Title: Minimisation of exergy losses in mono high pressure nitric acid process

Authors: Rajubhai K. Mewada; Samir C. Nimkar

Addresses: Department of Chemical Engineering, Institute of Technology, Nirma University, Ahmedabad – 382481, Gujarat, India ' Department of Chemical Engineering, Bharati Vidyapeeth Institute of Technology, Navi Mumbai – 400614, Maharashtra, India

Abstract: Nitric acid production plant is self-sufficient in energy. It is a net exporter of energy. But its exergy efficiency is very low. Turbocompressor, which utilises work produced by recovered heat, is used to maintain pressure in the process. Large amount of heat is taken out from cooler condenser by using cooling tower water. In this paper, energy and exergy analysis of mono high pressure nitric acid process is carried out. Both turbocompressor and cooler condenser are accounting to 33.28% of total exergy destruction. An attempt has been made to reduce exergy losses in both equipments by using a practical approach. Heat available in cooler condenser is recovered by using the organic Rankine cycle (ORC) within available practical limits of the plant. Exergy analysis of ORC shows that 42% of the losses in cooler condenser are reduced.

Keywords: nitric acid production; energy efficiency; exergy efficiency; compressors; cooler condensers; organic Rankine cycle; energy analysis; exergy analysis; exergy losses; turbocompressor.

DOI: 10.1504/IJEX.2015.069990

International Journal of Exergy, 2015 Vol.17 No.2, pp.192 - 218

Received: 22 Jan 2014
Accepted: 08 May 2014
Published online: 22 Jun 2015 *

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