Patent Application
20230030578
The present technology generally relates to devices, systems, and methods for feeding material into a plasma for processing of the material by the plasma. In particular, the present technology relates to a system for conveying powder material from a hopper to a plasma torch using any combination of a pneumatic system, an auger, and a vibrating mesh screen.
Plasma torches provide a high temperature plasma for a variety of purposes. In general, there are several types of plasma torches including induction plasma torches and microwave plasma torches. Other types of plasma torches can include direct current (DC) plasma, with arcing between a cathode and anode. These types of plasma torches provide substantially different high temperatures, with microwave plasma reaching about 6,000 K and the rest reaching about 10,000 K.
These high temperature plasmas may enable processing of a variety of materials that are exposed to or fed into the plasma. One such type of processing is taking one or more materials of a particular size and shape and, by exposing or feeding it into the plasma, changing the one or more materials into a different size and/or shape.
Provided herein are devices and methods for providing material feedstock into a plasma of a plasma torch. According to one aspect, the present disclosure relates to a system for processing fine powders. The system includes a hopper for dispensing powder material through a hopper outlet, and a feeding chamber positioned downstream of the hopper outlet to receive the powder material and convey the powder material to a plasma torch. The system also includes a pneumatic system providing a gas flow sufficient to propel the powder material without extinguishing a plasma of the plasma torch, an auger positioned at the hopper outlet, and a mechanical vibrator and a mesh screen attached to a flange of the feeding chamber. In some embodiments, the mechanical vibrator vibrates the mesh screen at a frequency between 1000 and 10000 Hz. In some embodiments, the pneumatic system provides a gas flow between 10 and 60.
According to another aspect, the present disclosure relates to a method of feeding fine powders into a plasma torch. The method includes operating a hopper to dispense powder material through a hopper outlet, and rotating an auger positioned at the hopper outlet to deliver the powder material from the hopper outlet to a feeding chamber. The method also includes vibrating a mechanical vibrator connected to a mesh screen at an outlet of the feeding chamber to deliver a metered volume of powder material through the outlet of the feeding chamber. The method also includes conveying a gas flow through a pneumatic system connected to the outlet of the feeding chamber to convey the powder material from the outlet of the feeding chamber to a plasma torch. In some emboidments, the rotation speed of the auger, frequency of vibration of the mechanical vibrator, and gas flow speed are each selected to produce a desired flow of powder material into the plasma torch. In some embodiments, vibrating the mechanical vibrator includes vibrating the mesh screen at a frequency between 1000 to 10000 Hz. In some embodiments, operating the hopper includes dispensing powder material having a size distribution between 10 to 100 microns.
According to another aspect, the present disclosure relates to a system for processing fine powders that includes a hopper for dispensing powder material through a hopper outlet, a feeding chamber, and a hybrid powder feed system. The feeding chamber is positioned downstream of the hopper outlet to receive he powder material and convey the powder material to a plasma torch. The hybrid powder feed system includes at least two of: a pneumatic system, an auger positioned at the hopper outlet, or a vibrating mesh screen device positioned at an outlet of the feeding chamber. In some embodiments, the hybrid powder feed system includes the pneumatic system and the vibrating mesh screen device positioned at the outlet of the feeding chamber. In some embodiments, the hybrid powder feed system includes the pneumatic system and the auger positioned at the hopper outlet. In some embodiments, the hybrid powder feed system includes the vibrating mesh screen device positioned at the outlet of the feeding chamber and the auger positioned at the hopper outlet. In some embodiments, the hybrid powder feed system includes the pneumatic system, the auger positioned at the hopper outlet, and the vibrating mesh screen device positioned at the outlet of the feeding chamber. In some embodiments, the vibrating mesh screen device includes a mechanical vibrator and a mesh screen attached to a flange of the feeding chamber. In some embodiments, the mesh screen has between 100 to 225 openings per inch. In some embodiments, the mechanical vibrator vibrates the mesh screen at a frequency between 1000 and 10000 Hz. In some embodiments, the hopper is designed to dispense powder material having a size distribution between 10 to 100 microns. In some embodiments, the auger includes variable pitch or variable diameter along its length. In some embodiments, the pneumatic system provides a gas flow between 10 to 60 SCFH argon. In some embodiments, the gas flow is sufficient to propel the powder material without extinguishing a plasma of the plasma torch. In some embodiments, the pneumatic system includes a tee junction and parallel gas line for providing a secondary gas flow to the hopper.
The invention may be more fully understood from the following detailed description taken in conjunction with the accompanying drawings.
Certain exemplary embodiments will now be described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the devices and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments and that the scope of the present invention is defined solely by the claims. The features illustrated or described in connection with one exemplary embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the present technology.
