Device and method for repairing polycyclic aromatic hydrocarbon in transformer substation soil through microwaves

Abstract

The invention belongs to the technical field of soil remediation, and discloses a device and method for microwave remediation of polycyclic aromatic hydrocarbon in transformer substation soil, and the method comprises the step that a mixture of the transformer substation soil to be remediated and an oxidizing agent is treated for 30-60 min under 250-1000 W microwaves. The device comprises a microwave generation system, a tuner and a quartz reactor, the microwave generation system comprises a microwave generator and a circulator which are connected, the circulator is connected with a tuner, and the tuner is connected with the quartz reactor. According to the method, the mixture of the transformer substation soil to be remediated and the oxidizing agent is treated under microwaves, modification of the soil polluted by the polycyclic aromatic hydrocarbon is achieved, compared with a pollutant treatment function of a traditional method, harmlessness of pollutants can be achieved, different pollutants in the soil can be removed at the same time, the process is simple, and the method is suitable for large-scale popularization and application. The number of devices is reduced, and the land area is effectively saved.

Description

Technical Field

[0001] The invention belongs to the technical field of soil remediation, and in particular relates to a device and method for microwave remediation of polycyclic aromatic hydrocarbons in substation soil. Background Art

[0002] A substation is a device used to convert high-voltage electricity into low-voltage electricity. It is usually used in power systems in cities or industrial areas. It is mainly used for the transmission and distribution of electric energy. It can convert electricity from high-voltage transmission lines into low voltage and then connect it to different power consumption areas. The main equipment of a substation includes transformers, voltage transformers, current transformers, circuit breakers, disconnectors, load switches, high-voltage fuses, lightning rods and arresters.

[0003] Since the electronic components and insulation materials used in substations contain harmful chemicals such as heavy metals (such as lead, mercury, cadmium, etc.), volatile organic compounds, etc., these chemicals can easily enter the soil and cause soil pollution. Organic pollution in the soil may inhibit the growth and development of plants, causing symptoms such as slow growth and yellowing of leaves. This will affect the yield and quality of crops and have an adverse impact on agricultural production. Soil organic pollution may destroy the balance of the soil ecosystem and lead to a decrease in soil biodiversity. This will affect the stability and resistance of the ecosystem, making it more susceptible to external interference and destruction. Therefore, it is necessary to conduct degradation experiments on the soil around the substation to obtain the best treatment effect of soil pollution.

[0004] Existing technologies for remediating contaminated substation soil include physical, chemical and biological technologies. Physical treatment is costly and complex, chemical treatment may introduce secondary pollution, and biological treatment is environmentally friendly but has a slow degradation rate, so it is necessary to provide an effective method for remediating contaminated substation soil. Summary of the invention

[0005] In order to overcome the problems of high cost and secondary pollution of substation soil treatment in the prior art, the purpose of the present invention is to provide a device and method for microwave remediation of polycyclic aromatic hydrocarbons in substation soil. The method utilizes microwave radiation combined with an oxidant without secondary pollution, which can effectively remove harmful substances in substation soil, protect the environment and human health, and has the advantages of being fast, efficient and low cost.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows: One aspect of the present invention provides a process for microwave remediation of polycyclic aromatic hydrocarbons in substation soil, comprising: The mixture of the substation soil to be repaired and the oxidant is treated under a microwave of 250-1000 W for 30-60 minutes.

[0007] A further improvement of the present invention is that the substation soil to be repaired contains polycyclic aromatic hydrocarbons.

[0008] A further improvement of the present invention is that the oxidant is hydrogen peroxide.

[0009] A further improvement of the present invention is that the usage ratio of the substation soil to be repaired to the hydrogen peroxide is 2g: 0.2-0.8ml, and the mass concentration of the hydrogen peroxide is 3%.

[0010] Another aspect of the present invention provides a device for repairing polycyclic aromatic hydrocarbons in substation soil using microwaves, comprising a microwave generating system, a tuner and a quartz reactor; The microwave generating system comprises a microwave generator and a circulator connected to each other, the circulator is connected to a tuner, and the tuner is connected to a quartz reactor.

[0011] A further improvement of the present invention is that it also includes a single-mode cavity for placing a quartz reactor.

[0012] A further improvement of the present invention is that it also includes a condensation system, an exhaust gas treatment device and a vacuum pump, the single-mode cavity is connected to the condensation system, and the condensation system is connected to the vacuum pump via the exhaust gas treatment device.

