Managing energy recovered from waste tail gas in a full-scale refinery plant

Great savings of fuel consumption and an almost zero-discharge of carbon pollutants can be achieved by the direct reuse of the recovered tail gas as furnace fuel. This paper presents the results of on-site studies using a full-scale furnace to demonstrate the simple adjustments of the furnace operational parameters. The results reveal that when the residual oxygen concentration in the excess air is reduced from 3.6 to 2.4%, the furnace thermal efficiency is raised from 81.9 to 83.2%. Adjusting the furnace damper opening angle from 45 to 39° will lead to annual savings of 1.9 × 106 m3 natural gas consumption. This paper also presents the use of a membrane separation method to concentrate the hydrogen containing in the tail gas as from 78.7 to 93.9 mol%. The concentrated hydrogen gas is expected to be a valuable material to produce high value added products.