TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Reactor: The outlet aperture is formed in at least one of the primary shell member and the second tube sheet device. The reactor includes an outer shell having two ends and an outer shell wall extending between the ends. The outer shell is closed at the second end, extending around the primary shell member and the second tube sheet device, and has an inlet for the fuel. A fuel passageway is formed between the outer shell wall and the sidewall of the primary shell member, and extends from the inlet for the fuel to at least one outlet aperture. The second tube sheet device includes a secondary shell member having a peripheral sidewall with an end of the secondary shell member adjacent to the secondary end of the primary shell member and together with the secondary end, forming a disconnected joint. The second tube sheet device is free to move relative to the primary shell member upon thermal expansion of the heat exchange tubes. A gap is formed at the disconnected joint. At least one outlet aperture comprises the gap. The reactor further includes a first catalyst to catalyze the reaction of the fuel and the gaseous fluid and a second catalyst in the primary shell member in the vicinity of the primary end and outside the heat exchanging chamber.The first catalyst is in a secondary shell member having a peripheral sidewall. An end of the peripheral sidewall is adjacent to the secondary end of the primary shell member and, together with the secondary end, forms the disconnected joint. The first catalyst enables flow of a mixture of the fuel and the gaseous fluid through it to produce the gaseous mixture. The first catalyst comprises an autothermal reformation catalyst; a partial oxidation catalyst; a steam reformation catalyst or a combustion catalyst. The second catalyst is a water/gas shift reaction catalyst, or a preferential oxidation catalyst. At least one outlet aperture is formed at the secondary end of the primary shell member. The second tube sheet device includes a secondary shell member having a peripheral sidewall with a first predetermined/internal diameter and a coaxial sleeve extension extending from either the peripheral sidewall at its end closest to the secondary end or its sidewall at its secondary end respectively and having a second predetermined/external diameter different than the first predetermined/internal diameter respectively. The sleeve extension has a free end in the region of the at least one outlet aperture which are formed at or near the secondary end of the primary shell member. The secondary shell member is relatively movable during use of the fuel conversion reactor between a first position and a second position. In the first position, at least one aperture is partially blocked by the sleeve extension. In the second position, at least one aperture is at least substantially open for passage of the gaseous fluid. The heat exchanging apparatus for a fuel conversion reactor, preferably comprises: the outer shell having two ends and inner and external surfaces extending between the two ends; a first inlet for a fuel in the outer shell in the vicinity of the first end; a primary inner shell having primary and secondary ends and an outer surface extending between the primary and secondary ends; a fuel passageway between the outer surface of the inner shell and the inner surface of the outer shell and extending longitudinally from the first inlet to the secondary end of the inner shell; a secondary inner shell having a first end adjacent to the secondary end of the primary inner shell and a second end spaced from the first end of the secondary inner shell; at least one outlet aperture, which is formed in at least one of the primary inner shell and the secondary inner shell in the region of the secondary end of the primary inner shell to provide for passage of a gaseous fluid out of the primary inner shell; a further passageway between the secondary inner shell and the outer shell and extending from the first end to the second end of the secondary inner shell, a mixture of the fuel and the gaseous fluid flowing through the passageway during use of the apparatus; a first tube sheet fixed in the primary inner shell near to the primary end and sealingly closing off the primary inner shell; a second tube sheet fixedly connected to the secondary inner shell and sealingly closing off the secondary inner shell; and several heat exchange tubes extending from the first tube sheet to the second tube sheet and connected to both tube sheets. The heat exchange tubes forms passageways for a hot gaseous mixture to flow through the second tube sheet and then through the first tube sheet. The hot gaseous mixture is cooled in the tubes during use of the apparatus. The second end is closed. The primary inner shell extends into the outer shell and is joined to the outer shell. The secondary end of the primary inner shell and the first end of the secondary inner shell form a disconnected joint and the secondary inner shell is free to move relative to the primary inner shell upon thermal expansion of the heat exchange tubes. The heat exchanging apparatus including a second inlet for the gaseous fluid provided in a side of the primary inner shell in the vicinity of the primary end. Baffle plates are within the primary inner shell between the two tube sheets. At least one outlet aperture can vary in effective size during use of the heat exchanging apparatus. The outer shell is formed with projections that are spaced around the outer shell and that project inwardly to engage the outer surface of the primary inner shell. A catalyst can be included within the outer shell in the region of the second end for effective contact with the mixture of the fuel and the gaseous