Exhaust system for steam turbine

Abstract

An exhaust system for a steam turbine provided with an improved annular flow guide in a high pressure or intermediate pressure turbine. The improved flow guide reduces flow turbulence in an exhaust hood and reduces pressure loss to thereby improve turbine plant efficiency. The shape (vertically symmetric) of a flow guide 5A according to a conventional technology was modified into the shape (vertically asymmetric) of a flow guide 5 such that the length of a downstream flow guide portion 5d is greater than that of a upstream flow guide portion 5u. Numerical analyses were performed to find the optimum flow guide occupation ratio of the conventional technology and the corresponding total pressure loss coefficient. The obtained values were used as reference values. Further, the flow guide occupation ratio of the upstream flow guide portion 5u was set at 0.4 and the flow guide occupation ratio of the downstream flow guide portion 5d was set at 0.7; at values where the total pressure loss coefficient becomes lower than the reference value. The rectification effect of the flow guide can thus be enhanced.

Description

technical field [0001] The present invention relates to a turbine exhaust for discharging a steam flow passing through a rotor of a steam turbine from an exhaust pipe, in particular to an exhaust for a high or intermediate pressure turbine. Background technique [0002] A power plant that generates electricity by rotating a turbine with steam generated by a steam generator such as a boiler generally includes a plurality of turbines corresponding to the steam pressure, such as a high-pressure turbine, an intermediate-pressure turbine, or a low-pressure turbine. The steam that has completed the rotating operation by passing from the high-pressure turbine to the low-pressure turbine is finally introduced into the condenser, where it is condensed into condensed water and then returned to the steam generator. [0003] Immediately after the outlets of the high, medium and low pressure turbines, there is a turbine exhaust device leading to the downstream equipment such as the turbi...

AI Technical Summary

Problems solved by technology

If the annular flow guide is too large (long), it will block the flow path and become the main cause of performance degradation

Therefore, most of the deflectors of conventional high-pressure turbines and medium-pressure turbines have substantially the same cross-sectional shape in the circumferential direction (upper and lower symmetry), and it is difficult to think of changing this shape.

[0011] In addition, the exhaust chamber of the high-pressure turbine or the intermediate-pressure turbine has a shorter axial distance than the exhaust chamber of the low-pressure turbine, so that a sufficient diffuser function cannot be obtained.

Therefore, in the prior art, even if it is proposed to change the shape of the flow guide of the low-pressure turbine, it is difficult to immediately think of the idea of ​​the flow guide suitable for the high-pressure turbine and the medium-pressure turbine.

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