Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 30172
Exergy Analysis of Combined Cycle of Air Separation and Natural Gas Liquefaction

Authors: Hanfei Tuo, Yanzhong Li

Abstract:

This paper presented a novel combined cycle of air separation and natural gas liquefaction. The idea is that natural gas can be liquefied, meanwhile gaseous or liquid nitrogen and oxygen are produced in one combined cryogenic system. Cycle simulation and exergy analysis were performed to evaluate the process and thereby reveal the influence of the crucial parameter, i.e., flow rate ratio through two stages expanders β on heat transfer temperature difference, its distribution and consequent exergy loss. Composite curves for the combined hot streams (feeding natural gas and recycled nitrogen) and the cold stream showed the degree of optimization available in this process if appropriate β was designed. The results indicated that increasing β reduces temperature difference and exergy loss in heat exchange process. However, the maximum limit value of β should be confined in terms of minimum temperature difference proposed in heat exchanger design standard and heat exchanger size. The optimal βopt under different operation conditions corresponding to the required minimum temperature differences was investigated.

Keywords: combined cycle simulation, exergy analysis, natural gas liquefaction.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1073599

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2359

References:


[1] A.J. Finn, G.L. Johnson, T.R. Tomlinson, Developments in natural gas liquefaction, Hydrocarbon Processing, vol. 78, no. 4, pp. 47-56, 1999.
[2] M.A. Barclay, D.F. Gongaware, K. Dalton, M.P. Skrzypkowski, Thermodynamic cycle selection for distributed natural gas liquefaction, AIP Conference Proceeding, vol. 710, pp. 75-82, 2004.
[3] C.W. Remeljej, A.F.A Hoadley, An exergy analysis of small-scale liquefied natural gas (LNG) liquefaction processes, vol. 31, no. 12, pp. 2005-2019, 2006.
[4] R.L. Cornelissen, G.G. Hirs, Exergy analysis of cryogenic air separation, Energy Conversion and Management vol. 39, no. 18, pp. 1821-1826, 1998.
[5] Y. Li, N. Yan, H. Tuo, Small-scale gas liquefaction process using air separation refrigeration unit: China, CN1908558.
[6] J.P. Tranier, L.Roses. Combined air separation natural gas liquefaction plant: US, 7143606 B2. 2006-12-05.J.
[7] W.D. Seider, Process design principles, Wiley, New York, 1998.
[8] B. Linnhoff, Pinch analysis- a state-of-the-art overview, Trans. IChemE, vol. 71, pp. 503-522, 1993.
[9] X. Feng, X. Zhu, Combing pinch and exergy analysis for process modifications, Applied Thermal Engineering, vol. 17, no. 3, pp. 249- 261, 1997.
[10] A. Aspelund, D. Berstad, T. GUndersen, An extended pinch analysis and design procedure utilizing pressure based exergy for subambient cooling, Applied Thermal Engineering, vol. 27, no. 16, pp. 2633-2649, 2007.
[11] A. Salama, Numerical techniques for determining heat energy targets in pinch analysis, Computers and Chemical Engineering, vol. 29, pp. 1861-1866, 2005.
[12] B. Linhoff, V.R. Dhole, Shaft work targets for low-temperature process design, Chemical Engineering Science, vol. 47, no. 8, pp. 2081-2091, 1992.