External floating roof tank combustible gas detection system based on distributed optical fiber sensing

Abstract

The utility model discloses an external floating roof tank combustible gas detection system based on distributed optical fiber sensing, which comprises a topology selection module, a data acquisition module, a data transmission module, a data analysis module and a gas alarm module, the data transmission module comprises a wireless unit, an optical fiber unit and a network transmission unit, the data analysis module comprises a local edge analysis unit and a network comparison unit, and the gas alarm module is used for carrying out reminding and alarm processing according to data comparison and data analysis results. The optical fiber routing and sensor layout is flexibly adjusted through the topology selection module according to the perimeter, the structure type and the environment level of the external floating roof tank, and the monitoring blind area and the equipment failure rate of the large-perimeter tank are reduced. Multi-source features are fused, influences of temperature and humidity fluctuation, pressure change of a sealing area and equipment vibration on detection precision are eliminated through auxiliary features such as temperature, pressure and vibration, and false alarms are reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of petroleum liquefied gas, in particular to a combustible gas detection system for an outer floating roof tank based on distributed optical fiber sensing. BACKGROUND

[0002] As the core storage facility for volatile petroleum products such as crude oil, gasoline, and kerosene, the outer floating roof tank, with the structural feature that the floating plate rises and falls synchronously with the oil level, can minimize the contact area between the oil and the air, reduce the volatilization loss, and is widely used in the fields of petroleum and chemical industry, storage area, etc. The key to its safe operation lies in the sealing performance of the primary and secondary sealing areas. Due to factors such as structural gap and aging of sealing elements, combustible gases such as propane and butane generated by oil volatilization are easily accumulated in this area. Once the concentration reaches the lower explosive limit and encounters static electricity, lightning, operation errors, etc., it is easy to cause deflagration accidents. At the same time, excessive oil and gas volatilization will also cause air pollution and damage air quality. As a key link for safety protection, the outer floating roof tank gas detection system needs to monitor the combustible gas concentration in the sealing area in real time and accurately, and timely warn of risks. Its performance directly determines the safety protection level and environmental protection compliance ability of the tank area.

[0003] The current outer floating roof tank gas detection technology mainly focuses on electrochemical sensors, semiconductor sensors, ordinary laser sensors, and portable detection devices. Among them, electrochemical and semiconductor sensors have been widely used due to their lower cost, but they need continuous power supply, which not only increases the deployment cost and electrical safety hazards, but also is easily affected by impurities such as long-chain alkanes and hydrogen sulfide in the sealed and oil-rich environment, causing sensor poisoning and fouling failure. Ordinary laser sensors have high safety and methane detection sensitivity, but their working wavelength is only suitable for methane, and they cannot identify propane, butane, and other core components of crude oil volatilization. Moreover, a single sensor needs to be matched with a single transmission optical fiber. In the case of deploying more than 8 sensors in a single storage tank and monitoring multiple tanks in a cluster, the fiber core consumption is huge, and the engineering implementation is difficult. Portable detection devices rely on regular manual inspection and cannot achieve 24-hour real-time monitoring. In the face of sudden leaks, the response is lagging, and the labor cost is high. In addition, existing technologies rely on a single gas concentration parameter to determine risks, without considering the interference of environmental factors such as temperature, humidity, pressure, and vibration on the detection results, which may cause false positives and false negatives.

[0004] Although the existing detection technology can realize basic monitoring function in specific scenarios, there are still four core problems to be solved: first, poor topological adaptability, the existing sensors are mostly fixed deployment mode, which cannot flexibly adjust the optical fiber route and sensor layout according to the circumference of the external floating roof tank, the structure type (single / double), the environment level (oil pollution, salt fog), resulting in more monitoring blind area of large circumference tank and high equipment failure rate in harsh environment; second, weak resistance to multi-source interference, only relying on single gas concentration signal, which cannot eliminate the influence of temperature and humidity fluctuation, sealing area pressure change and equipment vibration on detection accuracy, resulting in high false alarm rate; third, insufficient system expansion, the number of single optical fiber series sensors is limited (usually ≤4), and a large number of optical fibers and host computers need to be laid when monitoring multiple tanks in cluster, resulting in sharp increase of procurement and installation cost; fourth, imbalance between reliability and maintenance cost, electrochemical and semiconductor sensors need to be frequently calibrated and replaced, and laser sensors cannot adapt to core detection components, resulting in short equipment maintenance period and high cost, which is difficult to meet the long-term stable monitoring demand. Practical new type content

