METHODS AND APPARATUSES FOR DEFROSTING AND CLEARING INTERNAL COMPONENTS OF A BLASTING APPARATUS

Abstract

A particle blast apparatus comprises an interior cavity, a defrost port in fluid communication with the interior cavity, such that defrost gas is selectively introduced into the interior cavity through the defrost port; and an internal flow path extending from a source of blast media to a transport gas flow path, wherein at least a portion of the internal flow path extends through the interior cavity. A method of defrosting a particle blast apparatus that uses cryogenic materials comprises providing a particle blast apparatus comprising an interior cavity, an internal flow path extending from a source of blast media to a transport gas flow path through an interior cavity, and introducing defrost gas into the interior cavity.

Claims

1. A particle blast apparatus comprising: a. an interior cavity; b. a defrost port in fluid communication with the interior cavity, such that defrost gas is selectively introduced into the interior cavity through the defrost port; and c. an internal flow path extending from a source of blast media to a transport gas flow path, wherein at least a portion of the internal flow path extends through the interior cavity.

2. The particle blast apparatus of claim 1 further comprising a defrost valve in fluid communication with the defrost port.

3. The particle blast apparatus of claim 1 further comprising a comminutor, wherein the comminutor is disposed within the interior cavity.

4. The particle blast apparatus of claim 3 further comprising a metering element, wherein the metering element is disposed upstream of the comminutor.

5. The particle blast apparatus of claim 4, wherein the interior cavity is disposed within a housing, wherein the particle blast apparatus further comprises a first skirt engaged with a first side of the housing and a second skirt engaged with a second side of the housing, wherein the second side of the housing is opposite the first side of the housing.

6. The particle blast apparatus of claim 1, wherein the interior cavity is disposed within a housing.

7. The particle blast apparatus of claim 5, further comprising a first skirt engaged with a first side of the housing.

8. The particle blast apparatus of claim 6, further comprising a second skirt engaged with a second side of the housing, wherein the second side of the housing is opposite the first side of the housing.

9. The particle blast apparatus of claim 1, wherein the source of blast media is a source of cryogenic blast media.

10. A method comprising: a. providing a particle blast apparatus, wherein the particle blast apparatus comprises i. an interior cavity, and ii. an internal flow path extending from a source of blast media to a transport gas flow path, wherein at least a portion of the internal flow path extends through the interior cavity; and b. introducing defrost gas into the interior cavity.

11. The method of claim 10, wherein the particle blast apparatus further comprises a defrost valve and a defrost port, wherein the defrost port is in fluid communication with the defrost valve and the interior cavity, wherein the defrost gas introducing step further comprises activating the defrost valve.

12. The method of claim 10, wherein the particle blast apparatus further comprises a metering element disposed upstream of the transport gas flow path, wherein the method further comprises causing the metering element to remain rotationally stationary.

13. The method of claim 10, wherein the particle blast apparatus further comprises a comminutor disposed within the interior cavity, wherein the comminutor comprises a first roller and a second roller, wherein the method further comprises rotating at least one of the first roller and the second roller.

14. The method of claim 10, wherein the particle blast apparatus further comprises a feeding rotor disposed upstream of the transport gas flow path, wherein the method further comprises causing the feeding rotor to remain rotationally stationary.

15. The method of claim 10, wherein the particle blast apparatus further comprises a comminutor disposed within the interior cavity and a feeding rotor disposed between the comminutor and the transport gas flow path, wherein the comminutor comprises a first roller and a second roller, wherein the method further comprises rotating at least one of the first roller and the second roller while introducing defrost gas into the interior cavity and causing the feeding rotor to remain rotationally stationary while introducing defrost gas into the interior cavity.

16. The method of claim 10 further comprising stopping blast media from entering the interior cavity while introducing defrost gas into the interior cavity.

17. The method of claim 10 further comprising introducing a flow of transport gas along the transport gas flow path while introducing defrost gas into the interior cavity.

18. The method of claim 10, wherein the particle blast apparatus further comprises: a. a comminutor disposed within the interior cavity, wherein the comminutor comprises a first roller and a second roller; b. a metering element disposed upstream of the comminutor; and c. a feeding rotor disposed intermediate the comminutor and the transport gas flow path, wherein the method further comprises causing the metering element to remain rotationally stationary while rotating at least one of the first roller and the second roller, causing the feeding rotor to remain rotationally stationary, introducing a flow of transport gas along the transport gas flow path, and introducing defrost gas into the interior cavity.

19. A method comprising: a. providing a particle blast apparatus, wherein the particle blast apparatus comprises i. an interior cavity, ii. a comminutor, wherein the comminutor is disposed within the interior cavity, wherein the comminutor comprises 1. a first roller, 2. a second roller, and 3. a gap defined by an outer surface of the first roller and an outer surface of the second roller, wherein the gap has a size, wherein the second roller is movable relative to the first roller between a first position at which the gap size is a first gap size and a second position at which the gap size is a second gap size, wherein the second gap size is greater than the first gap size; b. introducing defrost gas into the interior cavity; c. rotating at least one of the first roller and the second roller; and d. adjusting the size of the gap.

20. The method of claim 19, wherein introducing defrost gas into the interior cavity occurs while rotating at least one of the first roller and the second roller and adjusting the size of the gap.

21. The method of claim 20 further comprising stopping blast media from entering the interior cavity while introducing defrost gas into the interior cavity, rotating at least one of the first roller and the second roller, and adjusting the size of the gap.

22. The method of claim 21, wherein the particle blast apparatus further comprises a feeding rotor disposed downstream of the comminutor, wherein the method further comprises rotating the feeding rotor while stopping blast media from entering the interior cavity, introducing defrost gas into the interior cavity, rotating at least one of the first roller and the second roller, and adjusting the size of the gap.

23. The method of claim 22 further comprising introducing a flow of transport gas into the particle blast apparatus while rotating the feeding rotor, stopping blast media from entering the interior cavity, introducing defrost gas into the interior cavity, rotating at least one of the first roller and the second roller, and adjusting the size of the gap.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The accompanying drawings illustrate embodiments which serve to explain the principles of the present innovation.

[0009] FIG. 1 diagrammatically illustrates a particle blast apparatus.

[0010] FIG. 2 is a front perspective view of a feeder assembly that may be carried by the particle blast apparatus of FIG. 1.

[0011] FIG. 3 is a front perspective view of the feeder assembly of FIG. 2, with drives omitted for clarity.

[0012] FIG. 4 is a rear perspective view of the feeder assembly of FIG. 2.

[0013] FIG. 5 is a cross-sectional perspective view of the feeder assembly of FIG. 3 taken through a vertical plane passing through the midline of the feeder assembly.

[0014] FIG. 6A is a cross-sectional side view of the feeder assembly of FIG. 4 taken at the same vertical plane as in FIG. 5.

[0015] FIG. 6B is an enlarged fragmentary cross-sectional side view of the metering element and guide.

[0016] FIG. 6C is a cross sectional view taken along line 6C-6C of FIG. 6A.

[0017] FIG. 7 is an exploded perspective view of the feeding portion of the feeder assembly.

[0018] FIG. 8 is an exploded perspective view of the metering portion and the comminutor of the feeder assembly.

[0019] FIG. 9 is an exploded perspective view of the metering portion and the comminutor of the feeder assembly.

[0020] FIG. 10 is a perspective view of an embodiment of a skirt.

[0021] FIG. 11 is a cross-sectional perspective view of the feeder assembly similar to FIG. 5, taken at a different angle and through a different vertical plane, one which does not pass through the midline of the feeder assembly.

[0022] FIG. 12 is a cross-sectional perspective view of the feeder assembly, similar to FIG. 11, taken through a vertical plane which passes through the midline of the feeder assembly, illustrating a larger gap between the rollers of the comminutor.

[0023] FIG. 13 is a cross-sectional side view of the feeder assembly taken at the same vertical plane as in FIG. 12, illustrating the same size gap between the rollers of the comminutor.

[0024] FIG. 14 is a cross-sectional side view of the feeder assembly similar to FIG. 13, illustrating a gap size smaller than the maximum gap size and larger than the minimum gap size.

[0025] FIG. 15 is a top view of the rollers of the comminutor illustrating the diamond pattern formed by the raised ridges in the converging region.

[0026] FIG. 16 is a bottom view of the rollers of the comminutor illustrating the X pattern formed by the raised ridges in the diverging region.

[0027] FIG. 17 is a top view of the metering element through the guide.

[0028] FIG. 18 is a perspective view of the metering element.

[0029] FIG. 19 is a plan view of the end profile of the metering element of FIG. 18, taken at line 19-19 of FIG. 18.

[0030] FIG. 20 is a plan view of a profile of the metering element of FIG. 18, taken at line 20-20 of FIG. 18.

[0031] FIG. 21 is a plan view of a profile of the metering element of FIG. 18, taken at line 21-21 of FIG. 18.

[0032] FIG. 22 is a bottom view of the metering element through the guide.

[0033] FIG. 23 is a perspective view of a pressure regulator assembly.

[0034] FIG. 24 is a cross-sectional top view of the actuator of the pressure regulator assembly of FIG. 23.

[0035] FIG. 25 is a schematic diagram of a pneumatic circuit.

[0036] FIG. 26 is a cross-sectional top view of the actuator similar to FIG. 23.

[0037] FIG. 27 is a cross-sectional side view of a ball valve.

[0038] FIG. 28 is a schematic diagram of a pneumatic circuit.

[0039] FIG. 29 is a flow chart depicting steps in an embodiment of a defrost mode.

[0040] FIG. 30 is a flow chart depicting steps in an embodiment of a clog clearing mode.

DETAILED DESCRIPTION

[0041] In the following description, like reference characters designate like or corresponding parts throughout the several views. Also, in the following description, it is to be understood that terms such as front, back, inside, outside, and the like are words of convenience and are not to be construed as limiting terms. Terminology used in this patent is not meant to be limiting insofar as devices described herein, or portions thereof, may be attached or utilized in other orientations. Referring in more detail to the drawings, one or more embodiments constructed according to the teachings of the present innovation are described.

[0042] It should be appreciated that any patent, publication, or other disclosure material, in whole or in part, that is said to be incorporated by reference herein is incorporated herein only to the extent that the incorporated material does not conflict with existing definitions, statements, or other disclosure material set forth in this disclosure. As such, and to the extent necessary, the disclosure as explicitly set forth herein supersedes any conflicting material incorporated herein by reference.

[0043] Although this patent refers specifically to carbon dioxide, the invention is not limited to carbon dioxide but rather may be utilized with any suitable frangible material as well as any suitable cryogenic material or other type of particle such as water ice pellets or abrasive media. References herein to carbon dioxide, at least when describing embodiments which serve to explain the principles of the present innovation are not necessarily limited to carbon dioxide but are to be read to include any suitable frangible or cryogenic material.

