulse shock absorber 62;

[0059] First filter 70;

[0060] Second filter 80;

[0061] a first check valve 90;

[0062] a second check valve 110;

[0063] a third check valve 120;

[0064] A second rotor flowmeter 130;

[0065] A third rotor flowmeter 140;

[0066] a first pressure gauge 150;

[0067] a second pressure gauge 160;

[0068] a third pressure gauge 170;

[0069] First safety valve 180;

[0070] Second safety valve 190;

[0071] First on-off valve 200;

[0072] A second on-off valve 210;

[0073] A third on-off valve 220;

[0074] Fourth on-off valve 230;

[0075] Fourth rotor flowmeter 240;

[0076] A first public node A;

[0077] The second public Node B. DETAILED DESCRIPTION

[0078] In order to make the purpose, technical solution and advantages of the technical solution of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of specific embodiments of the present invention. The same figure marks in the drawings represent the same parts. It should be noted that the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the described 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.

[0079] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning understood by persons of ordinary skill in the field to which the invention belongs. The words "first", "second" and similar terms used in the patent application specification and claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "a" or "an" do not necessarily indicate a quantity limitation. Words such as "include" or "comprising" mean that the elements or objects preceding the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connected" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0080] According to the first aspect of the present invention, a flotation multi-point reagent addition system 100 based on feedforward control is provided. Figure 1 Shown, including:

[0081] Medicine barrel 10;

[0082] A multi-stage centrifugal pump 20 and a mechanical diaphragm pump 30 are connected in parallel and form a first common node A and a second common node B at their two ends, respectively. The first common node A is connected to the medicine barrel 10. The multi-stage centrifugal pump 20 is configured to pump the medicine from the first common node A to the second common node B. The mechanical diaphragm pump 30 is configured to generate negative pressure so that the medicine is pumped from the first common node A to the second common node B while pressurizing the medicine.

[0083] a pressure-maintaining tank 40 having an input end 41 and an output end 42 , wherein the input end 41 is connected to the second common node B and is configured to store medicine inputted via the input end 41 and output a stable medicine via the output end 42 ;

[0084] A plurality of dosing components 50 are connected in parallel and communicated with the output end 42 , wherein each dosing component 50 includes an electric needle valve 51 configured to control the opening and closing degree to adjust the flow rate of the added agent.

[0085] The working process of the dosing system 100 is as follows: the mechanical diaphragm pump 30 generates negative pressure, causing the medicine in the medicine barrel 10 to flow from the medicine barrel 10 toward the first common node A under the adsorption effect of the negative pressure. The medicine flows to the mechanical diaphragm pump 30, where the medicine is pressurized and then pumped into the pressure-maintaining tank 40 through the input end 41, so that the pipe pressure reaches near the target pipe pressure; the actual pipe pressure value is obtained and the difference between the actual pipe pressure and the target pipe pressure is calculated. The multi-stage centrifugal pump 20 then performs residual compensation for the target pipe pressure to achieve the target dosing amount; the medicine flows from the output end 42 to the multiple dosing components 50, and the electric needle valve 51 of the dosing component 50 compensates for the residual of the target dosing amount to achieve the addition of the target medicine flow rate;

[0086] In short, the addition system 100 enables precise flow control of direct addition of a single reagent at multiple locations, with multiple flowmeters used for detection and calibration, thus enabling precise flow control of flotation reagents at multiple locations. A mechanical diaphragm pump and a multi-stage centrifugal pump 20 create a negative pressure inlet for the reagent, which is then buffered and subjected to constant pressure control. The reagent in the main flow path is then diverted and discharged by a precision needle valve. The actual flow rate is verified by branch flowmeters and the main flowmeter, enabling feedback control.

[0087] The dosing system 100 can take into account dosing accuracy over a large range and has a flow rate calibration function; it is suitable for continuous operation and has a long service life; in addition, it has stable feeding pressure and high impurity removal efficiency, and can avoid the problem of drug pipe clogging; the dosing system 100 improves the accuracy, rationality and reliability of flotation dosing, thereby reducing labor intensity, saving manpower, reducing drug consumption, and significantly improving economic and social benefits.

[0088] In one example of the present invention, the buffer component 60 is further included.

