WO2019179293A1 - 一种气液两相流量测量系统 - Google Patents

一种气液两相流量测量系统 Download PDF

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WO2019179293A1
WO2019179293A1 PCT/CN2019/076343 CN2019076343W WO2019179293A1 WO 2019179293 A1 WO2019179293 A1 WO 2019179293A1 CN 2019076343 W CN2019076343 W CN 2019076343W WO 2019179293 A1 WO2019179293 A1 WO 2019179293A1
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phase
flow
moisture content
capacitance
liquid
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French (fr)
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徐英
汪晶晗
张涛
李继良
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Tianjin Tj Uni Taihe Automation Control & Instrument Co Ltd
Tianjin University
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Tianjin Tj Uni Taihe Automation Control & Instrument Co Ltd
Tianjin University
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance

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  • the invention belongs to the technical field of gas-liquid two-phase flow measurement, and relates to a novel gas-liquid two-phase flow measurement system based on a differential pressure method device and a device based on a swirling phase separation capacitance water content method.
  • Gas-liquid two-phase flow is widely present in various fields of industrial production. With the advancement of technology, the measurement of gas-liquid two-phase flow using non-separation techniques is gradually accepted. At present, the relatively mature gas-liquid two-phase flow measurement technology that can be applied in industrial fields mainly includes "differential pressure + ray technology”, “differential pressure + microwave technology”, “double differential pressure technology” and the like.
  • the invention is directed to the technical difficulties to be solved in the field: firstly, it is safe and radiation-free, and is convenient for on-site management; secondly, the measurement range is as wide as possible, and is applicable to changes of complex fluid flow patterns, for example, for layered wavy flow, annular flow, Complex flow patterns such as mixed flow and even slug flow; third, simple structure, light weight, and easy maintenance.
  • the invention aims at starting from the above technical difficulties and proposes a novel gas-liquid two-phase flow measuring system.
  • the differential pressure type throttling device has a simple structure, high reliability, low cost, and good measurement accuracy within a certain range, and has become a measuring device capable of working stably under both flow patterns of two-phase flow.
  • Commonly used throttling devices include standard throttling devices such as orifice plates, venturis, nozzles, venturi nozzles, and deformation structures of standard devices, such as shaped orifice plates, porous orifice plates, shaped venturis, shaped nozzles, cones, wedges, etc.
  • Non-standard throttling device In 1967, Chisholm D.
  • Capacitance method is a traditional moisture content measurement technology with simple principle and convenient maintenance. At present, the technology based on capacitance method mainly adopts non-contact method.
  • Jarle Tollefsen and Erling A. Hammer published a paper “Capacitance sensor design for reducing errors in phase concentration measurements", which studied the use of surface spiral electrodes to measure the aqueous and gas phase concentrations in crude oil; 2009 A. Ja wornk, A.
  • Krupa et al. used the phase shift information of the wall capacitive sensor to measure the phase content of the two-phase flow.
  • the object of the present invention is to provide a gas-liquid two-phase flow measuring system which is simple in structure, wide in range range and high in reliability, and can effectively overcome the influence of flow pattern and can be used for slug flow (ie, high volume content).
  • the gas-liquid two-phase flow of the liquid rate is effectively predicted.
  • the invention adopts the following technical solutions:
  • a moisture measuring system based on differential pressure and swirling split-phase capacitance water content sensor comprising a differential pressure flow meter and a moisture content sensor fixed on a measuring pipe, a differential pressure flow meter and a moisture content sensor installed horizontally, to flow first
  • the differential pressure flowmeter measures the total virtual high-quality flow of the two-phase flow, and then measures the liquid phase content in the two-phase flow through the moisture content sensor to realize the non-separation measurement of the two-phase flow;
  • the moisture content sensor is a swirling flow
  • the split-phase capacitance water content sensor comprises a cyclone phase splitting section and a capacitance measuring section, and the swirling phase-separating section comprises a spiral blade support rod, two or more spiral blades and an outer tube wall distributed around the outer circumference of the spiral blade support rod; capacitance measurement
  • the segment includes a metal inner core covering the outer periphery of the inner core of the metal and the outer metal tube wall.
  • the helix angle of the spiral blade is between 30° and 60°, and each of the spiral blades is evenly distributed along the circumference.
  • the tail of the spiral blade support rod is matched with and connected to the size of the metal core, and the outer tube wall and the outer metal tube wall are matched and connected to each other.
  • the inner diameter of the flow pipe is D
  • the inner diameter of the outer metal pipe wall is 1 ⁇ 3D
  • the pitch of the spiral blade is 0.5D ⁇ 3D
  • the length of the capacitance measuring unit is 2D ⁇ 6D
  • the ratio of the diameter of the metal inner core to the diameter of the outer metal pipe wall is 1. : 2 to 1:8.
