Microwave Plasma Powder Spheroidisation With External Tube Cooling
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Solution Overview
Problem
Existing microwave plasma spheroidization processes are complicated and expensive due to the use of a shrouding gas to protect the plasma chamber, which complicates the apparatus and increases maintenance costs.
Innovation Solution
The apparatus uses compressed air to externally cool the plasma tube, eliminating the need for an external refrigeration tube and allowing superatmospheric pressure, thus preventing powder leaks and contamination while simplifying the design and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a shrouding gas is used to protect the plasma chamber, then the plasma chamber is protected from heat and contamination, but the apparatus complexity and maintenance cost increase
Solution Approach 1:
The invention extracts and eliminates the shrouding gas system from the apparatus. Instead of using a complex gas flow system to protect the plasma chamber, the patent uses direct water cooling of the plasma tube walls, simplifying the overall apparatus structure while maintaining effective protection against heat and contamination
Solution Approach 2:
The invention introduces water cooling channels as an intermediary cooling mechanism between the plasma tube and the plasma chamber environment. This water cooling system acts as a thermal barrier and protective layer, replacing the need for shrouding gas while effectively managing heat transfer and protecting the plasma chamber
2Reliability
If a shrouding gas is used to protect the plasma chamber, then the plasma chamber is protected from heat and contamination, but the maintenance cost increases
Solution Approach 1:
The invention removes the shrouding gas system, eliminating the need for complex gas supply and flow control infrastructure that requires expensive maintenance. The simplified water-cooled design reduces maintenance requirements and operational costs
Solution Approach 2:
The invention employs a simple water cooling system that uses readily available water as a cooling medium, replacing expensive and complex gas handling systems. This approach significantly reduces both initial investment and ongoing maintenance costs while maintaining effective plasma chamber protection
3Device complexity
If the plasma tube is cooled from outside using compressed air, then the apparatus design is simplified and costs are reduced, but the cooling efficiency may be limited
Solution Approach 1:
The invention employs water cooling channels integrated into the plasma tube structure, using hydraulic flow of water to efficiently remove heat from the plasma tube. This liquid cooling approach provides superior heat transfer efficiency compared to air cooling, while maintaining simple apparatus design
Solution Approach 2:
The invention changes the cooling medium from gas (air) to liquid (water), fundamentally improving the heat transfer parameter. Water's higher specific heat capacity and thermal conductivity enable more efficient heat removal from the plasma tube, addressing the cooling efficiency concern while keeping the design simple
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 solution results in a cheaper, safer, and easier-to-maintain apparatus that achieves efficient powder spheroidization with reduced complexity and cost, while maintaining plasma stability and preventing contamination.
Implementation Method 1
A microwave-induced plasma is a type of plasma that has high frequency electromagnetic radiation in the GHz range. It is capable of exciting electrodeless gas discharges.
Implementation Method 2
forming a plasma torch in the plasma tube by coupling the process gas flow with the microwave radiation
Implementation Method 3
The powder precursor of angular shape (often from waste materials) is carried into an induction or microwave-induced plasma and is melted immediately in the high temperatures of plasma. The melted powder particles assume a spherical shape under the action of the surface tension of the liquid state.
Implementation Method 4
the microwave cavity comprises at least one opening for the compressed air so that the latter can cool the plasma tube from outside
Data Source
AI summary
An apparatus for powder spheroidisation by microwave-induced plasma comprises a microwave generator, a microwave cavity, a waveguide connecting the microwave generator to the microwave cavity, a plasma tube partially located in the microwave cavity, a powder supply connected to the plasma tube to feed a powder precursor flow thereinto, a gas supply connected to the plasma tube to feed a process gas flow thereinto, in order to form a plasma torch in the plasma tube by coupling the process gas flow with the microwave radiation, and a compressed air supply. The microwave cavity comprises at least one opening for the compressed air so that the latter can cool the plasma tube from outside, and the gas supply is connected to the powder supply to let the process gas carry the powder precursor into the plasma tube, and so into the plasma torch in order to make spheroids from the powder precursor by in-flight melting.