Sequential Combustor Dilution Gas Admixer Pressure Loss Ratio
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Solution Overview
Problem
Existing gas turbine combustion systems face challenges in maintaining low emissions and operational flexibility, particularly at part load and transient conditions, due to variability in operating conditions and inadequate control of inlet temperatures and fuel mixing in sequential combustion systems.
Innovation Solution
A sequential combustor arrangement that includes a dilution gas admixer between the first and second combustion chambers, which controls the inlet flow conditions by adjusting the pressure loss ratio of the first combustor to the dilution gas admixer within a specific range (2 to 12) to ensure stable combustion and reduce emissions, using compressed air or a mixture of air and flue gases as dilution gas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the inlet gas temperature to the second combustion chamber is increased, then the combustion efficiency is improved, but the emissions (NOx, CO, unburned hydrocarbons) increase and flashback occurs
Solution Approach 1:
The combustion process is divided into two separate combustion chambers with distinct functions. The first combustion chamber performs primary combustion, while the second combustion chamber performs secondary combustion with diluted gases. This segmentation allows temperature and emission control in each stage, preventing excessive temperatures that cause NOx while ensuring complete combustion for efficiency.
Solution Approach 2:
A dilution gas admixer is introduced as an intermediary component between the first and second combustion chambers. This admixer introduces dilution gas (such as recirculated exhaust gas or ambient air) to lower the temperature of gases entering the second combustion chamber, preventing flashback and reducing NOx emissions while maintaining combustion efficiency through proper temperature control.
2Object-generated harmful factors
If the inlet gas temperature to the second combustion chamber is decreased, then emissions are reduced and flashback is prevented, but combustion stability deteriorates and CO emissions increase
Solution Approach 1:
The system dynamically adjusts the dilution gas flow rate and composition to optimize the inlet temperature to the second combustion chamber. By controlling the amount of dilution gas introduced through the admixer, the system maintains temperature within an optimal range that ensures stable combustion and low emissions across varying operating conditions.
3Adaptability or versatility
If the gas turbine operates at lower load, then operational flexibility is improved, but the control of inlet temperatures and fuel mixing becomes inadequate leading to higher emissions
Solution Approach 1:
The sequential combustion system with dilution gas admixer provides dynamic control capabilities that adapt to varying load conditions. The dilution gas flow rate can be adjusted independently of the main fuel flow, allowing the system to maintain optimal combustion conditions and low emissions across the entire operating range from part load to full load, thereby improving operational flexibility.
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 maintains stable combustion with reduced emissions (NOx, CO, and unburned hydrocarbons) and prevents flashback by ensuring proper mixing and temperature control, enhancing operational flexibility and efficiency of the gas turbine across varying load conditions.
Implementation Method 1
a dilution gas admixer for admixing a dilution gas to the first combustor combustion products leaving the first combustion chamber
Implementation Method 2
a first burner for admitting a first fuel into a combustor inlet gas during operation, and a first combustion chamber for burning the first fuel with the combustor inlet gas
Data Source
AI summary
The invention refers to a sequential combustor arrangement including a first combustor with a first burner for admitting a first fuel into a combustor inlet gas during operation and a first combustion chamber for burning the first fuel, a dilution gas admixer for admixing a dilution gas to the first combustor combustion products leaving the first combustion chamber, and a second burner for admixing a second fuel and a second combustion chamber. To assure good mixing over a wide operating range, the ratio of the pressure loss of the first combustor to the pressure loss of the dilution gas admixer is in the range of 1 to 6. The invention further refers to a gas turbine including such a sequential combustor arrangement as well as method for operating a gas turbine with such a sequential combustor arrangement.