Catalyst Feed System

Abstract

The present invention relates to a process for feeding a polymerization catalyst into a polymerization reactor, said process comprising the steps of: (i) forming a catalyst slurry comprising oil and a solid catalyst component in a first catalyst preparation vessel; (ii) transferring the catalyst slurry from the first catalyst preparation vessel to a first catalyst feed vessel; (iii) maintaining the catalyst slurry in the first catalyst feed vessel in a homogeneous state; (iv) withdrawing a portion of the catalyst slurry from the first catalyst feed vessel, preferably continuously withdrawing the catalyst slurry from the first catalyst feed vessel, and introducing the withdrawn portion of the catalyst slurry into a polymerization reactor; wherein the oil has a dynamic viscosity of from 25 to 1500 mPa*s at the conditions within the first catalyst preparation vessel and the first catalyst feed vessel, wherein the catalyst slurry is transferred along a substantially vertical path downwards from the first catalyst feed vessel to the reactor.

Claims

1. A process for feeding a polymerization catalyst into a polymerization reactor, said process comprising the steps of: (i) forming a catalyst slurry comprising oil and a solid catalyst component in a first catalyst preparation vessel; (ii) transferring the catalyst slurry from the first catalyst preparation vessel to a first catalyst feed vessel; (III) maintaining the catalyst slurry in the first catalyst feed vessel in a homogeneous state; (iv) withdrawing a portion of the catalyst slurry from the first catalyst feed vessel and introducing the withdrawn portion of the catalyst slurry into a polymerization reactor; wherein the oil has a dynamic viscosity of from 25 to 1500 mPa*s at the conditions within the first catalyst preparation vessel and the first catalyst feed vessel, wherein the catalyst slurry is transferred along a substantially vertical path downwards from the first catalyst feed vessel to the reactor.

2. The process according to claim 1 comprising a second catalyst preparation vessel and wherein the catalyst slurry from the first catalyst preparation vessel and the second catalyst preparation vessel is transferred to the first catalyst feed vessel via a first catalyst transfer line.

3. The process according to claim 1 comprising a second catalyst preparation vessel, a first catalyst feed vessel and a second catalyst feed vessel, wherein the catalyst slurry of the first catalyst preparation vessel is transferred to the first catalyst feed vessel via a first catalyst transfer line and the catalyst slurry of the second catalyst preparation vessel is transferred to the second catalyst feed vessel via a second catalyst transfer line.

4. The process according to claim 1, wherein the catalyst slurry from the first catalyst feed vessel and/or the second catalyst feed vessel is transferred into the polymerization reactor by using at least one valveless piston pump; and/or wherein the catalyst feed vessel(s) are located vertically above or diagonally above the polymerization reactor.

5. The process according to claim 1, wherein the oil is white oil; and/or wherein the oil has a dynamic viscosity of from 30 to 1500 mPa*s at the conditions within the first catalyst preparation vessel and/or the second catalyst preparation vessel and the first catalyst feed vessel and/or the second catalyst feed vessel; and/or wherein the catalyst fed to the first catalyst preparation vessel and/or the second catalyst preparation vessel is a dry catalyst powder; and/or wherein the concentration of the catalyst in the slurry is between 10 to 40 wt. %, based on the total amount of slurry.

6. The process according to claim 1, wherein the catalyst is selected from the group consisting of Ziegler-Natta catalysts, metallocene catalysts, late transition metal catalysts and mixtures thereof.

7. The process according to claim 1, wherein the transport from the first catalyst preparation vessel to the first catalyst feed vessel and/or from the second catalyst preparation vessel to the second catalyst feed vessel is done batchwise.

8. The process according to claim 2, wherein the at least one transfer line can be emptied using oil and/or N.sub.2.

9. The process according to claim 3 comprising the step of monitoring the level of the catalyst slurry by means of a level sensor in the first catalyst feed vessel and the second catalyst feed vessel; and/or the step of monitoring the level of the catalyst slurry by means of a level sensor in the first catalyst preparation vessel and the second catalyst preparation vessel.

10. The process according to claim 9 comprising the steps of stopping the withdrawal of the catalyst slurry from one of the first catalyst feed vessel and the second catalyst feed vessel, and starting the withdrawal of the catalyst slurry from the other one of the first catalyst feed vessel and the second catalyst feed vessel in response to the signal from the level sensor.

