Search Results (55)

Currently, machine learning methods are widely applied in the power industry to solve various tasks, including short-term power consumption forecasting. However, the lack of interpretability of machine learning methods can lead to their incorrect use, potentially resulting in electrical system instability or equipment failures. This article addresses the task of short-term power consumption forecasting, one of the tasks of enhancing the energy efficiency of gas industry enterprises. In order to reduce the risks of making incorrect decisions based on the results of short-term power consumption forecasts made by machine learning methods, the SHapley Additive exPlanations method was proposed. Additionally, the application of a multi-agent approach for the decomposition of production processes using self-generation agents, energy storage agents, and consumption agents was demonstrated. It can enable the safe operation of critical infrastructure, for instance, adjusting the operation modes of self-generation units and energy-storage systems, optimizing the power consumption schedule, and reducing electricity and power costs. A comparative analysis of various algorithms for constructing decision tree ensembles was conducted to forecast power consumption by gas industry enterprises with different numbers of categorical features. The experiments demonstrated that using the developed method and production process factors reduced the MAE from 105.00 kWh (MAPE of 16.81%), obtained through expert forecasting, to 15.52 kWh (3.44%). Examples were provided of how the use of SHapley Additive exPlanation can increase the safety of the electrical system management of gas industry enterprises by improving experts’ confidence in the results of the information system. Full article

At Leibniz University of Hannover, Germany, a new turbomachinery test facility has been built over the last few years. A major part of this facility is a new 6 MW compressor station, which is connected to a large piping system, both designed and built by AERZEN. This system provides air supply to several wind tunnel and turbomachinery test rigs, e.g., axial turbines and axial compressors. These test rigs are designed to conduct high-quality aerodynamic, aeroelastic, and aeroacoustic measurements to increase physical understanding of steady and unsteady effects in turbomachines. One primary purpose of these investigations is the validation of aerodynamic and aeroacoustic numerical methods. To provide precise boundary conditions for the validation process, extremely high homogeneity of the inflow to the investigated experimental setup is imminent. Thus, customized settling chambers have been developed using analytical and numerical design methods. The authors have chosen to follow basic aerodynamic design steps, using analytical assumptions for the inlet section, the “mixing” area of a settling chamber, and the outlet nozzle in combination with state-of-the-art numerical investigations. In early 2020, the first settling chamber was brought into operation for the acceptance tests. In order to collect high-resolution flow field data during the tests, Leibniz University and AERZEN have designed a unique measurement device for robust and fast in-line flow field measurements. For this measurement device, total pressure and total-temperature rake probes, as well as traversing multi-hole probes, have been used in combination to receive high-resolution flow field data at the outlet section of the settling chamber. The paper provides information about the design process of the settling chamber, the developed measurement device, and measurement data gained from the acceptance tests. Full article

During the energy transition period and the increased supply of developed land, an analysis was conducted on the economic viability of transforming post-mining buildings. This study sought to answer the following questions: Does the circular economy create new conditions for adapting these specific industrial facilities? Should mining buildings be adapted or should they be demolished and built anew? The objectives of the article were to perform a comparative analysis (financial, environmental, and social) of these alternatives and to develop a decision-making model for managing obsolete mining facilities using circular economy principles. Decision-making regarding mining buildings should occur as part of revitalising post-mining areas. Consequently, the method used was research through design followed by comparative analyses: financial, environmental, and social. As a result, the study demonstrated the potential for adapting buildings on a defunct mining site, mainly compressor and fan station. The financial, environmental, and social profitability of investing in the adaptive reuse of historic buildings was established. The entire process was encapsulated in a universal decision-making model. The analytical results presented in the article indicate that mining buildings represent a significant resource in a circular economy and their adaptation should be prioritised. Full article

The problem of increasing heat resistance and corrosion and erosion resistance of gas turbine units in compressor stations was solved through the development of new layered materials containing nanostructured grains. The authors carried out a destruction analysis of gas turbine units in compressor stations. It was shown that after 10–30,000 h of operation, the greatest damage occurred when the gas turbine operated in dusty environments at high temperatures (or in air environments with a high salt content). The developed layered composites include the thermal barrier and functional reinforced nanostructured layers consisting of refractory carbides and oxides. This paper describes the destruction mechanism of gas turbine units under the influence of high-temperature aggressive environments. As a result, a new formation technology for reinforced nanostructured layered composites has been developed. The developed composition makes it possible to increase the heat resistance of materials by approximately 10 times. This significantly increases the reliability and durability of gas turbine units in compressor stations. The structural and mechanical parameters of the layered nanostructured heat-resistant composites have been studied. Full article

