AU2006285513A1 - Container decontamination - Google Patents

Description

WO 2007/027111 PCT/NZ2006/000227 TITLE OF THE INVENTION CONTAINER DECONTAMINATION 5 BACKGROUND TO THE INVENTION This invention relates to container decontamination and more particularly a method and 10 apparatus for the thermal decontamination of containers, particularly shipping containers and other enclosed vessels. The term "container" is taken to include applications involving enclosed vessels but also can include ducting such as air conditioning ducting for example. Historically enclosed vessels, including shipping containers and ducting, have been 15 decontaminated using chemicals or fumigants such as methyl bromide. For health and environmental reasons this is becoming increasingly unacceptable. Imported products into New Zealand, more particularly plant and vehicles are commonly inspected, and if an infestation of pests/insects or other microbiology is suspected or 20 discovered, then a heat disinfestation operation is carried out. The manner in which this is carried out is labour intensive and, therefore, costly. Because only plant/vehicles which are discovered to be infested, or are suspected of being infested, are subjected to thermal decontamination, there is always the possibility of infested plant/vehicles coming into the country. This is in part because the manual inspection procedure does not always enable 25 possible areas of infestation to be accessed and hence inspected or fully inspected. The thermal decontamination processes used to-date suffer from a number of drawbacks. One is that the item(s) to be disinfested may need to be unloaded from a container so that. the thermal decontamination procedure can be carried out. Also, with plant/vehicles these 30 may need to be moved/transported some distance away from the importing vessel and hence there is always the possibility of pests/insects escaping into the environment prior to the disinfestation procedure being carried out.

