Abstract: Effluent from a carbon black reactor is directly discharged FIG. 2 from the reactor to a quick cooling radiant heat exchanger before, or in some instances after, a reaction-stopping water quench. The cooled reaction quench is then supplied to an air preheater to preheat the carbonaceous feed stock that is supplied to the reactor. The heat exchanger includes a chamber having outside walls formed by heat exchanger tubes which are welded together. If desired, additional cooling capacity is provided by platens formed of heat exchanger tubes which are contained in the chamber to which the reactor effluent is supplied.