CN102914326A - Measuring method for high-pressure steam-water two-phase fluids - Google Patents

Abstract

The invention provides a measuring method for high-pressure steam-water two-phase fluids. The measuring method includes: using a flow divider for controlling the proportion of the high-pressure steam-water two-phase fluids, mounting a steam flow meter and a water flow meter at an upper port and a lower port of a separator respectively, and enabling the fluids flowing through the steam flow meter and the water flow meter to flow into a main loop in a mixed manner finally; and adjusting the pressure difference between the main loop and a branch loop by the aid of throttling devices of the main loop and the branch loop, measuring the flow dividing coefficient on the theoretical basis in a laboratory, scheduling the flow dividing coefficient by a 9T/h gas once-through boiler during heavy oil thermal recovery, and confirming the flow dividing coefficient finally. A measuring device comprises the flow divider and a separation system mounted on a horizontal steam-water two-phase fluid pipeline, the main pipe wall is provided with six flow dividing holes, an annular collecting chamber is arranged outside the main pipe wall and used for collecting the fluids flowing out of the flow dividing holes, a small separator is connected with the annular collecting chamber, the steam flow meter and the water flow meter are mounted at the top and at the bottom of the separator respectively, and outlets of the steam flow meter and the water flow meter are connected with the throttling device simultaneously and are connected to the lower end of the main loop throttling device finally.

Description

A kind of measuring method for high pressure vapour-water two-phase fluid

Technical field

The present invention relates to the fields of measurement of pipeline inner high voltage vapour-water two-phase flow, the particularly measurement of the steam injection in a kind of heavy crude heat extraction process, the method is precisely reliable, and is very practical.

Background technology

Extracting and separating method is a kind of common technology in multiphase flow measurement, can be with the polyphasic flow of the smaller large flow of measurement device by shunting.Chinese patent ZL98113068.2 discloses a kind of two-phase flow measurement method, the method is by proportional one two-phase fluid that distributes from two-phase flow, then after being isolated into monophasic fluid, use the single-phase flow flowmeter measurement and go out each phase flow rate, determine again each phase total flow of tested two-phase flow according to shunt ratio, this method is subjected to the impact of shunt ratio precision, shunt ratio is more constant, the total flow measuring accuracy is higher, equally, when measuring the two-phase flow phase content, also must guarantee the representativeness of sampling sample, in order to improve sampling precision, improve the representativeness of sample, before the sampler of being everlasting polyphasic flow is mixed or the rectification processing, although it is constant and representative to improve like this split ratio of sample under principle and laboratory condition, but be subjected to the impact of measuring media degree of purity and environment temperature very large after being applied to site environment, be not easy to industrial applications.

Measuring method provided by the invention, cast aside traditional extracting and separating method, the sample shunt ratio of namely taking a sample and representational strict demand, but derive by theoretical formula, determine split ratio, with the metering of steam injection in the steam measurement device solves heavy crude heat extraction process of small size very, the production application effect is extremely remarkable.

Summary of the invention

Order of the present invention is: the measuring method for high pressure vapour-water two-phase fluid provided by the invention, derive by theoretical formula, determine split ratio, with the metering of steam injection in the steam measurement device solves heavy crude heat extraction process of small size very, the production application effect is extremely remarkable.

The object of the present invention is achieved like this: a kind of measuring method for high pressure vapour-water two-phase fluid, derive by theoretical formula, determine split ratio, the diverting coefficient that demarcation is good is brought equation into and is obtained the parameters such as the flow of heavy crude heat extraction steam injection, mass dryness fraction, method is precisely reliable, and implementation step is as follows:

Step 1 formula calculates:

1) record total flow and the shunt volume scale relation of steam, water:

$M_s=\frac{M_{\mathrm{ss}}}{K_s}---\left(1\right)$

$M_w=\frac{M_{\mathrm{sw}}}{K_w}---\left(2\right)$

M _s: total steam flow;

M _w: total liquid phase flow;

M _Ss: by the steam diversion amount of steam-flow meter;

M _Sw: by the liquid phase shunt volume of water ga(u)ge;

K _s: the steam diversion coefficient;

K _w: the separating liquid coefficient.

