Partial Shutdown Phase in Ethylene Polymerization Reactors
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Solution Overview
Problem
Existing polymerization processes for ethylene homopolymers and copolymers often lead to total plant shutdowns due to adverse conditions, resulting in inefficiencies in energy, material usage, and increased downtime, while also failing to comply with environmental regulations.
Innovation Solution
A process that includes a polymerization phase followed by a partial shutdown phase, where the reactor pressure is reduced and then increased, utilizing a recycle connection and a combination of primary and secondary compressors, and adjusting initiator flow rates to manage pressure and fluid flow efficiently, thereby avoiding full shutdowns and minimizing environmental impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a total shutdown of the plant is performed to handle adverse conditions, then safety and compliance are ensured, but energy efficiency deteriorates, material waste increases, and downtime increases
Solution Approach 1:
The patent applies partial shutdown instead of total shutdown, where only the polymerization reactor is taken offline while other plant sections continue operating. This partial action maintains safety compliance for the affected reactor while avoiding the complete energy loss and material waste associated with total plant shutdown
Solution Approach 2:
The plant operation is segmented into independent sections, allowing the polymerization reactor to be shutdown separately from other units. This segmentation enables isolated handling of adverse conditions in one section without forcing shutdown of the entire plant, thereby preserving energy efficiency and reducing material waste
2Reliability
If a total shutdown of the plant is performed to handle adverse conditions, then safety and compliance are ensured, but productivity deteriorates due to increased downtime
Solution Approach 1:
The patent implements partial shutdown of only the affected polymerization reactor rather than total plant shutdown, significantly reducing downtime. The reactor can be quickly repressurized and returned to operation, maintaining high productivity while still ensuring safety compliance for the specific adverse condition
Solution Approach 2:
The patent performs preliminary repressurization of the reactor using the recycle connection and compressors before resuming polymerization. This preliminary action prepares the reactor for quick restart, minimizing downtime and maintaining productivity while ensuring safety compliance
3Speed
If reactor pressure is rapidly reduced during shutdown, then shutdown speed increases, but material waste increases due to hydrocarbon emission
Solution Approach 1:
The patent converts the harmful rapid pressure reduction that causes hydrocarbon emission into a beneficial controlled process. By using the recycle connection and compressors to manage pressure reduction, the system maintains fluid flow control, preventing uncontrolled emissions while still achieving rapid shutdown when needed
Solution Approach 2:
The recycle connection acts as an intermediary between the reactor and the environment during pressure reduction. It provides a controlled pathway for fluid flow, allowing rapid pressure equalization while preventing uncontrolled hydrocarbon emission to the atmosphere, thus reconciling shutdown speed with emission prevention
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 process reduces energy consumption, minimizes material waste, decreases downtime, and adheres to environmental regulations by allowing for a controlled partial shutdown and quick return to operation, while maintaining polymer quality.
Implementation Method 1
a recycle connection having an inlet in fluid communication with the reactor outlet side of the plant and an outlet in fluid communication with the reactor inlet side of the plant and having a flow of fluid from the reactor outlet side of the plant into the recycle connection and from the recycle connection to the reactor inlet side of the plant
Implementation Method 2
a combination of primary and secondary compressors
Data Source
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AI summary
A process for polymerizing ethylene to obtain an ethylene-based polymer in a plant, wherein the plant includes a reactor in fluid communication with a recycle connection, wherein the process comprises a polymerization phase, a partial shutdown phase, and the steps of reducing the pressure in the reactor for entering from the polymerization phase into the partial shutdown phase; and increasing the pressure in the reactor for exiting from the partial shutdown phase and re-entering the polymerization phase.