[0044] Referring to FIG. 1, there is shown a representation of a particle blast apparatus, generally indicated at 2, which includes cart 4, delivery hose 6, hand control 8, and discharge nozzle 10. Internal to cart 4 is a blast media delivery assembly (not shown in FIG. 1) which includes a hopper and a feeder assembly disposed to receive particles from the hopper and to entrain particles into a flow of transport gas. Particle blast apparatus 2 is connectible to a source of transport gas, which may be delivered in the embodiment depicted by hose 12 which delivers a flow of air at a suitable pressure, such as, but not limited to, 70-80 PSIG. Particle blast apparatus 2 is also connectible to a source of defrost gas, which may be delivered in the embodiment depicted by hose 13 which delivers a flow of gas at a suitable pressure, such as, but not limited to, about 70-80 PSIG. Hose 12 and hose 13 are each depicted as a flexible hose, but any suitable structure may be used to convey the transport gas and defrost gas. In some embodiments, at least a portion of hose 12 and hose 13 may comprise a single hose, while in other embodiments hose 12 and hose 13 may be separate hoses. Hose 13 may be connected to particle blast apparatus 2 via defrost valve 306 and defrost port 21 (described below) in order to allow defrost gas to be selectively introduced into the interior of particle blast apparatus 2. In some embodiments, the defrost gas has a pressure of about 80 PSIG when it reaches defrost port 21 from defrost valve 306. After passing through defrost port 21, in some embodiments, the pressure of the defrost gas may vary from almost zero PSIG to about 80 PSIG depending on if the interior portion of particle blast apparatus 2 where the defrost gas is introduced (e.g., roller cavity 51 (described below)) is air tight (i.e., completely sealed) or if there are gaps present that allow the defrost gas to escape to atmosphere. The pressure of defrost gas in the interior of particle blast apparatus 2 is greater the closer the interior of particle bast apparatus 2 is to being completely sealed. In some embodiments, the transport gas and the defrost gas may be supplied by the same source, although this is not necessarily required. In some embodiments, the defrost gas may comprise air. Preferably, the temperature of the defrost gas is greater than or equal to about minus 78 degrees Celsius, and more preferably the temperature of the defrost gas is greater than or equal to about zero degrees Celsius. If the temperature of the defrost gas is greater than or equal to about minus 78 degrees Celsius but less than zero degrees Celsius, then that defrost gas will help sublimate ice that is formed of carbon dioxide particles. If the temperature of the defrost gas is greater than or equal to about zero degrees Celsius, then that defrost gas will help melt both ice that is formed of carbon dioxide particles and ice that is formed of water (commonly referred to as water ice.)

[0045] Blast media, such as, but not limited to, carbon dioxide particles, indicated at 14, may be deposited into the hopper through top 16 of the hopper. The carbon dioxide particles may be of any suitable size, such as, but not limited to, a diameter of 3 mm and a length of about 3 mm. The feeder assembly entrains the particles into the transport gas, which thereafter flow at a subsonic speed through the internal flow passageway defined by delivery hose 6. Delivery hose 6 is depicted as a flexible hose, but any suitable structure may be used to convey the particles entrained in the transport gas. Hand control 8 allows the operator to control the operation of particle blast apparatus 2 and the flow of entrained particles. Downstream of control 8, the entrained particles flow into entrance 10a of discharge nozzle 10. The particles flow from exit 10b of discharge nozzle 10 and may be directed in the desired direction and/or at a desired target, such as a work piece (not shown).

[0046] Discharge nozzle 10 may be of any suitable configuration, for example, discharge nozzle 10 may be a supersonic nozzle, a subsonic nozzle, or any other suitable structure configured to advance or deliver the blast media to the desired point of use.

[0047] Control 8 may be omitted and the operation of the system controlled through controls on cart 4 or other suitable location. For example, the discharge nozzle 10 may be mounted to a robotic arm and control of the nozzle orientation and flow accomplished through controls located remote to cart 4.

[0048] Referring to FIGS. 2-4, there is shown hopper 18 (shown in dashed lines for clarity) and feeder assembly 20 of particle blast apparatus 2. Hopper 18 may include a device (not shown) for imparting energy to hopper 18 to aid in the flow of particles therethrough. Hopper 18 is a source of blast media, such as cryogenic particles, for example, but not limited to, carbon dioxide particles. Hopper exit 18a is aligned with guide 22, at hopper seal 24. Any suitable source of blast media may be used, such as without limitation, a pelletizer.

[0049] Feeder assembly 20 is configured to transport blast media from a source of blast media into a flow of transport gas, with the blast media particles being entrained in the transport gas as the flow leaves feeder assembly 20 and enters delivery hose 6. In the embodiment depicted, feeder assembly 20 includes metering portion 26, comminutor 28 and feeding portion 30. Feeder assembly 20 may also be referred to as core 20 and metering portion 26 and comminutor 28 may be referred to collectively as particle control system (PCS) 27. As discussed below, comminutor 28 may be omitted from feeder assembly 20 metering portion 28 may be omitted from feeder assembly 20, and feeding portion 30 may be of any construction which entrains particles into the transport gas whether a single hose, multiple hose and/or venturi type system. The pressure and flow of transport gas delivered to feeding portion 30 is controlled by pressure regulator assembly 32. In embodiments that include metering portion 26 but omit comminutor 28, metering portion 26 may discharge directly to feeding portion 30. In embodiments that omit metering portion 26 but include comminutor 28, comminutor 28 may receive particles directly from a source of blast media such as hopper 18. In embodiments that omit metering portion 26 and comminutor 28, feeding portion 30 may receive particles directly from a source of blast media, such as hopper 18.

[0050] Feeder assembly 20 includes a plurality of motors to drive its different portions. These motors may be of any suitable configuration, such as pneumatic motors and electric motors, including, but not limited to, DC motors and VFD. Metering portion 26 includes drive 26a, which, in the embodiment depicted, provides rotary power. In the embodiment depicted, comminutor 28 includes three drives, 28a, 28b, and 28c which provide rotary power. In the embodiment depicted, feeding portion 30 includes drive 30a, which provides rotary power through right angle drive 30b. Any suitable quantity, configuration and orientation of drives, with or without the presence of right angle drives, may be used. For example, fewer motors may be used with appropriate mechanisms to transmit power to the components at the appropriate speeds (such as chains, belts, gears, etc.). As can be seen in FIG. 3, with the drives and right angle drive removed, locating pins may be used to locate the drives.

[0051] Feeder assembly 20 may include one or more actuators 34, each having at least one extendable member (not illustrated), disposed to be selectively extended into the particle flow from hopper 18 to feeder assembly 20 at guide 22, capable of mechanically breaking up clumps of particles, as such is described in U.S. Pat. No. 6,524,172.

[0052] As can be seen in FIG. 4, feeder assembly 20 includes a defrost port 21 configured to allow defrost gas to be introduced into feeder assembly 20. In the illustrated embodiment, defrost port 21 is located on support 96a (described in more detail below).

[0053] Referring also to FIGS. 5 and 6A, metering portion 26 includes guide 22 and metering element 36. Metering element 36 is configured to receive blast media, such as cryogenic particles, from a source of blast media, such as hopper 18, at first region 38 and to discharge blast media at second region 40. Metering element 36 includes outer peripheral surfaces 36c. Guide 22 may be made of any suitable material, such as aluminum, stainless steel, or plastic. Guide 22 is configured to guide blast media from hopper 18 to first region 38. Guide 22 may have any configuration suitable to guide blast media from hopper 18 to first region 38, such as, without limitation, converging walls. Metering element 36 is configured to control the flow rate of blast media for particle blast apparatus 2. The rate may be expressed using any nomenclature, such as mass (or weight) or volume per unit time, such as pounds per minute. Metering element 36 may be configured in any way suitable to control the blast media flow rate. In the embodiment depicted, metering element 36 is configured as a rotor-a structure which is rotatable about an axis, such as axis 36a. In the embodiment depicted, metering element 36 is supported by shaft 36b, with a key/keyway arrangement preventing rotation between metering element 36 and shaft 36b. Drive 26a is coupled to shaft 36b and may be controlled to rotate shaft 36b about axis 36a, thereby rotating metering element 36 about axis 36a. Metering element 36 will also be referred to herein as rotor 36, metering rotor 36 or even doser 36, it being understood that references to metering element 36 as a rotor or a doser shall not be interpreted in a manner which limits metering element to the rotor structure illustrated. As a non-limiting example, metering element 36 may be a reciprocating structure. Metering rotor 36, as depicted, includes a plurality of cavities 42, which are also referred to herein as pockets 42. Pockets 42 may be of any size, shape, number or configuration. In the embodiment depicted, pockets 42 open radially outwardly and extend between the ends of metering rotor 36, as described below. Rotation of metering rotor 36 cyclically disposes each pocket 42 at a first position adjacent first region 38 to receive particles and a second position adjacent second region 40 to discharge particles.

[0054] Comminutor 28 includes roller 44 which is rotatable about an axis, such as axis 44a and roller 46 which is rotatable about an axis, such as axis 46a. In the embodiment depicted, roller 44 is supported by shaft 44b, with a key/keyway arrangement preventing rotation between roller 44 and shaft 44b. Drive 28a is coupled to shaft 44b and may be controlled to rotate shaft 44b about axis 44a, thereby rotating roller 44 about axis 44a. In the embodiment depicted, roller 46 is supported by shaft 46b, with a key/keyway arrangement preventing rotation between roller 46 and shaft 46b. Drive 28b is coupled to shaft 46b and may be controlled to rotate shaft 46b about axis 46a, thereby rotating roller 46 about axis 46a. Rollers 44, 46 may be made of any suitable material, such as aluminum.

[0055] Rollers 44 and 46 have respective peripheral surfaces 44c, 46c. Gap 48 is defined between each respective peripheral surface 44c, 46c. Converging region 50 is defined upstream of gap 48 by gap 48 and rollers 44, 46. (Downstream is the direction of flow of blast media through feeder assembly 20, and upstream is the opposite direction.) Converging region 50 is disposed to receive blast media from second region 40 which has been discharged by metering element 36. Diverging region 52 is defined downstream of gap 48 by gap 48 and rollers 44, 46.

[0056] Comminutor 28 is configured to receive blast media, which comprises a plurality of particles, such as carbon dioxide particles, from metering element 36 and to selectively reduce the size of the particles from the particles' respective initial sizes to a second size which is smaller than a predetermined size. In the embodiment depicted, comminutor 28 receives blast media from metering portion 26/metering element 36. In an alternative embodiment, metering portion 26/metering element 36 may be omitted and comminutor 28 may receive blast media from any structure, including directly from a source of blast media, including, but not limited to, hopper 18. As is known, rollers 44, 46 are rotated to move peripheral surfaces 44c, 46c in the downstream direction at gap 48, the terminus of converging region 50. As blast media particles travel in the downstream direction through gap 48, the sizes of particles which are initially larger than the width of gap 48 between peripheral surfaces 44c, 46c will be reduced to a second size based on the gap size.

[0057] The size of gap 48 may be varied between a minimum gap and a maximum gap. The maximum gap and minimum gap may be any suitable size. The maximum gap may be large enough that none of the particles traveling through gap 48 undergo a size change. The minimum gap may be small enough that all of the particles traveling through gap 48 undergo a size change. Depending on the maximum gap size, there may be a gap size, which is less than the maximum gap size, at which comminution of particles first begins. At gap sizes at which less than all of the particles traveling through gap 48 are comminuted, comminutor 28 reduces the size of a plurality of the plurality of particles. In some embodiments, the minimum gap is configured to comminute particles to a very fine size, such as 0.012 inches, which may be referred to in the industry as microparticles, with the minimum gap being as small as 0.006 inches in some embodiments. In some embodiments, the maximum gap is configured to not comminute any particles, with the maximum gap being 0.7 inches. Any suitable minimum and maximum gap may be used.

