Seeking a pre-cooling scheme for the propylene chiller in an ethylene plant.
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The facility is equipped with 6 ethylene storage tanks of 2,000 m3 each, and one chiller (using propylene as a refrigerant) that is shut down for maintenance. At present, the olefin separation unit is not in operation, so it is not possible to carry out pre-cooling of the gas and liquid phases; instead, an ice machine must be used to cool the storage tank (which contains nitrogen). I am seeking good suggestions on how to proceed. Thank you.
Is there a flash tank? Is there ethylene in the system?
It’s a spherical tank, not the type that operates at atmospheric pressure.
It’s not that complicated actually; we pre-cool them one by one.
Your system currently contains nitrogen at room temperature; you can use a refrigerator to lower the temperature of this nitrogen, and then send it from your system to the sphere tank for pre-cooling. If pressure is required for pre-cooling, you can use a compressor to compress nitrogen and supply it to the system. Controlling the load on the refrigerator allows for good control of the nitrogen temperature. The second method is to use a liquid nitrogen truck for pre-cooling, but you need to plan the startup time of your ethylene plant carefully; pre-cooling with liquid nitrogen must be followed immediately by pre-cooling with process gas, otherwise the temperature will rise again. Personal advice! I hope this can be helpful to you.