METHOD FOR OPERATING MULTI-FLOW PASSAGE DEVICE

PROBLEM TO BE SOLVED: To stably obtain a reaction product C of a desired quality in a method for operating a multi-flow passage device 1 and in the multi-flow passage device 1 by keeping a residence time in which the reaction product C remains in a reaction flow passage constant.SOLUTION: In a method for operating a multi-flow passage device 1, when the flow rate of a raw material fluid or a reaction product C flowing through a reaction flow passage decreases during the operation of the multi-flow passage device 1 having the reaction flow passage for generating the reaction product C by chemically reacting the raw material fluid while circulating it, a fluid Z which is inert to the raw material fluid or reaction product C is mixed on the downstream side of an introduction position of the raw material fluid in accordance with a decrease in the flow rate of the raw material fluid or reaction product C.