[0013] A further improvement of the present invention is that the tuner includes a piston tuner and a tuner.

[0014] A further improvement of the present invention is that the condensation system includes a condenser, a control system and a compressor, the single-mode cavity is connected to the compressor, the compressor is connected to the condenser, and the condenser is connected to the control system.

[0015] A further improvement of the present invention is that it also includes a power supply connected to the microwave generator.

[0016] Compared with the prior art, the present invention has the following beneficial effects: In the present invention, the soil contaminated by PAHs is modified by treating a mixture of the substation soil to be repaired and an oxidant under microwaves. Compared with the pollutant treatment function of the traditional method, this purification process can also achieve the harmlessness of pollutants and remove different pollutants in the soil at the same time. Compared with the traditional soil remediation method, the process flow of the present invention is simpler and significantly reduces the number of required equipment compared to the traditional pyrolysis treatment. This feature not only reduces the equipment investment cost, but also effectively saves land area, and the removal of PAHs reaches 99.9%. In addition, no by-products are produced during the microwave treatment process, avoiding the risk of secondary pollution. This green and environmentally friendly treatment method allows the present invention to improve the quality of substation soil while also helping to protect the surrounding ecological environment, reflecting the concept of sustainable development.

[0017] In the present invention, a microwave purification device for polycyclic aromatic hydrocarbons in soil is constructed by setting up a microwave generating system and a quartz reactor, and microwave radiation conditions + oxidants can be used to achieve the removal of organic matter such as polycyclic aromatic hydrocarbons in soil. The purification process of the present invention optimizes and improves the traditional system for degrading polycyclic aromatic hydrocarbons in soil. The soil is treated and then enters the microwave generating system, and is efficiently treated by microwave radiation. Compared with the traditional system, its process is simple, the device is reduced, and the land area is effectively saved.

[0018] Furthermore, hydrogen peroxide without secondary pollution is used as an oxidant, and there are no by-products, which is beneficial to protecting the surrounding environment.

[0019] Furthermore, the microwave generator uses high-frequency electromagnetic waves to generate electrical energy, which can quickly and evenly heat the pollutants in the soil, causing them to decompose or transform into harmless substances. The circulator is used to adjust the distribution of microwave energy and improve purification efficiency.

[0020] Furthermore, the condenser is used to cool the gas or steam and convert it into liquid. The condenser usually achieves the condensation process by transferring heat to a cooling medium (such as water or air). The control system is used to monitor and regulate the condensation process, including the control of temperature, pressure and flow. The compressor is used to compress the refrigerant gas into a high-pressure gas so that it can enter the condenser for condensation. The compressor is the microwave field source of the refrigeration system, ensuring that the refrigerant circulates in the system.

[0021] Furthermore, the exhaust gas treatment device can effectively treat other pollutants in the process and prevent them from spreading again, thereby reducing the impact on the surrounding environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Process flow chart for microwave remediation of PAHs in substation soil; Figure markings: 1-power supply, 2-microwave generator, 3-circulator, 4-tuner, 5-single mode cavity, 6-quartz reactor, 7-thermocouple system, 8-inlet, 9-condensation system, 10-exhaust gas treatment device, 11-vacuum pump. DETAILED DESCRIPTION

[0023] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly and comprehensively understood.

[0024] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0025] Polycyclic aromatic hydrocarbons (PAHs) refer to aromatic hydrocarbons containing two or more benzene rings. They have two main combinations: one is the non-condensed ring type, which includes biphenyl, biphenyls and polyphenylated aliphatic hydrocarbons; the other is the condensed ring type, that is, two carbon atoms are shared by two benzene rings.

[0026] PAHs are toxic, genotoxic, mutagenic and carcinogenic, which can cause multiple hazards to the human body, such as damage to the respiratory system, circulatory system, nervous system, liver and kidneys. They are identified as the main organic pollutants that affect human health.

[0027] The present invention is a microwave remediation method for polycyclic aromatic hydrocarbons pollutants in substation soil. This method adopts a microwave purification treatment and remediation system to effectively remove harmful substances in substation soil and protect the environment and human health.

[0028] See also Figure 1 The present invention discloses a microwave device for repairing polycyclic aromatic hydrocarbons in soil of a substation, comprising a power supply 1, a microwave generating system, a tuner 4, a quartz reactor 6, a thermocouple system 7, an injection port 8, a condensation system 9, an exhaust gas treatment device 10 and a vacuum pump 11, wherein: The power supply 1 is connected to the microwave generator 2 , and the power supply 1 provides the required electric energy for the microwave generator 2 to use.

