Basic Ionic Liquids Scavenge HCl in Crude Processing
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Solution Overview
Problem
Conventional methods for neutralizing acids in refineries often lead to the formation of corrosive chloride salts, causing severe fouling and corrosion in crude distillation units due to high chloride content and inadequate control over fractionation operations, making it difficult to predict and mitigate corrosion issues.
Innovation Solution
The use of basic ionic liquids, specifically quaternary ammonium compounds, to scavenge hydrochloric acid from crude oil before it reaches the distillation tower, preventing corrosion by reacting with HCl and other chloride species, thus reducing overhead chloride levels in the crude tower system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional neutralizers (ammonia or organic amines) are used to neutralize acids, then acid neutralization is achieved, but corrosive chloride salts form causing severe fouling and corrosion
Solution Approach 1:
The patent changes the chemical parameters of the neutralizer by using ionic liquids with specific cations (quaternary ammonium, pyridinium, imidazolium, etc.) and anions (hydroxide, carbonate, bicarbonate, alkoxide, etc.) that have different properties from conventional ammonia and organic amine neutralizers. These ionic liquids neutralize HCl without forming volatile corrosive chloride salts, thereby resolving the contradiction between acid neutralization and corrosion prevention
Solution Approach 2:
The patent employs composite ionic liquid formulations combining specific cation-anion pairs that work synergistically to neutralize HCl and prevent corrosion. The ionic liquid composition acts as a composite material where the cation provides structural stability and the anion provides neutralization capability, together preventing corrosive salt formation while protecting equipment
2Productivity
If crude oil with high chloride content is processed, then production volume is maintained, but corrosion damage increases in CDU and vacuum units
Solution Approach 1:
The patent applies preliminary action by introducing ionic liquids into the crude oil stream before the crude distillation unit to pre-neutralize HCl formed by hydrolysis of magnesium and calcium chlorides. This preliminary neutralization prevents HCl from reaching the tower overhead system, allowing high chloride crude to be processed without subsequent corrosion damage
Solution Approach 2:
The ionic liquid acts as an intermediary substance between the high chloride crude oil and the distillation equipment. It intercepts and neutralizes HCl in the crude stream, preventing direct contact between corrosive HCl and equipment surfaces, thereby enabling continuous processing of high chloride crude without corrosion damage
3Reliability
If caustic injection is used for overhead chloride control, then chloride levels are reduced, but equipment complexity and operational complexity increase
Solution Approach 1:
The patent extracts the neutralization function from complex multi-component caustic injection systems and implements it through simpler ionic liquid addition. The ionic liquids are introduced in small amounts (e.g., 1-50 ppm) directly into the crude stream, eliminating the need for complex caustic injection infrastructure while achieving effective overhead chloride control
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 method effectively inhibits corrosion in the crude tower overhead system by keeping HCl levels low, avoiding the introduction of harmful alkali metals into downstream processes and allowing for higher usage of corrosion inhibitors without contributing to ash in finished products, thus reducing corrosion damage and fouling.
Implementation Method 1
contacting the crude oil with an amount of a basic ionic liquid effective to react with the hydrochloric acid to scavenge the hydrochloric acid therefrom
Data Source
AI summary
Treatment of crude oil with basic ionic liquids (ILs), results in scavenging of any hydrochloric acid (HCl) that is present to remove the HCl. The IL is a quaternary ammonium compound having the formula R4N+X− or R3N+R′N+R3, where R is independently an alkyl group, an alkylbenzyl group, a hydroxyalkyl group, or a hydroxyalkylbenzyl group, and R is straight or branched and has 1-22 carbon atoms, R′ is a straight or branched alkylene or oxyalkylene having 1 to 10 carbon atoms, and where X− is selected from the group consisting of hydroxide, carbonate, alkylcarbonate, bicarbonate or alkoxide, where the alkyl group of the alkyl-carbonate or alkoxide, if present, is straight or branched and has 1 to 8 carbon atoms. The ILs are introduced into the crude oil after the refinery desalters and before the crude distillation tower to prevent or inhibit HCl from distilling to the crude tower overhead.