Study On The Technology Of Low-NO_x Emission Optimized Operation In A 135 MW Circulating Fluid Bed Boiler

The circulating fluidized bed (CFB) is one of the high-efficient and low-pollution burning technologies which is evolved from babble fluidization bed. Because of their advantages of high-efficient and low-pollution, wide adaptability to various kinds of coal, load adjustment and economical, CFB has been developed rapidly and has been applied to many industry such as utility boiler, industrial boiler and waste recycling over the dozens of years. The effect of operating parameter on the operating economy and pollution emissions is closely related with many influence facts such as coal, boiler design and unit load. The technical features of CFB boiler are firstly summarized in this paper. Integrated approach is adopt to identify the running state of unit which combined computational fluid mechanics and field test method. The paper is intended to offer advises about reform of unit and improving the operating economy and decreasing the pollution emissions. Following aspects are included in this paper:1. Although the secondary air has a significant impact on combustion and NOx emission in the furnace, the power plant operators incapable of judging the distribution of secondary air system. By numerically studying of the influence factors of secondary air distributions, the curves of different load, open of air door and rate of the upper layer secondary air are obtained. Via further optimize the opening of damper, we has achieved the balance of the secondary air velocity in horizontal direction of the boiler, the optimization of the combustion, and improved the boiler efficiency.2. The flow field, temperature distribution, gas component concentrations and NOx formation in the furnace are obtained by numerically simulating the normal operational conditions. The influence of operation oxygen content, rate of secondary air, ratio of upper secondary air to lower, diameter of coal particle are studied by single variable method.3. The purpose of experiment for combustion adjustment is not only identify the running state of unit, but also provide advises about reform of unit and improving the operating economy and decreasing the pollution emissions.