HEAT EXCHANGE APPARATUS AND PROCESS

摘要

Heat exchange apparatus and process, particularly heat exchange primary reforming with the primary reformed gas being subjected to partial combustion (and optionally secondary reforming) and the resultant partially combusted gas being used as the heat exchange medium to supply heat required for the primary reforming. The apparatus includes process fluid inlet (11) and outlet (14) zones separated from the heat exchange zone (13) by boundary means such as tube sheets (15, 16, 17) or header pipes (35). A plurality of heat exchange tubes (19) for a process fluid extending through a heat exchange zone (13) from one of the boundary means (15, 16) and slideably engage at the other boundary means (17) with seal tubes (26) fastened to said other boundary means (17). The interior of the inner one of the seal tube (26) and its associated heat exchange tube (19) is provided with a constriction (31) of reduced cross-sectional area forming a low pressure region (32) downstream of said constriction, an expansion region (33) of cross-sectional area greater than that of the constriction (31) downstream of said constriction, and one or more passages (34) through the wall of that inner tube connecting said low pressure region to the exterior of the inner tube. The passages (34) are located within the overlapping region of the seal tube (26) and heat exchange tube (19) so as to provide a leakage flow path for heat exchange medium from the heat exchange zone, through the overlapping region and said passages, into the low pressure region.