DOUBLE-ZONE SHELL AND TUBE EQUIPMENT, RELATED PLANT CONTAINING SAID EQUIPMENT AND PROCESS FOR PRODUCING A CHEMICAL IN SAID PLANT

Equipment (1A) comprising: a first and a second tube plate (6 7) a tube bundle (2) comprising exchanger tubes (8) a shell (3) provided with at least a first at least a second and at least a third shell-side connection (13 14 15) for feeding and removing said shell-side fluid a first distributor (4) connected to said first tube plate (6) a second distributor (5) connected to said second tube plate (7) a partition wall (58) on the shell side configured to divide said shell (2) into a first and a second zone (18 19) said partition wall (58) defining a perimeter duct (21) having a first and a second opening (23 24) configured to put in fluid communication said first and said second zone (18 19) through said perimeter duct (21); first and second diaphragms (27 28) installed in said first and second zones (18 19) respectively adapted to support said heat exchanger tubes (8) and/or to perform deviations of the flow of said shell-side fluid in order to increase the heat exchange said perimeter duct (21) essentially annular in shape surrounding the portion of said tube bundle passing through said second zone (19) so that said first (13) and third shell-side connections (15) are respectively directly connected to the first zone (18) and to the second zone (19) and said second shell-side connection (14) is directly connected to the perimeter duct (21).