| 摘要 |
PROBLEM TO BE SOLVED: To prevent the lowering of heat transfer performance and the corrosion of a heat exchanger tube material by blocking adhesion of an ammonia sulfate based substance to a waste heat recovery heat exchanger without posing a problem in heat transfer performance and profitability. SOLUTION: In equipment for recovering waste heat at a gas fired thermal power plant, an alkali water spray device 27 is installed to spray an alkaline aqueous solution to a heat exchanger tube 25 of heaters 7 and 10. The pH of the alkaline solution to be sprayed to the heat exchanger tube 25 is set at 9 or more. Alkali species herein used are carbonates (Na2 CO3 , K2 CO3 , MgCO3 ) or phosphates (Na3 PO4 , Na2 HPO4 , K3 PO4 ) and the concentration thereof is set according to the amount of ammonia sulfate based compound attached. An exhaust gas bypass duct and a removing recovery device for the ammonia sulfate based compound are installed on the back wash side of an exhaust gas of a denitration device 14. A catalyst which is treated in a gas atmosphere containing 20ppm or less of NH3 and 5-20% of water is used in the denitration device 14. |
