Marine SCR Reaction Device with Nested Cylinder Backflow
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Solution Overview
Problem
Traditional SCR reactors for marine diesel engines have a direct-flow structure that results in a large size and insufficient mixing homogeneity, making them difficult to integrate in limited spaces and reducing catalytic reaction efficiency.
Innovation Solution
A compact marine SCR system reaction device with a conveying unit, reaction chamber, catalyst modules, and an air homogenization chamber that allows flue gas to flow back and mix with the reducing agent, reducing the device's size and improving catalytic reaction efficiency through a deflector with a backflow ring, guide ring, air homogenization plates, and rings for enhanced gas mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a direct-flow mixing pipeline structure is used to connect the urea nozzle to the catalytic reactor, then the structure is simple, but the overall length and size become long and large, making it difficult to arrange in limited cabin space
Solution Approach 1:
The mixing pipeline is disposed inside the catalytic reactor, with the mixing pipeline inner cylinder nested within the catalytic reactor outer cylinder. This nested arrangement allows the mixing function to be integrated within the reactor structure, eliminating the need for a separate external mixing pipeline and thereby reducing the overall length and size of the SCR system while maintaining the direct-flow mixing capability
2Stability of the object's composition
If the length of the mixing pipeline is increased to improve mixing homogeneity, then the mixing homogeneity improves, but the size of the direct-flow reactor increases again
Solution Approach 1:
Instead of increasing the length of the mixing pipeline in one dimension, the patent utilizes the radial space between the inner and outer cylinders of the catalytic reactor. The mixing pipeline is arranged concentrically within the reactor, allowing sufficient mixing length to be achieved by optimizing the radial clearance and axial height rather than extending the pipeline length externally, thus improving mixing homogeneity without increasing the overall reactor volume
3Volume of moving object
If the SCR system is made more compact to reduce size, then the integration improves, but the mixing of flue gas and reducing agent may become insufficient
Solution Approach 1:
The spray nozzle injects the reducing agent (urea solution) into the mixing pipeline ahead of time, allowing preliminary mixing to occur as the fluid travels through the mixing pipeline inner cylinder. This preliminary action ensures that by the time the mixture enters the catalytic reactor, the reducing agent is already well-distributed in the flue gas, achieving sufficient mixing homogeneity in a compact configuration
Solution Approach 2:
The mixing pipeline acts as an intermediary component between the spray nozzle and the catalytic reactor. It provides a dedicated mixing zone where the reducing agent and flue gas can mix thoroughly before entering the catalyst, ensuring proper mixing homogeneity is achieved in the compact space without requiring a larger reactor volume
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 solution enables a more compact and integrated SCR system with improved NOx reduction efficiency by ensuring thorough mixing of flue gas and reducing agents within the air homogenization chamber, enhancing the catalytic reaction process.
Implementation Method 1
The selective catalytic reduction technology is to inject a reducing agent (e.g., urea solution), into the exhaust gas of a diesel engine to reduce the NOx in the flue gas into N2 and H2O
Implementation Method 2
the flue gas and a reducing agent can be fully mixed in the air homogenization chamber to improve the catalytic reaction efficiency
Data Source
AI summary
A reaction device of a marine SCR system comprises a conveying unit (110), a reaction chamber (120), at least one catalyst module (130), and an air homogenization chamber (140), wherein, the conveying unit (110) includes an input pipeline (111) and an output pipeline (112) sleeved outside the input pipeline (111). One end of the reaction chamber (120) is connected to the conveying unit (110). The reaction chamber (120) comprises an inner cylinder (121) and an outer cylinder (122) sleeved outside the inner cylinder (121), the inner cylinder (121) is in communication with the input pipeline (111), and the outer cylinder (122) is in communication with the output pipeline (112). The catalyst module (130) is provided between the inner cylinder (121) and the outer cylinder (122). The air homogenization chamber (140) is connected to the other end of the reaction chamber (120) and is in communication with both the inner cylinder (121) and the outer cylinder (122). With the reaction device of the marine SCR system whereby the outer cylinder is sleeved outside the inner cylinder, flue gas from the inner cylinder is turned by the air homogenization chamber and then flows back into the outer cylinder. This can not only substantially reduce the size of the reaction device to improve the integration of the SCR system, but also allow the flue gas to turn in the air homogenization chamber and then flow back, so that the flue gas and a reducing agent can be fully mixed in the air homogenization chamber to improve the catalytic reaction efficiency.