BE1029046A1 - Hot sampling system - Google Patents

Abstract

The present invention relates to a hot soil sampling system making it possible to extract samples representative of the state of the subsoil at different depths. It makes it possible to extract hot soils which have lost their cohesion due to their heating. Thus, during thermal depollution, consisting in heating the ground, often beyond 100°C, control samples can be taken as the depollution progresses, in order to give a representative view of the actual state of depollution. It consists of two coaxial cylinders sliding one inside the other and making it possible to open and close a sampling window at the defined depth and thus ensure a representative sample in a warm ground.

Description

Hot sampling system BE2021/0009

DESCRIPTION ‚ FIELD OF THE INVENTION { The present invention relates to a sampling and control system during a process | thermal depollution of contaminated soils. In particular, the invention relates to a method and devices for extracting a hot soil sample during or at the end of treatment in order to subsequently analyze the chemical composition of this sample.

BACKGROUND OF THE INVENTION Soil contamination has become a matter of great concern in many places. Soil can become contaminated with chemical, biological and/or radioactive contaminants. Material spills, leaking storage tanks and seepage in material dumps are just a few examples of the many ways soil can become contaminated. If left in place, many of these contaminants will find their way into aquifers, the air, or the food supply and could pose public health risks.

There are many methods proposed to remove surface contaminants, such as excavation followed by incineration, in situ vitrification, biological treatment, chemical additives for deactivation, radio frequency heating, etc. Although effective in some applications, these methods can be very expensive and impractical if many tons of soil need to be treated.

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A process frequently used to remove contaminants from underground soil is in situ thermal desorption, used to increase the efficiency of a soil vapor extraction process. In situ thermal desorption involves heating the soil without excavation to raise the temperature of the soil while simultaneously removing gaseous effluents from the soil. — Heat added to contaminated soil can raise the soil temperature above the contaminant vaporization temperatures in the soil and cause the contaminants to vaporize. A vacuum applied to the ground extracts the vaporized contaminant from the ground.

Another method of heating soil containing contaminants includes injecting a heated fluid into the soil. Such a method is for example described in US Patent No. 6,000,882. The method described here consists of introducing a system of perforated pipes into the ground. A stream of hot air is sent through the pipes. Hot air is injected into the floor through perforations | in the pipes at the pipe perforations. Contaminant vapor forms in the ground, which can be removed from the ground through the pipe perforations and vented to an off-gas treatment unit.

Another way of heating a floor consists in heating a floor by thermal conduction by means of electric resistances or in heating the latter for injection of electric current into the floor and dissipation of the latter by Joule effect. The thermal conduction heating of contaminated soil in combination with the removal of contaminating gases from the soil using a vapor extraction system is old in the art.

During in situ thermal desorption, all surfaces in contact with the atmosphere are generally covered with concrete and an insulation layer after the concrete layer.

There are therefore many soil treatment systems which consist, in one way or another, of heating the soil to mobilize the contaminants and then extract them.

All these systems face a common difficulty related to measuring the progress of the | depollution on the one hand and the verification that it is complete on the other hand. Indeed, conventional sampling techniques (sampling) are not designed to sample hot soils, in particular soils with a temperature above 100°C. The main difficulties associated with hot sampling are related to the texture and structure of the soil, which loses its cohesion due to drying out, and on the other hand to ensure that changes in physical and chemical conditions n do not influence the quality of the recovered sample, in particular due to the volatilization of the more volatile elements during sampling.

However, knowledge of the composition of the earth being treated is an asset that will make it possible to evaluate the performance of the process and improve its operation. Conventional sampling techniques (augers, gouges, coating, etc.) are ineffective in such a process because the processed material literally “flows” within them. In addition, the high temperature (>>120°C) prevents the use of formed plastics such as check valves, advancement of crankcase parts, etc.

The present invention therefore aims to provide a solution to be implemented to extract several samples from this volume in treatment in order to be able to know the composition of the earth after a certain time of treatment and in this way to define the progress of the treatment. It also makes it possible to take a hot sample of equivalent quality to a cold sample, making it possible to validate the achievement of the objectives of thermal depollution.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings illustrate the invention: Figure 1: Hot sampler - internal and external exploded Figure 2: Sampler - external appearance 40 Figure 3: Detail of the internal and external sampler Figure 4: Sampling sequence with lost point

Figure 5: Exploded view of external and internal sampler Figure 6: Perspective view of lost tip sampling The legend of the figures is as follows:

1. Hot sampler: outer tube

2. Internal coaxial cylinder

3. Crank

4. Conical point (lost or not)

5. External opening window

6. Scraper

7. Internal sampler cap

8. Internal opening window

9. Internal sampler

10. Rod of the internal sampler DETAILED DESCRIPTION OF THE INVENTION The hot sampling system is a system allowing the extraction of a representative sample of hot earth during or after heat treatment.

