Ammonia Injection Header Layout for Uniform Flue Gas Mixing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing reducing agent injection systems in heat recovery steam generators experience uneven ammonia concentration due to wake regions and inhibited Karman vortex formation, leading to inadequate nitrogen oxide removal efficiency.
Innovation Solution
A reducing agent injection device with header pipes and supply units positioned downstream, maintaining a distance of at least three times the header pipe's outer diameter to allow stable Karman vortex formation and uniform ammonia distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the ammonia supply pipe and header are arranged in the flue upstream of the header pipe, then the reducing agent temperature can be sufficiently increased, but a wake region occurs downstream causing uneven ammonia concentration distribution
Solution Approach 1:
The patent inverts the conventional arrangement by positioning the supply pipe downstream of the header pipe instead of upstream. This reversal eliminates the wake region problem caused by upstream supply pipe installation while still allowing sufficient heating distance, thereby resolving the contradiction between temperature increase and concentration uniformity.
Solution Approach 2:
The patent specifies a particular spatial dimension (distance greater than three times the header pipe outer diameter) to position the supply pipe downstream. This dimensional specification ensures that the supply pipe does not interfere with the Karman vortex development while maintaining adequate heating distance, thus achieving both temperature increase and uniform concentration distribution.
2Device complexity
If the ammonia supply pipe is provided downstream of the header pipe near the header pipe, then installation space is saved, but the Karman vortex development is inhibited suppressing ammonia diffusion
Solution Approach 1:
The patent specifies a minimum distance (greater than three times the header pipe outer diameter) in the downstream direction to position the supply pipe. This dimensional constraint ensures adequate space for Karman vortex development while still positioning the supply pipe downstream to save installation space compared to upstream arrangement, thus resolving the contradiction between space saving and vortex development.
3Ease of manufacture
If the supply pipe is positioned at a standard distance from the header pipe, then installation is simplified, but uneven ammonia concentration occurs due to wake regions and inhibited vortex formation
Solution Approach 1:
The patent establishes a specific dimensional relationship (distance greater than three times the header pipe outer diameter) between the supply pipe and header pipe. This quantitative specification provides clear installation guidance while ensuring proper vortex development and uniform ammonia concentration distribution, thus resolving the contradiction between installation simplicity and concentration uniformity.
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
Ensures uniform ammonia concentration in the flue gas, enhancing the efficiency of nitrogen oxide removal by promoting ammonia diffusion and reaction with catalysts.
Implementation Method 1
In the flue, a Karman vortex that has an effect of diffusing ammonia injected from the injection nozzles is generated downstream of the header pipe.
Implementation Method 2
a Karman vortex that has an effect of diffusing ammonia injected from the injection nozzles is generated downstream of the header pipe
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The object is to make the concentration of a reducing agent uniform with respect to a gas flowing through in a duct. An ammonia injection unit (20) injects, to a flue gas flowing through in a duct (3), a reducing agent having an effect of reducing nitrogen oxides contained in the flue gas. The ammonia injection unit (20) includes a plurality of injection nozzles (21) configured to inject an ammonia gas to a flue gas flowing through in the duct (3); a plurality of header pipes (22), the plurality of injection nozzles (21) being provided to each of the plurality of header pipes, and an ammonia gas flowing through inside the plurality of header pipes (22); and a header (23) provided inside the duct (3) and downstream of a gas flow in the header pipes (22) and configured to supply a reducing agent to the plurality of header pipes (22). The distance (D) from each header pipe (22) to the header (23) is a distance longer than three times of an outer diameter (d) of the header pipe (22).