Method and apparatus for enhanced jet flow

Abstract

A method and apparatus for producing an enhanced jet stream that can be directed toward a workpiece. The enhanced jet stream has higher energy, allowing the jet stream to remove coatings that are difficult to remove from substrates. A heated stream is combined with an entrained particle stream and discharged through a nozzle. The heated stream enables more energy to be imparted to the coating.

Description

Background Art

[0001] As is well known, there are particle blasting systems that utilize various types of blasting media. Systems for entraining cryogenic particles, such as solid carbon dioxide particles, in a conveying fluid and directing the entrained particles toward an object / target, and various components associated therewith, such as nozzles, are well known and are shown in U.S. Patents 4,744,181; 4,843,770; 5,018,667; 5,050,805; 5,071,289; 5,188,151; 5,249,426; 5,288,028; 5,301,509; 5,473,903; 5,520,572; 6,024,304; 6,042,458, 6,346,035, 6,524,172, 6,695,679, 6,695,685, 6,726,549, 6,739,529, 6,824,450, 7,112,120, 7,950,984, 8,187,057, 8,277,288, 8,869,551, 9,095,956, 9,592,586, 9,931,639, and 10,315,862, all of which are incorporated herein by reference in their entirety.

[0002] In addition, U.S. Patent Application Serial No. 11 / 853,194, filed on September 11, 2007, for a particle blast system with a synchronized feeder and particle generator, U.S. Publication No. 2009 / 0093196; U.S. Provisional Application Serial No. 61 / 589,551, filed on January 23, 2012, for a method and apparatus for sizing carbon dioxide particles; U.S. Provisional Application Serial No. 61 / 592,313, filed on January 30, 2012, for a method and apparatus for dispensing carbon dioxide particles; U.S. Patent Application Serial No. 13 / 475,454, filed on May 18, 2012, for a method and apparatus for forming carbon dioxide pellets; U.S. Patent Application Serial No. 14 / 062,118, filed on October 24, 2013, for a method and apparatus for forming carbon dioxide pellets including at least an impeller or a deflector. No. 14 / 516,125, filed on October 16, 2014, for a method and apparatus for forming solid carbon dioxide, U.S. Publication No. 2015 / 0166350; No. 15 / 297,967, filed on October 19, 2016, for a jet media pulverizer, U.S. Publication No. 2017 / 0106500; No. 15 / 961,321, filed on April 24, 2018, for a particle blasting device; and No. 62 / 890,044, filed on August 21, 2019, for a particle blasting device and method, the entire contents of which are incorporated herein by reference.

[0003] Also known are particle blasting devices that entrain non-cryogenic blasting media, such as, but not limited to, abrasive blasting media. Examples of abrasive blasting media include, but are not limited to, silicon carbide, aluminum oxide, glass beads, crushed glass, and plastic. Abrasive blasting media can be more aggressive than dry ice media and may be more effective in some situations.

[0004] Mixed media blasting is also known, in which more than one type of media is entrained in a stream directed toward a target. In one form of mixed media blasting, dry ice pellet media and abrasive media are entrained in a single stream directed toward a target. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] The drawings illustrate embodiments serving to explain the principles of the invention.

[0006] Figure 1 A particle injection system constructed in accordance with one or more teachings of the present invention is schematically illustrated.

[0007] Figure 2 An ejector for adding energy to the entrained particle flow is schematically shown.

[0008] Figure 3 A converging-diverging configuration for examining the dynamics of a fluid flowing through a first flow path and a second flow path in communication with the first flow path in accordance with aspects of the present teachings is schematically illustrated. DETAILED DESCRIPTION

[0009] In the following description, similar reference numerals represent similar or corresponding parts in multiple views. In addition, in the following description, it should be understood that terms such as front, back, medial, lateral, etc. are words of convenience and should not be understood as limiting terms. The terms used in this patent are not meant to be limiting, and the devices or parts thereof as described herein can be attached or used in other directions. With reference to the accompanying drawings in more detail, one or more embodiments constructed according to the teachings of the present invention are described.

[0010] It should be understood that any patent, publication or other public material incorporated herein by reference, whether in whole or in part, is incorporated herein only to the extent that the material incorporated therein does not conflict with existing definitions, statements or other public materials set forth in the present disclosure. Therefore, to the extent necessary, the disclosure as expressly set forth in the present disclosure will supersede any conflicting material incorporated herein by reference.