11. A process for producing olefin polymers in a polymerization reactor comprising the steps of feeding the polymerization catalyst into the polymerization reactor by using the process of claim 1.

12. The process for producing olefin polymers in a polymerization reactor according to claim 11 comprising the steps of (i) continuously introducing at least one olefin monomer into the polymerization reactor; (ii) optionally, continuously introducing diluent and/or hydrogen into the polymerization reactor; (iii) operating the polymerization reactor in such conditions that the at least one olefin monomer is polymerized by the polymerization catalyst to form a reaction mixture containing the catalyst, unreacted monomer(s), formed polymer and optionally diluent and/or hydrogen; and (iv) optionally, withdrawing a portion of the reaction mixture from the polymerization reactor.

13. An olefin polymer obtainable by the process according to claim 11.

14. A catalyst slurry feeding system for producing olefin polymers in a polymerization reactor comprising a first catalyst preparation vessel for forming a catalyst slurry comprising oil and a solid catalyst component; a first catalyst feed vessel for maintaining the catalyst slurry in a homogenous state; a polymerization reactor; a first transfer line connecting the first catalyst preparation vessel to the first catalyst feed vessel; a first feed line connecting the first catalyst feed vessel to the polymerization reactor; wherein the first feed line is provided with a pump; and wherein the first catalyst feed vessel is located above the polymerization reactor.

15. The system according to claim 14, wherein the system comprises a second catalyst preparation vessel and wherein the first catalyst preparation vessel is connected to a first catalyst feed vessel via a first transfer line and the second catalyst preparation vessel is connected to a second catalyst feed vessel via a second transfer line; and/or wherein the catalyst feed vessel(s) is located at a point above the injection point of the polymerization reactor.

16. The process according to claim 1, wherein the withdrawing comprises continuously withdrawing the catalyst slurry from the first catalyst feed vessel.

17. The process according to claim 5, wherein the oil is food approved white oil.

18. The process according to claim 5, wherein the oil has a dynamic viscosity of from 35 to 990 mPa*s.

19. The process according to claim 5, wherein the concentration of the catalyst in the slurry is between 15 and 30 wt. %.

20. The process according to claim 5, wherein the concentration of the catalyst in the slurry is between 20 and 25 wt. %.

Description

[0109] FIG. 1 shows a system of the inventive process including a catalyst preparation vessel, a catalyst feed vessel, a catalyst feed pump and a polymerization reactor.

[0110] FIG. 2 shows another system of the inventive process including two catalyst preparation vessels, two catalyst feed vessels, two catalyst feed pumps and a polymerization reactor.

[0111] FIG. 3 shows a system of the inventive process with crossing transfer lines, crossing feed lines and two switching systems.

[0112] Unless explicitly described otherwise, the description of the present invention is to be understood so that one or more of any of the above described preferred embodiments of the invention can be combined with the invention described in its most general features. In addition, it will be appreciated that variants of the above-disclosed and other features and functions, or alternatives thereof, may be combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the present claims.

DESCRIPTION OF THE FIGURES

[0113] FIG. 1 shows an example of the inventive process. The process includes a catalyst preparation vessel (1), a catalyst feed vessel (3), a catalyst feed pump (4) and a polymerization reactor (6). The catalyst preparation vessel (3) can be located on ground level for easy access. In the catalyst preparation vessel (1) the catalyst slurry is formed and then said catalyst slurry is transferred to the catalyst feed vessel (3) via a catalyst transfer line 2. The transport from the catalyst preparation vessel to the catalyst feed vessel can be done batchwise. Preferably the catalyst feed vessel (3) is located at a level which is above the level of the catalyst preparation vessel (1). Thereby the transfer of the catalyst slurry from the catalyst preparation vessel (1) to the catalyst feed vessel (3) occurs substantially upwards. Meanwhile, the catalyst slurry in a homogeneous state, is withdrawn from the bottom of the operating catalyst feed vessel (3). The withdrawn portion of the catalyst slurry is transferred by using for example a valveless piston pump (4) via the feed line (5) to the polymerization reactor (6). The catalyst feed vessel (3) is located above the polymerization reactor (6).

