Analysis method for argon in synthetic ammonia cycle gas
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In our company’s production process, argon comes from two sources: the oxygen used in the gasification furnace and the air used for methane conversion; especially when the air demand in the conversion system is high, a large amount of argon enters the system. Online analyzers are used for analyzing the recycle gas in the synthesis tower, but argon cannot be detected. The method for calibrating argon involves sample collection at regular intervals set by the analyst (once every two hours) for chromatographic analysis; this approach does not allow for timely determination of the amount of inert gases in the recycle gas, resulting in unstable adjustments during the operation of the synthesis tower. Are there any good methods to promptly reflect changes in argon in the recycle gas?
I’m not sure what process your plant uses for ammonia synthesis; online analyzers are used for monitoring the recycle gas, and these analyzers are definitely continuous-type instruments. The Ar content in the syngas is only a few ppm, so it cannot be detected. Unless a maintenance procedure is used to replace the constant analyzer with a micrometer.
1. Typically, the argon content in the circulating gas can be several times lower than the methane content. 2. When there are fluctuations in the amount of air used, it is mainly the hydrogen-to-nitrogen ratio that experiences changes, right? Even if the volume of air changes by tens of thousands of cubic feet per hour, the amount of argon changes by only 100 cubic feet per hour. In a synthesis system (where the actual circulating gas volume is likely to be between 5,000 and 10,000 cubic feet), this should not cause significant fluctuations. So the cause should be sought in the operation. 3. Inert gas analysis by chromatography is very inaccurate. Since the main purpose of chromatography is to analyze the contents of hydrogen and nitrogen, it is impossible to cover everything.
There’s no need to analyze this! Analyzing the hydrogen-to-nitrogen ratio and ammonia content should suffice, right?