Main Gas Research Articles

Low Power Gas Sensors: From Structure to Application.

Gas sensors are pivotal across industries, encompassing environmental monitoring, industrial safety, and healthcare. Recently, a surge in demand for low power gas sensors has emerged, driven by the huge need for applications in portable devices, wireless sensor networks, and the Internet of things (IoT). The practical realization of a densely interconnected sensor network demands gas sensors to have low power consumption for energy-efficient operation. This Perspective offers a comprehensive overview of the progress of low-power sensors for gas and volatile organic compound detection, with a keen focus on the interplay between sensing materials (including metal oxide semiconductors, metal-organic frameworks, and two-dimensional materials), sensor structures, and power consumption. The main gas sensing mechanisms are discussed, and we delve into the mechanisms for achieving low power consumption including material properties and sensor design. Furthermore, typical applications of low power gas sensors are also presented, including wearable technology, food safety, and environmental monitoring. The review will end by discussing some open questions and ongoing needs.

Towards atomic-scale smooth surface manufacturing of β-Ga2O3 via highly efficient atmospheric plasma etching

Abstract The highly efficient manufacturing of atomic-scale smooth β-Ga2O3 surface is fairly challenging because β-Ga2O3 is a typical difficult-to-machine material. In this study, a novel plasma dry etching method named plasma-based atom-selective etching (PASE) is proposed to achieve the highly efficient, atomic-scale, and damage-free polishing of β-Ga2O3. The plasma is excited through the inductive coupling principle and carbon tetrafluoride is utilized as the main reaction gas to etch β-Ga2O3. The core of PASE polishing of β-Ga2O3 is the remarkable lateral etching effect, which is ensured by both the intrinsic property of the surface and the extrinsic temperature condition. As revealed by density functional theory-based calculations, the intrinsic difference in the etching energy barrier of atoms at the step edge (2.36 eV) and in the terrace plane (4.37 eV) determines their difference in the etching rate, and their etching rate difference can be greatly enlarged by increasing the extrinsic temperature. The polishing of β-Ga2O3 based on the lateral etching effect is further verified in the etching experiments. The Sa roughness of β-Ga2O3 (001) substrate is decreased from 14.8 to 0.057 nm within 120 s, and the corresponding material removal rate reaches up to 20.96 μm/min. The polished β-Ga2O3 displays significantly improved crystalline quality and photoluminescence intensity, and the polishing effect of PASE is independent of the crystal faces of β-Ga2O3. In addition, the competition between chemical etching and physical reconstruction, which is determined by temperature and greatly affects the surface state of β-Ga2O3, is deeply studied for the first time. These findings not only demonstrate the high-efficiency and high-quality polishing of β-Ga2O3 via atmospheric plasma etching but also hold significant implications for guiding future plasma-based surface manufacturing of β-Ga2O3.

ANALYSIS OF THE CAUSES OF ACCIDENTS IN THE OIL AND GAS INDUSTRY

In the modern world, the oil and gas industry plays a key role in ensuring the energy security of countries. An important problem of this industry is the high level of accidents on main pipelines. The importance of issues of ensuring the safety of production processes and working conditions of personnel is obvious: accidents that occur at enterprises can paralyze work for a long time, attracting the attention of the media and regulatory authorities, causing not only financial but also significant image damage. In connection with the above, the analysis and statistical study of accidents in this area have become relevant in recent years. Occupational safety measures include risk assessment at workplaces, briefings, medical examinations, provision of personnel with personal protective equipment, special assessment of workplaces, occupational safety days, etc. In order to restore the technical and economic indicators of the oil and gas industry, increase reliability and trouble-free operation, complexes of measures are carried out to repair, reconstruct and modernize the components of the main gas pipeline. Ensuring industrial safety during repair work depends on both the reliability of the process equipment and the reliability of the personnel, since a significant number of accidents and incidents occur due to reasons related to the influence of the human factor. Many studies have been devoted to the problem of management in the field of labor protection and ensuring safety at work. Despite the significant number of works, a practical lack of developments on the issues of managing the processes of ensuring safety and labor protection at enterprises in the oil and gas industry has been discovered, which indicates the need for a more in-depth study of this topic.