WO 2007/027111 PCT/NZ2006/000227 2 As noted above, cost is also a significant issue, not only with plant and vehicles but also other items/imported goods, that may require disinfestation. 5 In addition, thermal decontamination apparatus and methods often do not create a sufficiently hostile environment to ensure that disease pathogens, virus pests/insects etc. are killed off, especially those that might be located in areas which are somewhat inaccessible. To address this, the thermal environment used to carry out the disinfestation is maintained for a lengthy period of time. This, however, simply increases the inefficiencies 10 of the known processes and hence the cost. A further problem that can arise as a result of such processes is that of contaminated air exiting to atmosphere whereby disease pathogens, virus, insects and others can be placed into the environment-and put bio security at risk. 15 SUMMARY OF THE INVENTION There is thus a need for thermal decontamination apparatus and methods for use, in particular with shipping containers or other enclosed vessels including ducting and piping 20 which provides an improved or, at least, an alternative method/means for decontamination and destruction of disease pathogens, virus, insects and others which put bio security at risk and therefore goes some way to addressing at least some of the drawbacks associated with known methods/means. An object of the present invention is to provide such apparatus and method for thermal decontamination. 25 The inventive concept embodied in the present invention is apparatus and method of thermal decontamination which employs forced positive pressure, humid superheated air encapsulated and recycled to form a closed system. This provides an environment to WO 2007/027111 PCT/NZ2006/000227 3 achieve thermal decontamination in a manner which improves efficiency and efficacy as well as preventing contaminated air from exiting to atmosphere. Broadly in one aspect of the invention there is provided a method of decontaminating a 5 container or closed vessel including the steps of creating a formed positive pressure superheated airflow and directing this into the container/closed vessel and directing an output airflow from the container/closed vessel back into apparatus creating the forced positive pressure superheated airflow. 10 In a second broad aspect of the invention there is provided decontamination apparatus including a container or closed vessel; superheated airflow producing apparatus including a flame tube, burner and turbine arranged to create a forced positive pressure superheated airflow; means to direct the input airflow into the container/closed vessel and means to direct a return airflow into-the airflow producing apparatus. 15 In a particular form of the invention the thermal decontamination is effected directly within the container or vessel in which items to be decontamination are located. Accordingly, the invention can be used directly with containers used for the importation of items such as vehicles, machinery, foods and organic products. According to a further embodiment, 20 however, the container or vessel to be decontaminated may- be placed within another container to allow simultaneous interior and exterior treatment of the container or vessel. BRIEF DESCRIPTION OF THE DRAWINGS 25 In the following more detailed description of preferred embodiments of the invention reference will be made to the accompanying drawings in which: Figure 1 is a schematic illustration of apparatus for carrying out the thermal decontamination process in a closed vessel, and WO 2007/027111 PCT/NZ2006/000227 4 Figure 2 is a somewhat schematic illustration of apparatus according to the present invention employed in a method of carrying out thermal decontamination of a shipping container. 5 DETAILED DESCRIPTION OF AN EMBOIDEMENTS OF THE INVENTION According to the invention there is provided a thermal decontamination method whereby air is heated using a diesel or gas fired burner firing into a flame tube. Water or heated water 10 vapour is introduced into the superheated airflow which is moved by a power driven turbine to create high volume forced humid air. This combination of superheated air and water vapour is directed into an enclosed container to thereby carry out thermal killing of disease pathogens, virus, insects, pests and others. The air cycles through the container and is fed (extracted) back into the flame tube/turbine to thereby create a closed system. The flame 15 combustion will heat up the interior/content of the container to effect destruction of the target infestation and will ultimately provides a controllable environment in the container. According to an alternative embodiment of the invention, the method may be carried out without the addition of water vapour if this is necessary to accommodate certain substrates 20 or products within the container. As is described hereinafter, the method can be carried out directly within a shipping container in which the item or items to be decontaminated is/are located. Thus, for example, the shipping container could be one which has been imported into the country and 25 for which decontamination of the products within the container is required. Alternatively, the shipping container could be simply a container used -to create a vessel into which product, to be decontaminated, can be .placed. For example, heating apparatus, as hereinafter described, can be coupled to a shipping container into which a vehicle can be driven. Once the vehicle has been placed in the container the container can be closed up WO 2007/027111 PCT/NZ2006/000227 5 and the decontamination procedure carried out. In this way a relatively low capital cost decontamination plant for motor vehicles, machinery or other items can be achieved. Thus, as shown in the drawing, the apparatus 10 for creating the superheated air/water 5 vapour is connected directly to an enclosed vessel e.g. a conventional shipping container C. The apparatus 10 can be mobile in nature (see Figure 2) by being mounted on a wheeled chassis 12 which can be connected to a towing vehicle 13. In this way the apparatus 10 can be moved about to enable it to be positioned adjacent and connected to a shipping container wherever the shipping container may be located. 10 To this end, and as shown in Figure 2 of the drawings, the shipping container C can have the doors D open and the apparatus 10 abutted against the doors. The apparatus 10 therefore incorporates a sealing arrangement 14 which not only seals against the forward facing edges of the open doors D but also provides a seal across- the -top and bottom of the doors and up 15 to the end of the container C. In this way a complete seal is formed between the apparatus 10 and the interior of the container C. It will be evident that other arrangements to achieve a substantially sealed connection with the open end of the container C can be employed. In an alternative arrangement, the apparatus 10 can be engaged with a fixed wall such as the 20 closed end wall of the container C. This can be achieved by suitable ducting connected between an outlet of the apparatus 10 and a wall of the container C, and between the wall of the container C and an inlet of the apparatus. Such an arrangement is suitable when the container C is to function solely as an enclosed vessel into which say motor vehicles, machinery and the like can be placed through the open doors and decontamination once the 25 doors have been closed to complete the enclosed vessel. This is the type of arrangement as shown in Figure 1. As is shown in Figure 2 of the drawings, the apparatus 10 includes a powered turbine 15, a burner 16 and a water injector 17. Fluid tanks 18 are provided for suppling water to the WO 2007/027111 PCT/NZ2006/000227 6 water injector and supplying fuel to the burner 16 (when the burner is oil/diesel powered) and also the prime mover (engine) of the powered turbine 15. The apparatus 10 can, for example, be a suitably adapted BioVapour (trade mark) thermal heating apparatus produced and marketed by Dearcorp Limited. 5 The apparatus 10 further includes an outlet duct 19 whereby superheated air/water vapour can exit from the apparatus 10. It also includes an inlet duct 20 whereby exiting vapour/superheated air from the container C can be retuned to the flame tube and turbine. Thus, as previously mentioned, the apparatus 10 with the container C forms a closed 10 system. It will be appreciated that in such an arrangement input air is drawn into the burner but will be controlled to be only sufficient to maintain combustion. The apparatus and method is suited for products and surfaces capable of accepting high temperature such as metal, steel, wood and others. Therefore, it is suitable for 15 decontamination of empty sea containers as well as sea containers containing such products capable of accepting high temperatures. The products may, as previously disclosed, already be contained within the sea container or placed therein for the decontamination procedure to be carried out. 20 By way of example only (the invention is not limited to the parameters mentioned herein) the heating apparatus 10 can be operated in accordance with the following: Heat -75C to 500C Most preferred - 1 OC to 250C 25 Water Vapour Rate - 1 It to 1 Olts Most preferred - 2lts to 5lts WO 2007/027111 PCT/NZ2006/000227 7 Air Volume - 10,000m 3 /hr to 1 00,000m 3 /hr Most preferred - 20,000m 3 /hr to 80,000m 3 /hr Treatment Duration - I min to 48 hrs 5 Most preferred - 3 mins to 3 hrs Burner Capacity - 50kw to 1,0001kw Most preferred 250kw to 600kw 10 When decontamination of containers or closed vessels is carried out in respect of products susceptible to high temperatures such as machinery, cars, fabrics etc. the same operation is carried out but with the following preferred parameters of operation: Heat - 45C to 200C 15 Most preferred - 50C to 80C Water Vapour Rate - 0.5Its to 1 Olts Most preferred - 1 Its to 4lts 20 Air Volume - 1 0,000m 3 /hr to 11 00,000m 3 /hr Most preferred - 20,000m 3 /hr to 80,000m 3 /hr Treatment Duration - 1 min to 48 hrs Most preferred - 3 mins to 3 hrs 25 Burner Capacity - 50kw to 1,000kw Most preferred 250kw to 600kw WO 2007/027111 PCT/NZ2006/000227 8 The treatment duration in both applications mentioned above is relative to container size based on approximately 32m 3 and 72m 3 capacity. Apparatus of the type described above used to carry out a thermal decontamination method 5 on an enclosed vessel has been found to be extremely effective yet efficient in operation and with improved efficacy over known thermal decontamination methods. The employment of forced positive pressure, humid superheated air into an enclosed vessel and then recycled in a closed system is the basis of the invention. This forcing of positive pressure superheated air into the container will create a pressure in the container such that venting via a filtered 10 vent 21 may be required in order to control internal pressure within the vessel C. The use of the powered turbine 15 gives velocity and volume of air movement. Thus, good driving/ penetrating of the air and water vapour into nooks and crannies in the item(s) to be decontaminated, is achieved. This. forces heat transfer and the turbulence/buffeting 15 achieved by the forced positive pressure humid superheated air creates an environment in which the target infestation will be destroyed. With inaccessible areas such as to be typically found in machinery, vehicles and the like, there will be potentially cold areas in which the target infestation may otherwise survive. However, the forced air flow ensures that such cold areas are minimised and, indeed, the turbulence/buffeting effect of the forced pressurised 20 air flow can achieve the sucking out of target infestation from such areas. In practical applications for air conditioning, a closed system may not be possible. The substrates to be treated may be before, during or after heat treatment washed down with a decontamination fluid at a temperature ranging between 20 0 C to 200 0 C. 25 As previously described the system may be operated without the addition of water vapour if necessary to accommodate certain substrates or products.

