CN1076777A - The measuring method of gas (vapour) liquid two-phase amount and mass gas content rate - Google Patents

Abstract

The invention provides a kind of impulse force characteristic and differential pressure characteristic according to target type meter, utilize single target type meter, one cover differential pressure measurement instrument is carried out the flow of gas (vapour) gas-liquid two-phase liquid and the measurement of mass gas content rate, can be used for the measurement of gas (vapour) gas-liquid two-phase liquid of multiple medium, the experimental result of air-water shows that measuring error is less than 4%.

Description

The measuring method of gas (vapour) liquid two-phase amount and mass gas content rate

The present invention relates to a kind of measuring method of flow and mass gas content rate of two-phase fluid.

It is generally acknowledged that flow and the mass gas content rate of measuring two-phase fluid must adopt two covers or the above measurement instrument of two covers, i.e. multiple measurement instrument could realize, but the required instrument of this measuring method is more, the cost height, expense is big, and complexity is installed, and therefore is restricted in industrial application.Disclose a kind of method of utilizing single orifice plate to carry out two-phase flow measurement among the CN1035364A, this aspect simplified measurement instrument is being a very much progress, and required transmitter also is minimum in the existing at present method.But the weak point of this method is will be by tabling look-up to determine the x value, on-line measurement is become difficult to achieve, to compare with other parameter be microscopic quantity to the two-phase flow pulse characteristic that utilizes of this method in addition, is easy to be subjected to the influence of various factors, and measuring accuracy is reduced.

The objective of the invention is to avoid the weak point of above-mentioned technology.On instrument structure, this method only needs an instrument, simpler than general combined method, and reduce by a testing pressure, though Duo a transmitter (target power transmitter) than CN1035354A, introduced bulk parameter-differential pressure, help improving the antijamming capability and the measuring accuracy of instrument, and need not table look-up during data processing, be easy to realize on-line measurement.This method is applicable to the measurement of the two-phase flow of multiple gas-liquid working medium.

The present invention includes following several steps: 1. with a target type meter (or combination of the fluid resistance measuring sensor of Any shape and dynamometry transmitter) as measuring sensor.2. respectively bore a hole (two holes are on same horizontal line) on the tube wall before and after the target sheet of target type meter, as shown in Figure 1, differential pressure is obtained from these two holes.3. utilize a differential pressure transmitter to measure this differential pressure.4. the suffered impulse force of target sheet is measured with the target power transmitter, and the general and target sheet of this transmitter is fitted together.5. all measured signals enter microcomputer by the A/D change-over panel.Microcomputer is measured signal, and according to the target power F, the differential pressure △ P that record, pressure P, temperature T (situation to normal temperature and wet saturated steam does not then need thermometric), utilizes formula (1), (2) to try to achieve the flow and the mass gas content rate of two-phase fluid.

$G_m=\frac{B_2{G}_C{\mathrm{-B}}_1{G}_b}{A_1{\mathrm{-A}}_2}\mathrm{(1)x=}\frac{A_2{G}_C{\mathrm{-A}}_1{G}_b}{B_1{G}_b{\mathrm{-B}}_2{G}_C}\mathrm{(2)}$

$G_a\mathrm{=\; \epsilon a}{}_{a}A{}_0\sqrt{\mathrm{2\; △P\; \rho }{}_0}{\mathrm{,A}}_1\mathrm{=\; \epsilon K}{}_C\sqrt{\rho {}_{\omega }\mathrm{/\rho }{}_1}{\mathrm{,\; B}}_1\mathrm{=1-A}{}_{1}G{}_b\mathrm{=a}{}_{b}A\sqrt{\mathrm{2F\rho }{}_0}{\mathrm{,\; <figure-callout\; id="2"\; label="A"\; filenames="921083599\_DRIMG1.png"\; state="\{\{state\}\}">A</figure-callout>}}_2\mathrm{=K}{}_b\sqrt{\rho {}_0\mathrm{/\rho }{}_1}{\mathrm{,\; <figure-callout\; id="2"\; label="B"\; filenames="921083599\_DRIMG1.png"\; state="\{\{state\}\}">B</figure-callout>}}_2\mathrm{=1-A}{}_2$

G _m-two-phase fluid mass rate (Kg/s)

