Low cost thermal coupling in ethylene recovery
First Claim
1. A process for fractionation of a mixture of light hydrocarbons containing at least hydrogen, methane, ethylene, and ethane and optionally propylene and heavier hydrocarbons comprising:
- (a) achieving a product-quality separation of at least a portion of the light hydrocarbons comprising hydrogen, methane, ethylene and ethane in a first integrator column to produce a first overhead stream and a first bottoms stream;
(b) fractionating the first overhead stream to produce a second bottoms stream comprising substantially a portion of a single component of one of said light hydrocarbons; and
(c) fractionating the first bottoms stream separately from the first overhead stream to produce a second overhead stream comprising substantially the remaining portion of the said single light hydrocarbon component in (b).
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Abstract
The invention is a process for reducing capital and energy costs in ethylene recovery. Moderate pressure processing and thermally coupled fractionation steps are achieved through the use of integrator columns. Ethylene separation from cracked gas originating from ethane through gas oil feeds can now be done with thermodynamically efficient fractionation at capital cost competitive with low efficiency designs. Acetylene hydrogenation may be done before demethanization where desired, and dephlegmation is preferred to accomplish high-efficiency rectification of hydrogen and methane from ethylene. Open loop heat pumps can optionally be incorporated into the ethane/ethylene splitter fractionation step, whose desirability is controlled by optimization of capital and energy costs.
59 Citations
21 Claims
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1. A process for fractionation of a mixture of light hydrocarbons containing at least hydrogen, methane, ethylene, and ethane and optionally propylene and heavier hydrocarbons comprising:
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(a) achieving a product-quality separation of at least a portion of the light hydrocarbons comprising hydrogen, methane, ethylene and ethane in a first integrator column to produce a first overhead stream and a first bottoms stream; (b) fractionating the first overhead stream to produce a second bottoms stream comprising substantially a portion of a single component of one of said light hydrocarbons; and (c) fractionating the first bottoms stream separately from the first overhead stream to produce a second overhead stream comprising substantially the remaining portion of the said single light hydrocarbon component in (b). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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Specification