Thermodynamic Analysis of an Ammonia Synthesis Process Based on Brayton Cycle

Abstract:

The paper develops a new ammonia synthesis process based on Brayton cycle, successfully solving the problem of low heat recovery efficiency of reaction heat by conventional Rankine cycle. In the new process, a gas turbine expander is introduced to drive the multistage compressor coaxially instead of raising steam in a waste heat boiler to drive a steam turbine. Such a process represents a typical reaction-separation system with a recycle stream and cold separation of the product from the recycle loop. Through thermodynamic analysis, it is found that the ammonia synthesis system has the innate convenience and conditions to use the actual improved Brayton cycle. Moreover, since the cold separation is always influenced by gas-liquid equilibrium of pure ammonia, absorption separation is integrated in the process to achieve better use of the reaction heat, which can be driven by the low temperature heat. Flow sheets of the new process are described with the pressure and temperature parameters according to the actual operation conditions. For this special case, thermodynamic calculation and analysis are carried out by a software. The calculated results show that the expansion work is much larger than the required compression work. Even if the utilization efficiency is relatively low, the output work can meet the need of gases compression.

• Periodical: Advanced Materials Research (Volumes 396-398)
• Pages: 939-945
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.396-398.939
• Online since: November 2011
• Authors: Yu Bie, Ming Fu Hu, Xu Zhang, Xiao Qin Zhu, Jing Hua Chang, Wen Yuan Mao
• Keywords: Ammonia Synthesis, Brayton Cycle, Heat Recovery, Thermodynamic Analysis

References

[1] Max Appl: Ammonia: Principles and Industrial Practice (John Wiley Publications, Weinheim 1999).

[2] A. Horton: British Patent GB1146292. (1969).

[3] M. Parmegiani, S.D. Milanese and O. Bellofatto: U.S. Patent 3552122. (1971).

[4] B Linnhoff, J.E. Le Leur and B.L. Pretty: European Patent 0301844B1.(1993).

[5] F.J.J.G. Janssen, A.H.M. Vekooijen and P.J. Ploumen: European Patent 0753652. (1997)

[6] M.A. Agee, L.J. Weick, K.L. Agee and E.L. Trepper: U.S. Patent 6155039. (2000)

[7] J Perold, I.L. Greeff and K.J. Ptasinski: South African Journal of Chemical, Vol. 13 (2001) No. 2, p.1.

[8] I.L. Greeff, J.A. Visser, K.J. Ptasinski and F.J.J.G. Janssen: Applied Thermal Engineering, Vol. 22 (2002) No. 14, p.1549.

[9] I.L. Greeff, J.A. Visser, K.J. Ptasinski and F.J.J.G. Janssen: Energy, Vol. 28 (2003) No. 14, p.1495.

[10] I.L. Greeff, J.A. Visser and K.J. Ptasinski: Energy, Vol. 29 (2004) No. 12, p.2045.

[11] Y.H. Gu and J. Wang: Nuclear Power Engineering, Vol. 24 (2004) No. 2, p.107. (In Chinese)

[12] Y.Y. Yao: Principles of Chemical Engineering (Tianjin Science and Technology Press, Tianjin 1987). (In Chinese)