α _c-differential pressure characteristic discharge coefficient

α _b-impulse force characteristic discharge coefficient

A ₀Circulation area (the m at-target sheet place ²)

Circulation area (the m of A-pipeline ²)

The g-E

ρ _g-density of gas phase (Kg/m ³)

ρ _l-density of liquid phase (Kg/m ³)

△ P-differential pressure (Pa)

F-target power (N)

K _c-two-phase differential pressure coefficient

K _b-two-phase impulse force coefficient

The x-mass gas content rate

Purpose of the present invention can also reach by following steps:

Target type meter can be the combination of fluid resistance measuring sensor (lacking plate, porous plate, reticular lamina, cylinder etc. as plectane, circle) with the dynamometry transmitter of Any shape.

Computing formula (1), (2) can be the experimental formula replacement of independent variable in order to △ P, F, or x calculates G with experimental formula _mCalculate with formula (1).

Microcomputer can be replaced by single card microcomputer or other processor.

The process flow diagram that Fig. 2 measures for the invention process.Among the figure, the 1-air inflow is measured turbine, 2-mixed-phase device, 3-mass flowmeter, 4-pressure-measuring-point, 5-temperature point, 6-differential pressure measuring point, 7-target type meter, 8-regulating working conditions valve, 9-microcomputer measuring system.

The invention will be further described in conjunction with the embodiments

Embodiment

Use method of the present invention and measure air-water two phase flow and mass gas content rate.

The process flow diagram that Fig. 2 measures for the invention process, target type meter is contained on the horizontal pipe, air-water two-phase flow flows in pipeline, the two-phase flow total flow equals single-phase water inlet and single-phase charge flow rate sum, internal diameter of the pipeline D=50mm, select commercially available pneumatic target type meter for use, circular plate type target sheet, target sheet diameter d=35mm, ratio β=0.7 of target sheet diameter and internal diameter of the pipeline, differential pressure is recorded by two pressure points before and after the target sheet, selects 1151 higher capacitance differential pressure cells of sensitivity and precision and pressure transmitter measurement differential pressure and pressure for use, and temperature number is the platinum resistance thermometer sensor, thermometer measure of BA1 (situation to normal temperature and wet saturated steam does not then need thermometric) with calibration.The differential pressure that records, pressure, target power, temperature signal are sent in A/D converter, the microcomputer through transmitter, and microcomputer goes the rounds to detect to each amount, and every sampling 100 times utilizes following formula to average, and this average is as an experimental point.

In the formula A represent to be measured, A _iBe i the measured value of A to be measured.

For realizing on-line measurement, the density of gas, liquid two-phase utilizes pressure, temperature to return out calculating formula respectively according to measurement range, can directly calculate each phase density after recording pressure, temperature.In each phase density of obtaining and differential pressure, target power substitution formula (1), (2), calculate give vent to anger (vapour) liquid two-phase amount and mass gas content rate.After microcomputer disposes to data, flow and mass gas content rate can be shown, write down as requested automatically, and the measured value of each parameter to be measured can be provided.

Calculated example 1:

Known: differential pressure △ P=1601.9Pa

Target power F=2.867N

Pressure P=0.201 * 10 ⁸Pa

Temperature T=290.28K

Ask: air-water two-phase fluid flow and mass gas content rate.

In the present embodiment measurement range, the density of air, water can be calculated with following formula:

ρ _g＝1.0009 (P)/(RT)

ρ _l＝-5.4×10 ^-3（T-273.15） ²+1.35×10 ^-2（T-273.15）+1000.29

The unit of pressure P is Pa in the formula, temperature T be K, R=287.12 is the air gas constant.

Internal diameter of the pipeline D=50mm

Target sheet diameter d=35mm

α _b＝0.5166，α _c＝0.7055，K _b＝2.65，K _c＝-1.43

1. according to P, T asks each phase density:

ρ _g＝2.445 Kg/m ³

ρ _l＝998.87 Kg/m ³

2. ask G according to formula (1) _m, computation process is omitted,

G _m＝0.07023 Kg/s＝252.83Kg/h

3. ask x according to formula (2), computation process is omitted,

x＝0.8723

Single-phase measured discharge is 246.05Kg/h, and error is 2.75%.

Single-phase actual measurement mass gas content rate is 0.8997, and error is 3.04%.

