WO2005043128A1

WO2005043128A1 - Sampling particulate material

Info

Publication number: WO2005043128A1
Application number: PCT/NZ2004/000279
Authority: WO
Inventors: Brent Waterhouse
Original assignee: Avalon Engineering Limited
Priority date: 2003-11-03
Filing date: 2004-11-03
Publication date: 2005-05-12

Abstract

A method of sampling a particulate material includes the steps of: I.Reducing a pressure of a fluid in a receiving vessel (4) to below a pressure of a fluid in a source of said particulate material (2); II. Opening a conduit (3) between the receiving vessel and the particulate material such that a fluid in the source of particulate material moves through the conduit towards the receiving vessel, thereby conveying a portion of the particulate material towards the receiving vessel; III. Repeating steps 1) and 2), if required, until a sample having a required amount of particulate material is held within the receiving vessel; and IV. Conveying the sample from the receiving vessel to a sample receptacle (11).

Description

SAMPLING PARTICULATE MATERIAL

TECHNICAL FIELD

The present invention relates to material sampling systems and methods, and in particular, but not exclusively, to a system and method for sampling a particulate material.

BACKGROUND ART

In the food powder industries, there is often a requirement to take samples of the powder at various stages throughout the manufacturing and packing process. The samples may be tested for qualities such as purity, contamination, mechanical properties and density.

Current technologies for taking samples generally fall into 3 categories:

1. Manual sampling - where a person takes a sample by hand from the desired sampling point.

2. Automatic sampling, auger style - where a screw auger is used to extract the powder automatically from the sampling point.

3. Automatic sampling, push/pull style - where a scoop type device is inserted into the powder to extract the powder automatically from the sampling point.

In each of these methods, the sample is generally put in an open-mouth plastic bag in which it is manually transported to a testing facility.

Each of these systems have various disadvantages including;

^■ Potential for contamination of the powder during sampling. ^■ The use of moving parts which could end up in the powder from which the sample is to be taken if there is a malfunction. ■ The length of time required to clean the sampling system, lowering the rate at which samples can be taken. ■ Lack of consistency of sample size. ^■ Potential to cause significant damage to the sample powder during sample taking due to damaging of the powder by the sampling device. ^■ High levels of operator input may be required.

OBJECT OF THE INVENTION

It is an object of a preferred embodiment of the present invention to provide a particulate material sampling system and/or a method of sampling a particulate material, which will overcome or at least ameliorate problems with such systems and/or methods at present, or which will at least provide the public with a useful choice.

Further objects will become apparent from the following description, which is given by way of example only.

DISCLOSURE OF THE INVENTION

According to one aspect of the present invention there is provided a method of sampling a particulate material, the method including the following steps, in order: i) Reducing a pressure of a fluid in a receiving vessel to below a pressure of a fluid in a source of said particulate material; ii) Opening a conduit between said receiving vessel and said particulate material such that said fluid in said source of particulate material moves through said conduit towards said receiving vessel, thereby conveying a portion of said particulate material towards said receiving vessel; iii) Repeating steps ii) and iii), if required, until a sample having a required amount of particulate material is held within said receiving vessel; and iv) Conveying said sample from said receiving vessel to a sample receptacle.

Preferably, said step iv) may include the steps of increasing said pressure of said fluid in said receiving vessel to above a pressure of a fluid in said sample receptacle and opening a conduit between said receiving vessel and said sample receptacle such that said fluid in said receiving vessel moves towards said sample receptacle, thereby conveying said sample to said sample receptacle. Preferably, the method may further include the steps of; v) Increasing said pressure in said receiving vessel to greater than the pressure of said fluid in said source of particulate material; vi) Opening said conduit between said receiving vessel and said particulate material such that said fluid in said receiving vessel moves through said conduit towards said source of particulate material, thereby conveying a remainder of said particulate material, if any, from said receiving vessel, back to said source of particulate material and substantially removing a residue of said portion of particulate material, if present, from said conduit.

Preferably, said fluid in said receiving vessel may be air or an inert gas.

