RU2190844C2 - Sensor of leakage of liquid oil products - Google Patents

Abstract

FIELD: environment protection against pollution, detection of leakage of liquid oil products into ground. SUBSTANCE: sensor has two or more electrodes, one on them being surrounded by layer of dielectric material. Dielectric layer is completely or partially made of material soluble in liquid oil products. Resistance between electrodes of sensor quickly falls approximately by a factor of three if leakage of oil products to wet ground near sensor located nearby happens which makes it feasible to obtain reliable and authentic registration of little leakage of oil product to ground. EFFECT: reliable and authentic registration of leakage of oil products to ground. 3 cl, 4 dwg

Description

 The invention relates to the field of environmental protection from pollution and can be used to detect leakage of liquid petroleum products into the soil.

 A known leakage sensor of liquid petroleum products (European patent 306183, class C 01 N 27/12), which is two or more conductor electrodes surrounded by a layer of a polymer material - polytetrafluoroethylene, which has a porous structure interspersed with carbon and in the absence of liquid petroleum is dielectric with low resistivity. In the presence of a liquid petroleum product, the latter fills the pores of the polymer and significantly increases its resistivity. As a result, the electrical resistance between the electrodes increases, which can be detected by a resistance meter connected to the electrodes - an ohmmeter.

 The main disadvantage of the known sensor is its unsuitability for detecting leaks of liquid petroleum products into wet soil. When the known sensor is located in moist soil, moisture fills the pores of the polymer, after which displacement by liquid oil becomes problematic. The multiplicity of the change in resistance between the electrodes of the known sensor even under ideal conditions does not exceed several times, and when it is located in moist soil, it becomes even smaller, which is insufficient for reliable detection of small leaks.

 The proposed device solves the technical problem of creating a liquid oil product leak detector, which, when located in wet soil, provides reliable and reliable detection of relatively small (up to several liters) local liquid oil product leaks near the sensor installation site.

 To solve the problem, in a liquid oil product leak detector containing two or more electrodes, at least one of which is surrounded by a dielectric layer, said layer is at least partially made of a material soluble in liquid oil products. As a material soluble in liquid petroleum products, bitumen can be used.

 In FIG. 1-4 presents various design options of the proposed sensor. In the simplest case, the proposed sensor contains two electrodes 1 and 2 (Fig. 1). The electrode 1 is surrounded by a layer 3 of a dielectric soluble in liquid petroleum products, for example, a layer of bitumen. Wires 4 are used to connect the electrodes 1 and 2 to the resistance meter. Both electrodes are placed in the ground 5.

 More compact and easy to use is the sensor shown in FIG. 2. It contains a dielectric plate 6, on the opposite surfaces of which are located the electrodes 1 and 2, made in the form of electrically conductive coatings. A layer 3 of a dielectric material soluble in liquid petroleum products is applied on top of the electrodes. In particular, the dielectric plate 6 can be made of getinaksa, the electrodes 1 and 2 from copper foil glued on the surface of the getinaksa plate. A layer 3 of a dielectric material soluble in liquid petroleum products can be deposited on the surface of the dielectric plate 6 together with the electrodes 1 and 2 located on it by dipping this plate in bitumen varnish.

 More reliable in operation is the sensor shown in figure 3. The sensor contains two dielectric plates 7 and 8, mounted against each other. The holes 7 are made in the plate 7. On the surface of the plate 8 are electrodes 1 and 2, made in the form of electrically conductive coatings, on which a layer of a dielectric material soluble in liquid petroleum products is applied. The gap between the plates 7 and 8 is filled with a porous hygroscopic material, for example, a strip 10 of fabric folded in several layers. The sensor shown in FIG. 4, differs from that described above in that the electrode 2 with a layer 3 of a dielectric material soluble in liquid petroleum products 3 is located on the surface of the plate 8 facing the surface of the plate 7 on which the electrode 1 with a layer 3 of soluble in liquid petroleum products deposited on it is located dielectric material. In this case, holes 11 can be made in the plate 8. In the last two cases (Figs. 3 and 4), the plates 7 and 8 are mechanically fastened together and together with the electrodes 1 and 2, the gasket 10, and also wires 4 form a rigid sensor , which is placed in the soil 5. When the sensor is buried in the soil, the dielectric layer 3 cannot be damaged, since it is protected by dielectric plates 7 and 8.

