Soil gas-based pollution leak detection method, system, electronic device, and storage medium

Abstract

The application discloses a kind of based on soil gas pollution leak detection method and system, which comprises the following steps: A, the air pipe and the air extraction pipeline of evenly spaced setting porous pipe are laid in the air-permeable sand layer of corresponding position of storage and transport equipment, and the basic parameter data of air pipe, porous pipe and air extraction pump are obtained;B, according to the basic parameter data, the air flow rate of leakage gas in the air pipe and the porous pipe in each unit pipe section is calculated one by one through air flow distribution model;C, according to the air flow rate of leakage gas in the air pipe and the porous pipe, the transmission time of leakage gas in each unit pipe section is calculated respectively;D, the transmission time of leakage gas in each unit pipe section is accumulated, and the position of leakage point is judged by total transmission time.The method and system of the application not only can quickly detect whether leakage occurs, but also can quickly locate the leakage point;It has the characteristics of accurate and efficient, economical and convenient.

Description

Technical Field

[0001] This invention relates to the field of petrochemical pollution leakage monitoring technology, and in particular to a method, system, electronic device and storage medium for detecting pollution leakage at petrochemical sites based on soil gas detection. Background Technology

[0002] Leaks of petroleum and other organic solvents can cause varying degrees of soil and groundwater pollution, seriously impacting ecological security and human health. Due to the widespread and complex network of underground pipelines and structures in petrochemical sites, leaks are difficult to detect and locate. Traditional leak detection technologies for petrochemical storage and transportation equipment often rely on changes in pipeline acoustic signals, medium temperature, and pressure to determine if a leak has occurred. These passive detection methods suffer from low sensitivity, complex data analysis, high equipment costs, and difficulty in pinpointing the leak location.

[0003] Existing technologies include several methods for leak detection. For example, CN111982415A discloses a pipeline leak detection method and device. This method monitors and photographs the equipment using a camera and analyzes image color changes to determine if a leak has occurred. However, this method requires spraying industrial pigments onto the monitored equipment, complex image processing, and suffers from low sensitivity and blind spots, thus failing to accurately and comprehensively detect leaks. CN112857699A discloses a method for leak detection and location in long-distance oil and gas pipelines using acoustic vector sensors. This method deploys acoustic vector sensors in a three-dimensional spatial distribution, establishes a database of leak sounds in long-distance oil and gas pipelines through data acquisition, then uses an array of acoustic vector sensors to sense the leak sounds, and uses the autocorrelation matrix eigenvalue decomposition of the entire array's received data matrix to analyze the database and determine the leak location. This method requires a complex sensor array, has high technical requirements, is economically inefficient, and cannot detect minute, silent leaks.

[0004] Studies have found that aromatic and aliphatic compounds in gasoline readily volatilize when exposed to the environment, transforming into gaseous volatile organic compounds (VOCs) that enter the ambient atmosphere. Therefore, chemical analysis of soil gas can be used to detect fuel leaks in underground storage tanks and pipelines. Soil gas-based leak detection technology involves analyzing the air within the pores of soil particles in the vadose zone to determine the presence of VOCs, thereby identifying potential leaks of organic solvents such as petroleum.

[0005] Therefore, there is an urgent need for a soil gas-based pollution leak detection device and specific detection methods that can not only quickly detect whether there is a leak in the storage and transportation equipment of petrochemical sites, but also quickly locate the leak point.

[0006] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0007] The purpose of this invention is to provide a soil gas-based method and system for detecting pollution leaks, which can be applied to leak detection in petrochemical site storage and transportation equipment. It can not only quickly detect whether a leak has occurred, but also quickly locate the leak point; it is accurate, efficient, economical and convenient.

[0008] To achieve the above objectives, according to a first aspect of the present invention, the present invention provides a method for detecting pollution leaks based on soil gas, comprising the following steps: A. Laying out an extraction pipeline with uniformly spaced gas guide pipes and porous pipes in a permeable sand layer at corresponding locations of the storage and transportation equipment, and obtaining basic parameter data of the gas guide pipes, porous pipes, and extraction pumps; B. Calculating the airflow rate of the leaking gas in the gas guide pipes and porous pipes in each unit pipe segment using an airflow distribution model based on the basic parameter data; C. Calculating the transmission time of the leaking gas in each unit pipe segment based on the airflow rate of the leaking gas in the gas guide pipes and porous pipes; D. Accumulating the transmission time of the leaking gas in each unit pipe segment, and determining the location of the leak point based on the total transmission time.

[0009] Furthermore, in the above technical solution, the basic parameter data in step A may include: the air pump flow rate and the inlet pressure of the air pump; the inner diameter and the length of the air guide pipe; the inner and outer diameters, the length, and the permeability coefficient of the porous pipe; as well as the background atmospheric pressure and the dynamic viscosity of soil gas at 20°C.