  • the water-facing surface of the spiral blade support rod is streamlined.
  • the invention also provides a gas-liquid two-phase flow measuring system with wider application, including a differential pressure flowmeter and a moisture content sensor fixed on the measuring pipeline, a differential pressure flowmeter and a moisture content sensor installed in series, and a differential pressure flowmeter.
  • the moisture content sensor is used to measure the liquid phase content in the two-phase flow, and realize the non-separating measurement of the two-phase flow;
  • the moisture content sensor is a swirling split-phase capacitor containing water
  • the rate sensor comprises a cyclone phase separation unit and a capacitance measuring unit, and the swirling phase separation unit comprises a spiral blade support rod, two or more spiral blades and an outer tube wall distributed around the outer circumference of the spiral blade support rod;
  • the capacitance measuring unit comprises a metal inside
  • the core covers the insulating layer on the outer circumference of the metal inner core and the outer metal tube wall.
  • the helix angle of the spiral blade is between 30° and 60°, and each of the spiral blades is evenly distributed along the circumference.
  • the tail of the spiral blade support rod is matched with and connected to the size of the metal core, and the outer tube wall and the outer metal tube wall are matched and connected to each other.
  • the inner diameter of the flow pipe is D
  • the inner diameter of the outer metal pipe wall is 1 ⁇ 3D
  • the pitch of the spiral blade is 0.5D ⁇ 3D
  • the length of the capacitance measuring unit is 2D ⁇ 6D
  • the ratio of the diameter of the metal inner core to the diameter of the outer metal pipe wall is 1. : 2 to 1:8.
  • the water-facing surface of the spiral blade support rod is streamlined.
  • the present invention has the following technical effects:
  • the present invention combines a differential pressure method throttling device with a cyclone-phase-separating capacitance water content method to measure both moisture and high volume liquid content gas present in an industrial site.
  • the liquid two-phase flow (such as the slug flow) is measured, and the liquid phase measurement range can be achieved from 0 to 100%.
  • the flow guiding action of the spiral vane changes the flow direction and state of the fluid. Due to the large density of the liquid phase, the circular motion is performed under the action of centrifugal force, and the liquid phase is smashed through the gas phase to the wall of the tube to achieve gas-liquid separation. The gas phase is concentrated in the central region, the gas core rotates, and the liquid phase distributes along the tube wall to form a rotating liquid film. At this time, the capacitance measurement result of the capacitance measuring unit is independent of the distribution of the liquid phase in the space, that is, the flow is not affected. Type effect.
  • the present invention will significantly enhance the gas-liquid two-phase spinning effect through a plurality of sets of flow-through spiral blades
  • FIG. 1 Schematic diagram of the installation method of the gas-liquid two-phase flow measurement system, a total of eight are given.
  • 1-1 represents a differential pressure method throttling device; and 1-2 represents a cyclone phase separation capacitance water content method.
  • the gas-liquid two-phase flow may first pass through the differential pressure throttling device (1(a), 1(d), 1(e), 1(g)), or may first pass through the swirling phase separation capacitor moisture content. Method (1(b), 1(c), 1(f), 1(h)).
  • Figure 2 is a block diagram of the measurement principle of the gas-liquid two-phase flow measurement system.
  • FIG. 3 Schematic diagram of the sensor of the cyclone phase separation capacitor moisture content method.
  • Figure 4 is a schematic view of a multi-spiral blade of a cyclone phase separation unit.
  • FIG. 4(a1) is a left side view of the three-helix blade
  • FIG. 4(a2) is a front view of the three-spiral blade
  • FIG. 4(a3) is an overall schematic view of the three-helix blade
  • FIG. 4(b1) is a left side view of the four-helix blade
  • FIG. 4(b2) is a front view of the four-spiral blade
  • FIG. 4(b3) is an overall schematic view of the four-helix blade.
  • Figure 5 shows the relationship between the relative liquid film thickness and the volumetric liquid fraction LVF in a gas-liquid two-phase flow capacitor unit.
  • Figure 6 shows the relationship between the relative liquid film thickness and the relative capacitance value in a gas-liquid two-phase flow capacitor unit.
  • Figure 7 shows the relationship between the volumetric liquid fraction LVF and the capacitance value.
  • Figure 7(b) shows the volumetric liquid fraction LVF and capacitance value at three different pressures (0.6 MPa, 1.2 MPa, 1.6 MPa) at a gas phase apparent flow rate of 10 m/s. Change diagram.
