NUMERICAL SIMULATION OF THE INFLUENCE OF OFA ON THE COMBUSTION IN A DUAL CIRCLE TANGENTIAL FIRING SINGLE FURNACE BOILER

摘要

Introduction Recently, the USC technology has become a necessary choice for China in the area of clean coal power generation. In the reference [1] a 1000MW dual circle tangential firing single furnace Bitumitefired USC boiler of Yuhuan Plant was researched in numerical simulation method, which has been in service. However, no lignitefired units rated at 1000MW have been in service so far. In light of the domestic abundant lignite resource and mature of USC technology, a 1000 MW lignite-fired USC unit with a single furnace and dual circle tangential firing system is being developed. Staged-air combustion is an effective low-Nox emission technology, which includes air horizontally-staged approach and air axially-staged approach. And the air axially-staged approach means Over-Fire Air (OFA) technology. There is an optimal OFA position for every boiler. In view of the mature of numerical simulation on the combustion process in the furnace, in this paper, a numerical simulation was done to investigate the combustion process in the furnace of the lignitefired USC boiler with OFA approach mentioned above, through which the temperature field distribution, Nox emission and char burnout characteristics with different OFA positions were achieved.