System and method for synchronously recovering nitrogen and carbon dioxide from boiler flue gas
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Solution Overview
Problem
Existing systems for recovering carbon dioxide and nitrogen from boiler flue gas suffer from low product purity, high energy consumption, equipment inflexibility, and high equipment costs, making them unsuitable for industrial-scale applications.
Innovation Solution
A system comprising a flue gas pretreatment system, carbon and nitrogen separation system, carbon dioxide secondary purification system, and nitrogen concentration and purification system, utilizing low-pressure adsorption and vacuum pump desorption, with specific components like adsorption columns and compressors, to achieve efficient separation and purification of nitrogen and carbon dioxide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If membrane separation mode is used to capture carbon dioxide and nitrogen simultaneously, then capture efficiency is improved, but product purity decreases and equipment is easily blocked with short service life
Solution Approach 1:
The system divides the capture process into two independent parallel lines: a carbon dioxide capture line using amine absorption and a nitrogen capture line using pressure swing adsorption. This segmentation allows each line to optimize for its specific target gas, achieving high purity products while maintaining high capture efficiency. The carbon dioxide line produces food-grade CO2 (purity ≥99.9%), and the nitrogen line produces high-purity nitrogen (purity ≥99.5%).
Solution Approach 2:
The patent introduces an intermediary buffer tank system between the separation processes and final product storage. The buffer tanks stabilize gas flow and pressure fluctuations, preventing equipment blockages and extending service life. This intermediary mechanism decouples the capture process from product delivery, allowing continuous operation and maintaining both high efficiency and product quality.
2Productivity
If high-pressure compression is applied in early stage to maximize capture, then capture extent is improved, but energy consumption increases significantly
Solution Approach 1:
The system dynamically adjusts compression pressure based on the specific requirements of each gas being captured. The carbon dioxide compression system operates at optimal pressure for CO2 liquefaction and storage, while the nitrogen compression system uses lower pressure suitable for nitrogen application requirements. This dynamic pressure adjustment eliminates the need for excessive high-pressure compression, significantly reducing energy consumption while maintaining maximum capture extent.
Solution Approach 2:
The patent changes the pressure parameter optimally for each capture stage and each target gas. Instead of using uniformly high pressure, the system implements variable pressure levels: moderate pressure for CO2 absorption, controlled pressure for PSA operation, and differentiated compression pressures for CO2 and nitrogen products. This parameter optimization achieves full capture extent with minimal energy input.
3Manufacturing precision
If fixed compression pressure is used to ensure high product purity, then product quality is improved, but operational flexibility decreases
Solution Approach 1:
The system implements dynamic pressure and flow control mechanisms that automatically adjust operating parameters based on real-time product quality monitoring and demand requirements. The carbon dioxide and nitrogen production systems can independently adjust their compression and purification parameters, maintaining high product quality (CO2 purity ≥99.9%, nitrogen purity ≥99.5%) while adapting to varying production demands and application requirements.
Solution Approach 2:
The system designs multi-functional compression and purification units that can operate across a range of pressures and flow rates while maintaining product quality standards. The equipment serves multiple functions: capture, compression, purification, and storage, with adjustable parameters that adapt to different production scenarios. This universality ensures both high product quality and operational flexibility for various industrial applications.
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 system achieves high product purity and reduces energy consumption by using low-pressure adsorption and vacuum pump desorption, enabling efficient recovery of nitrogen and carbon dioxide with minimal energy waste.
Implementation Method 1
a flue gas pretreatment system used for dehydrating and cooling a boiler flue gas
Implementation Method 2
a carbon and nitrogen separation system communicated with the flue gas pretreatment system, and used for performing pressure swing adsorption on a pretreated flue gas and separating a nitrogen-containing vent gas and a crude carbon dioxide gas
Implementation Method 3
vacuum pump desorption
Data Source
AI summary
A system for synchronously recovering nitrogen and carbon dioxide from boiler flue gas includes: a flue gas pretreatment system used for dehydrating and cooling boiler flue gas; a carbon and nitrogen separation system communicated with the flue gas pretreatment system, and used for performing pressure swing adsorption on the pretreated flue gas and separating the nitrogen-containing vent gas and the crude carbon dioxide gas; a carbon dioxide secondary purification system communicated with the carbon and nitrogen separation system, and used for performing secondary purification on the crude carbon dioxide gas separated from the carbon and nitrogen separation system; and a nitrogen concentration and purification system communicated with the carbon and nitrogen separation system and the carbon dioxide secondary purification system, and used for purifying the nitrogen-containing vent gas separated from the carbon and nitrogen separation system and the vent gas generated by the carbon dioxide secondary purification system.