Patent EA-002863-B1 (EA)
Title: Process for introducing a liquid in a fluidised bed
Inventor: BARRACO JOSEPH
IPC: C08F2/01
Filed: 2000-04-18
Abstract: 1. A process for the introduction of a liquid into a continuous process for the gas-phase polymerisation of an olefin monomer chosen from (a) ethylene, (b) propylene, (c) a mixture thereof, and one or more other alpha-olefins in combination with (a), (b) or (c), in a fluidised bed reactor, by continuously recycling the gas phase which supports the fluidised bed and passes through the latter, the said gas phase having been heated in contact with the polymerisation catalyst under reactive conditions and with polymer particles being formed, by cooling the said recycled gas phase, the process characterized in that the liquid is introduced by means of at least one nozzle comprising a feed pipe (1) and a sleeve (2) sliding inside and at the end of the said pipe, the position of the said sleeve (2) along the feed pipe (1) being determined by the pressure of the feed liquid (3) and the return force of a preloaded spring (4), the said spring having one end fixed to the sleeve (2) and the other end to the feed pipe (1), the sleeve (2) being provided with one or more recesses (10) along its surface for sliding with the feed pipe (1), the said recesses (10) emerging in a groove (11) around the circumference of the sleeve (2) and below a circular stop (8) integral with the same sleeve (2), and characterized in that, i) when the pressure of the feed liquid (3) is not high enough to move the sleeve (2), the said stop (8) rests on a rim (9) of the end of the feed pipe (1) making it possible for the introduction of the said liquid (3) to be stopped or for it to be kept stopped, the said rim (9) and the circular stop (8) of the sleeve each being provided with a bearing surface (12) and (13), the contact area of which being minimised in order to allow good sealing, and, ii) when the pressure of the feed liquid (3) is high enough to move the sleeve (2), the said liquid (3) is conveyed by the recesses (10) as far as the groove (11) in the sleeve in order to be introduced towards the outside between the bearing surfaces, on the one hand, of the rim (9) of the end of the feed pipe (1) and, on the other band, of the stop (8) of the sleeve (2). 2. Process according to the preceding Claim, characterised in that the gas phase which supports the fluidised bed and passes through the latter is continuously recycled by cooling the said recycled gas phase to a temperature at which some liquid condenses, by separating the said condensed liquid from the gas phase and by introducing said condensed liquid directly into the fluidised bed by the process of the invention. 3. Process according to any one of the preceding Claims, characterised in that the number of recesses (10) is between 2 and 8, preferably between 4 and 6, for example 4. 4. Process according to any one of the preceding Claims, characterised in that the contact area of the bearing surfaces (12) and (13) of the rim (9) of the end of the feed pipe (1) and of the stop (8) of the sleeve (2) is minimised by virtue of a chamfer on the inside of the said rim (9). 5. Process according to any one of the preceding Claims, characterised in that the movement of the sleeve is limited by a blocking device. 6. Process according to any one of the preceding Claims, characterised in that a catalyst or a prepolymer is introduced in the fluidised bed directly with the with the nozzle of the present invention. 7. Process according to any one of the preceding Claims, characterised in that the fluidised bed reactor comprises from 2 to 8 nozzles. 8. Process according to any of the preceding Claims, characterised in that the nozzles are oriented in a vertical position. 9. Process according to Claim 8, characterised in that the dispersion of the liquid outside the nozzle is equal to 360 degree . 10. Process according to any one of the Claims 1 to 7, characterised in that the nozzles are oriented in an horizontal position. 11. Process according to Claim 10, characterised in that a feed liquid jets is formed in the fluidised bed and have the shape of an horizontal hollow cones.