Study of Distribution and Quantification of Flammable Gas in Confined Space

The contribution deals with leakage of natural gas from domestic low-pressure piping. Spreading of the leaked natural gas in the confined space is deals with and the areas are defined where local hazardous concentrations are formed. Mathematical CFD models provide broad overview of spreading of natural gas, in dependence on the elapsed time from the start of leakage. The contribution should improve the understanding of spreading and distribution of mixture of gaseous fuels in confined spaces, and thus leads to significant reduction of the risk of occurrence of fire or explosion or to prevention of these hazards.

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Lime kiln conversion from coke to natural gas operation – an option in direction of sustainable energy

Sugar Industry ◽

10.36961/si24555 ◽

2020 ◽

pp. 431-434

Author(s):

Oliver Arndt

Keyword(s):

Natural Gas ◽

New Technology ◽

Exhaust Gas ◽

Gas Temperature ◽

Gaseous Fuels ◽

Lime Kiln ◽

Lime Kilns ◽

Co2 Balance ◽

Exhaust Gas Temperature

This paper deals with the conversion of coke fired lime kilns to gas and the conclusions drawn from the completed projects. The paper presents (1) the decision process associated with the adoption of the new technology, (2) the necessary steps of the conversion, (3) the experiences and issues which occurred during the first campaign, (4) the impacts on the beet sugar factory (i.e. on the CO2 balance and exhaust gas temperature), (5) the long term impressions and capabilities of several campaigns of operation, (6) the details of available technologies and (7) additional benefits that would justify a conversion from coke to natural gas operation on existing lime kilns. (8) Forecast view to develop systems usable for alternative gaseous fuels (e.g. biogas).

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Comparison Between Two-Shaft Simple and Single-Shaft Recuperated Brayton Cycles Using Different Types of Gaseous Fuels

Volume 5: Industrial and Cogeneration; Microturbines and Small Turbomachinery; Oil and Gas Applications; Wind Turbine Technology ◽

10.1115/gt2010-23633 ◽

2010 ◽

Author(s):

A. K. Malkogianni ◽

A. Tourlidakis ◽

A. L. Polyzakis

Keyword(s):

Natural Gas ◽

Gas Turbines ◽

Alternative Fuels ◽

High Efficiency ◽

Heating Value ◽

Gaseous Fuels ◽

Oil And Natural Gas ◽

Parametric Studies ◽

The Impact ◽

Lower Heating

Geopolitical issues give rise to problems in the smooth and continuous flow of oil and natural gas from the production countries to the consumers’ development countries. In addition, severe environmental issues such as greenhouse gas emissions, eventually guide the consumers to fuels more suitable to the present situation. Alternative fuels such as biogas and coal gas have recently become more attractive because of their benefits, especially for electricity generation. On the other hand, the use of relatively low heating value fuels has a significant effect to the performance parameters of gas turbines. In this paper, the impact of using four fuels with different heating value in the gas turbine performance is simulated. Based on the high efficiency and commercialization criteria, two types of engines are chosen to be simulated: two-shaft simple and single-shaft recuperated cycle gas turbines. The heating values of the four gases investigated, correspond to natural gas and to a series of three gases with gradually lower heating values than that of natural gas. The main conclusions drawn from this design point (DP) and off-design (OD) analysis is that, for a given TET, efficiency increases for both engines when gases with low heating value are used. On the contrary, when power output is kept constant, the use of gases with low heating value will result in a decrease of thermal efficiency. A number of parametric studies are carried out and the effect of operating parameters on performance is assessed. The analysis is performed with customized software, which has been developed for this purpose.

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Cockroaches traverse crevices, crawl rapidly in confined spaces, and inspire a soft, legged robot

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1514591113 ◽

2016 ◽

Vol 113 (8) ◽

pp. E950-E957 ◽

Cited By ~ 69

Author(s):

Kaushik Jayaram ◽

Robert J. Full

Keyword(s):

Body Weight ◽

High Speed ◽

Stride Length ◽

Body Height ◽

Legged Robot ◽

Confined Space ◽

Performance Limits ◽

Biological Inspiration ◽

Confined Spaces ◽

Postural Changes

Jointed exoskeletons permit rapid appendage-driven locomotion but retain the soft-bodied, shape-changing ability to explore confined environments. We challenged cockroaches with horizontal crevices smaller than a quarter of their standing body height. Cockroaches rapidly traversed crevices in 300–800 ms by compressing their body 40–60%. High-speed videography revealed crevice negotiation to be a complex, discontinuous maneuver. After traversing horizontal crevices to enter a vertically confined space, cockroaches crawled at velocities approaching 60 cm⋅s−1, despite body compression and postural changes. Running velocity, stride length, and stride period only decreased at the smallest crevice height (4 mm), whereas slipping and the probability of zigzag paths increased. To explain confined-space running performance limits, we altered ceiling and ground friction. Increased ceiling friction decreased velocity by decreasing stride length and increasing slipping. Increased ground friction resulted in velocity and stride length attaining a maximum at intermediate friction levels. These data support a model of an unexplored mode of locomotion—“body-friction legged crawling” with body drag, friction-dominated leg thrust, but no media flow as in air, water, or sand. To define the limits of body compression in confined spaces, we conducted dynamic compressive cycle tests on living animals. Exoskeletal strength allowed cockroaches to withstand forces 300 times body weight when traversing the smallest crevices and up to nearly 900 times body weight without injury. Cockroach exoskeletons provided biological inspiration for the manufacture of an origami-style, soft, legged robot that can locomote rapidly in both open and confined spaces.

