Heating screws for the treatment of invasive plants

Abstract

The invention relates to a method for treating soil containing invasive plants, which method comprises: - inserting and removing threaded heating elements into and from the subsoil; each of the threaded heating elements comprising a shaft (1) and a threading (3) in the form of helical blades arranged around central elements of the shaft along the entire length of the threaded heating element; the diameter of the threads (3) being 2 to 4 times greater than that of the cross-section of the shaft (1); the threads (3) being inclined between 20 and 40°; - heating the subsoil to a target temperature; the heating being controlled by temperature probes (6) placed between the threaded heating elements and lighting elements; - wherein a device controls the heating power depending on the temperature measurements taken by the temperature probes (6).

Description

[0001] HEATING SCREWS FOR THE TREATMENT OF INVASIVE PLANTS

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to a method of heat treatment of soil affected by invasive plants or weeds, in particular Japanese knotweed.

[0004] In a second aspect, the present invention also relates to a device for inserting a heating element into the floor, controlling the heating and automatically adapting the heating power to the target temperatures.

[0005] The present invention relates to the technical field of soil treatment.

[0006] CONTEXT

[0007] Japanese knotweed is a widespread noxious weed in North America and Europe. It is found in natural areas, parks, gravel bars, along stream beds and banks, rights-of-way, and roadsides. It is also found in riparian areas and on uplands. Japanese knotweed thrives in moist soils or where roots can penetrate most soils. Plants often establish after being rejected from cultivated gardens or escaping from abandoned houses. Japanese knotweed also spreads through mechanical mowing and the unintentional transport of cut rhizome segments into neighboring landscapes.

[0008] Japanese knotweed, a member of the buckwheat family (Polygonacaea), is an erect, shrub-like, herbaceous perennial that often reaches a height of over 3 meters. As with all members of this family, the base of the stem above each joint is surrounded by a membranous sheath. Japanese knotweed stems are smooth (like bamboo), stout, and swollen at the joints where the leaf joins the stem. Although leaf size varies depending on environmental conditions, age, and other factors, they are normally about 150 mm long and 75–100 mm wide, broadly oval to somewhat triangular, most often pointed at the tip, and are alternate on the stems. The stems are hollow but may be filled with water depending on soil moisture levels and where they are growing.The first or two lower nodes can often be filled with water. The small, pale greenish-white flowers appear in attractive branched sprays in summer and are followed by small, winged fruits. When they appear, the seeds are triangular, glossy, very small, about 2.5 mm long. Seeds cannot be produced in all growing situations, and normally not in conditions found outside the native Asian range. The plants grow rapidly and often form large thickets or patches. The roots are rhizomes that can extend up to 10 m long. Buds along the rhizomes can develop into new stems depending on environmental and cultural conditions. Digging around the base of established plants encourages the development of new vegetative buds along the rhizome system.

[0009] Japanese knotweed can spread by sprouts from the rhizomes of established plants and by sprouts from stems that have been cut from the parent plant. Roots and stems can develop when stem nodes come into contact with soils suitable for plant establishment.

[0010] Known methods for controlling Japanese knotweed include foliar application. Foliar applications are made using spray equipment designed to apply small droplets to the entire plant (stems and leaves). They can be made using backpack sprayers or hose-end sprayers. Applicators must be careful to treat only the target species and not desirable neighboring vegetation. Foliar applications to new growth from rhizome segments and cane nodes have been shown to be effective on plants during the first 3 to 4 weeks of growth (less than 1.2 m in height). On established roots, spraying new growth may require multiple applications over several years to achieve control. This product is not recommended for riparian areas.Depending on the severity of the infestation, foliar applications may require re-treatment during the growing season and possibly a follow-up treatment in subsequent years.

