An Improved Sparging Assembly and Sparging Method

This application claims priority from Australian Provisional Patent Application No. 2007903073 filed on 7 June 2007, the contents of which are to be taken as incorporated herein by this reference.

The present invention relates to an improved sparging assembly and components thereof. The invention has particular, but not exclusive, application in the wine production industry. The invention also relates to an improved sparging method.

Sparging is the process of dispersing a gas into a liquid. It is commonly used in, for example, the chemical, petrochemical, pharmaceutical and food industries for fermentation and oxidation reactions, synthesis and the manufacture of fine chemicals. Sparging is typically use to change one or more of the parameters of a liquid, either by subtraction or addition of a gas in order to alter the quality and/or shelf life of a product.

When making wine, the level of dissolved oxygen and/or dissolved carbon dioxide in the wine affects the final product. The specification of the wine, its quality and its shelf life may be effected by these levels. Hence, sparging is carried out during the manufacturing process to control these gas levels. It is recognised however that sparging must be carried out with little or no change to the organoleptic properties of the wine. This has proved difficult in the past due to the relatively high gas flow rates of the inert sparging gas used and the low efficiency of existing sparging systems.

If not carried out properly, sparging of wine can remove some of the volatile aromatic compounds that are important to wine quality. This is a particular concern to wine manufacturers.

The present invention seeks to provide an improved sparging assembly and method of sparging.

The discussion of the background to the invention herein is included to explain the context of the invention. This is not to be taken as an admission that any of the material referred to was published, known or part of the common general knowledge as at the priority date of this application.

According to a first aspect of the present invention there is provided a sparging assembly including a body defining a flow path for a liquid to be sparged, an entry port for entry into said body of a sparging gas and means for creating turbulence of the liquid as it flows through the body and contacts said sparging gas.

The first aspect of the present invention recognises that sparging efficiency can be increased by causing turbulence of the liquid during sparging.

In accordance with an embodiment of the first aspect of the invention, the turbulence creating means causes the liquid to adopt a spiral or turbulent flow. The turbulence creating means includes at least one tine arranged to be mounted within said body and located within the flow path of said liquid. The tine is shaped to twist the flow of liquid as it travels along said flow path. Preferably, the flow of liquid is twisted through substantially 180°.

In accordance with another embodiment of the first aspect of the invention, the turbulence creating means is a vortex unit that includes an outer ring, a centre connector and at least one tine. The tine is connected, for example by welding, to an inner face of the outer ring and an outer face of the centre connector. Preferably three tines are included in the vortex unit and they are spaced at 120° from each other around the centre connector. The centre connector is preferably a length of tube.

According to a second aspect of the present invention there is provided a sparging assembly including a body with an inlet for entry of a liquid to be sparged and an outlet for exit of sparged liquid, an entry port for entry of a sparging gas and a gas permeable membrane located within the body, said gas permeable membrane defining at least a part of a pathway along which the liquid flows between said inlet and said outlet so that sparging gas permeating through said membrane forms bubbles that contact with said liquid.

The second aspect of the present invention recognises that in order to achieve improved sparging fine bubble propagation of the sparging gas needs to be established. This provides a higher surface area for effective mass transfer of dissolved oxygen and/or carbon dioxide from the liquid being sparged. By providing a higher surface area of the sparging gas, it is also possible to reduce the flow rate of that gas. This is particularly advantageous when the liquid being sparged is wine, as higher sparging gas flow rates tend to erode the quality of the wine.

It is envisaged that it would be desirous for the bubbles formed at the interface between the liquid and the sparging gas to have a diameter of about 0.01 mm. In one embodiment this may be achieved by using a gas permeable membrane preferably having porosity between 2 and 100 microns, and more preferably about 40 microns.

In accordance with one embodiment of the second aspect of the invention, the gas permeable membrane is arranged to be located within the body so that the liquid passes through a bore of the membrane.

The membrane is preferably made of sintered metal having a porosity of about 40 microns. The metal is preferably stainless steel.

The membrane is preferably located within the body so that a gas flow zone is established between an inner surface portion of the body and an outer periphery of the membrane. The membrane may be a bush.