[0089] They are respectively provided between the multi-stage centrifugal pump 20 and the second common node B and between the mechanical diaphragm pump 30 and the second common node B, and are configured to stabilize the medicament with pulsed fluidity pumped out by the multi-stage centrifugal pump 20 or the mechanical diaphragm pump 30;

[0090] The buffer assembly 60 includes a buffer chamber 61 and a pulse damping shock absorber 62 connected thereto;

[0091] That is to say, the multi-stage centrifugal pump 20 and the mechanical diaphragm pump 30 will cause the medicine to produce pulse-type fluidity during the process of pumping the medicine. This pulse-type flow of medicine will cause instability in the flow of medicine. Therefore, a buffer component 60 is provided. By adding a damping pulse shock absorber 62 in the buffer bin, the medicine flowing into the buffer bin returns to stability under the action of the damping pulse shock absorber 62, and then flows into the pressure maintaining tank 40; by providing the buffer component 60, the stability of the medicine flow can be improved and the accuracy of the medicine addition can be improved.

[0092] In one example of the present invention, the first filter 70 and the second filter 80 are further included.

[0093] The first filter 70 is provided between the medicine barrel 10 and the first public node A and is configured to filter the medicine flowing through the medicine barrel 10 to the first public node A;

[0094] The second filter 80 is provided between the output end 42 and the dosing assembly 50 and is configured to filter the medicine flowing from the pressure-maintaining tank 40 to the dosing assembly 50 ;

[0095] For example, the first filter 70 is a bag filter and the second filter 80 is a Y-type filter; preferably, the filtering accuracy of the first filter 70 is less than the filtering accuracy of the second filter 80, that is, the first filter 70 filters larger particles of impurities, and the second filter 80 is used to filter smaller particles of impurities.

[0096] The drug pretreatment device, including a dual drug filtration device, is used at both the feed and discharge ends to reduce impurities in the drug. The dual filtration device consists of two liquid filters. The pre-filter is a bag filter that removes 99% of impurities from the drug. The front end of the filter is connected to a one-way valve and a feed valve via a feed pipe, while the rear end is connected to a multi-stage centrifugal pump 20, a safety valve, and a mechanical diaphragm pump 30 via pipelines. The post-filter is a Y-type filter, connected to a total flow meter via a main pipeline, and to a manual valve at the rear end, effectively preventing impurities from clogging the flow meter and needle valve.

[0097] By setting up a first filter 70, the medicine flowing out of the medicine barrel 10 can be filtered for the first time to prevent the medicine containing impurities from flowing to the multi-stage separation pump and the mechanical diaphragm pump 30 and causing blockage and damage; by setting up a second filter 80, the medicine flowing out of the pressure maintaining tank 40 can be further filtered to prevent the medicine containing impurities from clogging the flow meter and the electric needle valve 51.

[0098] In one embodiment of the invention, a pressure-maintaining tank 40 is equipped with an observation liquid chamber 43 to ensure stable pipe pressure. The tank 40 also includes a drug inlet, an observation chamber, a drug outlet, and a pressure gauge. The pressure-maintaining tank 40 is vertically positioned. The drug enters the drug inlet, passes through the drug inlet pipeline, and freely flows / drips into the transparent observation chamber, entering the drug outlet through the bottom outlet of the observation chamber. The observation chamber is preferably made of PVC-U, and a pressure relief valve is used to control the height of the observation chamber page.

[0099] In one example of the present invention, the first check valve 90 is further included.

[0100] It is arranged between the medicine barrel 10 and the first public node A, and is configured so that the medicine in the medicine barrel 10 can only flow through the medicine barrel 10 toward the first public node A, so as to prevent the medicine from flowing back into the medicine barrel 10.

[0101] In one example of the present invention, the second check valve 110 and the third check valve 120 are further included.

[0102] The second check valve 110 is provided between the multi-stage centrifugal pump 20 and the second common node B, and is configured to allow the agent to flow only from the multi-stage centrifugal pump 20 toward the second common node B;

[0103] The third check valve 120 is provided between the mechanical diaphragm pump 30 and the second common node B, and is configured to allow the medicine to flow only from the mechanical diaphragm pump 30 toward the second common node B;

[0104] That is, the second check valve 110 and the third check valve 120 can prevent the medicine from flowing back from the pressure maintaining tank 40 to the multi-stage separation pump and the mechanical diaphragm pump 30 when the pressure of the pressure maintaining tank 40 is greater than the pressure of the second common node B.

[0105] In one example of the present invention, the dosing assembly 50 further includes: a first rotor flowmeter 52,

[0106] It is connected in series with the electric needle valve 51 and is configured to measure the flow rate of the medicine flowing through the electric needle valve 51 .

