Two-stage rectification for the separation of hydrocarbons
First Claim
1. In a process for the separation of C2+ or C3+ hydrocarbons from a hydrocarbon-containing raw gas under pressure, by recitification wherein the raw gas is cooled and expanded and the resultant condensates are introduced into a rectification column wherein the C2+ or C3+ hydrocarbons, respectively, are separated from the lower-boiling components, the improvement which comprises feeding the condensate fractions produced during cooling and expansion of the raw gas into a first rectifying column operated under a higher pressure to yield a bottoms fraction and an overhead product, the latter containing components boiling lower than the C2+ or C3+ hydrocarbons, expanding the bottoms fraction and then feeding resultant expanded bottoms fraction into a second rectifying column operating under a lower pressure than the first column, to yield C2+ or C3+ hydrocarbons bottoms product and an overhead fraction, compressing the latter overhead fraction and recycling resultant compressed overhead fraction into the first rectifying column.
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Abstract
To separate C2+ or C3+ hydrocarbons from hydrocarbon-containing gaseous mixtures by fractional condensation and rectification, the rectification is conducted in two columns, the second column being at a pressure at least 5 bar lower than the first. One of the condensates is subcooled before being passed, for purposes of peak cooling, to the upper zone of the high pressure column, substantial energy savings are realized.
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Citations
22 Claims
- 1. In a process for the separation of C2+ or C3+ hydrocarbons from a hydrocarbon-containing raw gas under pressure, by recitification wherein the raw gas is cooled and expanded and the resultant condensates are introduced into a rectification column wherein the C2+ or C3+ hydrocarbons, respectively, are separated from the lower-boiling components, the improvement which comprises feeding the condensate fractions produced during cooling and expansion of the raw gas into a first rectifying column operated under a higher pressure to yield a bottoms fraction and an overhead product, the latter containing components boiling lower than the C2+ or C3+ hydrocarbons, expanding the bottoms fraction and then feeding resultant expanded bottoms fraction into a second rectifying column operating under a lower pressure than the first column, to yield C2+ or C3+ hydrocarbons bottoms product and an overhead fraction, compressing the latter overhead fraction and recycling resultant compressed overhead fraction into the first rectifying column.
Specification