US20200386243A1

US20200386243A1 - Powder jet pump

Info

Publication number: US20200386243A1
Application number: US16/603,114
Authority: US
Inventors: Karl K. Stensvad; Eric A. Vandre; Saurabh Batra
Original assignee: 3M Innovative Properties Co
Current assignee: 3M Innovative Properties Co
Priority date: 2017-04-10
Filing date: 2018-03-27
Publication date: 2020-12-10
Also published as: CN110494655A; CN110494655B; EP3610158A1; EP3610158B1; WO2018191008A1

Abstract

A powder jet pump that is effective for creating a smoothly flowing gas stream with well dispersed particles.

Description

TECHNICAL FIELD

The present disclosure relates generally to the introduction of fine particles into a gas stream, and more particularly to an efficient powder jet pump.

BACKGROUND

Certain industrial processes require the introduction of particulate matter into a gas stream. Powder jet pumps (i.e., jet pumps that are suitable for entraining powder into a fluid) can be used for the introduction of powder into a gas stream. They use a motive (pressurized) fluid to induce flow in a suction fluid (or fluid containing powder in the case of a powder jet pump). These devices are commonly used to move bulk solids or fluids containing solids. They are often ideally suited to this task because of their simplicity and robustness. Typically, they have no moving parts. Jet pumps typically have a mixing region where the motive and suction fluids meet before they enter a nozzle. While a nozzle is a common design feature of jet pumps, the function is distinctly different from a Venturi pump in that pressure drop is created by energy transfer from the motive fluid to the suction fluid. In a true Venturi pump, suction is created by the pressure drop in the nozzle itself.
Powder jet pumps may be used to introduce powder at a powder inlet port and mix it with a gas stream (e.g., air), then emit well-dispersed powder particles entrained in the gas stream. In some applications, subsequent gas handling devices can cause gas stream pressures at the powder jet pump outlet (i.e., back pressure) to be high or fluctuate to high pressure, thereby cause the powder jet pump to stall, or reverse the flow direction. This problem has been generally overcome by various designs that use high output gauge pressure from the powder jet pump, but such high pressure are not always desirable. There remains a need for powder jet pumps that can operate effectively at relatively low gauge pressure.

SUMMARY

The present disclosure provides a powder jet pump that is notably energy efficient and effective at creating a smoothly flowing gas stream with well-dispersed particles. The powder jet pump may impart rotational angular momentum to the gas/particle mixture to improve the dispersion and resist agglomeration at low gas stream gauge pressures (e.g., 1-10 psi). Advantageously, the powder jet pump has improved resistance to stalling at higher back pressures than prior designs.
In one aspect, the present disclosure provides a powder jet pump, comprising:
a main body having a particle inlet at a first end and an outlet connector at a second end, the particle inlet being in fluid communication with an inlet chamber;
a nozzle defining a passage in fluid communication with the chamber and outlet connector, wherein the nozzle includes a nozzle throat;
at least one suction inlet in fluid communication with the chamber;
an annular plenum positioned around the main body having a gas inlet; and
at least two jet passages each having an inlet opening into the annular plenum and an outlet opening within the nozzle throat.
As used herein:
the term “gauge pressure” refers to a relative pressure measurement which measures pressure relative to outlet pressure and is defined as the absolute pressure minus the outlet pressure; and
the term “nozzle throat” refers to an area of minimum cross section of a nozzle.
Features and advantages of the present disclosure will be further understood upon consideration of the detailed description as well as the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure may be more completely understood in consideration of the following detailed description of various embodiments of the disclosure in connection with the accompanying figures, in which:

FIG. 1 is a perspective drawing of exemplary powder jet pump 20 according to the present disclosure;

FIG. 2 is side cross section view of powder jet pump 20, taken along section lines 2-2 in FIG. 1;

FIG. 2A is an enlarged view of region 2A in FIG. 2;

FIG. 2B is an enlarged perspective cross-sectional view of region 2B in FIG. 2; and

FIG. 3 is a side view of powder jet pump 20.

Repeated use of reference characters in the specification and drawings is intended to represent the same or analogous features or elements of the disclosure. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art, which fall within the scope and spirit of the principles of the disclosure. The figures may not be drawn to scale.

