Koch Process Systems, Inc.

Helix Technology Corporation

James M Ryan

Arthur S Holmes

John V O'Brien

Distillative separations of hydrocarbon feed mixtures containing at least methane and carbon dioxide, as well as other components, such as ethane, higher hydrocarbons, and hydrogen sulfide are disclosed. In the separations described, methane is preferably separated from an acid gas under conditions of composition, temperature and pressure which would normally produce acid gas solids. Acid gas solids are prevented by adding a liquid solids-preventing agent into this distillation column. A second distillation column is subsequently employed to further separate the feed gas mixture. The second distillation column is operated under conditions which an azeotrope would normally form between the light hydrocarbon and carbon dioxide, which azeotrope would limit the carbon dioxide overhead composition. The azeotrope is prevented by introducing an agent for preventing azeotrope formation. Alternatively, the second distillation column may be operated to separate carbon dioxide from hydrogen sulfide. In this case, a liquid agent is added to the second distillation column to increase the relative volatility of carbon dioxide to hydrogen sulfide. All liquid agents preferably comprise a C.sub.3 -C.sub.6 alkane, such as butane, or a mixture of such alkanes.

Distillative separations of gas mixtures containing methane, carbon

A method for the distillative separation of a feed stream containing light hydrocarbons and acid gas components in a distillative column into an enriched overhead product, such as a carbondioxide fraction, and an enriched bottom product of C.sub.2 + and hydrogen sulfide, the method which comprises: introducing a liquid alkane additive into the column, to provide a relatively uniform, constant temperature zone in the column above the point of feed inlet of the feed stream; extracting heat from the upper portion of the low-temperature zone; and introducing heat into the lower portion of the temperature zone approximately at or above the feed inlet of the feed stream, to reduce the energy requirement of the distillation.

Energy-saving distillative separation using low-temperature heat input

An improved method for the distillation of a feed stream containing hydrocarbon components, which method is directed toward the production of a bottom product stream and an overhead product stream, both with desired specifications, which method comprises recycling a minor portion of the bottom product stream typically, but not necessarily, derived from said separation directly to a reflux condenser for the overhead product stream of said method, in order to effect a savings in energy in said distillative method, such as by adjusting the column operating conditions, such as the column operating pressure or the top or bottom operating temperatures of said column.

Distillative separation employing bottom additives

A distillative separation of carbon dioxide and hydrogen sulfide is improved by adding a C.sub.3 -C.sub.6 alkane, a mixture of C.sub.3 -C.sub.6 alkanes, SO.sub.2 or SO.sub.3 to a distillation column to increase the relative volatility of carbon dioxide to hydrogen sulfide. Increasing the relative volatility facilitates the separation.

Distillative separation of carbon dioxide from hydrogen sulfide

An improved distillative separation of carbon dioxide and light hydrocarbons is disclosed in which the formation of an azeotrope between these components is prevented by addition of an agent to said distillation column and in which prevention of the azeotrope allows a more complete separation to be achieved.

Distillative separation of carbon dioxide from light hydrocarbons

A method of eliminating solids formation in a cryogenic distillative separation of acid gases from methane is disclosed. This method comprises adding a solids-preventing agent to the solids potential zone of the distillation column. Typical solids-preventing agents are one or more C.sub.2 -C.sub.5 alkanes, or other nonpolar liquids which are miscible with methane at the column conditions. The elimination of solids formation permits a more complete separation to be achieved.

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Weston, MA, United States of America

James M Ryan