Of the multi-tube once-through boiler feedwater control device

摘要

PURPOSE: To maintain the dryness of steam within a certain range by providing a steam-dryness detector and by controlling feedwater on the basis of the dryness of the steam and prolong the life span of a boiler by preventing the overheat of heating tubes. ;CONSTITUTION: In a shell and tube type once-through boiler, a feedwater pump 8 is driven when a waterlevel at the inside of heating tubes in a boiler body 1 is lower than a normal level, which is between a maximum waterlevel A and a minimum waterlevel B. The feedwater is introduced into the heating tubes 3 through a lower header 5 in the boiler body 1 and is evaporated by the combustion heating of a burner 6, following which it is discharged from an upper header 4 through a steam separator 10 and a steam pipe 13. In this case, a steam-dryness detector 23 is provided on the steam pipe 13 and on the basis of the result of the determination of the dryness of steam, an indicating signal for the operation and stoppage of the feedwater pump 8 transmitted from a determining device 24 therefor is outputted to a feedwater pump- operating device 22 through a transferring device 27. This transferring device 27 is transferred by a transfer-actuating device 28 on the basis of outputs from a steam- pressure detector 29 and a combustion indicator 31.;COPYRIGHT: (C)1994,JPO&Japio