Maintenance, Reliability and Condition Monitoring
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Vibration characteristics and seismic performance of historical buildings with brick-wood structures
Get PDFTo explore the vibration characteristics and seismic performance of historical buildings in Tianjin, we conducted on-site vibration testing under ambient vibration on three historical buildings with brick-wood structures in Tianjin. Specifically, we delved into the vibration characteristics and seismic performance of historic buildings with brick-wood structures by establishing the vibration analysis model, performing the theoretical calculations, and conducting seismic performance analysis. The results reveal that 1) the vibration frequencies of historical buildings with brick-wood structures are low, mainly concentrated in 2.0-8.0 Hz, which conforms to the vibration range of general buildings; 2) based on vibration analysis, it is concluded that the structural integrity of these buildings is good and there are no obvious structural defects; 3) the layout and storey height of historical buildings have great impacts on the vibration characteristics and seismic performance. 4) the comprehensive seismic capacity index of three buildings ranges from 0.91 to 1.75. The results of dynamic analysis under ambient vibration are consistent with those of theoretical analysis, providing a basis for preserving and reinforcing historical buildings
Research on road damage recognition and classification based on improved VGG-19
Get PDFIn recent years, methods of road damage detection, recognition and classification have achieved remarkable results, but there are still problems of efficient and accurate damage detection, recognition and classification. In order to solve this problem, this paper proposes a road damage VGG-19 model construction method that can be used for road damage detection. The road damage image is processed by digital image processing technology (DIP), and then combined with the improved VGG-19 network model to study the method of improving the recognition speed and accuracy of VGG-19 road damage model. Based on the performance evaluation index of neural network model, the feasibility of the improved VGG-19 method is verified. The results show that compared with the traditional VGG-19 model, the road damage VGG-19 road damage recognition model proposed in this paper shortens the training time by 79 % and the average test time by 68 %. In the performance evaluation of the neural network model, the comprehensive performance index is improved by 2.4 % compared with the traditional VGG-19 network model. The research is helpful to improve the model performance of VGG-19 road damage identification network model and its fit to road damages
Decarbonisation options of existing thermal power plant burning natural gas
Get PDFNowadays power industry faces deepest crises ever with unprecedented prices shocks and climate challenges at the same time. From one hand we realise the need of energy transformation of power industry towards more sustainable future with climate neutral technologies. From the other hand it become obvious that this change could not happen immediately and transition period is needed with some fossil fuel technology still playing an important role as a back-up for renewable energy sources. The biggest question what is the best and cost-efficient way to decarbonise existing thermal power generation. We try to address it on the example of existing combined cycle gas turbine (CCGT) power plant fuelled by natural gas. Clearly the following possible options were identified: 1) replacement of natural gas with alternative gases, such as green hydrogen, bio or synthetic methane, 2) carbon capture and underground storage (CCS) in geological formations, 3) carbon capture, liquefaction and export, 4) carbon capture and utilisation (CCU). US giant General Electric in its publication “Decarbonizing gas turbines through carbon capture” is considering similar options for decarbonising of gas turbines. They divide it into two approaches: 1) pre-combustion by using a zero or carbon neutral fuels, such as hydrogen, synthetic methane, biofuels or ammonia and 2) post-combustion by removing carbon from the plant exhaust, using liquid or solid sorbents or oxy-fuel cycles. In this publication we try to compare these different options, despite they are not clearly comparable. For the analysis we take natural gas fired CCGT plant Riga TPP-2 in Latvia with installed capacity of 881 MW (in condensing mode)
Studying the impact of reservoir temperature, water salinity and CO2 dryness on CO2 injectivity during geological CO2 sequestration
Get PDFCarbon capture and storage (CCS) is proved to be effective measure for reducing CO2 emissions. whilst the world still highly depends on the use of fossil fuel energy, this method is necessary for reaching the world’s 1.5 °C goal. Saline aquifers among all possible underground formations are most common targeted ones for CO2 storage due to their frequent presence, and large storage capacity. However, this storage option suffers from sufficient well injectivity to inject large volumes of CO2 at acceptable rates through a minimum number of wells. The injectivity impairment/reinforcement happens through mineral dissolution, fine particle movement, salt precipitation and hydrate formation (known so far). Each of these mechanisms will be more dominant in injectivity alteration at different distance from the injection point depending on reservoir pressure and temperature, formation water salinity, rock mineralogy, and flow rate of CO2 injection as well as its dryness. In this study we have chosen a commercial software Eclipse 300 together with an open-source code to investigate the impact of formation characteristics, CO2 -Brine-Rock interaction, pressure, temperature as well as injection rate on