Experimental Study On The Effect Of Oxygen Enriched Combustion Atmosphere On The Characteristics Of Ash Deposition

Coal is an important industrial fuel. However, while it's stimulating economic development, it's also polluting the environment. Oxygen enriched combustion is a promising carbon capture technology. Ash deposition during coal combustion is inevitable. It will seriously affect the safety and economy of coal-fired power plant. If oxygen enriched combustion technology were meant to be widely used, the ash deposition characteristics in this atmosphere should be clarified. The forms of mineral in ash have great impact on deposition behavior. The behavior of inorganic minerals and ash deposition formation as well as the research status of it at home and abroad are reviewed in this paper. Due to its complexity, the ash deposition mechanism, especially under oxygen enriched condition is still unclear.Shenhua coal was selected as the research object. Raw coal and low temperature ash were subjected to CCSEM, XRD and TG/DSC analysis in order to study the mineral species content and mineral transformations undergo in air and oxygen enriched atmosphere. The results indicate that the Fe in Shenhua coal are mainly exist in the form of siderite, Ca are mainly exist in the form of calcite. In air combustion, calcite decomposed completely before 800?, which will take much longer in oxygen enriched combustion condition. The ash fusion point analysis show lower ST under oxygen enriched condition. A thoroughly experiment was carried out in six atmosphere using flat flame entrained flow reactor. The results show in oxygen enriched atmosphere there will be more CaCO3 and CaSO4, which will promote the low AFT glass phase mineral generation, together with their strong adhesivity, the deposition potential will be stronger. The lower percentage of crystal phase Fe2O3, the more small particles and adhesive white floc adhere to the surface of large particles, the larger amount of submicron particles, all attributes to the fact that the deposition potential is stronger in oxygen enriched atmosphere. With the increase of oxygen concentration, the extend of particle breakage and melting will be greater.Selecte Colstrip mine, Prairie eagle, Zhundong coal as experimental object to investigate whether oxygen enriched atmosphere has a similar effect on other coal besides Shenhua coal. With the help of TG/DSC test, we know the oxygen enriched combustion process is slower than that of air combustion in varying degrees, and the wight loss is less because the fixation of SO2 and CO2. The last experiment was conducted in DTF in four different atmospheres. The result show under the same oxygen concentration, the melting degree is higher in air combustion than in oxyfuel enriched combustion. Nevertheless, the presence of more CaCO3 and CaSO4 will enhance the deposit potential in oxygen enriched atmosphere. The characteristics of iron minerals in distinct forms reacting to different atmosphere are variable, which depends on the specific atmosphere and phase.