Submerged Combustion Vaporizer NOx Suppression via Staged Fuel Injection
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Solution Overview
Problem
Submerged combustion vaporizers for heating cryogenic fluids emit nitrogen oxides (NOx) into the atmosphere, which are harmful pollutants that existing technologies have not effectively suppressed.
Innovation Solution
The system injects a staged fuel stream into the exhaust duct system and mixes water into the premix within the burner to reduce NOx levels by diluting the combustible mixture and lowering the flame temperature, thereby suppressing NOx production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional combustion is used in the SCV, then heating efficiency is maintained, but NOx emissions increase
Solution Approach 1:
The combustion process is divided into multiple stages with separate fuel injection points. Primary combustion occurs in the burner, and secondary combustion occurs downstream in the duct system where additional fuel is injected and mixed with the exhaust gases, allowing controlled combustion that reduces NOx while maintaining heating efficiency
Solution Approach 2:
The system changes the combustion parameters by injecting staged fuel streams at different locations and controlling the mixing ratios. This allows optimization of the combustion process to achieve lower flame temperatures and reduced NOx formation while maintaining adequate heating output
2Object-affected harmful factors
If flame temperature is reduced to suppress NOx, then NOx emissions decrease, but heating efficiency decreases
Solution Approach 1:
The heating process is segmented into primary combustion (lower temperature for NOx control) and secondary combustion (additional heating). The staged fuel injection allows the system to maintain lower peak flame temperatures that reduce NOx while still achieving the required heating effect through the combined combustion stages
Solution Approach 2:
The exhaust gases from the primary combustion act as an intermediary medium. They are mixed with additional fuel in the duct system, serving as both the combustion products to be treated and the heating medium for the secondary combustion process, enabling temperature control and NOx suppression
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 approach effectively maintains low NOx levels in the exhaust, providing a method for both new installations and retrofits of submerged combustion vaporizers, thereby reducing environmental pollution.
Implementation Method 1
mixing water into the premix
Implementation Method 2
diluting the combustible mixture and lowering the flame temperature
Implementation Method 3
a burner that fires into a duct system
Implementation Method 4
combustion of the fuel stream
Implementation Method 5
The exhaust then heats the water and the submerged tubing
Implementation Method 6
direct the burner exhaust to bubble upward through the water in the tank
Data Source
AI summary
A submerged combustion vaporizer may include a premix burner with multiple integral mixers for forming premix and discharging the premix into the duct system that communicates the burner with the sparger tubes. The SCV may further include a NOx suppression system that injects a staged fuel stream into the exhaust in the duct system, and/or a NOx suppression system that mixes water with the premix.