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WO2020123697A1 - Systèmes de traitement au jet abrasif à bruit réduit - Google Patents

Systèmes de traitement au jet abrasif à bruit réduit Download PDF

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Publication number
WO2020123697A1
WO2020123697A1 PCT/US2019/065783 US2019065783W WO2020123697A1 WO 2020123697 A1 WO2020123697 A1 WO 2020123697A1 US 2019065783 W US2019065783 W US 2019065783W WO 2020123697 A1 WO2020123697 A1 WO 2020123697A1
Authority
WO
WIPO (PCT)
Prior art keywords
nozzle
abrasive blasting
abrasive
nozzle assembly
blasting
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US2019/065783
Other languages
English (en)
Inventor
Christopher Sullivan
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Oceanit Laboratories Inc
Original Assignee
Oceanit Laboratories Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US16/216,972 external-priority patent/US11383349B2/en
Application filed by Oceanit Laboratories Inc filed Critical Oceanit Laboratories Inc
Priority to US16/819,035 priority Critical patent/US12280468B2/en
Priority to CA3159321A priority patent/CA3159321A1/fr
Priority to KR1020227022777A priority patent/KR20220110268A/ko
Priority to PCT/US2020/025586 priority patent/WO2021118625A1/fr
Priority to JP2022535240A priority patent/JP7574297B2/ja
Priority to CN202080086029.XA priority patent/CN114829068B/zh
Priority to AU2020399540A priority patent/AU2020399540B2/en
Priority to EP20897655.5A priority patent/EP4072778A4/fr
Publication of WO2020123697A1 publication Critical patent/WO2020123697A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
    • B24C5/00—Devices or accessories for generating abrasive blasts
    • B24C5/02—Blast guns, e.g. for generating high velocity abrasive fluid jets for cutting materials
    • B24C5/04—Nozzles therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B1/00—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means
    • B05B1/002—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means designed to reduce the generation or the transmission of noise or to produce a particular sound; associated with noise monitoring means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B7/00—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas
    • B05B7/14—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas designed for spraying particulate materials
    • B05B7/1481—Spray pistols or apparatus for discharging particulate material
    • B05B7/1486—Spray pistols or apparatus for discharging particulate material for spraying particulate material in dry state
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
    • B24C3/00—Abrasive blasting machines or devices; Plants
    • B24C3/02—Abrasive blasting machines or devices; Plants characterised by the arrangement of the component assemblies with respect to each other
    • B24C3/04—Abrasive blasting machines or devices; Plants characterised by the arrangement of the component assemblies with respect to each other stationary
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
    • B24C7/00—Equipment for feeding abrasive material; Controlling the flowability, constitution, or other physical characteristics of abrasive blasts
    • B24C7/0046—Equipment for feeding abrasive material; Controlling the flowability, constitution, or other physical characteristics of abrasive blasts the abrasive material being fed in a gaseous carrier

Definitions

  • the invention relates to apparatus and methods for abrasive blasting. More particularly, the invention describes reduced noise abrasive blasting assemblies and systems and methods of constructing such systems.
  • Abrasive blasting operations used for paint and surface coating removal are essential to the maintenance of the ships, aircraft, and land vehicles of the US armed forces, as well as to industrial vehicles and machinery. But these operations expose maintenance personnel to sound pressure levels (SPLs) of 119 dB and greater on a routine basis, which result in significant health, productivity and compliance issues for blast operators. Many blast operators experience hearing loss as a direct result of prolonged exposure to blast noise.
  • Personal protective equipment (PPE) such as earplugs and earmuffs can reduce the immediate risk but introduces a loss of situational awareness and still does not satisfy OSHA-level requirements for noise exposure limits.
  • the OSHA noise standard (29 CFR 1910.95), limits a worker’s permissible noise exposure limit (PEL) to a time-weighted average of 90 dBA for 8 hours, and better hearing protection is not considered to reduce worker noise exposure. Only by reducing sound at its source will a worker experience non-hazardous noise.
  • FIG l Illustrated in Figure l is a conventional, state of the art supersonic abrasive blasting system 10 comprising a compressor 12, compressor hose 14, and abrasive tank 16 containing abrasive media 18.
  • An abrasive metering valve 20 controls the rate of release of abrasive media 18 into a standard blast hose 22. Release media 18 travels through a blast hose 22 to a claw coupling 24 and through supersonic convergent-divergent nozzle 26 where it is released into the environment at supersonic speed and with considerable noise. Details of state of the art convergent-divergent nozzle 26 are depicted in Figure 2 in cross section.
