CN217466729U

CN217466729U - Oil water content online detection system based on microwave technology

Info

Publication number: CN217466729U
Application number: CN202123036266.6U
Authority: CN
Inventors: 张涛; 陈晓; 韩冰; 胡学梅
Original assignee: Jilin University
Current assignee: Jilin University
Priority date: 2021-12-06
Filing date: 2021-12-06
Publication date: 2022-09-20
Anticipated expiration: 2031-12-06

Abstract

The utility model relates to an online detection system of oil moisture content based on microwave technology, by the microwave signal source, install microwave resonance unit, output signal processor, parameter detecting element, PC end and the microwave transmission line in the oil pipeline and constitute, microwave resonance unit links to each other with microwave signal source and output signal processor through the microwave transmission line respectively, microwave signal source and output signal processor all are connected to parameter detecting element, parameter detecting element connects the PC end; the microwave resonance unit comprises a resonance cavity wall, an upper pipeline, a lower pipeline, a sample cavity, a probe, an upper gear, a lower gear, a microwave transmitting port and a microwave receiving port. The utility model has the advantages of low cost, fast data acquisition speed, low power consumption of microwave signals and easy installation; the detection method has the advantages of wide application range, no harm to human bodies, high detection speed, accurate detection, high data updating speed, capability of detecting the water-containing quality of oil liquid in an industrial chain in real time and convenience for real-time monitoring of workers.

Description

Microwave technology-based oil water content online detection system

Technical Field

The utility model belongs to the technical field of oil moisture content on-line monitoring under the microwave technology, concretely relates to oil moisture content on-line measuring system based on microwave technology.

Background

With the development of economy and science and technology, the requirement of human beings on the finished oil is more and more increased, and meanwhile, the quality of the finished oil is also more and more regarded, wherein the water content of the finished oil is an important factor influencing the quality of the finished oil. The finished oil is prepared by producing and processing crude oil, mainly comprises petroleum fuel, petroleum solvent, lubricating oil and the like, and has extremely low moisture content. The water content in the product oil has important influence on the reliability, safety and the like of various power system hydraulic systems, fuel systems and lubricating oil systems. Excessive moisture in the finished oil can cause hidden danger to the safety of industrial equipment. Under the national standard, the water content in the lubricating oil is lower than 0.03%, and the water content of part of oil is zero. Because the water exists in the oil, the oil is oxidized and deteriorated, and the lubricating oil is emulsified, so that the quality of the lubricating oil is reduced, and the lubricating effect is poor; in the same way, water in the oil can aggravate the corrosion of organic acid to metal and corrode equipment, so that serious mechanical accidents such as shaft sticking and burning of an engine are caused. Therefore, accurate and online detection of the water content of the oil is an important link in the industrial production process, so that potential safety hazards and capital loss are reduced.

At present, the methods for detecting the water content of oil mainly comprise a density method, a capacitance method, an ray method, a microwave method and the like. The water content of the oil liquid measured by the density method is calculated by the densities of pure oil and pure water, but the densities of water and oil are greatly influenced by temperature and other factors, so that the accuracy of measuring the water content of the oil liquid by the density method is insufficient. The capacitance method measurement mode is to realize the detection of the moisture according to the change of the moisture in the oil liquid and the change of the capacitance, but the detection range of the measurement mode is smaller; the ray method has higher measurement accuracy, but the cost is high, and the universal application cannot be realized; meanwhile, the ray also has certain harm to human body.

At present, most of existing devices for detecting the water content of oil by utilizing a microwave technology are used for detecting crude oil with high water content; the traditional detection of the low-water-content oil liquid is to extract a small amount of samples and detect the oil liquid in a laboratory, so that the dynamic water content change of the oil liquid in the production and transmission processes cannot be detected on line in real time; the existing device for monitoring the water content of the low-water-content oil on line has low accuracy and insufficient sensitivity.

Disclosure of Invention

An object of the utility model is to provide a detection system who installs convenient microwave cavity technology and detect fluid moisture content to solve the problem of online accurate detection fluid moisture content, can obtain the moisture condition of the fluid of surveying in real time, fast, accurately. The utility model discloses a biparametric detection method can improve detection device's precision greatly, can realize installing functions such as convenient, on-line monitoring on production line and transmission line simultaneously.

