Torches and burners for flame cultivation and flaming

Details Torches and burners for flame cultivation and flaming Torches and burners for flame cultivation and flaming

2000-04-04

2001-07-10

Yeung, James C. (Department: 3743)

Combustion

Flame holder having attached handle

C431S343000, C431S242000, C431S248000, C126S27120R

Reexamination Certificate

active

06257875

ABSTRACT:

FIELD OF THE INVENTION
The present invention is concerned with flame cultivation burners and flaming torches which find application in agricultural and forrestal land management, road surface asphalting and similar tasks which require application of heat or a flame onto objects. In particular, the present invention is concerned with flame cultivation burners and flaming torches which use liquefied petroleum gas (LPG) as a fuel source for the bumers, and relates to an improved burner with integral fuel vaporiser and improved hand-held flame cultivation and flaming torches.
BACKGROUND OF THE INVENTION AND PRIOR ART
Flame treatment or “flame cultivation” is well known in agriculture and horticulture to control weeds and pests that adversely affect arable land. There is a large body of published patent literature concerned with many aspects of this technology, U.S. Pat. No. 2,408,328 setting forth the basic principles of flame cultivation, and thus, reference should be made to this U.S. patent for a detailed explanation of the technique.
Flame cultivation and flaming burners can be incorporated in hand-held torch devices carried by a person for localised or small scale flame cultivation to control weeds and plant pests, particularly in hard to access locations, such as drainage trenches, irrigation ditches and the like, as well as for igniting vegetation for small and large scale clearance of arable land, back-burning operations and the like. Such burners also find use in motorised flame cultivators incorporating a bank or array of burners supported on a boom carried or drawn by a self-propelled agricultural vehicle for large scale surface flame cultivation of arable land.
In the following, the expression torch head and burner will be used synonymously to denote a hollow prismatic or tubular skirt or casing that houses at least one gas delivery jet arrange to emit a jet of combustible fuel (either liquid or gaseous) that is combusted at least partially within the casing so as to generate a flame that is discharged under draft or pressure from an appropriately shaped burner casing mouth. The specific configuration and constructional elements of a flame cultivation and flaming torch heads can vary greatly and is influenced by factors such as the type of application the device is mainly intended for, eg hand-held torches vs torch batteries in an agricultural implement, whether direct flaming or hot combustion gas weeding is to be employed, the fuel supply source, the need for fuel supply regulators and control devices, whether continuous or intermittent high intensity heat is to be applied, the need for a pilot flame or igniters, the required heat energy output rate, burner type (ie combustion of priorly vaporised or vaporising liquid fuel), etc. Accordingly, the large number of patent specifications in this field of technology (international patent classes IPC A01 M 15, F23 D 11, F23 D 14) concern improvements/inventions that are specific to each burner type as well as their specific application.
Agricultural Flame Cultivators
In the field of flame cultivation of large tracts of land, U.S. Pat. No. 3,164,927 (Holloway) discloses a flame cultivator in which a plurality of main burners are supported on a traverse rig or boom mounted on the rear end of a tractor. Two auxiliary burners arranged to direct a gas jet obliquely with respect to the main burner streams (but not intersecting therewith) are mounted on opposite sides outside the prismatic casing of the main burner. All gas delivery jets are supplied with gaseous fuel (butane or propane) from a central supply tank mounted on the tractor via a central supply line and branch lines having regulator valves disposed therein. The gaseous fuel is usually delivered in equal amounts and with equal pressure to the identical fuel delivery jet nozzles, and a mixture of gas and air is created in the burners that is ignited for flame cultivation purposes. It is readily understandable that gas delivery pressure for each jet nozzle can be individually controlled by the associated control valve in the gas delivery lines to each burner to suit varying operational requirements in relation to energy output and flame temperature at each burner. It is also readily apparent that where the burner configuration is modified to use gaseous fuels, an additional vaporiser will be required, as the fuel is conveniently stored in liquid form in a tank, in order to vaporise or convert the liquid fuel into its vapour or gaseous form prior to delivery to the burners. A similar implement is disclosed in U.S. Pat. No. 3,543,436 (Baxter) and U.S. Pat. No. 3,425,407 (Furman et al).
Hand-operated Flame Cultivation and Flaming Torches
Hand-operated torches represent another area of application and are mostly used to destroy plants, e.g. bush, forest undergrowth and the like, in land clearing operations. Such type of torches, referred to as flaming torches, will generally be constructed to generate high intensity flames capable of setting aflame dead wood and live plants alike, whereas with hand-held flame cultivation torches the aim is to destroy unwanted weeds and vermin without setting the crop plants on fire, and thus torch designs are preferred which generate sufficient heat to destroy the cells of young weeds and crop pests without use of high intensity flames that will ignite the vegetation. This aspect is of particular importance in arid zones.
Hand-held torches for agricultural as well as other purposes, e.g. road works, roof taring and the like, generally share a number of common structural features. They have an elongate handle tube or rod which carries at one of its distal ends the torch head which incorporates one (or more) burners. In simple designs, the fuel supply line is connected directly to an LPG hose that is secured at a regulator at the outlet valve of an LPG storage cylinder. More elaborate torches incorporate at the torch itself a deadman shutter (valve) to turn on or off fuel supply to the burners, as well as other regulators and pressure gages in the fuel supply line.
The size of the LPG cylinder of non hand-held torches would usually be determined by the required heat output capacity of the torch burners (as represented by fuel consumption). With hand-held torches though, manoeuvrability of the torch in the field is paramount. For example, small hand-held torches such as those manufactured by Primus and sold under the label “Gardener” and which are mainly intended for the hobby gardener, use small capacity, disposable or refillable LPG cartridges having a self closing connecting valve. Such cartridges can have a capacity of 1 to 3 litres and are attached directly to a fitting at the end of the torch handle. The main limitation as to possible cylinder sizes, however, will generally be their weight. The cylinder must be able to be carried by the torch operator. This is usually accomplished either using a customised back pack or a non-motorised cart. Having regard to restrictions imposed by the location where the torch is to be used and the surrounding terrain, the back pack arrangement is often used in flame cultivation and vegetation torching applications where a larger LPG fuel supply is required, e.g. 5 to 15 litres cylinder capacity.
Smaller hand-held torches incorporate a torch burner arrangement that is relatively lightweight. However, heavy duty, high capacity torch burner heads can have a substantial weight, eg 2 to 4 Kg. Whilst this may not seem much, when mounted at the distal end of a long tubular torch handle of 1.5 m or longer, proper balancing of the torch head by an operator is often difficult and tiring.
Torches with Integral Vaporisers
U.S. Pat. Nos. 3,357,474 and 3,486,497 (both granted to Pivonka) describe torches with combined LPG fuel vaporiser and burner arrangements within a burner casing or head that can equally be integrated in hand-held torches for flame cultivation and igniting vegetation (flaming), as well as large scale flame cultivation implements and machinery.
U.S. Pat. No. 3,357,474 in particular discloses a comb

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