Ethane Fraction Separation for High-Ethane Steam Cracker Feeds
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Solution Overview
Problem
Steam cracking plants face challenges in efficiently processing hydrocarbon mixtures with high ethane content, as existing separation technologies are not designed to handle increased ethane levels, leading to capacity issues and economic inefficiencies when transitioning from low-ethane to high-ethane fresh feeds.
Innovation Solution
A method is introduced to separate a predominantly ethane-containing fraction during or after the partial separation of other components from the hydrocarbon mixture, reducing the ethane content in the first fraction to less than 25%, allowing existing separation plants to process it without the need for significant capacity expansions or additional structural efforts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If steam cracking plants process high ethane content hydrocarbon mixtures, then productivity and economic benefit are improved, but separation plant capacity and structural complexity must be significantly expanded
Solution Approach 1:
The separation process is divided into two distinct stages: first separating hydrocarbons with 3+ carbon atoms, then separately removing ethane from the remaining fraction. This segmentation allows existing separation units to handle the C3+ fraction while a dedicated ethane removal unit manages the ethane content, avoiding the need to expand entire separation trains.
Solution Approach 2:
The invention extracts and removes ethane specifically from the hydrocarbon mixture after initial C3+ separation. By taking out the problematic ethane component at a specific stage in the separation process, the solution prevents ethane from overwhelming downstream separation units, thereby maintaining their original capacity while enabling high-ethane feed processing.
2Adaptability or versatility
If existing separation plants process high ethane content mixtures, then adaptability is improved, but manufacturing precision and separation efficiency deteriorate
Solution Approach 1:
The invention performs preliminary C3+ hydrocarbon separation before the ethane-rich fraction reaches downstream separation units. This preliminary action prepares the mixture by removing the bulk of heavier components first, so that subsequent ethane removal occurs in a controlled manner that preserves separation precision in downstream units.
Solution Approach 2:
The process uses an intermediate separation stage where C3+ hydrocarbons are removed as a mediator step between crude cracking and final product separation. This intermediary separation creates a more manageable feed composition for downstream units, allowing them to maintain their design separation efficiency even when processing high-ethane feeds.
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 continued operation of separation systems with minimal changes, effectively managing higher ethane contents and maintaining tolerable ethane levels in downstream facilities, thus simplifying and cost-effectively adapting to increased ethane levels in hydrocarbon feedstocks.
Implementation Method 1
separate a predominantly ethane-containing fraction during or after the at least partial separation of other components from the hydrocarbon mixture
Data Source
Figure 1A~1B
Figure 2~3
Figure 4~5
AI summary
The invention relates to a method for separating a hydrocarbon mixture (C) obtained at least partially by means of steam cracking (10), which hydrocarbon mixture contains at least hydrocarbons having one, two, and three carbon atoms, among them ethane and ethylene, wherein first a first fraction (C2+, C2-) is extracted from the hydrocarbon mixture (C), wherein other components are at least partially removed, which first fraction contains the majority of the hydrocarbons having two and more carbon atoms previously contained in the hydrocarbon mixture (C) or the majority of the hydrocarbons having two and less carbon atoms previously contained in the hydrocarbon mixture (C), wherein further fractions (C1, C2, C2H4, C3+, C2H6) are then extracted from the first fraction (C2+, C2-). In parallel with or after the at least partial removal of the other components from the hydrocarbon mixture (C), a fraction (R, S) containing ethane is removed in an amount that reduces the ethane content in the first fraction (C2+, C2-) to less than 25%, wherein the fraction (R, 2) containing ethane is low in or free from other hydrocarbons having two carbon atoms. The invention further relates to a separating plant (30), to a corresponding steam cracking plant, and to a method for converting a steam cracking plant.