[0011] Another known method of Japanese knotweed control is cut stem application. This involves cutting the Japanese knotweed stem between the first and second internode and applying it to the "well" created by cutting the internode in half. This method applies approximately 10 to 20 ml to the well. Depending on the site, there are several herbicide options for this application method. Cut stem applications have been shown to be 95% effective on mature plants. After 1.2 m of regrowth on the remaining stems, a second cut stem application or injection should eliminate any regrowth. Another known method of Japanese knotweed control is stem injection, as in US 7,805,884 B2. Stem injection applications are made just below the first or second node, near the soil line.Typically, a Japanese knotweed probe is used to create a small opening on either side of the stem, just below the node, to allow water to escape. A syringe metered to inject 5 ml of herbicide treatment delivers the treatment dose diagonally downward through one of the two holes closest to the applicator. The second hole can then allow pressurized water to escape if the node is full of water. Plants normally absorb the herbicide within 20 minutes of injection.

[0012] The riparian zone injection process has proven to be the most effective against regrowth of the plant, while being selective for Japanese knotweed and posing no threat to the environment. The observed results of the injections into each cane have resulted in complete snow control, and no regrowth has occurred after treatment for 22 months. Each cane must be injected. Each cane has its own rhizome system. Although the injection process is time-consuming at first, it is more cost-effective than multiple trips to the same location for foliar applications made over the years with minimal results. Toward the end of the growing season, the stems tend to become tougher, requiring a sharper, more robust device to penetrate the cane cavity.

[0013] Another known method is to cool the soil to negative temperatures and kill the rhizomes due to very cold temperature (as in the case of NL2026136B1);

[0014] Another method involves exterminating the weeds in an extermination chamber having at least one open side, placing the open side over the weeds to be exterminated, and substantially closing the edge of the open side of the chamber (W02010008286). A similar refrigeration method is described in EP 2409566.

[0015] None of the foregoing inventions and patents, taken alone or in combination, is considered to describe the present invention as claimed.

[0016] These known devices, methods and uses have the following disadvantages or problems:

[0017] Methods based on injecting chemicals into the plant or knowingly not being 100% effective and requiring multiple injections, no quick solution can therefore be proposed when it is not a question of eliminating before the start of a construction site for example. Methods based on cooling or knowingly expensive and difficult to implement.

[0018] The present invention aims to solve at least some of the problems and drawbacks mentioned above.

[0019] The invention aims to provide a practical, fast and efficient method for placing heating elements in the ground, ensuring good heat conduction in the ground, operating with any energy source available on site, and being almost entirely automatic, not requiring continuous presence on site during heating. More importantly, the present methods allow very rapid definitive elimination of invasive plants and weeds, and more particularly of Japanese knotweed.

[0020] SUMMARY OF THE INVENTION

[0021] To this end, the present invention relates to a simple and manual method for placing heated auger screws in the ground, at shallow depths, allowing both easy placement and better conduction in the target area. The use of a single element (the heated screws) makes it possible to avoid the removal of soil (excavated material) and the use of external materials, such as gravel, and to ensure very rapid installation using a manual or mechanical auger;

[0022] These heated screws are hollow, and the heat source, which can be circulating hot air or electrical resistances, is located within this hollow. Since each heating element is independent of the others, the method can be adapted to any geometry and depth of the affected area. This ensures that the entire affected area has reached the temperature and that there will be no regrowth of plants or weeds in the future.

[0023] DETAILED DESCRIPTION OF THE INVENTION

[0024] Unless otherwise defined, all terms used in the disclosure of the invention, including technical and scientific terms, have the meaning commonly understood by a person having ordinary skill in the art to which the present invention pertains. The definitions of terms are included for convenience in order to better appreciate the teaching of the present invention.

[0025] In this document, the following terms have the following meanings:

[0026] The terms "A", "a" and "the" used in this document refer to both the singular and the plural, unless the context clearly requires otherwise. For example, "a compartment" means one or more compartments.

[0027] The term "about," as used herein to refer to a measurable value such as a parameter, quantity, time duration, etc., is intended to encompass variations of + / -20% or less, preferably + / -10% or less, more preferably + / -5% or less, even more preferably + / -1% or less, and even more preferably + / -0.1% or less of the specified value, to the extent that such variations are appropriate for carrying out the disclosed invention. However, it is understood that the value to which the modifier "about" refers is itself specifically disclosed.

