Shell and Tube Lean Direct Injector for Gas Turbine Combustion
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Solution Overview
Problem
Existing combustion systems face challenges in uniformly injecting multiple fuel and air streams, leading to high nitrogen oxide (NOx) emissions due to large recirculating flow fields, and current lean direct injection (LDI) combustors are complex to construct with multiple diffuser tips and passages.
Innovation Solution
A shell and tube heat exchanger concept is used to design a lean direct injection (LDI) combustion system where one side carries the oxidizer (air) and the other side carries fuel to the combustor, with holes in the end plate allowing for uniform injection, allowing for easy construction of multiple LDI injector sets with uniform air and fuel flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If multiple fuel passages and diffuser tips are used to inject fuel and air streams, then the combustion system can achieve lean direct injection for reduced NOx emissions, but the head end assembly becomes complicated and difficult to construct
Solution Approach 1:
The combustion system is divided into multiple independent LDI injector sets, each containing a diffuser tip with fuel passages and an adjacent annular region for air injection. This segmentation allows each injector set to be designed and constructed as a simple, repeatable module, eliminating the need for a complicated head end assembly while achieving uniform injection across multiple streams
Solution Approach 2:
The patent combines the fuel injection and air mixing functions into a single integrated LDI injector set structure, where the diffuser tip with fuel passages and the annular air region are merged into one compact unit. This merging simplifies the overall assembly by eliminating separate components and reducing the complexity of the head end assembly
2Stability of the object's composition
If a large recirculation zone is used to stabilize the combustion reaction zone, then combustion stability is improved, but nitrogen oxide (NOx) emissions increase
Solution Approach 1:
The patent creates different flow conditions in different regions: a recirculating flow field in the combustion chamber for stability, and a lean direct injection zone at the diffuser tip for low NOx emission. The LDI injector sets are positioned to create localized high-velocity jets that mix fuel and air efficiently, maintaining stability without requiring a large recirculation zone that would increase NOx emissions
Data Source
AI summary
The present invention is directed to a lean direct injection (LDI) combustion system for a gas turbine using a shell and tube heat exchanger concept to construct a shell and tube lean direct injector (“LDI”) for the combustion system. One side of the LDI injector, either the shell side or the tube side, carries an oxidizer, such as air, to the combustor, while the other side of the LDI injector carries fuel to the combustor. Straight or angled holes drilled in an end plate of the combustor allow the fuel to enter the combustor and mix with air being injected into the combustor.