U.S. patent application number 11/469850 was filed with the patent office on 2007-04-19 for portable steam and heat generator for pest control.
Invention is credited to Steven Vaughan.
Application Number | 20070084422 11/469850 |
Document ID | / |
Family ID | 32831568 |
Filed Date | 2007-04-19 |
United States Patent
Application |
20070084422 |
Kind Code |
A1 |
Vaughan; Steven |
April 19, 2007 |
PORTABLE STEAM AND HEAT GENERATOR FOR PEST CONTROL
Abstract
The present invention is directed to an apparatus for directing
at least one of steam, hot water and hot water vapor along with hot
air onto vegetation, the apparatus comprising a source of water and
a source of fuel connected and supplying water and fuel to steam
generator having a boiler heated by a burner, the apparatus
including a valve arrangement between the source of water and fuel
and the steam generator, the valve arrangement having a STAND-BY
mode and an ON mode, the STAND-BY mode of the valve arrangement
providing for a reduced flow of water and fuel to the steam
generator to maintain a pilot flame in the burner and sufficient
water flow to reduce the response time of the apparatus to generate
at least one of steam, hot water and hot water vapor along with hot
air as needed when the valve arrangement is placed in the ON
mode.
Inventors: |
Vaughan; Steven; (Victoria,
CA) |
Correspondence
Address: |
Dennison Associates
Suite 301
133 Richmond Street West
Toronto
ON
M5H 2L7
CA
|
Family ID: |
32831568 |
Appl. No.: |
11/469850 |
Filed: |
September 2, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11198354 |
Aug 8, 2005 |
7100540 |
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11469850 |
Sep 2, 2006 |
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PCT/CA04/00156 |
Feb 9, 2004 |
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11198354 |
Aug 8, 2005 |
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Current U.S.
Class: |
122/451R |
Current CPC
Class: |
B05B 7/20 20130101; F22B
1/22 20130101; F22D 5/26 20130101; Y10S 122/10 20130101; B05B
9/0838 20130101; B05B 7/201 20130101; F22B 1/26 20130101; A01M
21/04 20130101; B05B 9/085 20130101; B05B 9/0888 20130101; A01M
15/00 20130101; B05B 9/002 20130101 |
Class at
Publication: |
122/451.00R |
International
Class: |
F22D 5/26 20060101
F22D005/26 |
Claims
1. An apparatus for directing at least one of steam, hot water and
hot water vapor along with air heated by a burner onto a target
area, the apparatus comprising a source of water and a source of
fuel connected and supplying water and fuel to a steam generator
having a boiler heated by a burner, the apparatus including a valve
arrangement between the source of water and fuel and the steam
generator, the valve arrangement having a STAND-BY mode and an ON
mode, the STAND-BY mode of the valve arrangement providing for a
reduced flow of water and fuel to the steam generator to maintain a
pilot flame in the burner and sufficient water flow to reduce the
response time of the apparatus to generate at least one of steam,
hot water and hot water vapor along with hot air as needed when the
valve arrangement is placed in the ON mode.
2. An apparatus according to claim 1, wherein the valve arrangement
includes two controls, a first control for controlling the flow of
water and a second control for controlling the flow of fuel.
3. An apparatus according to claim 2 wherein both the first and
second controls comprise an ON position, an OFF position and a
STAND BY position, the STAND BY position permitting sufficient flow
of fuel to maintain a low flame in the burner and a reduced flow of
water.
4. An apparatus according to claim 3, wherein both the first and
second controls are controlled by a single trigger switch.
5. An apparatus according to claim 4 wherein the trigger switch is
provided with two positions, a first position which activates both
the first control and second control to the ON position and a
second position which activates both the first control and the
second control to the STAND BY position.
6. An apparatus according to claim 2 wherein each of the first and
second controls comprise the combination of an ON-OFF valve to
provide for no flow or full flow of water and fuel and a bypass
line with a restricted orifice which bypass the ON-OFF valve to
provide for a reduced flow of water and fuel.
7. An apparatus according to claim 1 wherein the valve arrangement
further includes a means for providing varying flow rates of water
to the flash boiler to adjust the ratio of steam, superheated
steam, hot water and hot water vapor for application to the target
area.
8. An apparatus according to claim 7 wherein the means for
providing varying flow rates comprises an adjustable needle valve
for the water supply.
9. An apparatus according to claim 6 wherein the adjustable needle
valves are provided with a plurality of preset positions to vary
the amount of water provided to the steam generator.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S. Ser. No.
11/198,354 filed Aug. 8, 2005 which is a continuation-in-part of
PCT/CA2004/000156 filed Feb. 9, 2004.
FIELD OF THE INVENTION
[0002] The present invention is directed to an apparatus for
controlling pests among other uses, particularly vegetation or
weeds using a blast of hot air and steam, hot water or hot water
vapor. In particular, the present invention is directed to an
apparatus having a valve arrangement to maximize operation of the
apparatus.
BACKGROUND OF THE INVENTION
[0003] The control of unwanted pests, such as vegetative growth, is
utilized to improve aesthetic appearance as well as removing the
noxious pests or vegetation. In the past, one of the most common
methods of controlling such unwanted growth was through the
application of pesticides to the vegetation. Such pesticides,
particularly herbicides, were commonly applied by spraying a liquid
herbicide or through spreading of powders or granules. However, in
recent years the use of herbicides has met with increased
resistance owing to environmental, health and safety concerns.
Herbicides can contaminate soil, air, groundwater and desirable
vegetation and may cause health problems to those exposed to such
chemicals. In view of these problems, the use of herbicides has
been restricted or in some cases completely banned in many
jurisdictions.
[0004] Another common method of controlling unwanted vegetative
growth is through physical removal of the plant. This method has
drawbacks in that it is time consuming, labor intensive, physically
demanding and disturbs the soil surface, exposing more weed seed.
In addition if all of the plant material is not removed and some of
the root structure remains, the plant may regrow and have to be
removed yet again.
[0005] As environmental concerns are reducing the use of
pesticides, and the prohibitive costs and inefficiencies of manual
weeding become apparent, the use of heat and/or steam for
vegetation control is gaining popularity. Heat coagulates plant
protein, destroying plant cells, disrupting vascular flow and
respiration. Also waxy protective leaf coatings are removed,
promoting dehydration and death of the plant. Studies have shown
that exposure to 80 C. (176 F.) for one second can kill vegetation.
Also steam or moist heat is superior to flame or dry heat for
weeding as damp air transfers heat more readily, and is easier to
apply in a downward direction (hot, dry air rises and diffuses
faster). Steam or moist air is less likely to cause accidental
fires and thus is safer than flame or dry heat.
[0006] Recently, the use of heat to kill unwanted vegetation has
been utilized and a number of apparatus to apply heat, generally in
the form of hot water or steam have been proposed. Examples of such
apparatus are shown in U.S. Pat. Nos. 5,385,106, 5,430,970,
5,927,601, 5,946,851, 6,029,589, 6,047,900, and 6,321,037, PCT
Patent Application WO 00/22926 and New Zealand Patent Application
237,524 among others.
[0007] U.S. Pat. No. 5,385,106 describes cart, backpack, and
vehicle mounted apparatus which utilize propane or electricity to
heat water in a chamber which is then delivered along piping for
application to the plant. One problem with this apparatus is that
the heated water must travel along the tubing before application to
the plant which may cause some cooling of the water. U.S. Pat. No.
