In this case history, an auto assembly plant enjoys a reduction in energy use and maintenance after retrofitting a powerhouse boiler with a new control valve system.

Potential energy savings continues to motivate industry to analyze their processes for efficiency improvements and to cut operating costs. A major automobile plant in North America is experiencing reduced fuel usage, reduced maintenance, and enhanced safety, through a powerhouse control modification that is producing measurable results.

The savings were produced by replacing existing mechanical burner controls with an electronic air/fuel ratio control system on one of four powerhouse boilers. These boilers are used to generate steam for heating and energy to run various operations at the final assembly plant.

Maxon’s SMARTLINK® MRV, a parallel-positioning ratio control valve system, was installed on the plant’s No. 3 boiler to optimize fuel utilization by reducing control errors and reducing excess combustion air.

SMARTLINK® MRV is an electronic fuel / air ratio control system designed for use in industrial applications. Where mechanical systems and jackshafts produce moderately good control, they require frequent maintenance and seasonal adjustment. SMARTLINK® resolves maintenance issues and improves control with a high degree of precision and repeatability with intelligent valve architecture. The powerhouse’s operating personnel set a 22-point control profile for each valve, maintaining precise ratio and temperature control under different operating environments.

Because its actuators are adjustable to 0.1 degree of accuracy, SMARTLINK® nearly eliminates valve hysteresis normally encountered with traditional, mechanically-linked valves, dampers, jackshafts, and control motors. It also reduces setpoint hunting, which decreases fuel usage, reducing the dead band on operating temperature.

Specific fuel cost savings on this boiler were proven using data comparing performance before and after the SMARTLINK® conversion. The No. 3 boiler’s conversion cost provides a ROI of 1.5 years at the operating capacity of 20 MMBtu/h with a conservative fuel/air ratio setting. By further reducing excess oxygen at maximum fire, additional fuel savings is expected to bring the return on investment for installing SMARTLINK® down to 1 year or less.

Enhanced plant safety was another benefit of the conversion, since the new valve actuators are Factory Mutual (FM) approved as non-incentive for hazardous locations. They also meet the demands of rugged industrial environments with fully sealed, metal housings rated for NEMA 4X application.

The system also provides self-check and fail-safe outputs, continuously comparing real-time positions to setpoints. The SMARTLINK® system communicates with any common burner control for prompts before allowing modulation; an important safety not found on most control systems. Access to setpoints and configurations in the control system are protected by an electronic pass code to prevent unauthorized adjustments or tampering.

The conversion of mechanical linkages to this electronically linked valve system at the auto plant has proven to not only reduce their fuel costs, but other “wins” are reduced maintenance and a very high degree of additional operating safety. TB

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