In Situ Coke Morphology Monitoring via AC Impedance
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Solution Overview
Problem
Current methods for monitoring coke morphology in delayed coking processes are inadequate, as they rely on inaccurate ratios and complex, time-consuming analyses, leading to inefficiencies and safety concerns due to the formation of sponge coke, which is difficult to remove and can cause hot spots.
Innovation Solution
In situ monitoring of coke morphology using AC impedance by transmitting an AC current between electrodes within the delayed coking unit, measuring impedance, and comparing it to established curves to determine whether sponge or shot coke is being formed, allowing for real-time adjustments to feed composition and operating parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If MCR to asphaltene ratio or aromatic carbon to heteroatom ratio methods are used to predict coke morphology, then some prediction capability is provided, but the measurements are inaccurate especially at intermediate values and the analysis is time-consuming
Solution Approach 1:
The patent replaces complex chemical analysis methods (MCR ratio, aromatic carbon to heteroatom ratio) with electrical impedance measurement. Instead of breaking down resid suspension and performing specialized chemical analyses, the system uses AC impedance spectroscopy to directly measure coke morphology properties in real-time, dramatically reducing analysis time while improving accuracy across the full range of morphology values.
Solution Approach 2:
The impedance measurement system utilizes the coke itself as the measuring medium. The AC impedance is measured directly across the coke in the drum, allowing the coke to provide its own morphological information through its electrical properties without requiring external chemical analysis or sample preparation.
2Adaptability or versatility
If sponge coke is formed, then certain feedstocks can be processed, but the coke is difficult to remove and causes safety concerns due to hot spots
Solution Approach 1:
The patent implements real-time feedback monitoring of coke morphology using AC impedance measurements during the coking process. By continuously tracking impedance changes, the system can detect when sponge coke is forming and provide feedback to operators to adjust process parameters (temperature, pressure, feed rate) to prevent sponge coke formation or to switch to shot coke formation conditions, ensuring easier removal and safety.
Solution Approach 2:
The system performs preliminary detection of coke morphology trends during the coking cycle using impedance measurements. This allows operators to take preliminary actions (adjusting process parameters) before sponge coke fully forms and becomes difficult to remove, preventing the problematic condition rather than reacting to it after formation.
3Productivity
If delayed coker cycle time is reduced to increase throughput, then efficiency improves, but accurate monitoring of coke morphology becomes more critical to avoid safety issues
Solution Approach 1:
The real-time impedance monitoring system provides continuous feedback on coke morphology during shortened coking cycles. This allows operators to maintain safe operation reliability even with reduced cycle times by immediately detecting when morphology changes indicate potential safety issues, enabling rapid adjustment of process parameters to prevent problems while maintaining high throughput.
Solution Approach 2:
The patent replaces slow, post-cycle morphology assessment methods with real-time electrical impedance measurement. This substitution enables continuous monitoring during accelerated coking cycles, providing the reliability needed for high-throughput operation by immediately identifying morphology changes that could lead to safety issues.
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 accurate, real-time prediction of coke morphology, allowing refineries to preferentially produce shot coke, reducing cycle times, improving efficiency, and enhancing safety by facilitating easier coke removal and preventing hot spots.
Implementation Method 1
measuring an impedance between the transmitting electrode and the receiving electrode across the coke at the frequency
Data Source
AI summary
Methods and systems for in situ monitoring of coke morphology in a delayed coking unit. At least one transmitting electrode and at least one receiving electrode are utilized to transmit AC current across coke being formed within the delayed coking unit. An impedance analyzer can be used to measure the impedance encountered between the transmitting electrode and the receiving electrode. This measure impedance is compared to an impedance curve comprising known impedance values for different coke morphologies to determine the morphology of coke being formed in the delayed coking unit.