Figure 1. Steam molar fraction contour plots in the combined parallel plate heat exchanger-reactor for hydrogen production by steam-methanol reforming.
The methanol molar fraction contour plots in the combined parallel plate heat exchanger-reactor are illustrated in Figure 2 for hydrogen production by steam-methanol reforming. The combined heat exchanger-reactor consists of sheets of triangularly corrugated material laminated together so as to form a series of roughly parallel passageways. In order for the exchanger to effectively function, the inlet area of the exchanger utilizes a highly complicated design feature characterized by detents and depressed crossflow passageways which effectively causes fluid flow blockage. Consequently, this heat exchanger possesses a high pressure drop. The method of construction recited in the patent and exemplified by the drawings utilize long metal welds or similar materials joining techniques resulting in a structure highly susceptible to internal rupture, leakage and uncontrolled fluid crossover. The combined heat exchanger-reactor consists of a monolithic honeycomb structure wherein the channels of the honeycomb are divided into separate groups, group one channels carrying one fluid with group two channels carrying another fluid which differs from the first either by composition, temperature, pressure, and direction of flow. The main design feature of the combined heat exchanger-reactor is that one group of channels extends outward from the honeycomb parallel to the direction of fluid flow in the honeycomb, each channel of the group one being in contact through common walls with channels in group two, each channel of group one being separated from other channels of group one by the intervening voids formed by the presence of the channels of group two. One or both of the open ends of the group one channels are manifolded so as to form a separation of entrances of the extended group one channels as compared to the group two channels and the entire system is incorporated into an outer mechanical shell so as to facilitate fluid flow through group one and group two channels, thereby permitting the entry or exit of fluid in group one channels while preventing entry of such same fluid into the group two channels and thereby permitting the independent passage of different fluids through the different channel systems. The common walls which exist between adjacent channels of the different groups facilitate heat transfer from one channel group to another. The honeycomb structure, with its mutually supporting, double cantilevered inner walls, imparts strength to the overall system permitting the walls to be very thin and thereby being responsible for the low weight and rapid thermal response of the combined heat exchanger-reactor configuration. Alternatively, the manifolding of the group one channels may be designed so as to create numerous independent group one channel systems while still being completely surrounded by the group two channel system, thereby permitting numerous independent reactions to proceed simultaneously and permitting more than two independent fluid flows to be conducted under varying conditions within a single chemical reactor and heat exchanger system.