  • Figure 8 shows the relationship between the virtual high OR of the differential pressure throttling device as a function of volumetric liquid fraction LVF.
  • the present invention uses a multi-blade-flow type swirling split-phase capacitor water content method to rectify the gas-liquid two phases by the flow-through spiral blade.
  • the liquid phase is forced to distribute on the wall of the tube to form a liquid film. Since the measuring system adopts multiple sets of spiral blades, the spinning effect is remarkable.
  • FIG. 1 it is a schematic diagram of a method for measuring a gas-liquid two-phase flow rate system in combination with a differential pressure method throttling device and a cyclone phase-separating capacitance water content method.
  • the measuring system is installed in series. There are 8 installation modes in the figure.
  • the flow can be measured by the differential pressure method to measure the total virtual high-quality flow of the two-phase flow. It can also be measured by the cyclone-phase-capacitance water content method.
  • the liquid phase content in the phase flow can be installed horizontally, vertically upwards or vertically downwards, or can be installed in series through a U-shaped tube (not shown) or an inverted U-shaped tube, in addition,
  • the schematic is either horizontal or vertical, and in practical applications it can also be mounted on a slanted measuring pipe.
  • the split-phase capacitance moisture content sensor constitutes a moisture two-phase flow measurement system to measure the two-phase flow of wet natural gas in the industrial site.
  • the measurement method is as follows:
  • the change in volumetric moisture content LVF in the gas-liquid two-phase flow causes a change in the thickness of the liquid film ⁇ h/h 0 , that is, the thickness of the liquid film divided by the thickness of the water layer h 0 when the water is full, and further, the change in the thickness of the liquid film causes a capacitance value.
  • the relative change ⁇ C/C 0 that is, the change in capacitance caused by the presence of the liquid phase of the two-phase flow divided by the capacitance value C 0 of the single-phase gas, is: LVF ⁇ ⁇ h / h 0 ⁇ ⁇ C / C 0 . According to the change law of volumetric water content and capacitance, the corresponding mathematical model is established.
  • W tp is the virtual high mass flow rate of the fluid
  • C d is the outflow coefficient of the venturi
  • ⁇ is the expansion coefficient of the measured fluid
  • ⁇ is the throttling ratio, ie the throat diameter and the inlet diameter The ratio d/D
  • ⁇ P tp is the pressure difference before and after the two-phase flow passes through the throttle
  • ⁇ g is the density of the gas.
  • LVF volumetric moisture content measured by the capacitance measuring unit
  • ⁇ l / ⁇ g liquid-gas density ratio
  • Fr g gas-phase Froude number, which is the ratio of the gas phase inertial force to the liquid gravity in the gas-liquid two-phase flow.
  • the volumetric liquid content can be obtained, and according to the formulas (2), (3), (4), and (5), an iterative calculation of the gas phase flow rate can be realized, thereby obtaining a gas phase and a phase separation flow rate.
  • the multi-blade cyclone phase-separating capacitor moisture content method of the present invention is shown in FIG. Can be combined with any single-phase differential pressure meter, such as orifice plate, venturi, V cone and so on.
  • the present invention is different from the conventional moisture content measuring device in that the gas-liquid two phases are subjected to cyclone phase separation to measure the capacitance.
  • the gas-liquid two-phase flows into the cyclone phase separation unit (swirl phase separation section) through the differential pressure device, and simultaneously swirls with a plurality of sets of spiral blades, and the liquid phase can be completely separated from the gas phase to the pipe wall.
  • the metal inner core serves as the inner electrode
  • the outer metal tube wall (Fig. 3, 2-3) and the liquid film distributed on the tube wall together constitute the outer electrode, the gas phase and the insulating layer.
  • the insulating dielectric layer is formed to form a capacitor. To improve the sensitivity of the capacitor, it is necessary to ensure that the diameter of the outer metal tube wall is twice or more the diameter of the metal inner core.
  • FIG. 4(a1) is a left-side view of the three-spiral blade
  • FIG. 4(a2) is a front view of the three-spiral blade
  • FIG. 4(a3) is an overall schematic view of the three-spiral blade.
  • the angle of each blade is 120°, the inner diameter of the pipe is D, and the pitch is 2.5D
  • Figure 4 (b1) is the left side view of the four-helix blade
  • Figure 4 (b2) is the front view of the four-spiral blade
  • Figure 4 (b3) For the overall schematic diagram of the four spiral blades, each blade has an angle of 90°, and the inner diameter of the pipe is D, and the pitch is 1.5D.
  • the CFD numerical simulation method is used to simulate the variation of the air-water two-phase flow in the measurement system.
