AU2006200714B2 - Storage vessel vent means, storage system including said vent means, and method of venting a storage vessel - Google Patents

Abstract

A storage vessel vent means including a housing having at least one inlet and an outlet, a fan and a first valve means provided within the housing, at least one filter means for 5 filtering a fluid supplied to said fan and said first valve means from said at least one inlet, wherein said first valve means is adapted to allow at least a portion of said fluid to flow from said filter means to said outlet without passing through said fan if a pressure of said fluid between said filter means and said fan exceeds a pressure of said fluid at said outlet by more than a required amount. CLj

Description

AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): NDA Engineering Limited Invention Title: STORAGE VESSEL VENT MEANS, STORAGE SYSTEM INCLUDING SAID VENT MEANS, AND METHOD OF VENTING A STORAGE VESSEL The following statement is a full description of this invention, including the best method of performing it known to me/us: 1 1A STORAGE VESSEL VENT MEANS, STORAGE SYSTEM INCLUDING SAID VENT MEANS, AND METHOD OF VENTING A STORAGE VESSEL TECHNICAL FIELD 5 The present invention relates to means for venting storage vessels such as milk silos, and in particular, but not exclusively, to vent means which are suitable for use in hygienic silos having "clean in place" or "CIP" installations. 10 BACKGROUND Food quality storage vessels such as milk silos or tanks are often cleaned by "clean in place" systems whereby the interior of the silo is sprayed with a hot liquid, sometimes followed by a cold liquid, during cleaning. 15 The hot and cold sprays cause changes in the temperature, and therefore pressure, of the air within the silo. The pressure variation may be sufficiently large that the silo must be vented to prevent deformation and/or failure. 20 At present, the air introduced into such silos is typically taken from a hygienic area such as a factory processing area. In some installations this may be inconvenient, difficult and/or impractical. A further problem with such silos is the possibility of the pressure inside the silo 25 varying relative to the pressure of the atmosphere outside the silo during filling or emptying operations. In extreme cases this pressure differential may cause failure of the silo. 30 OBJECT OF THE INVENTION It is an object of a preferred embodiment of the invention to provide a storage vessel vent means and/or a ventilated storage system and/or a method of venting a storage vessel which will overcome or ameliorate problems with such vent means and/or 35 storage systems and/or methods at present, or at least one which will provide the public with a useful choice.

-2 Other objects of the present invention may become apparent from the following description, which is given by way of example only. 5 SUMMARY OF THE INVENTION According to one aspect of the present invention there is provided a storage vessel vent means including a housing having at least one inlet and an outlet, a fan and a first valve means provided within the housing, at least one filter means for filtering a fluid 10 supplied to said fan and said first valve means from said at least one inlet, wherein said first valve means is adapted to allow at least a portion of said fluid to flow from said filter means to said outlet without passing through said fan if a pressure of said fluid between said filter means and said fan exceeds a pressure of said fluid at said outlet by more than a required amount. 15 Preferably, said vent means may include a conduit having an inlet connectable to said outlet of said housing. Preferably, said conduit may be provided with second valve means adapted to 20 substantially prevent said fluid from flowing from an outlet of said conduit to said outlet of said housing. Preferably, said conduit may be provided with a third valve means adapted to allow fluid to vent from between said second valve means and said outlet of said conduit if 25 a pressure of said fluid at said conduit outlet exceeds a first preselected pressure. According to a second aspect of the present invention there is provided a ventilated storage system including a storage vessel in fluid communication with the storage vessel vent means of any of the four immediately preceding paragraphs. 30 Preferably, said storage system may include a fourth valve means in fluid communication with said storage vessel and adapted to allow fluid to vent from an interior of said storage vessel to an exterior of said storage vessel if a pressure of said fluid within said storage vessel exceeds a second preselected pressure. 35 Preferably, said second preselected pressure may be less than said first -3 preselected pressure. According to a third aspect of the present invention a method of venting a storage vessel includes bringing said storage vessel into fluid communication with an outlet of a 5 storage vessel vent means which includes; a housing having at least one inlet and said outlet, a fan and a first valve means provided within the housing, at least one filter means for filtering a fluid supplied to said fan and said valve means from said at least one inlet, wherein said valve means is adapted to allow at least a portion of said fluid to flow from said filter means to said outlet without passing through said fan if a pressure of said fluid 10 between said filter means and said fan exceeds a pressure of said fluid at said outlet by more than required amount. According to a fourth aspect of the present invention a storage vessel vent means and/or a ventilated storage system and/or a method of venting a storage vessel is 15 substantially as herein described with reference to the accompanying drawings. 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. 20 BRIEF DESCRIPTION OF THE FIGURES Figure 1: Is a diagrammatic cross-section side view of a storage vessel vent means 25 according to one possible embodiment of the present invention. Figure 2: Is a diagrammatic plan view of the storage vessel vent means of Figure 1, with the filter elements, fan and valves shown in hidden detail. 30 Figure 3: Is a diagrammatic cross-section side view of a ventilated storage system according to one possible embodiment of the present invention.