fluid in order to produce the hot gaseous mixture. The apparatus includes the catalyst for a fuel conversion reaction or an autothermal reformation of a hydrogen-containing fuel to produce a hot gaseous mixture containing hydrogen or a catalyst for a carbon monoxide cleanup reaction operatively connected to a downstream end of the passageways formed by the heat exchange tubes. The catalyst is within the outer shell in the region of the second end and is able to produce the hot gaseous mixture by effective contact with the mixture of the fuel and the gaseous fluid. The hot gaseous mixture is a hydrogen-containing reformate having a temperature of at least 500 degrees C. The primary inner shell has a catalyst containing section adjacent the primary end and a further catalyst is in the catalyst containing section. The primary inner shell has an outlet to allow outflow of a hydrogen-containing reformate from it. When the reactor is a fuel reformer, the reformer converts hydrogen-containing fuel to hydrogen using a catalytic reaction. The heat exchanging shell apparatus includes a primary shell member having two opposite ends and a first tube sheet fixed near to one of the two ends and a secondary shell member having a first end located adjacent the other of the two ends and a second tube sheet fixedly connected to the secondary shell member. The several heat exchange tubes extend from the first tube sheet to the second tube sheet and is connected to both tube sheets. The heated gaseous fluid is withdrawn from the chamber through at least one aperture formed in at least one of the primary shell member and the secondary shell member in the region of the other of the two ends of the primary shell member. The heat exchanging shell apparatus includes an outer shell member which encloses at least a substantial portion of the primary and secondary shell members, a fuel passageway between the outer shell member and the primary shell member and extending longitudinally from a fuel inlet of the outer shell member to the other of the two ends of the primary shell member.Preferred Reformer: The reformer comprises: the primary shell member having primary and secondary ends and a sidewall extending between the ends; a secondary shell member having a first end located adjacent the secondary end of the primary shell member, at least one outlet aperture formed in at least one of the primary and the secondary shell members in the region of the secondary end of the primary shell member to provide at least one outlet for a gaseous fluid flowing through the primary shell member; an inlet on the primary shell member for introduction of the gaseous fluid into a heat exchanging chamber formed by the primary shell member; a first tube sheet fixed onto the primary shell member and sealingly closing the heat exchanging chamber at a first end of the chamber; a second tube sheet fixedly connected to the secondary shell member and forming a second end of the heat exchanging chamber which is opposite the first end; several heat exchange tubes extending from the first tube sheet to the second tube sheet and rigidly connected to both tube sheets; a first catalyst for a fuel conversion reaction adjacent to the second tube sheet and outside the heat exchanging chamber to produce the hot gaseous mixture from a mixture of the hydrogen-containing fuel and the gaseous fluid. The hot gaseous mixture is cooled to a desired temperature by heat exchange with the gaseous fluid passing through the heat exchanging chamber during use of the reformer. The reformer also contains the second catalyst for a second catalytic reaction outside the heat exchanging chamber and operatively connected to the downstream end of the passageways so that the cooled gaseous mixture is brought into effective contact with the second catalyst during use of the reformer; and a hydrogen-containing fuel mixture delivery arrangement to deliver the mixture of the hydrogen-containing fuel and the gaseous fluid, the latter flowing from the one or more outlet apertures, to the first catalyst. The heat exchange tubes provide passageways for a hot gaseous mixture to flow through the heat exchanging chamber to a downstream end of the passageways. When the gaseous fluid is a mixture of steam and air, the delivery arrangement comprises an outer shell member extending around the primary and secondary shell members and rigidly connected to the primary shell member. The first end of the secondary shell member and the secondary end of the primary shell member form a disconnected joint and the size of the at least one outlet varies and is dependent on operating temperatures of the fuel reformer in the heat exchanging chamber. A hydrogen-containing fuel inlet is provided at one end of the outer shell member located closest to the primary end and fuel passageways are formed between the outer shell member and the primary shell member and extend from the fuel inlet to the one or more outlet apertures. At least one further passageway is formed between the outer shell member and the secondary shell member and the passageway allows the mixture of the hydrogen-containing fuel and the gaseous fluid to flow from a region adjacent to the at least one outlet aperture to an enclosed mixing chamber adjacent to the first catalyst. At least one baffle plate is on the heat exchange tubes and within the heat exchanging chamber and causes the flow of the gaseous fluid to follow a winding path through the heat exchanging chamber. The reformer includes several baffle plates. One of the baffle plates is near to the outlet aperture and has a central opening through which the gaseous fluid flows in a radially outward direction toward the outlet apertures. The outer shell member includes a sidewall formed with projections that