US3486497A

US3486497A - Method and apparatus for killing weeds

Info

Publication number: US3486497A
Application number: US674292A
Authority: US
Inventors: Ralph C Pivonka
Original assignee: Warren Petroleum Corp
Current assignee: Chevron USA Inc; Warren Petroleum Corp
Priority date: 1967-10-10
Filing date: 1967-10-10
Publication date: 1969-12-30
Anticipated expiration: 1986-12-30

Description

Dec. 30, 19.69

R. c. PIVONKA METHOD AND APPARATUS FOR KILLING WEEDS 2 Sheets-Sheet 1 Filed Oct. 10, 1967 INVENTOR. RALPH C. P/I O/VKA Dec. 30, 1969 R. PlVONKA 3,486,497

METHOD AND APPARATUS FOR KILLING WEEDS Filed Oct. 10, 196'? 2 Sheets-Sheet 2 Pig. 2

INVENTOR.

RALPH C. P/VO/V/(A United States Patent 3,486,497 METHOD AND APPARATUS FOR KILLING WEEDS Ralph C. Pivonka, La Crosse, Kaus., assignor to Warren Petroleum Corporation, Tulsa, Okla., a corporation of Delaware Filed Oct. 10, 1967, Ser. No. 674,292

Int. Cl. F23c 5/00; F23d 11/44 US. Cl. 126271.2 6 Claims ABSTRACT OF THE DISCLOSURE This invention relates to the killing of weeds and more particularly to a method and apparatus for killing weeds with a flame.

It is frequently desirable to kill the weeds along the shoulders of a road, in irrigation or drainage ditches, or around equipment located in an open field. Sometimes it is desirable to ignite brush over a large area to start a back fire to prevent spread of forest fires. One method that has been used to kill weeds is by directing a flame or hot combustion gases against weeds. Because of the very large areas of road shoulders, irrigation ditches, etc., a burner capable of releasing heat at high rates over a large area is desired.

The burners heretofore available either for flame cultivation or nonselective killing of weeds have had a limited heat release capacity Generally, the ignition of the fuel occurs within a torch from which flame and hot combustion gases are discharged and directed against the weeds to be killed. The large volume of hot gases that pass through the burner necessitate a burner of large size even for very low heat release capacities. Moreover, the blast of hot gases discharged from the burners frequently cannot penetrate deeply into brush or through thick growths of weeds because of the shielding of the foliage. Much of the heat released by the combustion is wasted by being diverted from cont-act with the weeds.

This invention resides in a method and apparatus for the nonselective killing of weeds in which a fine stream of liquid fuel is discharged at a high velocity through an orifice onto the area to be cleared and simultaneously moving a flame directed onto that area to ignite the fuel substantially at the location of impact of the fuel stream with the ground or other solid surface. In the apparatus, an orifice of small diameter serves as an outlet for a liquid fuel line to discharge the fine stream of fuel, and a vaporizing torch is positioned to discharge a flame in the same direction as the liquid stream.

In the drawings:

FIGURE 1 is a longitudinal sectional view of the weed burner of this invention;

3,486,497 Patented Dec. 30, 1969 ice FIGURE 2 is a front elevational view of the weed burner mounted on a tractor; and

FIGURE 3 is a horizontal sectional view through one type of orifice cap to be used for controlling the spray pattern of liquid fuel used to burn the weeds.

Referring to FIGURE 1 of the drawings, the weed burner indicated generally by reference numeral 10 has an LPG supply line 12 for connection to a fuel storage tank of suitable size depending upon the'use of the particular burner. Any fuel which is sufliciently volatile at atmospheric temperatures to rapidly form a combustible mixture of fuel and air that can be ignited by momentary contact with a flame can be used. A preferred fuel is LPG. LPG has a high enough vapor pressure to provide the pressure required to operate the liquid spray and torch without auxiliary equipment. 'It also vaporizes quickly to form a combustible gaseous mixture that is immediately ignited on contact with a flame. The term LPG as herein used includes propane, butane, mixtures of propane and butane, and mixtures of propane, butane and higher boiling hydrocarbons such as pentane and hexane. Higher boiling hydrocarbons such as gasoline and kerosene can be used, but those fuels require some means for raising the pressure high enough to operate the liquid spray and torch. The necessary pressure can be obtained by mixing a volatile fuel such as propane with kerosene. Mixtures of kerosene or furnace oil with propane are advantageous in causing a longer burning flame with increased heat release as compared With propane alone. Fuels less volatile than kerosene are diflicult to ignite and are not suitable unless mixed with propane or a similar fuel. For convenience, the fuel is hereinafter referred to as LPG in the description of this invention.

