Calcium Removal from Crude Oil Using Citric Acid Sequestration
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Solution Overview
Problem
Current methods for removing calcium from hydrocarbonaceous media, particularly in high calcium crudes, face challenges such as corrosion issues due to pH drop and solubility limitations of calcium citrate at elevated temperatures, leading to deposition problems in refinery equipment.
Innovation Solution
A combination of citric acid as a sequestrant to form calcium citrate, which partitions to the water phase, combined with a specifically formulated deposit control polymer to inhibit calcium-based scale formation in the water phase and on refinery surfaces, preventing deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If citric acid is used as a sequestrant to remove calcium from crude oil, then calcium extraction efficiency is improved, but calcium citrate solubility decreases at elevated temperatures causing deposition
Solution Approach 1:
The patent introduces a deposit control agent as an intermediary substance that mediates between the calcium citrate formation and deposition processes. This agent prevents direct contact between calcium citrate and equipment surfaces, thereby maintaining high extraction efficiency while preventing the solubility-related deposition issues at elevated temperatures
Solution Approach 2:
The patent modifies the chemical parameters of the system by adjusting pH levels and adding deposit control agents to change the solubility and deposition characteristics of calcium citrate. These parameter changes enable effective calcium removal while preventing scale formation on equipment surfaces
2Quantity of substance
If calcium is removed from crude oil using conventional desalting methods, then calcium content is reduced, but corrosion issues arise due to pH drop
Solution Approach 1:
The patent converts the harmful effect of pH drop into a beneficial process by using the acidic environment to enhance calcium extraction efficiency. The pH drop that would normally cause corrosion is instead harnessed to improve the sequestration of calcium by citric acid, while corrosion inhibitors are added to mitigate the harmful effects
3Quantity of substance
If calcium extraction is increased to handle high calcium crudes, then metal contamination is reduced, but deposit formation on refinery equipment increases
Solution Approach 1:
The deposit control agent serves as a mediator that allows high levels of calcium extraction to occur while preventing the direct deposition of calcium-based scales on refinery equipment. This intermediary substance enables the system to achieve both high extraction levels and reduced deposit formation
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 effectively removes calcium from high calcium crudes without causing corrosion issues and allows for higher calcium extraction levels by inhibiting calcium citrate scale formation, maintaining efficient desalter operations and reducing equipment fouling.
Implementation Method 1
The sequestrant, when added to the hydrocarbonaceous medium, results in the formation of a calcium complex that partitions to the water phase
Implementation Method 2
a calcium complex that partitions to the water phase as the hydrocarbonaceous medium is brought in contact with an aqueous wash phase
Implementation Method 3
A specifically formulated deposit control agent is brought into contact with the water phase to control calcium based deposit formation
Implementation Method 4
inhibit calcium-based scale formation in the water phase and on refinery surfaces, preventing deposition
Data Source
AI summary
Methods for reducing calcium deposition along surfaces in contact with the water phase of a resolved water/oil emulsion are disclosed. High calcium crude oil and the like are contacted with a sequestrant to form a sequestered calcium containing complex that partitions to the water phase in the resolved emulsion. A specifically formulated polymeric deposit control agent is added to the water phase to inhibit calcium deposit formation therein and along surfaces in contact with the water phase.