SU980071A1 - Method of regulating gas mass rate-of-flow from container - Google Patents

Description

(54) METHOD FOR REGULATING THE MASS CONSUMPTION OF GAS FROM THE CYLINDER

The invention relates to the automatic regulation of the gas flow rate, and more specifically to the system of regulation, in which the method of maintaining a constant mass flow rate of gas discharged from a cylinder is applied.

A known method of controlling the flow rate of gas in pneumatic systems is that a certain pressure drop on the sensitive element of the regulator, combined with the metering body, is kept under pressure and the flow cross section of the latter is changed accordingly, while the critical pressure drop tl is maintained at the outlet choke.

The disadvantage of this method is that the accuracy of maintaining the gas flow is low, since the temperature of the gas, which can vary over a wide range, is not taken into account.

The closest technical solution to the present invention is a method of controlling the mass flow rate of gas from a cylinder, which consists in measuring the absolute values of the pressure and temperature of the gas in

the cylinder connected directly to the metering body of the regulator, and correspondingly, changes the value from the bore section of the latter in order to obtain the specified flow rate and critical pressure difference on the regulating body C2 3.

In this method, the accuracy of maintaining the gas flow is increased,

as the temperature of the flowing gas is taken into account. However, this method is suitable for pneumatic systems, in which the change in gas temperature does not proceed quickly enough. it

This is due to the fact that the sensors for measuring the temperature of the gas have significant inertia. Therefore, with a rapid change in temperature

20 sensors do not have time to monitor changes in this parameter of gas.

The purpose of the invention is to increase the accuracy of mass maintenance, at close to adiabatic processes.

25 cylinder emptying.

This goal is achieved by the fact that in the method of controlling the mass flow rate of gas from a cylinder, the absolute values of pressure and temperature of gas in a cylinder, directly related to the metering body, are measured.

And accordingly, they change the value of the flow section of the last dp to obtain the specified flow rate and the critical pressure drop across the regulator organ, constantly changing the value of the flow area of the metering body according to the signal of the gas temperature in the cylinder before supplying the gas to the dispenser body and removing this signal from the MCUoT when the gas is supplied to the latter, and a further change in the passage section of the metering body is made only by changing the pressure of the gas in the cylinder according to the law

6 if F -1P-1

im

. 2n

2p beg

where F is the area of the flow area of the metering body, G is the specified mass flow rate

gas,

(p) - coefficient of gas flow through the metering body; absolute temperature ganach. for in the tank before the flow rate;

absolute gas pressure

beginning in the cylinder before the flow rate;

P is the absolute gas pressure in the cylinder; h

n is the coefficient of polytropes. The drawing shows the device with which the proposed method is carried out. The device contains a cylinder 1 with compressed gas, a pipeline 2, with a shut-off body 3, connecting the cylinder 1 with a metering body 4, having a movable needle 5, which is connected to the regulator's actuators b, temperature sensors 7 and gas pressure 8 connected to the computing device 9, and the master 10 assovoy consumption.

When the shut-off device 3 of Yollon 1 is closed, pressure sensors 8 and temperatures 7, which record the pressure and temperature of the gas in the cylinder 1, transmit signals to the computing system 9. Any change in the temperature and pressure of the gas in the cylinder 1 causes the position of the needle 5 of the metering body 4 to change, associated with the actuator 6, which affects the computing device 9.

As a result, the needle 5 occupies a position corresponding to the given temperature in the cylinder and the pressure and reference signal from the setting device 10. When gas is supplied from the cylinder 1 through line 2 to the metering body 4 of the regulator, opening the valve 3 causes the gas temperature in the cylinder 1 to change.

change in the process of work is taken into account depending on the pressure change according to the law

P-1

(-R-h

t t

BUT (H

 us /

de T

-the absolute temperature of the gas in the cylinder 1;

- absolute gas pressure in cylinder 1

the absolute temperature of the LHCIM is in the cylinder-1 before the flow rate is applied;

absolute gas pressure

yach in tank 1 before flow

coefficientpolitropy.

At the same time, the size of the through passage of the metering body 4 is established in accordance with the law.

n-f

where is f

the area of the flow area of the dispensing organ;

and a given mass flow rate of gas, -.

(P)

gas flow rate through the metering body. In accordance with this ratio of computing device 9, taking into account the signal of initial values of gas temperature and pressure in cylinder 1 before switching on, converts the signal from pressure sensor 8 and the signal from unit 10 to a control signal supplied to actuator 6, which moves the needle 5, provides for the regulation of the mass flow rate of gas.

The proposed system operates for 15-20 seconds. During this time, a constant mass flow rate is maintained, since only the gas pressure in the cylinder 1 is taken into account by means of a pressure sensor 8 with low inertia.

. The independence of the adjustment of the regulator from the change in load is ensured by the supercritical gas flow rate in the throttle control element 4.

In the proposed device, the temperature drop rate can reach 10-20 degrees / s, with an absolute temperature of the gas in the cylinder 1 of about 50 K. At this rate of falling, the error in measuring the temperature (at a constant time of the temperature sensor around

0 V 1 s) could reach 10-20, i.e. 20-40% of absolute temperature and.

In this method, the accuracy is due to the fact that the change in the temperature of the gas in the cylinder 1 takes into account

Claims (1)

Claim A method of controlling the mass flow rate of gas from a cylinder, which consists in measuring the absolute values of pressure and gas temperature in a cylinder connected directly to the metering body, and accordingly, they change the value of the flow cross section of the latter to obtain a given value of the flow rate and critical pressure drop across the regulatory body , characterized in that, in order to improve the accuracy of maintaining the mass flow at close to adiabatic processes of evacuation of the cylinder, the passage value is constantly changed cross-section of the metering body by the signal of the gas temperature in the cylinder before the gas is supplied to the metering body, and this signal is removed when gas is supplied to the latter, and a further change in the flow-through section of the metering body is made only by changing the gas pressure in the cylinder according to 5 of the law - F s - * ^iam S P-1 * ^P n “h ²ⁿ ₽ ^g where F is the area of the passage section 10 of the metering body; G is the given mass gas flow rate; C = C (n) is the coefficient of gas flow through the metering body; 15 T _yaach - the absolute temperature of the gas in the cylinder before applying the flow; ^p zhchg ~ absolute pressure of gas in a cylinder before giving 20 consumption; p is the absolute gas pressure in the cylinder; η is the polytropic coefficient.