  • Nozzle 26 is comprised of a barrel 28 having a bore 30 with a convergent bore section 32, throat 34, and divergent bore section 36. Gases mixed with abrasive media 18 are compressed when traveling through convergent section 32 and then dispersed through divergent section 36, causing media 18 particles to accelerate within the divergent section 36 of nozzle 26 and out therefrom.
  • Conventional abrasive blasting system setups utilize a single 1” inner diameter blast hose 22 with a convergent-divergent type supersonic nozzle attachment 26.
  • the abrasive blasting media in these setups undergo most of their acceleration over a short distance in and following exit from nozzle 26.
  • the new assemblies and systems provide for effective abrasive blasting with significantly less noise than current state of art while reducing ergonomic stress from the size and weight of the carried portion of the systems.
  • the new assemblies and systems provide a greater length over which the particles are accelerated prior to exit, either in hosing, a nozzle, or both, bringing particle velocity closer to gas velocity at exit and enabling use of a lower gas exit velocity to reduce system noise while maintaining or even improving productivity. While amount of blasting time is related to noise exposure (due e.g. to regulatory compliance issues), productivity of a nozzle, which is related to velocity of the abrasive exiting the nozzle, is of equal concern in abrasive blasting. A higher velocity means that the blast operator can spend less time blasting per square meter. Less time translates to higher worker productivity and lower operational costs.
  • New assemblies and systems in some embodiments are comprised of standard blast hose, a novel accelerator hose portion, couplings including a transition coupling, and nozzle.
  • This improved abrasive blasting system maintains the desired abrasive particle velocity while decreasing the exit gas velocity and consequently decreasing sound production. This is accomplished through an acceleration hose section with reduced inner diameter and sufficient length to provide the necessary abrasive particle velocity.
  • the new systems maintain the productivity and efficiency of conventional abrasive blasting systems but with greatly reduced acoustic noise production and reduced operator fatigue due to the lower weight of the carried portion of the system.
  • One aspect of the subject invention is abrasive blasting apparatus that produce significantly less noise than conventional supersonic abrasive blasting systems while
  • a further aspect of the subject invention is abrasive blasting apparatus having a carried portion that is smaller and lighter than conventional supersonic abrasive blasting systems while demonstrating equivalent or superior efficiency and results.
  • Another aspect of the subject invention is abrasive blasting systems that employ a length of accelerator hose having an inside diameter smaller than conventional standard blast hose, taken over an additional length, to accelerate the media particles to a desired velocity prior to the particles entering the blast nozzle.
  • a further aspect of the subject invention is the use of transition coupling to step down the inner diameter of the media path from the standard blast hose to the accelerator hose.
  • Another aspect of the subject invention is abrasive blasting systems that employ a nozzle having a straight section following a diverging section, to accelerate the media particles to a desired velocity prior to the particles exiting the blast nozzle.
  • New assemblies and systems in some embodiments are comprised of a hose and nozzle assembly, the hose and nozzle assembly having a first portion having a first internal diameter, a constricted portion having an internal diameter less than the first internal diameter, a converging portion connecting the first portion to the constricted portion and having a converging internal diameter, and a straight portion downstream from the constricted portion, having a constant internal diameter less than that of the first portion.
  • the straight portion has a length such that a velocity of gas exiting the blasting nozzle assembly is reduced by at least 30% relative to the blasting nozzle assembly without the straight portion when operated with a predetermined gas/particle mix and pressure.
  • the length of the straight portion is effective to reduce exiting gas velocity when operated with a predetermined gas/particle mix and pressure by between 7% and 43%, in some embodiments between 30% and 40%, and in some embodiments by 35%.
  • fluid flows through the first portion, the converging portion, the constricted portion and the straight portion in that order.
  • the constricted portion, converging portion, and straight portion are all portions of a nozzle, which may also have a diverging portion connecting the constricted portion with the straight portion.
  • the converging portion, constricted portion, diverging portion and straight portion may together constitute a nozzle and the constricted portion may be the throat of the nozzle.
  • the straight portion may be at least 2” in length and less than 5.2” in length, and in some embodiments 2.5” in length.
  • the nozzle may be a #6 nozzle. In other embodiments, it may be any diameter nozzle.
  • the internal diameter of the straight portion is selected to produce a predetermined“hot spot” diameter of abrasive action.
