FEED-WATER TREATMENT METHOD IN THERMAL POWER PLANT

• Main Authors: AMAMIYA HIDE, INAGAKI SHUICHI
• Format: Patent
• Language: English
• Published: 16.05.1997
• Edition: 6
• Subjects: AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHINBOILERS; BLASTING; CONTROLLING WATER LEVEL; FEED-WATER SUPPLY; HEATING; LIGHTING; MECHANICAL ENGINEERING; METHODS OF STEAM GENERATION; PREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER; STEAM BOILERS; STEAM GENERATION; WEAPONS

PROBLEM TO BE SOLVED: To prevent breakage of a boiler heat exchanger tube, and prevent development of pitting corrosion in turbine members, corrosion fatigue fracture and stress corrosion cracking by injecting deoxygenation agent in the steam in a low temperature turbine. SOLUTION: Ammonia and oxygen is injected from a condensing and demineralizing equipment outlet oxygen pouring from line 15 at an outlet part of a condensing and demineralizing equipment 7. The oxygen poured in the demineralizing system is removed out of the system by a deaerator 10, and oxygen is again injected into the feed-water at an outlet part of a water storage tank 12 of the deaeration from a deaerator outlet oxygen injecting line 16. A deoxygenation agent spray line 18 having a deoxygenation agent spray pump 17 is connected to a turbine stage part of one stage before in which the wet steam of a low pressure turbine 4 is obtained. Hydrazine which is the deoxygenation agent is sprayed into the steam in the low pressure turbine 4 through the spray line 18 while the turbine is in operation so as to be equivalent to the dissolved oxygen concentration at the inlet of the low pressure turbine 4. The spray point is preferably in the temperature range in which the steam temperature is around 200 deg.C.