The utility model aims at realizing through the following technical scheme:

an oil water content online detection system based on a microwave technology is composed of a microwave signal source 1, a microwave resonance unit 2 installed in an oil conveying pipeline, an output signal processor 3, a parameter detection unit 4, a PC (personal computer) end 5 and a microwave transmission line 6; the microwave resonance unit 2 is respectively connected with a microwave signal source 1 and an output signal processor 3 through a microwave transmission line 6, the microwave signal source 1 and the output signal processor 3 are both connected to a parameter detection unit 4, and the parameter detection unit 4 is connected with a PC (personal computer) end 5;

the microwave resonance unit 2 comprises a resonance cavity wall 8, an upper pipeline 7 and a lower pipeline 9 which are fastened with the resonance cavity wall 8, a sample cavity 10 for containing detection oil, one or two probes arranged in the sample cavity 10, an upper gear 11 and a lower gear 12 which are arranged on the upper side and the lower side of the sample cavity 10, a microwave transmitting port 17 and a microwave receiving port 18; the resonant cavity wall 8 is tightly contacted with the sample cavity 10, and oil is injected into the sample cavity 10 through the upper pipeline 7 and is contacted with the resonant cavity wall 8; the microwave transmitting port 17 and the microwave receiving port 18 are provided with SMA adapter ports which penetrate through the resonant cavity wall 8 and are fixed in the resonant cavity; the probe is inserted into the inner side of the SMA adapter, and the outer side of the SMA adapter is respectively connected with the microwave transmission line 6;

the microwave signal source 1 is connected to the microwave transmitting port 17 through a microwave transmission line 6, a microwave signal is input into the resonant cavity through the probe, and when the input microwave wavelength is matched with the size of the resonant cavity, standing waves are formed in the cavity to generate a resonance phenomenon; the microwave signal is received by the probe and then transmitted to the output signal processor 3 through the microwave transmission line 6 by the microwave receiving port 18.

Further, the upper and

lower pipes

7, 9 are fastened to the cavity wall 8 by means of four screws 20 and four nuts 19.

Furthermore, the resonant cavity is an open cylindrical resonant cavity, two ends of the resonant cavity are composed of an upper gear 11 and a lower gear 12, and the resonant cavity wall 8 is tightly contacted with the upper pipeline 7 and the lower pipeline 9 through the upper gear 11 and the lower gear 12 to form a whole.

Further, the SMA adapter does not completely penetrate through the resonant cavity wall 8, and the distance from the inner side of the SMA adapter to the sample cavity 10 is 0.1-0.8 mm.

Furthermore, the number of the probes is two, the microwave transmitting probe 15 and the microwave receiving probe 16 are not directly contacted with the resonant cavity wall 8, an interval is reserved between the probes and the resonant cavity wall 8, and the microwave transmitting probe 15 and the microwave receiving probe 16 are respectively connected with the left side SMA adapter port 13 and the right side SMA adapter port 14 in an inserting mode.

Furthermore, the microwave signal source 1 is a microwave voltage-controlled oscillator, the output signal processor 3 is a power converter, and the parameter detection unit 4 is a voltage detection unit.

Further, the probe is one, and the single probe transmits and receives the microwave signal.

Further, the microwave signal source 1 is replaced by a broadband microwave source; meanwhile, part of the transmitted signals are input into a receiver, and input signals are detected; the output signal processor 3 is replaced by an output signal collecting unit consisting of a power divider and a directional coupler; the parameter detection unit 4 is replaced by a receiver to realize the detection of the incident signal and the reflected signal.

Compared with the prior art, the beneficial effects of the utility model are that:

1. the utility model has the advantages of low cost, fast data acquisition speed (only a few minutes rather than a few hours), low power consumption of microwave signals, easy installation, etc.;

2. the utility model integrates a microwave signal source, a microwave resonant cavity, an output signal processor, a parameter detection unit and a PC end, and systematically on-line nondestructive detection of the water content of oil is realized by utilizing double-parameter measurement, the detection system has the characteristics of small volume, accurate measurement, easy installation, wide application range and the like, the accurate on-line detection of the water content of the oil on a production line and a transmission line is realized, the problems of overlarge detection system, complex installation and disassembly and the like are solved, and the microwave resonant cavity is accessed as a part of a pipeline and has no influence on the whole production line and transmission line pipeline fluid;

3. the detection system and the detection method have the advantages of wide application range, economy and applicability, lower power of the microwave generating source, less generated radiation and no harm to human bodies; the detection system is high in detection speed, accurate in detection and high in data updating speed, can realize real-time detection of the water-containing quality of oil in an industrial chain, and is convenient for workers to monitor in real time.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention, and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

Fig. 1 is a structural block diagram of the microwave technology oil water content monitoring system of the utility model;

fig. 2 is a structural view of a microwave resonance unit;

FIG. 3 is a plan view showing the structure of a microwave resonance unit;

FIG. 4 is a diagram of the mode field structure of the cylindrical resonant cavity TE 111;

FIG. 5 is a graph of dual probe cavity S parameter versus frequency f;

FIG. 6 is a graph of single probe cavity S parameter versus frequency f;

FIG. 7 is a graph showing the relationship between the resonant frequency f and the output power P when oil with a water content of 0 is added into the cylindrical resonant cavity and oil with a certain water content is added into the cylindrical resonant cavity.

