WO2004003529A1

WO2004003529A1 - The device for measurement of humidity in nonmetallic mediums

Info

Publication number: WO2004003529A1
Application number: PCT/RU2003/000282
Authority: WO
Inventors: Oleg Dmitrievich Zvyagin; Alexander Anatolyevich Vasilyev; Mikhail Germanovich Gapochka; Grigory Alekseevich Ivanchenko; Vitaly Evgenyevich Konstantinov; Anatoly Fedorovich Korolev; Nikolai Evgenyevich Syroedov; Anatoly Ivanovich Raev
Original assignee: Oleg Dmitrievich Zvyagin; Vasilyev Alexander Anatolyevic; Mikhail Germanovich Gapochka; Grigory Alekseevich Ivanchenko; Konstantinov Vitaly Evgenyevic; Anatoly Fedorovich Korolev; Nikolai Evgenyevich Syroedov; Anatoly Ivanovich Raev
Priority date: 2002-06-28
Filing date: 2003-06-27
Publication date: 2004-01-08
Also published as: AU2003253529A1; RU2207549C1

Abstract

The present invention relates to measurement technologies and can be used for determination of humidity in gaseous, liquid or solid nonmetallic media. According to the principles of the invention, the measured mediums sample is contained in a cell, the receiver and generator heads are combined in a single module located at the norm throat of the transmitter-receiver antenna at the focal plane of the reflecting profiled surfaces of the walls of the cell, which has a transparent wall conjugated with the horn opening, is made of a material reflecting millimeter-range wavelengths and provided with orifices for filling in and discharging of measured and reference media and a movable shutter to produce a flow-through section with a regenerable filter made of space-globular structure sorbent polymer at its starting.

Description

The device for measurement of humidity in nonmetallic mediums

Technical Field The present invention relates to measurement technologies and can be used for determination of humidity in gaseous, liquid or solid nonmetallic media required in food, automotive, aircraft, power, and other various industries.

Background Art A known device for measurement of humidity [1] comprises generator and receiver heads, a transmitting antenna, a cell containing the measured mediums, and an auxiliary receiver set at a definite angle with respect to the flux in order to produce a signal phase shift. In this case, however, measurement accuracy and sensitivity are affected by the alignment inaccuracy of both primary and auxiliary receivers, as their mechanical positioning changes the conditions of signal transportation within the measuring section of the device. It alters both the phase and the amplitude of the useful signal and, consequently, deteriorates the measurement accuracy and sensitivity. Another known device for measurement of humidity [2] comprises two transmitting radiators, a receiver head, and a coupler used to transport the fluxes of electromagnetic radiation to a cell comprising several specifically sized sections of different thickness. Humidity is then evaluated by the intensity of the integral flux. In this case, however, measurement accuracy and sensitivity are affected by the alignment inaccuracy of the two transmitting radiators, the coupler and the receiver head.

Another known device for measurement of humidity [3] comprises generator and receiver heads, a transmitter-receiver antenna with a horn, a cell containing the measured mediums, a low-frequency acoustic vibrator to modulate the reflected signal, and a mechanism for antenna displacement along the direction of wave propagation in order to change the signal phase. The disadvantage of this system is the spatial separation of the acoustic radiation source and the antenna displacement mechanism, which results in an imprecise co-ordination of these elements, producing additional inaccuracies of measurement and deteriorating the measurement resolution. Besides, the propagation of the signal 1 through the cell walls causes a partial loss of information, producing additional noise and also contributing to the decrease of measurement sensitivity and precision. Another known device for measurement of humidity [4], taken as the closest analogue to the present invention, comprises generator and receiver heads, a power supply unit, a transmitter-receiver antenna with a horn in contact with the measured mediums, a waveguide circulator, a waveguide transformer, two untying slimline isolators, and series- connected amplifier and detector units. Measurement precision and sensitivity of this system is, however, affected by the strong dependency on the type of the measured mediums at the zero point of the twin bridge, as the signals reflected from the mediums surface and its volume add up. Reflected microwave signals only allow to measure high humidity levels in the measured mediums. The mechanical adjustment of the waveguide transformer seriously deteriorates the measuring system precision and sensitivity. Besides, the non-rigid connection between the horn and the measured mediums does not allow to produce a stable reflected signal. The object of the present invention is to improve the measurement precision and sensitivity. Disclosure of Invention

This object is achieved in a device for measurement of humidity in nonmetallic media comprising generator and receiver heads connected to a power supply unit, a transmitter-receiver antenna with a horn in contact with the measured mediums sample, series-connected amplifier and detector units, wherein, according to the formula of the present invention, the measured mediums sample is contained in a cell, the receiver and generator heads are combined into a single module located at the horn throat of the transmitter-receiver antenna at the focal plane of the reflecting profiled surfaces of the walls of the cell, which has a transparent wall conjugated with the horn opening, is made of a material reflecting millimeter-range wavelengths and provided with orifices for filling in and discharging of measured and reference media and a movable shutter to form a flow-through section with a regenerable filter made of space-globular structure sorbent polymer at its starting. A device is proposed wherein the measured mediums sample is contained in a cell, while the generator and receiver heads are combined into a single module located at the horn throat of the transmitter-receiver antenna at the focal plane of the reflecting profiled surfaces of the walls of the cell, which has a transparent wall conjugated with the horn opening, is made of a material reflecting millimeter-range wavelengths and provided with filling and discharging orifices and a movable shutter to form a flow-through section with a regenerable sorbent filter at its starting.

