Flaring: What’s behind a suggestive light in the night?

In oil and gas refining, turbomachinery compressors routinely vent excess gas through flares — the combustive plumes visible above refineries at night. This practice wastes recoverable energy, increases operating costs, and contributes to atmospheric pollution. For decades, anti-surge control relied on proprietary black-box hardware platforms, creating vendor lock-in, high spare parts costs, and lengthy service windows during failures. A Slovakian oil and gas refinery operating an ethylene compression unit needed a control system that could recycle gas within the compressor circuit rather than burning it off, while working across both new and existing plant infrastructure.

Energy Control Technologies (ECT) deployed its configurable anti-surge control algorithms on Rockwell Automation's Allen-Bradley ControlLogix programmable automation controller (PAC), integrated within the PlantPAx distributed control system. The ControlLogix multi-processor architecture allowed a dedicated CPU for ECT's anti-surge algorithms to coexist alongside the standard compressor control CPU on a single PAC — fully segregated at the hardware level yet unified within one control environment. The algorithms manage valve sequencing, pressure and temperature regulation, and cold-gas injection through ethylene transformation curves, with processor scan response rates of 30–40 milliseconds. The solution replaced a proprietary platform and applied equally to the greenfield build and to brownfield retrofits where legacy anti-surge systems can be swapped into existing PlantPAx installations.

The implementation delivered measurable operational and financial improvements for the Slovakian refinery's ethylene compression unit:

• Energy savings: Gas that would have been combusted as flare is now recycled within the compressor circuit, reducing energy waste.
• Higher efficiency: Tighter anti-surge control and integrated valve management improved compressor throughput and asset utilization.
• Increased profitability: The satellite compression unit — previously non-essential to the main refining process — became a meaningful contributor to refinery productivity, with direct impact on margins in a highly competitive refining market.

Access to PlantPAx's native analytics also enabled improved predictive maintenance strategies and reduced unplanned downtime.

• Open-platform control architectures eliminate proprietary vendor lock-in and reduce long-term maintenance costs compared to black-box anti-surge systems.
• Configurable, non-programmable algorithm parameters (600 configuration points in ECT's case) create a repeatable, fully documented process that any qualified engineer can maintain over time.
• Multi-processor PAC architectures allow anti-surge and compressor control to be segregated at the CPU level while remaining integrated within a single DCS environment.
• Brownfield applicability is a practical advantage — existing PlantPAx installations can absorb anti-surge upgrades without a full system replacement.
• Gas recycling through intelligent compressor control converts an environmental liability (flaring) into a recoverable energy and profitability asset.