Method And Apparatus For Fumigant Gas Capture

Abstract

In one aspect the invention provides a fumigant gas capture apparatus. This apparatus includes at least one channel adapted for connection to a volume containing a fumigant gas, the channel defining an inlet which receives gas and an outlet which allows gas to exit the channel. The apparatus also includes at least one drive structure arranged to drive fumigant gas through the channel, at least one spray nozzle adapted to deliver a treatment liquid into the channel, and at least one packing element positioned within the channel to allow a spray nozzle or nozzle to spray treatment liquid on to the packing element.

Claims

1.-22. (canceled)

23. A fumigant gas capture apparatus which includes plurality of channels provided with a vertical orientation adapted for connection to a volume containing a fumigant gas, each channel defining an inlet located at the bottom of the channel which receives gas and an outlet located at the top of the channel which allows gas to exit the channel, said plurality of channels being arranged for interconnection with one another with linkages being provide between the outlet of one or more channels to the inlet of one or more channels to filter fumigant gas flows through a sequential array of channels, at least one drive structure arranged to drive fumigant gas through the channel, at least one spray nozzle adapted to deliver a treatment liquid into the channel, and at least one packing element positioned within the channel to allow a spray nozzle or nozzle to spray treatment liquid on to the packing element.

24. The fumigant gas capture apparatus as claimed in claim 23 wherein said at least one packing element is sprayed with treatment liquid by a spray nozzle to coat at least a portion of the surface of said at least one packing element with treatment liquid to expose fumigant gases to the coated surface or surfaces of the packing element when driven through the channel.

25. The fumigant gas capture apparatus as claimed in claim 23 which captures and treats methyl bromide.

26. The fumigant gas capture apparatus as claimed in claim 23 which includes a reservoir of treatment liquid adapted to deliver treatment liquid to said at least one spray nozzle.

27. The fumigant gas capture apparatus as claimed in claim 26 wherein the treatment liquid is a basic or alkaline liquid having a pH value of at least seven.

28. The fumigant gas capture apparatus as claimed in claim 26 wherein the treatment liquid is composed from or includes an organic solvent.

29. The fumigant gas capture apparatus as claimed in claim 23 wherein a channel is formed by a linear conduit with a single inlet adjacent to one end and a single outlet adjacent to its opposite end.

30. The fumigant gas capture apparatus as claimed in claim 23 which integrates one spray nozzle only in each of its channels, each spray nozzle being positioned adjacent to the outlet of the channel.

31. The fumigant gas capture apparatus as claimed in claim 23 wherein a packing element reduces the size of treatment liquid droplets sprayed on the packing element on which the fumigant gases are exposed to when driven through the channel.

32. The fumigant gas capture apparatus as claimed in claim 23 wherein a packing element promotes a phase of the fumigant gas compounds into a liquid form.

33. The fumigant gas capture apparatus as claimed in claim 23 wherein a packing element is arranged to induce turbulence in the fumigant gases and optimise the surface area contact between the gases and liquids within a channel.

34. The fumigant gas capture apparatus as claimed in claim 23 wherein a channel employed with the invention locates a plurality of packing elements.

35. The fumigant gas capture apparatus as claimed in claim 23 wherein packing elements form a packed tower arrangement when a channel has a vertical orientation with treatment liquid sprayed into the top of the tower and fumigant gases driven through the bottom of the tower.

36. The fumigant gas capture apparatus as claimed in claim 23 which employ one or more of fans or pumps to push and or pull gas flows through channels.

37. The fumigant gas capture apparatus as claimed in claim 23 wherein a fan or pump is provided for each channel.

38. The fumigant gas capture apparatus as claimed in claim 23 which includes a heat transfer structure engaged with the inlet of at least one channel.

39. The fumigant gas capture apparatus as claimed in claim 23 which includes a mobile support platform supported by set of wheels.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Additional and further aspects of the present invention will be apparent to the reader from the following description of embodiments, given in by way of example only, with reference to the accompanying drawings in which:

[0052] FIG. 1 shows a side view of a fumigant is gas capture and treatment apparatus as provided in accordance with a preferred embodiment, and:

[0053] FIG. 2 shows a plan view of the apparatus of FIG. 1, and

[0054] FIG. 3 shows a side cross-section view of one of the channels integrated into the apparatus shown with respect to FIGS. 1 and 2.

[0055] Further aspects of the invention will become apparent from the following description of the invention which is given by way of example only of particular embodiments.

BEST MODES FOR CARRYING OUT THE INVENTION

[0056] FIGS. 1 and 2 show side and plan views of a gas capture and treatment apparatus 1 as provided in accordance with a preferred embodiment. FIG. 3 provides a side cross section view of one of the channels 2 used in the construction of the apparatus.

