SU1749807A1 - Conductometrical analyzer of air admixture content - Google Patents

Abstract

The invention relates to medical technology. The essence of the invention: a conductometric analyzer of the content of impurities in the air contains two flow conductometric cells included in the shoulders of the AC bridge. The entrance of one cell is connected by cooled capillaries to a steam generator, a gas pump, and a gas preheater. The output of both cells is connected via ion-exchange filters by a steam generator. The vapor passing through the capillaries condenses into them. The analyzed air is in contact with steam in one of the capillaries; air impurities saturate the condensate. The difference in electrical conductivity of the condensate in the cells determines the concentration of impurities in the air. Condensate from the cells is returned to the steam generator, which allows the system to operate in a closed loop. 1 il. WITH

Description

The invention relates to medical technology, and more specifically to devices for determining the degree of contamination of air inhaled by a person.

KU-1 conductometric gas analyzers for determining carbon monoxide CO in air, having an oxidation device from CO to CO2, followed by absorption of CO2 by alkali and measuring the conductivity of the resulting solution are known. The amount of CO in the air is judged by the magnitude of the electrical conductivity of an alkali that reacted with C02.

The disadvantage of these devices is the need for frequent replacement of solutions.

alkali reacted with C02. The devices are designed to determine CO in individual air samples. The possibility of long-term continuous operation of the device is excluded, which prevents continuous monitoring of the CO content in the air.

Conductometric gas analyzers are known for determining the Vesthoff company CO, the measurements of which are based on an automatic AC bridge with two K-conductometric cells. In the gas analyzer, CO is acidified to CO2 and reacted with COa of the NaOH solution.

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The disadvantages of the device include the need to replace the reacted NaOH solution and remove the iodine resulting from the oxidation of CO to C02 with iodine anhydride.

Closest to the invention is a conductometric gas analyzer consisting of a differential electrolytic converter and a bridge measuring circuit. There are two conductometric cells in the shoulders of the AC bridge. The first cell measures the electrical conductivity of the pure absorption solution, and the second, the electrical conductivity of the absorption solution that has reacted with the gas component detected. The unreacted part of the gas and the reacted solution are removed from the installation.

The disadvantage of these gas analyzers is the need to prepare and frequently replace the absorption solutions, to replace the absorption solution during the transition to determining the concentration of a new component in the gas. Periodic flushing of the flow part of the analyzers is also necessary in order to eliminate salt deposits. All this makes it impossible for long-term operation of gas analyzers with preservation of measurement accuracy.

The purpose of the invention is to improve the measurement accuracy, reducing operating costs.

The drawing shows a diagram of the analyzer.

The analyzer consists of a housing 1 with a lid 2 in which flow-through conductometric cells 3 and 4 are placed. The input of cell 3 is connected by a capillary 5 to a steam generator 6. The input of a cell 4 is connected by a capillary 7 to a steam generator 6 and a capillary 8 with a heater 9 of the analyzed gas and pump 10. The output of cells 3 and 4 is connected via ion-exchange filters 11 (anion exchanger and cation exchanger) to the steam generator 6. The steam generator 6 consists of a body 12, partially filled with water, an electric heater 13 with a regulator of 14 voltage, a drop of boilers 15, a steam intake pipe 16, and a drain t felling 17, feed tube 18, level gauge 19 and steam superheater 20.

The housing 1 of the analyzer is equipped with a cooler 21 consisting of semiconductor thermocouples connected to a power source through an automatic voltage regulator 22 tuned to a specific temperature using a mercury electrocontact thermometer 23.

The steam generator b and the body 1 of the analyzer are covered with a layer of thermal insulation 24.

Valves 25 - 33 are installed in the analyzer to adjust the flow rate of the liquid, steam, and the gas to be analyzed.

Gas from cell 4 enters the atmosphere at

capillary 34.

The analyzer works as follows.

The steam generator is filled with desalinated water through the valve 33 and the tube 17.