  • the reduced noise abrasive blasting nozzle assembly in some embodiments also includes a media tank, abrasive media, and compressed gas to carry the abrasive media, and the hose and nozzle assembly includes one or more hose sections.
  • the subject invention achieves sufficient abrasive particle velocity through greater acceleration distances in an airstream with a lower exit velocity, thereby reducing the nozzle generated noise experienced with supersonic blast nozzles. Adjustments to blasting productivity can be made by adjusting the abrasive mass flow rate.
  • Figure 1 illustrates a conventional state of the art supersonic abrasive blasting system.
  • Figure 2 depicts, in cross section, a conventional supersonic convergent-divergent nozzle used in the abrasive blasting system illustrated in Figure 1.
  • Figure 3 reproduce graphs from Settles’ paper (Settles G., A scientific view of the productivity of abrasive blasting nozzles, 1996), showing predicted and measured velocities through a conventional Laval nozzle and the large difference between abrasive velocity and exit gas velocity.
  • Figure 4 is a graph showing the drag coefficient as a function of Mach number for two Reynolds numbers for spheres.
  • Figure 5 is a graph showing the required reduction in jet exit velocity to achieve desired reduction in Sound Pressure Level (SPL) based on the relationship of jet exit velocity to jet noise production.
  • SPL Sound Pressure Level
  • Figure 6 is a graph demonstrating modeled particle velocity versus distance in 345 m/s accelerator section for Type V acrylic media 20/30 mesh.
  • Figure 7 is a Moody Diagram used for estimation of Friction Factor from Reynolds Number and pipe roughness.
  • Figure 8 illustrates the major component parts of a preferred embodiment of the improved reduced noise abrasive blasting system of the subject invention.
  • Figure 9 shows, in cross-section, details of the transition coupling used to step down the inside diameter of the abrasive media path employed in the reduced noise abrasive blasting system illustrated in Figure 8 and the relative geometry of the nozzle and accelerator hose.
  • Figure 10 is a photograph of a prototype reduced noise abrasive blasting accelerator hose and nozzle.
  • Figure 11 is a photograph illustrating, in comparative format, productivity of the invention prototype (left side) and conventional blasting (right side) using #8 nozzle blasting Type V media on half of an exposed coated baking pan for 30 seconds, both with 4 turns of abrasive metering valve knob.
  • Figure 12 is a photograph comparing the results of using a reduced noise blasting system of the subject invention operating with additional abrasive to a conventional system operating with a Marco #8 nozzle.
  • Figure 13 is an autospectrum of a conventional state of the art supersonic abrasive blasting apparatus with a Marco #8 nozzle and the subject invention prototype with Type V media and 40 psi operating pressure, along with background noise levels from blasting compressor unit.
  • Figure 14A-B are side and perspective see-through views, respectively, of a Marco #6 Venturi nozzle.
  • Figure 15 is a sectional view of an XL Venturi #6 nozzle.
  • Figures 16A-B are a side see-through and sectional view, respectively, of an improved blast nozzle, according to an embodiment of the present invention.
  • Figures 17A-B is a side see-through and sectional view, respectively, of an extended length improved blast nozzle, according to an embodiment of the present invention.
  • Figure 18 is a schematic illustrating convergent-divergent nozzle expansion.
  • Figures 19A-B are CFD results showing Mach number distributions at 67 psig nozzle pressure using ANSYS Fluent for a Marco #6 nozzle ( Figure 19A) and for an improved nozzle according to an embodiment of the present invention ( Figure 19B).
  • Figures 20A-B are CFD results showing Mach number distributions at 100 psig nozzle pressure using ANSYS Fluent for a Marco #6 nozzle ( Figure 20A) and for an improved nozzle according to an embodiment of the present invention ( Figure 20B).
  • Figures 21 A-B are CFD results showing Mach number distributions at 67 psig nozzle pressure with added wall drag using ANSYS Fluent for a Marco #6 nozzle ( Figure 21 A) and for an improved nozzle according to an embodiment of the present invention ( Figure 2 IB).
  • Figure 22 is a graph showing average 1/3 octave sound spectra for a variety of nozzles.
  • the acceleration of particles in a stream can be modeled using empirically determined drag coefficient presented previously (Settles & Geppert, 1997) based on data from Bailey and Hialt.
