Maintaining b. t. u. content of residue gas from absorber

Claim 1

A PROCESS FOR TREATING A GASEOUS HYDROCARBON MATERIAL MIXTURE COMPRISING LOW-BOILING NORMALLY GASEOUS HYDROCARBON MATERIALS, LOWER BOILING NORMALLY GASEOUS HYDROCARBON MATERIALS AND HIGHER BOILING HYDROCARBON MATERIALS WHICH COMPRISES: PASSING SAID MIXTURE INTO AN ABSORPTION ZONE AND THEREIN CONTACTING SAME WITH A LEAN PRESATURATED ABSORPTION MEDIUM AND ABSORBING SAID LOW-BOILING NORMALLY GASEOUS HYDROCARBON MATERIALS, HIGHER BOILING HYDROCARBON MATERIALS AND A PORTION OF SAID LOWER-BOILING NORMALLY GASEOUS HYDROCARBON MATERIALS WITHDRAWING UNABSORBED HYDROCARBON MATERIALS FROM SAID ABSORPTION ZONE; WITHDRAWING A RESULTING RICH ABSORPTION MEDIUM FROM SAID ABSORPTION ZONE AND PASSING SAME INTO 2 FIRST SEPARATION ZONE, THEREIN SEPARATING SAID ABSORBED LOW-BOILING AND LOWER BOILING HYDROCARBON MATERIALS FROM SAME AND WITHDRAWING A GASEOUS STREAM OF LOW AND LOWER BOILING NORMALLY GASEOUS HYDROCARBON MATERIALS FROM SAID FIRST SEPARATION ZONE; PASSING SAID GASEOUS STREAM OF LOW AND LOWER BOILING HYDROCARBON MATERIALS INTO A SELECTIVE ADSORPTION SEPARATION ZONE, THEREIN SEPARATING AND RECOVERING A STREAM OF LOW-BOILING NORMALLY GASEOUS HYDROCARBON MATERIALS AND WITHDRAWING A STREAM OF LOWER BOILING HYDROCARBON MATERIALS; CONTROLLING THE AMOUNT OF LOW-BOILING NORMALLY GASEOUS HYDROCARBON MATERIALS WITHDRAWN IN RESPONSE TO THE VARIATION OF THE B. T. U. CONTENT OF THE UNABSORBED HYDROCARBON MATERIALS WITHDRAWN FROM