Method and apparatus for minimizing ice accumulation in and at the exit of a blast nozzle

Abstract

The method and apparatus prevents ice from obstructing the flow of cryogenic particles entrained in the flow exiting the blast nozzle during continuous operation of the particle blast system. A fluid stream having an appropriate temperature, moisture content, and flow rate flows through an annular passage surrounding the nozzle.

Description

Technical Field

[0001] The present invention relates to a method and apparatus for minimizing or eliminating ice accumulation on the inner surface of an inner nozzle and adjacent to a nozzle outlet.

Background Art

[0002] Particle blast systems that utilize various types of blast media are well known. Systems for entraining cryogenic particles, such as solid carbon dioxide particles, in a transport fluid and for directing the entrained particles towards an object / target are well known, as are the various components associated therewith, such as nozzles, and are shown in U.S. Pat. Nos. 4,744,181; 4,843,770; 5,018,667; 5,050,805; 5,071,289; 5,188,151; 5,249,426; 5,288,028; 5,301,509; 5,473,903; 5,520,572; 6,024,304; 6,042,458; 6,346,035; 6,524,172; 6,695,679; 6,695,685; 6,726,549; 6,739,529; 6,824,450; 7,112,120; 7,950,984; 8,187,057; 8,277,288; 8,869,551; 9,095,956; 9,592,586; 9,931,639; 10,315,862; and 10,737,890, all of which are hereby incorporated by reference in their entirety.

[0003] Furthermore, U.S. Patent Application No. 11 / 853,194, published on September 11, 2007, for Particle Blast System With Synchronized Feeder and Particle Generator; Provisional Patent Application No. 61 / 589,551, filed on January 23, 2012, for Method And Apparatus For Sizing Carbon Dioxide Particles; Provisional Patent Application No. 61 / 592,313, filed on January 30, 2012, for Method And Apparatus For Dispensing Carbon Dioxide Particles; and U.S. Patent Application No. 13 / 475,454, filed on May 18, 2012, for Method And Apparatus For Forming Carbon Dioxide Pellets; Apparatus Including At Least An Impeller Or Diverter And For Dispensing Carbon Dioxide Particles And Method Of U.S. Patent Application No. 14 / 062,118, published on October 24, 2013, for Use; U.S. Patent Application No. 14 / 516,125, published on October 16, 2014, for Method And Apparatus For Forming Solid Carbon Dioxide; U.S. Patent Application No. 15 / 297,967, published on October 19, 2016, for Blast Media Comminutor; U.S. Patent Application No. 15 / 961,321, filed on April 24, 2018, for Particle Blast Apparatus; U.S. Patent Application No. 16 / 999,633, filed on August 21, 2020, for Particle Blast Apparatus and Method;U.S. Patent Application No. 17 / 139,292, filed December 31, 2020, for Method and Apparatus for Enhanced Blast Stream, Particle Blast Apparatus and Method; and U.S. Provisional Patent Application No. 63 / 185,467, filed May 7, 2021, for Method and Apparatus For Forming Solid Carbon Dioxide, are both incorporated herein by reference in their entirety.

[0004] To the extent that the material incorporated by reference conflicts with the disclosure of this patent, the disclosure of this patent shall prevail.

[0005] While this patent specifically refers to carbon dioxide in describing the innovation, this innovation is not limited to carbon dioxide and can rather be applied to any suitable cryogenic material. Therefore, unless explicitly stated otherwise, references to carbon dioxide in this specification and in the claims should be interpreted as including any suitable cryogenic material, rather than being limited to carbon dioxide.

[0006] As is well known, cryogenic particle blasting systems, such as carbon dioxide particle blasting systems, discharge a stream of cryogenic particles, such as carbon dioxide particles, entrained in a transport gas, from a blast nozzle. The size of the particles used may depend on the specific application in which the blasting system is used. U.S. Patent No. 5,520,572 describes a particle blasting apparatus that entrains small particles in a transport gas stream. The entrained stream of particles flows through a delivery hose to the blast nozzle for its final use, such as being directed at a workpiece or other target. The outgoing stream may be subsonic, supersonic, or supersonic.

