Convenient calibration and autonomous control method of digital frequency conversion controller for industrial metering pump

Abstract

The present invention relates to on-site convenient calibration technology and autonomous control technology of special digital frequency conversion controller for metering pumps, which solves the problem of on-site calibration. With the help of the control of digital frequency conversion controller, complex calibration becomes simple and easy, and only needs to start the metering pump , when the pump stops working, measure the output Q of the metering pump to obtain the characteristic parameters of the pump, and store them in the non-volatile storage unit of the digital frequency conversion controller. Automatically calculate flow rate, cumulative quantity and other metering parameters, and provide a correction method for calibration results. The invention solves the problem of autonomous control, does not need an external controller, only needs the measured value of the controlled quantity and the process setting value to realize autonomous control, can reduce the control structure, reduce the cost, especially the process setting value It is converted into a standard signal value and has good versatility.

Description

technical field [0001] The invention is limited to the technical field of digital frequency conversion controllers for industrial metering pumps, and in particular relates to convenient calibration and autonomous control methods for the special digital frequency conversion controllers. technical background [0002] Industrial metering pumps are widely used in quantitative and proportional dosing of fluids in petroleum, chemical, water treatment, food, pharmaceutical, environmental protection, liquid fertilization and other fields. [0003] The main function of industrial metering pumps is to adjust the flow rate according to the requirements of the production process. At present, there are mainly three fluid adjustment methods as follows: [0004] 1. Offline adjustment by hand wheel [0005] This method adjusts the stroke size of the diaphragm or plunger through the adjustment handwheel of the metering pump, and then indirectly adjusts the flow rate. The disadvantages are:...

AI Technical Summary

Problems solved by technology

[0006] (1) There are strong alkali, strong acid and toxic gas on the industrial site, which is inconvenient for manual operation and difficult to meet the process requirements of modern industrial production on-line real-time adjustment

[0007] (2) When the working flow is small and the stroke is close to zero, but the driving motor still runs at the rated speed, it is basically in a state of doing useless work, causing unnecessary energy consumption, and at the same time causing reactive power of the mechanical transmission mechanism and the driving motor wear and tear

[0008] (3) The mechanical structure of adjusting the stroke by the hand wheel is relatively complicated, the reliability is low, and the cost of manufacturing and installation will be increased

[0009] (4) For modern industrial production that requires online real-time control, frequency converters and PLC controllers need to be configured additionally, resulting in a further increase in cost, and PLC is a general-purpose programmable controller, which requires professionals to meet the special requirements of metering pumps Only after programming can it be suitable for the control of industrial metering pumps

[0012] (1) The adjustment speed is slow (it takes about 160 minutes to adjust from the minimum flow rate to the maximum flow rate), the dynamic response ability is poor, and the pure belt is large, which makes it difficult to meet the requirements of online real-time control of the automation process

[0013] (2) The mechanical structure of the electric regulator is complicated, the reliability is low, and the cost is high

[0014] (3) Large weight and volume, inconvenient to install

[0015] (4) When the flow rate is small, the same as the first method, the driving motor still runs at the rated speed, basically in a state of doing useless work, resulting in unnecessary energy consumption, and at the same time causing reactive wear of the mechanical transmission mechanism and the driving motor

[0027] In the adjustment method of digital frequency conversion controller, the accuracy of the flow is closely related to the calibration. The existing calibration method is relatively cumbersome. It is necessary to know the transmission ratio, stroke volume (or displacement) of the specific metering pump, etc., which is very inconvenient for field applications. Convenient, especially when the actual working conditions are inconsistent with the factory calibration conditions (for example, when the actual working pressure is inconsistent with the factory test pressure), there will be a large difference between the factory parameters and the actual parameters. Therefore, according to the on-site working conditions, in the actual Calibration near the working point can effectively improve the accuracy of the metering pump, so this invention provides a convenient calibration method

[0028] Although the existing digital frequency conversion controllers can receive external 4-20mA analog signals or various digital signals, they can only passively adjust the flow rate according to the received signals. Generally, the flow rate changes linearly (or proportionally) following the received signal. Instead of actively adjusting the flow rate according to the requirements of the production process, this requires an additional controller to calculate and generate a control signal based on the measured value of the field instrument and the set value required by the process, and then transmit the control signal to the digital frequency conversion controller. Make it linearly adjust the flow according to this signal

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