A Micro Cogeneration System with LNG Cold Utilization-part 2: Exergy Analyses

This paper discusses the performances of LNG vaporizers usually used in practice, it is very import to improve the functions of LNG vaporizer because the liquefied natural gas (LNG) must be heated and gasified when it is used, then analyses the advantages and disadvantages of these LNG vaporizers. This paper studies and designs creatively a new type of LNG vaporizer which uses a method of flue gas lashing and sending up spray, and puts forward the basic requirements and the design project of this vaporizer. Some techniques such as the gas flow circle unit, the inner and outer cylinders of combustion chamber, the flue gas nozzle of cone, the flue gas circulation, the automatic filling water system and so on are used in this LNG vaporizer. These techniques are creative and advanced, and the authors have had the intellectual property rights. The advantages of this LNG vaporizer are high efficiency, quickly starting up, fast gasified speed, compact structure, saving energy, protecting environment and so on. This LNG vaporizer is suitable for the independent small or middle scale areas which can not be contained into the large natural gas supplying networks for various reasons, the loads fluctuating largely areas in which the natural gas supplied loads are regulated in time, and supplied or stopped frequently, the particular areas in which the special parameters of natural gas must be needed.

Liquefied Natural Gas (LNG) is an important component in meeting the future energy needs of the United States and other industrialized countries. The ability to locate (produce), process, liquefy, transport, and re-gasify stranded natural gas is vital to maintaining a stable long-term natural gas supply necessary for sustained economic growth [1]. Two of the key components in this supply chain are the vaporization of the LNG at the import terminal and the peak shaver trains that liquefy pipe line natural gas, store it and then vaporize the liquid to feed the gas to the pipe line when additional flow is required. This paper outlines a novel approach incorporating a traditional fired heater with waste heat recovery to vaporize LNG at an import terminal or peak shaver train while maintaining a high thermal efficiency. A comparison is made between the new technology and more conventional methods, with emphasis on emissions. Some of the advantages and disadvantages associated with the design and implementation of these systems are explored in this presentation. As a fundamental cannon of ethics, engineers are obligated to address the most efficient and responsible use of resources. The environmental impact of supplying the necessary natural gas energy to industry and consumers is significant. This paper addresses these aspects as considered during the development of the alternative LNG vaporization technology.

Advanced exergy and exergo-economic analyses of a novel combined power system using the cold energy of liquefied natural gas

The synergetic effects of carbon and hydrogen metabolism on the exergy destruction and loss in a coal-to-SNG process

The global demand of liquefied natural gas (LNG) has risen rapidly in recent years for the reasons of energy security and sustainable development. This has led to considerable recent research interests and efforts in the LNG production chain and associated risks in handling, storage, and transport of LNG, largely driven by the intrinsic process safety issues of LNG, potential terrorist threats, and public confidence in LNG safety. This review presents an overview on some recent advances in the LNG value chain, covering upstream gas production and gathering, liquefaction, shipping, and regasification processes. Recent developments in the experimentation and modeling of LNG spills associated with the LNG value chain are then summarized, covering the events following a LNG spill, including LNG pool formation, vapor dispersion, and combustion. The consequent hazards and safety issues are also discussed, with a focus on the methods for improving the safety of personnel, facilities, and ships. The key technical gaps in the related research areas have been identified, and future research directions are outlined.

Assessment of a waste energy recovery (WER) unit for power and refrigeration generation: Advanced thermodynamic examination

Validation of FLACS against experimental data sets from the model evaluation database for LNG vapor dispersion

Effects of high temperature generator pressure on energetic and exergetic performance of double effect series flow type absorption cooling system

Integration of Photovoltaic Technology to Decentralized Liquefied Natural Gas-Fueled Combined-Cooling-Heating-and-Power Plants

Studies of the unavoidable exergy loss rate and analysis of influence parameters for pipeline transportation process

In large air compressor installations consisting of multiple compressors operating continuously, even a small reduction in the inlet air temperature can improve the plant efficiency. Exergy efficiency is more rational than energy efficiency, and exergy analysis is more helpful than energy analysis for locating and evaluating available energy-saving potentials, identifying opportunities for improvements in system design, and establishing cost-effective system maintenance programs. When exergy analysis is performed on a system, thermodynamic imperfections can be quantified as exergy destruction, which represent losses in energy quality. In the present study, a thermodynamic analysis is made on the inlet air cooling system employed in a centrifugal compressor. Exergy input rate, exergy output rate, exergy loss rate, exergy destruction rate, and exergy efficiency were calculated with five different dead state temperatures and five different dead state relative humidities. Sustainability assessment is done by estimating the sustainability based on exergy efficiency.

Compared with conventional natural gas, liquefied natural gas has the advantages of easier storage and transportation, more safety, less indirect investment, better peak regulation, and environmental protection. This paper studies the large-scale cryogenic propane precooled mixed refrigerant (C3MR) liquefied natural gas (LNG) process. The phase equilibrium of the liquefaction process is calculated by the Peng-Robinsonstate equation using ASPEN. A numerical model for the thermal process simulation of the liquefaction process is established by MATLAB. Based on Active X technology, data invocation between software is realized, which overcomes the problem of process variable changes under limited degrees of freedom. The minimum sum of the propane precooling amount for the compressor energy consumption is used as the objective function, the control variate method is used to address the liquefaction process model, and the parameter sensitivity analysis is performed and combined with the exergy analysis. The effects of multiple parameters (e.g., the pressures and temperatures) on the process performance are analyzed and discussed. The results indicate that the combined analysis of the parameter sensitivity and exergy adopted in this paper are able to increase the system performance and reduce the exergy loss of equipment. The maximum reduction of the throttling loss of the process is 60.14%, and the total exergy loss is reduced by 25.8%.

Application of exergy analysis for improving energy efficiency of natural gas liquids recovery processes

Energy and exergy analysis of novel combined cooling and power (CCP) cycles

LNG (Liquefied Natural Gas) shares in the global energy market is steadily increasing. One possible application of LNG is as a fuel for transportation. Stricter air pollution regulations and emission controls have made the natural gas a promising alternative to liquid petroleum fuels, especially in the case of heavy transport. However, in most LNG-fueled vehicles, the physical exergy of LNG is destroyed in the regasification process. This paper investigates possible LNG exergy recovery systems for transportation. The analyses focus on “cold energy” recovery systems as the enthalpy of LNG, which may be used as cooling power in air conditioning or refrigeration. Moreover, four exergy recovery systems that use LNG as a low temperature heat sink to produce electric power are analyzed. This includes single-stage and two-stage direct expansion systems, an ORC (Organic Rankine Cycle) system, and a combined system (ORC + direct expansion). The optimization of the above-mentioned LNG power cycles and exergy analyses are also discussed, with the identification of exergy loss in all components. The analyzed systems achieved exergetic efficiencies in the range of to , which corresponds to a net work in the range of 214 to 380 kJ/kg.