Study on the effect pattern of moisture on the oxidized combustion of ventilation air methane

AbstractVentilation air methane (VAM) is one of the main greenhouse gas sources. Owing to the characteristics of low concentration of ventilation air methane and high moisture content, we build an experimental platform and take the oxidative combustion temperature and methane conversion rate as the research indexes, and the systematic research finds that the inhibitory effect of moisture on the oxidative combustion of ultra‐low concentration of methane (<1%) is a nonlinear polynomial law. In the meantime, we constructed OH(H2O)n+CH4 and studied its reaction potential energy surface using quantum chemical calculations, which used the most significant primitive reaction of methane combustion, OH+CH4→H2O+CH3, as the theoretical basis. We found that as moisture content increased, so did its reaction energy barrier, making the reactants more stable, strengthening the three‐body collision effect, and reducing the number of free radicals, all of which hindered the methane chain reaction. The study aimed to validate the experimental finding that moisture inhibits the oxidative combustion of ventilation air methane by examining the internal mechanism of methane oxidation. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd.

A novel acid-free combined technology to achieve the full recovery of crystalline silicon photovoltaic waste

To achieve the global carbon neutrality commitment, photovoltaics, a clean and renewable source of energy, is increasingly deployed. Photovoltaic panels are core components of photovoltaic systems. As these panels reach the end of their life, recovering the photovoltaic waste becomes crucial. Currently, strong acid reagents are commonly used in the recovery of silver from crystalline silicon photovoltaic waste, posing environmental risks and restricting the industrialization of their recycling. In this study, a novel acid-free technology to achieve the full recovery of crystalline silicon photovoltaic waste was proposed. A pyrolysis process was first conducted for decapsulation, with carbon dioxide being the main gas component at 60.64 %. Next, bioleaching technology was employed to leach silver from waste crystalline silicon photovoltaic cells. The silver leaching rate in a single leaching cycle reached 44.7 %. Meanwhile, the mechanism of silver leaching was further analyzed. Finally, high-velocity fluid frictional separation, a technique that uses high-speed fluid flow to separate material, was chosen to obtain silicon wafers. The reclaimed silicon samples had a total thickness variation of 6.64 µm to11.62 µm, with average carrier lifetimes exceeding 4.9 µs, higher than that obtained by wet etching. This study is expected to advance the industrialization of the recovery of photovoltaic waste, which is also beneficial for the sustainable development of the photovoltaic supply chain.

Diagnosis of GHG Emissions in an Offshore Oil and Gas Production Facility

This work presents a diagnosis of greenhouse gas (GHG) emissions for floating production storage and offloading (FPSO) platforms for oil and gas production offshore, using calculation methodologies from the American Petroleum Institute (API) and U.S. Environmental Protection Agency (EPA). To carry out this analysis, design data of an FPSO platform is used for the GHG emissions estimation, considering operations under steady conditions and oil and gas processing system simulations in the Aspen HYSYS® software. The main direct emission sources of GHG are identified, including the main combustion processes (gas turbines for electric generation and gas turbine-driven CO2 compressors), flaring and venting, as well as fugitive emissions. The study assesses a high CO2 content in molar composition of the associated gas, an important factor that is considered in estimating fugitive emissions during the processes of primary separation and main gas compression. The resulting information indicates that, on average, 95% of total emissions are produced by combustion sources. In the latest production stages of the oil and gas field, it consumes 2 times more energy and emits 2.3 times CO2 in terms of produced hydrocarbons. This diagnosis provides a baseline and starting point for the implementation of energy efficiency measures and/or carbon capture and storage (CCS) technologies on the FPSO in order to reduce CO2 and CH4 emissions, as well as identify the major sources of emissions in the production process.