[0058] Feeding portion 30 may be of any design which is configured to receive blast media particles and introduce the particles into the flow of transport gas, entraining them in the flow. In the embodiment depicted, feeding portion 30 includes feeding rotor 54, guide 56 disposed between gap 48 and feeding rotor 54, and lower seal 58. Feeding rotor 54 is rotatable about an axis, such as axis 54a. In the embodiment depicted, shaft 54b (see FIG. 7) is integral with feeding rotor 54, and may be of unitary construction. Alternately, shaft 54b may be a separate shaft which carries feeding rotor 54 so that feeding rotor 54 does not rotate with respect to shaft 54b. Feeding rotor 54 may be made of any suitable material, such as stainless steel.

[0059] As illustrated, drive 30a is coupled to shaft 54b, through right angle drive 30b, and may be controlled to rotate shaft 54b and, concomitantly, feeding rotor 54 about axis 54a.

[0060] Feeding rotor 54 comprises peripheral surface 54c (see FIG. 7), also referred to herein as circumferential surface 54c, which has a plurality of pockets 60 disposed therein. Each pocket 60 has a respective circumferential width. Guide 56 defines cavity 57. Guide 56 is configured to receive particles from comminutor 28 and guide the particles through cavity 57 into pockets 60 as feeding rotor 54 is rotated about axis 54a. As mentioned above, in some embodiments, comminutor 28 may be omitted from feeder assembly 20 with guide 56 receiving particles directly from metering element 36. In addition, in some embodiments, metering element 36 and comminutor 28 may be omitted from feeder assembly 20 with guide 56 receiving particles directly from a source of blast media, such as hopper 18. Guide 56 includes wiping edge 56a adjacent peripheral surface 54c and extending longitudinally, generally parallel to axis 54a. Feeding rotor 54 rotates in the direction indicated by the arrow such that wiping edge 56a defines a nip line for feeding rotor 54 and functions, with the rotation of feeding rotor 54, to force particles into pockets 60. During operation of the particle blast apparatus 2, ice can form in pockets 60 on feeding rotor 54. As a result, the particles may not be effectively evacuated from pockets 60, which can result in a build up of ice and particles within roller cavity 51, thereby inhibiting the rotation of rollers 44, 46, blocking the flow of particles within feeder assembly 20, and negatively impacting the overall performance of particle blast apparatus 2.

[0061] Lower seal 58 seals against peripheral surface 54c. Lower seal 58 may be of any suitable configuration.

[0062] Feeding portion 30 defines transport gas flow path 62 indicated by flow lines 62a and 62b through which transport gas flows during operation of particle blast apparatus 2. Transport gas flow path 62 is connectable to a source of transport gas, either directly or through pressure regulator assembly 32 (described below), with the appropriate fittings external to feeding portion 30. Transport gas flow path 62 may be defined by any suitable structure and configured in any suitable way which allows the entrainment of particles discharged from pockets 60 into the transport gas. In the embodiment depicted, lower seal 58 and piston 64 define at least a portion of transport gas flow path 62, with part of flow path 62 being through pockets 60, as described in U.S. Pat. No. 11,607,774.

[0063] Rotation of feeding rotor 54 introduces particles into the flow of transport gas, entraining them in the flow. The entrained flow (particles and transport gas) flows through delivery hose 6 and out discharge nozzle 10. Thus, there is a particle flow path extending between the source of blast media to the discharge nozzle, which, in the embodiment depicted, extends through metering portion 26, comminutor 28 and feeding portion 30.

[0064] Referring to FIG. 6B, there is shown an enlarged fragmentary cross-sectional view of metering rotor 36 and guide 22. Guide 22 includes wiping edge 22a disposed adjacent outer peripheral surfaces 36c of metering rotor 36. Outer peripheral surfaces 36c travel past wiping edge 22a as metering rotor 36 is rotated. Wiping edge 22a is configured to wipe across opening 42a of each pocket 42 as metering rotor 36 is rotated. Wiping edge 22a is disposed at wiping angle a relative to a tangent to metering rotor 36, with an arcuate section transitioning from the sloped sides of guide 22 to wiping edge 22a. In the embodiment depicted, this arcuate transition section has a radius of 0.29 inches, although any suitable radius or transition shape may be used. As used herein, wiping angle is the angle formed between the wiping edge and a tangent to metering rotor as illustrated in FIG. 6B. Wiping angle a is configured to not result in a nip line between wiping edge 22a and outer peripheral surfaces 36c as metering rotor 36 is rotated in the direction indicated. If a nip line is present at this location, particles could be forced and/or crushed into pockets 42, which for carbon dioxide particles, results in the particles tending not to fall out of the pocket at discharge. In the embodiment depicted, wiping angle a is greater than 90.

[0065] FIG. 6C illustrates the overhang of entrance 22 relative to metering rotor 36, the overhang of housing 94 relative to roller 44, and that roller 44 (and correspondingly roller 46) is wider than metering rotor 36. As shown, surface 22c of entrance 22 axially overhangs first end 36d of metering rotor 36 and surface 22d of entrance 22 axially overhangs second end 36e. The upper portions of both ends 36d, 36e are disposed in recesses, defined by surfaces 22c, 22d in housings 94f, 94e respectively. With this construction, particles traveling through guide 22 are blocked from reaching ends 36d, 36e. Similarly, surfaces 94a and 94b overhang the ends of roller 44 (and concomitantly the ends of roller 46, not seen in FIG. 6C). The upper portions of both ends of rollers 44, 46 are disposed in recesses. As can be seen in FIG. 6C, roller 44 (and concomitantly roller 46) is wider than metering rotor 36. This construction avoids ledges where ice could build up.

[0066] Referring to FIG. 7, an exploded perspective view of feeding portion 30 is depicted. In addition to the above description, in the embodiment depicted, feeding portion 30 includes housing 66 and base 68. Base includes centrally disposed raised portion 70. Similar to the structure described in U.S. Pat. No. 10,315,862, an internal cavity of piston 64 sealingly engages raised portion 70, forming a chamber which is in fluid communication with the transport gas. Spring 72 is disposed to urge piston upwardly, with pilot 74 engaging piston 64 as seen in FIG. 6A. In the embodiment depicted, lower seal 58 is secured to piston 64 by fasteners 76 with appropriate seals.

[0067] Housing 66 includes bores 66a, 66b which receive bearings 78a, 78b. Bearings 78a, 78b rotatably support feeding rotor 54. Bearing 78a is retained in bore 66a by retainer 80 which is secured to housing 66. Bearing 78b is retained in bore 66b by support 82, which is secured to housing by fasteners 84. Right angle drive 30b may be attached to support 82. Housing 66 may be made of any suitable material, such as aluminum.

[0068] Inlet 86 and outlet 88 (see FIG. 6A) of transport gas flow path 62 are formed in housing 66 as shown. Fittings 90, 92 sealing engage housing 66 at inlet 86 and outlet 88, respectively, with retainers 90a, 92a securing them thereto.

[0069] Referring to FIGS. 8 and 9, there are illustrated exploded perspective views of metering portion 26 and comminutor 28. In the depicted embodiment, housing 94 houses metering rotor 36 and rollers 44, 46. Shaft 36b may be rotationally supported by bearings 36f. Housing 94 may be made of any suitable material, such as aluminum, and of any suitable configuration. In the embodiment depicted, housing 94 comprises eight parts. As illustrated, housings 94a and 94b carry roller 44, while housings 94c and 94d carry roller 46. Housings 94e and 94f carry metering rotor 36. Housing 94 also includes skirts 95c and 95d. In the illustrated embodiment, skirt 95c comprises a substantially solid panel that is attached to an outer surface of housing 94c and skirt 95d comprises a substantially solid panel that is attached to an outer surface of housing 94d. Skirts 95c, 95d may be made of any suitable material, including, but not limited to, polycarbonate plastic, such as Lexan. As shown, each skirt 95c, 95d includes an opening 97c, 97d with an axis that aligns with the axis of shaft 46b to allow shaft 46b to pass through the respective skirt 95c, 95d. As shown, openings 97c, 97d are circular. In the illustrated embodiment, each skirt 95c, 95d also includes an elongated opening 99c, 99d configured to engage with a projection on each respective housing 94c, 94d. Skirts 95c, 95d may help prevent contaminants from entering the interior of housing 94. In addition, when defrost gas is introduced into feeder assembly 20, the skirts 95c, 95d may also help direct defrost gas around the internal components of comminutor 28, such as rollers 44, 46, and generally keep the defrost gas from easily escaping through openings in housing 94. An embodiment of skirt 95c is shown in FIG. 10.

[0070] Housings 94a, 94b, 94c, 94d define roller cavity 51, which includes converging region 50, gap 48, diverging region 52 and the area between peripheral surfaces 44c, 46c of rollers 44, 46 and the interior surfaces of housings 94a, 94b, 94c, 94d. As can be seen in FIG. 13, defrost port 21 is in fluid communication with roller cavity 51 via defrost port outlet 21a. Accordingly, defrost gas can be introduced into roller cavity 51 via defrost port 21. The defrost gas that is introduced into roller cavity 51 may escape roller cavity 51 through small gaps between adjacent parts that define roller cavity 51. Some of these gaps may be present even when the defrost gas is not being introduced into roller cavity 51, while other gaps may be created by the force resulting from the defrost gas such that those gaps are only present when the defrost gas is introduced into roller cavity 51 and is being forced out of the gaps. By way of example only, defrost gas may escape roller cavity 51 through gaps between each skirt 95c, 95d and the respective portion of shaft 46b (and its associated couplings) passing through the opening 97c, 97d in each skirt 95c, 95d. Additional gaps may be present or created by defrost gas between the face of skirt 95c and the adjacent portions of housing 94a and between the face of skirt 95d and the adjacent portions of housing 94b.

[0071] Housings 94c and 94d are moveable relative to housings 94a and 94b so as to vary the width of gap 48. Housings 94a, 94b, 94c and 94d have corresponding supports 96a, 96b, 96c and 96d. Supports 96a, 96b rotatably support shafts 36b and 44b, and supports 96c, 96d rotatably support shaft 46b. Supports 96a, 96b, 96c and 96d may be made of any suitable material, such as aluminum. Housings 94a, 94b and supports 96a, 96b are depicted as not being moveable relative to feeding portion 30 and hopper 18.