[0010] Furthermore, in the above technical solution, the step-by-step calculation in step B is performed sequentially from the first unit pipe segment closest to the air pump towards the far end of the pipe; the airflow distribution model includes the following formulas (1) to (4):

[0011]

[0012] Among them, Q dq P is the airflow rate in the air delivery tube, in L / min; in P represents the absolute pressure at the inlet of the air delivery tube, in Pa; out P is the absolute pressure at the outlet of the air delivery tube, in Pa; bFor reference atmospheric pressure, Pa; μ is the dynamic viscosity of soil gas at 20℃, Pa·s; R is the inner diameter of the gas delivery pipe, m; L is the length of the gas delivery pipe, m; for the first unit pipe section, Q dq P is the pumping flow rate of the air pump. out The absolute pressure P at the inlet of the air pump is calculated using formula (1) to determine the inlet pressure of the air guide pipe in the first unit section. in ;

[0013]

[0014] Among them, Q por ρ is the airflow velocity in the porous tube, L / min; K is the permeability coefficient of the porous tube, m / d; h is the length of the porous tube, m; P0 is the background atmospheric pressure, Pa; P w The absolute pressure inside the porous tube is Pa. In each unit tube section, the airflow enters the guide tube through the porous tube, and the absolute pressure P at the inlet of the guide tube is... in Equal to the internal absolute pressure P of the porous tube w ;P b For reference atmospheric pressure, Pa;r e The outer diameter of the porous tube is in meters (m); r w The inner diameter of the porous tube is in meters (m).

[0015] Q dq，i+1 =Q dq，i -Q por，i Formula (3);

[0016] Among them, Q dq，i+1 Q is the airflow rate in the (i+1)th segment of the air duct, in L / min; dq，i Q is the airflow rate in the i-th segment of the air duct, in L / min; por，i Let L be the airflow velocity in the i-th segment of the porous tube, in L / min.

[0017]

[0018] Among them, P out，i+1 P is the absolute pressure at the outlet of the (i+1)th segment of the air duct, in Pa; w，i Let be the internal absolute pressure of the i-th segment of the porous tube, in Pa.

[0019] Furthermore, in the above technical solution, the calculation of the transmission time of the leaked gas in each unit pipe segment in step C is specifically carried out in the following manner:

[0020] When a leak occurs below the Kth section of the gas duct, the volatilized leaked gas enters the permeable sand layer and then enters the extraction pipeline through the Kth section of the porous pipe. Then:

[0021]

[0022] Among them, Q dq，k The airflow rate in the k-th segment of the air duct is expressed in L / min.

[0023]

[0024] Among them, t k Let A be the transit time of the leaked gas in the k-th segment of the gas duct, in minutes; k L is the cross-sectional area of ​​the air passage in the k-th segment of the air duct; k Let be the length of the k-th segment of the air duct.

[0025] Furthermore, in the above technical solution, the total transmission time in step D is the detection time T of the leaked gas, specifically:

[0026]

[0027] Furthermore, in the above technical solution, the permeable sand layer may include a fine sand layer, a medium sand layer, and a coarse sand layer laid sequentially from bottom to top; the air extraction pipeline is laid horizontally within the coarse sand layer.

[0028] Furthermore, in the above technical solution, the length ratio of the air guide tube to the porous tube can be 10 to 25:1.

[0029] Furthermore, in the above technical solution, the inner diameter R of the air duct and the rated flow rate Q of the air pump can satisfy R... 2 / Q<1.6*10 -6 .

[0030] Furthermore, in the above technical solution, the storage and transportation equipment can be an oil pipeline or an oil storage tank, and the leaked gas is VOCs volatilized from the leaked material of the storage and transportation equipment; the vacuum pump is connected to a gas detector.

[0031] According to a second aspect of the present invention, the present invention provides a soil gas-based pollution leak detection system, comprising: a basic data acquisition module for acquiring basic parameter data of a gas guide pipe, a porous pipe, and a pump; a gas flow rate calculation module for calculating the gas flow rate of the leaking gas in the gas guide pipe and the porous pipe in each unit pipe segment based on the basic parameter data and a gas flow distribution model; a transmission time calculation module for calculating the transmission time of the leaking gas in each unit pipe segment according to the gas flow rate of the leaking gas in the gas guide pipe and the porous pipe; and a leak location determination module for accumulating the transmission time of the leaking gas in each unit pipe segment and determining the location of the leak point by the total transmission time.

[0032] According to a third aspect of the present invention, an electronic device is provided, comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to cause the at least one processor to perform a soil gas-based pollution leak detection method as described in any of the above-described technical solutions.

[0033] According to a fourth aspect of the present invention, the present invention provides a non-transitory computer-readable storage medium storing computer-executable instructions for causing a computer to perform a soil gas-based pollution leak detection method as described in any of the above technical solutions.