0 The water level is controlled by the level gauge 19. The voltage regulator 14 and the valve 25 are used to set the required steam flow rate through the capillaries 5 and 7. The steam condensation in the steam line through

The 5 paths to the capillaries 5 and 7 are prevented by overheating the steam in the superheater 20. The vapor entering the capillaries 5 and 7 is cooled in them to 1-5 ° C and condenses into liquid. Stabilization of the temperature of the capillaries 5 and 7 is provided

0 by the system of automatic control of the temperature of the housing 1 of the analyzer, in which the capillaries are 5,7,8 and 34. The required temperature of the housing 1 is set at the electric contact temperature of 23 m. on the electric refrigerator 21, which cools the housing 1. When the temperature of the cabinet 1 reaches the required temperature, the electric refrigerator 21 automatically switches off at a signal from the thermometer 23.

Condensate vapor from the capillary 5 enters the cell 3, fills it and flows through

5 capillaries and ion exchange filters 11 to the steam generator.

During the condensation process, gas (air ;, containing a controlled component,

0 coming into the capillary 7 from the capillary 8 from the air pump 10. The adjustment of the air flow is carried out by the valve 29. With the mixing of steam and air, they are made, good contact. After

5 gas condensation — in the capillary 7, the vapor condensate enters the cell 4, fills it and through the capillaries through the ion exchange filters 11 is discharged into the steam generator b.

Analyzed air in contact with

0 with steam and steam condensate, saturates the condensate with the analyzed component, which increases the electrical conductivity of the condensate due to the dissociation of the analyzed component in water.

5 Since cell 3 contains pure condensate, and cell 4 contains condensate mixed with a monitored component, the electrical conductivity of condensate in cell 4 is greater than cell 3. This will disrupt the balance of the bridge containing cells 3 and 4, and the magnitude of the imbalance signal will be proportional to the difference between the electric wire and the condensate in cells 4 and 3.

Control of the content of impurities in the gas (air) is carried out on the basis of the available data on the electrical conductivity of aqueous solutions of the components being determined.

The concentration of impurities is determined by the dependence of the concentration on the electrical conductivity at a constant temperature of the solutions:

 (tf) r-const,

where C is the concentration of an aqueous solution of a controlled air impurity, mol / kg;

K-specific oophoodism of aqueous solutions,.

Based on this dependence, the scale of a millivoltmeter connected to the diagonal of the measuring bridge can be calibrated in units of the determined impurity concentration in the gas.

In order for the analysis of controlled impurities of a gas to be reliable, it is necessary that an equal amount of vapor condensate pass through cells 3 and 4 per unit of time. In this case, the influence of the interaction of the material from which the cell elements are made on the electrical conductivity of the condensate is the same for both cells; this effect increases with low consumption of condensate through the cell and decreases with large expenses. The mode of operation at equal flow rates of condensate through the cells 3 and 4 is provided by adjusting the valve 31. Controlling the flow rate of the condensate through the cell 4 is carried out with the valves 26,27 and 31 open by discharging the condensate into the measuring dish. Monitoring the flow of condensate through the cell 3 is carried out with the valve 30 open and valve 31 closed as well.

by dumping condensate into a measuring bowl. The control of the total flow rate of condensate through the cells 3 and 4 is carried out by opening the valve 27 with the valve 26 closed by discharging the condensate into the measuring dish.

The use of ion exchange filters 11 allows the cleaning of condensate entering the feed of the steam generator 6.

. The entire analyzer operates in a closed cycle, the steam condensate is returned back to the steam generator, it is not necessary to continuously feed the steam generator 6. The use of the preheater 9 of the analyzed gas allows, along with inorganic impurities, to analyze concentrations of organic air impurities that decompose when heated , form substances dissociating in water and increasing its electrical conductivity. An example of such impurities is dichloroethane.

Claims (1)

Invention Formula Conductometric analyzer of the content of impurities in the air, containing two flow-conducting conductometric cells included in the shoulders of the AC bridge, one of which is connected to the line supplying the analyzed air, characterized in that, in order to improve the measurement accuracy, the analyzer is equipped with a water vapor generator, with the output of which is connected to the input part of cells with cooled capillaries, and the output part of each cell is connected through ion exchange filters to the input of water vapor generator, line supply of the analyzed air is connected to the cooled capillary the entrance of one of the cells through the capillary, equipped with an adjustable heater of the analyzed air.