Radial Steam Turbine Research Articles

6-3.余剰蒸気からのエネルギ回収量を増加させるための蒸気過熱器の開発((1)省エネルギー型機器,Session 6 省エネルギー)

6-3.余剰蒸気からのエネルギ回収量を増加させるための蒸気過熱器の開発((1)省エネルギー型機器,Session 6 省エネルギー)

Computational analysis of erosion in a radial inflow steam turbine

Abstract In the present work, the erosion of the blades of a radial inflow turbine due to the ingested steam flow containing solid particles was investigated in detail. The study has been conducted by designing and modeling the 3D geometry of the turbine using the CFturbo tool and by carrying out a series of CFD simulations using the software package ANSYS CFX 15.0. As compressibility effects may affect the output results, a study was conducted to ensure the validity of the incompressible flow assumption. Furthermore, the erosion simulation results indicated that there are three main surface areas where significant erosion occurs. The first and by far the most affected part of the studied radial steam turbine is the trailing edge of the stator blade, where a relatively huge number of particles with sharp angles strike the surface. This surface area is found to be affected by a concentration effect, where a high number of particles impinge on a small surface area continuously. The second but less affected part is the leading edge of the suction side of the rotor blade, where the particles strike the blade surface many times. The particles are trapped in a vortex area between the trailing edge of the stator blades and the leading edge of the rotor blades. The third surface area which is eroded significantly is the central region of the pressure side of the rotor blade. However, the blade erosion in this area is less than the other two areas. Additionally, the effects of several factors such as the rotor rotational speed, input mass flow and particle size on the erosion have been studied in detail. The relations between these factors and the erosion rate density have been determined.

Conceptual Design of Power Generation System Utilizing Heat from Exhaust Gases of Marine Diesel Engine

Exhaust gas economizers have been installed on a wide range of ships, for better fuel oil economy; since the oil crises of the 1970's. After the turn of the century, the pressure improve the fuel economy further, as well as to protect the environment markedly increased. The authors propose a concept for a power generation system, for domestic ships, to substantially improve fuel oil economy. Also, reduce SOx emissions by utilizing the rejected heat of exhaust gases from marine diesel engines. As a heat exchanging device, a circulating fluidized bed, here a mixture of the exhaust gas and fine, desulphurization solid particles circulate. This for reason of higher overall heat transfer coefficients and the quality to reduce sulphur-oxides emissions through a dry desulphurization process, in the fluidized bed. As an electric power plant, a radial steam turbine was integrated with a high speed dynamo, this selected because of a higher energy conversion rate. This technology is based on the micro gas turbine. A preliminary estimate indicates that an electric power of 80 to 100 kW will be recovered from the exhaust gases, and at the loading factor of 75 % for 1500kW-class marine diesel engines.

4409 100kWラジアル蒸気タービンシステムの開発(J11-1 コージェネ,マイクログリッド,J11 小型・分散エネルギー技術)

In view of growing needs for the effective recovery of steam energy, which might be otherwise wasted because of its low temperature, low pressure and so on, one of the reliable and promising choices is the introduction of small, distributed steam power generation systems. In particular, high-efficiency small steam turbines in the power range of less than 1MW are effective for the above usage, such as the on-site introduction to where the surplus or that low-grade steam exists. In this paper, the 100kW radial steam turbine system with 2t/h-class once-through boilers and steam heaters is presented focusing on its system concept, design features and operational results. And in the inlet pressures up to 0.75MPa and inlet temperatures up to 216℃, the steam turbine power generation system was operated in order to investigate the total system efficiencies and performances. And the turbine efficiency at the output shaft was calculated to be 84% at the design condition, and it was higher than what were previously reported.

Flow Investigation of a Radial Steam Turbine Nozzle

Flow Investigation of a Radial Steam Turbine Nozzle

Embrittlement of a steam turbine rotor

A 3Cr0.5Mo turbine disc has been examined to gain more knowledge regarding the life prediction of steam turbines. The disc was used in a radial steam turbine for about 70,000 h between 1965 and 1992. During service hot and pressurized steam caused a temperature gradient in the disc from 535 °C in the centre to 330 °C in the periphery. It is clear that there is a reduction in hardness from the periphery to the centre of the discs, and also a decrease in Charpy V energy. The reduction in hardness is mainly caused by additional tempering of the material due to the high temperature in the centre of the disk. The reduction in Charpy V energy shows that the material has become severely embrittled and the transition temperature is notably higher in the centre than in the periphery. Auger analysis shows that the major cause of the embrittlement is the diffusion of phosphorus to the prior austenite grain boundaries.

Optimum Design of a Low-Pressure, Double Inflow, Radial Steam Turbine for Open-Cycle Ocean Thermal Energy Conversion

This paper describes the thermo-fluid design concept of a low-pressure, radial inflow steam turbine for the Open-Cycle Ocean Thermal Energy Conversion (OTEC). For the optimum design consideration, the necessary theoretical tools are developed. The design concept permits the utilization of single-stage and multistage configurations for small and medium power ranges, respectively.

Paper 9: Theoretical and Experimental Studies of Wet Steam Erosion in a Counter-Rotating Radial Steam Turbine

Erosion test in a model counter-rotating radial flow turbine has been performed to assist in the design of a 460-MW radial flow turbine. Three rows of erosion specimens were inserted at different radial locations in the last blade ring upstream of the blades to investigate the influence of the radial distance between the stages. Results showed that small droplets were formed and that erosion diminished with increased radial spacing up to a certain distance. A theoretical model for calculating droplet trajectories, sizes, and impact velocities has been derived, taking full account of wake velocity, variable droplet drag coefficient, and atomization. The calculations explained all the experimental facts and made it possible to convert the model test results to the full-size turbine showing no risk of erosion in the latter.