Controlling heating valve of natural gas

Claim 1

IN A GASOLINE EXTRACTION SYSTEM WHEREIN A NATURAL GAS CONTAINING HYDROCARBONS BOILING WITHIN THE GASOLINE BOILING RANGE AND HYDROCARBONS BOILING LOWER THAN THE GASOLINE BOILING RANGE ARE EXTRACTED AS NATURAL GASOLINE FROM THE NATURAL GAS LEAVING A RESIDUE GAS, A METHOD FOR MAINTAINING THE B. T. U. CONTENT OF THE RESIDUE GAS AT A PREDETERMINED VALUE COMPRISING DEETHANIZING THE NATURAL GASOLINE TO PRODUCE AN ETHANE FREE NATURAL GASOLINE AND AN OVERHEAD PRODUCT CONTAINING ETHANE AND SOME PRODUCT SEPARATING THIS OVERHEAD PRODUCT INTO A FIRST PORTION AND A SECOND PORTION, COOLING SAID FIRST PORTION TO PRODUCE SOME CONDENSATE AND RETURNING THIS CONDENSATE TO THE STABILIZER AS REFLUX, AND ADDING THE SECOND PORTION OF THE OVERHEAD PRODUCT AND UNCONDENSED VAPORS FROM SAID FIRST PORTION TO THE RESIDUE GAS: CONTINUOUSLY DETERMINING THE B. T. U. CONTENT OF THE THUS ENRICHED RESIDUE GAS AND CONTROLLING SAID SEPARATION OF THE STABILIZING OVERHEAD PRODUCT TO PROVIDE A SUFFICIENT QUANTITY OF SAID SECOND PORTION OF THE OVERHEAD PRODUCT TO MAINTAIN THE B. T. U. CONTENT OF THE ENRICHED RESIDUE GAS AT SAID PREDETERMINED VALUE.