Thiol Oxidation Process Using Segmented Pressure Zones
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Solution Overview
Problem
Current sulfur removal processes in hydrocarbon streams face challenges in using lighter hydrocarbons as wash oil due to vaporization issues at operating pressures and temperatures, necessitating increased plot space and additional vessels for alkali regeneration.
Innovation Solution
A caustic regeneration process that includes a low-pressure oxidizing zone and a high-pressure disulfide separation vessel, utilizing a caustic circulation pump to increase the pressure of the alkaline stream, allowing the use of light hydrocarbons like LPG, C4, or C3 hydrocarbons as wash oil, optimizing operating pressures between 210 kPa to 550 kPa and 690 kPa to 2760 kPa.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If lighter hydrocarbons are used as wash oil, then the sulfur removal efficiency is improved, but the hydrocarbons vaporize at operating pressure and temperature
Solution Approach 1:
The process is divided into two distinct pressure zones: a low-pressure oxidizing zone (210-550 kPa) where oxidation occurs, and a high-pressure separation zone (690-2760 kPa) where disulfide separation occurs. This segmentation allows lighter hydrocarbons to be used as wash oil in the high-pressure zone where they remain liquid, while the oxidation in the low-pressure zone proceeds efficiently.
Solution Approach 2:
The invention changes the pressure parameter between zones - the oxidizing zone operates at lower pressure (210-550 kPa) to prevent vaporization during oxidation, while the separation vessel operates at higher pressure (690-2760 kPa) to maintain lighter hydrocarbons in liquid phase for effective washing and separation.
2Productivity
If additional vessels are added for alkali regeneration, then the sulfur removal process is improved, but the plot space requirement increases
Solution Approach 1:
The invention combines the oxidizing zone and disulfide separation vessel into an integrated system where the pump connects the two zones. This merging eliminates the need for separate alkali regeneration vessels that would otherwise be required, reducing plot space while maintaining process efficiency.
Solution Approach 2:
The high-pressure separation vessel serves multiple functions: it acts as both the disulfide separation vessel and the wash oil contactor. The lighter hydrocarbon wash oil is introduced directly into this vessel to separate disulfides from the alkali stream, eliminating the need for separate washing vessels.
3Productivity
If alkali pressure is increased for separation, then the disulfide separation efficiency is improved, but the pump requirements and energy consumption increase
Solution Approach 1:
The system uses dynamic pressure control where the pump provides just enough pressure increase to move the alkali stream from the low-pressure oxidizing zone to the high-pressure separation zone. The pressure is dynamically adjusted based on the specific operating conditions, optimizing energy consumption while maintaining 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
Enables the effective use of lighter hydrocarbons as wash oil, reducing the need for additional vessels and plot space, while maintaining efficient sulfur removal and regeneration of alkali, thereby improving the overall sulfur extraction process.
Implementation Method 1
passing a thiol rich alkaline stream and an oxygen containing gas to a low pressure oxidizing zone to oxidize at least a portion of the thiol compounds to disulfide compounds
Implementation Method 2
A liquid stream comprising the alkali containing the disulfide compounds is passed through a pump to increase the pressure of the liquid stream comprising the alkali containing the disulfide compounds
Implementation Method 3
The pressurized alkaline stream containing the disulfide compounds and a sulfur lean liquid light hydrocarbon stream are introduced to a high pressure disulfide separation vessel to form a sulfur lean alkaline stream and a sulfur rich liquid light hydrocarbon stream
Data Source
AI summary
A process and apparatus for oxidizing thiol compounds from an alkaline stream. The process includes passing a thiol rich alkaline stream and an oxygen containing gas to a low pressure oxidizing zone to oxidize at least a portion of the thiol compounds to disulfide compounds. A liquid stream comprising the alkali containing the disulfide compounds is passed through a pump to increase the pressure and form a pressurized alkaline stream. The pressurized alkaline stream and a sulfur lean liquid light hydrocarbon stream are introduced to a high pressure disulfide separation vessel to form a sulfur lean alkaline stream and a sulfur rich liquid light hydrocarbon stream.