Ethylene Polymer Drying and Diluent Recovery Without Evaporator Bypass
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Solution Overview
Problem
Existing ethylene polymer production processes face challenges in efficiently and economically processing the mother liquor obtained after polymer particle separation, requiring multiple separation steps that are energy-intensive and inefficient.
Innovation Solution
A process that includes drying ethylene polymer particles with a gas stream, separating the hydrocarbon load from the gas stream to form a recover stream, and directly transferring this stream to a diluent distillation unit without passing an evaporator, while recycling a portion of the isolated diluent back to the polymerization reactors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the hydrocarbon recover stream is recycled to the produced suspension prior to separating polymer particles from mother liquor, then small polymer particles are prevented from being entrained in the gas exiting the powder dryer, but the amount of liquid to be evaporated increases
Solution Approach 1:
The invention extracts the hydrocarbon recover stream from the conventional recycling path and directs it directly to the diluent distillation unit, bypassing the evaporator. This extraction of the hydrocarbon stream from the liquid phase processing path eliminates the need to evaporate this portion of the liquid, thereby reducing energy consumption while maintaining polymer particle separation efficiency through alternative means.
Solution Approach 2:
The invention segments the hydrocarbon recover stream processing from the mother liquor processing paths. By separating these two streams and treating them through different routes (hydrocarbon stream to distillation unit, mother liquor through evaporator), the process optimizes energy usage by avoiding redundant evaporation of the hydrocarbon portion while maintaining effective polymer particle separation.
2Reliability
If multiple separation steps are used to remove side products and purify diluent from mother liquor, then the diluent can be recycled to polymerization, but the process becomes energy-intensive and inefficient
Solution Approach 1:
The invention performs preliminary separation by directing the hydrocarbon recover stream (which contains volatile components) directly to the diluent distillation unit before the evaporator stage. This preliminary action removes a significant portion of the liquid that would otherwise require energy-intensive evaporation, while still enabling effective diluent purification and recycling through the distillation process.
Solution Approach 2:
The diluent distillation unit serves as an intermediary processing step that receives the hydrocarbon recover stream directly, performing purification without requiring the intermediate evaporation step. This intermediary approach allows for effective diluent recovery and recycling while significantly reducing the overall energy consumption of the separation process.
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 reduces the amount of liquid to be evaporated, decreases energy consumption, and enhances the economic efficiency of the ethylene polymer production process by minimizing energy-intensive evaporation steps.
Implementation Method 1
drying the wet ethylene polymer particles by contacting the particles with a gas stream and thereby forming a gas stream carrying a hydrocarbon load
Implementation Method 2
which produces isolated diluent from the wax-depleted portion of the mother liquor
Data Source
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AI summary
A process for preparing an ethylene polymer in a suspension polymerization comprising separating the formed suspension of ethylene polymer particles in a solid-liquid separator into wet ethylene polymer particles and mother liquor, drying the wet ethylene polymer particles by a gas stream and forming a gas stream carrying a hydrocarbon load, and thereafter separating the hydrocarbon load from the gas stream and thereby forming a liquid hydrocarbon recover stream, transferring a part of the mother liquor into a work-up section comprising an evaporator for producing a wax-depleted portion of the mother liquor and comprising a diluent distillation unit, which produces isolated diluent from the wax-depleted portion of the mother liquor, wherein at least a part of the hydrocarbon recover stream is transferred to the diluent distillation unit without passing the evaporator for producing the wax-depleted portion of the mother liquor.