The air separation unit located at the Lukoil Karpatneftekhim plant in Kalush, Ukraine was designed and built in 1996. According to the CCS initial site survey report, the air compressor began experiencing problems in 2010:

• Excessive vibration of the first stage of the compressor (YT1111)
• Vibration of the suction line and service platform
• Increased noise of the air flow in the area of the compressor

These were all typical signs of unregulated compressor control resulting in multiple compressor surges over time. These findings were confirmed in the course of surge tests conducted during commissioning.

These issues were a major cause of up to 12 unscheduled plant shutdowns per year. As the existing control system was no longer capable of preventing the compressor from surging, the decision to replace the entire compressor control system was made. Further to CCS' successful implementation of the surge prevention control system on the chlorine compressor units at the same site, Karpatneftekhim appealed to CCS with a request to design a compressor control system for the air compressor unit. One of the requirements was to implement a Yokogawa hardware/software-based solution since the plant was planning on upgrading to a Yokogawa Centum DCS in the near future. Part of the upgrade project is to maintain critical operating systems in a common hardware platform.

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