Experimental Study On NO Reduction By Flue Gas Carrying Char In The Condition Of Layer Combustion

For a long time, China is the world’s largest consumer of coal and boilers.Therefore, there is a large number of emissions of nitrogen oxides causingincreasingly serious environmental problems. Emissions from coal-fired industrialboilers account for a large proportion. However, due to the reasons of difficultboiler renovation, low operation and management level and lack of restrictiveenvironmental regulations, the problems of NOxemission on industrial boilers arenot properly addressed. The technology of flue gas carrying coal char can achievethe purpose of improving combustion efficiency and reduce nitrogen oxideemissions without substantial transformation on boilers. Since most studies on char-NO reaction is used in pulverized coal boilers’ reburn predecessors, its findings arenot necessarily applicable to industrial boilers. Based on the experimental study onlarge size char-phase reduction of NO, the paper provides support to strengthen thetechnical on data, which is important to reduce nitrogen oxide emissions ofindustrial boilers.The paper chooses Shuozhou bituminous coal for the preparation of differentlarge particle char samples in9kinds of pyrolysis conditions under inert atmosphereof horizontal tube furnace and research char properties by industry analysis.Through measuring the pore structure of coal char by mercury instrument, the paperexplore the influence of residence time and pyrolysis temperature on pore sizedistribution. The results show that increasing the residence time at low temperaturesis conducive to increasing the specific surface area and pore volume of char, shortresidence time char at high temperatures help to increase the surface area and porevolume. Then the application of X-ray diffraction analysis is done to discover theeffects of pyrolysis conditions on char microcrystalline structure. The results showthe pyrolysis temperature is conducive for microcrystalline structure to orderlydirection. And using mercury analyzer and scanning electron microscopy incombination to explore the influence of pre-oxidation of the surface morphology ofchar. It is found that char becomes more developed conclusions by getting pre-oxidation of the pore.The paper studies the influence of pyrolysis conditions to heterogeneousreduction reaction of large size char and NO using temperature-programmed method(250~1000℃) on a vertical fixed bed reactor. By adding oxygen to the reactionatmosphere, the paper studies the effect of concentration of oxygenlarge to char-NOreaction at constant temperature. the initial reaction results show that a high oxygenconcentration is better to promote the reaction than hypoxic or anaerobic conditions,and changing the experimental temperature at higher oxygen concentrations has little effect on large size char-NO reaction. After pre-oxidation treatment, thecapability of char reducing NO is been improved. When the pre-oxidation time islonger, the reactivity is better at a certain oxygen concentration. More than the bestpre-oxidation concentration, reactivity of coal chars decreases. This paper alsomakes the coal loading different metal elements by impregnation method. The resultshow that the order of catalytic activity of metal elements is Fe>Cu>K>Na>Ca>Mgry comparising with the char not supported metal.