CN1023152C - Gas-liquid phase pipe flow rate measuring method and device - Google Patents

Abstract

The present invention relates to a force-induced hydraulic chamber-amplified downdraught engine which belongs to the field of hydraulic drive mechanisms. Staged energy amplification is carried out through a multi-stage machine set composed of a hydraulic motor and an oil pump which have the same power. After energy diffluence, a part of energy enters the hydraulic motor to do work to as to convert pressure energy into mechanical energy, the other part flows back to an energy accumulator and uses the energy of the energy accumulator as a power source to start the engine so that the engine can continuously output energy and do work on a working surface. The engine can substitute various resources and other engines in a wide range and is an energy-saving product.

Description

Gas-liquid phase pipe flow rate measuring method and device

The present invention relates to measure in the measurement of fluid flow field a kind of method and apparatus of gas (vapour) liquid phase pipe flow volumetric flow rate.

Gas, liquid two-phase flow measurement are the problems that urgently will solve in the engineering fields such as chemical industry, the energy, oil.Measure in the gas bigger with the single-phase flow nature difference, the liquid traffic flow in the prior art, the method that can satisfy the engineering application requirements that be widely used and unique is a partition method.Promptly utilize gas, liquid density difference character earlier, they are separated in bulk container or other forms of separation vessel, then with single-phase flow flow rate test method difference independent measurement gas, flow quantity.Obvious this method needs separation vessel, single-phase gas, flow quantity test macro, and the pipe system of switching runner, various level control (LC) equipment etc., total system is huge, complicated.As realizing that robotization faces a series of difficulties.In order to address this problem, in engineering reality, the single-phase flow flow-measuring method also is expanded sometimes and is used for gas, liquid two-phase flowmeter, but except few flow characteristics gas close with single-phase flow character, liquid flowed, most diphasic flow flow measurements then can't realize with the method.This be because, for long pipeline (more than ten meters), the moving overwhelming majority of gas, liquid two-phase is intermittent, and the Liquid Flow in the long tube is very compressible, so intermittence is flowing in the big ups and downs that the pressure disturbance of measuring sensor place generation will cause flowing velocity.Therefore, it is mobile greatly that the single-phase flow method is not suitable for this resting period variation.Thereby gas, the liquid that also just can not be used for the long pipeline of actual engineering flow.

In order to address this problem, the gas of new development, liquid two-phase measuring method are correlation methods, promptly obtain on the straight pipeline with two gas, liquid two-phase void fraction sensor, generally be on the vertical pipeline, each phase cross section content (void fraction or void fraction) on two tube sections of upstream and downstream, then upstream and downstream void fraction signal is carried out correlation analysis, obtain average speed stream, obtain gas, the long-pending flow of liquid according to void fraction and mean flow rate.Referring to Xu Lingan: " related flow measurement technology ", publishing house of University Of Tianjin 1988.SCOTT，R·W·W：New Flow Measurement in the mid 80S international conference：a review，Measurement+control，Flow Measurement Special Issue，June 1986，PP.75～79。But this method can't be measured the separated flow structure at present.This fluidal texture is present in every other gas except that complete dispersion train flow pattern (bubble flow or mist flow), the liquid two-phase flow pattern, promptly is present in nearly all engineering actual flow.In this fluidal texture between the two-phase velocity contrast very big, phase cross section share also is difficult to accurately measure.Referring to: Hagiwara, Y:Simultaneous Measurement of Liguid Film Thickness, Wall Shear Stress and Gas Flow Turbulence of Horizontal Wavy Two-Phase Flow; Int.J.Multiphase Flow; Vol 15, No.3, PP.421～431,1989.In addition, the relevant speed that correlation analysis obtained generally is structure-borne speed rather than the potpourri average velocity in the two-phase flow, and this method is only applicable to the flow measurement in the VERTICAL TUBE.In a word, except ancient partition method, without any simpler, and can satisfy that practical engineering application requires, the relatively gas in the long tube, the method for liquid phase pipe flow volume flow measurement in the prior art.

Purpose of the present invention and task provide a kind of simple in structure, and measuring accuracy satisfies the measurement mechanism and the method for engineering application requirements, realize that the long-pending flow direct-on-line of gas, liquid of long gas, liquid two-phase pipeline is measured.