[0007] Under certain flow conditions and specific ambient conditions, continuous operation of several blast nozzles can cause water ice to accumulate on the outside of the nozzles. This accumulation can grow over time during continuous use of the system and eventually obstruct or block the flow exiting the blast nozzle. The water ice formed on the outside of the nozzle at the exit can break off and be incorporated into the outgoing flow of entrained particles, potentially damaging the target or workpiece. [Overview of the project] [Means for solving the problem]

[0008] This innovation can reduce, minimize, and eliminate ice buildup on the inner surface and outlet of blast nozzles, thereby reducing or completely eliminating obstruction and blockage. According to this innovation, at least a portion of the length of the blast nozzle is surrounded by a fluid stream warm enough to reduce or eliminate ice buildup.

[0009] According to one aspect of this innovation, the fluid stream may be annular.

[0010] According to another aspect of this innovation, the fluid stream can flow through an annular passage defined by a structure surrounding the outside of the blast nozzle.

[0011] In a further embodiment of this innovation, the exit of the annular passage may be located near the exit of the blast nozzle.

[0012] The attached drawings illustrate embodiments that help illustrate the principles of this innovation. [Brief explanation of the drawing]

[0013] [Figure 1] An embodiment of a particle blast system configured according to one or more teachings of this innovation is schematically shown. [Figure 2]This is an exploded view of one embodiment of a shrouded blast nozzle assembly configured according to one or more teachings of this innovation. [Figure 3] Figure 2 is a cross-sectional view of a blast nozzle assembly with a shroud, drawn in a plane passing through the central axis. [Figure 4] Figure 2 is a magnified view of the discharge end of the shrouded blast nozzle assembly. [Figure 5] This is an end view of nozzle 20. [Figure 6] Figure 2 is a cross-sectional view of the blast nozzle assembly shroud, drawn in a plane passing through the central axis. [Figure 7] This is a cross-sectional view of an alternative embodiment of a shrouded blast nozzle assembly configured according to one or more teachings of this innovation, drawn in a plane passing through the central axis. [Modes for carrying out the invention]

[0014] In the following description, similar reference numerals indicate similar or corresponding parts throughout several figures. Furthermore, it should be understood that terms such as front, back, inside, and outside are for convenience only and should not be interpreted as restrictive. The terminology used in this patent is not intended to limit the devices or parts thereof described herein to the extent that they may be mounted or utilized in other orientations. Referring more closely to the drawings, one or more embodiments configured in accordance with the teachings of this innovation are described.

[0015] Any patents, publications, or other disclosures incorporated herein by reference, in whole or in part, should be understood to be incorporated herein only to the extent that the incorporated material does not conflict with existing definitions, statements, or other disclosures contained herein. To the extent necessary, the disclosures expressly contained herein supersede any conflicting material incorporated herein by reference.

[0016] Referring to Figure 1, a particle blast system 2 is schematically shown, which in the embodiment depicted comprises a source 4 of cryogenic particles encompassed in a transport gas flow (also referred to herein as the encompassed cryogenic particle source 4), an encompassed flow delivery hose 6, a hand control 8, a discharge or blast nozzle assembly 10, and a shroud fluid hose 12. A fluid source 14 is connected to the shroud fluid delivery hose 12 and configured to supply shroud fluid to the discharge assembly 10. The fluid source 14 is shown as including a pressurized fluid source 16, such as an air compressor 16, and an aftercooler 26. The encompassed cryogenic particle source 4 may be directly connected to the pressurized fluid source 16, as shown, which serves as a source of transport gas for the encompassed cryogenic particle source 4, or it may be connected to the aftercooler 26 for that transport gas source.

[0017] The encompassing cryogenic particle source 4 may be any configuration that encompasses cryogenic particles into the transport gas flow. The encompassing cryogenic particle source 4 is schematically shown as including a hopper 4a, which functions as a cryogenic particle source for the supply section 4b. The supply section 4b may be any suitable configuration, including a supply rotor (not shown) that introduces particles into the transport gas flow. In the embodiments depicted, the cryogenic particles may be carbon dioxide particles, and the innovation will be described below in relation to the use of carbon dioxide particles as cryogenic particles, however such references will not limit the innovation to the use of carbon dioxide particles. Thus, the cryogenic particle source 4 encompassing into the transport gas flow will also be referred to herein as the encompassing carbon dioxide particle source 4, and the innovation will not be limited to any particular type of cryogenic particle.

