Valves for gas-turbines and multipressure gas-turbines, and gas-turbines therewith

Abstract

A multiport valve suitable for use with a gas-turbine allowing switching of a mode of gas-turbine operation between a Brayton cycle and an inverse Brayton cycle, and a gas-turbine configured to switch between a high-pressure operation mode according to a Brayton cycle and a low-pressure operation mode according to an inverse Brayton cycle employing the valve are provided. Also provided are a method and apparatus for operating a gas-turbine according to an inverse Brayton cycle.

Description

RELATED APPLICATION[0001]The present application gains priority from U.S. Provisional Patent Application No. 61 / 116,394 filed 20 Nov. 2008 which is included by reference as if fully set forth herein.FIELD AND BACKGROUND OF THE INVENTION[0002]The present invention, in some embodiments, relates to the field of gas-turbines, and more particularly, but not exclusively, to gas-turbines operable in both high-pressure (Brayton cycle) and low-pressure (inverse Brayton cycle) modes. The present invention, in some embodiments, relates to the field of gas-turbines, and more particularly, but not exclusively, to gas-turbines operable in low-pressure mode (inverse Brayton cycle).[0003]Gas-turbines are known for being lightweight, reliable and requiring little maintenance compared to alternative work-producing motors, e.g. an internal combustion engine (ICE). Above all, gas-turbines are known for efficiently converting chemical energy stored in a combustible fuel to mechanical energy when working...

AI Technical Summary

Benefits of technology

[0017]Aspects of the invention relate to valves that allow simple and efficient varying of the pressure and power output of a gas-turbine, that in some embodiments is substantially continuous. Aspects of the invention relate to gas-turbines that are configured to efficiently operate in different pressure modes, allowing different power outputs at substantially similar efficiencies.

[0037]b) during inverse Brayton cycle operation of the gas-turbine, directing fluid from the compressor to the heat-exchanger cold-stream inlet through the conduit so that a portion of the fluid entering the heat-exchanger cold-stream inlet is from the compressor. As a result, inlet air is mixed with a portion of the oxygen-depleted exhaust from the compressor, decreasing oxygen content of the combustible mixture in the combustor, reducing the amount of NOx produced in the combustor and emitted by the gas-turbine.

Problems solved by technology

However, in spite of their potential, gas-turbines are currently not well known in applications requiring work-producing motors—for example ground vehicles such as cars and trucks—for several reasons.

One reason is that a given gas-turbine may generate a certain power at high efficiency for a prescribed load, but is less efficient at part load, particularly if turbine speed is maintained.

Thus, if turbine speed is reduced when power demand is low, a sudden increased power demand can be met only after a noticeable time lag.

A third reason is that the lifetime of gas-turbines is severely limited by startup / shutdown events.

Unlike an ICE, it is not practical to shut down a gas-turbine when idling.

A fourth reason is that the power requirements for many applications, e.g. ground vehicles, are low compared to the power gas-turbines efficiently produce.

Although large gas-turbines are relatively efficient, the efficiency of a gas-turbine decreases with smaller size (less than 300 kW) for various reasons including leakage around the periphery of the turbine which is increasingly significant with smaller turbine size.

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