[0011] Many factors affect the ultimate performance of the entrained particle stream exiting the injection nozzle of a particle injection system and impacting a target. According to the teachings of the present invention, the kinetic energy of the particles as they impact the target and the temperature of the stream can be considered as factors that affect the ultimate performance. The present invention provides an apparatus and method for achieving the particle kinetic energy at the workpiece and / or the temperature of the stream at the workpiece to provide the desired performance.

[0012] The present invention utilizes the addition of energy to the entrained particle flow, thereby increasing the kinetic energy of the particles at the workpiece and / or increasing the flow temperature at the workpiece. In the embodiments disclosed herein, the addition of energy is achieved by providing a heated fluid flow, such as a gas, and combining the heated fluid flow with the entrained particle flow. In one embodiment, the heated fluid is combined with the entrained particle flow proximal to the injection nozzle. In embodiments where the injection nozzle is a supersonic nozzle, the heated fluid can be combined with the entrained particle flow proximal to the minimum throat region of the converging-diverging flow path, and can be combined immediately upstream of the position where the combined flow reaches Mach 1.

[0013] Figure 1Schematically illustrated is a particle spraying system 2 including a particle spraying device 4. The particle spraying device 4 is connectable to a source of compressed fluid 6, which is delivered via a hose 8 to a particle feeder (not shown) disposed within a unit 10. As is well known, the particle feeder entrains particles of a spraying medium, which in the illustrated embodiment are particles of carbon dioxide, which are received from a source of spraying medium particles into a conveying fluid, and the entrained particle stream flows through an entrained flow channel defined by a delivery hose 12 to an applicator 14 and out of a spray nozzle 18.

[0014] The compressed fluid from source 6 can be any suitable transport fluid, such as air, at any suitable pressure, such as 40 psig to 300 psig. The transport fluid, at least after it leaves source 6, is a flowing fluid having sufficient kinetic energy to transport particles entrained therein.

[0015] In the illustrated embodiment, the jet nozzle 18 is a supersonic nozzle. Although the jet nozzle 18 is depicted as a supersonic nozzle, the present invention may be used with sonic and subsonic nozzles.

[0016] In the illustrated embodiment, the injector 16 is interposed between the applicator 14 and the nozzle 18. The injector 16 may be constructed as a separate component or as an integral part of the applicator 14.

[0017] The system 2 includes a heater 20 that receives a compressed fluid stream from a source 6 through a hose 22, adds energy to the compressed fluid stream, causing the temperature to increase, and delivers the high-energy fluid (also referred to herein as a heated fluid) to the ejector 16 through a heated fluid passage defined by a hose 24. The temperature of the heated stream when it reaches the ejector 16 can be any suitable temperature, such as 750° F. The temperature range can be in the range of above ambient temperature up to and including 750° F. Depending on the desired performance and objectives, the temperature of the heated stream may be above 750° F.

[0018] The heater 20 may be disposed at any suitable location. Figure 1 In the diagram, a heater 20 is schematically shown disposed close to the ejector 16 to minimize heat loss of the heated flow between the heater 20 and the ejector 16. A dryer (not shown) disposed at any suitable location may be included to remove moisture from the compressed fluid. The dryer may be an integral part of the source 6 or the heater 20.

[0019] Reference Figure 2, one embodiment of the injector 16 is shown as an example. As described above, although the injector 16 is shown as a separate component, the features and functions of the injector 16 can be an integral part of the applicator 14. The injector 16 includes a first flow path 26 (also referred to as a first flow channel) and a second flow path 28 (also referred to as a second flow channel). The first flow path 26 includes an inlet 30 and an outlet 32, wherein the fluid flow in the first flow path 26 flows from the inlet 30 to the outlet 32. The injection nozzle 18 ( Figure 2 30) is connected in fluid communication with the outlet 32. In the illustrated embodiment, the first flow path 26 of the ejector 16 includes a first portion 34 in fluid communication with the inlet 30, followed by a second portion 36 in fluid communication with the outlet 32. In the illustrated embodiment, the first portion 34 is configured as a converging portion, which functions as a converging portion required to generate supersonic flow downstream. In an alternative embodiment, the converging portion shown as a portion of the first portion 34 can be disposed upstream of the inlet 30, wherein the inlet 30 is directly in fluid communication with the second portion 36.