This layout minimizes signal losses within the measurement volume of the cell due to the heads arrangement, cell walls profiling and the choice of the material, as well as to the rigid connection between the heads, the antenna horn and the cell, which allows, in the millimeter wavelength range, to reduce the measurement inaccuracy, both systematical and random, and to improve the signal/noise ratio, thus perfecting the measurement precision and sensitivity. The formation of the flow-through volume at high humidity levels using a non-transparent movable shutter eliminates the influence of the noise emerging from the rest of the volume on the useful signal. At the same time, the use of a sorbent filter allows a terminal drying of reference samples of the measured mediums to calibrate the measuring system, which improves the reliability of measurements and, therefore, enhances their precision and sensitivity.

Brief Drawings Description

Fig. 1 represents the layout of the device for measurement of humidity in nonmetallic media.

Detailed Drawings Description

The device comprises generator (1) and receiver (2) heads connected with a power supply unit (3), a transmitter-receiver antenna with a horn (4) in contact with a measured mediums sample (5), series-connected amplifier

(6) and detector (7) units. The measured mediums sample (5) is placed in a cell (8), and the generator (1) and receiver (2) heads are combined into a single module located in the throat of the horn (4) of the transmitter- receiver antenna at the focal plane of the reflecting profiled walls of the cell (8). The cell (8) with a transparent wall (9) conjugated with the opening of the horn (4) is made of a material reflecting the millimeter range wavelengths and provided with orifices (10,11) for filling in and discharging of measured and reference media and a movable shutter (12) to form a flow-through section (13) with a regenerable filter (14) made of a space-globular structure sorbent polymer at its starting. The detector unit (7) is series-connected to an analog-to-digital converter (15), a control unit (16) back-coupled with the power supply unit (3), an indicator unit (17) and a keyboard (18) allowing to select the measurement range, scale and dimension of measured values with an output connected to the control unit (16), which is back-coupled with the amplifier unit (6) and the detector unit (7).

The Best Mode for Carrying Out the Invention

The vacuumized cell (8) is filled with a pre-dried reference sample of the measured mediums through the opened orifice (11) and the filter (14) with the movable shutter (12) open. The terminal drying of the sample takes place in the cell (8). After the cell (8) is filled, it is sealed hermetically. To minimize the losses due to reflection from the transparent wall (9) and to improve the measurement precision and sensibility, an adjustment of the signal in the transmitter-receiver system according to the physical properties of the mediums is carried out during the calibration. It can be done either by special processing of the received signal in the control unit (16) or by adjustment of the high-frequency signal parameters in the power supply unit (3). When the cell (8) is fed with the measured mediums, the regenerable filter (14) is not used. During the calibration and measurements, the high- frequency millimeter wavelength range signal produced by the generator head (1) and modulated with a low-frequency signal produced by the power supply unit (3) according to the parameters specified by the control unit (16) is transported to the cell (8) with the measured or reference sample via the horn (4) conjugated with the transparent cell wall (9). The walls of the cell (8) do not cause any loss of the measurement information. The signal is reflected from the profiled inner surfaces of these walls and transported further to the receiver head (2) combined in a single unit with the generator head (1), and then to the amplifier (6) allowing to improve the signal/noise ratio. The detector unit (7) extracts the low-frequency component of the signal, to be further transported to the analog-to-digital converter (15). The signal represented as a digital code is then processed in the control unit (16) according to the operator-specified algorithm. Final results are output to the indicator unit (17). The generator (1) and receiver (2) heads are located at the focal plane of the reflecting profiled surfaces of the walls of the cell (8). Frequency wobbling or phase modulation of the waves according to the program specified by the control unit (16) cause the measurement to be repeated, which allows to achieve higher reliability of measurements in case of application of dynamic forces and vibrations. In this case, the amplitude and phase of the wave propagating through the mediums under investigation inside the cell (8) are measured. To determine the humidity in media with high water content, the amplitude of the electromagnetic wave reflected from the mediums surface adjacent to the transparent wall of the cell (8) is measured. This is achieved by separating the flow-through section of the cell (8) with the movable shutter (12), opening the orifices (10) and (11), and feeding the mediums from the main pipe, by-passing the filter (14). In this case, measurements can be carried out on a moving mediums, e.g. while filling reservoirs.

Industrial Applicability

The industrial applicability of the device is affirmed experimentally/ Thus, the use of the proposed device allows to improve the precision and sensitivity of measurements due to the exclusion of moving mechanical adjustment elements, as well as to the use of the maximum informative part of the signal and minimization of losses during both calibration and measurements.

Sequence Listing

1. SU > 271104, G 01 N 22/04, 1970.

2. SU tto 671913, G 01 N 22/04, 1979.

3. SU JN 216368, G 01 N 22/04, 1968. 4. RU JN^O 2132051, G 01 N 22/04, 1999.

Claims

A device for measurement of humidity in nonmetallic media comprising generator and receiver heads connected with a power supply unit, a transmitter-receiver antenna with a horn in contact with the measured mediums sample, series-connected amplifier and detector units, wherein the measured mediums sample is contained in a cell, the receiver and generator heads are combined into a single module located at the horn throat of the transmitter-receiver antenna at the focal plane of the reflecting profiled surfaces of the walls of the cell, which has a transparent wall conjugated with the horn opening, is made of a material reflecting millimeter-range wavelengths and provided with orifices for filling in and discharging of measured and reference media and a movable shutter to form a flow-through section with a regenerable filter made of space-globular structure sorbent polymer at its starting.