[0072] Referring also to FIGS. 5, 6A, and 12, feeder assembly 20 includes gap adjustment mechanism 98 which is connected to supports 96c, 96d to move and dispose supports 96c, 96d (along with housings 94c, 94d) at and between a plurality of positions, including a first position at which gap 48 is at its minimum and a second position at which gap 48 is at its maximum. Gap adjustment mechanism 98 comprises shaft 100 which is rotatable about an axis, such as axis 100a, and external teeth or threads 100b disposed extending longitudinally as illustrated. Drive 28c is coupled to shaft 100 and may be controlled to rotate shaft 100. Gap adjustment mechanism 98 comprises member 102 with internal teeth or threads 102a disposed about axis 100a, which are shaped complementarily with external teeth or threads 100b, engaging therewith. Rotation of shaft 100 causes relative longitudinal motion between shaft 100 and member 102.

[0073] Member 102 is secured to plate 104 by a plurality of fasteners 106. Plate 104 is secured to support 96c by fastener 108a and to support 96d by fastener 108b.

[0074] Shaft 100 includes flange 110 which is captured between support 112 and retainer 114, allowing rotational motion about axis 100a with little or no axial motion. A plurality of rods 116 secure support 112 to supports 96a, 96b, with no movement therebetween. Rods 116 support plate 104 so that it can move axially along rods 116. Plate 104 includes a plurality of guides 104a which are disposed in complementarily shaped bores 118c, 118d. Since plate 104 is secured to supports 96c, 96d by fasteners 108a, 108b, there is no relative movement between guides 104a and supports 96c, 96d. Guides 104a are sized to allow rods 116 to slide axially therein.

[0075] Supports 96a, 96b include guides 120a, 120b respectively which are disposed in complementarily shaped bores (not seen) in supports 96c, 96d. These bores are sized to allow guides 120a, 120b to slide axially therein. Guides 120a, 120b support and guide supports 96c, 96d at and between the first and second positions of their travel. Rods 116 extend through guides 104a, bores 118c, 118d, and guides 120a, 120b, being fastened to supports 96a, 96b such that support 112 is supported and does not move relative to supports 96a, 96b.

[0076] Rotation of shaft 100 moves plate 104 along axis 100a and concomitantly moves supports 96c, 96d, housings 94c, 94d, and roller 46 relative to supports 96a, 96b, housings 94a, 94b, and roller 44, thereby varying the width of gap 48. In the illustrated embodiment, when supports 96c, 96d, housings 94c, 94d, and roller 46 are in the first position (i.e., when gap 48 is at its minimum), then defrost port outlet 21a is at least partially obstructed by housing 94c. Defrost port outlet 21a may still be capable of introducing defrost gas into roller cavity 51 when it is partially obstructed by housing 94c. Defrost port outlet 21a becomes more exposed (i.e., less obstructed) as supports 96c, 96d, housings 94c, 94d, and roller 46 move toward the second position (i.e., when gap 48 is at its maximum). In some embodiments, defrost port outlet 21a is completely exposed, thereby allowing defrost gas to freely flow into roller cavity 51 without any obstructions, when supports 96c, 96d, housings 94c, 94d, and roller 46 reach the second position, while in other embodiments, defrost port outlet 21a is completely exposed as supports 96c, 96d, housings 94c, 94d, and roller 46 transition toward, but prior to reaching, the second position.

[0077] Rollers 44 and 46 may comprise a plurality of rollers. As seen in FIG. 9, roller 44 may comprise sub-rollers A and B non-rotatably carried by shaft 44b and roller 46 may comprise sub-rollers C and D non-rotatably carried by shaft 46b. Each individual sub-roller A, B, C, D has a respective peripheral surface A, B, C and D.

[0078] Rollers 44, 46, regardless whether comprised of single rollers or a plurality of rollers, may include a plurality of bores 122 therethrough. If rollers 44, 46 comprise a plurality of rollers, bores 122 within each roller may be aligned axially. Bores 122 reduce the overall mass of rollers 44, 46. Such reduced mass reduces the time required for a temperature change in rollers 44, 46, such as a reduction in the time required for any ice built up on rollers 44, 46 during operation to melt during periods that particle blast apparatus 2 is not being operated. In another embodiment, air or other gas may be directed to flow through bores 122 to promote a faster temperature change.

[0079] For additional clarity, FIG. 11 provides a cross-sectional perspective view of feeder assembly 20.

[0080] Referring to FIGS. 12 and 13, supports 96c, 96d (not visible in FIGS. 12 and 13) are disposed at the second position at which gap 48 is at its maximum. Roller 46 is spaced apart from roller 44 at a maximum distance. Regardless of the position of roller 46 and the concomitant size of gap 48, roller 44 remains in the same position. Roller 44 defines first edge 48a of gap 48, which also remains in the same position regardless of the position of roller 46.

[0081] First edge 48a is always disposed at a location disposed intermediate axis 54a and wiping edge 56a. Wiping edge 56a defines a boundary of wiping region 56b. Generally wiping region 56b extends about the width of one pocket 60 when the leading edge of such pocket 60 is disposed at wiping edge 56a. Wiping region 56b is in alignment with first edge 48a. When supports 96c, 96d are disposed at the first location at which the size of gap 48 is at a minimum, the entire gap is aligned with wiping region 56b, such that the comminuted particles may fall or be directed into pockets 60 proximal wiping edge 56a.

[0082] FIG. 14 is similar to FIG. 13, depicting gap 48 at a size in between the maximum gap and minimum gap. Feeder assembly 20 is configured such that gap adjustment mechanism 98 may move and dispose supports 96c, 96d at and between a plurality of positions intermediate the first and second positions such that gap 48 may be set at a plurality of sizes intermediate the maximum gap and the minimum gap. In the depicted embodiment, the configuration of gap adjustment mechanism 98 essentially allows the size to be set at the maximum, minimum and any size intermediate thereof.

[0083] Peripheral surfaces 44c, 46c may be of any suitable configuration. In the embodiment depicted, peripheral surfaces 44c, 46c have a surface texture, which may be of any configuration. It is noted that for clarity, surface texture has been omitted from the figures except in FIGS. 6C, 15 and 16. FIGS. 6C, 15 and 16 illustrate rollers 44, 46 having a surface texture comprising a plurality of raised ridges 124. FIG. 15 illustrates rollers 44, 46 comprised of sub-rollers A, B, C and D, viewed from the top into converging region 50. Each peripheral surface A, B, C, D comprises a plurality of raised ridges 124 disposed at an angle relative to either edge. The angle may be any suitable angle, such as 30 relative to the axial direction. In the embodiment depicted, the angles of each peripheral surface A, B, C, D ridge are the same, although any suitable combination of angles may be used.

[0084] The surface texture in the depicted embodiment is configured to provide uniformity across the axial width of rollers 44, 46 of the comminuted particles discharged by comminutor 28 to feeding portion 30. Such uniformity is achieved in the depicted embodiment by the surface texture being configured to move particles entering comminutor 28 at converging region 50 toward the axial middle of rollers 44, 46. As seen in FIG. 15, the plurality of ridges 124 of roller 44 (sub-rollers A, B) and the plurality of ridges 124 of roller 46 (sub-rollers C, D) form a diamond pattern in converging region 50. At the interface between rollers A and B and rollers C and D, individual raised ridges 124 may or not precisely align.

[0085] When viewed from the bottom, the plurality of ridges 124 of roller 44 (sub-rollers A, B) and the plurality of ridges 124 of roller 46 (sub-rollers C, D) form an X pattern in the diverging region.

[0086] FIG. 17 shows a top view of metering rotor 36 through guide 22. Arrow 126 indicates the direction of rotation of metering rotor 36. Referring also to FIGS. 18-21, in the depicted embodiment, metering rotor 36 is configured to provide uniformity across the axial width of metering rotor 36 of the blast media particles discharged by metering rotor 36 at second region 40 to comminutor 28 and uniformity in the rate of discharge at second region 40. Such uniformity may be achieved in the depicted embodiment by the configuration of pockets 42. Metering rotor 36 may be made of any suitable material, such as UHMW or other polymers.

[0087] As seen in FIG. 18, metering rotor 36 comprises first end 36d and second end 36e which are spaced apart from each other along axis 36a. Pockets 42 extend from first end 36d to second end 36e. Pockets 42 when viewed radially toward axis 36a have a general V shape, also referred to herein as a chevron shape, with apex 42b pointed in the opposite direction of rotation. Pockets 42 when viewed axially have a general U shape. Any suitable axial shape may be used. Any suitable radial shape may be used, including pockets that extend straight from first end 36d to second end 36e.

[0088] In the depicted embodiment, pockets 42 are configured to promote movement of particles toward the axial center of pockets 42. As metering rotor 36 rotates in the direction of arrow 126, the axial inclination of the chevron shape may cause particles to move toward the axial center, resulting in more even distribution across the axial width of metering rotor 36.

[0089] FIGS. 19-21 illustrate the axial profile of pockets 42 at the corresponding locations indicated in FIG. 18. FIG. 20 illustrates the profile of pockets 42 at apex 42b, the midpoint. At apex 42b, the angle of pockets 42 transition to the opposite, mirror angle, without a sharp intersection. A radius may be formed at this intersection to create a non-sharp transition 42c.

[0090] FIG. 22 is a view of metering rotor 36 looking upstream from the bottom, through second region 40. Discharge edge 22b is illustrated extending generally axially relative to axis 36a. As can be seen, the V or chevron shape of pockets 42 results in the outermost portions 42d of pockets 42 passing discharge edge 22b first, prior to apex 42b. With this configuration, only a small section of one of the lands of peripheral surface 36c arrives at discharge edge 22b, providing less pulsing than if each land forming peripheral surface 36c were axially straight.

[0091] As mentioned above, metering element 36 is configured to control the flow rate of blast media for particle blast apparatus 2. By separating the flow rate control from the feeding rotor, pulsing at lower flow rates may be avoided. When the feeding rotor also controls the particle flow rate, to deliver lower flow rates, the rotational speed of the feeding rotor must be reduced. At lower speeds, due to the relative alignment of the pockets of the feeding rotor, pulsing occurs. Even with the pockets of the feeding rotor full, at lower rotational speeds of the feeding rotor, the time between the presentation of each opening for discharge is increased resulting in the pulsing.

[0092] In embodiments in which metering element 36 is present, feeding rotor 54 may be rotated at a constant, typically high, speed, independent of the feed rate. At a constant high speed, the time between the presentation of each opening for discharge is constant for all feed rates. At low feed rates with feeding rotor 54 rotating at a constant high speed, the percentage fill of each pocket will be smaller than at high feed rates, but pulsing will be reduced.

[0093] By separating the flow rate control from the feeding rotor, the feeding rotor may be operated closer to its optimal speed (based, for example, on component designs and characteristics, such as the motor profile, wear rate, etc.).

[0094] In the embodiment depicted, feeding rotor 54 may be operated at a constant rotation speed for all feed rates, such as 75 RPM to 80 RPM. In the embodiment depicted, comminutor 28 may be operated at a constant rotation speed for all feed rates, such as 1500 RPM for each roller 44, 46. In the embodiment depicted, metering rotor 36 may be operated at a rotation speed that varies so as to control the flow rate of particles.

