Title: Replacing of mechanical compressors by gas ejectors in flare gas recovery systems

Authors: Amin Engarnevis; Majid Amidpour; Hadi Jafari

Addresses: Energy System Engineering Department, Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Pardis Ave., Mollasadra Ave., Vanak Square, Tehran, 19991-43344, Iran ' Energy System Engineering Department, Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Pardis Ave., Mollasadra Ave., Vanak Square, Tehran, 19991-43344, Iran ' Energy System Engineering Department, Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Pardis Ave., Mollasadra Ave., Vanak Square, Tehran, 19991-43344, Iran

Abstract: One of the main concerns of humankind in this century is the global warming induced by the increasing concentration of greenhouse gases in the atmosphere. A promising process for controlling the atmospheric CO2 level is prevention of combustion in flares causing high losses of raw material and energy that could generate more desired products. In the present work, a flare gas recovery unit (FGRU) is proposed to recover the flared gases by an oil refinery as the required fuel gas and to decrease the environmental impacts owing to flare emissions. As a gas ejector compression, it proposes an alternative method instead of conventional mechanical compression, to minimise the cost. In order to evaluate this method, the proposed FGRU in Tehran Oil Refinery is simulated and a new mathematical 1-D model is developed to predict the ejector performance and to specify the geometry for optimal performance. In addition, the economics of two flare gas recovery methods are studied and compared. The results show a decrease in both capital and operational costs with production of 9,808.13 tons of fuel gas per year and an acceptable payback of 0.88 year. Gas jet compression yields the higher rate of return, and it is more suitable for Tehran Oil Refinery rather than the other choices due to its lower capital requirements. [Received: February 12, 2012; Accepted: May 29 2012]

Keywords: flare gas recovery; gas ejectors; gas jet compression; mathematical modelling; economic evaluation; mechanical compressors; global warming; greenhouse gases; flared gases; oil refineries; flare emissions; simulation.

DOI: 10.1504/IJOGCT.2013.054850

International Journal of Oil, Gas and Coal Technology, 2013 Vol.6 No.4, pp.422 - 448

Received: 13 Feb 2012
Accepted: 29 May 2012

Published online: 29 Jan 2014 *

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