Concentric Tube Urea Injection Lance for Boiler Protection
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Solution Overview
Problem
Existing SNCR technologies have large diameter injection lances that pose a risk of damaging boilers and require complex cooling systems, necessitating the development of smaller diameter, efficiently cooled lances that do not harm boilers.
Innovation Solution
The design comprises an inner tube, central tube, and outer tube with decreasing diameters, featuring an atomization nozzle, decomposition zone, and injection opening, where the inner tube is cooled by atomization gas and the outer tube is used for injecting a reducing agent, with a decomposition zone between the nozzle and opening, allowing for efficient decomposition of reducing agents without damaging boilers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If large diameter injection lances are used to reach the central area of the boiler, then the reducing agent can be effectively injected, but the risk of damaging the boiler increases and the cooling system becomes more complex
Solution Approach 1:
The injection lance is segmented into three concentric tubes (inner tube, central tube, outer tube) with different functions. The inner tube has a smaller diameter than the central tube, and the central tube has a smaller diameter than the outer tube. This segmentation allows each tube to be optimized for its specific function while collectively achieving effective reducing agent injection without requiring a large overall diameter that would damage the boiler.
Solution Approach 2:
The injection lance employs a nested tube structure where the inner tube is disposed within the central tube, and the central tube is disposed within the outer tube. This nesting arrangement allows multiple functional zones to be integrated within a compact outer diameter, enabling effective reducing agent injection while minimizing the risk of boiler damage.
2Productivity
If large diameter injection lances are used, then reducing agent injection is effective, but complex cooling systems are required
Solution Approach 1:
The cooling function is segmented and integrated into the existing three-tube structure. The inner tube is cooled by atomization gas flowing between the inner tube and central tube, while the outer tube is cooled by cooling gas flowing between the central tube and outer tube. This segmentation of cooling functions into the existing structural elements eliminates the need for separate complex cooling systems.
3Object-affected harmful factors
If smaller diameter injection lances are used, then boiler damage risk is reduced, but cooling efficiency becomes more challenging
Solution Approach 1:
The nested three-tube structure provides multiple concentric cooling zones. The inner tube benefits from cooling by atomization gas in the annular space between it and the central tube. The outer tube benefits from cooling by cooling gas in the annular space between it and the central tube. This nesting arrangement maximizes cooling efficiency within a compact diameter, reducing boiler damage risk while maintaining adequate cooling.
Solution Approach 2:
Different cooling approaches are applied to different parts of the injection lance based on their specific thermal requirements. The inner tube uses atomization gas for cooling, while the outer tube uses cooling gas. This localized cooling strategy optimizes cooling efficiency for each component within the smaller diameter structure.
4Temperature
If the inner tube is cooled by atomization gas and the outer tube by cooling gas, then cooling efficiency is improved, but the structural complexity increases
Solution Approach 1:
The three-tube structure serves multiple functions simultaneously. The annular spaces between the tubes serve both as flow passages for atomization gas and cooling gas, and as cooling channels. This multi-functionality achieves high cooling efficiency for both inner and outer tubes while avoiding additional complex cooling components.
Solution Approach 2:
The structural elements and cooling functions are merged into a single integrated three-tube assembly. The cooling channels are formed by the annular spaces between the nested tubes, eliminating the need for separate cooling system components. This merging achieves efficient cooling while minimizing structural 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
This configuration allows for safe and efficient injection of reducing agents into flue gas streams, avoiding boiler damage and eliminating the need for costly cooling systems, while ensuring complete decomposition of reducing agents within the specified temperature range.
Implementation Method 1
a liquid exiting the liquid outlet of the inner tube is atomized by the atomization nozzle via an atomization gas flowing between the inner tube and the central tube
Implementation Method 2
the decomposition zone and the injection opening of the outer tube are in fluid connection with the volume between the central tube and the outer tube for introducing a cooling gas in the decomposition zone
Implementation Method 3
the decomposition zone is adapted to decompose a reducing agent precursor
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
The present application relates to an injection lance comprising an inner tube, a central tube, and an outer tube, wherein the inner tube has a smaller diameter than the central tube, and the central tube has a smaller diameter than the outer tube, the inner tube is disposed within the central tube, wherein the central tube is disposed within the outer tube, the central tube ends in an atomization nozzle, the outer tube ends in an injection opening, and wherein the injection lance comprises a decomposition zone between the atomization nozzle and the injection opening, the decomposition zone being adapted to decompose a reducing agent precursor. The present application further relates to a method for injecting a reducing agent in a flue gas treatment system and a method for treating a flue gas by means a flue gas treatment system.