稼動前ボイラー鋼管のミルスケール除去へのクエン酸の応用とその効果判定のセミミクロ試験法について

Abstract

In earlier work by C. M. Loucks et al. on citric acid cleaning test employed for preoperational mill-scale removal from the boiler tube, a black-iron boiler tube 28 in long and 1/2 in in diameter, was used as test specimen. But as the specimen was uneconomical for the factorial experiment to determine the cleaning condition, a semi-micro specimen prepared by halving length wise a black iron tube, 50mm long and 48-56mm in diameter, was used. Acid cleaning test was carried out by immersing the semi-micro specimen into 3% citric acid hot aq. solution poured and agitated in a 500cc beaker, and the descaling effect was measured by the difference of mean contact electric resistance, before and after the cleaning of the inside walls of each pieces. At the same time, ageing of acid solution was measured by photoelectric photometry. From the statistical analyses of the results of the experiment to determine the cleaning condition, it wes found that the temperature of acid solution was significant for cleaning hours but liquid velocity (agitation) was not always significant.