Combustion Control for Low NOx and Slag Prevention
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Solution Overview
Problem
Existing combustion technologies for reducing NOx emissions in coal combustion fail to adapt quickly to changing operating conditions, leading to suboptimal NOx reduction and increased unburned carbon in fly ash, and can cause slagging due to inadequate adjustment of operating parameters.
Innovation Solution
A combustion method involving a concentrated fuel and air stream is injected into a burner, rapidly heated by high-temperature combustion gas, and controlled based on sensed parameters to maintain a fuel-rich flame zone, optimizing NOx reduction and preventing slagging, using a system with a burner, combustion chamber, sensor, and controller to adjust operating conditions dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If combustion temperature is reduced or oxygen concentration is lowered to control NOx, then NOx emission is reduced, but burning efficiency decreases and burning rate slows down
Solution Approach 1:
The invention changes the temporal distribution of oxygen concentration parameters during combustion. By introducing air in staged manner (primary air for combustion, secondary air for NOx reduction), the system achieves low NOx emissions while maintaining high burning rate through optimized oxygen supply timing and concentration at different combustion stages
Solution Approach 2:
The invention maintains continuous combustion with high burning rate while intermittently introducing air to reduce NOx. The staged air injection ensures combustion continues without interruption, achieving both high productivity and low harmful emission by balancing continuous energy release with periodic oxygen supplementation
2Object-generated harmful factors
If combustion time is increased to reduce NOx emission, then NOx emission is reduced, but boiler size must be increased and capital investment rises
Solution Approach 1:
The invention maintains continuous combustion at high rate throughout the combustion process, eliminating the need to extend combustion time. By continuously supplying optimized air-fuel mixture and maintaining efficient burning conditions, the system achieves low NOx emissions without increasing boiler size or capital investment
Solution Approach 2:
The invention optimizes combustion parameters (oxygen concentration, temperature, air staging) to achieve rapid combustion completion. By changing these parameters dynamically during combustion, the system reduces NOx formation mechanisms while maintaining short combustion time, thus avoiding boiler size increases
3Object-generated harmful factors
If operating parameters are not quickly adjusted to adapt to changing conditions, then device structure remains simple, but NOx reduction becomes suboptimal and unburned carbon increases
Solution Approach 1:
The invention incorporates feedback control mechanisms that continuously monitor combustion conditions and adjust air supply accordingly. This enables rapid adaptation to changing operating conditions (coal quality variations, load changes) while maintaining optimal NOx reduction, resolving the contradiction between simple structure and adaptability through intelligent control
Solution Approach 2:
The invention introduces dynamic adjustment capabilities to the combustion system, allowing operating parameters (air flow rates, oxygen concentration) to be quickly modified in response to changing conditions. This dynamic approach enables the system to adapt to different coal types and operating scenarios while maintaining low NOx emissions
4Productivity
If high combustion temperature is used to maintain burning rate, then burning efficiency is maintained, but slagging occurs on burner and combustion chamber walls
Solution Approach 1:
The invention changes temperature distribution parameters by introducing air in staged manner. Primary combustion zone maintains high temperature for efficient burning, while secondary air introduction creates cooler zones that prevent slagging on walls. This parameter optimization allows high burning rate while controlling harmful thermal effects
Solution Approach 2:
The invention creates different thermal conditions in different spatial zones. The burner core maintains high temperature for efficient combustion, while peripheral zones receive cooler secondary air to prevent slagging. This local quality differentiation allows simultaneous achievement of high burning rate and prevention of harmful thermal deposition
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 achieves ultra-low NOx emissions and reduced unburned carbon in fly ash while preventing slagging, allowing for adaptability to various coal types without significant capital investment or operational cost increases.
Implementation Method 1
rapidly heated by high-temperature combustion gas
Implementation Method 2
the fuel nitrogen is devolatilized rapidly
Implementation Method 3
Fuel NOx is NOx formed due to the conversion of chemically bound nitrogen (fuel nitrogen)
Implementation Method 4
combustion process with high-temperature gas
Implementation Method 5
high temperature oxidation of atmospheric nitrogen
Data Source
AI summary
A method of combustion for pulverized hydrocarbonaceous fuel includes injecting a concentrated fuel and air stream into a burner, causing a low-pressure zone; directing a flow of a high-temperature combustion gas from a combustion chamber into the low-pressure zone in the burner; mixing the high-temperature combustion gas with the injected concentrated stream to heat the injected concentrated stream; injecting the heated concentrated stream from the burner to the combustion chamber, wherein the concentrated stream is rapidly devolatilized and combusted in a flame that has a fuel-rich flame zone; sensing a combustion parameter; and, based on the sensed combustion parameter, controlling combustion to achieve at least one of a desired NOx reduction and a desired distance from the burner to a flame front.