  • the gas phase apparent flow rate is 3m/s-20m/s
  • the pressure is 0.6MPa, 0.8MPa
  • the differential pressure throttling device is venturi.
  • the diameter of DN50, the throttle ratio of 0.55, the effect of volumetric liquid fraction on the thickness of the liquid film, the influence of the capacitance value and the effect of the false height are as follows:
  • Figure 5 shows the air-water two-phase flow relative to the liquid film thickness at a gas flow rate of 3 m/s, 5 m/s, 10 m/s, and 20 m/s at 0.6 MPa (the liquid film thickness value divided by the full pipe water)
  • LVF ⁇ h/h 0 the relative thickness of the liquid film shows a monotonous upward trend with increasing liquid content; when the liquid content is the same, the higher the gas phase flow rate, the thinner the liquid film thickness.
  • Fig. 6 is a graph showing the relationship between the apparent flow velocity of the gas phase at 0.6 MPa and the relative change of the liquid film thickness of the 20 m/s air-water two-phase flow and its induced capacitance, that is, ⁇ h/h 0 ⁇ ⁇ C/C 0 , indicating the same
  • the greater the rate of change of the relative thickness of the liquid film the greater the rate of change of capacitance
  • the smaller the flow rate the greater the relative change rate of the capacitance at the same rate of change of the liquid film, indicating that the capacitance change is more sensitive at a small flow rate, and the capacitance sensitivity is high.
  • the lower the lower limit of the liquid phase range the better the measurement of low liquid content.
  • Figure 7 is: Fig. 7(a) is a graph showing the relationship between the apparent liquid flow rate of 3m/s, 5m/s, 10m/s, 20m/s volumetric liquid rate LVF and capacitance at 0.6MPa, ie LVF ⁇ C/C 0 . It can be seen from the figure that the higher the gas phase flow rate, the larger the capacitance value, and the capacitance value monotonously increases with the LVF.
  • Figure 7(b) shows the effect of the apparent gas flow rate of 10 m/s on the measured capacitance under three different pressures (0.6 MPa, 1.2 MPa, 1.6 MPa).
  • the higher the pressure the smaller the relative capacitance change.