Negative impact of vibration on process pipelines of a compressor station with electrically driven gas pumping units

Relevance. In gas industry, the amount of equipment that has outlived its intended service life is increasing every year. In accordance with the law “On Industrial Safety of Hazardous Production Facilities,” compressor stations are dangerous objects, the reliable operation of which largely determines the condition of main gas pipelines. Technological pipelines of a compressor station are important objects of this system. They are subject to strict requirements due to the action of static and dynamic loads on them. Reliability of compressor stations is based on the results of a study of the condition of the object and the main factors affecting increased wear of equipment. The solution to wear problem is timely monitoring of equipment, in particular level measurement and determining the causes of pipeline vibrations using vibration diagnostics methods, and frequency and modal analysis methods. Aim. To study the causes of increased dynamic loads on the technological piping that arise during the operation of electric and gas pumping units at a compressor station using vibration monitoring methods. Methods. Vibration monitoring methods to analyze the causes of increased vibration values in the process piping of a compressor station with an electric gas pumping unit. Results and conclusions. The authors have measured vibration in a wide frequency band and assessed the technological condition of the main equipment of the compressor station with EGPA-6.3/8200-56/1.44-R based on the regulatory documentation STO Gazprom 2-2.3-324-2009. The main frequencies of the root-mean-square value of the vibration velocity, at which the highest vibration values were observed, were identified, and a modal analysis was performed using ANSYS software. Based on the results of natural studies and modal analysis, it was concluded about the occurrence of resonant high-frequency oscillations, multiple of the rotor rotation frequency.

Short-Term Prediction Method for Gas Concentration in Poultry Houses Under Different Feeding Patterns

Ammonia (NH3) and carbon dioxide (CO2) are the main gases that affect indoor air quality and the health of the chicken flock. Currently, the environmental control strategy for poultry houses mainly relies on real-time temperature, resulting in lag and singleness. Indoor air quality can be improved by predicting the change in CO2 concentration and proposing an optimal control strategy. Combining the advantages of seasonal-trend decomposition using loess (STL), Granger causality (GC), long short-term memory (LSTM), and extreme gradient boosting (XGBoost), an ensemble method called the STL-GC-LSTM-XGBoost model is proposed. This model can set fast response prediction results at a lower cost and has strong generalization ability. The comparative analysis shows that the proposed STL-GC-LSTM-XGBoost model achieved high prediction accuracy, performance, and confidence in predicting CO2 levels under different environmental regulation modes and data volumes. However, its prediction accuracy for NH3 was slightly lower than that of the STL-GC-LSTM model. This may be due to the limited variability and regularity of the NH3 dataset, which likely increased model complexity and decreased predictive ability with the introduction of XGBoost. Nevertheless, in general, the proposed integrated model still provides a feasible approach for gas concentration prediction and health-related risk control in poultry houses.

Study on the Characteristics of Combustible Mixed Gas Production during Lignite Oxidation Process

CO, H2, and other combustible gases will be produced during coal oxidation in coal mines, which will increase the risk of explosion when mixed with methane. Therefore, it is very important to understand the production characteristics of combustible gas during coal oxidation. In this paper, a programmed temperature gas test system is built to study the impact of lignite on the production of gases at different particle sizes and temperatures, and the release characteristics of gases are also analyzed. The result shows that the production of combustible gas is influenced by the coal particle size significantly when the temperature is above 200 °C, and it decreases as the particle size increases. CO is the main gas during the early stage of coal spontaneous combustion, and the release of CH4 and H2 increases after 300 °C. The fitted equations of gas generation and temperature are consistent with the experimental results. The research results are helpful in understanding the hazards of coal spontaneous combustion and have a certain guiding significance for coal mine monitoring and prevention of coal spontaneous combustion.

Study on control strategies of the MW-scale supercritical CO2 recompression Brayton cycle for lead-cooled fast reactor

The supercritical CO2 (sCO2) Brayton cycle for the lead-cooled fast reactor (LFR) is an ideal power generation system for the distributed energy supply in remote islands. To figure out the optimal operating modes of the MW-scale sCO2 LFR unit in different load demands, this work performs a dynamic simulation based on the developed control modules. A parametric analysis is conducted about the effects of rotational speed, split ratio, and main gas temperature on the dynamic characteristics. Control strategies are further studied based on the thermodynamic performance and safety under four variable temperature load regulation modes and three fixed temperature rapid load regulation modes. Results show that the tracking αopt mode has the highest average net efficiency (ηnetav) of 19.13 %. The tracking αsafe mode allows compressors to operate in the safest range by sacrificing a little ηnetav. Excellent load change rates are revealed by using the main circuit regulating valve control mode and the turbine bypass control mode, with −12.48 %Pe/min & 11.92 %Pe/min, and −8.25 %Pe/min & 9.70 %Pe/min, respectively. Though the load change rate of the RS control mode is −3.96 %Pe/min & 3.47 %Pe/min, its ηnetav is higher. Our work guides the efficient, flexible, and safe operation of the sCO2 LFR unit.

Noble Gases, Carbon and Nitrogen Isotopes in Different Lithologies of Pesyanoe: Irradiation History and Impact Processes on the Aubrite Parent Body

Abstract We present the results of stepwise crushing and combustion analyses for noble gases, carbon and nitrogen in Pesyanoe aubrite pyroxene lithologies, composed of grey (Px-G) and light (Px-B) enstatites differing in the degree of impact processing and the number of inclusions. Our study identifies three main noble gas endmembers in Pesyanoe: a cosmogenic component, radiogenic 40Ar, and an endmember representing a mixture of solar wind and Q components in variable proportions. Based on petrographic and noble gas data we argue that these gases accumulated in the material during its regolith history and were later redistributed into gas inclusions/voids as the result of an impact event. During impact metamorphism, Px-G acquired its grey color and multiple gas inclusions were formed within it, more than in case of Px-B. Our study demonstrates for the first time: (1) The host phase of gases trapped during shock metamorphism are grains of rock-forming minerals, in particular Px-G, due to the formation of a large number of cracks in the direction of cleavage during brittle deformation, (2) The gas capture is associated not with the final stage of the formation of consolidated fragmental breccia, at which lithification of the fragments occurred, but with one of the intermediate impact events. High amounts of trapped and cosmogenic noble gases are released during the stepwise crushing—significantly higher than in case of any other studied aubrite. Some unusually high 36Ar/132Xe ratios (up to 54 780 versus 22 705 in the solar wind) were discovered during crushing of Px-G. Our preferable explanation of this phenomenon is a specific superposition of noble gas elemental fractionation processes related to the impact cratering of the Pesyanoe parent body. The carbon isotopic composition (δ13C = –21.2 ± 0.2‰, 1σ) is slightly heavier than that of the Bustee aubrite carbon. The combined use of different extraction methods made it possible to determine that the solar type and indigenous (δ15Nindig = –0.1 ± 3.2‰, 1σ) nitrogen components are located in the gas inclusions, whereas the extraneous nitrogen component (~+45‰) is chemically bound. The large cosmic ray exposure age variations (44 and 55 Ma in case of Px-G and Px-B, respectively) and the heterogeneous distribution of solar-type gases in Pesyanoe aubrite point to a diverse irradiation history of the material before breccia formation. Alternatively/additionally, cosmogenic gases (as well as solar and primordial) in Px-G may have became lost and/or partly redistributed into gas inclusions as a result of the impact event.

CONTROL OF SHROUD LEAKAGE LOSS AND WINDAGE TORQUE IN A LOW-PRESSURE TURBINE STAGE

Abstract As new aeroengine architectures move to larger diameter fans and rotors, the associated increase in weight will need to be counterbalanced by lighter, more compact, and more efficient low-pressure turbines (LPT). Efficiency gains in LPTs can be achieved by reducing the losses associated with the shroud leakage flows. Flow control studies on the topic have traditionally focused on reducing the mixing loss, which constitutes a considerable proportion of the total loss. Nonetheless, increasing engine speeds are driving additional gains obtained by also targeting the reduction of windage losses. Developing a flow control solution with the dual objective of reducing over-tip cavity mixing and windage losses has not previously been attempted. This is a challenge due to conflicting flow control requirements and geometric constraints. Reducing windage loss generally requires increasing the swirl-ratio of the leakage flow, while reducing mixing loss requires reducing this ratio to match that of the main gas path. The current work proposes a novel flow control solution to successfully achieve this purpose through the emerging technology of additive manufacturing. The successful flow control concept was developed through numerical simulation, printed using an additive manufacturing process, and validated in a purpose-built rig. Experiments and computations were consistent with a cumulative reduction in cavity windage of 16%. The FCC is estimated to increase the mechanical efficiency of the turbine stage in isolation by 1%.

