RU2244293C2 - Microwave method for evaluating liquid media moisture content and salinity - Google Patents

Abstract

FIELD: petrochemistry and laboratories such as those for measuring moisture percentage and salinity influencing engine efficiency and breakdown voltage of transformer oil.

SUBSTANCE: analyzed specimen in the form of small-diameter rod is placed in first cylindrical resonance cavity and E ₀₁₀ or E ₀₁₁ electromagnetic field is excited to determine low or high values of moisture volume concentration, respectively. Working Q of first cylindrical resonance cavity that serves as measure of moisture volume concentration in liquid medium being analyzed is measured; then analyzed specimen in the form of small-diameter cylindrical rod is placed in second cylindrical resonance cavity, E ₀₁₀ or E ₀₁₁ electromagnetic field is excited to determine low or high values of moisture volume concentration, respectively, and working Q of second cylindrical cavity is measured at frequency ensuring that loss due to rotational relaxation of water polar molecules is comparable with that due to salinity. In this case working Q of second cylindrical resonance cavity serves as moisture salinity measure and frequency of first cylindrical resonance cavity is chosen to ensure that loss due to rotational relaxation of polar water molecules in microwave region is much higher than that due to salinity. Device used to evaluate moisture content and its salinity in liquid media has cylindrical resonance cavity with pipeline carrying analyzed liquid disposed on its axis, tunable microwave oscillator, and Q meter. Output of tunable microwave oscillator is connected to exciting loop, input of Q meter, to receiving loop of cylindrical cavity, and control output of Q meter, to control input of tunable microwave oscillator. It also has second cylindrical resonance cavity filled with low-loss dielectric that incorporates pipeline carrying analyzed liquid disposed on its axis. Diameters and axes of cylindrical cavities are aligned. Newly introduced are second tunable microwave oscillator and second Q meter; output of second tunable microwave oscillator is connected to exciting loop, input of second Q meter, to receiving loop of second cylindrical cavity, and control output of Q meter, to control input of second tunable microwave oscillator.

EFFECT: ability of determining liquid media salinity along with its moisture content.

2 cl, 1 dwg

Description

The present invention relates to methods for determining the moisture and salinity of liquid media. It can find application, in particular, in the petrochemical industry.

The known conductometric method for determining humidity (see Zhukov Yu.P., Kulakov MV High-frequency electrodeless conductometry -M .: Energy 1968. P.104). The measurement of volumetric humidity by this method is limited to the area from 2% to 30%. In the humidity range of 0-2%, measurement is almost impossible, since the values of the resistances of the materials become greater than the input resistances of the measuring devices. Another disadvantage is the influence on the measurement result of the inconstancy of the electrical conductivity of the moisture itself.

A known resonator method for determining the volumetric concentration of moisture (see Berliner MA, Moisture Measurement -M .: Energy 1973), adopted as a prototype. The test sample in the form of a cylindrical rod of small diameter is placed in the cavity of a volume resonator (OR), an electromagnetic field (EMF) of a certain spatial structure is excited: vibration type E _{010 is} used to determine small values of volumetric moisture concentration; H ₀₁₁ type vibration allows one to study samples with a large volume concentration of moisture. The output value of the primary measuring transducer (PIP) is the change in the quality factor of the resonator ΔQ = QQ ₀ (Q-loaded; Q _{0 -} unloaded Q factor of the OP caused by the introduction of the material under study). The disadvantage of the prototype is the inability to determine the salinity of the moisture.

The present invention is aimed at expanding the functionality.

This technical result is achieved by the fact that the microwave method for determining the moisture content and the degree of salinity in liquid media, in which the test sample in the form of a cylindrical rod of small diameter is placed in the cavity of the first cylindrical volume resonator, excites an electromagnetic field of type E ₀₁₀ in the case of determining small values bulk moisture concentration ₀₁₁ or H in the case definition of high bulk moisture concentration values measured loaded Q of the first cylindrical cavity resonator, vlyayuschuyusya measure volumetric moisture concentration in the test liquid medium, then the test sample in the form of a cylindrical rod of small diameter placed in the cavity of the second cylindrical cavity resonator is excited electromagnetic field of type E ₀₁₀ in case the determination of small values of volume of moisture concentration or H ₀₁₁ in the case of determining large values of bulk moisture concentration, measure the loaded Q factor of the second cylindrical volume resonator at such a frequency that losses caused by rotational relaxation polar water molecules are commensurate with losses due to salinity, while the loaded Q factor of the second cylindrical volume resonator is a measure of moisture salinity, and the frequency of the first cylindrical volume resonator is chosen such that the losses caused by rotational relaxation of polar water molecules in the microwave region are much larger than the losses due to salinity.