DETAILED DESCRIPTION

The present disclosure describes a powder jet pump for the introduction of particles into a gas stream.
Referring now to FIGS. 1-3, exemplary powder jet pump 20 comprises a main body 22 has a particle inlet 24 at a first end 27 and an outlet connector 44 at a second end 29. Particle inlet 24 is in fluid communication with inlet chamber 28. Nozzle 42 defines passage 48 in fluid communication with inlet chamber 28 and outlet connector 44. Nozzle 42 includes nozzle throat 40. Suction inlets 26 are in fluid communication with inlet chamber 28. Annular plenum 32 is positioned around main body 22 has gas inlet 34. While shown as a torus, it will be recognized that other shapes of the annular plenum that accomplish the technical effect of feeding the jet passages may also be used (e.g., polygonal plenums). Hollow jet passages 52 each have a respective inlet opening 56 (see FIG. 2B) into the annular plenum 32 and an outlet opening 36 within nozzle throat 40. Optional braces 38 add structural reinforcement to powder jet pump 20.
In use, pressurized gas (e.g., compressed air) enters gas inlet 34, continues into annular plenum 32, and is directed through jet passages 52 from annular plenum 32 to nozzle throat 40 positioned at the end of inlet chamber 28 opposite particle inlet 24. Throat 40 widens into nozzle 42, terminating in outlet connector 44. Exemplary useful gases include air, nitrogen, and argon. Other gases may also be used.
Typical gauge pressures for the pressurized gas are 1 to 10 psi (6.9 to 69 kPa). Other gauge pressures may also be used.
In the embodiment shown in FIG. 1, respective outlet openings 36 of jet passages 52 are helically advanced in the direction of gas stream rotation relative to their inlet openings 56, although this is not a requirement.
Preferably, the jet passages (which are tubes) have an inner diameter in the range of 0.01 inch (0.25 mm) to 0.05 inch (1.27 mm), although this is not a requirement. Preferably, the jet passages have respective lengths in the range of 0.10 inch (0.25 mm) to 1.00 inch (2.54 cm), although this is not a requirement.
Referring now to FIG. 2, particle inlet 24 has an annular counterbore 45 which can receive, e.g., an O-ring seal to prevent particle leakage during operation of powder jet pump 20 if connected to a particle feed device (e.g., a screw feeder or gravity hopper). Nozzle throat 40 has a nozzle throat inner wall 46. Jet passages 52 are helically configured such that a portion of each jet passage 52 adjacent to its respective outlet opening 36 is disposed at an angle of 1 to 10 degrees relative to the nozzle throat inner wall 46. In this embodiment, the gas stream causes a vortex to form in the nozzle throat, thereby reducing recirculating flow in the gas stream emerging from nozzle. While the above geometry is preferred, other angles of the jet passages relative to the nozzle throat inner wall may also be used.
Nozzle throat 40 has an inner diameter 41, and nozzle 42 has a maximum inner diameter 43 (see FIG. 2A). In some embodiments, the ratio of the inner diameter 41 to the maximum inner diameter 43 is in the range of 1:1 to 1:20, preferably 1:2 to 1:10, and more preferably 1:4 to 1:7. Preferably, the nozzle throat has a minimum inner diameter in the range of 0.03 inch (0.76 mm) to 0.11 inch (2.79 mm), although this is not a requirement.
While the powder jet pump can be made from assembled parts, in preferred embodiments, the powder jet pump is unitary (i.e., a single part). This may be accomplished by a rapid prototyping method such as, for example, fused deposition modeling or stereolithography.
The various components of the powder jet pump may be made of any suitable material(s), including, for example, metal, plastic (including engineering plastics such as high density polyethylene, polycarbonate, polyimide, polyether ether ketone, polyether ketone), glass, and fiber reinforced composites, (e.g., fiberglass, carbon fiber composites), and combinations thereof.
Powder jet pumps according to the present disclosure can be used in powder coating applications including but not limited to painting, powder dispersion, and the coating of woven and non-woven articles.
Exemplary embodiments of the present disclosure may take on various modifications and alterations without departing from the spirit and scope of the present disclosure. Accordingly, it is to be understood that the embodiments of the present disclosure are not to be limited to the following described exemplary embodiments, but is to be controlled by the limitations set forth in the claims and any equivalents thereof.

