Dehydration after methanation
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This post was last edited by dragon__x on 2011-5-13 17:05. In ammonia synthesis projects, the methanation process involves installing molecular sieve adsorbers at the methanation outlet or at the exit of the first stage of the syngas compressor, in order to prevent liquid droplets from damaging the compressor. Is there any method that does not use molecular sieves?
Of course there is. In the early KELLOGE process, there was no molecular sieve dehydration step; the fresh gas mixed directly with the gas from the synthesis circuit at the third stage of the compressor before entering the refrigeration circuit. There, liquid ammonia was cooled and separated, after which the gas proceeded to the synthesis tower for reaction. The moisture in the fresh gas eventually ends up in the ammonia produced; this is also the ammonia separation process before the tower. Furthermore, in small ammonia plants, the fresh gas enters the ammonia cooler where water is removed through cooling and separation; after that it mixes with the recycled gas, is compressed, and then sent to the synthesis tower.
Thank you for the answer from above. Are there two methods: first cooling the gas and water separately after alkylation, and then removing water using a molecular sieve before compression?； Next, after deep cooling of the gas-liquid ammonia mixture following alkylation, water is separated and then compressed ； What are the advantages and disadvantages of each of these two approaches?
After methanation, it is sufficient to remove the water from the gas using a water cooler and a separator; this has no impact on the subsequent compressors. As the synthesis gas is compressed to the pressure required by the synthesis system, oil and water can be removed through the successive stages of compression, cooling, and separation in the compressors
Our methanated gas is cooled with water and then passes through a water separator. Since the temperature of the circulating water is high in summer, an ammonia cooler is installed after the water separator to cool the gas before further water separation. They are all upgraded from the original old equipment.
What is the outlet temperature after ammonia cooling? Will it freeze?
This post was last edited by mfjxg on 2021-9-15 at 15:11. We use a simple water-cooling + separation system; problems arise in hot summer weather when there is too much water in the compressor sections and in the make-up air separator, which affects the compressor’s performance. Now consider adding ammonia cooling and molecular sieves after water cooling.