Electrospray Device for Fluidized Bed Coating and Spray-Drying
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Solution Overview
Problem
Existing fluidized bed apparatuses face challenges in achieving uniform coating and spray-drying due to non-uniform electric fields and unstable charging of particles, leading to inefficiencies and quality issues in both coating and spray-drying processes.
Innovation Solution
The integration of an electrospray device with a charged nozzle and partition, along with a magnetic field generator, generates a controlled electromagnetic and magnetic field to stabilize particle charging and optimize the motion of charged droplets and particles, ensuring uniform coating and efficient spray-drying through Coulombic fission and rotational upward paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an electrospray device with charged nozzle and partition is used, then particle charging stability and coating uniformity are improved, but device complexity increases
Solution Approach 1:
The apparatus is divided into distinct functional zones: a charged nozzle for electrospray generation, a partition structure creating separate spray and fluidization regions, and a charged partition for particle charging. This segmentation allows each component to perform its specific function optimally, improving coating uniformity while maintaining manageable complexity through modular design.
Solution Approach 2:
A magnetic field generator is introduced as an intermediary component to generate a magnetic field that works in conjunction with the electric field from the charged nozzle and partition. This magnetic field mediator helps stabilize particle charging and control droplet motion, enhancing coating uniformity without requiring direct modification of the electrospray system itself.
2Productivity
If a magnetic field generator is added to the electrospray device, then particle motion control and spray pattern development are improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The magnetic field generator is integrated with the existing electrospray device structure, combining electromagnetic field generation capabilities into a unified system. This merging allows the magnetic field to work synergistically with the electric field from the charged components, improving spray pattern development and particle motion control while avoiding the need for completely separate systems.
Solution Approach 2:
The charged partition structure serves multiple functions: it acts as an electrode for particle charging, creates a defined spray zone geometry, and works with the magnetic field generator to control particle motion. This multi-functionality reduces the need for additional dedicated components, offsetting the complexity increase from adding the magnetic field generator.
3Adaptability or versatility
If electrospray is applied to both coating and spray-drying processes, then process versatility is improved, but operation complexity increases
Solution Approach 1:
The system employs dynamic control of voltage polarity between the charged nozzle and partition, allowing the same apparatus to be switched between coating mode (attractive electrostatic force) and spray-drying mode (repulsive electrostatic force). This dynamic reconfiguration enables process versatility without requiring physically different equipment for each application.
Solution Approach 2:
The versatility between coating and spray-drying processes is achieved by changing key operating parameters: the voltage polarity and magnitude applied to the nozzle and partition, the liquid flow rate, and the particle feed rate. These parameter adjustments allow the same electrospray device to optimize performance for different process requirements without structural modifications.
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 results in improved particle size distribution, reduced agglomeration, and enhanced coating quality, with the ability to produce ultrafine particles and guide them efficiently for collection, addressing the inefficiencies and quality issues in previous methods.
Implementation Method 1
a power supply directly or indirectly connected between the nozzle and the partition to apply voltage
Implementation Method 2
the liquid supplied to the end of the emission electrode is charged, in order to release charged droplets from the end of the emission electrode
Implementation Method 3
the sprayer body is provided with a swirl generator for generating a swirling air stream
Implementation Method 4
a magnetic field generator, the magnetic field generator being a coil which is spirally twined around a circumference of the partition
Implementation Method 5
a Taylor cone is formed by the liquid at the exit of the nozzle at the end of the emission electrode under the electric field force whose orientation is opposite to that of the surface tension force
Implementation Method 6
The liquid provided by the liquid pump is retained at an exit of the nozzle under the surface tension force
Implementation Method 7
When the ratio of the charge intensity on the droplet surface to the droplet radius reaches the Rayleigh instability limit, the droplets incur the Coulombic fission to form a large number of droplets in small particle size
Implementation Method 8
During the movement of the charged droplets from the emission electrode to the opposed electrode under the electric field force, the solvent of the charged droplets evaporates continually
Data Source
AI summary
The electrospray device comprises a sprayer comprising a sprayer body and nozzle, and a partition positioned vertically and coaxially with the sprayer. The sprayer body is provided with a swirl generator for generating a swirling air stream, and a power supply connected between the nozzle and the partition, to apply voltage to the nozzle and the partition. The electrospray device may be part of a fluidized bed apparatus comprising a product container, a lower plenum base, an air distribution plate resided therebetween. When the power supply applies voltage in opposite polarities to the nozzle and the partition, the fluidized bed apparatus is used for coating particles; and when the power supply applies voltage of the same, the fluidized bed apparatus is used for spray-drying a solution. The electrospray device uses an electromagnetic hydrodynamic method to improve the performance of the fluidized bed apparatus and optimize the process of product.