NOVELTY - Hydrogen is produced by: (i) separating oxygen from oxygen-containing feed; (ii) reacting oxygen with hydrocarbon and steam to produce a synthesis gas; (iii) separating hydrogen to produce a hydrogen-depleted crude synthesis gas and a hydrogen permeate; and (iv) combusting hydrogen-depleted stream in the presence of oxygen-containing feed stream to form the heated oxygen-containing feed stream.    USE - Production of hydrogen for use in the synthesis of industrial chemicals and in fuel cells.    ADVANTAGE - The production of hydrogen is less complex and more useful for small-scale hydrogen generation plants. The use of hydrogen-depleted crude synthesis gas as fuel to preheat air or other oxygen-containing gas solves the problem of flaring of low grade fuel gas and reduces the number of heat exchangers. The combustion of hydrogen-depleted crude synthesis gas also produces more heat per mole of oxygen consumed than other fuels.    DETAILED DESCRIPTION - Production of hydrogen involves:    (a) separating oxygen from a heated oxygen-containing feed stream (10, 14, 20) with an oxygen transport membrane (26) to produce an oxygen permeate;    (b) reacting the oxygen permeate, a hydrocarbon contained in a hydrocarbon-containing feed stream (30, 34, 40), and steam contained in a steam feed stream in a partial oxidation and reforming reaction to produce a crude synthesis gas comprising hydrogen, carbon monoxide, water and carbon dioxide;    (c) separating the hydrogen from the synthesis gas in a hydrogen transport membrane (64) to produce a hydrogen-depleted crude synthesis gas (16, 66) and a hydrogen permeate (72);    (d) forming a product stream (78) containing hydrogen composed of the hydrogen permeate; and    (e) combusting a stream of the hydrogen-depleted crude synthesis gas in the presence of an oxygen-containing feed stream to form the heated oxygen-containing feed stream.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic illustration of apparatus for producing hydrogen.    Oxygen-containing feed stream (10, 14, 20)    Hydrogen-depleted crude synthesis gas (16, 66)    Oxygen transport membrane (26)    Oxygen-depleted retentate (27)    Hydrocarbon-containing feed stream (30, 34, 40)    Sweep gas (62)    Hydrogen transport membrane (64)    Hydrogen permeate (72)    Product stream (78)