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LNG a clean fuel -the underlying potential to improve thermal efficiency LNG a clean fuel -the underlying potential to improve thermal efficiency
Abstract
The presence of sulphur in marine fuel oil relates to health and environmental concerns, as the respective combustion generates sulphur dioxide (SO2). The only method to control this SO2 generation is to limit the quantity of sulphur in the fuel. Shipping activities, although not the main source, contribute around 13% of the total anthropogenic SO2 IMO-3GHG [2015. Third IMO Greenhouse Gas Study, 3rd ed. London: International Maritime Organisation]; on a positive note, this is expected to reduce after the worldwide implementation of 0.5% sulphur regulation for marine fuel. One of the accepted methods to comply with the regulatory criteria is the use of alternate fuel, i.e. liquefied natural gas (LNG). The analysis in hand discusses the potential benefits of LNG as a marine fuel.
The technical limitation associated with the formation of sulphuric acid (H2SO4) is directly related to its Dew point, as it condenses below 160°C and causes acidic corrosion of machinery components. The prevalent combustion-based systems are maintaining a safe and economical exhaust gas range between 150°C and 170°C. If the exhaust gas temperature is higher than 170°C excessive heat is lost, which makes the plant inefficient; in contrast, if the temperature drops below 150°C there is the possibility of corrosion damage to the equipment. Considering that LNG is absolutely free from sulphur contamination, it can be used to overcome this technical limitation and add to the overall thermal efficiency due to the availability of increased operating range.
... In addition to reducing different types of pollutants, they pay attention to possible methane emissions and state that the use of LNG should be supported with other efficiency-enhancing methods in line with the aim of decarbonization procedures. Sharma et al. (2020) revealed the possible benefits of the use of LNG as a marine fuel and examined some technical limitations regarding the risk of the creation of sulphuric acid and corrosion for contribution to overall thermal efficiency. ...
In this study, environmental and economic examinations of Liquefied Natural Gas (LNG) investments are conducted. A year-long noon report data is received from a container ship and LNG conversion is performed. Savings from both the fuel expenses and the amount of the emissions are calculated and presented. To eliminate the fuel consumption uncertainties in future operation periods of the stated ship, different scenarios that simulate various fuel consumption statuses are created and analyzed within the Monte Carlo Simulation method. Lastly, calculations are made with two different time prices, approx. one and half year apart. As a result of the analyses, LNG can provide high environmental benefits since it reduces 99% for SOx, 95% for PM10, 95% for PM2.5, 41% for CO2, and 82% for NOx, respectively. It is also determined that LNG investment is highly sensitive to fuel prices. In addition, the LNG usage can be beneficial for maritime companies in terms of marine policies such as paying carbon tax based on the expanding European Union Emission Trade System to maritime business. Still, it needs supportive carbon reduction method to comply with the maritime decarbonization strategy. This study has great importance in that the economic analysis way presented is able to adapt any alternative fuel system conversion for the maritime industry.
... In recent years, in order to reduce the emission of ship exhaust pollutants, the International Maritime Organization (IMO) has put forward increasingly strict ship exhaust emission policies [26], in which clean fuels such as ammonia [27], LNG [28], and hydrogen [29] keep emerging. Frankl et al. [30] and Mounaim-Rousselle et al. [31] proposed that the combustion of ammonia fuel can achieve "zero carbon" emission, making it undoubtedly a more ideal carbon-free fuel for CO2 carriers. ...
A CO 2 boiled off gas (CO 2 BOG) reliquefaction system using liquid ammonia cold energy is designed to solve the problems of fuel cold energy waste and the large power consumption of the compressor in the process of CO 2 BOG reliquefaction on an ammonia-powered CO 2 carrier. Aspen HYSYS is used to simulate the calculation, and it is found that the system has lower power consumption than the existing reliquefaction method. The temperature of the heat exchanger heater-1 heat flow outlet node (node C-4) is optimised, and it is found that, with the increase of the node C-4 temperature, the power consumption of the compressor gradually increases, and the liquefaction fraction of CO 2 BOG gradually decreases. Under 85% conditions, when the ambient temperature is 0°C and the temperature of node C-4 is -9°C, the liquid fraction of CO 2 BOG reaches the maximum, which is 74.46%, and the power of Compressor-1 is the minimum, which is 40.90 kW. According to this, the optimum temperature of node C-4 under various working conditions is determined. The exergy efficiency model is established, in an 85% ship working condition with the ambient temperature of 40°C, and the exergy efficiency of the system is the maximum, reaching 59.58%. Therefore, the CO 2 BOG reliquefaction system proposed in this study could realise effective utilisation of liquid ammonia cold energy.