[0028] The terms "Comprised", "comprising", "comprises" and "composed of", as used herein, are synonymous with "include", "includes", "comprises" or "contain", "containing", "contains" and are inclusive or open terms that specify the presence of the following, e.g., a component, and do not exclude the presence of additional components, features, elements, members, steps not cited, known in the art or disclosed herein.

[0029] Furthermore, the terms first, second, third and the like in the description and claims are used to distinguish like elements and not necessarily to describe a sequential or chronological order, unless otherwise indicated. It is understood that the terms so used are interchangeable in appropriate circumstances and that the embodiments of the invention described herein may operate in sequences other than those described or illustrated herein.

[0030] The enumeration of numerical ranges by their endpoints includes all numbers and fractions within that range, as well as the listed endpoints. The expression "wt%", "weight percentage", "wt%" or "wt%", here and throughout the description, unless otherwise defined, refers to the relative weight of the respective component to the total weight of the formulation.

[0031] While the terms "one or more" or "at least one", such as one or more members or at least one member of a group of members, are self-explanatory, by way of example, the term includes in particular a reference to any one of said members, or to two or more members, such as, for example, >3, >4, >5, >6 or >7 etc. of said members, and up to all of said members.

[0032] Unless otherwise defined, all terms used in the disclosure of the invention, including technical and scientific terms, have the meaning commonly understood by a person having ordinary skill in the art to which the present invention pertains. For convenience, definitions of terms used in the description are included to better appreciate the teaching of the present invention. The terms or definitions used herein are provided solely to facilitate the understanding of the invention.

[0033] Reference to "an embodiment" or "an embodiment" in this specification means that a particular feature, structure, or trait described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the phrases "in an embodiment" or "in an embodiment" that appear in various places in this specification do not necessarily all refer to the same embodiment, but may do so. Furthermore, the particular features, structures, or traits may be combined in any suitable manner, as would appear to a person skilled in the art from the present disclosure, in one or more embodiments.Furthermore, if some embodiments described herein include some features included in other embodiments, but not others, combinations of features from different embodiments are intended to fall within the scope of the invention and form different embodiments, as would be understood by those skilled in the art. For example, in the following claims, any of the claimed embodiments may be used in any combination.

[0034] The present invention relates to a method for heating the soil to kill invasive plants or weeds, such as Japanese knotweed. It is well known that invasive plants pose a threat to our environment, buildings, and infrastructure. Some of them, such as Japanese knotweed, spread rapidly in certain regions of the world where they are not faced with ecosystems that limit their growth. They then thrive at the expense of local species and can also destroy infrastructure.

[0035] Their root-based reproduction system is highly resistant to conventional methods such as chemical treatments, cutting, smothering, etc. Most of these existing methods are not effective and / or may require several years of application before getting rid of the plants.

[0036] It has been proven that rhizomes do not withstand increased temperatures above 55°C to 65°C. Heat treatment is therefore an effective method for controlling invasive plants quickly and permanently.

[0037] It is also necessary to find quick solutions, especially in the infrastructure sector, as long-term, multi-year solutions are not acceptable for projects requiring solutions within a few weeks. Thermal treatment of these soils is therefore an effective and rapid solution.

[0038] To be effective, however, a heat treatment must ensure that the entire volume of soil is heated to the target temperature, not just certain parts. Indeed, if certain parts do not reach the target temperature, it is possible that residual rhizomes will survive the treatment and continue the spread of the invasive plant.

[0039] Conduction heating is therefore an essential element of the invention, because the conduction ensured in a porous medium will guarantee homogeneous heating of the entire volume, hence the guarantee that no residual rhizome will remain after treatment, once the target temperature has been reached.

[0040] Current thermal treatment methods, however, are based on resistive heating, which does not cover the entire volume, as the current only passes through the most conductive paths and leaves behind highly resistive parts of the soil. Existing conductive heating methods are designed for contaminated soils, i.e., they contain both vapor extraction wells (designed to transport vapors containing contaminants) and heating elements placed in pre-drilled holes, which are filled with a permeable medium such as gravel. This gravel is designed to transport heat and maintain high permeability for vapor collection.

