CN105783984A - Method and apparatus for measuring gas-liquid two-phase flow based on optical fiber probe method - Google Patents

Abstract

The present invention discloses a method and an apparatus for measuring the gas-liquid two-phase flow based on the optical fiber probe method. Based on the method and the apparatus, the phase content, the speed and the flow of each of the gas-phase flow and the liquid-phase flow can be recognized. Meanwhile, the overall average speed and the overall flow of the gas-phase flow and the liquid-phase flow can be recognized. The apparatus comprises a measuring tube (1), an optical fiber probe (2), a photoelectric conversion unit (3), a data acquisition and processing system (4), a control computer (5) and a differential pressure flowmeter (6).

Description

Utilize the method and apparatus that optical fiber probe method measures biphase gas and liquid flow

Technical field

The present invention relates to field of fluid measurement, specifically a kind of method and apparatus utilizing optical fiber probe method to measure biphase gas and liquid flow.This device may identify which each phase content of biphase gas and liquid flow, speed and flow and bulk flow velocity, flow.

Background technology

Engineering is widely present the flow phenomenon of two phase flow, wherein general with biphase gas and liquid flow.Such as in petroleum transportation pipeline, around hydroturbine rotor, the intracloud convection current of air etc., broadly fall into biphase gas and liquid flow flowing.Measured by two phase flow flow parameter, understand its characteristic and Changing Pattern, related scientific research, design and production tool are of great significance.Compared with single-phase flow, two phase flow owing to alternate there is mass transfer boundary is each, even chemical reaction, and in time, spatially variable at random, making the detection more complexity of such as each phase content, flow velocity, flow and the flow parameter such as overall rate, flow, difficulty is very big.Up to now, existing detection technique and method are built upon the detection means on single-phase sensor integration mostly, it is thus achieved that quantity of information little, and the overall permanence of two phase flow cannot be carried out real-time monitored description.Parameter and the form of expression that the measurement of biphase gas and liquid flow relates to are as follows:

1. flow

(1) mass flow of biphase gas and liquid flow:

G=G_g+G_l,

Wherein, G total mass flow rate；G_gAnd G_lRespectively gas phase and liquid phase quality flow.

(2) volume flow of biphase gas and liquid flow:

Q=Q_g+Q_l,

Wherein, Q total volumetric flow rate；Q_gAnd Q_lRespectively gas phase and liquid phase volume flow.

2. flow velocity

(1) gas-liquid divides phase velocity

$w_g=\frac{Q_g}{A_g};w_l=\frac{Q_l}{A_l},$

Wherein, w_gAnd w_lRespectively gas phase and liquid phase component velocity；A_gAnd A_lThe sectional area that respectively gas phase and liquid phase fluid pass through.

(2) gas-liquid divides phase superficial velocity

$w_{\mathrm{sg}}=\frac{Q_g}{A};w_{\mathrm{sl}}=\frac{Q_l}{A},$

w_sgAnd w_slRespectively gas phase and liquid phase superficial velocity；Actual internal area

A=A_g+A_l。

3. density

(1) flow density

${\mathrm{\ρ}}_f=\frac{G}{Q}.$

(2) real density

ρ=α ρ_g+(1-α)ρ_l,

Wherein, ρ_gAnd ρ_lRespectively gas phase and liquid phase fluid density；α is void fraction, also referred to as voidage.

4. void fraction

(1) void fraction (voidage)

$\mathrm{\α}=\frac{A_g}{A}.$

(2) filling-emptying model

$\mathrm{\β}=\frac{Q_g}{Q}.$

(3) mass gas content rate

$\mathrm{\χ}=\frac{{\mathrm{\β\ρ}}_g}{{\mathrm{\β\ρ}}_g+(1-\mathrm{\β}){\mathrm{\ρ}}_l}.$

Requirements at the higher level along with metering for two phase flow in commercial production, control aspect, it is necessary to exploitation one can measure each phase content, flow velocity and flow in acquisition biphase gas and liquid flow and the device of bulk flow velocity, flow simultaneously.

Optical fiber probe method becomes the new method of gas-liquid two-phase flow measurement, has highly sensitive, responds fast feature.Specifically the application principle in gas-liquid two-phase flow measurement is the light refractive index that utilizes gas-liquid two-phase medium different to detect the relative time that pulsatile flow field gas-liquid two-phase exists in the certain point gas-liquid of a certain local space.Its ratio is exactly point phase content of the local of this point.

Continuous print measures point mutually each phase velocity and the flow that can also obtain aforementioned biphase gas and liquid flow, if being equipped with multiple other kinds of sensor, it is achieved measurement in a closed series, then can obtain the flow parameter of complete biphase gas and liquid flow.

The present invention provides the method and apparatus of a kind of gas-liquid two-phase flow measurement based on optical fiber probe method.The method and device may identify which each phase content of biphase gas and liquid flow, speed and flow and bulk flow velocity, flow.

