PURPOSE: To evade the instability of burning before the rated operation, by making the air ratio of a sub-burner greater than that of the rated operation until the load reaches about 1/4, and effecting the rated operation while the load is about 1/4 to 1/3.
CONSTITUTION: In the low NoX boiler which is provided from the lower to the upper part in its furnace side wall with a main burner for somewhat incomplete combustion zone, the sub-burner having a lower air ratio than the former and an after burner having an air ratio 1 or more, until the load is 0 W about 1/4, the fuel feeding ratio to the main burner and the sub-burner is kept at the ratio of the rated operation with the air ratio being about 0.9, and until the load is 1/4W1/3, the air ratio of the sub-burner is reduced to 0.5W0.7, during this period the air ratio of the after burner is made approximately steady, and until the load is 1/3Wthe rated load, the number of sets of operated main burners and sub-burners is increased according to the load to effect finally the rated operation. When it is desired to stop, the above starting procedure is reversed.
OKIURA KUNIO
MORITA SHIGEKI
KAWAGUCHI YOSHITO