[0020] The second portion 36 includes a substantially constant cross-sectional area along its length to a converging cross-sectional area. The second portion 36 may have a portion of a substantially constant cross-sectional area that leads to a portion of a converging cross-sectional area. When the second portion 36 is part of a supersonic converging diverging passage, the second portion is configured for operating conditions of the system 2 with a minimum cross-sectional area located near the outlet 32, downstream of the junction of the first flow path 26 and the second flow path 28 (described below), so that the position of Mach 1 in the supersonic flow occurs downstream of the junction. After reaching Mach 1, supersonic expansion of the flow occurs primarily in the jet nozzle 18.

[0021] The second flow path 28 includes an inlet 38 and an outlet 40, wherein the fluid flow through the second flow path 28 flows from the inlet 38 to the outlet 40. The outlet 40 fluidly connects the second flow path 28 with the first flow path 26 at a junction area 42. In the illustrated embodiment, the second flow path 28 includes a first portion 44 in fluid communication with the inlet 38, followed by a second portion 46 in fluid communication with the outlet 40 at the junction area 42. In the illustrated embodiment, the first portion 44 is configured as a converging portion that functions to accelerate the flow within the second flow path 28. In an alternative embodiment, the converging portion shown as a portion of the first portion 44 can be disposed upstream of the inlet 38, wherein the inlet 38 is directly in fluid communication with the second portion 46.

[0022] The second portion 46 includes a substantially constant cross-sectional area to a converging cross-sectional area along its length. The second portion 46 may have a portion of a substantially constant cross-sectional area that leads to a portion of a converging cross-sectional area. In a supersonic embodiment, downstream of the junction area 42, the combined flow of the first flow path 26 and the second flow path 28 will reach Mach 1. Therefore, the second flow path is configured to not produce Mach 1 in the fluid flowing therethrough.

[0023] In the illustrated embodiment, the hose 24 is connected to the inlet 30 so that the heating stream flows through the first flow path 26. The conveying gas stream with entrained particles is delivered to the flow path 28 through the inlet 38. This configuration avoids energy losses that would cause the heating stream to turn through the junction angle (the angle between the first flow path 26 and the second flow path 28). The junction angle should be as small as possible to minimize losses through the angle. Alternatively, the conveying gas stream with entrained particles can be delivered to the flow path 26 through the inlet 30, and the heating stream can be delivered to the flow path 28 through the inlet 38, wherein these flow paths are respectively configured for the arrangement of the streams.

[0024] In operation, according to one embodiment, the heated flow is directed through the first flow path 26, arriving at the second portion 36 after its velocity is increased by converging at or upstream of the first portion 34. The entrained particle flow is directed through the second flow path 28, arriving at the second portion 46 after its velocity is increased by converging at or upstream of the first portion 44. The heated flow and the entrained particle flow combine proximal to the junction region 42, and the combined flow reaches Mach 1 downstream of the junction region 42 due to the configuration of the flow path of the ejector 16, which is configured for the design properties of the flow (e.g., pressure, temperature, density).

[0025] The combined flow consisting of the heated flow and the entrained particle flow flows through and out of the jet nozzle 18 directed toward the target workpiece. In the illustrated embodiment, the energy added to the entrained particle flow due to the combination with the heated flow produces a supersonic entrained particle flow with much higher energy than without the added energy. This higher energy can be manifested as a higher velocity of the gas flow, a higher temperature of the fluid, and / or a higher kinetic energy of the entrained particles. The higher the gas flow velocity, the higher the velocity of the entrained particles.

[0026] According to the present invention, the resultant stream from the system is capable of removing difficult to remove coatings, such as epoxies and enamels, from substrates.

[0027] The cryogenic particles entrained in the lower transport fluid are not exposed to the temperature of the heating stream until the streams are combined, thereby minimizing sublimation of the cryogenic particles due to the thermal energy of the heating stream. In the supersonic embodiment shown, this occurs immediately upstream of the Mach 1 speed of sound plane in the first flow path 26. Once combined, the streams are immediately accelerated to above Mach 1.

[0028] Now refer to Figure 3 , which is a schematic diagram of a convergent-divergent configuration for reviewing the fluid dynamics of the flow. As described above, in the illustrated embodiment, the heating flow shown by arrow 48 is accelerated by the convergence of the first portion 34 and enters the second portion 36. The cross-sectional area of ​​the second portion 36 is necessary for the required heating flow velocity and the required heat retention. Although the second portion 36 can continue to converge before the connection of the entrained particle flow, it should be noted that increasing the speed of the heating flow by converging will result in a corresponding decrease in temperature. 1 Mach occurs downstream of the connection area 42 at the sonic plane 50 (a normal shock wave is schematically shown). The sonic plane 50 is the connection point of nozzles of various design characteristics, which can produce supersonic outlet flows as shown, or can produce sonic flows. In one embodiment, the sonic plane 50 coincides with the outlet 32.

