Analysis Of Effects Of Different Refractory Belt Arrangements On The Boiler Combustion

Coal is the most widely used conventional energy in china, occupying up to 93.8% of total fossil energy. According to the report, the worldwide proved reserves of coal are capable of providing human energy supply for more than 200 years. However, the inferior coal accounts for more than half of the reserve. As an important non-renewable energy, stable, efficient and low pollution combustion of inferior coal has been one of the most positively researched directions.Among all the methods for stabilizing the combustion of inferior coal, refractory belt is most widely used. Burning low volatile anthracite in the furnace without arranging burner band. Low combustion temperature and instability, leading to the incomplete combustion of fly ash and the increasing of slag carbon content. In particular, when the design heat load is low or heating surface is mismatched, superheater and reheater steam temperature is low, which affect the economy of generating unit and the turbine running safety. Laying in the hearth of burner band can be isolated from the local water wall and fire, the heat exchange between the approximate adiabatic effect, improving furnace temperature and combustion stability, reducing the carbon content of fly ash and slag, raising the prey flushing inlet flue gas temperature of the superheater and reheater tube bundle area, improving the main steam temperature to the design value, to maintain the design of the unit under the corresponding load of output.Refractory belt arrangement is not fixed, there are many ways to arrange it. Traditionally, the general layout in water-cooled wall near the burner, is in the main combustion zone, can effectively improve the area temperature, for the flame retardant of inferior coal and has good steady combustion effect. And in the region of the non-traditional decorate burner band of boiler furnace parameters influence each are not identical.The designed coal for a certain 300 MW coal burning boiler in Hu Nan is He Nan meager-lean coal with low volatile and some bituminous coal is blended to stabilize the combustion in actual operation, causing an unexpected high temperature that leads to a severe coking phenomenon in furnace. The improper way of setting refractory-belt in the main combustion zone is considered to be the primary cause. Aiming at this issue, the feasible layer and area for arranging the refractory-belt is discussed, and the zone above burner is supposed to be appropriate for deploying the refractory-belt, and the area is calculated through Thermodynamic Calculation. A three-dimensional numerical simulation is established to analyze the influence of refractory-belt layer and area on the layer surface coking and boiler combustion efficiency. Data demonstrates that after modification the coking phenomenon is largely weakened and the combustion efficiency is satisfactory. Furthermore, a raynger 3I type furnace infrared thermometer is utilized to collect the main combustion zone temperature and some related data to measure the boiler efficiency. The actual operation data shows that the numerical simulation is in accordance with the realistic combustion and the modification of refractory-belt is successful...