Process for producing ethylene
First Claim
1. A process for the production of an ethylene product stream front an oxygenate conversion effluent stream comprising hydrogen, methane, ethylene, ethane, propylene, propane, and C4-plus olefins said process comprising:
- a) passing the oxygenate conversion effluent stream to a deethianizer zone to provide a light hydrocarbon feedstream comprising hydrogen, methane, ethylene and ethane, and a deethanized stream comprising propylene, propane, and C4-plus olefins;
b) passing the light hydrocarbon stream to a demethanizer zone operating at a demethanizing temperature greater than about −
45°
C. to provide a bottom stream comprising ethylene and ethane and an overhead stream comprising hydrogen, methane, and ethylene;
c) passing the overhead stream at effective adsorption conditions to an adsorption zone containing at least two adsorption beds, each of said adsorption beds containing a selective adsorbent to adsorb the ethylene on adsorption to produce an adsorber effluent stream comprising hydrogen and methane, and on desorption to produce a desorbed stream comprising ethylene and immediately following adsorption withdrawing a vent stream comprsing hydrogen and methane in a cocurrent depressurization step which is terminated prior to the breakthrough of ethylene;
d) passing the bottom stream to a C2 splitter zone to produce the ethylene product stream and an ethane stream; and
e) combining the desorbed stream with the oxygenate conversion effluent stream prior to passing the oxygenate conversion effluent stream to the demethanizer zone.
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Abstract
A process is provided for the concentration and recovery of ethylene and heavier components from an oxygenate conversion process. A separation process such as a pressure swing adsorption (PSA) process is used to remove hydrogen and methane from a demethanizer overhead stream comprising hydrogen, methane and C2 hydrocarbons and subsequently return the recovered C2 hydrocarbons to be admixed with the effluent from the oxygenate conversion process. This integration of a separation zone with a fractionation scheme in an ethylene recovery scheme using an initial demethanizer zone resulted in significant capital and operating cost savings by the elimination of cryogenic ethylene-based refrigeration from the overall recovery scheme.
98 Citations
17 Claims
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1. A process for the production of an ethylene product stream front an oxygenate conversion effluent stream comprising hydrogen, methane, ethylene, ethane, propylene, propane, and C4-plus olefins said process comprising:
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a) passing the oxygenate conversion effluent stream to a deethianizer zone to provide a light hydrocarbon feedstream comprising hydrogen, methane, ethylene and ethane, and a deethanized stream comprising propylene, propane, and C4-plus olefins;
b) passing the light hydrocarbon stream to a demethanizer zone operating at a demethanizing temperature greater than about −
45°
C. to provide a bottom stream comprising ethylene and ethane and an overhead stream comprising hydrogen, methane, and ethylene;
c) passing the overhead stream at effective adsorption conditions to an adsorption zone containing at least two adsorption beds, each of said adsorption beds containing a selective adsorbent to adsorb the ethylene on adsorption to produce an adsorber effluent stream comprising hydrogen and methane, and on desorption to produce a desorbed stream comprising ethylene and immediately following adsorption withdrawing a vent stream comprsing hydrogen and methane in a cocurrent depressurization step which is terminated prior to the breakthrough of ethylene;
d) passing the bottom stream to a C2 splitter zone to produce the ethylene product stream and an ethane stream; and
e) combining the desorbed stream with the oxygenate conversion effluent stream prior to passing the oxygenate conversion effluent stream to the demethanizer zone. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification