阅读说明：本技术 一种旋流状态下射频含水率测量仪及方法 (Radio frequency water content measuring instrument and method in cyclone state ) 是由 张兴凯 张振远 廖锐全 潘皓天 于 2019-11-29 设计创作，主要内容包括：本发明属于原油含水率测量技术领域,具体涉及一种旋流状态下射频含水率测量仪及方法。一种旋流状态下射频含水率测量仪,包括套管,套管一端与旋流器水平连接,另一端与导管垂直连接；套管外部设置有射频信号处理模块和通信电线保护罩,通信电线保护罩通过内部电线对射频信号处理模块供电以及信号传输；套管内部设置有与射频信号处理模块连接的射频天线；所述射频信号处理模块包括嵌入式单片机、信号源发生器、信号放大器、数据检测模块和数据采集卡。本发明利用旋流状态测量含水率,受不稳定油水分布的影响更小,测量结果更加精确。本发明可拆卸式零部件设计,能够及时清理天线表面结蜡结垢,更换部件方便,可延长使用寿命。(The invention belongs to the technical field of crude oil water content measurement, and particularly relates to a radio frequency water content measuring instrument and method in a cyclone state. A radio frequency water content measuring instrument in a rotational flow state comprises a sleeve, wherein one end of the sleeve is horizontally connected with a cyclone, and the other end of the sleeve is vertically connected with a guide pipe; the radio frequency signal processing module and the communication wire protection cover are arranged outside the sleeve, and the communication wire protection cover supplies power and transmits signals to the radio frequency signal processing module through the internal wires; a radio frequency antenna connected with the radio frequency signal processing module is arranged in the sleeve; the radio frequency signal processing module comprises an embedded single chip microcomputer, a signal source generator, a signal amplifier, a data detection module and a data acquisition card. The invention utilizes the rotational flow state to measure the water content, is less influenced by unstable oil-water distribution, and has more accurate measuring result. The design of the detachable parts can clean wax deposition and scale on the surface of the antenna in time, the parts are convenient to replace, and the service life can be prolonged.)

1. The utility model provides a radio frequency moisture content measuring apparatu under whirl state which characterized in that: comprises a sleeve (1), one end of the sleeve (1) is horizontally connected with a swirler (11), and the other end is vertically connected with a guide pipe (1.1); a radio frequency signal processing module (2) and a communication wire protection cover (4) are arranged outside the sleeve (1), and the communication wire protection cover (4) supplies power and transmits signals to the radio frequency signal processing module (2) through internal wires; a radio frequency antenna (5) connected with the radio frequency signal processing module (2) is arranged in the sleeve (1); the radio frequency signal processing module (2) comprises an embedded single chip microcomputer, a signal source generator, a signal amplifier, a data detection module and a data acquisition card.

2. The radio frequency water content measuring instrument in the swirling state according to claim 1, wherein: the radio frequency antenna (5) is in threaded connection with the sleeve (1), and the radio frequency antenna (5) is fixed at the axis of the sleeve (1) through the fixer (3).

3. The radio frequency water content measuring instrument in the rotational flow state according to claim 2, wherein: the structure of the radio frequency antenna (5) from outside to inside is a polytetrafluoroethylene antenna protective cover (7) and a silver-plated copper core (8), an external thread base (9) is arranged at one end of the radio frequency antenna (5), and an internal feed hole (10) is formed in the external thread base (9).

4. The method for measuring the water content by the radio frequency water content measuring instrument under the cyclone state according to the claims 1-3, characterized by comprising the following steps:

s1, connecting the cyclone (11) end of the measuring instrument with a crude oil pipeline, measuring the crude oil with known water content through the cyclone (11), and forming a two-phase flow with oil as an inner ring and water as an outer ring through the casing (1) after the crude oil is acted by the cyclone (11);

s2, the radio frequency antenna (5) generates a radio frequency signal of 40MHz-50MHz under the action of a signal source generator and a signal amplifier of the radio frequency signal processing module (2), and acts on the two-phase flow generated in the step S1;

s3, detecting the radio frequency signal after passing through the crude oil by a data detection module of the radio frequency signal processing module (2), inputting the radio frequency signal into a receiving circuit in the radio frequency signal processing module (2), obtaining the voltage value at two ends of the measuring resistor, and recording the voltage value in a data acquisition card;

s4, repeating S1-S3 operation on a plurality of groups of crude oil with different water contents, and measuring voltage values corresponding to the different water contents;

s5, establishing a corresponding relation between the measured voltage value data and the water content of the known crude oil, and fitting a water content prediction curve;

and S6, repeating the operation from S1 to S3 on the crude oil with the water content to be measured, calibrating the measured voltage value in the water content prediction curve obtained in S5, and obtaining and outputting and displaying the water content value.

