Oxy-combustion Mixing Grid for Uniform Oxygen Distribution
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Solution Overview
Problem
Oxygen firing in steam generators for coal-fired systems faces challenges with high flue gas recirculation costs and complexity, and limitations on oxygen concentration due to material constraints, necessitating effective oxygen mixing within flue gas streams to maintain efficient heat transfer and prevent premature combustion.
Innovation Solution
A distribution and mixing grid with a plurality of lances arranged transverse to the flue gas flow direction, equipped with inlets and outlet nozzles for oxygen discharge, is positioned within the ducts of the oxy-combustion system to ensure uniform oxygen distribution and mixing, utilizing computational fluid dynamic modeling for optimal configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If oxygen concentration in the oxidant stream is increased above 21%, then combustion efficiency is improved, but material costs increase due to the need for higher grade materials to withstand oxygen service
Solution Approach 1:
The invention changes the concentration parameter of oxygen in the oxidant stream by using a distribution and mixing grid to achieve uniform mixing. This allows the system to operate at optimal oxygen concentrations (21-23.5%) without exceeding material limits, as the uniform distribution prevents localized high-concentration zones that would require expensive high-grade materials.
2Temperature
If flue gas recirculation rate is increased to maintain mass flow, then heat transfer process is supported, but system complexity and auxiliary power consumption increase
Solution Approach 1:
The invention extracts the mixing function from the flue gas recirculation system by introducing a dedicated distribution and mixing grid. This separate mixing mechanism allows oxygen to be uniformly distributed without requiring high rates of flue gas recirculation, thereby reducing system complexity and auxiliary power consumption while still supporting the heat transfer process.
3Temperature
If flue gas recirculation rate is increased to maintain mass flow, then heat transfer process is supported, but auxiliary power consumption increases
Solution Approach 1:
The invention extracts the mixing function from the flue gas recirculation system by introducing a dedicated distribution and mixing grid. This separate mixing mechanism allows oxygen to be uniformly distributed without requiring high rates of flue gas recirculation, thereby reducing auxiliary power consumption while still supporting the heat transfer process.
4Quantity of substance
If oxygen mixing in recycled flue gas stream is improved, then oxygen concentration can be maintained within 21-23.5% range, but duct and component design becomes more complex
Solution Approach 1:
The invention segments the oxygen injection process into multiple discrete injection points distributed throughout the duct via the grid structure. This segmentation allows uniform oxygen distribution to be achieved through simple geometric arrangement rather than complex active control systems, maintaining oxygen concentration within the desired 21-23.5% range while avoiding excessive duct design 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 grid achieves superior oxygen mixing, maintaining concentrations within the desired range of 21% to 23.5% across the duct, reducing the need for high-grade materials and minimizing auxiliary power consumption, while ensuring efficient heat transfer and combustion processes.
Implementation Method 1
One or more of the outlet nozzles is directed generally in the flow direction of the first fluid outside of the lances, and is configured to discharge a second fluid (e.g., oxygen) therefrom
Implementation Method 2
The grid achieves superior oxygen mixing, maintaining concentrations within the desired range of 21% to 23.5% across the duct
Data Source
AI summary
A grid for distributing and mixing fluids in a duct includes a plurality of lances arranged in a first plane and configured to be positioned transverse to a direction of a first fluid flowing outside of the lances and within a predetermined flow area. Each of the plurality of lances has at least one first inlet and a plurality of outlet nozzles. One or more of the outlet nozzles is directed generally in the flow direction of the first fluid outside of the lances, and is configured to discharge a second fluid therefrom.