Claims (20)

1. A method of decontaminating a container or closed vessel including the steps of creating a formed positive pressure superheated airflow and directing this into the 5 container/closed vessel and directing an output airflow from the container/closed vessel back into apparatus creating the forced positive pressure superheated airflow.

2. The method of claim 1 further including injecting water into the superheated airflow 10 prior to entering the container/closed vessel.

3. The method of claim 1 or 2 wherein the air flow into the container/closed vessel is at a temperature of between substantially 75 0 C and 500 0 C. 15

4. The method of claim 1 or 2 wherein the air volume of the airflow is between substantially 10,000m 3 /hr and 100,000m 3 /hr, more preferably 20,000m 3 /hr to 80,000m 3 /hr.

5. The method of claim 4 wherein the method is carried out for a period of between 1 20 minute and 48 hours, more preferably 3 minutes to 3 hours.

6. The method of claim 3, 4 or 5 when appendant to claim 2 wherein the water vapour rate is between 0.5 litre to 10 litres, more preferably 1 litre to 5 litres. 25

7. The method of any one of claims 1 to 6 wherein one or more items to be decontaminated are placed in the container (closed vessel prior to commencement of application of the airflow into the container/closed vessel),

8. The method of claim 7 wherein the item is a vehicle. WO 2007/027111 PCT/NZ2006/000227 10

9. The method of any one of claims 1 to 8 wherein air is added to the apparatus creating the forced positive pressure superheated airflow at a rate sufficient to maintain combustion. 5

10. Decontamination apparatus including a container or closed vessel; superheated airflow producing apparatus including a flame tube, burner and turbine arranged to create a forced positive pressure superheated airflow; means to direct the input airflow into the container/closed vessel and means to direct a return airflow into the 10 airflow producing apparatus.

11. The apparatus of claim 10 further including a water injector for injecting water into the airflow to create a forced superheated humid positive pressure airflow into the container/closed vessel. 15

12. The apparatus of claim 10 or 11 wherein the air producing apparatus is mobile.

13. The apparatus of claim 12 further including sealing means coupled to the means to direct the input and return airflow, the sealing means being arranged to create a 20 sealed coupling between the airflow producing apparatus and the container via opened closure of the container.

14. The apparatus of any one of claims 10 to 13 wherein the burner is of a capacity in the range of substantially 50kw to 1,000kw, more preferably 250kw to 600kw. 25

15. The apparatus of any one of claims 10 to 14 wherein the turbine is of a capacity able to create an air volume flow of between substantially 10,000m 3 /hr to 1 00,000m 3 /hr, more preferably between 20,000m 3 /hr to 80,000 m 3 /hr. WO 2007/027111 PCT/NZ2006/000227 11

16. The apparatus of any one of claims 10 to 15 further including filtered air vent means in the container/closed vessel.

17. The apparatus of any one of claims 10 to 16 wherein the burner is gas or diesel 5 powered.

18. The apparatus of any one of claims 10 to 17 wherein the turbine is gas or diesel powered. 10

19. A method of decontaminating a container as claimed in claim 1 substantially as herein described.

20. Decontamination apparatus as claimed in claim 10 substantially as herein described with reference to the accompanying drawings. 15