SU627391A1 - Thermomagnetic gas analyzer - Google Patents

Description

one

The invention relates to analytical instruments, namely, thermomagnetic gas analyzers for determining the oxygen concentration in gas mixtures.

Thermomagnetic gas analyzers are known, in which the paramagnetic properties of oxygen are used. The gas analyzer consists of a magnetic system creating a non-uniform magnetic field and a heated body placed in this field {1}.

Oxygen contained in the analyzed gas surrounding the heated body, due to its paramagnetic properties, is drawn into the magnetic field and heated from the heated body, thereby losing some of the paramagnetic properties and is ejected from the magnetic field with a lower temperature hydrogen chloride. A thermomagnetic .KOHBeKuiTH is formed around the heated body, the intensity of which is determined by the oxygen concentration. Thermomagnetic convection lowers the temperature of a heated body, therefore, by measuring the change in its temperature, the oxygen concentration in the analyzed gas is judged.

2

. The closest to the proposed is a thermomagnetic gas analyzer for oxygen, made according to a two-bridge ratio scheme, which includes working and comparative bridges 2J. Each bridge contains working and comparative sensing elements included in the adjacent shoulders of the bridge and representing

thermistors and fixed resistors. Sensitive elements are heated by an electric current passing through them up to a temperature of 100–200 C. A working sensitive elements of both bridges are located in a non-uniform magnetic field created by a magnetic system, and the comparative elements are outside it.

Sensitive elements of the worker

bridge are in the medium of the analyzed gas, and the sensitive elements of the comparative, bridge are in the medium of the comparative gas with a constant concentration of oxygen, due to

the output signal of the working bridge is proportional to the concentration of oxygen in the analyzed gas, and the output signal of the comparative bridge is constant and is determined by the concentration

oxygen in comparative gas. Sig, 3 of the worker and comparatively come to the device, producing a signal proportional to their ratio. The readings of the thermomagnetic gas analyzers made according to the two-bridge scheme do not depend on the change in the ambient temperature and the supply voltage, since these factors affect both bridges in proportion to their output signals. Such thermomagnetic gas analyzers contain essentially two thermomagnetic sensors with magnetic systems and because of this, they have large dimensions and mass. The aim of the invention is to reduce the size and weight of thermomagnetic gas analyzers, made according to a two-bridge scheme, while maintaining their basic property - the readings are independent of changes in ambient temperature and supply voltage, i.e. metrological characteristics. The goal is achieved by the fact that in a thermomagnetic gas analyzer the comparative bridge is made in the form of a thermal conductivity bridge, one of which, at least, is a sensitive element is housed in carbon dioxide; those. A thermal conductivity sensor is used that includes two sensitive elements in the form of thermistors included in the adjacent arms of the bridge circuit and located in measuring cells in which there is no heat transfer by convection. One sensitive element, the working one, is in a cell filled with air, and the other comparative element is in a cell with carbon dioxide. Due to the difference in the thermal conductivities of air and carbon dioxide, the sensitive elements have different temperatures, which determines the presence of voltage in the measuring diagonal of the comparative bridge. The use of a thermal conductivity sensor significantly reduces the weight and dimensions of the gas analyzer. Filling a comparative cell with carbon dioxide provides the most common design of the thermomagnetic sensor (used as a working bridge), the independence of the readings of the ratio of changes in ambient temperature and voltage, Thermomagnetic gas san alkoe agora j made in accordance with invented. by ginning. have dimensions and mass of sensors by 30% h ..; Shu: h & previously known, the complexity of manufacturing the heat transfer sensors are 3– 3-4 times lower than that for dl. The State of the Art of Magnetic Sensors, the Invention of the Invention Thermomagnetic gas analyzer ka oxygen “made according to a two-bridge circuit is fired. ; including working bridges; About the fact that, in order to reduce the size and weight of the device while maintaining its metrological characteristics, the comparative bridge is made in the form of a thermal conductivity bridge, one of which is less sensitive, and has a noticeable stencil "Information sources taken BQ attention during examination; 1.Pavlenko B.A, Gas analyzers., M, Lo, 1965 ,. with. 7 2-79 „2. In the same place, s, 79-82,