RU1795424C - Gas flow rate control device - Google Patents

Abstract

The invention relates to automation and can be used to control the flow rate of gaseous media. The purpose of the invention is to improve the accuracy of regulation. The device contains a supply pipe 1, an actuator of a control valve 2, a control pipe 3, a throttling element 4 in the form of a critical nozzle, an output manifold 5, a pressure regulator 6, a unit for calculating the set value of the gas pressure 7 in front of the throttling element 4, a gas pressure sensor 8, a gas temperature sensor 9 to a channel for setting the gas flow rate 10. 1 ill.

Description

The invention relates to automation and can be used in chemical, gas and other industries to control the flow of gaseous media.

A known method and device for controlling the flow of liquid and gas, according to which the regulation is carried out by creating a swirling movement of the flow and its subsequent throttling through the constriction device.

A disadvantage of the known technical solution is that it has low accuracy, a large noise level, and a small adjustment range.

The closest to the described invention in technical essence and the achieved result is a technical solution based on the regulation of the differential pressure on the constricting device in the form of a diaphragm.

In order to control the gas flow rate, it is necessary to maintain a constant pressure and temperature in front of the diaphragm, which complicates the control circuit. In addition, when several control threads are operated in parallel, a pressure perturbation when one of the threads is turned on is transmitted to the sensitive elements of the other threads. This causes overshoot, disrupts the stability of the flow rate maintenance process, and reduces the accuracy of regulation.

The aim of the invention is to improve the accuracy of regulation.

This object is achieved in that the device is equipped with a unit for calculating a predetermined gas pressure value in front of the throttling element made in the form of a critical nozzle and a gas temperature sensor in front of the throttling element, the first and second inputs of the unit for calculating the set gas pressure value in front of the throttling element being connected respectively to the channel gas flow rate and a temperature sensor, and the output of the calculation unit is connected to the second input of the controller.

Comparison of the claimed technical solution with the prototype shows that it

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characterized by the presence of a unit for calculating a predetermined gas pressure value in front of the throttling element, and their connections with other circuit elements.

Thus, the proposed device has properties that do not coincide with the properties of previously known devices for controlling gas flow, and the features can be qualified as significant differences.

The invention is illustrated in the drawing, which shows a diagram of a device for controlling gas flow.

The device includes a supply pipe 1, an actuator for a control valve 2, a control pipe 3, a throttling element 4 in the form of a critical nozzle, an output manifold 5, a pressure regulator 6, a unit for calculating the set value of the gas pressure 7 in front of the throttling element 4, a sensor gas pressure 8, gas temperature sensor 9, gas flow setting channel 10.

A device for controlling the flow of gas operates as follows.

Gas from the supply pipe 1 is supplied to the inlet of the control valve 2, where the gas pressure is partially throttled. From the control valve 2, gas enters the control pipe 3 and then through the throttle element 4, made in the form of a critical nozzle, to the output manifold 5. Information about the value of the set flow rate Q through the channel. The flow rate set point M goes to the calculation unit for the set pressure of the basin 7, which calculates the pressure P by the formula:

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corresponding to a given flow rate, taking into account the temperature Ti, in front of the throttling element 4, the value of which is supplied to block 7.

The calculated value of the preset pressure P is supplied to the regulator b, in which the value of P is continuously compared with the current value of the pressure Pc in front of the throttling element 4 in the form of a critical nozzle and, if they are inconsistent, generates a command signal to the actuator of the control channel 2, aimed at maintaining the preset pressure P .

For the throttling element 4 to work in the form of a critical nozzle and, accordingly, the flow rate can be calculated by the formula (1), the ratio between the pressures to the throttling element 4 Pc and in the output manifold 5 Pk must satisfy the condition:

, 2. (2)

When condition (2) is satisfied, the pressure change in the output manifold 5 is not transmitted to the control pipe 3.

Thus, the proposed technical solution provides a stable and high-quality flow control process by maintaining only one parameter - the pressure value in front of the throttling element 4 in the form of a critical nozzle.

Claims (1)

SUMMARY OF THE INVENTION A device for controlling a gas flow rate, comprising a regulator, the output of which is connected to an actuator of a regulating valve, a throttling element installed in the pipeline behind the regulating valve, a gas pressure sensor in front of the throttling element connected to the first input of the regulator, and gas flow setting channel, characterized in that, in order to improve the accuracy of regulation, The device is equipped with a unit for calculating the set value of the gas pressure in front of the throttling element, made in the form of a critical nozzle, and a gas temperature sensor in front of the throttling element, the first and second inputs of the unit for calculating the set value of gas pressure in front of the throttling element, respectively, being connected to the gas flow setting channel and to the sensor gas temperature, and its output is connected to the second input of the controller.