2. Methods
In the present study, a catalytic reactor employs an un-partitioned exothermic catalytic reaction channel and multiple cooling conduits passing through the exothermic catalytic reaction channel. An oxidation catalyst is deposited on the exterior surfaces of the conduits within the exothermic catalytic reaction channel. This placement of the catalyst allows the oxidation catalyst to be backside cooled by any fluid passing through the cooling conduits. Backside cooling means that at each location where an oxidation catalyst is deposited on one surface of a wall no oxidation catalyst is deposited on an adjacent or opposite surface in contact with the cooling fluid, and a portion of the heat generated by reaction on the oxidation catalyst is conducted through the substrate to the adjacent or opposite surface that is in direct contact with the cooling fluid [67, 68]. The catalytic reactor can be made in numerous configurations with the following common elements [69, 70]. A casing forms the outer boundary, which can be of any shape. The reactor casing can be a single fabricated component, or can consist of two or more components joined together. Two or more conduits are placed within the casing such that one fluid stream can traverse an un-partitioned channel, the exothermic catalytic reaction channel, defined by the interior surface of the casing and the exterior surfaces of the conduits, and a number of separate fluid streams can traverse the passages defined by the interior surfaces of the conduits, without mixing occurring between fluid in the exothermic catalytic reaction channel and fluid in the conduits’ interior passages. A heat transfer relationship exists between the fluid in the exothermic catalytic reaction channel and the fluids in the conduits’ interior passages.
The structure of the integral heat exchange is represented physically in Figure 1 in which the catalytic reactor employs an arrangement of catalyzed and non-catalyzed substrate passages for providing passive cooling of the catalytic reactor. Such cooling permits the catalyst to function with higher reaction temperatures than otherwise possible. By applying a catalytic coating to a fraction of the walls of the parallel passages of a combustion catalyst substrate, the uncoated passages act to cool the common walls exposed to the reacting flow in the coated passages. Accordingly, the present design is directed to a catalytic reactor unit, which comprises the combination of a substrate composed of a plurality of generally parallel passages open at their opposite ends and exposed to a heated flow of fuel and air mixture therethrough and selected ones of the passages being coated with a catalyst and others of the passages being free of the catalyst so as to provide the substrate with an arrangement of catalyzed passages in which the mixture is catalytically reacted and non-catalyzed passages in which the mixture is substantially not reacted but instead provides passive cooling of the substrate. The substrate is composed of a plurality of intersecting walls defining the generally parallel passages being aligned in rows and columns. The walls have sections which border and define the respective passages. Each wall section is in common with two adjacent passages and has a pair of oppositely-facing surface regions, one of which is exposed to one of the two adjacent passages and the other exposed to the other of the two adjacent passages. The solid catalyst can have various forms and compositions and can be the types used to oxidize fuels in the presence of molecular oxygen. The catalyst can be in the form of relatively small, solid particles of various sizes and shapes, often in sizes below about one inch in the largest dimension, with a plurality of such particles being arranged together to form one or more catalyst masses or beds in the combustion zone. The catalyst is preferably of larger form and has a skeletal structure with gas flow paths therethrough.