are spaced around the outer shell and that project radially inwardly to engage the sidewall of the primary shell member. There are several outlet apertures in the primary shell member and the second catalyst comprises a carbon monoxide cleanup catalyst capable of reducing carbon monoxide concentration in the cooled gaseous mixture. The carbon monoxide cleanup catalyst further increases hydrogen yield. The inner shell apparatus comprises a primary inner shell member having two opposite ends and a secondary inner shell member having one end located adjacent one of the two ends of the primary inner shell members. The at least one aperture is formed in at least one of the primary inner shell member and the secondary inner shell member in the region of the one end of the primary inner shell member. Several heat exchange tubes are mounted in the primary inner shell member.Preferred Method: When the fuel comprises a hydrogen-containing fuel, the reaction of the fuel and the gaseous mixture is a catalytic fuel conversion reaction, which produces hydrogen in the gaseous mixture. The initial mixture comes into contact with a first catalyst capable of effecting the catalytic fuel conversion reaction. The gaseous mixture contains hydrogen flows from the first catalyst. The gaseous fluid contains water and oxygen, a mixture of air and steam. When the hot gaseous mixture passes through the passageways to a second catalyst, the method further involves causing the partially cooled gaseous mixture to come into contact with the second catalyst to reduce a concentration of carbon monoxide in the partially cooled gaseous mixture. The method involves heating the fuel by causing the fuel to flow along the fuel passageway to provide heat exchange between the fuel and the gaseous fluid passing through the chamber. The fuel comprises a hydrogen-containing fuel and the reaction of the fuel and the gaseous mixture is a catalytic fuel conversion reaction which produces hydrogen in the gaseous mixture, such that the initial mixture comes into contact with a first catalyst capable of effecting the catalytic fuel conversion reaction. The gaseous mixture contains hydrogen flows from the first catalyst. The first catalyst is in the secondary shell member and a second catalyst is in the primary shell member in proximity to the one of the two ends. The first end of the secondary shell member and the other of the two ends of the primary shell member form a disconnected joint, and the step of passing the hot gaseous mixture through the passageways causes thermal expansion of the heat exchange tubes and a resulting movement of the secondary shell member relative to the primary shell member. When the method converts the hydrogen-containing fuel to hydrogen using a catalytic reaction, the method is carried out by providing the outer shell having first end and second closed end and an inner shell apparatus having two opposite ends, extending into the outer shell at the first end and joined to the outer shell. A passageway is formed between the outer shell and the inner shell apparatus and extends from the inlet for hydrogen-containing fuel to one of the two ends of the inner shell apparatus; passing a gaseous fluid through a chamber formed in and by the inner shell apparatus to heat the gaseous fluid and then passing the gaseous fluid through at least one apertures formed in a side of inner shell apparatus. The heated gaseous fluid enters the passageway. The conversion method further involves simultaneously passing hydrogen-containing fuel through the inlet and the passageway and heating the hydrogen-containing fuel by heat exchange with the heated gaseous fluid and mixing with the heated gaseous fluid to form a mixture of the fuel and the gaseous fluid; and contacting the mixture with catalytic material to produce hydrogen. The gaseous fluid is heated by heat exchange in the chamber by passing hot reformate through the tubes. The reformate contains hydrogen and is produced by a catalytic fuel conversion reaction of the mixture of the fuel and the gaseous fluid. The catalytic reaction process includes a first catalytic reaction employing a first catalyst for producing a fuel conversion reaction arranged at the one end of the inner shell apparatus and a second catalytic reaction employing a second catalyst arranged at an opposite end of the inner shell apparatus. The first catalytic reaction produces a reformate which is passed through the chamber by heat exchange tubes and which is used to heat the gaseous fluid. The second catalytic reaction reduces a concentration of carbon monoxide in the reformate. The catalytic material is divided into a first body of catalytic material capable of producing a fuel conversion reaction and a second body of catalytic material with each body in a respective one of opposite end sections of the inner shell apparatus. The first body produces the reformate and the second body reduces a concentration of carbon monoxide in the reformate. The first body of catalytic material is an autothermal reformation catalyst capable of converting the hydrogen-containing fuel to hydrogen. The second body of catalytic material is a carbon monoxide cleanup catalyst. The one end of the secondary inner shell member and the adjacent end of the primary inner shell member form a disconnected joint and the secondary inner shell member moves relative to the primary shell member due to thermal expansion of the heat exchange tubes as the hot reformate passes through the tubes. The gaseous fluid flows radially outwardly through at least one aperture where it enters the passageway and is combined with the fuel. The gaseous fluid and fuel are uniformly mixed in a mixing chamber such that the mixture presents a uniform distribution to the catalytic material.