5,430,970 describes an apparatus including an endless,
ground-engaging belt, or apron, disposed immediately aft of a hot
water spray. When hot water is sprayed on the weeds and
undergrowth, the sprayed vegetation is not only compressed by the
apron, but also heat from the water is retained therein, insulated
from ambient conditions by the apron.
[0008] U.S. Pat. Nos. 5,927,601 and 6,047,900 describe a vehicle
mounted apparatus for the application of pressurized hot water to
vegetation particularly along roadside berms. The apparatus has a
boiler arranged to heat water supplied under pressure from a water
tank and then pass the heated water under pressure to an applicator
head. Once again, the heated water must travel along extensive
piping which can result in cooling of the water before it reaches
the plant.
[0009] U.S. Pat. No. 5,946,851 describes a weed killing apparatus
having a hollow chamber with an air inlet and an open hot air
outlet, a source of compressed air to provide an air flow and a
burner assembly for heating the air so that the air exits from the
outlet as a blast of hot air and a means for introducing moisture
to the heated air so that the plants are wetted and heated to kill
them.
[0010] U.S. Pat. No. 6,029,589 describes a portable steam weed
killing apparatus having an electrically powered steam generator
which generates steam and delivers it through flexible tubing to a
weed cover placed over the undesired plant. The apparatus, being
electrically powered is limited in the area which can be treated
which is dependent upon the length of extension cords and is thus
not suitable for large scale operation.
[0011] U.S. Pat. No. 6,321,037 describes a hand held dispenser of
hot water intended for weed control. The apparatus has a handle
containing a hose connection for connecting to a domestic water
supply, a flow regulator, a heating tube, an exit tube, and a
nozzle. The handle is connected to a tube which contains a main
electric heating element for heating the water as it flows from the
bottom to the top of the apparatus before being piped through the
exit tube to the nozzle. Once again, as the apparatus is powered by
household electrical supply and connected to the domestic water
supply, the range of operation of the apparatus is limited.
[0012] PCT Patent Application No. WO 00/22926 describes a large
tractor mounted unit which mixes hot gases and steam for
application to weeds in agricultural applications. The mixture of
hot gases and steam is mixed after the steam generator using
pressure and then applied to the desired area. This apparatus is
complicated to manufacture and operate.
[0013] New Zealand Patent Application No. 237,524 describes a
backpack mounted portable steam generator that generates steam
within the handle of the applicator and delivers the steam by means
of a tube to the target area. This apparatus suffers disadvantages
in that the user may be exposed to the hot gases at the handle and
the length of the tube may result in cooling of the steam, thereby
reducing effectiveness.
[0014] There thus remains a need for a simple, lightweight,
portable, and cost effective apparatus for applying steam, hot
water or hot water vapor and heat to unwanted vegetation to kill
the vegetation and which utilizes minimal energy while maximizing
efficiency in its operation.
SUMMARY OF THE INVENTION
[0015] The present invention is directed to an apparatus for
directing at least one of steam, hot water and hot water vapor
along with hot air onto vegetation, the apparatus comprising a
source of water and a source of fuel connected and supplying water
and fuel to steam generator having a boiler heated by a burner, the
apparatus including a valve arrangement between the source of water
and fuel and the steam generator, the valve arrangement having a
STAND-BY mode and an ON mode, the STAND-BY mode of the valve
arrangement providing for a reduced flow of water and fuel to the
steam generator to maintain a pilot flame in the burner and
sufficient water flow to reduce the response time of the apparatus
to generate at least one of steam, hot water and hot water vapor
along with hot air as needed when the valve arrangement is placed
in the ON mode.
[0016] In an aspect of the invention, the valve arrangement
includes two controls, a first control for controlling the flow of
water and a second control for controlling the flow of fuel.
[0017] In a further aspect of the invention, both the first and
second controls are controlled by a single switch.
[0018] In another aspect of the invention, both the first and
second control have an ON position, an OFF and a STAND-BY
position.
[0019] In yet another aspect of the invention, the valve
arrangement further includes a means for providing varying flow
rates of water to the flash boiler to adjust the ratio of steam,
superheated steam, hot water and hot water vapour for application
to the target area.
[0020] In yet another aspect of the invention, there is provided an
apparatus for producing a blast of at least two of steam,
superheated steam, hot air, hot water and hot water vapour for
application to a target area, the apparatus comprising a holding
means; a flash boiler heated by a burner, the flash boiler and
burner coupled to said holding means; a fuel container connected
and supplying fuel to the burner and a means for connecting the
apparatus to a domestic water supply to supply water to the flash
boiler, such that in use, fuel and water are supplied essentially
simultaneously to the flash boiler and the burner and a blast is
urged therefrom adjacent a target area.
[0021] In yet another aspect of the invention, there is provided an
apparatus for generating at least one of steam, hot water and hot
water vapor along with air heated by a burner for application to
unwanted vegetation. The apparatus comprises a wheeled cart
supporting a water container, a water pump and a fuel container, an
applicator wand comprising a holding means and an applicator head
coupled to the holding means. The applicator head comprises a
housing, an inlet and an outlet to define a cavity to accept a
flash boiler adjacent the outlet, the flash boiler comprising a
steam generator and a burner for heating the steam generator. A
first elongate hose connects the water container to a first control
located on the applicator wand, the first control controlling and
supplying a flow of water to the steam generator, and a second
elongate hose connects the fuel container to a second control
located on the applicator wand, the second control controlling and
supplying a flow of fuel to the burner. Both the first and second
controls are controlled by a single switch, such that when said
switch is activated, fuel and water are supplied essentially
simultaneously to said flash boiler and a blast of heated air and
at least one of steam, superheated steam, hot water and hot water
vapor is urged from the outlet to the unwanted vegetation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Preferred embodiments of the present invention are
illustrated in the attached drawings in which:
[0023] FIG. 1 is a perspective view of a first embodiment of an
apparatus for controlling undesired pests according to the present
invention for carrying as a backpack;
[0024] FIG. 2 is a perspective view partly in cross section of the
wand of the apparatus of FIG. 1;
[0025] FIG. 3 is a rear view of the apparatus of FIG. 1 being
carried by a user;
[0026] FIG. 4 is a perspective view of a second embodiment of an
apparatus for controlling pests according to the present invention
for mounting on a truck;
[0027] FIG. 5 is a perspective view of a third embodiment of an
apparatus of the present invention;
[0028] FIG. 6 is a perspective view partly in cross section of the
wand of the apparatus of FIG. 5;
[0029] FIG. 7 is a perspective view partly in cross section of a
fourth embodiment of an apparatus of the present invention;
[0030] FIG. 8 is a perspective view partly in cross section of a
fifth embodiment of an apparatus of the present invention;
[0031] FIG. 9 is a schematic view of a variable water supply
means;
[0032] FIG. 10 is a side elevation view in cross section of a
further embodiment of a flash boiler for use in the apparatus of
the present invention;
[0033] FIG. 11 is a side elevation view of an attachment for
treating roots for the apparatus of the present invention;
[0034] FIG. 12 is a perspective view of a further attachment for
the flash boiler of the present invention;
[0035] FIG. 13 is a side elevation view partly in cross section of
a further embodiment of an apparatus of the present invention;
[0036] FIG. 14 is a side elevation view partly in cross section of
the valve and handle assembly of the embodiment of FIG. 13; and
[0037] FIG. 15 is a perspective view of a further embodiment of the
apparatus of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0038] A preferred embodiment of the apparatus of the present
invention generates a blast of hot air and at least one of steam,
hot water or hot water vapor from an applicator head containing a
flash boiler heated by a burner, the flash boiler being located in
the apparatus adjacent to the outlet to apply the blast to a target
area. The apparatus is useful for many applications requiring a
blast of hot air and steam, hot water or hot water vapor such as
controlling pests through the application of hot air and steam, hot
water or hot water vapor directly to the pests only as needed.
