Caustic Fluid Sulfur Purification via Hydrocarbon Solvent Extraction
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Solution Overview
Problem
In mercaptan removal systems, disulfide oil carried back to the final hydrocarbon product increases sulfur content, exceeding target specifications, necessitating an improved method for sulfur removal from caustic streams.
Innovation Solution
A method involving mixing a caustic fluid with a hydrocarbon solvent at elevated pressure, followed by filtration through a prefilter assembly and a liquid-liquid coalescer, to reduce sulfur content, utilizing a system with specific pressure and temperature ranges and components like porous prefilter and liquid-liquid coalescer elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If disulfide oil is carried back to the final hydrocarbon product, then the sulfur content of the product increases, but the target specification is exceeded
Solution Approach 1:
The patent extracts disulfide oil from the caustic stream using a hydrocarbon solvent in an extraction column. The solvent selectively dissolves the disulfide oil, separating it from the caustic fluid. This extracted disulfide oil-solvent mixture is then processed further to remove the sulfur compounds before the hydrocarbon product is finalized, ensuring sulfur content specifications are met.
Solution Approach 2:
The patent introduces a hydrocarbon solvent as an intermediary substance to facilitate the removal of disulfide oil from the caustic stream. This solvent acts as a mediator that selectively interacts with the disulfide oil, enabling its separation and subsequent removal from the system, thereby preventing sulfur contamination of the final hydrocarbon product.
2Productivity
If hydrocarbon solvent is injected at high pressure into mixing valve, then mixing efficiency improves, but pressure differential requirements increase
Solution Approach 1:
The patent employs a dynamic mixing valve design that allows adjustment of pressure differential to optimize mixing efficiency. The system dynamically balances the high pressure injection of hydrocarbon solvent with the caustic stream flow, maintaining optimal mixing conditions while managing pressure requirements through controllable valve operation.
Solution Approach 2:
The patent utilizes hydraulic principles in the mixing valve where high-pressure hydrocarbon solvent is injected into the caustic stream. The pressure differential (10-50 psid) creates turbulent mixing conditions that enhance mass transfer efficiency, leveraging fluid dynamics to achieve thorough mixing without requiring excessive pressure.
3Loss of energy
If prefilter assembly operates at low pressure differential, then energy consumption decreases, but filtration effectiveness may be compromised
Solution Approach 1:
The patent divides the filtration process into two stages: a prefilter assembly for initial solids removal and a liquid-liquid coalescer for finer separation. This segmentation allows the prefilter to operate at low pressure differential (1-25 psid) while still achieving effective filtration by handling the bulk solids removal, with the coalescer addressing remaining liquid droplets.
Solution Approach 2:
The prefilter assembly utilizes porous filtering elements that provide large surface area and appropriate pore sizes for effective solids removal at low pressure differentials. The porous structure enables efficient particle capture without requiring high pressure, maintaining both energy efficiency and filtration effectiveness.
4Loss of energy
If liquid-liquid coalescer assembly operates at low pressure differential, then operational cost decreases, but separation efficiency must be maintained
Solution Approach 1:
The liquid-liquid coalescer assembly employs porous coalescing media with specific pore size distributions that facilitate liquid droplet coalescence at low pressure differentials (1-15 psid). The porous structure provides numerous nucleation sites for droplet formation and coalescence, enabling efficient liquid-liquid separation without requiring high pressure.
Solution Approach 2:
The coalescer assembly extends the separation process into the vertical dimension with multiple stages or layers of coalescing media. This dimensional approach allows gravity to assist the separation process, reducing the need for high pressure differential while maintaining effective liquid-liquid separation efficiency.
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
Effectively reduces sulfur content in the caustic fluid, ensuring the hydrocarbon product meets target specifications by separating sulfur from the hydrocarbon solvent, maintaining low sulfur levels in the final product.
Implementation Method 1
mixing a caustic fluid including sulfur with a hydrocarbon solvent
Implementation Method 2
passing the caustic fluid including sulfur mixed with hydrocarbon solvent through a prefilter assembly
Implementation Method 3
passing the solids-depleted caustic fluid including sulfur mixed with hydrocarbon solvent through a liquid-liquid coalescer assembly
Data Source
AI summary
Methods and systems for purifying a caustic fluid including sulfur are provided.