Effervescent Nozzle for Catalyst Injection in Olefin Polymerization
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Solution Overview
Problem
Existing nozzles for catalyst injection in olefin polymerization face challenges such as uneven catalyst distribution, accelerated polymer growth, and particle accumulation, leading to fouling and unpredictable reactor performance, especially with highly active catalysts that polymerize quickly and form agglomerates.
Innovation Solution
A nozzle design featuring a first conduit with a tapered section and an injection tip, surrounded by a second conduit with radially and axially spaced orifices, and a support member, which allows for controlled catalyst slurry and inert gas flow to prevent agglomeration and ensure uniform dispersion within the reactor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If liquid catalyst is injected directly into the reactor, then catalyst injection is simple, but catalyst dispersal is uneven and polymer particles grow too large
Solution Approach 1:
The nozzle divides the liquid catalyst stream into multiple smaller streams through multiple injection holes, and further atomizes them into droplets using compressed gas. This segmentation prevents uneven dispersal and controls particle growth by distributing catalyst more uniformly throughout the reactor.
Solution Approach 2:
Compressed gas is introduced as an intermediary substance between the liquid catalyst and the polymer particles. The gas atomizes the liquid catalyst into fine droplets and carries them into the reactor, improving dispersal uniformity while preventing direct contact that would cause rapid polymerization and particle growth.
2Productivity
If high concentration of catalyst is used to increase productivity, then polymer production increases, but particle agglomeration and fouling worsen
Solution Approach 1:
Compressed gas is used to atomize the liquid catalyst into fine droplets and transport them into the reactor. This pneumatic delivery method ensures that even at high catalyst concentrations, the catalyst is distributed as discrete droplets rather than a continuous stream, preventing particle agglomeration and fouling while maintaining high productivity.
Solution Approach 2:
The physical state of catalyst delivery is changed from liquid stream to atomized droplets through compression and shearing forces. This parameter change in the catalyst delivery form allows higher catalyst concentrations to be used without causing agglomeration, as the droplet morphology prevents coalescence and subsequent particle growth.
3Productivity
If catalyst injection rate is increased to maintain production, then productivity is maintained, but particle size increases and fluidization is lost
Solution Approach 1:
The injection system segments the catalyst flow into multiple holes, each creating a separate stream that is further broken into droplets. This segmentation allows high total injection rates while maintaining small individual droplet sizes, preventing particle agglomeration and maintaining fluidization even at high productivity levels.
Solution Approach 2:
Compressed gas provides the mechanical energy to atomize the liquid catalyst into fine droplets at high injection rates. The pneumatic atomization ensures that increased catalyst injection rate does not lead to increased droplet size or particle agglomeration, thereby maintaining particle fluidization and preventing reactor shutdown.
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 nozzle design ensures uniform and repeatable catalyst injection, controlling polymer growth and particle size, reducing fouling and reactor shutdowns by creating small droplets that are well dispersed in the fluidized bed, thereby maintaining consistent polymer production.
Implementation Method 1
The effervescent nozzle atomizes the liquid catalyst into fine droplets using compressed gas
Implementation Method 2
uniform dispersion within the fluidized bed
Implementation Method 3
A three-dimensional computational fluid dynamics (CFD) study was conducted to model the effervescent flow patterns within the nozzle
Implementation Method 4
The CFD simulations revealed that the tapered section and multiple orifices created effervescent flow patterns
Data Source
Figure 1~1A
Figure 2~4
Figure 5
AI summary
A nozzle for catalyst injection for olefin polymerization is provided. In one or more embodiments the nozzle includes a first conduit including a body, a tapered section, and an injection tip. The nozzle also includes a second conduit having an inner surface and an outer surface. The first conduit is disposed about the second conduit defining a first annulus therebetween. The nozzle further includes a support member at least partially disposed about the outer surface of the first conduit defining a second annulus therebetween. The support member has a converging outer surface at a first end thereof.