[0041] All these devices associated with existing conduction thermal desorption are expensive and bulky. In addition, the installation of these heating devices requires multiple operations such as drilling, removing drill augers, installing heating elements, inserting steam extraction tubes, inserting gravel, etc.

[0042] With the present invention, all of these steps are performed at once, which significantly reduces the cost of installing the heating elements. In addition, the auger-heated screws contained in the present invention have the added advantage of allowing greater conduction into the soil, making treatment more efficient and / or faster.

[0043] Wires are a well-known device in earth drilling. It is mainly used to excavate the ground with an auger, extracting the earth through the wires to the surface, thus generating a vacuum. Drilling wires are used to create voids and are extracted in order to place other elements (such as pipes or tubes with gravel or equivalent materials).

[0044] The present invention is a method in which threaded heating elements are inserted into the soil at a specific rate, so as not to disturb the soil itself. They remain in the soil for the entire heating period and are only removed once the treatment objectives have been achieved.

[0045] The shape of the thread should be such that the outer diameter is between 2 and 4 times the diameter of the inner central tube (shaft), with an angle, as in Figure 4, between 20 and 40°, in order to disturb the soil as little as possible when inserting the elements into the soil and to maximize the conduction of heat in a minimum of time to the entire targeted soil volume.

[0046] Threaded heating elements are known from D3 (EP0444714.3), but in D3 the heating elements are perforated and serve as both extraction and heating elements, as they are combined with the recirculation of hot air; D3 does not specify any dimensions or shapes of the threads, so there is no real advantage in having the specific shapes mentioned for the conduction heating to be transferred at the best possible rate;

[0047] The invention is also described by the following non-limiting examples, which illustrate the invention and are not intended to limit the scope of the invention and should not be construed as such.

[0048] DESCRIPTION OF FIGURES.

[0049] For the purpose of better illustrating the properties of the invention, the following presents, by way of example and without in any way limiting other potential applications, a description of a number of preferred applications of the method for examining the condition of grout used in a mechanical connection based on the invention, in which:

[0050] FIG. 1 schematically shows the heating screw, with an external spiral metal shape that allows the soil to be perforated by the rotation of the screw, advancing the device to the required depth, but also providing a larger heated surface (the spirals) that is heated by metallic conduction and therefore transmits heat more quickly and efficiently into the soil.

[0051] Additionally, the screws allow for better contact with the ground, as the device does not require any hammering to be installed. This allows for better contact and therefore better conduction.

[0052] FIG. 2 shows in more detail the preferred embodiment where the heated screw is heated with circulating hot water, or any other heat transfer fluid such as hot air or heating oil.

[0053] FIG. 3 shows a preferred embodiment in which several heating elements are installed to cover an area at a certain depth so that the total volume is properly heated. The figure clearly shows where the temperature sensors (6) are located in order to control the energy injected into each heating element. These temperature sensors measure the temperature at different depths thanks to individual thermocouples (5) and a specific model will calculate the necessary power to be injected into the ground (7). It is assumed that the present invention is not limited to any embodiment described above and that certain modifications can be made to the manufacturing example presented without the appended claims being affected.

[0054] It is clear that the method according to the invention and its applications are not limited to the examples presented.

[0055] The present invention is in no way limited to the embodiments described in the examples and / or illustrated in the figures. On the contrary, the methods according to the present invention can be carried out in many different ways without departing from the scope of the invention.

Claims

CLAIMS 1. Method of treating soil containing invasive plants, comprising: - insertion and removal of threaded heating elements in the basement; - helical blades around the central elements of the shaft along the entire length of the drilling element; - the diameter of the threads is 2 to 4 times greater than that of the shaft section; - the nets are inclined between 20 and 40°; - heat the basement to a target temperature; - the heating is controlled by temperature sensors placed between the heating elements and the lighting elements; - where a device controls the heating power based on temperature measurements.

2. The method of claim 1, wherein the thermocouple sensors are threaded.

3. The method of claim 1, wherein the heating elements are made of steel or an iron-based alloy.

4. The method of claim 1, wherein the heating elements contain varying levels of heating power.

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