FI108001B - Fluid supply - Google Patents

Description

108001

BACKGROUND OF THE INVENTION The present invention relates to a gas phase reaction technique and relates to the introduction of a liquid into a gas phase reactor. The invention can be used, for example, in polymerization processes, especially olefin polymerization processes, for supplying liquefied recycle gas to a fluidized bed gas phase reactor.

The fluidized bed polymerization reactor comprises a bed of solid polymer particles which is held in a fluid state by conducting a gas stream at the bottom of the bed. The gas stream flows upwardly in the reactor at a rate sufficient to support the solid particles. The unreacted gas is collected at the top of the reactor, compressed and returned to the bottom of the bed. The reactor can also be equipped with a rotary mixer. The gas phase reactor can be used, for example, in polymerization processes.

In exothermic processes, the production capacity of a gas phase reactor is often limited by the ability to remove heat from the reactor. The heat can be removed, for example, by cooling the recycle gas before returning it to the reactor. It is also possible to cool the recycle gas to such an extent that some of the components in the gas are condensed. When the partially condensed recycle gas returns to the reactor, the condensed components evaporate, thereby cooling the reaction environment. One way to remove heat and control the reactor temperature is to condense the recycle gas before returning it to the reactor. The concentrate is • fed through the inlet openings on the bottom wall of the reactor.

Such a cooling system is disclosed, for example, in US 4,368,291. The document discloses a process for preparing polyethylene in which ethylene is first polymerized in a liquid reactor and then in a gas phase reactor. The dispersion material from the gas phase reactor can be removed and cooled, possibly sealed, and recycled to the reactor.

EP-B-89691 discloses a gas phase monomer polymerization process in which the recycle gas is cooled so that at least part of it is condensed. A biphasic mixture containing gas and 30 condensed liquids is recycled to the bottom of the bed.

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EP-B-699213 also discloses a gas phase polymerization process of olefins in which the recycle gas is cooled so that at least part of it is condensed. The gas and liquid fractions are then separated, the gas is led back to the bottom of the bed, and the liquid is passed directly to the substrate. The liquid is injected into the substrate using only liquid nozzles or gas-assisted nozzles.

General description of the invention

A method according to claim 1 has now been invented. Some preferred embodiments of the invention are defined in the other claims.

According to the invention, the liquid is fed to the reactor through mixing. Thus, the liquid can be applied very uniformly to the reactor.

According to one embodiment of the invention, the purpose of the fluid supply is to remove the heat of the exothermic reaction. The liquid which is then passed through the mixing medium is such that it evaporates under the conditions of the gas phase reactor, thereby eliminating the heat of polymerization. The liquid may be freshly fed or may be a component of the recycle gas obtained by cooling the recycle gas stream by condensing part of the flow and then separating the condensed component.

The reactor may be, in particular, a fluidized bed reactor, and the gas is fed in particular to the base of such a reactor.

According to one embodiment of the invention, the recycle-20 gas stream collected from the top of the reactor is cooled such that at least one of the gas stream components is condensed. The condensed component is then separated from the gas stream. The gas stream is led back to the bottom of the fluidized bed, and the liquid stream is passed through the mix and passed through the mix into the bed. In this way, the condensed liquid is evenly distributed within the layer and does not form solid barriers with the particles in the layer.

The invention is particularly useful in polymerization processes, for example olefin polymerization processes. The olefin may be, for example, a lower olefin such as propylene or ethylene or a mixture thereof, optionally together with higher alpha-olefins and / or dienes such as 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1,9-decadiene, 1,5-hexadiene and 1,7-octadiene. The gas phase-30 polymerization process may also be a single step in a multi-step process. A specific example of this is a two-step process in which the polymerization is first performed in a liquid reactor such as a loop reactor and then in a gas phase reactor.

The mixer is preferably rotatable and provided with a shaft. Preferably, the shaft is vertical and extends beyond the bottom of the reactor. The liquid is preferably fed to the reactor through a stirrer shaft. The reactor may be provided with a sealed chamber for supplying liquid through the hollow shaft.

Brief Description of the Drawings

The accompanying drawings form part of the written description.

Figure 1 is a schematic description of a fluidized bed polymerization process.

Figure 2 shows an embodiment of the invention in which the liquid together with the flushing gas can be fed to the reactor.

Figure 3 illustrates another embodiment of the invention in which the liquid can be fed to the reactor separately from any flushing gas.

Figure 4 shows an alternative to the embodiment of Figure 3.

Detailed Description of Some Preferred Embodiments of the Invention

As shown in Figure 1, the gas containing gaseous monomers or polymerizable monomers is fed through line 1 to the fluidized bed gas phase reactor 2. The fresh monomer (s) and any other gaseous materials may be added to line 1 at a convenient location. The gas stream may also contain, for example, the catalysts required to effect polymerization in the reactor. The polymer particles form a layer on the gas distribution plate 3 at the bottom of the reactor. The gas distributor plate has small holes through which gas can be directed evenly to the bottom of the bed. The polymer is removed from the layer via line 4. The bed is maintained in a fluid state by collecting unreacted gas from the top of reactor 2 through line 5, compressing gas 25 in compressor 6, and circulating gas to reactor bottom through line 1.

The reactor may be used, for example, for the polymerization of olefins such as propylene or ethylene. Additional monomers, such as comonomers, or other reaction components, such as hydrogen, or other substances, such as aluminum alkyl cocatalysts, may be introduced into reactor 2 by combining fresh feed with recycle gas line 1.

