Evaluating the Gas Distribution Quality of PEMFC in Dynamic Response: Severe Condition of Delayed Gas Supply

There are investigated the influence of operating pressures in the gas supply system on the level of such energy indicators as efficiency, gas flow and gas overrun by gas equipment in residential buildings. There is established a relationship between the values of operating pressures in the gas supply system and the gas consumption level of household appliances. The causes of insufficient pressure in the gas networks of settlements are analyzed in the article. There is also developed an algorithm for calculating the change in the efficiency of gas appliances depending on the operational parameters of the gas network. It has been found that the most efficient operation of gas appliances is observed at an overpressure at the inlet of gas appliances of about 1200 Pa.To ensure the required quality of natural gas combustion among consumers and minimize gas consumption there are justified the following measures in the article: coordinating a domestic regulatory framework for assessing the quality of natural gas with international norms and standards; improving the preparation of gas coming from local wells before supplying it to gas distribution networks; auditing low pressure gas pipelines and reconstructing areas affected by corrosion; ensuring standard gas pressure in the network for the normal operation of domestic gas appliances; stating quality indicators of natural gas combustion by gas sales organizations.

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Influence of center gas supply device on gas–solid flow in COREX shaft furnace through DEM–CFD model

International Journal of Chemical Reactor Engineering ◽

10.1515/ijcre-2020-0012 ◽

2020 ◽

Vol 18 (5-6) ◽

Author(s):

Heng Zhou ◽

Shuyu Wang ◽

Binbin Du ◽

Mingyin Kou ◽

Zhiyong Tang ◽

...

Keyword(s):

Gas Flow ◽

Shaft Furnace ◽

Middle Zone ◽

Cfd Model ◽

Gas Velocity ◽

Gas Distribution ◽

Particle Segregation ◽

Solid Flow ◽

Corex Shaft Furnace ◽

Gas Supply

AbstractIn order to develop the central gas flow in COREX shaft furnace, a new installment of center gas supply device (CGD) is designed. In this work, a coupled DEM–CFD model was employed to study the influence of CGD on gas–solid flow in COREX shaft furnace. The particle descending velocity, particle segregation behaviour, void distribution and gas distribution were investigated. The results show that the CGD affects the particles descending velocity remarkably as the burden falling down to the slot. Particle segregation can be observed under the inverse ‘V’ burden profile, and the influence of CGD on the particle segregation is unobvious on the whole, which causes the result that the voidage is slightly changed. Although the effect of CGD on solid flow is not significant, the gas flow in shaft furnace has an obvious change. Compared with the condition without CGD, in the case with CGD, the gas velocity is improved significantly, especially in the middle zone of the furnace, which further promotes the center gas distribution. Meanwhile, the pressure drop in the furnace with the installation of CGD is increased partly.

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Performance Improvement of SVPWM-Based Three-Phase Grid-Connected Inverters

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.732-733.1261 ◽

2013 ◽

Vol 732-733 ◽

pp. 1261-1264

Author(s):

Zhi Lei Yao ◽

Lan Xiao ◽

Jing Xu

Keyword(s):

Dynamic Response ◽

Control Strategy ◽

Pulse Width Modulation ◽

Control Method ◽

Grid Current ◽

Current Controller ◽

Three Phase ◽

Reference Grid ◽

Grid Connected Inverter

An improved control strategy for three-phase grid-connected inverters with space vector pulse width modulation (SVPWM) is proposed. When the grid current contains harmonics, the d-and q-axes grid currents is interacted in the traditional control method, and the waveform quality of the grid current is poor. As the reference output voltage cannot directly reflect the change of the reference grid current with the traditional control strategy, the dynamic response of the grid-connected inverter is slow. In order to solve the aforementioned problems, the d-and q-axes grid currents in the decoupled components of the grid current controller are substituted by the d-and q-axes reference grid currents, respectively. The operating principles of the traditional and proposed control methods are illustrated. Experimental results show that the grid-connected inverter with the improved control strategy has high waveform quality of the grid current and fast dynamic response.

