CN116026646A - Soil and groundwater VOC on-line monitoring device and method - Google Patents

Abstract

The invention discloses an on-line monitoring device and method for VOC of soil and underground water, wherein the device comprises: the underground water VOC collecting unit heats underground water with a preset volume collected on site to boil, and the VOC in the underground water volatilizes and simultaneously the gas phase in the liquid enters the upper part of the liquid surface to blow off the VOC; the soil VOC acquisition unit heats soil around the soil VOC monitoring well with the air covering belt, and the VOC in the soil is absorbed into the gas phase through pyrolysis; and the VOC on-line monitoring unit is used for receiving the underground water VOC and the soil VOC transmitted through the high-temperature heat tracing sampling pipe and respectively detecting the concentration. The device and the method can overcome the technical defect of insufficient detection precision caused by insufficient VOC volatilization in the on-site sampling process of the petrochemical field, and can simultaneously realize on-line monitoring and early warning of VOC pollution of soil and underground water of the petrochemical field.

Description

Soil and groundwater VOC on-line monitoring device and method

Technical Field

The invention relates to the technical field of petrochemical field environment protection, in particular to an on-line monitoring device and method for VOC (volatile organic compounds) in soil and underground water.

Background

Petroleum is taken as a main component of global energy and plays a vital role in the development process of national economy. However, petroleum inevitably leaks during exploitation, transportation, processing and storage, severely damaging the soil and groundwater environments. VOCs are representative pollutants of petrochemical fields, have certain toxicity and cancerogenic harm, and when the content of the VOCs in the environment exceeds a certain amount, the human body can show visual phenomena such as memory decline and the like, and even can generate serious harm to livers, nerves, brains and the like of the human body. Therefore, the on-line monitoring and early warning of the VOC of the soil and the underground water are of great significance.

At present, the soil and groundwater VOC monitoring has the following problems:

1) The soil and underground water VOC pollution monitoring mainly relies on manually collecting soil and underground water samples for detection, and has the problems of long period, high sampling operation requirement, high sample preservation environment requirement, sample distortion and the like, so that pollution problems can not be found in time and the pollution problems can not be responded quickly;

2) The gas chromatograph used by the existing underground water VOC on-line monitoring system has high requirements on experimental environment and high purchase and use costs;

3) The existing site VOC on-line monitoring system is difficult to realize the synchronous on-line accurate monitoring and early warning of the pollution of the underground water and the soil VOC by using the same monitoring system, and if the underground water and the soil VOC use different monitoring devices, the site on-line monitoring cost is high, and the large-scale popularization and application are difficult;

4) The concentration of volatile organic compounds in groundwater and soil at the initial stage of pollution is low, and the existing system for monitoring VOC in gas phase and soil gas at the upper part of an underground water well is influenced by factors such as the tightness of a monitoring well, the concentration of VOC in a medium, the temperature, the volatilization degree and the like, and cannot accurately monitor and early warn.

Chinese patent application CN110057396a discloses a soil and groundwater volatile organic compound continuous monitoring system and early warning method, and this system includes sensor integrated unit, data transmission unit and data processing unit, and the sensor integrated unit passes through data transmission unit and is connected with data processing unit electricity, and the sensor integrated unit includes the buoy, sets up volatile gas detection sensor at the buoy top and sets up the quality of water parameter sensor in the buoy bottom. The monitoring system of this scheme can long-time on-line monitoring, improves sampling monitoring efficiency, relies on the natural volatilization of VOC in groundwater and the soil under ambient temperature to carry out monitoring and early warning, does not improve the ambient temperature of groundwater and soil, and the VOC volatilizes inadequately, and the pollution condition in groundwater and the soil can not be fully reflected to the VOC concentration in the gas phase, can't distinguish the pollution medium main part under the data abnormal condition, and technology complicacy, fault-tolerant rate are low.

Therefore, there is a need for an on-line monitoring and early warning device that is low in cost, can simultaneously monitor and warn the pollution of soil and groundwater VOC in petrochemical fields, and can achieve high detection accuracy.