injectivity alteration. The goal for this work is to provide a workflow which can help predicting injectivity alteration using the existing tools. Simulation results show that permeability is affected severely by salt precipitation during CO2 injection. Combined static and dynamic parameter study demonstrate that the injection rate plays a crucial role in size and expansion of CO2 plume as well as growth rate of dry out zone length, amount of salt precipitation and length of equilibrium region. The higher the injection rate, the quicker activation of the capillary and gravity force which leads to drag more brine to near well-bore resulting in higher volume fraction of salt precipitation. However, low injection rate could result in smaller CO2 plume, shorter dry out zone and longer equilibrium region in term of distance from injection point. Thus, optimizing the injection rate regarding reservoir parameters i.e., temperature, pressure and in-situ salinity, will lead to higher storage capacity as well as well performance and maintenance
Perspectives of the offshore CCS development in the polish EEZ on a Baltic Sea: insights from ongoing preliminary research for pilot CO2 injection
Get PDFThe key to effectively combatting progressive climate change lies in promptly reducing greenhouse gas (GHG) emissions, particularly carbon dioxide (CO2), whose concentration continues to rise due to human activities. The European Union (EU) has established legally binding targets, including achieving climate neutrality by 2050, with an intermediate goal of reducing GHG emissions by 55 % by 2030 compared to 1990 levels. Poland, one of the major CO2 emitters in Europe, also possesses significant storage potential in terms of projected CO2 capacity within its sedimentary basins. Considering this, the implementation of Carbon Capture and Storage (CCS) technology could play a crucial role in Poland's efforts to decarbonize its economy. For several years, the Oil and Gas Institute – National Research Institute (INiG – PIB) has been at the forefront of domestic research activities concerning underground CO2 injection. The involvement dates back to 1996 by pioneering the development of a concept, design, and implementation of one of Europe's earliest industrial installations for reinjecting acid gas, consisting of approximately 80 % CO2 and 20 % H2S, into the reservoir water underlying a productive natural gas field. This facility in Borzęcin operated by PGNiG (now part of ORLEN GROUP), is a unique testing ground where the injection process has been running continuously for 27 years. The research conducted at INiG – PIB has played an important role in identifying appropriate geological structures in Poland with a total storage capacity of 10-15 Gt CO2. Around 90-93 % of the CO2 storage capacity is found in saline aquifers, with a significant portion of approximately 7-10 % identified within mature hydrocarbon fields. Despite recent progress in managing industrial CO2 emissions, the peace of CCS development falls short of meeting the objectives set by the Paris Agreement. The main hindrance lies in the absence of a suitable regulatory framework for CO2 transport and storage infrastructure. Recognizing this challenge, the national offshore operator, Lotos Petrobaltic (LPB), presented in 2021 a Green Paper on CCS development in Poland. This document outlines a set of recommendations for legislative alternations to facilitate the initiation of large-scale, commercial CCS projects within the country. Given the current national regulations and assumptions regarding low social barriers, the most expeditious approach to implementing a First-of-a-Kind (FOAK) large-scale CCS project in Poland seems to involve deploying depleted hydrocarbon reservoirs located at the Polish Exclusive Economic Zone (EEZ) within the Baltic Sea. The LPB, with research and scientific support from INiG – PIB, has launched a program aimed at conducting a preliminary assessment of CO2 injection in Middle Cambrian sandstones. The project is scheduled to begin with a pilot injection into the well-identified, depleted structure of the B3 oil reservoir. Subsequently, it may be expanded to include adjacent hydrocarbon reservoirs and could ultimately encompass the entire Cambrian aquifer. The Cambrian aquifer is characterized by complex tectonics, comprising several blocks separated by fault zones. These fault zones may act as barriers to the propagation of reservoir fluids, as demonstrated by the presence of hydrocarbon traps in the vicinity of some fault zones. The B3 oil field, covering an area of 36,2 km2, is an elongated SW-NE, asymmetric anticline, cut on the west side by an inverted fault zone. The reservoir interval, with an average depth of 1450 meters below sea level comprises of sandstones of the Paradoxides Paradoxissimus (Middle Cambrian Zone) horizon showing a monoclinal dip towards the south-east. The reservoir formation exhibits heterogeneity in both within the vertical profile and the horizontal direction, characterized by a wide range of petrophysical parameters values. According to preliminary assessments, the CO2 storage capacity of the B3 site is estimated to be around 7 Mt CO2. The expansion of CO2 storage to the remaining hydrocarbon fields and the overarching Cambrian aquifer megastructure could potentially increase the total storage capacity to more than 150 Mt. The envisioned CO2 sources include emitters from the chemical industry, where CO2 is a by-product of the fertilizer production process. During the project’s pilot phase, the predicted CO2 injection rate is expected to be between 25-50 kt CO2 per year. As the project transitions to the upscaled phase, the injection rate is projected to increase significantly, reaching approximately 2 Mt CO2 per year. The transportation of CO2 for full-scale injection is planned through multimodal means, considering potential synergies with the multimodal CO2 Terminal in Gdansk, which is being planned under the ECO2CEE project (formerly EU CCS Interconnector). A pipeline connection between the offshore storage area and the CO2 Terminal is under consideration. The main research problems addressed within the INiG – PIB and LPB joint initiative include determining the sequestration potential of the Cm2pp aquifer, assessing the feasibility of the CO2-EOR process, recognizing the effects of injected CO2/reservoir rock/caprock interactions on injectivity, geomechanical parameters, and sealing integrity, as well as investigating CO2-induced corrosion of steel components in the transport and injection plant