Select Embodiments of the Present Disclosure

In a first embodiment, the present disclosure provides a powder jet pump, comprising:
a main body having a particle inlet at a first end and an outlet connector at a second end, the particle inlet being in fluid communication with an inlet chamber;
a nozzle defining a passage in fluid communication with the chamber and outlet connector, wherein the nozzle includes a nozzle throat;
at least one suction inlet in fluid communication with the chamber;
an annular plenum positioned around the main body having a gas inlet; and
at least two jet passages each having an inlet opening into the annular plenum and an outlet opening within the nozzle throat.
In a second embodiment, the present disclosure provides a powder jet pump according to the first embodiment, wherein the gas inlet is configured to impart a direction of rotation within the annular plenum to a gas travelling through the gas inlet and into the annular plenum.
In a third embodiment, the present disclosure provides a powder jet pump according to the first or second embodiment, wherein respective outlet openings of the at least two jet passages are helically advanced in the direction of rotation relative to their respective inlet openings.
In a fourth embodiment, the present disclosure provides a powder jet pump according to any one of the first to third embodiments, wherein the nozzle throat has a nozzle throat inner wall, and wherein the at least two jet passages are configured such that a portion of each jet passage adjacent to its respective outlet opening is disposed at an angle of 1 to 10 degrees relative to the nozzle throat inner wall.
In a fifth embodiment, the present disclosure provides a powder jet pump according to any one of the first to third embodiments, wherein the nozzle throat has a longitudinal axis, wherein the at least two jet passages are configured such that a portion of each jet passage adjacent to its respective outlet opening is disposed at an angle of 1 to 10 degrees relative to the longitudinal axis of the nozzle throat.
In a sixth embodiment, the present disclosure provides a powder jet pump according to any one of the first to fifth embodiments, wherein the nozzle throat has an inner diameter, wherein the nozzle has a maximum inner diameter, and wherein the ratio of the inner diameter of the nozzle throat to the maximum inner diameter of the nozzle is in the range of 1:2 to 1:10.
In a seventh embodiment, the present disclosure provides a powder jet pump according to any one of the first to sixth embodiments, wherein the powder jet pump is unitary.
In an eighth embodiment, the present disclosure provides a powder jet pump according to any one of the first to seventh embodiments, wherein the nozzle throat has a minimum inner diameter in the range of 0.03 inch (0.76 mm) to 0.11 inch (2.79 mm).
In a ninth embodiment, the present disclosure provides a powder jet pump according to any one of the first to eighth embodiments, wherein the at least two jet passages have respective inner diameters in the range of 0.01 inch (0.25 mm) to 0.05 inch (1.27 mm).
In a tenth embodiment, the present disclosure provides a powder jet pump according to any one of the first to eighth embodiments, wherein the at least two jet passages have respective lengths in the range of 0.10 inch (0.25 mm) to 1.00 inch (2.54 cm).
Objects and advantages of this disclosure are further illustrated by the following non-limiting examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this disclosure.

EXAMPLES

Unless otherwise noted, all parts, percentages, ratios, etc. in the Examples and the rest of the specification are by weight.

Example 1

An apparatus generally as depicted in FIG. 1 was fabricated by standard additive manufacturing techniques. The inner diameter of the throat was 0.08 inch (2 mm). The jet passages had a length of 0.55 inch (14 mm) and an inner diameter of 0.02 inch (0.5 mm). Fine carbon particles were introduced into the particle inlet via a twin-screw feeder at a rate of 1 g/min. Air was introduced at the gas inlet at gauge pressures ranging between 1 and 10 psi (6.9 to 69 kPa). A fine dispersion of the particles in the gas/particle mixture emerging from the outlet connector was observed over the pressure range.
All cited references, patents, and patent applications in the above application for letters patent are herein incorporated by reference in their entirety in a consistent manner. In the event of inconsistencies or contradictions between portions of the incorporated references and this application, the information in the preceding description shall control. The preceding description, given in order to enable one of ordinary skill in the art to practice the claimed disclosure, is not to be construed as limiting the scope of the disclosure, which is defined by the claims and all equivalents thereto.

Claims

What is claimed is:

1. A powder jet pump, comprising:

a main body having a particle inlet at a first end and an outlet connector at a second end, the particle inlet being in fluid communication with an inlet chamber;

a nozzle defining a passage in fluid communication with the chamber and outlet connector, wherein the nozzle includes a nozzle throat;

at least one suction inlet in fluid communication with the chamber;

an annular plenum positioned around the main body having a gas inlet; and

at least two jet passages each having an inlet opening into the annular plenum and an outlet opening within the nozzle throat.

2. The powder jet pump of claim 1, wherein the gas inlet is configured to impart a direction of rotation within the annular plenum to a gas travelling through the gas inlet and into the annular plenum.

3. The powder jet pump of claim 2, wherein respective outlet openings of the at least two jet passages are helically advanced in the direction of rotation relative to their respective inlet openings.

4. The powder jet pump of claim 1, wherein the nozzle throat has a nozzle throat inner wall, and wherein the at least two jet passages are configured such that a portion of each jet passage adjacent to its respective outlet opening is disposed at an angle of 1 to 10 degrees relative to the nozzle throat inner wall.

5. The powder jet pump of claim 4, wherein the at least two jet passages are configured such that a portion of each jet passage adjacent to its respective outlet opening is disposed at an angle of 1 to 10 degrees relative to the longitudinal axis of the nozzle throat.

6. The powder jet pump of claim 1, wherein the nozzle throat has an inner diameter, wherein the nozzle has a maximum inner diameter, and wherein the ratio of the inner diameter of the nozzle throat to the maximum inner diameter of the nozzle is in the range of 1:2 to 1:10.

7. The powder jet pump of claim 1, wherein the powder jet pump is unitary.

8. The powder jet pump of claim 1, wherein the nozzle throat has a minimum inner diameter in the range of 0.03 inch (0.76 mm) to 0.11 inch (2.79 mm).

9. The powder jet pump of claim 1, wherein the at least two jet passages have respective inner diameters in the range of 0.01 inch (0.25 mm) to 0.05 inch (1.27 mm).

10. The powder jet pump of claim 1, wherein the at least two jet passages have respective lengths in the range of 0.10 inch (0.25 mm) to 1.00 inch (2.54 cm).