scholarly journals Simulation of Dual Mixed Refrigerant Natural Gas Liquefaction Processes Using a Nonsmooth Framework

Processes ◽  
2018 ◽  
Vol 6 (10) ◽  
pp. 193 ◽  
Author(s):  
Matias Vikse ◽  
Harry Watson ◽  
Truls Gundersen ◽  
Paul Barton
Keyword(s):  
Natural Gas ◽  
Heat Exchangers ◽  
Degrees Of Freedom ◽  
Large Scale ◽  
Aspen Plus ◽  
Large Temperature ◽  
Scale Production ◽  
Simulation Tool ◽  
Natural Gas Liquefaction ◽  
Feasible Solutions

Natural gas liquefaction is an energy intensive process where the feed is cooled from ambient temperature down to cryogenic temperatures. Different liquefaction cycles exist depending on the application, with dual mixed refrigerant processes normally considered for the large-scale production of Liquefied Natural Gas (LNG). Large temperature spans and small temperature differences in the heat exchangers make the liquefaction processes difficult to analyze. Exergetic losses from irreversible heat transfer increase exponentially with a decreasing temperature at subambient conditions. Consequently, an accurate and robust simulation tool is paramount to allow designers to make correct design decisions. However, conventional process simulators, such as Aspen Plus, suffer from significant drawbacks when modeling multistream heat exchangers. In particular, no rigorous checks exist to prevent temperature crossovers. Limited degrees of freedom and the inability to solve for stream variables other than outlet temperatures also makes such tools inflexible to use, often requiring the user to resort to a manual iterative procedure to obtain a feasible solution. In this article, a nonsmooth, multistream heat exchanger model is used to develop a simulation tool for two different dual mixed refrigerant processes. Case studies are presented for which Aspen Plus fails to obtain thermodynamically feasible solutions.

scholarly journals Activated Carbon from Winemaking Waste: Thermoeconomic Analysis for Large-Scale Production

Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6462
Author(s):  
Isaac Lorero ◽  
Arturo J. Vizcaíno ◽  
Francisco J. Alguacil ◽  
Félix A. López
Keyword(s):  
Activated Carbon ◽  
Heat Exchangers ◽  
Large Scale ◽  
Activated Carbons ◽  
Hydrothermal Carbonization ◽  
Thermodynamic Efficiency ◽  
Physical Activation ◽  
Scale Production ◽  
Production Scale ◽  
Costs Analysis

An activated carbon manufacturing process from winemaking waste is analyzed. In that way, vine shoots conversion is studied as a basis for plant designing, and mass and energy balances of hydrothermal carbonization and physical activation are fulfilled. To develop an energy-integrated plant, a network of heat exchangers is allocated to recover heat waste, and a cogeneration cycle is designed to provide electricity and remaining heat process demands. Furthermore, thermoeconomic analysis is applied to determine the thermodynamic efficiency and the economic viability of the plant. Energy balance indicates that heat exchangers energy integration covers 48.9% of the overall demands by crossing hot and cold streams and recovering heat from residual flue gas. On the other hand, the exergy costs analysis identifies combustion of pruning wood as the main source of exergy destruction, confirming the suitability of the integration to improve the thermodynamic performance. Attending to economic costs analysis, production scale and vineyard pruning wood price are identified as a critical parameter on process profitability. With a scale of 2.5 ton/h of pruning wood carbonization, a break-event point to compete with activated carbons from biomass origin is reached. Nevertheless, cost of pruning wood is identified as another important economic parameter, pointing out the suitability of wet methods such as hydrothermal carbonization (HTC) to treat them as received form the harvest and to contribute to cutting down its prices.

Offshore Adaptability of the CO2 Pre-Cooling Dual Nitrogen Expander Natural Gas Liquefaction Process

2012 ◽  
Vol 608-609 ◽  
pp. 1369-1374 ◽  
Author(s):  
Jian Lu Zhu ◽  
Yu Xing Li ◽  
Wu Chang Wang ◽  
Huan Huan Sheng ◽  
Yong Hao Liu ◽  
...  
Keyword(s):  
Natural Gas ◽  
Large Scale ◽  
Point Of View ◽  
Gas Temperature ◽  
Natural Gas Liquefaction ◽  
Liquefaction Process

CO2 pre-cooling dual nitrogen expander liquefaction process was proposed for the LNG-FPSO unit and compared with propane pre-cooling dual nitrogen expander process and mixed refrigerant pre-cooling nitrogen expander process by simulation. Gas property sensitivity of the process was analyzed from the thermodynamic point of view. And offshore adaptability of the process was evaluated. The results show that the process will be suitable for mid to large-scale LNG production in severe sea condition. And it will be not sensitive to the changes of gas temperature, pressure and composition.

scholarly journals Thermodynamic, Economic and Environmental Analyses of Ammonia-Based Mixed Refrigerant for Liquefied Natural Gas Pre-Cooling Cycle

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1298
Author(s):  
Ray Soujoudi ◽  
Randall Manteufel
Keyword(s):  
Natural Gas ◽  
Degrees Of Freedom ◽  
Specific Energy Consumption ◽  
Liquefied Natural Gas ◽  
Coefficient Of Performance ◽  
Large Temperature ◽  
Base Case ◽  
Cooling Cycle ◽  
Potential Index ◽  
Economic Analyses