In the figure: 1. the microwave signal source 2, the microwave resonance unit 3, the output signal processor 4, the parameter detection unit 5, the PC end 6, the microwave transmission line 7, the upper pipeline 8, the resonance cavity wall 9, the lower pipeline 10, the sample cavity 11, the upper gear 12, the lower gear 13, the left SMA adapter port 14, the right SMA adapter port 15, the microwave transmitting probe 16, the microwave receiving probe 17, the microwave transmitting port 18, the microwave receiving port 19, the nut 20 and the screw.

Detailed Description

The present invention will be further described with reference to the following examples:

the present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures. Meanwhile, in the description of the present invention, the terms "first", "second", and the like are used only for distinguishing the description, and are not to be construed as indicating or implying relative importance.

The utility model uses HFSS simulation technology to realize the electromagnetic simulation of the cylindrical resonant cavity and determine the resonant cavity size with the best simulation result; through radius, length, the probe of optimize module pair resonance chamber in emulation software HFSS stretch into cavity length, gear thickness, gear tooth number and optimize, find the quality factor better, can obviously distinguish the resonance cavity size of different aqueous fluids, combine the experiment to verify the utility model discloses can obtain the moisture content of different fluids fast.

The size of the cylindrical resonant cavity is related to the resonant wavelength and the working mode, and the dielectric loss coefficient of water is larger and more stable when the frequency is 9.0-10.0 GHz; therefore, the resonant frequency of the resonant cavity is 9.0-10.0 GHz.

Under the double-probe resonance unit and the single-probe resonance unit, the working mode of the resonant cavity is TE111 mode, as shown in FIG. 3. Preliminarily calculating the size of the cavity according to the formula (1), the formula (2) and the formula (3), and the resonance wavelength lambda of the cavity ₀ Resonant frequency f and quality factor Q ₀ Respectively as follows:

wherein, R is the radius of the cylindrical resonant cavity, L is the length of the cylindrical resonant cavity, delta is the skin depth, and c is the speed of light.

Through the HFSS simulation, a cylindrical resonant cavity with a proper size is found, and the online detection of the water content of the oil liquid is realized by combining the whole detection system.

As shown in fig. 1, the utility model discloses an online detection system of oil moisture content based on microwave technology, by microwave signal source 1, microwave resonance unit 2, output signal processor 3, parameter detecting element 4, PC end 5 and microwave transmission line 6 constitute; the microwave resonance unit 2 is respectively connected with the microwave signal source 1 and the output signal processor 3 through a microwave transmission line 6. The microwave signal source 1 and the output signal processor 3 are both connected to a parameter detection unit 4 for detecting microwave signal parameter information of the microwave signal source 1 and the output signal processor 3.

The microwave resonance unit 2 comprises a resonance cavity wall 8, an upper pipeline 7, a lower pipeline 9, one or two probes extending into the resonance cavity, an SMA adapter port for placing the resonance cavity, a sample cavity 10 for containing detection oil, an upper gear 11, a lower gear 12, a microwave transmitting port 17 and a microwave receiving port 18. The upper gear 11 and the lower gear 12 are arranged at the upper side and the lower side of the sample cavity 10. The sample chamber 10 is in close contact with the resonator wall 8. The upper pipeline 7, the lower pipeline 9 and the resonant cavity wall 8 are fastened through four screws 20 and four nuts 19, and can be connected with an oil pipeline of a specific measuring system through the screws and the nuts.

The resonant cavity is an open cylindrical resonant cavity, two ends of the resonant cavity are composed of an upper gear 11 and a lower gear 12, and the gear structure is favorable for increasing the flow of oil through the resonant cavity and the resonance of the resonant cavity, so that the quality factor of the resonant cavity is increased; the resonant cavity wall 8 is tightly contacted with the upper pipeline 7 and the lower pipeline 9 through an upper gear 11 and a lower gear 12 to form a whole.

The probe may be a single probe or a dual probe.

When the probe is a double probe, the microwave transmitting probe 15 and the microwave receiving probe 16 are respectively not directly contacted with the resonant cavity wall 8, and a gap is reserved between the probe and the resonant cavity wall 8 to prevent short circuit. The left SMA adapter port 13 is arranged at the position of the microwave transmitting port 17, the microwave transmitting probe 15 is inserted on the inner side of the left SMA adapter port 13, and the outer side of the left SMA adapter port 13 is connected with the microwave transmission line 6. Similarly, the right SMA adapter 14 is placed on the microwave receiving port 18, the receiving microwave probe 16 is inserted on the inner side of the right SMA adapter 14, and the outer side of the right SMA adapter 14 is connected with the microwave transmission line 6.

At this time, the microwave signal source 1 uses a microwave voltage-controlled oscillator under the condition that one end of the dual-probe transmits and the other end receives microwave signals; the output signal processor 3 may use a power converter; the parameter detection unit 4 adopts a voltage detection unit to realize measurement of relevant parameters.

