Ask Ron Besuijen

Ron's Response:

Let us first look at a definition from Kumar Dey “Centrifugal compressor surge is a characteristic behavior of the compressor that occurs in situations when inlet flow is reduced, and the compressor head developed is so low that it cannot overcome the pressure at the compressor discharge. During a centrifugal compressor surge situation, the compressor outlet pressure (and energy) reduces dramatically which causes a flow reversal within the compressor”. This is considered to be a very dangerous and detrimental phenomenon as it results in compressor vibration that results in the failure of the compressor parts.

Surge conditions have caused loss of efficiency, mechanical damage, loss of containment and loss of life. A compressor is most susceptible to surge during startup, reduced load or sudden load changes. Surge controllers can be managed by basic PID flow controllers or a dedicated controller system. 

Simulators have been successfully used to test and tune dedicated controller systems before they are installed in the process. This can reduce their commissioning time and allow the unit to return to full production sooner. It will also help to validate the accuracy of the control philosophy and expedite updating the startup procedures. 
Training panel operators to respond to surge conditions is also critical. Basic PID flow controllers are typically inadequate to handle large surge events and require operator intervention. This requires a large output increase on the controller that operators need to train for and be comfortable with. 

Dedicated surge controllers can handle surge events more effectively. Operators will need to be trained on its functionality and how to manage instrumentation failures. There are several flow, pressure and temperature transmitters that input to the controller that can drift or fail that can impact the control system. These failures can be practiced on a simulator to train the panel operators to detect failures and respond correctly to mitigate the impact. 

Simulators are an excellent tool to train operators regardless of the control system. They can also be used to test new systems to increase effectiveness and reduce commissioning time. During some upsets a panel operator may not have five minutes to choose a course of action, never mind six months. 

Fortunately, we have simulators to train our operators, and they do have a pause button so they can develop the skills required to pick up on cues, anticipate developments and validate their actions. Simulator training is not only about learning to complete tasks and execute procedures, but also about developing a thought process that is critical to responding to problems that have never been thought of. 

The Dynamic Mental Networks concept is an attempt to further our understanding of how process operators must navigate difficult problems in a dynamic environment.