A HEAT EXCHANGER

摘要

A heat exchanger comprising a pressure vessel (1). A plurality of serpentine s (8) convey a fluid to be heated through the pressure vessel (1) in one direction. A duct (9) surrounding the serpentines (8) conveys a second fluid in the opposite direction to give up its heat to the first fluid. The duct ( 9) is spaced from the pressure vessel (1) and is surrounded with thermal insulation (23). An opening in the duct (9) equalises the pressure between t he inside and the outside of the duct (9) which is also supported against expansion caused by the pressure inside the duct (9) exceeding the pressure outside the duct (9).