That would be a good comparison study to do - as far as I know, CCC seem to have a monopoly share of the antisurge controller market for high capacity centrifugal compressors, for some unknown reason. I dont know of anyone who has been brave enough to veer away to some other make. Having said that, I also know of many compression units offshore with unstable capacity controls in the South China Sea, running on CCC performance / antisurge controllers.
well, having first hand experience, the original owner (Naum and Saul ?) did significant work in collecting/analyzing compressor operating/anti-surge data and incorporated the results into a simple and effective anti-surge control system. the controller is suitable for axial and centrifugal units, different MWs, etc. They did the math and it is well proven. What i initially learned of anti-surge control systems was completely changed upon learning otherwise.
yes, the cost may expensive, but when anti-surge control and process control is needed, CCC is certainly the best. i know there are others that can deliver the same goods, but the good people at CCC have the knowledge and experience to handle simple and complex control systems. remember this, the control system is only as good as the controller, control elements, and sensors are. i have witnessed a controller work just fine, but the 100+ year old control element had so much slop in mechanical elements/linkage that the operators were continuously trying to tune out the cyclic responses. nobody bothered to look or observe the mechanical control elements.
the software can be customized to fit the end-users need.
yes, i have done simple anti-surge control systems (had a plc programmer do the programming) and it worked just fine. but if i had 3 axial flow compressors in series and parallel w/ 4 other similar units (3 series axial flow compressor) (an aerodynamic test tunnel) , or a single driver for two centrifugal units, yes, i'd seriously consider the best. the last thing the owner would want is a failed unit and causing delays.
regarding unstable capacity control, well, first thing i do is review the design, observe the input signals, observe the control elements, and then look at the controller. it could be any one of these items or something else . . .
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That would be a good comparison study to do - as far as I know, CCC seem to have a monopoly share of the antisurge controller market for high capacity centrifugal compressors, for some unknown reason. I dont know of anyone who has been brave enough to veer away to some other make. Having said that, I also know of many compression units offshore with unstable capacity controls in the South China Sea, running on CCC performance / antisurge controllers.
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Comparaison Study:
Control System by CCC
Price: Very High
Reliability: High
Algorithm Sophistication: High
Proven References: High
Suitability for complex process: High (e.g. LNG, load sharing, etc.)
Suitability for basic process: High
Field service cost: High
Support / operator training: Tailored to product
Control System by Compressor OEM
Price: Moderate to Low
Reliability: High to Moderate
Algorithm Sophistication: Moderate to High
Proven References: High
Suitability for complex process: High depending on Compressor vendor experience
Suitability for basic process: High
Field service cost: Moderate to High
Support / operator training: More industry generic
One of the tougher process controls challenges for combination performance and antisurge controllers is to enable decoupling of control interactions for compressors when operating in parallel, especially with both machines close to min flow (ie close to surge) at min speed.
Many a time, CCC claim they can make one antisurge valve work in both capacity and in antisurge service, but I know of project teams that havent taken credit for this claim, and they prefer the more conservative approach to keep these controllers and their final elements separate.
they can make one antisurge valve work in both capacity and in antisurge service.
This is not difficult to implement.
It is basically an override value of distance to surge (deviation) that is passed to the anti-surge controller as an input from master system, e.g. DCS.
Performance control and anti-surge control fight each other especially in vicinity of surge. If anti-surge control works in capacity control normally the operating point is brought further away from surge.
Are you saying that if there are two or several trains in parallel, there are added complications?
The main complication in parallel compressor train operation it to decouple the controller / control valve interactions between the trains - without this decoupling, this causes oscillations in both controller outputs which leads to unstable operation.