[0107] In one example of the present invention, the second rotor flowmeter 130 and the third rotor flowmeter 140 are further included.

[0108] The second rotor flowmeter 130 is provided between the multi-stage centrifugal pump 20 and the second common node B, and is configured to measure the flow rate of the reagent flowing out of the multi-stage centrifugal pump 20;

[0109] The third rotor flowmeter 140 is disposed between the mechanical diaphragm pump 30 and the second common node B, and is configured to measure the flow rate of the medicine flowing out of the mechanical diaphragm pump 30 .

[0110] In one example of the present invention, the fourth rotor flowmeter 240 is further included.

[0111] The fourth rotor flowmeter 240 is disposed between the output end 42 and the second filter 80 and is configured to measure the flow rate of the medicine flowing out of the output end 42 of the pressure maintaining tank 40 .

[0112] In one example of the present invention, the first pressure gauge 150, the second pressure gauge 160 and the third pressure gauge 170 are further included.

[0113] The first pressure gauge 150 is disposed between the multi-stage separation pump and the buffer assembly 60 and is configured to monitor the pressure of the agent pumped out by the multi-stage separation pump;

[0114] The second pressure gauge 160 is disposed between the mechanical diaphragm pump 30 and the buffer assembly 60 and is configured to monitor the pressure of the medicine pumped out by the mechanical diaphragm pump 30 ;

[0115] The third pressure gauge 170 is disposed on the pressure-maintaining tank 40 and is configured to monitor the pressure of the medicine in the pressure-maintaining tank 40 .

[0116] In one example of the present invention, the first safety valve 180 and the second safety valve 190,

[0117] The first safety valve 180 is connected in parallel with the mechanical diaphragm pump 30 and is configured to control the working pressure of the mechanical diaphragm pump 30 to protect the mechanical diaphragm pump 30;

[0118] The second safety valve 190 is connected between the buffer assembly 60 and the second common node B, and is configured to control the pressure of the medicine flowing out of the buffer assembly 60 to protect the adding system 100 .

[0119] In one example of the present invention, the invention further includes: a first on-off valve 200, a second on-off valve 210, a third on-off valve 220, and a plurality of fourth on-off valves 230.

[0120] For example, Figure 5 As shown, the dosing components 50 include five, and the corresponding fourth on-off valves 230 include five;

[0121] The first on-off valve 200 is disposed between the medicine barrel 10 and the first check valve 90 and is configured to control the on-off flow of the medicine from the medicine barrel 10 toward the first check valve 90 ;

[0122] The second on-off valve 210 is provided between the buffer assembly 60 and the second rotor flowmeter 130 and is configured to control the on-off flow of the agent from the buffer assembly 60 toward the second rotor flowmeter 130 ;

[0123] The third on-off valve 220 is provided between the buffer assembly 60 and the third rotor flowmeter 140 and is configured to control the on-off flow of the agent from the buffer assembly 60 toward the third rotor flowmeter 140 ;

[0124] One of the fourth on-off valves 230 is disposed between the first pressurizing component and the second filter 80 and is configured to control the on-off flow of the agent from the second filter 80 toward the first pressurizing component;

[0125] The remaining fourth on-off valves 230 are respectively disposed between two adjacent pressurizing assemblies and are configured to control the on-off flow of the medicine from the previous pressurizing assembly to the next pressurizing assembly.

[0126] In one example of the present invention, the present invention further includes: a controller,

[0127] It is coupled to the multi-stage centrifugal pump 20 and the mechanical diaphragm pump 30 and is configured to control the motor speed of the mechanical diaphragm pump 30 to reach the target speed so that the pipeline pressure reaches near the target pipeline pressure; obtain the actual pipeline pressure value and calculate the difference between the actual pipeline pressure and the target pipeline pressure, and then control the multi-stage centrifugal pump 20 to perform residual compensation on the target pipeline pressure to achieve the target dosage;

[0128] It is coupled to the dosing assembly 50 and configured to control the electric needle valve 51 to compensate for the residual error of the target dosing amount to achieve the addition of the target drug flow rate.