[0005] The embodiment of the application provides an external floating roof tank combustible gas detection system based on distributed optical fiber sensing, to solve the problems in the prior art that the topological adaptability of the external floating roof tank combustible gas detection system is poor, the optical fiber route and sensor layout cannot be flexibly adjusted according to the external floating roof tank, resulting in more monitoring blind area of large circumference tank and high equipment failure rate in harsh environment, the resistance to multi-source interference is weak, only relying on single gas concentration signal, which cannot eliminate the influence of temperature and humidity fluctuation, sealing area pressure change and equipment vibration on detection accuracy, resulting in high false alarm rate, the system expansion is insufficient, the number of single optical fiber series sensors is limited, a large number of optical fibers and host computers need to be laid when monitoring multiple tanks in cluster, resulting in sharp increase of procurement and installation cost, the reliability and maintenance cost are imbalanced, electrochemical and semiconductor sensors need to be frequently calibrated and replaced, and laser sensors cannot adapt to core detection components, resulting in short equipment maintenance period and high cost, which is difficult to meet the long-term stable monitoring demand.

[0006] In one aspect, the embodiment of the application provides an external floating roof tank combustible gas detection system based on distributed optical fiber sensing, comprising:

[0007] A topological selection module is configured to select a topological structure according to physical parameters of the external floating roof tank;

[0008] A data acquisition module is configured to arrange sensors according to the topological structure, and the data acquisition module selects a sensor type of a topological node according to the physical parameters of the external floating roof tank;

[0009] A data transmission module, the data transmission module includes a wireless unit, an optical fiber unit and a network transmission unit, the wireless unit is used for local data transmission of the external floating roof tank, the optical fiber unit is used for data transmission of the sensor, and the network transmission unit is used for data transmission between a local edge server and a network server.

[0010] A data analysis module, the data analysis module includes a local edge analysis unit and a network comparison unit, the local edge analysis unit is used for preprocessing and data classification of sensor data collected by the data collection module, and the network comparison unit is used for comparison of the sensor data after preprocessing and data classification with preset data to obtain a gas detection result.

[0011] In a possible implementation, the physical parameters of the external floating roof tank include tank body structure parameters, environment parameters, reliability requirement parameters and storage area scale parameters, the tank body structure parameters are provided with three levels of S1, S2 and S3, the environment parameters are provided with three levels of E1, E2 and E3, the reliability requirement parameters are provided with three levels of R1, R2 and R3, and the storage area scale parameters include three levels of M1, M2 and M3.

[0012] In a possible implementation, the topology structure includes:

[0013] A bus type topology is used for a scenario matching S1+E1+R1+M1 parameters;

[0014] A tree type topology is used for a scenario matching S2 / S3+E2+R2+M1 parameters;

[0015] A star-tree hybrid topology is used for a scenario matching S2+E2+R2+M2 / M1 parameters;

[0016] A ring type redundant topology is used for a scenario matching S2 / S3+E3+R3+M1 / M2 parameters.

[0017] In a possible implementation, the data collection module selects a sensor type according to the physical parameters of the external floating roof tank and the topology structure, the sensor type includes a core sensor and an auxiliary sensor, the core sensor includes a general type, an oil stain resistant type and a salt mist resistant type, and the auxiliary sensor includes a temperature sensor, a pressure sensor and a vibration monitoring sensor.

[0018] In a possible implementation, the sensor is arranged through a strong magnet, and a sensor installation distance is set according to the physical parameters of the external floating roof tank.

[0019] In a possible implementation, the data transmission module is provided with a local, regional, and cloud three-level communication network, which is jointly constructed by the wireless unit, the optical fiber unit, and the network transmission unit.

[0020] In a possible implementation, the local edge analysis unit performs data cleaning, environment calibration, and feature extraction on the sensor data through the local edge server, and the data classification is performed according to the type of the sensor.

[0021] In a possible implementation, the gas alarm module performs alarm processing by risk level, region, and terminal.

[0022] The external floating roof tank combustible gas detection system based on distributed optical fiber sensing in the application has the following advantages:

[0023] (1) The topology selection module quickly sets the optical fiber routing and sensor layout according to the preset table, reduces the monitoring blind area of the large circumference tank, and reduces the equipment failure rate.

