RU2273828C2 - Method and device for measuring mass flow of gas-liquid mixture - Google Patents

Abstract

FIELD: measurement technology.

SUBSTANCE: oil-gas mixture is divided to liquid and gaseous phases by means of separator connected with container. Space of container between two levels which limit the space is filled with liquid phase and, when emptying container, by gaseous phase. Times of filling and emptying of volume are registered simultaneously. Container is provided with scales for registering change in expulsive force in time, which force acts on hollow body connected with scale. The body has calibrated volume and calibrated height. It is provided with flat edges. The body is disposed in container inside area of mentioned volume. Container in the area of body disposition has calibrated area of internal cavity's cross-section. Container is subject to filling in and emptying till liquid covers body completely or till level of liquid goes downs lower than body's border. Maximal and minimal readings of scales achieved during time of filling in and emptying are used for measuring densities of liquid and gaseous phases and their mass flows from given design formulas. Mass flow can be determined without necessity of calibration for height of volume of liquid and distance between levels of filling.

EFFECT: simplified procedure of measurement; improved precision.

2 cl, 3 dwg

Description

The invention relates to the field of measuring equipment and can be used to determine the flow rate of gas-liquid mixtures, in particular oil and gas mixtures.

A known method for determining the mass flow rate of gas-saturated oil, based on the separation of the mixture into liquid and gas phases, the flow of liquid into the vessel with a calibrated slot hole, measuring the pressure of the liquid column in the vessel and determining the flow rate of the liquid phase according to a certain formula (see P.P. Kremlevsky. Flowmeters and counters of quantity. - Leningrad, Mechanical Engineering, 1989, p. 224).

The known method is implemented using a device containing a separator, a container, a vessel with a calibrated slotted hole, pressure gauges of a liquid column in a vessel and column heights, pipelines.

The disadvantage of this method is that it does not provide the ability to measure the flow rate of the gas phase of the mixture.

The closest known technical solution is a method for determining the flow rate of a gas-liquid mixture, based on the separation of the mixture into liquid and gas phases, filling of a volume calibrated by height of the volume V (h) of the container with alternately different phases from one level to another, measuring the distance h between levels, time Δt filling the volume between the levels and changing the pressure Δp of the liquid column at different liquid levels, determining the density and volumetric flow rates of the phases of the medium according to the corresponding formulas using V (h), h, Δp, Δt.

A device for implementing this method comprises a separator of a gas-liquid mixture into liquid and gas phases, a tank with a volume calibrated by height between certain filling levels, differential pressure sensors, a level sensor, a synchronization system for measuring the differential pressure and time of filling the volume between two fixed levels in the tank, valves , pipelines (see. "Technical description of the installation of GZU" Ikar "40-8-400", the manufacturer of OJSC "Ikar" - Kurgan pipe fittings plant in the city of Kurgan).

The disadvantage of this method and device is the difficulty of implementation, since this requires calibrating the height of the volume of the tank and the distance between the levels of filling the tank, matching the operations of measuring the differential pressure and time with the process of filling (emptying) the liquid of the tank from one fixed level to another, measuring changes liquid column pressure and the distance between filling levels in the presence of ripple when changing parameters in the tank. In addition, the method does not provide a sufficiently high accuracy in determining the costs due to the significant number of parameters that need to be determined in the process of its implementation, and because of a decrease in the accuracy of their measurement in the presence of ripples and the need to coordinate measurements with respect to time and height of filling the tank.

The objective of the invention is to simplify the method and device for its implementation, improving the accuracy of measurements.

The technical result achieved in this case is that it is not necessary to calibrate the volume of the container and the distance between the levels of filling the tank, coordinate the measurement of the pressure drop and time with the process of filling (emptying) the liquid of the tank from one fixed level to another, and measure changes in column pressure liquid and the distance between filling levels in the presence of ripple when changing parameters in the tank.

This result is achieved by the fact that in the method for determining the flow rate of a gas-liquid mixture, which includes dividing the mixture into liquid and gas phases, determining the density of the liquid and gas phases, filling the volume of the container between two volume-limiting levels in turn with the liquid phase and emptying the container with the gas phase while recording the time Δt _{g, g} filling and emptying the volume, determining the density of the liquid and gas phases and the mass flow rate of the phases, the hollow body of the calibrated volume and calibrated are placed in the tank th height with horizontally flat ends, which loads the scales, the container is filled with the liquid phase and emptied from it until the liquid completely covers the body or its level drops below the body boundary, the magnitude and the change forces acting on the hollow body, fix the moments t ₁ and t _{2 of the} beginning and end of the change in the buoyancy force when filling the tank with liquid and when emptying, determine the density of the liquid and gas phase as ρ _W = N _W / V ₁ , ρ _g = N _g / V ₁ , where N _f and N _g are the maximum and minimum weight readings, V ₁ is the volume of the hollow body, and the mass flow rates (G _f and G _g ) of the liquid and gas phases of the mixture are calculated by the formulas

where F is the cross-sectional area of the internal cavity of the container in the area of the hollow body, h is the height of the body, Δt _{W, g} = t ₂ -t ₁ is the time of filling and emptying the volume.

