AU2007215373B2

AU2007215373B2 - A heating assembly

Info

Publication number: AU2007215373B2
Application number: AU2007215373A
Authority: AU
Inventors: Peter Henry
Original assignee: P H E ENTPR Pty Ltd
Current assignee: Phe Enterprises Pty Ltd
Priority date: 2006-02-09
Filing date: 2007-02-08
Publication date: 2009-04-02
Anticipated expiration: 2027-02-08
Also published as: WO2007092989A1; AU2007215373A1

Description

WO 2007/092989 PCTiAU2007/000134 1 A HEATING ASSEMBLY Technical Field This invention relates to a heating assembly for use in hydrogen peroxide sterilisation.

Background to the Invention In the food and drinks packaging industry it is typically necessary to ensure that packaging containers are clean and sterile before being filled with product. This is done for food hygiene reasons, and to extend the shelf life of food and drink products.

Often, drink containers are sterilised just before filling by way of an in-line hydrogen peroxide sterilisation system that forms part of the bottling production line.

These sterilisation systems heat a dosed amount of a hydrogen peroxide and air mixture and direct the heated mixture into a bottle to sterilise the bottle. It is important that the hydrogen peroxide and air mixture is mixed and heated in a controlled manner to provide effective sterilisation.

An example of a known heating apparatus for use in peroxide sterilisation is shown in attached figures 1 and 2. The apparatus 10 includes an inner barrel 11 having a central bore 12. Around the barrel 11 are wrapped two heating elements 14, 16. The 2 0 heating elements are fused to the outside surface of barrel 11. Two thermocouples 18, monitor the temperature in the vicinity of respective ones of heating elements 12, 14 to allow for thermostatic control of the heating apparatus. When used in a bottling production line a controlled dose of hydrogen peroxide and air is introduced into one end of bore 12 as each empty bottle passes the heating apparatus. The mixture passes through the bore and is heated. Heat exchangers in the form of springs 22 and worms 24 aid in transfer of heat to the mixture and also assist in uniform mixing of the hydrogen peroxide and air. The heated mixture leaves the other end of bore 12 and is directed into an empty food or drink container to sterilise the container. The temperature of the mixture leaving the bore is typically at around 200 degrees centigrade and must be controlled very accurately for optimum sterilisation without leaving a harmful residue of hydrogen peroxide in the container being sterilised.

Peroxide heaters of the type shown in figures 1 and 2 typically last for about 1000 hours of use before one of the heating elements 14, 16 fails. When used in a WO 2007/092989 PCT/AU20071000134 2 production line running 24 hours per day this equates to only about 6 weeks of use.

When either of the heating elements 14, 16 fail they cannot be replaced due to being fused in place. The entire heating assembly 10 must be discarded and replaced.

Summary of the Invention In a first aspect the present invention provides a heating assembly for use in a peroxide sterilisation system, the heating assembly including a bore, and at least one heating element is associated with the bore, wherein the heating element is removably mounted in the assembly to facilitate replacement of the heating element. If a heating element fails then it can be replaced without the need to replace the entire assembly thus saving material and the cost of materials.

The bore may be provided in an inner barrel and the heating elements lie in recesses provided about the outside of the inner barrel.

The assembly may further include an outer barrel which has recesses for housing the heating elements.

The outer barrel may be formed from a number of separate shells.

The assembly may further include clamping means provided about the assembly.

In a second aspect the present invention provides a heating assembly for use in a peroxide sterilisation system, the heating assembly including a bore, and at least two heating elements are associated with the bore, wherein the heating elements are rated to provide for effective heating capacity to effect sterilisation in the event of one of the at least two heating elements failing. If a heating element fails then the unit can continue to operate thus extending the period between servicing the heating assembly and reducing production line down-time and associated costs.

In a third aspect the present invention provides a method of modifying a heating assembly for use in a peroxide sterilisation system, the heating assembly including a bore provided in an inner barrel, the method including the steps of: removing the inner barrel of the assembly and fitting a replacement inner barrel, the replacement inner barrel having recesses spaced about its outside surface for mounting heating elements.

WO 2007/092989 PCT/AU20071000134 3- Brief Description of the Drawings An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic cross sectional view of an embodiment of a prior art hydrogen peroxide heating assembly; Figure 2 depicts the heater assembly of figure 1 partially disassembled; Figure 3 is a side view of a heater assembly according to an embodiment of the present invention; Figure 4 is a partially disassembled view of the heater assembly of figure 3; Figure 5 is a cross section view along the line A-A of figure 3; Figure 6 is a perspective view of the barrel of the heater assembly of figure 3; Figure 7 is a cross section view along the line B-B of figure 6; Figure 8 is a cross section view of one of the outer barrels of figure 3; Figure 9 is a side view of a heating element and shell used in an alternative embodiment of the invention; Figure 10 is a cross sectional view along the line C-C of figure 9; and Figure 11 is a cross sectional view of an alternative embodiment of the invention.

Detailed Description of the Preferred Embodiment Referring to Figures 3 to 8, a heater assembly 100 according to an embodiment of the invention is shown. Heater assembly 100 includes an inner barrel 111 with a central bore 112 of 20mm diameter. In use, heater assembly 100 operates to heat a mixture of hydrogen peroxide and air in a similar manner to the heater assembly of figures 1 and 2 as described above. Thus, a prior art heating assembly can simply be swapped for one according to figures 3 to 8.