  • the gas phase density increases, the liquid flow rate increases under the same flow rate and liquid content rate, and the liquid film becomes thinner, resulting in a decrease in the capacitance change value.
  • the relative change in capacitance under each pressure varies with volume. The trend of liquid rate LVF is consistent.
  • Figure 8 shows the apparent gas flow rates at 0.6 MPa of 3 m/s, 5 m/s, 10 m/s and 15 m/s (gas Froude numbers: 0.395, 0.645, 1.280 and 1.912, respectively).
  • the imaginary virtual high value increases with the volumetric liquid content. Large, with good regularity.
  • the volume liquid content can be obtained.
  • the gas phase flow rate can be measured, and the total amount and the liquid phase content can be obtained. Liquid phase flow.

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Abstract

一种气液两相流量测量系统，包括固定在测量管道上的差压流量计和含水率传感器，差压流量计和含水率传感器串联安装，差压流量计用于测量两相流总的虚高质量流量，含水率传感器用于测量两相流中的液相含率，实现两相流量的非分离计量；所述的含水率传感器为旋流分相电容含水率传感器，包括旋流分相单元和电容测量单元，旋流分相单元包括螺旋叶片支撑杆，分布在螺旋叶片支撑杆外周的两个以上的螺旋叶片和外管壁；电容测量单元包括金属内芯，覆盖在金属内芯外周的绝缘层和外金属管壁。以及一种基于差压与旋流分相电容含水率传感器的湿气测量系统。

Description

一种气液两相流量测量系统 技术领域
本发明属于气液两相流流量测量技术领域，涉及一种基于差压法装置与一种基于旋流分相电容含水率法装置组合的新型气液两相流量测量系统。
背景技术
气液两相流广泛存在于工业生产的各个领域。随着科技的进步，使用非分离技术测量气液两相流流量逐渐被接受。目前，相对成熟的可应用在工业现场的气液两相流量测量技术主要包含“差压+射线技术”、“差压+微波技术”、“双差压技术”等等。本发明针对该领域亟待解决的技术难点：其一，安全无辐射，便于现场管理；其二，测量量程尽量宽，适用复杂流体流动形态的变化，例如适用于分层波状流、环状流、混状流甚至段塞流等复杂流动形态变化；其三，结构简单，体积轻便，维护方便等。本发明针对以上述技术难点出发，提出一种新型的气液两相流量测量系统。
差压式节流装置由于结构简单，可靠性高，成本低，在一定范围内具有较好的测量精度，已成为目前在两相流各流型下都能够较稳定工作的测量装置。常用的节流装置有孔板、文丘里、喷嘴、文丘里喷嘴等标准节流装置及标准装置的变形结构，如异型孔板、多孔孔板、异型文丘里、异型喷嘴、锥形、楔形等非标准节流装置。1967年Chisholm D.在《Flow of incompressible two‐phase mixtures through sharp‐edged orifices》基于孔板中蒸汽、水两相流动采用分相法理论推导出孔板气液两相流的虚高模型；林宗虎等人在1979年根据大量工况的气液密度比实验分析结果，提出了适用于压力0.7-20.1MPa，干度在0.1-1范围，孔板节流比为0.25-0.75，管道内径为8-75cm的虚高模型；1997年，De Leeuw提出了针对文丘里管的湿气虚高测量模型。其公式形式借用了Chisholm提出的孔板湿气测量模型，并对其参数进行相关修正；2002年，R.N.Steven用NEL的实验数据拟和了新的文丘里管测量湿气模型；2003年，M.Van Werven和H.R.E.Van Maanen将湿气看作雾状流，探讨了湿气流经文丘里管的流动模型。2008年以来，天津大学徐英对锥形、文丘里及其异型文丘里进行了深入研究，提出基于长喉颈双差压和三差压双比值法的文丘里的湿气气液两相流测量装置及测量方法。