... This avoids the chemical reaction that Sulfur Oxides (SOx) has in ship's emission, which is formed when a fuel containing sulfur is burnt in the presence of oxygen during combustion. 8 This provides higher flexibility and freedom to use exhaust gas energy, utilizing exhaust gas boiler and Organic Rankine cycle. ...
This study reports the energy specific air emissions from a diesel-cycle high pressure injection dual fuel engine for operation on liquefied natural gas and heavy fuel oil. An experiment at sea was performed onboard a bulk carrier during commercial voyages, to measure the efficiency of the engine and to measure air emissions relevant to air pollution and climate impact for operation on both fuels. The measurements showed that the energy conversion efficiency of the engine was higher for operation on liquefied natural gas because its lower NOx emissions permitted the use of a higher effective compression ratio whilst meeting the same NOx emissions level. The results showed that the climate impact for operation on heavy fuel oil was 2.1–2.3 times higher than for liquefied natural gas at 50% load, if considering only the emissions occurring at the engine. Analysis of the air emissions for their individual contributions to climate impacts suggested that black carbon had the strongest climate impact of all air emissions in the case of operation on heavy fuel oil. For operation on liquefied natural gas, CO 2 had the strongest individual climate impact amongst the air emissions from the engine.
... The relevant Fit for 55 legislation measures that directly affect shipping are: (1) EU ETS, (2) Therefore, an innovative top-down approach and algorithm has been developed to estimate effect of OPEX as part of the measures imposed by "Fit for 55", which are a CO 2 penalty (inclusion of shipping in EU ETS), fuel maritime tax, effect of imports at intraand extra-EU level and projections of fuel costs of conventional fossil fuels and alternative green fuels (such as hydrogen, ammonia, methanol, biogas, and bioethanol) as well as bridging fuels such as Liquefied Natural Gas (LNG) and Liquefied Petroleum Gas (LPG). Apart from the reduced GHG emissions, LNG can reduce the amount of SOx emissions, which is particularly important for Sulphur Emission Control Areas (SECA) [7]. The most popular alternative fuels in shipping are examined. ...
The recent inclusion of shipping in the Fit for 55 legislation package will have large knock-on effects on the industry and consequently on end consumers. The present paper presents an innovative top-down methodology, the MSF455 model, which estimates the new vessel Operational Expenditure (OPEX) as per the provisions of the Fit for 55 package and various scenarios based on carbon tax, penalty allowances, maritime fuel tax and effect. The methodology is presented and tested against six scenarios that are based on Det Norske Veritas’s (DNV) fuel maritime projections. The model illustrates that the distinction between intra-EU and extra-EU penalty allowance creates a large disparity and thus reduction in the competitiveness of goods (produced and transported).
... Potentially it can provide a higher overall thermal efficiency and contains a negligible amount of sulfur. This prevents the chemical reaction of sulfur to sulfur-oxides (SOx) in the engine emissions, which typically takes place when a fuel containing sulfur is burnt in the presence of oxygen during combustion [5]. LNG needs to be handled and stored as a cryogenic fluid. ...
Liquefied natural gas (LNG) is a well-known fuel consisting mainly of methane as main component of natural gas and is produced by liquefying the natural gas from gas fields at a temperature of 111 K. Since LNG has a very low sulfur content it significantly reduces the emission of harmful pollutants compared to other fossil fuels. As it has a high calorific value and is chemically stable under normal usage conditions it is extensively used as fuel for large engines for ships or power plants. However, in recent years methane has been identified as green-house gas which has a high global warming potential. Therefore, it is necessary to reform LNG so it emits less pollution and has a higher combustion efficiency in engines. This can be done by enriching LNG in a slush state with hydrogen molecules during its phase transition. The introduction of the hydrogen enrichment into slush LNG involves various interesting thermo-fluid dynamics phenomena which are not well understood yet. In the current review paper, an innovative method for the production process of hydrogen enriched slush LNG is introduced and the related thermo-fluid dynamics are described in detail with an emphasis on the promising potential as a fuel for LNG engines.