The microwave signal source 1 is connected to the microwave transmitting port 17 through the microwave transmission line 6, the microwave signal is input into the resonant cavity through the microwave transmitting probe 15, when the input microwave wavelength is matched with the size of the resonant cavity, standing waves are formed in the cavity, and a resonance phenomenon occurs; the microwave signal is received by the microwave receiving probe 16 and then transmitted to the output signal processor 3 through the microwave transmission line 6 by the microwave receiving port 18.

In the case of a single probe, only one of the microwave transmitting probe 15 and the microwave receiving probe 16 extending into the resonant cavity is reserved, and the single probe transmits and receives microwave signals.

Under the condition that the single probe transmits and receives microwaves, the microwave signal source 1 can be replaced by a broadband microwave source; simultaneously inputting part of the transmitted signals into a receiver, and detecting input signals; the output signal processor 3 can be replaced by an output signal collecting unit consisting of a power divider and a directional coupler; the parameter detection unit 4 may be replaced by a receiver to detect the incident signal and the reflected signal.

The SMA adapter port does not completely penetrate through the resonant cavity wall 8, and the distance from the inner side of the SMA port to the sample cavity 10 is 0.1-0.8 mm.

The utility model discloses 2 each partial materials of well microwave resonance unit and size are selected, in the two probe resonant cavities: the upper pipeline 7, the lower pipeline 9 and the resonant cavity wall 8 are made of metal materials, the inner radius of the upper pipeline is 8-13 mm, and the thickness of the upper pipeline is 4-8 mm; the microwave transmitting probe 15 and the microwave receiving probe 16 are made of copper materials, the length is 3-5 mm, and the radius is 0.25-0.5 mm; the probe is arranged in the middle of the axial direction of the resonant cavity; the upper gear 11 and the lower gear 12 are made of metal, the thickness of the gears is 0.8-1.5 mm, and the number of the gears is 4-12; the height of the resonant cavity is 15 mm-25 mm.

Within a single probe resonant cavity: the upper pipeline 7, the lower pipeline 9 and the resonant cavity wall 8 are made of metal materials, the inner radius of the upper pipeline is 19-23 mm, and the thickness of the upper pipeline is 4-8 mm; the microwave transmitting probe 15 and the microwave receiving probe 16 are made of copper materials, the length is 3-5 mm, and the radius is 0.25-0.5 mm; the probe is arranged in the middle of the axial direction of the resonant cavity; the upper gear 11 and the lower gear 12 are made of metal materials, the thickness of the gears is 2-5 mm, and the number of gear teeth is 6-12; the height of the resonant cavity is 45 mm-55 mm.

The microwave resonance unit of the present invention is shown in fig. 2 and fig. 3, and the microwave transmitting probe 15 and the microwave receiving probe 16 extending into the resonant cavity in the figure are coupled probes arranged in the sample cavity 10 to transmit and receive electromagnetic waves. The resonant cavity wall 8 is in close contact with the sample cavity 10, oil is directly injected into the sample cavity 10 through the upper pipeline 7, and the oil is directly in contact with the resonant cavity wall 8.

The detection method under the oil water content detection system based on the microwave technology comprises the following steps:

A. the microwave resonance unit 2 is installed in an oil delivery pipe, and oil flows into the sample chamber 10 through the upper pipe 7 and finally flows out of the lower pipe 9. In the process that the oil liquid flows through the sample cavity, the oil liquid is ensured to be laminar flow, the generation of bubbles is reduced, and errors caused to experimental results are avoided;

B. connecting a microwave signal source 1 and an output signal processor 3 to a microwave resonance unit 2; connecting a parameter measuring unit 4 to a microwave signal source 1 and an output signal processor 3; the PC terminal 5 is connected to the parameter detection unit 4.

C. Detecting the input voltage of a voltage controlled oscillator by a voltage detection device under the double-probe resonance unit, thereby obtaining a resonance frequency f; detecting the voltage output by the power converter to obtain the output power P of the resonant cavity, and calculating the water content of different oil liquids by utilizing the double-parameter measurement; or under the single-probe resonance unit, the resonance frequency f of the input resonant cavity and the microwave power P reflected in the resonant cavity are detected by the receiver, and the water content of different oil liquids is calculated by utilizing the double-parameter measurement.

Principle for detecting water content of oil

The water molecules are polar, and under the action of an external electric field, the water molecule electric dipoles can be rearranged under the action of the electric field to generate a rotary polarization phenomenon. In the water molecule polarization process, external electric field energy is absorbed and stored as potential energy; meanwhile, the absorbed energy of the external electric field is released in the form of heat energy due to the collision among water molecules in the polarization process. Water molecules have a high degree of electrical displacement and thus react strongly to microwave energy. But the oil has a low electric potential shift and a small response to microwave energy. In the resonant cavity, the dielectric constant of the oil can be changed due to little water in the oil; in the resonant cavity, because the oil liquid with different water contents has different reactions to the microwave energy, the dielectric constants of the oil liquid are different, and the resonant frequency of each time and the microwave power value output from the resonant cavity are different accordingly.

