Study Of Superfine Pulverized Coal Pyrolysis And NOx Emission Mechanism In Combustion

China as the biggest energy consumption country is facing threats from energy resources shortage and environment pollution. Coal is one of the most important fossil fuel, which occupies 66.7% in China’s primary energy consumption in 2013 according to the data from China’s National Bureau of Statistics. However, burning of coal produces a lot of pollutants such as NOx, SOx, etc. Thus, the development of clean coal combustion technology has become an urgent demand.The staged combustion of superfine pulverized coal reburning technology is one of the most efficient low NOx combustion technologies, both in pollutants’ emission control and the improvement of combustion efficiency, with lower ignition temperature and higher burn-off rate. Among the low NOx combustion technologies, staged combustion reburning technology is an effective comprehensive control of NOx formation. The fuel goes through into the main combustion zone, reburning zone and burned out zone- 3 levels for combustion. The majority of coal is burned in the main combustion zone, and the rest small part of coal is injected into the reburning zone which helps to create a reducing atmosphere by controlling the concentration of O2. Thus the NOx from main combustion is reduced and finally the unburned coal is burned out in the burn-out zone. Domestic research of superfine pulverized coal combustion technology starts from late 90 s last century, but most of the researches were focused on industrial fields, the study of pyrolysis& combustion mechanism is not deep or intensive. This article studied the mechanism of superfine pulverized coal pyrolysis& combustion, combined with industrial-scale experiments on drop-tube furnace boiler to research the pyrolysis& combustion mechanism and NOx emission characteristics of superfine pulverized coal. Finally the article studied melting characteristics of superfine pulverized coal ash, together supplied theoretical foundations for industrial application.The author studied the pyrolysis& combustion characteristics of superfine pulverized coal through TG-DSC tests by using thermobalance, studied the emission mechanism of gases during pyrolysis through TG-FTIR tests. Influences of particle sizes, pyrolysis atmosphere and heating rates to superfine pulverized coal pyrolysis process were researched. The combustion tests were conducted both on a thermobalance and a drop-tube furnace boiler to study the combustion and NOx emission mechanism. Finally the influences of particle sizes and pyrolysis atmosphere to pyrolysis process of superfine pulverized coal ash were researched; the ash samples’ components were analyzed by using XRF. Results showed staged combustion& reburning technology of superfine pulverized coal could effectively improve coal combustion process.