Liquid level of the external heat exchanger in the catalytic cracking unit
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The liquid level in the external heat exchanger of the catalytic cracking unit fluctuates greatly, just like an ECG. Dear friends, please help me analyze what the reason is How can we reduce the fluctuations? The external heat exchanger of my unit has a superheating section built in to directly generate superheated steam.
Try operating the valve manually first to see if the liquid level still fluctuates in the same way If there is no more fluctuation, it means your PID parameters have not been tuned properly! If the fluctuations continue, it indicates that they are caused by unstable heat extraction. It is necessary to adjust the fluidization air or loosening air to stabilize the heat extraction!
Fluctuation problems fall into two categories: 1) fluctuations in the steam system, such as unstable water supply and variations in steam consumption or pressure after steam generation. This can be tried manually using the water inlet valve or the steam pressure control valve. 2. The external heat source for heat extraction is unstable. The fluidization related to the external heat exchanger is influenced by the bed temperature and the loosening air, as well as by the structural design of the external heat exchanger (downflow type, backmixing type); it is relatively difficult to adjust. It is also necessary to check whether the external heat exchanger is operating within its normal load range (both overloading and underloading can have a significant impact). Finally, it is important to verify whether there are any perforations or leaks in the tubes of the external heat exchanger (this possibility is low, but it has been encountered before).
First, remove the internal overheating section; the inner tube is protected by low-pressure steam, and it is checked whether there are any perforations in the internal heat extraction tubes