[0129] That is, it is coupled to the multi-stage centrifugal pump 20 and the mechanical diaphragm pump 30 and is configured to control the multi-stage centrifugal pump 20 and the mechanical diaphragm pump 30 to work together so that the pipe pressure of the addition system 100 reaches the target pipe pressure and the target dosage is achieved;

[0130] It is coupled to the dosing assembly 50 and configured to control the electric needle valve 51 to compensate for the addition of the drug based on the residual of the target dosing amount;

[0131] The controller controls the mechanical diaphragm pump 30 to generate negative pressure so that the medicine in the medicine barrel 10 flows from the medicine barrel 10 toward the first common node A under the adsorption effect of the negative pressure, flows to the mechanical diaphragm pump 30, and the medicine is pressurized by the mechanical diaphragm pump 30 and pumped into the pressure-maintaining tank 40 through the input end 41, so that the pipe pressure reaches near the target pipe pressure; the actual pipe pressure value is obtained and the difference between the actual pipe pressure and the target pipe pressure is calculated, and then the controller controls the multi-stage centrifugal pump 20 to perform residual compensation on the target pipe pressure to achieve the target dosing amount; the medicine flows from the output end 42 to the multiple dosing components 50, and the controller controls the electric needle valve 51 of the dosing component 50 to compensate for the residual of the target dosing amount to achieve the addition of the target medicine flow rate.

[0132] It can be understood that the controller is also coupled to the pressure maintaining tank 40, the first rotor flowmeter 52, the second rotor flowmeter 130, the third rotor flowmeter 140, the fourth rotor flowmeter 240, the first pressure gauge 150, the second pressure gauge 160, the third pressure gauge 170, the first safety valve 180, the second safety valve 190, the first on-off valve 200, the second on-off valve 210, the third on-off valve 220, and multiple fourth on-off valves 230; and is used to control or feedback the measurement information or switch information of the above-mentioned measuring / control equipment; for example, the flow information of the flowmeter is fed back to the controller to control the on and off of the on-off valve, etc.

[0133] For example, the controller is PCL control; the specific working process is as follows:

[0134] The feedforward plus feedback control method of the diaphragm pump is as follows: the feedforward controller obtains the flow setting information, and performs feedforward control on the diaphragm pump according to the diaphragm pump characteristic model; the frequency converter controls the diaphragm pump motor to reach the target speed, so that the pipe pressure reaches near the target pipe pressure; the actual pipe pressure is transmitted to the PLC through the pressure gauge; the PLC calculates the difference between the actual pipe pressure and the target pipe pressure, and uses PID control to fine-tune the multi-stage centrifugal pump 20.

[0135] The feedforward plus feedback control method of the electric needle valve 51 establishes a flow characteristic model of the needle valve based on the needle valve characteristics and test calibration, establishes a feedforward controller to obtain flow setting information, and performs feedforward control on the electric needle valve 51 according to the flow characteristic model. Then, based on the obtained experimental data theoretical model, the dynamic relationship between the flow rate and the opening of the flow control valve is described. The electric needle valve 51 is feedforward controlled according to the flow characteristic relationship. After the difference obtained by the flow meter detection is transmitted to the PLC, the PLC transmits the control signal to the electric needle valve 51 through PID control with pre-adjusted parameters, and then performs fine adjustment. This control strategy combines the predictive ability of feedforward control and the adjustment ability of feedback control to improve the overall performance of the system and can respond to and adapt to various changes in operating conditions in real time.

[0136] In this embodiment, a multi-point coordinated control method is used. This method requires preliminary experiments to explore the multi-point needle valve flow interaction model, and then use the flow interaction model for analysis, and perform feedforward and feedback control based on the model. The multi-point needle valve flow interaction model is obtained from the preliminary experimental exploration. The test is divided into single valve test, synchronous adjustment test and combination test. The single valve test is to adjust the opening of each valve separately in sequence (from fully closed to fully open), and the other valves remain fully closed, and the flow changes are recorded. This helps to verify whether the impact of each valve on the system is indeed the same, and to establish a relationship between flow and opening for each needle valve; the synchronous adjustment test is to adjust all valves with the same opening at the same time and record the flow changes; the combination test is to gradually adjust the opening of all valves according to a predetermined sequence (such as each valve gradually adjusts from fully closed to fully open in different stages), and observe and record the flow at each stage. Feedforward plus feedback control is based on a flow interaction model of needle valves at multiple locations. For set flow values ​​at multiple dosing points, the feedforward model is used to calculate the expected openings of each needle valve based on the flow characteristics of the needle valves at these locations and the flow interaction model between them. Parameters are then set for each branch based on the resulting flow interaction model and the needle valve flow. Electric needle valve 51 is feedforward controlled based on the flow characteristic model. The flow meter transmits real-time flow to the PLC, which calculates the error between the set value and the actual value and sends a command to the needle valve. The needle valve then compensates for the target dosing residual, and the system automatically adjusts the needle valve opening to achieve the target flow. Ultimately, coordinated flow control is achieved when flow demand changes dynamically, avoiding interference and conflict.

