NZ237524A - Portable steam producing apparatus for killing weeds and other pests - Google Patents

Description

237 52 NEW ZEALAND PATENTS ACT, 1953 No.: 237524 Filed: 21 March 1991 COMPLETE-AFTER-PROVISIONAL SPECIFICATION THERMAL WEED KILLING APPARATUS FOR DOMESTIC AND AGRICULTURAL USE We, ALISTAIR RENFREW JERRETT of 66/1 Songer Street, Stoke, Nelson, New Zealand (formerly of 35 Ridgeway, Stoke, Nelson, New Zealand), RICHARD LLEWELLYN VERNON, of 5 Hurman Street, Karori, Wellington, New Zealand and DONALD JOHN BELL, of 1007 High Street, Lower Huti, New Zealand, all New Zealand citizens hereby declare the invention for which we pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement:- (followed by page 1A) »'< ?. P/Vi-,. "" rL:'; ~ 7 NOV 237524 - i,\ - This invention relate* to the killing of undesirable plant or other biological material, commonly known as "weeds" or "pests", in gardening or agriculture.

The object of this invention is to provide the user with a method of and device for killing or rendering biologically inactive undesirable biological material without resorting to potentially hazardous and residually toxic chemicals. In addition, the invention can be applied in a selective manner to targeted organisms with minimal damage to surrounding plants or animals or, if desired, in a non-specific manner.

Accordingly, the present invention may broadly be said to consist in a portable device suitable for killing biological material in situ comprising: (a) a portable, refillable, self-contained reservoir for water; (b) heating means spaced apart from said reservoir to heat water from said reservoir to provide steam; (c) means to supply water from said reservoir to said heating means, said supply means including an elongated tube through which water can flow from said reservoir to said heating means; and (d) means for directing steam generated by said heating means onto said biological material.

The heating means can comprise electrical induction means, liquid, gaseous or solid fuel combustion means or an electrical heating element.

In a convenient form, the heating means comprises a heating unit, a retaining means and a receiving means; wherein the receiving means receives water from the water supply means and directs it to the retaining means, the retaining means is connected to the steam directing means, and retains water so that it can be heated by the heating unit by conduction or radiation, and can then exit via the directing means as steam.

Preferably the water supply means includes a metering means.

Conveniently the water supply means includes a pump, most conveniently an electric pump. • - 237524 Alternatively the water supply means utilises gravity to supply water from said water reservoir to the heating means.

In one embodiment the steam directing means comprises at least one nozzle, and optionally further comprises a confining means for substantially confining steam to selected biological material.

Optionally the device includes an insulated handle portion and the heating means is located within the handle portion.

In another aspect, the invention provides a method of killing or controlling biological material comprising the steps of utilising a device as defined above to generate steam and applying the steam to the biological material.

The invention is broadly as defined above but also includes the embodiments shown in accompanying Figures 1 to 3.

The invention in one form uses a single jet of steam to thermally damage selected biological material. Steam has been selected specifically as the heating agent because of the high energy content of the gas due to the relatively high latent heat of vaporisation of water, the ease of which it can be directed and the relatively low temperature at which the gas is delivered (thereby ensuring a lower fire risk than that which would be associated with radiant heat or hot gas). The gas is also non-toxic and relatively harmless when cool.

The steam for the jet is generated by a portable steam generator. In one form of the device, shown in Figure 1, the jet of steam is generated by electrical healing of water in a low pressure vessel. The vessel is constructed of heavy gauge moulded plastic (1) and is intended to operate at a working pressure of approximately 0.5 to 1.0 Bar (approximately 107"C to I2I°C) and in this form the device has a carry handle built in to the filler cap (2) and a pressure relief valve (3). The steam is applied to the desired point via the flexible hose (4) connected to the insulated hand-piece (5) shown in Figure I A. Ilie insulated haiul-piecc is connected to the ahimiimifn~H»be-(6) which finally I ■ :ce j - 7 NOV 1994 237524 dispenses the steam and any condensate. In this form attachments can be fitted to the end of the aluminium tube (6) with the purpose of increasing the contact time of the steam to the desired material and/or increasing the effective spread of the steam jet.

Figure 2 shows a second configuration in which the steam jet is generated by water sprayed or dripped on a heated surface (1). In this form of the invention the water used for the steam generation is not heated until it contacts the heat surfaces of the tube (1). The flow of water in this and the following configurations can be produced from a low pressure, portable, hand pumped spray unit, an electrical or manual pump drawing from a portable reservoir or by gravity feed from a portable or other reservoir. In the form shown in Figure 2 the water is sprayed onto the electrically heated element (1) from the tube and nozzle assembly (2).

