Thermoeconomic analysis on a cascade energy utilization system for compression heat in air separation units

Rong, Yu; Zhi, Xiaoqin; Wang, Kai; Zhou, Xia; Cheng, Xingwang; Qiu, Limin; Chi, Xuelin

doi:10.1016/j.enconman.2020.112820

Cited by 30 publications

(7 citation statements)

References 47 publications

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“…Thus, air needs to be dried to remove water (and carbon dioxide) to prevent freezing from affecting the regular operation of the equipment. 201 ] as an absorbent for the air-drying process. 116 It was found that when IL [EMIM][BF 4 ] was selected as the absorbent, the water content in the air decreased sharply from 12000 to 138 ppm.…”

Section: Krannich Et Al Used Il [Emim][mesomentioning

confidence: 99%

Condensable Gases Capture with Ionic Liquids

Chen

Lei

et al. 2023

Chem. Rev.

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Condensable gases are the sum of condensable and volatile steam or organic compounds, including water vapor, which are discharged into the atmosphere in gaseous form at atmospheric pressure and room temperature. Condensable toxic and harmful gases emitted from petrochemical, chemical, packaging and printing, industrial coatings, and mineral mining activities seriously pollute the atmospheric environment and endanger human health. Meanwhile, these gases are necessary chemical raw materials; therefore, developing green and efficient capture technology is significant for efficiently utilizing condensed gas resources. To overcome the problems of pollution and corrosion existing in traditional organic solvent and alkali absorption methods, ionic liquids (ILs), known as “liquid molecular sieves”, have received unprecedented attention thanks to their excellent separation and regeneration performance and have gradually become green solvents used by scholars to replace traditional absorbents. This work reviews the research progress of ILs in separating condensate gas. As the basis of chemical engineering, this review first provides a detailed discussion of the origin of predictive molecular thermodynamics and its broad application in theory and industry. Afterward, this review focuses on the latest research results of ILs in the capture of several important typical condensable gases, including water vapor, aromatic VOCs (i.e., BTEX), chlorinated VOC, fluorinated refrigerant gas, low-carbon alcohols, ketones, ethers, ester vapors, etc. Using pure IL, mixed ILs, and IL + organic solvent mixtures as absorbents also briefly expanded the related reports of porous materials loaded with an IL as adsorbents. Finally, future development and research directions in this exciting field are remarked.

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Section: Krannich Et Al Used Il [Emim][mesomentioning

confidence: 99%

Condensable Gases Capture with Ionic Liquids

Chen

Lei

et al. 2023

Chem. Rev.

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“…Rong at al. [ 8 ] analyzed an air separation unit in an attempt to recover as much as possible from the exergy loss, with the heat transferred to the cooling system of the compressor’s zone. A part of this potential will run an organic Rankine cycle.…”

Section: Introductionmentioning

confidence: 99%

Exergetic Analysis of a Cryogenic Air Separation Unit

Bucsa

Şerban

Bălan

et al. 2022

Entropy

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This case study analyzes a cryogenic air separation unit (ASU) with a production of V˙O2=58300 [m3Nh] of gaseous oxygen with a concentration greater than 98.5%, operating in Romania on a steel plant platform. The goal of the paper is to provide an extensive model of exergetic analysis that could be used in an optimization procedure when decisional parameters are changed or structural design modifications are implemented. For each key part of the Air Separation Unit, an exergetic product and fuel were defined and, based on their definition, the coefficient of performance of each functional zone was calculated. The information about the magnitude of the exergetic losses offers solutions for their future recovery. The analysis of the exergy destructions suggests when it is worth making a larger investment. The exergetic analysis of the compression area of the ASU points out an exergy destruction and loss of 37% from the total plant’s electrical energy input. The exergy loss with the heat transferred to the cooling system of compressors can be recovered; for the exergy destruction portion, the challenge between investment and operating costs should be considered. The exergy destruction of the air separation columns found the High Pressure Column (HPC) to be more destructive than the Low Pressure Column. The share of the exergy destruction in the total plant’s electrical energy input is 8.3% for the HPC. The local COP of the HPC, calculated depending on the total exergy of the local product and fuel, is 62.66%. The calculus of the air separation column is performed with the ChemSep simulator.

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“…The electricity produced by ORC can also be further converted to the cooling capacity to satisfy the cooling demand of ACS. Rong et al [20,21] investigated a cascade waste heat recovery system including dehumidification (DEH), ORC, and MR (DEH-ORC-MR), and found that 50% of the feed air humidity ratio can be decreased, which helped to increase the average isothermal efficiency of the compressors by about 5%. The waste compression heat utilization rate and energy saving rate reached 61.5% and 4.9%, respectively.…”

Section: Introductionmentioning

confidence: 99%

Potential for Energy Utilization of Air Compression Section Using an Open Absorption Refrigeration System

Sun²,

Wang³

2022

Applied Sciences

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In this paper, an open absorption refrigeration system is proposed to recover part of the waste compression heat while producing cooling capacity to further cool the compressed air itself. The self-utilization of the compression waste heat can significantly reduce the energy consumption of air compression, and hence increase the energy efficiency of the cryogenic air separation unit. To illuminate the energy distribution and energy conversion principle of the open absorption refrigerator-assisted air compression section, a thermodynamic model is built and the simulation work conducted based on a practical triple-stage air compression section of a middle-scale cryogenic air separation unit. Our results indicate that the energy saving ratio is mainly constrained by the distribution of the cooling load of compressed air, which corresponds to the heat load of the generator and cooling capacity of the evaporator in the open absorption refrigerator. The energy saving ratio ranges from 0.52–8.05%, corresponding to the temperature range of 5–30 °C and humidity range of 0.002–0.010 kg/kg. It is also estimated, based on the economic analysis, that the payback period of the open absorption refrigeration system is less than one year, and the net project revenue during its life cycle reaches USD 5.7 M, thus showing an attractive economic potential.

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Thermoeconomic analysis on a cascade energy utilization system for compression heat in air separation units

Cited by 30 publications

References 47 publications

Condensable Gases Capture with Ionic Liquids

Condensable Gases Capture with Ionic Liquids

Exergetic Analysis of a Cryogenic Air Separation Unit

Potential for Energy Utilization of Air Compression Section Using an Open Absorption Refrigeration System

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