The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person of ordinary skill in the art.

Disclosure of Invention

The invention aims to provide a soil and groundwater VOC on-line monitoring device and method, which can overcome the technical defect of insufficient detection precision caused by insufficient volatilization of VOC in the on-site sampling process of petrochemical sites, and can simultaneously realize on-line monitoring and early warning of VOC pollution of soil and groundwater in the petrochemical sites.

To achieve the above object, according to a first aspect of the present invention, there is provided an on-line monitoring device for soil and groundwater VOC, comprising: the underground water VOC collecting unit heats underground water with a preset volume collected on site to boil, and the VOC in the underground water volatilizes and simultaneously the gas phase in the liquid enters the upper part of the liquid surface to blow off the VOC; the soil VOC acquisition unit heats soil around the soil VOC monitoring well with the air covering belt, and the VOC in the soil is absorbed into the gas phase through pyrolysis; and the VOC on-line monitoring unit is used for receiving the underground water VOC and the soil VOC transmitted through the high-temperature heat tracing sampling pipe and respectively detecting the concentration.

Further, in the above technical solution, the groundwater VOC collection unit may further include: the underground water sampler is in a columnar hollow structure in the middle part, and has conical upper and lower ends, and is used for collecting and heating underground water; and an elevator which descends or ascends the groundwater sampler to a predetermined height.

Further, in the above technical scheme, the underground water sampler may be provided with: the water level sensor is arranged on the inner wall of the underground water sampler and is used for monitoring the underground water sampling water level; the underground water heater is arranged in the middle of the underground water sampler and is positioned below the sampling water level; the one-way valve is arranged at the bottom of the underground water sampler and is used for enabling underground water to flow in one way in the sampling process.

Further, in the above technical scheme, the pipeline of the high temperature heat tracing sampling pipe for transmitting the groundwater VOC can be provided with: a first valve for controlling gas emissions within the groundwater sampler before sampling and after groundwater VOC monitoring; and the second valve is used for controlling the heated VOC gas to enter the VOC on-line monitoring unit in the groundwater VOC monitoring process.

Further, in the above technical scheme, the underground water sampler may further be provided with: and the third valve is used for evacuating and sampling the underground water after the underground water VOC is monitored.

Further, in the above technical scheme, the soil VOC collection unit may include: a soil heater for heating soil around the soil VOC monitoring well with the air-covering belt; the soil VOC sampling head is used for collecting gas-phase VOC thermally desorbed after the soil is heated and transmitting the gas-phase VOC to the VOC on-line monitoring unit through the high-temperature heat tracing sampling tube.

Further, in the above technical solution, the online monitoring device of the present invention may further include: the control unit is used for controlling the heating and sampling processes of the underground water VOC acquisition unit and the soil VOC acquisition unit and transmitting the heated gas-phase VOC to the VOC on-line monitoring unit.

Further, in the above technical solution, the on-line monitoring device may further include: and the remote terminal is used for receiving the VOC concentration monitoring data from the VOC on-line monitoring unit, comparing and analyzing the VOC concentration monitoring data with a background value and outputting an early warning signal of a preset level.

Furthermore, in the above technical scheme, the VOC on-line monitoring unit may employ a PID gas detector.

According to a second aspect of the invention, the invention provides an on-line monitoring method for VOC of soil and groundwater, comprising the following steps: A. heating underground water with a preset volume collected in a monitoring target area to boil, and blowing off VOC (volatile organic compounds) in the process that gas phase in the liquid enters the upper part of the liquid surface while VOC in the underground water volatilizes; B. heating soil around a gas-covered soil VOC monitoring well in a monitoring target area, wherein VOC in the soil is absorbed into a gas phase through pyrolysis; C. and (3) conveying the underground water VOC and the soil VOC through the high-temperature heat tracing sampling pipe and respectively detecting the concentrations.

