ES290109A1 - Improvements in and relating to the high pressure polymerisation of ethylene - Google Patents

Abstract

In a process of polymerizing ethylene under high pressure in an elongated reactor the linear velocity within which is increased periodically, the integral of reaction temperature taken over the period of each pulse is compared with the integral for the preceding pulse, the next interval between pulses and/or the linear velocity during the next pulse being varied as necessary to produce a constant integral and hence amount of polymer deposition. As shown, ethylene gas and a catalyst such as oxygen are fed at 11 to a reactor 10 having a preheating zone, a reaction zone, and a cooling zone the temperatures of which are controlled by surrounding water jackets. The polymer and gas are exhausted to known processing apparatus at 16. Pulsing is controlled by an integrator-type timer 26 which is effective through a selector switch 28 and an actuator 38 to adjust an exhaust valve 14 to increase the rate of flow until a comparator 40 indicates that reactor pressure as measured by a strain gauge measuring device 24 has fallen to a predetermined value. Between pulses the pressure within the reactor is maintained constant by pressure measuring device 24 controlling valve 14 through a further actuator 36 which is rendered effective by selector switch 28. The output of a thermocouple 18 measuring the temperature within the reactor is applied to a computer 22 which integrates over the period of a pulse and stores the result for comparison with the next integration. Any difference controls timer 26 to alter the period before the next pulse and/or the setting of valve 14 during the next pulse. Several computers may be associated with differently located temperature responsive devices, e.g. 18, 18a, and the integral having the greatest deviation is automatically selected to control the reactor. Failure to correct is indicated by an alarm 43. Specifications 816,110 and 1,000,308 are referred to.