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This post was last edited by yuchenchf on 2017-4-22 08:48. Infrared gas composition analyzers are primarily used in industry to analyze the composition of gases. By analyzing changes in the measured gas parameters, it is possible to understand the patterns of variation in these components, which in turn provides valuable guidance for achieving dynamic control throughout the production process. Such analysis is of great significance both for theoretical calculations and for on-site operations. This instrument is suitable for analyzing components such as CO2, CnHm, O2, CO, CH4, H2, and NOx in gas, semi-water gas, shift gas, and feed gas in industries such as nitrogen fertilizer plants, steel companies, and gas factories. Currently, there are mainly two categories of analytical instruments available on the market: laboratory analyzers and process analyzers. Here is a brief introduction to the instruments suitable for analyzing the composition of gas. I. Common Laboratory Analysis Instruments 1. Olsch Gas Analyzer. As a classic manual analyzer based on chemical principles, the Olsch gas analyzer offers advantages such as low cost, ease of operation, and simplicity in maintenance. It has been widely used for determining the concentrations of substances such as CO2, O2, CO, and H2 in gas. The principle involves using absorption methods to determine acidic gases, unsaturated hydrocarbons, oxygen, and carbon monoxide; hydrogen is burned on copper oxide, while saturated hydrocarbons burn on platinum wires in the presence of oxygen from the air, with weighing being used for measurement. Although this instrument is simple to operate and relatively inexpensive, its accuracy during measurements is not very high; the precision depends on the operator’s skill level, and the measurement data are not as intuitive and clear as those displayed on an LCD. The main limitations of Austen gas analyzers in terms of application are: 1) The volume of the comb tube affects the analysis results ； 2) Ar cannot be analyzed; it is not suitable to use an austenometer to analyze the cycle gas, and gas chromatography should be gradually adopted instead ； 3) The time required for conducting a hot work analysis using an austometer is long, and there may be certain errors; in addition, it is necessary to pay attention to the degree of completion of the chemical reaction, otherwise inaccurate readings can mislead production processes. 2. Trace sulfur analyzer: With the adoption of new desulfurization processes at normal temperatures, it is essential for nitrogen fertilizer plants to be equipped with trace sulfur analyzers. These instruments help ensure the safety of hydroformylation catalysts and ammonia synthesis catalysts, and provide a fast and convenient method for the qualitative and quantitative detection of various trace forms of sulfur in the gas samples produced. 3. Combustible gas detectors: Using an oxygen analyzer for hot work analysis takes a long time and may involve certain errors; therefore, it is recommended to use combustible gas detectors. 4. Industrial gas chromatograph: Industrial gas chromatography is most commonly used in gas analysis, with the gas components being determined in the order of H2, N2, CO, and CO2. Furthermore, this technique can also be used for the analysis of such components in converter gas and sintering exhaust gas. In recent years, chromatographic analyzers have become more widely used, but they require the separation of gases before analysis, which makes real-time online operation difficult to achieve. Except for a few blast furnaces in the country that still use this method, industrial gas chromatographs are gradually being replaced by mass spectrometers or infrared analysis systems. 5. Industrial gas mass spectrometer: The mass spectrometer performs qualitative and quantitative analysis based on the mass-to-charge ratio of the ions of a substance. Gas mass spectrometers typically use electron impact for ionization, and all substances have characteristic modes of dissociation. Mass spectrometers are characterized by extremely fast analysis speeds, the ability to analyze multiple components simultaneously, and high precision in analysis. However, the analytical capabilities of mass spectrometers in terms of multiple components and high speed do not offer significant advantages when applied in processes such as blast furnaces and sintering; the gases also need to be separated before analysis can take place, making real-time online analysis difficult to achieve. Moreover, the cost of such instruments is very high. At present, high-precision mass spectrometers still rely mainly on imports, and their repair parts must also be imported from abroad. Domestic agents tend to respond slowly, which has a significant impact on the operational rate of these systems. Furthermore, the operating environment in domestic markets differs from that abroad; the failure rate of instruments is high, maintenance is required frequently, and the maintenance costs are substantial. 