Further, in the above technical solution, before step a, the method may further include: and determining a background area at the groundwater upstream of the monitored target area, and extracting a maximum value from continuous detection values of the groundwater VOC and the soil VOC in the background area as a background value.

Further, in the above technical solution, step C may further include: and comparing and analyzing the groundwater and soil VOC concentration monitoring data of the monitoring target area with corresponding background values, and outputting an early warning signal of a preset level.

Compared with the prior art, the invention has the following beneficial effects:

1) The invention can realize the synchronous online accurate monitoring and early warning of the pollution of the groundwater and the soil VOC by using the same set of monitoring units;

2) The underground water sampler can take out underground water without disturbance, keep the sampling volume of the underground water in the sampler fixed, and realize the environmental consistency of sampling in different time periods;

3) The underground water in the sampler is heated, volatilization of VOC can be quickened, meanwhile, the gas phase plays a role in stripping VOC in the process of entering the upper part of the liquid level from the inside of the liquid, and the underground water VOC in the gas phase is transmitted through the high-temperature heat tracing sampling tube, so that the monitoring unit is convenient for monitoring the concentration of the underground water VOC;

4) Soil heaters are arranged around the soil gas VOC on-line monitoring well, the VOC in the soil can be thermally desorbed and enter a gas phase in a high-temperature environment, and the soil VOC in the gas phase is transmitted through a high-temperature heat tracing sampling pipe, so that the monitoring unit can monitor the soil VOC concentration conveniently;

5) According to the remote terminal provided by the invention, alarm information comprising emergency treatment plans of different levels can be output according to different pollution data, so that efficient treatment at the first time can be ensured.

The foregoing description is only an overview of the present invention, and it is to be understood that it is intended to provide a more clear understanding of the technical means of the present invention and to enable the technical means to be carried out in accordance with the contents of the specification, while at the same time providing a more complete understanding of the above and other objects, features and advantages of the present invention, and one or more preferred embodiments thereof are set forth below, together with the detailed description given below, along with the accompanying drawings.

Drawings

FIG. 1 is a schematic diagram of the connection structure of the soil and groundwater VOC on-line monitoring device of the invention.

Fig. 2 is a schematic diagram of the internal structure of the groundwater sampler in the groundwater VOC acquisition unit of the invention.

FIG. 3 is a schematic cross-sectional view of the upper port of the groundwater sampler of the invention.

Fig. 4 is a schematic flow chart of the soil and groundwater VOC on-line monitoring method of the present invention.

The main reference numerals illustrate:

1-underground water monitoring well;

2-groundwater sampler; 21-a sampler housing; 22-a water level sensor; 23-groundwater heater; 24-a one-way valve; 25-a third valve; 26-an underground water sampling line; 27-water line;

3-bundling of sampler pipelines; 30-sampler upper port; a 31-VOC sampling tube; a 32-conduit;

4-ground; 5-soil VOC monitoring well; 6-soil VOC sampling head; 7-a soil heater; 8-a control line; 9-a high-temperature heat tracing sampling tube; 10-elevator support; 11-an elevator; a 12-VOC on-line monitoring unit; 13-a control unit; 14-a remote terminal; 15-a first valve; 16-a second valve.

Detailed Description

The following detailed description of embodiments of the invention is, therefore, to be taken in conjunction with the accompanying drawings, and it is to be understood that the scope of the invention is not limited to the specific embodiments.

Throughout the specification and claims, unless explicitly stated otherwise, the term "comprise" or variations thereof such as "comprises" or "comprising", etc. will be understood to include the stated element or component without excluding other elements or other components.

Spatially relative terms, such as "below," "beneath," "lower," "above," "upper," and the like, may be used herein for ease of description to describe one element's or feature's relationship to another element's or feature's in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the article in use or operation in addition to the orientation depicted in the figures. For example, if the article in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the elements or features. Thus, the exemplary term "below" may encompass both a direction of below and a direction of above. The article may have other orientations (rotated 90 degrees or other orientations) and the spatially relative descriptors used herein interpreted accordingly.

