METHOD AND DEVICE FOR REDUCING OLEFIN LOSSES DURING THE REMOVAL OF CARBON DIOXIDE FROM AN OLEFIN FLOW FROM DEHYDROGENATION REACTIONS
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Abstract
The product gas from a dehydrogenation reaction is treated by a downstream gas scrub followed by depressurization in a high-pressure flash vessel equipped with mass transfer elements, wherein a fuel gas flows upwardly through the mass transfer elements in the high-pressure flash vessel countercurrent to depressurized solvent so that absorbed hydrocarbons are taken up by the fuel gas. The fuel gas is the heating gas for heating the dehydrogenation reactor and is, for example, natural gas. To increase efficiency, the hydrocarbon stream which has been separated from the acidic gas can be recirculated to the process gas path upstream of the gas scrub.
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Citations
31 Claims
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1-16. -16. (canceled)
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17. A process for removing carbon dioxide from a hydrocarbon stream in the preparation of alkenes from alkanes, comprising:
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introducing an industrially oxygen-free gas mixture containing a feed alkane and an inert gas into a reaction apparatus containing at least one catalyst bed to dehydrogenate the feed alkane, said reaction apparatus heated by a heating gas; removing from the reaction apparatus a product gas mixture containing alkenes, alkanes, hydrogen, the inert gas and carbon dioxide (CO2); absorbing acidic gas constituents comprising one or more of carbon dioxide, hydrogen sulfide (H2S), carbonyl sulfide (COS) and mercaptans present in the product gas by contacting the product gas with a solvent which absorbs acidic gases in a gas scrub downstream of the dehydrogenation, forming an adsorbate solution; and conveying the adsorbate solution, which also contains coabsorbed hydrocarbons, to the top of a high-pressure flash vessel containing mass transfer elements, and feeding a fuel gas to the bottom of the high-pressure flash vessel countercurrent to the adsorbate solution flowing downwards over the mass transfer elements, wherein the major part of hydrocarbons present in the adsorbate solution including alkenes desorbed from the adsorbate solution leave the high-pressure flash vessel at the top, wherein the fuel gas is the heating gas which is used for heating the dehydrogenation reactor. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. An apparatus for removing carbon dioxide from a hydrocarbon stream in the preparation of alkenes from alkanes, comprising a gas scrubbing absorption column which contacts an acidic gas-containing process stream with an acidic gas-absorbing solvent, wherein downstream of the absorption column there is a high-pressure flash vessel which depressurizes acidic gas-laden solvent and this high-pressure flash vessel has an inlet for the acidic gas-laden solvent, an inlet for a fuel gas, an outlet for an acidic gas-laden solvent and an outlet for a gaseous hydrocarbon stream.
Specification