6. Others: Other commonly used devices include conductivity meters, pH meters, spectrophotometers, and moisture analyzers. II. Common Process Analysis Instruments 1. Trace Gas Analyzer The determination of trace amounts of (CO + CO2) in refined gas is an important analysis task in nitrogen fertilizer plants. Due to their low concentrations (CO + CO2 ≤ 25×10-6), and in some cases even at ppb levels, it is difficult to determine these components using manual methods. 2. Thermal conductivity analyzer: Thermal conductivity analyzers are the earliest type of online analyzers to appear, with a large variety of models and wide-ranging applications. They are commonly used to automatically determine the volume fractions of various gases such as H2, Ar, and SO2 in mixtures. 3. Oxygen analyzers: For the online analysis of oxygen content in gas, electrochemical or thermomagnetic oxygen analyzers are commonly used. They have high sensitivity, can be equipped with alarm functions, and are easy to maintain and replace. 4. Constant-infrared gas analyzers: These constant-infrared gas analyzers are used to continuously measure the concentrations of substances such as CO, CO2, NH3, CH, H2, and O2 in various mixed gases; they represent an important category of online analyzers. Non-dispersive infrared (NDIR) gas analyzers, as a fast and accurate gas analysis technique, are particularly common in continuous emission monitoring systems (CEMS) as well as in applications for detecting vehicle exhaust gases. Most of the major domestic manufacturers of NDIR gas analyzers use infrared gas analysis methods developed in the early 1980s internationally, such as using nickel-athomium wires as infrared light sources, employing mechanical means to modulate the infrared light, and using thin-film capacitive microphones or InSb as sensors. Due to the use of mechanical motor modulation, the instrument consumes a lot of power, has poor stability, and is also expensive to manufacture. The use of a film capacitor microphone as a sensor also makes the instrument highly sensitive to vibrations, which renders it unsuitable for portable measurements. With the advancement of infrared light sources, sensors, and electronic technology, NDIR infrared gas sensors have seen rapid development both domestically and internationally. The main advantages lie in the absence of mechanical modulation devices, the use of new infrared sensors and electrically modulated light sources, as well as the adoption of a low-power embedded system in the instrument’s circuitry. These features give the instrument advantages in terms of size, power consumption, performance, and price that surpass those of previous models. The Gasboard-3100 (online type) gas analyzer available on the market today utilizes internationally leading non-spectroscopic infrared gas analysis technology, long-lasting electrochemical sensing technology, as well as MEMS-based thermal conductivity technology. It is capable of simultaneously measuring the calorific value of gas and biogas online, as well as the volume concentrations of gases such as CO, CO2, CH4, H2, O2, and CnHm. The Gasboard-3100 gas analyzer (online type) is widely used for measuring the volume concentrations of multiple components in process gases in the gas industry, such as those found in nitrogen fertilizer plants, steel companies, gas plants, including gas, semi-water gas, shift gas, and feed gases. By analyzing the changes in the parameters of the measured gas, it is possible to understand the patterns of variation in these components, thereby enabling dynamic monitoring throughout the production process. “\"Instrumentation of analytical techniques and automation of analytical instruments\" is the dominant direction of development. Analysis methods and techniques serve as the guide for analytical instruments; established analysis and testing methods all need to be translated into instrumental setups. As production continues to develop, the requirements for the quality and performance of analysis are also increasing, and laboratory analyzers can no longer meet the needs of continuous, automated production monitoring and control. In addition to relying on the currently advancing electronic and computing technologies, the automation of analytical instruments also requires the integrated use of the increasingly popular embedded intelligent platform technologies as well as ultra-precision machining technologies. Process analyzers are gradually becoming widespread in small and medium-sized enterprises in China, providing real-time dynamic control and monitoring for production processes.