  • the acceleration of a particle of mass, m is found from the drag, D, as
  • A is the cross-sectional area of the sphere and Urei is the relative velocity between the gas and the particle.
  • Illustrated in Figure 4 is the drag coefficient as a function of Mach number for two Reynolds numbers for spheres.
  • SPL sound pressure level
  • SWL sound power level
  • the mass of the sphere is the density of the particle, p panicle multiplied by the volume acceleration becomes
  • the instant invention achieves sufficient abrasive particle velocity through greater acceleration distances in an airstream with a lower exit velocity, thereby reducing nozzle generated noise experience with supersonic blast nozzles. Adjustments to blasting productivity can be made by adjusting the abrasive mass flow rate.
  • Pressure loss or head loss
  • the head loss, or pressure loss, due to friction along a pipe is given by the Darcy-Weisbach equation as
  • L is the length of the pipe section
  • D is the pipe diameter
  • p is the density of the fluid
  • V is the average fluid velocity
  • fu is the Darcy friction factor based on Reynolds Number, Re and relative pipe roughness, e/d and is equal to approximately 0.02 for plastic/rubber.
  • Figure 7 shows a Moody Diagram used for estimation of Friction Factor from Reynolds Number and pipe roughness.
  • a 3 ⁇ 4” inner diameter blast hose operating close to“choked” condition has a velocity of 230 to 340 m/s and a Reynolds number of 300,000 to 436,000. Drag over the length of the hose induces pressure losses which decrease the average velocity in the pipe.
  • Velocity in the hose will be sonic if the choked flow conditions exist where the pressure downstream falls below a critical value
  • p* is 28.9 psia or 14.2 psig.
  • a preferred embodiment of the subject invention was designed that takes airborne particles from the example 1” hose and accelerates them through a smaller diameter hose a sufficient distance such that a productive particle speed is obtained. Transition couplings that step down the inside diameter of the hose provide smooth transitions between the different hose section diameters with minimal pressure losses.
  • compressor 112 pressurizes gas to near 120 psi.
  • Compressed gas is pumped through initial hose section 114 into abrasive media tank 116 containing abrasive media 118.
  • An abrasive metering valve 120 controls the rate of release of abrasive media 118.
  • a standard 1" inside diameter blast hose 124 attaches, at one end to metering valve 120 and, at the other end, to a transition coupling 122.
  • a length of reduced inside diameter, 3/4" for example, accelerator hose 130 connects transition coupling 122 to a nozzle 134 through a claw coupling 132.
  • Transition coupling 122 serves to step down the inside diameter of the path that is taken by abrasive media 118 from the 1" diameter blast hose 124 to the smaller diameter acceleration hose 130.
  • transition coupling 122 is comprised of housing 128 enclosing a bore (not shown).
  • the blast hose side 125 of transition coupling 122 has a 1" inside diameter bore, while the accelerator side 130 of transition coupling 122 has a 3/4" diameter bore.
  • Each side of transition coupling 122 connects with the respective hose using conventional claw coupling 132 technology.
  • the nozzle 134 exit diameter 136 is sized to control the desired abrasive“hot spot” diameter such that the effective blasting region of the reduced noise abrasive blasting system can match that of a conventional supersonic nozzle.
  • Figure 12 illustrates that the prototype operating at the 6-tum setting was clearly more productive than the Marco #8 operating at the 4-turn setting.
  • Other preferred embodiments of the reduced noise abrasive blasting systems of the present invention are systems that employ a new nozzle having a straight section following a diverging section, to accelerate the media particles to a desired velocity prior to the particles exiting the blast nozzle.
  • Such low noise abrasive blasting nozzles are suitable to replace nozzles such as the Marco #6 Venturi nozzle with improved blasting productivity and reduced noise production.
  • the exit shock condition of the new nozzles is designed to dramatically reduce jet noise from flow exiting the nozzle. Comparative testing between a new nozzle and an existing commercial nozzle achieved 17dB(A) noise reduction while showing improvement in productivity in tests with garnet. CFD modeling shows an improved particle acceleration zone. Further, evaluation shows improved productivity and reduced noise with steel shot using a new nozzle versus a Marco #6 Venturi nozzle, with improved productivity, reduced acoustic noise, and reduced handling fatigue.
  • Figure 14A-B are side and perspective see-through views, respectively, of a Marco #6 Venturi nozzle 1400.
