City Gate Research Articles

Research on multi-energy coupled preheating system of city gate station based on Modelica simulation

Natural gas depressurization at city gate stations can cause hydrate formation, necessitating preheating before pressure regulation. To reduce the high energy consumption of traditional city gate station preheating processes, this study introduces four novel multi-energy coupled systems: photovoltaic-air source heat pump (PV-ASHP), solar thermal-combined heat and power-ASHP (ST-CHP-ASHP), CHP-ASHP, and ASHP system, with a typical city gate station in Shanghai taken as the research case. Dynamic energy simulation systems were developed in Dymola software to evaluate the proposed systems from energy, environmental, and economic perspectives, conducting a comparison with conventional boiler preheating systems, including sensitivity analysis of energy prices on system economics. Results indicate PV-ASHP has the lowest annual total cost (ATC) and shortest discounted payback period, while ATC values for ST-CHP-ASHP, CHP-ASHP, and ASHP increase by 6.4 %, 9.6 %, and 12.6 %, respectively. ST-CHP-ASHP and PV-ASHP demonstrate advantages in primary energy rate and carbon emissions, with ST-CHP-ASHP performing slightly better than PV-ASHP. Currently, PV-ASHP demonstrates the highest development potential. If photovoltaic feed-in tariffs remain constant, and natural gas prices decrease by over 12.5 % or CHP feed-in tariffs increase by over 38.4 %, ST-CHP-ASHP becomes more economically viable. This research provides valuable insights for retrofitting China's existing city gate station preheating systems.

A risk assessment of a gas pressure reduction station system with confidence for dealing with imprecisions and unknowns

Process systems are sensitive and vital industrial facilities. Disturbances in their performance may cause harm to the environment,humans,or significant economic damage. In risk assessment of chemical process industries, the available data, information, and knowledge are typically rare, limited, and often unrealistic. This issue poses a challenge to conducting a credible quantitative risk assessment and effects the robustness of the results. To address these challenges, this work proposes a methodology based on the Dempster-Shafer theory of evidence as the reasoning framework. It incorporates risk identification, analysis, and mitigation phases to ensure a thorough analysis of risks and the integration of proactive risk reduction strategies. The approach aims to model the worst-case hazard scenario and assess associated risks using various methods such as FMECA, Bow-Tie, Credal Network, and Dempster-Shafer theory. The proposed approach models imprecision and data ambiguity using intervals and associated belief mass. This extension provides a basis for addressing the fundamental problem of prior ignorance about the distribution of the observed data, which is prevalent in data mining applications. A new approach is proposed that utilizes Belief and Plausibility curves, similar to a Cumulative Distribution Function, to propagate uncertainty, enhance criticality discrimination, and determine cumulated belief measures. This approach is applied in analyzing the failure modes identified in FMECA and is further extended through the credal network for comprehensive risk assessment. Results show how to express irrelevant and independent judgments, and how to work out with inferences in credal networks. This issue is often overlooked, but if properly addressed it represents the key to ultimately drawing reliable conclusions and fully utilizing the system's available data. A case study of the City Gate Station system was used to verify the application potential of the proposed approach.

A novel preheating system in pressure reduction stations—natural gas directly flowing inside deep borehole heat exchangers

To prevent hydrates from forming during the pressure reduction process in natural gas pressure reduction stations (i.e., city gate stations, CGS), fuel-intensive preheating methods are normally adopted, leading to high fuel consumption and carbon emissions. In this study, an innovative preheating system for natural gas is proposed, which is called the “Direct Geothermal Heating System” (DGHS). The main idea is to inject high-pressure natural gas into geothermal wells before the throttling valve; thus, natural gas is directly heated by the surrounding strata when it flows through the geothermal well. A proper temperature for natural gas should be ensured, as natural gas goes back to the ground for pressure regulation. The idea is performed based on the preheating configuration using coaxial deep borehole heat exchangers (DBHE). A mathematical model describing the flow and heat transfer processes of DGHS through DBHE is established to study its heat transfer characteristics. Additionally, the environmental and economic benefits of the proposed configuration are also investigated. Through the CGS case in this paper, the findings indicate that, over the fifteen years of preheating with a DBHE depth of 2000 m and inlet flow rate of 4.39 × 107 Nm³/year, the outlet temperature of the throttling valve remains within the range of 17 °C–37 °C, meeting the heating requirement of CGS. Among fifteen preheating cycles, the average peak heating power of the DBHE reaches 105.78 kW. In addition, in the 15th year, the proposed system has a 1/3 cost of a traditional line heater, along with a reduction of 46.43 × 105 kg in CO2 emission. The DGHS for natural gas is easy to establish and operate; once it is promoted on a large scale, it will produce huge economic and environmental benefits.