[0095] For best operation, the flow of transport gas needs to be adequate and consistent providing the desired controllable flow and pressure. Although an outside source of gas, such as air, may be able to provide the desired flow and pressure in a controllable manner, outside sources are generally unreliable in this regard. Thus, for such consistency and control, prior art particle blast systems have included on board pressure regulation connected to an outside source of gas, such as air. Prior art particle blast systems have used a valve, such as a ball valve, as an on-off control of the incoming gas and regulated the pressure downstream thereof. Prior art pressure regulation has been accomplished by use of an inline pressure regulator disposed in the flow line with the desired pressure controlled by a fluid control signal, such as an air pressure signal from a pilot control pressure regulator. At higher transport gas flow rates, the inline pressure regulator produced high pressure losses. In the prior art, to make up for such pressure loss at higher flows, oversized inline pressure regulators or alternate non-regulated transport gas flow paths can be utilized, adding cost, complexity and undesirable increase in overall weight and size of design.

[0096] Referring to FIG. 23, pressure regulator assembly 32 of the embodiment depicted is shown. Pressure regulator 32 includes flow control valve, generally indicated at 202. Flow control valve 202 comprises actuator 204 and ball valve 206. Ball valve 206 includes inlet 208, which is connected to a source of transport gas, and outlet 210, which is connected through appropriate fitting 90 to inlet 86 and which may itself be considered a source of transport gas. In the embodiment depicted, T fitting 212 is connected to inlet 208. T fitting 212 includes inlet 212a which is connected to a source (not shown) of transport gas which, in the embodiment depicted, is not pressure regulated. T fitting includes outlet 212b which is connected to another T fitting 214, to which pressure sensor 216 is connected and senses the pressure within T fitting 214. Outlet 214a is configured to provide pressure and flow to other components of particle blast system 2.

[0097] Referring to FIG. 24, a cross-sectional top view of actuator 204 is illustrated, with ball valve 206 illustrated diagrammatically. Actuator 204 is configured to be coupled with a controlled member, in the embodiment depicted, ball 218 (see FIG. 27) to move the controlled member between and including a first controlled position and a second controlled position. In the embodiment depicted, when ball 218 is at the second controlled position, ball valve 206 is closed. Actuator 204 comprises body 220 which defines first internal chamber 222, which is generally cylindrical, but which can be any suitable shape. At one end, end cap 224 is connected to body 220, sealing first internal chamber 222. At the other end, body 226 is connected to body 220, sealing internal chamber 222. Body 220 may be of unitary construction or of assembled pieces. Body 220 and body 226 may be of unitary construction. Body 226 defines second internal chamber 228.

[0098] Piston 230 is disposed in first internal chamber 222, sealingly engaging sidewall 222a. Within first internal chamber 222, piston 230 forms chamber 232 on first side 230a, and chamber 234 on second side 230b. Piston 236 is disposed in first internal chamber 222, sealingly engaging sidewall 222a. Within first internal chamber 222, piston 236 forms chamber 238 on first side 236a, with second chamber 234 disposed on second side 236b.

[0099] Piston 230 is shaped complementarily to sidewall 222a and includes extension 230c with teeth 230d. Piston 236 is shaped complementarily to sidewall 222a and includes extension 236c with teeth 236d. Teeth 230d and teeth 236d engage pinion 240 which is rotatable about axis 240a, which in the embodiment depicted, is aligned with axis 218b of stem 218a. Pinion 240 is coupled, directly or indirectly to stem 218a which in turn is connected to ball 218. Rotation of pinion 240 causes concomitant rotation of stem 218a and ball 218. Pinion 240 may be rotated between and including a first position and a second position, which correspond to the first and second positions of ball 218when pinion 240 is at its first position, ball 218 is at its first position; when pinion 240 is at its second position, ball 218 is at its second position.

[0100] Pistons 230 and 236 also move between and including first and second positions, concomitantly due to their engagement with pinion 240. As pistons 230 and 236 move, they cause pinion 240 to rotate correspondingly. At their respective second positions, pistons 230 and 236 are at their minimum spaced apart distance relative to each other, causing pinion 240 and ball 218 to be at their respective second positions, making ball valve 206 closed. At their respective first positions, pistons 230 and 236 are at their maximum spaced apart distance relative to each other, causing pinion 240 and ball 218 to be at their respective first positions. In the embodiment depicted, ball valve 206 is a quarter turn valve and when ball 218 is at its first position, ball valve 206 is completely open. Although two pistons 230, 236 are illustrated, piston 236 could be omitted with piston 230 being appropriately sized.

[0101] Ball valve 206 regulates the pressure of the flow of transport gas into inlet 90. With reference to the pneumatic circuit schematic of FIG. 25, chambers 232 and 238 are in fluid communication with the flow passageway downstream of ball 218 so that the pressure within chambers 232 and 238 is the same as the actual static pressure in downstream passageway 242. In FIG. 24, this is diagrammatically illustrated by line 244, bypass valve 246 and line 248. Activation of bypass valve 246 allows the user to set ball valve 206 to completely open, bypassing/disabling the regulating function of ball valve 206. Lines 244, 248 may be of any suitable configuration.

[0102] Chamber 234 is placed in fluid communication with a pressure control signal, which either is or is proportional to the desired downstream pressure. As shown diagrammatically in FIG. 24, actuator 204 includes port 250 in fluid communication with chamber 234 which is configured to be connected to a pressure control signal by line 252. As illustrated, quick exhaust valve 254 may be interposed between port 250 and line 252, which may allow quick exhaust of the pressure within chamber 234 when desired, such as when ball valve 206 is being closed. The pressure of pressure control signal may be set by the operator. As seen in FIG. 25, pressure regulator 256 controls the pressure delivered to line 252 when control valve 258 is in the appropriate position. The position of control valve 258 is controlled by blast valve 260, which may be disposed in hand control 8. Actuation of blast valve 260 delivers regulated pressure flow from regulator 262 to control valve 258 causing it to move to the appropriate position for controlled pressure flow from pressure regulator 256 to flow to line 252. The pressure of the input to pressure regulator 256 may be unregulated as indicated in FIG. 25, it being noted that that input is regulated upstream thereof by regulator 264.

[0103] During operation, pressure within chamber 234, controlled by the pressure control signal delivered through line 252, will move pistons 230 and 236 outwardly, causing ball valve 206 to open, increasing the pressure in downstream flow passageway 242. As this pressure increases, the pressure within chamber 232 and 238 will increase and act on pistons 230 and 236 against the pressure in chamber 234, moving pistons 230 and 236 inwardly causing ball valve 206 to close, reducing the flow and the pressure in downstream flow passageway 242, which is the portion of the flow passageway downstream of ball 218, including the portion thereof within ball valve 206. Ball valve 206 will move to an equilibrium position at which the force on pistons 230 and 236 from chambers 232 and 238 equals the force on pistons 230 and 236 from chamber 234. Changes in pressure in chambers 232 and 238, such as due to changes in the upstream source pressure, or in chamber 234, such as due to a change by the operator, will result in ball valve 206 moving to a new equilibrium position.

[0104] As seen in FIG. 24, piston 266 is disposed in second internal chamber 228, sealingly engaging sidewall 228a. Within second internal chamber 228, piston 266 forms chamber 268 on first side 266a and chamber 290 (see FIG. 26) on second side 266b. Piston 266 is shaped complementarily to sidewall 228a and includes extension 266c which extends through bore 226a of end wall 226b, into chamber 232. A pair of spaced apart seals 270 disposed in annular grooves in bore 226a seal between chamber 232 and 228 against extension 266c. Vent 272 vents the area between seals 270 so that there will be a difference in pressure across the seals for all the seals to effectively be compression loaded in the seal grooves and prevent leakage.

[0105] End cap 274 is connected to body 226, and includes annular groove 276, which is shaped complementarily to and aligned with annular groove 278. Piston 266 is moveable between and including a first position at which the internal volume of chamber 228 is at its maximum and a second position at which the internal volume of chamber 228 is at its minimum, whereat extension 266c extends its maximum distance into chamber 232.

[0106] The ends of springs 280 and 282 are disposed in annular grooves 276 and 278 and configured to resiliently bias piston 266 toward the second position. In FIG. 24, with piston 266 in its first position, springs 280 and 282 are in their most compressed state, urging piston to the right to move to its second position. Although two springs are shown, there need be only at least one resilient member to resiliently urge piston 266 toward its second position.

[0107] To hold piston 266 in its first position, chamber 268 may be selectively pressurized with sufficient pressure to overcome the force exerted by springs 280 and 282. Body 226 includes port 284 in fluid communication with chamber 268. Fitting 286 is illustrated disposed in port 284, with line 288 in fluid communication with chamber 228 through fitting 286. Line 288 is connected to a source of pressurized fluid, such as air, so that chamber 268 can be pressurized. As seen in FIG. 25, pressure in line 288 is controlled by blast valve 260. Actuation of blast valve 260 delivers pressure to line 288 and ultimately chamber 268 such that piston 266 is held in its first position, overcoming the force exerted by springs 280 and 282. At this position, piston 230 has its full range of motion from its first position to its second position.

[0108] Referring to FIGS. 24-26, when blast valve 260 is released, pressure within chamber 268 is vented through blast valve 260 via line 288, allowing springs 280 and 282 to immediately move piston 266 from its first position (FIG. 24) to its second position (FIG. 26). As piston 266 moves from its first position to its second position, part of piston 266, extension 266c, engages piston 230 and moves piston 230 to its second position, at which ball valve 206 is closed. Concomitantly with the release of blast valve 260, pressure to line 252 is interrupted resulting in control valve 258 to interrupt the pressurization of chamber 234. With the drop in pressure of chamber 234, quick exhaust valve 254 allows venting of chamber 234 as piston 230 is moved by extension 266c.

[0109] FIG. 27 illustrates an exemplary ball valve used to explain a construction of ball valve 206, so thus FIG. 27 is correspondingly so numbered. Ball valve 206 comprises ball 218 having stem 218a which is rotatable about axis 218b. The transport gas flows through ball valve 206 in the direction indicated by arrow 294. Flow passageway 296 comprises upstream flow passageway 298, which is located upstream of ball 218, and downstream flow passageway 242, which is located downstream of ball 218. Ball 218 is controlled to move between and including a first position, at which ball valve 206 is completely open with ball passageway 218c aligned with flow passageway 296, and a second position, at which ball valve 206 is closed with ball 218 completely blocking flow passageway 296 as illustrated in FIG. 27.

