WO2014138775A1

WO2014138775A1 - System and method for particulate matter agglomeration using carrier particles

Info

Publication number: WO2014138775A1
Application number: PCT/AU2014/000195
Authority: WO
Inventors: Payam MOUSAVIOUN
Original assignee: Peak 3 Pty Ltd
Priority date: 2013-03-11
Filing date: 2014-02-28
Publication date: 2014-09-18

Abstract

A method of particulate matter agglomeration enables cost effective and efficient filtration of small particles. The method includes receiving a colloid including colloidal particles; introducing carrier particles into the colloid, where the carrier particles are generally larger than the colloidal particles; and applying ultrasonic energy to both the colloid and the carrier particles to cause the colloidal particles to agglomerate with the carrier particles.

Description

TITLE

SYSTEM AND METHOD FOR PARTICULATE MATTER AGGLOMERATION USING CARRIER PARTICLES FIELD OF THE INVENTION

The present invention relates to particle agglomeration. In particular, although not exclusively, the invention relates to particle agglomeration using ultrasonic energy and carrier particles. BACKGROUND TO THE INVENTION

Airborne particles are an important consideration in air quality. Dust, pollen and smoke are examples of such particles that, when present, can significantly decrease air quality. Similarly, the presence of particles is an important consideration in the quality of other fluids such as water.

Diesel exhaust fumes are an example of fumes including airborne particles that significantly reduce air quality. Exposure to diesel exhaust and diesel particulate matter (DPM) is a known hazard to humans and diesel emissions are classified by the International Agency for Research on Cancer as a Group 1 Carcinogen. In other words diesel particulate matter is known to be carcinogenic to humans.

Filters are thus often used to remove such particles in order to improve the quality of these fluids. An example of such a filter of the prior art is the mechanical mesh-type filter, which is used to trap the particles while letting the remaining fluid pass.

A problem with mechanical filters of the prior art is that they cannot efficiently filter very small particles. In the case of diesel exhaust filters, many systems of the prior art simply reduce the "smoke", or larger particulate size, and while appearing to be cleaner, the exhaust fumes still contain large amounts of DPM having small particle size. Similar problems exist for other types of fumes'.

A further problem with mechanical filters is that they become clogged and require replacement and/or cleaning at regular intervals. Such systems of the prior art including mechanical filters therefore do not provide adequate filtration.

Attempts have been made to improve filtration of particles using ultrasonic energy to agglomerate particles. While such agglomeration does result in larger agglomerated particles, it has not significantly improved filtration of very small particles.

There is therefore a need for an improved particle filtration system.

OBJECT OF THE INVENTION

It is an object of some embodiments of the present invention to provide consumers with improvements and advantages over the above described prior art, and/or overcome and alleviate one or more of the above described disadvantages of the prior art, and/or provide a useful commercial choice.

SUMMARY OF THE INVENTION

According to a first aspect, the invention resides in a method of particulate matter agglomeration, the method including:

receiving a colloid including colloidal particles;

introducing carrier particles into the colloid, where the carrier particles are generally larger than the colloidal particles; and

applying ultrasonic energy to both the colloid and the carrier particles to cause the colloidal particles to agglomerate with the carrier particles.

As will be readily understood by the skilled addressee, the colloid can be any suitable mixture in which small particles of one substance are distributed throughout another substance.

Preferably, the colloid is an aerosol. More preferably, the aerosol is a solid aerosol. Alternatively, the aerosol is a liquid aerosol.

Suitably, the aerosol includes diesel exhaust fumes. Suitably, the colloid is a suspension. Alternatively, the colloid is an emulsion. Alternatively again, the colloid comprises gaseous particles in a liquid.

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Preferably, the ultrasonic energy is applied at a frequency greater than 10kHz. More preferably, the ultrasonic energy is applied at a frequency greater than 20kHz.

Preferably, the method further comprises removing at least part of the agglomerated particles by filtration. More preferably, the filtration comprises mechanical filtration.

Preferably, the method further comprises adjusting a temperature of the colloid.

Preferably, a substantial portion of the carrier particles are larger than 20 m long. Preferably the carrier particles are on average at least

10 times larger than the colloidal particles.

Preferably, the method further comprises adjusting a flow of the carrier particles based upon at least one of: a temperature of the colloid; a flow rate of the colloid and a density of the colloid.