Enrichment conditions and resource potential of coal-rock gas in Ordos Basin, NW China

To reveal the enrichment conditions and resource potential of coal-rock gas in the Ordos Basin, this paper presents a systematic research on the sedimentary environment, distribution, physical properties, reservoir characteristics, gas-bearing characteristics and gas accumulation play of deep coals. The results show that thick coals are widely distributed in the Carboniferous–Permian of the Ordos Basin. The main coal seams Carboniferous 5# and Permian 8# in the Carboniferous–Permian have strong hydrocarbon generation capacity and high thermal evolution degree, which provide abundant materials for the formation of coal-rock gas. Deep coal reservoirs have good physical properties, especially porosity and permeability. Coal seams Carboniferous 5# and Permian 8# exhibit the average porosity of 4.1% and 6.4%, and the average permeability of 8.7×10−3 μm2 and 15.7×10−3 μm2, respectively. Cleats and fissures are developed in the coals, and together with the micropores, constitute the main storage space. With the increase of evolution degree, the micropore volume tends to increase. The development degree of cleats and fissures has a great impact on permeability. The coal reservoirs and their industrial compositions exhibit significantly heterogeneous distribution in the vertical direction. The bright coal seam, which is in the middle and upper section, less affected by ash filling compared with the lower section, and contains well-developed pores and fissures, is a high-quality reservoir interval. The deep coals present good gas-bearing characteristics in Ordos Basin, with the gas content of 7.5–20.0 m3/t, and the proportion of free gas (greater than 10%, mostly 11.0%–55.1%) in coal-rock gas significantly higher than that in shallow coals. The enrichment degree of free gas in deep coals is controlled by the number of macropores and microfractures. The coal rock pressure testing shows that the coal-limestone and coal-mudstone combinations for gas accumulation have good sealing capacity, and the mudstone/limestone (roof)-coal-mudstone (floor) combination generally indicates high coal-rock gas values. The coal-rock gas resources in the Ordos Basin were preliminarily estimated by the volume method to be 22.38×1012 m3, and the main coal-rock gas prospects in the Ordos Basin were defined. In the central-east of the Ordos Basin, Wushenqi, Hengshan–Suide, Yan'an, Zichang, and Yichuan are coal-rock gas prospects for the coal seam #8 of the Benxi Formation, and Linxian West, Mizhi, Yichuan–Huangling, Yulin, and Wushenqi–Hengshan are coal-rock gas prospects for the coal seam #5 of the Shanxi Formation, which are expected to become new areas for increased gas reserves and production.

Real-time analysis of anodic mixed gas generated on carbon electrodes during TiO reduction in a LiCl-based salt at 650 °C

The anode gas components produced during the electrolytic reduction of TiO was analyzed in this study in real time using a carbon anode in LiCl containing various Li2O and Li2CO3 concentrations under high-potential operation at 650 °C. A molten salt with 0.3 wt.% Li2O under 6 V cell voltage predominantly generated CO2 until depletion of the initial oxygen ion source, after which Cl2 gas began to form. A molten salt containing 0.2 and 1.3 wt.% Li2O and 1.3 wt.% Li2CO3, respectively, also generated CO2 as the main anode gas, followed by CO, O2, and Cl2 gas generation. In contrast, a molten salt with 0.8 and 0.5 wt.% Li2O and Li2CO3, respectively, initially generated CO, leading to carbonate accumulation, which gradually decreased as the concentration of generated CO2 increased and it became the dominant gas, while that of O2 remained constant (6–9%). Cl2 was predominantly generated upon depletion of the oxygen ion source in the salt. Cl2 reacted with carbonate ions in the salt, thus releasing CO2 gas and preventing carbonate accumulation in the salt. This study revealed that anode gas composition during electrolytic reduction with carbon anodes is critically influenced by the oxygen ion source concentration of the salt.