Other possible uses include a steam cleaner for surfaces not
susceptible to heat damage or for heat activation of other
materials such as detergents or cleansers or other uses as set out
below. Preferably, the apparatus is for controlling pests,
particularly unwanted vegetation; however, the apparatus may also
be used to control other pests, such as insects, microbial
infestations, invertebrates such as mollusks or mussels, etc. The
apparatus preferably has an applicator wand for delivery of the
heat and steam, hot water or hot water vapor to the vegetation and
is characterized by the wand being provided with an applicator head
having a steam generator, preferably a burner assembly and a flash
boiler, located at the end of the wand, adjacent to or in close
proximity to the target area of application. The apparatus has a
water supply and fuel supply for the burner and steam generator,
the water and fuel being supplied to the burner and steam generator
through suitable hoses.
[0039] The apparatus of the present invention includes a valve
arrangement between the source of water and fuel and the steam
generator, the valve arrangement having a STAND-BY mode and an ON
mode. The STAND-BY mode of the valve arrangement provides for a
reduced flow of water and fuel to the steam generator to maintain a
pilot flame in the burner and sufficient water flow to reduce the
response time of the apparatus to generate at least one of steam,
hot water and hot water vapor along with hot air as needed when the
valve arrangement is placed in the ON mode.
[0040] Preferably, the apparatus is portable and may be mounted on
a backpack, wheeled cart, or vehicle, features the use of an
applicator head to generate steam, hot water or hot water vapor and
hot air for the primary purpose of vegetation and pest control.
Within the applicator head, the combustion of propane or a similar
fuel occurs to produce steam, hot water or hot water vapor and
surplus hot air, both of which are combined and applied to the
target area to control pests, especially unwanted vegetation such
as weeds. Water is provided to the applicator wand and preferably
pre-heated before being raised to delivery temperature within a
flame-heated steam generator, specifically a flash boiler. This
creates steam that mixes with the surplus heat from the flame to
produce super-heated steam, hot water, and hot air, all of which
are driven through the applicator tube on the end of the hand held
applicator wand by the pressure of the expanding steam and hot
gasses from the flame stream.
[0041] A first embodiment of the apparatus of the present invention
for backpack operation is illustrated in FIGS. 1 to 3 generally
indicated by the numeral 10. The apparatus 10 consists of a
backpack 12 having a container 14 for holding the water and fuel
supply and delivery means for delivering the water and fuel to the
applicator wand 16. The backpack 12 is provided with straps 18 by
which the container may be carried on a user's back. The interior
of the backpack container 14 is provided with a water tank 20,
capable of holding sufficient water for operation of the apparatus.
As will be explained in further detail below, owing to the design
of the apparatus, a few gallons of water is sufficient to allow the
operation for the apparatus for at least about 2 hours. The water
tank 20 is provided with a filler opening 22 and an outlet 24
connected to the applicator wand 16 through a suitable hose 26.
Preferably, the outlet 24 of the water tank 20 is provided with an
inline filter 28 for removing any debris or particulate matter
which may accumulate in the water tank 20 and which could affect
the operation of the downstream valves which will be described
below. In order to properly control the flow of water to the steam
generator, the water is preferably pumped through the hose by a
pump means located in the backpack 12. In the embodiment
illustrated, the pump means is a conventional hand pump 30 utilized
in back pack mounted liquid spray applicators but the pump means
could be electrically powered or use air or gas pressure. An
electrically powered pump means would preferably be a demand water
pump powered by rechargeable batteries. The pump would only operate
if the pressure drops below a preset limit. Thus, the pump only
operates as needed. As a further alternative, the pump may be
switched on when the trigger is pressed.
[0042] In a preferred embodiment, the apparatus is adapted for
retrofitting to a pesticide backpack spray apparatus by replacing
the spray wand of the backpack sprayer with the apparatus of the
present invention and adding a small fuel supply tank or cylinder.
The backpack tank is cleaned of pesticide residue and used as the
water container and the backpack integral pump is used to generate
the water pressure.
[0043] The backpack 14 carries a source of fuel for the burner
assembly. In the embodiment illustrated, the source of fuel is one
or more propane or pressurized gas or liquid fuel cylinders 32. The
outlet of the fuel cylinder is attached to a flexible pressurized
fuel line 34 which delivers the fuel to the applicator wand 16. As
a safety feature, a fuel shut off valve 36 is preferably provided
at the outlet of fuel cylinder 32 on the backpack 12.
[0044] The applicator wand 16 of this embodiment is designed for
one arm operation as illustrated in FIG. 3, and consists of a
forearm brace 40, a handle 42 with trigger controls, and a suitable
dimensioned metal tube or pipe 44 carrying fuel and water lines and
connected to the applicator head 46 containing the burner assembly
and steam generator. The applicator head 46 preferably has an
insulated, reflective, metallic wall 48 to maximize and focus heat
production. The applicator head 46 is dimensioned to produce the
desired steam and heat output while being able to be manipulated by
the user. Preferably, the applicator head 46 is tubular having a
diameter of between about 1 and 4 inches, more preferably about 1
to 3 inches, most preferably about 1.5 inches and a length of
between about 4 and 12 inches, more preferably about 6 to 10
inches, most preferably about 8 inches. These dimensions would be
adjusted depending upon the size of burner used and the desired
output of steam, hot water or hot water vapor and heat.
[0045] Referring to FIG. 2, the fuel line 34 is connected to the
handle 42 of the applicator wand 16 through a suitable connection
such as a quick connect fitting 50. Preferably, for ease of
handling, the fuel line 34 and water hose 26 are joined together
along most or all of their length. A valve 52 located in the handle
downstream from the quick connect fitting 50 regulates the fuel
flow to allow for fuel shut off and set the maximum fuel flow. A
fuel line 54 travels to the handle from the valve 52 to a control
valve 56 controlled by the trigger control 58. The control valve 56
has two positions--a "STAND BY" position, which permits a reduced
fuel flow to maintain a pilot light in the burner as will be
explained below and to provide low heat output, and an ON position
when the trigger control is activated which permits full fuel flow
and maximum heat. With this type of valve a control is provided to
regulate the flow of fuel in the "STAND BY" position to set the
pilot light. From the control valve 56, a fuel line 60 then travels
along the pipe 44 of the applicator wand 16 to the burner head 62
in the applicator head 46.