电容法是一种传统的含水率测量技术，原理简单、维护方便，目前基于电容法的技术主要采取的是非接触法。例如，1998年JarleTollefsen和Erling A.Hammer发表论文《Capacitance sensor design for reducing errors in phase concentration measurements》，研究了利用表面螺旋电极，测量原油中的水相和气相浓度；2009年A.Jaworek、A.Krupa等人在论文《Phase-shift detection for capacitance sensor measuring void fraction in two-phase flow》中给出了利用对壁式电容传感器的相位移信息实现对两相流相含率的测量，其主要测试小管径(管道内径1，2，4，9.5mm)和低流速的两相流；2015年Kathleen De Kerpel等人在《Two-phase flow regime assignment based on  wavelet features of a capacitance signal》利用对壁式电容，对内径8mm的水平管进行实验，流动形态主要有弹状流、间歇流、环状流，分析了电容器信号的小波特性，认为流型和干度对小波特征有十分明显的影响。综上所述，根据非接触电容法测量多相流相含率的现状分析可知，国内外科研工作者已经在多相流相含率的测量领域展开了大量的工作，在优化电容器结构及其激励模式方面均积累了宝贵的经验。但其测量结果受到两相流流型的严重影响，传感器的响应仍旧强烈的依赖于各相介质的空间分布，给相含率的测量带来了很大难度，难于工业推广应用。
发明内容
本发明的目的旨在提供适用于工业应用的结构简单、量程范围宽、可靠性高的气液两相流流量测量系统，能够有效克服流型影响，并能够对段塞流(即高体积含液率)的气液两相流动进行有效预测。本发明采用如下技术方案：
一种基于差压与旋流分相电容含水率传感器的湿气测量系统，包括固定在测量管道上的差压流量计和含水率传感器，差压流量计和含水率传感器水平安装，来流先经过差压流量计测量两相流总的虚高质量流量，再经过含水率传感器测量两相流中的液相含率，实现两相流量的非分离计量；所述的含水率传感器为旋流分相电容含水率传感器，包括旋流分相段和电容测量段，旋流分相段包括螺旋叶片支撑杆，分布在螺旋叶片支撑杆外周的两个以上的螺旋叶片和外管壁；电容测量段包括金属内芯，覆盖在金属内芯外周的绝缘层和外金属管壁。
优选地，螺旋叶片的升角在30°～60°之间，每个螺旋叶片沿圆周均匀分布。螺旋叶片支撑杆的尾部与金属内芯的尺寸相配合并相互连接，外管壁和外金属管壁尺寸相配合并相互连接。设来流管道内径为D，外金属管壁内径为1～3D，螺旋叶片的螺距为0.5D～3D，电容测量单元长度为2D～6D，金属内芯直径与外金属管壁直径比为1:2～1:8。螺旋叶片支撑杆的迎水面为流线型。
本发明同时提供一种应用更广泛的气液两相流量测量系统，包括固定在测量管道上的差压流量计和含水率传感器，差压流量计和含水率传感器串联安装，差压流量计用于测量两相流总的虚高质量流量，含水率传感器用于测量两相流中的液相含率，实现两相流量的非分离计量；所述的含水率传感器为旋流分相电容含水率传感器，包括旋流分相单元和电容测量单元，旋流分相单元包括螺旋叶片支撑杆，分布在螺旋叶片支撑杆外周的两个以上的螺旋叶片和外管壁；电容测量单元包括金属内芯，覆盖在金属内芯外周的绝缘层和外金属管壁。
优选地，螺旋叶片的升角在30°～60°之间，每个螺旋叶片沿圆周均匀分布。螺旋叶片支撑杆的尾部与金属内芯的尺寸相配合并相互连接，外管壁和外金属管壁尺寸相配合并相互连接。设来流管道内径为D，外金属管壁内径为1～3D，螺旋叶片的螺距为0.5D～3D，电容测量单元长度为2D～6D，金属 内芯直径与外金属管壁直径比为1:2～1:8。螺旋叶片支撑杆的迎水面为流线型。
与现有技术相比，本发明具有如下的技术效果：
(1)本发明通过一种差压法节流装置与一种基于旋流分相电容含水率法装置组合，既可以测量湿气，又可对工业现场中出现的高体积含液率的气液两相流(如段塞流)进行测量，液相测量范围可实现0～100％。
(2)本发明上下游只需与对应直管段法兰连接即可；
(3)气液两相流流入旋流分相单元后，螺旋叶片的导流作用改变了流体的流动方向和状态。液相由于密度偏大，在离心力作用下做圆周运动，同时液相将穿过气相被甩向管壁，实现气液分离。气相集中在中心区域，气核旋转流动，液相沿管壁分布做旋转流动，形成旋转的液膜，此时，电容测量单元的电容测量结果与液相在空间的分布无关，即不受流型影响。
(4)本发明将通过多组导流式螺旋叶片，气液两相起旋效果显著加强；
(5)无需分离，不依赖放射性技术和示踪技术对气液两相流中的含水率进行测量，结构简单、安全可靠，维护费用低。
附图说明
图1气液两相流流量测量系统安装方式示意图，一共给出了8种。
其中，1-1表示差压法节流装置；1-2表示旋流分相电容含水率法装置。
共有8中不同的串联安装方式，分别为水平安装(1(a)、1(b))、竖直自下而上安装(1(c)、1(d))、竖直自上而下安装(1(e)、1(f))、倒U型安装(1(g)、1(h))；
气液两相流来流既可以先经过差压法节流装置(1(a)、1(d)、1(e)、1(g))，也可以先经过旋流分相电容含水率法装置(1(b)、1(c)、1(f)、1(h))。
图2气液两相流流量测量系统测量原理结构框图。
图3旋流分相电容含水率法装置传感器示意图。
