Experiment and Numerical Simulation of NOx Reduction by Natural Gas Reburning

NOx emission from the coal burning is one of the major pollutant sources for atmosphere, and it is a threat to environment, climate and human health. The pollutant problem of NOx emission becomes more and more serious with coal fired boilers increasing. Many scholars begin to research the forming and destroying mechanism of NOx for resolving the problem of NOx emission from coal fired boilers in power plants, and a good many NOx controlling methods are invented such as Low-NOx Burners, Air Staging, Fuel Reburning, Flue Gas Recirculation, Selective Catalytic Reduction and Selective Noncatalytic Reduction. Therefinto, Natural Gas Reburning (NGR) has the advantage of lower investment, low operating expenses and high NOx reduction efficiency. It has very important value of engineering application for reducing NOx emission with Natural Gas Reburning.Now, NGR technology have been proven to be an available technology by all industrial demonstrations in USA and Europe, but the critical technologies haven’t been openly reported and the systemic research hasn’t been found. So, before applied NGR technology to pulverized coal boilers in China, the systemic research must been carried for mastering the critical technologies and industrial demonstrating. Using the typical tangentially fired boilers in China as researching object, numerical and experimental investigation on NGR technology for NOx reduction, to explore and understand the mixing characteristic, burning characteristic and to exploit the industrial equipments, all of which will enrich and promote the academic researches and carry forward the technological innovations and engineering applications of NGR technology.This paper is in allusion to the development and actuality reburning technologies of coal fired boilers in china and foreign countries. It is firstly to more deeply investigate the critical influencing factors on reducing NOx emission of tangentially coal fired boilers with NGR technology combined numerical and experimental methods. The mixing mechanism of the reburning injection in furnace was emphasis in this paper, and the methods on oppositely injecting reburning gas and over firing air (OFA) in the front and rear walls in tangentially coal fired boiler is the firstly brought forward, which can strengthen the gas flow mixing in furnace and reducing the gas flow swirling remains at the furnace outlet.The researches include the cold experimental and numerical studies on mixing