To maintain operation until renovating of an air separator, by using raw air which is supplied to a device as alternate gas for oxygen and nitrogen during returning the device to the normal condition, when a plant stops due to the concentration decrease of oxygen gas generated by an air separator or device abnormality.
Raw air 1 from atmosphere is supplied to an adsorption tower 4 through a filter 42, an air compressor 2, and a water washable cooling tower 3, and moisture and carbon dioxide are separately removed by adsorption agent. At this time, setting value of oxygen concentration is judged using data sent from an oxygen concentration meter 61, when oxygen concentration of the oxygen concentration meter 61 is less than 90% or the meter stops at the moment, interrupting valves 34, 58 in connection tubes 37, 59 are opened, and interrupting valves 35, 60, 31 are closed. Therefore, raw air 1 is directly lead to a nitrogen compressor 6 and an oxygen compressor 7 to be compressed, the air from the nitrogen compressor 6 is sent to a mixer 48 through a circulation line 41 and mixed with powdered coal 49, and air from the oxygen compressor 7 is supplied to a coal burner 50.
SATO YOSHIO
KOYAMA SHUNTARO
MORIHARA ATSUSHI
KISO FUMIHIKO
AKIYAMA TORU
KATAGIRI YUKINORI
FUKUHARA HIROSHI
BABCOCK HITACHI KK
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