Two-Stage Pretreatment Reactor for Sulphur Extraction
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Solution Overview
Problem
The existing process for extracting sulphur-containing compounds from hydrocarbons using a soda solution faces inefficiencies due to fluctuations in soda concentration during batch pretreatment, leading to variable sulphur species concentrations and reduced extraction performance, necessitating frequent soda renewal and affecting the efficiency of subsequent countercurrent extraction.
Innovation Solution
A two-stage pretreatment process is implemented, where the first stage is performed in batch mode and the second stage is continuous co-current with a piston flow reactor, using a fresh or spent soda solution to stabilize sulphur compound extraction and improve overall process performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If batch mode pretreatment is used to maximize extraction performance, then extraction efficiency is improved, but soda concentration fluctuates over time requiring frequent renewal
Solution Approach 1:
The single batch pretreatment reactor is divided into two separate batch reactors operating in sequence. The first reactor handles the initial high-concentration sulphur compounds while the second reactor treats the effluent from the first. This segmentation allows each reactor to operate at optimal soda concentration for its specific function, improving overall stability while maintaining high extraction efficiency.
Solution Approach 2:
The first batch reactor performs preliminary extraction of the majority of sulphur-containing compounds before the hydrocarbon enters the second reactor. This preliminary action removes the bulk of contaminants that would otherwise rapidly consume soda in the second reactor, extending the operational life of the soda solution and reducing renewal frequency.
2Productivity
If high soda concentration is used to maintain extraction performance, then extraction efficiency is improved, but soda consumption increases
Solution Approach 1:
Different soda concentrations are used in different stages of the process. The first batch reactor operates with a lower initial soda concentration (2-10% by weight) since it handles the bulk of sulphur compounds. The second batch reactor uses a higher soda concentration to ensure complete removal of remaining sulphur species. This localized optimization of concentration reduces overall soda consumption while maintaining high extraction efficiency throughout the process.
3Stability of the object's composition
If frequent soda renewal is performed to maintain consistent concentration, then extraction performance stability is improved, but process continuity is disrupted
Solution Approach 1:
By dividing the pretreatment into two separate batch reactors, the system can maintain more consistent overall performance. When soda needs renewal in one reactor, the other can continue operating, and the reactors can be staggered to ensure continuous treatment. This segmentation reduces the frequency and impact of soda renewal operations on process continuity.
Solution Approach 2:
The first batch reactor is designed to handle the majority of sulphur compound removal in advance, creating a more stable and manageable load for the second reactor. This preliminary action reduces the rate of soda consumption in the second reactor, extending its operational cycle and reducing the frequency of renewals needed to maintain consistent extraction performance.
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 reduces sulphur compound fluctuations, minimizes soda consumption, and enhances extraction efficiency by maintaining consistent soda concentrations, resulting in a 40% reduction in average sulphur content in the hydrocarbon phase compared to traditional methods.
Implementation Method 1
extraction of sulphur-containing compounds from a hydrocarbon cut (gasoline, LPG, etc.) by liquid-liquid extraction with a soda solution
Implementation Method 2
the soda laden with sodium thiolates is oxidized in the air in the presence of a dissolved catalyst, for example based on cobalt phthalocyanine. In this way, the species of the sodium thiolate type are converted to disulphides
Data Source
AI summary
Process of extracting sulphur-containing compounds from a hydrocarbon cut of the gasoline or LPG type by liquid-liquid extraction with a soda solution employing a unit (2) for pretreatment of the feedstock to be treated located upstream of the unit (4) for extraction with soda, said pretreatment unit consisting of a first pretreatment reactor operating in batch mode followed by a second continuous reactor of the piston type operating in piston mode.