SNCR Reagent Gasification in Cement Preheater
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Solution Overview
Problem
Current SNCR methods in cement production plants face inefficiencies due to direct injection of aqueous reducing agents, which react with solid particles, reduce reagent effectiveness, and result in increased costs and NOx generation, as the reagents are oxidized at high temperatures, leading to reduced denitrification performance and increased emissions.
Innovation Solution
A method involving the filtration of hot gases to separate solid particles, followed by the injection of a reagent as an aqueous solution into a reactor where it evaporates and gasifies, allowing its reintroduction into the preheater at high temperatures, thereby optimizing reagent use and preventing reagent oxidation, using ceramic filters or felt bag filters and optionally catalysts like vanadium pentoxide or titanium dioxide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aqueous reducing agents are directly injected into the preheater, then the denitrification process can be implemented, but the reagents react with solid particles reducing effectiveness and increasing costs
Solution Approach 1:
The patent extracts solid particles from the gas stream by introducing the gas-liquid mixture into a cyclone separator before the preheater. This separation removes the harmful interaction between reagent droplets and solid particles, preventing reagent binding and oxidation while maintaining denitrification performance
Solution Approach 2:
The patent performs preliminary atomization of the aqueous reagent solution into fine droplets before injection. This creates a larger surface area for faster evaporation and gasification, ensuring the reagent is in gas phase before contacting the hot gas stream, thus avoiding liquid-reagent binding with solids
2Reliability
If aqueous reducing agents are directly injected into the preheater, then the denitrification process can be implemented, but the reagents are oxidized at high temperatures generating more NOx
Solution Approach 1:
The patent performs preliminary gasification of the reagent by atomizing the aqueous solution into fine droplets that rapidly evaporate and gasify in the hot gas stream before entering the preheater. This ensures the reagent is already in gas phase, preventing liquid-reagent oxidation and subsequent NOx generation
Solution Approach 2:
The cyclone separator extracts liquid reagent droplets from the gas stream, preventing them from entering the high-temperature preheater where oxidation would occur. Only gasified reagent components proceed to the denitrification zone
3Reliability
If aqueous reducing agents are directly injected into the preheater, then the denitrification process can be implemented, but the reagent binds with solid particles reducing effectiveness
Solution Approach 1:
The cyclone separator extracts and removes solid particles from the gas stream before the reagent is injected. This prevents the binding reaction between reagent droplets and solid particles, ensuring reagent availability for denitrification
Solution Approach 2:
The patent changes the physical state of the reagent from liquid to gas phase through atomization and gasification. This parameter change prevents liquid-reagent binding with solid particles while maintaining chemical reactivity for NOx reduction
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 denitrification efficiency by minimizing reagent consumption, reducing operating costs, and preventing NOx generation, while maintaining process performance by ensuring immediate gasification and avoiding reagent binding with solid particles.
Implementation Method 1
channelling said gas flow to a filter element adapted to separate the solid particles of the gaseous stream
Implementation Method 2
atomizing the aqueous solution containing the reagent by introducing into the gas to be treated, thus obtaining the simultaneous and immediate evaporation of water
Implementation Method 3
gasification of the reagent, allowing its reintroduction into the preheater at high temperatures
Data Source
Figure 1
AI summary
The present invention relates to an apparatus and a method for the selective non- catalytic reduction (SNCR) of NOx in industrial cement production plants. In particular, the method according to the present invention provides for the atomization of an aqueous solution containing the reagent by introducing it into the gas to be treated that is at a high temperature, thus achieving the simultaneous and immediate evaporation of the water and gasification of the reagent. Thanks to this method, there is achieved improved performance of the non- catalytic reduction process of NOx while using the same reagent or, specularly, the same performance with a lesser amount of reagent being required, with consequent reduction of the costs.