Gas Turbine SCR Control for NOx and Slip Reduction
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Solution Overview
Problem
Gas turbine systems face challenges in effectively reducing nitrogen oxides (NOx) emissions due to over-injection of reductants in Selective Catalytic Reduction (SCR) processes, which leads to reductant 'slip' and increased combustion dynamics, necessitating a coordinated approach to regulate emissions control measures.
Innovation Solution
A turbine system control system that coordinates fuel/air ratio, steam/water injection, and SCR operation to optimize NOx reduction, utilizing available SCR capacity to maintain emissions below regulatory thresholds while reducing mechanical and thermal fatigue, and improving power output and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If reductant injection is increased to reduce NOx emissions, then NOx reduction is improved, but reductant slip increases
Solution Approach 1:
The control system continuously monitors actual NOx emissions and compares them with predicted values, then adjusts reductant injection rates dynamically. This closed-loop feedback mechanism prevents both over-injection (causing slip) and under-injection (insufficient NOx reduction) by real-time optimization of the injection rate based on measured versus predicted emissions.
Solution Approach 2:
The system uses a predictor model to estimate upcoming NOx emissions based on current operating conditions before they actually occur. This preliminary prediction allows the control system to pre-adjust reductant injection rates, ensuring optimal injection timing and quantity before emissions peaks occur, thereby preventing both slip and insufficient reduction.
2Object-generated harmful factors
If reductant injection is increased to reduce NOx emissions, then NOx reduction is improved, but combustion dynamics increase
Solution Approach 1:
By continuously monitoring actual NOx emissions and comparing with predictions, the system adjusts reductant injection to the minimum effective rate needed for compliance. This prevents excessive injection that would amplify combustion dynamics while still achieving sufficient NOx reduction through precise, demand-based dosing.
Solution Approach 2:
The system dynamically changes the reductant injection rate parameter based on real-time operating conditions and predicted emissions. By adjusting this parameter precisely to match actual needs rather than using fixed high rates, the system achieves NOx reduction while minimizing disturbances to combustion stability and dynamics.
3Loss of substance
If SCR capacity is optimized to reduce reductant slip, then reductant utilization is improved, but NOx reduction capacity may be limited
Solution Approach 1:
The predictor model forecasts upcoming NOx emissions based on current operating parameters before they manifest. This allows the control system to pre-position the appropriate reductant injection rate, ensuring that sufficient reductant is available when needed for NOx reduction while avoiding excessive injection that would cause slip. The prediction enables precise timing and dosing.
Solution Approach 2:
The closed-loop control continuously compares predicted NOx emissions with actual measurements and adjusts reductant injection accordingly. This feedback ensures that the SCR system operates at optimal utilization points, matching reductant injection precisely to actual emissions needs, thereby preventing both slip and insufficient NOx reduction capacity.
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 system effectively reduces NOx emissions by adjusting operating parameters, minimizing reductant slip, and reducing combustion dynamics, thereby extending hardware life and improving overall performance and efficiency of the gas turbine system.
Implementation Method 1
a selective catalytic reduction system having a catalyst
Implementation Method 2
a selective catalytic reduction system having a catalyst... a reducing agent, such as ammonia, is supplied to an injector... to react injected ammonia with NOx from the combustor
Data Source
Figure 1
Figure 2~3
AI summary
Embodiments of the present disclosure are directed towards a system 10 including a gas turbine engine 12, a selective catalytic reduction system 30, and a control system 46 configured to regulate operation of the selective catalytic reduction system 30 based at least partially on preset variations in an emissions compound of exhaust gases produced by the gas turbine engine 12.