Device and method for recovering carbon dioxide and nitrogen from flue gas
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Solution Overview
Problem
Existing methods for recovering carbon dioxide and nitrogen from flue gas are energy-intensive, costly, and inefficient, particularly in large-scale applications, and do not effectively utilize the cold energy released during LNG gasification.
Innovation Solution
A device and method utilizing cryogenic adsorption technology combined with LNG cold energy for CO2 and N2 recovery, including a pretreatment system, CO2 and N2 separation system, N2 purification and liquefaction system, and CO2 purification and liquefaction system, using molecular sieves or activated carbon for adsorption and cryogenic distillation to achieve high-purity products with low energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If absorption technology is used to separate CO2 from flue gas, then large treatment capacity and high purity CO2 can be obtained, but the regeneration of the absorbed solution requires a lot of heat and chemical absorbents have toxicity and corrosion
Solution Approach 1:
The patent uses cryogenic phase change separation technology, utilizing the phase transition properties of gases at low temperatures to separate CO2 from flue gas. The system cools the flue gas to condense CO2 while other gases remain in gaseous state, eliminating the need for chemical absorbents and their associated regeneration heat requirements.
Solution Approach 2:
The invention replaces the chemical absorption mechanism with a physical phase change mechanism. By substituting chemical absorbents with cryogenic condensation, the system eliminates toxicity and corrosion issues while reducing thermal energy consumption for regeneration.
2Ease of manufacture
If membrane separation technology is used, then separation can be achieved by pressure difference, but the technology is limited in large-scale applications
Solution Approach 1:
The patent employs cryogenic phase change separation which can be scaled up more effectively than membrane separation. By utilizing phase transitions at low temperatures, the system achieves both operational simplicity and large-scale applicability, overcoming the limitations of membrane technology.
3Duration of action of stationary object
If pressure swing adsorption technology is used, then adsorbents can be easily regenerated with long service life, but the cost and energy consumption are high for low-concentration carbon dioxide flue gas
Solution Approach 1:
The invention replaces adsorption-based separation with phase change-based separation. By cooling the flue gas to cryogenic temperatures, CO2 condenses while other gases remain gaseous, enabling easy separation without requiring adsorbent regeneration and reducing energy consumption for low-concentration CO2 streams.
4Temperature
If conventional electric driven refrigeration is used for cold energy production, then cooling can be achieved, but the recovery cost is high
Solution Approach 1:
The patent converts the waste heat from LNG gasification, which would otherwise be lost, into useful cold energy for driving the CO2 separation process. By utilizing this waste thermal energy in reverse heat exchange, the system achieves cryogenic cooling without high energy costs associated with conventional electric refrigeration.
Solution Approach 2:
The system uses the waste heat from LNG gasification to provide the cooling needed for CO2 separation. The waste thermal energy essentially serves the cooling function itself, creating a self-sustaining process that reduces external energy requirements and recovery costs.
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
The method achieves high-purity CO2 and N2 recovery with low energy consumption by leveraging LNG cold energy, reducing the need for external electric refrigeration and optimizing energy utilization through gradient cooling, thereby lowering costs and environmental impact.
Implementation Method 1
A device and method utilizing cryogenic adsorption technology combined with cold energy from LNG gasification
Implementation Method 2
a cryogenic adsorption device, which are used for further cooling and adsorbing the pretreated flue gas to separate CO2 and N2
Implementation Method 3
a N2 distillation and liquefaction device consisting of a raw material compressor, a heat exchanger, a cooler, a gas-liquid separator, and a distillation system
Implementation Method 4
which are used for further purifying and liquefying nitrogen-containing gas obtained from the CO2 and N2 separation system
Data Source
AI summary
A device for recovering carbon dioxide and nitrogen from flue gas includes a pretreatment system, a CO2 and N2 separation system, a N2 purification and liquefaction system, and a CO2 purification and liquefaction system. The pretreatment system includes a high-temperature NG cooler, a gas-liquid separator, a booster fan, and a dryer; the CO2 and N2 separation system includes a low-temperature LNG cooler and a cryogenic adsorption device; the N2 purification and liquefaction system includes a set of N2 distillation and liquefaction device consisting of a compressor, a cooler, a heat exchanger, a gas-liquid separator, and a distillation tower; and the CO2 purification and liquefaction system includes a set of CO2 distillation and liquefaction device consisting of a compressor, a cooler, a condenser, an evaporator, a liquefier, and a purification tower, which are used for further purifying and liquefying desorbed gas obtained from the CO2 and N2 separation system.