[0018] The aftercooler 26 reduces the amount of vapor in the pressurized fluid supplied by the compressor 16. In the embodiment depicted, the pressurized fluid is air, and the aftercooler 26 reduces the amount of water vapor in it. A separator may be combined with the aftercooler 26. Alternatively, a fluid heater may be used as part of or in place of the aftercooler 26 to more reliably ensure that the temperature of the fluid stream entering the discharge assembly 10 through the shrouded fluid hose 12 prevents the formation of water ice in the area outside the nozzle 20 and on the inner surface 20h of the nozzle 20.

[0019] The hand control 8 holds the discharge assembly 10 and includes a control device that communicates with a controller (not shown) to control the operation of the blast system 2. The hand control 8 may be used by an operator to orient the discharge assembly 10 toward a target or workpiece so that the accompanying flow emanating from the discharge assembly 10 collides with the target or workpiece. The discharge assembly 10 may be held by any suitable support other than the hand control 8, such as being held by a controllable / movable structure such as a robot, or it may not be movable, in which case the target or workpiece may be moved relative to the discharge assembly 10.

[0020] Referring to FIG. 2, an exploded view of one embodiment of the ejection assembly 10, also referred to herein as the blast nozzle assembly 10, is shown. In the depicted embodiment, the blast nozzle assembly 10 includes a nozzle base 18, a nozzle 20, a shroud 22, and a fitting 24. Referring also to FIG. 3, in the depicted embodiment, the nozzle base 18 includes a first male thread 18a for connecting the nozzle base 18 to the hand control 8 or any other support. The nozzle base 18 includes a second male thread 18b, which is configured to threadedly engage a first female thread 22a of the shroud 22, whereby the nozzle base 18 can be attached to the shroud 22. The nozzle base 18 includes an internal thread 18c (see FIG. 3), which is configured to threadedly engage a male thread 20a of the nozzle 20. The threads are not the only way these components can be connected together. Any suitable connection configuration between the nozzle base 18, the nozzle 20, and the shroud 22 can be used. Depending on the manufacturing technique, the blast nozzle assembly can be made as an integral structure, but there are advantages to using components that can be assembled, such as the compatibility of groups of components that allow common parts to be assembled into different final assemblies for specific operating parameters and applications.

[0021] In the embodiment depicted in FIG. 3, the nozzle base 18 and the nozzle 20 constitute a convergent-divergent nozzle, which, when operated with appropriate parameters, discharges a supersonic entrained particle flow from an outlet 20c. Alternatively, the nozzle base 18 and the nozzle 20 may be configured as a subsonic sonic nozzle or a sonic nozzle.

[0022] In the depicted embodiment, the nozzle base 18 includes an internal passage 18d that converges in a direction (flow direction) from an inlet 18e to an outlet 18f. In the depicted embodiment, the outlet 18f is formed at an upstream end of the internal thread 18c and, when connected to the nozzle 20, the outlet 18f abuts proximally to and occupies the same space as an inlet 20d of the nozzle 20.

[0023] Nozzle 20 includes an internal passage 20e that diverges in the direction from inlet 20d to outlet 20c in the depicted embodiment. Thus, internal passages 18d and 20e form a continuous converging-diverging passage, and its throat (where sonic flow occurs as is well known) is at outlet 18f / inlet 20d.

[0024] The combined internal passages 18d and 20e of nozzle base 18 / nozzle 20 form a nozzle passage. Regardless of whether the nozzle passage is configured as a subsonic nozzle, a sonic nozzle, or a supersonic nozzle, the nozzle passage can be connected to a source 4 of entrained carbon dioxide particles disposed in fluid communication therewith.

[0025] Referring also to FIG. 6, shroud 22 defines an internal passage 22b having an outlet 22c. Shroud 22 includes a plurality of inlets 22d in fluid communication with internal passage 22b at the end to which nozzle base 18 is attached. In the depicted embodiment, there are two inlets 22d, although a single inlet or three or more inlets may be used. Each respective inlet 22d includes a respective second female thread 22e configured to mate with a respective fitting 24. Inlets 22d are configured to be connected to a fluid source 14, which in the depicted embodiment includes a pressurized fluid source 16 and an aftercooler 26 (or, alternatively, a fluid heater or an aftercooler and heater as described above). In the depicted embodiment, shroud fluid hose 12 places inlets 22d and thus internal passage 22b in fluid communication with fluid source 18. Further, fluid source 14 to shroud fluid hose 12 may be provided separately from the pressurized fluid supplied by compressor 16 to supply portion 4b.