Learn the shunting constant K from equation (1) and (2) _sAnd K _wRepresent the ratio that major loop flows to sampling loop, i.e. K _wGreater than K _s

Learn K from equation (1) and (2) _sWith K _wActual value depend on the comparative resistance size of minute loop and major loop, shunting circuit is relation in parallel with major loop, so the pressure loss is identical;

ΔP _m＝ΔP _s (3)

Δ Pm: the major loop pressure loss;

Δ P _s: the shunting circuit pressure loss;

Δ P _mWith Δ P _sCan adopt the phase-splitting model to calculate:

$\sqrt{{\mathrm{\ΔP}}_m}=\sqrt{{\mathrm{\ΔP}}_{\mathrm{ms}}}+{\mathrm{\θ}}_m\sqrt{{\mathrm{\ΔP}}_{\mathrm{mw}}}---\left(4\right)$

$\sqrt{{\mathrm{\ΔP}}_s}=\sqrt{{\mathrm{\ΔP}}_{\mathrm{ss}}}+{\mathrm{\θ}}_s\sqrt{{\mathrm{\ΔP}}_{\mathrm{sw}}}---\left(5\right)$

Δ P _MsWith Δ P _MwRepresent respectively the pressure loss when steam and water flow through major loop separately;

Δ P _SsAnd Δ P _SwRepresent respectively the pressure loss when gas phase and water flow through shunting circuit separately;

θ represents the modifying factor that changes according to pressure;

${\mathrm{\ΔP}}_{\mathrm{ms}}=[{\mathrm{\λ}}_m\mathrm{\Σ}\frac{1}{d_m}+\mathrm{\Σ}{\mathrm{\ξ}}_m]\frac{1}{2{\mathrm{\ρ}}_s}{\left(\frac{M_{\mathrm{ms}}}{A_m}\right)}^2---\left(6\right)$

${\mathrm{\ΔP}}_{\mathrm{mw}}=[{\mathrm{\λ}}_m\mathrm{\Σ}\frac{1}{d_m}+\mathrm{\Σ}{\mathrm{\ξ}}_m]\frac{1}{2{\mathrm{\ρ}}_w}{\left(\frac{M_{\mathrm{mw}}}{A_m}\right)}^2---\left(7\right)$

${\mathrm{\ΔP}}_{\mathrm{ss}}=[{\mathrm{\λ}}_s\mathrm{\Σ}\frac{1}{d_s}+\mathrm{\Σ}{\mathrm{\ξ}}_s]\frac{1}{2{\mathrm{\ρ}}_s}{\left(\frac{M_{\mathrm{ss}}}{A_s}\right)}^2---\left(8\right)$

${\mathrm{\ΔP}}_{\mathrm{sw}}=[{\mathrm{\λ}}_s\mathrm{\Σ}\frac{1}{d_s}+\mathrm{\Σ}{\mathrm{\ξ}}_s]\frac{1}{2{\mathrm{\ρ}}_w}{\left(\frac{M_{\mathrm{sw}}}{A_s}\right)}^2---\left(9\right)$

λ is the darcy friction factor in following formula, and L is length of tube, and d is bore, ξ local loss coefficient, ρ _wWater-mass density, ρ _sVapour density, M is mass rate, and A is the tube section area, and symbol Σ represents summation; Subscript m represents major loop, and subscript S represents shunting circuit;

2) according to law of conservation of mass, the discharge relation formula of total flow and shunting circuit:

M _s＝M _ms+M _ss (10)

M _w＝M _mw+M _sw (11)

X _mBe major loop mass dryness fraction, X _sFor the shunting circuit mass dryness fraction, ignore θ _mWith θ _sMinute differences, that is: θ _m=θ _sThen=θ brings equation (4)-(11) in the equation (3) into, obtains:

$\frac{K_0}{K_s}-1=\mathrm{\θ}(1-\frac{k_0}{k_w})\sqrt{\frac{{\mathrm{\ρ}}_G}{{\mathrm{\ρ}}_L}}(\frac{1}{X_s}-1)---\left(12\right)$