According to a second aspect, the invention resides in a particle matter agglomeration system including:

a first input for receiving a colloid, the colloid including colloidal particles;

a second input for receiving carrier particles, the carrier particles generally larger than the colloidal particles;

an acoustic chamber, coupled to the first input and the second input; and

an ultrasonic transducer, for applying ultrasonic energy to both the colloid and the carrier particles inside the acoustic chamber to cause the colloidal particles to agglomerate with the carrier particles.

Preferably, the ultrasonic transducer comprises a piezoelectric transducer.

Preferably, the system further comprises a filter, for removing the agglomerated colloidal particles. Preferably, the system further comprises a control module, for controlling operation of at least one of: the first input; the second input; and the ultrasonic transducer. Preferably, the control module includes a temperature sensor, for measuring a temperature of the colloid. Preferably, the control module includes a flow rate sensor for measuring a flow of at least one of the first input and the second input. Preferably, the control module includes a sensor for measuring a density of the colloid.

BRIEF DESCRIPTION OF THE DRAWINGS

To assist in understanding the invention and to enable a person skilled in the art to put the invention into practical effect, preferred embodiments of the invention are described below by way of example only with reference to the accompanying drawings, in which:

FIG. 1 illustrates a front perspective view of a particulate agglomeration system for a ventilation system, according to an embodiment of the present invention;

FIG. 2 illustrates an enlarged cut-away view of an acoustic chamber of the particulate agglomeration system of FIG. 1, according to an embodiment of the present invention;

FIG. 3 illustrates a front view of the particulate agglomeration system of FIG. 1;

FIG. 4 illustrates a top view of the particulate agglomeration system of FIG. 1;

FIG. 5 illustrates a left side view of the particulate agglomeration system of FIG. 1;

FIG. 6 illustrates a Scanning Electron Microscopy (SEM) image of a carrier particle on which a plurality of dust particles have agglomerated, according to an embodiment of the present invention;

FIG. 7a illustrates a Scanning Electron Microscopy (SEM) image of a carrier particle on which a plurality of DPM particles have agglomerated, according to an embodiment of the present invention;

FIG. 7b illustrates an enlarged view of a portion of the image of FIG. 7a, according to an embodiment of the present invention;

FIG. 8 illustrates a Scanning Electron Microscopy (SEM) image of a solid canier particle on which a plurality of liquid DPM particles have agglomerated, according to an embodiment of the present invention; and FIG. 9 illustrates a schematic view of a processing module of the system of FIG. 1 , according to an embodiment of the present invention.

Those skilled in the art will appreciate that minor deviations from the layout of components as illustrated in the drawings will not detract from the proper functioning of the disclosed embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention comprise particle agglomeration systems and methods. Elements of the invention are illustrated in concise outline form in the drawings, showing only those specific details that are necessary to the understanding of the embodiments of the present invention, but so as not to clutter the disclosure with excessive detail that will be obvious to those of ordinary skill in the art in light of the present description.

In this patent specification, adjectives such as first and second, left and right, front and back, top and bottom, etc., are used solely to define one element or method step from another element or method step without necessarily requiring a specific relative position or sequence that is described by the adjectives. Words such as "comprises" or "includes" are not used to define an exclusive set of elements or method steps. Rather, such words merely define a minimum set of elements or method steps included in a particular embodiment of the present invention.

The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge.

According to one aspect, the invention resides in a method of particulate matter agglomeration, the method including: receiving a colloid including colloidal particles; introducing carrier particles into the colloid, the carrier particles generally larger than the colloidal particles; and applying ultrasonic energy to both the colloid and the carrier particles to cause the colloidal particles to agglomerate with the carrier particles.

Advantages of the present invention include cost effective and efficient filtration of small particles from aerosols, suspensions, emulsions, bubbles in a liquid, or any other suitable colloid. In certain applications this can increase personal safety for humans working in association with systems that generate such aerosols, and/or decrease environmental impact as a larger proportion of small particles can be removed. According to certain embodiments, diesel machinery can be more safely operated in areas without good ventilation due to improved filtration of diesel particulate from the machinery.

FIG. 1 illustrates a front perspective view of a particulate agglomeration system 100 for a ventilation system, according to an embodiment of the present invention.

The particulate agglomeration system 100 includes an air inlet 105, comprising an inlet filter 110, for receiving and pre-filtering fumes, which can comprise air and other gases. The inlet-filter 1 0 is for removing large particles or objects that otherwise may clog the particulate agglomeration system 100. Examples of objects filtered by the inlet-filter 110 can include leaves and other debris.

