Abstract: A polymer slurry composed of solid polymer particles and a diluent such as an inert hydrocarbon and or an inert halogenated hydrocrbon, kept at a sufficient super-atmospheric pressure to maintain the diluent in the liquid state, is continuously introduced into a heating tube divided into a first and a second heating zone, the diameter of the second heating zone being larger than that of the first heating zone. The flow rate of the slurry passing through the first heating zone is controlled by regulating the amount of heat supplied to the first heating zone. Substantially all of the vaporized diluent is then introduced into a separation zone and separated from the solid polymer particles.