Operation monitoring method for the amine solution system

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Monitoring of amine solution: For exhaust gas treatment units equipped with the SCOT process, the quality of the amine solution is a critical control factor to ensure proper emissions from the unit. We can monitor the amine solution using the following parameters and adjust the operation of the exhaust gas treatment process to meet our desired requirements. 1. Color monitoring of rich liquid and lean liquid. The color of the amine solution is basically transparent at first; once the amine solution starts to come into contact with the process gas, its color changes dramatically. The rich liquid will rapidly change from colorless to brownish-green, as a result of the reaction between hydrogen sulfide in the process gas and iron. As a protective film of ferrous sulfide accumulates on the surfaces of pipes, heat exchange systems, towers, and other equipment, a more dense protective layer is formed, which prevents further reaction between hydrogen sulfide and iron. This is precisely why ordinary carbon steel can be used in amine solution systems. However, in some amine solution systems, corrosion is not only not suppressed but tends to worsen, leading to various problems, which will be explained in detail below. Generally speaking, the color of the rich liquid definitely contains some green tones, or even dark brown shades; it is darker in color compared to the lean liquid. The rich liquid contains more solid particle impurities than the lean liquid. The lean solution usually appears light brown or light yellow; by controlling the color of the amine solution, it is possible to monitor the quality of the amine solution as well as the quality of its regeneration. For example, if the amine solution is red in color, it indicates that it contains a large amount of iron ions and there is an oxidation issue; in such cases, it is necessary to check whether the amine solution is exposed to oxygen in the system and to address the problem promptly. When hydrogen sulfide gas is introduced into the lean solution in the laboratory, the color of the amine solution changes to black rapidly, indicating that the concentration of carbon dioxide in the amine solution is high. Therefore, there are definitely issues with the use of filters in the rich solution, and this should draw our attention. The greenish color of the lean solution indicates that there are certain issues with the quality of its regeneration, which means we need to focus our attention on the regeneration system. 2. Monitoring of solid particles in the aqueous solution: Solid particles are generally present in amine solutions, and to varying degrees, they have an impact on the system. The sources of solid particles may include FeS, FeCO3, HSS, and other substances. There are no strict regulations or industry standards regarding the amount of solid particles in amine solutions. However, it is certain that the erosion and wear caused by these solid particles are among the main factors contributing to corrosion in amine solution systems. 3. It is necessary to conduct regular analytical tests on the composition of the amine solution in order to monitor its components. Relevant data indicate that the allowable ranges for these substances in the amine solution are as follows: ACETATE – less than 1000 ppm wt%; CHLORIDES – less than 1000 ppm wt%; FORMATES – less than 1000 ppm wt%; SULFATES – less than 500 ppm wt%; THIOSULFATES – less than 10,000 ppm wt%. The controlled concentration of HSS in the amine solution should be between 1-2%, with a maximum level not exceeding 3%.