Continuous Control Issues Concerning Operation Improvement of Small-Scale Biomass Boilers

Abstract To meet the increasing environmental and efficiency requirements, the possibilities to improve the performance of a 25 kW th wood pellet boiler by utilizing PLC and feedback control are investigated. The process is first stabilized by improving the grate sweeping sequence, which originally disturbs the process. Prior to continuous combustion control development, the process is analyzed and identified. After sequential control improvements the combustion behaves well but tends to drift. A PID controller was designed to enable drifting compensation. It is shown that improved grate sweeping sequence and continuous feedback control provide a major improvement for system performance cost effectively.