CN201032457Y - Low gas content gas-liquid dual-phase flow measuring apparatus based on standard Venturi tube and vortex flowmeter - Google Patents

Abstract

The utility model discloses a gas-liquid two-phase flow measuring device with low air content based on capacitance sensor and standard Venturi tube and Vortex flowmeter. The device consists of a measuring pipeline, a flow mixer at the front end of the measuring pipeline, a standard Venturi tube in the middle of the measuring pipeline, a Vortex flowmeter and a temperature sensor at the rear end of the measuring pipeline, a pressure difference sensor connected with the standard Venturi tube, an A/D transmitting card and a computer. All sensors are connected to the computer through the A/D transmitting card. The utility model has the advantages of long service life, small size, simple structure, convenient installation, comparatively low pressure loss and wide application scope, and is characterized by many reachable measuring parameters, high flow inspection precision and good real-time performance. The utility model is suitable for the measuring of low air content gas-liquid two-phase flow such as oil gas.

Description

Low air void gas-liquid two-phase flow measuring apparatus based on standard Venturi tube and vortex shedding flow meter

Affiliated technical field

The utility model relates to a kind of low air void gas-liquid two-phase flow measuring apparatus based on standard Venturi tube and vortex shedding flow meter.

Background technology

Biphase gas and liquid flow is prevalent in oil, the chemical industry.The complicacy of the mobile system of gas-liquid two-phase brings a lot of difficulties for biphase gas and liquid flow flow, density and the isoparametric measurement of branch phase content, especially when gas phase content in the biphase gas and liquid flow was low, difficult measurement of the branch phase content of gas-liquid two-phase or measurement result precision were not high.

The biphase gas and liquid flow of low air void extensively is present in fields such as oil, chemical industry, and the measurement of biphase gas and liquid flow flow, density and branch phase content has been caused engineering technical personnel's concern and become the focus of current biphase gas and liquid flow area research and one of difficult point.At present Parameter Measurement of Gas-liquid Two-phase is mainly taked following four kinds of methods: (1) uses the method for traditional single-phase flow instrument in conjunction with the measuring two-phase flow parameter model.This method can directly be used ripe single-phase flow instrument measurement diphasic stream parameter, is that people make great efforts one of direction of studying always, but this method needs two measuring sensors, and the precision of the different applications of model influence measurement; (2) use the new technology in modern times.Characteristics such as that this method has is untouchable, precision height, but install more complicated cost an arm and a leg, and service condition requires high, measure field are required harsh, and it is very big to use difficulty in industry spot.(3) on the hardware foundation of maturation, be support platform, use flexible measurement method and measure diphasic stream parameter with the computer technology.That is that all right at present is ripe for this method, needs ripe hardware supported, and equipment price is also somewhat expensive, and precision is not high, and the scope of application is less.(4) application of advanced signal Processing and intelligent method are measured diphasic stream parameter.Utilize signal processing technology and intelligent method, can from the fluctuation signal of two/polyphasic flow, obtain many important but the parameter and the information that are difficult to directly obtain have advantages such as cost is low, hardware is simple.

Another kind of commonly used metering method is biphase gas and liquid flow to be mixed become homogeneous flow, utilize single-phase flowmeter such as restriction flowmeter to wait and obtain flow, but the flow that obtains is the gas-liquid two-phase total volumetric flow rate, can't obtain each minute phase content and separate phase flow rate data.Though densitometer can solve the individual phase measurement problem in conjunction with single-phase flowmeter, measuring accuracy is not ideal enough during still actual the use, and cost is also very high.Vibrating tube densimeter commonly used is very responsive to field conditions such as the temperature of medium, pressure.And there is safety problem in gamma ray density meter, operating conditions is required high.

Summary of the invention

The purpose of this utility model provides a kind of low air void gas-liquid two-phase flow measuring apparatus based on standard Venturi tube and vortex shedding flow meter.

The technical scheme that its technical matters that solves the utility model adopts is: the ultimate principle of the method that low air void biphase gas and liquid flow flow, density and branch phase content are measured is as follows: on the metering pipeline, a mixed flow device at first is installed, this mixed flow device stirs into homogeneous flow with the biphase gas and liquid flow of low air void, the homogeneous flow of this moment can be regarded single-phase flow as, and direct then application standard Venturi tube and vortex shedding flow meter are in conjunction with measuring biphase gas and liquid flow flow, density and branch phase content.

Low air void gas-liquid two-phase flow measuring apparatus based on standard Venturi tube and vortex shedding flow meter has the metering pipeline, on the metering pipeline, be provided with mixed flow device, standard Venturi tube, vortex shedding flow meter and temperature sensor successively, the supporting differential pressure pick-up that is equipped with of standard Venturi tube, vortex shedding flow meter, differential pressure pick-up and temperature sensor link to each other with the A/D transition card, and the A/D transition card links to each other with computing machine.

The beneficial effects of the utility model are: under the situation of not carrying out the gas-liquid two-phase separation, utilize Venturi tube and vortex shedding flow meter to detect the branch phase content of biphase gas and liquid flow flow, density and gas-liquid two-phase simultaneously, improved the precision and the real-time of Parameter Measurement of Gas-liquid Two-phase.Also can be used for the measurement of the oil-gas two-phase flow parameter of the low air void in the petroleum industry, with respect to existing multiple measuring method, characteristics of the present utility model are to solve the engineering survey problem with the ingenious combination of traditional single-phase flow measurement instrument.Use the combination of Venturi tube and vortex shedding flow meter and measure biphase gas and liquid flow flow, density and branch phase content simultaneously.Measurement is reliable, stable, precision is high, applied widely, easy for installation, volume is little.