Analyzing the entire liquefaction cycle, using a large temperature span with many degrees of freedom, may not always result in a practical solution. The objective of this paper is to investigate the feasibility of using an environmentally friendly refrigerant compound, ammonia, in the mixed refrigerant (MR) for the liquefied natural gas (LNG) pre-cooling cycle through thermodynamic performance, economic analyses and environmental impact. Fifteen cases studies within three major mixed refrigerants groups of MR-1, MR-2 and MR-3 were developed by adding ammonia to various molar compositions of lighter and heavier hydrocarbons. The thermodynamic analysis shows increasing ammonia’s concentrations in the mixed refrigerant by 10% had the largest enhancement on coefficient of performance (COP) of MR-1 by 0.67 and decreased the specific energy consumption of the pre-cooling cycle by 128 kJ/kg compared to the base case. Economic analyses revealed that the mixed refrigerant MR-1, with ammonia, methane, ethane and propane, benefited the most from higher concentration of ammonia in the mixed refrigerant, which resulted in both lower annual capital and operational costs by $2.52 MM and $3.67 MM, respectively. Lastly, reducing the methane concentration in MR and replacing it with ammonia, decreased the amount of refrigerant leakage through compressor’s seals and reduced the global warming potential index (GWPI) of mixed refrigerant up to 24.3%.

scholarly journals ENERGY EFFICIENT NATURAL GAS LIQUEFACTION TECHNOLOGIES IN LOW-TONNAGE PLANTS: UKRAINE’S PROSPECTS

2020 ◽  
pp. 7-18
Author(s):  
H.V. Zhuk ◽  
O.I. Pyatnichko ◽  
L.R. Onopa ◽  
Yu.V. Ivanov
Keyword(s):  
Natural Gas ◽  
Energy Efficient ◽  
Point Of View ◽  
Small Scale ◽  
Refrigeration Cycle ◽  
Scale Production ◽  
Refrigeration Equipment ◽  
Natural Gas Liquefaction ◽  
Production Wells ◽  
Alternative Sources

Along with the growth of natural gas consumption in the world, small-scale production of liquefied natural gas (LNG) is developing at a faster pace. It opens up the possibility of LNG obtaining and transporting as a commodity product at remote from gas networks fields or wells, and also at low-production wells and alternative sources of methane-containing gas. The development of modern technologies for natural gas liquefaction has been studied and the liquefaction cycles used in the low-tonnage scale have been classified. In Ukraine, rather large reserves of natural gas are found in small as well as depleted fields, so the problem of energy efficient technologies for liquefaction and transportation of their hydrocarbon resources creating is of particular relevance. For the development of such low-resource fields, liquefaction units operating on the compression-throttle cycle are most suitable. Energy efficient technological schemes of natural gas liquefaction plants have been developed: in the high-pressure throttle-ejector cycle with pre-cooling using a propane refrigerating machine and in the middle-pressure throttle cycle with ethane refrigeration cycle and the recovery of part of the liquefied gas. Optimum parameters of the refrigeration cycle and the whole plant are obtained from the point of view of minimizing the specific energy costs. The advantages of the proposed throttle schemes are simplicity, reliability, that are results from the use of standard compressor and refrigeration equipment, and energy efficiency of 0.5 kWh/kg LNG, which is sufficiently high for low-tonnage LNG production. Ref. 20, Fig. 6, Tab.1.

scholarly journals On the hydrodynamics of unstable excitations

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Olalla A. Castro-Alvaredo ◽  
Cecilia De Fazio ◽  
Benjamin Doyon ◽  
Francesco Ravanini
Keyword(s):  
Bound States ◽  
Degrees Of Freedom ◽  
Large Scale ◽  
Scattering Matrix ◽  
Large Temperature ◽  
Analytic Structure ◽  
Quantum Field Theories ◽  
Unstable Particles ◽  
Hydrodynamic Approach ◽  
Stable Particles

Abstract The generalized hydrodynamic (GHD) approach has been extremely successful in describing the out-of-equilibrium properties of a great variety of integrable many-body quantum systems. It naturally extracts the large-scale dynamical degrees of freedom of the system, and is thus a particularly good probe for emergent phenomena. One such phenomenon is the presence of unstable particles, traditionally seen via special analytic structures of the scattering matrix. Because of their finite lifetime and energy threshold, these are especially hard to study. In this paper we apply the GHD approach to a model possessing both unstable excitations and quantum integrability. The largest family of relativistic integrable quantum field theories known to have these features are the homogeneous sine-Gordon models. We consider the simplest non-trivial example of such theories and investigate the effect of an unstable excitation on various physical quantities, both at equilibrium and in the non-equilibrium state arising from the partitioning protocol. The hydrodynamic approach sheds new light onto the physics of the unstable particle, going much beyond its definition via the analytic structure of the scattering matrix, and clarifies its effects both on the equilibrium and out-of-equilibrium properties of the theory. Crucially, within this dynamical perspective, we identify unstable particles as finitely-lived bound states of co-propagating stable particles of different types, and observe how stable populations of unstable particles emerge in large-temperature thermal baths.

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