Integrated controlled freeze zone (CFZ) tower and dividing wall (DWC) for enhanced hydrocarbon recovery

A method for the separation of a sour gas feedstream containing methane and carbon dioxide acid gas in a distillation tower comprising:

• maintaining a lower distillation zone comprising a dividing wall, which extends substantially vertically through the lower distillation zone to divide the lower distillation zone into a pre-fractionation zone and a product zone, said lower distillation zone configured to produce an enriched carbon dioxide liquid bottoms stream and a freezing zone vapor feed stream;
• maintaining a controlled freezing zone configured to contact the freezing zone vapor feedstream with at least one freezing zone liquid feedstream containing methane at a temperature and pressure whereby both solids-containing carbon dioxide and a methane-enriched vapor stream are formed in the controlled freezing zone;
• introducing the sour gas feedstream containing methane and carbon dioxide gas into the lower distillation zone;
• producing the enriched carbon dioxide liquid bottoms stream and the freezing zone vapor feedstream;
• introducing the freezing zone vapor feedstream into the controlled freezing zone;
• contacting in the controlled freezing zone the freezing zone vapor feedstream with the at least one freezing zone liquid feedstream;
• forming in the controlled freezing zone the solids containing carbon dioxide and the methane-enriched vapor stream;
• melting the solids containing carbon dioxide and introducing a liquid stream containing the melted solids into the lower distillation zone;
• separating the liquid stream containing the melted solids into a liquid acid gas stream and a hydrocarbon stream;
• recovering from a draw tray of the lower distillation zone a portion of the hydrocarbon stream and concentrating the portion of the hydrocarbon stream using an adsorption or membrane system to produce an enriched hydrocarbon product stream and an enriched sour gas stream;
• and
• reintroducing the enriched sour gas stream into the lower distillation section.

A distillation tower for the separation of a feedstream containing methane and carbon dioxide acid gas comprising:

• a lower distillation zone comprising:
• a dividing wall, which extends substantially vertically through the lower distillation zone to divide the lower distillation zone into a pre-fractionation zone and a product zone, both of the zones opening at both ends of the dividing wall in common zones above and below the dividing wall, wherein an enriched carbon dioxide liquid bottoms stream and a freezing zone vapor feedstream are produced at a temperature and pressure at which substantially no carbon dioxide solids are formed;
• a side draw tray outlet configured to receive a hydrocarbon stream separated from the enriched carbon dioxide liquid bottoms stream;
• and
• an adsorption or membrane device in fluid communication with the side draw outlet, wherein the adsorption or membrane device is configured to separate the hydrocarbon stream into an enriched hydrocarbon product stream and an enriched sour gas stream;
• a reintroduction inlet in fluid communication with the absorption or membrane device to reintroduce the enriched sour gas stream into the lower distillation section;
• an inlet to the lower zone of the distillation tower for a feedstream containing methane and carbon dioxide acid gas;
• a controlled freezing zone wherein a freezing zone liquid feedstream containing methane is contacted with the freezing zone vapor feedstream at a temperature and pressure wherein both solids containing carbon dioxide and a methane-enriched vapor stream are formed;
• and
• an upper distillation section wherein an acid gas component from the methane-enriched vapor stream is removed.