[0046] The water hose 26 is connected to the handle 42 of the
applicator wand 16, at which point, the water flow may be set or
tuned with a water metering valve 64 used to set the flow rate of
the water flowing through the hose 26. Preferably, the water
metering valve 64 is an adjustable needle valve, although other
types of valves such as a preset orifice valve may also be used to
provide the optimal desired flow rate of the water. From the water
metering valve 64, a water line 66 is attached to a second valve 68
controlled by the trigger control 58. The second valve 68 provides
reduced water flow in the "STAND-BY" position, and permits full
water flow in the "ON" position as will be described in detail
below. From the second valve 68, the water travels down a water
tube 70 along the applicator wand pipe 44 to a pre-heating assembly
72 within the applicator head 46. In the embodiment illustrated,
the pre-heating assembly is a counter current coiled pipe 72 which
winds upwards from the bottom of the applicator head adjacent the
wall thereof. The water then enters the flash boiler 74, which is
located adjacent to and heated by the flame from the burner head
62. Here the water is converted to steam and the pressure of
expansion forces it down a short exit pipe 76 to exit out of the
applicator tube 46 with additional heat from the flame. This heat
and steam is applied to the target area to control the unwanted
vegetation.
[0047] In continuous use an apparatus as described above will
consume approximately 2 to 6 litres (0.75 to 1.6 U.S. Gallons) of
water and 450 to 900 grams (1 to 2 lbs) of fuel per hour. Thus, a
backpack or apparatus with about 8 litres (2 gallons) water
capacity and about 2 kgs (4.5 lbs.) of fuel would weigh
approximately 14 kgs. (30 lbs.) when filled, and would permit
approximately 2 hours of operation under normal field conditions of
selective application or "spot spraying" of vegetation.
[0048] A second embodiment of an apparatus for controlling
vegetation according to the present invention is illustrated in
FIG. 4. This embodiment of the apparatus is adapted for heavy duty
or extended use and is preferably capable of mounting on a vehicle.
Depending upon the size of the apparatus, the vehicle may be a
wheeled cart that the user may pull or push along as they are
removing unwanted vegetation. For larger applications, the
apparatus is mounted on a motor vehicle such as the bed of a
GATOR.TM. or truck as is illustrated in FIG. 4.
[0049] The apparatus 110 consists of a frame 112 containing a water
tank 120 and one or more fuel cylinders 132 as well as fuel supply
and delivery means for delivering the water and fuel to the
applicator wand 116. The provision of the frame 112 allows the
apparatus to be easily moved on and off the bed of the vehicle. The
water tank 120 is capable of holding sufficient water for extended
operation of the apparatus, generally on the order of 20 to several
hundred gallons. The water tank 120 is provided with a filler
opening 122 and an outlet 124 connected to the applicator wand 116
through a suitable hose 126. Preferably, the outlet 124 of the
water tank 120 is provided with an inline filter 128 for removing
any debris or particulate matter which may accumulate in the water
tank 120 and which could affect the operation of the downstream
valves which will be described below. In order to properly control
the flow of water to the steam generator, the water is preferably
pumped through the hose by a pump means located in the frame 112.
In the embodiment illustrated, the pump means is an electrically
powered pump 130 which is powered by an auxiliary battery and/or
the vehicles electrical system. Other types of pumps such as a
gasoline powered pump may also be used. The pump may be a flow
through pump and may operate as a demand pump where the pump is
only active when the water pressure in the water line drops below
the desired level. Alternatively, the pump could be used to control
the air pressure in the tank to force the water through the outlet.
As a further alternative, the pump may be switched on when the
trigger is pressed.
[0050] The apparatus 110 also contains a source of fuel for the
burner. In the embodiment illustrated, the source of fuel is one or
more propane or pressurized fuel cylinders 132. The outlet of the
fuel cylinder 132 is attached to a flexible pressurized fuel line
134 which delivers the fuel to the applicator wand 116. As a safety
feature, a fuel shut off valve 136 is preferably provided at the
outlet of fuel cylinder 132. In order to provide for control of
fuel consumption, the fuel cylinder may be provided with a
regulator to regulate the pressure of the fuel being delivered to
the apparatus.
[0051] The applicator wand 116 of this embodiment is designed for
two hand operation and consists of a handle 140, a pistol style
grip 142 with trigger controls, and a suitable dimensioned metal
tube or pipe 144 carrying the fuel and water lines and connected to
the applicator head 146 containing the burner assembly and steam
generator. The applicator head 146 preferably has an insulated,
reflective, metallic wall 148 to maximize and focus heat
production. The applicator head 146 is dimensioned to produce the
desired steam and heat output while being able to be manipulated by
the user. Preferably, the applicator head 146 is tubular having an
inner diameter of between about 2 and 6 inches, more preferably
about 2 inches, and a length of between about 8 and 20 inches, more
preferably about 14 inches, depending upon burner size and desired
steam and hot air output.
[0052] Referring to FIG. 4, the fuel line 134 is connected to the
pistol grip 142 of the applicator 116 through a suitable connection
such as a quick connect fuel fitting 150. Preferably, for ease of
handling, the fuel line 134 and water hose 126 are joined together
along most or all of their length. A valve 152 located in the
pistol grip 142 downstream from the fuel fitting 150 regulates the
fuel flow to allow for fuel shut off and set the maximum fuel flow.
A fuel line 154 travels through the pipe 144 from the valve 152 to
a control valve 156 controlled by the trigger control 158. The
control valve 156 has two positions--"STAND BY" position, which
permits a reduced fuel flow to maintain a pilot light in the burner
as will be explained below and to provide low heat output, and an
"ON" position when the trigger control is activated which permits
full fuel flow and maximum heat. The "STAND BY" position of the
valve is adjustable to set the flame for the "STAND BY" or pilot
flame such as through the use of a suitable needle valve. From the
control valve 156, a fuel line 160 then travels along the pipe 144
of the applicator wand 116 to the burner head 162 in the applicator
head 146.
[0053] The water hose 126 is connected to the pistol grip 142 of
the applicator wand 116, at which point, the water flow is set or
tuned with a water metering valve 164 used to set the flow rate of
the water flowing through the hose 126. Preferably, the water
metering valve 164 is a needle valve, although other types of
valves such as a preset orifice valve may also be used to provide
the desired flow rate of the water. The water metering valve 164
may be located at other positions along the water path such as just
before the applicator head 146. From the flow control valve 164, a
water line 166 is attached to a second valve 168 controlled by the
trigger control 158. The second valve 168 provides reduced water
flow in the "STAND-BY" position, and permits water flow in the "ON"
position as will be described in detail below. From the second
valve 168, the water travels down a water tube 170 along the
applicator pipe 144 to a pre-heating assembly 172 within the
applicator head 146. In the embodiment illustrated, the pre-heating
assembly is a counter current coiled pipe 172 which winds upwards
from the bottom of the applicator head 146 adjacent the wall 148
thereof. The water then enters the flash boiler steam chamber 174,
which is located adjacent to and heated by the flame from the
burner assembly 162. Here the water is converted to steam and the
pressure of expansion forces it down a short exit pipe 176 to exit
out of the applicator head 146 with additional heat from the flame.
This heat and steam is applied to the target area to control the
unwanted vegetation.
[0054] In the second embodiment, the burner assembly 162 is
provided with a plurality of outlets for the fuel such that the
flame is applied to the steam generator over a larger area. For
example, the burner assembly 162 could be a circular burner head
having a plurality of openings to produce a circular flame.
Alternatively, the burner assembly 162 could be one or more linear
burner heads having a plurality of openings to produce an extended
linear flame.
[0055] In use an apparatus for mounting in the bed of a truck as
described above will use about 6 to 60 liters (1.5 to 15 U.S.
gallons) of water per hour and about 900 to 4500 grams (2 to 10
pounds) of propane per hour depending upon the desired output of
heat and steam.