According to a third aspect of the present invention there is provided a sparging assembly including a body defining a flow path for a liquid to be sparged, an entry port for entry of a sparging gas into said body, means for creating turbulence of the liquid as it flows through the body and a gas permeable membrane located within the body, said membrane defining at least a part of a pathway along which the liquid flows between said inlet and said outlet so that gas permeating through said membrane forms bubbles that contact said liquid.

According to a fourth aspect of the invention there is provided a sparging vortex unit for a sparging assembly, said unit including at least one tine arranged to be located within a body of the sparging assembly, said tine shaped to twist the flow of liquid through substantially 180° as it travels along a flow path within said assembly.

According to a fifth aspect of the invention there is provided a sparging membrane for a sparging assembly, said membrane including a gas permeable bush arranged to be located within a body of a sparging assembly so that the liquid passes through a bore of the bush.

According to a sixth aspect of the invention there is provided a method of method of sparging a liquid including the step of causing said liquid to flow through a sparging assembly according to a first or second aspect of the invention.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 is a schematic of a system for oxygen removal from wine by nitrogen sparging using a sparger assembly in accordance with an embodiment of the invention;

Figure 2 is an assembly cross-sectional view of a sparging assembly in accordance with an embodiment of the invention;

Figure 3 is a cross-sectional view of the inlet connector of the sparging assembly shown in Figure 2;

Figure 4 is a cross-sectional view of the body of the sparging assembly shown in Figure 2;

Figure 5 is a cross-sectional view of the sintered metal bush of the sparging assembly shown in Figure 2;

Figure 6 is a cross-sectional view of the outlet connector of the sparging assembly shown in Figure 2;

Figures 7 and 7A are respective cross-sectional and end views of the nut of the sparging assembly shown in Figure 2; and

Figures 8 and 8A are respective end and side views of vortex unit of the sparging assembly shown in Figure 2.

The present invention has application in a variety of different industries for the sparging of different liquids with different carrier gases. The following description refers to the sparging of wine using the sparging gas (carrier gas) nitrogen. However, it should be understood that the present invention is not limited to such an application.

The embodiment of the sparging assembly described below combines the first and second aspects of the invention. Accordingly, the sparging assembly described includes means for causing turbulence of the liquid during sparging and means for achieving fine bubble propagation of the sparging gas. It should be understand that although it is beneficial to combine both of these elements

into the sparging assembly, the invention is not intended to be restricted to such an arrangement.

Figure 1 is a schematic showing a system for oxygen removal from wine by nitrogen sparging using a sparger assembly 100. Wine to be sparged is contained in a storage container 12. Pump 14 transfers the wine from the storage container 12 via line 16 and through the sparger assembly 100. The sparger assembly 100 is provided with a nitrogen carrier gas from a nitrogen supply 18 via line 20. The sparger assembly 100 is arranged so that it can be connected to the lines 16, 20 and 22 using "quick connect" couplings, for example Tri-Clover ® clamps.

The sparged wine leaves the sparger assembly 100 via line 22 and flows through a valve 24. Valve 24 can be operated to divert the sparged wine for further treatment via line 26 or to a buffer tank 28 in which nitrogen is removed before the sparged wine is sent to a further storage tank via line 30.

As shown in Figure 1 , a pressure regulator 32, flow meter 34, hose 36, isolating valve 38 and check valve 40 are provided on the line 20.

Figure 2 illustrates the sparger assembly 100 in cross-section. The sparger assembly 100 includes an inlet connector 120, a body 140, a gas permeable membrane in the form of a sintered metal bush 160, an outlet connector 180, a nut 200 and turbulence creating means in the form of a vortex unit 220.

The inlet connector 120 is threadedly connected to an inlet end of the body 140. An outlet end of the body 140 is threadedly connected to the outlet connector 180. Respective o-ring seals 230, 232 are provided to ensure proper sealing between the inlet connector 120 and the inlet end of the body 140 and the outlet end of the body 140 and the outlet connector 180.