[0034] Compared with the prior art, the present invention has one or more of the following beneficial effects:

[0035] 1) Using the device of the present invention, VOCs gas formed by leakage of oil pipeline or oil storage tank and volatilization in soil can be introduced into the gas extraction pipeline, and the content of VOCs gas can be monitored by a gas detector to determine whether the storage and transportation equipment of the petrochemical site has leaked.

[0036] 2) The method of the present invention can minimize the sampling volume and monitoring cost. At the same time, a mathematical model of airflow distribution is constructed based on the physical detection device of the present invention, which can accurately and quickly predict the leak location based on the detection results. This not only greatly reduces the complexity of on-site work, but also achieves low-cost and high-precision leak location prediction.

[0037] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it according to the contents of the specification, and to make the above and other objects, technical features and advantages of the present invention easier to understand, one or more preferred embodiments are listed below and described in detail with reference to the accompanying drawings. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the structure of the soil gas-based pollution leak detection device of Embodiment 1 of the present invention (applicable to oil pipelines).

[0039] Figure 2 This is a schematic diagram of the structure of the soil gas-based pollution leak detection device of Embodiment 1 of the present invention (applicable to oil storage tanks).

[0040] Figure 3 This is a schematic flowchart of the soil gas-based pollution leak detection method of Embodiment 2 of the present invention.

[0041] Figure 4This is the curve showing the change of VOCs concentration over time obtained by applying the method of Example 2 to the leak detection process of an oil storage tank.

[0042] Figure 5 This is a schematic diagram of the structure of the soil gas-based pollution leak detection system in Embodiment 3 of the present invention.

[0043] Figure 6 This is a schematic diagram of the hardware structure of the soil gas pollution leak detection electronic device according to Embodiment 6 of the present invention.

[0044] Explanation of key figure labels:

[0045] 1-Permeable sand layer, 1-1-Fine sand layer, 1-2-Medium sand layer, 1-3-Coarse sand layer; 2-Extraction pipeline, 2-1-Gas guide pipe, 2-2-Porous pipe; 3-Extraction pump, 4-Photoionization detector. Detailed Implementation

[0046] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0047] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0048] In this document, for ease of description, spatial relative terms such as “below,” “under,” “down,” “above,” “above,” “up,” etc., are used to describe the relationship of one element or feature to another element or feature in the accompanying drawings. It should be understood that spatial relative terms are intended to encompass different orientations of an object in use or operation, in addition to those depicted in the figures. For example, if an object in the figure is flipped, an element described as “below” or “under” another element or feature would be oriented “above” that element or feature. Thus, the exemplary term “below” can encompass both the downward and upward orientations. An object may also have other orientations (rotated 90 degrees or other orientations), and the spatial relative terms used herein should be interpreted accordingly.

[0049] In this document, the terms "first," "second," etc., are used to distinguish two different elements or parts, and are not used to define specific positions or relative relationships. In other words, in some embodiments, the terms "first," "second," etc., can also be used interchangeably.

[0050] The methods, systems, electronic devices, and storage media of the present invention are described in more detail below by way of specific embodiments. It should be understood that the embodiments are merely exemplary and the present invention is not limited thereto.

[0051] Example 1

[0052] This embodiment is a physical device embodiment, providing a soil gas-based pollution leak detection device. For example... Figure 1 , 2 As shown, the device includes a permeable sand layer 1, an extraction pipeline 2, an extraction pump 3, and a gas detector 4. The permeable sand layer 1 is laid at the corresponding locations of the storage and transportation equipment in the petrochemical site; specifically, it can be laid as follows: Figure 1 As shown, it can be laid above the oil pipeline, or as... Figure 2 As shown, the permeable sand layer 1 is laid along the circumference of the oil storage tank. Preferably, but not limitingly, the width of the permeable sand layer 1 can be 1–2.5 m, and it may include a fine sand layer, a medium sand layer, and a coarse sand layer arranged sequentially from bottom to top, with each layer having a thickness of 0.3–0.6 m. The fine sand layer 1-1 is selected from sand with a permeability coefficient between 1.5 and 4.5 m / d, preferably 2.5–3.5 m / d, and an average particle size of 0.05–0.15 mm, preferably 0.075–0.1 mm. This selection of permeability coefficient and particle size can effectively adsorb pollutants and prevent leaked liquid fuel or compounds from entering the upper layer. The medium sand layer 1-2 is selected from sand with a permeability coefficient between 4.5 and 8 m / d, preferably 5–6.5 m / d, and an average particle size of 0.2–0.5 mm, preferably 0.35–0.45 mm. This can increase the porosity of the soil layer and accelerate the volatilization of leaked fuel or compounds. The coarse sand layer 1-3 is selected with a permeability coefficient between 15 and 25 m / d, preferably 18.5 to 21.5 m / d, and an average particle size of 1.0 to 2.5 mm, preferably 1.5 to 2.0 mm. The coarse sand layer 1-3 can accelerate the gas entering the extraction pipe 2, and can also filter out impurities entering the extraction pipe 2. The extraction pipe 2 is laid in the coarse sand layer 1-3.