Technical Field

The invention belongs to the technical field of crude oil water content measurement, and particularly relates to a radio frequency water content measuring instrument and method in a cyclone state.

Background

Crude oil water content measurement has been an important ring in three-phase flow measurement technology. At present, the measurement technology of the water content of crude oil is mainly divided into two categories, one category is an artificial measurement method, also called an offline measurement method, and mainly comprises a distillation method, an electric desorption method and a Karl Fischer method; one is an electrical method measurement, also called an on-line measurement method, mainly including a conductance method, a ray method, a capacitance method, an electromagnetic method and a radio frequency method.

At present, due to various unstable factors and incompleteness of the on-line measurement method, manual measurement is still used as the main crude oil water content measurement method in the first production line. The distillation method is mainly based on the boiling point difference of different mixtures in the output liquid, and the water content value in the output liquid is obtained after heating, cooling and condensation. The electric desorption method and the Karl Fischer method have the same problems, and have high cost and high cost. Therefore, the current practical production faces the dilemma, the measurement result of the manual method is accurate and the precision is high, but the manual method is not representative and is labor-consuming; the online method measurement method is convenient and timely, but has large errors, cannot meet the requirements of actual production, and is still needed to be popularized and applied, so that the research on the crude oil water content measurement technology needs to be broken through and solved urgently.

Disclosure of Invention

Aiming at the problems, the invention provides a radio frequency water content measuring instrument and a method in a rotational flow state.

The invention aims to provide a radio frequency water content measuring instrument in a rotational flow state, which comprises a sleeve, wherein one end of the sleeve is horizontally connected with a cyclone, and the other end of the sleeve is vertically connected with a guide pipe; the radio frequency signal processing module and the communication wire protection cover are arranged outside the sleeve, and the communication wire protection cover supplies power and transmits signals to the radio frequency signal processing module through the internal wires; a radio frequency antenna connected with the radio frequency signal processing module is arranged in the sleeve; the radio frequency signal processing module comprises an embedded single chip microcomputer, a signal source generator, a signal amplifier, a data detection module and a data acquisition card.

Furthermore, the radio frequency antenna is in threaded connection with the sleeve, and the radio frequency antenna is fixed at the axis of the sleeve through a fixer.

Furthermore, the structure of the radio frequency antenna from outside to inside is a polytetrafluoroethylene antenna protective cover and a silver-plated copper core, an external thread base is arranged at one end of the radio frequency antenna, and an internal feed hole is formed in the external thread base.

The second purpose of the invention is to provide a method for measuring radio frequency water content in a cyclone state, which comprises the following steps:

s1, connecting the cyclone end of the measuring instrument with a crude oil pipeline, measuring the crude oil with known water content through the cyclone, and forming a two-phase flow with oil as an inner ring and water as an outer ring through a sleeve after the crude oil is acted by the cyclone;

s2, the radio frequency antenna generates a radio frequency signal of 40MHz-50MHz under the action of a signal source generator and a signal amplifier of the radio frequency signal processing module, and acts on the two-phase flow generated in the step S1;

s3, detecting the radio frequency signal after passing through the crude oil by a data detection module of the radio frequency signal processing module, inputting the radio frequency signal into a receiving circuit in the radio frequency signal processing module to obtain the voltage value at two ends of the measuring resistor, and recording the voltage value in a data acquisition card;

s4, repeating S1-S3 operation on a plurality of groups of crude oil with different water contents, and measuring voltage values corresponding to the different water contents;

s5, establishing a corresponding relation between the measured voltage value data and the water content of the known crude oil, and fitting a water content prediction curve;

and S6, repeating the operation from S1 to S3 on the crude oil with the water content to be measured, calibrating the measured voltage value in the water content prediction curve obtained in S5, and obtaining and outputting and displaying the water content value.

The invention has the following beneficial effects:

the measurement principle is based on the radio frequency impedance theory of media, the water-containing crude oil is used as a dielectric medium, and the water content in the crude oil is reflected by measuring the impedance characteristic change of an oil-water mixture to a radio frequency signal.

And secondly, measuring the water content by using the rotational flow state, layering oil and water under the rotational flow action of a cyclone, forming an outer ring by using low oil density, and forming an inner ring by using high water density. The uneven distribution of the capacitor caused by too much oil-water mixing parts is avoided, so that the water content measuring instrument in the rotational flow state is more accurate in numerical value and is less influenced by the unstable oil-water distribution.

