Combustion Characteristics Test. Oxygen-rich Environment

The variety of the oxygen concentration will make the great influence to the coal combustion. The enhance of the oxygen concentration is able to reduce ignition heat , ignition-temperature and increase reaction velocity , flame temperature which will promote combustion completely. At the present time, oil was used to fire or combustion supporting in the pulverized coal fired boiler of fuel electric plant in the world by and large. If the oxygen-enriched air (high oxygen concentration air) be used to support combustion can stead the oil in the power plants, the economic benefits will be quite good.The paper choose the different coal samples from brown coal to dry-burning coal and make the oxygen-enrichment combustion tests in the Drop tube furnace and the thermogravimetric apparatus.During D-furnace experiments the ignition-temperature decreases with the oxygen concentration increasing. Low volatile dry-burning coal is the most acutest to the oxygen concentrate. Oxygen concentration increased from 16% to 36%, The ignition-temperature decreased 24%, decreasing by 147℃. Kaliena coal's ignition-temperature has a little change with oxygen concentrate, decreasing by 36℃. Because of it's low ignition-temperature, the decrease reach 12%. The trend of 4 bituminites are between one of brown coal and dry-burning coal, ignition-temperature decreased 15% or so, 60～100℃. And the decreasing velocity of the bituminites' ignition-temperature become lower after the oxygen concentration reach 26%. The little difference occur among bituminites. For coal concentrate experiment, We find oxygen-enriched weaken the effect of coal concentrate on ignition-temperature. Coal dimension has a weak effect on ignition-temperature under different oxygen concentrate.In thermogravimetric apparatus, the Timax of all the coals decrease with oxygen concentrates increasing. About 50℃, the rate is 10%. With the increasing of oxygen concentration, the character of ignition turn better: TG curve move left and turn steeper.The paper also analyse the effect of oxygen concentrate on reaction velocity; burnout efficiency and release of SO₂ and NOx. There is exponential relation between Coal reaction velocity and oxygen concentrate. The higher oxygen concentrate promotes burnout efficiency especially for the coals, which is difficult to burn, increasing 11% in burnout efficiency. Higher oxygen concentrate must not increase the release of SO₂ and NOx, under a appropriate excess air rate, there being low release of SO₂ and NOx.