The system consists of a hot sampler (1), an auger or an equivalent system intended to drill to the depth required for sampling and a set of rods for extending the drilling to the desired depth and manipulating the hot sampler.

The hot sampler (1) consists of two coaxial cylinders (1 and 2), each of them having an opening window (5 and 8) of comparable size, placed at the top of the cylinder, and of height corresponding to the required depth window for sampling; The internal cylinder (2) is connected to the operator through the rod (10) which allows the latter to turn the internal cylinder when the latter is positioned at the correct depth. The rod also helps establish the correct sampling depth.

The system consists of inserting a hot sampler (1) into the ground at the depth chosen for the representative sampling. When the hot sampler (1) is positioned at the correct depth, the rod (10) is rotated until the inner (8) and outer (5) windows are opposite each other. other.

40 — The sampling element inserted at the determined depth is made up of two “cylindrical” elements sliding one inside the other around a radial axis. In a preferred embodiment, said sampling technique is made possible following the placement of reservation tubes (TR) with a diameter between 30 and 70mm, preferably between 40 and 60mm at the same time as the placement of the elements heaters for in situ thermal desorption treatment, in the treatment zone. The position and length of these tubes depends on the location of the points equidistant from the heating elements. In a preferred embodiment, said sampling technique comprises the following steps:

1. The two tubes (1)(2) are pushed together into the soil or the material to be sampled through the reservation tubes (TR) by force of the arms or using a sledgehammer. They are - expandable by screwing a length of 0.7 to 2m, preferably 0.9 to 1.2m on the other to obtain the desired depth. Depending on the type of soil, the introduction of this device into the soil can be complicated, it is first necessary to introduce a tube comprising a screw thread into the soil or the materials to be sampled.

2. Once the sampling depth has been reached, turn the handle (3) half a turn to open the window (8) and sample the soil in the window of the inner tube (5 and 8).

3. To complete the filling of the window, both tubes are rotated approximately 5 turns. . 4. Once filled, the window must be closed by turning the inner tube half a turn (8).

5. The inner tube (2) is pulled out using an excavator or pulling device or by force of the arms. The 1 m lengths are gradually unscrewed one by one to obtain the soil sample. The soil is immediately collected in a suitable container. In another preferred embodiment, the external window (5) is provided with a scraper (6) making it possible to force the soil to be sampled to enter the sampler (1) when the latter has undergone significant heating and is become too hard to flow naturally to the sampler. The collected soil sample is then sent to an accredited laboratory to analyze the targeted pollutants. In another preferred embodiment, the said sampling technique consists in introducing the tube (1) into the ground through the TR tubes using a hammer. Again, in some cases the use of a tube with a screw thread is necessary before the introduction of the 40 sample tube (1 and 9).

_ BE2021/0009 5 In a preferred embodiment, the rod connected to the sampler (10) is provided with depth indications corresponding to the exact depth from which the sample was taken. | In a preferred embodiment, the rod consists of 2 coaxial rods. The external linked to the sampler (1) and the internal to the internal sliding element (9).

In a preferred embodiment, the hot sampler is placed on a conical tip (4), attached or not to said sampler; In a preferred embodiment, one or more windows of different sizes depending on the type of material to be removed (variable inner window — large and fixed outer)

Claims (6)

1. Soil sampling system allowing the extraction of a sample of hot soil, comprising at least one cylindrical element inserted into another cylindrical element of greater diameter allowing rotation of the internal element in the external element, and in which the internal element comprises at least one opening allowing the entry of the solid to be sampled when the latter is placed in such a position that the openings in the internal and external cylinder are aligned and allow the solid to be sampled to flow into the internal cylinder and such that the external cylinder is provided with a scraper making it possible to force the entry of soils into the sampler during the rotation of the latter. 2. System as in claim 1 wherein the inner and outer cylinders are of heat resistant metal 3. System as in claims 1 to 2 wherein the outer cylinder is provided with fins in the form of a spiral or fraction of a spiral in order to improve the introduction of the tool into the ground 4. System as in claims 1 to 3 where the external rod is provided with metric indications in order to determine the exact location of the sample 5. System as in claims 1 to 4 where the inner and outer cylinders are threaded | 6. System as in claims 1 to 5 where the outer cylinder is. equipped with fins in the form of a full or partial spiral and allowing better penetration into the ground;