Venturi Initiator Nozzle for Ethylene Polymerization Mixing
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Solution Overview
Problem
Existing methods for injecting initiators into tubular reactors for ethylene-based polymerization face challenges such as uneven distribution, leading to unbalanced reaction profiles, high molecular weight polymer buildup, and undesirable reactions due to inadequate mixing and drag-induced laminar flow near reactor walls, which result in inconsistent product quality and potential system shutdowns.
Innovation Solution
The use of a Venturi-type initiator injection nozzle with a constricting and expanding portion to create a turbulent mixing zone, optimizing the initiator injection site's position relative to the process fluid flow center, and employing a shaped injector tip to ensure rapid and uniform dispersion of the initiator within the process fluid, minimizing laminar flow layers and reducing the formation of high molecular weight polymers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If initiator is injected directly into the process fluid without special nozzle design, then the injection system is simple, but the initiator distribution becomes uneven leading to unbalanced reaction profiles
Solution Approach 1:
The patent introduces an intermediary turbulent mixing zone between the initiator injection point and the main process fluid flow. This zone acts as a mediator that facilitates thorough mixing of initiator with process fluid before entering the reaction zone, eliminating uneven distribution without requiring complex multi-component injection systems
Solution Approach 2:
The patent changes the flow regime parameter from laminar to turbulent flow in the mixing zone. By creating turbulent flow conditions through the constricting and expanding portions of the nozzle, the mixing efficiency is dramatically improved, ensuring uniform initiator distribution throughout the process fluid
2Productivity
If the process fluid flows at high velocity through the reactor, then productivity is improved, but drag-induced laminar flow forms near walls causing undesirable reactions
Solution Approach 1:
The patent extracts the mixing function from the main reaction zone and places it in a separate turbulent mixing zone within the nozzle. This separation ensures that turbulent mixing occurs before the fluid enters the reaction zone, preventing laminar flow formation near walls during the high-velocity productive flow through the reactor
Solution Approach 2:
The patent performs preliminary turbulent mixing of the initiator with process fluid in the nozzle before the fluid enters the main reactor. This preliminary action ensures complete mixing occurs upstream, preventing the formation of laminar flow layers and associated harmful reactions during the high-velocity flow through the reaction zone
3Productivity
If initiator concentration is high at the injection site for efficient initiation, then reaction initiation efficiency is improved, but high molecular weight polymer buildup occurs causing clogging
Solution Approach 1:
The patent segments the flow into distinct zones: a high-concentration initiator injection zone for efficient initiation, followed by a turbulent mixing zone that rapidly disperses the initiator. This segmentation allows high initiator concentration where needed while preventing localized polymer buildup through immediate turbulent dispersion
Solution Approach 2:
The patent uses hydraulic principles to create turbulent flow through the constricting and expanding portions of the nozzle. This turbulent flow regime rapidly disperses the injected initiator throughout the process fluid, maintaining high initiation efficiency while preventing localized high molecular weight polymer formation that would cause clogging
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 enhances initiator mixing, reduces the likelihood of undesirable reactions, improves heat transfer efficiency, and increases single-pass conversion efficiency by preventing high molecular weight polymer buildup, leading to more consistent and efficient ethylene-based polymer production.
Implementation Method 1
The process fluid flow passage comprises a constricting portion, a throat, and an expanding portion in that order... creating a turbulent mixing zone
Implementation Method 2
The injector outlet is located in the constricting portion of the process fluid flow passage upstream of the throat... creating a turbulent mixing zone
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 2A~2B
AI summary
An initiator injection nozzle for mixing an initiator with a process fluid, comprising: a body comprising an inlet port to receive the process fluid, an outlet port, and an injector inlet to receive initiator; a process fluid flow passage through which the process fluid traverses between the inlet port and outlet port along a central process flow axis, further comprising a constricting portion, a throat, and an expanding portion in that order,- an initiator fluid flow passage through which the initiator traverses between the injector inlet and injector outlet along an injector central vertical axis, where the initiator fluid flow passage intersects the process fluid flow passage in the constricting portion; a stylus at least partially containing the initiator fluid flow passage and further comprising a shaped injector tip forming the injector outlet of the initiator fluid flow passage; where the injector outlet is located in the constricting portion of the process fluid flow passage and upstream of the throat by a horizontal offset as determined along the central process flow axis; and where the injector outlet is located off the central process flow axis by a vertical offset as determined along the injector central vertical axis