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Short Review On Varicose Vein And Its Management

International Journal of Research in Pharmaceutical Sciences ◽

10.26452/ijrps.v12i1.4190 ◽

2021 ◽

Vol 12 (1) ◽

pp. 832-836

Author(s):

Pranav N ◽

Anila K N ◽

Riju.R.Menon

Keyword(s):

Quality Of Life ◽

Varicose Vein ◽

Inflammatory Responses ◽

Early Stage ◽

Treatment Strategies ◽

Short Review ◽

Disease Diagnosis ◽

Treated Group ◽

Severe Condition

A varicose vein is a condition which affects a large number of people in Western countries and India especially, the northern areas. For curing this proper disease diagnosis, sufficient care for patient and treatment strategies are required, to control the symptoms and signs of varicose vein, the flavonoid group of drugs have been widely used for many years. Under this group, Daflon is the most potent and efficient drug which can be used. This enhances the bioavailability and absorption from the gastrointestinal area. Improved quality of patient's life and efficacy makes this drug therapy more potent and significant. Some of the clinical studies have shown its better action for increased venous tone, lymphatic drainage, decreases cosmetic disfigurement, inflammatory responses occur in microcirculation, protection from free radicals and improved quality of life and efficacy. When compared with other available drugs like Polidocanol, Sotradecol, Asclera, Varithena, Sodium tetradecyl sulfate etc. .clinical benefits of Daflon is more. This drug is useful in the early stage and can be used in severe condition along with sclerotherapy, compression treatment and surgery. Increased patient’s quality of life and increased efficacy were observed in Daflon treated group. Thus it is efficacious as a standard therapy alone and also in combination with other conservative treatment.

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Numerical Monitoring of Natural Gas Distribution Discrepancy Using CFD Simulator

Journal of Applied Mathematics ◽

10.1155/2010/407648 ◽

2010 ◽

Vol 2010 ◽

pp. 1-23 ◽

Cited By ~ 3

Author(s):

Vadim E. Seleznev

Keyword(s):

Natural Gas ◽

Distribution System ◽

Field Measurements ◽

Identification Problem ◽

Distribution Networks ◽

Reference Points ◽

Gas Distribution ◽

Natural Gas Transmission ◽

Minimum Discrepancy ◽

Gas Supply

The paper describes a new method for numerical monitoring of discrepancies in natural gas supply to consumers, who receive gas from gas distribution loops. This method serves to resolve the vital problem of commercial natural gas accounting under the conditions of deficient field measurements of gas supply volumes. Numerical monitoring makes it possible to obtain computational estimates of actual gas deliveries over given time spans and to estimate their difference from corresponding values reported by gas consumers. Such estimation is performed using a computational fluid dynamics simulator of gas flows in the gas distribution system of interest. Numerical monitoring of the discrepancy is based on a statement and numerical solution of identification problem of a physically proved gas dynamics mode of natural gas transmission through specified gas distribution networks. The identified mode parameters should have a minimum discrepancy with field measurements of gas transport at specified reference points of the simulated pipeline network.

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Analysis and evaluation of the effect of vibrations on historical buildings

MATEC Web of Conferences ◽

10.1051/matecconf/202031300020 ◽

2020 ◽

Vol 313 ◽

pp. 00020

Author(s):

Shota Urushadze ◽

Miroš Pirner

Keyword(s):

Early Detection ◽

Dynamic Response ◽

Human Activity ◽

Road Traffic ◽

Historic Buildings ◽

Historical Buildings ◽

Analysis And Evaluation ◽

Vibration Magnitude ◽

Degradation Of Materials

Continued exposure of human induced vibrations contributes to the degradation of materials and joints, causing the initiation of cracks or the growth of existing ones, such that they may endanger the structure. Loads, which an undamaged structure could safely resist, can be critical if repeated numerous times. This risk is present in various types of historical buildings, and is influenced by changes in vibration magnitude, by the distance from their source, and by the quality of the building’s maintenance. Good maintenance, which includes regular inspections, allows early detection of any emerging damage and its subsequent repair. This article describes the methods and results of the measurement of dynamic response to road traffic and other types of technical seismicity in four historic buildings. The goal of this paper is to present some examples of analysis and evaluation of the effects of such human activity.

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Properties of Artificial Gaseous Mixtures for their Safe Use and Support the Natural Gas Supply Networks / Własności Sztucznych Mieszanin Gazowych do Bezpiecznego ich Użytkowania i Wspomagania Zasilania Sieci Gazu Ziemnego

Archives of Mining Sciences ◽

10.2478/v10267-012-0022-5 ◽

2012 ◽

Vol 57 (2) ◽

pp. 351-362 ◽

Cited By ~ 1

Author(s):

Mariusz Łaciak

Keyword(s):