Before system detection, equipment preheating needs to be carried out on the whole system, the preheating time is 30 minutes, meanwhile, the external temperature is guaranteed to be unchanged in the detection process, and otherwise, temperature correction needs to be carried out.

When the system is detected, oil to be detected is injected into the sample cavity 10, the dielectric constant in the whole sample cavity is slightly changed (large volume and small epsilon change), and the system monitoring is started; the microwave signal source 1 oscillates in a predetermined frequency range of 9 to 15GHz, and a microwave signal is input into the resonant cavity through the probe, and at a certain frequency, an electromagnetic wave oscillates in the resonant cavity to form a standing wave, so that a resonance phenomenon occurs.

The utility model adopts an open cylindrical resonant cavity, when the dual probes in the resonant cavity transmit and receive microwave signals and only one probe in the resonant cavity transmits and receives microwaves, the working mode is TE111 mode, when the length L of the cavity is more than 2.1R, the TE111 mode is the lowest mode in the resonant cavity, and the interference modes are less; the cavity is small and the frequency band is wide; as shown in fig. 4: the direction of the electric field in the cavity points to the outside of the cavity, and the magnetic field points to the top of the cylindrical cavity from the bottom of the cylindrical cavity along the surface of the cavity. The resonant frequency of the resonant cavity is 9.0-10.0 GHz, the dielectric constant of water is about 70 and the dielectric constant of oil is about 2.3 near 9.0-10.0 GHz; and the dielectric loss coefficient of water is much larger than that of oil, the corresponding resonant wavelength is not large, and the designed resonant cavity is small in size and convenient to install.

Preliminarily calculating the size of the cavity according to the formula (1), the formula (2) and the formula (3), and the resonance wavelength lambda of the cavity ₀ Resonant frequency f and quality factor Q ₀ Respectively as follows:

The size of the primary cavity is obtained through the formula, the size of the cavity is corrected through HFSS simulation, the length of the probe extending into the cavity, the number of teeth of the gear and the thickness of the gear are determined, and finally the size of the resonant cavity with high quality factor Q value and high resolution is obtained.

The online detection of the water content of the oil based on the microwave technology is carried out by determining the change of the resonant frequency after the sample is added into the resonant cavity and before the sample is not added, and the dielectric constants of the oil with different water contents are obtained by calculating the resonant frequency, so that the measurement of the water content of the oil is realized. The resonant wavelength is constant in a particular resonant cavity, and the resonant frequency changes with the change in the dielectric constant of the sample due to the change in the dielectric constant of the sample in the sample cavity. When a sample to be detected is not added into the system (when air exists in the sample cavity), the microwave voltage-controlled oscillator outputs 9-15 GHz microwave, and a microwave signal with a certain frequency resonates in the resonant cavity; after the sample cavity is filled with oil, the frequency of the microwave signal which resonates in the cavity changes, and at the moment, the power value output from the resonant cavity also changes correspondingly.

Further, the water content of the oil liquid is obtained through the relation between the resonant frequency and the dielectric constant of the resonant cavity and the added sample and the linear relation between the power attenuated by the resonant cavity and the water content, and the implementation method of the double-parameter measurement comprises the following steps:

under the double-probe resonant unit, the microwave voltage-controlled oscillator inputs a low-power microwave signal into the resonant cavity, and the power converter receives the microwave signal power output from the resonant cavity and converts the microwave signal power into voltage. The voltage detection unit detects the voltage input to the microwave voltage-controlled oscillator, and a corresponding frequency value f is obtained through calculation; the voltage detection unit detects the voltage output by the power converter, and the power value P of the microwave signal output from the resonant cavity is calculated. Under the single-probe resonance unit, a broadband microwave source transmits microwave signals into a resonant cavity, meanwhile, part of the transmitted signals are input into a receiver, and the input microwave frequency f is detected; an output signal collecting unit composed of a power divider and a directional coupler is used for receiving microwave signals reflected from the resonant cavity and finally inputting the microwave signals to a receiver, and the receiver detects the microwave power value P reflected from the resonant cavity. The obtained detected value of the relevant parameter is sent to the PC terminal 5.

The utility model discloses a realize that the used key part of fluid moisture content on-line measuring is resonant cavity unit 2 based on microwave technology. In the resonant cavity, electromagnetic waves are reflected back and forth in the cavity, and when the wavelength of the electromagnetic waves is matched with the size of the resonant cavity, standing waves are generated and resonance occurs; the whole cavity is filled with a sample, and dielectric perturbation is realized through large-volume and small-dielectric change; when the dielectric constant of the sample in the resonant cavity changes, the electromagnetic field, the resonant frequency and the output power value in the cavity also change. The utility model discloses a sample in the well resonant cavity is the fluid of different moisture, and the water content changes in the fluid, and its dielectric constant also can change, and the change of dielectric arouses intracavity resonant frequency and resonant cavity's output's change. And finally, the resonant frequency and the microwave output power are related to the water content of the oil.

