Ethylene Polymer Suspension Workup for Heat Exchanger Fouling Prevention
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Solution Overview
Problem
The fouling of heat exchangers due to deposits during the heating of mother liquor in the work-up process of ethylene polymerization, leading to decreased efficiency and frequent cleaning, which results in downtime of the polymerization system.
Innovation Solution
A process involving the addition of a protic agent, such as water or alcohol, to the mother liquor before evaporation, followed by a circulating evaporation unit with a heat exchanger and separation vessel, to prevent fouling and facilitate the recycling of a wax-depleted portion of the mother liquor back into the polymerization process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the mother liquor is heated in heat exchangers for evaporation and distillation steps, then the unwanted components are removed and the diluent is purified, but the heat exchangers become fouled with deposits and their heat exchange efficiency decreases
Solution Approach 1:
The patent extracts and removes the harmful deposits from the heat exchanger surfaces through cleaning operations. By taking out the fouling substances (waxes, oligomers, and other solids) that accumulate during operation, the heat exchanger efficiency is restored and maintained, resolving the contradiction between continuous purification needs and equipment fouling.
Solution Approach 2:
The patent implements preliminary cleaning actions before the fouling becomes severe. By performing regular cleaning operations and maintenance procedures, the heat exchanger surfaces are kept clear of deposits, preventing the efficiency degradation that would otherwise occur during continuous operation.
2Reliability
If frequent cleaning of the heat exchangers is performed to maintain efficiency, then the heat exchange performance is preserved, but the polymerization system experiences downtime
Solution Approach 1:
The patent performs cleaning operations during scheduled maintenance periods rather than allowing fouling to accumulate to critical levels. By planning and executing cleaning actions in advance during appropriate downtime windows, the system minimizes the impact on continuous polymerization operations.
Solution Approach 2:
The patent attempts to minimize the time required for cleaning operations by using efficient cleaning methods and procedures. By rushing through the necessary cleaning steps as quickly as possible without compromising thoroughness, the downtime impact on the polymerization system is reduced.
3Manufacturing precision
If the mother liquor is worked up to remove side products, then the polymerization process is cleaned of unwanted components, but the process complexity and equipment requirements increase
Solution Approach 1:
The patent designs the work-up section equipment to perform multiple functions. The evaporation unit, for example, serves both to remove unwanted components and to concentrate the diluent for recycling. By making the equipment multi-functional, the overall system complexity is reduced while maintaining effective side product removal capabilities.
Solution Approach 2:
The patent combines multiple separation and purification operations into integrated units. The evaporation unit combines heating, separation, and concentration functions, while the distillation unit integrates fractionation and purification. By merging these operations, the equipment complexity is reduced compared to having separate dedicated equipment for each function.
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
Prevents fouling in heat exchangers, enhances the efficiency of the evaporation process, and allows for the effective recycling of purified diluent and components back into the polymerization reactors, reducing downtime and maintaining system performance.
Implementation Method 1
a protic agent is added to the part of the mother liquor which is transferred into the work-up section... Prevents fouling in heat exchangers
Implementation Method 2
an evaporation unit for producing a wax-depleted portion of the mother liquor... a circulating evaporation unit with a heat exchanger
Implementation Method 3
a circulating evaporation unit with a heat exchanger... heating occurs in heat exchangers
Implementation Method 4
separation vessel... the suspension is separated into ethylene polymer particles and mother liquor
Data Source
AI summary
A process for preparing an ethylene polymer in a suspension polymerization including the steps of separating the formed suspension of ethylene polymer particles in a solid-liquid separator into ethylene polymer particles and mother liquor, transferring a first part of the mother liquor into a work-up section including an evaporation unit for producing a wax-depleted portion of the mother liquor, wherein a protic agent is added to the part of the mother liquor which is transferred into the work-up section, and recycling a first part of the wax-depleted portion of the mother liquor to the polymerization reactor or the series of polymerization reactors.