The steam generated by the action of heating the water sprayed from tube (2) is contained within the chamber (3) and directed to the desired point via tube (4). The device is held via the insulated hand-piece (5).

Other configurations for the heating element are possible. These might include a flat element over which the water flows or heating in a tube by electrical induction.

Figure 3 shows a third form of the device in which the steam required for thermal inactivation of the biological material is produced by heating water using a liquid fuel or gaseous fuel flame. This is another hand-held form. In this form the flame and hot gases (1) from the burner (2) are conducted over the water heating coil (3) by the tubular metal duct (4). Water is introduced into the heating coil (3) via the tube (5). The heating coil (3) is connected to the tube (6) which directs the steam generated to the required point. The tubular insulating hand-piece (7) is separated from the flame duct (4) by the air space (8).

A fourth form of the device (not shown) is one in which the steam is produced by introducing water into a hot gas stream. In this form the hot gas stream can be produced either by using a fan to pass air over electrical heating elements or the exhaust gases of ;i "blow torch-like" flame. The hot gas is then used to evjipjoratc water which has been 237524 sprayed or dripped into the gas stream. The steam and heated air stream is then conducted to the desired point via a tubular duct.

It is obvious that the fourth form described above could be easily altered to utilise a liquid, solid or gas fuelled burner to produce the hot gas stream.

The forms shown in this specification are examples of many possible forms of hand-held devices for the thermal inactivation of biological material known as "weeds" or "pests" using steam. It is obvious that larger but still portable units could be constructed using the same principles as apply to these units. Such units might be designed to be carried by motor vehicles such as tractors or trucks.

Claims (22)

237524 WHAT YVH CLAIM IS:

1. A portable device suitable for killing biological material in situ comprising: (a) a portable, refillable, self-contained reservoir for water; (b) heating means spaced apart from said reservoir to heat water from said reservoir to provide steam; (c) means to supply water from said reservoir to said heating means, said supply means including an elongated tube through which water can flow from said reservoir to said heating means; and (d) means for directing steam generated by said heating means onto said biological material.

2. A device as claimed in claim 1 wherein said heating means comprises electrical induction means to heat water to provide steam.

3. A device as claimed in claim 1 wherein said heating means comprises liquid, gaseous or solid fuel combustion means to heat water to provide steam.

4. A device as claimcd in claim 1 wherein said heating means comprises an electrical heating element.

5. A device as claimed in claim 1 wherein the heating means comprises a healing, unit, a retaining means and a receiving means; wherein the receiving means reeeives water from the water supply means and dirccts it to the retaining means, the retaining means is connected to the steam directing means, and retains water so that it can be heated by the heating unit by conduction or radiation, and can then exit via the directing means as steam.

6. A device as claimed in claim 5 wherein the heating unit comprises a resistive heating element. - () - ^ •

7. A device as claimed in claim 5 wherein the heating unit comprises a liquid, gaseous or solid fuel combustion means. S.

A device as claimed in claim 5 wherein the heating unit comprises an electrical induction means. V.

A device as claimed in any one of claims 1 to 8 wherein the water supply means includes a metering means.

10. A device as claimed in any one of claims 1 to 9 wherein the water supply means includes a pump.

11. A device as claimed in claim 10 wherein said pump is an electric pump.

12. A device as claimed in any one of claims 1 to 9 wherein the water supply means utilises gravity to supply water from said water reservoir to the heating means.

13. A device as claimed in any one of claims 1 to 12 wherein the steam directing means comprises at least one nozzle.

14. A device as claimed in any one of claims 1 to 13 wherein the steam directing means further comprises a confining means for substantially confining steam to selected biological material.

15. A device as claimed in any one of claims 1 to 14 wherein the steam exits the steam directing means at a low pressure.

16. A device as claimcd in any one of claims 1 to 15 wherein the dcvice includes an insulated handle portion and the heating means is located within the handle portion. r

17. A device as claimed in anv one of claims I to 16 wherein the biological material is plant matter. IS.

A device as claimed in claim 17 wherein the plant matter is a weed. ll>.

A method of killing or controlling biological material comprising the step of utilising a device as claimed anv one of claims 1 to 17 to generate sfeam and applying the steam to the biological material.

20. A method as claimed in claim 19 wherein the biological material is plant matter.

21. A method as claimed in claim 20 wherein the plant matter is a weed.

22. A device substantially as herein described with reference to any one of the accompanying drawings. ALIST(ZtNF&lrt vitMP71"; uJueWbLLV/V './CftoO -XHrO 6ULL. By Ih" iKj'JlltS A J PAliK & SON