[0024] (2) The influence of temperature, pressure, vibration, and other auxiliary features on the detection accuracy is eliminated, such as temperature and humidity fluctuations, changes in sealing area pressure, and equipment vibration, to reduce false positives.

[0025] (3) The topology selection module reduces the laying cost of the sensor. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0027] Figure 1 The structure diagram of the external floating roof tank combustible gas detection system based on distributed optical fiber sensing provided by the embodiment of the present application is shown in the following figure:

[0028] Figure 2 The data transmission diagram of the external floating roof tank combustible gas detection system based on distributed optical fiber sensing provided by the embodiment of the present application is shown in the following figure. DETAILED DESCRIPTION

[0029] With reference to the drawings and the embodiments disclosed in the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0030] A structural diagram of a combustible gas detection system for an external floating roof tank based on distributed optical fiber sensing is provided in the embodiments of the present application. The combustible gas detection system for the external floating roof tank based on distributed optical fiber sensing is provided in the embodiments of the present application, comprising:

[0031] A topology selection module is configured to select a topology structure according to physical parameters of the external floating roof tank.

[0032] A data acquisition module is configured to arrange sensors according to the topology structure. The data acquisition module selects a sensor type of a topology node according to the physical parameters of the external floating roof tank.

[0033] A data transmission module comprises a wireless unit, an optical fiber unit and a network transmission unit. The wireless unit is configured to perform local data transmission of the external floating roof tank. The optical fiber unit is configured to perform data transmission of the sensors. The network transmission unit is configured to perform data transmission between a local edge server and a network server.

[0034] A data analysis module comprises a local edge analysis unit and a network comparison unit. The local edge analysis unit is configured to perform preprocessing and data classification on sensor data collected by the data acquisition module. The network comparison unit is configured to compare the sensor data after preprocessing and data classification with preset data to obtain a gas detection result.

[0035] The physical parameters of the external floating roof tank comprise tank structure parameters, environmental parameters, reliability requirement parameters and storage area scale parameters. The tank structure parameters are set to have three levels of S1, S2 and S3. The environmental parameters are set to have three levels of E1, E2 and E3. The reliability requirement parameters are set to have three levels of R1, R2 and R3. The storage area scale parameters comprise three levels of M1, M2 and M3.

[0036] The topology structure comprises:

[0037] A bus type topology is configured to match a scenario of S1+E1+R1+M1 parameters.

[0038] A tree type topology is configured to match a scenario of S2 / S3+E2+R2+M1 parameters.

[0039] Star-tree hybrid topology: the star-tree hybrid topology is used for matching the scene of S2+E2+R2+M2 / M1 parameters;

[0040] Ring redundancy topology, the ring redundancy topology is used for matching the scene of S2 / S3+E3+R3+M1 / M2 parameters.

[0041] The data acquisition module selects sensor types according to the outer floating roof tank physical parameters and the topology structure, the sensor types include core sensors and auxiliary sensors, the core sensors include general type, oil stain resistant type and salt mist resistant type, and the auxiliary sensors include temperature sensors, pressure sensors and vibration monitoring sensors.

[0042] The sensor is laid through a strong magnet, and the sensor installation distance is set according to the outer floating roof tank physical parameters.

[0043] The data transmission module is provided with a local, regional, cloud three-level communication network, and the local, regional, cloud three-level communication network is jointly constructed through the wireless unit, the optical fiber unit and the network transmission unit.

[0044] The local edge analysis unit performs data cleaning, environment calibration and feature extraction on the sensor data through the local edge server, and the data classification is classified according to the type of the sensor.

[0045] The gas alarm module performs alarm processing by risk level, region and terminal.

[0046] Exemplarily, according to the parameter comparison table setting in “Optical Fiber Sensing Network” (Beijing: Science Press, Chapter 2 of “Optical Fiber Sensing Network” “Networking and Topology of Optical Fiber Sensing Network”), the existing topology scheme is set to a comparison table scheme in advance.

[0047] Key parameters are obtained by manual input or automatic acquisition of sensors, and the outer floating roof tank physical parameters are shown in Table 1 as follows:

[0048] Table 1 Comparison table of outer floating roof tank physical parameters

[0049]

[0050] The matching logic of the topology structure is set according to Table 1:

[0051] Bus topology: matching S1+E1+R1+M1 scene, such as 120m perimeter inland diesel tank, single armored optical fiber in series with 6-8 sensors, no shunt device, cost reduction of about 30%.

