Naphtha Solvent Extraction for Aromatics and Olefins Yield
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Solution Overview
Problem
Conventional methods for producing aromatics and light olefins from naphtha face challenges such as high hydrogen consumption, generation of low-value by-products, and the need for complex and costly processing steps, including hydrodesulphurization and solvent extraction, which result in reduced yields and increased energy expenditure.
Innovation Solution
A method combining solvent extraction and hydrocracking/HDS units to separate naphtha into paraffinic and aromatic/naphthenic streams, allowing for the conversion of naphthenes to aromatics and reduction of paraffinic species, thereby minimizing hydrogen consumption and avoiding the need for pre-hydrodesulphurization, while maximizing the yield of high-value products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional steam cracking is used to produce light olefins and aromatics from naphtha, then light olefins and aromatic species are produced, but low-value C9+ aromatics and condensed aromatics by-products are generated
Solution Approach 1:
The invention segments the naphtha feedstock into different components (aromatics, naphthenes, paraffins) using solvent extraction before cracking. This allows selective processing where aromatics and naphthenes are extracted and cracked separately under optimized conditions, while paraffins are cracked under different conditions, preventing the formation of C9+ and condensed aromatics by-products that occur when all components are cracked together in conventional steam cracking.
2Manufacturing precision
If hydrocracking is used to generate pure aromatics without solvent extraction, then pure aromatics are produced, but very large quantities of hydrogen are required
Solution Approach 1:
The invention extracts aromatics and naphthenes from the naphtha feedstock using solvent extraction before hydrocracking. By removing the aromatic and naphthene components that require hydrogen for conversion, the subsequent hydrocracking step only needs to process the paraffinic components, dramatically reducing hydrogen consumption while still achieving high aromatic purity in the final product.
3Manufacturing precision
If two stages of hydrotreating and solvent extraction are used to produce pure aromatics from Pygas, then pure aromatic compounds are obtained, but processing complexity and energy expenditure increase
Solution Approach 1:
The invention performs preliminary solvent extraction on the naphtha feedstock before cracking to remove aromatics and naphthenes. This preliminary separation allows the cracked products to be obtained with much lower levels of contamination, simplifying downstream purification steps and reducing overall processing complexity while maintaining high aromatic purity.
4Manufacturing precision
If solvent extraction is used to separate aromatics from naphtha, then aromatic species are concentrated, but light non-aromatics and naphthenic species are co-dissolved requiring energy-intensive stripping
Solution Approach 1:
The invention optimizes the solvent extraction parameters including solvent type, temperature, and pressure to maximize the selectivity for aromatics while minimizing co-dissolution of light non-aromatics and naphthenes. By carefully controlling these parameters, the extract contains high concentrations of aromatics with minimal contamination, significantly reducing the energy required for subsequent stripping operations.
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 increases the yield of high-value aromatics and light olefins by reducing the downgrading of naphthenes and paraffinic species, minimizing hydrogen consumption, and simplifying the processing steps, leading to more efficient and cost-effective production.
Implementation Method 1
separating said naphtha in a solvent extraction unit into a raffinate stream comprising paraffinic species and an extract stream comprising aromatic and naphthene species
Implementation Method 2
converting said naphthenes to aromatic species in a hydrocracking unit
Implementation Method 3
organO-sulphur species are converted to H2S in the hydrocracker
Implementation Method 4
naphtha, a mixture of hydrocarbons... can be processed by steam cracking to produce light olefins
Data Source
Figure 1
AI summary
The present invention relates to method of producing aromatics and light olefins from a hydrocarbon feedstock comprising the steps of: (a) subjecting the hydrocarbon feedstock to a solvent extraction process in a solvent extraction unit; (b) separating from the solvent extracted hydrocarbon feedstock obtained in step (a) a raffinate fraction comprising paraffins and a fraction comprising aromatics and naphtenes; (c) converting said fraction comprising aromatics and naphtenes in a hydrocracking unit and separating into a high content aromatics fraction and a stream high in light paraffins;; (d) converting said raffinate fraction in a steam cracking unit into light olefins.