What limits the minimum starting pressure of a centrifugal compressor?
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One of our company’s hydrogenation units uses a centrifugal compressor as the recycle hydrogen compressor, which is driven by a turbine. The normal operating pressure is 17.8 MPa, and the medium used is hydrogen. Since the hydrogenation unit needs to be purged with nitrogen at the time of startup, and the hydrogenation reactor has a minimum pressure rise temperature – requiring that the temperature exceed 93°C at 4.0 MPa – the recycle hydrogen compressor must be started in order to raise the temperature before reaching 4.0 MPa. The earlier the recycle hydrogen compressor is started, the shorter the startup time for the system. However, this starting pressure cannot be set arbitrarily low; we want to know how this minimum starting pressure is determined and what factors need to be taken into consideration. Please give your advice. This post was last edited by JW4103 on 2008-1-10 16:06.]
Please, all the bosses, share your opinions. Those who are interested may ask
The system pressure is too low; it’s impossible for the circulation volume to increase under such conditions. When the pressure is too low, the amount of gas entering the system isn’t sufficient, which requires backflow. During my time at Hainan, their hydrocracking unit fed hydrogen directly into the system from the hydrogen generator outlet; the hydrogen pressure was around 2.3 MPA. When the hydrocracking pressure reached around 2.3 MPa, the unit would be started up
The starting pressure is determined based on the set compression ratio