Let's Spill the BIMs. Reflections on the Potential of BIM Applications in Archaeology

Nowadays, there is a growing interest in applying BIM (Building Information Modeling) technologies to cultural heritage and archaeological sites. These applications are at an early stage for archaeology, but relevant issues clearly arise from the adaptation of BIM, originally intended for AEC, to such a diverse field. To highlight these problems, three case studies from Veneto (Italy) have been examined: two protohistoric burial mounds in perishable material from Padua and Este, and a Roman city gate at Altinum. The paper highlights the main difficulties encountered during the elaboration process, as well as the advantages and disadvantages of using this specific tool. The aim is to reflect on the possibilities and reasons for the use of BIM in archaeology, and possibly to start a critical theoretical discussion about it.

Nonlinear seismic analysis of city gate architectural heritages using a sensitive-based model updating method

Due to the unknown accumulation of internal damage and severe degradation of structural mechanisms, updating numerical model related to current damage using Operational Modal Analysis and performing nonlinear seismic analysis pose significant challenges. In this paper, a nonlinear seismic analysis method is proposed involving a three-stage finite element model updating process. This method not only updates the global parameters and local parameters of substructure, but also updates the FEM to true current damage state based on elastic-plastic constitutive model considering current damage. First, on-site vibration and material performance tests were conducted to obtain modal data and material properties of the structure. Second, each component in the model was updated to detect damage, employing a sensitivity-based approach in Stage 1. Then, each element within the severely damaged components obtained from Stage 1 was updated for damage detection, again using a sensitivity-based approach in Stage 2. Finally, the current damage state was updated based on elastoplastic constitutive model considering the current damage and a seismic analysis was performed in Stage 3. The results indicate that, in Stage 1, updating the global parameters of the model aligns the calculated data with the measured data. In Stage 2, updating the local parameters to accurately identify the location and severity of damage within the heavily affected components is demonstrated by a simple example. These results can establish a scientific foundation for the nonlinear seismic analysis of city gate architectural heritages.

Skulpture Marije Pobjednice u gradovima tvrđavama na jugoistočnoj granici Habsburške Monarhije

The paper analyses statues of Mary the Victorious (Maria victrix, Santa Maria de Victoria, Marija Zmagovalka, Maria vom Siege, Gyözedelmes Immaculata) in the fortified cities at the south-eastern frontier of the Habsburg Monarchy, highlighting some previously unidentified examples of this iconographic type in Petrovaradin and Alba Iulia. These cities were part of a comprehensive fortification system conceived by Eugene of Savoy following Habsburg victories over the Ottomans under his leadership. The paper examines comparative graphic, painterly, and sculptural works that may have influenced the authors of these sculptures. Notably, two altarpieces by Carlo Maratta (1625–1713), executed in the 1660s for the Franciscan church of S. Isidoro Agricola in Rome and the church of S. Agostino in Siena, emerge as highly influential in this context, with numerous artworks modelled upon them. The iconographic type of Mary the Victorious depicts the joint triumph of the Virgin Mary and her Child over Evil, with Christ piercing the personification of evil at their feet with a cross-shaped spear. This paper associates this specific iconographic choice with the origin of these artworks near the Habsburg-Ottoman frontier, interpreting it as an expression of Catholic and Habsburg triumphal rhetoric and propaganda. Some examples suggest probable Jesuit influence, as they were among the primary promoters of this iconographic type. In Osijek, a city of exceptional strategic importance on the south-eastern Habsburg-Ottoman frontier, the iconographic type of Mary the Victorious is represented by two examples. The earlier, more elaborate one, tentatively dated to the 1730s, originally adorned the city gate of Osijek’s fortress Tvrđa. In 1784, together with three other statues, it was placed on the outer perimeter of the Holy Trinity monument in the centre of Tvrđa. The second Osijek example is located in the Lower Town and dated by an inscription to 1757, when it was erected as a votive statue against the plague. Two public statues of Mary the Victorious are located in Petrovaradin, the second most important fortress on the south-eastern frontier of the Habsburg Monarchy. Unlike those from Osijek, the Petrovaradin statues are not free-standing, but inserted into the façade niches of public buildings in the suburbs of the Petrovaradin fortress. The polychromous wooden statue on the building of the Šajkaš Battalion stands out for its quality, with stylistic features pointing to the early decades of the 18th century. The second statue is located in the niche of the nearby Bridge Toll Office building. It is argued that the Jesuits or the Franciscans may have selected this iconographic type, as they were the key promoters of Mary the Victorious. The statues were probably commissioned to commemorate Mary’s role in the Christian victory over the Ottomans near Petrovaradin in 1716, as their locations suggest. Mary’s role as the saintly protector against the plague, which struck the area in 1738, should also be considered. In Alba Iulia, which was the easternmost point of Eugene’s chain of fortified cities, Mary the Victorious is the central statue on the side altar in the cathedral of St Michael, constructed around 1754. In conclusion, the paper presents two examples of sculptural and painterly depictions of Mary the Victorious in the wider frontier area (Požega, Valpovo), commissioned by the Jesuits or members of the Habsburg elite, since due to specific political circumstances, they emerge as key patrons of significant artworks in this region.

