GB849929A - Improved method and apparatus for catalyst activation - Google Patents

Abstract

<PICT:0849929/III/1> In a process for activating solid catalyst particles wherein the catalyst is contacted with a stream of inert gas at an activation temperature and at a velocity sufficient to maintain the catalyst in a fluidized state, the stream of gas is maintained in a closed recirculating system, make-up gas is added to the recirculating stream at a predetermined rate and gas is purged from the stream at a rate equal to the make-up gas rate so that a circulation rate may be maintained independently of the make-up and purge rates. Catalyst to be activated, such as chromium oxide impregnated on a silica-alumina base is conveyed to a fluidizing zone 12 of a vessel 11 where it rests on a grid 15 and is fluidized by air from blowers 22 and 22a passing through a line 23, inlet 17 and outlet 18. Entrained catalyst is removed from the airstream in a disengaging zone 13 of larger area to reduce the velocity of the air. The air from outlet 18 passes through a cyclone separator 19 and is returned by a line 21 to blowers 22 and 22a. The air stream in line 23 is heated in a heater 41. Fresh air is brought into the circulating stream through a line 26, and an equal amount of air is purged through a line 24, removing moisture and catalyst poisons. When the air and catalyst have reached the activation temperature (e.g. 400 to 1750 DEG F.) the make-up air is passed through driers 33 and 35. Some of the air in line 21 is cooled in a cooler 38 before it is passed through bag filters 25 in purge line 24 or through the blowers 22 and 22a, the temperature in line 21 being controlled by a temperature controller 42 which adjusts a valve 44 in a line 39 by-passing the cooler 38. To obtain a constant air velocity for fluidization, the pressure drop in the fluidizing zone 12 is measured by a differential pressure controller 45, in combination with pressure lines 46 and 47, which regulates a valve 48 in line 23 and blowers 22 and 22a. Make-up air addition is kept constant by a flow recorder 51 regulating a valve 52, and a pressure controller 53 controls a valve 54 in purge line 24 to stabilize the pressure of the circulating air by purging an amount of air equal to the make-up air. A dew point indicator recorder 59 controls heater 41, so that the activation temperature is maintained until the dew point is below 0 DEG F., preferably below -40 DEG F. After the catalyst is activated it is cooled while the air is circulated, and is then passed to receivers 62 and 62a.