The present invention is achieved in that its measurement mechanism comprises the measurement pipeline, upstream and downstream void fraction sensor, and signal processing system and data acquisition and arithmetic system are formed.Described measurement pipeline is a special pipeline that is formed by connecting by go up a slope pipe and heavy grade descending pipe, and described upstream and downstream void fraction sensor is installed near the upward slope pipe in pipe junction, upper and lower slope.Utilize above-mentioned measurement mechanism to make the interior generation of upward slope pipe intermittent mobile, the liquid film behind the blocking-up liquid plug is mobile, and the liquid plug forward liquid level that formation has consistent velocity flow profile in the upward slope pipe; By detecting the existence and the void fraction thereof of liquid plug, measure gas, liquid two-phase potpourri speed, liquid plug liquid cross-sectional share and liquid plug occupy the time share of sensor; And, can record gas, liquid two-phase volume flow by to the restriction of flowing through the longest liquid film length in junction and the liquid film flow rate calculation is gentle, the correction of liquid mean flow rate.

The present invention compared with prior art, not only have simple in structure, security of system is reliable, characteristics such as measurement range is wide, and owing to utilized gas in the special shape pipeline, liquid two-phase dynamic characteristic, thereby solved the two phase flow pattern variation effectively, the separated flow structure is difficult to measure, structure-borne speed easily and the potpourri mean flow rate obscure, difficulties such as speed, pressure big ups and downs have realized the gas of long gas, liquid two-phase pipeline, the direct-on-line measurement of the long-pending flow of liquid effectively.This invention also taken into full account the flow characteristics of two-phase flow itself and engineering use in gas, phenomenon that the liquid two-phase flow pattern is changeable, the survey parameter necessary calculating and correction have been carried out, thereby compared with prior art, improved measuring accuracy, made measurement result can satisfy the practical application of engineering fully.

Concrete structure of the present invention and implementation method are provided by following accompanying drawing, embodiment and computing formula.

Accompanying drawing is a structural principle synoptic diagram of the present invention.

Describe the concrete enforcement of this invention in detail below in conjunction with accompanying drawing.

Entire measuring device comprises a special pipeline that is formed by junction [13] and heavy grade descending pipe [10] by the pipe [9] that goes up a slope, be installed in two void fraction sensors A in upstream and downstream [1] and B[2 near the upward slope pipe in junction], and signal processing system [11] and data acquisition and arithmetic system [12].Wherein, gradient the best of the pipe [9] that goes up a slope is 0.25～0.4, and its length can be 4～8 meters; Gradient the best of descending pipe [10] is 0.5～1, and caliber D is identical with the moving pipeline of institute flow measurement.Sensors A and B adopt bubble flow void fraction sensor, available any existing sound, light, electric transducer, and the distance of two upstream and downstream sensors is 4～8D.Bubble flow void fraction test macro, signal Processing amplification and data acquisition and arithmetic system are prior art.

Utilize above-mentioned measurement mechanism and system, in the flow range of required survey, make to produce intermittent flowing in the pipe that goes up a slope, it is made up of the liquid plug [5] that contains or do not contain minute bubbles and the air pocket [6] of a section interruption, has liquid film [8] to flow under the air pocket.After a liquid plug was through junction [13], liquid film subsequently was flowing in and can not continues under the action of gravity to go up a slope and most of liquid film is prevented from, and can not pass through the junction.This makes us need not measure the separated flow structure in intermittent the flowing, thereby has avoided indeterminable problem in the prior art.After a liquid plug is through the junction, liquid film refluence [7] subsequently makes near there not being liquid to exist in the raise pipe of junction, when making this section of the liquid plug process upward slope pipe that arrives subsequently, formed a liquid plug forward liquid level [3] with consistent velocity flow profile, its translational speed is exactly potpourri mean flow rate U _M, and the hydrodynamics of it and liquid is irrelevant.And liquid plug afterbody [4], promptly the translational speed at air pocket top then is intermittent flow structure-borne speed U _TThe liquid plug be one be similar to even bubble flow contain the minute bubbles fluid column, near two bubble flow void fraction sensors A [1] and sensor B[2 are installed on the upward slope pipe of junction], the existence and the void fraction (1-R thereof of detection liquid plug _S), then can measure gas, liquid two-phase potpourri average velocity U _M, liquid plug liquid cross-sectional share R _SAnd the liquid plug occupies the time share T of sensor _SiAnd then, then can accurately obtain gas, the long-pending flow of liquid by to the restriction of the longest liquid film length that flows through junction [13] and the correction of liquid film flow rate calculation and mean flow rate.

