RU2289155C2 - Actuating device for controlling flows of liquid substances in pipelines - Google Patents

Abstract

FIELD: engineering of devices for controlling technological processes.

SUBSTANCE: device for controlling flow contains device for generating additional information about flow of liquid substance, connected to one of inputs of electric positioning device, another input of which is connected to source of analog electric signal. Output of positioning device is connected to servo-motor, connected by its rod to adjusting tool, mounting on pipeline. Device for generating additional information about flow contains piezo-metric averaging pipe with outputs for tapping full and static pressures, mounted in pipeline in front of adjusting tool alongside the flow of liquid substance, and pressure difference indicator with electric analog output signal, connected by its inputs to outputs of piezo-metric pipe. Output of pressure difference indicator is connected to input of square-rooting device.

EFFECT: invention is invariant to alterations of flow mode, provides increased precision of generation of additional information about flow, requires no prior calibration of adjusting tool.

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Description

The invention relates to the field of process control, and in particular to actuators with an analog electric input signal for automatic control systems.

Known actuator for regulating fluid flows in pipelines (Shegal GL Electrical actuators. M.-L .: Gosenergoizdat, 1961, p.12), containing an electromagnetic motor (solenoid) connected by a rod to a regulatory body mounted on the pipeline. In the process of control, the electromagnetic motor by means of the rod moves the regulator in proportion to the analogue electrical input signal.

The disadvantage of this actuator is the large consumed electrical power and the possibility of use only on pipelines of small diameter (up to 30 mm).

The closest in technical essence is the actuator for regulating the flow of liquid media in pipelines (patent WO 03/062938 A1, G 05 D 7/06, 07/31/2003), containing an electric servomotor connected by a rod to a regulatory body mounted on the pipeline, electric a positioner with two inputs, one of which is connected to an analog electrical signal source, and the positioner output is connected to a servomotor, and a device for generating measurement information about the flow rate of a liquid medium flowing through t uboprovod including an electric apparatus of the square root extraction.

During operation, the electric positioner compares the value of the signal from the source of the analog electric signal with the value of the signal from the device for generating measurement information about the flow rate of the liquid flowing through the pipeline, and generates a corresponding output signal, under the action of which the servomotor moves the rod and changes the flow rate liquid medium until the signal difference at the inputs of the positioner becomes equal to zero.

To generate measurement information on the flow rate of a liquid medium, the following sensors are used: a pressure sensor connected to the pipeline to the regulator in the medium flow, a pressure sensor after the regulator and a rod displacement sensor connecting the servomotor to the regulator. In addition, in order to generate a signal for measuring information on the flow rate of the liquid medium, information on the dependence of the valve dimension coefficient (the product of the valve cross-sectional area on the flow coefficient) and the position of the regulator stem obtained previously experimentally is introduced into the said device.

The disadvantage of this actuator is the low accuracy of generating measurement information about the flow rate of the liquid medium, which is determined by the fact that in this case the flow regime of the medium (laminar, turbulent or transitional), which can change during the operation of the actuator when the degree of closure of the regulatory body is not taken into account, is taken into account. In addition, the use of two pressure sensors and the subsequent calculation of the difference of their signals can cause a very high error in determining this difference, since the pressure difference can be small (the difference of close values) for different degrees of closure of the regulatory body. A significant drawback of such an actuator is the need for a preliminary experimental determination for each regulatory body of the relationship between the dimensional coefficient and the position of the stem of the regulatory body, i.e. the need for calibration of the regulatory body, which is associated with large material and labor costs, especially for actuators of large diameter. Another disadvantage of such an actuator is the contamination of the regulatory body during operation, which changes the relationship between the dimensional coefficient and the position of the stem of the regulatory body, which is the reason for the change in the discharge characteristics of the latter.

The objective of the invention is to improve the actuator for regulating fluid flows in pipelines, namely, the creation of an actuator that is invariant to a change in the flow regime of a liquid medium, a change in the pressure of the liquid medium in front of the regulatory body and does not require preliminary calibration of the regulatory body.

EFFECT: creation of an actuating device for regulating fluid flows in pipelines, which is invariant to changes in the fluid flow regime and does not require preliminary calibration of the regulatory body.

The technical result is achieved by the fact that in the actuator for regulating fluid flows in pipelines, containing an electric servomotor connected by a rod to a regulator installed on the pipeline, an electric positioner with two inputs, one of which is connected to an analog electrical signal source, and the positioner output connected to a servomotor, and a device for generating measurement information about the flow rate of a liquid medium flowing through a pipeline including an electric The square root extraction device according to the invention, the device for generating measurement information about the flow rate of the liquid medium of the actuator comprises a piezometric averaging tube with outlets for sampling the total averaged pressure and static pressure installed in the pipeline in front of the regulating body along the liquid flow, and a pressure difference sensor with electric an analog output signal connected by its inputs to the outputs of the piezometric averaging tube, while the output the differential pressure sensor is connected to the input of the root extraction device, the output of which is connected to the second input of the positioner.

