Sequential Hydroconversion and Desulfurization of Crude Oil
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Solution Overview
Problem
The processing of heavy crude oils faces challenges due to contaminants like organic nickel and vanadium compounds, which reduce catalyst activity and lifetime, and high concentrations of coke precursors, leading to frequent catalyst replacement and reduced economic feasibility, especially in hydrodesulfurization processes.
Innovation Solution
A catalytic hydrotreating process using a bimodal support material with specific pore sizes and metal compositions in two reactors, where the first reactor employs a hydroconversion catalyst to reduce asphaltene content and the second reactor uses a desulfurization catalyst to produce a low-sulfur, high-API gravity crude oil product, operating at different temperatures to extend catalyst life and reduce downtime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional hydrodesulfurization processes are used on heavy crude oil, then sulfur removal is achieved, but catalyst activity and lifetime are reduced due to metal deposition from nickel and vanadium compounds
Solution Approach 1:
The hydroprocessing unit is divided into multiple reaction zones or stages, allowing the catalyst to be protected from direct exposure to high concentrations of metal contaminants in heavy crude oil. This segmentation enables the catalyst to maintain activity longer by processing partially treated streams rather than raw heavy crude continuously.
Solution Approach 2:
A preliminary treatment step is implemented before the main hydrodesulfurization process to remove or reduce the concentration of nickel and vanadium compounds from the heavy crude feedstock. This preliminary action prevents metal deposition on the catalyst, thereby extending catalyst lifetime and reducing replacement frequency.
2Productivity
If operating temperature is increased to maintain catalyst performance, then catalyst activity is improved, but catalyst lifetime is reduced due to accelerated deactivation
Solution Approach 1:
The process operates at optimized moderate temperatures rather than maximum temperatures, balancing catalyst activity with catalyst stability. By carefully controlling temperature parameters and using appropriate catalyst formulations, the system achieves acceptable conversion rates while minimizing thermal deactivation and extending catalyst operational life.
3Reliability
If catalyst replacement is performed frequently to maintain performance, then product quality is maintained, but process downtime and operational costs increase
Solution Approach 1:
By implementing preliminary contaminant removal and optimizing feedstock treatment, the catalyst operates in a cleaner environment that extends its effective lifetime. This reduces the frequency of catalyst replacements and minimizes process downtime while maintaining consistent product quality standards.
Solution Approach 2:
The process is designed to maintain continuous operation with extended catalyst run lengths. By preventing rapid catalyst deactivation through feedstock pretreatment and optimized operating conditions, the system achieves longer continuous production periods without interruption, improving overall plant availability and reducing maintenance-related downtime.
4Productivity
If hydroprocessing of whole crude oil is performed, then processing efficiency is improved, but coke formation increases leading to catalyst deactivation
Solution Approach 1:
The hydroprocessing of whole crude oil is divided into multiple reaction stages, with intermediate separation or treatment steps that remove coke precursors before they can polymerize and form heavy coke deposits on the catalyst. This segmentation maintains high processing efficiency while reducing catalyst deactivation from coke formation.
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 process effectively reduces sulfur content and increases API gravity of crude oil, extending catalyst life and reducing downtime by maintaining catalyst performance and minimizing the need for frequent replacement, thus enhancing the economic feasibility of the hydroprocessing unit.
Implementation Method 1
contacting the hydrogen gas crude oil mixture with a hydroconversion catalyst in a first reactor maintained at a temperature of between about 400° C. and 450° C. to produce an effluent having an asphaltene content of less than 5% by weight
Implementation Method 2
contacting the effluent hydrogen gas mixture with a desulfurization catalyst in a second reactor to produce an upgraded crude oil product having a reduced sulfur content
Implementation Method 3
contacting a crude oil feedstock with hydrogen gas to produce a hydrogen gas crude oil mixture
Data Source
AI summary
The invention relates to a method for removing sulfur from crude oils using a catalytic hydrotreating process operating at moderate temperature and pressure and reduced hydrogen consumption. The process produces sweet crude oil having a sulfur content of between about 0.1 and 1.0 wt % in addition to reduced crude density. The method employs least two reactors in series, wherein the first reactor includes a hydroconversion catalyst and the second reactor includes a desulfurization catalyst.