[0052] Tree topology: match S2 / S3+E2+R2+M1 scenario, such as 250m circumference crude oil tank, through the fiber distribution box, 4-way branching, each way in series with 3-4 sensors, suitable for large circumference coverage.

[0053] Star-tree hybrid topology: match S2+E2+R2+M2 / M3 scenario, such as 6-tank cluster, the central control room is connected to each tank sub-control unit through the main fiber, and the tree sub-topology is used in the tank, supporting 32-tank parallel monitoring.

[0054] Ring redundancy topology: match S2 / S3+E3+R3+M1 / M2 scenario (such as 180m circumference gasoline tank along the coast), double-fiber ring design, ring redundancy topology supports automatic switching, with switching time <3s, and the sensor of ring redundancy topology is deployed with double sensors at the same point.

[0055] Through the above matching logic and the physical parameter table of the external floating roof tank, the topology structure diagram, the fiber laying path diagram, and the sensor deployment point table of the external floating roof tank are output.

[0056] The data acquisition module completes sensor selection, layout and data acquisition according to the scheme output by the topology selection module, and realizes real-time sensing of combustible gas concentration and environmental parameters.

[0057] Among them, the sensor selection rules are as follows:

[0058] The core sensor is a passive optical fiber sensor based on laser spectrum absorption principle, with a center wavelength of 1653nm, and different environmental models are selected: E1 environment: suitable for general sensor, protection level IP65; E2 environment: suitable for oil stain resistant probe with fluorine coating; E3 environment: suitable for salt mist resistant 316 stainless steel shell, protection level IP66.

[0059] Auxiliary sensors are also provided, including: the temperature sensor PT1000 has an accuracy of ±0.5℃, and the E3 environment selects a wide temperature type with a temperature of -40℃~85℃; the pressure sensor selects an absolute pressure type, and the pressure range is 0~10kPa; the vibration monitoring selects a multiplexed distributed optical fiber, and the optical fiber monitors the vibration of 10~500Hz through Rayleigh scattering.

[0060] When the sensors are laid out, the sensor spacing is uniformly distributed according to the circumference of the sealing area, S1 grade tank ≤25m, S2 / S3 grade tank ≤20m, and high-risk scenarios such as gasoline tank ≤10m; the position of the sensor is that the spectral sensor is installed on the rain shield inside 30cm above the secondary seal, and the probe is inclined at 45° and points to the sealing gap.

[0061] Temperature / pressure sensors are deployed with the spectral sensors on the same bracket, with one temperature sensor for every two spectral sensors; the sensors are arranged through stainless steel brackets and strong magnets, and the sensors are adsorbed under the rain shield by the strong magnet, and in the E3 environment, the sensors need to be equipped with corrosion-resistant gaskets.

[0062] During data acquisition, the sampling frequency of the spectral sensor of the passive optical fiber is 1 Hz for the spectral signal, the sampling frequency of the temperature sensor is 1 Hz for the temperature signal, the sampling frequency of the pressure sensor is 0.5 Hz for the pressure signal, and the sampling frequency of the vibration sensor is 20 Hz for the vibration signal. The data format of all sensors is JSON format with timestamp, the synchronization accuracy of the timestamp is ≤1 ms, and the data contains sensor ID, original value, and status code.

[0063] The data transmission module realizes reliable transmission and redundant backup of sensor data according to a three-level transmission network of "local-region-cloud", wherein the three-level transmission network includes three transmission units of a wireless unit, an optical fiber unit, and a network transmission unit, and specifically:

[0064] The optical fiber unit is a core transmission link, and the transmission medium is an armored optical cable for use in the tank, and a salt mist resistant optical cable is selected in the E3 environment; the routing protection of the optical fiber unit is realized by passing through a zinc-coated conduit in the floating ladder section, the metal drag chain is used in the floating disc lifting section, and the rain shield section is laid along the C-shaped steel bracket;

[0065] The wireless unit is a local auxiliary transmission, which is used for short distance communication between the sub-control unit and the local edge server; it is deployed on the tank top and supports battery power supply;

[0066] The network transmission unit is a remote transmission, and the edge server to the cloud uses the MQTT protocol for encrypted transmission, the main link uses industrial Ethernet, and the standby link uses 4G / 5G network.

