Risk Assessment for Natural Gas Hydrate Carriers: A Hazard Identification (HAZID) Study

Early Warning Weather Hazard System for Power System Control

Power systems and their primary components, mostly the transmission and distribution of overhead lines, substations, and other power facilities, are distributed in space and are exposed to various atmospheric and meteorological conditions. These conditions carry a certain level of risk for reliable electrical power delivery. Various atmospheric hazards endanger the operation of power systems, where the most significant are thunderstorms, wildfire events, and floods which can cause various ranges of disturbances, faults, and damages to the power grid, or even negatively affect the quality of life. By utilizing a weather monitoring and early warning system, it is possible to ensure a faster reaction against different weather-caused fault detections and elimination, to ensure a faster and more adequate preparation for fighting extreme weather events, while maintaining overhead line protection and fault elimination. Moreso, it is possible to bypass overhead lines that have the highest risk of unfavorable meteorological events and hazards, and reroute the energy, thus providing electricity to endangered areas in times of need while minimizing blackouts, and consequently, improving the quality of human life. This paper will present an analysis of the various risks of atmospheric phenomena, in the meteorological and climate context, and discuss various power system components, the power system control, operations, planning, and power quality. A concept with the main functionalities and data sources needed for the establishment of an early warning weather hazard system will be proposed. The proposed solution can be used as a utility function in power system control to mitigate risks to the power system due to atmospheric influences and ongoing climate change.

Safety and Reliability Analysis of an Ammonia-Powered Fuel-Cell System

Recently, the shipping industry has been under increasing pressure to improve its environmental impact with a target of a 50% reduction in greenhouse gas emissions by 2050, compared to the 2008 levels. For this reason, great attention has been placed on alternative zero-carbon fuels, specifically ammonia, which is considered a promising solution for shipping decarbonisation. In this respect, a novel ammonia-powered fuel-cell configuration is proposed as an energy-efficient power generation configuration with excellent environmental performance. However, there are safety and reliability concerns of the proposed ammonia-powered system that need to be addressed prior to its wider acceptance by the maritime community. Therefore, this is the first attempt to holistically examine the safety, operability, and reliability of an ammonia fuel-cell-powered ship, while considering the bunkering and fuel specifications. The proposed methodology includes the novel combination of a systematic preliminary hazard identification process with a functional and model-based approach for simulating the impact of various hazards. Furthermore, the critical faults and functional failures of the proposed system are identified and ranked according to their importance. This work can be beneficial for both shipowners and policymakers by introducing technical innovation and for supporting the future regulatory framework.

Risk assessment of fire, explosion and release of toxic gas of Siri-Assalouyeh sour gas pipeline using fuzzy analytical hierarchy process

Background

Risk assessment of gas pipelines is very important because of various hazards and economic losses. Using fuzzy logic increases the reliability and accuracy of the results. The purpose of this study is to evaluate the fuzzy risk of fire, explosion and release of toxic gas in the pipeline using fuzzy analytical hierarchy process.

Methodology

Extraction of all hazards from HAZOP and HAZID was carried out. Fuzzy risk assessment was performed using MATLAB software. Using fuzzy hierarchy process analysis, the weight of each basic risk item (BRI) was summed up in a framework, and the fuzzy risk level was determined with a five-state criterion including highly desirable, favorable, moderate, undesirable and highly undesirable.

Results

The final risk score was equal to 0.1492, which according to the five-state criterion the risk level is in the favorable area. The highest risk score was related to hot work with open flame item with a risk score of 0.2485.

Conclusions

The final risk score of fire, explosion and release of toxic gas in Siri-Assaluyeh gas pipeline is in the optimal area. Fuzzy risk assessment, compare to conventional risk matrices, provides more data to safety managers about the hazards and their rankings. Accordingly, the results are expected to be applicable to the safety managers while making decisions related to the risk management of gas pipelines.

Developing the environmentally friendly technologies of combustion of gas hydrates. Reducing harmful emissions during combustion

In recent years, there has been a sharp increase in interest in the development of environmentally friendly technology for burning methane gas hydrate. In addition to solving energy problems, gas hydrates will help to make significant progress in solving environmental problems. The use of gas hydrate combustion technology is shown to reduce harmful emissions. In this work, experimental studies on the combustion of double hydrate powder of propane-methane have been performed at five different ways of combustion organization. Powder heating was realized using: 1) induction heating; 2) radiation and convective heating; 3) using a hot metal body; 4) combustion without forced gas flow and 5) combustion in the presence of forced and free air convection. Currently there has been neither a comprehensive study of the combustion of double gas hydrates, nor a comparison of the combustion efficiency for different methods; besides, no data on emissions have been obtained. The maximum dissociation rate is implemented with the use of induction heating. Using a gas analyzer the concentration of gases during the gas hydrate combustion has been measured. Comparison of different ways of combustion allows optimizing the combustion efficiency of gas hydrates.