Preferably, said particulate material may be a food powder.

According to a second aspect of the present invention there is provided a particulate material sampling system which utilises the method of any of five immediately preceding paragraphs. According to a third aspect of the present invention there is provided a particulate material sampling system including a receiving vessel provided with first conduit means connectable to a source of particulate material to be sampled, second conduit means connectable to a sample receptacle means, each said conduit means provided with valve means for sealing the respective conduit, pressure varying means for selectively varying a pressure of a fluid within said receiving vessel between a first pressure which is below a pressure of a fluid surrounding said particulate material to be sampled and a second pressure which is equal to or greater than a pressure of a fluid within said sample receptacle, and means for controlling said valve means and said pressure varying means such that, in use, a sample of said particulate material is conveyed from said particulate material source to said sample receptacle means.

Preferably, said pressure varying means may include a compressed air/inert gas source. Preferably, said pressure varying means may include a vacuum source. Preferably, said means for controlling said valve means and said pressure varying means may be an automated control means.

Preferably, in use, said system may perform the method of any one or more of the paragraphs above.

According to a further aspect of the present invention a particulate material sampling system is substantially as herein described with reference to the accompanying figure.

According to a still further aspect of the present invention a method of sampling a particulate material is substantially as herein described.

Further aspects of the invention, which should be considered in all its novel aspects, will become apparent from the following description given by way of example of possible embodiments of the invention.

BRIEF DESCRIPTION OF THE FIGURES Figure 1 : Shows, very diagrammatically, a sampling system according to a preferred embodiment of the present invention.

BEST MODE FOR PERFORMING THE INVENTION Referring first to Figure 1 , a particulate material sampling system according to a preferred embodiment of the present invention includes a main vessel 1 providing a source of the particulate material 2 to be sampled. Examples of suitable particulate materials include milk powder, coffee powder, whey protein concentrate powder, non- dairy creamer or food additive powders and other food powders. The main vessel 1 may be, for example, a storage vessel, or a chute or funnel from which the particulate material

2 is deposited into a container (not shown) such as a flexible package.

A first conduit 3 is provided between the main vessel 1 and a receiving vessel 4. The first conduit 3 is provided with a first valve means 5 between the receiving vessel 4 and main vessel 1 , the first valve means 5 preferably located towards the receiving vessel end of the conduit 3. The receiving vessel 4, which is a pressure vessel having any suitable shape and configuration, is provided with pressure varying means to vary the pressure of a fluid within the receiving vessel 4, the fluid typically being air. Those skilled in the art will appreciate that other suitable fluids, both gas and liquids, may be used depending on the particulate material 2 which is being sampled. Those skilled in the art will further appreciate that in some embodiments the particulate material 2 may be stored in an inert gas atmosphere, and all reference herein to fluids or air may be read as references to inert gas unless the context clearly requires otherwise.

The pressure varying means may include a source of compressed air 6 and a vacuum source 7, vacuum being herein defined as a pressure lower than that in the main vessel 1. The compressed air source 6 and vacuum source 7 may be regulated by a compressed air valve means 8 and vacuum source valve means 9 respectively. The pressure within the receiving vessel 4 may be controlled by varying the pressure of the compressed air source 6 and vacuum source 7 while keeping the opening times of the compressed air valve means 8 and vacuum source valve means 9 constant, although a more preferable method is to hold the pressures of the sources 6, 7 constant and vary the opening times of the valves 8, 9.

A second conduit 10 leads from the receiving vessel 4 to a sample receptacle 11 and is provided with a second valve means 14. One or both of the second conduit 10 and sample receptacle 11 may be provided with a vent 12, which may include a filter means 13.

To obtain a sample of the particulate material 2 from the main vessel 1 , the first valve means 5, second valve means 14, and compressed air valve means 8 are closed and the vacuum source valve means 9 is opened for a predetermined time, allowing the vacuum source 7 to reduce the pressure of the fluid within the receiving vessel 4 to below that of the fluid surrounding the particulate material 2 in the main vessel 1. The fluid in the main vessel 1 is also typically air, usually at substantially ambient pressure, although as mentioned above, the fluid in the main vessel 1 may be an inert gas.