The terms "first," "second," and the like herein are used for distinguishing between two different elements or regions and are not intended to limit a particular position or relative relationship. In other words, in some embodiments, the terms "first," "second," etc. may also be interchanged with one another.

The invention provides a soil and groundwater VOC on-line monitoring device which comprises a groundwater VOC acquisition unit, a soil VOC acquisition unit, a VOC on-line monitoring unit 12, a control unit 13 and a remote terminal 14. The respective constituent parts are described in detail below.

Groundwater VOC acquisition unit:

the underground water VOC acquisition unit is used for heating underground water with a preset volume acquired on site to boiling, the volatilization of VOC in the underground water can be accelerated by heating, and meanwhile, the process that gas phase in the liquid enters the upper part of the liquid surface can play a role in stripping VOC.

Further, as shown in fig. 1, the groundwater VOC collection unit specifically includes a groundwater sampler 2 and a lifter 11. The groundwater sampler 2 is arranged in the groundwater monitoring well 1 below the ground 4, the diameter range of the groundwater monitoring well 1 is preferably 80-200mm, and the space required by lifting the sampler is needed to be considered. The middle part of the underground water sampler 2 is of a columnar hollow structure, the upper end and the lower end of the underground water sampler are conical, the underground water sampler is used for collecting and heating underground water, disturbance on the underground water can be reduced during sampling, and the diameter range of the sampler is preferably 75-150mm. The lifter 11 is fixed to the wellhead of the groundwater monitoring well 1 by the lifter bracket 10, and the groundwater sampler 2 can be lowered to a sampling point position of a predetermined depth or raised to a predetermined height near the wellhead by the lifter 11.

As further shown in fig. 2, a water level sensor 22, an underground water heater 23, and a check valve 24 are provided in a housing 21 of the underground water sampler 2. The water level sensor 22 is arranged on the inner wall of the groundwater sampler 2 and is used for monitoring the groundwater sampling water level, when sampled groundwater reaches the setting position of the water level sensor 22, the control unit 13 controls the one-way valve 24 to be closed, sampling is stopped, the volume of groundwater sampled each time can be ensured to be consistent, and the accuracy of measurement is facilitated. The groundwater heater 23 is disposed in the middle of the groundwater sampler 2 below the sampling water level, and the heating temperature range of the heater is preferably 50-260 ℃. When the underground water sampler 2 rises to the vicinity of the wellhead under the action of the lifter 11 after the sampling is completed, the underground water heater 23 starts to work and heats the sampled underground water to boiling, so that the VOC in the underground water is volatilized in an accelerating way, and the rising gas phase in the liquid can blow off the VOC. The underground water heater 23 is arranged in the underground water sampler 2, so that gas-phase VOC in the underground water can be obtained more effectively, and the monitoring accuracy is improved. The invention can also increase the groundwater aeration unit according to the requirement, and further increase the stripping effect. The one-way valve 24 is arranged at the bottom of the groundwater sampler 2 and is used for enabling groundwater to flow in one way in the sampling process, and the one-way valve 24 is in an open state in the sampling process. After heating to obtain the groundwater VOC in the gas phase, the groundwater VOC is sent to the VOC on-line monitoring unit 12 of the present invention through a transfer line.

As further shown in FIG. 1, the invention adopts the high-temperature heat tracing sampling pipe 9 as a transmission pipeline, so that the underground water VOC can be kept in a high-temperature gas phase state all the time, and the monitoring of the VOC on-line monitoring unit 12 is facilitated. A first valve 15 and a second valve 16 are arranged on a pipeline of the high-temperature heat tracing sampling pipe 9 for conveying the underground water VOC. Wherein the first valve 15 is used to control the gas discharge in the groundwater sampler before sampling and after groundwater VOC monitoring. The second valve 16 is used to control the heated VOC gas to enter the VOC on-line monitoring unit during groundwater VOC monitoring. As further shown in fig. 2, a third valve 25 is provided in the groundwater sampler 2, and the third valve 25 is used for evacuating and sampling groundwater after monitoring groundwater VOC, and preparing for the next sampling.

