5. R&D Items
As stated above, the SMGT's targeted performance exceeds that of conventional gas turbines, so the performance of its combustor, recuperator, compressors and turbines must also exceed those of conventional gas turbines.
Below is the latest research on achieving the target goals for each component and the results.
5.1) Research on Low NOx Combustor
In place of the conventional diffusion combustion method, a low-NOx combustor is being developed featuring pre-vaporization and pre-mixing to create a lean combustion, one that permits use of liquid fuel such as fuel oil type A.
As is well known, the lean combustion method lowers the maximum combustion temperature, suppressing the generation of thermal NOx. However, this method has the drawback of a tendency towards unstable, incomplete combustion. In order to develop a combustor that maintains low-NOx combustion over a wide range of load conditions from light off through to full-load operation, a variety of problems must be solved.
The 3-burner combustor now being developed (Figure 4) uses: (1) a pilot burner for light off, (2) a main burner using pre-vaporization and pre-mixing to ensure the proper mixing of fuel and air for lean combustion, and (3) a supplemental burner which injects fuel into the following region of the main combustion under full load conditions. Figure 5 shows how fuel supply is regulated to each burner from light off to full load. As a result, low-NOx operation is maintained over a wide range.
To develop this technology, the following research has been carried out: Experiments to improve the fuel injection characteristics of injector nozzles. Tests to improve combustion stability, efficiency and NOx emission of the main burner. In addition, flow model experiments have been used to perform precision flow analysis inside the combustor.