The particulate agglomeration system 100 further includes a first carrier particle injection feeder 115, a second carrier particle injection feeder 120 and an acoustic chamber 125. The first and second carrier particle injection feeders 115, 120 are used to inject carrier particles to be mixed with the fumes prior to acoustic agglomeration in the acoustic chamber 125.

The first carrier particle injection feeder 115 is used to inject carrier particles substantially between 20μηι and 40pm in diameter, and the second carrier particle injection feeder 120 is used to inject carrier particles substantially between 1pm and 30pm in diameter. The carrier particles are generally larger than the particles of the fumes. Thus, while the fumes may contain large particles, the fumes contain a significant number of small particles to which the system 100 targets. The agglomerated particles are, due to their size, easier to remove than the small particles of the fumes.

The acoustic chamber 125 comprises an ultrasonic transducer (not shown), which is described in further detail below. The ultrasonic transducer provides an ultrasonic field to the fumes and canier particles, causing particles of the fumes to agglomerate with the carrier particles.

The ultrasonic field forces smaller exhaust particles to move at a faster rate than the larger carrier particles. This results in collisions between the smaller particles of the fumes and the larger carrier particles, which in turn form large agglomerated particles.

The ultrasonic transducer is controlled and powered by an amplifier 130 that regulates a frequency of vibration of the ultrasonic transducer. Furthermore, the ultrasonic transducer is cooled by coolant that is stored in a coolant bath 135, and pumped around a shaft of the ultrasonic transducer. The coolant is used to maintain the ultrasonic transducer at a constant temperature when a temperature of the fumes varies. In addition, the cooling system is able to prevent an increase in temperature of the ultrasonic transducer caused by vibration of the transducer head. Accordingly, the coolant can also prevent damage to the ultrasonic transducer caused by overheating of the ultrasonic transducer.

The agglomerated particles then enter a filter chamber 140, which is used to capture and collect the agglomerated particles, while letting a remainder of the fumes pass through.

The particulate agglomeration system 100 further includes an axial fan 145, configured to draw the fumes from the air inlet 105, through the system 100, to an outlet 150. However, as will be readily understood by the skilled addressee, any suitable means for forcing flow of fumes through the particulate agglomeration system 100 can be used, including creating a pressure differential between the inlet 105 and outlet 150 of the particulate agglomeration system 100.

FIG. 2 illustrates an enlarged cut-away view of the acoustic chamber 125 of the system 100, according to an embodiment of the present invention.

The acoustic chamber 125 includes an ultrasonic transducer 205, a first sampling tube 210 and a second sampling tube 215. The first sampling tube 210 is used to collect fume samples prior to ultrasonic treatment by the ultrasonic transducer 205, and the second sampling tube 215 is used to collect fume samples subsequent to treatment by the ultrasonic transducer 205.

The first sampling tube 210 is placed before the ultrasonic transducer 205 with respect to a flow of fumes from inlet 105 to the outlet 150, and includes a first plurality of holes 220 that are directed away from the ultrasonic transducer 205. The second sampling tube 215 is placed after the ultrasonic transducer 205 with respect to the flow of fumes, and includes a second plurality of holes 225 that are directed towards the ultrasonic transducer 205. This arrangement ensures that samples collected by the first sampling tube 210 are generally samples that have not been treated by the ultrasonic transducer 205, and samples collected by the second sampling tube 215 are generally samples that have been treated by the ultrasonic transducer 205.

The coolant is pumped to the ultrasonic transducer 205 by a coolant pump 230. According to certain embodiments, the coolant pump 230 is automatically controlled to ensure a constant temperature of the ultrasonic transducer 205. In other words, as the temperature of the ultrasonic transducer 205 increases, a flow rate of the coolant pump 230 can also be increased.

FIG. 3 illustrates a front view of the system 100, FIG. 4 illustrates a top view of the system 100, and FIG. 5 illustrates a left side view of the system 100. As best illustrated by FIG. 3, the first and second carrier particle injection feeders 115, 120 extend approximately half way into a mixing chamber 305, which in use results in the carrier particles being mixed into a central portion of the mixing chamber 305. The ultrasonic transducer 205 is located in a lower portion of the acoustic chamber 125, which enables the ultrasonic transducer 205 to apply acoustic energy to a substantial portion of the fume mixture.

The ultrasonic transducer 205 is configured for operation perpendicular to the flow of fumes and carrier particles. This enables high acoustic intensity across the entire flow of particles, as the acoustic energy dissipates quickly with respect to distance travelled.