This result is also achieved by the fact that the capacity of the device for determining the mass flow rate of a gas-liquid mixture intended for implementing the method and comprising a separator of the gas-liquid mixture into liquid and gas phases, a counter for filling and emptying the volume of the tank between two levels and pipelines connected to the tank, is connected to the tank, equipped with valves, equipped with scales for determining and recording the change in buoyancy force over time and the hollow body connected with the scales with calibrated volume lifting and calibrated height with flat ends located horizontally, which is placed in the zone of the said volume, while the tank has a calibrated cross-sectional area of the inner cavity in the area of the hollow body.

A diagram of a device for determining the mass flow rate of a gas-liquid mixture according to the proposed method is shown in figure 1.

Figure 2 (a, b) shows a graph of the dependence of the buoyancy force on time during operation of the device.

The device comprises a separator 1 (see FIG. 1) of a gas-liquid mixture, a container 2 with a volume for filling it with the mixture phases, a counter for filling and emptying the volume of the container between two levels, devices 3 for monitoring the parameters of the medium in the container. The capacitance between levels A has a calibrated cross-sectional area of the internal cavity. Inside the container in the zone between levels A on the scales 4, there is a hollow body 5 of a calibrated volume of calibrated height with flat ends located horizontally, and a balancing system 6 on the balance of body weight. The separator through valve 8 and pipe 7 is connected to the source of the mixture and pipelines 9, 10 - with the tank. The capacity of the pipelines 11, 12 through the valves 13, 14 is connected to the collecting manifold. The pipe 15 through the valve 16 connects the source of the mixture with the collection manifold.

The determination of costs by the proposed method is as follows. Close the valves 16, 14 and disconnect the source of the mixture and the lower part of the tank from the collecting manifold. Valves 8 and 13 are opened. The gas-liquid mixture from the source enters the separator, is divided into liquid and gas phases, which, respectively, through pipelines 10 and 9 enter the tank. In this case, the gas phase from the tank enters the collection manifold, and the liquid phase accumulates in the tank. When the liquid completely closes the body 5, close the valve 13 and open the valve 14. The liquid begins to be displaced from the tank into the drain manifold by the gas coming from the separator. When the liquid level drops below the boundary of the body 5, the valves 14 and 8 are closed. During operation, the magnitude and change in time of the buoyancy force N acting on the body 5 is recorded using scales (ten-weight). The graphs of the dependence of N on time t have the form shown in figure 2. Points 1-4 fracture dependencies correspond to the moments when the liquid in the container border in filling or emptying of the body coincides with the end faces 5, the values of the ejection force and the N _x N _z respectively take place when the body 5 is completely stored in the liquid or gas.

The density of liquids and gas phases is determined by the formulas

The volumetric flow rate of liquid V _g and gas V _g is determined using the relations

where F is the calibrated cross-sectional area of the internal cavity of the tank in the area of the body 5, h is the calibrated height of the body 5, Δt = t ₂ -t ₁ is the time of filling and emptying the volume (see figure 2). The mass flow rate of gas G _x and G _z is determined by the formulas

The obtained values of the densities and flow rates relate to the conditions that are fixed in the tank during operation using the devices 3 control parameters.

The implementation of the proposed method does not require calibration according to the height of the volume of the container and the distance between the levels of filling the tank, coordinating the operations of measuring the pressure drop and time with the process of filling (emptying) the liquid of the tank from one fixed level to another, measuring changes in the pressure of the liquid column and the distance between the filling levels in conditions of ripple when changing parameters in the tank. This leads to a simplification of the device and the procedure for determining costs. In addition, the parameters by which costs are determined can be determined with high accuracy, which increases the accuracy of the method.

Claims (2)

1. The method of determining the mass flow rate of the phases of a gas-liquid mixture, including the separation of the mixture into liquid and gas phases, filling the volume of the container between two levels restricting it alternately with the liquid phase and when the container is emptied by the gas phase while recording the time Δt _{w, g of} filling and emptying the volume, determination the density of the liquid and gas phases and the mass flow rate of the phases, characterized in that a hollow body of calibrated volume and calibrated height with horizontally flat In this case, which loads the scales, the container is filled with the liquid phase and emptied from it until the liquid completely covers the body or its level drops below the body boundary, the magnitude and the change in the buoyancy force acting on the hollow body are recorded over time , fix the moments t ₁ and t _{2 of the} beginning and end of the change in buoyancy when filling the tank with liquid and when emptying, determine the density of the liquid and gas phase as ρ _W = N _w / V ₁ , ρ _g = N _g / V ₁ , where N _W and N _g - the maximum and minimum weight reading; V ₁ - the volume of the hollow body, and calculate the mass flow rate G _W and G _{g the} liquid and gas phases of the mixture according to the formulas

where F is the calibrated cross-sectional area of the internal cavity of the tank in the area of the hollow body; h is the height of the body; Δt _{W, g} = t ₂ -t ₁ - the time of filling and emptying of the volume. 2. A device for determining the mass flow rate of phases of a gas-liquid mixture, comprising a separator of a gas-liquid mixture into a liquid and gas phases associated with the tank, a counter for filling and emptying the tank volume between two levels and pipelines connected to the tank equipped with valves, characterized in that the tank is equipped with weights for determining and recording in time the change in buoyancy force and a hollow body connected with the scales with a calibrated volume and a calibrated height with flat ends located th horizontally, which is located in the zone of the said volume, while the container has a calibrated cross-sectional area of the inner cavity in the area of the hollow body.

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