[0137] It should be noted that the addition system 100 uses multiple flow meters for calibration to ensure the accuracy of flow detection, and the flow meter detection is divided into drug inlet branch detection and drug outlet branch detection. In the mechanical diaphragm pump 30 branch of the drug inlet branch, a flow meter is set after the buffer bin, and the multi-stage centrifugal pump 20 branch flow meter is also set after the buffer bin. The total drug outlet flow detection flow meter is set after the pressure holding bin. The drug inlet branch, drug outlet branch and total flow meters are set as redundant calibration designs. The flow meters use different measurement principles, but the calibration method uses the total flow calibration method. Since the front-end drug supply branch is in the pulse section and the total flow meter is in the flow stable section, the instantaneous flow calibration cannot be used. The total flow calibration method is adopted to alleviate the influence of pipeline pulses. For drug inlet branch verification, during the same time period T, the total flow rate of the 30 mechanical diaphragm pump branches is recorded as L1, indicating the pipeline is in the pulse stage. The total flow rate of the 20 multistage centrifugal pump branches is recorded as L2, indicating the pipeline is in the pulse stage. The total flow meter reading is L3, indicating the flow is in the stable stage. If L3 - L2 - L1 > 5% * L3, there may be a problem with the pipeline damping system. You need to: 1. Check for pipeline blockage. 2. Check and adjust the pressure setting range of the damper air pressure back pressure valve and safety valve.

[0138] It is understandable that the addition system 100 uses a redundant pressure gauge detection and calibration to ensure pipeline pressure stability. The pressure gauge detection is divided into the multi-stage centrifugal pump 20 branch detection and the mechanical diaphragm pump 30 branch detection. In the multi-stage centrifugal pump 20 branch, a pressure gauge is set after the buffer tank. The mechanical diaphragm pump 30 branch is also set after the buffer tank. For the multi-stage centrifugal pump 20 branch, the pressure indication number is recorded as P1, which is in the pipeline pulse section. For the diaphragm pump branch, the pressure indication number is recorded as P2, which is in the pipeline pulse section. The pressure gauge of the pressure-maintaining tank 40 is recorded as P3, which is in the pressure stable section. When P3-P1>5%*P3, it indicates that there may be a problem with the pipeline damping system. It is necessary to: 1. Check the pipeline blockage; 2. Check the pressure setting range of the damper air pressure back pressure valve and the safety valve; 3. Check the pipeline for air and water leakage. Similarly, for the mechanical diaphragm pump 30 branch, when P3-P2>5%*P3, the pipeline damping system needs to be checked.

[0139] The second aspect of the present invention provides a method for adding reagents to the flotation multi-point reagent adding system 100 based on feedforward control as described above, comprising the following steps:

[0140] A motor-maximum flow characteristic model of the mechanical diaphragm pump 30 is established, and based on the characteristic model of the mechanical diaphragm pump 30, the motor speed of the mechanical diaphragm pump 30 is controlled to reach a target speed so that the pipe pressure reaches near the target pipe pressure; the actual pipe pressure value is obtained and the difference between the actual pipe pressure and the target pipe pressure is calculated. The multi-stage centrifugal pump 20 then performs residual compensation on the target pipe pressure to achieve the target dosage;

[0141] A flow-electric needle valve 51 model is established, and the electric needle valve 51 compensates for the residual of the target dosage based on the flow-electric needle valve 51 model to achieve the addition of the target agent flow.

[0142] The specific working process of the adding method is as follows: the mechanical diaphragm pump 30 generates negative pressure, so that the medicine in the medicine barrel 10 flows from the medicine barrel 10 toward the first common node A under the adsorption effect of the negative pressure, flows to the mechanical diaphragm pump 30, and is pressurized by the mechanical diaphragm pump 30 and then pumped into the pressure-maintaining tank 40 through the input end 41, so that the pipe pressure reaches near the target pipe pressure; the actual pipe pressure value is obtained and the difference between the actual pipe pressure and the target pipe pressure is calculated, and then the multi-stage centrifugal pump 20 performs residual compensation on the target pipe pressure to achieve the target dosage; the medicine flows from the output end 42 to the multiple dosing components 50, and the electric needle valve 51 of the dosing component 50 compensates for the residual of the target dosage to achieve the addition of the target medicine flow rate;

[0143] This addition method can take into account dosing accuracy over a large range and has the function of flow calibration; it is suitable for continuous operation and has a long service life; in addition, the feeding pressure is stable, the impurity removal efficiency is high, and the problem of drug pipe blockage can be avoided; this addition method improves the accuracy, rationality and reliability of flotation dosing, thereby reducing labor intensity, saving manpower, reducing drug consumption, and significantly improving economic and social benefits.