[0029] As shown by arrows 52, the entrained particle flow is accelerated by converging upstream of the second portion 46. The cross-sectional area of ​​the second portion 46 can achieve a desired reduction in static wall pressure relative to the total pressure provided and the associated mass flow rate of the entrained particle flow. The static wall pressure at the outlet 40 / joining area 42 is lower than the total pressure of the entrained particle flow entering the second portion 36.

[0030] The joining region 54 is the region where the two flows join, and the length of the joining region 54 may be close to zero if the outlet cross-sectional area and corresponding internal / outlet pressures are capable of providing choked sonic flow conditions at the outlet 32 ​​.

[0031] Depending on the design, there may be a variety of pressures and flows. For example, at 80 PSI, the combined flow rate may be 60 to 65 CFM. In another embodiment, at 150 PSI, the heating flow may be 170 CFM. The flow characteristics may be in between.

[0032] The relative flow rates of the heating flow and the entrained particle flow can be adapted to the design and operating parameters of the system. In one embodiment, the heating flow accounts for about 75% of the total flow rate and the entrained particle flow accounts for about 25% of the total flow rate.

[0033] The fluid temperature may be monitored to optimize the temperature at the jet nozzle outlet. For example, the temperature may be monitored at the outlet 56 of the nozzle 18, or may be monitored upstream of the sonic plane 50, such as at 58 by a processing system 60. The processing system 60 may be microprocessor-based or may be of any suitable configuration, which may be configured to control the temperature and flow rate of the heating stream and the mass flow rate, particle size, and flow rate of the entrained particle stream. (The temperature monitored by the processing system 60 is not shown in FIG. 1 .) Figure 1 (shown in

[0034] One aspect of the present invention is the ability to maintain the flow rate above the dew point temperature.

[0035] The present invention and illustrated embodiments deliver cryogenic particles in an entrained particle stream that is separate from the flow of the heating stream, keeping the entrained particle stream unaffected by the thermal effects of the heating stream until the two streams are combined in the ejector just before the throat of the combined stream flow path and exit from the ejection nozzle.

[0036] The applicator 14 may include a control element that may provide an input or signal to the processing system 60 allowing an operator to control the amount of heat in the heating stream, such as by way of non-limiting example, whether by specifying a target sensed temperature 56, 58, or by setting a specific volume of cryogenic particles, a particle mass flow rate, or a relative flow rate between the heating stream and the entrained particle stream.

[0037] According to various aspects of the present disclosure, an element, or any part of an element, or any combination of elements can be implemented with a "processing system" comprising one or more physical devices, which includes a processor. Non-limiting examples of processors include microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), programmable logic controllers (PLCs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform various functions described throughout the present disclosure. One or more processors in a processing system can actuate processor executable instructions. A processing system that executes instructions to produce a result is a processing system that is configured to perform tasks that will result in a result, such as by providing instructions to one or more components of a processing system, which will cause these components to perform certain actions, which are either performed alone or combined with other actions performed by other components of the processing system, thereby resulting in a result. Software should be broadly interpreted as instructions, instruction sets, codes, code segments, program codes, programs, subroutines, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, execution threads, programs, functions, etc., whether or not referred to as software, firmware, middleware, microcode, hardware description language or otherwise. The software may reside on a computer-readable medium. A computer-readable medium may be a non-transitory computer-readable medium. Computer-readable media include, for example, magnetic storage devices (e.g., hard disks, floppy disks, magnetic strips), optical disks (e.g., compact disks (CDs), digital versatile disks (DVDs)), smart cards, flash memory devices (e.g., cards, sticks, key drives), random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, removable disks, and any other suitable medium for storing software and / or instructions that can be accessed and read by a computer. The computer readable medium may reside in the processing system, reside outside the processing system, or be distributed among multiple entities including the processing system. The computer readable medium may be embodied in a computer program product. For example, a computer program product may include a computer readable medium in packaging materials. Those skilled in the art will recognize how to best implement the functions described throughout this disclosure based on the specific application and the overall design constraints imposed on the entire system.