The growing importance of hydrogen as an energy carrier in a future decarbonised energy system has led to a surge in its production plans. However, the development of infrastructure for hydrogen delivery, particularly in the hard-to-abate sectors, remains a significant challenge. While constructing new pipelines entails substantial investment, repurposing existing pipelines offers a cost-effective approach to jump-starting hydrogen networks. Many European countries and, more recently, other regions are exploring the possibility of utilising their current pipeline infrastructure for hydrogen transport. Despite the recent efforts to enhance the understanding of pipeline compatibility and integrity for hydrogen transportation, including issues such as embrittlement, blend ratios, safety concerns, compressor optimisation, and corrosion in distribution networks, there has been limited or no focus on pipeline expansion options to address the low-energy density of hydrogen blends and associated costs. This study, therefore, aims to explore expansion options for existing natural gas high-pressure pipelines through additional compression or looping. It seeks to analyse the corresponding cost implications to achieve an affordable and sustainable hydrogen economy by investigating the utilisation of existing natural gas pipeline infrastructure for hydrogen transportation as a cost-saving measure. It explores two expansion strategies, namely pipeline looping (also known as pipeline reinforcement) and compression, for repurposing a segment of a 342 km × 36 inch existing pipeline, from the Escravos–Lagos gas pipeline system (ELPS) in Nigeria, for hydrogen transport. Employing the Promax^® process simulator tool, the study assesses compliance with the API RP 14E and ASME B31.12 standards for hydrogen and hydrogen–methane blends. Both expansion strategies demonstrate acceptable velocity and pressure drop characteristics for hydrogen blends of up to 40%. Additionally, the increase in hydrogen content leads to heightened compression power requirements until approximately 80% hydrogen in the blends for compression and a corresponding extension in looping length until around 80% hydrogen in the blend for looping. Moreover, the compression option is more economically viable for all investigated proportions of hydrogen blends for the PS1–PS5 segment of the Escravos–Lagos gas pipeline case study. The percentage price differentials between the two expansion strategies reach as high as 495% for a 20% hydrogen proportion in the blend. This study offers valuable insights into the technical and economic implications of repurposing existing natural gas infrastructure for hydrogen transportation. Full article

Nowadays, with the need for clean and sustainable energy at its historical peak, new equipment, strategies, and methods have to be developed to reduce environmental pollution. Drastic steps and measures have already been taken on a global scale. Renewable energy sources (RESs) are being installed with a growing rhythm in the power grids. Such installations and operations in power systems must also be economically viable over time to attract more investors, thus creating a cycle where green energy, e.g., green hydrogen production will be both environmentally friendly and economically beneficial. This work presents a management method for assessing wind–solar–hydrogen (H₂) energy systems. To optimize component sizing and calculate the cost of the produced H₂, the basic procedure of the whole management method includes chronological simulations and economic calculations. The proposed system consists of a wind turbine (WT), a photovoltaic (PV) unit, an electrolyzer, a compressor, a storage tank, a fuel cell (FC), and various power converters. The paper presents a case study of green hydrogen production on Sifnos Island in Greece through RES, together with a scenario where hydrogen vehicle consumption and RES production are higher during the summer months. Hydrogen stations represent H₂ demand. The proposed system is connected to the main power grid of the island to cover the load demand if the RES cannot do this. This study also includes a cost analysis due to the high investment costs. The levelized cost of energy (LCOE) and the cost of the produced H₂ are calculated, and some future simulations correlated with the main costs of the components of the proposed system are pointed out. The MATLAB language is used for all simulations. Full article

Industrial emissions of trace gases and VOCs can be an important contributor to air quality in cities. Disentangling different point sources from each other and characterizing their emissions can be particularly challenging in dense industrial areas, such as Detroit, Dearborn and surrounding areas in Southeast Michigan (SEMI). Here, we leverage mobile measurements of trace gases and speciated volatile organic compounds (VOCs) to identify emitting sites. We characterize their complicated emissions fingerprints based on a core set of chemical ratios. We report chemical ratios for 7 source types including automakers, steel manufacturers, chemical refineries, industrial chemical use (cleaning; coatings; etc.), chemical waste sites, compressor stations, and more. The source dataset includes visits to over 85 distinct point sources. As expected, we find similarities between the different types of facilities, but observe variability between them and even at individual facilities day-to-day. Certain larger sites are better thought of as a collection of individual point sources. These results demonstrate the power of mobile laboratories over stationary sampling in dense industrial areas. Full article