[0144] In one example of the present invention, establishing a motor-maximum flow characteristic model of the mechanical diaphragm pump 30 includes the following steps:

[0145] First, through preliminary experiments, the corresponding relationship between the maximum flow rate and the motor speed of the mechanical diaphragm pump 30 is obtained, the function type of the corresponding relationship between the two is analyzed, and a mathematical model is used to fit the relationship between the two. The fitted relationship is analyzed and verified. Once it is proved that the relationship is accurate, it is the mechanical diaphragm pump 30 motor-maximum flow characteristic model.

[0146] In one example of the present invention, the relationship between the motor speed and the maximum flow rate of the mechanical diaphragm pump 30 is:

[0147] Y=a1X 3 -a2X 2 +a3X-a4,

[0148] Wherein, Y is the motor speed of the mechanical diaphragm pump 30 in r / min, X is the maximum flow rate of the addition system 100 in L / h, and a1, a2, a3 and a4 are model parameters.

[0149] In one example of the present invention, establishing a flow-electric needle valve 51 model includes the following steps:

[0150] First, a one-to-one correspondence between the reagent flow rate and the opening of the electric needle valve 51 is obtained through preliminary experiments. Then, the type of the correspondence between the two is analyzed. Then, a mathematical model of this type is used to fit the relationship between the two. The fitted relationship is analyzed and verified. Once the relationship is proven to be accurate, it becomes a flow-needle valve opening model.

[0151] In one example of the present invention, the relationship between the flow rate of the agent and the opening of the electric needle valve 51 is:

[0152]

[0153] Where Y is the flow rate in L / h, X is the needle valve opening in %, and b1, b2, and b3 are model parameters.

[0154] In one example of the present invention, Figure 6 As shown, the algorithm for the electric needle valve 51 to compensate for the residual error of the target dosage based on the flow-electric needle valve 51 model includes:

[0155] Based on the needle valve opening deviation at the current control moment and the control quantity signal of the electric needle valve 51 opening at the previous control moment, the initial control quantity signal of the electric needle valve 51 opening at the current control moment is obtained. The initial control quantity signal of the electric needle valve 51 opening at the current control moment is added to the electric needle valve 51 opening compensation value to obtain the final control quantity signal of the electric needle valve 51 opening; wherein, the return error compensation value ΔL of the electric needle valve 51 is set by the characteristics of the electric needle valve 51 and the flow characteristic model of the needle valve established by test calibration, and is a fixed value, and the positive or negative value is determined by the kth control moment t k The control increment signal ΔU(t k ) determines, if ΔU(t k )>0, then ΔL>0, if ΔU(t k )<0, then ΔL<0.

[0156] Specific cases

[0157] Based on the dual-pump pipe pressure feedforward plus feedback control strategy, for the target pipe pressure SP1, the diaphragm pump is first feedforward controlled to make the pipe pressure reach the target value first. After the actual pipe pressure is calibrated by the pressure gauge, the multi-stage centrifugal pump 20 then performs residual compensation for the target pipe pressure, forming a dual-pump pipe pressure feedforward plus feedback control. The target pipe pressure SP1 is calculated from the target flow range. According to fluid mechanics, when the needle valve opening is constant, the flow rate is positively correlated with the pressure. Therefore, the maximum flow rate of the system is determined by the pipe pressure. After analyzing the experimental data and fitting calculations, the one-to-one correspondence between the pipe pressure and the maximum flow rate is first obtained through preliminary experiments. Then, the type of the corresponding relationship between the two is analyzed. Then, the mathematical model of this type is used to fit the relationship between the two. The fitted relationship is analyzed and verified. After proving that the relationship is accurate, it is the pipe pressure-maximum flow model: Z = 0.009356X-0.1348, where Z is the pipe pressure in MPa and X is the maximum flow rate in L / h. The fitting relationship diagram is shown as follows: Figure 2As shown. The diaphragm pump feedforward plus feedback control method, the feedforward controller obtains the flow setting information, and performs feedforward control on the diaphragm pump according to the diaphragm pump characteristic model. The frequency converter controls the diaphragm pump motor to reach the target speed, so that the pipe pressure reaches near the target pipe pressure. The actual pipe pressure is transmitted to the PLC through the pressure gauge. The PLC calculates the difference between the actual pipe pressure and the target pipe pressure, and uses PID control to fine-tune the multi-stage centrifugal pump 20. The diaphragm pump characteristic model is obtained based on the relationship between the diaphragm pump motor speed and the maximum flow rate. After analyzing the experimental data and fitting calculations, the one-to-one correspondence between the maximum flow rate and the diaphragm pump motor speed is first obtained through preliminary experiments. Then, the type of the corresponding relationship between the two is analyzed, and then the mathematical model of this type is used to fit the relationship between the two. The fitted relationship is analyzed and verified. After proving that the relationship is accurate, it is the diaphragm pump motor speed-maximum flow characteristic model: Y=0.01012X 3 -1.376X 2 +63.88X-842.9, where Y is the inverter motor speed in r / min, and X is the maximum flow rate of the system in L / h. The fitting relationship diagram is as follows: Figure 3 shown.

