What are the advantages and disadvantages of circulating fluidized bed boilers?

1) Wide fuel adaptability. Circulating fluidized bed boiler can burn both high quality coal and poor quality fuel. A large number of circulating fluidized bed boilers have been put into operation at home and abroad using coal gangue, coal sludge, oil shale, petroleum coke, slag, bark, waste wood, sludge, garbage and other special fuels;

2) Stable and efficient combustion. Thanks to the presence of a large amount of high-temperature materials, the fuel is rapidly heated to above the ignition temperature after entering the furnace chamber. Since the amount of fuel is very small compared with the amount of high-temperature materials, circulating fluidized bed boilers do not have the problems of fire extinguishing and unstable combustion. And most of the unburned fuel can be circulated many times through the cyclone separator, with long residence time and high combustion efficiency;

3) Superior environmental performance. Circulating fluidized bed boiler by adding limestone furnace desulfurization can significantly reduce the concentration of flue gas sulfur dioxide emissions, the original emissions of nitrogen oxides is also lower than that of pulverized coal boilers. Circulating fluidized bed boiler cyclone separator area temperature is particularly suitable for SNCR denitration process, sprayed into the reducing agent such as urea solution or ammonia can obtain 60%-85% denitrification efficiency (SNCR denitrification process for pulverized coal boilers denitrification efficiency is generally about 40%), without the use of expensive SCR denitrification process;

4) Simple fuel preparation system. The coal feed particles are 0~13mm or 0~8mm wide sieve, no coal grinding system, which is greatly simplified compared with pulverized coal boiler;

5) Good load regulation performance. The load adjustment range of circulating fluidized bed boiler can reach 4:1, and the load adjustment speed can reach 5~8% BMCR/min. Under normal conditions, circulating fluidized bed boilers do not need to put oil to boost combustion in their operating range. Circulating fluidized bed boiler is easy to achieve pressure fire hot standby, warm state start oil consumption is very small, hot state start even without oil;

6) The local area of the furnace chamber heating surface is easy to wear. Circulating fluidized bed furnace gas-solid fluid characteristics of the impact, coupled with the main combustion of high ash poor quality coal, circulating fluidized bed boiler furnace heating surface local wear phenomenon, the need to take the necessary technical measures in the design and manufacture, operation and maintenance to ensure long-cycle operation. In recent years, with the development of technology, many circulating fluidized bed boilers have been able to achieve 8 to 10 months of continuous reliable operation;

7) High energy consumption level of the unit. Circulating fluidized bed boiler due to the presence of large resistance components such as cloth wind plate, cyclone separator, especially the need for high wind pressure to support the fluidization of the bed material, flue gas resistance is relatively high compared to pulverized coal boilers; at the same time, many circulating fluidized bed boiler power plant fan selection margin is large, the plant electricity rate is high, there is room for improvement; but the circulating fluidized bed boiler fuel adaptability, can burn the advantages of low calorific value coal is the pulverized coal furnace can not The circulating fluidized bed boiler fuel calorific value is generally lower than that of pulverized coal boiler 4~6MJ/kg, which affects boiler efficiency 1~3%;

8) The level of automation control is required to be higher. Compared with conventional pulverized coal boiler, circulating fluidized bed boiler combustion automatic control requirements than the same level of pulverized coal furnace.