STUDY OF GAS FUEL LEAKAGE AND EXPLOSION IN THE ENGINE ROOM OF A SMALL LNG-FUELED SHIP

The engine fuel piping in LNG-fuelled ships’ engine room presents potential gas explosion risks due to possible gas fuel leakage and dispersion. A 3D CFD model with chemical reaction was described, validated and then used to simulate the possible gas dispersion and the consequent explosions in an engine room with regulations commanded ventilations. The results show that, with the given minor leaking of a fuel pipe, no more than 1kg of methane would accumulate in the engine room. The flammable gas clouds only exit in limited region and could lead to explosions with an overpressure about 12 mbar, presenting no injury risk to personnel. With the given major leaking, large region in the engine room would be filled with flammable gas cloud within tens of seconds. The gas cloud might lead to an explosion pressure of about 1 bar or higher, which might result in serious casualties in the engine room.

System Design for Early Detection of Explosive and Flammable Gas Leaks Using Mobile Robot in Confined Space

The presence of explosive or flammable gases in confined space may contribute towards accidents that threaten the workers safety and industrial progress. Conventionally, the existing instrument for gas detection in confined space is manually carried by humans whereby the workers or competence person itself were exposed directly to the gases. This project is aim to develop a prototype system to detect the presence of gases leak where the robotic system replaces humans to carry gas sensors. Users only need to maneuver the robot using a mobile phone to monitor the specific area that may have an explosive or flammable gas leak which includes Liquefied Petroleum Gas (LPG) and methane gases. The sensors will detect if a change in the gas concentration has exceeded a safety limit and will activate the alarm as an alert signal. The readings of gases as input signals were sent wirelessly to the Personal Computer (PC) as a user device for monitoring purposes. This prototype is successfully developed, tested and calibrated using the samples of LPG gas, methane, smoke and environment temperature. The result proved that the developed system is able to detect an air sample using selected gas sensors and display the data in graph form with live monitoring. This will contribute significantly to acquiring a new and alternative method using the system for detecting the presence of gases in confined space application.

Impact Assessment of Flammable Gas Dispersion and Fire Hazards from LNG Tank Leak

This study conducts an impact assessment of flammable gas dispersion and fire hazards from LNG tank leak. The release source model is used to estimate LNG release rate. A CFD (computational fluid dynamics) based 3D model is established to simulate dispersion behavior of flammable gas from the phase transformation of LNG. Subsequently, a FDS (fire dynamics) based model is built to simulate the pool fire due to LNG tank leak. The impact of gas dispersion and fire on personnel and assets is assessed based on simulation results, which can provide a theoretical basis and method support for major accident assessment of tank leakage in large LNG receiving station. The results show that the dispersion of flammable gas from LNG tank leak has an obvious stage characteristic. The flammable gas reached a steady state around 300 s, and the corresponding coverage area is about 16250 m2. The pool fire simulations indicate that the steady flame is formed at 20 s. The flames flow along the wind, and the maximum temperature of the fire reaches 670°C, and the maximum thermal radiation reaches 624 kW/m2. According to the fire damage criteria, the pool fire from LNG tank leak may pose a serious threat on the safety of adjacent assets and personnel.

Exogenous Hydrogen Sulfide Plays an Important Role by Regulating Autophagy in Diabetic-Related Diseases

Autophagy is a vital cell mechanism which plays an important role in many physiological processes including clearing long-lived, accumulated and misfolded proteins, removing damaged organelles and regulating growth and aging. Autophagy also participates in a variety of biological functions, such as development, cell differentiation, resistance to pathogens and nutritional hunger. Recently, autophagy has been reported to be involved in diabetes, but the mechanism is not fully understood. Hydrogen sulfide (H2S) is a colorless, water-soluble, flammable gas with the typical odor of rotten eggs, which has been known as a highly toxic gas for many years. However, it has been reported recently that H2S, together with nitric oxide and carbon monoxide, is an important gas signal transduction molecule. H2S has been reported to play a protective role in many diabetes-related diseases, but the mechanism is not fully clear. Recent studies indicate that H2S plays an important role by regulating autophagy in many diseases including cancer, tissue fibrosis diseases and glycometabolic diseases; however, the related mechanism has not been fully studied. In this review, we summarize recent research on the role of H2S in regulating autophagy in diabetic-related diseases to provide references for future related research.