Enhanced performance of cyclone separator through coupling of centrifugal force, electrostatic force and particle pre-charge

The electrostatic enhancement can effectively improve the performance of cyclone separator at low load or high-temperature, but its application is limited owing to the reduction of spark voltage in high-temperature. Aiming at this question, a new technology coupling centrifugal force, electrostatic force and particle pre-charge was proposed. The characteristics of particles charging and agglomeration were analyzed, and the influence of different factors on the change of particle partition number concentration and total removal efficiency of cyclone separator were studied. The results showed that, increasing the charge generator voltage and decreasing the main pipe gas velocity can increase the particles charge quantity and improve agglomeration, which is benefit for the efficiency improvement of either cyclone separator or electrostatic cyclone separator, especially at low inlet gas velocity. Higher charge generator voltage and lower inlet gas velocity, more obvious efficiency improvement. The total removal efficiency can be increased by up to 10 % and 9 % respectively for the cyclone separator and electrostatic cyclone separator because of particle pre-charge at 10 m/s of inlet gas velocity, and the removal efficiency of fine particles can also be effectively improved. Comparing with the electrostatic cyclone separator, achieving the same total removal efficiency, the internal voltage can be reduced 16 kV through particle pre-charge. The electrostatic force and centrifugal force were the main factor of the small particles and big particles removal, respectively.

Predictive modeling of flow characteristics in supersonic separators using machine learning

In the pursuit of cleaner energy sources, pre-processing fuel streams is crucial before distribution. Challenges arise during this process, leading to operational issues and diminished transmission efficiency. Among different technologies, supersonic separators are the ones that separate undesired components from the main gas stream more effectively. Precise forecasting of nozzle flow rate and shockwave location at a low cost can markedly enhance the efficiency of manufacturing and rating. In this research, the one-dimensional method has been developed to solve flow equations simultaneously by implementing equations of state. CFD has been used for the verification of the developed model, and the effect of different equations of state is investigated. Results show that the one-dimensional model significantly reduces the calculation time. Different EOSs result in up to 2.0 % and 3.5 % variation in the prediction of shock location and the mass flow rate, respectively.A machine learning methodology is employed to predict the location of shockwaves and the choked flow rate at an even lower cost. A dataset of 160 entries, generated using Peng Robinson's EOS, serves as the basis for this analysis. Prediction tasks are executed using Random Forest, k-nearest Neighbors, and Multilayer Perceptron models. While all three models demonstrate proficiency in data interpolation with R2 scores up to 0.9962 and 0.9951 for the shockwave location and mass flow rate, respectively, discerning their performance in extrapolation appears contingent on the specific case. In the case of extrapolation, Multilayer Perceptron and k-Nearest Neighbors show better match to one-dimensional results.

Анализ влияния нарушений требований безопасности на возникновение происшествий на предприятиях магистрального транспорта газа

The procedure of behavioral safety audit has successfully established itself in the practices of Russian and international companies in various industrial sectors. When conducting a behavioral safety audit, an auditor compares the observed conditions and employee’s actions with the established classifier based on the behavioral safety audit results report. In order to determine the relationship between hazardous actions of employees and dangerous conditions at their workplaces with the potential severity of accident consequences, a retrospective analysis has been conducted for the study, where the root causes of 411 accidents that occurred at main gas transportation enterprises have been compared with violations of safety requirements using 33 criteria of the behavioral safety audit. During the discriminant analysis, canonical discriminant functions and centroids have been determined, the coefficient of canonical correlation and the values of Wilks' lambda criterion and F-criterion have been calculated, and standardized and structural coefficients have been identified. As a result of the study, 10 criteria of the classifier of the behavioral safety audit have been detected, whose violation significantly affects the determination of the potential severity of accidents; the degree and conditions of such impact within the context of the examined selection have been established and substantiated.