[0038] Clear definition

[0039] "Based on" means that something is at least partially determined by the thing it is indicated as being "based on." When something is completely determined by something, it will be described as being "completely based on" that thing.

[0040] A "processor" refers to a device that can be configured to perform the various functions set forth in this disclosure, either alone or in combination with other devices. Examples of "processors" include microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), programmable logic controllers (PLCs), state machines, gated logic, and discrete hardware circuits. The phrase "processing system" is used to refer to one or more processors, which may be included in a single device, or distributed across multiple physical devices.

[0041] A statement that a processing system is "configured to" perform one or more actions means that the processing system includes data (which may include instructions) that can be used to perform the specific actions that the processing system is "configured to" perform. For example, in the case of a computer (a "processing system"), installing Microsoft WORD on a computer would "configure" the computer to be used as a word processor, using the instructions of Microsoft WORD in combination with other inputs such as an operating system and various peripheral devices (e.g., keyboard, display, etc. ...).

[0042] The foregoing description of one or more embodiments of the present invention has been given for the purpose of illustration and description. The present invention is not intended to be exhaustive or to limit the present invention to the precise form disclosed. Based on the above teachings, obvious modifications or variations are possible. The embodiment is selected and described in order to best illustrate the principles of the present invention and its practical application occasions, so that a person of ordinary skill in the art can best utilize the invention in various embodiments and make various modifications suitable for the intended specific purposes. Although only a limited number of embodiments of the present invention are explained in detail, it should be understood that the scope of the present invention is not limited to the details of the construction and arrangement of the components described in the foregoing description or shown in the accompanying drawings. The present invention can have other embodiments and can be practiced or executed in various ways. In addition, for the sake of clarity, specific terms are also used. It should be understood that each specific term includes all technical equivalents that operate in a similar manner to achieve similar purposes. The scope of the present invention is intended to be defined by the appended claims.

Claims

1. A particle injection system configured to discharge a stream of entrained particles from an injection nozzle while the particle injection system is operating within its operating parameters, the particle injection system comprising: a. Heating fluid source; b. a source of conveying fluid; c. a particle feeder connected to the transport fluid source, the particle feeder being configured to entrain particles into the transport fluid flow flowing from the transport fluid source, thereby generating an entrained particle flow; d. An injector, the injector comprising: i. A first flow channel comprising a first flow channel inlet and a first flow channel outlet, wherein the first flow channel comprises: (a) a first portion in fluid communication with the first flow channel inlet; and (b) a second portion subsequent to the first portion, the second portion comprising a generally constant to converging cross-sectional area along its length; and ii. a second flow channel comprising a second flow channel inlet and a second flow channel outlet, the second portion comprising a junction region located upstream of the first flow channel outlet, the second flow channel being in fluid communication with the first flow channel fluid at the junction region via the second flow channel outlet; e. an entrainment flow channel in fluid communication with the second flow channel inlet and configured to deliver the entrained particle flow from the particle feeder to the second flow channel; and f. A heating fluid channel placing the heating fluid source in fluid communication with the first flow channel inlet.

2. The particle injection system according to claim 1, characterized in that: The first portion includes a converging portion.

3. The particle injection system according to claim 1, characterized in that: A Mach 1 location in supersonic flow within the first flow channel occurs downstream of the junction region when the particle injection system is operating within its operating parameters.

4. The particle injection system according to claim 1, characterized in that: The second portion includes a portion of constant cross-sectional area that leads to a portion of converging cross-sectional area.

5. The particle injection system according to claim 3, characterized in that: The injection nozzle is in fluid communication with the first flow passage outlet, the injection nozzle being configured to supersonically expand a flow therein.

6. The particle injection system according to claim 1, characterized in that: The second flow channel includes a first portion, and the first portion of the second flow channel includes a converging portion.

7. The particle injection system according to claim 6, characterized in that: The second flow passage includes a second portion downstream of the first portion of the second flow passage, the second portion of the second flow passage including a portion of constant cross-sectional area leading to a portion of converging cross-sectional area.

8. The particle injection system according to claim 1, characterized in that: The particles include cryogenic particles.

9. The particle injection system according to claim 1, characterized in that: The first flow channel is straight from the first flow channel inlet to the first flow channel outlet.

10. The particle injection system according to claim 1, characterized in that: The particle injection system is operated within its operating parameters and the static pressure of the heated fluid flowing through the first flow channel at the junction area is lower than the total pressure of the entrained particle flow entering the second portion.

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