Separation of gas mixtures by fractionation with indirect heat exchange

Abstract

Abstract METHOD AND SYSTEM FOR SEPARATING COMPONENTS OF GAS MIXTURES SUCH AS MIXTURES OF HYDROCARBONS CONTAINING FROM 1 TO ABOUT 4 CARBON ATOMS, AND PARTICULARLY DESIGNED FOR RECOVERY OF HYDROCARBONS HEAVIER, I.E., OF HIGHER MOLECULAR WEIGHT, THAN METHANE FROM NATURAL GAS CONTAINING A MAJOR PROPORTION OF METHANE AND A MINOR PROPORTION OF ETHANE AND WHICH MAY ALSO CONTAIN SMALL AMOUNTS OF PROPANE, AND OTHER HEAVIER HYDROCARBONS, WHICH INVOLVES, ACCORDING TO ONE EMBODIMENT, COOLING A COMPRESSED FEED MIXTURE OF SUCH NATURAL GAS, DIVIDING THE COOLED COMPRESSED FEED MIXTURE INTO A FIRST PORTION AND A REMAINING PORTION, AND PASSING THE FIRST PORTION OF SUCH COOLED COMPRESSED FEED MIXTURE IN HEAT EXCHANGE RELATION ALONG THE LOWER PORTION OF A DISTILLATION COLUMN TO FURTHER COOL THE FIRST PORTION OF THE FEED MIXTURE AND SUPPLY REBOIL HEAT TO THE LOWER PORTION OF THE COLUMN. SUCH FURTHER COOLED FIRST PORTION OF THE FEED MIXTURE IS WITHDRAWN FROM HEAT EXCHANGE RELATION WITH THE COLUMN, IS ADDITIONALLY COOLED BY EXTERNAL REFRIGERATION AND SUCH ADDITIONALLY COOLED FIRST PORTION OF THE FEED MIXTURE IS PASSED IN HEAT EXCHANGE RELATION ALONG THE UPPER PORTION OF THE DISTILLATION COLUMN TO FURTHER COOL THE LAST-MENTIONED PORTION OF THE FEED MIXTURE AND PROVIDING REBOIL HEAT IN THE UPPER PORTION OF THE COLUMN. THE REMAINING PORTION OF THE COOLED COMPRESSED FEED MIXTURE IS FURTHER COOLED AND COMBINED WITH THE COOLED PORTION OF FEED MIXTURE IN LIQUID FORM WITHDRAWN FROM HEAT EXCHANGE RELATION WITH THE UPPER PORTION OF THE COLUMN, AND THE RESULTING COMBINED COOLED FEED MIXTURE IS INTRODUCED INTO THE TOP OF THE COLUMN AS FEED FOR THE COLUMN. A SEPARATION OF THE FEED MIXTURE IN THE COLUMN IS EFFECTED BY A NON-ADIABATIC DISTILLATION IN THE COLUMN, AND A LIQUID BOTTOMS PRODUCT IS WITHDRAWN CONSISTING ESSENTIALLY OF SUBSTANITIALLY PURE ETHANE AND AN OVERHEAD PRODUCT CONSISTING ESSENTIALLY OF METHANE IS OBTAINED, WHICH IS USED TO COOL THE ABOVENOTE REMAINING PORTION OF THE FEED MIXTURE. THIS PRCESS AND SYSTEM ARE DESIGNED TO EFFECT AN EFFICIENT SEPARATION FOR HIGH RECOVERY OF ETHANE FROM THE ABOVE-NOTED NATURAL GAS BY REMOVING REFRIGERATION FROM THE COLUMN ALONG THE LENGTH OF THE COLUMN IN AN EFFICIENT SUBSTANTIALLY THERMODYNAMICALLY REVERSIBLE MANNER, THAT IS, NON-ADIABATICALLY, RESULTING IN A SUBSTANTIAL REDUCTION IN POWER REQUIREMENT.

Inventors

• 👤 Michael L Hoffman
• 👤 Henry Huang

Bibliographic Details