CN120406285A

CN120406285A - A control algorithm for uniformly adding liquid by dynamic feedback via a delivery pump

Info

Publication number: CN120406285A
Application number: CN202510491620.8A
Authority: CN
Inventors: 仲路; 徐飞
Original assignee: Nanjing Times Technology Co ltd
Current assignee: Nanjing Times Technology Co ltd
Priority date: 2025-04-18
Filing date: 2025-04-18
Publication date: 2025-08-01

Abstract

The present invention discloses a control algorithm for the dynamic and uniform dripping of liquids by feedback realized by a delivery pump, including an HMI human-machine interface, a PLC controller, a weighing system, a speed-regulating metering pump and a reactor according to weight, specifically comprising the following steps: the real-time weighing mass data of the weighing system is transmitted to the PLC controller as the real-time original weighing data, the customer's input setting value is discretized into per second, and then used as the current setting value input to the PID control algorithm, and the mass that has left the weighing system is calculated (weight loss method) according to the change in the real-time mass data of the weighing system, as the actual input amount of the PID control algorithm. The present invention belongs to the field of daily necessities technology, and specifically refers to a control algorithm for the dynamic and uniform dripping of liquids by feedback realized by a delivery pump.

Description

Control algorithm for realizing feedback dynamic uniform liquid dripping through delivery pump

Technical Field

The invention belongs to the technical field of articles for daily use, and particularly relates to a control algorithm for dynamically and uniformly dripping liquid through feedback realized by a delivery pump.

Background

In general, a PLC (Programmable Logic Controller: programmable logic controller) system, a DCS (Distributed Control System: distributed control system) system or a method for self-modeling by customers is to calculate real-time fed-back flow amount (i.e. flow rate) of unit time by taking time accumulation of a running pump as a denominator and real-time weight fed back by a weighing system as a molecule, and then to perform feedback calculation to obtain output which acts on a conveying pump according to the flow rate feedback as PV of PID (proportional-integral-DERIVATIVE CONTROL proportional integral differential control, here called PID for short), and set addition amount and addition time calculation result as SV flow rate, so as to realize automatic control of feedback flow rate of the pump;

This method is limited in that the customer's destination is very strong, simply by inputting the process requirements into the system, simply deriving the SV (setpoint), and then deriving the PV (presentvalue current value) from the accumulated time, the PID output is calculated. Therefore, if the PID parameters are not coordinated slightly, the set flow cannot be compensated in a period of time, PID adjustment is performed, then the next period is reversely adjusted again, so that a fluctuation adding amount is obtained repeatedly, the adding amount in the period of time of a client cannot be uniform all the time, and the process test condition is influenced, so that the final experiment fails.

Disclosure of Invention

The invention does not depend on a linear metering pump, can realize the purpose of uniformly adding liquid phase materials only by a weighing system with data transmission, a common speed-regulating metering pump, a PLC or a controller with a programming function on site, and solves various process problems caused by overlong nonlinear adjustment time of flow and a pump.

In order to realize the functions, the technical scheme adopted by the invention is that the control algorithm for dynamically and evenly dripping liquid through feedback realized by a conveying pump comprises an HMI (human-machine interface), a PLC (programmable logic controller), a weighing system, a speed regulating metering pump and a reaction kettle according to parts by weight, and specifically comprises the following steps:

S1, a PLC (programmable logic controller) transmits real-time weighing quality data of a field weighing system to the PLC through a communication bus to serve as real-time original weighing data;

S2, receiving a data input signal of an HMI human-machine interface by a PLC, taking data input by a customer as a set value (g/m) gram/min, discretizing into each second according to the set value, or converting into a mass gram (g) required to be fed in each set acquisition period, and taking the mass gram (g) as a current set value input by a PID control algorithm;

And S3, after the PID control algorithm collects the set value, calculating the mass (weight reduction method) which is separated from the weighing system according to the change quantity of the real-time mass data of the feedback weighing system, as the input actual quantity of the PID control algorithm, then calculating the pump speed of the speed regulating metering pump to be corrected in the next period, and predicting whether the speed of the speed regulating metering pump to be increased or decreased in the next period so as to correct the mass deviation of the last time, and not directly participating in the calculated flow, so as to dynamically control the liquid to be uniformly dripped into the reaction kettle.

