Abstract: This invention effectively suppresses the corrosion fatigue of a boiler evaporation tube that is associated with repeated stress attributed to the presence of a corrosive environment and scales. This method for suppressing corrosion fatigue of a boiler evaporation tube includes maintaining the dissolved oxygen concentration of the boiler water at 1.0 mg/L or less. Preferably deionized water is used for the boiler water and a scale dispersant is present in the boiler water.

Abstract: The purpose of the present invention is to effectively reduce the corrosion fatigue of an evaporating tube in a boiler which occurs in association with a corrosive environment or repeated application of stress due to the presence of scales. A method for reducing the corrosion fatigue of an evaporating tube in a boiler, in which each of the concentration of chloride ions and the concentration of sulfate ions in the boiler water is managed at 10 mg/L or less. It is preferred to manage each of the concentration of chloride ions and the concentration of sulfate ions in boiler water by subjecting boiler feed water to a desalination treatment with an ion exchange device, a reverse osmosis membrane device or an electrodeionization device or by increasing the collection rate of boiler condensed water.

Abstract: A linear motor driven elevator including in an elevator shaft, a fixed portion, an upper turning portion, and a lower turning portion. An ascending passage and a descending passage are sectionally formed between both turning portions in the fixed portion in a manner that the passages are positioned oppositely. A plurality of cages are accommodated in the passages, the cages being provided with permanent magnets which oppose the linear motor primary coils. Locking mechanisms for selectively locking the cages in position are provided. The turning portions each include a motor driven turn table which rotates the cage about the center axis of the elevator shaft to switch from the ascending to the descending passages and vice versa.