Can Combustor Shell Coupling for Thermal Expansion Management
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Solution Overview
Problem
Existing gas turbines face challenges in achieving high efficiency while minimizing NOx emissions and maintaining operational flexibility, as high turbine inlet temperatures lead to increased emissions, and current sealing technologies between the cold and hot shells in can combustors either restrict relative movement or increase pressure drop.
Innovation Solution
A direct surface contact coupling between the upstream end of the cold shell and the hot shell, eliminating the need for additional sealing elements, allowing relative movement without affecting the air gap dimension, and incorporating a cooling air channel with axial and circumferential sliding capabilities, featuring passing slots and inclined effusion holes for film cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sealing elements (hula seal or piston ring) are used between cold shell and hot shell, then the interface is sealed, but the air gap dimension is reduced and pressure drop increases
Solution Approach 1:
The invention removes traditional sealing elements (hula seals, piston rings) from the interface between cold and hot shells. Instead, it uses the direct contact between the inner surface of the cold shell upstream end and the outer surface of the hot shell intermediate portion to achieve sealing, thereby eliminating the space occupation of sealing elements and maintaining the air gap dimension without increasing pressure drop
Solution Approach 2:
The invention introduces a cooling air channel as an intermediary structure between the cold and hot shells. This channel provides a controlled path for cooling air while the direct surface contact between shells maintains sealing. The cooling air channel includes passing slots in the cold shell and effusion holes in the hot shell that allow cooling air to reach the hot shell surface without requiring additional sealing elements
2Stability of the object's composition
If the cold shell and hot shell are rigidly fixed together, then structural stability is improved, but relative movement to compensate temperature differences is restricted
Solution Approach 1:
The invention creates a dynamic interface between the cold and hot shells where the upstream end of the cold shell can slide axially and circumferentially relative to the hot shell. This is achieved through direct surface contact without rigid fixation, allowing the shells to move relative to each other to compensate for thermal expansion and contraction while maintaining sealing through the contact surfaces
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 enables relative movement between the shells to compensate for temperature differences without altering the air gap, maintaining efficiency and reducing NOx emissions by ensuring a sealed and cooled interface, thus improving the performance of the gas turbine plant.
Implementation Method 1
The cooling air channel comprises a plurality of passing slots having at least an axial extent obtained in the upstream end of the outer tubular body and at least a channel obtained in a portion the inner tubular body radially corresponding with the slot. The effusion holes are inclined with respect to the radial direction centered at the combustor axis to realize a film cooling
Data Source
Figure 1~2
Figure 3~7
AI summary
A can combustor (4) for a gas turbine (1), the can combustor (4) comprising: at least a burner (5, 20, 22); at least a liner (7) defining a combustion chamber (6, 21, 23) having a combustor axis (24); wherein the liner (7) comprises: an inner tubular body (30); an outer tubular body (31) overlapping at least in part the inner tubular body (30) and spaced from the inner tubular body (30) for defining a cooling air gap (32); wherein the outer tubular body (31) comprises a upstream end (34) coupled with an intermediate portion of the inner tubular body (30).