[0158] Based on the dosing control strategy of the electric needle valve 51, for the target dosing amount SP2, first control the multi-stage centrifugal pump 20 and the diaphragm pump to make the pipe pressure reach the target value, and then feed-forward control the target dosing amount through the electric needle valve 51. After the actual flow is calibrated by the branch flow meter, the needle valve compensates for the residual of the target dosing amount. The electric needle valve 51 adopts a feed-forward plus feedback control method. The flow characteristic model of the needle valve is established based on the needle valve characteristics and test calibration, and a feed-forward controller is established to obtain the flow setting information. The electric needle valve 51 is feed-forward controlled according to the flow characteristic model. It can be seen from fluid mechanics that when the pressure is constant, the flow is positively correlated with the needle valve opening. According to the relationship between the flow and the needle valve, after analyzing the experimental data and fitting calculations, a mathematical model is used to fit the relationship between the two. The relationship between the flow and the needle valve opening is: Where Y is the flow rate, the unit is L / h, X is the needle valve opening, the unit is %, the fitting relationship diagram is as follows Figure 4 As shown in the figure. The theoretical model is then used to describe the dynamic relationship between the flow rate and the opening of the flow control valve. Based on this flow characteristic relationship, feedforward control is performed on the electric needle valve 51. The difference detected by the flow meter is transmitted to the PLC, which then transmits the control signal to the electric needle valve 51 through PID control with pre-adjusted parameters for fine-tuning. This control strategy combines the predictive power of feedforward control with the regulatory power of feedback control to improve the overall system performance and enable real-time response and adaptation to various operating conditions.

[0159] The exemplary implementation of the flotation multi-point reagent addition system 100 and method based on feedforward control proposed in the present invention is described in detail above with reference to the preferred embodiments. However, it will be understood by those skilled in the art that, without departing from the concept of the present invention, various modifications and variations can be made to the above-mentioned specific embodiments, and various combinations of the various technical features and structures proposed in the present invention can be made without exceeding the scope of protection of the present invention, which is determined by the appended claims.

