Ethane Separation Unit for Steam Cracking Capacity Adaptation
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Solution Overview
Problem
Steam cracking systems face challenges in efficiently processing hydrocarbon mixtures with high ethane content, as existing separation systems are not equipped to handle increased ethane levels, requiring significant additional construction or capacity upgrades, which is economically unfavorable.
Innovation Solution
A method is introduced to reduce the ethane content in the first fraction of the hydrocarbon mixture to less than 25% by incorporating an additional separation unit, either in parallel or downstream from the demethaniser or deethaniser, allowing existing separation systems to process ethane-rich feedstocks without the need for extensive upgrades.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing separation systems process ethane-rich feedstocks, then the capacity to handle natural gas liquids and shale gas is improved, but the separation system requires significant additional constructional outlay or capacity increases
Solution Approach 1:
The separation system is divided into multiple functional units: a first separation unit (demethanizer) that removes methane to produce a C2+ fraction, and a second separation unit (deethanizer) that processes this fraction to remove ethane. This segmentation allows each unit to be optimized for its specific function, enabling the system to handle ethane-rich feedstocks without requiring a complete system overhaul.
Solution Approach 2:
The first separation unit performs preliminary separation by removing methane from the feedstock before the second separation unit handles ethane removal. This preliminary action simplifies the workload of the second unit and allows the system to efficiently process ethane-rich feedstocks by pre-concentrating the ethane content in the C2+ fraction.
2Adaptability or versatility
If multiple series of separation units are provided to handle high ethane content, then the separation capability is improved, but the device complexity and constructional effort increase considerably
Solution Approach 1:
The second separation unit is designed to perform multiple functions: it receives and processes the C2+ fraction from the first separation unit, removes ethane to produce a C3+ fraction, and can handle varying ethane concentrations from different feedstock sources. This multi-functionality eliminates the need for multiple separate separation series while maintaining the capability to process ethane-rich mixtures.
3Productivity
If the capacity of separation units is increased to handle ethane-rich cracked gas, then the processing capacity is improved, but the constructional effort and cost increase significantly
Solution Approach 1:
The processing capacity is distributed across two separation units with specialized functions. The first unit handles methane removal for all feedstock types, while the second unit is optimized for ethane removal from the C2+ fraction. This segmentation allows each unit to operate at optimal capacity without requiring excessive enlargement of the entire system.
Solution Approach 2:
By removing methane in the first separation unit before ethane removal in the second unit, the system efficiently manages ethane-rich feedstocks without requiring the second unit to handle the full feedstock flow. This preliminary action concentrates the ethane removal task on a smaller, more efficiently sized second separation unit.
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 existing steam cracking systems to handle ethane-rich feedstocks without significant modifications, maintaining operational efficiency and reducing costs associated with upgrading separation units, thus facilitating the use of economically advantageous ethane-rich hydrocarbon mixtures.
Implementation Method 1
a first fraction is obtained from the hydrocarbon mixture by separating off other components at least in part
Implementation Method 2
further fractions are subsequently obtained from the first fraction
Data Source
AI summary
A method for separating a hydrocarbon mixture, which is obtained at least in part by steam cracking and which contains at least hydrocarbons having one, two and three carbon atoms, including ethane and ethylene, a first fraction initially being obtained from the hydrocarbon mixture by separating off other components at least in part, said fraction containing the predominant part of the hydrocarbons having two or more carbon atoms previously contained in the hydrocarbon mixture or the predominant part of the hydrocarbons having two or fewer carbon atoms previously contained in the hydrocarbon mixture, further fractions subsequently being obtained from the first fraction. A fraction containing ethane is separated off in an amount which reduces the ethane content in the first fraction to less than 25%, the fraction containing ethane being low in or free from other hydrocarbons having two carbon atoms.