Optimal design of heat pipes for city gate station heaters by applying genetic and Bayesian optimization algorithms to an artificial neural network model

This study contains a novel idea to improve the performance of city gate station heaters, using pulsating heat pipes with optimized structure. In this research, a hybrid method including Bayesian and genetic algorithms is implemented to optimize the architecture of an artificial neural network (ANN) model and find the optimal operating point for heat pipes. In the previous study, the authors have proposed a neural network-based model to predict the thermal performance of heat pipes, based on a wide range of their design parameters, including dimensions of heat pipe, number of turns, working fluid, inclination angle, filling ratio, and heat input. In the present study, the prediction model architecture is optimized using Bayesian optimization algorithm. The best performance is achieved when iterations of the employed Bayesian optimization is set to 300 iterations or samples, which 150 samples are produced to train the Bayesian model and other 150 iterations are utilized in order to find the optimal ANN structure and hyper-parameter tuning of the model. The optimal ANN model with structure of 9-97-21-68-100-1 has evaluation parameters of 0.980 and 0.014 for R2 and MSE of total dataset, respectively. The performance metrics indicate an improvement in accuracy of the ANN model with a 53.33% reduction in MSE value and a 3.15% increase in R2 score. Then, the genetic algorithm is applied to the optimal model to find the optimum operating parameters of the heat pipe. In this regard, the design parameters of the best heat pipe in order to use in the city gate station heaters, are obtained by setting the genetic algorithm population equal to 300. Finally, as a practical case study, a real heater with capacity of 10,000 SCMH which is located in Iran is selected. Considering constraints and limitations of this heater, the proposed model indicates that a vertical pulsating heat pipe with four turns which is filled 55% with water as the working fluid, has the optimal thermal resistance of 0.104 K/W. Utilizing the optimal heat pipe in the mentioned heater is a promising solution for efficiency improvement and fuel consumption and CO2 emission reduction, which decreases the operating costs of the heater as well.

Developing a bi-objective maintenance optimization model for process industries by prioritizing resilience and robustness using dynamic Bayesian networks

In this paper, we developed a new model that combines resilience concept with robust maintenance resource allocation, and team assignment strategies to evaluate system performance after disruption. This model offers insights for proactive preparation before disruptive events and facilitates optimal decision-making in the aftermath of such disruptions. Our approach involves a non-linear programming model that operates at both strategic and operational decision levels. It aims to simultaneously minimize total maintenance costs while maximizing resilience by determining the allocation of backup resources to system components before a disruption occurs and suggesting emergency maintenance team assignments post-disruption, all while adhering to resilience constraints.We quantify resilience using a dynamic Bayesian Network method and Markov process, utilizing metrics based on absorption, adaptation, and restoration performance (reliability) curves. We propose a bi-objective optimization model and leverage the genetic algorithm NSGA-III to obtain Pareto-optimal solutions. To address the inherent uncertainty of various disruption scenarios, we generate a range of possible scenarios and employ robust optimization techniques to derive solutions that can withstand these uncertainties. To demonstrate the effectiveness of our proposed model, we conduct a case study involving a City Gate Station in agas industry.

