MULTIPLE COOLED SUPPORTS FOR HEAT EXCHANGE TUBES IN HEAT EXCHANGER

A heat exchanger (108) includes a casing (140) configured to direct a working fluid (142, 144) therethrough, and at least one heat exchanger (HE) section (168) in the casing (140). Each HE section (168) includes a pair of spaced supports (170). The spaced supports (170) include: an upstream support (172U) and a downstream support (172D) with at least one of them including a coolant carrying body (182) configured to direct a coolant (184) therethrough. A first cross-support (174) couples to and extends between respective upstream and downstream supports (172U, 172D); and at least one second cross-support (176) couples to and extends between the respective upstream and downstream supports (172U, 172D). Cross-supports (174) are vertically distanced from adjacent cross-supports (174). A plurality of tube positioners (180) coupled to each cross-support (174) position a plurality of heat exchange tubes (146) extending across a working fluid path (164) through the casing (140). The segmented support of the tube positioners (180) and the cooling of the cross-supports (174) allows ferritic material to be used for once-through, duct-fired HRSGs (148).