RU38945U1 - ANALYZER OF SELECTIVE DETERMINATION OF VOLUME HYDROGEN CONCENTRATION IN GASES - Google Patents

Abstract

1. An analyzer for the selective determination of the volume concentration of hydrogen in gases, containing channels for the input and output of gases and a diffusion cell included in the analytical unit, consisting of two chambers separated from each other by a polymer diffusion membrane, selectively passing H, characterized in that it additionally contains a gas supply unit, a unit for measuring and recording the signal, forming a block system with the analytical unit, while the analytical unit is equipped with a thermoconductometric gas detector and a column in the form trubki.2 metal. The analyzer according to claim 1, characterized in that the metal tube is made with a length of 900-1100 mm with an inner diameter of 3-3.5 mm. The analyzer according to claim 1, characterized in that the thermoconductometric detector contains comparative and measuring chambers in which the thermistors are located. The analyzer according to claim 1, characterized in that the gas supply unit contains an air microcompressor and variable chokes. The analyzer according to claim 1, characterized in that the signal measuring and recording unit comprises a nonequilibrium electric bridge and an automatic plate potentiometer.

Description

The utility model relates to the field of gas analysis, in particular to means for controlling the hydrogen content in various gaseous media, and is intended for use in chemical technology processes, mining, and other industries.

A known analyzer for the selective determination of hydrogen in gases (RU No. 2144718, class G 01 N 27/12, 1999), which contains a housing, channels for input and output of gases and a semiconductor sensor containing a non-conductive ceramic substrate coated with a heater, contacts for measuring conductivity and a sensitive layer, made on the basis of In ₂ About ₃ , modified with additives CuO (1-10 wt.%), selectively analyzing H ₂ . The sensor is placed in a separate chamber of the diffusion cell, isolated from the analysis chamber by a polymer diffusion membrane that selectively passes H ₂ and is purged with a hydrogen-free gas.

The disadvantage of this analyzer is the need to use a special semiconductor sensor made of expensive material and complicating the operation of the measuring instrument due to the need for its coordination with the general measuring circuit.

Utility Model Essence

The task of creating a utility model is to simplify the design while maintaining the accuracy and reproducibility of the measurement results.

The problem is achieved in that the analyzer selectively determines the volumetric concentration of hydrogen in gases containing channels for the input and output of gases and a diffusion cell included in

an analytical unit consisting of two chambers separated by a polymer diffusion membrane selectively passing H ₂ ; according to a utility model, it further comprises a gas supply unit, a signal measuring and recording unit forming a block system with the analytical unit, while the analytical unit is equipped with a thermoconductometric detector gases and a column, in the form of a metal tube 900-1100 mm long with an inner diameter of 3-3.5 mm and a piece of vacuum tube for introducing a sample of the analyzed gas. Thermoconductivity detector contains comparative and measuring chambers in which thermistors are placed. The gas supply unit includes an air microcompressor and variable chokes, while the signal measurement and recording contains a nonequilibrium electric bridge and an automatic plate potentiometer.

The use of a block system including a gas supply unit, an analytical unit, and a signal measuring and recording unit makes it possible to systematize the construction of a measuring instrument and simplify its maintenance. The inclusion of a thermoconductometric detector in the analytical unit makes it possible to use standard measuring circuits, and the use of a metal column allows us to solve the problem of eliminating the influence of external disturbances on the measuring signal.

This solves the problem of simplifying the design, without the use of special sensors, while maintaining the accuracy and reproducibility of the measurement results.

List of figures

The figure shows a diagram of an analyzer for the selective determination of the volume concentration of hydrogen in gases.

Information confirming the feasibility of implementing a utility model

The analyzer comprises a gas supply unit I, an analytical unit II, and a signal measuring and recording unit III.

The gas supply unit I includes an air micro-compressor 1 and variable chokes 2, 3, 4.

In the analytical unit II, there is a diffusion cell 5, a thermoconductometric gas detector 6, column 7 (a metal tube 1 m long with an inner diameter of 3 mm) and a piece of vacuum tube 8 for introducing a sample of the analyzed gas medium. The diffusion cell consists of two chambers 9 and 10, separated from each other by a fluoroplastic membrane 11. The thermoconductometric detector 6 has chambers: comparative 12 and measuring 13, in which thermistors are located.