[0053] Further as Figure 1 , 2As shown, the extraction pipeline 2 comprises multiple unit sections, each unit section having an interconnected gas guide pipe 2-1 and a porous pipe 2-2. The extraction pipeline 2 is horizontally positioned within the coarse sand layer 1-3 of the permeable sand layer 1. Specifically, the extraction pipeline 2 is divided into units of a certain length, each unit containing a section of gas guide pipe 2-1 and a section of porous pipe 2-2, which are connected by a threaded seal. The preferred length ratio of the gas guide pipe 2-1 to the porous pipe 2-2 is (10-25):1. The gas guide pipe 2-1 serves as a gas delivery pipeline, a non-absorbent sealed gas pipeline with smooth inner and outer walls, made of polymer materials or cast iron pipe, preferably polytetrafluoroethylene (PTFE) pipe. The porous pipe 2-2 serves as an external gas inlet, a non-absorbent open pipeline with porous walls. The inner diameter of the air guide tube 2-1 is between 1 and 50 mm, preferably 3 to 10 mm, and the ratio of the outer diameter to the inner diameter is less than 2.7. The opening area of ​​the porous tube 2-2 is 15% to 40% of the wall surface, and the opening diameter is between 1.5 and 2.0 mm.

[0054] Further as Figure 1 , 2 As shown, the vacuum pump 3 is connected to one end of the vacuum pipeline 2, and is used to supply air to storage and transportation equipment (e.g., Figure 1 Oil pipelines or Figure 2 The pump powers the extraction of VOCs gas that leaks from the oil storage tank and volatilizes into the extraction pipeline. Preferably, but not limitingly, the extraction pump is an explosion-proof pump, and the inner diameter R of the duct and the rated flow rate Q of the pump satisfy R... 2 / Q<1.6*10 -6 .

[0055] Further as Figure 1 , 2 As shown, the gas detector 4 is connected to the vacuum pump 3 and is used to monitor VOCs gas (i.e., leaked gas) formed by the volatilization of leaked gas from oil pipelines or gas storage tanks. The gas detector 4 can realize the quantitative detection of VOCs content in the gas, and preferably uses photoionization detectors (PID).

[0056] Using the apparatus of this embodiment, VOCs gas generated from leaks in oil pipelines or storage tanks and volatilization in the soil can be introduced into an extraction pipeline, and the VOCs gas content can be monitored by a gas detector to determine whether a leak has occurred in the storage and transportation equipment of a petrochemical site. Furthermore, based on the apparatus of this embodiment, the method of Embodiment 2 of the present invention can further accurately and quickly predict the location of leaks.

[0057] Example 2

[0058] Combination Figure 3As shown, this embodiment provides a method for detecting pollution leaks based on soil gas. This method is implemented using the physical device described in Embodiment 1 and includes the following steps:

[0059] Step S101: A suction pipeline, consisting of evenly spaced air guide pipes and porous pipes, is laid out in the permeable sand layer at the corresponding location of the storage and transportation equipment. Basic parameter data of the air guide pipes, porous pipes, and suction pump are then obtained. Specifically, the layout of the suction pipeline can be found in Example 1. Figure 1 and Figure 2 The basic parameters required in this step include, but are not limited to: the pumping flow rate and inlet pressure of the pump; the inner diameter and length of the gas delivery pipe; the inner and outer diameters, length, and permeability coefficient of the porous pipe. In addition to the above-mentioned basic equipment parameters, background atmospheric pressure and the dynamic viscosity of soil gas at 20°C are also required. Using these known parameters and the following mathematical model of airflow distribution obtained by the inventors, the transmission time of the leaking gas in the pumping pipeline can be calculated, thereby determining the specific location of the leak.

[0060] Step S102: Based on the basic parameter data in step S101, calculate the gas flow rate of the leaked gas in the gas guide pipe and the porous pipe in each unit pipe segment using the airflow distribution model. The gas flow in the extraction pipeline can be divided into two parts: the gas flow in the gas guide pipe and the gas flow in the porous pipe. The gas flow in the gas guide pipe conforms to the law of laminar flow of fluid in a horizontal circular pipe. According to the inventor's research, formula (1) can be used to simulate the gas flow law in the gas guide pipe. The gas flow in the porous pipe conforms to the basic law of fluid movement in a porous medium. According to the inventor's research, formula (2) can be used to simulate the gas flow law in the porous pipe. The model calculation starts from the first segment near the extraction pump and then proceeds segment by segment towards the far end of the pipeline. The airflow distribution model specifically includes the following formulas (1) to (4):

[0061]

[0062] Among them, Q dq P is the airflow rate in the air delivery tube, in L / min; in P represents the absolute pressure at the inlet of the air delivery tube, in Pa; out P is the absolute pressure at the outlet of the air delivery tube, in Pa; b For reference atmospheric pressure (value is 101.325 x 10⁻⁶), 3 ), Pa; μ is the dynamic viscosity of soil gas at 20℃, Pa·s; R is the inner diameter of the gas delivery pipe, m; L is the length of the gas delivery pipe, m; for the first unit pipe section, Q dq P is the pumping flow rate of the air pump. outThe absolute pressure P at the inlet of the first unit pipe section is calculated using formula (1), which is the inlet pressure of the air pump. in .