Thermodynamic Features of the Intensive Formation of Hydrocarbon Hydrates

This paper presents the results of a study on the influence of pressure and temperature of the gas–water medium on the process of hydrocarbon gas hydrate formation occurring at the phase interface. Herein, a mathematical model is proposed to determine the optimum ratios of pressure, gas temperatures, water, and gas bubble sizes in the bubbling, gas ejection, or mixing processes. As a result of our work, we determined that gas hydrate in these processes is formed at the gas–water interface, that is, on the boundary surface of gas bubbles. Moreover, there is a gas temperature range where the hydrate formation rate reaches its maximum. These study findings can be used to optimize various technological processes associated with the production of gas hydrates in the industry.

Gas Hydrate Combustion in Five Method of Combustion Organization

Experiments on the dissociation of a mixed gas hydrate in various combustion methods are performed. The simultaneous influence of two determining parameters (the powder layer thickness and the external air velocity) on the efficiency of dissociation is studied. It has been shown that for the mixed hydrate, the dissociation rate under induction heating is 10–15 times higher than during the burning of a thick layer of powder, when the combustion is realized above the layer surface. The minimum temperature required for the initiation of combustion for different combustion methods was studied. As the height of the sample layer increases, the rate of dissociation decreases. The emissions of NO_x and CO for the composite hydrate are higher than for methane hydrate at the same temperature in a muffle furnace. A comparison of harmful emissions during the combustion of gas hydrates with various types of coal fuels is presented. NO_x concentration as a result of the combustion of gas hydrates is tens of times lower than when burning coal fuels. Increasing the temperature in the muffle furnace reduces the concentration of combustion products of gas hydrates.

Gas hydrates in sustainable chemistry

This review includes the current state of the art understanding and advances in technical developments about various fields of gas hydrates, which are combined with expert perspectives and analyses.

Advancing Hazard Assessment of Energy Accidents in the Natural Gas Sector with Rough Set Theory and Decision Rules

The impacts of energy accidents are of primary interest for risk and resilience analysts, decision makers, and the general public. They can cause human health and environmental impacts, economic and societal losses, which justifies the interest in developing models to mitigate these adverse outcomes. We present a classification model for sorting energy accidents in the natural gas sector into hazard classes, according to their potential fatalities. The model is built on decision rules, which are knowledge blocks in the form of “if (condition), then (classification to hazard class x)”. They were extracted by the rough sets method using natural gas accident data from 1970–2016 of the Energy-related Severe Accident Database (ENSAD) of the Paul Scherrer Institut (PSI), the most authoritative information source for accidents in the energy sector. This was the first attempt to explore the relationships between the descriptors of energy accidents and the consequence (fatalities). The model was applied to a set of hypothetical accidents to show how the decision-making process could be supported when there is an interest in knowing which class (i.e., low, medium, high) of fatalities an energy accident could cause. The successful use of this approach in the natural gas sector proves that it can be also adapted for other energy chains, such as oil and coal.

Numerical Study on Gaseous CO2 Leakage and Thermal Characteristics of Containers in a Transport Ship

This study investigates numerically gaseous CO2 leakage characteristics inside the containers of a transport ship and examines thermal effects on the structural damage that might happen in the containers. First, with consideration of the phase change, the ejected mass flow rate was estimated using the commercial code of DNV PHAST. Based on this estimated mass flow rate, we introduced an effective area model for accounting for the fast evaporation of liquefied CO2 occurring in the vicinity of a crack hole. Using this leakage modeling, along with a concept of the effective area, the computational fluid dynamics (CFD) simulations for analyzing transient three-dimensional characteristics of gas propagation in a confined space with nine containers, as well as the thermal effect on the walls on which the leaking gas impinges, were conducted. The commercial code, ANSYS FLUENT V. 17.0, was used for all CFD simulations. It was found that there are substantial changes in the pressure and temperature of the gas mixture for different crack sizes. The CO2 concentration at human nasal height, a measure of clear height for safety, was also estimated to be higher than the safety threshold of 10% within 200 s. Moreover, very cold gas created by the evaporation of liquefied CO2 can cool the cargo walls rapidly, which might cause thermal damage.