Summary of the invention

The present invention provides the method and apparatus of a kind of gas-liquid two-phase flow measurement utilizing optical fiber probe method.The method and device may identify which each phase content of biphase gas and liquid flow, speed and flow and bulk flow velocity, flow.Fig. 1 is the layout of the device utilizing optical fiber probe measurement biphase gas and liquid flow.Shown in figure, this device includes: measures pipeline (1), optical fiber probe (2), photoelectric conversion unit (3), data Collection & Processing System (4), control computer (5), differential pressure flowmeter (6).Its annexation is:

The periphery of the measurement pipeline (1) that optical fiber probe (2) flows from tested biphase gas and liquid flow inserts flow field；

Photoelectric conversion unit (3) connects optical fiber probe (1)；

Photoelectric conversion unit (3) connects data Collection & Processing System (4)；

Differential pressure flowmeter (1) is positioned in measurement pipeline (1), in the downstream of optical fiber probe (2)；

Control computer and connect optical fiber probe (2), photoelectric conversion unit (3), data Collection & Processing System (4).

Fig. 2 is the schematic diagram that optical fiber probe measures each phase content of biphase gas and liquid flow.Figure represents, inserts optical fiber probe (2) along measuring pipeline (1) wall.In the process measured, when biphase gas and liquid flow flows through optical fiber probe (2), if surrounding medium is gas, bubble (7) occurs, its refractive index is less than the refractive index of optical fiber probe, incident illumination (9) major part is reflected back (10), photoelectric conversion unit one high level (11) of output.If surrounding medium is liquid (8), its refractive index more than the refractive index of optical fiber probe, incident illumination major part be refracted in liquid (12) disappear, the photoelectric conversion unit that is connected with optical fiber probe exports a low level (13).So, along with optical fiber probe alternately contacts with gas-liquid, namely photoelectric conversion unit exports the voltage signal converted in time.This continuous dynamic analog voltage signal enters computer after data collecting system, becomes discrete dynamic digital voltage signal, is computed processing the local that can obtain probe position place and divides phase content.

Accompanying drawing explanation

Fig. 1 is the layout of the device utilizing optical fiber probe measurement biphase gas and liquid flow；In figure, 1 measures pipeline, 2 optical fiber probes, 3 photoelectric conversion units, 4 data Collection & Processing Systems, 5 control computer, 6 differential pressure flowmeters.

Fig. 2 is the schematic diagram of each phase content utilizing optical fiber probe measurement biphase gas and liquid flow；In figure, 7 bubbles, 8 liquid, 9 incident illuminations, 10 reflection light, 11 high level, 12 it is refracted to light in liquid, 12 low levels.

Detailed description of the invention

Structure and the principle of the method and apparatus utilizing optical fiber probe measurement biphase gas and liquid flow that the present invention proposes is further illustrated with a specific embodiments.This device is for measuring each phase content of Air-C_2H_2 Flame, speed and flow and bulk flow velocity, flow.Parts composition in this device is identical with Fig. 1 with annexation.

In detailed description of the invention,

Measuring the cross section of pipeline (1) for circular, to be 1m, internal diameter for length be 50mm, wall thickness 10mm, material is lucite.Horizontal positioned.Circumferentially by installing hole, aperture 3mm；

Optical fiber probe (2) diameter is 3mm, and probe tip is long is 10mm, circular cone needle-like sapphire, is followed by optical fibers.The part steel thimble inserting test section at probe leading portion seals, at the standard electric cable end that the fibre-optic other end is, to insert photoelectric conversion unit (3)；

Data Collection & Processing System (4) measures the voltage of empty photoelectric conversion unit (3)；

Control computer (5) connection, optical fiber probe (2), photoelectric conversion unit (3), data Collection & Processing System (4), operation, the continuous print sampling interval of specified data collection simultaneously and the system of process (4), thus obtaining point phase velocity of Air-Water；

The downstream of pipeline (1) measured by differential pressure flowmeter (7), measures total flow.

Claims (1)

1. one kind utilizes the method and apparatus that optical fiber probe method measures biphase gas and liquid flow, this device includes: measuring pipeline (1), optical fiber probe (2), photoelectric conversion unit (3), data Collection & Processing System (4), control computer (5), differential pressure flowmeter (6), its annexation is:

The periphery of the measurement pipeline (1) that optical fiber probe (2) flows from tested biphase gas and liquid flow inserts flow field；

Photoelectric conversion unit (3) connects optical fiber probe (1)；

Photoelectric conversion unit (3) connects data Collection & Processing System (4)；

Differential pressure flowmeter (1) is positioned in measurement pipeline (1), in the downstream of optical fiber probe (2)；

Control computer and connect optical fiber probe (2), photoelectric conversion unit (3), data Collection & Processing System (4).