[0063]

[0064] Among them, Q por ρ is the airflow velocity in the porous tube, L / min; K is the permeability coefficient of the porous tube, m / d; h is the length of the porous tube, m; P0 is the background atmospheric pressure (value is the same as P). b The same, also 101.325x10 3 ), Pa; P w The absolute pressure inside the porous tube is Pa. In each unit tube section, the airflow enters the guide tube through the porous tube, and the absolute pressure P at the inlet of the guide tube is... in Equal to the internal absolute pressure P of the porous tube w ;P b For reference atmospheric pressure, Pa;r e The outer diameter of the porous tube is in meters (m); r w denoted as the inner diameter of the porous tube, in meters (m).

[0065] Q dq，i+1 =Q dq，i -Q por，i Formula (3);

[0066] Among them, Q dq，i+1 Q is the airflow rate in the (i+1)th segment of the air duct, in L / min; dq，i Q is the airflow rate in the i-th segment of the air duct, in L / min; por，i Let be the airflow rate in the i-th segment of the porous tube, in L / min.

[0067]

[0068] Among them, P out，i+1 P is the absolute pressure at the outlet of the (i+1)th segment of the air duct, in Pa; w，i Let be the internal absolute pressure of the i-th segment of the porous tube, in Pa.

[0069] This step uses formulas (1) to (4) above to calculate the airflow rate in the gas guide pipe and the perforated pipe of each unit pipe section. Specifically, for the first unit pipe section connected to the suction pump, Q dq，1 P is the pumping flow rate of the air pump. out，1 The inlet pressure of the air pump is given by the formula (1), which contains initial measurable parameters. μ and L are also known. Therefore, the inlet pressure of the air guide pipe in the first unit section can be calculated by using the formula (1). in，1 In each unit pipe section, the airflow enters the guide pipe through the porous pipe, and the absolute pressure P at the inlet of the guide pipe... inEqual to the internal absolute pressure P of the porous tube w That is, P w，1 =P in，1 Therefore, Q of the porous pipe in the first unit segment can be obtained by continuing to use formula (2). por，1 At this point, the parameter calculation for the first unit pipe section is complete. Then, Q is obtained according to formula (3). dq，2 Then, using the same method as in the first unit, P is obtained sequentially. in，2 P w，2 Q por，2 .

[0070] Step S103: Based on the gas flow rate of the leaked gas in the gas guide pipe and the porous pipe in step S102, calculate the transmission time of the leaked gas in each unit pipe segment. Specifically, the following method is used:

[0071] When a leak occurs below the Kth section of the gas duct, the volatilized leaked gas enters the permeable sand layer and then enters the extraction pipeline through the Kth section of the porous pipe. Then:

[0072]

[0073] Among them, Q dq，k The airflow rate in the k-th segment of the air duct is expressed in L / min.

[0074]

[0075] Among them, t k Let A be the transit time of the leaked gas in the k-th segment of the gas duct, in minutes; k L is the cross-sectional area of ​​the air passage in the k-th segment of the air duct; k Let be the length of the k-th segment of the air duct.

[0076] This step uses formulas (5) and (6) to calculate the transmission time of the leaked gas in the Kth segment of the gas duct.

[0077] Step S104: The transmission time of the leaked gas in each unit pipe segment calculated in step S103 is accumulated, and the location of the leak point is determined by the total transmission time. The total transmission time is also the detection time T of the leaked gas, specifically:

[0078]

[0079] Based on the physical device of Embodiment 1, using steps S101 to S104 of this embodiment, the airflow distribution of soil gas in the extraction pipeline can be calculated using formulas (1) to (4). Then, formulas (5) to (7) are used to calculate the transmission time of leaked gas VOCs in each unit pipe section, thereby locating the leak point. The method of this embodiment can minimize the sampling volume and monitoring cost. At the same time, based on the physical detection device of Embodiment 1, a mathematical model of airflow distribution is constructed, which can accurately and quickly predict the leak location based on the detection results. This not only greatly reduces the complexity of on-site work, but also achieves low-cost and high-precision leak location prediction.