Design and Implementation of an IoT Based LPG and CO Gases Monitoring System

Nowadays use of liquefied petroleum gas (LPG) has increased. LPG is an asphyxiating, volatile and highly flammable gas. In a LPG leak situation, potential health accidents are increased either by inhalation or by combustion of the gas. On the other hand, carbon monoxide (CO) is a toxic gas that comes mainly from combustion in car engines. Breathing CO-polluted air can cause dizziness, fainting, breathing problems, and sometimes death. To prevent health accidents, including explosions, in open or closed environments, remote and real-time monitoring of the concentration levels of CO and LPG gases has become a necessity. The aim of this work is to demonstrate the use of Internet of Things (IoT) techniques to design and build a telemetry system to monitor in real-time the concentration of GLP and CO gases in the surrounding air. To implement this work, as central hardware there is a microcontroller, CO and PLG sensors on the electronic station. Besides, Amazon Web Services (AWS) was used as an IoT platform and data storage in the cloud. The main result was a telematics system to monitor in real time the concentrations of both GLP and CO gases, whose data is accessible from any device with internet access through a website. Field tests have been successful and have shown that the proposed system is an efficient and low-cost option.

Possibilities of Capturing Methane from Hard Coal Deposits Lying at Great Depths

Methane present in coal seams is a natural hazard present during the exploitation of underground mining plants. It is an explosive and flammable gas that is released into mining excavations, and it is necessary to reduce its concentration. Capturing methane while preparing extraction is virtually impossible due to the low permeability of coal resulting from its deposition depth. After the beginning of exploitation and disrupting the seam’s structure, methane is released into mine air. The most common method of minimizing gas released into ventilation air is draining the rock mass. This method allows achieving the desired ventilation parameters but requires appropriate mining techniques in hazardous areas. The article presents the example of methane capture during the operation in the longwall B-15 with an overlying drainage gallery. The authors have highlighted an example of the longwall B-15 that when using this particular drainage method, allowed capturing twice the amount of methane forecasted, thus increasing the efficiency of methane drainage. At the preliminary stage of longwall development, the amount of methane charged by the drainage system had relatively low values, reaching 15 m3/min. In the next few months, these parameters increased and varied between 35 to 55 m3/min. A significant difference in methane capture appeared in the second stage of exploitation, where the highest value of captured methane reached 82 m3/min. This particular longwall example shows that it is crucial to properly design the drainage system for seams with high forecasted methane release. It is worth remembering that using a drainage gallery provides an increase in the methane capture from the desorption zone areas, thus increasing total methane capture in comparison to forecasts.

Risk assessment of workers’ exposure to BTEX and hazardous area classification at gasoline stations

Vaporization of benzene, toluene, ethylbenzene, and xylene (BTEX) compounds pollutes the air and causes health hazards at gasoline stations. This study revealed the risk of BTEX exposure according to the hazardous area classification at gasoline stations. The risk assessment of gasoline workers from a representative group of 47 stations, which followed the United States Environmental Protection Agency-IRIS method of assessing BTEX exposure, was expressed as the hazard index (HI). A result of matrix multipliers of the hazardous exposure index and fire possibility from flammable gas classified hazardous area-I and area-II at the fuel dispensers. BTEX concentrations were actively sampled in ambient air and a flammable gas detector was used to measure the flammability level. Results showed that the BTEX concentrations from ambient air monitoring were in the range of 0.1–136.9, 8.1–406.0, 0.8–24.1 and 0.4–105.5 ppb for benzene, toluene, ethylbenzene, and xylene, respectively, which exceeded the NIOSH exposure limit of 100 ppb of benzene concentration. The risk assessment indicated that five stations reached an unacceptable risk of worker exposure to BTEX (HI>1), which correlated with the numbers of gasoline dispensers and daily gasoline sold. The risk matrix classified hazardous area-I at 4 meters and hazardous area-II at 4–8 meters in radius around the fuel dispensers. This study revealed the hazardous areas at gasoline stations and suggests that entrepreneurs must strictly control the safety operation practice of workers, install vapor recovery systems on dispenser nozzles to control BTEX vaporization and keep the hazardous areas clear of fire ignition sources within an eight-meter radius of the dispensers.