Patent ID: 7172737

Claim:
In a fuel conversion reactor, a shell-and-tube heat exchanger for heating a gaseous fluid prior to reaction with a fuel and for cooling a gaseous mixture produced by the reaction, said heat exchanger comprising: (a) a first heat exchanger section comprising: (i) a first primary shell member having primary and secondary ends and a sidewall extending between said ends and defining a first heat exchanging chamber located within the first primary shell member; (ii) a first tube sheet fixedly mounted on said first primary shell member in the vicinity of said primary end and sealingly closing said first heat exchanging chamber at one end of the first chamber; (iii) a first tube sheet device which is separate from said first primary shell member and is located in the vicinity of said secondary end, said first tube sheet device forming another end of said first chamber that is opposite said one end of the first chamber; and (iv) a first plurality of heat exchange tubes extending from said first tube sheet to said first tube sheet device and rigidly connected to both the first tube sheet and the first tube sheet device, said heat exchange tubes providing passageways for said gaseous mixture to flow inside the tubes through said first heat exchanging chamber; and (v) one or more outlet apertures formed in the region of said secondary end of said first primary shell member in order to provide at least one outlet for said gaseous fluid which flows through said first heat exchanging chamber on a shell-side thereof during operation of said fuel conversion reactor; and (b) a second heat exchanger section comprising: (i) a second primary shell member having primary and secondary ends and a sidewall extending between said ends and defining a second heat exchanging chamber in flow communication with the first heat exchanging chamber, the second primary shell member being concentric with the first primary shell member with the primary end of the first primary shell member being located proximate the secondary end of the second primary shell member; (ii) a second plurality of heat exchange tubes mounted in the second primary shell member and communicating with the heat exchange tubes of the first heat exchanger section; (iii) an inlet in the sidewall of the second primary shell member for introducing the gaseous fluid into the second heat exchanging chamber; (iv) one or more outlet apertures formed in the region of the secondary end of the second primary shell member to provide at least one outlet for the gaseous fluid to flow from the second heat exchanging chamber to the first heat exchanging chamber; wherein the first heat exchanger section further comprises one or more inlet apertures formed in the region of the primary end of the first primary shell member to provide at least one inlet for the gaseous fluid to flow into the first heat exchanging chamber from the second heat exchanging chamber.