Multi-stage Ammonia Decarbonization with Temperature Control
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Solution Overview
Problem
Existing ammonia-based decarbonization processes face challenges with low absorption efficiency and significant ammonia escape, which affect the overall efficiency and energy consumption in CO2 capture from industrial gases.
Innovation Solution
Implementing a multi-stage ammonia-process decarbonization method with four or more stages of absorption, where temperature profiles are controlled across stages, and ammonia addition is managed to optimize absorption efficiency and minimize ammonia escape, using a sequential arrangement of absorption vessels with temperature control and ammonia addition units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single-stage ammonia absorption process is used, then the device structure is simple, but the absorption efficiency is low and ammonia escape is serious
Solution Approach 1:
The absorption process is divided into multiple stages (first-stage, second-stage, third-stage absorbers) with different temperature controls. Each stage handles a portion of the CO2 absorption, allowing the system to achieve high overall absorption efficiency while managing ammonia escape at each individual stage. The segmentation of the absorption process into temperature-controlled zones resolves the contradiction by distributing the absorption load across multiple simpler units rather than requiring one complex single-stage system.
2Productivity
If temperature is increased to improve CO2 absorption rate, then absorption efficiency improves, but ammonia escape increases
Solution Approach 1:
Different temperature conditions are applied to different absorption stages according to their specific requirements. The first-stage absorber operates at a lower temperature (15-25°C) to minimize ammonia escape, while the second-stage absorber operates at a higher temperature (25-35°C) to maximize CO2 absorption rate. This local differentiation of temperature quality across stages resolves the contradiction by optimizing each stage's temperature for its specific function rather than using a uniform temperature throughout the system.
Solution Approach 2:
The absorption system is segmented into temperature zones where each zone is optimized for its specific purpose. The first-stage absorber uses lower temperature to control ammonia escape, while subsequent stages use higher temperatures to enhance absorption kinetics. This segmentation allows the system to simultaneously achieve low ammonia escape and high overall absorption efficiency.
3Quantity of substance
If ammonia concentration in absorption liquid is increased to enhance absorption capacity, then CO2 loading capacity improves, but ammonia escape and energy consumption increase
Solution Approach 1:
Different ammonia concentrations are applied to different absorption stages based on their specific needs. The first-stage absorber uses a lower ammonia concentration (1-3 wt%) to minimize ammonia escape and regeneration energy, while the second-stage absorber uses a higher ammonia concentration (3-5 wt%) to maximize CO2 loading capacity. This local optimization of ammonia concentration resolves the contradiction by matching concentration to functional requirements at each stage.
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 approach enhances absorption efficiency, reduces energy consumption, and effectively controls ammonia escape, improving the overall CO2 capture process.
Implementation Method 1
The chemical absorption method using ammonia water as an absorption liquid has the characteristics of strong absorption capacity
Implementation Method 2
the rich solution is heated to desorb and release CO2, where the desorption temperature is 85°C to 95°C
Data Source
Figure 1
AI summary
The invention relates to a method for multi-stage ammonia-process decarbonization, the method comprising absorbing, using ammonia as an absorbent, CO2 from a process gas in an absorber including four or more stages of absorption, the four or more stages including, sequentially arranged along the flow direction of the process gas, a first-stage absorption, a second-stage absorption, a third-stage absorption, a fourth-stage absorption, and an optional higher stage absorption; and controlling a temperature of the process gas in the second- and third-stage absorptions to be not lower than a temperature of the process gas in the first-stage absorption, and a temperature of the process gas in the fourth- and the optional higher-stage absorptions to be lower than the temperature of the process gas in the first-stage absorption.