This research presents a review and classification of the published work related to applied risk analysis and risk management in the maritime liquefied natural gas (LNG) sector from 2000 to 2023. The papers are categorised under two primary contexts. The first is the risk analysis theory context which represents the classification with respect to (w. r. t.) the used risk analysis method, the used risk analysis tool, and the objective of risk analysis, whereas the second is the presented case in the risk analysis context which represents the classification w. r. t. the analysed LNG ship type, the analysed operation, and the inclusion level of human error in risk analysis. The above process has revealed that the interest in this domain of research has increased significantly during the past decade. In addition, the use of dynamic risk analysis (DRA) tools, and the inclusion of human error in the risk analysis model have been observed significantly in the past five years, in particular, for modelling the risk of external LNG transfer operations. It is concluded that the inclusion of the effect of human and organisational factors (HOFs) in risk analysis, and the use of DRA methods for modelling the risk of the daily routine operations of the complex maritime LNG systems can improve the management of the operational risk of these systems.
Aiming at the problems that the fuel releases a lot of cold energy and the refrigerated containers consume a lot of electricity on large LNG powered container ships, a set of cold energy cascade utilization scheme that mainly uses LNG cold energy for refrigerated containers is designed. The simulation software Aspen HYSYS is used to establish and simulate the process of the ship’s cold energy cascade utilization system under five different working conditions, and the main parameters of the key nodes are obtained, according to the established exergy efficiency model, the exergy efficiency of the main equipment and the whole system is solved. Under the five working conditions, the maximum exergy efficiency of the refrigerated container system before optimization is 24.54%, at this time, the exergy efficiency of the entire cold energy utilization system is 24.86%. With the goal of improving the exergy efficiency of the entire system, using a hierarchical optimization method, the key parameters affecting the exergy efficiency of each cold energy utilization module are analyzed and optimized respectively, and the optimal operating parameters of different cold energy utilization module were determined. So as to realize the optimization of the whole cold energy cascade utilization system. The results show that the exergy efficiency of the optimized LNG cold energy cascade utilization system for ships under five working conditions is improved, under the 65% working condition, the exergy efficiency of the optimized refrigerated container system is 27.69%, and the exergy efficiency of the whole cold energy utilization system is 28.04%, which are increased by 3.15% and 3.18% respectively. Which proves that the LNG cold energy cascade utilization system can realize the effective utilization of LNG cold energy.
With the aim of considering the problem of excess fuel cold energy and excessive power consumption of refrigerated containers on large LNG-powered container ships, a new utilisation method using LNG-fuelled cold energy to cool refrigerated containers in cargo holds is proposed in this study, and the main structure of the cold storage in the method is modelled in three dimensions. Then, combined with the different conditions, 15 different combination schemes of high temperature cold storage and low temperature cold storage are designed to utilise the cold energy of LNG fuel, the exergy efficiency and cold energy utilisation rate calculation model of the system is established. The simulation tool ‘Aspen HYSYS’ is used to simulate and calculate the exergy efficiency and cold energy utilisation rate of the system under 15 combinations, verifying the feasibility of the scheme. According to the characteristics of such a ship’s cross-seasonal navigation routes and the number of refrigerated containers loaded in different ports, the combination schemes of the number of low-temperature cold storage and high-temperature cold storage are selected. Thus, the average exergy efficiency and cold energy utilisation rate of the whole line is obtained, which proves that LNG-powered container ships could effectively utilise the cold energy of LNG. By calculating the total electric energy consumed by refrigerated containers on the whole sailing route, before and after the adoption of the LNG cold energy method, it is found that the adoption of this new method can promote the realisation of energy saving and emission reduction of ships.
Knowledge of the sulfuric acid dewpoint temperature (ADT) is important in many combustion processes. An effective ADT sensor can be made by cooling a glass surface and measuring its surface conductivity and temperature with a pair of precious metal electrodes, one of which is a Pt-PtRh thermocouple. The main purpose is to prevent ductwork corrosion whilst maintaining good thermal efficiency, but a knowledge of the relevant physical chemistry allows the sulfur trioxide and sulfuric acid concentrations in the flue gases to be derived from the ADT.
This book provides a thorough development of the second law of thermodynamics (featuring the entropy-production concept), an up-to-date discussion of availability analysis (including an introduction to chemical availability), and a sound description of the application areas. Topics covered include control volume energy analysis, vapor power systems, gas power systems, thermodynamic relations for simple compressible substances, nonreacting ideal gas mixtures and psycrometrics, reacting mixtures and combustion, and chemical and phase equilibrium.
