Valmet APC application improves biomass combustion at westrock Covington

Valmet’s Advanced Process Control (APC) application, DNA FBB Combustion Manager, is now in use to optimize combustion in the biomass boiler at WestRock’s Covington, VA, mill. As a result, the mill can maximize and increase the boiler’s main steam output beyond the maximum continuous rating (MCR).

Other benefits include more stable and controlled steam output as well as better operational uniformity across shifts, furnace symmetry and spray valve control.

Valmet’s APC estimates the British thermal units (BTU) of the biomass fuel in real time and ensures a consistent optimum fuel power-to-air ratio.

The application is reported to have lowered the average O2 by about 0.3 percentage points, which improves boiler efficiency, reduces NOX emissions and subsequently minimizes NH3 consumption. Additionally, the controller now properly allocates the fuel demand between the feeders, taking into account any control and/or mechanical process limitations.

“This improvement has enabled us to run a higher, more stable load, resulting in a record-setting steaming average the following month,” says Barry Hensley, powerhouse superintendent, WestRock.

The combustion control application is part of the boiler plant’s Valmet DNA automation system. In 2012, Valmet supplied the automation for the new biomass bubbling fluidized bed boiler at Covington. The scope of the system included the boiler, Balance of the Plant, auxiliaries and a training simulator.

Valmet DNA FBB Combustion Manager offers optimized combustion for both bubbling and circulating fluidized bed boilers. Its purpose is to protect the combustion process against variations in production, fuel amount and quality, and combustion circumstances.

As a result, the environmental, operational and financial benefits include a stabilized combustion process, increased boiler efficiency, a wider boiler operation range, minimized flue gas oxygen content and minimized NOX and CO emissions.

Valmet Automation, www.valmet.com

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