Pipeline transportation is widely regarded as the most cost-effective method for conveying substantial volumes of hydrogen across extensive distances. However, before hydrogen can be widely used, a new pipeline network must be built to reliably supply industrial users. An alternative way to rather expensive investments in new infrastructure could be to use the existing pipeline network to add pure hydrogen to natural gas and further transport the gas mixture in an industrially safe way. The new solution necessities will be examined for compression, transportation, and fire hazard accidents, which have not been scrutinized by other scholars. This study presents the results of a comprehensive analysis of the methane–hydrogen mixture compression process and a mathematical description of the main pipeline operation during gas mixture transportation, considering industrial fire safety issues. By examining a case study involving a main gas pipeline and its associated mathematical model for hydrogen transportation, it becomes feasible to assess the potential hazards associated with various leakage areas and the subsequent occurrence of fires. The findings of this investigation demonstrate that the spontaneous combustion of hydrogen due to leakage from a natural gas pipeline is directly influenced by the proportion of hydrogen present in the gas mixture. If the hydrogen percentage reaches a balanced ratio of 50–50%, it is plausible that the equipment at the compressor station could be subject to detrimental consequences, potentially leading to accidents and fires. Furthermore, the obtained results from modeling in ANSYS Fluent software propose two practical scenarios, which demonstrate that despite the limited research conducted on the safety aspects and the occurrence of fires during the operation of hydrogen gas pipelines, industrial and fire safety necessitate the inclusion of hydrogen transport infrastructure as a pivotal element within the broader framework of hydrogen infrastructure development. Full article

This paper presents a comparative analysis of two hydrogen station configurations during the refueling process: the conventional “directly pressurized refueling process” and the innovative “cascade refueling process.” The objective of the cascade process is to refuel vehicles without the need for booster compressors. The experiments were conducted at the Hydrogen Research and Fueling Facility located at California State University, Los Angeles. In the cascade refueling process, the facility buffer tanks were utilized as high-pressure storage, enabling the refueling operation. Three different scenarios were tested: one involving the cascade refueling process and two involving compressor-driven refueling processes. On average, each refueling event delivered 1.6 kg of hydrogen. Although the cascade refueling process using the high-pressure buffer tanks did not achieve the pressure target, it resulted in a notable improvement in the nozzle outlet temperature trend, reducing it by approximately 8 °C. Moreover, the overall hydrogen chiller load for the two directly pressurized refuelings was 66 Wh/kg and 62 Wh/kg, respectively, whereas the cascading process only required 55 Wh/kg. This represents a 20% and 12% reduction in energy consumption compared to the scenarios involving booster compressors during fueling. The observed refueling range of 150–350 bar showed that the cascade process consistently required 12–20% less energy for hydrogen chilling. Additionally, the nozzle outlet temperature demonstrated an approximate 8 °C improvement within this pressure range. These findings indicate that further improvements can be expected in the high-pressure region, specifically above 350 bar. This research suggests the potential for significant improvements in the high-pressure range, emphasizing the viability of the cascade refueling process as a promising alternative to the direct compression approach. Full article

The development of shale gas reservoirs often involves the utilization of horizontal well segmental multi-stage fracturing techniques. However, these reservoirs face challenges, such as rapid initial wellhead pressure and production decline, leading to extended periods of low-pressure production. To address these issues and enhance the production during the low-pressure stage, pressurized mining is considered as an effective measure. Determining the appropriate pressurization target and method for the shale gas wells is of great practical significance for ensuring stable production in shale gas fields. This study takes into account the current development status of shale gas fields and proposes a three-stage pressurization process. The process involves primary supercharging at the center station of the block, secondary supercharging at the gas collecting station, and the introduction of a small booster device located behind the platform separator and in front of the outbound valve group. By incorporating a compressor, the wellhead pressure can be reduced to 0.4 MPa, resulting in a daily output of 12,000 to 14,000 cubic meters from the platform. Using a critical liquid-carrying model for shale gas horizontal wells, this study demonstrates that reducing the wellhead pressure decreases the critical flow of liquid, thereby facilitating the discharge of the accumulated fluid from the gas well. Additionally, the formation pressure of shale gas wells is estimated using the mass balance method. This study calculates the cumulative production of different IPR curves based on the formation pressure. It develops a dynamic production decline model for gas outlet wells and establishes a relationship between the pressure depletion of gas reservoirs and the cumulative gas production before and after pressurization of H10 −2 and H10 −3 wells. The final estimated ultimate recovery of two wells is calculated. In conclusion, the implementation of multi-stage pressurization, as proposed in this study, effectively enhances the production of, and holds practical significance for, stable development of shale gas fields. Full article

The inadequate ability to dissipate heat of the gas head cover of the diaphragm compressor will result in its excessive temperature, which will put the operation of the hydrogen filling station at risk for safety issues and raise operating costs. This paper analyzed the structure and the heat transfer characteristics of the gas head cover, along with the relevant heat transfer boundaries, based on which a finite element simulation model of the temperature distribution was established. A test rig for the temperature test of a 22 MPa diaphragm compressor was built to validate this simulation model. The results indicated that the simulated temperatures agree well with the measured values, and the deviation is within 9.1%. Further, this paper proposed two head cover structures for enhancing the heat transfer according to the temperature field distribution characteristics, and the simulation and experimental verification were carried out, respectively. The findings demonstrate that the method of enhancing heat transfer around the centre area is more effective, reducing the highest temperature by 14.1 °C, because it greatly lowers thermal conduction resistance, which is the principal impediment to the heat dissipation of the gas head cover. Full article