  • the total length of the nozzle depicted is 6.53”, with a converging section 1410 2.80” in length, a throat 1420 0.50” in length, and a diverging section 1430 3.13” in length, a 1.25” inner diameter opening, a 0.38” diameter throat, and a 0.55” diameter exit.
  • the exit portion 1440 is 0.10” in length and also diverging.
  • a Venturi nozzle is the standard for abrasive blasting operations. Conventional nozzles are convergent/divergent nozzles such as the Marco #6. The particular version shown has a wide entry which is meant to enhance particle distribution homogeneity.
  • Figure 15 is a sectional view of an XL Venturi #6 nozzle 1500, which has a total length of 11.71 inches as depicted and a longer diverging section 1530 than the standard Marco #6 Venturi nozzle shown in Figures 14A-B (8.31” instead of 3.13”).
  • the converging section 1510, throat 1520, and exit 1540 are identical.
  • Figures 16A-B are a side see-through and sectional view, respectively, of an improved blast nozzle 1600, according to an embodiment of the present invention.
  • the total length of the nozzle shown is 9.07”, with a 0.50” long throat 1620, 3.13” long diverging section 1630, and 2.56” long straight section 1650, with converging portion 1610 making up the remaining length.
  • the inner diameter of the opening is 1.25” the diameter of the throat is 0.375” and the diameter of the straight section is 0.55”.
  • the converging angle is 8.88 degrees and the angle of the diverging exit portion 1640 is 50 degrees.
  • Figures 17A-B is a side see-through and sectional view, respectively, of an extended length improved blast nozzle 1700, according to an embodiment of the present invention, with converging portion 1710, throat 1720, diverging portion 1730, straight portion 1750 and exit portion 1740.
  • This nozzle 1700 has a longer straight section 1750 than the nozzle 1600 shown in Figures 16A-B and is similar in overall length to the XL Venturi #6 nozzle shown in Figure 15, with a total length of 11.71”.
  • the dimensions are identical to those of the nozzle 1600 depicted in Figures 16A-B except that the straight portion 1750 is 5.20” in length.
  • a design that has a lower air exit velocity without reducing the velocity of the abrasive particles allows for equal or greater productivity while greatly reducing sound volume.
  • the new nozzles add a straight section (neither converging nor diverging) to the end of a conventional nozzle design.. This extends the particle accelerating section while reducing the exit Mach number. The extension of the accelerating section is based on the maximum Mach number being achieved at the end of the diverging section, with this maintained more or less until the end of the straight section.
  • the length of this straight section ranges from 1/5 of the nozzle throat diameter to ten times the nozzle throat diameter
  • the added interaction distance between the slower abrasives in the flow and the air slows down the air in a similar way as wall friction, more efficiently accelerating the abrasive particles while reducing the nozzle exit velocity.
  • Figure 18 is a schematic illustrating convergent-divergent nozzle expansion in overexpanded 1810, fully expanded 1820, and underexpanded 1830 conditions.
  • Conventional abrasive blasting nozzles are operated in general at what is considered an overexpanded condition, meaning that the flow passes through an oblique shock 1870 as it exhausts and contracts 1840 after the nozzle exit.
  • Flow is supersonic throughout the divergent portion of the nozzle and at the exit, and the jet pressure adjusts to the atmospheric pressure by means of oblique shock waves 1840 outside the exit plane.
  • fully expanded flow 1850 does not expand or contract after exit, while underexpanded flow expands 1860 after the exit with expansion fans 1880.
  • Reducing the reservoir pressure can, under the right circumstances, induce a normal shock at the exit plane of a nozzle, substantially reducing the velocity of the gas as it exits the nozzle.
  • reducing the reservoir pressure of a conventional abrasive blasting nozzle reduces the particle velocity and renders such a setup impractical.
  • the effect of blasting media on the supersonic flow structure leads to normal shock formation at higher than expected reservoir pressures when the supersonic section is uniformly extended.
  • a long high Mach number nozzle section followed by a normal shock at the nozzle exit reduces the exit speed of the air and thus the acoustic noise generation. This has the same effect as running an abrasive-free nozzle at a low enough pressure to produce a normal shock wave at the exit. Having a normal shock wave at the exit drastically reduces the air exit velocity with little effect on the net abrasive velocity.
  • Figures 19A-B are CFD results 1900, 1901 showing Mach number distributions at 67 psig nozzle pressure using ANSYS Fluent for single phase compressible air flow with no media for a Marco #6 nozzle ( Figure 19A) and for an improved nozzle according to an embodiment of the present invention ( Figure 19B).
