Abstract: A spiral heat exchanger includes a vessel, a plurality of concentric sheet metal spirals situated in the vessel and defining first and second spiral flow channels for respective first and second fluids for effecting a heat exchange therebetween; first and second closure plates extending perpendicularly to the vessel axis and covering the spirals at opposite spiral edges thereof; and mounting bars pressing the closure plates against axially opposite edges of the spirals. The first closure plate defines a first axially oriented opening and the second closure plate defines a second axially oriented opening providing, in the first flow channel, an inlet and an outlet for the first fluid. The vessel comprises a cylindrical vessel shell entirely surrounding the spirals.