Potential difference-based diversion electrode arrangement and field intensity compensation method

Abstract

The present invention relates to a potential difference-based diversion electrode arrangement and field intensity compensation method, comprising the following steps: the arrangement positions of paired diversion electrodes are determined according to the difference of potential around a position of field intensity to be compensated and the direction of an electric field line, and the paired diversion electrodes are inserted; and the field intensity enhancement rate of the position of field intensity to be compensated and the compensated field intensity value are calculated according to the difference of potential and arrangement positions of the paired diversion electrodes. In the present invention, the paired diversion electrodes are arranged in the direction of the electric field line by using the spatial difference of potential in the electric field, and the compensation of local field intensity is implemented, thereby beneficial to improving the overall efficiency of electrokinetic remediation for organic contaminated soil, and reducing the spatial difference of remediation efficiency.

Claims

1. A potential difference-based diversion electrode arrangement and field intensity compensation method, comprising the following steps: determining arrangement positioning of a paired set of diversion electrodes, which arrangement positioning is determined according to a difference of potential around a position of field intensity to be compensated and the direction of an electric field line formed by an additional pair of matrix electrodes, and the paired set of diversion electrodes are spaced along the electric field line in accordance with the determined arrangement positioning, and wherein the paired set of diversion electrodes are composed of opposite polarity electrode A and electrode B, and a conducting line connecting the electrode A and electrode B, and wherein determining the arrangement positioning of the paired set of diversion electrodes according to the difference of potential around the position of field intensity to be compensated and the direction of an electric field line comprises the following steps: the electrode A and the electrode B are installed at both sides, at equal distances, of the geometric center of a region to be compensated that is determined to be a position c of field intensity to be compensated, the position c of field intensity to be compensated satisfying the following conditions: (i) the positions of installation of the paired set of diversion electrodes A and B are a and b respectively, and a, b and c are on the same electric field line f, (ii) a difference of potential exists between the positions a and b; (iii) change in the potential between the positions a and b in the direction of the electric field line is monotone increasing or monotone decreasing.

2. The potential difference-based diversion electrode arrangement and field intensity compensation method of claim 1, wherein the paired set of diversion electrodes are made of the same material.

3. The potential difference-based diversion electrode arrangement and field intensity compensation method of claim 1, wherein the electrode A and the electrode B are arranged in parallel, and the upper ends are connected by the conducting line; and the upper end of the electrode A is opposite to the upper end of the electrode B in polarity.

4. The potential difference-based diversion electrode arrangement and field intensity compensation method of claim 1, wherein after the paired set of diversion electrodes are installed there is an enhancement in, the field intensity enhancement rate of the position of field intensity to be compensated.

5. The potential difference-based diversion electrode arrangement and field intensity compensation method of claim 4, wherein the enhancement in the field intensity rate of the position of field intensity to be compensated, which is provided by the installment of the paired set of diversion electrodes, is: $I = \frac{K .Math. U_{a} d_{a c}^{2} + U_{b} d_{bc}^{2} .Math.}{d_{a c}^{2} d_{b c}^{2} E_{c}}$ wherein I is the field intensity enhancement rate of the position c of field intensity to be compensated; U.sub.a and U.sub.b are potential of the positions a and b; d.sub.ac and d.sub.bc are distances between the position a and the position c, and the position b and the position c respectively; E.sub.c is the original field intensity of the position c; and K is an attenuation coefficient of the potential in a dielectric.

6. The potential difference-based diversion electrode arrangement and field intensity compensation method of claim 4, wherein installation of the paired set of diversion electrodes results in the compensated field intensity value being:
E=(1+I)E.sub.c wherein E is the compensated field intensity of the position c of field intensity to be compensated; I is the original field intensity enhancement rate of the position c of field intensity to be compensated; and E.sub.c is the original field intensity of the position c.

Description

DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a composition diagram showing an apparatus with paired diversion electrodes in the present invention;

(2) FIG. 2 is a schematic diagram showing a potential isoline in an electric field and a spatial distribution of field intensity in embodiment 1 of the present invention;

(3) FIG. 3 is a diagram showing a position of field intensity to be compensated and arrangement positions of paired diversion electrodes in embodiment 1 of the present invention;

(4) FIG. 4 is a diagram showing a position of field intensity to be compensated and arrangement positions of paired diversion electrodes in embodiment 2 of the present invention.

