US-12623934-B1 - Electrochemcial treatment of saline wasterwater with captured CO2 to produce saline free water

US12623934B1US 12623934 B1US12623934 B1US 12623934B1US-12623934-B1

Abstract

Methods of separating water, salt, CO 2 , and crude oil from wastewater, the methods comprising: providing gas/oil separation system that produces a waste saline water stream and a CO 2 stream; providing an electrochemical cell having an anode, a cathode, and three electrodialytic compartments; feeding a fresh water stream to the anode to produce H + and O 2 ; feeding the waste CO 2 stream and O 2 to the cathode to produce bicarbonate (HCO 3 —) and hydroxide ions (OH − ); feeding the waste saline water stream to a center electrodialytic compartment; wherein the sodium Na + from the waste saline water stream reacts with the bicarbonate to form NaHCO 3 and the chloride (Cl − ) from the waste saline water stream reacts with the H + to produce hydrochloric acid; and producing salt and desalinated water.

Inventors

Norah Waled Aljuryyed
Abeer Ateeq Alarawi

Assignees

SAUDI ARABIAN OIL COMPANY

Dates

Publication Date: 20260512
Application Date: 20250116

Claims (14)

1 . A method of separating water, salt, CO 2 , and crude oil from wastewater, the method comprising: producing a salt water stream and a gas stream from a gas/oil separation system; feeding the gas stream into a low pressure gas treatment system to produce a treated CO 2 stream; feeding the salt water stream into a water-oil separator to produce a waste saline water stream comprising sodium (Na + ) and chloride (Cl − ); combining the waste saline water stream and the treated CO 2 stream to produce a water/CO 2 stream; feeding the water/CO 2 stream to an electrochemical cell having an anode, a cathode, and three electrodialytic compartments; feeding a fresh water stream to the anode to produce H + and O 2 ; feeding the treated CO 2 stream and O 2 to the cathode to produce bicarbonate (HCO 3 —) and hydroxide ions (OH − ); feeding the waste saline water stream to a center electrodialytic compartment; wherein the sodium (Na + ) from the waste saline water stream reacts with the bicarbonate to form NaHCO 3 and the chloride (Cl − ) from the waste saline water stream reacts with the H + to produce hydrochloric acid; and producing salt and desalinated water.
2 . The method of claim 1 , wherein the cathode comprises a Pt/C catalyst.
3 . The method of claim 1 , wherein the anode comprises titanium.
4 . The method of claim 1 , wherein the gas/oil separation system comprises a degassing tank, dehydrator, and a crude stabilizer.
5 . The method of claim 4 , wherein the gas/oil separation system produces refined crude oil.
6 . The method of claim 1 , wherein the method further comprises producing dry salt.
7 . The method of claim 1 , wherein the waste saline water stream does not comprise hydrogen disulfide.
8 . The method of claim 1 , wherein the electrochemical cell comprises ion exchange membranes.
9 . A method of separating water, salt, CO 2 , and crude oil from wastewater comprising: separating a wastewater feed from an oil refinery into a gas stream comprising CO 2 and a salt water stream; treating the gas stream to produce a treated CO 2 stream; separating oil from the salt water stream to produce a saline water stream; combining the saline water stream with the treated CO 2 stream to produce a water/CO 2 stream; and feeding the water/CO 2 stream to an electrochemical cell to produce salt and desalinated water.
10 . The method of claim 9 , further comprising: separating the wastewater feed into a crude oil stream by a low pressure trap; and feeding the crude oil stream to an oil refinery comprising a degassing tank, a dehydrator, and a crude stabilizer.
11 . The method of claim 10 , wherein the low pressure trap produces a first salt water stream, the degassing tank produces a second salt water stream, and the dehydrator produces a third salt water stream.
12 . The method of claim 11 , wherein the first salt water stream, the second salt water stream, and the third salt water stream combine to form the salt water stream.
13 . The method of claim 10 , further comprising, by electrostatic coalescence, separating an emulsion of salt water and wet crude oil in the dehydrator to produce a dehydrator salt water stream and a dehydrator oil stream.
14 . The method of claim 13 , further comprising combining the dehydrator salt water stream with the salt water stream before entering an oil/water separator to produce the saline water stream.