Claims

1. A flotation multi-point reagent addition system based on feedforward control, characterized in that: include: Medicine barrels (10); A multistage centrifugal pump (20) and a mechanical diaphragm pump (30), wherein the multistage centrifugal pump (20) and the mechanical diaphragm pump (30) are connected in parallel and form a first common node (A) and a second common node (B) at both ends thereof, respectively, wherein the first common node (A) is connected to the medicine barrel (10), wherein the multistage centrifugal pump (20) is configured to pump the medicine from the first common node (A) to the second common node (B), and the mechanical diaphragm pump (30) is configured to generate a negative pressure so that the medicine is pumped from the first common node (A) to the second common node (B) while pressurizing the medicine; A pressure-maintaining tank (40) having an input end (41) and an output end (42), wherein the input end (41) is connected to the second common node (B) and is configured to store medicine input via the input end (41) and output a stable medicine via the output end (42); A plurality of dosing assemblies (50), wherein the plurality of dosing assemblies (50) are connected in parallel and communicated with the output end (42), wherein each dosing assembly (50) comprises an electric needle valve (51) configured to control the opening and closing degree to adjust the flow rate of the added agent; A controller is coupled to the multi-stage centrifugal pump (20) and the mechanical diaphragm pump (30), and is configured to control the motor speed of the mechanical diaphragm pump (30) to reach a target speed so that the pipe pressure reaches near the target pipe pressure; obtains the actual pipe pressure value and calculates the difference between the actual pipe pressure and the target pipe pressure, and then controls the multi-stage centrifugal pump (20) to perform residual compensation on the target pipe pressure to achieve the target dosage; and is coupled to the dosing assembly (50), and is configured to control the electric needle valve (51) to compensate for the residual of the target dosage to achieve the addition of the target drug flow rate; The adding method of the flotation multi-point reagent adding system based on feedforward control includes the following steps: A motor-maximum flow characteristic model of the mechanical diaphragm pump (30) is established, and based on the characteristic model of the mechanical diaphragm pump (30), the motor speed of the mechanical diaphragm pump (30) is controlled to reach a target speed, so that the pipe pressure reaches near the target pipe pressure; an actual pipe pressure value is obtained and a difference between the actual pipe pressure and the target pipe pressure is calculated, and then the multi-stage centrifugal pump (20) performs residual compensation on the target pipe pressure to achieve the target dosage; A flow-electric needle valve (51) model is established, and the electric needle valve (51) compensates for the residual of the target dosage based on the flow-electric needle valve (51) model to achieve the addition of the target agent flow.

2. The flotation multi-point reagent addition system based on feedforward control according to claim 1 is characterized in that: Also included: a buffer component (60), They are respectively arranged between the multi-stage centrifugal pump (20) and the second common node (B) and between the mechanical diaphragm pump (30) and the second common node (B), and are configured to stabilize the medicine with pulse fluidity pumped out by the multi-stage centrifugal pump (20) or the mechanical diaphragm pump (30); The buffer assembly (60) includes a buffer chamber (61) and a damping pulse shock absorber (62) connected thereto.

3. The flotation multi-point reagent addition system based on feedforward control according to claim 1 is characterized in that: Also included: a first filter (70) and a second filter (80), The first filter (70) is provided between the medicine barrel (10) and the first public node (A), and is configured to filter the medicine flowing through the medicine barrel (10) to the first public node (A); The second filter (80) is provided between the output end (42) and the dosing assembly (50), and is configured to filter the medicine flowing through the pressure-maintaining tank (40) to the dosing assembly (50).

4. The flotation multi-point reagent addition system based on feedforward control according to claim 1 is characterized in that: Also includes: a first check valve (90), It is arranged between the medicine barrel (10) and the first common node (A), and is configured so that the medicine in the medicine barrel (10) can only flow through the medicine barrel (10) toward the first common node (A).

5. The flotation multi-point reagent addition system based on feedforward control according to claim 1 is characterized in that: The establishment of the motor-maximum flow characteristic model of the mechanical diaphragm pump (30) includes the following steps: First, the correspondence between the maximum flow rate and the motor speed of the mechanical diaphragm pump (30) is obtained through preliminary experiments, the function type of the correspondence between the two is analyzed, the relationship between the two is fitted using a mathematical model, and the fitted relationship is analyzed and verified. After proving that the relationship is accurate, it is the mechanical diaphragm pump (30) motor-maximum flow rate characteristic model.

6. The flotation multi-point reagent addition system based on feedforward control according to claim 5 is characterized in that: The relationship between the motor speed and the maximum flow rate of the mechanical diaphragm pump (30) is: ； Where, Y is the motor speed of the mechanical diaphragm pump (30) in r / min, X is the maximum flow rate of the addition system in L / h, a 1 、 a 2 、 a 3 and a 4 are model parameters.

7. The flotation multi-point reagent addition system based on feedforward control according to claim 1 is characterized in that: The establishment of the flow-electric needle valve (51) model includes the following steps: First, a one-to-one correspondence between the flow rate of the reagent and the opening of the electric needle valve (51) is obtained through preliminary experiments. Then, the type of the corresponding relationship between the two is analyzed. Then, a mathematical model of this type is used to fit the relationship between the two. The fitted relationship is analyzed and verified. Once the relationship is proven to be accurate, it becomes a flow-needle valve opening model.

8. The flotation multi-point reagent addition system based on feedforward control according to claim 7 is characterized in that: The relationship between the flow rate of the reagent and the opening of the electric needle valve (51) is: ； Among them, Y is the flow rate, the unit is L / h, X is the needle valve opening, the unit is %. b 1 、 b 2 and b 3 are model parameters.

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