[0080] The following is based on Figure 2 The oil storage tank leak detection and specific calculation process involved in the article is given as a concrete example, which includes the airflow rate Q and the leakage gas transmission time t of each unit pipe section. k The leak gas detection time T is compiled into the table below. The actual detection time is compared with the calculated leak gas detection time T in the table. If the actual detection time is close to or equal to the calculated detection time T, it can be determined that the pollution leak occurred in the soil layer below the Kth unit pipe section. This specific example verifies the technical effect of the invention through experiments, which are explained in detail below:

[0081] like Figure 2 As shown, a permeable sand layer with a width of 1 meter is laid along the bottom edge of the oil storage tank. From bottom to top, fine sand, medium sand, and coarse sand layers are laid in sequence, with each layer having a thickness of 0.3m. The permeability coefficient of the fine sand layer is 2.5m / d, and the average particle size is 0.075mm; the permeability coefficient of the medium sand layer is 5m / d, and the average particle size is 0.35mm; the permeability coefficient of the coarse sand layer is 18.5m / d, and the average particle size is 1.5mm.

[0082] The extraction pipeline is laid horizontally along the bottom edge of the oil storage tank within the coarse sand layer of the permeable sand layer. The total length of the extraction pipeline is 21m, divided into 1.05m units. Each unit contains a 1m long guide pipe and a 0.05m long perforated pipe, which are connected by a threaded seal. Both the guide pipe and the perforated pipe are made of polytetrafluoroethylene (PTFE). The guide pipe has an inner diameter of 6mm, the perforated pipe has an inner diameter of 3mm and an outer diameter of 5mm, and the perforated area of ​​the perforated pipe wall accounts for 15% of the total area, with an orifice diameter of 1.5mm. An explosion-proof extraction pump with a flow rate of 15L / min and an inlet pressure of 81KPa is used, and a photoionization detector (PID) is employed as the gas detection system.

[0083] First, activate the PID controller under ambient air conditions for initialization. Once the instrument readings stabilize, connect it to the detection device of this invention, turn on the vacuum pump, and record the PID detection data every 20 seconds. Using gasoline as a simulated pollutant, pour 0.5L of gasoline into the soil layer below the 20th unit section of the vacuum pipeline to simulate a tank leak scenario. Continue running the detection device and record the VOCs detection time.

[0084] Based on the test results, the curve of VOCs concentration changing with the detection time was plotted as follows: Figure 4 . Figure 4 As can be seen from the data, the PID started detecting VOCs at 12.6 minutes, which is the actual detection time T. s =12.6min.

[0085] The airflow distribution mathematical model provided by this invention is used below to locate the specific leak location of the oil storage tank. The initial parameter is: Q dq，1 =15L / min, P out，1 =81×10 3 Pa, P b =101.325x10 3 Pa, μ=7×10 -5 Pa·s, R=0.006m, L=1m, total number of units n=20, r e =0.005m; r w =0.003m, h=0.06m, k=120m / d. Substituting the initial parameters into formulas (1) to (4), the airflow rate in the gas guide pipe and the porous pipe in each unit pipe section can be calculated one by one. Then, formulas (5) and (6) can be used to calculate the transmission time of the leaked gas in the Kth section of the gas guide pipe. By adding the time of the leaked gas in the first section to the Kth section of the gas guide pipe, the total transmission time of the leaked gas in the extraction pipeline can be obtained. The calculation results are shown in Table 1 below:

[0086] Table 1. Simulation results of airflow distribution and leak gas detection time in each unit pipe section.

[0087]

[0088] Based on the aforementioned measured detection time T s =12.6min. Comparing this with the simulated calculation result T, we can find that the simulated total time T for the 20th segment is 13min, which is consistent with the measured detection time T. s The location is closest to the actual leak location, which is near the 20th unit pipe section. This location is basically consistent with the actual leak location, proving that the present invention can achieve the expected technical effect.

[0089] Example 3

[0090] like Figure 5 As shown, this embodiment provides a soil gas-based pollution leak detection system. This system is a virtual device corresponding to the method in Embodiment 2, and therefore, this embodiment can achieve the same technical effect as Embodiment 2. The system includes: a basic data acquisition module 201, an airflow rate calculation module 202, a transmission time calculation module 203, and a leak location determination module 204. The basic data acquisition module 201 is used to acquire basic parameter data of the air guide pipe, the porous pipe, and the suction pump; the airflow rate calculation module 202 is used to calculate the airflow rate of the leaked gas in the air guide pipe and the porous pipe in each unit pipe segment based on the basic parameter data and an airflow distribution model; the transmission time calculation module 203 is used to calculate the transmission time of the leaked gas in each unit pipe segment based on the airflow rate of the leaked gas in the air guide pipe and the porous pipe; the leak location determination module 204 is used to accumulate the transmission time of the leaked gas in each unit pipe segment and determine the location of the leak point based on the total transmission time.