Heater assembly 100 includes two outer barrels 120 and 122. Both outer barrels 120, 122 are constructed identically and only one will be described in detail.

Outer barrel 120 has an array of nine equally spaced recesses 124 provided about its inner surface. Recesses 124 are dimensioned to each house one cylindrically shaped heating element 130. Each heating element 130 is about 6mm in diameter and is about in length. Each element has a double glass nickel tail and is rated at 300Watts 240Volts. Nine recesses 126 are provided about inner barrel 111. Recesses 126 WO 2007/092989 PCT/AU20071000134 4 correspond to recesses 124 provided in outer barrel 120 and together cooperate to house heating elements 130.

To assemble, flange 136 is TIG welded to inner barrel 111 to form a waterproof sealed join. Nine heating elements 130 are then placed in recesses 126 towards the low temperature end of the assembly. An outer barrel 122 is then slid over the heating elements which lie in the cylindrical apertures formed by recesses 126 and 124. Heat sink paste is used in the joins between the heaters and the barrel to improve heat transfer. Once the outer barrel 122 is in place, clamping means in the form of two 6mm wide stainless steel bands are placed about the outer barrel, tightened with a tightening tool and fastened with bandit clamps 131. Outer barrel has a slot 132 that allows for a small amount of elastic deformation and the bandit clamps 131 are tightened to squeeze the heating elements tightly within the inner and outer barrels. The same procedure is then repeated to fit nine heating elements and outer barrel 120 at the high temperature end of the assembly. A thermocouple is then inserted through slot 132, one for each outer barrel 120, 122. The thermocouples each sit in a hole (not shown) of 1.5mm diameter and 1mm depth previously drilled into inner barrel 11 1.

The connecting wires from each of the heaters are then fed through an outer housing similar to that shown in figure 1 for external connection to a control unit (not shown) and the completed inner and outer barrel assembly is slid into the outer housing.

The other end flange 137 is then pressed onto the end of inner barrel 111 and TIG welded to seal. Springs and worms are then introduced into bore 112. A circlip (not shown) is fitted inside inner barrel to prevent the springs and worms from dropping out.

Heating elements 130 are connected to the control unit in parallel. Thus, in the event of breakdown of one of the heating elements 130, the remaining heating elements can continue to operate. This means that the assembly 100 can go on working despite the breakdown of a heating element. Assembly 100 will continue to work until the number of failed elements causes the assembly to be unable to reach and maintain an adequate operating temperature. The actual number of failed elements that can be tolerated in a particular application depends upon various factors including ambient and desired operating temperatures. In the embodiment described above, the nine heating elements rated at 300W combine to provide heating capacity of 2700W for both the low and high temperature ends of the heater. The inventor has found that the heating assembly can operate adequately for the purpose of hydrogen peroxide sterilisation if up WO 2007/092989 PCT/AU20071000134 to two elements 130 have failed in both of the high and low temperature ends of the assembly.

In the event of failure of heating elements 130, it is possible to replace them by disassembling assembly 100. Flanges 136 or 137 may be removed and the bandit clamps 131 released to allow for replacement of heating elements.

It is possible to modify a prior art heating assembly such as the one shown in figures 1 or 2 to retrofit a new inner barrel 111 to arrive at an assembly according to the present invention. This might be done in the event of failure of an existing heater assembly. To do this, the end flanges of the assembly are machined off and a new inner barrel 111 is utilised with recesses 126. Assembly is otherwise the same as described above. Various parts of an existing assembly may thus be re-used including the end flanges, existing wiring, outer housing and mounting brackets.

Referring to figures 9 to 11, an alternative embodiment of a heating assembly is shown. This version utilises twelve heating elements 230 which are about 13mm in length and 6mm in diameter and each rated at 500Watts 240Volts, giving a combined capacity of 6kW. In this embodiment, the outer barrel is formed from a number of separate shells 220.

To assemble, the heating elements are placed in recesses 226 provided in inner barrel 211. Each heating element 230 is then covered by a steel shell 220 of 1.2mm thickness and about 13mm in length. Again, heat sink paste is applied to these components during assembly to improve heat transfer. A stainless steel band (not shown) is then applied about the assembly and tightened to keep the heating elements in place. Thermocouple 240 is inserted into a hole in inner barrel 211 to monitor temperature during use.

In the embodiments described above the bore of the inner barrel was Similarly, heating assemblies of larger or smaller capacities may be produced which may have different dimensions.

Any reference to prior art contained herein is not to be taken as an admission that the information is common general knowledge, unless otherwise indicated.

Finally, it is to be appreciated that various alterations or additions may be made to the parts previously described without departing from the spirit or ambit of the present invention.

Claims

1. A heating assembly for use in a peroxide sterilisation system, the heating assembly including a bore, and a number of heating elements are associated with the bore, wherein the heating elements are removably mounted in the assembly to facilitate replacement of the heating elements; the bore is provided in an inner barrel and the heating elements lie in recesses provided about the outside of the inner barrel, wherein the recesses extend along the assembly in the direction of the axis of the bore.

2. A heating assembly according to claim 1 further including an outer barrel which has recesses for housing the heating elements.

3. A heating assembly according to claim 2 wherein the outer barrel is formed from a number of separate shells.

4. A heating assembly according to any preceding claim further including clamping means provided about the assembly. A heating assembly according to any preceding claim wherein the heating elements are rated to provide for effective heating capacity to effect sterilization in the event of one of the heating elements failing.