JP-2026075311-A - Heat treatment well

Abstract

[Problem] To provide a heat treatment well that can purify a treatment area where contaminants exist only in deep regions by heating only the soil in those deep regions, thereby reducing the effort required to install suction wells. [Solution] A heat treatment well 1 is provided in which a heating well 11, a buffer section 13, and a suction well 12 are integrated by an outer tube 10 installed downward in the processing area A, a heating well heater 20a is placed inside the outer tube 10 that forms the heating well 11 and the buffer section 13, a through hole 13a is provided in the outer tube 10 that penetrates the outer tube 10, and the inside of the outer tube 10 that forms the buffer section 13 and the suction well 12 is in a negative pressure state. [Selection Diagram] Figure 1

Inventors

• 土田 充
• 小松 大祐
• 平澤 卓也
• 保坂 幸一
• 中島 邦将
• 中島 均
• 穂刈 利之
• 齋藤 亮
• ▲崎▼田 晃基

Assignees

• 清水建設株式会社

Dates

Publication Date

20260508

Application Date

20241022

Claims (7)

1. A heat treatment well is installed in a treatment area for contaminated soil where no contaminants are present in a shallow depth region from the surface to a certain depth, and contaminants are present in a deep depth region from the shallow depth region to a certain depth, A heating well installed in the aforementioned deep region, A suction well installed in the aforementioned shallow depth region, It has a buffer section positioned between the heating well and the suction well, and installed in the shallow depth region, The heating well, the buffer section, and the suction well are integrated by an outer tube installed downwards in the processing area. A heating well heater is placed inside the outer tube that forms the heating well and the buffer section. The outer tube forming the buffer portion is provided with a through hole that penetrates the outer tube. A heat treatment well in which the buffer section and the outer tube forming the suction well are under negative pressure.
2. A heat treatment well according to claim 1, wherein a ventilation layer filled with crushed stone and/or gravel is arranged to surround the outer wall of the outer pipe forming the heating well and the buffer section.
3. The heat treatment well according to claim 1, wherein a boundary plate is installed inside the outer tube to separate the heating well from the buffer section.
4. The heat treatment well according to claim 1, wherein a suction well heater is arranged within the outer tube forming the suction well.
5. The heat treatment well according to claim 4, wherein the heating well heater and the suction well heater are electrically heated insulating heaters.
6. The heating well heater has a heating element integrated with the heating element of the suction well heater, The heat treatment well according to claim 5, wherein the heat-generating portion of the heating well heater has a smaller cross-sectional area than the heat-generating portion of the suction well heater.
7. The heating well heater has a heating element integrated with the heating element of the suction well heater, The heat treatment well according to claim 5, wherein the heat-generating portion of the heating well heater is made of a material with higher electrical resistance than the heat-generating portion of the suction well heater.

Description

This invention relates to a heat treatment well. Soil can be contaminated with volatile organic compounds (VOCs), oils, mercury, polychlorinated biphenyls (PCBs), dioxins, and other substances. One known method for remediating contaminated soil is excavation and removal (excavation and removal method). This method is the simplest and most reliable way to remediate contaminated soil. However, it requires the removal of the contaminated soil, which must then be transported and processed. Therefore, this method incurs significant transportation and processing costs. Another method for remediating contaminated soil is in-situ remediation, which removes pollutants in the same location. Known in-situ remediation methods include bioremediation, which uses microorganisms to decompose pollutants, and chemical decomposition methods (Fenton process) that use hydrogen peroxide, etc. However, in in-situ remediation methods, if the soil in the area where the contaminated soil is located is clayey or silty with low permeability, it becomes extremely difficult to deliver the treatment chemicals to the contaminated soil. For this reason, in-situ remediation methods sometimes required a considerable amount of time to purify the contaminated soil. Furthermore, as an in-situ remediation method, in-situ thermal desorption, which uses heat to desorb contaminants from contaminated soil, is known. There are three methods of in-situ thermal desorption: the electric heating heater method, the electrical resistance method, and the steam method. Unlike methods using electric heating elements and steam, the in-situ thermal desorption method using electric heating elements can uniformly heat contaminated soil to over 100°C in situ. Therefore, in this method, the interstitial water in the soil of the treatment area can be sufficiently expanded as it turns into steam. Furthermore, the steam generated by heating the soil of the treatment area can desorb vaporized pollutants from the soil particles and also carry them along with the soil. As a result, the in-situ thermal desorption method using electric heating elements can efficiently remove pollutants from the contaminated soil of the treatment area. An example of an in-situ thermal desorption method using an electric heating element is the method described in Patent Document 1. Patent Document 1 describes a method in which heat is applied to a treatment area containing contaminants, a portion of the contaminants is vaporized, and this vapor is then aspirated and removed from the treatment area. Patent No. 4509558 Figure 1(a) is a schematic cross-sectional view showing the heat treatment well of the first embodiment. Figure 1(b) is a schematic cross-sectional view of the heat treatment well of the first embodiment, cut along the line I-I' shown in Figure 1(a), as seen from above in Figure 1(a). The heat treatment well of the present invention will be described in detail below, with appropriate reference to the drawings. The drawings used in the following description may be enlarged for convenience in order to clearly illustrate the features of the present invention. Therefore, the dimensional ratios of each component may differ from those of the actual components. The materials, dimensions, etc., exemplified in the following description are examples only, and the present invention is not limited to them. It can be implemented with appropriate modifications without altering the essence of the invention. [Heat-treated wells] Figure 1(a) is a schematic cross-sectional view showing the heat treatment well of the first embodiment. Figure 1(b) is a schematic cross-sectional view of the heat treatment well of the first embodiment, cut along the line I-I' shown in Figure 1(a), as seen from above in Figure 1(a). As shown in Figure 1(a), the heat treatment well 1 of this embodiment is installed and used in a treatment area A of contaminated soil where no contaminants are present in the shallow depth region D1 from the surface G to a certain depth, and contaminants are present in the deep depth region D2 from the shallow depth region D1 to a certain depth. As shown in Figure 1(a), the heat treatment well 1 of this embodiment includes a heating well 11 installed in a deep depth region D2, a suction well 12 installed in a shallow depth region D1, and a buffer section 13 positioned between the heating well 11 and the suction well 12 and installed in the shallow depth region D1. The depth dimension of the heating well 11 is determined according to the depth of the deep region D2 where the contaminants are present. That is, the depth dimension of the heating well 11 can be approximately the same as the depth of the deep region D2, and may be, for example, 5m to 10m or 10m to 20m. The depth dimension of the suction well 12 is shorter by the length of the buffer section 13 than the depth distance of the shallow depth region D1, and may be, for example, 3m to 8m or 8m to 18m. The depth dimension of the buff