Thirdly, the design of detachable spare part can in time clear up the antenna surface wax deposit scale deposit, and it is convenient to change the part, can increase of service life.

Drawings

Fig. 1 is a schematic perspective view of a measuring instrument according to the present invention.

Fig. 2 is a schematic cross-sectional view of the measuring instrument provided by the present invention.

Fig. 3 is a schematic diagram of a work flow of the rf signal processing module.

Fig. 4 is a schematic cross-sectional view of the rf antenna of the present invention.

Fig. 5 is a front view of the fastener of the present invention.

FIG. 6 is a flow chart of a method for measuring radio frequency water content in a swirling state according to the present invention.

Fig. 7 is a moisture content-voltage value corresponding curve fitted in step S5 of the method for measuring moisture content under swirling state according to the present invention.

FIG. 8 is a schematic cross-sectional view of crude oil within a casing after swirling.

Wherein: the device comprises a sleeve 1, a radio frequency signal processing module 2, a fixer 3, a communication wire protective cover 4, a radio frequency antenna 5, a threaded port 6, an antenna protective cover 7, a silver-plated copper core 8, an external thread base 9, an internal feed hole 10 and a swirler 11.

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments. The present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments.

As shown in fig. 1-2, a radio frequency water content measuring instrument in a swirling state comprises a sleeve 1, wherein one end of the sleeve 1 is horizontally connected with a swirler 11, and the other end of the sleeve 1 is vertically connected with a guide pipe 1.1; a radio frequency signal processing module 2 and a communication wire protection cover 4 are arranged outside the sleeve 1, and the communication wire protection cover 4 supplies power and transmits signals to the radio frequency signal processing module 2 through internal wires; a radio frequency antenna 5 connected with the radio frequency signal processing module 2 is arranged in the sleeve 1; the radio frequency signal processing module 2 comprises an embedded single chip microcomputer, a signal source generator, a signal amplifier, a data detection module and a data acquisition card.

As shown in fig. 3, the radio frequency signal processing module 2 uses an embedded single chip microcomputer STM32F407 as a core, a carried signal source module AD9851 as a signal source generator, performs signal logarithmic amplification through an AD8310 signal amplifier, and provides an output frequency of 0MHz-70MHz for a radio frequency antenna. And simultaneously, an instrument amplifier for measuring the resistance and the two sections of the resistance is used for data detection of radio frequency outgoing signals and outputting direct current voltage at the receiver, and a data acquisition card for recording data is used.

The diameter of the steel casing 1 is 25.4mm, the left side is connected with a swirler 11, and swirlers 11 with different specifications are selected according to required performance. The upper portion of the steel sleeve 1 is provided with a radio frequency signal processing module 2 and a communication wire protection cover 4, the communication wire protection cover 4 supplies power to the radio frequency signal processing module 2 through an internal wire and transmits signals, and the specific size of the radio frequency signal processing module 2 is determined according to a selected communication module.

Wherein, the radio frequency antenna 5 is screwed in from the screw thread opening at the right side of the steel casing 1 and is fixed at the axle center of the casing 1 through the fixer 3.

As shown in fig. 4, the total length of the rf antenna 5 is 210mm, the rf antenna 5 is composed of a teflon antenna protective cover 7 and a silver-plated copper core 8 from outside to inside, an external thread base 9 is arranged at one end of the rf antenna 5, and an internal feed hole 10 is arranged on the external thread base 9. Wherein the outer diameter of the polytetrafluoroethylene antenna protective cover 7 is 8mm, and the length thereof is 203 mm; the length of the internal silver-plated copper core 8 is 200mm, and the external diameter is 7mm, and the internal silver-plated copper core is used as a feed antenna; the right-side tail part is provided with an external thread base 9 with the length of 10mm and the outer diameter of 10mm, the outer ring is provided with threads corresponding to the thread opening 6 of the pipeline part, the axis is provided with an internal feed hole 10 with the diameter of 2mm, and the external thread base is used for supplying power to the radio frequency antenna 5 and externally connecting a radio frequency signal source.

Fig. 5 is a three-dimensional structure diagram of the fixer 3, the center of the fixer 3 is a hollow circular ring with the diameter of 8mm and the width of 1mm, the outer side of the fixer is composed of three rectangular supports with the width of 1mm and the length of 7.8mm, and the three supports trisect the circumference. The radio frequency antenna 5 passes through the axis of the fixer 3 when being installed, and plays a role of stabilizing the antenna in the rotational flow.

