WestRock Improves Combustion with Valmet APC Application at Covington Mill

Valmet's Advanced Process Control (APC) application, Valmet DNA FBB Combustion Manager, has improved combustion for the biomass boiler at WestRock's Covington mill in Virginia, USA. 

By optimizing combustion, the mill has been able to maximize and increase the main steam output of the biomass boiler beyond the maximum continuous rating (MCR). Other benefits include more stable and controlled boiler steam output as well as improved operational uniformity across shifts, furnace symmetry, and spray valve control. Valmet's APC application 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 has lowered the average O2 by about 0.3 percentage points, which improves boiler efficiency, reduces NOX emissions, and subsequently minimizes NH3 consumption. Additionally, Valmet's advanced load 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," said Barry Hensley, powerhouse superintendent, WestRock.

The combustion control application is part of the boiler plant's Valmet DNA automation system. In 2012, Valmet was chosen as the automation supplier for the new biomass bubbling fluidized bed boiler at the Covington mill. The scope of the system included the boiler, Balance of the Plant, auxiliaries and a training simulator. Valmet's strong project execution team and close cooperation with Covington personnel made it possible to meet the challenging project deadlines. 

"Valmet's commitment to a shared journey forward together with the Covington mill is how the APC project came about. The ROI for the project was less than six months. With our solution and biomass expertise, and working together with the mill's personnel, we were able to exceed all of the project targets," said David Eapen, solution manager, Automation, Valmet.

Valmet DNA FBB Combustion Manager is an advanced control application for the optimized combustion of both bubbling and circulating fluidized bed boilers. The purpose of the application is to protect the combustion process against variations in production, fuel amount, fuel quality, and combustion circumstances. 

As a result, Valmet DNA FBB Combustion Manager provides several environmental, operational, and financial benefits, including a stabilized combustion process, increased boiler efficiency, a wider boiler operation range, minimized flue gas oxygen content, as well as minimized NOX and CO emissions.

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