METHOD FOR OPERATING HARD WATER-SOFTENING APPARATUS, AND HARD WATER-SOFTENING APPARATUS

摘要

PROBLEM TO BE SOLVED: To make soft water of high purity sufficiently reduced in hardness leakage quantity by almost perfectly regenerating an outlet region.SOLUTION: The hard water-softening method includes a water softening process for making soft water W2 by passing raw water W1 through a cation exchange resin bed 311 having a depth D1 of 300-1,500 mm and a ratio of depth D1 to diameter Z of 1.8-3 with a downward flow, and a regeneration process for distributing a regeneration solution W3 from both sides of the top part 321 and bottom part 322 of the cation exchange resin bed 311 to collect a solution at an intermediate part 323 to generate a counter flow of the regeneration solution W3 to regenerate the whole cation exchange resin bed 311. In the regeneration process, an amount of regeneration solution is supplied to a hardness leakage preventing bed 313, of which the depth D2 is set to 100 mm on the basis of the bottom part 322 of the cation exchange resin bed 311 so that the regeneration level becomes at least 1-6 eq/L-R. In a water softening process after the regeneration process, hard water of which the electric conductivity is 150 mS/m or below and the total hardness is 500 mgCaCO/L or below is supplied.