DEVICE AND METHOD FOR CONTROLLING PRIMARY DRAFT FAN FOR PULVERIZED COAL COMBUSTION BOILER

摘要

PROBLEM TO BE SOLVED: To continue safe operation without damaging a primary draft fan by preventing the rapid draft increase of a primary draft fan outlet pressure during trip or stop action of a coal pulverizer under operation. SOLUTION: A primary draft fan control device for a pulverized coal combustion boiler is formed such that a pulverized coal combustion boiler has a plurality of coal pulverizers and a primary draft fan control device has a primary blower 42 for the coal pulverizer provided in common to a plurality of the coal pulverizers. The opening of a moving blade 41 of the primary draft fan is regulated based on a detecting signal for the outlet pressure of the primary draft fan 42 and a coal flow rate signal and a primary draft fan outlet pressure is controlled to a specified pressure. During a trip or a stop of the coal pulverizer, a primary draft fan moving blade is throttled at a high speed based on a variation value of a coal flow rate signal occasioned by the trip or the stop and a rate of change limiter 11 is provided to release the moving blade 41 from throttling at a timing matched with restoration of the primary draft fan outlet pressure.