As further shown in fig. 1, the groundwater sampler 2 is connected with the VOC on-line monitoring unit 12 and the control unit 13 through the sampler tube bundle 3. Specifically, the piping bundle 3 has therein a VOC sampling tube 31 leading to the VOC on-line monitoring unit 12, the VOC sampling tube 31 communicating with the housing 21 of the groundwater sampler 2. The sampler tube bundle 3 also has a conduit 32 connected to the control unit 13 for controlling the operation of the groundwater heater 23. As further shown in fig. 2 and 3, the cross section of the upper port 30 of the sampler shows the arrangement of the VOC sampling tube 31 and the conduit 32.

Soil VOC acquisition unit:

as shown in fig. 1, a soil VOC monitoring well 5 with a gas-covered zone is built around a groundwater monitoring well 1, the soil VOC monitoring well is arranged at the upper part of a saturated zone, and the top of the monitoring well is subjected to barrier treatment. The soil VOC acquisition unit is used for heating soil around the gas-coated soil VOC monitoring well, and the VOC in the soil can be inhaled into the gas phase through pyrolysis. Specifically, the soil VOC acquisition unit includes a soil heater 7 and a soil VOC sampling head 6. The soil heater 7 is located around the periphery of the soil VOC monitoring well 5 to heat the surrounding soil, and four heaters are preferably used. The control unit 13 can control the soil heater 7 to work through a control circuit, and the heated soil can obtain the VOC in the gas phase through the thermal desorption. The soil VOC sampling head 6 is used for collecting the gas phase VOC which is thermally desorbed after the soil is heated and transmitting the gas phase VOC to the VOC on-line monitoring unit 12 through the high temperature heat tracing sampling pipe 9.

VOC on-line monitoring unit:

the VOC on-line monitoring unit 12 is configured to receive the groundwater VOC and the soil VOC transmitted through the high temperature heat tracing sampling tube 9 and perform concentration detection on the groundwater VOC and the soil VOC, respectively. Preferably, and without limitation, the VOC on-line monitoring unit 12 detects the gas using a PID detector, measuring in the range of 0-50ppm.

Control unit and remote terminal:

as shown in fig. 1, the control unit 13 of the present invention is used for controlling the heating and sampling processes of the underground water VOC collection unit and the soil VOC collection unit, and controlling the heated gas phase VOC to be transmitted to the VOC on-line monitoring unit. The remote terminal 14 of the present invention is configured to receive the VOC concentration monitoring data from the VOC on-line monitoring unit 12, perform a comparison analysis with a background value, and output an early warning signal of a preset level. Specifically, the invention determines a background area at a monitoring site (i.e., a monitoring target area) that is disposed upstream of an uncontaminated region of the groundwater flow. And arranging a plurality of groups of underground water monitoring wells and soil monitoring wells in the background area, constructing an on-line monitoring system for soil and underground water VOC, continuously running, and taking the maximum value in continuous running data as the background value of the monitoring field. And (3) performing contrast analysis by taking the background value as a reference, and outputting multi-stage early warning according to a contrast analysis result.

The invention also provides an on-line monitoring method for the VOC of the soil and the groundwater, which can comprise the following steps:

and step S101, determining a background area on the upstream of groundwater in the monitored target area, and extracting a maximum value from continuous detection values of the groundwater VOC and the soil VOC in the background area as a background value.

Step S102, heating the underground water with the preset volume collected in the field of the monitoring target area to boil, and blowing off the VOC in the process that the gas phase in the liquid enters the upper part of the liquid surface while the VOC in the underground water volatilizes.

