Exergy analysis of two cryogenic air separation processes

Energy ◽  
2010 ◽  
Vol 35 (12) ◽  
pp. 4731-4739 ◽  
Author(s):  
L.V. van der Ham ◽  
S. Kjelstrup
Keyword(s):  
Exergy Analysis ◽  
Air Separation ◽  
Separation Processes

scholarly journals Reply to Variny et al. Comment on “Hamayun et al. Evaluation of Two-Column Air Separation Processes Based on Exergy Analysis. Energies 2020, 13, 6361”

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6445
Author(s):  
Muhammad Haris Hamayun ◽  
Naveed Ramzan ◽  
Murid Hussain ◽  
Muhammad Faheem
Keyword(s):  
Exergy Analysis ◽  
Air Separation ◽  
Separation Processes

This is a reply to the paper by Variny et al. [...]

scholarly journals Evaluation of Two-Column Air Separation Processes Based on Exergy Analysis

Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6361
Author(s):  
Muhammad Haris Hamayun ◽  
Naveed Ramzan ◽  
Murid Hussain ◽  
Muhammad Faheem
Keyword(s):  
Large Scale ◽  
Exergy Analysis ◽  
Separation Process ◽  
Air Separation ◽  
Scale Production ◽  
Exergy Destruction ◽  
Separation Processes ◽  
Distillation Columns ◽  
Operational Conditions ◽  
Destruction Rate

Cryogenic air separation processes are widely used for the large-scale production of nitrogen and oxygen. The most widely used design for this process involves two distillation columns operating at different pressures. This work focuses on the selection of suitable cryogenic air separation process by evaluating seven alternative designs of the two-column air separation process based on detailed exergy analysis. The feed conditions (500 tons/h, and 50% relative humidity of air), product purities (99 mole% for both nitrogen and oxygen), and operational conditions (pressures of both distillation columns) are kept same in all designs. The two cryogenic distillation columns in each configuration are heat-integrated to eliminate the need for external utilities. Steady-state simulation results are used to calculate the exergy efficiency (%) of each equipment as well as its contribution toward the overall exergy destruction rate (kW) of the process. The results show that the compression section is a major source of exergy destruction, followed by the low-pressure column, and the multi-stream heat exchanger. A Petlyuk-like configuration, labeled as C1, provides the lowest exergy destruction rate.

scholarly journals Exergy Analysis of Liquid Nitrogen Power Cycles

2019 ◽  
Vol 201 ◽  
pp. 01004
Author(s):  
Paweł Wojcieszak
Keyword(s):  
Liquid Nitrogen ◽  
Energy Demand ◽  
Power Plants ◽  
Exergy Analysis ◽  
Renewable Energy Sources ◽  
Air Separation ◽  
Direct Expansion ◽  
Separation Processes ◽  
Separation Unit ◽  
Electrical Grid

Nitrogen is by-product from cryogenic air separation processes used for oxygen production for metallurgy and oxygen-enriched combustion purposes. If the gases are delivered from air separation unit (ASU) in liquid phase, liquid nitrogen (LN2) can be used as energy accumulator for stabilization of electrical grid system with large share of renewable energy sources. When the energy demand is high and not enough electricity is generated in power plants, energy accumulated in LN2 may be recovered in a cryogenic power cycle. In this research complete exergy analysis of liquid nitrogen direct expansion cycle and combined direct expansion/Brayton cycle was performed.

scholarly journals Comment on Hamayun et al. Evaluation of Two-Column Air Separation Processes Based on Exergy Analysis. Energies 2020, 13, 6361

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6443 ◽  
Author(s):  
Miroslav Variny ◽  
Dominika Jediná ◽  
Patrik Furda
Keyword(s):  
Exergy Analysis ◽  
Scientific Literature ◽  
Aspen Plus ◽  
Simulation Software ◽  
Air Separation ◽  
Oxygen Production ◽  
Separation Processes ◽  
Aspen Hysys ◽  
Energy Consumption Optimization ◽  
Selection Of