The microwave signal source 1 inputs low-power broadband microwaves into the resonant cavity through the microwave transmission line 6, at the moment, the electromagnetic waves are transmitted back and forth in the sample cavity 10 containing oil, the microwave receiving probe 16 receives the electromagnetic waves, the output signal processor 3 outputs the received electromagnetic wave signals, and finally, related microwave signal parameters are detected through the parameter detection unit 4. The parameter detection unit 4 detects the frequency input to the microwave resonance unit 2, thereby obtaining a corresponding resonance frequency value f; the parameter detection unit 4 detects the voltage value after the power conversion of the output microwave signal in the output signal processor 3, and calculates the output power value P of the resonant cavity.

When no sample is added in the sample cavity (cavity), the electromagnetic wave resonates in the resonant cavity; when oil is injected into the sample cavity, the resonant frequency f, the S parameter and the quality factor Q value are correspondingly changed, the resonant frequency is changed along with the change of the dielectric constant, and the water content of the oil is calculated through the resonant frequency of the oil and the resonant frequency of the cavity; in the double-probe and single-probe resonant units, the curves of the resonant frequency f and the S parameter of the cavity and the injection oil resonant cavity are respectively shown in fig. 5 and fig. 6.

By measuring the resonant frequency f and the output power P of the resonant cavity, the water content of the oil can be calculated through the parameters. The utility model discloses a two parameter detection, the method is as follows:

a microwave signal source 1 inputs low-power broadband microwaves (9 GHz-15 GHz) into a resonant cavity through a microwave transmission line 6, at the moment, the electromagnetic waves propagate back and forth in a sample cavity 10 containing oil, a microwave receiving probe 16 receives the electromagnetic waves, an output signal processor 3 outputs received electromagnetic wave signals, and finally microwave power output by the resonant cavity is detected through a parameter detection unit. When no oil is added (under the cavity), the corresponding resonant power f is obtained through the PC end _vac After the sample chamber 10 is filled with oil of different water contents, the dielectric constant of the oil is epsilon _mix And the same resonance frequency f of the oil with a certain water content is obtained at the PC end _mix . The dielectric constant epsilon of the oil can be obtained according to the following formula _mix ：

Transforming equation (4) to obtain equation (5), as follows:

from the Brougerman equation, the dielectric constant ε of water is known _water Dielectric constant ε of oil _oil (dielectric constant ε of water at a constant temperature _water Dielectric constant ε of oil _oil Is a constantCounting), the water content beta of the oil liquid can be obtained; the water content beta of the oil is calculated by the following formula:

the PC end can receive the attenuation power of the resonant cavity at the same time, and the output power of the resonant cavity is P under the condition of the resonant cavity _vac (ii) a When the oil is injected into the resonant cavity, the output power of the resonant cavity is P _mix . The input power of the microwave signal is constant and is P ₀ . With the increase of the water content in the oil liquid, the loss of the microwave energy in the resonant cavity is increased, the oil liquid with different water content is injected into the resonant cavity, and the obtained output power value is different accordingly. After the microwave passes through the medium, the attenuation N of the resonant cavity is calculated by the following formula:

in the formula: p ₁ Representing the power output by the resonant cavity; p ₀ Representing the input power to the cavity.

Respectively obtaining the attenuation N under the cavity from the formula (7) ₀ And the attenuation N' after the oil is added; the formula is as follows:

the relation between the attenuation N and the water content beta of the oil can be obtained through statistical analysis on the accurate measurement of the microwave power attenuation, such as the following formula:

β＝kN (10)

in the formula: k is a scaling factor.

According to statistical analysis, the numerical value of the proportional coefficient k is determined, and the water content of the oil can be obtained through the formula (10); the utility model discloses a detection method is through measuring resonant frequency f and resonant cavity output power P two parameters, realizes the moisture content of accurate measurement fluid.

Example 1

The utility model discloses an online detection system of oil water content based on microwave technology, which comprises a microwave signal source 1, a microwave resonance unit 2, an output signal processor 3, a parameter detection unit 4, a PC end 5 and a microwave transmission line 6; the microwave resonance unit 2 is respectively connected with the microwave signal source 1 and the output signal processor 3 through a microwave transmission line 6.

In the utility model, the microwave resonance unit 2 is made of materials, and in the double-probe resonant cavity, the upper pipeline 7, the lower pipeline 9 and the resonant cavity wall 8 are made of metal materials, the inner radius of the upper pipeline is 8-13 mm, and the thickness of the upper pipeline is 4-8 mm; the microwave transmitting probe 15 and the microwave receiving probe 16 are made of copper materials, the length is 3-5 mm, and the radius is 0.25-0.5 mm; the probe is arranged in the middle of the axial direction of the resonant cavity; the upper gear 11 and the lower gear 12 are made of metal materials, the thickness of the gears is 0.8-1.5 mm, and the number of the gears is 4-12; the height of the resonant cavity is 15 mm-25 mm.