Optimization of combined algorithms control electric drives of installations natural gas cooling

The relevance of the problem of reducing energy consumption by electric drives of natural gas cooling units at compressor stations of main gas pipelines is substantiated. The possibility of solving this problem with the help of a combined control system containing two groups of gas air cooling devices is considered: with continuously and discretely controlled speed of electric fan drives. An algorithm for control that is optimal according to the criterion of maximum power savings is obtained, taking into account the peculiarities of temperature distribution along the length of the heat exchanger of the cooling apparatus. It is shown that under conditions of restrictions on control actions, the optimal control algorithm consists of several intervals. Relationships were obtained for calculating the optimal speed of electric fan drives of the first group, the number of switched on electric fan drives of devices of the second group, and power savings at individual control intervals. The influence of the number of devices with continuous fan speed control on the amount of power savings was assessed. The possibility of using a simplified methodology for assessing energy savings based on average indicators of the operating mode of a cooling installation is discussed.

Oolitic Sedimentary Characteristics of the Upper Paleozoic Bauxite Series in the Eastern Ordos Basin and Its Significance for Oil and Gas Reservoirs

In recent years, great breakthroughs have been made in gas explorations of the Upper Paleozoic bauxite series in the Longdong area of the Ordos Basin, challenging the understanding that bauxite is not an effective reservoir. Moreover, studying the reservoir characteristics of bauxite is crucial for oil and gas exploration. Taking the bauxite series in the Longdong area as an example, this study systematically collects data from previous publications and analyzes the petrology, mineralogy, oolitic micro-morphology, chemical composition, and other sedimentary characteristics of the bauxite series in the study area using field outcrops, core observations, rock slices, cast slices, X-ray diffraction analysis, scanning electron microscopy and energy spectra, and so on. In this study, the oolitic microscopic characteristics of the bauxite reservoir and the significance of oil and gas reservoirs are described. The results show that the main minerals in the bauxite reservoir are boehmite and clay minerals composed of 73.5–96.5% boehmite, with an average of 90.82%. The rocks are mainly bauxitic mudstone and bauxite. A large number of oolites are observable in the bauxite series, and corrosion pores and intercrystalline pores about 8–20 μm in size have generally developed. These pores are important storage spaces in the reservoir. The brittleness index of the bauxite series was found to be as high as 99.3%, which is conducive to subsequent mining and fracturing. The main gas source rocks of oolitic bauxite rock and the Paleozoic gas series are the coal measure source rocks of the Upper Paleozoic. The oolitic bauxite reservoirs in the study area generally have obvious gas content, but the continuity of the planar distribution of the bauxite reservoirs is poor, providing a scientific basis for studying bauxite reservoirs and improving the exploratory effects of bauxite gas reservoirs.

Odor emission pattern of the waste storage workshop of kitchen waste treatment plant and control strategy study with CFD simulation.

Odor emission has become a great issue for kitchen waste management plants. Among all, unorganized emission source such as waste storage tank is the key cause. It is necessary to understand the odor emission characteristics and provide a proper control solution. In this study, a typical kitchen waste treatment plant located in Guangdong Province of China was selected to investigate the odor emission characteristics. According to the survey, the main complaint due to odor emission is on waste storage workshop. Hence, its odor emission has been investigated in this study. The gas samples were collected from the workshop in different season. According to the results, the odor emission during summer is the worst. In total, 105 odorous gases were detected from the waste storage workshop. The main odorous gases can be categorized into sulfur compounds, oxygen-containing organic compounds and terpenes. In specific, ethanol, acetic acid, methylmercaptan, α-pinene, methioether and limonene were the major odorous pollutants. Based on grey correlation, principal component analysis (PCA) and step-up regression analysis, methylmercaptan contributes the most to the odor concentration. It suggests that the odor emission control should pay more attention on methylmercaptan. The Computational Fluid Dynamics (CFD) stimulation was employed to investigate the odor distribution with applying air blowing as a curtain to separate the inside and outside atmosphere or suction to vacuum the inside air to prevent the odor emission. It was found that it could efficiently prevent odor emission by setting a 45° inclined air suction port at the top of the entrance gate. The study provides a theoretical basis on odor control for the waste storage workshop of kitchen waste management plants.