DETAILED DESCRIPTION

(5) The present invention will be further described in detail below in combination with the drawings and the embodiments.

(6) A potential difference-based diversion electrode arrangement and field intensity compensation method, comprising the following steps:

(7) (1) The arrangement positions of paired diversion electrodes are determined according to the difference of potential around the position of field intensity to be compensated and the direction of an electric field line;

(8) (2) The field intensity enhancement rate of the position of field intensity to be compensated and the compensated field intensity value are calculated according to the difference of potential and arrangement positions of the paired diversion electrodes,

(9) wherein

(10) (1) The paired diversion electrodes are specifically composed of an electrode A and an electrode B which are made of the same material, and a conducting line connecting the two;

(11) (2) The electrode A and the electrode B which are connected by the conducting line are placed in the electric field, to form a closed loop, and the field intensity compensation is implemented through a local electrode reaction.

(12) The arrangement positions of the diversion electrodes should meet the following conditions:

(13) (1) The arrangement positions a and b of the paired diversion electrodes A and B should cover the position c of field intensity to be compensated;

(14) (2) The positions a, b and c should be on the same electric field line f;

(15) (3) A difference of potential exists between the positions a and b, U=|UaUb|>0; Uc and Ub are potential of the positions a and b;

(16) (4) The change in the potential between the positions a and b in the direction of the electric field line is monotone increasing or monotone decreasing, i.e. (U.sub.xU.sub.y)(xy)>0 (x, y{any two points between the positions a and b on the electric field line f, and xy}).

(17) The field intensity enhancement rate and the compensated field intensity value are specifically calculated by the following technical method:

(18) (1) After diversion electrodes are arranged according to the conditions, the field intensity enhancement rate I of the position c is as shown in formula (1):

(19) $\begin{matrix} I = \frac{K .Math. U_{a} d_{a c}^{2} + U_{b} d_{bc}^{2} .Math.}{d_{a c}^{2} d_{b c}^{2} E_{c}} & formula (1) \end{matrix}$

(20) wherein I is the field intensity enhancement rate (%) of the position c; U.sub.a and U.sub.b are potential (V) of the positions a and b; d.sub.ac and d.sub.bc are distances (cm) between the position a and the position c, and the position b and the position c respectively; E.sub.c is the original field intensity (V/cm) of the position a; and K is an attenuation coefficient (cm.sup.1) of the potential in a dielectric.

(21) (2) The compensated field intensity value E is calculated by the method as shown in formula (2)
E=(1I)Ecformula (2)

(22) wherein E is the compensated field intensity (V/cm) of the position c; I is the original field intensity enhancement rate (%) of the position c; and Ec is the original field intensity (V/cm) of the position c.

Embodiment 1

(23) The contaminated soil remedied in this embodiment is petroleum-contaminated soil configured in the laboratory, the collected soil is loamy soil from which macroscopic impurities and roots of grass and trees are removed, is air-dried naturally indoors and then sieved using a sieve of 2 mm, petroleum is extracted from a certain petroleum pit of Shuguang Oil Production Plant, Liaohe Oil Field Company, and is prepared into petroleum-contaminated soil of 45 g/kg. The prepared soil is air-dried naturally for 7 days, the moisture content is adjusted to be 20% using deionized water, three treatments are conducted, i.e. control remediation, electrokinetic remediation and electrokinetic remediation for field intensity to be compensated, and the soil is respectively loaded into a remediation apparatus (20 cm L10 cm W10 cm H).

(24) As shown in FIG. 1, the contaminated soil remediation apparatus has an arrangement manner of electrodes of 12, and the electrodes are made of graphite, each having a diameter of 1 cm, a height of 11 cm, and an external voltage of 20V. The two electrodes are kept to be opposite in polarity, and the formed electric field is as shown in FIG. 2. The electrode polarity switching time is 4 h, and the remediation time is 60 d.

(25) The specific operation flow includes:

(26) Step 1: An appropriate coordinate system covering the overall electric field is established according to the arrangement positions of electrodes and the spatial distribution of the electric field, and the position of field intensity to be compensated is determined according to the spatial distribution of pollutants;

(27) (1) An X-Y coordinate system which takes a connecting line between the original electrode P1 and electrode P2 as X axis (lateral axis) and a middle line of the connecting line between the electrode P1 and the electrode P2 as Y axis (longitudinal axis) is established (FIG. 3) according to the arrangement positions of the electrodes and the spatial distribution of the electric field (FIG. 2), wherein the positions of the electrode P1 and the electrode P2 are (10, 0) and (10, 0) respectively;

(28) (2) By taking the sum of the mean value of pollutant concentrations and the standard deviation as a threshold, the spatial distribution of the pollutant concentrations is divided into a high concentration region and a low concentration region; and because of the heterogeneity of the spatial distribution of pollutants, if field intensity compensation is conducted at the geometric center of the region with higher pollutant content, the position c of field intensity to be compensated is (6, 0).

