NOVELTY - A channel reactor system comprises at least two channel units (110, 210), each containing a reaction channel plate assembly (120) into which reaction gas is introduced and a heat-exchanging channel plate assembly (130) into which cooling fluid is introduced; and at least one intermediate plate (200) disposed between the upper and lower channel units.    USE - For water-gas shift reaction (claimed) useful for production of hydrogen-rich gas useful in fuel cell; and various multi-steps reaction processes such as carbon monoxide reaction process, and reaction process for producing aldehyde.    ADVANTAGE - The channel reactor system is miniaturized and has a structure by which heat can be effectively removed. The channel plate assembly and heat-exchanging channel plate assembly are constituted integrally with each other to obtain an excellent heat-removing effect. The system easily performs heat-exchange and control of heat. Since the heat-exchanging channel plate assembly is disposed adjacently to the reaction channel plate assembly, there is no need to provide an additional member such as a pipe for coupling a cooling unit to the reactor so that a thermal efficiency of the system can be remarkably enhanced. The heat-exchanging plate assembly is disposed such that the heat-exchanging plate assembly is contacted with the reaction channel plate assembly, so that the generated in the exothermic reaction can be effectively removed. By disposing in stack the upper end plate, the first channel unit, the intermediate plate, the second channel unit and the lower end plate, it is possible to obtain the effect that a size (volume) of the system can be significantly reduced.    DETAILED DESCRIPTION - A channel reactor system comprises at least two channel units into which reaction gas and cooling fluid are separately introduced, each channel unit contains a reaction channel plate assembly into which reaction gas is introduced and a heat-exchanging channel plate assembly into which cooling fluid is introduced; and at least one intermediate plate disposed between the upper and lower channel units, and supplying new reactant and cooling fluid to reaction gas and cooling fluid in flowed from the upper channel unit and supplying reaction gas and cooling fluid to the reaction channel plate assembly and the heat-exchanging channel plate assembly of the lower channel unit, respectively. The reactor system further comprises an upper end plate disposed on the uppermost channel unit to supply reaction gas to the reaction channel plate assembly and cooling fluid to the heat-exchanging channel plate assembly of the upper channel unit; a lower end plate disposed below the lowermost channel unit, and discharging reaction product discharged from the reaction channel plate assembly and discharging cooling fluid discharged from the heat-exchanging plate assembly of the lowermost channel unit; and gaskets between first and second channel plates.    DESCRIPTION OF DRAWING(S) - The figure shows an exploded view of the reactor system.    channel unit (110, 210)    reaction channel plate assembly (120, 220)    heat-exchanging channel plate assembly (130, 230)    intermediate plate. (200)