Split Acid-Base AWL Reactor for Neutral-pH CO2 Sequestration
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Solution Overview
Problem
Current carbon capture and storage (CCS) methods are energy-intensive and expensive, and existing AWL processes face limitations in CO2 hydration kinetics and dissolution rates, leading to incomplete CO2 conversion to bicarbonate and acidic effluent water.
Innovation Solution
A reactor design with two chambers: a first chamber for CO2 gas adsorption and acid-enhanced conversion to bicarbonate, and a second chamber for base-facilitated conversion of unreacted aqueous CO2 to bicarbonate, using equimolar acid and base additions to maintain a neutral or near-neutral pH effluent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If acid is added to enhance CO2 hydration kinetics in AWL processes, then CO2 conversion rate is improved, but effluent water becomes acidic
Solution Approach 1:
The reactor is divided into two separate chambers: the first chamber performs acid-enhanced CO2 conversion to bicarbonate, while the second chamber neutralizes the acidic effluent. This segmentation allows each chamber to optimize its function without interfering with the other, resolving the contradiction between conversion rate and effluent pH
Solution Approach 2:
The second chamber acts as an intermediary that receives the acidic effluent from the first chamber and neutralizes it using a base. This intermediary step removes the harmful acidic effect while preserving the beneficial CO2 conversion that occurred in the first chamber
2Object-generated harmful factors
If base is added to neutralize acidic effluent, then effluent pH is improved, but net base buildup occurs
Solution Approach 1:
The system uses feedback control where the pH of the effluent from the first chamber is monitored, and base is added to the second chamber in proportion to the acid added in the first chamber. This feedback mechanism ensures that the net acid-base balance remains neutral, preventing both acidic and basic buildup while maintaining proper effluent pH
Solution Approach 2:
The system changes the parameters of acid and base addition dynamically based on the CO2 conversion rate and effluent pH requirements. By adjusting these parameters in real-time, the system maintains neutral pH effluent without creating net acid or base buildup
3Productivity
If CO2 hydration kinetics are enhanced, then CO2 sequestration efficiency is improved, but dissolution rates become limiting
Solution Approach 1:
The first chamber performs preliminary action by enhancing CO2 hydration kinetics through acid addition, converting CO2 to bicarbonate before the effluent reaches the second chamber. This preliminary conversion accelerates the overall sequestration process without being limited by the natural dissolution rate in subsequent stages
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
Efficient and scalable CO2 sequestration and storage as bicarbonate ions in water, with minimal environmental impact by maintaining a neutral pH effluent and avoiding net acid or base buildup, suitable for marine applications.
Implementation Method 1
a gas inlet for delivering a gas stream including a CO2 amount of CO2 gas to the first chamber
Implementation Method 2
a reaction medium solid
Implementation Method 3
an acid inlet for delivering an acid amount of an acid to the first chamber
Implementation Method 4
a base inlet for delivering a base amount of a base to the second chamber; wherein the base amount is equimolar to the acid amount
Data Source
AI summary
A reactor for enhanced and scalable CO2 sequestration and storage in water with neutral or near neutral pH outflow is described, along with a method of use thereof. The reactor and method are an AWL reactor and method that additionally employ an acid to enhance CO2 hydration kinetics, and, as such, the conversion of CO2 to bicarbonate ions for storage. In addition, the reactor and method employ a base, in an amount equimolar to the acid's amount, to directly capture any un-titrated aqueous CO2, and, as such, to convert even more CO2 to bicarbonate ions for robust storage, and also to neutralize the otherwise over-acidified effluent water stream being returned to the environment from the reactor.