Through analysis of the fouling substances on different parts of the gas-gas heater (GGH) in wet flue gas desulphurization system

it is clear that the main components of fouling substances leading to blockage of GGH are CaSO4

CaSO4·2H2O

and compounts of silica.After large amount of tests and studies in the laboratory

the effective cleaning medium for eliminating fouling substances by using chemical method has been choised

and the damage degree of chemical medium to the heat-exchanging plates in GGH being evaluated.Through pilot test

the chemical cleaning medium and the cleaning process have been detemined.Results of application show that the used chemical cleaning medium and technological process are safe and effective

the emamel on heat-exchanging plates can't be damaged during disposal of fouling substances from GGH.