Liquid-Solid Sampling System for a Loop Slurry Reactor

Patent metadata

Field	Value
Publication number	US-2016347887-A1
Application number	US-201514726736-A
Country	US
Kind code	A1
Filing date	Jun 1, 2015
Priority date	Jun 1, 2015
Publication date	Dec 1, 2016
Grant date	—

Abstract

Polymerization reactor systems providing integrated liquid-solid sampling systems are disclosed. Methods for operating such polymerization reactor systems and for measuring a property of the liquid portion of liquid-solid mixture are described.

First claim

We claim:

1 . A process for operating a polymerization reactor system, the process comprising:
(I) contacting a transition metal-based catalyst system with an olefin monomer and an optional olefin comonomer in a loop slurry reactor within the polymerization reactor system under polymerization reaction conditions to produce an olefin polymer, the loop slurry reactor containing a liquid-solid mixture; (II) measuring a property of the liquid in the loop slurry reactor via a method comprising the steps of:
(i) withdrawing a sample of the liquid-solid mixture from the loop slurry reactor;
(ii) flowing the sample of the liquid-solid mixture through a vertical settling tube;
(iii) periodically stopping the flow of the sample of the liquid-solid mixture in the tube for a time period sufficient for the solid to settle to a bottom portion of the tube and for the liquid to occupy an upper portion of the tube;
(iv) removing a small fraction of the liquid in the upper portion of the tube and transferring the small fraction of the liquid to an analytical instrument for measuring the property of the liquid;
(v) restoring flow through the tube; and
(vi) returning an unused fraction of the sample of the liquid-solid mixture to the loop slurry reactor; and
(III) when the property of the liquid in the loop slurry reactor has reached a predetermined level, adjusting a polymerization reaction condition.

2 . The process of claim 1 , wherein the liquid-solid mixture is a slurry of solids in a liquid diluent.

3 . The process of claim 1 , wherein:
the time period is from about 1 sec to about 1 min; and a density difference between the solid and the liquid is at least 0.2 g/cc.

4 . The process of claim 1 , wherein:
the small fraction of the liquid contains less than 5 wt. % solids; and the amount of the small fraction of the liquid removed is less than 5 wt. %, based on the total amount of the liquid-solid mixture in the settling tube.

5 . The process of claim 1 , wherein:
the transition metal-based catalyst system is a chromium-based catalyst system, a Ziegler-Natta based catalyst system, a metallocene-based catalyst system, or a combination thereof; and the olefin monomer comprises a C 2 -C 24 olefin.

6 . The process of claim 1 , wherein the transition metal-based catalyst system is contacted with ethylene and an olefin comonomer comprising 1-butene, 1-hexene, 1-octene, or a mixture thereof.

7 . The process of claim 1 , wherein the polymerization reaction conditions comprise a polymerization reaction temperature in a range from about 60° C. to about 115° C., and a reaction pressure in a range from about 1.38 MPa to about 6.89 MPa.

8 . The process of claim 1 , wherein:
step (ii) is performed continuously for at least 1 min before step (iii) is conducted; and step (iii) is conducted at a pressure equivalent to that of the loop slurry reactor.

9 . The process of claim 1 , wherein:
in step (i), the sample is withdrawn from a discharge side of a reactor circulation pump; and in step (vi), the unused fraction is returned to a suction side of a reactor circulation pump.

10 . The process of claim 1 , wherein the process does not include a centrifuging step, a flashing step, or a sieving step.

11 . A polymerization reactor system comprising:
(A) a loop slurry reactor configured to contact a transition metal-based catalyst system with an olefin monomer and an optional olefin comonomer under polymerization reaction conditions to produce an olefin polymer; and (B) a liquid-solid sampling system comprising:
(a) an inlet valve and an inlet pipe for withdrawing a liquid-solid mixture from the loop slurry reactor;
(b) a vertical settling tube downstream of the inlet pipe, the tube configured to segregate the solid to a bottom portion of the tube and for the liquid to occupy an upper portion of the tube;
(c) an outlet valve and an outlet pipe for returning an unused fraction of the liquid-solid mixture to the loop slurry reactor, the outlet pipe downstream of the tube;
(d) a sample valve and a sample pipe, the sample valve positioned at the upper portion of the tube and configured to withdraw a small fraction of the liquid in the upper portion of the tube;
(e) an analytical instrument downstream of the sample pipe, the analytical instrument configured to measure a property of the liquid; and
(f) a controller (f1) configured to open the inlet valve and the outlet valve to permit flow of the liquid-solid mixture from the loop slurry reactor, through the inlet pipe and the tube, and returning to the loop slurry reactor through the outlet pipe; and (f2) configured to periodically stop flow of the liquid-solid mixture by closing the inlet valve and the outlet valve for a time period sufficient for the solid to settle to the bottom portion of the tube and for the liquid to occupy the upper portion of the tube, and subsequently opening the sample valve to withdraw the small fraction of the liquid.

12 . The system of claim 11 , wherein the reactor system comprises a single loop slurry reactor.

13 . The system of claim 11 , wherein the reactor system comprises two or more reactors, at least one of which is the loop slurry reactor.

14 . The system of claim 11 , wherein the analytical instrument is a gas chromatograph, a liquid chromatograph, a spectrometer, or a combination thereof.

15 . The system of claim 14 , further comprising a filter assembly before the analytical instrument.

16 . The system of claim 11 , further comprising a carrier gas inlet that enters the sample pipe after the sample valve and before the analytical instrument.

17 . The system of claim 11 , wherein the settling tube is configured to operate at a pressure equivalent to that of the loop slurry reactor.

18 . The system of claim 11 , wherein:
the time period is from about 15 sec to about 2 min; a density difference between the solid and the liquid is in a range from about 0.2 g/cc to about 1 g/cc; the small fraction of the liquid is less than 5 mL; the small fraction contains less than 1 wt. % solids; and the amount of the small fraction is less than 2 wt. %, based on the total amount of the liquid-solid mixture in the settling tube.

19 . The system of claim 11 , wherein the system does not contain a centrifuge, a flash drum, or a sieve.

20 . A method for measuring a property of a liquid in a vessel containing a liquid-solid mixture, the method comprising:
(i) withdrawing a sample of the liquid-solid mixture from the vessel; (ii) flowing the sample of the liquid-solid mixture through a vertical settling tube; (iii) periodically stopping the flow of the sample of the liquid-solid mixture in the tube for a time period sufficient for the solid to settle to a bottom portion of the tube and for the liquid to occupy an upper portion of the tube; (iv) removing a small fraction of the liquid in the upper portion of the tube and transferring the small fraction of the liquid to an analytical instrument for measuring the property of the liquid; (v) restoring flow through the tube; and (vi) returning an unused fraction of the sample of the liquid-solid mixture to the vessel.

Assignees

• Chevron Phillips Chemical Co Lp

Inventors

• Ege Stephen L
• Romig Ralph W

Classifications

• B01J19/2435

  Loop-type reactors · CPC title

• B01J19/2455

  provoking a loop type movement of the reactants (tubular loop-type reactors B01J19/2435; loop reactors having moving elements inside B01J19/1868) · CPC title

• C08F210/08

  Butenes · CPC title

• C08F2/14

  Organic medium · CPC title

• B01J8/08 Primary

  with moving particles (with fluidised particles B01J8/18) · CPC title