| 摘要 |
The present invention relates to a heat exchanger (1), in particular a large-sized steam generator, having a conveying structure (11) for conveying a first process fluid (F1) and a plurality of heat-exchange tubes (12), in which a second process fluid (F2) circulates; the tubes (12) have respective substantially plane spiral portions (13) set on top of one another in a number of levels to form a substantially annular tube bundle (14). The tube bundle (14) delimits, inside, a substantially cylindrical central space (29) and, outside and together with a casing (2) housing the tube bundle (14), an annular space (30). The internal central space (29) and the annular space (30) constitute respective ducts for passage of the first process fluid (F1) that traverses the tube bundle (14) radially, whilst the second process fluid (F2) circulates within the spiral portions (13) with a radial component of the velocity locally opposite to that of the first process fluid (F1). |
