Method for separating a hydrocarbon mixture
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Solution Overview
Problem
Steam cracking plants face challenges in managing high ethane content in cracked gases when using ethane-rich hydrocarbon mixtures, leading to increased structural and operational demands on separation units, which nullifies economic benefits and complicates the conversion of plants from low-ethane to high-ethane feeds.
Innovation Solution
A method that involves separating an ethane-containing fraction from the cracked gas before further processing, reducing the ethane content in the first fraction to levels manageable by existing separation plants, allowing for continued operation without significant capacity expansions or additional structural efforts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If ethane-rich hydrocarbon mixtures are used as furnace feed, then the quantity of valuable ethylene product is improved, but the ethane content in cracked gas increases leading to higher separation complexity and structural demands
Solution Approach 1:
The separation process is divided into multiple stages: first separating light ends (C1-C2), then separating C3-C4 fractions, and finally handling the C5+ fraction. This segmentation allows each separation unit to handle specific components efficiently, managing the high ethane content through systematic fractionation rather than requiring a single complex separation system.
Solution Approach 2:
A C2 splitter column is introduced as an intermediary separation unit between the demethanizer and the C3-C4 separator. This intermediary unit specifically addresses the ethane enrichment problem by separating ethane from the C2 fraction, allowing the downstream separation units to operate with reduced ethane content and avoiding the need for significant capacity expansions.
2Adaptability or versatility
If existing olefin production plants are adapted for high-ethane feeds, then processing capability is improved, but significant additional structural effort and capacity expansion are required
Solution Approach 1:
The invention provides operational flexibility by allowing the C2 splitter to operate at different load conditions and by enabling dynamic adjustment of separation parameters. This dynamic operation allows the plant to adapt to varying ethane content in the feed without requiring physical structural changes, maintaining processing capability while avoiding additional manufacturing effort.
Solution Approach 2:
The invention utilizes parameter changes in the separation process, specifically adjusting temperature, pressure, and reflux ratios in the C2 splitter and other separation units to optimize ethane separation. By changing operational parameters rather than structural configuration, the plant achieves adaptability to high-ethane feeds without significant additional structural effort.
3Productivity
If separation units are expanded to handle high ethane content, then processing capacity is improved, but costs increase nullifying economic benefits
Solution Approach 1:
The C2 splitter performs preliminary separation of ethane from the C2 fraction before the material enters downstream separation units. This preliminary action prevents ethane from accumulating in subsequent units, allowing them to operate at their original design capacity without expansion. The pre-separation approach maintains processing capacity while avoiding the costs associated with expanding downstream units.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the processing of high-ethane content gases within existing separation systems, maintaining operational efficiency and reducing costs by adjusting the ethane content to levels comparable to low-ethane feed scenarios, thus preserving the economic benefits of using ethane-rich feeds.
Implementation Method 1
a first fraction is obtained from the hydrocarbon mixture with at least partial separation of other components
Data Source
Figure 1A~1B
Figure 2~3
Figure 4~5
AI summary
The invention relates to a process for separating a hydrocarbon mixture (C) obtained at least partially by steam cracking (10) and containing at least hydrocarbons having one, two and three carbon atoms, including ethane and ethylene, wherein the hydrocarbon mixture (C) is initially separated from at least partially Separation of other components, a first fraction (C2+) is obtained, which contains the majority of the hydrocarbons previously contained in the hydrocarbon mixture (C) with two or more carbon atoms, with further fractions (C2, C2H4, C3+ , C2H6) can be obtained. After the other components have been at least partially separated off and before the further fractions (C2, C2H4, C3+, C2H6) are obtained from the hydrocarbon mixture (C), an ethane-containing fraction (R, S) is separated off in an amount which reduces the ethane content in the first fraction (C2+,C2-) is reduced to less than 25%, the ethane-containing fraction (R,S) containing at most 10% on a molar basis of other hydrocarbons having two carbon atoms. A separation plant (30) is also the subject of the present invention.