  • Figures 20A-B are CFD results 2000, 2001 showing Mach number distributions at 100 psig nozzle pressure using ANSYS Fluent for a Marco #6 nozzle ( Figure 20A) and for an improved nozzle according to an embodiment of the present invention ( Figure 20B). Results clearly show that the improved nozzle has an extended acceleration section over a variety of conditions in comparison to a standard Marco #6 nozzle.
  • the improved nozzle with 67 psig has a slightly lower maximum Mach number than the Marco #6 nozzle (2.21 versus 2.26), but a longer section over which there is supersonic flow to accelerate particles. Similar results were found at a 100 psig nozzle pressure.
  • Figures 21A-B are CFD results 2100, 2101 showing Mach number distributions at 67 psig nozzle pressure with added wall drag using ANSYS Fluent for a Marco #6 nozzle ( Figure 21 A) and for an improved nozzle according to an embodiment of the present invention (Figure 2 IB).
  • the added wall drag uses an increased wall friction coefficient to simulate drag from particles on the flow. The main takeaway from this result is that the long straight nozzle section of the improved nozzle creates a greater effect on the flow structure.
  • the sound level was measured using a sound level meter at the operator’s left shoulder while operating the nozzle into open air (to avoid the sound generated by sand hitting metal during actual blasting).
  • the sound levels for the 1/3 octave bands were measured for a 10 second period and MIN, MAX and AVG sound levels were automatically calculated and stored. Background sound levels were also recorded to confirm that background noise did not contribute to the measured noise levels of the nozzles.
  • Table 1 summarizes the key results of the testing along with some operator comments. From the first round of testing the quietest and most productive nozzle was an improved nozzle termed Oceanit BN6V1, or Oceanit Short SS, which is the nozzle shown schematically in
  • Figures 17A-B It was 16 dB quieter and cleaned a test panel in 51 seconds vs 69 seconds for the standard long Venturi.
  • the XL nozzle (XL Venturi #6) showed some improvement in sound performance but no gains in productivity, and was deemed too large and heavy for everyday use.
  • BNG-V2 are lower than the standard Venturi 2210 across the entire spectrum and substantially lower than the Venturi XL 2220 across most of the spectrum as well. Also worth noting is the spike 2250 centered on 4000 Hz for the standard Venturi nozzle (Marco #6) which may be associated with greater turbulence generation from a high-speed jet and/or jet screech- which is avoided by a subsonic exit velocity after a normal shock at the nozzle exit.
  • the new reduced noise producing abrasive blasting nozzle is demonstrated to be superior in a commercial abrasive blasting setting.
  • High particle speeds produce productive nozzles.
  • Low exit air velocities produce low noise nozzles.
  • the new nozzles maintain or improve the abrasive particle velocity exiting the nozzle while reducing the exit air velocity.
  • the new nozzles (based on a #6 Venturi) utilize an extended exit section which extends the high-Mach number acceleration zone of the nozzle while producing a much lower exit velocity, in part (in some embodiments) through the creation of a normal shock wave at the end of the nozzle.
  • the productivity of the new nozzles was shown to be better than the standard Marco #6 Venturi nozzle in tests with garnet and steel shot while achieving 17dB noise reduction over commercial nozzles, reduced kickback and resulting user fatigue, and improved handling characteristics.
  • CFD modeling shows an improved particle acceleration zone.
  • Weighted Average alleviates the employers need to modify employees’ current practices, decreases the need for personal protective equipment (PPE), reduces the likelihood of injury in the case of PPE failure, and ensures that personnel in adjacent“safe zones” are guaranteed to be safe from exposure. Most importantly, reducing noise in the blasting facility to 90 dBA or less allows workers to operate for a full 8-hour standard work day within OSHA compliance.
  • PPE personal protective equipment
  • a #6 nozzle embodiment may be any size, including #8, #7, and #5 nozzles and a #6 90-degree nozzle.
  • the same design can be applied to any converging-diverging nozzle, using any type of abrasive media/material, including coal slag, garnet, acrylic, etc.
  • the new nozzles may be made, for example, of ceramic or stainless steel (with or without a wear-resistant ceramic liner), and of any known nozzle material.
  • the nozzles may have protective grips to improve handling and eliminate concerns of static electricity for stainless steel versions.
  • the nozzles may be designed for and used with a variety of hose pressures and blast patterns.