[0026] As shown in Figure 3, the blast nozzle assembly 10 includes a nozzle 20 coupled to a nozzle base 18 as described above, the nozzle base 18 being coupled to a shroud 22 via a second male thread 18b / first female thread 22a, thereby positioning the nozzle 20 within the internal passage 20e. The nozzle 20 includes a number of spacers or standoffs 20b (see Figure 5) extending radially outward from the outer surface 20f of the nozzle 20, proximal to the outlet 20c. As shown in Figure 5, the spacers 20b are spaced radially apart from each other by 120° in the embodiment depicted. The spacers 20b are spaced longitudinally (along the nozzle axis 20g) from the inlet 20d toward the outlet 20c, and are positioned to support the nozzle 20 against the inner surface 22f and to align the nozzle axis 20g with the shroud axis 22g within tolerance. Therefore, the outer diameter enclosed by the spacers 20b allows the nozzle 20 to be inserted into the internal passage 22b beyond the first female thread 22a and rotated within the internal passage 22b when the second male thread 18b of the nozzle base 18 is rotated to secure the nozzle base 18 to the shroud 22, while still providing support and alignment to the nozzle 20. Any appropriate number and spacing of spacers 20b can be used. For example, each spacer 20b may be positioned in a different axial location, while still providing support and alignment that can improve the fluid flow through the internal passage 22b of the shroud 22.

[0027] The arrangement / installation of the nozzle 20 within the shroud 22 forms an annular passage 22b' from the internal passage 22b, with the majority of its length bounded by the outer surface 20f and the inner surface 22f. The inlet 22d is in fluid communication with the annular passage 22b'. When the inlet 22d is connected to the fluid source 14, the annular passage 22b' is in fluid communication with the fluid source 14.

[0028] Referring also to Figure 4, the nozzle 20 and shroud 22 are positioned relative to each other such that outlet 20c can be aligned with outlet 22c. As will be discussed later, in addition to precise alignment, there is a functional range for the relative positions of outlet 20c and outlet 22c.

[0029] During the operation of the particle blast system 2, carbon dioxide particles are introduced into the flow of transport gas from the compressor 16 by the supply section 4b. The flow of entrained carbon dioxide particles travels through the entrained flow delivery hose 6 to the nozzle base 18. In the embodiment depicted, this flow is accelerated as it flows through the converging internal passage 18d, reaching Mach 1 at the throat (outlet 18f / inlet 20d). The flow is then further accelerated by the diverging internal passage 20e, becoming supersonic, and finally exiting through the outlet 20c.

[0030] Regardless of whether the flow exiting nozzle 20 is subsonic, supersonic, or supersonic, the temperature of the flow exiting outlet 20c is extremely low, very cold, for example, -128.89°C (-200°F).

[0031] Regardless of the actual flow temperature, if the temperature of the outer surface of a blast nozzle without a shroud is below freezing according to the teachings of this innovation, moisture in the surrounding environment will form water ice on the nozzle's outer surface. Under certain operating parameters, the ice formed on the outer surface of the nozzle adjacent to the outlet accumulates and eventually extends into the flow path through which the entrained particles exit, reducing the outlet area and thus decreasing the effectiveness of the exiting flow. The outlet may become completely blocked.

[0032] In accordance with the teachings of this innovation, the blast nozzle assembly 10 includes a nozzle 20 at least partially located within a shroud 22. The nozzle 20 is surrounded by a fluid stream, e.g., air, but not limited to air, flowing through an annular passage 22b'. The temperature, moisture content, and flow rate of this fluid stream are desirable to be sufficient to prevent ice from obstructing the outflow of entrained particles over unspecified periods during continuous operation of the particle blast system 2. If the temperature, moisture content, and flow rate of this fluid stream are sufficient to prevent ice from obstructing the outflow of entrained particles over the entire design period for continuous operation of the particle blast system 2, the performance may be acceptable.

[0033] Therefore, in accordance with the teachings of this innovation, ice does not accumulate on the nozzle or shroud during continuous operation, at least for the design period for continuous operation, causing obstruction to the outflow of entrained particles. The temperature, moisture content, and flow rate of the fluid stream through the annular passage 22b' are sufficient to prevent ice from obstructing the flow of the fluid stream through the annular passage 22b'.