O-ring seal 234 is provided to ensure a proper seal between the outlet connector 180 and the line 22. A washer 236 is provided to ensure a proper

seal between the inlet connector 120 and the line 16. Nut 200 has an internal thread 202 to enable threaded connection with an external thread on the line 16. A nut or other connector (not shown) is used to connect the outlet end of the outlet connector to the line 22.

The inlet connector 120 as illustrated in Figure 3 is made in three parts that are welded together. These three parts are a collar 122, a tube 124 and a coupling 126. Prior to welding the collar 122, tube 124 and the coupling 126 together, the nut 200 is located on the tube 124. Location of the nut 200 about the tube 124 of the inlet connector 120 is illustrated in Figure 3.

The body 140 as illustrated in Figure 4 is made in four parts that are welded together. The body 140 has a nominal length of 150mm and nominal diameter of 75mm. The four parts of the body 140 are an inlet coupling 142, a tube 144, an outlet coupling 146 and an inlet pipe 148. The inlet pipe 148 has an external thread to enable it to be threadedly connected to the nitrogen supply line 20.

The tube 144 of the body 140 has an internal diameter larger than the internal diameter of the inlet connector 120. As illustrated, the internal diameter of the tube 144 of the body 140 is about 72mm and the internal diameter of the inlet connector 120 is about 47mm. This increase in the internal diameter of the tube 144 of the body 140 reduces friction and stress in the wine by providing a path of equal or larger diameter than the wine supply line 16. Hence, the quality of the resultant wine is enhanced.

Figure 5 illustrates the sintered metal bush 160 that is arranged to be located within the body 140 by means of a machined locating spigot at each end of the sparger body 140 and the o-ring seals 230, 232. The bush 160 is made of stainless steel and, as illustrated, is nominally 70mm in diameter and about 140mm in length. The bush 160 has a porosity of about 40 microns.

The bush 160 is located within the body 140 so that nitrogen passing through the inlet pipe 148 will flow into a gas flow zone between an inner surface of the

tube 144 and an outer periphery of the bush 160. The nitrogen gas thus travels around the outer periphery of the bush 160 and then through it. As the bush 160 has a porosity of about 40 microns very fine bubbles of nitrogen gas are caused to flow into the wine that passes through the inner diameter (bore) of the bush 160. The bubbles of nitrogen gas have a diameter of about 0.01 mm at a pressure of about 30OkPa.

The bush 160 as described is a stainless steel bush. However, the bush 160 may be made of other materials. For example, the bush 160 may be made from a sintered metal, a porous ceramic or plastics material.

The outlet connector 180 as illustrated in Figure 6 is made in three parts that are welded together. These three parts are an inlet collar 182, a tube 184 and an outlet collar 186. An optional adaptor (not illustrated) may be supplied for the outlet and inlet connectors 180, 120 to facilitate connection to fittings of different thread sizes. This optional adaptor may be supplied with Tri-Clover ® clamps.

The vortex unit 220 includes an outer ring 222, a centre tube 224 and three tines 226. Each tine 226 is welded to an inner face of the outer ring 222 and an outer face of the centre tube 224. The tines 226 are spaced at 120° from each other.

As best shown in Figure 8A, each tine 226 is elongate and is twisted through at least 180° over its length. The tines 226 as depicted are 17mm wide, 124mm in length and at 90mm (from their connected end) they have twisted through 180°.

The vortex unit 220 is arranged to be positioned within the inlet connector 120 so that an underside of the outer ring 222 is located against a seat 122a formed in the collar 122. The vortex unit 220 is upstream of the bush 160. Washer 236 holds the outer ring 222 against the seat 122a when the nut 200 is threadedly engaged with the line 16.

In use, the wine to be sparged enters the sparger assembly 100 via line 16 and flows through the inlet connector 120. As the flow of wine passes through the vortex unit 220 it is caused to "twist". It is envisaged that the flow of wine will twist through 180° thereby creating spiral turbulence of the flow of wine in the body 140 of the sparger assembly 100. This turbulence helps to increase the contact rate between the wine and the fine diameter bubbles of nitrogen gas that have passed through the metal bush 160. This increases the contact rate/exchange surface between the wine and the nitrogen bubbles greatly improving the efficiency of the deoxygenating process. The combination of gas bubbles of a small diameter, typically 0.01 mm, and the increased surface contact between the gas and the wine created by the vortex unit 220 means an efficiency of typically better than 90% is achievable.

