TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Details: The first and second fluids pass through passages in crossing flows. The heat exchanger comprises corrugated plates facing each other in pairs in a mirror image form, to define parallel channels for each pair of plates, which are arranged as sets, to define passages with an undulating course in the crossing, countercurrent or cocurrent flow directions, with respect to the direction of flow in the channels between one pair of plates and the next. At least two adjacent channels are connected by transverse connecting conduits. The pairs of plates are formed by welding along the two flat sides of two plates that face each other as a mirror image. The shell has an inlet space for the first fluid between the inlet opening for the first fluid and the heat exchanger, and an outlet space for the first fluid between the outlet opening for the first fluid and the heat exchanger. It also has an upper space for entry of the second fluid above the heat exchanger and communicating with the outside through the inlet opening for the second fluid, and a lower space for exit of the second fluid below the heat exchanger and communicating with the exterior through the outlet opening for the second fluid. The inlet and outlet spaces are separated from each other.Preferred Process: The steam reforming process is performed at 500-1100, preferably 650-950 degreesC. The ratio between the flows of the heating fluid and the fluid for reforming is 10:1 - 25:1, preferably 20:1.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Catalyst: The steam reforming catalyst is based on nickel. The combustion catalyst is based on noble metals, such as Pd or Pt.Preferred Method: The catalysts are deposited as a thin layer on the surfaces of their respective flow passages. The steam reforming catalyst layer is formed to 50-200, preferably 80-150 micron, and the combustion catalyst layer is formed to 30-80, preferably 40-70 g/m2. They are deposited by a wash coating method, from a suspension of catalyst and a support material. The deposition of the catalyst layer is followed by calcination of the catalyst.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Fluid: The fluid for reforming is a methane/steam mixture. The heating fluid is a mixture of hydrogen and/or gaseous hydrocarbons or other fuels.