Experimental tests and modeling of H2S-CO2-brine systems – a case study
Get PDFA geochemical study aimed to determine the impact of CO2 and H2S, mixtures on the representative formation rocks from the Dębowiec Fm. and Paralic series of the Upper Silesian Coal Basin, and the adjacent Małopolska Block (Poland) was performed. In the way of experiments and hydrochemical modeling the following goals were achieved: determination of the impact of acid gases on the mineralogical composition and porosity, and the assessment of mineral trapping capacity of cap rocks. Dissolution of skeletal grains, as the dominant process (the most distinct in carbonates and chlorite) was determined by means of SEM analysis in all of the samples. The increase in porosity at the injection stage, depending on the mineralogy of samples was caused by the decomposition of calcite and siderite or ankerite (Dębowiec Fm.), daphnite, clinochlore, and siderite (Paralic series) and hematite, ankerite, dolomite (Małopolska Block). After 10 000 years of simulated storage, the total porosity decreased in the cap rocks by several percent points, mainly due to precipitation of saponite, muscovite, gibbsite, phlogopite and dawsonite, in favor of the rock insulating properties. Among the secondary minerals enabling the trapping of CO2 and S in simulated storage there were observed: dolomite and pyrite (Dębowiec Fm.), dolomite, calcite and pyrite (Paralic series) and siderite, anhydrite, pyrite (Małopolska Block). Maximum calculated mineral-trapping capacity, calculated based on the results of kinetic modeling, reached 43.4 kgCO2/m3 and 44.9 kgS/m3 for CO2+ H2S co-injection into the Dębowiec Fm. Miocene rock
Laser ultrasonic excitation using graphene heat dissipation film for ultrasonic detection of seismic physical model
Get PDFWith excellent thermal conductivity and unique two-dimensional structure, the graphene heat dissipation film (GHDF) has been a potential photoacoustic (PA) material for multiple applications. In this study, we apply the GHDF into laser ultrasonic detection of seismic physical model (SPM). The PA effect of the GHDF is theoretically analyzed and experimentally demonstrated. The GHDF is physically attached to the upper surface of SPM, and excited effectively by a 532 nm pulsed laser. Distinguishable layered echo signal of SPM verifies the feasibility of the ultrasonic excitation approach using GHDF. This work opens up a new application of GHDF in ultrasonic detection of SPM
Design of highly reflective film for smart radiation device
Get PDFSmart radiation device (SRD) based on the asymmetrical Fabry-Perot cavity automatically tune its IR emittance depending on the ambient temperature, making it an ideal choice for thermal control system of spacecrafts. The low solar absorption is desirable for SRD to prevent the spacecraft from overheating by sun light. In this paper, a multilayer highly reflective film with LHk stacking layers is designed to reduce the solar absorptance (As) of the Ag/Al2O3/VO2 structured SRD. The reflective film achieves a high reflection band in ~220 nm bandwidth from 460 nm to 680 nm, which results in a reduction of the solar absorptance by 25.56 % for SRD working at low temperature and 24.27 % at high temperature as the stacking factor k= 5. The simulation results indicate that an economic reflective film with k= 3 can achieve effective suppression of As of SRD, demonstrating the promising potential of the proposed reflective film in thermal control application of spacecrafts
Nonlinear dynamic analysis and defect detection of gears
Get PDFIn the current work, the nonlinear dynamic behavior of an eight degrees of freedom gear system is investigated. Tooth crack is introduced into the model. The main sources of excitation are the time varying mesh stiffness (TVMS), time varying mesh damping, backlash and friction inter teeth. By using the potential energy method applied into the cantilevered beam, the TVMS is calculated. The backlash is considered as a dead zone. The effect of backlash, friction and tooth crack on the vibration frequencies is highlighted. The crack detection is based on the time-frequency analysis
Rehabilitation coatings-current challenges and opportunities for the future
Get PDFUnderground pipelines used for oil, gas and water distribution in Saudi Arabia and gulf region are estimated more than 33000 km in length with a range of diameters from 8 and 80 inch. Most of these pipelines are buried in different types of corrosive soil conditions and in most cases an external coating is employed along with cathodic protection (CP). Most of the existing pipelines are over 30 years old now and this is the stage to carry out rehabilitation projects for life extension of this aging infrastructure. The selection of the suitable coating systems for the rehabilitation projects is a very complicated process as it requires in depth understanding the coating/environments interactions in that particular environment along with application challenges. This paper discusses in detail the different types of external underground pipeline coating types and their selection criteria for rehabilitation projects along with recent trends and future recommendations