[0034] In the embodiments depicted, the air is a fluid stream flowing through the annular passage 22b'. The temperature of the air at outlet 22c is preferably above the dew point temperature of the ambient conditions, and the moisture content is low. In the embodiments depicted, the aftercooler 26 reduces the moisture content of the airflow into the annular passage 22b'. The flow rate of the fluid stream through the annular passage 22b' should be sufficient to perform the indicated function, but not to obstruct or affect the flow exiting the nozzle 20.

[0035] The nozzle 20 and shroud 22 can be made of any suitable material. For example, the nozzle base 18, nozzle body 20, and shroud 22 may be aluminum or titanium. Titanium provides strength even with small wall thickness and is resistant to damage. Titanium can also help avoid static electricity buildup if there is a suitable path for electrostatic discharge.

[0036] The outlet plane of nozzle outlet 20c is illustrated as aligned with outlet 22c in the depicted embodiment. Aside from the precise alignment related to the temperature, moisture content, and flow rate of the fluid stream through the annular passage 22b', there is a functional range for the relative positions of outlets 20c and 22c. Recessing outlet 20c within the annular passage 22b' relative to outlet 22c may require the fluid stream flowing through the annular passage 22b' to have a higher temperature, lower moisture content, or higher flow rate to prevent ice from obstructing the outflow of entrained particles during continuous operation of the particle blast system 2 over the entire design period for continuous operation. Insufficient temperature, moisture content, and flow rate parameters of the fluid stream flowing through the annular passage 22b' can lead to ice buildup and harmful bridging between the shroud and the nozzle.

[0037] The length of the nozzle enclosed by the annular passage must be sufficient to prevent ice from obstructing the outflow of entrained particles during continuous operation of the particle blast system 2, throughout the entire design period for continuous operation, and may depend on the temperature, moisture content, and flow rate parameters of the fluid stream flowing through the annular passage. The portion of the nozzle enclosed by the annular passage may include a divergent section from the throat to the outlet, as shown in Figures 2 to 6. The shrouded portion may include a converging section.

[0038] Figure 7 shows an alternative embodiment of the shrouded blast nozzle assembly 110 in which the annular passage 122b' does not encircle the entire length of the shroud 122. A seal 122a is formed between the shroud 122 and the nozzle 120. The embodiment in Figure 7 may not provide adequate minimization of water ice accumulation on the inner surface of the nozzle as all operating parameters.

[0039] Explicit definition "Based on" means that something is determined, at least partially, by the thing indicated as being "based on." If something is entirely determined by something, it would be written as "based exclusively on" that thing.

[0040] "Processor" means a device that can be configured, individually or in combination with other devices, to perform the various functionalities described herein. Examples of "processors" include microprocessors, microcontrollers, digital signal processors (DSPs), field-programmable gate arrays (FPGAs), programmable logic devices (PLDs), programmable logic controllers (PLCs), state machines, gate logic, and discrete hardware circuits. The term "processing system" is used to refer to one or more processors that may be contained in a single device or distributed across multiple physical devices.

[0041] The statement that a processing system is “configured” to perform one or more actions means that the processing system contains data (which may include instructions) that can be used to perform a particular action that the processing system is “configured” to perform. For example, in the case of a computer (a type of “processing system”), if you install Microsoft Word on the computer, the computer is “configured” to function as a word processor and works using Microsoft Word instructions in combination with other inputs such as the operating system and various peripherals (e.g., a keyboard, monitor, etc.).

[0042] The above description of one or more embodiments of this innovation is presented for illustrative and explanatory purposes only. It is not intended to be exhaustive or to limit the invention to the exact form disclosed. Obvious modifications or alterations are possible in light of the above teachings. The embodiments have been selected and described so as to best illustrate the principle of this innovation and its practical application, thereby enabling those skilled in the art to best utilize the innovation in various embodiments and with various modifications to suit specific intended uses. Although only a limited number of embodiments of this innovation are described in detail, it should be understood that the scope of this innovation is not limited to the structural and arrangement details of the components described in the above description or shown in the drawings. Other embodiments of this innovation are possible and can be carried out or performed in various ways. Also, specific terms have been used for clarity. It is understood that each specific term includes all technical equivalents that operate in the same manner to achieve a similar purpose. The scope of the invention is intended to be defined by the claims submitted together.