[0091] Example 4

[0092] This embodiment provides a non-transient (non-volatile) computer storage medium storing computer-executable instructions that can execute the methods in any of the above-described method embodiments and achieve the same technical effect. The method includes the following steps: A. Laying out a suction pipeline with uniformly spaced gas guide pipes and porous pipes in a permeable sand layer at corresponding locations in the storage and transportation equipment, and obtaining basic parameter data for the gas guide pipes, porous pipes, and suction pump; B. Calculating the airflow rate of the leaked gas in the gas guide pipes and porous pipes in each unit pipe segment using an airflow distribution model based on the basic parameter data; C. Calculating the transmission time of the leaked gas in each unit pipe segment based on the airflow rate of the leaked gas in the gas guide pipes and porous pipes; D. Accumulating the transmission time of the leaked gas in each unit pipe segment, and determining the location of the leak point based on the total transmission time.

[0093] Example 5

[0094] This embodiment provides a computer program product, which includes a computer program stored on a non-transitory computer-readable storage medium. The computer program includes program instructions, which, when executed by a computer, cause the computer to perform the methods described in the above aspects and achieve the same technical effect. The method includes the following steps: A. Laying out a gas extraction pipeline with uniformly spaced gas guide pipes and porous pipes in a permeable sand layer at corresponding locations in the storage and transportation equipment, and obtaining basic parameter data of the gas guide pipes, porous pipes, and gas extraction pump; B. Calculating the airflow rate of the leaked gas in the gas guide pipes and porous pipes in each unit pipe segment using an airflow distribution model based on the basic parameter data; C. Calculating the transmission time of the leaked gas in each unit pipe segment based on the airflow rate of the leaked gas in the gas guide pipes and porous pipes; D. Accumulating the transmission time of the leaked gas in each unit pipe segment, and determining the location of the leak point by the total transmission time.

[0095] Example 6

[0096] Figure 6 This is a schematic diagram of the hardware structure of the electronic device in this embodiment. The device includes one or more processors 610 and a memory 620. Taking one processor 610 as an example, the device may also include an input device 630 and an output device 640.

[0097] The processor 610, memory 620, input device 630 and output device 640 can be connected by a bus or other means.

[0098] The memory 620, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs, non-transitory computer-executable programs, and modules. The processor 610 executes various functional applications and data processing of the electronic device by running the non-transitory software programs, instructions, and modules stored in the memory 620, thereby implementing the processing method of the above-described method embodiments.

[0099] The memory 620 may include a program storage area and a data storage area, wherein the program storage area may store the operating system and applications required for at least one function; the data storage area may store data, etc. Furthermore, the memory 620 may include high-speed random access memory, and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, the memory 620 may optionally include memory remotely located relative to the processor 610, and these remote memories may be connected to the processing device via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0100] Input device 630 can receive input digital or character information and generate signal input. Output device 640 may include display devices such as a display screen.

[0101] The one or more modules are stored in the memory 620. When executed by the one or more processors 610, the following steps are performed: A. A gas extraction pipeline with uniformly spaced gas guide pipes and porous pipes is laid in the permeable sand layer at the corresponding position of the storage and transportation equipment, and the basic parameter data of the gas guide pipes, porous pipes, and gas extraction pump are obtained; B. Based on the basic parameter data, the airflow rate of the leaked gas in the gas guide pipes and porous pipes in each unit pipe segment is calculated one by one using the airflow distribution model; C. Based on the airflow rate of the leaked gas in the gas guide pipes and porous pipes, the transmission time of the leaked gas in each unit pipe segment is calculated respectively; D. The transmission time of the leaked gas in each unit pipe segment is accumulated, and the location of the leak point is determined by the total transmission time.

[0102] The above-described product can execute the methods provided in the embodiments of the present invention, and has the corresponding functional modules and beneficial effects for executing the methods. Technical details not described in detail in this embodiment can be found in the methods provided in other embodiments of the present invention.

[0103] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0104] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented using software plus a general-purpose hardware platform, or of course, using hardware. Based on this understanding, the above technical solutions, in essence or the parts that contribute to the related technology, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0105] The foregoing description of specific exemplary embodiments of the present invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. Any simple modifications, equivalent changes, and alterations made to the foregoing exemplary embodiments should fall within the scope of protection of the present invention.

