Open-Tip Flare Burner Assembly for Ultra-Low NOx Combustion
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Solution Overview
Problem
Conventional surface burners used in waste gas flares are susceptible to clogging, overheating, and failure due to dirt and contaminants, leading to inefficiencies and increased maintenance, and they struggle to achieve ultra-low nitrous oxide (NOx) emissions while operating with lean air mixtures.
Innovation Solution
The use of an open tip burner assembly that mixes waste gas and oxidant in a pre-mixing chamber or at the burner tip, combined with a swirl plate to anchor and direct the flame, allows for a very lean waste gas-oxidant mixture, achieving ultra-low NOx emissions by introducing excess oxidant to cool the flame and reduce thermal stress on components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional surface burners are used in waste gas flares, then the burners can operate with lean air mixtures, but the burners are susceptible to clogging, overheating, and failure due to dirt and contaminants
Solution Approach 1:
The burner is divided into multiple ports with different functions: some ports introduce waste gas while others introduce oxidant. This segmentation allows each port to be optimized for its specific function and reduces the risk of complete burner failure, as clogging in one port does not necessarily prevent operation through other ports.
Solution Approach 2:
Different regions of the burner are given different properties: the burner includes ports of varying sizes and orientations, with some ports specifically designed for contaminant resistance while others optimize combustion efficiency. The burner tip geometry is specifically designed to anchor the flame while allowing excess oxidant to pass through and cool the burner surface.
2Productivity
If conventional burners operate with lean air mixtures, then combustion efficiency is maintained, but nitrous oxide emissions increase due to high flame temperatures
Solution Approach 1:
The burner changes the temperature parameter by introducing excess oxidant that cools the flame. The burner operates with an oxidant-to-waste-gas ratio greater than the stoichiometric ratio, which maintains combustion efficiency while reducing flame temperature to below 1800°F, thereby reducing thermal NOx formation.
Solution Approach 2:
Excess oxidant acts as an intermediary cooling medium that passes through the flame zone without being completely consumed. This cool oxidant stream reduces the temperature of the combustion products and prevents excessive thermal NOx formation while maintaining complete combustion of the waste gas.
3Object-generated harmful factors
If excess oxidant is introduced to cool the flame, then nitrous oxide emissions are reduced, but the complexity of the burner assembly increases
Solution Approach 1:
The burner assembly is designed to perform multiple functions through its port configuration: the same ports that introduce oxidant for combustion also serve as cooling channels. The excess oxidant introduced for emission control simultaneously cools the burner surfaces and stabilizes the flame, eliminating the need for separate cooling systems.
4Productivity
If the burner operates at high temperatures to maintain combustion efficiency, then combustion performance is improved, but thermal stress on components increases leading to overheating and failure
Solution Approach 1:
Cool oxidant is introduced upstream and mixes with the waste gas before combustion occurs. This preliminary cooling action reduces the peak flame temperature and prevents excessive thermal stress on the burner components, while still allowing complete combustion to occur.
Solution Approach 2:
The burner uses fluid dynamics of the oxidant stream to achieve cooling: the excess oxidant flows through the combustion zone as a cooling fluid, absorbing heat from the flame and burner surfaces. This pneumatic cooling system eliminates the need for separate mechanical cooling systems.
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 open tip burner assembly achieves ultra-low NOx emissions (less than 0.025 #/MM BTU) and low carbon monoxide emissions (less than 0.06 #/MM BTU) while maintaining operational stability and reducing the risk of clogging and overheating, with a flame temperature below 1800°F.
Implementation Method 1
a swirl plate positioned upstream of the burner tip... The swirl plate operates to direct and anchor the combustion flame
Implementation Method 2
an open tip burner assembly that mixes waste gas and oxidant in a pre-mixing chamber or at the burner tip
Implementation Method 3
achieving ultra-low NOx emissions by introducing excess oxidant to cool the flame and reduce thermal stress on components
Implementation Method 4
igniting the mixture to create a combustion flame... Burning one ton of methane produces 2.75 tons of CO2
Data Source
AI summary
A flare system operable at ultra-low nitrous oxide (NOx) emission levels without utilizing a surface burner. The flare system includes a flare stack and a burner assembly positioned in the flare stack between a closed plenum and an open exhaust chamber, the burner assembly and the flare stack defining an excess oxidant passage for routing excess oxidant between the plenum and the exhaust chamber. The burner assembly includes: a body defining a central passage through which oxidant and waste gas flow, the central passage being separated from the excess oxidant passage, a burner tip defining an open tip passage through which the oxidant and the waste gas flow from the central passage into the exhaust chamber, and a swirl plate positioned upstream of the burner tip. The swirl plate operates to direct and anchor a combustion flame ignited in the exhaust chamber.