Plant Performance Improvement through Combustion Optimization

摘要

It is estimated that in most boilers, anywhere from 10 to 35% of the control loops are in manual and about 85% have incorrect tuning parameters. The result is an increased risk of unsafe boiler operation, inefficient combustion and emission control, along with a high degree of process variability from shift to shift. Studies have shown that automating the base controls and implementing an Advanced Process Control (APC) solution could potentially provide bottom-line benefits in the range of 2 - 6% of operating costs. This paper presents technology and results from two different APC implementation projects. The first project is the combustion control optimization of a 22 year old boiler burning high sulfur waste coal. The APC solution resulted in a 13% reduction in reagent use for emission control. The tighter and more cost effective emission control permitted the owner to comply with future (2016) emission regulations without the need of a back end scrubber. This presented a capital cost avoidance of about $12 million. The second project is the combustion control optimization of a biomass boiler commissioned in late 2013. The APC solution implemented on the fuel, air and emission controls resulted in improvements in boiler efficiency (0.2%), lower CO emissions, lower NH3 consumption for NOX control, and enabled the boiler to respond to 3 - 5% per minute demand load changes. These two projects represent contrasting scenarios in terms of fuel, operating targets and age of the boiler, but in either case, the benefit from the APC project was significant. They demonstrate clearly the need for the industry to stop neglecting opportunities and start leveraging an asset the plant already owns - the control system.