LPG supply line 12 is connected to a T 14 from which a liquid discharge line 16 extends laterally and then changes in direction in an L 18. The end of discharge line 16 is closed by an orifice cap 20 having an orifice 21 therein for spraying liquid LPG directly onto the ground. Any desired arrangement of orifice in the orifice cap can be employed to give the desired spray pattern. In the orifice cap illustrated in FIGURE 3 of the drawings, three orifices are provided to distribute streams of liquid LPG over a relatively wide area. The orifices are designed to discharge a high velocity stream of small diameter. A single orifice 7 inch in diameter has been found to give a long penetrating flame when LPG is the fuel. Three orifices inch in diameter, such 'as illustrated in FIGURE 3, will give a fan-shaped flame.

A control valve 22 in line 16 permits adjustment of the rate of discharge of LPG from the weed burner. In the embodiment illustrated in FIGURE 1, a solenoid-operated valve 24 is provided to allow on-oif remote control of the flow. In a portable unit, a solenoid valve, such as valve 24, will not be necessary and may be replaced with a lever-operated, quick-closing valve if quick closing means are desired.

A torch supply line 26 provided with a control valve 28 and solenoid-operated valve 30 extends from T 14 in a direction parallel to the major part of discharge line 16 to a torch indicated generally by reference numeral 32. a

Supply line 26 is connected through a bushing 34 to a vaporizer tube 36. Vaporizer tube 36 is enclosed within a thimble 38 held in place around the vaporizer tube 36 by a coupling 40 screwed on the outer surface of bushing 34. A helical coil 42 in the annular space between the tube 36 and thimble 38 increases the distance the gases must travel and thereby improves transfer of heat to the fluids in the torch.

Secured to the outer surface of the thimble 38 are a pair of nozzle assemblies 44 which have restricted outlets 46 for discharging vaporized LPG at a high velocity. Holes are drilled in the wall of the nozzle assemblies 44 and tube 36 to provide passages 45 through which LPG flows into the nozzle assemblies 44. A sleeve 47 surrounds the nozzle assemblies 44 and is spaced therefrom to allow flow of air through the sleeve toward its outlet end 49. The outlet end of the sleeve is approximately in line with the orifice cap 20 while the tube 36 and thimble 38 extend beyond the orifice cap. The torch 32 is described and claimed in my application Ser. No. 482,082, field on Aug. 24, 1965, now Patent No. 3,357,474 and entitled Combined Fuel Vaporizer and Torch.

In the operation of the weed killer, the valve 28 and valve 30 are opened to allow LPG to flow through the torch supply line 26 and tube 36 into thimble 38. The LPG then flows back through the annulus between tube 36 and thimble 38, into nozzle assemblies 44, and out through orifices 46. The LPG discharged from orifice 46 is then ignited by any suitable means. The flame resulting from ignition of LPG heats thimble 38 which transfers heat to the LPG flowing therethrough and vapor zes that LPG, whereupon the LPG is discharged through nozzles 46 at a high velocity. Air is drawn into the upper open end of sleeve 32 for mixture with LPG within the sleeve. Valve 28 is adjusted to provide a flame of the desired length.

Valves

22 and 24 are opened to allow liquid LPG to flow through liquid discharge line 16 and orifice 21 to discharge a stream of liquid directly onto the area or growth to be flamed. Upon vaporization at the ground level or deep within brush and mixing with air to form a combustible mixture, the LPG is ignited by the flame from the torch 32. Moving the torch and stream of LPG simultaneously over the area to be flamed insures quick and complete ignition before vapors of fuel move away from the target area. A bracket 43 holds tube 16 and burner 32 in fixed relation to one another to insure synchronization of their movement.

A combustible mixture of air and LPG is formed onl after vaporization of the LPG after striking the target area. Combustion then occurs at the base of the plants where the largest amount of heat is required for killing weeds. The tendency of propane or butane to seek low levels when vaporized, and especially when cooled by natural vaporization, aids the flames in adhering to the ground long periods. In this manner, the weed burning device of this invention allows eflicicnt utilization of the heat of combustion with resultant fuel savings of the order of 50 percent or even more. Loss of heat to the atmosphere at some distance from the weeds is minimized.

For burning of weeds along roadways or irrigation ditches, one or more weed burners are mounted on a tractor such as illustrated in FIGURE 2 of the drawings. Referring to FIGURE 2, a tractor indicated generally by reference numeral 50 is shown with a front-mounted platform 52 on which a tank of LPG 54 is mounted. The tractor 50 is provided with a boom 56 which may be raised and lowered by the hydraulic system of the tractor. Mounted on the outer end of the boom 56 is a burner 10. It will be appreciated that any number of desired burners may be mounted on the boom, and they can be inclined at any desired angle to discharge LPG to provide the desired pattern of burning. The individual burners can be made up with two or more nozzles for discharging liquid in combination with a single torch.

