Convective reformer furnaces have long been used for catalytic gas reactions including the production of hydrogen rich or synthesis gases. The basic design for such reformers can be found in U.S. Pat. No. 3,958,951 dated May 25, 1976.
Basically, a reformer utilizes an external combustion chamber having burners to produce high temperature flue gas for providing heat to a series of process or reformer tubes in an assembly including a tube sheet attached to the tubes and so mounted to retain the tubes in the furnace. The reformer tubes generally contain catalyst disposed in a portion of the tube through which the feed gases are passed for reaction. In the mid to late 1980's the use of ceramic tubes in convective reformers became well known.
The U.S. Pat. No. 3,958,951, cited above, utilizes reformer tubes open at both ends and having a central section for containment of the catalyst, the product gases being passed into a central tube for removal. However, development of the reformer furnace led to the use of bayonet tubes, closed at one end and open at the other end, as generally shown in U.S. Pat. No. 4,810,472 dated Mar. 7, 1989.
The reformer tubes currently known in the art, however, have not been completely reliable when dealing with a system utilizing high pressure and high temperature. It is therefore an object of the present invention to provide an improved reformer tube for use with steam reforming in convective reformers under high temperature and pressure.