Alkaline Solution Regeneration for Sulfur Extraction

Solution Overview

Problem

Existing processes for regenerating alkaline solutions used in the extraction of sulfur-containing compounds from hydrocarbon cuts require excessive alkaline solution to control temperature during oxidation reactions, leading to increased investment and operating costs, as well as higher inventory needs for alkaline solution and catalyst.

Innovation Solution

The process reduces the excess alkaline solution used for temperature control by employing a partially regenerated alkaline solution depleted in mercaptides but containing residual disulphides, which is recycled back into the oxidation reactor to control temperature, thereby minimizing the overall alkaline solution and catalyst inventory.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If excess alkaline solution is used to control temperature during oxidation reaction, then temperature control is improved, but investment costs and operating costs increase

Engineering Contradiction:

Improvetemperature controlVSAvoidalkaline solution quantity

Core Design Contradiction:

TemperatureVSQuantity of substance

Solution Approach 1:

The invention recovers residual disulphides from the separated alkaline solution and reuses them in the oxidation reaction. This closes the material loop, reducing the need for continuous addition of fresh alkaline solution while maintaining temperature control and reaction efficiency

Inventive Principle:

Principle #34Discarding and recovering

Solution Approach 2:

The invention changes the concentration parameter of disulphides in the alkaline solution by recovering and concentrating them. This allows maintaining effective temperature control with reduced overall alkaline solution volume, as the recovered disulphides provide the necessary thermal mass and reaction control

Inventive Principle:

Principle #35Parameter changes

2Temperature

If excess alkaline solution is used to control temperature during oxidation reaction, then temperature control is improved, but operating costs increase

Engineering Contradiction:

Improvetemperature controlVSAvoidoperating costs

Core Design Contradiction:

TemperatureVSEase of operation

Solution Approach 1:

The invention recovers residual disulphides from the separated alkaline solution and reuses them in the oxidation reaction. This closes the material loop, reducing the need for continuous addition of fresh alkaline solution while maintaining temperature control and reaction efficiency

Inventive Principle:

Principle #34Discarding and recovering

Solution Approach 2:

The system uses its own output (residual disulphides in separated alkaline solution) to serve its input needs (temperature control and reaction maintenance). The recovered disulphides are fed back into the oxidation reactor, creating a self-sustaining process that reduces external material inputs and operating costs

Inventive Principle:

Principle #25Self-service

3Temperature

If excess alkaline solution is used to control temperature during oxidation reaction, then temperature control is improved, but inventory of alkaline solution and catalyst increases

Engineering Contradiction:

Improvetemperature controlVSAvoidinventory of alkaline solution and catalyst

Core Design Contradiction:

TemperatureVSQuantity of substance

Solution Approach 1:

The invention recovers residual disulphides from the separated alkaline solution and reuses them in the oxidation reaction. This closes the material loop, reducing the need for continuous addition of fresh alkaline solution while maintaining temperature control and reaction efficiency

Inventive Principle:

Principle #34Discarding and recovering

Solution Approach 2:

The invention merges the separation and oxidation sections by recycling the separated alkaline solution containing residual disulphides back to the oxidation reactor. This integration reduces the total inventory needed, as the same solution serves multiple functions across different process sections

Inventive Principle:

Principle #5Merging (Combining)

4Temperature

If excess alkaline solution is used to control temperature during oxidation reaction, then temperature control is improved, but energy efficiency decreases

Engineering Contradiction:

Improvetemperature controlVSAvoidenergy efficiency

Core Design Contradiction:

TemperatureVSLoss of energy

Solution Approach 1:

The invention recovers residual disulphides from the separated alkaline solution and reuses them in the oxidation reaction. This closes the material loop, reducing the need for continuous addition of fresh alkaline solution while maintaining temperature control and reaction efficiency

Inventive Principle:

Principle #34Discarding and recovering

Solution Approach 2:

The invention maintains continuous circulation and reuse of the alkaline solution containing recovered disulphides. This continuous action eliminates the need for repeated heating and processing of fresh solution, significantly reducing energy consumption while maintaining effective temperature control

Inventive Principle:

Principle #20Continuity of useful action

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 the investment costs, operating costs, and energy consumption while maintaining the exothermicity of the oxidation reaction, improving energy efficiency and reducing the consumption and purge of alkaline solution and catalyst during transient phases.

Implementation Method 1

Regeneration of the alkaline solution consists of an exothermic oxidation reaction in the presence of a catalyst converting mercaptide type species into disulphides

Methodology Applied

Scientific EffectOxidation: Oxidation

Implementation Method 2

said cooling means being constituted by an excess alkaline solution sent directly to said reactor

Methodology Applied

Scientific EffectHeat transfer: Heat Exchanger

Implementation Method 3

The separation of the effluents from the reactor produces, on the one hand, a partially regenerated alkaline solution, and on the other hand a hydrocarbon phase which is rich in disulphides

Methodology Applied

Scientific EffectPhase separation: Density Gradient

Data Source

PatentUS10780398B2Process for the regeneration of an alkaline solution used in a process for the extraction of sulphur-containing compounds not comprising a washing step

Publication Date: 2020.09.22 AXENS SA

AI summary

The present invention relates to the field of extraction of sulphur-containing compounds such as mercaptans, COS, H2S or CS2 from a hydrocarbon cut. This selective extraction is carried out by bringing the hydrocarbon cut in the liquid phase into contact with an alkaline solution, for example caustic soda. The process in accordance with the invention is an improved process for the regeneration of alkaline solution which can be used to reduce the quantity of alkaline solution necessary in the regeneration section.