What Are CFB Boiler Return Feeder Coking Reasons
Return feeder is an important part of circulating fluidized bed boiler, once it produces coking, the material reverting will abort, boiler output is reduced and even badly affects boiler safe, stable operating. To know the reason why CFB boiler return feeder coking can do much help in reducing accidents.
1.Over-temperature combustion chamber. Hot separator operating temperature and combustion chamber temperature are close to each other, or even higher than the combustion temperature. When the combustion chamber is running, then cycle ash temperature that entered into cyclone separator can easily exceed ash deformation temperature, resulting in coking.
2.Return feeding system leakage. Under normal conditions return feed system should have no air leakage, less flue gas oxygen content in boiler cyclone, moving at a constant speed and circulating ash residence time is short, therefore not enough to cause the cycle ash combustion, whereas, leakage is easy to cause circulating ash combustion and coking.
3.High carbon content in fly ash. if poor combustion when boiler ignition, or bad match between stroke volume and combustion fuel size, or hard burning gangue, anthracite coal, for their less volatile, powder quantity, high ignition temperature, slow combustion and other reasons can lead to excessive fine carbon particles into the cyclone separator and increase carbon content in ash, causing secondary combustion and coking.
4.Small circulating ash amount. Less ash leads to too slowly moving in loop material return system, almost static, easy to cause coking, meanwhile, less ash makes flue gas carrying coal particle into return feeder easier, and leads to coking.
Circulating fluidized bed steam boiler manufacturer
ZG Boiler developed the fourth generation SHX series CFB steam boiler, combustion chamber and cyclone separator are composed by membrane water cooled wall, which can absorb the inside heat, allow residue carbon in flue gas to continuously burn, and no coking will cause. Anyone has interested in the high efficiency boiler, welcome to consult online or email to zg@zzboiler.com !