[0029] The microwave generating system is composed of a microwave generator 2 and a circulator 3 connected to each other. The microwave generator 2 is composed of an oscillator and an antenna. The oscillator is the core component of the microwave generator 2 and is used to generate microwave signals. It achieves this function by generating high-frequency electrical signals. Common oscillator types include crystal oscillators, magnetrons, and fiber lasers. The antenna radiates microwave signals into space or receives microwave signals from space. The microwave generator 2 is a core device for providing a microwave field. The circulator 3 is used to absorb reflected power and protect the magnetron. The circulator 3 is connected to the tuner 4.

[0030] The microwave generator 2 is used to provide a microwave field. The microwave generator adopts 1.0KW, 2.45GHz and has stability.

[0031] Furthermore, the tuner 4 is composed of a piston tuner and a 3-slot tuner (i.e., the tuner has 3 slots) in an R340 waveguide, which are respectively used to superimpose incident waves and reflected waves in the cavity. The R340 waveguide can effectively guide microwave signals and reduce signal losses during transmission. The microwave generator 2 is connected to the load or antenna through a feeder. The tuner 4 can change the signal, frequency, and phase of the microwave to achieve information transmission, and the 3-slot tuner can ensure the minimum reflected power.

[0032] The quartz reactor 6 is used to place the substation soil containing polycyclic aromatic hydrocarbons. The quartz reactor 6 is arranged in the single-mode cavity 5 , and a thermocouple system 7 is arranged above the quartz reactor 6 .

[0033] A sample inlet 8 is provided at one side of the single-mode cavity 5 . The single-mode cavity 5 is connected to a condensation system 9 . The condensation system 9 is connected to a vacuum pump 11 via an exhaust gas treatment device 10 .

[0034] The quartz reactor 6 uses a piston of the WR340 waveguide, which can increase the stability of the reflected power.

[0035] Furthermore, the quartz reactor 6 is a device that uses a quartz tube to realize chemical reactions. The soil sample is placed in the quartz tube and reacts at high power.

[0036] Furthermore, the thermocouple system 7 is used to measure the temperature in the single membrane cavity 5 in the experiment, and has a small size and a short response time. Specifically, the thermocouple system 7 includes a thermocouple element, a protective tube and a temperature measuring instrument. The thermocouple element is the core part of the thermocouple, and is welded together by two different metal (or alloy) wires to form a junction. When the temperature of the junction is different from that of other parts, a thermoelectric potential (voltage) will be generated, and this voltage is related to the temperature difference. The protective tube is sleeved on the thermocouple element to protect the thermocouple element from the influence of the external environment (such as corrosion, high temperature or mechanical damage). The temperature measuring instrument is connected to the thermocouple element, and the temperature measuring instrument is used to convert the voltage signal generated by the thermocouple element into a readable temperature value.

[0037] Furthermore, the sample inlet 8 is used for adding soil samples and oxidant hydrogen peroxide, and the added amounts are precisely controlled.

[0038] Furthermore, the condensation system 9 is used for cooling the gas after the reaction, and includes a condenser, a control system, and a compressor. The compressor is connected to the condenser, and the condenser is connected to the control system. The condenser is used to cool the gas or steam and convert it into a liquid. The condenser usually realizes the condensation process by transferring heat to a cooling medium (such as water or air). The control system is used to monitor and regulate the condensation process, including the control of temperature, pressure, and flow. The compressor is used to compress the refrigerant gas into a high-pressure gas so that it can enter the condenser for condensation. The compressor is the microwave field source of the refrigeration system, ensuring that the refrigerant circulates in the system.

[0039] Furthermore, the exhaust gas treatment device 10 includes an activated carbon filter for treating other pollutant gases generated in the reaction to improve the exhaust gas treatment effect.

[0040] Furthermore, the pollution-free gas treated by the tail gas treatment device 10 is discharged through the vacuum pump 11 .

[0041] A microwave repair process for polycyclic aromatic hydrocarbons in substation soil in the present invention comprises the following steps: Pretreatment: Take out 2 grams of soil sample contaminated by PAHs and place it in the quartz reactor 6 in the center of the single-mode cavity 5, ensuring that the sample is aligned with the waveguide device to obtain the best microwave radiation effect.

[0042] Next, pre-irradiation was performed, the treatment time (t) was set between 30 and 60 minutes, a power (P) value of 230 to 1000 watts (W) was applied and 0.2-0.8 ml of hydrogen peroxide with a mass concentration of 3% was added through the injection port 8. The internal soil sample temperature was measured using a k-type thermocouple system.