The vacuum source valve means 9 is then closed and the first valve means 5 opened for a predetermined time. This allows air from the main vessel 1 , which is at higher pressure than the air in the receiving vessel 4, to flow down the first conduit 3 to the receiving vessel 4, carrying a portion of the particulate material 2 with it as it flows.

If necessary this process may be repeated, until a sample having a required amount of particulate material is held within the receiving vessel 4. In embodiments requiring repetition of the above step, the vacuum source 7 must be placed in a position where the particulate material cannot enter it while the vacuum source valve means 9 is open, for example at the top of the receiving vessel 4. A filter (not shown) may additionally or alternatively be used.

When a sample having a required amount of particulate material 2 is held within the receiving vessel 4 the first valve means 5 is closed and the sample of the material held in the receiving vessel 4 may be conveyed by suitable means to a sample receptacle 11 , for example a bottle, jar or more typically a plastic bag.

In a preferred embodiment the sample may be conveyed by opening the compressed air valve means 8 for a predetermined time and increasing the pressure of the fluid within the receiving vessel 4 to above that of the pressure of the fluid in the sample receptacle 11 , and then closing the compressed air valve means 8 and opening the second valve means 14 to allow the fluid in the receiving vessel 4 to flow towards the sample receptacle 11 , thereby conveying the sample of particulate material into the sample receptacle 11. The applicant has surprisingly found that the size of the sample present in the receiving vessel 4 is highly repeatable, although additional controls on the sample size, such as weighing the sample, may also be used if additional control, or verification, of the sample size is required.

The vent 12, if used, prevents overpressurisation of the sample receptacle 11 and a filter means 13 prevents the escape of material through the vent means 12. In a preferred embodiment the sample receptacle is attached to the second conduit with a sufficiently tight seal to substantially prevent the escape of particles from the sample, although the seal may not be completely air tight.

After the sample has been deposited into the sample receptacle 11 the second valve means 14 may be closed and the compressed air valve means 8 opened to again pressurize the fluid in the receiving vessel 4 to a pressure greater than that in the main vessel 1. Once the compressed air valve means 8 has been open for a sufficient time for a suitable pressure to have been reached within the receiving vessel 4, the compressed air valve means 8 may be closed and the first valve means 5 opened to allow the fluid in the receiving vessel 4 to blow back into the main vessel 1 , thereby purging the receiving vessel 4 of any particulate material remaining, and simultaneously purging the first conduit

3 of any residue of particulate material 2 which may be present. This step may be repeated as necessary. In some embodiments the compressed air valve means 8 may be left open when the first valve means 5 is opened to assist with the purging step. The sample receptacle 11 may then be removed for testing of the particulate, and may be replaced by a fresh sample receptacle 1 1.

The system is then ready to take the next sample. Typically the timing of the sampling may be matched with the filling of a storage vessel (not shown) from the main vessel 1 , so that there are one or more sample receptacles 1 1 which contain material 2 with properties which are representative of the material 2 in each particular storage vessel.

In one embodiment used for milk powder the first conduit 3 was 600mm long and 25mm in diameter and substantially horizontally orientated and the second conduit 10 was

185mm long and 50mm in diameter and substantially vertically orientated.

The receiving vessel 4 was lowered to a pressure of around -4psi (gauge) to draw the milk powder into the receiving vessel 4, the fluid surrounding the powder in the main vessel 1 being at substantially atmospheric pressure. The procedure was repeated twice to convey the required 8 to 10g size sample to the receiving vessel 4.

The receiving vessel 4 was then raised to a pressure of around 2psi (gauge) and the second valve means 14 opened for around 1s to allow the sample to pass from the receiving vessel 4 to the sample receptacle 11.

The receiving vessel 4 was then pressurized to around 4psi (gauge) for the purging cycle. Those skilled in the art will appreciate that the present invention has many advantages over the systems and methods of the prior art. As there are no moving parts other than the valves in contact with the material 2, the potential for contamination of the material 2 is reduced. The contamination risk is also reduced by the purging of the first conduit 3 and receiving vessel 4 between the taking of each sample.