The particle agglomeration system 100 further includes a transducer head assembly 310, for receiving and providing coolant to the ultrasonic transducer 205. The transducer head assembly 310 includes a coolant jacket (not shown), for surrounding a shaft of the ultrasonic transducer 205 with coolant, thus enabling heat to dissipate from the ultrasonic transducer 205 into the coolant.

As best illustrated by FIG. 4 and FIG. 5, the filter chamber 140 comprises a plurality of vertically extending filter elements 405, for performing mechanical filtration of the agglomerated fumes.

While the particulate agglomeration system 100 is described with reference to a ventilation system, the particulate agglomeration system 100 can be easily modified for use with any type of colloid such as an aerosol, including diesel exhaust fumes, air or other gases that contain dust, paint particles or other fine solid or liquid particles, or water or other liquid containing impurities, such as impurities included in a suspension or emulsion.

A single ultrasonic transducer 205 is illustrated in the system 100, however according to alternative embodiments, several ultrasonic transducers 205 can be used. The several ultrasonic transducers 205 can be placed in series along a length of the acoustic chamber 125, in parallel along a width of the acoustic chamber 125 or form a combination thereof. Similarly, the ultrasonic transducers 205 can have identical operation, or be set to different frequencies or modulations.

As discussed, agglomeration of the fumes with the carrier particles makes the filtering process more efficient, as particles are of a larger size and mass. Accordingly, simpler and/or more robust filtration methods can be applied.

FIG. 6 illustrates a Scanning Electron Microscopy (SEM) image 600 of a carrier particle 605 on which a plurality of dust particles 610 have agglomerated.

The carrier particle 605 is approximately 35μηη in diameter, and the dust particles 610 vary in size from approximately 500nm to greater than 3pm.

The agglomerated particles were generated by applying an ultrasonic frequency of 20 kHz and a sound pressure level of 160 dB in an acoustic chamber containing a mixture of carrier particles 605 and dust 610.

The ultrasonic frequency applied to the colloid is advantageously greater than 10 kHz. However, it appears that frequencies greater than 20kHz are more efficient.

FIG. 7a illustrates a Scanning Electron Microscopy (SEM) image

700 of a carrier particle 705 on which a plurality of DPM particles 710 have agglomerated. FIG. 7b illustrates an enlarged view of portion 700a.

The carrier particle 705 is approximately 25pm in diameter, and the DPM particles 710 vary in size, but are generally less than 1pm.

Advantageously, a substantial portion of the carrier particles 705 are larger than 20pm long. Similarly, the carrier particles are advantageously on average at least 10 times larger than the colloidal DPM particles 710. This enables the DPM particles 710, after agglomeration, to be filtered using significantly coarser filtration techniques than if agglomeration had not taken place. FIG. 8 illustrates a Scanning Electron Microscopy (SEM) image 800 of a solid carrier particle 805 on which a plurality of liquid DPM particles 810 have agglomerated.

The carrier particle 805 is elongate in shape, approximately 40pm in length and 20 pm in width. The liquid DPM particles 810 vary in size, but are generally less than 3 m .

The carrier particles 605, 705 and 805 illustrated in FIGs. 6-8 describe examples of carrier particles that can be used with the system 100. The system 100, however, can be used with any suitable combination of carrier particles, colloidal particles and transport medium. The carrier particles and colloidal particles can each be solid, liquid or gas, and the transport medium can be liquid or gas.

A further illustrative example of use of the present invention includes de-gasification of liquids in which larger gas bubbles are used as carrier particles, the larger gas bubbles used to agglomerate with smaller micro-gas bubbles. Yet a further illustrative system of the present invention comprises an ultrasonic dryer, wherein solid or liquid carrier particles are introduced into a misty stream of smaller liquid particles, wherein the smaller liquid particles agglomerate with the carrier particles, and are thus removed.

FIG. 9 illustrates a schematic view of a processing module 900 of the system 100, according to an embodiment of the present invention.

The processing module 900 includes a processor 905, a memory 910 coupled to the processor 905, and a plurality of data interface ports 915. The amplifier 130 of the system 100 can, for example, include the processing module 900, or be connected to and controlled by the processing module 900.

The memory 910 includes instruction code executable by the processor 905 for controlling the system 100. For example, the instruction code can include instructions for controlling a frequency of the ultrasonic transducer and/or a flow rate of the carrier particles. The plurality of data interface ports 915 can be connected to sensors (not shown). The sensors can include temperature sensors, for sensing a temperature of the colloid, flow rate sensors, for sensing a flow rate of the colloid, and sensors for detecting a density of the colloid. The instruction code can then consider the input from the sensors when controlling the system 00.