That is: potpourri mean flow rate: U _M=L _AB/ (T _DB-T _DA) (1)

Intermittent flow structure-borne speed: U _T=L _AB/ (T _LB-T _LA) (2)

The liquid volume flow: $Q_L\mathrm{=(1/T)［A（U}{}_M\mathrm{+u)}\underset{T}{\overset{}{\mathrm{\Σ}}}{T}_{\mathrm{s1}}R{}_s+\underset{T}{\overset{}{\mathrm{\Σ}}}{Q}_F\mathrm{i\; ］}$ （3）

Volumetric flow of gas: Q _G=A(U _M+ u)-Q _L(4)

In the above-listed formula, L _ABIt is distance between the two sensors of upstream and downstream; T _D, T _LBe respectively that the liquid plug arrives and leave certain sensor time; A is that pipeline section is long-pending; T _Si=T ⁱ _LA-T ⁱ _DABe the time interval that i liquid plug occupies sensors A in Measuring Time T, Q _FiBe i liquid plug heel with the liquid film flow, u is the modified value to mean flow rate.

Be to flowing through the longest liquid film length in junction and the calculating of liquid film flow and the modification method of mean flow rate below.

Ignore liquid film all friction force effects of flowing, and substitute hydrostatic force item on the circular pipe consideration tube section with imaginary square pipe, then liquid film is flowing in x=U _TThe equation of momentum of (z is that tubular axis is to the mark of sitting quietly) is on the moving moving axes of t-z:

[（C ²R ² _S/R ³ _F）-0.9（Cosβ/Fr）]dR _F＝（Sinβ/Fr）·d（x/D） （5）

In the following formula, C=U _T/ U _M-1, R _FBe liquid film sectional area share; β is the pipe elevation angle of going up a slope; Fr=U ² _M/ gD, D are calibers.The integration following formula has:

1/2 C ²R ² _s[（1/R ² _F）-（1/R ² _s）]＝0.9（Cosβ/Fr）（R _s-R _F）+（Sinβ/Fr）·（L _F/D） （6）

The continuity that flows according to liquid film: liquid film flow velocity U _F=[1+C-(CRs/R _F) U _M; At junction U _F=0, the expression liquid film flows through the junction to be finished, and R is arranged this moment _F=CRs/(1+C), corresponding liquid film length L _FOFor flowing through the longest liquid film length in junction:

L _FO/D＝[1/2（1+2C）Fr-0.9Cosβ·（Rs/1+C）]/Sinβ （7）

The liquid plug through the junction after, the liquid film sectional area and the speed that flow through the junction subsequently can't be surveyed.But its share that accounts for total flow quantity be can not ignore again, particularly for flow at high speed.One length L _F＜L _FOLiquid film flow through the fluid flow Q of junction _FShould be:

Q _F＝A∫ ^to _oR _FU _Fdt

Consider U _TThe R that dt=dx and formula (6) obtain _FApproximate expression, can have:

$Q_F\mathrm{=AD·\; ｛（CR}{}_s\mathrm{·Fr/Sin\beta )［}\sqrt{\mathrm{(C}{}^2{\mathrm{+(1.8Cos\beta )/Fr+(2Sin\beta /Fr)·L}}_f\mathrm{/D}})$

$-\sqrt{\mathrm{(C}{}^2\mathrm{+1.8Cos\beta /Fr\; ］}}{\mathrm{-(CR}}_s\mathrm{/1+C)·(L}{}_F\mathrm{/D)\}}$

$\mathrm{u=}\sqrt{\mathrm{(po/［\alpha }{}_G\mathrm{(1-\alpha }{}_G\mathrm{)p}{}_L\mathrm{］）}}{\mathrm{·［\alpha }}_G\mathrm{（1／2L}{}_{s}R{}_s\rho {}_{\mathrm{Lg}}\mathrm{Sin\beta )/Po\; ］}$ （8）

If L _F＞L _FO, L in the following formula then _FShould be by L _FOSubstitute.

When a liquid plug leaves when going up a slope pipe [9] by junction [13], the fluid column hydrostatic pressing that the liquid plug is added in upstream line constantly diminishes, and making flows quickens.And liquid plug forward liquid level [3] translational speed of surveying is to flow to quicken gas, liquid mixture speed before, should equal the speed that the junction is flow through at liquid plug middle part so liquid plug [5] flows through the average velocity of junction.

