CO2 Separation Process Using Waste-Stream Expansion Recovery
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Solution Overview
Problem
Current methods for carbon dioxide recovery from oxy-combustion power plants are inefficient and costly due to high power consumption and capital expenditures, particularly in the use of adiabatic compressors and hot gas expanders, which result in reduced carbon dioxide concentration and increased energy costs.
Innovation Solution
A carbon dioxide separation process that involves warming and expanding a waste stream from the flue gas, using two separators and two expanders to recover energy efficiently, thereby reducing power consumption and improving carbon dioxide concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If adiabatic compressors and hot gas expanders are used in the carbon dioxide recovery process, then the power consumption is reduced, but the carbon dioxide concentration in the flue gas decreases and operational costs increase
Solution Approach 1:
The patent changes the operating parameters of the compression and expansion processes by using isothermal compressors instead of adiabatic compressors, and cold gas expanders instead of hot gas expanders. This parameter change optimizes both power consumption and carbon dioxide concentration, resolving the technical contradiction between energy efficiency and gas concentration maintenance.
Solution Approach 2:
The patent uses a cold gas expander that replicates the expansion function of the hot gas expander but operates with cold gas instead. This copying approach allows the system to recover power efficiently while maintaining the carbon dioxide concentration, as the cold gas expander avoids the dilution effect associated with hot gas expansion.
2Quantity of substance
If high purity oxygen is used in the oxy-combustion process, then the carbon dioxide concentration in the flue gas increases, but the capital expenditure and power input increase
Solution Approach 1:
The patent implements a self-service mechanism where the cold gas expander uses the cold gas from the carbon dioxide separation process itself to drive the expansion. This eliminates the need for external high purity oxygen input, as the system uses its own waste cold gas to maintain the oxy-combustion process, thereby reducing both capital expenditure and power input while maintaining high carbon dioxide concentration.
Solution Approach 2:
The patent recovers the cold gas that would otherwise be discarded from the carbon dioxide separation process and uses it to drive the cold gas expander. This recovery approach generates power to offset the power input required for the oxy-combustion process, resolving the contradiction between achieving high carbon dioxide concentration and minimizing power input.
3Manufacturing precision
If the flue gas is cooled and moisture is removed, then the carbon dioxide purification is improved, but the power consumption and capital expenditures increase
Solution Approach 1:
The patent merges the cooling and moisture removal functions into a single integrated process step within the carbon dioxide separation apparatus. By combining these functions, the system achieves high carbon dioxide purification without requiring separate complex devices for each function, thereby reducing device complexity while maintaining purification precision.
Solution Approach 2:
The patent uses an intermediary cold gas stream that facilitates both cooling and moisture removal simultaneously. This cold gas acts as a mediator that transfers heat and removes moisture in a single process, simplifying the overall system design and reducing device complexity while achieving the desired purification level.
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 enhances the efficiency and cost-effectiveness of carbon dioxide recovery by minimizing power input and capital expenditures, achieving higher carbon dioxide concentrations and reducing operational costs.
Implementation Method 1
warming at least a portion of a waste stream, that has been separated from a flue gas stream. This waste stream is then expanded, which results in a cool vapor exhaust stream
Data Source
AI summary
An improved process for the separation of carbon dioxide from the flue gas of an oxy-combustion power plant is provided. The flue gas is compressed, cleaned, cooled and dried. This clean, compressed dry flue gas is then further cooled, partially condensed and separated into liquid and vapor streams. The liquid streams, which contain a high concentration of carbon dioxide, are vaporized, compressed and exported to an end user. The vapor streams are heated and expanded, in order to extract useable energy. At least two expanders are used to extract this energy, with an intermediate warming step.