Numerical simulation and performance analysis of solar hydrogen production using anion exchange membrane electrolyzer and blending with natural gas

Hydrogen production using solar energy and blending in a natural gas pipeline is a cost-effective alternative to hydrogen storage and transmission that leads to lower CO2 emissions caused by the energy infrastructure. In this paper, energy, exergy, and Exergoeconomic analyses of a solar hydrogen production system and its blending with natural gas in a city gate station of Isfahan city are performed in three days with minimum, average, and maximum solar irradiations. The system includes photovoltaic arrays, anion exchange membrane electrolyzer cells (AEMECs), a hydrogen compressor, and a system blending. The AEMEC is used due to its less expensive catalysts, non-acidic electrolyte, and high efficiency at high pressures. A three-dimensional numerical model is developed to determine the AEMEC’s polarization curve, accurately. The results show that with increasing solar irradiation and decreasing ambient temperature, the maximum power of the PV increases and the energy and exergy efficiency of the PV decreases. By increasing the injection of hydrogen into natural gas from 1% to 10% vol., the lower heating value of the fuel and the Wobbe Index decrease by 6% and 1.55%, respectively. By injection of 10% vol. hydrogen gas into natural gas compared to the case of using natural gas without hydrogen, the exergy cost of natural gas blended with hydrogen increases by 5.9%. Considering the environmental benefits of using hydrogen in combination with natural gas, including the reduction of greenhouse gases, and the fact that blending hydrogen up to 10% vol. with natural gas does not require any change in urban gas supply facilities, this process is feasible. In the case of using high-pressure AEMEC and removing the compressor to produce hydrogen at high pressure, the exergy cost of high-pressure hydrogen reduces by 29.3%.

An active approach to heat transfer enhancement in indirect heaters of city gate stations: An experimental modeling

A major problem with gas pressure reduction stations is the very low thermal efficiency of indirect water bath heaters (IWBHs) used to prevent gas hydration. In this study, an innovative active method based on the ultrasonication technology is investigated to improve heat transfer in IWBHs. Considering the sophisticated thermos-physical phenomena involved in this problem and its complex governing equations, a laboratory-modeled ultrasonic heater is used to conduct the experiments. The results have been successfully validated using an empirical relationship. In order to evaluate the effect of ultrasonic vibrations, all the tests were done in two modes, namely without vibration and with vibrating at different ultrasonic power levels. The results show that the positive thermal impact of ultrasonic vibration on increasing the heat transfer rate is more evident at lower fluid flow rates and lower heater power levels. In the current experiments, the maximum value of ultrasonic heat transfer enhancement was evaluated as 166 % at a fluid flow rate of 0.5 LPM and a heater power of 200 W. Findings of this novel research can lead to the efficiency enhancement of existing gas pressure reduction stations and significant energy savings.

Forecasting System For Increasing Crime At The Binjai City Police Station With The Application Of The Website-Based Exponential Smoothing Method

Binjai City is the closest city to the city of Medan, which is the heart of North Sumatra. As one of the closest cities to the city gate of Medan, there are many activities that require a lot of activities. In Binjai City there is a Binjai City Police Office which is located Jl. Sultan Hasanuddin No.1, Binjai City, North Sumatra. Based on crime data at the Binjai City Police Station, it shows that crime that occurs every day is constantly increasing. This is because several factors influence it, namely internal factors within oneself such as having a realistic mindset and so on while external factors such as economic level factors or low education levels that have an impact on the difficulty of finding jobs, uneven population density, very minimal salaries, urgent needs, supportive environmental situations, social inequality trigger envy and resentment, environmental associations that require costs and so on. When people are faced with such a situation, the thing that will come to their mind is how to get money to meet the needs of their families at all costs. So that it affects one's mentality and actions to commit criminal acts.Exponential smoothing method is a procedure that continuously improves forecasting with the average (smoothing = smoothing) past values of a time sequence data with. The Exponential smoothing method is a development of the Moving Averages method.

Generation of renewable hydrogen from sewage sludge — Quantitative and energy-based technology evaluation

The paper presents a critical analysis of a commercial pre-feasibility study for hydrogen generation from sewage sludge generated in a wastewater treatment plant sized Population Equivalent (PE) = 160,000 Three commercial offers based on hydrothermal carbonization, gasification/plasma gasification and gas separation, are analysed and validated in terms of chemical reactions and energy balance. The obtained hydrogen yield equals 10 kg H2/Mg sludge for Technology#2 and 5.5 kg H2/Mg sludge for Technology#3, while the process efficiency equals 31.4% and 41.2%, respectively. The offer for Technology#1 is inconsistent. The potential market can be built in the transport sector, based on buses (8–12/day) or locomotives (1–2/day) and complemented by passenger cars (16–22/day). Hydrogen surplus can be disposed into the natural gas network at a city gate station, with target concentration <2%. Alternatively, it is possible to install a fuel cell unit for on-site electricity generation of 1780 MWh/a sold to the public grid.