[0043] Among them, the power range of 230 to 1000 watts can ensure the effective heating of soil samples during microwave radiation, promoting the decomposition and removal of pollutants.

[0044] The single cavity 5 is connected to the gas inlet of the condensation system 9. The condensation system 9 condenses the gas after the experiment, and then treats it with the tail gas treatment device 10, and then connects to the vacuum pump 11, and finally discharges the gas. After irradiation treatment, the soil sample is taken out of the equipment, stored in a sealed closed box, cooled at room temperature (20°C), and refrigerated (0°C) before analysis.

[0045] The following are specific embodiments.

[0046] Example 1 (2 grams of soil sample contaminated with benzopyrene, treatment time 35 minutes, microwave power 700 W, 0.6 ml of 3% mass concentration hydrogen peroxide).

[0047] Specific operation: Turn on the switch of power supply 1. At this time, microwave generator 2 starts to operate and microwave irradiates the soil sample (+0.6ml hydrogen peroxide) placed in quartz reactor 6. After the treatment, the gas released by the microwave irradiated soil sample is cooled by condensation system 9. Subsequently, these cooled gases pass through tail gas treatment device 10, and finally, the treated gas will be discharged through vacuum pump 11. After irradiation treatment, the soil sample is taken out of the equipment, stored in a sealed closed box, cooled at room temperature (20°C), and refrigerated (20°C) before analysis.

[0048] Treatment efficiency: Under this condition, the experimental treatment efficiency reaches 99.9%, and the removal rate can be considered to be 100%, with good removal effect.

[0049] Example 2 (2 grams of soil sample contaminated with benzopyrene, treatment time 30 minutes, microwave power 1000 W, 0.8 ml of hydrogen peroxide with a mass concentration of 3%).

[0050] Specific operation: Turn on the switch of power supply 1. At this time, microwave generator 2 starts to operate and microwave irradiates the soil sample (+0.6ml hydrogen peroxide) placed in quartz reactor 6. After the treatment, the gas released by the microwave irradiated soil sample is cooled by condensation system 9. Subsequently, these cooled gases pass through tail gas treatment device 10, and finally, the treated gas will be discharged through vacuum pump 11. After irradiation treatment, the soil sample is taken out of the equipment, stored in a sealed closed box, cooled at room temperature (20°C), and refrigerated (20°C) before analysis.

[0051] Treatment efficiency: Under this condition, the experimental treatment efficiency reaches 99.9%, and the removal rate can be considered to be 100%, with good removal effect.

[0052] Example 3 (2 grams of soil sample contaminated with benzopyrene, treatment time 60 minutes, microwave power 250 W, 0.2 ml of 3% mass concentration hydrogen peroxide).

[0053] Specific operation: Turn on the switch of power supply 1. At this time, microwave generator 2 starts to operate and microwave irradiates the soil sample (+0.6ml hydrogen peroxide) placed in quartz reactor 6. After the treatment, the gas released by the microwave irradiated soil sample is cooled by condensation system 9. Subsequently, these cooled gases pass through tail gas treatment device 10, and finally, the treated gas will be discharged through vacuum pump 11. After irradiation treatment, the soil sample is taken out of the equipment, stored in a sealed closed box, cooled at room temperature (20°C), and refrigerated (20°C) before analysis.

[0054] Treatment efficiency: Under this condition, the experimental treatment efficiency reached 87.3%, which has a good removal effect.

[0055] Comparative Example 2 (2 g soil sample contaminated with benzopyrene, heat treatment time 35 minutes) Specific operation: Directly heat the soil sample through direct heating equipment to promote the thermal desorption of pollutants, the temperature is 300℃ (when the microwave power is 700W, the temperature is detected at 280-300℃) to achieve the removal effect. Finally, store it in a sealed closed box, cool it at room temperature (20℃), and refrigerate it (20℃) before analysis.

[0056] Treatment efficiency: The experimental treatment efficiency under this condition reached 63.8%. It can be considered that direct heating has a certain treatment effect, but the removal effect is not ideal and the consumption is huge.

