Refinery Feedstock Corrosivity Characterization via Electrochemical Impedance
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Solution Overview
Problem
Current methods for characterizing the corrosivity of crude oils and refinery feedstocks are inadequate, as they rely on traditional approaches like Total Acid Number (TAN) and do not effectively account for the complex corrosive properties of naphthenic acids and sulfur compounds, leading to inefficiencies in blending and corrosion management.
Innovation Solution
The method involves using electrochemical impedance spectroscopy (EIS), linear and cyclic voltammetry, and vibrational spectroscopic analysis to evaluate the corrosivity of crude oils by measuring resistance, capacitance, and molecular associations as a function of temperature, allowing for the optimization of blends to minimize corrosion impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional Total Acid Number (TAN) methods are used to characterize corrosivity, then the evaluation process is simple and quick, but the measurement precision and accuracy of corrosivity assessment is insufficient
Solution Approach 1:
The patent transitions from measuring a single parameter (TAN) to measuring multiple parameters including electrochemical impedance at different frequencies, capacitance, and resistance. This multi-parameter approach provides comprehensive characterization of corrosivity while maintaining practical feasibility through standardized measurement protocols
Solution Approach 2:
The patent replaces traditional chemical titration methods with electrochemical measurement techniques. By using electrochemical impedance spectroscopy and capacitance measurements, the system achieves more accurate corrosivity assessment without requiring complex chemical analysis equipment
2Reliability
If high naphthenic acid crudes are avoided or heavily treated, then corrosion protection is improved, but the productivity and efficiency of refinery operations decreases
Solution Approach 1:
The patent implements a feedback-based blending system where real-time electrochemical measurements of crude oil samples guide blending decisions. The system continuously monitors impedance and capacitance parameters, compares them against target specifications, and automatically adjusts blend composition to maintain optimal corrosivity levels, enabling efficient processing of high-naphthenic-acid crudes
Solution Approach 2:
The patent changes the approach from avoiding high-naphthenic-acid crudes to actively managing their corrosivity through precise blending. By measuring and controlling electrochemical parameters (impedance, capacitance, resistance), the system transforms a restrictive approach into an optimization opportunity, allowing broader feedstock utilization while maintaining corrosion protection
3Manufacturing precision
If simple blending based on TAN numbers is used, then the ease of operation is high, but the manufacturing precision of achieving desired corrosivity levels is poor
Solution Approach 1:
The patent replaces manual TAN-based blending calculations with automated electrochemical measurement and control systems. The system automatically measures impedance spectra, calculates equivalent circuit parameters, and determines optimal blend compositions, replacing complex manual procedures with streamlined electronic measurements while improving precision
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 provides a more accurate characterization of corrosivity, enabling the optimization of crude oil blends to achieve desired corrosivity levels, thereby reducing equipment corrosion and improving refinery operations.
Implementation Method 1
performing impedance measurements on the crude oil as a function of temperature to obtain a first electrochemical impedance (EI) spectrum
Implementation Method 2
comparing the first EI data with the second EI data includes comparing at least one of a resistance measurement and a capacitance measurement
Implementation Method 3
oxidation/reduction of corrosive species such as acids occurs, allowing the use of voltammetry to characterize the feedstock with respect to is its corrosion property
Implementation Method 4
detecting molecular associations and dissociation of acids in the crude oil feedstock as a function of temperature from ambient to 700° F. by vibrational spectroscopic analysis
Data Source
AI summary
A method for characterizing and optimizing refinery feedstock blends according to their corrosivity is provided. Refinery feedstocks can be characterized based on any of: dissociation of acids in the crude, breakup of naphthenic acid molecular associations, mass changes of carbon steel samples, and/or dissociation of sulfur compounds in the feedstocks. The characterization is performed as a function of temperature via any of electrical resistivity measurement, vibrational spectroscopic analysis, voltammetry, electrochemical impedance spectroscopy, crystal microbalance measurements of weight changes, and combinations thereof. The method employs models and/or hardware to optimize the usage of refinery feedstocks in the blending and valuation of the feedstocks.