Feedwater heater

Abstract

A horizontal feedwater heater for use in heat power stations, of the type having a shell, a plurality of U-bent heat transfer tubes extended in the longitudinal direction of the shell and a vent tube extended in the longitudinal direction of the shell substantially at the center of the latter and adapted for extracting and discharging non-condensed gas. The feedwater heater has a baffle disposed at each side of the vent tube and having a horizontal plate portion extended horizontally from the vent tube and an inclined plate portion inclined downwardly from the end of the horizontal plate portion at an obtuse angle to the latter. The length of projection of the baffle from the vent tube is varied along the length of the shell in accordance with the ratio of amount of heat exchanged between the steam and feedwater in each axial section of the tube nest connected to the water inlet to the amount of heat exchanged between these fluids in the corresponding tube nest section of the feedwater outlet side, thereby to permit an efficient extraction of the non-condensed gas. The structural members connectable with the heating steam is made from a low alloy steel containing more than 1% of Cr to exhibit a high corrosion resistance.