Segmented Tubular Reactor for Ethylene Polymerization
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Solution Overview
Problem
The existing ethylene polymerization processes face limitations in increasing productivity while maintaining the physical properties of polymers, as raising reaction temperature risks ethylene decomposition and expanding compressor volume is constrained by motor load, limiting conversion rate and polymer production.
Innovation Solution
A continuous high-pressure ethylene polymerization method using a polymerization reaction zone divided into a primary and secondary zone, where the secondary zone is 1.5-6.5 times longer and 1.2-4 times larger in cross-sectional area than the primary zone, with specific initiator types and introduction points to control reaction efficiency and pressure drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the reaction temperature is raised to increase the conversion rate, then the polymer production increases, but the risk of ethylene decomposition occurring explosively increases
Solution Approach 1:
The polymerization reaction zone is divided into a primary reaction zone and a secondary reaction zone. The primary zone uses low-temperature initiators to start polymerization at safer temperatures, while the secondary zone uses high-temperature initiators to complete the conversion, thus achieving high productivity without explosive decomposition risks.
Solution Approach 2:
The invention changes the temperature parameters by using different initiators with different activation temperatures in different zones. Low-temperature initiators (activating at 50-100°C) are used in the primary zone, while high-temperature initiators (activating at 100-200°C) are used in the secondary zone, enabling controlled polymerization at safe temperature ranges.
2Productivity
If the volume of the compressor cylinder is expanded to increase the ethylene feed rate, then the polymer production increases, but the motor load increases requiring further considerations
Solution Approach 1:
The invention changes the conversion rate parameter by optimizing initiator types and concentrations in different zones, enabling higher conversion rates (40-90%) with the existing compressor capacity, thus increasing productivity without expanding compressor volume or increasing motor load.
3Productivity
If the conversion rate is increased to improve productivity, then the polymer production increases, but the physical properties of the resulted polymers may not be suitable for specific applications
Solution Approach 1:
The reaction zone is segmented into primary and secondary zones with different initiator systems. The primary zone produces polymer with certain molecular weight using low-temperature initiators, while the secondary zone adds more polymer chains using high-temperature initiators, enabling control over molecular weight distribution and physical properties while maintaining high conversion rates.
Solution Approach 2:
Different initiators with different temperature characteristics are applied locally in different zones. The primary zone uses low-temperature initiators for controlled polymerization, while the secondary zone uses high-temperature initiators for completing conversion, ensuring both high productivity and suitable polymer physical properties for specific applications.
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 method enhances productivity and maintains suitable polymer physical properties by optimizing reaction zones and initiator introduction, preventing excessive pressure drop and ensuring stable polymer production.
Implementation Method 1
low temperature initiator alone or initiator mixture containing mainly low temperature initiator is introduced into the primary reaction zone
Implementation Method 2
ethylene polymerization is a polymerization reaction conducted under the conditions of high temperature and high pressure
Implementation Method 3
excessively raising the reaction temperature to increase the conversion rate, there is a risk of ethylene decomposition being explosively occurred
Implementation Method 4
ethylene polymerization is a polymerization reaction conducted under the conditions of high temperature and high pressure
Data Source
AI summary
A method for continuous ethylene polymerization under high pressure using a polymerization reaction zone comprises a primary reaction zone and a secondary reaction zone wherein the secondary reaction zone has a length of 1.5-6.5 times the length of the primary reaction zone and a cross-sectional area of 1.2-4 times the cross-sectional area of the primary reaction zone. Ethylene is fed continuously into the primary reaction zone at the starting point of the primary reaction zone. Low temperature initiator alone, or an initiator mixture containing mainly low temperature initiator is introduced into the primary reaction zone at the starting point of the primary reaction zone. Initiator alone or an initiator mixture is introduced into the secondary reaction zone at two or more different points of the secondary reaction zone. Ethylene polymer products of various physical properties are produced with high productivity, while the pressure drop is minimized.