Specifically, during monitoring of the VOC in the groundwater, the control unit 13 controls the groundwater sampler 2 to descend, the first valve 15 is opened, the second valve 16 is closed, the groundwater enters the groundwater sampler 2 through the one-way valve 24, the gas discharged from the sampler is discharged through the first valve 15, the water level in the sampler reaches the water level line 27 at the preset position, and the water level sensor 22 transmits signals to the control unit 13, so that the accuracy of the groundwater sampling depth can be ensured. The control unit 13 sends a command to the elevator 11, the groundwater sampler 2 stops and starts to rise, at which time the one-way valve 24 is automatically closed and the groundwater sampler 2 rises. After the underground water sampler 2 rises to the initial position, the second valve 16 is opened, the first valve 15 is closed, the underground water heater 23 inside the sampler starts to work, the water sample in the sampler is heated to boiling, volatilization of VOC is quickened, and meanwhile, the gas phase plays a role in blowing off the VOC from the process that the liquid enters the upper part of the liquid level.

And step S103, heating the soil around the covered gas zone soil VOC monitoring well in the monitored target area, and sucking the VOC in the soil into the gas phase through pyrolysis.

Specifically, a gas-covered soil VOC monitoring well 5 is built around the underground water monitoring well 1, a soil heater 7 is arranged around the soil VOC monitoring well, a control unit 13 controls the soil heater 7 to work through a control circuit, and the VOC in the soil is thermally desorbed and enters a gas phase in a high-temperature environment.

And step S104, conveying the underground water VOC and the soil VOC through the high-temperature heat tracing sampling pipe and respectively detecting the concentrations.

Specifically, the gas-phase underground water VOC enters the VOC on-line monitoring unit 12 through the high-temperature heat tracing sampling tube 9 and the second valve 16, and the monitoring data is sent to the remote terminal 14; the gas-phase soil VOC enters the VOC on-line monitoring unit 12 through the soil VOC sampling head 6 by the high-temperature heat tracing sampling pipe 9, and the monitoring data is sent to the remote terminal 14.

Step S105, comparing and analyzing the underground water and soil VOC concentration monitoring data of the monitoring target area with corresponding background values, and outputting a pre-set level early warning signal.

Specifically, the remote terminal 14 may separate the abnormal data by comparing the database, further determine the pollution data by processing the abnormal data, and directly output the alarm information once the pollution data is determined, and output different levels of alarm information according to different pollution data, where the different levels of alarm information include different emergency treatment plans, so as to ensure that the first time makes efficient treatment.

For example, if the concentration value monitored by the monitoring site is 2 times of the background value, a III-level early warning can be output, and a III-level emergency plan is corresponding, namely, if sudden pollution is detected from a monitoring site inspection person to a monitoring point, the attention to the area is kept and the online monitoring frequency is increased; if the concentration value monitored by the monitoring field is 4 times of the background value, a II-level early warning can be output, namely, whether sudden pollution occurs to the monitoring point position check or not, underground water and soil samples are collected and sent to a laboratory for detection, the on-line monitoring frequency is increased, the pollution condition is judged according to the detection condition, pollution check is carried out on the field by environment-friendly supervisor organization personnel in the monitoring area, and a check report is written; if the concentration value monitored by the monitoring site is more than 6 times of the background value, I-level early warning can be output, monitoring site inspection personnel can check whether sudden pollution occurs to the monitoring point position, underground water and soil samples are collected and sent to a laboratory for detection, on-line monitoring frequency is increased, pollution conditions are judged according to detection conditions, a site investigation scheme is formulated, site pollution condition investigation is carried out, and site investigation reports are written.

By adopting the soil and groundwater VOC on-line monitoring device and the method, the groundwater sampler can take out groundwater without disturbance, the sampling volume of groundwater in the sampler is kept fixed, and the environmental consistency of sampling in different time periods can be realized; the underground water in the sampler is heated, so that volatilization of VOC can be quickened, and simultaneously, the gas phase enters the upper part of the liquid level from the inside of the liquid to play a role in stripping VOC; applying a thermal desorption technology to online monitoring, arranging heaters around the soil gas VOC online monitoring well, and thermally desorbing the VOC in the soil under a high-temperature environment and entering a gas phase; the remote terminal can output alarm information comprising emergency treatment plans at different levels according to different pollution data, and can ensure that high-efficiency treatment is performed at the first time.

