Biomass fired circulating fluidized bed boiler CFB boiler for short. The CFB(Circulatory Fluidized Bed) combustion technology has been gradually close to the public due to its unique advantages in alternative fuel, disposal of various wastes and environmental protection. The application of this technology to biomass treatment began in the late 1980s, and it has gained considerable scale and certain operating experience abroad.
Coal, oil, natural gas and other fossil fuels have been exploited on a large scale since the 1970s, and their reserves have been sharply reduced. At present, the search for alternative energy sources has aroused wide concern in the whole society. Biomass energy is a kind of renewable energy with abundant sources. It is the world’s fourth-largest source of energy consumption after coal, oil and natural gas.
The development and utilization of biomass fuel has become the consensus of the world. Among many biomass energy conversion technologies, direct combustion is one of the most feasible and efficient ways to utilize biomass resources. Understanding the research and application status of biomass waste combustion in CFB boiler will have very important guiding significance for further recycling and utilization of biomass waste and solving energy problems.
Biomass circulating fluidized bed boiler adopts single boiler barrel, natural circulation mode, generally divided into the front and the tail of two vertical shafts. The front shaft is a general suspension structure, surrounded by membrane water cooling wall composition. From bottom to top, primary air chamber, dense phase area, thin phase area, tail flue duct from top to bottom, high temperature superheater, low temperature superheater, economizer, air preheater. The tail shaft adopts the supporting structure, and the two shafts are connected by the vertical cyclone separator, and the lower part of the separator is connected with the feed back device and the ash cooler. There are anti-wear lining inside the combustor and separator. Tubular furnace wall is used in the front shaft, metal guard plate is used outside and light furnace wall is used in the rear shaft. Eight steel columns bear all the weight of the boiler.
The boiler adopts under bed ignition (oil or gas), fractional combustion, primary air ratio accounts for 50-60%, fly ash circulation is low ratio, medium temperature separation ash discharge adopts dry type, respectively discharged by water-cooled spiral slag discharge machine, ash cooler and dust catcher bucket. The furnace is the key to ensure the full combustion of fuel, the turbulent bed is adopted to make the fluidization velocity in 3.5-4.5m /s, the appropriate furnace section is designed, the thin lining (high aluminum brick) is laid on the furnace membrane wall tube, even when the boiler is burning with different fuels, the combustion efficiency can be maintained above 98-99%.
Energy saving and environmental protection is the problem that each country long-term development priority, circulating fluidized bed boiler is developed based on this, the high reliability, high stability, high availability, the best environmental features and wide fuel adaptability, especially for inferior fuel adaptability, more and more attention, completely suitable to the situation and development advantage.