Adjustment algorithm of damper openings of tangentially fired boilers based on secondary air distribution

In the design of tangentially fired boilers, because of the limitations of the occupied area and on-site space, the structural relationship between the windbox of the secondary air pipe and the burner nozzle is the main pipe and the parallel branch pipe. The distribution of secondary air flow in each layer of the burner nozzle is not uniform when the boiler is running at peak-shaving operation. Therefore, after the distribution method of secondary air flow is determined, the adjust of air flow through the precise adjustment of secondary air damper opening is necessary. An adjustment model of secondary air damper opening under a hot condition is established through the effective coupling of the Newton–Raphson descent iteration method and a three-dimensional numerical simulation method. For different secondary air distribution objectives, precise adjustment of secondary air damper opening can be achieved through a few times of numerical simulation calculation using this model. Given the secondary air pipe of a 350 MWe supercritical tangentially fired boiler as the research object and two secondary air distribution objectives as examples, the feasibility and accuracy of the model are verified by realizing precise adjustment of damper openings. • An adjustment algorithm of secondary air damper openings is presented. • A new coupling model is established to adjust secondary air damper openings. • Resistance characteristics are calculated using numerical simulation. • The effects of damper opening on pressure drop are studied. • Damper openings are obtained by Newton-Raphson descent iteration method.