Experience in using molecular sieves
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How is the service life of molecular sieve desiccants for syngas in ammonia synthesis determined? From a process perspective, parameters such as outlet moisture are within acceptable limits, and the pressure drop across the bed itself does not change much; however, over time the pressure drop in the outlet filter increases.
Our molecular sieves were originally designed to be replaced every 12 hours; after some time, this interval was increased to every two days. When communicating with other manufacturers, we heard that in some cases they replace them once a day. We mainly depend on the cooling efficiency of the methanation water cooler and the separation efficiency of the inlet separator of the syngas compressor. After some analysis, it was found that when the moisture content in the gas entering the compressor is low, 105-F enables relatively complete separation; it takes three days for water vapor to penetrate through a molecular sieve. Therefore, we decided to carry out the replacement every two days. However, at such a rate, it will also take nearly 20 hours for the regeneration process to be completely completed. It is normal for the pressure difference across the outlet filter to start increasing, as there is a lot of dust from the molecular sieve desiccant; it was the same at the beginning for us as well. But after several backflushing operations, the situation is now basically normal. The performance is also very good.
How is the service life of molecular sieve desiccants for syngas in ammonia synthesis determined? 1. Inlet temperature and pressure of the molecular sieve. The water content depends on the water vapor pressure. 2. The absorption capacity of molecular sieves. Regeneration effect, age of the molecular sieve. 3. Safety factor.