Example 1

Determining a background area in an upstream uncontaminated area of underground water of a petrochemical field, arranging three groups of underground water monitoring wells and soil monitoring wells in the background area, constructing an on-line monitoring device for soil and underground water VOC, continuously running for 30 days, taking the maximum value in continuous running data as the background value of the monitoring field, wherein the background value of the underground water is 1.5ppm, and the background value of the soil is 2ppm.

The soil and groundwater VOC on-line monitoring device is built on a monitoring site, the background value of the groundwater VOC is 1.5ppm, the background value of the soil VOC is 1ppm, the monitoring frequency is once in 10 days, and continuous on-line operation monitoring is carried out. The control unit controls the groundwater sampler to descend, the first valve is opened, the second valve is closed, groundwater enters the groundwater sampler through the one-way valve, exhaust gas in the sampler is discharged through the first valve, water level in the sampler reaches a water level line, the water level sensor transmits signals to the control unit, the control unit sends instructions to the lifter, the groundwater sampler stops and starts to ascend, the one-way valve is automatically closed, after the groundwater sampler ascends to an initial position, the second valve is opened, the first valve is closed, a heater inside the groundwater sampler starts to work, the working temperature is set to 200 ℃, water samples in the sampler boil after a period of time, VOC fully volatilizes, and simultaneously VOC in the process that gas phase enters the upper part of a liquid level from the inside of the liquid is blown off. The gas enters the VOC on-line monitoring unit through the high-temperature heat tracing sampling tube and the second valve, and the monitoring data is sent to the remote terminal.

Building a gas-covered soil VOC monitoring well around the underground water monitoring well, arranging a heater around the soil VOC monitoring well, sending an instruction by a control unit, starting the heater to work, setting the working temperature to 200 ℃, thermally desorbing and entering a gas phase in the soil under a high-temperature environment, and enabling the gas to enter a VOC on-line monitoring unit through a high-temperature heat tracing sampling tube.

After the monitoring of the VOC in the underground water is finished, the control unit sends an instruction, the heater in the underground water sampler stops working, the first valve is opened, the second valve is closed, the third valve of the underground water sampler is opened, and the third valve is automatically closed after the water sample in the sampler is emptied. After the soil VOC monitoring is finished, the control unit sends an instruction, and the heater around the soil monitoring well stops working.

The remote terminal separates abnormal data through the comparison of the monitoring data and the background value, when the VOC of the underground water in the monitoring data exceeds 3ppm or the VOC of the soil exceeds 4ppm, the remote terminal outputs III-level early warning, the monitoring site inspection personnel find out burst pollution when the monitoring site inspection is finished, the attention of the area is kept in the later period, and the online monitoring frequency is adjusted to be 7 days once; when the VOC of the ground water in the monitoring data exceeds 6ppm or the VOC of the soil exceeds 8ppm, the remote terminal outputs a level II early warning, the monitoring site inspection personnel does not leak to the monitoring point location inspection, the ground water and the soil sample are collected and sent to a laboratory for detection, the on-line monitoring frequency is adjusted to be 7 days once, the ground water and the soil sample laboratory detection data show that the site characteristic VOC pollutants are detected, but the quality standard of the ground water is not exceeded, and the pollution inspection is carried out on the site by the environment-friendly main pipe organization personnel in the monitoring area.

The foregoing descriptions of specific exemplary embodiments of the present invention are presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application to thereby enable one skilled in the art to make and utilize the invention in various exemplary embodiments and with various modifications as are suited to the particular use contemplated. Any simple modifications, equivalent variations and modifications of the above-described exemplary embodiments should fall within the scope of the present invention.

