Carbon dioxide emission reduction method

A method of reducing carbon dioxide emissions in a refinery comprising:

• obtaining a refinery off gas stream upstream from a refinery fuel gas header within the refinery and down stream from a sulfur removal unit;
• heating a hydrocarbon containing stream composed at least in part of the refinery off gas stream and producing a reacted stream from the hydrocarbon containing stream by catalytically reacting hydrogen with hydrocarbons and sulfur compounds present within the hydrocarbon containing stream without oxygen so that the reacted stream contains saturated hydrocarbons and hydrogen sulfide formed from hydrogenation of the hydrocarbons and the sulfur compounds, respectively, or alternatively, catalytically reacting oxygen, steam and the hydrocarbons and the hydrogen with the sulfur compounds so that the reacted stream contains additional hydrogen, saturated hydrocarbons, carbon monoxide and the hydrogen sulfide;
• cooling the reacted stream, adsorbing the hydrogen sulfide within the reacted stream to produce a treated reacted stream and combining the treated reacted stream with a steam stream to produce a reactant stream;
• producing a reformed stream comprising hydrogen, carbon monoxide, steam and carbon dioxide, at least in part, by subjecting the reactant stream to steam methane reforming in a steam methane reformer fired by a fuel;
• the steam methane reforming being carried out at a pressure that is in a range of between about 125 psia and about 300 psia and at a steam to carbon ratio of between about 2.0 and about 3.5 thereby to produce reaction products from the steam methane reforming having a methane content of no greater than about 2.0 mol %;
• reacting the carbon monoxide and steam contained in the reformed stream in at least one water-gas shift reactor such that a shifted stream is produced having a hydrogen and carbon dioxide content greater than that of the reformed stream and other constituents;
• separating carbon dioxide from the shifted stream to produce a carbon dioxide containing gas stream and a hydrogen containing gas stream having a greater concentration of the other constituents than the carbon dioxide containing gas stream;
• producing a first hydrogen containing fuel gas stream and a second hydrogen containing fuel gas stream from the hydrogen containing gas stream such that the first hydrogen containing fuel gas stream and the second hydrogen containing fuel as stream each having a composition that is the same as that of the hydrogen containing gas stream;
• and
• returning the first hydrogen containing fuel gas stream to the refinery fuel gas header and utilizing the second hydrogen containing fuel gas stream to supply at least part of the fuel to the steam methane reformer.