A device for determining the moisture content and the degree of its salinity in liquid media, containing a cylindrical volume resonator, on the axis of which there is a pipeline with the studied liquid, a frequency-tunable microwave generator, a quality factor meter, while the output of a frequency-tunable microwave generator is connected to the exciting loop, input Q-meter - with the receiving loop of a cylindrical volume resonator, and the control output of the Q-meter - with the control input of a frequency-tunable gene the microwave radiator, additionally includes a second cylindrical volume resonator filled with a low-loss dielectric, on the axis of which there is a pipeline with the studied liquid, the diameters and axes of the cylindrical volume resonators being the same, the second frequency-tunable microwave generator, the second quality meter, and the output of the second tunable the frequency of the microwave generator is connected to the exciting loop, the input of the second Q-meter is connected to the receiving loop of the second cylindrical volume resonator, and the control output of the second Q-meter - with the control input of the second microwave frequency-tunable generator.

The drawing shows a device for implementing the proposed method.

c целью сравнения с γ₀ См/м за счет засоленности.The essence of the proposed method is as follows. The studied sample of strict shape and size (for example, in the form of a pipe axially located in the center 1) is placed in the cavity 1, at an frequency f ₁ an electromagnetic field of a certain spatial structure is excited, for example, E ₀₁₀ or H _{011 of a} cylindrical volume resonator. The loaded Q factor of QOR Q _{1 is} measured. The frequency f ₁ is chosen such that the losses caused by the rotational relaxation of polar water molecules in the microwave region are much larger than the losses due to salinity (ohmic losses due to the conduction current, i.e., γ ₀ S / m). In King R., Smith G. Antennas in material environments in two books. Book 1. -M .: World. 1984. Page 396 provides reference values of the real ε'and imaginary ε "parts of the dielectric constant of water at different frequencies and at different temperatures. The table shows the conversion of the imaginary part ε" of the dielectric constant of water into equivalent or effective conductivity:

for the purpose of comparison with γ ₀ S / m due to salinity.

См/м)Specific equivalent or effective conductivity of water due to rotational relaxation of polar molecules (

Cm / m)

Table No. 1 t, ° C f ₁ = 23.6 GHz f ₂ = 9.35 GHz f ₃ = 3GHz 0 36.21 cm / m 21.5 cm / m 4.13 cm / m 10 42 19.6 2.97 twenty 45.47 16.63 2.19 thirty 46.45 13.51 1.6 40 43.95 eleven 1.25 fifty 39.89 8.79 0.97 60 35.29 7.1 0.8 70 28.86 5.35 0.57

In the same source, on page 399, reference data is given for the specific conductivity of water γ ₀ in direct current versus the degree of salinity, for example, for t = 20 ° C (see table No. 2).

Direct current specific conductivity of sea water (γ ₀ , S / m) at t = 20 ° C from salinity

может быть выражена (см. Кинг Р., Смит Г. Антенны в материальных средах в двух книгах. Книга 1. -М.: Мир. 1984. Стр.398, формула (10.1)):As is known, the total conductivity of water

can be expressed (see King R., Smith G. Antennas in material media in two books. Book 1. — M.: Mir. 1984. P.398, formula (10.1)):

where γ ₀ is the direct current conductivity of water;

- удельная проводимость воды за счет вращательной релаксации полярных молекул.

- specific conductivity of water due to rotational relaxation of polar molecules.

