When should venting be carried out before starting up the ammonia synthesis tower, and when should it be done after startup?
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When should venting be carried out before starting up the ammonia synthesis tower, and when should it be done after startup?
This similar topic has been discussed before; please refer to this post: http://bbs.hcbbs.com/viewthread.php?tid=717265
The venting before and after the synthesis tower is primarily related to the process design and selection, each having its own advantages and disadvantages. However, nowadays most systems use back-pressure venting at the tower; the Kellogg process that was used in the past relied on front-pressure venting. Thanks to technical improvements, most systems now employ back-pressure venting instead
Under normal conditions, venting is carried out after the tower is started up to keep the methane level in the system within a certain range; in the case of shutdown and pressure relief, venting after starting up the tower is the main method, with slight venting also done in front of the tower； If the venting is set to a high level before starting the furnace, it may cause gas backflow, which can deposit catalyst powder on the electric furnace and affect its normal operation; in severe cases, this can damage the furnace.
The tower vent is generally used for controlling tower temperature and during shutdown pressure relief. When the temperature in the synthesis tower drops, venting before the tower is used to adjust the gas flow, but the opening degree of the vent valve must not be too large to prevent gas backflow.