It’s desperate. The level in the column sump is simply unstable and fluctuates like a drunken sailor. The process control system (PCS) and the plant operator are constantly occupied with keeping these fluctuations under control to such an extent that the plant is at least running and no permanent alarm is triggered. And what have we not already tried everything. Tuning the control loops in the PLS, improving the instrumentation, looking for process or control connections that cause these problems and so on.