SU1322140A1 - Acoustical method of determining concentration of nitrogen dioxide in gases - Google Patents

Abstract

The invention relates to methods for analyzing gases using ultrasonic vibrations (UT) and can be used in determining the concentration of nitrogen dioxide in flue and flue gases. The purpose of the invention is to increase the accuracy and reduce the time to determine the concentration. With increasing pressure of the analyzed gas (AG), the size of the solid component (nitrogen dioxide) on the vibrator 6 per unit of time increases, which leads to an instantaneous deposition of coagulated particles and a decrease in the duration of the test. The AG is compressed in compressor 3, enters the test chamber 4, where compression is stopped and the ultrasonic signal is passed from the emitter 7. Thereafter, the AG is heated to the evaporation temperature of the nitrogen dioxide and the oscillation period of the vibrator is measured. The emitter 7 ultrasonic testing works up to 90-95% coagulation of nitrogen dioxide. 1 il. W (L

Description

The invention relates to methods for analyzing gases using ultrasonic vibrations and can be used to determine nitrogen dioxide in flue and flue gases.

The purpose of the invention is to improve the accuracy and reduce the time to determine the concentration by increasing the efficiency of the solid phase of nitrogen dioxide.

The drawing shows the block diagram of the device that implements the proposed method.

The device contains a filter 1 of mechanical impurities, a desiccant 2 moisture, a compressor 3, a test chamber 4, a refrigerating chamber 5, a vibrator 6, a radiator 7 of ultrasonic vibrations (UT), a control unit 8, a vacuum pump 9 (forvacuum) an oscillation meter 10, a heater 11, the generator 12 ultrasonic vibrations.

The method is carried out as follows.

The analyzed gas is pre-cleaned with filter 1 and dried with desiccant 2, then compressed in compressor 3 Compressed gas enters the test chamber 4 placed in the refrigerator 5, The vibrator 6 and the ultrasonic transmitter 7 are placed in the test chamber 4 When the specified pressure value is reached In the test chamber 4, the command of the control unit 8 controls the compression of the gas and switches on the emitter 7 of the ultrasonic vibrations connected to the generator 12. The emitter runs for a predetermined time interval and th turned off by a command from the control block B, and then the vacuum pump 9 is switched off the test gas from the chamber 4 and on reaching the predetermined discharge voltage values is carried out measuring the period of oscillation of the vibrator 6 meter 10 period.

After the measurement of the period, the control unit 8 issues a command to heat the vibrator 6 by the heater 11 to a temperature above the evaporation temperature of the nitrogen dioxide. The evaporating nitrogen dioxide is then pumped out. At the command of the control unit 8, the heater 11 and the vacuum pump 9 are turned off and the device is ready for the next analysis.

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The possibility of increasing accuracy and reducing (reducing) the duration of determining the concentration is based on the fact that the rate of adsorption increases with increasing pressure according to Henry's law. Therefore, as the pressure of the test gas in the test chamber increases, the solid component of nitrogen dioxide on the vibrator 6 is thus increased, per unit time. In addition, aerosol mixtures of liquids in the gas phase when exposed to ultrasonic vibrations noticeably coagulate and instantly precipitate (precipitate). The coagulation efficiency depends on the pressure (concentration), and increases with pressure. Thus, increasing the pressure in the test chamber 4 leads to a reduction in the duration and an increase in the measurement accuracy. The test time is determined by the time required to establish the pressure (ten seconds) and the time of action of the ultrasonic vibrations for (10–20 s).

The creation of a discharge in the test chamber eliminates the error in determining the resonant vibration frequency of the vibrator 6, since the vibrator 6 becomes unloaded.

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The gas pressure in chamber 4 (both compression and fracture) is predetermined on the basis of experimental data; this pressure value must ensure the specified accuracy of measurement. The operating time of the transmitter 7 UTD is also determined experimentally. In practice, the emitter 7 should work until it coagulates 90-95% nitrogen dioxide; The experimentally determined time interval is 10–20 s.

Thus, the method makes it possible to shorten the measurement time several times and to improve the accuracy of measuring the concentration of nitrogen dioxide.

Claims (1)

Invention Formula An acoustic method for determining the concentration of nitrogen dioxide in gases, which consists in placing a vibrator in the test chamber with previously dried, purified from mechanical impurities, and analyzing the gas to be analyzed. 313221404 Cooling the analyzed gas of undercutting and shortening the time of freeze-up of the dioxide of nitrogen-dividing concentration, before measuring, measure the period of oscillation by the vibration of the period of oscillation of the vibrator rator and by changing the period of its analyzed gas is compressed, the excitation of vibrations determines the concentration of 5 ultrasonic vibrations, nitrogen dioxide, which is distinguished and then created in the test box by the fact that, in order to increase the degree of discharge.