[0114] FIG. 2 shows another embodiment of the inventive process. This process includes two catalyst preparation vessels (11,12), two catalyst feed vessels (31,32), two catalyst feed pumps (41,42) and a polymerization reactor (6). The catalyst slurry of the first catalyst preparation vessel (11) is transferred to the first catalyst feed vessel (31) via a first catalyst transfer line (21) and the catalyst slurry of the second catalyst preparation vessel (12) is transferred to the second catalyst feed vessel (32) via a second catalyst transfer line (22). Preferably the catalyst feed vessels (31,32) are located at a level which is above the level of the polymerization reactor (6). The withdrawn portions of the catalyst slurry from the catalyst feed vessels (31,32) are transferred via the two feed lines (51,52) to for example two valveless piston pumps (41,42) and then transferred via the two reactor feed lines (71,72) to the polymerization reactor (6).

[0115] FIG. 3 shows another embodiment of the inventive process. FIG. 3 shows a flow sheet which is similar to the system shown in FIG. 2. However, in the system shown in FIG. 3 the first and second catalyst transfer lines (211,212 & 221,222) connecting the first and the second catalyst preparation vessel (11,12) and the first and second catalyst feed vessels (31,32) cross each other. The first and second feed lines (511,512 & 521,522) from the first and second catalyst feed vessels (31,32) to the valveless piston pumps (41,42) are also crossing each other.

[0116] The catalyst slurry of the first catalyst preparation vessel (11) is transferred to the first catalyst feed vessel (31) via a first catalyst transfer line (211,212), thereby passing a first switching system (23), which is located between the first part of the first transfer line (211) and the second part of the first transfer line (212). The switching system (23) comprises two or more valves and can be set so that the catalyst slurry is transferred via the second part of the first catalyst transfer line (212) to the first catalyst feed vessel (31) or via the second part of the second catalyst transfer line (222) to the second catalyst feed vessel (32). The catalyst slurry of the second catalyst preparation vessel (12) is transferred to the first catalyst feed vessel (32) via the first part of the first catalyst transfer line (221) thereby passing the first switching system (23). The first switching system (23) can be set so that the catalyst slurry is transferred via the second part of the second catalyst transfer line (222) to the second catalyst feed vessel (32) or via the second part of the first catalyst transfer line (212) to the first catalyst feed vessel (31).

[0117] The withdrawn portions of the catalyst slurry from the catalyst feed vessels (31,32) are transferred via the first and second feed lines (511,512 & 521,522) and a second switching system (53) to the valveless piston pumps (41,42) and then transferred via the two reactor feed lines (71,72) to the polymerization reactor (6). The withdrawn portion from the catalyst feed vessel (31) is transferred via the first part of the first feed line (511) to the second switching system (53) and then via the second part of the first feed line (512) to the valveless piston pump (41) or via the second part of the second feed line (522) to the other valveless piston pump (42). The withdrawn portions from the catalyst feed vessel (32) can be transferred via the first part of the second feed line (521) to the second switching system (53) and then via the second part of the second feed line (522) to the valveless piston pump (42) or via the second part of the first feed line (512) to the other valveless piston pump (41). The desired lines can be selected via the switching systems. This process provides even more flexibility with respect to the preparation and feeding of catalyst slurry.

LIST OF REFERENCE SKINS

[0118] 1 catalyst preparation vessel [0119] 11 first catalyst preparation vessel [0120] 12 second catalyst preparation vessel [0121] 2 catalyst transfer line [0122] 21 first catalyst transfer line [0123] 211 first part of first catalyst transfer line [0124] 212 second part of first catalyst transfer line [0125] 22 second catalyst transfer line [0126] 221 first part of second catalyst transfer line [0127] 222 second part of second catalyst transfer line [0128] 23 first switching system [0129] 3 catalyst feed vessel [0130] 31 first catalyst feed vessel [0131] 32 second catalyst feed vessel [0132] 4 catalyst feed pump [0133] 41 first catalyst feed pump [0134] 42 first catalyst feed pump [0135] 5 feed line [0136] 51 first feed line [0137] 511 first part of first feed line [0138] 512 second part of first feed line [0139] 52 second feed line [0140] 521 first part of second feed line [0141] 522 second part of second feed line [0142] 53 second switching system [0143] 6 polymerization reactor [0144] 7 reactor feed line [0145] 71 first reactor feed line [0146] 72 second reactor feed line