Hydrocarbon Deethanization Without C3 Absorber to Reduce Complexity
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Solution Overview
Problem
Current processes for separating hydrocarbon gas mixtures, such as those resulting from steamcracking, are complex and inefficient due to the use of C3 absorbers and intermediate coolers, leading to high instrumentation complexity and safety expenditures.
Innovation Solution
A deethanization and demethanization process that employs partial condensation steps without absorbers, followed by rectification at lower pressures, allowing for the separation of hydrogen, methane, and hydrocarbons with two or more carbon atoms, thereby simplifying the process and reducing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If C3 absorber and intermediate cooler are used in deethanization and demethanization, then separation effectiveness is improved, but device complexity and safety expenditure increase
Solution Approach 1:
The patent removes the C3 absorber and intermediate cooler from the separation sequence, replacing them with a simplified arrangement where the deethanizer column directly feeds the demethanizer column. This extraction of unnecessary equipment reduces device complexity while maintaining separation effectiveness through optimized column operation parameters.
Solution Approach 2:
Instead of using the conventional approach of adding multiple absorption and cooling stages to achieve separation, the patent inverts the approach by using a minimal two-column sequence with optimized operating conditions. The demethanizer is positioned to receive feed directly from the deethanizer, and operating pressures are optimized to achieve the required separation without additional equipment.
2Manufacturing precision
If conventional deethanization and demethanization sequence is used, then separation of hydrocarbon fractions is achieved, but energy consumption increases
Solution Approach 1:
The patent optimizes operating parameters including pressure levels and temperature profiles in the deethanizer and demethanizer columns. By carefully selecting and adjusting these parameters, the process achieves high-purity fraction separation while minimizing the energy required for heating, cooling, and compression operations.
Solution Approach 2:
The patent designs the pressure levels between columns to create an equipotential flow pattern, where the demethanizer operates at a pressure that allows efficient utilization of the cold stream from the deethanizer overhead condenser for cooling purposes, thereby reducing external refrigeration requirements and overall energy consumption.
3Productivity
If high pressure operation is used in rectification, then separation efficiency is improved, but fouling and safety risks increase
Solution Approach 1:
The patent optimizes the operating pressure of the rectification columns to achieve an optimal balance between separation efficiency and fouling prevention. By selecting specific pressure ranges and adjusting temperature profiles accordingly, the process maintains high separation efficiency while operating conditions that minimize fouling and safety risks are established.
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 significantly reduces the complexity and cost of hydrocarbon separation, achieving high purity fractions with lower energy consumption and reduced fouling, while eliminating the need for C3 absorbers and complex condensation systems.
Implementation Method 1
the gas mixture is subjected to a first cooling at 36 bar to −30 to −40° C. After the first cooling, a first phase separation takes place in a first vessel
Implementation Method 2
The gas phase from the first vessel is subjected to a second cooling, namely to −45° C. This second cooling is followed by a second phase separation in a second vessel
Implementation Method 3
The liquid phases from the first and second vessel are fed into a column operated at 30 bar
Data Source
AI summary
The invention relates to a process for separating a component mixture (K) comprising hydrogen, methane, hydrocarbons having two carbon atoms and hydrocarbons having three or more carbon atoms, wherein in a deethanization at least a portion of the component mixture (K) is subjected to a first partial condensation by cooling from a first temperature level to a second temperature level at a first pressure level to obtain a first gas fraction (G1) and a first liquid fraction (C1), at least a portion of the first gas fraction (G1) is subjected to a second partial condensation by cooling from the second temperature level to a third temperature level at the first pressure level to obtain a second gas fraction (G4) and a second liquid fraction (C2), and at least a portion of the first liquid fraction (C1) and at least a portion of the second liquid fraction (C2) are subjected to a rectification to obtain a third gas fraction (G3) and a third liquid fraction (C3+). The first liquid fraction (C1) or its part subjected to the rectification and the second liquid fraction (C2) or its part subjected to the rectification are expanded to a second pressure level and the rectification is carried out at the second pressure level, the first pressure level being 25 to 35 bar and the second pressure level being 14 to 17 bar. An overhead gas formed during the rectification is cooled to −25 to −35° C. and partially condensed, wherein a condensed portion of the overhead gas is used partially or completely as a reflux in the rectification and an uncondensed portion of the overhead gas is provided partially or completely as the third gas fraction (G3). The present invention likewise provides a corresponding plant (100, 200).