Claims (12)

1. Soil and groundwater VOC on-line monitoring device, its characterized in that includes:

the underground water VOC collecting unit heats underground water with a preset volume collected on site to boil, and the VOC in the underground water volatilizes and simultaneously the gas phase in the liquid enters the upper part of the liquid surface to blow off the VOC;

the soil VOC acquisition unit heats soil around the soil VOC monitoring well with the air covering belt, and the VOC in the soil is absorbed into the gas phase through pyrolysis;

and the VOC on-line monitoring unit is used for receiving the underground water VOC and the soil VOC which are transmitted through the high-temperature heat tracing sampling pipe and respectively detecting the concentration.

2. The soil and groundwater VOC on-line monitoring device of claim 1, wherein the groundwater VOC collection unit comprises:

the underground water sampler is in a columnar hollow structure in the middle part, and has conical upper and lower ends, and is used for collecting and heating underground water;

and an elevator which descends or ascends the groundwater sampler to a predetermined height.

3. The soil and groundwater VOC on-line monitoring device according to claim 2, wherein the groundwater sampler is provided with:

the water level sensor is arranged on the inner wall of the underground water sampler and is used for monitoring the underground water sampling water level;

the underground water heater is arranged in the middle of the underground water sampler and is positioned below the sampling water level;

and the one-way valve is arranged at the bottom of the underground water sampler and is used for enabling underground water to flow in one way in the sampling process.

4. The on-line monitoring device for soil and groundwater VOCs according to claim 3, wherein the pipeline of the Gao Wenban thermal sampling tube for transporting groundwater VOCs is provided with:

a first valve for controlling gas emissions within the groundwater sampler before sampling and after groundwater VOC monitoring;

and the second valve is used for controlling the heated VOC gas to enter the VOC on-line monitoring unit in the groundwater VOC monitoring process.

5. The soil and groundwater VOC on-line monitoring device according to claim 3, wherein the groundwater sampler is further provided with:

and the third valve is used for evacuating and sampling the underground water after the underground water VOC is monitored.

6. The soil and groundwater VOC on-line monitoring device of claim 1, wherein the soil VOC collection unit comprises:

a soil heater for heating the soil around the air-covered soil VOC monitoring well;

the soil VOC sampling head is used for collecting gas-phase VOC thermally desorbed after the soil is heated and transmitting the gas-phase VOC to the VOC on-line monitoring unit through the Gao Wenban thermal sampling tube.

7. The on-line monitoring device of soil and groundwater VOC according to claim 1, further comprising:

the control unit is used for controlling the heating and sampling processes of the underground water VOC acquisition unit and the soil VOC acquisition unit and transmitting the heated gas-phase VOC to the VOC on-line monitoring unit.

8. The on-line monitoring device of soil and groundwater VOC according to claim 1, further comprising:

and the remote terminal is used for receiving the VOC concentration monitoring data from the VOC on-line monitoring unit, comparing and analyzing the VOC concentration monitoring data with a background value and outputting an early warning signal of a preset level.

9. The on-line monitoring device for soil and groundwater VOCs according to claim 1, wherein said on-line monitoring unit for VOCs is a PID gas detector.

10. The on-line monitoring method for the VOC of the soil and the underground water is characterized by comprising the following steps:

A. heating underground water with a preset volume collected in a monitoring target area to boil, and blowing off VOC (volatile organic compounds) in the process that gas phase in the liquid enters the upper part of the liquid surface while VOC in the underground water volatilizes;

B. heating soil around a gas-covered soil VOC monitoring well in the monitoring target area, wherein VOC in the soil is absorbed into a gas phase through pyrolysis;

C. and (3) conveying the underground water VOC and the soil VOC through the high-temperature heat tracing sampling pipe and respectively detecting the concentrations.

11. The method for on-line monitoring of soil and groundwater VOCs according to claim 10, further comprising, prior to said step a:

and determining a background area at the underground water upstream of the monitoring target area, and extracting a maximum value from the continuous detection values of the underground water VOC and the soil VOC in the background area as a background value.

12. The method for on-line monitoring of soil and groundwater VOCs according to claim 11, further comprising, after said step C:

and comparing and analyzing the groundwater and soil VOC concentration monitoring data of the monitoring target area with corresponding background values, and outputting an early warning signal of a preset level.

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