[0056] A third embodiment of an apparatus according to the present
invention is illustrated in FIGS. 5 and 6 generally indicated by
the numeral 210. Similar to the first embodiment, this embodiment
210 is adapted for backpack use, however by increasing the sizes of
the applicator head and burner and steam generator contained
therein, the apparatus may be used for the larger scale
applications similar to the second embodiment described above.
[0057] The apparatus 210 consists of a backpack 212 having a water
container 214 for holding the water supply and carrying the fuel
supply and a delivery means for delivering the water and fuel to
the applicator wand 216. The backpack 212 is provided with straps
218 by which the backpack 212 may be carried on a user's back. The
water container 214 is capable of holding sufficient water for
operation of the apparatus. As will be explained in further detail
below, owing to the design of the apparatus, a few gallons of water
is sufficient to allow the operation for the apparatus for at least
about 2 hours. The water container 214 is provided with a filler
opening 222 and an outlet 224 connected to the wand 216 through a
suitable hose 226. Preferably, the outlet 224 of the water
container 214 is provided with an inline filter 228 for removing
any debris or particulate matter which may accumulate in the water
container 214 and which could affect the operation of the
downstream valves which will be described below. In order to
properly control the flow of water to the steam generator, the
water is preferably pumped through the hose by a pump means located
on the backpack 212. In the embodiment illustrated, the pump means
is a demand water pump 220 powered by rechargeable batteries 230.
The water pump 220 would only operate if the pressure drops below a
preset limit. Thus, the water pump 220 only operates as needed.
Alternatively, the water pump 220 may be activated by the trigger
control 258 described below.
[0058] The water container 214 carries a source of fuel for the
burner assembly. In the embodiment illustrated, the source of fuel
is one or more propane or pressurized gas or liquid fuel cylinders
232. When using propane, the fuel cylinders 232 may be prefilled
disposable cylinders or may be refillable cylinders. One such
refillable cylinder is a 6 inch diameter by 22 inch long aluminum
refillable cylinder capable of holding 6 lb of propane. The use of
a regulator to regulate the pressure of the fuel leaving the
cylinder may be desired to provide for better control and reduced
consumption of fuel usage.
[0059] In order to further control the consumption of fuel, it is
desired to regulate the temperature of the fuel container 232
during operation of the apparatus. In the embodiment illustrated,
the water container has a molded recess into which the fuel
cylinder 232 is placed. By providing an extended area of contact
between the water container walls and wall of the fuel container
232, the water container 214 acts as a heat sink for the fuel
cylinder 232, reducing the tendency of the fuel cylinder 232 to
cool down and frost over and thereby maintaining optimum fuel flow
even in reduced temperatures or during continuous operation. The
outlet of the fuel cylinder 232 is attached to a flexible
pressurized fuel line 234 which delivers the fuel to the applicator
wand 216. As a safety feature, a fuel shut off valve 236 is
preferably provided at the outlet of fuel cylinder 232 on the
backpack 212.
[0060] The applicator wand 216 of this embodiment is designed for
one arm operation as illustrated in FIG. 5, and consists of a
forearm brace 240, a handle 242 with trigger controls, and a
suitable dimensioned metal tube or pipe 244 carrying fuel and water
lines and connected to the applicator head 246 containing the
burner assembly and steam generator. The applicator head 246
preferably has an insulated, reflective, metallic wall 248 to
maximize and focus heat production. The applicator head 246 is
dimensioned to produce the desired steam and heat output while
being able to be manipulated by the user. Preferably, the
applicator head 246 is tubular having an inner diameter of between
about 1 and 4 inches, more preferably about 1 to 3 inches, most
preferably about 1.5 to 2 inches and a length of between about 4
and 12 inches, more preferably about 6 to 10 inches, most
preferably about 8 inches. These dimensions would be adjusted
depending upon the size of burner used and the desired output of
steam, hot water or hot water vapor and heat.
[0061] Referring to FIG. 6, the fuel line 234 is connected to the
handle 242 of the applicator wand 216 through a suitable connection
such as a quick connect fitting 250. Preferably for ease of
handling the fuel line 234 and water hose 226 may be joined
together along most or all of their length. A valve 252 located in
the handle downstream from the quick connect fitting 250 controlled
by a trigger control 258 regulates the fuel flow to allow for fuel
shut off and set the maximum fuel flow. The valve 252 has two
positions--a "STAND BY" position, which permits a reduced fuel flow
to maintain a pilot light in the burner and to provide low heat
output, and an ON position when the trigger control is activated
which permits full fuel flow and maximum heat. With this type of
valve, a control is provided to regulate the flow of fuel in the
"STAND BY" position to set the pilot light. From the handle 242, a
fuel line 260 then travels along the pipe 244 of the applicator
wand 216 to the burner head 262 at the applicator head 246.
[0062] The water hose 226 is connected to the handle 242 of the
applicator wand 216, which also contains a second valve 268
controlled by the trigger control 258. The second valve 268
provides reduced water flow in the "STAND-BY" position, and permits
full water flow in the "ON" position as will be described in detail
below. From the second valve 268 in the handle 242, the water
travels down a water tube 270 along the applicator wand pipe 244 to
a water metering valve 264 used to set the flow rate of the water
flowing to the steam generator. Preferably, the water metering
valve 264 is a preset orifice valve having an opening sized to set
the desired flow rate, although other types of valves such as an
adjustable needle valve may also be used to provide the desired
flow rate of the water. Preferably a filter or mesh is provided
immediately before the water metering valve 264 to reduce the
likelihood of the water metering valve 264 becoming clogged. The
water metering valve 264 is located just before a steam generator
272 within the applicator head 246 and a one way valve may also be
provided just before the steam generator 272 to reduce back
pressure during operation of the apparatus. In the embodiment
illustrated, the steam generator 272 includes a pre heater which is
a coiled pipe 274 which winds downwardly from the top of the
applicator head 246 adjacent the wall thereof. The water enters the
flash boiler 276 part of the steam generator 272, which is located
adjacent to and heated by the flame from the burner head 262. Here
the water is converted to steam and the pressure of expansion
forces it down a short exit pipe 278 to exit out of the applicator
tube 246 with additional heat from the flame. This heat and steam
is applied to the target area to control the unwanted
vegetation.
[0063] The steam generator 272 of this embodiment is a coil of
suitable metal tubing such as copper, stainless steel or a suitable
metal alloy. The coils are tight together in the pre heater near
the top in the region of the burner head 262 and spaced slightly
apart at the flash boiler 276 lower end. This allows for preheating
of the water within the tight coils and efficient heat transfer to
the spaced coils while allowing the excess heat and expanding gases
to pass though through the gaps between the coils at the lower end
and mix with the escaping steam. In order to further focus the
output of the applicator head 246, the steam generator coils and in
some embodiments, the applicator head 246 as well, taper inwardly
to surround the flame and focus the output. A preferred such steam
generator has tightly wound coils at the top about 2.5 to 5 inches
and coils spaced apart about 0.25 inches in the lower 1 to 3
inches. If desired, a pressure relief valve or restrictive nozzle
may be provided at the outlet of the steam generator to allow the
pressure and temperature of the steam to build up before being
released to the target area. A heat ballast to increase surface
area exposed to the flame may be added to assist in retaining and
transferring heat to the coils. Baffles may also be added in the
air space in the center of the tubing to distribute the flame and
modify and help in heat absorption by the steam generator.
