Thermodynamic Analysis of Full Scale Baseload LNG Chain

The world’s growing energy demand and the need for low-carbon energy sources are key factors that have made natural gas (NG) an attractive energy source compared to other available fossil fuels (i.e. coal and oil). Being the most feasible NG transportation method over long distances, the liquefied NG (LNG) demand is significantly increasing. The LNG supply chain, consisting of production, liquefaction, shipping, and regasification, is, however, an energy-intensive and thereby emission intensive process. Therefore, the appropriate LNG production with least energy consumption and maximum energy efficiency is of high importance. Thus, optimization of LNG chains is essential from both economic and sustainability point of view. Amongst energy efficiency optimization approaches, exergy analysis, based on the second law of thermodynamics, is a powerful tool that has been widely used to quantify exergy destructions and to determine exergy efficiencies and thereby, identify process improvement opportunities. In this thesis work, rigorous and detailed exergy analysis was performed on an entire baseload LNG chain that was simulated using ProMax® and Aspen Plus® simulation software for the delivery of 439 million standard cubic feet per day (MMSCFD). A comparison of the losses across the various units with and without utilities was performed, and optimization opportunities within the chain were identified. Findings of this study revealed that the LNG chain under consideration is associated with total loss of near 647 MW and 1054 MW during holding and loading operation modes, respectively. The main contributor to the exergy loss was found to be the utility section accounting for 61% of the total exergy loss. Within the LNG process, significant amounts of losses were found to occur in the sulfur recovery units, liquefaction unit, and sweetening processes; accounting for 38%, 30% and 24% of the total exergy loss, respectively. The compressors and their drivers (GTs), stream generators, LNG flashing and storage, columns (absorbers, distillations) and heat exchangers were found to be the main exergy consumers

Detailed exergy analysis of full scale LNG plant

Sustainability is one of the major challenges faced by the industrial sector as it is driven by both environmental and economic factors. Energy demands are increasing and, to date, most of the supply is generated via fossil-fuel combustion, such as coal, gas or oil. However, these processes release greenhouse gases, mainly CO2, that contribute to global warming and other environmental issues. Of the three fossil fuels, for a given amount of energy released, natural gas produces the least amount of CO2, making it the most vital energy source. The most practical way of transporting this natural gas over long distances is via liquefaction. However liquefied natural gas (LNG) plants consume substantial amounts of energy; thus, releasing significant amount of CO2. Therefore, enhancing the efficiencies of LNG plants is essential especially for large producer such as Qatar. As of today, Qatar is the largest producer of LNG in the world, with a capacity of near 78 Million tons per annual (MTA). Since the LNG industry in Qatar is a major contributor to the country's economy and development, there is a continuous need to improve and optimize existing LNG systems to extract more value out of them. Optimization of such complex system is; however, not a straight forward technique requiring different expertise ranging from engineering/process oriented insights to mathematical and thermodynamics techniques. Thus, it is deemed essential to identify plant sections that must be given priorities for optimization. This requires quantifying losses and efficiencies and one of the effective tools is exergy analysis. Identifying the areas of exergy losses within LNG plants emphasizes the areas where optimization is necessary. This project aims to foster the transition to cleaner LNG plants that operate more efficiently, in terms of energy consumption, towards an active contribution to the protection of the environment. The primary focus of the study is to identify exergy losses across a baseload LNG plant producing more than 3 MTA of LNG. In this research, a rigorous and detailed exergy analysis was performed on an entire actual LNG process that was simulated using ProMax® and Aspen Plus® simulation software. In order to carry out the thermodynamic analysis, exergy loss across each component of the entire plant was determined. Exergy analysis was not limited to process units, as it was extended to quantify exergy loss across the utility section. Results revealed that the main contributors to the exergy loss are the utility section, accounting for 49% of the total exergy loss. Within the LNG process, significant amounts of losses were found to occur in the liquefaction, sweetening and sulfur recovery units; corresponding for 37%, 30% and 21% of the total exergy loss, respectively. Components responsible for the highest exergy consumption were also highlighted, with the main consumers being the compressors and their drivers, stream generators, LNG flashing and storage, columns (absorbers, distillations) and heat exchangers. The contribution to the total exergy loss provided some insight on locations where improvements are needed to translate into more environmental and energy benefits. For example, most of the losses within the liquefaction section was attributed to compressors and the drivers responsible for the generation of the required shaft work; almost 19 MW exergy loss in the gas turbine corresponds to 1 MW exergy loss in the associated compressor. Thus, significant energy savings can be achieved via minimizing the compression energy. *Corresponding author. +974 44034148 Eamil address: [email protected] (E. Al-musleh) References [1] «2016 World LNG Report - International Gas Union,» Chevron, USA2016, Available: www.igu.org/download/file/fid/2123.qscienc

Study on boil-off gas (Bog) minimization and recovery strategies from actual baseload lng export terminal: Towards sustainable lng chains

10.3390/en14123478Energies1412347

Solar co-production of samarium and syngas via methanothermal reduction of samarium sesquioxide

This paper reports the thermodynamic analysis of the solar methanothermal reduction of Sm2O3 for the co-production of Sm and syngas in (a) Sm-Syngas open cycle, and (b) Sm-Syngas closed cycle. As per the chemical thermodynamic equilibrium modeling, the conversion of Sm2O3 into Sm increase with the increase in the CH4/Sm2O3 ratio and 100% conversion is possible at 2528 K if CH4/Sm2O3 ratio is equal to 3 is used. Exergy efficiency analysis of both open and closed cycles indicate that the QSm2O3-reduction, Qsolar, Qre-radiation, and Qquench increases with the increase in the CH4/Sm2O3 ratio. Likewise, WFC-Ideal-1, QFC-Ideal-1, and HHVsyngas-1 also increases with the upsurge in the CH4/Sm2O3 ratio. Similar observations were realized in case of Sm-Syngas closed cycle. The ?exergy (33.91%) and ?solar-to-fuel (45.93%) of the Sm-Syngas open cycle was observed to be maximum in case of CH4/Sm2O3 ratio = 3. As one of the applications, Sm was utilized toward splitting of H2O and CO2 together for the production of syngas via Sm-Syngas closed cycle. At similar operating conditions, the ?exergy-closed (45.22%) and ?solar-to-fuel-closed (61.24%) of the Sm-Syngas closed cycle was observed to be higher as compared to the Sm-Syngas open cycle. Furthermore, it was observed that, these efficiency values can be increased significantly due to the utilization of higher values of C and recycling of the heat rejected by the quench unit and H2O/CO2 splitting reactor.The authors gratefully acknowledge the financial support provided by the Qatar University Internal Grant ( QUUG-CENG-CHE-14 ? 15-10 ).Scopu