After analysis on the desulphurization system

the serious blockage of spraying layer due to long-term out of service which making the deposition inside the tube gradually turn to hard scale

leakage of the original flue gas

SO2 concentration at the inlet of the desulphurization system is larger than the designed value

and the over coarse limestone slurry particle were considered as the major causes.Thus

for short time shutdown of the desulphurization system

it is better to wash the deposition inside the sprayer by using process water and keep the residue wet;while after long time shutdown

it is better to cut the spraying mother tube for inspecting and clearing the internal deposition

to prevent the spraying layer from blocking;it is better to regulate the operation condition of slurry making system

to ensure the limestone slurry particle size is qualified.