[0067] In the data analysis module, through local preprocessing and cloud comparison analysis, accurate determination of the concentration of combustible gas is realized, and misjudgment caused by environmental interference and equipment failure is excluded.

[0068] The local edge analysis unit first preprocesses the sensor data, removes sensor outliers such as out-of-range spectral signals through data cleaning, then performs environmental calibration such as temperature compensation and pressure correction, and finally performs feature extraction to extract basic features such as spectral peak intensity, peak width, temperature gradient, and vibration energy spectrum. Then, according to the sensor type, the data is classified and the abnormal data is marked.

[0069] The results are classified by checking with real-time measurement data to realize alarm.

[0070] While the preferred embodiments of the application have been described, additional variations and modifications can be made to these embodiments by those skilled in the art once they have the benefit of the present disclosure without departing from the spirit and scope of the application. Accordingly, it is intended that the appended claims include all such modifications and variations as fall within the scope of the present application.

[0071] It is apparent that many modifications and variations of this application can be effected although only a few have been chosen for purposes of disclosure. Thus, it is intended that this application include all such modifications and variations as fall within the scope of the claims and their equivalents.

Claims

1. A combustible gas detection system for external floating roof tanks based on distributed fiber optic sensing, characterized in that, include: A topology selection module, which is used to select a topology structure based on the physical parameters of the external floating roof tank; A data acquisition module is used to deploy sensors according to the topology, and the data acquisition module selects the sensor type of the topology node according to the physical parameters of the external floating roof tank. The data transmission module includes a wireless unit, an optical fiber unit, and a network transmission unit. The wireless unit is used for local data transmission of the external floating roof tank, the optical fiber unit is used for data transmission of the sensors, and the network transmission unit is used for data transmission between the local edge server and the network server. The data analysis module includes a local edge analysis unit and a network comparison unit. The local edge analysis unit is used to preprocess and classify the sensor data collected by the data acquisition module. The network comparison unit is used to compare the preprocessed and classified sensor data with preset data to obtain gas detection results.

2. The combustible gas detection system for external floating roof tanks based on distributed optical fiber sensing according to claim 1, characterized in that, The physical parameters of the external floating roof tank include tank structure parameters, environmental parameters, reliability requirement parameters, and storage area size parameters. The tank structure parameters are set with three levels: S1, S2, and S3. The environmental parameters are set with three levels: E1, E2, and E3. The reliability requirement parameters are set with three levels: R1, R2, and R3. The storage area size parameters are set with three levels: M1, M2, and M3.

3. The combustible gas detection system for external floating roof tanks based on distributed optical fiber sensing according to claim 1, characterized in that, The topology includes: A bus topology, which is used to match scenarios with parameters S1+E1+R1+M1; A tree topology, which is used to match scenarios with parameters S2 / S3+E2+R2+M1; Star-tree hybrid topology: The star-tree hybrid topology is used to match scenarios with parameters S2+E2+R2+M2 / M1; A ring-shaped redundant topology is used to match scenarios with parameters S2 / S3+E3+R3+M1 / M2.

4. The combustible gas detection system for external floating roof tanks based on distributed optical fiber sensing according to claim 3, characterized in that, The data acquisition module selects sensor types based on the physical parameters and topology of the external floating roof tank. The sensor types include core sensors and auxiliary sensors. The core sensors include general-purpose, oil-resistant, and salt spray resistant types. The auxiliary sensors include temperature sensors, pressure sensors, and vibration monitoring sensors.

5. The combustible gas detection system for external floating roof tanks based on distributed optical fiber sensing according to claim 1, characterized in that, The sensors are deployed using strong magnets, and the installation distance of the sensors is set according to the physical parameters of the external floating roof tank.

6. The combustible gas detection system for external floating roof tanks based on distributed optical fiber sensing according to claim 1, characterized in that, The data transmission module is equipped with a three-level communication network consisting of local, regional, and cloud-based components. This three-level communication network is jointly constructed by the wireless unit, the fiber optic unit, and the network transmission unit.

7. The combustible gas detection system for external floating roof tanks based on distributed optical fiber sensing according to claim 1, characterized in that, The local edge analysis unit performs data cleaning, environmental calibration, and feature extraction on the sensor data through the local edge server. The data classification classifies the sensor data according to the type of sensor.

8. The combustible gas detection system for external floating roof tanks based on distributed optical fiber sensing according to claim 1, characterized in that, The gas alarm module classifies and processes alarms by risk level, region, and terminal.

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