Polymer Slurry Concentration in Loop Reactors

Solution Overview

Problem

Existing methods for concentrating polymer slurry from loop reactors, particularly in cascaded reactors, are unsatisfactory, leading to larger gas flow and equipment sizes in subsequent flash gas compressors and distillation sections, resulting in higher investment and operational costs.

Innovation Solution

A process that increases the concentration of polymer slurry before a flash unit, using a hydrocyclone to separate and recycle streams, reducing the gas flow to the flash gas compressor and subsequent distillation section, thereby reducing equipment size and energy consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If traditional settling legs are used to concentrate polymer slurry, then the slurry concentration is increased, but the equipment size and gas flow to subsequent flash gas compressor and distillation section become larger

Engineering Contradiction:

Improvepolymer slurry concentrationVSAvoidequipment size

Core Design Contradiction:

Quantity of substanceVSVolume of stationary object

Solution Approach 1:

The patent extracts and removes the diluent (inert hydrocarbon solvent) from the polymer slurry in a separate decanter unit before the flash gas compressor and distillation section. This pre-concentration step removes the majority of diluent early in the process, thereby reducing the gas flow and equipment size requirements for subsequent flash gas compression and distillation operations.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent segments the slurry concentration process into two distinct stages: first, a decanter unit that performs initial diluent removal and concentrates the slurry; second, the traditional flash gas compressor and distillation section that handles the already-concentrated slurry. This segmentation allows each unit to be optimized for its specific function, reducing overall equipment size.

Inventive Principle:

Principle #1Segmentation

2Quantity of substance

If traditional settling legs are used to concentrate polymer slurry, then the slurry concentration is increased, but energy consumption increases

Engineering Contradiction:

Improvepolymer slurry concentrationVSAvoidenergy consumption

Core Design Contradiction:

Quantity of substanceVSUse of energy by moving object

Solution Approach 1:

The patent extracts and removes the diluent (inert hydrocarbon solvent) from the polymer slurry in a separate decanter unit before the flash gas compressor and distillation section. This pre-concentration step removes the majority of diluent early in the process, thereby reducing the gas flow and equipment size requirements for subsequent flash gas compression and distillation operations.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent segments the slurry concentration process into two distinct stages: first, a decanter unit that performs initial diluent removal and concentrates the slurry; second, the traditional flash gas compressor and distillation section that handles the already-concentrated slurry. This segmentation allows each unit to be optimized for its specific function, reducing overall equipment size.

Inventive Principle:

Principle #1Segmentation

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach results in smaller, more economical process equipment, reduced energy consumption, and a more environmentally friendly process by minimizing the size of the flash gas compressor and separation units.

Implementation Method 1

passing the polymer slurry to a separation device for polymer particles, such as a hydrocyclone, to provide a concentrated slurry and an overhead stream

Methodology Applied

Scientific EffectHydrocyclone separation: Cyclone Separation

Implementation Method 2

conducting a second part of the concentrated slurry to a high pressure flash unit to separate the slurry into polymer and overhead gas

Methodology Applied

Scientific EffectFlash separation: Flash Evaporation

Implementation Method 3

compressing the overhead gas stream in a flash compressor

Methodology Applied

Scientific EffectGas compression: Gas Compressor

Implementation Method 4

passing the compressed flash gas stream into a heavies column in order to separate oligomers and other heavy components from the gas stream

Methodology Applied

Scientific EffectDistillation: Distillation

Implementation Method 5

directing at least a part of the liquid phase of the flash vessel into a lights column in order to separate the low-boiling components from the liquid phase

Methodology Applied

Scientific EffectDistillation: Distillation

Data Source

PatentUS7740808B2Process and apparatus for producing olefin polymers

Publication Date: 2010.06.22 BOREALIS TECH OY

AI summary

The present invention concerns a process and an apparatus for continuous polymerisation of olefin monomers. In particular, the present invention concerns a process and an apparatus for continuous polymerisation olefin monomers like ethylene and other monomers, wherein an olefin monomer is polymerised in slurry phase in an inert hydrocarbon diluent in at least one loop reactor. According to the invention, a polymer slurry is continuously withdrawn from the loop reactor and concentrated. The concentrated slurry is conducted to a flash unit in order to remove the remaining fluid phase, and gas obtained is compressed in a flash gas compressor before it is being fed to a distillation section. By means of the present invention it is possible reduce the size of the flash gas compressor and the capacity of the distillation sections. This significantly reduces investment cost for a continuously operated polymerization apparatus.