Skopje City Wall Housing Complex

The 1963 earthquake in Skopje, North Macedonia, prompted an international response culminating in the Town Planning Project financed by the UN Special Fund, which resulted in a new master plan for the city. An international competition for the reconstruction of the Skopje city center was launched as part of the project. The Kenzo Tange entry, which won three-fifths of the first prize, became a representation of the new Skopje. It relied on an autofabulation approach, using elements like ‘city gate’ and ‘city wall’ as important parts of the concept. One of the major features was the City Wall housing development which encircled the central business district (CBD). This paper examines the initial proposal and the phases it passed through to become a new development plan for the center. In this process, Tange played a significant role, defining major planning aspects of the complex, which was later completed according to projects by local architects. The City Wall supported housing as permanent activity in the center and introduced a housing complex of towers and blocks, which became a prominent feature of the Skopje skyline. Although it had to be adapted to the existing conditions and some of the original ideas had to be abandoned, the City Wall complex stood the test of time. Unfortunately, especially since the late 1980s and throughout the 1990s, a number of interventions and alterations have compromised its appearance and some of the basic ideas. The paper argues that the City Wall complex should be proclaimed a cultural heritage, and immediate action should be taken to prevent irreparable damage and to preserve the City Wall as an important and recognizable image of Skopje’s townscape.

Integration of Renewable Energy Systems at City Gate Stations to Reduce Pre-Heating Gas Consumption

Integration of Renewable Energy Systems at City Gate Stations to Reduce Pre-Heating Gas Consumption

Techno-economic assessment of a proposed novel hybrid system for natural gas pressure reduction stations

To prevent Natural Gas (NG) frozen during pressure reduction process, a heater is contrived for preheating NG. In this study, a novel system is suggested to supply part of heat demand of a NG City Gate Station (CGS). The system consists of a heat pump in which the compressor input work is supplied by the turbo-expanders. In the proposed system, pressure reduction is carried out by turbo-expanders instead of Regulator Valve (RV) to recover the energy of high pressure NG. The recovered energy by turbo-expanders meets the heat pump cycle work demand. A CGS is selected as a case study, and the suggested system is assessed in terms of energy, exergy, and economics. The amount of the annual fuel savings is calculated 2.42 × 106 kg (70.08%). Exergy analysis shows that the most exergy destruction occurs in the RV and heater. The exergy factor of the proposed system in the days that the system works, is about 2.2–5.1%. Based on the economic analysis, the value of simple payback period and discounted payback period are calculated 2.63 and 3.08 years, respectively. The annual revenue that comes from saving fuel is 310,000 $/year based on the current price of NG.

Design and analysis of a novel self-refrigerated natural gas liquefaction system integrated with helium recovery and CO2 liquefaction processes

Utilizing the high-pressure exergy of a pipeline gas is a route to overcome the challenge of high power consumption in liquefying natural gas. Through the expansion in city gate stations (CGSs), a notable cold duty is achieved that can liquefy a part of a natural gas feed. Based on this concept, the present research proposes a novel system for natural gas liquefaction utilizing pipeline exergy integrated with helium recovery and innovative carbon dioxide capturing and liquefaction. The process was evaluated by energy, exergy, economic, and exergoeconomic analyses. Results showed that the proposed system can co-produce LNG, liquid helium, and liquid CO2 products with low energy consumption, simplicity, and high profitability. The specific power consumption (SPC) and the exergy efficiency of the natural gas liquefaction system are 0.227 kWh/kgLNG and 64.24%, respectively, which shows a desirable performance as well as a notable potential for improvement. The process equipment of the helium liquefaction system also offers a higher total cost rate, mostly constituting an exergy destruction cost rate. The integrated system exhibits appropriate profitability by the internal rate of return of 47% and the payback period of 3.25 years.

Geometrical optimization of city gate station’s water bath indirect heater to minimization of fuel consumption

Gas industry as one of the greatest sectors of energy, has a major role in environmental issues. A category of energy intensive parts in gas industry is heaters in City Gate Stations which consume colossal volumes of the purified gases. Different optimization strategies to improve the efficiency of these heaters entailing preheating, waste heat recovery of exhausts, insulating pipelines and mounting economizers or recuperators or even using renewable energy sources have been already introduced. Besides, finding the optimized geometry is very essential in improving the efficiency. In this study, a far efficient model for heaters was introduced using the thermal modeling of the process. Based on the properties of the inlet gas, the volume of the gas passing from the CGS and ambient conditions, the consumption of the fuel as well as heater efficiency have been computed as a function of inlet gas properties, CGS’s gas flow rate and ambient condition. Then, results were verified by real data taken from Arak CGS station in Iran. The comparison proves the great correlation between the theoretical and experimental results. Findings show that with an increase in the heater length, a reduction in thermal re-sistance coincides with a higher thermal hysteresis. This causes higher fuel consumption and lower efficiency. Moreover, the higher the length of the fire tube, the more heat is transferred to the pure water and the higher is the efficiency. Considering the optimized heater configu-ration the efficiency improves two folds; changing from 32% to 71%.