(29) Step 2: The arrangement positions of paired diversion electrodes are determined according to the difference of potential around the position of field intensity to be compensated and the direction of an electric field line;

(30) (1) The positions a and b meeting the following conditions are selected:

(31) Condition 1: The positions a, b and c should be on the same electric field line f;

(32) Condition 2: A difference of potential exists between the positions a and b, i.e. U=|UaUb|>0;

(33) Condition 3: The change in the potential between the positions a and b in the direction of the electric field line is monotone increasing or monotone decreasing, i.e. (U.sub.xU.sub.y)(xy)>0 (x, y {any two points between the positions a and h on the electric field line f, and xy}).

(34) (2) The diameter of each of the electrodes is taken into account, to guarantee that the electrodes are not overlapped with each other; the paired diversion electrodes A and B are arranged at both sides of the position c at equal distance, and the arrangement positions a and b in this embodiment are (9, 0) and (3, 0) respectively.

(35) (3) The positions a, b and a are all on the electric field line of y=0, a difference of potential exists between a and b, i.e. U=|9.470.66|=8.81>0, and the change in the potential between the positions a and b in the direction of the electric field line is monotone decreasing.

(36) Step 3: The field intensity enhancement rate and the compensated field intensity value of the position of field intensity to be compensated are calculated according to the difference of potential and arrangement positions of the paired diversion electrodes;

(37) (1) It is measured through experiment that the soil in this embodiment is loamy soil, when the moisture content is 20%, the attenuation coefficient K of field intensity can be calculated by the comparison between the actually measured value and the theoretical value of the potential at the position c, namely, K at the position c is equal to U.sub.actually measured value/U.sub.theroretical value=0.45;

(38) (2) Values of potential U.sub.a, U.sub.b and U.sub.c at the positions a, b and c are measured by a high-precision potential measuring instrument;

(39) (3) According to the positions of a, b and c in the X-Y coordinate system, calculation is conducted to obtain distances d.sub.ac and d.sub.bc between a and c, and b and c;

(40) (4) The field intensity E.sub.c of the position c is calculated according to the actually measured value U.sub.c and the spatial distribution of field intensity in this embodiment;

(41) (5) Parameter values required by the formula (1) are shown in Table 1 in details:

(42) TABLE-US-00001 TABLE 1 Calculation Parameters of Field Intensity Enhancement Rate Items K U.sub.a U.sub.b d.sub.ac d.sub.bc E.sub.c Unit cm.sup.1 V V cm cm V/cm Source Exper- Actual Actual Calcu- Calcu- Actual iment measure- measure- lation lation measure- ment ment ment Numer- 0.45 9.47 0.66 3 3 0.59 ical Values

(43) (2) According to formula (1) and formula (2), the field intensity enhancement rate I of the position c of field intensity to be compensated and the compensated field intensity value E are calculated respectively as:
I=0.45|9.473.sup.2+0.663.sup.2|/(3.sup.23.sup.20.59)=85.8%
E=(1+0.858)0.59=1.10 (V/cm)

(44) Step 4: Sampling is conducted and remediation results are compared:

(45) (1) Point arrangement sampling is conducted according to a grid of 53, and the concentration of petroleum pollutants in soil, i.e. the residual amount after remediation, is measured using the infrared spectropliotometry.

(46) (2) Experiment treatment results are shown in Table 2 in detail.

(47) TABLE-US-00002 TABLE 2 Experiment Treatment Results Degree of Initial variation of pollutant Remediation residual content efficiency amount space Groups Treatment (g/kg) (%) (%) Control No 45 6 3.4 12.4 group Experimental Electrokinetic 43 3 53.7 8.7 group 1 remediation Experimental Electrokinetic 47 7 65.7 3.2 group 2 remediation for field intensity to be compen- sated

Embodiment 2

(48) Embodiment 2 is different from embodiment 1 in that:

(49) The remedied contaminated soil is pyrene-contaminated soil, the pyrene content is about 100 mg/kg, and the soil is sandy loam soil. Three treatments are conducted, i.e. control remediation, electrokinetic remediation and electrokinetic remediation for field intensity to be compensated, and the soil is respectively loaded into a remediation apparatus (24 cm L12 cm W10 cm H).