Block III measuring and recording the signal contains a nonequilibrium electric bridge 14, the circuit of which includes thermistors from chambers 12 and 13, equipped with a stabilized power source. The output of the nonequilibrium bridge 14 is connected to an automatic tablet potentiometer 15, which serves to measure and record the signal of the nonequilibrium bridge 14.

An analyzer for the selective determination of the volumetric concentration of hydrogen in gases works as follows. Before turning on the analyzer in operation, variable flow chokes 2, 3, and 4 control the flow rates of air (air - carrier) at the output of these chokes, setting them to 2-2.5 l / h.

The analyzer is turned on 30 minutes before the start of analysis.

Before the analysis using a resistor, zero is set to the nonequilibrium bridge 14. Set the initial level

the signal of the bridge 14, which should be 10-15% of the scale of the potentiometer 15. A sample of the analyzed gas taken by a syringe that is strictly constant in volume is injected by piercing the tube 8 in a carrier air stream flowing through column 7. This sample is transported by carrier gas through column 7 to chamber 9 of the diffusion cell. When the gases that make up the sample wash the membrane 11, hydrogen diffuses through the membrane 11 into the carrier air stream flowing through the chamber 10. The remaining components entering the gas sample do not penetrate into the chamber 10. The gas stream formed from the chamber 10 after hydrogen diffusion enters the measuring chamber 13 of the thermoconductivity detector 6. The comparative chamber 12 of this detector constantly receives a stream of clean air - carrier from the inductor 4. The nonequilibrium bridge 14 responds to changes in the operation of thermistors in the chambers x 12 and 13 as a result of the appearance of hydrogen in the gas stream entering the detector chamber 13, which causes the signal of detector 6, since the thermal conductivity of hydrogen is much greater (more than 7 times) of the thermal conductivity of air, and generates a measurement information signal to an automatic plate potentiometer 15, on which it is registered. In this case, the amplitude (height h) and the peak area S are proportional to the volume concentration of hydrogen C in the analyzed gas medium

h = K _h C,

or

S = K _s C,

where K _h is the analyzer conversion coefficient by peak height; K _s is the analyzer conversion coefficient by peak area.

In the pulsed mode of operation of the analyzers, it is preferable to use it when processing the results of the peak area.

To obtain quantitative results after each analysis or a series of analyzes performed for a limited period of time, it is necessary to calibrate the analyzer, the latter is carried out by entering a hydrogen sample into the analyzer, the volume of which must be equal to the volume of the sample of the analyzed gas medium.

Area So of the received signal:

S ₀ = K _s C ₀ ,

where C ₀ is the volume concentration of hydrogen in the sample (for pure balloon hydrogen, it can be assumed with sufficient accuracy that C ₀ = 100% vol.)

From the formulas it follows that the volume concentration of hydrogen in the analyzed gas medium can be found from the expression:

This analyzer for the selective determination of the volumetric concentration of hydrogen in gases is made in the form of a prototype.

Claims (5)

1. An analyzer for the selective determination of the volume concentration of hydrogen in gases, containing channels for input and output of gases and a diffusion cell included in the analytical unit, consisting of two chambers separated from each other by a polymer diffusion membrane, selectively transmitting H ₂ , characterized in that it additionally contains a gas supply unit, a signal measuring and recording unit, forming a block system with the analytical unit, while the analytical unit is equipped with a thermoconductometric gas detector and a column in de metal tube. 2. The analyzer according to claim 1, characterized in that the metal tube is made with a length of 900-1100 mm with an inner diameter of 3-3.5 mm. 3. The analyzer according to claim 1, characterized in that the thermoconductometric detector contains a comparative and measuring chambers in which the thermistors are located. 4. The analyzer according to claim 1, characterized in that the gas supply unit contains an air microcompressor and variable chokes. 5. The analyzer according to claim 1, characterized in that the signal measuring and recording unit comprises a nonequilibrium electric bridge and an automatic plate potentiometer.