Abstract: A mixer mixes at least two fluid components of the type which when mixed together undergo chemical reaction to form a solid or semi-solid reaction product. The components are separately introduced into the mixer, whereat they are mixed, and the reaction mixture is discharged from the mixer prior to the completion of the chemical reaction and while still in a fluid state. When desired, for example when it is necessary to shut down the operation of the mixer, the chemical reaction in the mixer is arrested by selectively cooling the reaction mixture down to a temperature at which the chemical reaction will not occur or will at least be retarded. This prevents the formation of the reaction product within the final mixer. Thereafter, for example when the operation of the mixer is again commenced, the reaction mixture is reheated to an increased temperature at which the chemical reaction will continue.

Abstract: A fluid stream including separate layers of plural components is mixed by dividing the fluid stream into a plurality of substreams, reorienting and recombining the substreams in a chamber, and repeating the steps of dividing, reorienting and recombining until a desired degree of mixing of the components is obtained. The substreams of a given stage or group of substreams are controlled so that the substreams are longitudinally dephased with respect to each other such that the fluids of the substreams are longitudinally blended when recombined. The dephasing is achieved by providing that at least selected of the passageways for the substreams of a given stage of the mixer are dimensioned such that the total resistances to flow of the fluid of the substreams passing through the selected passageways, from the beginnings thereof to the ends thereof, are unequal.