NOVELTY - A new total isomerization process with enhanced heat integration comprises heat exchanging the absorber feed and/or the hydrogen purge gas with the desorption effluent. Traditional heat exchanging techniques are employed in conjunction with a variable steam or hot oil flow, or with a surge drum.    USE - In a hydrocarbon isomerization process plant.    ADVANTAGE - The invention reduces the utility costs of the overall process.    DETAILED DESCRIPTION - A process for the isomerization of normal hydrocarbons in a feed stream containing mixed normal and non-normal-hydrocarbons comprises:    (a) flowing the feed stream to a reactor containing an isomerization catalyst and operating at about 232 C or less, or to an adsorption zone containing an adsorbent having a selectivity for the normal hydrocarbons and operating at about 260 C or greater;    (b) flowing a variable mass flow desorption effluent containing at least hydrogen and normal hydrocarbons to the reactor to form a reactor effluent containing hydrogen normal hydrocarbons and isomerized non-normal hydrocarbons;    (c) separating the reactor effluent into a hydrogen-enriched stream and a hydrocarbon-enriched stream;    (d) heat exchanging the hydrocarbon-enriched stream, the hydrogen-enriched stream, or both separately, with the variable mass flow desorption effluent so that the variable mass flow desorption effluent flowing into the reactor is at about the operating temperature of the reactor;    (e) heat exchanging the hydrocarbon-enriched stream, the hydrogen-enriched stream, or both, with at least one controlled variable heat providing stream so that the temperature of the hydrocarbon-enriched stream, the hydrogen-enriched stream or both, approaches the operating temperature of the adsorption zone;    (f) flowing the hydrocarbon-enriched stream to the adsorption zone to adsorb the normal hydrocarbons and collect the non-normal hydrocarbons; and    (g) desorbing the normal hydrocarbons from the adsorption zone using the hydrogen-enriched stream to produce the variable mass flow desorption effluent.    DESCRIPTION OF DRAWING(S) - The drawing is a schematic representation of a generic total isomerization process modified and operated according to the present invention.    Fresh feed stream (2)    Heat exchangers (4, 12, 26, 28, 36, 38, 58, 60)    Fired heater (6, 40, 62)    Adsorption zone (8)    Effluent stream (10)    Separator drums (14, 22, 30)    Hydrocarbon-rich stream (16, 18)    Desorption effluent line (20)    Isomerization zone (22)    Adsorber feed line (32)    Combined feed stream (42)