Preferably, the PID control algorithm in step S2 and step S3 uses the mass weighing data that changes in real time as an input port of the actual data control end, that is, a control object of the PID control algorithm, uses the theoretical planned added mass in a unit time after the dispersion as a set value as a control target, and adjusts the speed by outputting an adjustment speed to the speed-regulating metering pump so that the liquid amount achieved by the speed-regulating metering pump reaches the mass to be added in the unit time after the dispersion, and if the liquid amount deviates, the pump speed is continuously adjusted in a next period.

Preferably, the discretization calculation is that Sv (g) = [ Sv (g/m)/60 ]. Times.CP, wherein Sv (g/m) is set value gram/min for data input by a customer, and the CP controls a period (S), and the Sv (g) is converted into mass gram (g) required to be fed in a discretization acquisition period.

Preferably, the feed amount is calculated dynamically by W2=W0-W1, wherein W0 (g) is the actual value calculated by the weight reduction method of the weighing system, W1 (g) is the weight value measured by the weighing system in real time, and W2 (g) is the weight of the liquid which has been added to the reaction vessel.

Preferably, the PID data input is ysp (t) =sv (g), e (t) =sv (g) -W2, d (t) =0, irrespective of the differential term, the error e (t) is the difference between the set value and the actual value, where the actual value is the negative value of the added weight (weight reduction means addition because of the weight reduction method).

Preferably, the output y (t) is that the frequency variation=y (t) is calibrated to be initial frequency, wherein y (t) output represents the frequency variation of the speed regulating metering pump, the calibrated initial frequency is the initialized running frequency of the metering pump, the value is input by a user according to the inherent parameters of the pump, the rotating speed of the pump can be adjusted by changing the frequency of the pump, the flow of liquid is further controlled, and the dynamic adjustment of the liquid dropping amount is realized.

The liquid feeding device has the beneficial effects that by combining the control algorithm with equipment such as an HMI (human-machine interface), a PLC (programmable logic controller), a weighing system, a speed regulating metering pump and the like, the high-precision control of the liquid feeding quantity can be realized, discretization processing is carried out according to the input value set by a user, the feeding quality in each acquisition period is accurately calculated, the liquid is ensured to be uniformly dripped into a reaction kettle, the linear metering pump is not relied on, and various technical problems caused by overlong nonlinear adjustment time of the flow and the pump are solved.

Drawings

FIG. 1 is a block diagram of a system control flow in accordance with an embodiment of the present invention.

Detailed Description

The technical solutions of the present invention will be clearly and completely described in connection with the embodiments, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

The invention discloses a control algorithm for dynamically and uniformly dripping liquid through feedback realized by a delivery pump, which comprises an HMI (human-machine interface), a PLC (programmable logic controller), a weighing system, a speed regulating metering pump and a reaction kettle according to parts by weight, and comprises the following steps:

S1, installing an HMI human-machine interface, facilitating a user to input a set value and the running state of a monitoring system, connecting a PLC controller and a weighing system, ensuring accurate transmission of real-time weighing quality data through a communication bus, connecting a speed regulating metering pump with a reaction kettle, and connecting the speed regulating metering pump with the PLC controller in a signal manner to realize adjustment and control of pump speed;

s2, a user inputs a set value through an HMI human-machine interface, for example, the set value is 500g/m (g/min), the PLC performs discretization calculation according to the set value, and if the control period CP is 15S, the discretized feeding quality in unit time is obtained The weighing system measures the weight of the reaction kettle and the internal substances in real time, the initial weight W0 (g) =10000 g, the current actual weight W1 is continuously changed along with the addition of the liquid, and the PLC performs data acquisition and processing according to a set control period (15 seconds);

S3, at the beginning of a first control period, the weighing system measures the current actual weight W1 in real time, and if 9980g is assumed, the weight W2=W0-W1=20g is added;

PID data input, set value ysp (t) =sv (g), e (t) =sv (g) -W2, where e (t) =125-20=105 g, d (t) =0;

The PID control algorithm calculates the frequency variation y (t) of the speed-regulating metering pump according to the error, and if y (t) =0.25 is calculated through the algorithm, the actual frequency of the speed-regulating metering pump becomes 0.25×40=10 Hz;

