The Study On Superfine Pulverized Coal Reburning For NO_x Reduction

With the global continued increase of fossil fuel consumption, the problem of NO_x emission control has caused widespread concern of the world. As most energy needed in China has been coal for a long period, and the energy structure will last in the future, coal burning is the main cause of NO_x emissions, which pollutes the environment heavily in our country. To control NO_x emission, one of the most valid methods is reburning technology, which reduces the NO_x formed in primary burning zone by the deoxidized atmosphere in reburning zone. The technology is a promising method for its lower cost, easier realization and higher NO_x reduction efficiency, due to the reburning fuel being able the same as the primary one.Though investigating the specific problems about NO_x reduction in superfine pulverized coal reburning process by means of thermal tests, simulations and theoretical analyses, the thesis is to reveal the mechanism of NO_x reduction, get the basic data of burning characteristics of superfine pulverized coal in reburning process and the effects of NO_x reduction for superfine pulverized coal reburning under various burning conditions, and farthest improve the reduction efficiency of NO_x with good combustion efficiency.Firstly, based on the formation and reduction mechanism of NO_x, the reduction mechanism of homogenous phrase and heterogeneous phrase is discussed. A simplified chemical dynamic reaction model of NO_x reduction process of superfine pulverized coal reburning is established by means of sensitive analysis, and the main reaction mechanism is found for the process.By using thermogravimetry, the volatile releasing behavior is investigated separately when pulverized coal pyrolyzed in the deoxidized atmosphere. The releasing behavior of CmHn component of pulverized coal pyrolyzed under reburning condition is investigated innovatively by means of gas chromatography and tube heater. The effects of pyrogenation temperature, fuel characteristics and coal particulate size on pyrogenation behavior of pulverized coal in reburning zone are obtained for the first time. The fundamental reasons are found for increase reduction efficiency of NO_x when superfine pulverized coal used as reburning fuel.The ignition and burnout characteristics of superfine pulverized coal reburning are experimentally studied firstly under the condition of rapid pyrogenation in a thermal pulverized coal furnace. And in order to provide design basis for reasonably distributing...