图4旋流分相单元多螺旋叶片示意图。
其中，图4(a1)为三螺旋叶片左视图，图4(a2)为三螺旋叶片剖面图正视图，图4(a3)为三螺旋叶片整体示意图；
图4(b1)为四螺旋叶片左视图，图4(b2)为四螺旋叶片剖面图正视图，图4(b3)为四螺旋叶片整体示意图。
图5给出了气液两相流电容单元中相对液膜厚度与体积含液率LVF的变化关系图。
图6给出了气液两相流电容单元中相对液膜厚度与相对电容值的变化关系图。
图7给出了体积含液率LVF与电容值的变化关系图。
[根据细则91更正 02.04.2019]其中图7(a)为0.6Mpa下，表观流速为3m/s、5m/s、10m/s、20m/s体积含液率LVF与电容值的变化关系图;
[根据细则91更正 02.04.2019]图7(b)为三个不同压力(0.6MPa,1.2MPa,1.6MPa)条件下，气相表观流速为10m/S时体积含液率LVF与电容值的变化关系图。
图8给出了差压节流装置的虚高OR随体积含液率LVF变化关系图。
具体实施方式
下面参照附图对本发明做进一步详述。
为避免旋流分相式电容含水率法装置时受流型影响，本发明使用多叶片导流式旋流分相电容含水率法装置，通过导流式螺旋叶片对气液两相进行整流分离，使液相被迫分布在管壁形成液膜。由于本测量系统采用多组螺旋叶片，起旋效果显著。
如图1所示，为本发明涉及的差压法节流装置和旋流分相电容含水率法装置组合测量气液两相流量流量系统安装方式示意图。测量系统串联安装，图中共有8种安装方式，来流可先经过差压法节流装置测量两相流总的虚高质量流量，也可先经过旋流分相电容含水率法装置测量两相流中的液相含率，系统可水平安装，竖直向上或竖直向下安装，也可通过U形管(图中未示出)或倒U形管串联安装，此外，图中给出的或者是水平安装，或者是竖直安装的示意图，在实际应用中，也可以安装在倾斜的测量管道上。
图2为本发明的一个实施例，是一种差压法节流装置与旋流分相电容含水率法装置组合气液两相流量测量系统，采用水平安装的差压式流量计+旋流分相电容含水率传感器组成湿气两相流量测量系统，测量工业现场中湿天然气两相流量。测量方法如下：
(1)利用电容测量单元(电容测量段)测量体积含水率
气液两相流中体积含水率LVF的变化导致液膜厚度发生变化Δh/h 0，即液膜厚度值除以满管水时水层厚度h 0，进一步，液膜厚度的变化引起电容值的相对变化ΔC/C 0，即两相流由于液相的存在，引起的电容量变化除以单相气时电容值C 0，有：LVF→Δh/h 0→ΔC/C 0。根据体积含水率与电容之间的变化规律，建立相应的数学模型，有
LVF＝Ψ(ΔC/C 0)           (1)
(2)利用差压节流装置测量气相虚高质量流量W tp，有
Figure PCTCN2019076343-appb-000001
式中，式中：W tp为流体的虚高质量流量；C d为文丘里管的流出系数；ε为被测流体的可膨胀性系数；β为节流比，即喉部直径与入口直径之比d/D；ΔP tp为两相流通过节流件前后的压力差；ρ g为 气体的密度。
(3)虚高定义
差压法节流装置测量的气相虚高质量W tp与真实气相质量W g比值即为虚高，有
Figure PCTCN2019076343-appb-000002
(4)建立虚高模型
利用量纲分析法，建立虚高测量修正模型，形式为
OR＝Φ(LVF,ρ l/ρ g Fr g)             (4)
式中，LVF为利用电容测量单元测量的体积含水率，ρ l/ρ g为液气密度比，Fr g为气相弗劳德数,为气液两相流中气相惯性力与液体重力比值的平方根，为
Figure PCTCN2019076343-appb-000003
式中，U sg为气相表观流速，D为管道直径。
根据(1)式可获得体积含液率，根据(2)、(3)、(4)、(5)式可实现气相流速的迭代计算，从而求得气相、分相流量。
本发明的多叶片旋流分相电容含水率法装置，结构示意图如图3所示。可与任意单相差压式仪表串联组合使用，如孔板、文丘里、V锥等。本发明区别于以往的含水率测量装置，在于对气液两相进行旋流分相后进行电容的测量。如图3所示，气液两相经差压装置后流入旋流分相单元(旋流分相段)，用多组螺旋叶片同时起旋，液相能够与气相完全分离至管壁。液相由于密度偏大，在离心力作用下实现气相集中在中心区域、液相沿管壁的分相流动形态，从而克服流型对相含率测量的干扰。仿真研究发现，经过螺旋叶片后，气液分布基本稳定。在电容测量单元内，金属内芯(图3,2-1)作为内电极，外金属管壁(图3,2-3)与分布于管壁的液膜共同构成外电极，气相和绝缘层(图3,2-2)构成绝缘介质层，进而形成电容器，为提高电容灵敏度，需保证外金属管壁直径是金属内芯直径的2倍以上。
如图4所示，其中，图4(a1)为三螺旋叶片左视图，图4(a2)为三螺旋叶片剖面图正视图，图4(a3)为三螺旋叶片整体示意图。每个叶片夹角为120°，管道内径为D，螺距为2.5D；图4(b1)为四螺旋叶片左视图，图4(b2)为四螺旋叶片剖面图正视图，图4(b3)为四螺旋叶片整体示意图，每个叶片夹角为90°，设管道内径为D，螺距为1.5D。
