Abstract
The deoxygenation of boiler water by malto-oligosaccharide (MO) was studied in the range of NG values from 1 to 13.9 as a function of the number of glucose units NG, constituting MO. Phosphate was always added to MO as an indicator. The amount of P-alkalinity of boiler water decreased with NG, reached a minimum at NG=5.9, and then increased with NG. It corresponds to the fact that the amount of mono-carboxylic acids produced by the reaction reach a maximum at NG=5.9. The amount of (free) phosphate inos released from MO, rp, decreased with an increase in NG, reached a minimum value of 72% at NG=5.9, and then increased up to nearly 100% at NG=13.9. Diacethyl (CH3COCOCH3) having odor was produced in the reaction. The evolution amount of the diacethyl increased with NG, and had the maximum value at NG=2. This amount decreased with the NG over NG=2, and then reached a constant small value at NG=5.9.
From these results, it was found that the MO with NG=13.9 is superior for the oxygen scavenger.
