Change of Boiler Water Quality by Mixing of Sea Water--Possibility of automatic control of water quality in marine auxiliary boilers by monitoring pH and electric conductivity--

摘要

For the water quality control of marine boiler, it is very important to investigate the effects of sea water mixing on the characteristics of boiler water quality such as pH, concentrations of phosphate ion PO_4~(3-), chloride ion Cl~-, and electric conductivity EC. At first, the paper investigates theoretically the change of pH, that is, molarity of hydroxyl [OH~-], PO4~(3-) concentration and EC due to mixing of sea water into boiler water in consideration of the chemical reactions between scale components and phosphate/alkali type of water treatment chemicals. According to the results of this investigation, the paper proposes a method of automatic water quality control. Secondly, the paper carries out an experimental study with an actual boiler in order to confirm the validity of the above theoretical results. Finally, the paper describes some problems regarding the automatic marine boiler water treatment which has been revealed by experiments.