[0064] In continuous use an apparatus as described above will
consume approximately 2 to 6 liters (0.75 to 1.6 U.S. Gallons) of
water and 450 to 900 grams (1 to 2 lbs) of fuel per hour. Thus, a
backpack or apparatus with about 8 liters (2 gallons) water
capacity and about 2 kgs (4.5 lbs.) of fuel would weigh
approximately 14 kgs. (30 lbs.) when filled, and would permit
approximately 2 hours of operation under normal field conditions of
selective application or "spot spraying" of vegetation.
[0065] A further embodiment of a steam generator for use in the
apparatus of the present invention is illustrated in FIG. 7. The
tubing of the steam generator extends downwardly along the exterior
of the applicator head 310 to a pre-heating coil 320 within the
applicator head 310. The pre-heating assembly is a coiled pipe 320
which winds upwards from the bottom of the applicator head 310
adjacent the wall 312 thereof. The water then enters the flash
boiler 322, which is located adjacent to and heated by the flame
from the burner head 330. The flash boiler 322 is a cone shaped
series of coils having gaps between the coils to allow the flame
from the burner to pass through the gaps and surround the coils.
Here the water is converted to steam and the pressure of expansion
forces it down a short exit pipe 324 to exit out of the applicator
head 310 with additional heat from the flame. This hot air and
steam is applied to the target area to control the unwanted
vegetation.
[0066] A further embodiment of an apparatus of the present
invention is illustrated in FIG. 8. This embodiment is particularly
useful for small scale applications such as would be encountered by
a homeowner who was maintaining their own property. The apparatus
consists of an applicator wand 400 having a water container 402 for
holding the water supply and a fitting for attaching a one pound
disposable propane cylinder 404 carrying the fuel supply. The
apparatus may be provided with a strap 406 by which the weight of
the apparatus may be supported by the user. The water container 402
is capable of holding sufficient water for operation of the
apparatus, generally on the order of 1 to 2 liters and is provided
with a filler opening 408 and an outlet tubing provided with an
inline filter for removing any debris or particulate matter which
may accumulate in the water container and which could affect the
operation of the downstream valves which will be described below.
The water supply may be fed to the steam generator by gravity,
however, it is preferred is a small electrically powered pump is
utilized to regulate the flow of the water to the steam generator.
The pump is switched on by activation of the trigger described
below.
[0067] The applicator wand 400 of this embodiment is designed for
two hand operation and consists of a handle 410, a grip 412 with
trigger controls 414, and a suitable dimensioned metal tube or pipe
415 carrying the fuel 416 and water 418 lines and connected to the
applicator head 420 containing the burner assembly 422 and steam
generator. The applicator head 420 preferably has an insulated,
reflective, metallic wall to maximize and focus heat production.
The applicator head 420 is dimensioned to produce the desired steam
and heat output while being able to be manipulated by the user.
Preferably, the applicator head 420 is tubular having an inner
diameter of between about 1 and 3 inches, more preferably about 1.5
inches, and a length of between about 4 and 8 inches, more
preferably about 6 inches, depending upon burner size and desired
steam and hot air output.
[0068] A valve controlled by a trigger control 414 regulates the
fuel flow to allow for fuel shut off and set the maximum fuel flow.
The valve has two positions--a "STAND BY" position, which permits a
reduced fuel flow to maintain a pilot light in the burner and to
provide low heat output, and an ON position when the trigger
control is activated which permits full fuel flow and maximum heat.
With this type of valve, a control is provided to regulate the flow
of fuel in the "STAND BY" position to set the pilot light.
[0069] The water hose 418 contains a second valve controlled by the
trigger control. The second valve provides reduced water flow in
the "STAND-BY" position, and permits full water flow in the "ON"
position as will be described in detail below. From the second
valve, the water travels down a water tube 428 along the applicator
wand pipe to a water metering valve 430 used to set the flow rate
of the water flowing to the steam generator. Preferably, the water
metering valve 430 is a preset orifice valve having a opening sized
to set the desired flow rate, although other types of valves such
as an adjustable needle valve may also be used to provide the
desired flow rate of the water. Preferably a filter or mesh is
provided immediately before the water metering valve 430 to reduce
the likelihood of the valve becoming clogged. The water metering
valve 430 is located just before a steam generator within the
applicator head 420 and a one way valve may also be provided just
before the steam generator to reduce back pressure during operation
of the apparatus. Similar to the previous embodiments, in the
embodiment illustrated, the tubing of the steam generator extends
downwardly along the exterior of the applicator head to a
pre-heating coil within the applicator head. The pre-heating
assembly is a coiled pipe which winds upwards from the bottom of
the applicator head adjacent the wall thereof. The water then
enters the flash boiler, which is located adjacent to and heated by
the flame from the burner head. The flash boiler is a cone shaped
series of coils having gaps between the coils to allow the flame
from the burner to pass through the gaps and surround the coils.
Here the water is converted to steam and the pressure of expansion
forces it down a short exit pipe to exit out of the applicator head
with additional heat from the flame. This hot air and steam is
applied to the target area to control the unwanted vegetation.
[0070] In many of the applications where steam is used for pest
control, it is desirable to provide for a continuous flow of water
to the flash boiler, even in STAND-BY mode. By providing a small
trickle of water to the flash boiler, the response time when the
switch is pressed to the ON position is reduced and the life of the
flash boiler is extended. The continuous small flow of water is
provided by a valve arrangement having a suitable means to feed a
small amount of water to the flash boiler at all times. The means
may be a variable valve having a low flow rate when the switch is
in the STAND-BY position and the full flow rate when in the ON
position. Alternatively, the means may be provided by a flow bypass
which bypasses the main water valve and provides for a low flow of
water at all times. Such an arrangement is shown in FIG. 9 where a
by pass line 450 is provided between the inlet line 452 and outlet
line 454 of the main water valve 456. The bypass line 450 is
provided with a restricted orifice 458 to allow for a low flow of
water to bypass the valve 456 at all times. When the valve 456 is
opened to the ON position, the full flow of water through the valve
456 is provided to the flash boiler.
[0071] FIG. 9 also illustrates a further feature of a preferred
embodiment of the apparatus of the present invention. In some
applications, it is desirable that a higher proportion of hot water
be applied, while in other applications, a higher proportion of
steam is desired. The proportion of steam to water in the output of
the apparatus of the present invention can be adjusted by the
amount of water being provided to the flash boiler. The higher the
amount of water provided to the flash boiler, the less steam
generated as the flow of the water does not allow for sufficient
time in the flash boiler for all of the water to be converted to
steam. Thus by adjusting the flow rate of the water to the flash
boiler, the relative amounts of steam and hot water in the output
of the apparatus can be regulated.
[0072] There are a number of ways in which the flow of water to the
flash boiler and hence the ratio of water and steam in the output
can be adjusted. This can be accomplished by providing a flow
control valve 460 with a variable adjustment to allow for complete
control over the flow of water. In this way, the operator can
select the flow rate to provide the optimum ratio for a particular
application. However, this also requires to operator to be familiar
with the needs for each application and requires some adjustment of
the output by the operator.
[0073] For most applications, the actual ratio of steam to hot
water may not be critical, rather the presence of a certain amount
of hot water in the output may be advantageous. It is therefore
preferred if a multi-position switching means is provided to allow
the operator to select a high water, high steam and perhaps
intermediate positions. For example, as shown in FIG. 9b, a two
position valve 464 having outputs with different sized orifices to
control the relative flow of water to the flash boiler may be
provided. A selector switch 464 with a water selection 466 and a
steam selection 468 is provided to allow the operator to easily
switch between the two settings. A three or more position valve may
also be used to allow for more options in terms of the ratio of
water and steam in the output.
