NOx Removal Control System Using Temperature Distribution Feedback
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Solution Overview
Problem
Existing NOx removal devices face inefficiencies due to uneven concentration distribution of the reducing agent, even when the spraying level is constant, leading to inferior performance.
Innovation Solution
A control system that measures temperature distribution using optical fibers to determine the flow rate and concentration distribution of the reagent, allowing for precise adjustment of the reagent introduction to achieve a desired concentration distribution, thereby enhancing NOx removal efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the spraying level of the reducing agent is kept constant, then the operation is simple, but the concentration distribution does not reach the desired distribution when nozzles are blocked
Solution Approach 1:
The patent implements a feedback control mechanism where the actual concentration distribution of the reducing agent is measured and compared with the desired distribution. Based on this comparison, the control system automatically adjusts the spraying levels of individual nozzles to compensate for blockages or deviations, ensuring reliable concentration distribution while maintaining operational simplicity through automated correction.
Solution Approach 2:
The system transitions from static constant spraying levels to dynamic adjustable spraying levels. Each nozzle's spraying level can be independently modified based on real-time concentration measurements, allowing the system to adapt to changing conditions such as nozzle blockages while maintaining optimal performance.
2Productivity
If the concentration distribution is not uniform, then the NOx removal efficiency decreases, but increasing the spraying level to compensate increases reagent consumption
Solution Approach 1:
The patent applies local quality control by measuring and adjusting the concentration distribution at different spatial locations within the exhaust gas flow. Instead of uniformly increasing spraying levels across all nozzles, the system identifies specific regions with insufficient reducing agent concentration and targets only those areas for adjustment, thereby improving NOx removal efficiency without proportionally increasing overall reagent consumption.
Solution Approach 2:
The system dynamically changes the spraying parameters (flow rates, timing) of individual nozzles based on measured concentration distributions. By precisely controlling where and how much reducing agent is injected, the system optimizes the balance between achieving uniform concentration distribution for high NOx removal efficiency and minimizing total reagent consumption.
3Device complexity
If traditional flow rate control methods are used, then the control system is simple, but the concentration distribution cannot be accurately controlled when nozzles are blocked
Solution Approach 1:
The patent introduces temperature measurement as an intermediary parameter to infer reducing agent concentration distribution. Instead of directly measuring complex concentration fields, the system uses temperature measurements (which are easier to obtain and more accurate) as a proxy indicator. The temperature distribution correlates with the concentration distribution of the reducing agent, enabling precise indirect measurement without significantly increasing system complexity.
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 ensures a uniform and desired concentration distribution of the reagent, improving NOx removal efficiency, preventing reagent wastage, and maintaining the reliability of the NOx removal device and boiler plant operations.
Implementation Method 1
a reducing agent is sprayed into exhaust gas in a smoke path, and nitrogen oxides contained in the exhaust gas are removed in the form of nitrogen and water by means of chemical reactions with a catalyst. The reducing agent sprayed into the exhaust gas evaporates, and the temperature of the exhaust gas is reduced at this time due to the latent heat of evaporation
Implementation Method 2
the temperature of the exhaust gas is reduced at this time due to the latent heat of evaporation
Implementation Method 3
measuring the temperature distribution of the exhaust gas into which the reducing agent is sprayed optically
Data Source
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AI summary
A control system (20) of a NOx removal device is provided with reagent introducing means (15) for introducing a reagent into a fluid, a temperature measuring device (21) that measures a temperature distribution of the fluid, a reagent-concentration calculating portion (23) that calculates a concentration distribution of the reagent introduced into the fluid with the temperature distribution determined at the temperature measuring device (21), a reagent-flow-rate determining portion (24) that determines a flow rate of the reagent that the reagent introducing means (15) introduces in accordance with the concentration distribution calculated at the reagent-concentration calculating portion (23), and a reagent-introducing-means control portion (25) that controls the reagent introducing means (15) so as to introduce the reagent into the fluid at the flow rate determined at the reagent-flow-rate determining portion (24).