Water vaporizer with intermediate steam superheating pass

A water vaporizer comprising:

• a first flow path connected to a water inlet;
• a second flow path for receiving water vapor from the first flow path and being connected to a vapor outlet to exhaust the water vapor;
• a third flow path extending between an exhaust inlet and an exhaust outlet, the first, second, and third flow paths being substantially concentric;
• a first convoluted fin extending into the second flow path for transferring heat from a flow of exhaust traveling along the third flow path to the water vapor traveling along the second flow path;
• and
• a second convoluted fin extending into the second flow path and being arranged interior of the first fin for transferring heat from the water vapor traveling along the second flow path to a flow traveling along the first flow path;
• wherein the second convoluted fin is separated from the first convoluted fin to define a gap, wherein the gap is positioned in the second flow path.

A water vaporizer comprising:

• a first flow path connected to a water inlet;
• a second flow path for receiving superheated water vapor from the first flow path and being connected to a water vapor outlet to exhaust a superheated water vapor;
• a third flow path extending between an exhaust inlet and an exhaust outlet;
• and
• a convoluted fin extending into the second flow path for transferring heat from a flow of exhaust traveling along the third flow path to a flow traveling along one of the first and second flow paths, the convoluted fin having a first plurality of crests and a second plurality of crests opposite the first plurality of crests, the first plurality of crests defining a plurality of valleys between adjacent crests of the first plurality of crests, the second flow path having a bypass around the fin such that the plurality of valleys are in fluid communication with each other;
• wherein a width of the bypass along a length of the second flow path in a direction substantially parallel to the flow of exhaust along the third flow path is no greater than a width between adjacent convolutions of the fin.