The linear accelerator system of the PBP-CMU Electron Linac Laboratory has been designed with the aim of generating free-electron lasers (FELs) in the mid-infrared (MIR) and terahertz (THz) regions. The quality of the radiation is strongly dependent on the properties of the electron beam. Among the important beam parameters, the electron beam energy and energy spread are particularly important. To accurately measure the electron beam energy, the first dipole magnet in the bunch compressor system and the downstream screen station are employed as an energy spectrometer. The A Space Charge Tracking Algorithm (ASTRA) software is used for the design and optimization of this system. Simulation results demonstrate that the developed spectrometer is capable of accurately measuring the energy within the 5–25 MeV range. The screen station system is designed and constructed to have the ability to capture a beam size with a resolution of 0.1 mm per pixel. This resolution is achieved with a screen-to-camera distance of 1.2 m, which proves sufficient for precise energy measurement. The systematic error in energy measurement is found to be less than 10%, with a minimum energy spread of 0.4% achievable when the horizontal beam size remains below 3 mm. Full article

This study focused on exergo–conomic and parametric analysis for Taji station in Baghdad. This station was chosen to reduce the emission of waste gases that pollute the environment, as it is located in a residential area, and to increase the production of electric power, since for a long time, Iraq has been a country that has suffered from a shortage of electricity. The main objective of this work is to integrate the Taji gas turbine’s power plant, which is in Baghdad, with the Rankine cycle and organic Rankine cycle to verify waste heat recovery to produce extra electricity and reduce emissions into the environment. Thermodynamic and exergoeconomic assessment of the combined Brayton cycle–Rankine cycle/Organic Rankin cycle (GSO CC) system, considering the three objective functions of the First- and Second-Law efficiencies and the total cost rates of the system, were applied. According to the findings, 258.2 MW of power is produced from the GSO CC system, whereas 167.3 MW of power is created for the Brayton cycle (BC) under the optimum operating conditions. It was demonstrated that the overall energy and exergy efficiencies, respectively, are 44.37% and 42.84% for the GSO CC system, while they are 28.74% and 27.75%, respectively, for the Brayton cycle. The findings indicate that the combustion chamber has the highest exergy degradation rate. The exergo–economic factor for the entire cycle is 37%, demonstrating that the cost of exergy destruction exceeds the cost of capital investment. Moreover, the cost of the energy produced by the GSO CC system is USD 9.03/MWh, whereas it is USD 8.24/MWh for BC. The results also indicate that the network of the GSO CC system decreases as the pressure ratio increases. Nonetheless, the GSO CC system’s efficiencies and costs increase with a rise in the pressure ratio until they reach a maximum and then decrease with further pressure ratio increases. The increase in the gas turbine inlet temperature and isentropic efficiency of the air compressor and gas turbine enhances the thermodynamic performance of the system; however, a further increase in these parameters increases the overall cost rates. Full article

Compressed natural gas (CNG) main stations are critical components of the urban energy infrastructure for CNG distribution. Due to its high electrification and significant power consumption, researching the economic operation of the CNG main station in demand response (DR)-based electricity pricing environments is crucial. In this paper, the dehydration process is considered in the CNG main station energy consumption model to enhance its participation in DR. A bilevel economic dispatch model for the CNG main station is proposed, considering critical peak pricing. The upper-level and lower-level models represent the energy cost minimization problems of the pre-system and rear-system, respectively, with safety operation constraints. The bilevel programming model is solved using a genetic algorithm combined with a bilevel programming method, which has better efficiency and convergence. The proposed optimization scheme has better control performance and stability, reduces the daily electricity cost by approximately 21.04%, and decreases the compressor switching frequency by 50.00% without changing the CNG filling demand, thus significantly extending the compressor’s service life. Moreover, the average comprehensive power cost of processing one unit of CNG reduces 20.62%. Full article

A new electrically driven gas booster is described as an alternative to the classical air-driven gas boosters known for their poor energetic efficiency. These boosters are used in small scale Hydrogen storage facilities and in refueling stations for Hydrogen vehicles. In such applications the overall energy count is of significance and must include the efficiency of the compression stage. The proposed system uses an electric motor instead of the pneumatic actuator and increases the total efficiency of the compression process. Two mechanical principles are studied for the transformation of the rotational motion of the motor to the linear displacement of the compressor pistons. The strongly fluctuating power of the compressor is smoothed by an active capacitive auxiliary storage device connected to the DC circuit of the power converter. The proposed system has been verified by numeric simulation, including the thermodynamic phenomena, the kinetics of the new compressor drive and the the operation of the circuits of the power smoothing system. Full article