The present invention recognises that the efficiency of the deoxygenating process depends on the amount of intimate contact between the sparging gas

(e.g. nitrogen) and the liquid being sparged (e.g. wine), the time of that contact and the time allowed for the release of oxygen. Accordingly, by creating small diameter nitrogen gas bubbles within the bush 160 a larger surface area for contact between the gas and the wine is established. This larger surface area means that the contact time between the gas and wine is less important and hence can be reduced. It is believed that contact time for efficient removal of oxygen from wine can be reduced from about 30 seconds to 5 to 10 seconds.

By establishing turbulent flow of the wine as it passes through the bush 160 the contact rate between the wine and the gas is increased, again improving the efficiency of the deoxygenating process.

Another advantage of embodiments of the present invention is that it allows the ratio of nitrogen gas to wine to be reduced from 0.7 to 1.0 or even up to 4 volumes of gas per volume of wine to 0.1 to 0.2 volumes of gas per volume of wine.

The present invention when used for sparging wine allows for lower gas flow rates, a reduction or possible elimination in foaming of the wine and lower levels of dissolved oxygen or dissolved carbon dioxide.

The gas permeable membrane in accordance with the described embodiment of the invention is a sintered metal bush. However, the gas permeable membrane may adopt other forms. For example, the gas permeable membrane may be a length of material that forms part of a pathway along which the liquid flows between the inlet and outlet of the sparging assembly. In accordance with such an embodiment, the gas permeable membrane may form a section of a wall of a tube located with the body of the sparging assembly or an inner bush of a smaller diameter through which the gas would flow outwardly to make contact with the wine.

Test Data (1):

Testing of dissolved oxygen levels in unsparged wines and sparged wine using a sparger assembly in accordance with an embodiment of the invention and nitrogen as the sparging gas provided the following results:

In the above Tables of test data, the wine was transferred by pump at a rate of 15,000 litres per hour and the sparger assembly 100 set up with a gas flow rate equal to 5% of the pumping rate, or 12.5 litres per minute and a pressure of 30OkPa.

The terms used in the Tables define the wine type and/or winery operation, for example:

"Beaujolais after blend" refers to the wine type, and the winery operation after the wine was blended or mixed with other wine to achieve the desired final style.

"Chablis after blend" is a wine style and winery operation carried out after the wine was blended with another wine.

"Gordo Moselle after transfer" refers to the wine type, and a winery operation involving the movement of wine (transfer) from one wine tank to another. "Gordo Moselle after pad filter", and similar descriptions relating to Chard/Col, refer to that part of a winery operation where the blended wine is passed through a pad filter in order to remove suspended material in the wine and achieve the wine clarity required. This operation would be a typical place where sparging would be carried out immediately after the wine exits from the pad filter, as this operation can result in an increase in dissolved oxygen levels in the wine.

Further testing of a sparger assembly in accordance with an embodiment of the invention, using nitrogen as the inert gas at a gas flow rate equal to 5% of the

pumping rate, achieved a 94% average reduction in the dissolved oxygen level in the wine.

Wine in storage tanks was sparged in tank with a sparger assembly in accordance with an embodiment of the invention and a gas mixture of 60% nitrogen, balance carbon dioxide, achieved a 95% average reduction in the dissolved oxygen level in the wine.

Test Data (2):

Tests were conducted to examine the efficiency of oxygen removal versus nitrogen flow rates. The following results were obtained:

Further testing of a sparger assembly in accordance with an embodiment of the invention using a gas/liquid flow ratio of 10% achieved a maximum of 94% removal of dissolved oxygen. The best figure obtained prior to the use of a prior art sparger was 80% dissolved oxygen removal.

The embodiments and Tests have been described by way of example only and modifications within the spirit and scope of the invention are envisaged.