| 摘要 |
<P>PROBLEM TO BE SOLVED: To allow a chemical oxygen demand of boiler water to be suppressed to 30 mg/L or less that is one of environmental standards on an effluent while suppressing generation of scale in a steam boiler. <P>SOLUTION: Steam is generated by heating the boiler water in the steam boiler 20 while supplying supply water whose hardness is controlled to be 5 mgCaO<SB POS="POST">3</SB>/L or less to a steam boiler 20 by a water softening apparatus 52 through a water supply pathway 41 and while properly discharging part of the boiler water through a blow pathway 26. Also, agent aqueous solution containing alkali metal silicate, alkali metal hydroxide and ethylenediaminetetraacetic acid as the scale suppression agent is supplied to the supply water from an agent supply device 60 so that the concentration of the scale suppression agent may be at least 1.5 mol times equivalent to the hardness of the supply water. The boiler water controls the concentration multiplication so that the concentration of the scale suppression agent may be 40 mgEDTA/L or less by controlling the discharge of the boiler water from a flow pathway 26. <P>COPYRIGHT: (C)2012,JPO&INPIT |
