A Review of the Turbine Cooling Fraction for Very High Turbine Entry Temperature Helium Gas Turbine Cycles for Generation IV Reactor Power Plants

Abstract

of The potential for high Turbine Entry Temperatures (TET) turbines for Nuclear Power Plants (NPPs) require improved materials and sophisticated cooling. Cooling is critical to maintaining mechanical integrity of the turbine for temperatures >1000°C. Increasing TET is one of the solutions for improving efficiency after cycle optimum pressure ratios have been achieved but cooling as a percentage of mass flow will have to increase, resulting in cycle efficiency penalties. To limit this effect, it is necessary to know the maximum allowable blade metal temperature to ensure the minimum cooling fraction is used.

Analyses of the Effect of Cycle Inlet Temperature on the Precooler and Plant Efficiency of the Simple and Intercooled Helium Gas Turbine Cycles for Generation IV Nuclear Power Plants

“…The ICR and IC increase the Specific Work (SW) and Useful Work (UW) by reducing the work required by the compressors. This means that the ICR has an efficiency which is ~3% greater than the SCR and 6.6% greater than the IC when optimised turbine cooling methods are considered [3]. However, the ICR has a disadvantage in that the increased capacity, due to the number of components, adds complexity to the plant configuration.…”

“…The material is taken directly from [1,3,9] which were written by the authors and is part of the overall research work, which this study is linked to. [3].…”

“…The material is taken directly from [1,3,9] which were written by the authors and is part of the overall research work, which this study is linked to. [3]. The structure shows a typical SCR single shaft configuration with all the components and helium circuit including the bleed off point from the compressor (S denotes splitter), which channels cool the reactor, and the turbine via M (denoted as mixer).…”

“…On the other hand, the IC offers a simpler component configuration than the ICR but it requires reactor Core Outlet Temperatures ≥1000 °C to significantly improve the efficiency, which will make it competitive. This was investigated as part of this research work and is documented in [3]. The benefits of using helium as opposed to air are documented in [4][5][6] and provide a good theoretical platform for off-design operation, control, and transient operation of a helium nuclear gas turbine plant.…”

“…The three cycles pertaining to this study are extensively described in [3]. Figures 1-3 show the cycle schematics for the SCR, ICR, and IC, respectively.…”