[0074] An alternative arrangement is shown in FIG. 9c. In this
arrangement, a flow control valve 460, preferably a needle valve,
is provided. The valve is calibrated for the desired output
settings and the control knob 470 of the valve 460 is provided with
markings to allow the user to easily select the desired setting.
Thus the valve 460 is calibrated for a high steam output and the
control knob position for this setting is indicated. Similarly, a
high water setting is determined and the control knob position
indicated. One or more intermediate positions between these two
settings may be also provided if desired.
[0075] A further embodiment of a steam generator for use in the
apparatus of the present invention is illustrated in FIG. 10. The
steam generator of this embodiment has a generally hour glass
shape. The tubing of the steam generator extends downwardly along
the exterior of the applicator head 510 to a pre-heating coil 520
within the applicator head 510. The pre-heating assembly is a
series of coils which wind upwards from the bottom of the
applicator head 520 adjacent the wall 512 thereof. The coils then
reduce in diameter and then gradually increase to provide a cone
shape to the flash boiler section of the steam generator. The
pre-heated water enters the flash boiler section 522, which is
located adjacent to and heated by the flame from the burner head
530. The flash boiler 522 being a cone shaped series of coils
having gaps between the coils allows the flame from the burner to
pass through the gaps and surround the coils. Here the water is
converted to steam and the pressure of expansion forces it down an
exit pipe 524 to exit out of the nozzle 526 of the applicator head
510 with additional heat from the flame. This hot air and steam is
applied to the target area to control the unwanted vegetation.
[0076] The embodiment of the applicator head illustrated in FIG. 10
is provided with a screen 528 at the outlet of the applicator head.
The screen is preferably a wide mess screen having openings on the
order of 1/2 inch or less, preferably about 1/4 inch. The screen
528 helps to restrict the flame from the burner and maintains the
flame from the burner within the applicator head. The screen 528
also creates some turbulence in the output of the apparatus to help
in the distribution of the hot air, steam and hot water from the
apparatus onto the target area.
[0077] In some applications, particularly when treating the roots
of plants, it is desirable to place the output of the apparatus in
close contact with the plant material, and in some situations, it
is most desirable if the output is injected directly into the root
mass. This can be accomplished by providing an attachment 550 for
the end of the flash boiler 552 as illustrated in FIG. 11. The end
of the flash boiler output tube 554 is provided with a fitting 556
to which an extension tube 550 may be attached. The fitting 556 is
preferably a quick connect fitting or a screw fitting, most
preferably a screw fitting. The extension tube 550 is provided with
a fitting 558 complementary to the fitting 556 on the end of the
output tube 554 of the flash boiler 552 such that it may easily be
attached and detached from the output tube 554 as desired.
Preferably, the extension tube 550 has a restrictive profile 560 to
increase the force with which the treatment mixture of steam and/or
hot water from the flash boiler is dispensed to increase the
penetration of the treatment mixture into the root structure of the
plant. As illustrated in FIG. 11, the restrictive profile 560 is
preferably provided by flattening the tube 550 to reduce the output
diameter of the extension tube.
[0078] In other applications, it may be desirable to be able to
push the output either deeper into the plant or to increase the
contact pressure between the output and the plant material. In
order to accomplish this it is desirable that the extension of the
flash boiler output be capable of withstanding these forces. A
simple extension tube 550 such as shown in FIG. 11 may bend under
such forces and be less effective. In these situations, a further
attachment 570 is provided to allow the extension tube 550 to be
placed where desired with the necessary force. The additional
attachment 570 surrounds the extension tube 550 and prevents it
from being damaged and rendered less effective when forced into the
plant material or surrounding soil. As illustrated in FIG. 12,
preferably the attachment 570 has a funnel shape with the top 572
of the funnel supported by the applicator head 574 and the point
576 of the funnel containing and protecting the extension tube 550.
The funnel shape also acts as a wedge as the attachment is forced
into the plant material or soil, allowing for greater penetration
for treatment.
[0079] A further embodiment an applicator wand for use with the
apparatus of the present invention is illustrated in FIGS. 13 and
14, generally indicated by the numeral 600. The applicator wand 600
of this embodiment is designed for two hand operation and consists
of a handle 602, a pistol style grip 604 with trigger controls, and
a suitable dimensioned metal tube or pipe 606 carrying the fuel and
water lines and connected to the applicator head 608 containing the
burner assembly 609 and steam generator 610. The applicator head
608 preferably has an insulated, reflective, metallic wall 612 to
maximize and focus heat production. The applicator head 608 is
dimensioned to produce the desired steam and heat output while
being able to be manipulated by the user. Preferably, the
applicator head 608 is tubular having an inner diameter of between
about 2 and 6 inches, more preferably about 3 inches, and a length
of between about 8 and 20 inches, more preferably about 10 inches,
depending upon burner size and desired steam and hot air
output.
[0080] Referring to FIG. 14, the fuel line 614 is connected to the
pistol grip 604 of the applicator wand 600 through a suitable
connection such as a quick connect fuel fitting 616. Preferably,
for ease of handling, the fuel line 614 and water line 618 are
joined together along most or all of their length. A control valve
619 located in the pistol grip 604 downstream from the fuel fitting
616 regulates the fuel flow to allow for fuel shut off and set the
maximum fuel flow. A second control valve 620 is provided
downstream of the first control valve 619 and has two
positions--"STAND BY" position, which permits a reduced fuel flow
to maintain a pilot light in the burner as will be explained below
and to provide low heat output, and an "ON" position when the
trigger control 622 is activated which permits full fuel flow and
maximum heat. The "STAND BY" position of the valve is adjustable to
set the flame for the "STAND BY" or pilot flame such as through the
use of a suitable needle valve. From the control valve 620, a fuel
line 624 then travels along the pipe 606 of the applicator wand 600
to the burner assembly 609 located at the inlet of the applicator
head 608.
[0081] The water line 618 is connected to the hand guard 626 of the
pistol grip 604 of the applicator wand 600, and then enters a water
valve assembly 628. The water valve assembly 628 contains a water
metering valve 630 used to set the flow rate of the water flowing
through the water line 632 exiting the valve assembly 628 and
extending along the pipe 606 to the steam generator 610 within the
applicator head 608. Preferably, the water metering valve 630 is a
needle valve, although other types of valves such as a preset
orifice valve may also be used to provide the desired maximum flow
rate of the water. From the water metering valve 630, a water line
634 is attached to a second valve 636 controlled by the trigger
control 622. The second valve 636 may provide for reduced water
flow in the "STAND-BY" position, and permit full water flow in the
"ON" position. Alternatively, the water valve assembly may also
provide for a reduced water flow when in the "STAND-BY" mode. A
flow bypass bypasses the valves 630 and 636, which could be an
On-Off valve and provides for a low flow of water at all times is
provided. Such an arrangement is as shown in FIG. 9a where a by
pass line 637 is provided between the inlet line 618 and outlet
line 632 of the water supply. The bypass line 637 is provided with
a restricted orifice to allow for a low flow of water to bypass the
valves 630 and 636 at all times. When the second valve 636 is
opened to the ON position, the full flow of water through the valve
636 is provided to the steam generator 610.
