Inert Gas Partial Pressure Control in Polymerization

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

In gas phase polymerization processes, maintaining minimum reactor pressure to prevent product polymer carry-over and minimize compressor energy usage results in limited efficiency of inert gas removal, leading to increased losses of unreacted monomers and induced condensing agents.

Innovation Solution

Increasing the inert gas partial pressure independently of other operating parameters, up to the maximum safe pressure, to enhance the efficiency of inert gas removal in the output gas stream, thereby reducing losses of unreacted monomers and induced condensing agents.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If minimum total reactor pressure is maintained to prevent product polymer carry-over and minimize compressor energy usage, then compressor energy usage and product polymer carry-over are reduced, but inert gas removal efficiency decreases leading to increased hydrocarbon losses

Engineering Contradiction:

Improvecompressor energy usageVSAvoidhydrocarbon losses

Core Design Contradiction:

Loss of energyVSLoss of substance

Solution Approach 1:

The patent changes the inert gas partial pressure parameter independently from total reactor pressure to optimize inert gas removal efficiency. By adjusting the inert gas partial pressure specifically, the system achieves improved inert gas removal without necessarily increasing total reactor pressure, thus resolving the contradiction between compressor energy usage and hydrocarbon losses

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent segments the pressure control into two independent components: total reactor pressure control and inert gas partial pressure control. This allows separate optimization of each parameter - maintaining minimum total pressure for energy efficiency while independently increasing inert gas partial pressure for improved removal efficiency, thereby resolving the contradiction

Inventive Principle:

Principle #1Segmentation

2Object-generated harmful factors

If minimum total reactor pressure is maintained to prevent product polymer carry-over, then product polymer carry-over is reduced, but inert gas removal efficiency decreases leading to increased hydrocarbon losses

Engineering Contradiction:

Improveproduct polymer carry-overVSAvoidhydrocarbon losses

Core Design Contradiction:

Object-generated harmful factorsVSLoss of substance

Solution Approach 1:

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent segments the pressure control into two independent components: total reactor pressure control and inert gas partial pressure control. This allows separate optimization of each parameter - maintaining minimum total pressure for preventing product polymer carry-over while independently increasing inert gas partial pressure for improved removal efficiency, thereby resolving the contradiction

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 decreases hydrocarbon losses by optimizing inert gas partial pressure, reducing raw material intensity and operational costs without causing product polymer carry-over, while maintaining polymer production reliability.

Implementation Method 1

The venting system may include a separation device for separating the inert gas from unreacted monomer and induced condensing agent

Methodology Applied

Scientific EffectPartial pressure:

Implementation Method 2

The compressor acts as a blower that blows the gas through cooler. The polymerization reaction is an exothermic reaction, that is it releases heat, and the cooler is a heat exchanger that removes heat from the recycle stream through heat transfer

Methodology Applied

Scientific EffectHeat transfer:

Implementation Method 3

In condensed mode operation, the recycle stream is cooled to a temperature below the dew point of the recycle stream, resulting in condensing a portion of the recycle stream

Methodology Applied

Scientific EffectCondensation: Condensation

Data Source

PatentUS11618793B2Optimized inert gas partial pressure in a gas phase polymerization process

Publication Date: 2023.04.04 EXXONMOBIL CHEMICAL PATENTS INC

AI summary

Gas phase polymerization processes include contacting an input stream comprising a monomer and an induced condensing agent in the presence of an inert gas with a catalyst in a fluidized bed reactor to produce a polymer, unreacted monomer, and an output gas; recycling a recycle stream of the unreacted monomer from the reactor to the input stream; venting at least a portion of the output gas from the reactor; and maintaining a partial pressure of the inert gas in the reactor above a reference inert gas pressure to decrease losses of the recycle stream with the vented output gas. The processes may include controlling the inert gas partial pressure to vary the total reactor pressure up to the maximum safe pressure, without causing carry-over of product polymer.