When operating the synthesis section of an ammonia plant the amount of oxygenated compounds present in the fresh make-up gas is a critical parameter to keep closely watched.
Such oxygen-containing compounds, or oxygenates, are typically H20, CO and CO2 and are inevitable residues of the previous operations. It is well known a fact that they are poisons of iron-based synthesis catalyst, leading to its deactivation, the severity of which depends on the actual concentration of the oxygenates and the duration of the exposure. Sometimes this adverse situation develops unnoticed until its negative effects have already become manifest, leading to loss of production and/or earlier than expected catalyst replacement.
Usually not more than 10 ppm of total Equivalent Oxygen are tolerated for long term, trouble-free operation of the ammonia converter (calculated as sum of the ppm of H2O+CO+2xCO2). Higher concentrations are strongly not recommended, and they must prompt operators to quickly find the cause and fix the problem.
It is therefore crucial to measure the actual amount of oxygenates entering the synloop.
While for CO and CO2 this is not a problem since reliable, on-line instruments exist able to detect concentrations as low as 1 ppm and less, the determination of the water content is not so easy, due to the presence of ammonia, and requires customized gas chromatographs with special columns and features, usually not available in ammonia production plants.
To overcome this issue, Casale has devised a simple, portable instrument for the fast and reliable analysis of water (up to 1 ppm) in syngas containing ammonia. The instrument can be placed wherever there is a suitable sampling point, usually at the converter inlet and at the make-up compressor discharge.
The determination of water content with our special instrument is available as a comprehensive service which, if requested, may include the assessment of the converter performances.
If you are interested to know more send and inquiry or get in contact with our Expert.