=45.47 См/м >>γ₀=3.57 См/м (см. таблицы №1 и №2). Тогда нагруженная добротность ОР1 Q_l выражается в виде:The frequency f ₁ can be chosen equal to f ₁ = 23.6 GHz. For t = 20 ° C:

= 45.47 S / m >> γ ₀ = 3.57 S / m (see tables No. 1 and No. 2). Then the loaded figure of merit OP1 Q _l is expressed as:

,

,

where W _app1 is the stored energy of the electric field in OP1 with a certain spatial structure at the resonant frequency f ₁ ; P _sweat1 - power loss in the walls of the SOR1, the input-output energy and in the test sample.

f ₁ and W _app1 can be considered unchanged due to the small value of concentration with _v moisture, if the vibration E _{010 is} excited; upon excitation of the oscillations H ₀₁₁ f ₁ and W _app1 can also be considered unchanged due to the small value of the electric field near the axis of the center.

>>γ₀:R _pot1 without taking into account losses on input-output of energy and in the walls of TSOR1 and provided

>> γ ₀ :

(cν) - объем (объемная концентрация) влаги;

(cν) is the volume (volume concentration) of moisture;

V - исследуемый объем; E₁ - значение напряженности электрического поля в исследуемом объеме.

V is the test volume; E ₁ - the value of the electric field in the test volume.

As can be seen from (2), P _pot1 , and with it Q _1, depend on the volumetric moisture concentration c _v and does not depend on salinity γ ₀ . Therefore, the loaded Q factor Q ₁ at a frequency of f ₁ is a measure of volume concentration with _v moisture.

Then, at a frequency f _2, DOR2 with a certain spatial structure is introduced into resonance. The loaded Q factor Q _{2 is} measured. The frequency f ₂ is chosen such that the losses caused by the rotational relaxation of the polar water molecules are commensurate with the losses due to salinity. Such a frequency can be selected, for example, the frequency f ₂ = 3 GHz (see table No. 1 and No. 2). In this case, the loaded Q factor Q ₂ has the form:

where W _app2 is the stored energy of the electric field in OP2 with a certain spatial structure at the resonant frequency f ₂ ; P _sweat2 - power loss in the walls of the center 2, the input-output energy and in the sample.

R _pot2 - without taking into account losses on input-output of energy and in the walls of TSOR2:

where E ₂ - the value of the electric field in the test volume.

As can be seen from (3), P _pot2 - and with it Q ₂ depend on the volumetric moisture concentration c _v and on salinity γ ₀ . Therefore, the loaded Q factor Q ₂ at the frequency f ₂ is a measure of the volumetric moisture concentration c _v . T.O. Q ₁ is a measure of concentration (c _v ), and Q ₂ is the salinity of moisture.

To measure small values of moisture concentrations, it is preferable to use the E ₀₁₁ oscillation (the electric field of this oscillation is concentrated near the center of the center), to measure large values of concentration - H ₀₁₁ (the electric field of this oscillation on the axis is small). The interest in the vibrations of E ₀₁₀ and H _{011 is} due to the fact that the boundary conditions for the electric field lines are simple, since they (power lines) are parallel or perpendicular to the interface between two media: air - the medium under investigation (a pipe located axially). Of all the types of lower vibrations in the center, only vibrations E ₀₁₀ and H ₀₁₁ possess axial symmetry of the electromagnetic field. For example, the electric power lines of the oscillation E ₀₁₀ begin on one and end on the other end wall, that is, they are parallel to the pipeline, and for the oscillation H _{011, they} are tangent to the volume of the sample, since they are closed concentric circles.

A device for implementing the proposed method consists of a pipeline 1 with a test fluid, a first cylindrical volume resonator (COR1) 2, a second cylindrical volume resonator (COR2) 3, the first frequency-tunable microwave generator 4, the first Q-factor meter 5, and the second frequency-tunable microwave generator 6, the second Q-factor meter 7, the excitation loop 8 of COR1, the receiving loop 9 of COR1, the exciting loop 10 of COR2, the receiving loop of 11 COR2. COR 2 3 is filled with dielectric 12 with low losses.

The device operates as follows.

