On-line Sulfur Speciation for Hydroprocessing Control
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Solution Overview
Problem
Current hydroprocessing technologies face challenges in efficiently removing sterically hindered sulfur compounds due to increased hydrotreating severity and catalyst poisoning, leading to decreased catalyst life and higher maintenance costs, especially with the stringent sulfur regulations in diesel fuel refining.
Innovation Solution
Implementing an on-line gas analyzer with a sulfur specific detector, such as a gas chromatograph/atomic emissions detector (GC/AED), to quantify and classify sulfur compounds in real-time, allowing for feed forward control of hydroprocessing units by adjusting reactor temperatures and feed rates to optimize hydrotreating severity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If hydrotreating severity is increased to remove sterically hindered sulfur compounds, then sulfur removal efficiency is improved, but catalyst life decreases and maintenance costs increase
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting hydrotreating operating parameters (temperature, pressure, space velocity) based on real-time feed composition analysis. The gas chromatograph with sulfur-specific detector enables identification of sterically hindered sulfur compounds, allowing the control system to optimize severity parameters specifically targeted at these refractory compounds rather than applying uniform high severity, thereby extending catalyst life while achieving required sulfur removal.
Solution Approach 2:
The patent replaces conventional total sulfur content-based control with a sophisticated analytical system using gas chromatography coupled with sulfur-specific detection (SCD or AED). This substitution enables molecular-level identification and quantification of individual sulfur compounds, replacing crude total sulfur measurements with precise speciation data that guides selective severity application, reducing unnecessary severe conditions that damage catalysts.
2Device complexity
If total sulfur content is used to calculate desulfurization kinetics, then calculation simplicity is improved, but accuracy in predicting ultra-low sulfur diesel production decreases
Solution Approach 1:
The patent applies segmentation by dividing the total sulfur content into individual sulfur compound components using gas chromatography. Instead of treating sulfur as a single aggregate parameter, the system separates and quantifies each sulfur-containing compound ( dibenzothiophenes, benzothiophenes, thiophenes, etc.) individually. This segmented approach enables accurate kinetic modeling for ultra-low sulfur diesel production by accounting for the different reactivities of specific sulfur compounds, particularly the sterically hindered ones that control kinetics at low sulfur levels.
3Measurement precision
If on-line gas analyzer with sulfur specific detector is implemented, then real-time sulfur compound quantification is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses an intermediary approach by implementing a gas chromatograph as the separating and detecting system, coupled with either a sulfur chemiluminescence detector (SCD) or atomic emissions detector (AED). These detectors serve as intermediaries that specifically identify sulfur-containing compounds through their unique sulfur atoms, providing real-time speciation data without requiring complex sample preparation or analysis. The DCS integration acts as another intermediary, automatically translating analytical data into control actions, reducing the operational burden despite the sophisticated hardware.
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 extends catalyst life, reduces hydrogen consumption, minimizes off-spec product, and effectively achieves ultra-low sulfur diesel production by targeting specific sterically hindered molecules rather than total sulfur content, thereby optimizing the hydroprocessing unit operations.
Implementation Method 1
the analyzer uses gas chromatography (GC)
Implementation Method 2
atomic emissions detector (AED)
Implementation Method 3
sulfur chemiluminescence detector (SCD)
Implementation Method 4
uses catalysts to generate the reaction of hydrogen to remove sulfur and sulfur-contained components from petroleum
Data Source
AI summary
This unique process is a feed forward control of hydroprocessing by on-line sulfur speciation. An on-line gas analyzer such as (GC) with a sulfur specific detector (AED) would be installed to analyze the feed to a hydrotreating unit. The analyzer would be calibrated to quantify the individual sulfur compounds or classes of sulfur compounds present in the feed. The output from the analyzer would be linked to the unit's distributed control system to automatically change temperatures and feed rates to change hydrotreating severity. This invention could bring economical benefits by increasing the life of the hydrotreating catalyst, reducing operating cost, and decreasing the potential amount of offspec product. In one embodiment, the hydrotreating is a hydrodesulphurization process.