Overview: boiler blowdown can be divided into continuous blowdown and regular blowdown:

1. Continuous blowdown is to discharge the boiler blowdown continuously from the part of the boiler drum water with biggest concentration, the purpose is to avoid that the boiler water salinity is too high and the steam quality is affected, and in order to discharge the fine particles or suspending water slags in boiler water. The opening and closing as well as the adjusting for continuous blowdown shall be determined by the chemical personnel, who shall also inform the boiler person to operate. 

2. Regular blowdown is to discharge part of the boiler water from the lowest point ( the lower header)  of the boiler circulation system regularly. Its purpose is to remove the water slag and corrosion products in bottom of boiler and to adjust the quality of boiler water. The periodic blowdown of boiler shall be done by the boiler personnel and shall be supervised by  the chemical personnel at site.