[0082] In addition, the water valve assembly 628 is provided with
an arrangement to allow for changing the ratio of water to steam,
preferably a two position valve 638 having outputs with different
sized orifices to provide a high water or high steam output of the
flash boiler in a manner as described above in FIG. 9b. A selector
switch 639 with a water selection and a steam selection is provided
to allow the operator to easily switch between the two
settings.
[0083] From the second valve 636, the water travels down a water
line 632 along the applicator pipe 606 to the steam generator 610
within the applicator head 608. The steam generator 610 has a
pre-heating assembly which is a counter current coil 640 which
winds upwards from the bottom of the applicator head 608 adjacent
the wall 612 thereof. The water then enters the flash boiler steam
chamber 644, which is located adjacent to and heated by the flame
from the burner assembly 609. Here the water is converted to steam
and the pressure of expansion forces it down a exit pipe 642. The
applicator head 608 is provided with a wide mess screen 644 at the
outlet of the applicator head which helps to restrict the flame
from the burner and maintain the flame from the burner within the
applicator head 608. The screen also creates some turbulence in the
output of the apparatus to help in the distribution of the hot air,
steam and hot water from the apparatus onto the target area.
[0084] A further embodiment of the apparatus of the present
invention, particularly for use by a homeowner is illustrated in
FIG. 15. The apparatus utilizes an applicator wand 700 as described
with respect to FIGS. 13 and 14 above and a cart arrangement 702 to
supply the fuel and water to the applicator wand 700. The cart 702
is provided with a holder 704 for a fuel container, preferably a
propane cylinder 706 which connects to the applicator wand 700
through a suitable fuel hose 708. The cart 702 is also provided
with a water hose 710 connected at one end to the applicator wand
700 and having a pressure reducing valve 712 on the other end. A
garden hose 714 is then connected between the pressure reducing
valve 712 and the domestic water supply of the house, typically by
attaching the garden hose 714 to an exterior hose bib. As the unit
is designed for homeowner use, where a constant supply of water is
available, a separate water container and pump are not required.
The pressure of the water from the domestic water supply provides
for a sufficient flow of water for operation of the apparatus. The
cart 702 is also provided with a holder 716 to hold the applicator
wand 700 and a holder 718 to allow the fuel hose 708 and water hose
710 to be coiled for storage and transport.
[0085] To operate the apparatus of the present invention, the user
first fills the water container and ensures that there is an
adequate supply of fuel. The outlets of the water container and
fuel supply are connected to the inlet of the applicator wand with
the water and fuel hoses. The fuel flow valve is turned to set the
appropriate fuel flow rate with the trigger switch in the
"STAND-BY" position. The burner head is then lit and with the
trigger switch in the "ON" position, the fuel flow valve and water
flow valves adjusted to provide optimum water and fuel flow. During
this set up operation, the burner is heating both the pre-heater
and steam generator and the trigger switch is held in the on
position until steam is observed coming from the applicator head.
At this point the user releases the trigger switch to reduce the
flow of water and allow the low "STAND-BY" flow of fuel to the
burner head to maintain a low flame which also prevents the
temperature of the water pre-heater and steam generator from
dropping rapidly.
[0086] The user then moves along the area to be treated and the
applicator head is placed over the target area containing pests
such as unwanted vegetation and the trigger switch activated to
start the flow of water and fuel. The outlet end of the applicator
head is held as close as possible to the target area for a few
seconds. The trigger switch is then released and the user moves to
the next target area where the process is repeated. With the
backpack version of the apparatus of the present invention having
the hand pump, the user operates the hand pump intermittently to
maintain the water flow.
[0087] The smaller backpack apparatus is intended for small scale
application such as "spot spraying" or selective control of weeds
among desired vegetation, such as control of weeds growing in shrub
or vegetable gardens, lawns and cracks or crevices in pavement. The
larger vehicle mounted apparatus, with increased fuel and water
capacity and greater steam and heat output is intended for large
scale applications such as vegetation control along roadsides,
ditches, fence lines or vacant areas.
[0088] For reasons of safety, heat and steam output could be
controlled through automatic water and/or fuel input valves instead
of manually controlled needle or orifice flow control valves. A
bimetallic (or electric) thermostatically controlled valve for
example could automatically monitor output and regulate water
and/or fuel supply to the applicator head. A temperature gauge
could also be provided to give an indication of the output
temperature of the hot air and steam. The temperature sensing
device would be located at the outlet of the applicator head and
the display of the temperature could be provided at the handle to
allow the user to easily observe the output temperature.
[0089] To help maintain the temperature of the hot air and steam
from the applicator head, a removable funnel shaped shroud may be
provided to slip over the outlet end of the applicator head. To
provide for increased safety of the operator, a safety shield may
be attached to the shaft above the applicator head to protect
against possible blowback of hot air and steam.
[0090] To provide for adjustability in the length of the applicator
wand and to increase user comfort, the metal tube of the applicator
wand may be adjustable in length, by providing a telescoping tube
having one tube slid able within another and a releasable locking
means to lock the tubes in the desired position. Alternatively, the
wand may be two tubes located and connected side by side to one
another and slidable one past the other to allow for length
adjustability. A releasable locking means is provided to lock the
tubes in the desired position.
[0091] Another modification to increase user comfort could be the
provision of a single removable small wheel capable of withstanding
the output temperatures of the apparatus attached to the delivery
end of the wand applicator. This would allow the user to roll the
apparatus along the ground, thus reducing the weight supported the
user. This would be of particular use with the larger apparatus or
where the apparatus is being used for pest control of cracks and
crevices along hard surfaces such as pavement or concrete.
[0092] The apparatus of the present invention provides for
effective control of pests such as unwanted vegetation in an easy
to operate apparatus. The apparatus generates steam on the fly by
injecting small quantities of water into a steam generator heated
by a burner head located in the applicator head, close to the area
of application. The water is injected into the steam generator thus
allowing for a simpler to manufacture and operate apparatus. The
apparatus operates unlike a boiler based apparatus where the steam
is generated in a boiler and then carried to the applicator head.
Such a prior art apparatus requires a much more complex design as
the steam must be transported from the boiler to the applicator
head while not losing a significant amount of its heat. This
present apparatus utilizes its generated heat which is applied with
the steam for enhanced efficiency instead of venting it away or
having to insulate and pipe it to the target area. This apparatus
avoids the potentially dangerous use of a boiler and contained
high-pressure steam.
[0093] In addition to use in controlling vegetation, the apparatus
of the present invention can be used to control other pests such as
insect infestations, fungal growth, etc. In addition the apparatus
can also be used to clean surfaces which are not susceptible to
damage by higher temperatures. For example, the apparatus can be
used to remove mollusks or mussels from ship hulls, particularly
metal hulled vessels or grease and oil from oil rigs. The apparatus
can also be used for cleaning of other surfaces such as concrete,
brick, etc. It is particularly useful for removal of paint,
especially graffiti and gum from such surfaces or for de-icing and
drying. The apparatus is also useful for asphalt repair and
softening roofing tar. Another possible use of the apparatus of the
present invention is for heat activation of other materials such as
detergents or cleansers. In all of these applications, the output
of the applicator head is adjusted through adjustment of fuel and
water supply to maximize effectiveness.
[0094] Although various preferred embodiments of the present
invention have been described herein in detail, it will be
appreciated by those skilled in the art that variations may be made
thereto without departing from the spirit of the invention or scope
of the appended claims.
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