[0043] [Implementation Method] (1) A blast nozzle assembly, a. A shroud including a shroud passage, wherein the shroud passage is i. Shroud passage inner surface and, ii. Shroud outlet and, iii. At least one shroud inlet, each of which is in fluid communication with the internal passage and the shroud outlet, and each of which is configured to be connected to a source of shroud fluid, iv. The shroud flow direction defined in the direction from at least one shroud inlet to the shroud outlet, Shroud, including, b. A blast nozzle including an outer surface and an internal nozzle passage, wherein the internal nozzle passage is configured to transport a co-flow of cryogenic particles through it, i. Nozzle inlet and ii. Nozzle outlet and iii. The nozzle flow direction defined in the direction from the nozzle inlet to the nozzle outlet, A blast nozzle, Includes, A blast nozzle assembly in which the blast nozzle is attached to the shroud such that at least a portion of the outer surface of the blast nozzle constitutes the inner boundary of the shroud passage. (2) The blast nozzle assembly according to Embodiment 1, wherein the nozzle outlet is aligned with the shroud outlet. (3) The blast nozzle assembly according to Embodiment 1, wherein the nozzle outlet is located downstream of the shroud outlet. (4) The blast nozzle assembly according to Embodiment 1, wherein the shroud passage is annular. (5) The blast nozzle assembly according to Embodiment 1, wherein the blast nozzle includes a plurality of spacers configured to support the nozzle with respect to the inner surface of the shroud passage.

[0044] (6) The blast nozzle assembly according to Embodiment 5, wherein the nozzle includes a nozzle shaft, the shroud includes a shroud shaft, and the plurality of spacers are configured to align the nozzle shaft with the shroud shaft. (7) The blast nozzle assembly according to Embodiment 1, wherein the internal nozzle passage includes a converging portion and a diverging portion located downstream of the converging portion. (8) A particle blast system configured for cryogenic particles, a. Source of accompanying cryogenic particles, b. Source of shroud fluid, c. A blast nozzle assembly, i. A shroud including a shroud passage, wherein the shroud passage is (a) The inner surface of the shroud passage and (b) Shroud outlet and, (c) at least one shroud inlet, each of which is in fluid communication with the internal passage and the shroud outlet, and each of which is in fluid communication with the source of the shroud fluid, (d) A shroud flow direction defined in the direction from the at least one shroud inlet to the shroud outlet, Shroud, including, i. A blast nozzle including an outer surface and an internal nozzle passage, wherein the internal nozzle passage is configured to transport a co-flow of cryogenic particles through it, (a) A nozzle inlet that is in fluid communication with the source of the accompanying cryogenic particles, (b) Nozzle outlet and (c) The nozzle flow direction defined in the direction from the nozzle inlet to the nozzle outlet, A blast nozzle, A blast nozzle assembly, including Includes, A particle blasting system in which the blast nozzle is attached to the shroud such that at least a portion of the outer surface of the blast nozzle constitutes the inner boundary of the shroud passage. (9) The particle blast system according to Embodiment 8, wherein the source of the shroud fluid is configured to supply a shroud fluid having a temperature higher than the dew point temperature of the ambient conditions. (10) The particle blasting system according to Embodiment 8, comprising an aftercooler configured to reduce the water content of the shroud fluid.

[0045] (11) The particle blast system according to Embodiment 8, comprising a heater configured to raise the temperature of the shroud fluid. (12) The particle blast system according to Embodiment 8, wherein the source of the shroud fluid is configured to supply the shroud fluid at a temperature, water content, and flow rate sufficient to prevent ice from forming adjacent to the nozzle outlet for a period of time during continuous operation of the particle blast system, thereby obstructing the flow of entrained particles out. (13) The particle blast system according to Embodiment 12, wherein the particle blast system has a design period for continuous operation, and the source of the shroud fluid is configured to supply the shroud fluid at a temperature, moisture content, and flow rate sufficient to prevent ice from forming adjacent to the nozzle outlet and obstructing the outflow of entrained particles throughout the entire design period for continuous operation of the particle blast system. (14) A method for reducing ice buildup inside and at the outlet of a blast nozzle, which has a flow of entrained cryogenic particles that pass through the inside and exit the outlet, a. A step of transporting cryogenic particles entrained in the flow of transport gas through the outlet of the blast nozzle and out of the outlet over a certain period of time. b. A step of flowing a fluid adjacent to a portion of the outer surface of the blast nozzle, along its length, near the outlet of the blast nozzle, while the step of flowing the cryogenic particles is being performed, wherein the fluid has a temperature, water content, and flow rate sufficient to prevent obstruction of the flow of cryogenic particles through the outlet of the blast nozzle and out of the outlet during the period, Methods that include... (15) The method according to Embodiment 14, further comprising the step of removing water from the fluid before performing the step of flowing the fluid.