S4, when the second control period starts, measuring the current actual weight W1 again, assuming 9960g, W2=40g, recalculating a set value ysp (t) and an error e (t), and further adjusting the speed of the speed regulating metering pump;

s5, circulating in this way, adjusting each control period according to the real-time weighing data and the set value so as to correct the mass deviation of the previous period;

S6, an operator can monitor parameters such as weight change, set value, actual addition amount, speed of a speed regulating metering pump and the like of the reaction kettle in real time through an HMI human-machine interface;

And S7, if the system is found to have abnormal operation, such as abnormal weight change, unstable pump speed and the like, timely adjustment can be performed or the system can be stopped for fault investigation.

The PID control input and output are not flow, but weighing (mass g) is carried out, that is, the system collects weighing data in the real-time charging bucket as PV value, then the PV value is substituted into the system, theoretical added weighing weight is calculated every moment by moment through flow discretization calculation, and then the theoretical added weighing weight is calculated with the current real-time weighing calculation of measuring sampling to output the adjustment speed of the next control period, so that the error value of the previous period is corrected quickly, the speed can be kept constant in a range, finally, the control effect of uniformly adding liquid materials in the period of 10 seconds or 20 seconds can be realized, the effect is realized through the continuous operation of a user site for 1 month, the reaction kettle body is 50L, the set quantity of 500g/m is added, the average precision is within the error range of plus or minus 0.5g, and the problem of uniformity of liquid phase added materials which always puzzles users is solved well.

The invention and its embodiments have been described above without limitation. In summary, if one of ordinary skill in the art is informed by this disclosure, a structural manner and an embodiment similar to the technical solution should not be creatively devised without departing from the gist of the present invention.

Claims

1. The control algorithm for dynamically and uniformly dripping liquid through feedback realized by a delivery pump is characterized by comprising an HMI (human-machine interface), a PLC (programmable logic controller), a weighing system, a speed regulating metering pump and a reaction kettle according to parts by weight.

2. The control algorithm for dynamically and uniformly dripping liquid through feedback realized by a delivery pump according to claim 1, wherein the PID control algorithm in the step S2 and the step S3 takes real-time variable mass weighing data as an input port of an actual data control end, which is a control object of the PID control algorithm, theoretical plan increasing mass in unit time after discretization is taken as a set value as a control object, and the pump speed is continuously adjusted in a next period if deviation exists by outputting an adjustment speed to a speed-regulating metering pump, and adjusting the speed to enable the liquid quantity to reach the mass to be added in the unit time after discretization.

3. The control algorithm for dynamically and uniformly dripping liquid through feedback realized by a delivery pump according to claim 1, wherein the discretization calculation is that Sv (g) = [ Sv (g/m)/60 ]. CPs, wherein Sv (g/m) is a set value gram/minute of input data of a customer, and CPs control period (S), and Sv (g) is converted into a mass gram (g) required to be fed in a discretization acquisition period.

4. A control algorithm for the dynamic and uniform liquid drop-in feedback by a transfer pump according to claim 3, wherein the feed amount is dynamically calculated by W2=W0-W1, wherein W0 (g) is the actual value calculated by the weight reduction method of the weighing system, W1 (g) is the weight value measured in real time by the weighing system, and W2 (g) is the weight of the liquid which has been added to the reaction vessel.

5. A control algorithm for the dynamic and uniform liquid drop-in feedback achieved by a transfer pump according to claim 3, wherein the PID data input is ysp (t) =sv (g), e (t) =sv (g) -W2, d (t) =0, irrespective of the differential term, error e (t) is the difference between the set point and the actual value, where the actual value is the negative of the added weight.

6. The control algorithm for dynamically and uniformly dripping liquid through feedback realized by a delivery pump according to claim 5, wherein the output y (t) is frequency variation=y (t) and represents the frequency variation of a speed-regulating metering pump, the calibrated initial frequency is the initialized running frequency of the metering pump, the value is input by a user according to inherent parameters of the pump, the rotation speed of the pump can be adjusted by changing the frequency of the pump, the flow rate of the liquid is further controlled, and the dynamic adjustment of the dripping amount of the liquid is realized.