Evaluation on cold modeling flow field for a down-fired 600MWe supercritical boiler with multi-injection and multi-staging: A burner location experimental optimization and its validation by real-furnace measurements

摘要

This work presents a burner location optimization by cold modeling experiments and its validation by real-furnace measurements for a new down-fired 600MWe utility boiler with a low-NO_x combustion technology. By recording flow field measurements within a 1:20-scaled model of the furnace, cold airflow experiments were conducted at various burner location settings, i.e., the ratio (denoted by C_l) of the distance between the burner centerline and the front (rear) wall to the arch depth is 35%, 39%, 42%, 46%, and 49%, respectively. Meanwhile, at normal full load industrial-size experiments were performed with measurements taken of gas temperatures in the near wing-wall region, carbon content in fly ash, and NO_x emissions. At settings of 35% and 39%, flow field and velocity distributions along certain cross-sections as well as penetration depths of downward airflows were well-formed symmetric along the furnace center. At the left three higher settings, a deflected flow field appeared in the lower furnace, with the downward airflow near the rear wall being directed upward earlier than that near the front wall. With increasing the C_l value from 42% to 49%, the flow-field deflection became turbulent. To establish a symmetric flow field along with an appropriate airflow penetration depth, a burner location setup of C_l=39% was finally installed in the furnace. As expected, industrial-size data revealed that with the optimized burner location, excellent furnace performance characterized by symmetric combustion, good burnout, and low NO_x emissions, appeared within the furnace.