In general, aspects of the present technology are directed to devices, systems and methods relating to material feeding devices for plasma processing. In some embodiments, various materials can be processed using a plasma torch, including very fine powders between about 10 to 100 microns. However, a significant challenge arises with very fine powders, as they may not flow well. Decreased particle flow can clog the processing system and decrease yeild. This can pose a particular problem when the very fine particles are not spherical. In some embodiments, the powder particles could be of various morphologies such as angular powder, angular chips, irregular powder, sponge powders, etc.
If the particles clump together, they may become too large to be properly processed by the plasma. Material processing is adversely affected when the powder material concentration (in g/cm3) (i.e. the number of the particles within the plasma) is too high. In this condition, the high concentration of the material lessens the available energy and saturates the process. One way to improve processing is to prevent the particles from clumping together. The hybrid powder feed schemes disclosed herein are techniques that can help resolve this issue.
The embodiments disclosed herein can increase particle flow for very fine powders, and prevent the fine powders from clumping or joining together, using a hybrid powder feed design. The hybrid powder feed design includes one or more of the following systems for conveying powder material from a hopper to a plasma torch: a pneumatic system, an auger or screw feeder, and a vibrating mesh screen.
The hybrid powder feeder disclosed herein solves a long felt and unsolved need for a pneumatic system for conveying fine powders to a plasma torch, combined with additional powder conveyance techniques. Typical pneumatic systems create too strong of a gas flow, which would extinguish the plasma within the plasma torch. In order to convey such fine powders at a consistent powder flow and without the particles clumping together, a combination of one or more of a pneumatic system, an auger, and a vibrating mesh screen can be used.
The auger 103 can be positioned at the hopper outlet 102, and can rotate in order to convey the powder material to a feeding chamber 105 that is positioned downstream of the hopper outlet. The auger can include a number of blades and can have variable pitch or variable diameter along its length.
The feeding chamber 105 can include one or more flanges, which can include a flange, where a mesh screen 107 and a mechanical vibrator 109 can be secured. For example, the mesh screen 107 can be positioned within the feeding chamber 105 at the flange at a downstream end of the chamber, and a mechanical vibrator 109 can also be positioned or secured to the flange (or another component close to the mesh screen 107 in order to transfer mechanical vibrations to the screen and feeding chamber). In this way, the powder material that is deposited into the feeding chamber 105 from the auger 103 can be vibrated and dispensed through the mesh screen 107. In some embodiments, the mesh screen has a screen size between about 100 to about 225 mesh (about 100 to 225 openings per inch). In another embodiment, the mechanical vibrator vibrates the mesh screen at a particular frequency, such as between about 1000 and 10000 Hz.
In some embodiments, the dimensions and rotational speed of the auger 103, as well as the screen size of the mesh screen 107 and/or the vibration frequency of the mechanical vibrator 109 can be customized in order to achieve a desired powder flow rate out of the feeding chamber 105. These metrics can be based on the size of the powder material being dispensed, and can be customized together or individually.
In some embodiments, the pneumatic system provides a gas flow through theprimary gas line 415 sufficient to propel the powder material to the plasma torch without extinguishing the plasma. An example gas flow speed can range between about 10 and 60 SCFH argon.
In some embodiments, the pneumatic feed line 615, or some other type of powder feeding device, can be mounted to the plasma chamber 603, or to a plasma torch housing. As discussed above, the gas flow speed of the pneumatic system can be sufficient to convey the fine powder material to the plasma torch 603 without extinguishing the plasma plume 604.
At operation 703, the auger positioned at the hopper outlet is rotated to deliver the powder material from the hopper outlet to a feeding chamber. In some embodiments, the auger can include a number of blades and can have variable pitch or variable diameter along its length. and can be rotated at a particular speed depending on the size of the powder materials.
At operation 705, a mechanical vibrator connected to a mesh screen at the outlet of the feeding chamber is vibrated. By vibrating the mechanical vibrator, a metered volume of powder material can be delivered through the outlet of the feeding chamber. In some embodiments, the vibration frequency of the mechanical vibrator can be set or adjusted depending on the powder material size, the speed of the auger, the desired powder flow speed, and/or the size of the mesh screen.
At operation 707, a gas flow is conveyed through a pneumatic system connected to the outlet of the feeding chamber. The gas flow conveys the powder material from the outlet of the feeding chamber to a plasma torch, as discussed above, and can be selected or adjusted based on the powder material size, the speed of the auger, the desired powder flow speed, and/or the size of the mesh screen. In some cases, each of the metrics discussed above can be adjusted or tailored in order to produce a desired flow of powder materials into the plasma torch.
In the foregoing specification, the invention has been described with reference to specific embodiments thereof. However, various modifications and changes can be made thereto without departing from the broader spirit and scope of the invention. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.
This application claims the benefit of and priority to U.S. Application Number 63/226,299, filed on Jul. 28, 2021, and entitled "Hybrid Powder Feed Device", the contents of are hereby incorporated in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63226299 | Jul 2021 | US |