-4 BEST MODE FOR PERFORMING THE INVENTION The term "fluid" is used in this specification to denote a substantially gaseous fluid, for example air. 5 Referring first to Figures 1 and 2, a storage vessel vent means according to one possible embodiment of the present invention is generally referenced 100. The vent means 100 includes a housing 1 provided with at least one inlet 2. 10 Preferably two inlets 2 are provided on two opposite sides 3 of the housing 1, each inlet 2 provided with a filter element 4 to filter the air entering the housing 1. A fan or blower 5 is provided within the housing 1 to blow air from the inlets 2 to the outlet 6. 15 A one way valve 7 is provided within the housing 1 in parallel with the fan 5. The one way valve 7 is adapted to allow filtered air to flow from the space between the filters 4 and fan 5 to the outlet 6 if the pressure of the air between the filters 4 and fan 5 exceeds the pressure of the air at the outlet 6 by more than a required amount. 20 Referring next to Figure 3, a ventilated storage system is generally referenced 200. In the example illustrated the vent means 101 includes a vent means 100 as described above, with a conduit 10 connected to the outlet 6 of the housing 1. The conduit 10 has an outlet 11 in fluid communication with the headspace 12 of a storage 25 vessel, for example a milk silo 13. The term "headspace" is used herein to denote the interior volume of a storage vessel between the contents of the vessel and the top of the vessel. If the vessel is empty then the term "headspace" refers to the entire interior volume of the vessel. 30 The conduit 10 may be provided with a second one way valve means 14 adapted to prevent air from flowing from the outlet 11 of the conduit 10 to the housing outlet 6. This non return valve 14 is preferably substantially adjacent the conduit outlet 11. 35 The vent means 101 may also be provided with a third valve means 15 adapted to act as a pressure relief valve, allowing air to vent from the interior of the silo 13 if the -5 pressure of the air at the conduit outlet 11, which is substantially equal to the pressure of the air in the headspace of the silo 13, exceeds a preselected pressure. The pressure relief means 15 is preferably set to vent at a pressure below the safe operating pressure of the silo 13. In one embodiment, when used with a large milk silo, the third valve means 5 15 was set to vent at approximately 1.5kPa (gauge). The silo 13 may also be provided with a second vent means, generally referenced 300, which is preferably configured as an overflow. The overflow 300 may drain to another hygienic vessel, or to the atmosphere. 10 If the overflow 300 drains to the atmosphere then it is preferably provided with flow limiting means, for example a fourth one way valve or a water trap 16, which prevents flow through the second vent means 300 unless the pressure within the silo 13 is greater than a second preselected pressure. In this way unfiltered air is prevented from entering the 15 silo through the overflow 300. Under normal operating conditions any excess pressure is vented by the third one way valve 15, rather than through the overflow 300. 20 The vent means 101 operates as follows: Normal operation During normal operation the fan 5 operates to keep the atmosphere within the headspace 12 of the silo 13 at a substantially constant positive pressure, for example around 0.8kPa (gauge). 25 Air displacement due to filling of the silo 13 with milk is vented through the one way valve 15. When the silo 13 is emptied, air is supplied to the headspace by the vent means 101 in order to keep the required pressure in the headspace. The fan 5 is preferably selected to have a sufficient flow rate to keep the pressure in the headspace 12 positive during emptying of the silo 13.