This design ensures the invariance of the flow rate characteristics of the actuator to a change in the flow regime of the liquid medium through the pipeline, which can be laminar, turbulent or transitional, depending on the degree of closure of the regulatory body, and eliminates the need for preliminary, costly and time-consuming calibration of the regulatory body due to the inclusion of a flowmeter device that measures the average flow rate of a liquid medium through a pipeline under all conditions its course.

Compared with the prototype of the claimed design has a distinctive feature in the combination of elements and their relative position.

A diagram of an actuator for controlling fluid flows in pipelines is shown in the drawing.

An actuating device for regulating fluid flows in pipelines comprises an electric servomotor 1 connected by a rod 2 to a regulating body 3 mounted on the pipeline 4, an electric positioner 5 with two inputs. The first input 6 of the positioner 5 is connected to the source of the analog electric signal, and its output 7 is connected to the servomotor 1. The actuator includes a device for generating measurement information 8 about the flow rate of the fluid flowing through the pipeline, which includes an electric square root extraction device 9, a piezometric tube 10 with outputs 11 and 12 for sampling the total averaged and static pressures installed in the pipeline 4, in front of the regulating body 3 in the liquid flow food, and a pressure difference sensor 13 connected by its inputs 14 and 15 to the outputs 11 and 12 of the piezometric averaging tube 10. The output 16 of the pressure difference sensor 13 is connected to the input 17 of the square root extraction device, the output of which 18 is connected to the second input 19 of the positioner 5.

The operation of the actuator to control the flow of liquid in the pipelines is as follows.

The actuator, which is included as part of the automatic control of the technological parameter, receives an analog electrical signal from the automatic controller of the technological parameter, which implements one or another regulation law.

When the value of the analog electrical input signal changes during the operation of the automatic control system, the electric positioner 5 compares the value of this signal received at the first input 6 with the value of the signal received at the second input 19, which is proportional to the flow rate of the liquid medium, and generates a control signal from the output 7 to the servomotor 1. The latter moves the rod 2 of the regulatory body 3, changes its cross-section and the flow rate of the liquid medium through the pipeline until the difference als at the inputs of the positioner 5 becomes zero. The signal supplied to the input 19 of the positioner 5, is formed as follows. From the piezometric averaging tube 10, the signals of the total averaged and static pressures are fed to the inputs 14 and 15 of the pressure difference sensor 13, which converts the value of the pressure difference into a proportional electrical analog signal and transfers it from its output 16 to the input 17 of the square root extraction device 9. Using this device is necessary due to the fact that the mass flow of liquid medium g _w flowing through line 4 depends on the total pressure difference P _n at the output 11 of the averaging piezometric cuttings 10 and the static pressure P _v in the conduit 4 (Dp = P _n -P _CT) and is described by the following formula:

where k is a constant coefficient.

Thus, during the operation of the actuator, the mass flow of the liquid medium through the regulator will be proportional to the analogue electrical input signal.

The advantage of the proposed technical solution is:

- invariance to changes in the flow regime of the medium in the pipeline during operation of the actuator and contamination of the regulatory body;

- the possibility of application on pipelines of almost any diameter;

- reduction of operating costs by eliminating the need for preliminary calibration of the regulatory body.

The proposed actuator can be implemented on the basis of an electric servomotor, positioner, widespread electronic elements and simple means of measuring flow.

Actuator can be used to control the flow rate of a fluid in various industries.

Claims (1)

An actuator for regulating fluid flows in pipelines, comprising an electric servomotor connected by a rod to a regulator installed on the pipeline, an electric positioner with two inputs, one of which is connected to an analog electrical signal source, and the positioner output is connected to a servomotor, and a device for generating measuring information on the flow rate of a liquid medium flowing through a pipeline including an electric square-bed extraction device characterized in that the device for generating measurement information about the flow rate of the liquid medium contains a piezometric averaging tube with outputs for sampling the total averaged pressure and static pressure installed in the pipeline in front of the regulatory body for the flow of the liquid medium, and a pressure difference sensor with an electrical analog output signal, connected by its inputs to the outputs of the piezometric averaging tube, while the output of the differential pressure sensor is connected to the input of the quad extraction device reverse root, the output of which is connected to the second input of the positioner.