 The sensor depicted in figure 1, operates as follows. In the initial state, the resistance between the electrodes 1 and 2 is large and is determined by the resistance of the layer 3 of the dielectric material. If liquid petroleum product, such as gasoline, enters the soil, the latter spreads, capturing the area of the sensor. In this case, the dielectric layer 3 surrounding the electrode 1, at least partially dissolves. The resistance between electrodes 1 and 2 decreases sharply, as it is now determined mainly by the contact resistance of electrode 1 with wet soil, which can be detected by a resistance meter connected to wires 4. Wet soil acts as a conductor connecting electrodes 1 and 2 to each other after the destruction of the dielectric layer 3, and has a resistance substantially less than the contact resistance of the electrode with the soil.

 The following experiment was conducted using the sensor shown in figure 2. The sensor was neatly covered with wet sand, after which the resistance between the electrodes was measured, which amounted to more than 2 MΩ in direct current. Then, near the sensor, 50 ml of gasoline was poured into the sand. After gasoline leaked to the sensor, which could be visually checked by expanding the area of wetted sand, the resistance between the electrodes decreased from 2 MΩ to several kOhm, that is, about 1000 times. After digging the sensor, the inspection revealed a significant destruction of the bitumen film under the action of gasoline. The resistance R and capacitance C between the sensor electrodes at a frequency of 1 kHz were also measured using an E7-8 automatic digital bridge using a sequential equivalent circuit. Prior to filling gasoline, the sensor impedance parameters were: R = 3.58 MΩ, C = 160 pF. After filling gasoline: R = 2.5 kOhm, C = 16000 pF. Thus, the change in the components of the impedance R and C of the sensor at a frequency of 1 kHz, as well as at direct current, was more than 1000 times, which makes it possible to detect even small leaks of liquid petroleum products into the ground with a high degree of reliability.

 When using the sensor designs shown in Figs. 3 and 4, the gasket 10, made of a porous hygroscopic material, is moistened with water present in the soil penetrating through the openings 9 (11). In the presence of an oil product leak, the latter penetrates through the holes 8 to the gasket 10 and reaches the dielectric layer 3 through the capillaries of its porous material, dissolving it. In this case, as with the other sensors considered, the resistance between the electrodes decreases sharply.

 Thus, due to the fact that a material soluble in liquid oil is used as a dielectric in the sensor, in the presence of a leak of oil near the location of the sensor, the resistance between the electrodes of the latter quickly changes from the insulation resistance of the electrodes, which is at least several MΩ, to the contact resistance of the electrode with moist soil, amounting to not more than a few kOhm, that is, 1000 times. This allows you to achieve reliable and reliable operation of the sensor located in wet soil, even with small leaks of oil.

Claims (4)

 1. A leak detector of liquid petroleum products containing two or more electrodes, at least one of which is surrounded by a dielectric layer, characterized in that the dielectric layer is at least partially made of a material soluble in liquid petroleum products.  2. The leakage sensor of liquid petroleum products according to claim 1, characterized in that bitumen is used as a material soluble in liquid petroleum products.  3. The leakage sensor of liquid petroleum products according to claims 1 and 2, characterized in that it contains a dielectric plate, while the electrodes are made in the form of electrically conductive coatings located on opposite surfaces of this plate, and a dielectric material soluble in liquid petroleum products is applied to the electrically conductive coatings.  4. The leakage sensor of liquid petroleum products according to claims 1 and 2, characterized in that it contains two dielectric plates placed against each other, at least one of which has holes, and the electrodes are made in the form of conductive coatings located at least on one of the surfaces of the dielectric plates facing each other, a dielectric material soluble in liquid petroleum products is deposited on electrically conductive coatings, and the gap between the plates is filled with porous hygroscopic material.

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