Heat exchanger with leak detecting double wall tubes

DETAILED DESCRIPTION In general, a heat exchanger for transferring heat from a primary fluid to a secondary fluid, when made in accordance with this invention, comprises a shell, a plurality of double wall tubes with at least one groove at the interface of the walls, a single tubesheet having a plurality of holes for receiving one end of the tube disposed on one end of the shell and a pair of generally parallel spaced apart tubesheets having a plurality of holes for receiving the tubes disposed on the other end of the shell.
The tubes are so disposed in the shell and tubesheets that the outer wall of each tube terminates adjacent the inner tubesheet of the pair and the inner wall of each tube terminates adjacent the outer tubesheet of the pair.
The shell has enlarged bulbous portions disposed adjacent each end thereof and extends into the bulbous portions, forming a double wall with a chamber between the walls.
Foraminous collars are disposed between the chambers and the inner portion of the shell.
Inlet and outlet primary fluid nozzles are disposed within the bulbous portion to cause the primary fluid to flow through the shell side of the heat exchanger.
Heads are disposed on each end of the shell and cooperate with the tubesheets at each end of the shell to form headers for the tubes.
One of the heads has an inlet nozzle for the secondary fluid and the other head has an outlet nozzle for the secondary fluid, which allow the secondary fluid to flow through the tubes and pick up heat from the primary fluid.