Premium
A study of phosphate hide‐out from boiling water
Author(s) -
Balakrishnan P. V.
Publication year - 1977
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.5450550517
Subject(s) - boiler (water heating) , boiling , phosphate , corrosion , boiler water , chemistry , boiler feedwater , sodium , materials science , metallurgy , chemical engineering , waste management , engineering , organic chemistry
Sodium phosphates deposit on heat transfer surfaces from boiling solutions. This process of deposition, which is termed “hide‐out”, was studied in a recirculating loop operating at the temperature and pressure of the secondary system in CANDU‐PHW* steam generators. The relation between the compositions of the deposit and solution, is in agreement with studies by others. An additional depletion of phosphate was found, which probably related to reaction with corrosion product deposits on the loop surfaces. The observations from this study suggested a maximum desirable range for Na/PO 4 molar ratio in solution of 2.2 to 2.6 for phosphate treatment of steam generator water. Lithium phosphate treatment is unsuitable because it forms hard scales and also causes accelerated corrosion of boiler tubing.