NOx emissions are about one-tenth those of high-speed diesel engines (those having the lowest NOx emissions). Thermal efficiency is approximately the same as that of high-speed diesel engines. When these target figures are compared with those of industrial gas turbines of the same output class, they represent a one-third reduction in NOx emissions (liquid fuel combustor) and an approximately ten-point improvement in thermal efficiency. Ten-point increase in efficiency means about 30% improvement in fuel consumption.
In addition, the SMGT will be able to use the readily available type A fuel oil.
3. R&D Schedule
The R&D schedule is shown in Figure 2. In 1997, basic overall design work for the gas turbine was completed and the above target goals for each component were developed. Beginning in 1998, a variety of tests were carried out on the components. At present, this component research is almost completed. A prototype test engine of the SMGT will be completed midway through 2001. From then until 2002 (the plan's final year), rig tests will be performed to evaluate its performance.
4. Basic Design
Figure 1 shows a schematic diagram of the SMGT.
1) One way to reduce NOx emissions is by the wet method, using water or steam. However, because this method requires large amounts of clean water it is unsuitable for use on ships. The SMGT uses a dry-type low-NOx combustor (DLN) using lean combustion. The can-type (4 cans) combustor is used. The can-type combustor allows significant design freedom for DLN combustor design and is the easy-to-maintain.
2) Thermal efficiency is improved by using a regenerative cycle. The recuperator is a compact, highly efficient and durable plate-fin type suitable for marine use.
3) Further improvement in thermal efficiency is achieved by using a turbine inlet temperature of 1,200℃, exceeding that of conventional gas turbines in this class.
4) A compressor which combines both axial and radial stages is used. It is more efficient than a simple radial compressor. For this, more efficient cooled blades are required.
5) To improve thermal efficiency under partial load, a variable power turbine with variable nozzle is also being developed. In the case of regenerative double-shaft gas turbine, the gas temperature at the recuperator inlet can be maintained a high level under partial loads, which improves thermal efficiency; by reducing mass flow rate. Mass flow rate can be controlled by the variable nozzle. The SMGT will use variable stator vanes in the compressor's axial stage also.
6) The SMGT uses modular construction to facilitate installation/removal and for ease of maintenance.
Target design specifications are shown in Table 1 and Table 2, and the basic design of the power section (V-type) are shown in Figure 3.
Figure. 2 R&D schedule
