Swirl Generator for Fluidized Bed Coating
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Solution Overview
Problem
Existing fluidized bed apparatuses for particle-coating and granulating face challenges in optimizing the aerodynamic means for spray pattern and particle flow pattern, leading to issues like over-wetting, uneven-wetting, and agglomeration, due to uncontrolled air vortex and high radial velocity vectors, which affect the quality and efficiency of the coating process.
Innovation Solution
The introduction of a swirl generator that creates a rotational rising air stream near the sprayer, using a tubular sleeve with guiding slots to direct compressed air outwardly and upwardly, allowing particles to spin and travel in a rotational rising path, optimizing the spray and particle flow patterns while minimizing attrition and adhesions, and the use of dual partitions for separate particle size treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a diverting air stream with high radial velocity is used to push particles away from the nozzle, then the spray pattern development is improved and over-wetting is reduced, but particles may collide with the inner wall of the partition causing damage to coating film or granules
Solution Approach 1:
The patent introduces a second air stream flowing in the axial direction (vertical dimension) to complement the radial air stream. This creates a two-dimensional airflow control system where the axial stream carries particles upward along the partition wall, preventing them from colliding with the wall while the radial stream ensures proper spray pattern development.
2Manufacturing precision
If air vortex generators are used to improve particle contact with spray droplets, then coating uniformity is improved, but the high velocity vector impedes sufficient development of spray pattern and can cause over-wetting or agglomeration
Solution Approach 1:
The patent segments the air stream into two distinct components: a radial air stream for spray pattern development and an axial air stream for particle transport. This segmentation allows each air stream to be optimized independently, preventing the interference that occurs when a single vortex-generating stream tries to perform multiple functions.
3Productivity
If a stronger upward air stream is used to carry particles upward for coating, then coating efficiency is improved, but particle adhesion and agglomeration may occur due to insufficient spray pattern development
Solution Approach 1:
The radial air stream is introduced to preliminarily establish the spray pattern and disperse droplets before the particles are carried upward by the axial air stream. This preliminary action ensures that the spray pattern is fully developed and droplets are properly distributed before particles enter the spray zone, preventing adhesion and agglomeration.
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 solution enhances the development of spray and particle flow patterns, ensures uniform spraying, reduces particle collisions, and prevents adhesions, leading to improved coating quality and increased adaptability for different particle sizes, thus optimizing the fluidized bed apparatus's performance and expanding its application scope.
Implementation Method 1
the swirl generator comprises a tubular sleeve extending circumferentially around the sprayer body, an air chamber is defined between the sleeve and the sprayer body, and the sleeve comprises a plurality of guiding slots, the air from the source of compressed air via the air chamber is directed by the guiding slots to rotate outwardly
Implementation Method 2
a rotational rising air stream is generated in the partition under combined effect of the swirling air stream and the stronger upward air stream provided through the openings in larger dimension
Implementation Method 3
the particles are kept in a suspended semi-fluidized status by means of a weaker upward air stream passing through the surrounding area of the air distribution plate
Implementation Method 4
at least one sprayer which includes a sprayer body and a nozzle provided at its upper end, the lower end of said sprayer extending throughout the air distribution plate
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The present invention relates to a fluidized bed apparatus and a method for particle-coating or granulating, the fluidized bed apparatus includes a swirl generator which is mounted on a sprayer body in the fluidized bed apparatus and extends throughout an air distribution plate and is connected to a source of compressed air. The swirl generator comprises a tubular sleeve extending circumferentially around the sprayer body, and an air chamber is defined between the sleeve and the sprayer body, wherein the sleeve comprises a plurality of guiding slots. The air from the source of compressed air via the air chamber is directed by said guiding slots to rotate outwardly, so as to provide a swirling air stream circumferentially outwardly relative to the sprayer. The present invention can facilitate the development of the spray pattern and the particle flow pattern and allows the particles to spin respectively due to slight friction with the inner wall of the partition, thereby opportunities for the particles to obtain a more uniform spray when subsequently passing through the spray zone above the nozzle are increased, so that performance of the fluidized bed apparatus is improved.