In particular, the plurality of data interface ports 915 can be connected to a speed sensor of the fan 145, a mass flow rate sensor of the first carrier particle injection feeder 115, a mass flow rate sensor for the second carrier particle injection feeder 120, a sensor to measure a frequency and/or amplitude of the amplifier 130, and/or a flow rate sensor of the coolant pump 230.

Furthermore, the plurality of data interface ports 915 can be connected to sensors for measuring samples of the first and second sampling tubes 210, 215.

The system 100 can then introduce carrier particles at a rate according to the flow rate and/or density of the colloid, for example, or adjust other aspects of the system 100. Specifically, the system 100 can control a speed of the fan 145, or any other suitable aspect of the system 100 using a data interface port of the plurality of data interface ports 915.

According to certain embodiments (not shown), the system 100 includes means for adjusting a temperature of the colloid. This can, for example, comprise a heating element for heating the colloid, a heat sink or other heat transfer means for cooling the colloid, and or means to mix a hot or cold fluid with the colloid.

In summary, advantages of the present invention include cost effective and efficient filtration of small particles from aerosols, suspensions, emulsions, bubbles in a liquid, or any other suitable colloid. In certain, applications this can increase personal safety for humans working in association with systems that generate such aerosols, and/or decrease environmental impact a larger proportion of small particles can be removed. According to certain embodiments, diesel machinery can be more safely operated in areas without good ventilation due to improved filtration of diesel particulate from the machinery.

The above description of various embodiments of the present invention is provided for purposes of description to one of ordinary skill in the related art. It is not intended to be exhaustive or to limit the invention to a single disclosed embodiment. As mentioned above, numerous alternatives and variations to the present invention will be apparent to those skilled in the art of the above teaching. Accordingly, while some alternative embodiments have been discussed specifically, other embodiments will be apparent or relatively easily developed by those of ordinary skill in the art. Accordingly, this patent specification is intended to embrace all alternatives, modifications and variations of the present invention that have been discussed herein, and other embodiments that fall within the spirit and scope of the above described invention.

Claims

1. A method of particulate matter agglomeration, the method including:

receiving a colloid including colloidal particles;

2. The method of claim 1 , wherein the colloid comprises a mixture of small particles of one substance distributed throughout another substance.

3. The method of claim 1 , wherein the colloid is an aerosol.

4. The method of claim 3, wherein the aerosol is a liquid aerosol.

5. The method of claim 3, wherein the aerosol includes diesel exhaust fumes.

6. The method of claim 1 , wherein the colloid is a suspension.

7. The method of claim 1 , wherein the colloid is an emulsion.

8. The method of claim 1 , wherein the colloid comprises gaseous particles in a liquid.

9. The method of claim 1 , wherein the ultrasonic energy is applied at a frequency greater than 10kHz.

10. The method of claim 1 , wherein the ultrasonic energy is applied at a frequency greater than 20kHz.

11. The method of claim 1 , wherein the method further comprises removing at least part of the agglomerated particles by filtration.

12. The method of claim 11 , wherein the filtration comprises mechanical filtration.

13. The method of claim 1 , wherein the method further comprises adjusting a temperature of the colloid.

14. The method of claim 1 , wherein a portion of the carrier particles are larger than 20 m long.

15. The method of claim 1 , wherein the carrier particles are on average at least 10 times larger than the colloidal particles.

16. The method of claim 1 , wherein the method further comprises adjusting a flow of the carrier particles based upon at least one of: a temperature of the colloid; a flow rate of the colloid and a density of the colloid.

17 A particle matter agglomeration system including:

a second input for receiving carrier particles, wherein the carrier particles are on average larger than the colloidal particles;

an acoustic chamber, coupled to the first input and the second input; and an ultrasonic transducer, for applying ultrasonic energy to both the colloid and the carrier particles inside the acoustic chamber to cause the colloidal particles to agglomerate with the carrier particles.

18. The system of claim 17, wherein the ultrasonic transducer comprises a piezoelectric transducer.

19. The system of claim 17, further comprising a filter positioned downstream of the acoustic chamber for removing the agglomerated colloidal particles.

20. The system of claim 17, further comprising a control module, for controlling operation of at least one of: the first input, the second input, and the ultrasonic transducer; and wherein the control module includes at least one of: a temperature sensor for measuring a temperature of the colloid, a flow rate sensor for measuring a flow rate through at least one of the first input and the second input, and a sensor for measuring a density of the colloid.