Heat Exchange ◽

Natural Gas ◽

Landfill Gas ◽

Gas Mixtures ◽

Gaseous Mixtures ◽

Household Appliances ◽

The World ◽

Wobbe Index ◽

Gas Supply

Abstract The increase in natural gas consumption by the general public and industry development, in particular the petrochemical and chemical industries, has made increasing the world interest in using gas replacement for natural gas, both as mixtures of flammable gases and gas mixtures as LPG with air (SNG - Synthetic Natural Gas). Economic analysis in many cases prove that to ensure interchangeability of gas would cost less than the increase in pipeline capacity to deliver the same quantity of natural gas. In addition, SNG systems and installations, could be considered as investments to improve security and flexibility of gas supply. Known existing methods for determining the interchangeability of gases in gas gear based on Wobbe index, which determines the heat input and the burning rate tide, which in turn is related to flame stability. Exceeding the Wobbe index of a value increases the amount of carbon monoxide in the exhaust than the permissible concentration. Methods of determining the interchangeability of gases is characterized by a gas in relation to the above-described phenomena by means of quantitative indicators, or using diagrams interchangeability, where the gas is characterized by the position of a point in a coordinate system. The best known method for determining the interchangeability of gases is Delbourg method, in which the gas is characterized by the revised (expanded) Wobbe Index (Wr), the combustion potential, rate of soot formation (Ich) and the ratio of the formation of yellow ends (Ij). Universal way to determine the interchangeability of gas is also Weaver accounting method. It does not require determination of the reference gas. It is designed for utensils for household gas and gas pressure p = 1.25 kPa. The criteria and definition of gas interchangeability volatility in practice to the combustion in a gas gear. In the case of gas exchange in industrial furnaces, interchangeability criteria are usually not very useful because of other conditions of combustion and heat exchange. In industrial reheating furnace gas is combusted in a sealed combustion chambers. Air supply is regulated. The exhaust gases are discharged into canals and the chimney to the atmosphere. The temperature difference between load (fuel gas) and the flame is much less than in the case of gas household appliances. In the furnace heat exchange takes place mainly by radiation in 85% to 95%. The value of heat flux flowing from the gas to a heated charge is not proportional to the heat load burners. Interchangeability of gas is linked by adding to natural gas, a certain amount of gas that is a substitute for natural gas in meeting the criteria for substitution in order to ensure certainty of supply of natural gas to customers. Gases that can be used in the processes of blending and used as replacement gases are mainly a mixture of propane and propane - butane (LPG - Liquid Petroleum Gas), landfill gas or biogas (LFG - Landfill Gas) and dimethyl ether (DME). One of the more well-known gas mixtures used in many countries around the world to compensate for peak demands is a mixture containing about 75% of natural gas and approximately 25% propane / air (LPG / air). Also in Poland is prepared to amend the provisions in this regard (at this moment - oxygen in the gas network can not exceed 0.2%). In this paper, the calculations of interchangeability of gas mixtures LFG - LPG and LPG - air (SNG) for natural gas was made. It was determined whether the analyzed mixtures have similar stable flame zones regardless of the quality of LFG fuel and whether they may in whole or in part replace CH4, without any modification of equipment suction air for combustion. The obtained results will determine whether the fuel can be used as a replacement for natural gas used in such household appliances and, possibly, industrial burners. In connection with the possibility of changes in the quality of LFG, depending on such factors as storage time, as pre-treatment, will be determined the degree of interchangeability of LFG as a fuel mixed with regard to its quality.

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SOME ASPECTS OF PREVENTION OF CRYSTALLINE HYDRATES FORMATION AT GAS DISTRIBUTION STATIONS

Proceedings of Southwest State University ◽

10.21869/2223-1560-2017-21-3-68-74 ◽

2017 ◽

Vol 21 (3) ◽

pp. 68-74

Author(s):

V. S. Ezhov ◽

G. G. Shchedrina ◽

N. E. Semicheva

Keyword(s):