  • the reduced noise abrasive blasting systems of the present invention allow for abrasive blasting with significantly reduced resultant noise while providing the equivalent or improved productivity and efficiency compared with conventional abrasive blasting systems.
  • the improved reduced noise blasting system promotes worker health and safety and a quieter environment for those in the vicinity.
  • the improved abrasive blasting system exploits a lengthened accelerator section in the hosing and/or nozzle in order to maintain particle velocity while decreasing the gas exit velocity.
  • a straight bore nozzle can be used to produce the desired active abrasive area.
  • the maintained particle velocity provides the equivalent abrasive productivity while the decreased gas velocity provides for the reduced resultant noise.
  • the nozzle and hose dimensions, and the coupling types, and the specific configuration and sizes of hose, couplings, nozzle and accelerator section can be varied in accordance with the general principals of the invention as described herein in order to accommodate different working conditions, target materials, project specification, budgetary considerations and user preferences.
  • the nozzle may have any throat diameter, e.g. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc., including in embodiments featuring a new nozzle having a straight section.
  • more than one transition coupling and accelerator hose section and inside diameter may be employed in the systems of the subject invention.
  • the invention described herein is inclusive of all such modifications and variations.

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Abstract

L'invention concerne des ensembles et des systèmes de traitement au jet abrasif à bruit réduit. Les nouveaux ensembles et systèmes sont constitués d'un tuyau de soufflage standard, d'un tuyau d'accélérateur, de raccords et d'une buse. Le système de traitement au jet abrasif amélioré maintient constante la vitesse des particules abrasives tout en diminuant la vitesse du gaz de sortie, diminuant ainsi la production sonore. Ceci est accompli grâce à une section d'accélération ayant un diamètre interne réduit et une longueur suffisante pour fournir la vitesse de particule abrasive nécessaire. Le nouveau système conserve la productivité et l'efficacité des systèmes de traitement au jet abrasif classiques mais avec une production de bruit acoustique considérablement réduite, et réduit la fatigue de l'opérateur grâce au poids inférieur de la partie portée du système.
PCT/US2019/065783 2018-12-11 2019-12-11 Systèmes de traitement au jet abrasif à bruit réduit Ceased WO2020123697A1 (fr)

Priority Applications (8)

Application Number Priority Date Filing Date Title
US16/819,035 US12280468B2 (en) 2018-12-11 2020-03-13 Method and design for productive quiet abrasive blasting nozzles
EP20897655.5A EP4072778A4 (fr) 2019-12-11 2020-03-28 Procédé et conception pour buses silencieuses productives d'abrasion par projection
JP2022535240A JP7574297B2 (ja) 2019-12-11 2020-03-28 生産性が高い静音研磨材ブラストノズルのための方法及び設計
KR1020227022777A KR20220110268A (ko) 2019-12-11 2020-03-28 생산적인 저소음 연마재 분사 노즐을 위한 방법 및 설계
PCT/US2020/025586 WO2021118625A1 (fr) 2019-12-11 2020-03-28 Procédé et conception pour buses silencieuses productives d'abrasion par projection
CA3159321A CA3159321A1 (fr) 2019-12-11 2020-03-28 Procede et conception pour buses silencieuses productives d'abrasion par projection
CN202080086029.XA CN114829068B (zh) 2019-12-11 2020-03-28 用于高生产率的安静的磨料喷射喷嘴的方法和设计
AU2020399540A AU2020399540B2 (en) 2019-12-11 2020-03-28 Method and design for productive quiet abrasive blasting nozzles

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WO2024119226A1 (fr) * 2022-12-05 2024-06-13 Blastone Technology Pty Ltd Appareil de réduction de bruit
EP4255675A4 (fr) * 2020-12-02 2024-10-30 Blastone Technology Pty Ltd. Silencieux pour buse de soufflage
EP4255676A4 (fr) * 2020-12-02 2024-12-11 Blastone Technology Pty Ltd. Système de réduction de poussée pour une buse de soufflage

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EP4255675A4 (fr) * 2020-12-02 2024-10-30 Blastone Technology Pty Ltd. Silencieux pour buse de soufflage
EP4255676A4 (fr) * 2020-12-02 2024-12-11 Blastone Technology Pty Ltd. Système de réduction de poussée pour une buse de soufflage
WO2024119226A1 (fr) * 2022-12-05 2024-06-13 Blastone Technology Pty Ltd Appareil de réduction de bruit

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