Description

FIELD OF THE DISCLOSURE The present disclosure relates generally to methods to produce saline free water using a semi closed-loop system at a produced gas treatment facility, and, more particularly, to utilizing CO2 streams and wastewater from the gas/chemical processing plant to produce saline free water. BACKGROUND OF THE DISCLOSURE Water has been an essential substance in daily life for the world's social growth in industrial agricultural application. Its supply should be sustainable and cost-effective to maintain the usable water in the world which is only 3% in comparison to the whole water resources worldwide. Thus, the treatment and utilization of the water were strongly required to the resolve such global crisis. The global water shortage has resulted from population growth and industrialization and is a key challenge that humanity faces in the 21st century. Continuous progress on wastewater treatment technologies has been made to improve water reuse and reduce water shortages. Among them, the development of osmosis desalination, including the recovery of fresh water from an induction solution used for forward osmosis using power plant warm water and recycling of power plant exhaust gas. In the gas-oil separation plant, the pressure is often reduced in several stages to allow the controlled separation of volatile components. The idea is to achieve maximum liquid recovery and stabilized oil and gas, and to separate water. A large pressure reduction in a single separator will cause flash vaporization, leading to instability and safety hazards. SUMMARY OF THE DISCLOSURE Various details of the present disclosure are hereinafter summarized to provide a basic understanding. This summary is not an exhaustive overview of the disclosure and is neither intended to identify certain elements of the disclosure, nor to delineate the scope thereof. Rather, the primary purpose of this summary is to present some concepts of the disclosure in a simplified form prior to the more detailed description that is presented hereinafter. According to embodiments consistent with the present disclosure, methods of separating water, salt, CO2, and crude oil from wastewater include providing gas/oil separation system that produces a waste saline water stream and a CO2 stream. Providing an electrochemical cell having an anode, a cathode, and three electrodialytic compartments; feeding a fresh water stream to the anode to produce H+ and O2; feeding the waste CO2 stream and O2 to the cathode to produce bicarbonate (HCO3−) and hydroxide (OH−); feeding the waste saline water stream to the center electrodialytic compartment; wherein the sodium (Na+) from the waste saline water stream reacts with the bicarbonate to form NaHCO3 and the chloride (Cl−) from the waste saline water stream reacts with the H+ to produce hydrochloric acid; and producing salt and desalinated water. When an electrochemical cell is utilizing an anion exchange membrane to electrochemically separate carbon dioxide and oxygen from a feeding gaseous streams to the cell, the separation may occur according to the chemical reactions shown below: OH−+CO2↔HCO3− OH−+HCO3—↔CO32−+H2O M++HCO3—↔MHCO3, (M+=Na+) 2M++CO32−↔M2CO3 (M+=Na+) The anions in the cathode compartment then migrate through the cell and react with the protons formed in the oxidation process at the anode. 2H++CO32−↔H2O+CO2 H++HCO3−↔H2O+CO2 H++OH−↔H2O Other embodiments include systems to separate water, salt, and CO2 from wastewater. The system includes a wastewater feed comprising salt water and hydrocarbons, connected to a low pressure trap, wherein the low pressure trap separates the wastewater into three streams: a gas stream, a crude oil stream, and a salt water stream; and a water/CO2 stream connected to an electrochemical cell; wherein: the gas steam is fed into a low pressure gas treatment system to produce a treated CO2 stream; the salt water is fed into an oil/water separator to produce a saline water stream; and the water/CO2 stream combines the treated CO2 stream and the saline water steam, wherein the water/CO2 stream is fed into the electrochemical cell to produce water free of saline and salt. Any combinations of the various embodiments and implementations disclosed herein can be used in a further embodiment, consistent with the disclosure. These and other aspects and features can be appreciated from the following description of certain embodiments presented herein in accordance with the disclosure and the accompanying drawings and claims. BRIEF DESCRIPTION OF THE DRAWINGS The FIGURE is a schematic diagram of the system to separate water, salt, and CO2 from wastewater. DETAILED DESCRIPTION Embodiments of the present disclosure will now be described in detail with reference to the accompanying Figures. Like elements in the various figures may be denoted by like reference numerals for consistency. Further, in the following detailed description of embodiments of the present disclosure, nume