Feedwater preheater with two steam chambers

Feedwater preheater for heating feedwater in the form of steam turbine condensate by means of condensing extraction steam from a turbine, comprising a casing containing an outer steam chamber, a fixed tube plate and a movable tube plate disposed opposite one another in the casing, feedwater inlet and outlet chambers located adjacent said fixed tube plate, a feedwater reversing chamber disposed in said casing and partly defined by said movable tube plate, a first group of rectilinear feedwater conducting tubes connected at one end thereof through said fixed tube plate to said feedwater inlet chamber and at the other end through a first part of said movable tube plate to said reversing chamber, a second group of rectilinear tubes connected at one end thereof through a second part of said movable tube plate to said reversing chamber and at the other end thereof through said fixed tube plate to said feedwater outlet chamber, a steam vessel disposed in said casing and surrounding said second group of tubes, said steam vessel being closed against communication with said outer steam chamber and being rigidly connected to said second part, said first part of said movable tube plate extending freely beyond the connection of said steam vessel to said second part of said movable tube plate, said first group of tubes, on the one hand, and said second group of tubes, on the other hand, being substantially parallel to and coextensive with one another being mutually spaced apart a given distance so as to permit tipping and deformation of said movable tube plate within given limits in response to stresses producible therein by varying thermal expansion of the tubes of said first and second groups thereof.