[0057] The capture apparatus 1 includes an array of four channels 2 which can be connected to a volume containing a fumigant gas. In the embodiment shown the apparatus 1 is arranged to receive methyl bromide gas extracted from a pile of covered logs after the completion of a fumigation process. In various embodiments methyl bromide gas extracted from the log pile may pass through a heat treatment structure (not shown) before reaching the channels 2. This heat treatment structure can be used to raise the temperature of the methyl bromide gas prior to delivery to a channel.

[0058] Each channel 2 defines an inlet 3 which receives gas and an outlet 4 which allows gas to exit the channel. As can be seen from FIGS. 1 and 2 the channels have a vertical orientation with the outlet 4 at the top of the channel and the inlet 3 at the bottom of the channel.

[0059] FIG. 2 shows how each of these four channels can be configured in a modular fashion to vary the treatment applied to the gas supplied to the apparatus. In the particular embodiment shown the four channels are split into two pairs of channels. The outlet of a first channel 2a is connected to the inlet of a second channel 2b. The outlet of the second channel is then connected to a centrifugal filter 5 which removes entrained treatment liquid and allows the treated gas flow to be vented to atmosphere.

[0060] In other configurations all four channels may be connected outlet to inlet to maximise the treatment applied to a gas flow, and can potentially have the outlet of the final channel connected to the inlet of the first channel to recirculate the gas flow.

[0061] The capture apparatus 1 includes a pair of drive structures, formed in this embodiment by an inlet fan 6 and outlet fan 7. These fans are arranged to drive fumigant gas through each of the channels by either a blowing or suction effect.

[0062] As shown with respect to FIG. 3 the apparatus 1 includes a reservoir of treatment liquid 8 which is provided to deliver treatment liquid to a spray nozzle 9 integrated into each channel. In the embodiment shown this treatment liquid is formed from an organic solvent, although other compounds such as basic or alkaline liquids can be used in alternative embodiments.

[0063] Each spray nozzle 9 is adapted to deliver a treatment liquid into the channel 2 and is provided adjacent to the outlet 4 of the channel.

[0064] Each channel also contains a large number of packing elements positioned within the channel to allow the spray nozzle 9 to spray treatment liquid on to the packing elements. In the embodiment shown these packing elements are formed by a collection of tellerettes 10.

[0065] In use treatment fluid is delivered from the reservoir to each spray nozzle 8 and sprayed on to the tellerettes 10 packed into the interior of each vertically orientated channel 2. Fumigant gas is then driven through the channels under the action of either or both of the inlet and outlet fans 6, 7. The action of the fans drives the fumigant gas into contact with both a mist of treatment liquid droplets in addition to the treatment liquid coating the surfaces of the packing element tellerettes 10.

[0066] This used of vertically orientated channels filled with packing elements maximised the contact surface area and interaction between the treatment liquid and the gas flow, promoting a phase change to liquid for the fumigant gas. The treatment liquid then reacts with the captured fumigation compounds to neutralise same into a more benign form. Treated gas flows can then be vented to atmosphere without the fumigant compounds they once captured, and the treatment fluid used to neutralise these compounds can simply be drained from each channel and pumped back to the reservoir 8.

[0067] As can be seen from FIGS. 1 and 2 the apparatus also includes a mobile support platform 11. This platform is used to mount and support the various additional components of the invention through the provision of a deck 12 mounted to a set of wheels 13. A towing linkage 14 is also provided at one end of the deck to allow the apparatus to be towed by a vehicle from site to site.

[0068] In these embodiments the vertical height of each of the invention's channels may be restricted or controlled to provide a compact and manoeuvrable mobile apparatus 1. The interconnected channels mounted on the mobile platform can provide all the processing capacity required by a range of applications without necessarily increasing the height of the apparatus to where it would be prevented from accessing confined locations.

[0069] These channels can also be interconnected with one another in a modular fashion to suit the requirements of a particular application or fumigation space. When combined with the mobile platform this staged or modular arrangement provides for a portable character, allowing the operative components of the invention to be towed to various locations through or into restricted spaces.

[0070] In the preceding description and the following claims the word comprise or equivalent variations thereof is used in an inclusive sense to specify the presence of the stated feature or features. This term does not preclude the presence or addition of further features in various embodiments.

[0071] It is to be understood that the present invention is not limited to the embodiments described herein and further and additional embodiments within the spirit and scope of the invention will be apparent to the skilled reader from the examples illustrated with reference to the drawings. In particular, the invention may reside in any combination of features described herein, or may reside in alternative embodiments or combinations of these features with known equivalents to given features. Modifications and variations of the example embodiments of the invention discussed above will be apparent to those skilled in the art and may be made without departure of the scope of the invention as defined in the appended claims.