[0046] (16) The method of Embodiment 14, comprising the step of heating the fluid before performing the step of flowing the fluid. (17) The method according to Embodiment 14, wherein the step of flowing the fluid includes flowing the fluid through an annular passage partially defined by the outer surface of the blast nozzle. (18) The method according to Embodiment 14, wherein the temperature of the fluid is greater than the dew point temperature under ambient conditions. (19) A method for reducing ice buildup inside and at the outlet of a blast nozzle, which has a flow of entrained cryogenic particles that pass through the inside and exit the outlet, a. A step of transporting cryogenic particles entrained in the flow of transport gas through the outlet of the blast nozzle and out of the outlet over a certain period of time. b. While the step of flowing the cryogenic particles is being performed, a step of flowing a fluid adjacent to a portion of the outer surface of the blast nozzle, along its length, and near the outlet of the blast nozzle, wherein the fluid has a temperature, water content, and flow rate. c. The steps of controlling the temperature, sufficient moisture, and flow rate of the fluid to prevent obstruction of the flow of cryogenic particles through the outlet of the blast nozzle and out of the outlet during the period, Methods that include...

Claims

1. A blast nozzle assembly, a. A shroud including a shroud passage, wherein the shroud passage is i. Shroud passage inner surface and ii. Shroud outlet and iii. At least one shroud inlet, each of which is in fluid communication with the shroud outlet, and each of which is configured to be connected to a source of shroud fluid, iv. The shroud flow direction defined in the direction from the at least one shroud inlet to the shroud outlet, Shroud, including, b. A blast nozzle including an outer surface and an internal nozzle passage, wherein the internal nozzle passage is configured to transport a co-flow of cryogenic particles through it, i. A nozzle inlet that is in fluid communication with the source of the accompanying cryogenic particles and is located upstream of the at least one shroud inlet, ii. Nozzle outlet and iii. The nozzle flow direction defined in the direction from the nozzle inlet to the nozzle outlet, A blast nozzle, Includes, The blast nozzle is attached to the shroud such that at least a portion of the outer surface of the blast nozzle constitutes the inner boundary of the shroud passage. The internal nozzle passage includes a converging portion, The aforementioned convergence portion is a blast nozzle assembly located upstream of the shroud passage.

2. The blast nozzle assembly according to claim 1, wherein the nozzle outlet is aligned with the shroud outlet.

3. The blast nozzle assembly according to claim 1, wherein the shroud passage is annular.

4. The blast nozzle assembly according to claim 1, wherein the blast nozzle includes a plurality of spacers configured to support the nozzle with respect to the inner surface of the shroud passage.

5. The blast nozzle assembly according to claim 4, wherein the nozzle includes a nozzle shaft, the shroud includes a shroud shaft, and the plurality of spacers are configured to align the nozzle shaft with the shroud shaft.

6. The blast nozzle assembly according to claim 1, wherein the internal nozzle passage further includes a diverging portion located downstream of the converging portion.

7. A particle blast system configured for cryogenic particles, a. Source of accompanying cryogenic particles, b. Source of shroud fluid and c. A blast nozzle assembly, i. A shroud including a shroud passage, wherein the shroud passage is (a) Shroud passage inner surface and (b) Shroud outlet and (c) at least one shroud inlet, each of which is in fluid communication with the shroud outlet, and each of which is in fluid communication with the source of the shroud fluid, (d) The shroud flow direction defined in the direction from the at least one shroud inlet to the shroud outlet, Shroud, including, i. A blast nozzle including an outer surface and an internal nozzle passage, wherein the internal nozzle passage is configured to transport a co-flow of cryogenic particles through it, (a) A nozzle inlet that is in fluid communication with the source of the accompanying cryogenic particles and is located upstream of the at least one shroud inlet, (b) Nozzle outlet and (c) The nozzle flow direction defined in the direction from the nozzle inlet to the nozzle outlet, A blast nozzle, A blast nozzle assembly, including Includes, The blast nozzle is attached to the shroud such that at least a portion of the outer surface of the blast nozzle constitutes the inner boundary of the shroud passage. The internal nozzle passage includes a converging portion, The aforementioned convergence section is a particle blast system located upstream of the shroud passage.