Description of drawings

Below in conjunction with drawings and Examples the utility model is further specified.

Fig. 1 is a structural representation of the present utility model.。

The 1st, metering pipeline, the 2nd, mixed flow device, the 3rd, standard Venturi tube, the 4th, vortex shedding flow meter, the 5th, differential pressure pick-up, the 6th, temperature sensor, the 7th, A/D transition card, the 8th, computing machine

Embodiment

Restricting element selection standard Venturi tube in the utility model.After biphase gas and liquid flow to be measured entered metering pipeline 1, by mixed flow device 2, mixed flow device 2 mixes biphase gas and liquid flow became homogeneous flow earlier.Differential pressure pick-up 5 and the 3 supporting installations of standard Venturi tube.The differential pressure signal of standard Venturi tube 3 outputs changes the standard electric signal into through differential pressure pick-up 5 sends into computing machine 8 through A/D transition card 7 again.Vortex shedding flow meter 4 obtains the gas-liquid total volumetric flow rate of whole pipeline and changes flow signal into the standard electric signal sends into computing machine 8 through A/D transition card 7.Temperature sensor 6 is used for detecting the biphase gas and liquid flow temperature T and changes temperature signal into the standard electric signal sends into computing machine 8 through A/D transition card 7.In computing machine 8, be provided with memory module, store density and the data such as coefficient of flow of restricting element, perforated area of gas-liquid two-phase under different temperatures.Computing machine 8 is handled in real time, obtains the gas-liquid two-phase current density and divides phase content.

Realization gas-liquid two-phase measuring method for measuring is undertaken by following concrete steps:

(1) utilize vortex shedding flow meter to obtain the gas-liquid two-phase total volumetric flow rate q of pipeline _v, computing formula is as follows:

q _v＝Aξf (1)

In the formula:

A is the cross-sectional area of metering pipeline, and f is the pulse output number of vortex shedding flow meter, q _vBe the biphase gas and liquid flow total volumetric flow rate, ξ is the coefficient of flow of vortex shedding flow meter.Generally speaking, in specified flow range, ξ is a constant.

(2) the utility model adopts the standard knot fluid element, and measuring principle satisfies shellfish and makes great efforts equation and continuity

Equation is therefore according to Throttle Principle

$q_v=\mathrm{\α\ϵ}{A}_0\sqrt{\frac{2\mathrm{\Δp}}{\mathrm{\ρ}}}---\left(2\right)$

It is as follows to obtain gas-liquid two-phase hybrid density ρ computing formula:

$\mathrm{\ρ}=\frac{2{\mathrm{\α}}^2{A}_0^2{\mathrm{\ϵ}}^2\mathrm{\Δp}}{q_v^2}---\left(3\right)$

In the formula:

ρ is the biphase gas and liquid flow hybrid density of restricting element of flowing through, q _vObtained by vortex shedding flow meter, the differential pressure Δ p of restricting element place sampling pipe is obtained A by differential pressure pick-up ₀Be the restricting element perforated area, α is a standard Venturi tube coefficient of flow, when fluid Reynolds number during greater than critical Reynolds number, α is a constant, concrete numerical value is by experimental calibration, and ε is an expansibility factor, and its value is less than or equal to 1, for the incompressibility fluid, ε=1 is for the biphase gas and liquid flow of low air void, because gas holdup is very little, the biphase gas and liquid flow of this moment can be considered incompressible fluid, therefore accounts for ε=1.

(3) owing to the biphase gas and liquid flow hybrid density be:

ρ＝x ₁ρ ₁+(1-x ₁)ρ ₂ (4)

Obtaining gas-liquid two-phase by formula (4) divides phase content and separate phase flow rate computing formula as follows:

The rate that contains of gas phase is $x_1=\frac{\mathrm{\ρ}-{\mathrm{\ρ}}_2}{{\mathrm{\ρ}}_1-{\mathrm{\ρ}}_2}$

The rate that contains of liquid phase is x ₂=1-x ₁

The volumetric flow rate of gas phase is q _V1msm=x ₁q _v

The volumetric flow rate of liquid phase is q _V2msm=x ₂q _v

The mass rate of gas phase is q _M1=ρ ₁q _V1msm

The mass rate of liquid phase is q _M2=ρ ₂q _V2msmIn the formula:

ρ ₁, ρ ₂Be respectively the density of temperature gas phase and liquid phase when being T, temperature T is obtained by temperature sensor, x ₁, x ₂Be respectively the rate that contains of gas phase and liquid phase, q _V1msm, q _V2msmBe respectively the volumetric flow rate of gas phase and liquid phase, q _M1, q _M2Be respectively the mass rate of gas phase and liquid phase.

Claims (2)

1. low air void gas-liquid two-phase flow measuring apparatus based on standard Venturi tube and vortex shedding flow meter, it is characterized in that it has metering pipeline (1), on metering pipeline (1), be provided with mixed flow device (2), standard Venturi tube (3), vortex shedding flow meter (4), temperature sensor (6) successively, the supporting differential pressure pick-up (5) that is equipped with of standard Venturi tube (3), differential pressure pick-up (5), temperature sensor (6), vortex shedding flow meter (4) link to each other with A/D transition card (7), and A/D transition card (7) links to each other with computing machine (8).

2. the described a kind of low air void gas-liquid two-phase flow measuring apparatus based on standard Venturi tube and vortex shedding flow meter of claim 1 is characterized in that said vortex shedding flow meter adopts the liquid phase vortex shedding flow meter.

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