[0057] Comparative Example 3 (2 g soil sample contaminated with benzopyrene, treatment time 35 min, microwave power 700 W) Specific operation: Turn on the switch of the power supply 1. At this time, the microwave generator 2 starts to operate and performs microwave radiation treatment on the soil sample placed in the quartz reactor 6. After the treatment is completed, the gas released by the microwave-irradiated soil sample is cooled by the condensation system 9. Subsequently, these cooled gases pass through the exhaust gas treatment device 10, and finally, the treated gas will be discharged through the vacuum pump 11. After irradiation treatment, the soil sample is taken out of the equipment, stored in a sealed closed box, cooled at room temperature (20°C), and refrigerated (20°C) before analysis.

[0058] Treatment efficiency: The treatment efficiency under this condition reached 85.3%. It can be considered that microwave radiation has a certain treatment effect, but some wastes are still not removed.

[0059] Comparative Example 4 (2 g soil sample contaminated with benzopyrene, treatment time 35 minutes, hydrogen peroxide addition amount 0.6 ml) Specific operation: Combine the soil sample with 0.6 ml of hydrogen peroxide, mix thoroughly, seal and place for 35 minutes.

[0060] Treatment efficiency: Under this condition, the experimental treatment efficiency reached 74.4%. The addition of oxidant hydrogen peroxide has a certain effect on the pollutant treatment effect.

[0061] It can be seen from the experimental results of the above Example 1 and Comparative Examples 2, 3 and 4 that under the same conditions, the microwave + oxidant treatment method, which combines physics and chemistry, has a significantly improved removal effect compared to traditional thermal desorption (direct heating or indirect heating), and the removal effect in Example 1 reaches 99.9%; by comparing Examples 1-3, it can be concluded that under the same treatment conditions, for the consideration of treatment effect and economy, the optimal treatment parameters of this method are: 2 grams of soil sample, 35 minutes of treatment time, 700 W of microwave power, and 0.6 ml of 3% mass concentration of hydrogen peroxide. And through the subsequent tail gas treatment analysis, it is concluded that there are no other pollutants, so it is believed that this process is a fast and efficient treatment method for soil organic pollutants.

[0062] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

[0063] In addition, it should be understood that although this specification is described in accordance with the implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art. The above content is only to illustrate the technical idea of ​​the present invention, and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution according to the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A microwave repair process for polycyclic aromatic hydrocarbons in substation soil, characterized in that: include: The mixture of the substation soil to be repaired and the oxidant is treated under a microwave of 250-1000 W for 30-60 minutes.

2. The microwave repair process for polycyclic aromatic hydrocarbons in substation soil according to claim 1 is characterized in that: The soil of the substation to be remediated contains PAHs.

3. The microwave repair process for polycyclic aromatic hydrocarbons in substation soil according to claim 1 is characterized in that: The oxidant is hydrogen peroxide.

4. The microwave repair process for polycyclic aromatic hydrocarbons in substation soil according to claim 3 is characterized in that: The usage ratio of the substation soil to be repaired to hydrogen peroxide is 2g: 0.2-0.8ml, and the mass concentration of hydrogen peroxide is 3%.

5. A device for repairing polycyclic aromatic hydrocarbons in substation soil using microwaves according to any one of claims 1 to 4, characterized in that: It comprises a microwave generating system, a tuner (4) and a quartz reactor (6); The microwave generating system comprises a microwave generator (2) and a circulator (3) connected to each other, the circulator (3) is connected to a tuner (4), and the tuner (4) is connected to a quartz reactor (6).

6. The device for microwave repair of polycyclic aromatic hydrocarbons in substation soil according to claim 5 is characterized in that: It also includes a single-mode cavity (5) for placing a quartz reactor (6).

7. The device for microwave repair of polycyclic aromatic hydrocarbons in substation soil according to claim 6 is characterized in that: It also includes a condensation system (9), an exhaust gas treatment device (10) and a vacuum pump (11); the single-mode cavity (5) is connected to the condensation system (9), and the condensation system (9) is connected to the vacuum pump (11) via the exhaust gas treatment device (10).

8. The device for repairing polycyclic aromatic hydrocarbons in soil of a substation by microwave according to claim 5 is characterized in that: The tuners (4) include piston tuners and 3-slot tuners.

9. The device for microwave repair of polycyclic aromatic hydrocarbons in substation soil according to claim 5 is characterized in that: The condensation system (9) comprises a condenser, a control system and a compressor. The single-mode cavity (5) is connected to the compressor, the compressor is connected to the condenser, and the condenser is connected to the control system.

10. The microwave repair device for polycyclic aromatic hydrocarbons in substation soil according to claim 5, characterized in that: It also includes a power source (1) connected to the microwave generator (2).

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