Claims

1. A method for detecting pollution leaks based on soil gas, characterized in that, Includes the following steps: A. Lay out the air extraction pipeline with evenly spaced air guide pipes and porous pipes in the permeable sand layer at the corresponding position of the storage and transportation equipment, and obtain the basic parameter data of the air guide pipes, porous pipes and air extraction pump. The basic parameter data in step A include: the air pump flow rate and the inlet pressure of the air pump; the inner diameter and length of the air delivery pipe; the inner and outer diameters, length, and permeability coefficient of the porous pipe; and the background atmospheric pressure and the dynamic viscosity of soil gas at 20°C. B. Based on the basic parameter data, calculate the gas flow rate of the leaked gas in the gas guide pipe and the porous pipe in each unit pipe section one by one using the air flow distribution model; the calculation in step B is to start from the first unit pipe section closest to the air pump and calculate towards the far end of the pipeline one by one; the air flow distribution model includes the following formulas (1) to (4): ； in, The airflow rate in the air delivery tube is L / min; The absolute pressure at the inlet of the air delivery pipe, in Pa; The absolute pressure at the outlet of the air delivery pipe, in Pa; For reference atmospheric pressure, Pa; R is the dynamic viscosity of soil gas at 20℃, Pa·s; R is the inner diameter of the gas delivery pipe, m; L is the length of the gas delivery pipe, m; for the first unit pipe section, The air flow rate of the air pump is [value missing]. The absolute pressure at the inlet of the first unit pipe section is calculated using the formula (1), which is the inlet pressure of the air pump. ; ； in, The airflow rate in the porous tube is expressed in L / min. ρ is the permeability coefficient of the porous tube, m / d; h is the length of the porous tube, m; Background atmospheric pressure, Pa; The absolute pressure inside the porous tube, in Pa, is the absolute pressure at the inlet of the air guide pipe as the airflow passes through the porous tube into each unit pipe section. Equal to the internal absolute pressure of the porous tube ; For reference atmospheric pressure, Pa; The outer diameter of the porous tube is in meters (m). The inner diameter of the porous tube is in meters (m). ； in, is the airflow rate in the (i+1)th segment of the air duct, in L / min; The airflow rate in the i-th segment of the air duct is expressed in L / min. Let L be the airflow velocity in the i-th segment of the porous tube, in L / min. ； in, Let be the absolute pressure at the outlet of the (i+1)th segment of the air duct, in Pa; Let be the internal absolute pressure of the i-th segment of the porous tube, in Pa; C. Based on the gas flow rate of the leaking gas in the gas guide pipe and the porous pipe, calculate the transmission time of the leaking gas in each unit pipe segment; the specific method for calculating the transmission time of the leaking gas in each unit pipe segment in step C is as follows: When a leak occurs below the Kth section of the gas duct, the volatilized leaked gas enters the permeable sand layer and then enters the extraction pipeline through the Kth section of the porous pipe. Then: ； in, The airflow rate in the k-th segment of the air duct is expressed in L / min. ； in, Let be the transit time (in minutes) of the leaked gas in the k-th segment of the gas delivery pipe; Let be the cross-sectional area of ​​the air passage in the k-th segment of the air duct; Let k be the length of the air duct segment. D. Accumulate the transmission time of the leaked gas in each unit pipe segment, and determine the location of the leak point by the total transmission time; the total transmission time in step D is the detection time T of the leaked gas, specifically: 。 2. The method for detecting pollution leaks based on soil gas according to claim 1, characterized in that, The breathable sand layer includes a fine sand layer, a medium sand layer, and a coarse sand layer laid sequentially from bottom to top; the air extraction pipeline is laid horizontally within the coarse sand layer.

3. The method for detecting pollution leaks based on soil gas according to claim 1, characterized in that, The length ratio of the air duct to the porous tube is 10~25:

1.

4. The method for detecting pollution leaks based on soil gas according to claim 1, characterized in that, The inner diameter R of the air duct and the rated flow rate Q of the air pump satisfy R. 2 / Q <1.6*10 -6 .

5. The method for detecting pollution leaks based on soil gas according to claim 1, characterized in that, The storage and transportation equipment is an oil pipeline or an oil storage tank, and the leaked gas is VOCs volatilized from the leaked material of the storage and transportation equipment; the vacuum pump is connected to a gas detector.

6. A soil gas-based pollution leak detection system, characterized in that, The method described in any one of claims 1 to 5 includes: The basic data acquisition module is used to acquire basic parameter data of the air guide tube, the porous tube, and the air pump. The airflow rate calculation module is used to calculate the airflow rate of the leaked gas in the air guide pipe and the porous pipe in each unit pipe segment according to the basic parameter data and the airflow distribution model. The transmission time calculation module is used to calculate the transmission time of the leaked gas in each unit pipe segment based on the airflow rate of the leaked gas in the gas guide pipe and the porous pipe, respectively. The leak location detection module is used to accumulate the transmission time of the leaking gas in each unit pipe segment and determine the location of the leak point by the total transmission time.

7. An electronic device, characterized in that, include: At least one processor; as well as A memory communicatively connected to the at least one processor; wherein, The memory stores instructions that can be executed by the at least one processor to cause the at least one processor to perform the soil gas-based pollution leak detection method as described in any one of claims 1 to 5.

8. A non-transitory computer-readable storage medium, characterized in that, The non-transitory computer-readable storage medium stores computer-executable instructions for causing the computer to perform the soil gas-based pollution leak detection method as described in any one of claims 1 to 5.

Images