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Vapor Recovery from Condensate Storage Tanks Using Gas Ejector Technology

Journal of Chemical Engineering ◽

10.3329/jce.v27i1.15856 ◽

2013 ◽

Vol 27 ◽

pp. 37-41

Author(s):

Palash K Saha ◽

Mahbubur Rahman

Keyword(s):

Natural Gas ◽

Chemical Engineering ◽

Economic Loss ◽

Low Pressure ◽

Heat Energy ◽

Environmental Concerns ◽

Storage Tanks ◽

Gas Field ◽

Recovery Unit ◽

Yearly Saving

This paper demonstrates a method of recovering the low pressure vapor from the condensate tanks in the Bibiyana gas field. This method uses a gas ejector as a device to compress the low pressure natural gas from the condensate tanks to an intermediate pressure, which would then be fed into the intermediated stage of the existing vapor recovery unit. Thus the natural gas will be saved which would have been otherwise flared. The amount of tank vapor is estimated by different methods, which shows a significant amount of gas is now being flared. Flaring of gas is a problem which entails both economic loss and environmental concerns. It is estimated that, on the average 190 MSCFD tank vapor can be recovered using the proposed method involving a gas ejector. Thus yearly saving would be about 68 MMSCF of natural gas. The equivalent heat energy saving is about 74.55X109 BTU. In terms of greenhouse gas emissions, this project will reduce about 1,112 tons of CO2 emissions per year in the gas plant locality. DOI: http://dx.doi.org/10.3329/jce.v27i1.15856 Journal of Chemical Engineering, IEB Vol. ChE. 27, No. 1, June 2012: 37-41

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Droplet and Aerosol Suspension Times in Ambient Air in Confined Spaces and Transmission of COVID-19: Influence of Environmental Factors

Journal of Scientific Research ◽

10.3329/jsr.v13i2.50273 ◽

2021 ◽

Vol 13 (2) ◽

pp. 495-506

Author(s):

M. R. Islam ◽

S. H. Naqib

Keyword(s):

Relative Humidity ◽

Environmental Factors ◽

Ambient Air ◽

Confined Space ◽

Natural Processes ◽

Confined Spaces ◽

Potential Source ◽

Aerosol Droplet ◽

Exhaled Air ◽

Mode Of Transmission

The COVID‑19 pandemic, alternatively known as the coronavirus pandemic, is an unfolding pandemic of coronavirus disease 2019 (COVID‑19) across the entire globe in an unprecedented proportion. COVID-19 is caused by severe acute respiratory syndrome coronavirus 2. The mode of transmission of COVID-19 is a subject of intense research. The airborne transmission is one prime possibility. Breathing and talking are natural processes which generate exhaled particles. The exhaled air is an aerosol/droplet composed of naturally produced particulates of varying size. The duration over which the aerosols/droplets are suspended in the air is an important factor. Long suspended aerosols/droplets are potential source of transmission, particularly in confined spaces. We have calculated times of suspension by considering various environmental factors, namely, the ambient temperature and relative humidity in a confined space, in this work. Both temperature and relative humidity affect the suspension time of the exhaled aerosols/droplets with varying degree. The effects of environmental factors are significant for aerosols, particularly for those with small radii. We have discussed the possible implications of our findings in this paper.

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Improved Design Parameters for a Liquid Desiccant Dehumidifier in Confined Spaces

Solar Energy ◽

10.1115/isec2005-76075 ◽

2005 ◽

Author(s):

D. Dong ◽

M. Liu

Keyword(s):

Energy Consumption ◽

Ventilation System ◽

Exhaust System ◽

Design Parameters ◽

Confined Space ◽

Confined Spaces ◽

Exhaust Ventilation ◽

Moisture Condensation ◽

Improved Design ◽

Control Application

Investigations of a desiccant dehumidifier system have been performed for humidity control application in confined spaces. A previous study revealed that the base dehumidifier system can reduce moisture condensation by 22% over a conventional exhaust ventilation system. The current study aims to develop improved design requirements for a desiccant dehumidifier. The energy consumption of an exhaust ventilation system and an improved dehumidifier system was compared. To investigate the improved desiccant dehumidification system, numerical simulations were conducted and an objective function was established. This paper presents simulated results for an existing desiccant dehumidification system and an improved system, in which improved parameters are used. Use of the improved design parameters can reduce moisture condensation by 26.6% over a base dehumidifier system and shorten the dehumidifier performance period by 14%. Energy consumption with the sole use of an exhaust system is compared with that of the improved dehumidifier system under the same conditions. The results show that energy consumption can be substantially reduced, by 63%, in the improved dehumidifier system with the same amount of moisture condensation on surfaces of the confined space.

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