In following formula, K ₀Be the diverting coefficient under single-phase flow, determined by following equation:

${\mathrm{<figure-callout\; id="0"\; label="K"\; filenames="HDA00002152284600022.png"\; state="\{\{state\}\}">K</figure-callout>}}_0=\frac{A_s\sqrt{{\mathrm{\&lambda;}}_m\mathrm{\&Sigma;}\frac{1}{d_m}+\mathrm{\&Sigma;}{\mathrm{\&xi;}}_m}}{A_s\sqrt{{\mathrm{\&lambda;}}_m\mathrm{\&Sigma;}\frac{1}{d_m}+\mathrm{\&Sigma;}{\mathrm{\&xi;}}_m}+A_m\sqrt{{\mathrm{\&lambda;}}_s\mathrm{\&Sigma;}\frac{1}{d_s}+\mathrm{\&Sigma;}{\mathrm{\&xi;}}_s}}---\left(13\right)$

Equation (12) is the resistance balance equation, obtains from drag relationship, and this equation be can not determine the value of Ks and Kw, needs to replenish another equation km:

$K_m=\frac{M_{\mathrm{ss}}+M_{\mathrm{sw}}}{M_s+M_w}=\frac{1}{\frac{X_s}{K_s}+\frac{1-X_s}{K_w}}=F\left(X_s\right)---\left(14\right)$

Equation (14) claims distribution equations, and function F (Xs) will be determined by experiment;

3) boiler output mass dryness fraction is calculated by following formula:

$X=\frac{C_o-C_i}{C_o}---\left(15\right)$

The Ci boiler advances softening electrical conductivity of water; Co is boiler output condensation electrical conductivity of water, i.e. sampling separator conductivity, and minimum mass dryness fraction is adjusted to 60%, and the highest mass dryness fraction is 82%, and flow range was from 2000kg/ hour to 8000kg/ hour, and pressure limit is 7.6-10MPa;

Wherein before the diphasic flow experiment, carry out first the single-phase water experiment, determined k ₀=0.01350; According to boiler feed water amount and boiler output steam quality, diverting coefficient calculates θ=1.6259 according to equation (1) and (2);

K wherein _mBe total shunting coefficient and X _sBe the shunting circuit mass dryness fraction, determine F (X according to equation (14) _s):

Km＝0.02218-0.01042X _s (16)

By the above-mentioned relation formula, i.e. (12) resistance balance equation that (1)-(11), (13), (14) draw, (14) distribution equations and (16) equation; By equation (12) (14) (16) equation at steam diversion amount M _SsWith liquid phase shunt volume M _sOn the basis of measuring, calculate total flow and total mass dryness fraction;

Step 2 steam measurement device: consisted of by supervisor, tap hole, collecting ring, separating tank, steam-flow meter, water ga(u)ge, restriction device, major loop restriction device; Steam enters collection ring casing 3 along the tap hole of supervisor's 1 process shunt 2, arrive separating tank 4 and implement to separate, the steam after the separation is by steam-flow meter 5 meterings, and the water after the separation is by water ga(u)ge 6 meterings, get back to supervisor 1 by restriction device 7 after steam after the separation mixes with water, inject oil well; The pressure of whole system is to regulate by restriction device 7 and major loop restriction device 8.

The present invention utilizes the interior vapour of supervisor-water fluid-mixing to flow through measurement mechanism, fraction enters the collection ring casing by thief hole, this segment fluid flow is separated into single-phase steam and water at separation vessel, steam flows out from the separation vessel top and measures by steam-flow meter, current flow out from the separation vessel bottom and measure by water ga(u)ge, after the metering, steam and water again mixed flow are crossed restriction device, then flow back to the method for major loop by the lower end of supervisor's restriction device, the method is scientific and reasonable, simple to operate, practical value is high, shows technical progress.

