Heat exchanger with heat deformation absorbing mechanism

b, caaA heat exchange section composed of a fuel supply part; core, and steam collecting part. A heat exchange section composed of the fuel supply part, core and steam collecting part is secured to a side wall plate. Three faces of the heat exchange section except for the side wall plate side, high temperature gas inlet side and outlet side are covered by the housing body. Heat resistant filler, intervenes between the housing body and the heat exchange section. An upper and lower portions of the housing body are prevented from deforming due to thermal expansion of the core by a heat deformation absorbing mechanism which is formed by bending the joint of the flange of the housing body and an upper and lower end portions of the side wall plate.