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PROJECT: 45 MW Biomass Boiler Stability

Completed the design, installation, commissioning, and tuning of improved boiler fuel and air control logic for a 45 MW biomass shaker grate boiler power generator. Previously and since early 2014, it was not uncommon for the 1400 psig boiler to experience pressure swings as great as +-100 psi. Many thought that this was a direct result of the diverse BTU content in their fuel mix. After the completion of the commissioning and tuning portion of the project, the improved control logic design now achieves boiler pressure stability within +-10 psi; even while holding the MW output within +-0.5 MW and not using the turbine for pressure control.

The primary components for this improvement was the implementation of correct control theory and traditional boiler fuel/air process and control logic designs. Prior to the installation of the improved logic/tuning, it was not uncommon for the operators to respond to approximately 100 pressure control associated annunciation alarms. In the first four days of operation with the new logic, not a single pressure control alarm came in!

The boiler fuel and air controls always remain in fully automatic mode with very little need for operator attention.

RESULTS


• Through use of my extensive experience in reverse engineering of control system logic, I found many discrepancies in the departure of traditional fuel/air combustion control theory and stable regulatory analog control theory design.

• Redesigned the fuel/air regulatory analog control logic to more traditional and proven combustion control theory. Also, redesigned the areas of the control logic that I had identified as inherent to causing instabilities.

• Successfully conducted a full boiler tuning program on the upgraded combustion control logic achieving remarkable stability seldom seen on a biomass boiler burner a extremely diverse fuel mix.