Natural Gas ◽

Distribution Systems ◽

Integrated Treatment ◽

Crystalline Hydrate ◽

Gas Pipelines ◽

Gas Distribution ◽

Treatment Unit ◽

Natural Gas Dehydration ◽

Gas Supply ◽

Crystalline Hydrates

The existing methods for natural gas dehydration both in fields and at compressor stations cannot always provide standatdized values of natural gas dehydration. The analysis of operation of gas distribution systems shows that dehydration units are improperly placed and are often installed out of condensation and freezing zones. This is due to the lack of consideration of phase transitions impact in gas throttling on its temperature condition. Due to insufficient natural gas dehydration, crystalline hydrates can be formed on wellbores, distribution lines and main gas pipelines and at its reduction, disturbing the operation of the equipment of compressor stations, gas distribution stations, deranging instrumentation and automation. The issues of reliability of gas pipeline systems considering the formation of crystalline hydrate plugs in pipelines have been studied. The analysis of the methods and devices preventing hydrates formation and eliminating existing crystalline hydrate plugs has shown that to provide normalized parameters of the transported gas it is necessary to perform additional water vapor, condensate drops and crystalline hydrate particles removal from natural gas at gas distribution stations during winter months. Currently applied methods used to deal with crystalline hydrate plugs in main gas pipelines require significant expenses and do not effectively ensure the reliability of pipelines operation. An energy-efficient design of an integrated treatment unit which provides an additional natural gas treatment at GDS, increases the reliability of gas pipelines protection against hydrate blockage and improves the efficiency of gas supply systems as a whole have been proposed at the Department of Heat and Gas Supply and Ventilation of the SWSU.

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Multiple-criteria decision analysis for cross-country gas pipelines

E3S Web of Conferences ◽

10.1051/e3sconf/201910203010 ◽

2019 ◽

Vol 102 ◽

pp. 03010 ◽

Cited By ~ 1

Author(s):

Mikhail Sukharev ◽

Ruslan Popov ◽

Anton Balchenko

Keyword(s):

Gas Production ◽

Optimization Task ◽

Gas Pumping ◽

The Stability ◽

Production Capacities ◽

The Cost ◽

Gas Fields ◽

Planning Problems ◽

Gas Supply

The paper considers the shortand medium-term planning problems of the regimes of multi-line technical gas pipeline corridors (MLGP) of Russian gas supply system. The fall in gas production due to the depletion of the gas fields leads to a decrease in the load of some operating MLGPs. At the same time, there is a redundancy of production capacities at compressor stations (CS). It becomes possible to use various technological schemes for incorporating CS with lines "pass by" in order to reduce the cost of gas pumping. The solution of the optimization task for the search for MLGP regimes in a one-criterion (minimum of the energy cost) formulation leads to frequent equipment switching. That is unacceptable. Therefore, it is advisable to proceed to multi-criteria statements, formalizing and introducing as criteria the requirements for the stability of technological schemes for switching on equipment, which are usually respected by the dispatch services. The purpose of this article is the development and testing of mathematical models and a computer program to support the adoption of dispatch solutions for managing modes of large MLGPs under conditions of incomplete loading. The solution method is demonstrated by the example of a three-line MLGP. The choice of optimal control is carried out using dynamic programming methods. In order to improve the quality of the choice of control actions, an algorithm is suggested that takes into account the stochastic nature of the loading of the MLGP.

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Small-scale technology solutions to eliminate flaring

The APPEA Journal ◽

10.1071/aj15118 ◽

2016 ◽

Vol 56 (2) ◽

pp. 612 ◽

Cited By ~ 1

Author(s):

James Brown ◽

Chiew Yen Law ◽

Katherine Fielden ◽

Ceri-Sian Dee ◽

Neil Pollock

Keyword(s):

Natural Gas ◽

Economic Value ◽

Cost Effective ◽

Oil Fields ◽

Small Scale ◽

Well Testing ◽

Associated Gas ◽

Future Technologies ◽

Gas Supply

Five percent of the world’s gas supply is wasted by being flared or vented into the atmosphere, leading to a huge loss of potential revenue, not to mention a significant impact on the environment. This is equivalent to 150 billion cubic metres of natural gas per year and the release of 400 million metric tons of CO2 equivalent. The industry does this for a variety of valid reasons, including well testing, emergencies, commissioning, maintenance, or simply because an economic solution for capturing and using the gas has not been discovered. Capture of flared gas, therefore, presents an economic and environmentally beneficial opportunity to create new value chains that can benefit not only the industry but also people’s quality of life. This extended abstract draws on a recent DNV GL project to assess existing and future technologies and concepts for capturing small volumes of associated gas that are normally flared from oil fields, both onshore and offshore. The following four technology options that can be used to capture associated gas, convert it, and either utilise the product onsite or transport it to market for consumption are considered. Using more cost-effective ways of transporting natural gas where there is no existing pipeline. Converting gas into products with a higher economic value through chemical processes. Novel concepts—bringing the solution closer to the source of gas flaring. Other solutions. The extended abstract then focuses on cost-effective ways of transporting gas, in particular the use of micro-LNG solutions

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