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The gas discharged from the upper part of the reactor 2 is cooled and partially sealed in a heat exchanger 7, and the partially sealed flow is further led through line 8 to a separator vessel 9. The gas from the separator vessel 9 is led through line 1 to the bottom of reactor 2. The catalyst is introduced into reactor 2 via line 10. The catalyst feed may also take place in the form of polymer particles from an earlier polymerization step containing the active catalyst. The catalyst may also contain any gas required to convey the catalyst or polymer particles to the reactor 2. The seal from the tank 9 is led to the bottom 2 of the reactor via a separate line 11 by means of a pump 12.

The gas fed through line 1 may also contain a polymer formed in earlier steps.

The reactor 2 is provided with a rotary mixer 13 for mixing the polymer layer. The mixer comprises a vertical arm 14 extending below the bottom of the reactor 2. The arm 14 is provided with a mechanism 15 for rotating the agitated 13. 15 The upper end of the arm 14 extends above the gas distributor plate 3 and is provided with radial vanes 16 with blades 17 at their ends.

The shaft 14 of the mixer 13 is hollow, and above the gas distributor plate 3, the mixer is provided with holes for conducting fluid from the hollow shaft to the polymer layer. The seal feed line 11 leads to the hollow core of the shaft 14 separate from the gas flow of the line 1. From the hollow core of the arm 14, the seal is fed and mixed into the bed.

The reactor 2 of Figure 2 has a bottom having a central cone-shaped inner extension 18. The expansion 18 is thus surrounded by a bottom ring 19. The upper portion of the expansion 18 is separated by a solid wall 20 to form a chamber 21. The shaft 14.1 of the mixer 13 passes through the reactor 2. In the reactor 2, the arm 14.1 is provided with radial vanes 16 and blades 17. The blades 17 are located near the inner wall of the reactor. The agitator shaft seal, support bearings and rotary drive are located in the extension 18 below the chamber 21.

The stem 14.1 is hollow with its ends closed. The part inside the chamber 21 of the hollow shaft 14.1 is provided with holes 22. The vanes 16 have hollow cores which communicate with the hollow interior of the shaft 14.1 and the holes 23 which open into the reactor 2. The blades 17 have hollow interiors that engage the apertures of the blades 16 and are provided with inner or outer surfaces of the holes 24.

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The condensed circulating flow feed line 11 is connected to the chamber 21. The seal is thus introduced through the holes 22 into the shaft 14.1 and thence through the holes 23 and 24 into the reactor bed.

The gaseous circulation flow supply line 1 is connected to the bottom of the bottom ring 19.

5 Further flushing gas may be introduced through line 25 into chamber 21.

The apparatus of Figure 2 may in principle be similar to that described in EP-707513 for introducing a gas into a reactor, including additional means for feeding the liquid together with the gas.

Also, the reactor 2 of Figure 3 has a bottom having an internal expansion 18 and a bottom ring 19 and 10 for line 1 for supplying the gas circulating flow. The agitated arm 14.2 passes through the agitated arm seal, support bearings and rotary drive 15.2 and the gas distributor plate 3 to the reactor 2. The agitated arm 14.2 has a central opening 26 provided with a hollow inner arm 27 which extends through the agitated arm. At the upper end of the inner arm 27 are radial vanes 28, whose hollow cores communicate with the hollow si-15 shaft and the holes 29 which open into the reactor. The condensed circulation flow supply line 11 is connected via the fluid inlet seal 30 to the hollow interior of the inner arm 27.

The upper portion of the extension 18 is separated by a dense wall 31 so as to form a chamber 32. The shaft 14.2 has a hollow core which concentricly surrounds the hollow interior 27 of the inner arm 20. The concentric hollow portion of the arm 14.2 inside the chamber 32 is provided with holes 22 'which lead to holes in the upper part of the reactor which are mixed. The flushing gas is led through line 25 to the chamber 32 and thus to the reactor.

An alternative to the embodiment of Figure 3 is shown in Figure 4. Here, the feed line 11 leads to a sealed feed chamber 33 located between the mixing machine 15.3 and the sealed wall 31.1 of the chamber 25 32. The feed chamber 33 communicates with the interior of the hollow arm 14.3.

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Claims (10)

Method for feeding liquid into a gas phase reactor, characterized in that the liquid is fed into the reactor through a mixer. v A method according to claim 1 for supplying liquid intended to be displaced in a reactor. A method according to any of claims 1 or 2 for supplying liquid obtained by condensing gas from a reactor. 4. A method according to any of claims 1 to 3 for feeding liquid into a fluidized bed reactor. A process for carrying out a polymerization process in a gas-phase reactor, one in which the gas is removed from the reactor, at least a portion of the gas removed is condensed into liquid, and at least part of the condensed liquid is recirculated in the gas phase reactor, characterized in that at least part of the gas is reacted. the liquid is redirected through the mixer into the reactor. The process of claim 5 for carrying out an olefin polymerization process. Apparatus for carrying out a chemical process in a gas phase reactor, the apparatus comprising a reactor (2), a rotary mixer (13) and a device for feeding liquid into the reactor, characterized in that the apparatus comprises a device (14; 14.1 ; 14.2; 14.3) for feeding the liquid through the mixer (13) into the reactor. Apparatus according to claim 7, wherein the mixer comprises a shaft (14; 14.1; 14.2; 14.3), advantageously a vertical shaft extending beyond the reactor. Apparatus according to claim 8, wherein the reactor comprises a bottom and the shank 25 (14; 14.1; 14.2; 14.3) extends beyond the bottom of the reactor. Apparatus according to any of claims 8 or 9, wherein the shaft (14; 14.1; 14.2; 14.3) is hollow for feeding fluid.