In the single-probe resonant cavity, the upper pipeline 7, the lower pipeline 9 and the resonant cavity wall 8 are made of metal materials, the inner radius of the upper pipeline is 19-23 mm, and the thickness of the upper pipeline is 4-8 mm; the microwave transmitting probe 15 and the microwave receiving probe 16 are made of copper materials, the length is 3-5 mm, and the radius is 0.25-0.5 mm; the probe is arranged in the middle of the axial direction of the resonant cavity; the upper gear 11 and the lower gear 12 are made of metal materials, the thickness of the gears is 2-5 mm, and the number of gear teeth is 6-12; the height of the resonant cavity is 45 mm-55 mm.

The selection of materials of all parts is the best selection through experiments and simulation, and the larger the resolution of the oil resonant frequency f and the microwave output power value P, the better the resolution is, the water content of which is different as far as possible. Because the utility model discloses a measurement accuracy is high, and the microwave is strict to the processing requirement of device, so the processing of resonant cavity inner wall will be enough accurate, must smooth, and the gear surface also must be smooth, otherwise the experimental result has very big error. Taking 5 kinds of oil with different water contents as an example:

by HFSS simulation experiments, in the case of dual probes: when the inner radius of the resonant cavity is 10-11 mm, the wall thickness of the resonant cavity is 5-8 mm, and the thickness of the gear is 1-2 mm; in the case of a single probe: when the inner radius of the cavity is 19-22 mm, the wall thickness of the resonant cavity is 5-8 mm, and the thickness of the gear is 3-5 mm, the effect of separating the resonant frequencies is the best when different low-water-content oil liquids are measured (as shown in figure 7).

Example 2

The method for detecting the water content of the oil on line based on the microwave technology comprises the following specific implementation steps of a double-probe resonant cavity adopted by a microwave resonant unit 2:

when no oil is added (under the cavity), the corresponding resonant power f is obtained through the PC end _vac Resonant frequency f at this time _vac The range of (1) is 14-15 GHz; after the oil liquid is added, the range of the resonance frequency f obtained by the PC end is 9-10 GHz (in the frequency range, the resonance frequency f is most sensitive to the change of water in the oil liquid, and the resolution ratio of different water contents is better).

In order to measure the water content of the oil, different water-containing oil is respectively configured for experimental tests: sample 1 is oil with a water content of 0%; sample 2 is an oil with a water content of 0.05%; sample 3 is an oil with a water content of 0.1%; sample 4 is oil with a water content of 0.15%; sample 5 is oil with a water content of 0.2%; five samples are respectively injected into the resonant cavity, and the resonant frequency f of each sample can be respectively obtained at the PC end ₁ 、f ₂ 、f ₃ 、f ₄ 、f ₅ . And (4) calculating the water content of the oil liquid through the resonance frequencies of different water-containing oil liquids and through the steps (4), (5) and (6).

When the resonant cavity injects sample 1, f ₁ ＝9.47～9.48GHz，f _vac The dielectric constant of this sample was found to be 2.3 at 14.3 to 14.32GHz, and the water content of sample 1 was found to be 0.

When the resonant cavity injects sample 2, f ₂ The dielectric constant of this sample was 2.30317, which was determined to be 9.46 to 9.47GHz, and the water content of sample 1 was detected to be 0.05%.

Resonant cavity injectionSample 3, f ₃ The dielectric constant of this sample was 2.30635, which was determined to be 9.45 to 9.46GHz, and the water content of sample 1 was detected to be 0.1%.

When the resonant cavity injects sample 4, f ₄ The dielectric constant of this sample was 2.30953, which was determined to be 9.44 to 9.45GHz, and the water content of sample 1 was detected to be 0.15%.

When the resonant cavity injects sample 5, f ₅ The dielectric constant of this sample was 2.3127, which was determined to be 9.43 to 9.44GHz, and the water content of sample 1 was detected to be 0.2%.

When no oil is added (under the cavity), the corresponding output power P is obtained through the PC end _out Respectively injecting oil liquid of a sample 1, a sample 2, a sample 3, a sample 4 and a sample 5 into the sample cavity in sequence, and respectively obtaining the output power P of each water-containing resonant cavity at the PC end ₀ 、P ₁ 、P ₂ 、P ₃ 、P ₄ . And detecting the water content of the oil liquid according to the output power values of different water-containing oil liquids.

When the resonant cavity is injected into the sample 1, P ₀ And (3) obtaining the attenuation according to the output power of the resonant cavity, and detecting that the water content of the sample 1 is 0% according to a normalized curve of the attenuation and the water content when the attenuation is 16.86-16.91 dBm.

When the resonant cavity is injected into sample 2, P ₁ And (3) obtaining the attenuation according to the output power of the resonant cavity, and detecting that the water content of the sample 1 is 0.05% according to a normalized curve of the attenuation and the water content when the attenuation is 16.80-16.85 dBm.

