Experimental Study of Chemical De-scaling-I: Effect of Acid Concentration

Chemical cleaning is employed frequently for de-scaling exchangers in combination with other cleaning methods. a customized chemical solution is circulated through the scaled apparatus for certain time following drainage and washing. many cycles of cleaning may be necessary to reach satisfactory de-scaling level. the composition of the cleaning liquor is very important for efficient de-scaling. the scale from an industrial boiler is treated with four different acid solutions at five different strengths to study their dissolving effect on the scale/deposits in the tubes of the boilers. results reveal that 5% solution of hcl is the most effective to dissolve the scale in a specified time at room temperature. sulfuric acid shows very poor de-scaling properties under the test conditions. the order of effectiveness to dissolve the scale deposits is hcl > hno3> hcooh> h2so4. hydrochloric acid may provide 30-50% savings on the circulation time as compared to hno3 based on the rate of dissolution.