The rate or frequency with which samples can be taken is increased by the fact that an operator does not need to perform additional cleaning operations between each sample, except for occasional routine maintenance.

The consistency or repeatability of the sample size may also be improved over many sampling methods of the prior art, and the physical properties of the sample may be more representative of the bulk material than samples taken by prior art methods, as there is a minimum of mechanical interaction between the sampling system and the particulate material 2 such as might damage or alter the properties of the sample.

As will also be appreciated by those skilled in the art, the system may be readily automated by provision of suitable control means (not shown) to control the switching of the valves and the changing of the sample receptacle 11.

Although the present invention has been described with reference to sampling food powder, those skilled in the art will appreciate that other embodiments may be suitable for sampling other particulate materials. Where in the foregoing description, reference has been made to specific components or integers of the invention having known equivalents, then such equivalents are herein incorporated as if individually set forth.

Although this invention has been described by way of example and with reference to possible embodiments thereof, it is to be understood that modifications or improvements may be made thereto without departing from the scope of the appended claims.

Claims

CLAIMS: . A method of sampling a particulate material, the method including the following steps, in order: i) Reducing a pressure of a fluid in a receiving vessel to below a pressure of a fluid in a source of said particulate material; ii) Opening a conduit between said receiving vessel and said particulate material such that said fluid in said source of particulate material moves through said conduit towards said receiving vessel, thereby conveying a portion of said particulate material towards said receiving vessel; iii) Repeating steps ii) and iii), if required, until a sample having a required amount of particulate material is held within said receiving vessel; and iv) Conveying said sample from said receiving vessel to a sample receptacle.

2. The method of claim 1 wherein step iv) includes the steps of increasing said pressure of said fluid in said receiving vessel to above a pressure of a fluid in said sample receptacle and opening a conduit between said receiving vessel and said sample receptacle such that said fluid in said receiving vessel moves towards said sample receptacle, thereby conveying said sample to said sample receptacle.

3. The method of claims 1 or 2 including the further steps of; v) Increasing said pressure in said receiving vessel to greater than the pressure of said fluid in said source of particulate material; vi) Opening said conduit between said receiving vessel and said particulate material such that said fluid in said receiving vessel moves through said conduit towards said source of particulate material, thereby conveying a remainder of said particulate material, if any, from said receiving vessel, back to said source of particulate material and substantially removing a residue of said portion of particulate material, if present, from said conduit.

4. The method of any one of claims 1 to 3 wherein the fluid in said receiving vessel is air or an inert gas.

The method of any one of the previous claims wherein the particulate material is a food powder.

6. A particulate material sampling system which utilises the method of any one of claims 1 to 5.

7. A particulate material sampling system including a receiving vessel provided with first conduit means connectable to a source of particulate material to be sampled, second conduit means connectable to a sample receptacle means, each said conduit means provided with valve means for sealing the respective conduit, the system including pressure varying means for selectively varying a pressure of a fluid within said receiving vessel between a first pressure which is below a pressure of a fluid surrounding said particulate material to be sampled and a second pressure which is equal to or greater than a pressure of a fluid within said sample receptacle, and means for controlling said valve means and said pressure varying means such that, in use, a sample of said particulate material is conveyed from said particulate material source to said sample receptacle means.

8. The particulate material sampling system of claim 7 wherein said pressure varying means includes a compressed air/inert gas source.

9. The particulate material sampling system of claim 7 or 8 wherein said pressure varying means includes a vacuum source.

10. The particulate material sampling system of any one of claims 7 to 9 wherein said means for controlling said valve means and said pressure varying means is an automated control means.

11. The particulate material sampling system of any one of claims 7 to 10 wherein, in use, said system performs the method of any one of claims 1 to 5.

12. A particulate material sampling system is substantially as herein described with reference to the accompanying figure.

13. A method of sampling a particulate material substantially as herein described.