Dividing Wall Distillation for Para-Xylene Production
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Solution Overview
Problem
The production of para-xylene from catalytic reformate requires numerous costly fractionation steps, leading to high capital and operating costs, and there is a need for more energy-efficient methods to separate C7−, C8, and C9+ aromatic hydrocarbon fractions.
Innovation Solution
The use of dividing wall distillation columns to separate C6+ hydrocarbon fractions into C7−, C8, and C9+ aromatic hydrocarbon streams, allowing for the recovery of benzene and toluene, followed by transalkylation and xylene isomerization to enhance para-xylene production, while reducing energy consumption and hardware costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional multiple distillation steps are used to separate C7−, C8, and C9+ aromatic hydrocarbon fractions, then separation precision is improved, but device complexity and energy consumption increase
Solution Approach 1:
The patent combines multiple distillation functions into a single dividing wall distillation column that simultaneously separates C7−, C8, and C9+ aromatic hydrocarbon fractions. The dividing wall creates multiple separation zones within one column, achieving the separation precision of multiple columns while reducing device complexity and hardware costs.
Solution Approach 2:
The patent introduces a spatial dimension by adding a dividing wall that partitions the distillation column into separate sections. This dimensional change allows simultaneous separation of multiple fraction ranges (C7−, C8, C9+) within a single column structure, improving separation efficiency while reducing the number of required columns.
2Measurement precision
If conventional multiple distillation steps are used to separate C7−, C8, and C9+ aromatic hydrocarbon fractions, then separation precision is improved, but energy consumption increases
Solution Approach 1:
The patent combines multiple distillation functions into a single dividing wall distillation column that simultaneously separates C7−, C8, and C9+ aromatic hydrocarbon fractions. The dividing wall creates multiple separation zones within one column, achieving the separation precision of multiple columns while reducing device complexity and energy consumption.
Solution Approach 2:
The dividing wall distillation column enables continuous simultaneous separation of multiple fraction ranges in a single pass through the column. This continuous multi-functional separation eliminates the need for sequential distillation steps, reducing cumulative energy consumption while maintaining high separation precision for all fractions.
3Reliability
If conventional multiple distillation columns are used, then separation effectiveness is improved, but hardware cost increases
Solution Approach 1:
The patent combines multiple distillation functions into a single dividing wall distillation column that simultaneously separates C7−, C8, and C9+ aromatic hydrocarbon fractions. The dividing wall creates multiple separation zones within one column, achieving the separation precision of multiple columns while reducing device complexity and hardware costs.
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 cost-effective separation of hydrocarbon streams, reducing energy consumption and hardware requirements, thereby lowering the overall cost of para-xylene production and improving the efficiency of the para-xylene production process.
Implementation Method 1
dividing wall distillation columns provide effective and energy-efficient means for separating hydrocarbon streams, particularly the C7−, C8, and C9+-containing fractions
Implementation Method 2
separate the feed into a C7− aromatic hydrocarbon-containing stream, a C8 aromatic hydrocarbon-containing stream and a C9+ aromatic hydrocarbon-containing stream
Implementation Method 3
contacted with a xylene isomerization catalyst in a xylene isomerization zone under conditions effective to isomerize xylenes in the para-xylene depleted stream
Implementation Method 4
contacted with a transalkylation catalyst under conditions effective to produce a transalkylation product containing xylenes
Data Source
AI summary
In a process for producing para-xylene, at least one feed comprising C6+ aromatic hydrocarbons is supplied to a dividing wall distillation column to separate the feed into a C7− aromatic hydrocarbon-containing stream, a C8 aromatic hydrocarbon-containing stream and a C9+ aromatic hydrocarbon-containing stream. At least part of the C8 aromatic hydrocarbon-containing stream is then supplied to a para-xylene recovery unit to recover para-xylene from the C8 aromatic hydrocarbon-containing stream and produce a para-xylene depleted stream. The para-xylene depleted stream is contacted with a xylene isomerization catalyst in a xylene isomerization zone under conditions effective to isomerize xylenes in the para-xylene depleted stream and produce an isomerized stream, which is then at least partially recycled to the para-xylene recovery unit.