Combustion Air Jet Pump for Flue Gas Recirculation
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Solution Overview
Problem
Current methods for achieving low NOx emissions in fossil fuel-fired combustion applications through flue gas recycling increase equipment complexity, capital costs, and operational expenses, particularly due to the need for larger and more expensive fans to handle recycled flue gas, which can also become fouled and require additional maintenance.
Innovation Solution
A burner apparatus utilizing a combustion air driven jet pump to mix flue gas with combustion air and fuel, where the jet pump creates negative pressure to draw flue gas without the need for additional fans, allowing for efficient NOx reduction with reduced heat loss and thermal efficiency, using a design that includes a tapered nozzle and mixing tube to enhance mixing and suction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If flue gas recycling is implemented using conventional methods (additional piping, enlarged combustion air fan), then NOx emissions are reduced, but equipment complexity and capital costs increase
Solution Approach 1:
The patent combines the flue gas recirculation function with the existing combustion air fan by integrating a recirculation port and mixing chamber into the burner assembly. This allows the same fan to handle both combustion air and recirculated flue gas, merging two separate functions into one system and reducing equipment complexity while maintaining NOx reduction effectiveness
Solution Approach 2:
The patent introduces a mixing chamber as an intermediary component that receives both combustion air from the fan and recirculated flue gas through the recirculation port. This mixing chamber serves as a mediator that combines the two gas streams before delivery to the combustion zone, enabling flue gas recycling without requiring separate piping systems or additional fans
2Object-generated harmful factors
If the combustion air fan is enlarged to handle increased flue gas volume, then flue gas recirculation is achieved, but operational costs and energy consumption increase
Solution Approach 1:
The patent uses the existing combustion air fan at its normal operating capacity to handle both combustion air and recirculated flue gas. The recirculation port is designed to provide the necessary flue gas flow without requiring the fan to operate at increased capacity, thereby avoiding additional energy consumption while achieving effective flue gas recirculation for NOx control
3Object-generated harmful factors
If the combustion air fan is enlarged to handle increased flue gas volume, then flue gas recirculation is achieved, but fan maintenance requirements increase
Solution Approach 1:
The patent segments the gas handling system by providing separate pathways: the combustion air fan handles only combustion air through the main air inlet, while recirculated flue gas is introduced separately through the recirculation port into the mixing chamber. This segmentation prevents hot, corrosive flue gas from contacting the fan, eliminating the need for expensive alloy materials and reducing maintenance requirements
Solution Approach 2:
The mixing chamber serves as an intermediary that receives recirculated flue gas and mixes it with combustion air before the mixture enters the combustion zone. This positioning ensures that the fan never directly handles the hot, corrosive flue gas, protecting the fan from fouling and corrosion while enabling effective flue gas recirculation
4Object-generated harmful factors
If additional flue gas piping and high temperature rated fan are used, then flue gas recirculation is achieved, but device complexity and capital costs increase
Solution Approach 1:
The patent merges the flue gas recirculation pathway with the existing burner structure by integrating the recirculation port and mixing chamber into the burner assembly. This eliminates the need for separate flue gas piping and high temperature rated fans, reducing device complexity and capital costs while achieving effective NOx control through flue gas recirculation
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 solution reduces NOx emissions effectively while minimizing equipment upgrades and operational costs, using smaller ducting and maintaining thermal efficiency by integrating flue gas recycling into the combustion process without additional fan requirements.
Implementation Method 1
The negative pressure, once connected to the flue gas source, can be used to pull flue gas from the flue gas source without the use of an additional fan
Implementation Method 2
A jet pump for directing high velocity combustion air through a nozzle and along a central longitudinal axis of the plenum
Implementation Method 3
The flue gas and combustion air are mixed in a narrowing portion of the chamber used to convey the fluids
Implementation Method 4
The fuel and flue gas-combustion air mixture are mixed to form a fuel-flue gas-combustion air mixture in a mixing portion of the burner throat which has a diameter (D). The mixture is ignited and the flame and resultant flue gas exits the chamber at outlet 208
Data Source
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AI summary
Devices, methods, and systems for utilizing a burner with a combustion air driven jet pump are described herein. One burner apparatus includes a jet pump located inside a burner housing, the jet pump having a combustion air inlet that receives combustion air, a chamber to receive the combustion air from the combustion air inlet, and a tapered portion of the chamber that tapers to an outlet having a smaller diameter than the diameter of the inlet.