The test liquid, with an unknown concentration of moisture and the degree of its salinity, flows through the pipeline. The pipeline is located on the axis TsOR1 2 and TsOR2 3. For the convenience of the technological design, the diameters of TsOR1 2 and TsOR2 3 are made the same. The oscillations of the frequency-tunable first microwave generator 4 are fed to the exciting loop 8. The first quality factor 5 controls the frequency of the first frequency-tunable microwave generator 4. When the frequency of the first frequency-tunable microwave generator matches the resonant oscillation frequency E ₀₁₀ (or Н ₀₁₁ ) ЦОР1 2 by means of the excitation loop 8, the oscillation E ₀₁₀ (or H ₀₁₁ ) is excited in DSC1 2. Oscillations of the microwave through the receiving loop 9 are fed to the first Q-meter 5. The first Q-meter 5 measures one of the known methods (for example, by the bandwidth of the oscillating system) the loaded Q-factor Q ₁ . The frequency range of the first tunable microwave generator is chosen such that the losses caused by the rotational relaxation of polar water molecules in the microwave region are much larger than the losses due to salinity (ohmic losses due to the conduction current). T.O. loaded Q factor Q ₁ is a measure of moisture concentration.

In a similar manner, the loaded Q factor Q _{2 of} COR2 is measured. 3. The frequency range of the second tunable microwave 6 generator is selected such that the losses caused by rotational relaxation of the polar water molecules are commensurate with the losses due to salinity. To reduce the resonant frequency of oscillations E ₀₁₀ (or H ₀₁₁ ) COR2 3 is filled with a dielectric. 12. T.O. loaded Q factor Q ₂ is a measure of moisture salinity. To measure small values of moisture concentrations, it is preferable to use the E ₀₁₁ oscillation (the electric field of this oscillation is concentrated near the center of the center), to measure large concentrations of moisture - H ₀₁₁ (the electric field of this oscillation is small on the axis).

The present invention can find application in laboratory practice, since, for example, the percentage and salinity of moisture in fuel and lubricants affects the efficiency of the engine, in transformer oil, these factors affect the breakdown voltage, etc.

Claims (2)

1. The microwave method for determining the moisture content and the degree of salinity in liquid media, which consists in the fact that the test sample in the form of a cylindrical rod of small diameter is placed in the cavity of the first cylindrical volume resonator, an electromagnetic field of type E ₀₁₀ is excited if small values of volume concentration are determined moisture or H ₀₁₁ in the case of determining large values of volumetric moisture concentration, measure the loaded figure of merit of the first cylindrical volumetric resonator, which is a measure of the volumetric concentration moisture in the studied liquid medium, characterized in that the test sample in the form of a cylindrical rod of small diameter is placed in the cavity of the second cylindrical volume resonator, an electromagnetic field of type E ₀₁₀ is excited in the case of determining small values of the volumetric moisture concentration or H ₀₁₁ in the case of determining large values of volumetric moisture concentration, measure the loaded Q factor of the second cylindrical volume resonator at such a frequency that losses caused by rotational relaxation of polar molecules water, commensurate with losses due to salinity, while the loaded figure of merit of the second cylindrical volume resonator is a measure of moisture salinity, and the frequency of the first cylindrical volume resonator is chosen such that the losses caused by rotational relaxation of polar water molecules in the microwave region are much larger than the losses due to salinity account. 2. A device for determining the moisture content and the degree of salinity in liquid media, containing a cylindrical volume resonator, on the axis of which there is a pipeline with a test liquid, a frequency-tunable microwave generator, a quality factor meter, while the output of a frequency-tunable microwave generator is connected to an exciting loop , the input of the quality factor meter - with the receiving loop of the cylindrical volume resonator, and the control output of the quality factor meter - with the control input of the frequency-tunable Microwave generator, characterized in that it additionally includes a second cylindrical volume resonator filled with a low-loss dielectric, on the axis of which there is a pipeline with the liquid under investigation, the diameters and axes of the cylindrical volume resonators being the same, as well as a second frequency-tunable microwave generator, and a second Q factor meter while the output of the second frequency-tunable microwave generator is connected to the exciting loop, the input of the second Q-meter is connected to the receiving loop of the second cylinder volume resonator, and the control output of the second Q-meter with the control input of the second microwave frequency-tunable generator.