140XTS00500 What are the common gas analyzers at this stage? How does it work? Technology information automation
1. Thermal conductivity gas analyzer
140XTS00500 A kind of physical gas analysis instrument. According to the mechanism that different gases have different thermal conductivity, the content of some components is measured by measuring the heat transfer coefficient of mixed gases. This kind of analysis instrument is simple and reliable, suitable for many kinds of gases, and is a basic analysis instrument. However, it is difficult to directly measure the heat transfer coefficient of the gas, so in fact, the change of the heat transfer coefficient of the gas is often converted into the change of the resistance, and then the bridge is used to determine. The thermal sensitive elements of the thermal conductivity gas analyzer are mainly sensitive elements and metal resistance wires. The semiconductor material sensitive element has small volume, small thermal inertia and large resistance temperature coefficient, so the sensitivity is high and the time lag is small. Sintered bead metal oxide is used as the sensitive element on the platinum coil, and a non-reactive material is wound on the same platinum coil with the same internal resistance and heat transfer as the compensating element (Figure 1). These two components constitute the bridge circuit as two arms, which is the measurement circuit. When the metal oxide sensor of semiconductor material adsorbs the measured gas,140XTS00500 the conductivity and thermal conductivity change, and the heat dissipation state of the component also changes. The temperature change of the element changes the resistance of the platinum coil, and the bridge has an unbalanced voltage output, according to which the concentration of the gas can be detected. The thermal conductivity gas analyzer has a wide range of applications, in addition to the usual analysis of hydrogen, ammonia, carbon dioxide, sulfur dioxide and low concentration flammable gas content, but also as a detector in the chromatographic analyzer to analyze other components.
2. Electrochemical gas analyzer
140XTS00500 A chemical gas analysis instrument. It measures the composition of a gas in terms of the change in the amount of ions or the change in current caused by a chemical reaction. In order to improve the selectivity, prevent the surface of the measuring electrode from fouling and maintain the performance of the electrolyte, the diaphragm structure is generally used. The commonly used electrochemical analyzer has two kinds: constant potential electrolysis and galvani battery. The working principle of the constant potential electrolytic analyzer (FIG. 2) is to apply a specific potential on the electrode, and the measured gas will have an electrolytic effect on the electrode surface. As long as the potential added to the electrode is measured, the unique electrolytic potential of the measured gas can be determined, so that the instrument has the ability to select and identify the measured gas. Galvani battery analyzer (Figure 3) is to electrolyze the measured gas diffused into the electrolyte through the diaphragm, measure the electrolytic current formed, and determine the concentration of the measured gas. According to the selection of different electrode materials and electrolytes, the internal voltage of the electrode surface can be changed to achieve the selectivity of the gas with different electrolytic potential.
3, infrared induction absorption analyzer
140XTS00500 An analytical instrument that operates according to the characteristics of selective absorption of infrared induction by different constituent gases at different wavelengths. The type of gas can be distinguished by measuring the absorption spectrum. Measuring the absorption intensity can determine the concentration of the gas being measured. The infrared induction analyzer has a wide range of use, which can not only analyze the composition of gas, but also analyze the composition of solution, and has high sensitivity, rapid reaction, continuous online indication, and can also constitute a regulation system. The detection part of the infrared induction gas analyzer commonly used in industry consists of two optical systems with the same structure in parallel.