(50) The contaminated soil remediation apparatus has an arrangement manner of electrodes of 12, and the electrodes are made of iron, each having a diameter of 1 cm, a height of 11 cm and an external voltage of 24V. The two electrodes are kept to be opposite in polarity. The electrode polarity switching time is 2 h, and remediation time is 30 d.

(51) The specific operation flow includes:

(52) Step 1: The position of field intensity to be compensated is determined;

(53) (1) An X-Y coordinate system is established (FIG. 4) according to the arrangement positions of the electrodes and the spatial distribution of the electric field, wherein the positions of the electrode P.sub.1 and the electrode P.sub.2 are (12, 0) and (12, 0) respectively;

(54) (2) if field intensity compensation is conducted at the geometric center of the region with higher pollutant content in this embodiment, the position c of field intensity to be compensated is (5, 0).

(55) Step 2: The arrangement positions of paired diversion electrodes are determined;

(56) (1) The electric field characteristics, the positions a, b and c, and the diameters of the electrodes are comprehensively taken into account, the paired diversion electrodes A and B are arranged at both sides of the position a at equal distance, and the arrangement positions a and b are (9, 0) and (1, 0) respectively;

(57) (2) The positions a, b and c are all on the electric field line of a difference of potential exists between a and b, i.e. U=|9.470.66|=8.81>0, and the change in the potential between the positions a and b in the direction of the electric field line is monotone decreasing.

(58) Step 3: The field intensity enhancement rate of the field intensity position to be compensated and the compensated field intensity value are calculated;

(59) (1) Parameter values K, U.sub.a, U.sub.b, d.sub.ac d.sub.bc and E.sub.c are obtained by experiment, actual measurement and calculation, see Table 3 for details.

(60) TABLE-US-00003 TABLE 3 Calculation Parameters of Field Intensity Enhancement Rate Items K U.sub.a U.sub.b d.sub.ac d.sub.bc E.sub.c Unit cm.sup.1 V V cm cm V/cm Source Exper- Actual Actual Calcu- Calcu- Actual iment measure- measure- lation lation measure- ment ment ment Numer- 0.53 3.43 0.17 4 4 0.20 ical values

(61) (2) According to formula (I) and formula (2), the field intensity enhancement rate I of the position c of field intensity to be compensated and the compensated field intensity value E are calculated respectively as:
I=0.53|3.434.sup.2+0.174.sup.2|/(4.sup.24.sup.20.02)=59.6%
E=(1+0.596)0.20=0.32 (V/cm)

(62) Step 4: Sampling is conducted and remediation results are compared:

(63) (1) Point arrangement sampling is conducted according to a grid of 53 the concentration of pyrene in soil, i.e. the residual amount after remediation, is measured using the EPA method.

(64) (2) Experiment treatment results are shown in Table 4 in detail.

(65) TABLE-US-00004 TABLE 4 Experiment Treatment Results Degree of Initial variation of pollutant Remediation residual content efficiency amount space Groups Treatment (mg/kg) (%) (%) Control no 100 7 2.4 7.8 group Experimental Electrokinetic 100 10 49.8 7.1 group 1 remediation Experimental Electrokinetic 100 8 57.4 2.9 group 2 remediation for field intensity to be compen- sated

(66) The above contents are further detailed descriptions of the present invention in combination with specific preferential embodiments. However, it cannot be considered that the specific embodiments of the present invention are only limited to these descriptions. Several simple deductions or replacements may be made without departing from the conception of the present invention, all of which shall be considered to belong to the protection scope of the present invention.

Potential difference-based diversion electrode arrangement and field intensity compensation method

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A01B47/00

HUMAN NECESSITIES

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B09C2101/00

PERFORMING OPERATIONS; TRANSPORTING

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B09C1/08

PERFORMING OPERATIONS; TRANSPORTING

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B09C1/085

PERFORMING OPERATIONS; TRANSPORTING

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B09C1/08

PERFORMING OPERATIONS; TRANSPORTING

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A01B47/00

HUMAN NECESSITIES

Abstract

Claims

Description