US 12,312,313 B2
Energy-efficient process for removing butenes from C4-hydrocarbon streams
Philip Lutze, Dinslaken (DE); Stephan Peitz, Oer-Erkenschwick (DE); Armin Matthias Rix, Marl (DE); Tanita Valèrie Six, Dortmund (DE); Moritz Schröder, Muenster (DE); and Niklas Paul, Marl (DE)
Assigned to Evonik Oxeno GmbH & Co. KG, Marl (DE)
Appl. No. 18/260,069
Filed by Evonik Oxeno GmbH & Co. KG, Marl (DE)
PCT Filed Jan. 21, 2022, PCT No. PCT/EP2022/051366
§ 371(c)(1), (2) Date Jun. 30, 2023,
PCT Pub. No. WO2022/161869, PCT Pub. Date Aug. 4, 2022.
Claims priority of application No. 21153661 (EP), filed on Jan. 27, 2021.
Prior Publication US 2024/0059633 A1, Feb. 22, 2024
Int. Cl. C07C 7/11 (2006.01); C07C 7/04 (2006.01)
CPC C07C 7/11 (2013.01) [C07C 7/04 (2013.01)] 19 Claims
OG exemplary drawing
 
1. A process for separating butenes from a C4-hydrocarbon stream which contains at least butenes and butanes by extractive distillation with a solvent, the process comprising:
a. at least partially evaporating a liquid C4-hydrocarbon stream in a feed evaporator, to supply a gaseous C4-hydrocarbon stream and supplying the solvent above the gaseous C4-hydrocarbon stream to an absorber in which the gaseous C4-hydrocarbon stream and the solvent are contacted with one another to transfer predominantly butenes from the gaseous C4-hydrocarbon stream to the solvent, to obtain a laden solvent, wherein the laden solvent is collected in a liquid collector of the absorber and passed through an absorber evaporator and then passed into the bottom of the absorber below the liquid collector to outgas predominantly butanes from the laden solvent, and wherein the laden solvent is subsequently passed to a desorber as a bottoms stream;
b. supplying the laden solvent to the desorber, the bottom of which is at an elevated temperature relative to the bottom of the absorber, and in which the butenes are separated from the laden solvent to obtain at the top of the desorber a stream enriched in butenes, wherein the solvent, at least partially freed of butenes, is collected in a liquid collector of the desorber and passed through a desorber evaporator and then passed into the bottom of the desorber below the liquid collector to outgas any butenes remaining in the solvent and wherein the solvent is subsequently recycled to the absorber as a bottoms stream;
wherein heat of the solvent withdrawn as the bottoms stream of the desorber is used at least partially for heat integration by employing the heat of the solvent in at least one respective heat exchanger for preheating the laden solvent passed to the desorber, for evaporation in the absorber evaporator, and for evaporation of the liquid C4-hydrocarbon stream,
wherein an employed heating steam undergoes at least partial condensation in the at least one respective heat exchanger, thus generating a hot condensate at a pressure of 10 to 20 bar absolute, and a temperature of 150° C. to 210° C., which is passed to a condensate container.