8. The particle blast system according to claim 7, wherein the source of the shroud fluid is configured to supply shroud fluid having a temperature higher than the dew point temperature of the ambient conditions.

9. The particle blasting system according to claim 7, comprising an aftercooler configured to reduce the water content of the shroud fluid.

10. The particle blasting system according to claim 7, further comprising a heater configured to raise the temperature of the shroud fluid.

11. The particle blasting system according to claim 7, wherein the source of the shroud fluid is configured to supply the shroud fluid at a temperature, water content, and flow rate sufficient to prevent ice from forming adjacent to the nozzle outlet for a period of time during continuous operation of the particle blasting system, thereby obstructing the flow of entrained particles out.

12. The particle blasting system according to claim 11, wherein the particle blasting system has a design period for continuous operation, and the source of the shroud fluid is configured to supply the shroud fluid at a temperature, moisture content, and flow rate sufficient to prevent ice from forming adjacent to the nozzle outlet and obstructing the outflow of entrained particles throughout the entire design period for continuous operation of the particle blasting system.

13. A method for reducing ice accumulation inside and at the outlet of a blast nozzle, which has a flow of accompanying cryogenic particles that pass through the interior and exit the outlet, a. A step of creating a co-existing flow upstream of the blast nozzle by entraining multiple cryogenic particles into the flow of transport gas, b. A step of flowing the accompanying flow through the outlet of the blast nozzle and out of the outlet for a certain period of time, wherein the blast nozzle has an internal nozzle passage including a converging portion, and the accompanying flow flows through the internal nozzle passage. c. While performing the step of flowing the accompanying flow, a step of causing a fluid to flow within a shroud having a shroud passage, wherein the fluid flows along its length adjacent to a portion of the outer surface of the blast nozzle, in the vicinity of the outlet of the blast nozzle, the converging portion is located upstream of the shroud passage, and the fluid has a temperature, water content and flow rate sufficient to prevent ice from forming adjacent to the outlet of the blast nozzle during the period, thereby obstructing the flow of accompanying particles. Methods that include...

14. The method according to claim 13, further comprising the step of removing water from the fluid before performing the step of flowing the fluid.

15. The method according to claim 13, further comprising the step of heating the fluid before performing the step of flowing the fluid.

16. The method according to claim 13, wherein the shroud passage includes an annular passage partially defined by the outer surface of the blast nozzle.

17. The method according to claim 13, wherein the temperature of the fluid is above the dew point temperature under ambient conditions.

18. A method for reducing ice accumulation inside and at the outlet of a blast nozzle, which has a flow of accompanying cryogenic particles that pass through the interior and exit the outlet, a. A step of creating a co-existing flow upstream of the blast nozzle by entraining multiple cryogenic particles into the flow of transport gas, b. A step of flowing the accompanying flow through the outlet of the blast nozzle and out of the outlet for a certain period of time, wherein the blast nozzle has an internal nozzle passage including a converging portion, and the accompanying flow flows through the internal nozzle passage. c. While performing the step of flowing the accompanying flow, a step of causing a fluid to flow within a shroud having a shroud passage, wherein the fluid flows along its length adjacent to a portion of the outer surface of the blast nozzle, near the outlet of the blast nozzle, the converging portion is located upstream of the shroud passage, and the fluid has temperature, water content, and flow rate, d. A step of controlling the temperature, water content, and flow rate of the fluid to prevent ice from forming in the vicinity of the outlet of the blast nozzle during the period, thereby obstructing the flow of entrained particles. Methods that include...

19. The particle blast system according to claim 7, wherein the internal nozzle passage further includes a diverging portion located downstream of the converging portion.

20. The method according to claim 13 or 18, wherein the internal nozzle passage further includes a diverging portion located downstream of the converging portion.

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