Thinking flows in the whole pipeline is that mixed uniformly gas, liquid two-phase are moving, and think that length of pipeline is greater than pressure propagation length, then use flow relational expression on the equation group characteristic line of the compressible unsteadiness of simple wave zone one dimension, can calculate the mobility that flows through the junction in the fluid plug middle part liquid plug forward liquid level speed U that equals to test the speed _MWith following modified value u sum:

$\mathrm{u=}\sqrt{\mathrm{(po/［\alpha }{}_G\mathrm{(1-\alpha }{}_G\mathrm{)p}{}_L\mathrm{］）}}{\mathrm{·［\alpha }}_G\mathrm{（1／2L}{}_{s}R{}_s\rho {}_{\mathrm{Lg}}\mathrm{Sin\beta )/Po\; ］}$ （9）

Wherein: P _OBe piping system pressure; ρ _LBe fluid density; L _SBe the slug length that tests the speed, work as L _SWhen surpassing the upward slope length of tube, use the upward slope length of tube and replace.In addition, void fraction α _GThe ratio that should be equivalent to all air pocket total lengths and pipeline total length, available following formula calculates:

α _G＝Q _G/（Q _L+Q _G） （10）

Claims (4)

1, a kind of measurement mechanism of measuring gas, liquid phase pipe flow flow, it comprises measuring channel, upstream and downstream void fraction sensor, signal processing system (11) and data acquisition arithmetic system (12), it is characterized in that described measuring channel is to be formed by connecting by go up a slope pipe (9) and heavy grade descending pipe (10) by one, described upstream and downstream sensors (1), (2) are installed near the upward slope pipe in upper and lower pipe junction, slope (13).

2, according to the described measurement mechanism of claim 1, it is characterized in that described upward slope pipe (9) gradient is 0.25-0.4, descending pipe (10) gradient is 0.5-1, the upward slope length of tube is a 4-8 rice.

3, according to claim 1 or 2 described measurement mechanisms, it is characterized in that described upstream and downstream sensor is a bubble flow void fraction sensor, its spacing is 4-8D

4, a kind of measuring method of measuring gas, liquid phase pipe flow flow, it is characterized in that the special pipeline that is formed by connecting by go up a slope pipe (9) and heavy grade descending pipe (10) with one, make and produce intermittent flowing in the pipe that goes up a slope, stream membrane flow behind the blocking-up liquid plug, and form liquid plug forward liquid level (3), measure gas, liquid two-phase potpourri average velocity U with consistent velocity flow profile _M, liquid plug liquid cross-sectional share R _sAnd the liquid plug occupies the time share T of sensor _Si, and by to flowing through the longest liquid film length L in junction _FORestriction and liquid film flow Q _FThe modified value u of gentle, the liquid mean flow rate of calculating, according to the therapeutic method to keep the adverse qi flowing downward, the long-pending flow formula of liquid, can obtain gas, the long-pending flow of liquid:

The liquid volume flow: $Q_L\mathrm{=(1/T)［A（U}{}_M\mathrm{+u)}\underset{T}{\overset{}{\mathrm{\Σ}}}{T}_{\mathrm{s1}}R{}_s+\underset{T}{\overset{}{\mathrm{\Σ}}}{Q}_F\mathrm{i\; ］}$

Volumetric flow of gas: Q _G=A(U _M+ u)-Q _L

Q wherein _F, u calculates by following formula respectively:

$Q_F\mathrm{=AD·\; ｛（CR}{}_s\mathrm{·Fr/Sin\beta )［}\sqrt{\mathrm{(C}{}^2{\mathrm{+(1.8Cos\beta )/Fr+(2Sin\beta /Fr)·L}}_f\mathrm{/D}})$

$-\sqrt{\mathrm{(C}{}^2\mathrm{+1.8Cos\beta /Fr\; ］}}{\mathrm{-(CR}}_s\mathrm{/1+C)·(L}{}_F\mathrm{/D)\}}$

$\mathrm{u=}\sqrt{\mathrm{(po/［\alpha }{}_G\mathrm{(1-\alpha }{}_G\mathrm{)p}{}_L\mathrm{］）}}{\mathrm{·［\alpha }}_G\mathrm{（1／2L}{}_{s}R{}_s\rho {}_{\mathrm{Lg}}\mathrm{Sin\beta )/Po\; ］}$

Work as L _F＞L _FOThe time, get L _F=L _FO

L _FO＝｛[1/2（1+2C）Fr-0.9Cosβ·（Rs/1+C）]/Sinβ｝·D

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