Method of removing heat from polymerization reactions of monomers in the gas phase

In an improved method of removing heat from the polymerization reactions of monomers in the gas phase in which gaseous or liquid monomer optionally together with an inert liquid heat-transfer agent is introduced into the polymerization zone, pulverulent polymer is removed therefrom and gaseous monomer or gaseous inert heat-transfer agent, is removed from said polymerization zone, liquefied by cooling under the pressure prevailing in the polymerization zone and reintroduced in the liquid state into the polymerization zone, the improvement which comprises:

• a. condensing and storing said monomer or heat-transfer agent outside the polymerization zone, while the temperature in the polymerization zone is kept constant by regulating the rate of reintroduction of the liquid monomer or heat-transfer agent into the polymerization zone;
• b. mixing the liquid monomer or liquid heat-transfer agent with the pulverulent polymer within said polymerization zone, said liquid monomer or said liquid heat-transfer agent coming in direct contact with said pulverulent polymer before said monomer or said heat-transfer agent vaporizes;
• c. controlling the rate of flow of the vaporized monomer or heat-transfer agent so that it does not exceed 10 cm/sec/;
• d. maintaining the pressure and temperature in the polymerization zone being at such a level that the vaporized monomer or heat-transfer agent remains in the gaseous state;
• e. stirring said pulverulent polymer in said polymerization zone with a stirrer having an output of from 10 to 35 watts/liter of pulverulent polymer;
• and
• f. the mean circulation time of the polymer particles in the polymerization zone is maintained at from 30 to 100 seconds.