When the resonant cavity injects sample 3, P ₂ And (5) obtaining the attenuation according to the output power of the resonant cavity, and detecting that the water content of the sample 1 is 0.1% according to a normalized curve of the attenuation and the water content, wherein the normalized curve is 16.74-16.79 dBm.

When the resonant cavity is injected into the sample 4, P ₃ And (4) obtaining the attenuation according to the output power of the resonant cavity, and detecting that the water content of the sample 1 is 0.15% according to a normalized curve of the attenuation and the water content, wherein the normalized curve is 16.68-16.73 dBm.

P when the resonant cavity injects sample 5 ₄ Obtaining attenuation according to the output power of the resonant cavity, obtaining a normalized curve of the attenuation and the water content, and detecting a sampleThe water content of 1 was 0.2%.

It should be noted that the foregoing is only a preferred embodiment of the present invention and the technical principles applied. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail with reference to the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the scope of the present invention.

Claims

1. The utility model provides an oil moisture content on-line measuring system based on microwave technique which characterized in that: the device comprises a microwave signal source (1), a microwave resonance unit (2) installed in an oil liquid conveying pipeline, an output signal processor (3), a parameter detection unit (4), a PC (personal computer) end (5) and a microwave transmission line (6); the microwave resonance unit (2) is respectively connected with a microwave signal source (1) and an output signal processor (3) through microwave transmission lines (6), the microwave signal source (1) and the output signal processor (3) are both connected to a parameter detection unit (4), and the parameter detection unit (4) is connected with a PC (personal computer) end (5);

the microwave resonance unit (2) comprises a resonance cavity wall (8), an upper pipeline (7) and a lower pipeline (9) which are fastened with the resonance cavity wall (8), a sample cavity (10) for containing detection oil, one or two probes arranged in the sample cavity (10), an upper gear (11) and a lower gear (12) which are arranged on the upper side and the lower side of the sample cavity (10), a microwave transmitting port (17) and a microwave receiving port (18); the resonant cavity wall (8) is tightly contacted with the sample cavity (10), and oil is injected into the sample cavity (10) through the upper pipeline (7) and is contacted with the resonant cavity wall (8); SMA adapter ports which penetrate through the resonant cavity wall (8) and are fixed in the resonant cavity are arranged at the microwave transmitting port (17) and the microwave receiving port (18); the probe is inserted into the inner side of the SMA adapter, and the outer side of the SMA adapter is respectively connected with the microwave transmission line (6);

the microwave signal source (1) is connected to the microwave transmitting port (17) through a microwave transmission line (6), a microwave signal is input into the resonant cavity through the probe, and when the input microwave wavelength is matched with the size of the resonant cavity, standing waves are formed in the cavity to generate a resonance phenomenon; the microwave signal is received by the probe and then is transmitted to the output signal processor (3) through the microwave transmission line (6) by the microwave receiving port (18).

2. The microwave technology-based oil water content online detection system according to claim 1, characterized in that: the upper pipeline (7) and the lower pipeline (9) are fastened with the resonant cavity wall (8) through four screw rods (20) and four nuts (19).

3. The microwave technology-based oil water content online detection system according to claim 1, characterized in that: the resonant cavity is an open cylindrical resonant cavity, two ends of the resonant cavity are composed of an upper gear (11) and a lower gear (12), and the resonant cavity wall (8) is in close contact with the upper pipeline (7) and the lower pipeline (9) through the upper gear (11) and the lower gear (12) to form a whole.

4. The microwave technology-based oil water content online detection system according to claim 1, characterized in that: the SMA adapter does not completely penetrate through the wall (8) of the resonant cavity, and the distance from the inner side of the SMA adapter to the sample cavity (10) is 0.1-0.8 mm.

5. The microwave technology-based oil water content online detection system according to claim 1, characterized in that: the two probes are respectively provided with a microwave transmitting probe (15) and a microwave receiving probe (16) which are not directly contacted with the resonant cavity wall (8), an interval is reserved between the probes and the resonant cavity wall (8), and the microwave transmitting probe (15) and the microwave receiving probe (16) are respectively spliced with the left side SMA adapter port (13) and the right side SMA adapter port (14).

6. The microwave technology-based oil water content online detection system according to claim 4, characterized in that: the microwave signal source (1) is a microwave voltage-controlled oscillator, the output signal processor (3) is a power converter, and the parameter detection unit (4) is a voltage detection unit.

7. The microwave technology-based oil water content online detection system according to claim 1, characterized in that: the probe is one, and the single probe transmits and receives microwave signals.

8. The microwave technology-based oil water content online detection system according to claim 7, characterized in that: the microwave signal source (1) is replaced by a broadband microwave source; simultaneously inputting part of the transmitted signals into a receiver, and detecting input signals; the output signal processor (3) is replaced by an output signal collecting unit consisting of a power divider and a directional coupler; the parameter detection unit (4) is replaced by a receiver to realize the detection of the incident signal and the reflected signal.