Online Fuel Cutpoint Control Using Color Spectrum
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Solution Overview
Problem
Current hydrocarbon distillation processes in refineries face inefficiencies due to infrequent testing and measurement of product specifications, leading to suboptimal operational settings and missed profit opportunities from overlap between distillation fractions, as they can only be fine-tuned and corrected once or twice a day.
Innovation Solution
Implementing a system with vertically spaced condensation draw trays in a fractional distillation tower, where liquid hydrocarbon fractions are recycled as reflux to maintain temperature gradients and using light absorption sensors to continuously monitor and adjust the selectivity between heavier and lighter fractions, allowing for more frequent adjustments to cutpoints without significant labor or cost burdens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional gas chromatograph analysis is used to verify product specifications, then measurement accuracy is improved, but measurement time and productivity are worsened due to infrequent testing (once or twice per day)
Solution Approach 1:
The patent replaces the mechanical gas chromatograph analysis system with an optical absorption spectroscopy system. The optical system uses light absorption measurements at specific wavelengths to determine hydrocarbon composition and product specifications, enabling continuous real-time monitoring without the time-consuming mechanical separation and detection processes of gas chromatography.
Solution Approach 2:
The patent implements continuous online monitoring of product specifications using optical absorption sensors that continuously measure the composition of distillation fractions. This eliminates the intermittent batch testing approach and provides uninterrupted real-time data for process control, allowing immediate detection of specification deviations.
2Productivity
If aggressive operational settings are used to maximize throughput, then productivity is improved, but product specification compliance is worsened due to longer correction times when off-specification products are produced
Solution Approach 1:
The patent implements a closed-loop feedback control system where optical absorption measurements continuously monitor product composition and provide real-time feedback to the control system. When specification deviations are detected, the system automatically adjusts operational parameters such as reflux ratios and draw tray temperatures to correct the deviation, enabling aggressive throughput settings while maintaining specification compliance through immediate corrective action.
Solution Approach 2:
The patent uses real-time optical monitoring to detect trends and potential specification deviations before they result in off-specification product delivery. The system can predict when cutpoints may drift out of specification and take preliminary corrective actions by adjusting operational parameters, preventing specification violations before they occur rather than reacting after the fact.
3Productivity
If more frequent sampling and testing is implemented, then measurement frequency is improved, but labor and operational complexity are worsened
Solution Approach 1:
The patent implements a self-service monitoring system where optical absorption sensors are directly installed in the distillation column and automatically continuously measure the composition of fractions without requiring manual sampling, sample preparation, or laboratory analysis. The system self-calibrates and provides automatic real-time data, eliminating the labor-intensive manual sampling and testing operations while providing continuous monitoring capability.
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 enables more agile and precise control of hydrocarbon cutpoints, increasing the potential for maximizing higher-value product production by reducing the margin for error and allowing for real-time adjustments, thereby enhancing operational efficiency and profitability.
Implementation Method 1
light absorption of at least the two drained liquid hydrocarbon fractions is measured
Implementation Method 2
at least two distinct boiling distillation fractions are condensed from the predominantly vaporous stream of hydrocarbons in at least two vertically spaced apart condensation draw trays
Implementation Method 3
at least a portion of the cooled hydrocarbon fractions from each drain are recycled back into in the fractional distillation tower as reflux to cool trays in the fractional distillation device
Data Source
AI summary
The present disclosure describes a fractional distillation tower that uses color sensing technology that provides nearly real time cutpoint analysis of high value products. With this information, the cutpoints may be aggressively shifted to a financially advantageous product slate and stay aggressive throughout each day rather than wait for a once or twice daily report of what products have been made and their analyses with respect to specifications.