Chlorination-Assisted Coagulation for Produced Water Treatment
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Solution Overview
Problem
Conventional water treatment processes for petroleum production, such as coagulation and electrocoagulation, are costly and pose safety risks due to the need for large quantities of oxidants and sacrificial electrodes, and can lead to flow restrictions in subterranean formations when sulfate ions are introduced, while also requiring oxygen which is hazardous in explosive environments.
Innovation Solution
The chlorination-assisted coagulation process utilizes anaerobic conditions and the natural chloride and iron ions in produced water to convert chloride into hypochlorite or hypochlorous acid, oxidizing iron to form insoluble complexes with contaminants, reducing the need for external chemicals and avoiding sulfate formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional coagulants (metal sulfates) are used to treat produced water, then organic and inorganic contaminants are removed, but sulfate ions remain in treated water causing flow restrictions when reinjected into subterranean formations
Solution Approach 1:
The patent changes the chemical composition parameters of the coagulant from metal sulfates to metal chlorides. This parameter change ensures that chloride ions (which are naturally present in produced water) are used instead of introducing foreign sulfate ions, thereby maintaining contaminant removal effectiveness while preventing flow restrictions in the formation.
Solution Approach 2:
The patent converts the potentially harmful chloride ions present in produced water into a beneficial component by using them as the source of chlorine for coagulation. Instead of viewing chloride as a contaminant to be removed, the process utilizes it to generate hypochlorous acid and hypochlorite ions that assist in coagulating contaminants, while avoiding the introduction of harmful sulfate ions.
2Reliability
If electrocoagulation processes are used with sacrificial electrodes, then contaminants are coagulated, but large quantities of sacrificial electrodes are required increasing cost and operational complexity
Solution Approach 1:
The patent implements a self-service mechanism where chloride ions naturally present in the produced water serve as the source of chlorine for coagulation. The system uses the water's own constituents (chloride ions) to generate the necessary coagulating agents (hypochlorous acid and hypochlorite ions), eliminating the need for external chemical additions and reducing dependence on sacrificial electrodes.
Solution Approach 2:
The patent introduces hypochlorous acid and hypochlorite ions as intermediary substances that mediate between the chloride ions present in produced water and the coagulation process. These intermediaries are generated in-situ through electrochemical reactions and facilitate contaminant removal without requiring large quantities of sacrificial electrodes or external chemical additives.
3Ease of manufacture
If oxygen or oxygen-producing compounds are introduced for electrocoagulation, then electrode oxidation is facilitated, but fire and explosion hazards increase in hydrocarbon processing environments
Solution Approach 1:
The patent creates an inert environment by conducting electrocoagulation in the absence of molecular oxygen. Instead of using oxygen to oxidize chloride ions, the process relies on direct electrochemical oxidation at the anode and the oxidation capacity of generated hypochlorous acid and hypochlorite ions. This eliminates fire and explosion hazards while maintaining electrode oxidation efficiency.
Solution Approach 2:
The patent replaces the chemical mechanism of oxygen-based oxidation with an electrochemical mechanism. Instead of introducing oxygen gas or oxygen-producing compounds to facilitate electrode oxidation, the system uses electrical energy to directly oxidize chloride ions and generate hypochlorous acid and hypochlorite ions, which then oxidize contaminants and regenerate electrodes without requiring molecular oxygen.
4Reliability
If conventional electrocoagulation is operated under aerobic conditions, then hydrogen formation at cathode is prevented, but substantial amounts of oxygen are consumed increasing material costs
Solution Approach 1:
The patent implements self-service by using the chloride ions naturally present in produced water as the oxygen source for oxidation reactions. The system generates hypochlorous acid and hypochlorite ions from chloride ions through electrochemical reactions, eliminating the need for external oxygen supply while maintaining effective contaminant removal and hydrogen formation control.
Solution Approach 2:
The patent changes the oxidation mechanism from oxygen-based to chloride-based oxidation. By operating under anaerobic conditions and utilizing chloride ions as the oxidizing agent, the process eliminates oxygen consumption while maintaining hydroxyl radical generation and contaminant oxidation effectiveness. This parameter change transforms the oxidation pathway from aerobic to anaerobic electrochemical oxidation.
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 process effectively removes organic and inorganic contaminants from produced water, preventing flow restrictions and safety hazards, while being more cost-effective and safer to operate in hydrocarbon processing facilities.
Implementation Method 1
converting at least a portion of chloride ions in the produced water to hypochlorite or hypochlorous acid by passing an electric current through at least a portion of the produced water under anaerobic conditions
Implementation Method 2
reacting at least a portion of the iron (II) compounds of the produced water with the hypochlorite or hypochlorous acid to produce iron (III) ions, and coagulating the one or more organic compounds with the iron (III) ions
Implementation Method 3
a coagulant, as iron (III) sulfate or aluminum (III) sulfate, is added to the water to coagulate the organic and inorganic contaminants into insoluble solids that can be filtered or separated from the water
Data Source
AI summary
Chlorination-assisted coagulation processes and systems are disclosed for removing organic and inorganic contaminants from aqueous compositions and streams such as produced water generated by petroleum production operations. The chlorination-assisted coagulation process includes converting at least a portion of chloride ions in the aqueous composition to hypochlorite ions or hypochlorous acid by passing an electric current through at least a portion of the aqueous composition under anaerobic conditions, the aqueous composition including the chloride ions, iron (II) compounds, and one or more organic compounds. The chlorination-assisted coagulation process further includes reacting at least a portion of the iron (II) compounds of the aqueous composition with the hypochlorite or hypochlorous acid to produce iron (III) ions, and coagulating the one or more organic compounds with the iron (III) ions to produce a plurality of insoluble solid particles in a treated aqueous composition.