CALCULATION METHOD OF pH VALUE IN BOILER WATER UNDER LOW PHOSPHATE TREATMENT MODE AND APPLICATION THEREOF

The influence of different alkalization agents,i.e.NH3,Na3PO4,and NaOH,in boiler water upon the pH value of boiler water has been analysed,the calculation method for pH value of boiler water under low phosphate treatment mode being given,and the relationship curves between pH value of boiler water and the PO3-4 content in boiler water in different boiler water treatment systems and their typical application being also given.Results of study show that as listed in the following:(1) during the time of calculating the pH value of boiler water,if PO3-4 is less than 2 mg/L,the Na3PO4 can be handled as one-dimentional strong alkaline;(2) under condition of NaOH and Na3PO4 content inboiler water is lower,the effect of ammonia in boiler water upon the pH value is remarkable;(3) the existing on-line monitoring data of steam-water quality,such as feed-water conductivity,PO3-4 in boiler water,as well as proportioning ratio of NaOH and Na3PO4·12H2O in making up the dosage can be substituded into the calculation formula of pH value in boiler water,the pH value of boiler water can be conveniently calculated out,giving effective guidance to pH value control of boiler water,and can judge the accuracy of pH value measurement for boiler water;(4) the relationship curves in defferent boiler water treatment systems are useful to select the suitable boiler water treatment mode.