Oxygen production from air belongs to energy-intense processes and, as a result, possibilities for its decrease are a frequent topic of optimization studies, often performed with simulation software such as Aspen Plus or Aspen HYSYS. To obtain veritable results and sound solutions, a suitable calculation method hand in hand with justified assumptions and simplifications should form the base of any such studies. Thus, an analysis of the study by Hamayun et al., Energies 2020, 13, 6361, has been performed, and several weak spots of the study, including oversimplified assumptions, improper selection of a thermodynamic package for simulation and omission of certain technological aspects relevant for energy consumption optimization studies, were identified. For each of the weak spots, a recommendation based on good praxis and relevant scientific literature is provided, and general recommendations are formulated with the hope that this comment will aid all researchers utilizing Aspen Plus and Aspen HYSYS software in their work.

Exergy analysis of cryogenic air separation

1998 ◽  
Vol 39 (16-18) ◽  
pp. 1821-1826 ◽  
Author(s):  
R.L. Cornelissen ◽  
G.G. Hirs
Keyword(s):  
Exergy Analysis ◽  
Air Separation

Exergy Analysis of a Novel Cryogenic Concept for the Liquefaction of Natural Gas Integrated Into an Air Separation Process

2016 ◽  
Author(s):  
S. Tesch ◽  
T. Morosuk ◽  
G. Tsatsaronis
Keyword(s):  
Natural Gas ◽  
Power Consumption ◽  
Exergy Analysis ◽  
Primary Energy ◽  
Separation Process ◽  
Air Separation ◽  
Total Power ◽  
Separation Unit ◽  
Total Power Consumption ◽  
Liquefaction Temperature

The increasing demand for primary energy leads to a growing market of natural gas and the associated market for liquefied natural gas (LNG) increases, too. The liquefaction of natural gas is an energy- and cost-intensive process. After exploration, natural gas, is pretreated and cooled to the liquefaction temperature of around −160°C. In this paper, a novel concept for the integration of the liquefaction of natural gas into an air separation process is introduced. The system is evaluated from the energetic and exergetic points of view. Additionally, an advanced exergy analysis is conducted. The analysis of the concepts shows the effect of important parameters regarding the maximum amount of liquefiable of natural gas and the total power consumption. Comparing the different cases, the amount of LNG production could be increased by two thirds, while the power consumption is doubled. The results of the exergy analysis show, that the introduction of the liquefaction of natural gas has a positive effect on the exergetic efficiency of a convetional air separation unit, which increases from 38% to 49%.

scholarly journals Energy and exergy analysis of a simple gas turbine combined with linde cycle and N2 injected into the compressor of the gas turbine

2021 ◽  
Vol 1 (1) ◽  
pp. 006-015
Author(s):  
E. H. Betelmal ◽  
A. M. Naas ◽  
A. Mjani
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Exergy Analysis ◽  
Air Separation ◽  
Compression Process ◽  
Turbine Efficiency ◽  
Performance Variation ◽  
Energy And Exergy ◽  
Energy And Exergy Analysis ◽  
Gas Turbine Cycle

In this paper, we investigated a thermodynamic model of the regeneration gas turbine cycle with nitrogen supplied during the compression process. A suitable quantity of nitrogen that comes from the air separation cycle (Linde cycle) is injected between the stages of the compressor where it is evaporated, then the nitrogen and air mixture enters into the combustion chamber where it is burned and expanded in the turbine. We used this method to reduce greenhouse gases and improve gas turbine efficiency. In this work, we evaluated the operational data of the regeneration gas turbine cycle and the maximum amount of nitrogen that can be injected into the compressor. We also investigated the performance variation due to nitrogen spray into the compressor, and the effect of varying ambient temperature on the performance of gas turbines (thermal efficiency, power), as well as a comparison between the normal gas turbine cycle, and the remodelled compression cycle. The exergy analysis shows that the injection of the nitrogen will increase exergy destruction. The results demonstrated an 8% increase in the efficiency of the cycle, furthermore, CO2 emission decreased by 11% when the nitrogen was injected into the compressor.

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