[0110] FIG. 28 is pneumatic circuit schematic of an embodiment of a system configured to operate in a first operating mode, such as defrost mode 502, during which defrost gas is introduced into the interior of feeder assembly 20 and in a second operating mode, such as clog clearing mode 602, during which the feeder assembly 20 is operated in a certain manner so as to facilitate clearing of ice blockages or clogs present in the internal flow path of feeder assembly 20. The internal flow path refers to the path taken by blast media through an interior cavity of feeder assembly 20 as it flows from a source of blast media, such as hopper 18, through a feeding portion, such as feeding portion 30, and into a flow of transport gas to create an entrained flow. In the illustrated embodiment, blast media traveling along the internal flow path passes through metering portion 26, into and through comminutor 28 and feeding portion 30, and into a flow of transport gas to create an entrained flow. In the illustrated embodiment, defrost gas passes through filter/regulator 302 and adjustable regulator 304 before reaching defrost valve 306. As the defrost gas passes through filter/regulator 302, it is bled off via solenoid control to drain any possible accumulation of water within the filter bowl. The defrost gas then passes through defrost valve 306, which controls the flow of defrost gas to defrost port 21. Defrost valve 306 may comprise a standard solenoid valve. When defrost valve 306 is active (i.e., open), the defrost gas flows to defrost port 21 and is introduced into the interior of feeder assembly 20. When defrost valve 306 is inactive (i.e., closed), the defrost gas is not able to reach defrost port 21 and, as a result, is not introduced into the interior of feeder assembly 20. In other words, defrost port 21 is in fluid communication with defrost valve 306 such that when defrost valve 306 is active, defrost gas flows through defrost valve 306, to and through defrost port 21 and into roller cavity 51 of feeder assembly 20. Defrost valve 306 is thus configured to allow defrost gas to be selectively introduced through defrost port 21 into roller cavity 51. In some embodiments, after passing through defrost valve 306 but before reaching defrost port 21, the defrost gas passes through an airflow regulator 303 configured to control the airflow volume of the defrost gas reaching defrost port 21. In some embodiments airflow regulator 303 comprises a fixed orifice, while other suitable structures may be used in other embodiments. Airflow regulator 303 may be configured to limit the airflow volume of the defrost gas reaching defrost port 21 to any suitable amount, including, but not limited to, about 1 cubic foot per minute (CFM).

[0111] In one exemplary method of operation, particle blast apparatus 2 is configured to operate in a defrost mode 502. FIG. 29 depicts a flow chart showing defrost mode 502. In some embodiments, particle blast apparatus 2 may be operated in defrost mode 502 automatically (i.e., without requiring an operator to be operating particle blast apparatus 2). As shown, defrost mode 502 includes a defrost gas introduction step 504. During defrost gas introduction step 504, defrost valve 306 is activated in order to allow defrost gas to flow through defrost port 21 into roller cavity 51. In addition, during metering element inactive step 506, drive 26a, which provides rotary power to metering element 36, is inactive so that metering element 36 remains stationary in order to prevent blast media from being discharged by metering element 36 into second region 40. If drive 26a was active upon particle blast apparatus 2 entering defrost mode 502, then drive 26a is deactivated during metering element inactive step 506. If drive 26a was inactive upon particle blast system 2 entering defrost mode 502, then drive 26a remains inactive during metering element inactive step 506.

[0112] Further, defrost mode 502 also includes rollers active step 508, during which drive 28a is active in order to cause roller 44 to rotate and drive 28b is active in order to cause roller 46 to rotate. If drives 28a, 28b were active upon particle blast apparatus 2 entering defrost mode 502, then drives 26a, 26b remain active during rollers active step 508. If drives 28a, 28b were inactive upon particle blast apparatus 2 entering defrost mode 502, then drives 28a, 28b are activated during rollers active step 508. Rollers 44, 46 may initially be prevented from rotating, despite activation of their respective drive 28a, 28b during rollers active step 508, due to ice formed on rollers 44, 46 and/or a clog (e.g., a build up of ice) within roller cavity 51 adjacent rollers 44, 46. If rollers 44, 46 are initially stuck due to ice and/or a clog, the combination of the defrost gas being introduced into roller cavity 51 such that it flows around rollers 44, 46 and the activation of drives 28a, 28b will help free rollers 44, 46, thereby allowing them to rotate. The rotation of rollers 44, 46 will also facilitate breaking up ice on rollers 44, 46 or otherwise present in roller cavity 51. In some embodiments, during rollers active step 508, rollers 44, 46 are rotated at a speed that is within the power band of their respective drives 28a, 28b. As used herein, power band refers to the range of speeds that results in the drive producing an optimal amount of torque. By way of example only, in some embodiments, during rollers active step 508, rollers 44, 46 may be rotated at a speed of about 1700 revolutions per minute (RPM).

[0113] As shown in FIG. 29, defrost mode 502 includes feeding rotor inactive step 501, during which drive 30a, which provides rotary power to feeding rotor 54, is inactive so that feeding rotor 54 remains stationary, similar to drive 26a and metering element 36 in metering element inactive step 506 described above. If drive 30a was active upon particle blast apparatus 2 entering defrost mode 502, then during feeding rotor inactive step 510, drive 30a is deactivated. If drive 30a was inactive upon particle blast apparatus 2 entering defrost mode 502, then during feeding rotor inactive step 510, drive 30a remains inactive.

[0114] Steps 504, 506, 508, 510 may occur in any suitable order, including, but not limited to, the order shown in FIG. 29. In other embodiments, the order of steps 504, 506, 508, 510 may be rearranged. In some embodiments one or more of steps 504, 506, 508, 510 may occur simultaneously with each other. In some embodiments, steps 504, 506, 508, 510 may last as long as particle blast apparatus 2 remains in defrost mode 502, while in other embodiments, one or more of steps 504, 506, 508, 510 may stop while particle blast apparatus 2 is still in defrost mode 502. For example, defrost gas may continue to be introduced into roller cavity 51 (e.g., defrost valve 306 may remain active), metering element 36 may remain inactive, rollers 44, 46 may remain active, and feeding rotor 54 may remain inactive as long as particle blast apparatus 2 remains in defrost mode 502. In some embodiments of defrost mode 502, one or more of steps 506, 508, 510 may be omitted. In some embodiments of defrost mode 502, the duration of one or more of steps 504, 506, 508, 510 may be different from the duration of one or more of the other steps 504, 506, 508, 510.

[0115] During defrost mode 502, defrost gas flows around the components of feeder assembly 20 located within roller cavity 51, including rollers 44, 46, to help defrost those components and remove ice formed thereon. The defrost gas also flows into cavity 57 defined by guide 56 to help defrost the portion of feeding rotor 54 that is exposed to cavity 57. If drive 30a is activated while the defrost gas is flowing into cavity 57, thereby causing feeding rotor 54 to rotate, then the defrost gas will help defrost peripheral surface 54c of feeding rotor 54 as it rotates and different portions of peripheral surface 54c are exposed to the defrost gas. The defrost gas may also contact the portion of metering element 36 that is exposed to roller cavity 51, thereby helping defrost that as well. Water ice that is defrosted during defrost mode turns into water. The water can then either escape feeder assembly 20 through one or more of the small gaps between adjacent parts that define roller cavity 51 discussed above or collect in pockets 60 of feeding rotor 54 that are exposed to roller cavity 51. The next time drive 30a is activated and feeding rotor 54 rotates, the water that collected in pockets 60 is introduced into the flow of transport gas flowing along transport gas flow path 62 and expelled from discharge nozzle 10. Also, dry ice that is defrosted during defrost mode sublimates and can escape through one or more of the small gaps between adjacent parts that define roller cavity 51 discussed above or can combine with the transport gas flowing along transport gas flow path 62 the next time drive 30a is activated and feeding rotor 54 rotates.

[0116] In one exemplary method of operation, particle blast apparatus 2 is configured to operate in a clog clearing mode 602. FIG. 30 depicts a flow chart showing clog clearing mode 602. As shown, clog clearing mode 602 includes a defrost gas introduction step 604. During defrost gas introduction step 604, defrost valve 306 is activated in order to allow defrost gas to flow through defrost port 21 into roller cavity 51. In addition, during metering element inactive step 606, drive 26a, which provides rotary power to metering element 36, is inactive so that metering element 36 remains stationary in order to prevent blast media from being discharged by metering element 36 into second region 40. If drive 26a was active upon particle blast apparatus 2 entering clog clearing mode 602, then drive 26a is deactivated during metering element inactive step 606. If drive 26a was inactive upon particle blast system 2 entering clog clearing mode 602, then drive 26a remains inactive during metering element inactive step 606.

[0117] Further, clog clearing mode 602 also includes rollers active step 608, during which drive 28a is active in order to cause roller 44 to rotate and drive 28b is active in order to cause roller 46 to rotate. If drives 28a, 28b were active upon particle blast apparatus 2 entering clog clearing mode 602, then drives 26a, 26b remain active during rollers active step 608. If drives 28a, 28b were inactive upon particle blast apparatus 2 entering clog clearing mode 602, then drives 28a, 28b are activated during rollers active step 608. Rollers 44, 46 may initially be prevented from rotating, despite activation of their respective drive 28a, 28b during rollers active step 608, due to ice formed on rollers 44, 46 and/or a clog (e.g., a build up of ice) within roller cavity 51 adjacent rollers 44, 46. If rollers 44, 46 are initially stuck due to ice and/or a clog, the combination of the defrost gas being introduced into roller cavity 51 such that it flows around rollers 44, 46, the activation of drives 28a, 28b, and the adjustment of gap 48 (described below) will help free rollers 44, 46, thereby allowing them to rotate. The rotation of rollers 44, 46 will also facilitate breaking up any ice on rollers or in roller cavity 51. In some embodiments, during rollers active step 608, rollers 44, 46 are rotated at a speed that is within the power band of their respective drives 28a, 28b. By way of example only, in some embodiments, during rollers active step 608, rollers 44, 46 may be rotated at a speed of about 1700 RPM.

[0118] By including these steps, embodiments of clog clearing mode 602 are similar to defrost mode 502 described above. However, as shown, clog clearing mode 602 also includes additional steps. For example, in the illustrated embodiment, clog clearing mode 602 includes gap adjustment step 610, during which gap adjustment mechanism 98 is activated in order to repeatedly translate roller 46 and its associated components relative to roller 44 and its associated components, thereby adjusting the size of gap 48 between roller 44 and roller 46. During gap adjustment step 610, gap adjustment mechanism 98 may be used to translate roller 46 and its associated components between a first position where gap 48 is at its minimum and a second position where gap 48 is at its maximum or any points between those first and second positions. In other words, during gap adjustment step 610, gap adjustment mechanism 98 may be used to translate roller 46 and its associated components between a first position and a second position, where gap 48 increases as roller 46 and its associated components translate from the first position toward the second position and gap 48 decreases as roller 46 and its associated components translate from the second position toward the first position.

[0119] In addition, as shown, clog clearing mode 602 includes feeding rotor active step 612. During feeding rotor active step 612, drive 30a is active in order to cause feeding rotor 54 to rotate. If drive 30a was active upon particle blast apparatus 2 entering clog clearing mode 602, then drive 30a remains active during feeding rotor active step 612. If drive 30a was inactive upon particle blast apparatus 2 entering clog clearing mode 602, then drive 30a is activated during feeding rotor active step 612. Feeding rotor 54 may initially be prevented from rotating, despite activation of drive 30a, due to ice formed on feeding rotor 54 and/or a clog (e.g., a build up of ice) within guide 56 adjacent feeding rotor 54. If feeding rotor 54 is initially stuck due to ice and/or a clog, the combination of the defrost gas being introduced into roller cavity 51 such that it flows into cavity 57 of guide 56, the activation of drive 30a, the rotation of rollers 44, 46, and the adjustment of gap 48 will help free feeding rotor 54, thereby allowing it to rotate. The rotation of feeding rotor 54 will also facilitate breaking up any ice on feeding rotor 54. In some embodiments, feeding rotor 54 is rotated at any speed within the operating specifications of drive 30a. By way of example only, in some embodiments, during feeding rotor active step 612, feeding rotor 54 may be rotated at a speed of about 30 RPM, while in other embodiments, during the feeding rotor active step 612, feeding rotor 54 may be rotated at a speed of about 85 RPM.

