Emergency pressure relief
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I would like to ask: the emergency pressure relief values for hydrogenation units are 0.7 and 1.4 MPa. Some of these devices are installed above the cold high-pressure separator, while others are installed above the liquid separation tank at the inlet of the recycle hydrogen compressor. What is the difference between these two setups, and what are the design principles behind them?
Theoretically, installing it in either of these two locations can achieve the purpose of pressure relief, but different patent holders may make design differences in order to avoid infringement. In fact, most units locate the pressure relief point at the cold high-pressure section; if it is set at the compressor inlet separator tank, pressure release may cause significant damage to the circulating hydrogen desulfurization tower, even damaging its trays. At the same time, the amine solution on the tray may be carried over to the liquid separation tank; if a pressure release of 7 bar occurs while the recycle hydrogen compressor continues to operate, this will cause fluctuations in the liquid level in the separation tank, which in turn can lead to the compressor shutting down as part of an interlock mechanism. Overall, installation in a cold high-pressure section is the more common method.