Pipe-in-Pipe Mixing Device for Polyethylene Reactors
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Solution Overview
Problem
Existing mixing devices for high-pressure ethylene reactors are complex and costly to fabricate, while achieving a comparable degree of mixing and pressure drop to static mixers, which are essential for preparing ethylene-based polymers like LDPE.
Innovation Solution
A mixing device with a pipe-in-pipe structure, featuring an outer pipe and an inner pipe with tangential flow generation in an annular space, utilizing inner flow inlets positioned higher than the outer flow inlet to enhance mixing, allowing for a compact and cost-effective design suitable for laminar flow conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If complex static mixer structures are used to achieve desired mixing degree, then mixing quality is improved, but fabrication cost and device complexity increase
Solution Approach 1:
The mixing device is divided into multiple functional sections: a supply section with multiple supply inlets for different substances, and a pipe-in-pipe mixing section with an outer pipe and inner pipe. This segmentation allows each section to perform its specific function efficiently while maintaining overall simplicity.
Solution Approach 2:
The mixing device employs a pipe-in-pipe configuration where the inner pipe is nested within the outer pipe, forming an annular space between them. This nested structure enables compact design while providing distinct flow paths for different substances, achieving effective mixing without complex external components.
2Productivity
If tangential flow is generated in annular space to enhance mixing, then mixing efficiency is improved, but device design complexity increases
Solution Approach 1:
The supply inlets are positioned at different heights and orientations to dynamically generate tangential flow patterns in the annular space. This dynamic flow generation enhances mixing efficiency without requiring additional moving parts or complex mechanical components.
Solution Approach 2:
The supply inlets are arranged in three-dimensional space with different vertical positions and angular orientations. This spatial arrangement creates tangential flow components that enhance mixing in multiple dimensions, improving mixing efficiency while maintaining structural simplicity.
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
The device achieves a comparable degree of mixing and pressure drop to static mixers while being more compact and cost-effective, with a simpler structure, and operates efficiently in laminar low Reynolds number conditions, suitable for preparing ethylene-based polymers.
Implementation Method 1
the outer flow inlet being provided such that a tangential flow is generated in the annular space during use
Implementation Method 2
The mixing device according to the invention is particularly suitable for making such mixture in a flow having a Reynolds number of at most 1000. Thus, the mixing device according to the invention can make a mixture in a generally laminar low.
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
The invention relates to a mixing device comprising: - a supply section (200), and - a pipe-in-pipe section (100) comprising: - an outer pipe (110) extending vertically and - an inner pipe (120) having a closed top end and having an outlet for the mixture at a bottom end, wherein the inner pipe (120) is arranged concentrically to the outer pipe (110) inside the outer pipe (110) such that an annular space (130) is formed between the outer pipe (110) and the inner pipe (120), wherein the annular space has a closed top end and a closed bottom end, wherein the inner pipe (120) is provided with at least two inner flow inlets (121, 122) for receiving a flow from the annular space (130) into the inner pipe, wherein the outer pipe (110) is provided with an outer flow inlet (111) for receiving a flow from the supply section (200) into the annular space, the outer flow inlet (111) being provided such that a tangential flow is generated in the annular space (130) during use, wherein the two or more inner flow inlets are provided closer to the top end of the annular space than the outer flow inlet.