Solid-Phase Liquid Membrane NOx Removal for Low-Temperature Flue Gas
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Solution Overview
Problem
Existing denitration technologies struggle to efficiently remove nitrogen oxides from low-temperature flue gases (<160°C), with methods like SCR and wet oxidation showing inefficiencies and high energy consumption, while alternative methods have low efficiency and equipment limitations.
Innovation Solution
A solid-phase liquid membrane method that partially oxidizes NOx to NO2 using ozone or other oxidants, then absorbs it with a porous solid material containing a liquid membrane composed of specific components, including pH regulators, liquid membrane formers, and stabilizers, achieving high denitration efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional denitration methods (SCR, SNCR, wet oxidation) are used for low-temperature flue gases, then the process can be implemented, but the denitration efficiency is low and energy consumption is high
Solution Approach 1:
The patent changes the temperature parameter to operate at low temperatures (20-160°C) rather than high temperatures, and changes the chemical mechanism from catalytic reduction to oxidation followed by absorption. This parameter change enables effective denitration at low temperatures without requiring high energy input, resolving the contradiction between denitration efficiency and energy consumption.
Solution Approach 2:
The patent replaces the catalytic reduction mechanism (requiring high temperature and catalyst) with an oxidation-absorption mechanism using ozone or other oxidants followed by absorption in a liquid membrane. This substitution eliminates the need for high temperature operation and catalyst materials, reducing energy consumption while maintaining denitration efficiency.
2Productivity
If oxidation absorption method is used to convert NO to water-soluble high-valence nitrogen oxides, then the denitration process can proceed, but the utilization ratio of alkali liquor absorbent is low and denitration efficiency is below 80%
Solution Approach 1:
The patent uses a composite liquid membrane system combining multiple components: oxidant (ozone), absorption agent (alkali liquor), and a liquid membrane forming agent (surfactant or polymer). This composite structure enhances the absorption capability and utilization ratio of the alkali liquor, improving denitration efficiency above 80% while reducing absorbent waste.
Solution Approach 2:
The liquid membrane acting as an intermediary layer between the gas phase and liquid absorbent enhances mass transfer efficiency. The liquid membrane structure facilitates better contact and absorption of nitrogen oxides by the alkali liquor, increasing the utilization ratio of the absorbent and improving overall denitration efficiency.
3Productivity
If solid base absorbent is used for absorbing nitrogen oxides at low temperature, then the method can be applied to low-concentration NOx, but the efficiency is low (10-40%) and equipment requirements are complex
Solution Approach 1:
The patent employs a liquid membrane system that utilizes fluid dynamics and mass transfer principles to achieve efficient absorption. The liquid membrane flow and gas-liquid contact mechanisms provide superior absorption efficiency (above 80%) compared to solid base absorbents, while simplifying equipment requirements through a more compact and easier-to-operate liquid-phase system.
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 over 95% removal of nitrogen oxides at low temperatures, meeting ultra-low emission standards with minimal equipment requirements and cost, suitable for various flue gas conditions.
Implementation Method 1
partially oxidizing the NOx-containing flue gas into a NO2—NO mixed flue gas by means of oxidation methods such as ozone (O3) oxidation, ClO2 oxidation, and O2 oxidation
Implementation Method 2
absorbing and removing the oxidized NOx-containing flue gas by means of an absorption bed filled with an absorption material, where an absorbent material is a porous solid material containing a liquid membrane
Data Source
AI summary
A solid-phase liquid membrane method for purifying nitrogen oxide waste gases, using ozone, ClO2 or O2 to partially oxidize NOx components in a flue gas into NO2—NO mixed flue gas, which is then passed into an absorption bed filled with an absorption material, to absorb and remove nitrogen oxides; the absorption material comprises a porous solid-phase material and an absorption liquid membrane loaded thereon, a mass ratio (solid-liquid ratio) of the porous solid phase material to the liquid membrane being 1:(0.05-10); the liquid membrane is primarily composed of three parts: a pH value regulator, a liquid membrane forming agent and a liquid membrane stabilizer, the pH value regulator comprising an organic base and an inorganic base, the liquid membrane stabilizer comprising urea, and the liquid membrane forming agent comprising water and C1-C4 lower alcohols.