-6 CIP Cold to Hot During clean in place cleaning, the silo 13 is emptied of milk and a hot cleaning liquid is sprayed into the interior. The heating effect of the hot liquid increases the pressure of the air in the silo 13, which must be vented in order to prevent damage. 5 During this phase air is primarily vented through the pressure relief valve means 15. The non-return one way valve means 14 closes, preventing air from flowing towards the housing 1. CIP Hot to COLD During this phase the pressure of the air within the silo 13 may drop below 10 atmospheric pressure, for example to substantially -2kPa (gauge). Filtered air is provided by the fan 5 and, if required, the one way valve 7. All air supplied to the headspace 12 is filtered to ensure that the silo 13 remains sterile. Those skilled in the art will appreciate that the vent means 100, 101 of the present 15 invention allows a storage vessel such as a silo 13 to remain constantly pressurised with clean air during normal operation, and ensures that all air entering the silo 13 during CIP operations has been filtered, without requiring any connection to clean areas of a factory. While the silo 13 has been described as a storage vessel, the term "storage" is to 20 be given a broad interpretation, and may include embodiments in which some processing or reaction of the material occurs within the silo 13. Where in the foregoing description, reference has been made to specific components or integers of the invention having known equivalents, then such equivalents 25 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 spirit or scope of the 30 appended claims. The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that that prior art forms part of the common general knowledge in Australia, or any other country.

Claims (11)

1. A storage vessel vent means including a housing having at least one inlet and an outlet, a fan and a first valve means provided within the housing, at least one filter 5 means for filtering a fluid supplied to said fan and to said first valve means from said at least one inlet, wherein said first valve means is adapted to allow at least a portion of said fluid to flow from said filter means to said outlet without passing through said fan if a pressure of said fluid between said filter means and said fan exceeds a pressure of said fluid at said outlet by more than a required amount. 10

2. The storage vessel vent means of claim 1 including a conduit having an inlet connectable to said outlet of said housing.

3. The storage vessel vent means of claim 2 wherein said conduit is provided with 15 second valve means adapted to substantially prevent said fluid from flowing from an outlet of said conduit to said outlet of said housing.

4. The storage vessel vent means of claim 3 wherein said conduit is provided with a third valve means adapted to allow fluid to vent from between said second valve 20 means and said outlet of said conduit if a pressure of said fluid at said conduit outlet exceeds a first preselected pressure.

5. A ventilated storage system including a storage vessel in fluid communication with the storage vessel vent means of any one of claims 1 to 4. 25

6. The ventilated storage system of claim 5 including a fourth valve means in fluid communication with said storage vessel and adapted to allow fluid to vent from an interior of said storage vessel to an exterior of said storage vessel if a pressure of said fluid within said storage vessel exceeds a second preselected pressure. 30

7. The ventilated storage system of claim 7 wherein said second preselected pressure is greater than said first preselected pressure.

8. A method of venting a storage vessel including bringing said storage vessel into 35 fluid communication with an outlet of a storage vessel vent means which includes a housing having at least one inlet and said outlet, a fan and a first valve means provided within the housing, at least one filter means for filtering a fluid supplied to said fan and said valve means from said at least one inlet, wherein said valve means is adapted to allow at least a portion of said fluid to flow from said filter means to said outlet without passing through said fan if a pressure of said fluid 5 between said filter means and said fan exceeds a pressure of said fluid at said outlet by more than required amount.

9. A storage vessel vent means substantially as herein described with reference to the accompanying drawings. 10

10. A ventilated storage system substantially as herein described with reference to the accompanying drawings.

11. A method of venting a storage vessel substantially as herein described. 15 Dated this day of 2006 NDA ENGINEERING LIMITED 20 By its Patent Attorneys GRIFFITH HACK