[0120] In the illustrated embodiment, clog clearing mode 602 also includes transport gas flow step 614. During transport gas flow step 614, transport gas flows into particle blast apparatus 2 along transport gas flow path 62. In some embodiments, during transport gas flow step 614, ball valve 206 is activated (i.e., opened) in order to allow transport gas to flow into particle blast apparatus 2. Allowing transport gas to flow along transport gas flow path 62, which includes pockets 60 in feeding rotor 54, will help expel any water or ice particles collected in pockets 60 of feeding rotor 60. Having transport gas flowing around the portion of feeding rotor 54 exposed to transport gas flow path 62 will also help defrost feeding rotor 54 due to the temperature of transport gas. For example, the temperature of the transport gas may be about zero degrees Celsius or warmer, and, in some instances, the temperature of the transport gas may be the same as the ambient air temperature around particle blast apparatus 2. In some embodiments, the transport gas may be between about 26 degrees Celsius and 150 degrees Celsius. In some embodiments, particle blast apparatus 2 is configured such that ball valve 206 is activated by an operator. In those embodiments, particle blast apparatus 2 may require an operator be present at particle blast apparatus 2 (or actively controlling its operation) in order to operate particle blast apparatus 2 in clog clearing mode 602.

[0121] Steps 604, 606, 608, 610, 612, 614 may occur in any suitable order, including, but not limited to, the order shown in FIG. 30. In other embodiments, the order of steps 604, 606, 608, 610, 612, 614 may be rearranged. In some embodiments one or more of steps 604, 606, 608, 610, 612, 614 may occur simultaneously with each other. By way of example only, in one embodiment, defrost gas introduction step 604 may occur first and the other steps 606, 608, 610, 612, 614 may occur simultaneously with each other. In some embodiments, steps 604, 606, 608, 610, 612, 614 may last as long as particle blast apparatus 2 remains in clog clearing mode 602, while in other embodiments, one or more of steps 604, 606, 608, 610, 612, 614 may stop while particle blast apparatus 2 is still in clog clearing mode 602. For example, defrost gas may continue to be introduced into roller cavity 51 (e.g., defrost valve 306 may remain active), metering element 36 may remain inactive, rollers 44, 46 may remain active, gap adjustment mechanism 98 may remain active adjusting the size of gap 48, feeding rotor 54 may remain active, and transport gas may continue to flow along transport gas flow path 62 (e.g., ball valve 206 may be active) as long as particle blast apparatus 2 remains in clog clearing mode 602. In some embodiments of defrost mode 602, one or more of steps 604, 606, 608, 610, 612, 614 may be omitted. In still other embodiments of defrost mode 602, the duration of one or more of steps 604, 606, 608, 610, 612, 614 may be different from the duration of one or more of the other steps 604, 606, 608, 610, 612, 614. For example, in one embodiment of clog clearing mode 602, defrost gas introduction step 604 and metering element inactive step 606 may begin upon entering clog clearing mode 602 and continue for a predetermined initial duration period, including, but not limited to, about 5 minutes, and steps 608, 610, 612, and 614 may begin in response to a user depressing a trigger on hand control 8 and continue as long as the trigger remains depressed. In such an embodiment, steps 608, 610, 612, and 614 may stop when the trigger is released and steps 604 and 606 may continue if the initial duration period has not elapsed.

[0122] In some embodiments, particle blast apparatus 2 is configured to operate in both defrost mode 502 and clog clearing mode 602 and allow a user to select which mode to operate in. In addition, particle blast apparatus 2 may be programmed to operate in defrost mode 502 or clog clearing mode 602 for a predetermined amount of time, until an operator provides instructions to stop operating in the selected mode, such as by pulling a trigger on hand control 8 or selecting a button on a control panel, or until the earlier of the expiration of a predetermined amount of time or until an operator provides instructions to stop operating in the selected mode. By way of example only, in one embodiment, particle blast apparatus 2 may be programmed to operate in defrost mode 502 for between about two minutes and twenty minutes, preferably up to about five minutes. In some embodiments, the duration for defrost mode 502 may be increased by a user to any suitable amount of time.

EXEMPLARY COMBINATIONS

[0123] The following examples relate to various non-exhaustive ways in which the teachings herein may be combined or applied. The following examples are not intended to restrict the coverage of any claims that may be presented at any time in this application or in subsequent filings of this application. No disclaimer is intended. The following examples are being provided for nothing more than merely illustrative purposes. It is contemplated that the various teachings herein may be arranged and applied in numerous other ways. It is also contemplated that some variations may omit certain features referred to in the below examples. Therefore, none of the aspects or features referred to below should be deemed critical unless otherwise explicitly indicated as such at a later date by the inventor or by a successor in interest to the inventor. If any claims are presented in this application or in subsequent filings related to this application that include additional features beyond those referred to below, those additional features shall not be presumed to have been added for any reason relating to patentability.

Example 1

[0124] A system comprising: a source of defrost gas and a particle blast apparatus, wherein the particle blast apparatus comprises a feeder assembly configured to transport blast media from a source of blast media into a flow of transport gas, the blast media comprising a plurality of particles, the feeder assembly comprising a metering portion and a comminutor, wherein the comminutor is housed within a roller cavity defined by a housing, wherein the housing comprises a defrost port in fluid communication with the source of defrost gas, such that defrost gas is introduced into the roller cavity through the defrost port.

Example 2

[0125] The system of example 1, wherein the feeder assembly further comprises a first skirt engaged with a first side of the housing.

Example 3

[0126] The system of example 2, wherein the feeder assembly further comprises a second skirt engaged with a second side of the housing, wherein the second side of the housing is opposite the first side of the housing.

Example 4

[0127] The system of any of the preceding examples, wherein a temperature of the defrost gas is greater than or equal to minus seventy eight degrees Celsius.

Example 5

[0128] The system of example 4, wherein the temperature of the defrost gas is greater than or equal to zero degrees Celsius.

Example 6

[0129] The system of any of the preceding examples, wherein the defrost gas is air.

Example 7

[0130] The system of any of the preceding examples, wherein the system further comprises a source of transport gas in fluid communication with the particle blast apparatus, wherein the source of transport gas and the source of defrost gas are the same source.

Example 8

[0131] The system of any of the preceding examples, wherein the defrost gas is introduced into the roller cavity through the defrost port for a predetermined amount of time.

Example 9

[0132] A method comprising: providing a particle blast apparatus, wherein the particle blast apparatus comprises a feeder assembly configured to transport blast media from a source of blast media into a flow of transport gas, the blast media comprising a plurality of particles, the feeder assembly comprising a metering portion and a comminutor, wherein the comminutor is housed within a roller cavity defined by a housing; and introducing a flow of defrost gas into the roller cavity.

Example 10

[0133] The method of example 9, wherein the particle blast apparatus further comprises a defrost valve, wherein the housing comprises a defrost port in fluid communication with the defrost valve and the roller cavity, wherein the defrost gas introducing step further comprises activating the defrost valve.

Example 11

[0134] The method of any of example 9 and 10, wherein the metering portion comprises a metering element, wherein the method further comprises causing the metering element to remain rotationally stationary.

Example 12

[0135] The method of example 11 comprising causing the metering element to remain rotationally stationary while introducing the flow of defrost gas into the roller cavity.

Example 13

[0136] The method of any of examples 9-12, wherein the comminutor comprises a first roller and a second roller, wherein the method further comprises rotating at least one of the first roller and the second roller.

Example 14

[0137] The method of example 13, wherein the comminutor comprises a first roller drive engaged with the first roller to provide rotary power to the first roller, and a second roller drive engaged with the second roller to provide rotary power to the second roller, wherein the roller rotating step further comprises activating at least one of the first roller drive and the second roller drive.

Example 15

[0138] The method of any of examples 13 and 14 comprising rotating at least one of the first roller and the second roller while introducing the flow of defrost gas into the roller cavity.

Example 16

[0139] The method of any of examples 13-15, wherein the roller rotating step comprises rotating both the first roller and the second roller.

Example 17

[0140] The method of example 16, wherein the roller rotating step comprises rotating both first roller and the second roller while introducing the flow of defrost gas into the roller cavity.

Example 18

[0141] The method of any of examples 9-17, wherein the feeder assembly further comprises a feeding portion comprising a feeding rotor, wherein the method further comprises causing the feeding rotor to remain rotationally stationary

Example 19

[0142] The method of example 18 comprising causing the feeding rotor to remain rotationally stationary while introducing the flow of defrost gas into the roller cavity.

Example 20

[0143] The method of any of examples 9-17, wherein the comminutor further comprises a gap being defined by an outer surface of the first roller and an outer surface of the second roller; wherein the gap comprises a size, and the feeder assembly further comprises a support which carries the second roller, the support is movable among a plurality of positions intermediate and including a first position at which the gap is a minimum gap size and a second position at which the gap is the maximum gap size, wherein the method further comprises adjusting the size of the gap.

Example 21

[0144] The method of example 20 comprising adjusting the size of the gap while introducing the flow of defrost gas into the roller cavity.

Example 22

[0145] The method of any of examples 9-17 and 20-21, wherein the feeder assembly further comprises a feeding portion comprising a feeding rotor, wherein the method further comprises rotating the feeding rotor.

Example 23

[0146] The method of example 22, wherein the feeding portion further comprises a feeding rotor drive engaged with the feeding rotor to provide rotary power to the feeding rotor, wherein the feeding rotor rotating step comprises activating the feeding rotor drive.

Example 24

[0147] The method of any of examples 22 and 23 comprising rotating the feeding rotor while introducing the flow of defrost gas into the roller cavity.

Example 25

[0148] The method of any of examples 9-17 and 20-24 further comprising introducing the flow of transport gas into the particle blast apparatus.

Example 26

[0149] The method of example 25 comprising introducing the flow of transport gas into the particle blast apparatus while introducing the flow of defrost gas into the roller cavity.

Example 27

[0150] A method comprising: providing a particle blast apparatus comprising a feeder assembly configured to transport blast media from a source of blast media into a flow of transport gas, the blast media comprising a plurality of particles, the feeder assembly comprising a metering portion and a comminutor, wherein the metering portion comprises a metering element, wherein the comminutor comprises a first roller and a second roller; causing the metering element to remain rotationally stationary; and rotating at least one of the first roller and the second roller.

Example 28

[0151] The method of example 27, wherein the step of causing the metering element to remain rotationally stationary and the roller rotation step occur simultaneously with each other.

Example 29

[0152] The method of any of examples 27 and 28, wherein the comminutor further comprises a first roller drive engaged with the first roller to provide rotary power to the first roller and a second roller drive engaged with the second roller to provide rotary power to the second roller, wherein the roller rotating step further comprises activating at least one of the first roller drive and the second roller drive.

Example 30

[0153] The method of any of examples 27-29, wherein the roller rotating step comprises rotating both the first roller and the second roller.

Example 31

[0154] The method of any of examples 27-30, wherein the comminutor is housed within a roller cavity defined by a housing; and the method further comprises introducing a flow of defrost gas into the roller cavity.