利用CFD数值模拟方法，模拟空气水两相流在测量系统的中参数变化规律，气相表观流速为3m/s-20m/s，压力0.6MPa、0.8MPa,差压节流装置以文丘里为例，口径DN50,节流比0.55，体积含液率对 液膜厚度的影响、电容值的影响以及虚高的影响分析如下：
图5为0.6MPa下气相表观流速分别为3m/s、5m/s、10m/s、20m/s条件下的空气水两相流相对液膜厚度(液膜厚度值除以满管水时水层厚度h 0)与体积含液率LVF的变化关系，即LVF→Δh/h 0。由图5中我们可以看出，在不同气相流速下，液膜相对厚度随着含液率增大呈现了单调上升趋势；含液率相同时，气相流速越高，液膜厚度越薄。
图6为0.6MPa下气相表观流速为3m/s、20m/s空气水两相流相对液膜厚度与其引起的电容相对变化关系规律图，即Δh/h 0→ΔC/C 0，表明同一流速下，液膜相对厚度变化率越大，电容变化率越大；流速越小，相同液膜变化率下，电容相对变化率越大，表明较小流速下，电容变化越敏感，电容灵敏度高，液相量程下限越低，利于对低含液的测量。
[根据细则91更正 02.04.2019]
图7为：
图7(a)为：0.6MPa下，表观流速为3m/s、5m/s、10m/s、20m/s体积含液率LVF与电容相对变化关系规律图，即LVF→ΔC/C0。由图可见，气相流速越高，电容值越大，电容值随着LVF单调增加。
图7(b)为三个不同压力(0.6MPa,1.2MPa,1.6MPa)条件下，气相表观流速为10m/s对测量电容产生的影响。压力越高，相对电容变化越小。由于压力增高，气相密度增大，相同流速下，及含液率条件下，液相流速增大，液膜变薄，从而导致电容变化值的减小，各个压力下电容相对变化随着体积含液率LVF的变化趋势是一致的。
图8为0.6MPa下气相表观流速为3m/s、5m/s、10m/s和15m/s(气相弗劳德数分别为:0.395、0.645、1.280和1.912)空气水两相流流经口径DN50,节流比0.55的标准文丘里管时产生的虚高随体积含液率LVF的变化关系图，图中我们可以看出，文丘里虚高值随体积含液率的增大而增大，具有良好的规律性。
根据(1)式可获得体积含液率，根据(2)、(3)、(4)、(5)式的迭代计算，可实现气相流量的测量，根据总量和液相含率可求液相流量。
本发明并不限于上文描述的实施方式。以上对具体实施方式的描述旨在描述和说明本发明的技术方案，上述的具体实施方式仅仅是示意性的，并不是限制性的。在不脱离本发明宗旨和权利要求所保护的范围情况下，本领域的普通技术人员在本发明的启示下还可做出很多形式的具体变换，这些均属于本发明的保护范围之内。

Claims (10)

  1. 一种基于差压与旋流分相电容含水率传感器的湿气测量系统，包括固定在测量管道上的差压流量计和含水率传感器，其特征在于，差压流量计和含水率传感器水平安装，来流先经过差压流量计测量两相流总的虚高质量流量，再经过含水率传感器测量两相流中的液相含率，实现两相流量的非分离计量；所述的含水率传感器为旋流分相电容含水率传感器，包括旋流分相段和电容测量段，旋流分相段包括螺旋叶片支撑杆，分布在螺旋叶片支撑杆外周的两个以上的螺旋叶片和外管壁；电容测量段包括金属内芯，覆盖在金属内芯外周的绝缘层和外金属管壁。
  2. 根据权利要求1所述的系统，其特征在于，螺旋叶片的升角在30°～60°之间，每个螺旋叶片沿圆周均匀分布。
  3. 根据权利要求1所述的系统，其特征在于，螺旋叶片支撑杆的尾部与金属内芯的尺寸相配合并相互连接，外管壁和外金属管壁尺寸相配合并相互连接。
  4. 根据权利要求1所述的系统，其特征在于，设来流管道内径为D，外金属管壁内径为1～3D，螺旋叶片的螺距为0.5D～3D，电容测量单元长度为2D～6D，金属内芯直径与外金属管壁直径比为1:2～1:8。
  5. 根据权利要求1所述的系统，其特征在于，螺旋叶片支撑杆的迎水面为流线型。
  6. 一种气液两相流量测量系统，包括固定在测量管道上的差压流量计和含水率传感器，其特征在于，差压流量计和含水率传感器串联安装，差压流量计用于测量两相流总的虚高质量流量，含水率传感器用于测量两相流中的液相含率，实现两相流量的非分离计量；所述的含水率传感器为旋流分相电容含水率传感器，包括旋流分相单元和电容测量单元，旋流分相单元包括螺旋叶片支撑杆，分布在螺旋叶片支撑杆外周的两个以上的螺旋叶片和外管壁；电容测量单元包括金属内芯，覆盖在金属内芯外周的绝缘层和外金属管壁。
  7. 根据权利要求6所述的系统，其特征在于，螺旋叶片的升角在30°～60°之间，每个螺旋叶片沿圆周均匀分布。
  8. 根据权利要求6所述的系统，其特征在于，螺旋叶片支撑杆的尾部与金属内芯的尺寸相配合并相互连接，外管壁和外金属管壁尺寸相配合并相互连接。
  9. 根据权利要求6所述的系统，其特征在于，设来流管道内径为D，外金属管壁内径为1～3D，螺旋叶片的螺距为0.5D～3D，电容测量单元长度为2D～6D，金属内芯直径与外金属管壁直径比为1:2～1:8。
  10. 根据权利要求6所述的系统，其特征在于，螺旋叶片支撑杆的迎水面为流线型。
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