The inventive system comprises shunt and piece-rate system is installed on horizontal vapour-water two-phase flow pipeline, at supervisor's wall 6 tap holes are arranged, it is outer to be a collection ring casing, in order to collect the fluid that flows out from tap hole, a little separation vessel links to each other with the collection ring casing, at separation vessel top and bottom steam-flow meter and water ga(u)ge have been installed respectively, steam-flow meter links to each other with restriction device with the outlet of water ga(u)ge simultaneously, finally be connected to the lower end of major loop restriction device, the steam-flow meter that data collection processor collects and water ga(u)ge data and line pressure data are carried out operational analysis production flow line steam flow, mass dryness fraction, pressure, temperature, the needed technical parameter such as heat.

Description of drawings

The present invention is described further by reference to the accompanying drawings.

Accompanying drawing 1 is steam measurement apparatus structure schematic diagram;

As shown in the figure: 1-supervisor, 2-tap hole, 3-collect ring casing, 4-separating tank, 5-steam-flow meter, 6-water ga(u)ge, 7-restriction device, 8-major loop restriction device.

Accompanying drawing 2 is the A-A diagrammatic cross-section of Fig. 1;

1-supervisor, 2-tap hole, 3-collect ring casing, 9-bubble; The 10-liquid film; The 11-water droplet; 12-collects the ring casing outlet;

As shown in Figure 1 and Figure 2: steam enters collection ring casing 3 along the tap hole of supervisor's 1 process shunt 2, arriving separating tank 4 separates, steam after the separation is by steam-flow meter 5 meterings, water after the separation is by water ga(u)ge 6 meterings, get back to supervisor 1 by restriction device 7 after steam after the separation mixes with water, inject oil well; Wherein the pressure of whole system is to regulate by restriction device 7 and major loop restriction device 8.

Accompanying drawing 3 is the trial stretch schematic diagram;

As shown in Figure 3: the gas bullet stream that experimental point mainly distributes and is positioned at, on annular flow and the wave flow border.

There is the linear relationship schematic diagram in accompanying drawing 4 between the data variable;

As shown in Figure 4: represent the right functional expression of equation (12) at transverse axis, Z-axis represents the left side functional expression of equation (12); Be to have linear relationship between transverse axis and the Z-axis variable, data obtain θ=1.6259.

Accompanying drawing 5 is the schematic diagram that concerns of total shunting coefficient and shunting circuit mass dryness fraction;

As shown in Figure 5: K _m(always shunting coefficient) and X _sThe pass of (shunting circuit mass dryness fraction) is linear relation, determines F (X according to equation (14) _s).

Specific implementation method

The present invention is described further in conjunction with the embodiments.

Embodiment 1

Total flow of the present invention and shunt volume scale relation:

$M_s=\frac{M_{\mathrm{ss}}}{K_s}---\left(1\right)$

$M_w=\frac{M_{\mathrm{sw}}}{K_w}---\left(2\right)$

Ms: total steam flow;

M _w: total liquid phase flow;

M _Ss: by the steam diversion amount of steam-flow meter;

M _Sw: by the liquid phase shunt volume of water ga(u)ge;

K _s: the steam diversion coefficient;

K _w: the separating liquid coefficient.

Obtain the shunting constant K from equation (1) and (2) _sAnd K _wRepresent the ratio that major loop flows to sampling loop, as shown in Figure 2: the fluid of major loop is from flowing into sampling loop near the major loop tube wall, moisture abundant here, therefore more water can enter shunting circuit, i.e. K _wGreater than K _s, this is conducive to measure the flow of water under high mass dryness fraction condition.

Shunt ratio relation of the present invention is as follows:

Equation (1) and (2) are the definition of diverting coefficient just, K _sWith K _wActual value depend on the comparative resistance size of minute loop and major loop.We can see from Fig. 1: shunting circuit is relation in parallel with major loop, so the pressure loss is identical.

ΔP _m＝ΔP _s (3)

Δ P _m: the major loop pressure loss;

Δ P _s: the shunting circuit pressure loss.

Δ P _mWith Δ P _sCan adopt the phase-splitting model to calculate:

$\sqrt{{\mathrm{\&Delta;P}}_m}=\sqrt{{\mathrm{\&Delta;P}}_{\mathrm{ms}}}+{\mathrm{\&theta;}}_m\sqrt{{\mathrm{\&Delta;P}}_{\mathrm{mw}}}---\left(4\right)$

$\sqrt{{\mathrm{\&Delta;P}}_s}=\sqrt{{\mathrm{\&Delta;P}}_{\mathrm{ss}}}+{\mathrm{\&theta;}}_s\sqrt{{\mathrm{\&Delta;P}}_{\mathrm{sw}}}---\left(5\right)$

Δ P _MsWith Δ P _MwRepresent respectively the pressure loss when steam and water flow through major loop separately;

Δ P _SsAnd Δ P _SwRepresent respectively the pressure loss when gas phase and water flow through shunting circuit separately;

θ represents the modifying factor that changes according to pressure.

${\mathrm{\&Delta;P}}_{\mathrm{ms}}=[{\mathrm{\&lambda;}}_m\mathrm{\&Sigma;}\frac{1}{d_m}+\mathrm{\&Sigma;}{\mathrm{\&xi;}}_m]\frac{1}{2{\mathrm{\&rho;}}_s}{\left(\frac{M_{\mathrm{ms}}}{A_m}\right)}^2---\left(6\right)$

${\mathrm{\&Delta;P}}_{\mathrm{mw}}=[{\mathrm{\&lambda;}}_m\mathrm{\&Sigma;}\frac{1}{d_m}+\mathrm{\&Sigma;}{\mathrm{\&xi;}}_m]\frac{1}{2{\mathrm{\&rho;}}_w}{\left(\frac{M_{\mathrm{mw}}}{A_m}\right)}^2---\left(7\right)$

${\mathrm{\&Delta;P}}_{\mathrm{ss}}=[{\mathrm{\&lambda;}}_s\mathrm{\&Sigma;}\frac{1}{d_s}+\mathrm{\&Sigma;}{\mathrm{\&xi;}}_s]\frac{1}{2{\mathrm{\&rho;}}_s}{\left(\frac{M_{\mathrm{ss}}}{A_s}\right)}^2---\left(8\right)$

${\mathrm{\&Delta;P}}_{\mathrm{sw}}=[{\mathrm{\&lambda;}}_s\mathrm{\&Sigma;}\frac{1}{d_s}+\mathrm{\&Sigma;}{\mathrm{\&xi;}}_s]\frac{1}{2{\mathrm{\&rho;}}_w}{\left(\frac{M_{\mathrm{sw}}}{A_s}\right)}^2---\left(9\right)$

λ is the darcy friction factor in following formula, and L is length of tube, and d is bore, ξ local loss coefficient, ρ _wWater-mass density, ρ _sVapour density, M is mass rate, and A is the tube section area, and symbol Σ represents summation; Subscript m represents major loop, and subscript S represents shunting circuit.

According to law of conservation of mass, we can write out the discharge relation formula of total flow and shunting circuit:

M _s＝M _ms+M _ss (10)

M _w＝M _mw+M _sw (11)

X _mBe major loop mass dryness fraction, X _sBe the shunting circuit mass dryness fraction, if ignore θ _mWith θ _sMinute differences, that is: θ _m=θ _sThen=θ brings equation (4)-(11) in the equation (3) into, can obtain:

$\frac{K_0}{K_s}-1=\mathrm{\&theta;}(1-\frac{k_0}{k_w})\sqrt{\frac{{\mathrm{\&rho;}}_G}{{\mathrm{\&rho;}}_L}}(\frac{1}{X_s}-1)---\left(12\right)$

In following formula, K ₀Be the diverting coefficient under single-phase flow, can or calculate by following equation and determine by experiment:

${\mathrm{<figure-callout\; id="0"\; label="K"\; filenames="HDA00002152284600022.png"\; state="\{\{state\}\}">K</figure-callout>}}_0=\frac{A_s\sqrt{{\mathrm{\&lambda;}}_m\mathrm{\&Sigma;}\frac{1}{d_m}+\mathrm{\&Sigma;}{\mathrm{\&xi;}}_m}}{A_s\sqrt{{\mathrm{\&lambda;}}_m\mathrm{\&Sigma;}\frac{1}{d_m}+\mathrm{\&Sigma;}{\mathrm{\&xi;}}_m}+A_m\sqrt{{\mathrm{\&lambda;}}_s\mathrm{\&Sigma;}\frac{1}{d_s}+\mathrm{\&Sigma;}{\mathrm{\&xi;}}_s}}---\left(13\right)$

Equation (12) is the resistance balance equation, because it obtains from drag relationship, this equation can not be determined separately the value of Ks and Kw, therefore needs to replenish another equation km:

$K_m=\frac{M_{\mathrm{ss}}+M_{\mathrm{sw}}}{M_s+M_w}=\frac{1}{\frac{X_s}{K_s}+\frac{1-X_s}{K_w}}=F\left(X_s\right)---\left(14\right)$

Equation (14) is called as distribution equations, and function F (Xs) will be determined by experiment.

Embodiment 2

Site test of the present invention, carry out at Karamay, Xinjiang heavy crude heat extraction steam flood Once-through Boiler, experimental provision is that level is installed in the Once-through Boiler outlet section, the inflow of direct current cooker is realized flow regulation by frequency converter pilot plunger pump, measure by standard orifice flow meter, the steam quality of boiler output enters the boiler amount by the fine adjustments rock gas and regulates, and boiler output mass dryness fraction is calculated by following formula:

$X=\frac{C_o-C_i}{C_o}---\left(15\right)$

C i boiler feed water (softening water) conductivity; Co is boiler output condensation electrical conductivity of water, i.e. sampling separator conductivity, and Ci and Co adopt the measurement of portable electric electrical conductivity instrument.In experiment, for guaranteeing the safety of boiler, minimum mass dryness fraction is adjusted to 60%, and the highest mass dryness fraction is 82%, and flow range was from 2000kg/ hour to 8000kg/ hour, and pressure limit is 7.6-10MPa; The flow regime map of scope of experiment as shown in Figure 3, Vs represents the specific speed of steam, and Vw represents the conversion flow velocity of water, and experimental point mainly is positioned at gas bullet stream, on annular flow and the wave flow border._

This method is verified by site test:

Before the test of formal diphasic flow, carried out first single-phase water and tested to determine k 0(single-phase flow diverting coefficient), k0=0.01350 consequently; In the 2nd step-by-step test, the diverting coefficient of pressure, steam and water is by the automatic record of computing machine, and according to boiler feed water amount and boiler output steam quality, diverting coefficient can calculate according to equation (1) and (2); The diverting coefficient test findings represents the right functional expression of equation (12) as shown in Figure 4 at transverse axis, Z-axis represents the left side functional expression of equation (12); As can be seen from Figure 4, have linear relationship between transverse axis and the Z-axis variable, all experimental points all drop near the same straight line, and namely equation (12) is correct; Can obtain θ=1.6259 from these data.

As shown in Figure 5: K _m(always shunting coefficient) and X _sThe pass of (shunting circuit mass dryness fraction) is linear relation, and all test figures all drop on this same straight line, utilizes these data to determine F (X according to equation (14) _s):

Km＝0.02218-0.01042X _s (16)

Present steam and water shunting COEFFICIENT K _sAnd K _wCan pass through equation (12) (14) (16) and determine, as long as know steam diversion amount M _SsWith liquid phase shunt volume M _Sw, just can calculate steam and discharge M _sAnd M _w(perhaps total flow and total mass dryness fraction) M _SsAnd M _Sw, following table has been showed measurement result.

Flow-meter and dryness measurement result

Draw from upper table: the maximum flow measuring error is less than ± 2.5%, and maximum mass dryness fraction measuring error is less than ± 3.5%.Water diverting coefficient K _wGas phase diverting coefficient K _s4-6 doubly.

The using value of the inventive method:

By shunting phase-splitting measuring apparatus metering high pressure vapour-water two-phase flow; First diverting coefficient equation (resistance equation) comes from the drag relationship between major loop and minute loop, and by experiment checking; Second diverting coefficient equation (distribution equations) set up by test; Diverting coefficient can obtain by these two equations, can calculate total gas phase and liquid phase flow by water and the steam flow of shunting; Experiment shows, shunting is the technology of a kind of reliable measurement high pressure vapour-water two-phase flow with split-phase method.

Claims (1)

1. measuring method that is used for high pressure vapour-water two-phase fluid, it is characterized in that: derive by theoretical formula, determine split ratio, bring equation into and obtain the parameters such as the flow of heavy crude heat extraction steam injection and mass dryness fraction demarcating good diverting coefficient, the method is precisely reliable, implements step by step;

Step 1 formula calculates:

1) record total flow and the shunt volume scale relation of steam, water:

$M_s=\frac{M_{\mathrm{ss}}}{K_s}---\left(1\right)$

$M_w=\frac{M_{\mathrm{sw}}}{K_w}---\left(2\right)$

M _s: total steam flow;

M _w: total liquid phase flow;

M _Ss: by the steam diversion amount of steam-flow meter;

M _Sw: by the liquid phase shunt volume of water ga(u)ge;

K _s: the steam diversion coefficient;

K _w: the separating liquid coefficient.

Learn the shunting constant K from equation (1) and (2) _sAnd K _wRepresent the ratio that major loop flows to sampling loop, i.e. K _wGreater than K _s

Learn K from equation (1) and (2) _sWith K _wActual value depend on the comparative resistance size of minute loop and major loop, shunting circuit is relation in parallel with major loop, so the pressure loss is identical;

ΔP _m＝ΔP _s (3)

Δ Pm: the major loop pressure loss;

Δ P _s: the shunting circuit pressure loss;

Δ P _mWith Δ P _sCan adopt the phase-splitting model to calculate:

$\sqrt{{\mathrm{\&Delta;P}}_m}=\sqrt{{\mathrm{\&Delta;P}}_{\mathrm{ms}}}+{\mathrm{\&theta;}}_m\sqrt{{\mathrm{\&Delta;P}}_{\mathrm{mw}}}---\left(4\right)$

$\sqrt{{\mathrm{\&Delta;P}}_s}=\sqrt{{\mathrm{\&Delta;P}}_{\mathrm{ss}}}+{\mathrm{\&theta;}}_s\sqrt{{\mathrm{\&Delta;P}}_{\mathrm{sw}}}---\left(5\right)$

Δ P _MsWith Δ P _MwRepresent respectively the pressure loss when steam and water flow through major loop separately;

Δ P _SsAnd Δ P _SwRepresent respectively the pressure loss when gas phase and water flow through shunting circuit separately;

θ represents the modifying factor that changes according to pressure;

${\mathrm{\&Delta;P}}_{\mathrm{ms}}=[{\mathrm{\&lambda;}}_m\mathrm{\&Sigma;}\frac{1}{d_m}+\mathrm{\&Sigma;}{\mathrm{\&xi;}}_m]\frac{1}{2{\mathrm{\&rho;}}_s}{\left(\frac{M_{\mathrm{ms}}}{A_m}\right)}^2---\left(6\right)$

${\mathrm{\&Delta;P}}_{\mathrm{mw}}=[{\mathrm{\&lambda;}}_m\mathrm{\&Sigma;}\frac{1}{d_m}+\mathrm{\&Sigma;}{\mathrm{\&xi;}}_m]\frac{1}{2{\mathrm{\&rho;}}_w}{\left(\frac{M_{\mathrm{mw}}}{A_m}\right)}^2---\left(7\right)$

${\mathrm{\&Delta;P}}_{\mathrm{ss}}=[{\mathrm{\&lambda;}}_s\mathrm{\&Sigma;}\frac{1}{d_s}+\mathrm{\&Sigma;}{\mathrm{\&xi;}}_s]\frac{1}{2{\mathrm{\&rho;}}_s}{\left(\frac{M_{\mathrm{ss}}}{A_s}\right)}^2---\left(8\right)$

${\mathrm{\&Delta;P}}_{\mathrm{sw}}=[{\mathrm{\&lambda;}}_s\mathrm{\&Sigma;}\frac{1}{d_s}+\mathrm{\&Sigma;}{\mathrm{\&xi;}}_s]\frac{1}{2{\mathrm{\&rho;}}_w}{\left(\frac{M_{\mathrm{sw}}}{A_s}\right)}^2---\left(9\right)$

λ is the darcy friction factor in following formula, and L is length of tube, and d is bore, ξ local loss coefficient, ρ _wWater-mass density, ρ _sVapour density, M is mass rate, and A is the tube section area, and symbol Σ represents summation; Subscript m represents major loop, and subscript S represents shunting circuit;

2) according to law of conservation of mass, the discharge relation formula of total flow and shunting circuit:

M _s＝M _ms+M _ss (10)

M _w＝M _mw+M _sw (11)

X _mBe major loop mass dryness fraction, X _sFor the shunting circuit mass dryness fraction, ignore θ _mWith θ _sMinute differences, that is: θ _m=θ _sThen=θ brings equation (4)-(11) in the equation (3) into, obtains:

$\frac{K_0}{K_s}-1=\mathrm{\&theta;}(1-\frac{k_0}{k_w})\sqrt{\frac{{\mathrm{\&rho;}}_G}{{\mathrm{\&rho;}}_L}}(\frac{1}{X_s}-1)---\left(12\right)$

In following formula, K ₀Be the diverting coefficient under single-phase flow, determined by following equation:

$K_0=\frac{A_s\sqrt{{\mathrm{\&lambda;}}_m\mathrm{\&Sigma;}\frac{1}{d_m}+\mathrm{\&Sigma;}{\mathrm{\&xi;}}_m}}{A_s\sqrt{{\mathrm{\&lambda;}}_m\mathrm{\&Sigma;}\frac{1}{d_m}+\mathrm{\&Sigma;}{\mathrm{\&xi;}}_m}+A_m\sqrt{{\mathrm{\&lambda;}}_s\mathrm{\&Sigma;}\frac{1}{d_s}+\mathrm{\&Sigma;}{\mathrm{\&xi;}}_s}}---\left(13\right)$

Equation (12) is the resistance balance equation, obtains from drag relationship, and this equation be can not determine K _sWith the value of Kw, need to replenish another equation km:

$K_m=\frac{M_{\mathrm{ss}}+M_{\mathrm{sw}}}{M_s+M_w}=\frac{1}{\frac{X_s}{K_s}+\frac{1-X_s}{K_w}}=F\left(X_s\right)---\left(14\right)$

Equation (14) claims distribution equations, and function F (Xs) will be determined by experiment;

3) boiler output mass dryness fraction is calculated by following formula:

$X=\frac{C_o-C_i}{C_o}---\left(15\right)$

The Ci boiler advances softening electrical conductivity of water; Co is boiler output condensation electrical conductivity of water, i.e. sampling separator conductivity, and minimum mass dryness fraction is adjusted to 60%, and the highest mass dryness fraction is 82%, and flow range was from 2000kg/ hour to 8000kg/ hour, and pressure limit is 7.6-10MPa;

Wherein before the diphasic flow experiment, carry out first the single-phase water experiment, determined k ₀=0.01350; According to boiler feed water amount and boiler output steam quality, diverting coefficient calculates θ=1.6259 according to equation (1) and (2);

K wherein _mBe total shunting coefficient and X _sBe the shunting circuit mass dryness fraction, determine F (X according to equation (14) _s):

Km＝0.02218-0.01042X _s (16)

By the above-mentioned relation formula, i.e. (12) resistance balance equation that (1)-(11), (13), (14) draw, (14) distribution equations and (16) equation; By equation (12) (14) (16) equation at steam diversion amount M _SsWith liquid phase shunt volume M _sOn the basis of measuring, calculate total flow and total mass dryness fraction;

Step 2 steam measurement device: consisted of by supervisor, tap hole, collecting ring, separating tank, steam-flow meter, water ga(u)ge, restriction device, major loop restriction device; Steam enters collection ring casing (3) arrival separating tank (4) along the tap hole of supervisor (1) process shunt (2), implements to separate; Steam after the separation is by steam-flow meter (5) metering, and the water after the separation is got back to supervisor (1) by restriction device (7) by water ga(u)ge (6) metering after the steam after the separation mixes with water, injects oil well; Wherein the pressure of whole system is to regulate by restriction device (7) and major loop restriction device (8).

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