Analytical and Field Investigation of Ethylene Glycol Removal from the Indirect Water Bath Heater of a City Gate Station

Analytical and Field Investigation of Ethylene Glycol Removal from the Indirect Water Bath Heater of a City Gate Station

Fire at the gate of Hazor: A micro-geoarchaeological study of the depositional history of a Bronze Age City gate

The City of Hazor is one of the most significant archaeological sites from the biblical period in Israel. Studies on destruction have received much attention in archaeology in recent years. Previous excavations in Hazor have suggested a major conflagration event that destroyed the entire tell site at the end of the Late Bronze Age. The present study re-examines the sedimentary sequence of one of the city’s gates located in Area K by applying a suite of micro-geoarchaeological analyses to understand the stratigraphy previously documented by Yigael Yadin (1972) and later also interpreted by Amnon Ben-Tor et al. (1989); Ben-Tor (1993, 2016); Bechar et al. (2021). In the summer of 2019, 89 bulk sediment samples were taken within squares K5 and K7 in the gate’s passage. This study aimed to understand the archaeological formation processes at the gate and interpret human activities in the Lower City gate of Hazor based on the micro-archaeological record. Laboratory work included Fourier-transform infrared (FTIR) spectroscopy to analyze sediment samples’ composition and quantify phytoliths, wood ash, and dung spherulite concentrations. The major goals of this study are: a) to study the site formation processes, based on mineralogical assemblages and activity micro-residues, of a Middle Bronze to Late Bronze Age city gate; b) to identify mineralogical- and micro-remains, as indicators for fire and destruction of the gate; c) to identify occupation surfaces within the gate and their associated micro-residues; and d) to re-examine previous interpretations of the history of the gate and Hazor in light of the micro-archaeological record.The results confirmed Yadin’s interpretation of the occupation levels at stratum 3 (MB II-C) and 2 (LB I), but with no evidence for destruction between the strata. Those strata showed typical tell site remains, such as anthropogenic input of ash and phytoliths, indicating more or less continuous urban activity. For Yadin’s stratum 1B gate, we identified the floor, the roof, which was the main element that burnt, overlain by a thick unburnt accumulation of the second floor and final burnt debris atop. Our study also suggested a sequence of events for the fiery destruction of the gate and its collapse. The distribution of phytoliths and wood ash combined with the sediments’ composition proposes a single collapse event caused by fire from within the gate. The minimal anthropogenic record above the destruction horizon indicates possible disuse of the gate area following this major destruction event. The conclusions of this study offer new and direct evidence for the history of the gate at Hazor’s Lower City with continuous activity from the Middle Bronze into the Late Bronze Age, ending with a major and single event of destruction of the site at the end of the Late Bronze Age which was followed by its abandonment.

Examination of Condensation Liquid Formation in Istanbul Natural Gas Distribution Network

In this study, the formation of natural gas liquid in gas distribution lines, particularly at regional stations, service boxes, customer installations, and gas meters, was investigated. The study aims to address the problems associated with natural gas liquid formation, such as interruption of supply and decreased efficiency of combustion devices. The indirect measurement of the hydrocarbon dew point was analyzed using C6+ chromatograph data, and the model based on directly measured C6+ data were converted into C6/C7/C8 data by four different methods. As distinct from studies in the literature, this study experimentally determines the distribution of heavy hydrocarbons from C9 to C19 based on indirect methods for acquiring C8+ data and direct measurement of C6+ data. The hydrocarbon dew point temperature was calculated using the Peng–Robinson (PR) and Soave–Redlich–Kwong (SRK) equations of state. The results of the analysis performed on two city gate stations showed that the critical temperatures were 4.21 °C at a pressure of 10.81 bar and 8.27 °C at a pressure of 11.25 bar, respectively. These values were obtained from a model designed to determine the dew point temperature in the area where natural gas liquid formation was most prevalent. The experimental analysis and indirect measurements indicated the occurrence of a two-phase gas–liquid formation.