Example 32

[0155] The method of example 31, wherein the particle blast apparatus further comprises a defrost valve, wherein the housing comprises a defrost port in fluid communication with the defrost valve and the roller cavity, wherein the defrost gas introducing step further comprises activating the defrost valve.

Example 33

[0156] The method of any of examples 31 and 32, wherein the defrost gas introducing step occurs simultaneously with the metering element remaining rotationally stationary step and the roller rotation step.

Example 34

[0157] The method of any of examples 27-33, wherein the comminutor further comprises a gap being defined by an outer surface of the first roller and an outer surface of the second roller; wherein the gap comprises a size, and the feeder assembly further comprises a support which carries the second roller, the support configured to be disposed at a plurality of positions intermediate and including a first position at which the gap is a minimum gap size and a second position at which the gap is the maximum gap size, wherein the method further comprises adjusting the size of the gap.

Example 35

[0158] The method of example 34 wherein the gap adjustment step occurs simultaneously with the metering element remaining rotationally stationary step and the roller rotation step.

Example 36

[0159] The method of any of examples 27-35, wherein the feeder assembly further comprises a feeding portion comprising a feeding rotor, wherein the method further comprises rotating the feeding rotor.

Example 37

[0160] The method of example 36, wherein the feeding portion further comprises a feeding rotor drive engaged with the feeding rotor to provide rotary power to the feeding rotor, wherein the feeding rotor rotating step comprises activating the feeding rotor drive.

Example 38

[0161] The method of any of examples 36 and 37 wherein the feeding rotor rotation step occurs simultaneously with the metering element remaining rotationally stationary step and the roller rotation step.

Example 39

[0162] The method of any of examples 27-38 further comprising introducing the flow of transport gas into the particle blast apparatus.

Example 40

[0163] The method of example 39 wherein the transport gas flow introduction step occurs simultaneously with the metering element remaining rotationally stationary step and the roller rotation step.

Example 41

[0164] A method comprising: providing a particle blast apparatus comprising a feeder assembly configured to transport blast media from a source of blast media into a flow of transport gas, the blast media comprising a plurality of particles, the feeder assembly comprising a comminutor, wherein the comminutor comprises a gap being defined by an outer surface of a first roller and an outer surface of a second roller; wherein the gap comprises a size, and the feeder assembly further comprises a support which carries the second roller, the support configured to be disposed at a plurality of positions intermediate and including a first position at which the gap is a minimum gap size and a second position at which the gap is the maximum gap size; and adjusting the size of the gap.

Example 42

[0165] The method of example 41, wherein the feeder assembly further comprises a metering portion comprising a metering element, wherein the method further comprises causing the metering element to remain rotationally stationary.

Example 43

[0166] The method of example 42, wherein the step of causing the metering element to remain stationary occurs simultaneously with the gap adjustment step.

Example 44

[0167] The method of any of examples 41-43 further comprising rotating at least one of the first roller and the second roller.

Example 45

[0168] The method of example 44, wherein the comminutor further comprises a first roller drive engaged with the first roller to provide rotary power to the first roller and a second roller drive engaged with the second roller to provide rotary power to the second roller, wherein the roller rotating step further comprises activating at least one of the first roller drive and the second roller drive.

Example 46

[0169] The method of any of examples 44 and 45, wherein the roller rotating step comprises rotating both the first roller and the second roller.

Example 47

[0170] The method of any of examples 44-46, wherein the roller rotation step occurs simultaneously with the gap adjustment step.

Example 48

[0171] The method of any of examples 41-47, wherein the comminutor is housed within a roller cavity defined by a housing; and the method further comprises introducing a flow of defrost gas into the roller cavity.

Example 49

[0172] The method of example 48, wherein the particle blast apparatus further comprises a defrost valve, wherein the housing comprises a defrost port in fluid communication with the defrost valve and the roller cavity, wherein the defrost gas introducing step further comprises activating the defrost valve.

Example 50

[0173] The method of any of examples 48 and 49, wherein the defrost gas introducing step occurs simultaneously with the gap adjustment step.

Example 51

[0174] The method of any of examples 41-50, wherein the feeder assembly further comprises a feeding portion comprising a feeding rotor, wherein the method further comprises rotating the feeding rotor.

Example 52

[0175] The method of example 51, wherein the feeding portion further comprises a feeding rotor drive engaged with the feeding rotor to provide rotary power to the feeding rotor, wherein the feeding rotor rotating step comprises activating the feeding rotor drive.

Example 53

[0176] The method of any of examples 51 and 52 wherein the feeding rotor rotation step occurs simultaneously with the gap adjustment step.

Example 54

[0177] The method of any of examples 41-53 further comprising introducing the flow of transport gas into the particle blast apparatus.

Example 55

[0178] The method of example 54 wherein the transport gas flow introduction step occurs simultaneously with the gap adjustment step.

Example 56

[0179] A particle blast apparatus comprising: an interior cavity; a defrost port in fluid communication with the interior cavity, such that defrost gas is selectively introduced into the interior cavity through the defrost port; and an internal flow path extending from a source of blast media to a transport gas flow path, wherein at least a portion of the internal flow path extends through the interior cavity.

Example 57

[0180] The particle blast apparatus of example 56 further comprising a defrost valve in fluid communication with the defrost port.

Example 58

[0181] The particle blast apparatus of example 56 or 57 further comprising a comminutor, wherein the comminutor is disposed within the interior cavity.

Example 59

[0182] The particle blast apparatus of example 58 further comprising a metering element, wherein the metering rotor is disposed upstream of the comminutor.

Example 60

[0183] The particle blast apparatus of any of examples 56-59, wherein the interior cavity is disposed within a housing, wherein the particle blast apparatus further comprises a first skirt engaged with a first side of the housing and a second skirt engaged with a second side of the housing, wherein the second side of the housing is opposite the first side of the housing.

Example 61

[0184] The particle blast apparatus of any of examples 56-59, wherein the interior cavity is disposed within a housing.

Example 62

[0185] The particle blast apparatus of example 61, further comprising a first skirt engaged with a first side of the housing.

Example 63

[0186] The particle blast apparatus of any of examples 56-62, wherein the source of blast media is a source of cryogenic blast media.

Example 64

[0187] A method comprising: providing a particle blast apparatus, wherein the particle blast apparatus comprises an interior cavity, and an internal flow path extending from a source of blast media to a transport gas flow path, wherein at least a portion of the internal flow path extends through the interior cavity; and introducing defrost gas into the interior cavity.

Example 65

[0188] The method of example 64, wherein the particle blast apparatus further comprises a defrost valve and a defrost port, wherein the defrost port is in fluid communication with the defrost valve and the interior cavity, wherein the defrost gas introducing step further comprises activating the defrost valve.

Example 66

[0189] The method of either example 64 or 65, wherein the particle blast apparatus further comprises a metering element disposed upstream of the transport gas flow path, wherein the method further comprises causing the metering element to remain rotationally stationary.

Example 67

[0190] The method of any of examples 64-66, wherein the particle blast apparatus further comprises a comminutor disposed within the interior cavity, wherein the comminutor comprises a first roller and a second roller, wherein the method further comprises rotating at least one of the first roller and the second roller.

Example 68

[0191] The method of any of examples 64-67, wherein the particle blast apparatus further comprises a feeding rotor disposed upstream of the transport gas flow path, wherein the method further comprises causing the feeding rotor to remain rotationally stationary.

Example 69

[0192] The method of either of example 64 or 65, wherein the particle blast apparatus further comprises a comminutor disposed within the interior cavity and a feeding rotor disposed between the comminutor and the transport gas flow path, wherein the comminutor comprises a first roller and a second roller, wherein the method further comprises rotating at least one of the first roller and the second roller while introducing defrost gas into the interior cavity and causing the feeding rotor to remain rotationally stationary while introducing defrost gas into the interior cavity.

Example 70

[0193] The method of any of examples 64-69 further comprising stopping blast media from entering the interior cavity while introducing defrost gas into the interior cavity.

Example 71

[0194] The method of any of examples 64-70 further comprising introducing a flow of transport gas along the transport gas flow path while introducing defrost gas into the interior cavity.

Example 72

[0195] The method of example 64, wherein the particle blast apparatus further comprises a comminutor disposed within the interior cavity, wherein the comminutor comprises a first roller and a second roller; a metering element disposed upstream of the comminutor; and a feeding rotor disposed intermediate the comminutor and the transport gas flow path, wherein the method further comprises causing the metering element to remain rotationally stationary while rotating at least one of the first roller and the second roller, causing the feeding rotor to remain rotationally stationary, introducing a flow of transport gas along the transport gas flow path, and introducing defrost gas into the interior cavity.

Example 73

[0196] A method comprising: providing a particle blast apparatus, wherein the particle blast apparatus comprises an interior cavity, a comminutor, wherein the comminutor is disposed within the interior cavity, wherein the comminutor comprises a first roller, a second roller, and a gap defined by an outer surface of the first roller and an outer surface of the second roller, wherein the gap has a size, wherein the second roller is movable relative to the first roller between a first position at which the gap size is a first gap size and a second position at which the gap size is a second gap size, wherein the second gap size is greater than the first gap size; introducing defrost gas into the interior cavity; rotating at least one of the first roller and the second roller; and adjusting the size of the gap.

Example 74

[0197] The method of example 73, wherein introducing defrost gas into the interior cavity occurs while rotating at least one of the first roller and the second roller and adjusting the size of the gap.

Example 75

[0198] The method of example 74 further comprising stopping blast media from entering the interior cavity while introducing defrost gas into the interior cavity, rotating at least one of the first roller and the second roller, and adjusting the size of the gap.

Example 76

[0199] The method of example 74 further comprising stopping blast media from entering the interior cavity while conducting at least one of the following steps: introducing defrost gas into the interior cavity, rotating at least one of the first roller and the second roller, and adjusting the size of the gap.

Example 77

[0200] The method of either example 75 or 76, wherein the particle blast apparatus further comprises a feeding rotor disposed downstream of the comminutor, wherein the method further comprises rotating the feeding rotor while stopping blast media from entering the interior cavity, introducing defrost gas into the interior cavity, rotating at least one of the first roller and the second roller, and adjusting the size of the gap.

Example 77

[0201] The method of either example 76 or 77, further comprising introducing a flow of transport gas into the particle blast apparatus while rotating the feeding rotor, stopping blast media from entering the interior cavity, introducing defrost gas into the interior cavity, rotating at least one of the first roller and the second roller, and adjusting the size of the gap.

[0202] The foregoing description of one or more embodiments of the innovation has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiment was chosen and described in order to best illustrate the principles of the innovation and its practical application to thereby enable one of ordinary skill in the art to best utilize the innovation in various embodiments and with various modifications as are suited to the particular use contemplated. Although only a limited number of embodiments of the innovation is explained in detail, it is to be understood that the innovation is not limited in its scope to the details of construction and arrangement of components set forth in the preceding description or illustrated in the drawings. The innovation is capable of other embodiments and of being practiced or carried out in various ways. Also specific terminology was used for the sake of clarity. It is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose.