Aromatic Hydrocarbon Production via Segmented Distillation and Hydrodealkylation
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Solution Overview
Problem
Conventional processes for producing aromatic hydrocarbons, such as styrene and BTX components, are energy-intensive and complex, involving unnecessary steps and high hydrogen consumption due to the inclusion of C7+ hydrocarbons in raw material streams, leading to increased costs and energy consumption.
Innovation Solution
An apparatus that selectively produces styrene and BTX components by separating C6, C7, and C8 hydrocarbons in distinct columns, reducing hydrogen usage and eliminating redundant processes, with a second gasoline hydrogenation unit for direct xylene production, thereby simplifying the process and reducing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If C7+ hydrocarbons are included in the raw material stream for gasoline hydrogenation, then the production capacity is maintained, but hydrogen consumption increases and process complexity increases
Solution Approach 1:
The raw material stream is segmented into different carbon number ranges (C6- and C7+) through separation columns. The C6- fraction is directed to gasoline hydrogenation while the C7+ fraction is routed to hydrodealkylation, preventing unnecessary hydrogen consumption in the GHT unit while maintaining overall production capacity.
Solution Approach 2:
The C7+ hydrocarbon fraction is extracted and removed from the raw material stream before gasoline hydrogenation. This extraction prevents the harmful effect of increased hydrogen consumption while the extracted fraction is processed through an alternative route (hydrodealkylation) to maintain productivity.
2Productivity
If C7+ hydrocarbons are subjected to hydrodealkylation and mixed again after gasoline hydrogenation, then benzene production is achieved, but energy consumption doubles
Solution Approach 1:
The process is segmented into two parallel pathways: C6- hydrocarbons go through gasoline hydrogenation while C7+ hydrocarbons go through hydrodealkylation. This segmentation eliminates the need for repeated processing and mixing, reducing energy consumption while maintaining benzene production capacity.
Solution Approach 2:
The C7+ hydrocarbons undergo hydrodealkylation in advance before potential mixing with C6- stream. This preliminary action converts the C7+ fraction to benzene and other products that can be directly combined with GHT output, eliminating the need for a second round of processing and reducing overall energy consumption.
3Productivity
If the total raw material stream is supplied to gasoline hydrogenation, then all components are processed, but hydrogen consumption increases due to increased flow rate
Solution Approach 1:
The raw material stream is divided into C6- and C7+ fractions through separation columns. Only the C6- fraction is supplied to gasoline hydrogenation at optimized flow rates, while C7+ is processed separately through hydrodealkylation, thereby reducing total hydrogen consumption while maintaining overall processing throughput.
Solution Approach 2:
Different quality processing is applied to different fractions: the C6- fraction receives gasoline hydrogenation treatment while the C7+ fraction receives hydrodealkylation treatment. This local differentiation optimizes hydrogen usage by applying hydrogenation only where necessary while maintaining overall productivity.
4Productivity
If prefraction process is performed after gasoline hydrogenation to separate benzene, toluene, and xylene, then BTX components are obtained, but the process becomes more complicated
Solution Approach 1:
The C7+ fraction undergoes hydrodealkylation in advance, which converts ethylbenzene and other C8+ components into benzene and lighter hydrocarbons. This preliminary conversion simplifies subsequent separation steps because the feed stream already contains benzene from hydrodealkylation, reducing the complexity of BTX separation compared to processing the total stream through GHT first.
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
The apparatus achieves efficient production of styrene and BTX components with reduced energy use and simplified processes, maximizing product output while minimizing hydrogen consumption and catalyst degradation.
Implementation Method 1
a C6 separation column (DeC6) supplied with a raw material stream... supplying an upper discharge stream to a first gasoline hydrogenation (hydrodesulfurization) unit, and supplying a lower discharge stream to a C7 separation column
Implementation Method 2
a C7 separation column (DeC7) supplied with the lower discharge stream from the C6 separation column (DeC6)... supplying an upper discharge stream to the first gasoline hydrogenation unit or a hydrodealkylation (dealkylation) reaction unit, and supplying a lower discharge stream to a C8 separation column
Implementation Method 3
a C8 separation column (DeC8) supplied with the lower discharge stream from the C7 separation column (DeC7)... supplying an upper discharge stream to a second extractive distillation column (2nd EDC)
Implementation Method 4
a first gasoline hydrogenation unit (1st GHT) supplied with the upper discharge stream from the C6 separation column (DeC6)... to perform a hydrodesulfurization reaction
Implementation Method 5
a second gasoline hydrogenation unit (2nd GHT) supplied with the upper discharge stream from the second extractive distillation column (2nd EDC)... to perform a hydrodesulfurization reaction
Implementation Method 6
a hydrodealkylation reaction unit (HDA)... supplied with the upper discharge stream from the C7 separation column (DeC7)... and the upper discharge stream from the second extractive distillation column (2nd EDC) to perform a hydrodealkylation reaction
Implementation Method 7
a second extractive distillation column (2nd EDC) supplied with the upper discharge stream from the C8 separation column (DeC8)... supplying an upper discharge stream to a second gasoline hydrogenation unit (2nd GHT) or the hydrodealkylation reaction unit (HDA)
Data Source
AI summary
An apparatus for producing aromatic hydrocarbons including: a C6 separation column; a C7 separation column; a first gasoline hydrogenation unit; a C8 separation column; an extractive distillation column; a hydrodealkylation reaction unit; and a second gasoline hydrogenation unit.