Laser Methane Sensor Research Articles

Natural gas leakage: Forward and inverse method of leakage field based on multipath concentration monitoring

Natural gas leakage can easily lead to safety accidents and environmental pollution, affecting normal safe production and sustainable energy development. Among them, the leakage accident caused by the integrity failure of the process equipment is particularly noteworthy. To improve the efficiency of methane leakage monitoring and the accuracy of leakage source location, the forward prediction model of leakage concentration field, the optimization model of monitoring equipment layout, and the inversion model of leakage source location were established. To evaluate the model’s applicability, an open-air oil–gas joint station was selected for experimental simulation. The monitoring data of the open circuit laser methane sensor and the forward simulation results of the leakage concentration field were compared. It was found that at 30 % methane concentration, the monitoring distance was 0–6 m, with high monitoring accuracy. Then, by eliminating redundant monitoring sensors, three leakage field concentration monitoring paths are formed. A representative leakage source scenario set is selected for inversion localization. In the simulation of the single-point leakage experiment, the leakage location error is 1.824 m, and the average relative error is 3.6 %. Through error analysis, the results show that the inversion positioning model can also have a good adaptability to the parameter estimation of the leakage source when there are only 3 sets of observation data.

Temperature Compensation of Laser Methane Sensor Based on a Large-Scale Dataset and the ISSA-BP Neural Network.

We aimed to improve the detection accuracy of laser methane sensors in expansive temperature application environments. In this paper, a large-scale dataset of the measured concentration of the sensor at different temperatures is established, and a temperature compensation model based on the ISSA-BP neural network is proposed. On the data side, a large-scale dataset of 15,810 sets of laser methane sensors with different temperatures and concentrations was established, and an Improved Isolation Forest algorithm was used to clean the large-scale data and remove the outliers in the dataset. On the modeling framework, a temperature compensation model based on the ISSA-BP neural network is proposed. The quasi-reflective learning, chameleon swarm algorithm, Lévy flight, and artificial rabbits optimization are utilized to improve the initialization of the sparrow population, explorer position, anti-predator position, and position of individual sparrows in each generation, respectively, to improve the global optimization seeking ability of the standard sparrow search algorithm. The ISSA-BP temperature compensation model far outperforms the four models, SVM, RF, BP, and PSO-BP, in model evaluation metrics such as MAE, MAPE, RMSE, and R-square for both the training and test sets. The results show that the algorithm in this paper can significantly improve the detection accuracy of the laser methane sensor under the wide temperature application environment.

宽温紧凑型全量程激光甲烷传感探头设计

宽温紧凑型全量程激光甲烷传感探头设计

Laser methane sensor and its field application in coal mine safety

Based on the principle of laser absorption spectroscopy, a laser methane sensor for mine use has been developed. The design of the sensor system is discussed and its practical application for methane detection in coal mines is considered. A control system coupled to the sensor has been developed and the results obtained show the high quality of the performance of the laser methane sensor over the traditional catalytic combustion sensor and infrared sensor in many performance aspects, such as large range, high precision and low power consumption

Using autonomous underwater gliders for geochemical exploration surveys

Offshore exploration commonly uses geochemical sniffer technologies to detect hydrocarbon seepage. Advancements in sniffer technology have seen the development of submersible in-situ methane sensors. By integrating a Franatech laser methane sensor onto an autonomous underwater glider platform, geochemical survey durations can be increased, and associated exploration costs reduced. This paper analyses the effectiveness of methane detection using the integrated system and assesses its practical application to offshore hydrocarbon seep detection methods. Blue Ocean Monitoring surveyed the Yampi Shelf, an area with known oil and gas accumulations, and observed hydrocarbon seeps on the North West Shelf of Australia. Results from the survey showed a background dissolved methane concentration of 3 to 4 volumes per million (vpm). A distinct plume of methane between 30 to 84 vpm measured over 24 km2 was detected early in the survey. Three smaller plumes were also identified. Within a small plume, the highest concentration of methane was detected at 160 vpm. Methane above background levels was observed within 8 km of previously identified seeps; however, these seeps were unable to be pinpointed. Comparisons with data from previous surveys suggest similar oceanographic influences on the behaviour of the seeps, including tidal variations and the position of the thermocline. The results demonstrated that the integrated system may be used to effectively ground truth remote sensing interpretations and survey areas of interest over long durations, providing methane presence or absence results. To this effect, the integrated system may be implemented as a supporting technology for assessing the risks of further funding hydrocarbon detection surveys and focusing the area of interest before the deployment of vessel-based surveys.

A fiber optic methane sensor based on wavelength adaptive vertical cavity surface emitting laser without thermoelectric cooler

Based on Tunable Diode Laser Absorption Spectroscopy (TDLAS) technique and the feature of Vertical Cavity Surface Emitting Laser (VCSEL) wavelength scanning range up to dozens of nanometer, methane detection technique based on wavelength adaptive VCSEL without Thermoelectric Cooler (TEC), is proposed, then the laser methane sensor system design is followed. The reliability experiments study under variety of environments in laboratory, such as temperature impact test, damp heat, and cyclic and dusty impact test, were carried out. And then the test data and some analysis were given. These data verified the feasibility of the wavelength adaptive technique, and these data showed the laser methane sensor can provide long working time without any calibration, and they have the advantages of high accuracy and stability.

Fiber Laser Methane Sensor and its Application in Coal Mine Safety

Abstract Using the technology of tuneable diode laser absorption spectroscopy and the technology of micro-electronics, a fiber laser methane sensor based on C8051F410 is given. We use the DFB Laser as the light source of the sensor. By tuning temperature and driver current of the DFB laser, we can scan the laser over the methane absorption line, we realize the methane detection. It makes the real-time and online detection of methane concentration to be true, and it has the advantages just as high accuracy, immunity to other gases, long calibration cycle and so on. The sensor has the function of self-diagnose, the soft will alarm when the probe in a fault status, then it improve the dependence of the measurements. In coal mine safety, the proportion of gas accidents are improving continuously, Since for the coal mine safety, the personnel safety and the environment protection, it is very important to realize the real-time online detection of methane in coal mine. In this paper, some data that coming from the application of sensor in the field of coal mine is given. And we also do some analysis of the data. At last, according to the actual situation of the transducer in coal mine, we list some problems and the direction of further improvements.

Influence of ethylene spectral lines on methane concentration measurements with a diode laser methane sensor in the 1.65 μm region

Spectra measurements around 1.65 μm have revealed that spectral lines of ethylene are present in this range along with methane spectral lines. Furthermore, the HITRAN database has no parameters of these ethylene lines. In particular, it was found that several ethylene absorption lines are located near the methane feature often used for quantitative spectroscopy (R3 triplet of the 2ν3 band). Ethylene can be present together with methane in the samples under study, perturbing the recorded spectrum of CH4. This perturbation by an interfering species can produce systematic errors in the derived CH4 concentration. We have found in this work by numerical modelling that when measuring the methane concentration by a diode laser methane sensor operating in the 6046–6048 cm-1 range, the systematic error on the retrieved CH4 concentration decreases, as a rule, when decreasing the width of the fitted spectral window. At equal concentrations of ethylene and methane in the sample under study, the error on the concentration of CH4 determined by the correlation technique can reach 15%. When using the technique based on the 2nd or 3rd derivative of the spectrum, interfering or impurity lines induce a systematic error on the derived CH4 concentration, which is less than 2%.