As shown in fig. 6, a method for measuring moisture content by using a radio frequency moisture content measuring instrument in a swirling state includes the following steps:

s1, connecting the end of the swirler 11 of the measuring instrument with a crude oil pipeline, measuring the crude oil with known water content through the swirler 11, and forming a two-phase flow with oil as an inner ring and water as an outer ring through the sleeve 1 after the crude oil is acted by the swirler 11;

s2, the radio frequency antenna 5 generates a radio frequency signal of 40MHz-50MHz under the action of the signal source generator and the signal amplifier of the radio frequency signal processing module 2, and acts on the two-phase flow generated in the step S1;

s3, the data detection module of the radio frequency signal processing module 2 detects the radio frequency signal after passing through the crude oil, and inputs the radio frequency signal into the receiving circuit in the radio frequency signal processing module 2 to obtain the voltage value at the two ends of the measuring resistor, and records the voltage value in the data acquisition card;

s4, repeating S1-S3 operation on a plurality of groups of crude oil with different water contents, and measuring voltage values corresponding to the different water contents;

s5, establishing a corresponding relation between the measured voltage value data and the water content of the known crude oil, and fitting a water content prediction curve (shown in figure 7);

and S6, repeating the operation from S1 to S3 on the crude oil with the water content to be measured, calibrating the measured voltage value in the water content prediction curve obtained in S5, and obtaining and outputting and displaying the water content value.

Fig. 8 is a schematic cross-sectional view of crude oil after swirling in the casing 1, and the right center circle is a radio frequency antenna. Regarding the radio frequency antenna from the outer interface to the oil-water interface and from the oil-water interface to the inner wall of the pipeline as two different cylindrical capacitors, where r is the radius of the antenna and r is the length of the antenna₀The radius of the oil section in the pipe is the position of an oil-water interface, R is the inner diameter of the pipeline, the length L of the antenna and the water content D.

The cross-sectional area of the annular oil is S_OilThe cross-sectional area of the ring-shaped water is S_{Water (W)}The antenna cross-sectional area is S_SkyThe cross-sectional area of the whole liquid in the pipeline is S_{Liquid for treating urinary tract infection}。

Then

S_{Liquid for treating urinary tract infection}＝πR²-S_Sky＝π(R²-r²) (2)

S_Oil＝S_{Liquid for treating urinary tract infection}-S_{Water (W)}＝(1-D)S_{Liquid for treating urinary tract infection}(3)

Wherein: v_{Water (W)}Is the volume of pure water in the tube; v_{Liquid for treating urinary tract infection}Is the volume of all liquid in the tube; l_PipeIs the gauge pipe length.

And also

S_Oil＝πr₀ ²-πr²(4)

The following expressions (2) to (4) can be used:

the calculation formula of the cylinder capacitance can be obtained as follows:

wherein: c_Aerial-oilIs the capacitance value between the antenna and the oil-water interface; c_Oil-waterThe capacitance value between the oil-water interface and the inner wall of the pipeline is obtained; l is_SkyIs the antenna length; epsilon₀For vacuum dielectric constant, an approximation of 8.854187817X 10 is taken^-12F/m；ε_OilIs the dielectric constant of the oil；ε_{Water (W)}Is the dielectric constant of water.

The two capacitors are combined internally and externally, and can be regarded as series capacitors, and the total capacitance C is calculated as follows:

when the rf signal penetrates the medium, the total system impedance Z is:

R_{is connected with}For receiving the equivalent resistance of the sensor, f is the transmitting frequency of the radio frequency antenna, C is the total capacitance, Z is the total system impedance, J is a complex number, a purely mathematical symbol has no practical physical significance.

When the system impedance is determined, the current in the receiver is:

i is the current in the receiver and U is the overall voltage.

Adding a detection resistor R_MeasuringThen, the resistance R is detected_MeasuringThe voltages at both ends are:

U_measuring＝IR_Measuring(11)

U_MeasuringFor measuring the voltage across the resistor, R_MeasuringThe resistance is measured.

Because of different water content D, the oil and water are separated after the rotational flow, and the radius r of the oil section₀Changes occur, resulting in a change of the two-part cylindrical capacitance value, a change of the total capacitance and thus a change of the system current in the receiver. Because the frequency and the length of the radio frequency antenna are constants, the voltage of the radio frequency generator and the voltage of the receiver are fixed, so that the voltage value U at the two ends of the measuring resistor corresponds to the water content D of the oil product, and the water content is obtained by adjusting the coefficient.

Details not described in this specification are within the skill of the art that are well known to those skilled in the art.