In the operation of the apparatus illustrated in FIG- URE 2, the solenoid valve 30 is opened by a suitable switch within reach of the driver. Valve 28 is opened and torch 32 lit. Valve 22 is opened to give the approximate desired flow of LPG and then the solenoid valve 24 is opened from a position near the drivers seat. The tractor is then driven along the area to be treated. Because of the large amount of heat of combustion available in the liquid fuel, it is possible to drive the tractor at rates as high as fifteen miles per hour and effectively kill weeds along the side of the road.

The weed burner of this invention allows the liberation of large quantities of heat from a compact apparatus. Delivery of the fuel as a liquid directly onto the ground causes the volume of the LPG in the burner to be small. By discharging a liquid stream of the LPG, the fuel can be made to penetrate deeply through brush or other foliage before ignition and thereby result in liberation of heat at locations which are only difiiculty accessible in conventional burners.

I claim:

1. Apparatus for clearing weeds from an area comprising a fuel feed line connected at its inlet end to a liquid fuel supply line, a heat exchange section in said fuel feed line between the inlet end and discharge end thereof, a burner nozzle connected to the discharge end of the fuel feed line positioned to direct burning fuel discharged therefrom away from the liquid fuel supply line and into contact with the heat exchange section, a sleeve surrounding and spaced from the fuel feed line and burner nozzle and extending from the burner nozzle in the direction of discharge of fuel therefrom, a liquid fuel discharge line connected at its inlet to the fuel supply line, an orifice plate at the discharge end of the liquid fuel discharge line having an opening therein adapted to discharge a thin stream of liquid fuel, said liquid fuel discharge line extending outside of, but adjacent to, the sleeve, and a valve in the liquid fuel discharge line for control of the flow of liquid fuel therethrough.

2. Apparatus as set forth in claim 1 in which the discharge end of the sleeve and of the liquid fuel discharge line are in substantially the same plane.

3. Apparatus for clearing Weeds from an area comprising a fuel feed line connected at its inlet end to a fuel supply line, a burner nozzle connected to the discharge end of the fuel feed line, a sleeve surrounding and spaced from the fuel feed line and burner nozzle and extending from the burner nozzle in the direction of discharge of fuel therefrom, a liquid fuel discharge line connected at its inlet end to the fuel supply line and having its discharge end at a substantially larger distance than the burner nozzle from the liquid fuel supply line, an orifice plate at the discharge end of the liquid fuel discharge line having an opening therein adapted to discharge a thin stream of liquid fuel, said liquid fuel discharge line extending outside of the sleeve, and a valve in the liquid fuel discharge line for control of the flow of liquid fuel therethrough.

4. Apparatus as set forth in claim 3 in which the liquid fuel storage tank is mounted on a tractor, a boom extends laterally from the tractor, and the liquid fuel discharge line and torch are mounted on the boom adjacent its outer end.

5. Apparatus as set forth in claim 4 including valves in the liquid fuel discharge line and liquid fuel feed line, and means operable from the drivers seat of the tractor for operating the valves.

6. Apparatus for clearing weeds from an area comprising a liquid fuel discharge line connected to a fuel supply line, an orifice plate at the discharge end of the liquid fuel discharge line having an opening therein adapted to discharge a thin stream of liquid fuel, a valve in the liquid fuel discharge line for control of flow therethrough, a fuel feed line connected at its inlet end to the fuel supply line, a thimble enclosing and spaced from the end of the fuel feed line remote from the fuel supply line a nozzle assembly mounted on the thimble 5 6 adjacent the end of the thimble nearest the fuel supply 2,485,391 10/1949 Lasseigne et a1. line, a passage through the wall of the thimble into the 2,497,939 2/1950 Garraway et a1. 43191 X nozzle assembly, said nozzle assembly having an outlet of 2,833,272 5/1958 Kennepohl 126271.2 small diameter positioned to discharge fuel to the end of l the thimble remote from the fuel supply line, and a valve FOREIGN PITTENTS in the fuelfeed line, 5 108,620 10/1939 Australia.

References Cited CHARLES I. MYHRE, Primary Examiner UNITED STATES PATENTS Cl. 1,008,733 11/1911 Roy et a1 43-144 10 431 243 1,820,383 8/1931 Elze 431236