Calculated example 2:

Known: differential pressure △ P=1416.7Pa

Target power F=2.954N

Pressure P=0.209 * 10 ⁶Pa

Temperature T=291.22K

Ask: air-water two-phase fluid flow and mass gas content rate.

In the present embodiment measurement range, the density of air, water can be calculated with following formula:

ρ _g＝1.0009 (P)/(RT)

ρ _l＝-5.4×10 ^-3（T-273.15） ²+1.35×10 ^-2（T-273.15）+1000.29

The unit of pressure P is Pa in the formula, temperature T be K, R=287.12 is the air gas constant.

Internal diameter of the pipeline D=50mm

Target sheet diameter d=35mm

α _b＝0.5166，α _c＝0.7055，K _b＝2.65，K _c＝-1.43

1. according to P, T asks each phase density:

ρ _g＝2.538Kg/m ³

ρ _l＝998.68Kg/m ³

2. ask G according to formula (1) _m, computation process is omitted,

G _m＝0.09209 Kg/s＝331.53Kg/h

3. ask x according to formula (2), computation process is omitted,

x＝0.6552

Single-phase measured discharge is 321.26Kg/h, and error is 3.20%.

Single-phase actual measurement mass gas content rate is 0.6740, and error is 2.97%.

Method of the present invention only needs a target type meter instrument structure simple, low price, and the measuring accuracy height can be used for the measurement of the two-phase flow of multiple gas-liquid working medium, also can be used for the measurement of the flow and the pressure of monophasic fluid.

Claims (5)

1, a kind of is utilized the flow of target type meter measurement gas (vapour) gas-liquid two-phase liquid and the method for mass gas content rate, can produce differential pressure △ P during the target sheet that it is characterized in that utilizing two-phase fluid to flow through target type meter and to these two characteristics of impulse force F of target sheet, with pressure P and temperature T, set up two equations relevant with flow and mass gas content rate, therefrom separate explicit expression (1), (2) of outflow and mass gas content rate, all the collection of parameter is finished with microcomputer and A/D converter with processing.

$G_m=\frac{B_2{G}_C{\mathrm{-B}}_1{G}_b}{A_1{\mathrm{-A}}_2}\mathrm{(1)x=}\frac{A_2{G}_C{\mathrm{-A}}_1{G}_b}{B_1{G}_b{\mathrm{-B}}_2{G}_C}\mathrm{(2)}$

$G_a\mathrm{=\; \epsilon a}{}_{a}A{}_0\sqrt{\mathrm{2\; △P\; \rho }{}_0}{\mathrm{,A}}_1\mathrm{=\; \epsilon K}{}_C\sqrt{\rho {}_{\omega }\mathrm{/\rho }{}_1}{\mathrm{,\; B}}_1\mathrm{=1-A}{}_{1}G{}_b\mathrm{=a}{}_{b}A\sqrt{\mathrm{2F\rho }{}_0}{\mathrm{,\; A}}_2\mathrm{=K}{}_b\sqrt{\rho {}_0\mathrm{/\rho }{}_1}{\mathrm{,\; B}}_2\mathrm{=1-A}{}_2$

G _m--two-phase fluid mass rate (kg/s)

x _c--differential pressure characteristic discharge coefficient

α _b--impulse force characteristic discharge coefficient

A _o--the circulation area (m at target sheet place ²)

Circulation area (the m of A--pipeline ²)

The g--E

ρ _g--density of gas phase (kg/m ³)

ρ ₁--density of liquid phase (kg/m ³)

△ P--differential pressure (Pa)

F--target power (N)

K _c--two-phase differential pressure coefficient

K _b--two-phase impulse force coefficient

The x--mass gas content rate

2,, it is characterized in that used target type meter can be the combination of fluid resistance measuring sensor (plectane, circle lack plate, porous plate, reticular lamina, cylinder etc.) with the dynamometry transmitter of Any shape according to the described method of claim 1.

3,, it is characterized in that formula (1), (2) are is the G that the experimental formula of independent variable is represented with △ P, F according to the described method of claim 1 _m, the explicit shape of x, or x represents G with experimental formula _mRepresent with formula (1).

4,, it is characterized in that differential pressure passes through before and after the target sheet that perforate obtains on the tube wall according to the described method of claim 1.

5,, it is characterized in that microcomputer can be replaced by single card microcomputer or other processor according to the described method of claim 1.

Images