An extended number of international and/or national policies/regulations call for major improvements in contemporary energy consumption patterns (energy efficiency). A faster transition to sustainable energy production, as well as the introduction of various measures to improve the maritime industry’s environmental performance is also included in similar high level policy initiatives, with the establishment of Sulphur Emission Control Areas (SECAs) by the International Maritime Organization (IMO). One of the most prominent ways forward to achieve a more “environmental-friendly footprint” for those vessels engaged in maritime transport activities is to expand the use of Liquefied Natural Gas (LNG). Despite being of fossil origin, LNG is considered to be an important step toward cleaner shipping, given the better properties of the related exhaust gases when it is used as a marine fuel of internal combustion engines. The analysis at hand will discuss the development of a strategy for smoother and more efficient use of LNG as a fuel for transport needs in the Baltic Sea Region (BSR), with the aim of enabling “blue transport corridors”. This will be accomplished by investigating the related transport flows and LNG infrastructure developments; the creation of a wider in scope value chain that incorporates all transport modalities and industries that use natural gas today is also envisioned as the next step of research. This activity is a deliverable of the “Go LNG project”. Another important task within the same project is to provide stakeholders and other interested parties with a knowledge base of the most influential policies/regulations and technological standards in relation to LNG applications, including the cataloguing and short description of well-functioning business models and solutions already available.
Cited By :1884, Export Date: 2 September 2017
Solving the problem of volume is often the key to successful solid waste management. The low bulk density of solid waste requires costly storage containers at the point of generation, greatly influences the cost and difficulty of collection and handling, and is the primary factor in setting the cost and scale of landfill and other ultimate disposal operations.
An advanced, practical approach to the first and second laws of thermodynamics. Advanced Engineering Thermodynamics bridges the gap between engineering applications and the first and second laws of thermodynamics. Going beyond the basic coverage offered by most textbooks, this authoritative treatment delves into the advanced topics of energy and work as they relate to various engineering fields. This practical approach describes real-world applications of thermodynamics concepts, including solar energy, refrigeration, air conditioning, thermofluid design, chemical design, constructal design, and more. This new fourth edition has been updated and expanded to include current developments in energy storage, distributed energy systems, entropy minimization, and industrial applications, linking new technologies in sustainability to fundamental thermodynamics concepts. Worked problems have been added to help students follow the thought processes behind various applications, and additional homework problems give them the opportunity to gauge their knowledge. The growing demand for sustainability and energy efficiency has shined a spotlight on the real-world applications of thermodynamics. This book helps future engineers make the fundamental connections, and develop a clear understanding of this complex subject. Delve deeper into the engineering applications of thermodynamics. Work problems directly applicable to engineering fields. Integrate thermodynamics concepts into sustainability design and policy. Understand the thermodynamics of emerging energy technologies. Condensed introductory chapters allow students to quickly review the fundamentals before diving right into practical applications. Designed expressly for engineering students, this book offers a clear, targeted treatment of thermodynamics topics with detailed discussion and authoritative guidance toward even the most complex concepts. Advanced Engineering Thermodynamics is the definitive modern treatment of energy and work for today's newest engineers.
In this paper, a new approach is proposed for simplifying the calculation of flue gas specific heat and specific exergy value in one formulation depending on fuel chemical composition. Combustion products contain different gases such as CO2, SO2, N2, O2, H2O and etc., depending on the burning process. Specific heat and exergy of the flue gas differ depending on the chemical composition of fuels, excess air ratio and gas temperature. Through this new approach, specific heat and specific exergy value of combustion products can be estimated accurately in one formulation by entering the chemical composition of fuels, excess air ratio and gas temperature. The present approach can be applied to all carbon based fuels, especially biomass, fossil fuels and fuel mixtures for co-combustion and is so suitable for practical estimation of flue gas specific heat and specific exergy values provided that the fuel chemical composition is given.
Corrosion failures due to condensing flue gases containing H2O, SO3, NOx and HCl still occur more often than might be expected. The corrosion failures can be of several types: general corrosion, pitting attack and stress corrosion cracking (SCC). The chemistry of condensing gases is discussed, and some examples of corrosion in large-scale installations are presented, including blast stoves for steel production, heat recovery steam generators, and waste incineration boilers. The use of thermal insulation inside boiler casings can result in nitrate SCC when the flue gas contains high concentrations of NOx. Nitric acid from flue gas can react with carbon steel and insulation material forming ammonium nitrate and calcium nitrate. Both materials have hygroscopic properties and are very corrosive, even above the water dewpoint of the gases.
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