TURBINE COMPONENT COOLING AND COOLANT TEMPERATURE EXCHANGE USING NITROGEN
Publication Date: 2013-Jun-06
The IP.com Prior Art Database
The present invention relates to a cooled cooling air (CCA) system of a gas turbine that comprises a compressor, combustion, heat exchanger and turbine systems. A nitrogen source feeds the nitrogen into the combustion system at or above gas turbine compressor discharge pressure, but at a lower temperature, thereby cools down compressor discharge air or compressor mid-stage extraction air, to cool hot components in the turbine section or combustor section. The heat exchange system is introduced between the compressor air and the nitrogen being injected into the main combustion feed helps to re-inject the cooled air into the turbine and to inject the nitrogen into the combustion system.
The present invention relates generally to gas turbine cycles, and more particularly to gas turbine cycles employing a cooled cooling air (CCA) system for cooling hot compressor air extracted for cooling turbine or combustor parts.
In general, a gas turbine comprises a compressor, combustion and turbine systems. Gas turbine systems are typically used to generate electrical energy. To increase the performance of the gas turbine and thus to achieve increased possible degree of efficiency, efforts are made to achieve a particularly high temperature of the working substance on inlet side of the turbine (for example, 1200° C. to 1500° C).
However, such elevated turbine inlet temperatures can lead to material problems, in particular in relation to heat resistance of the turbine components such as, blades and vanes. As a result, to increase the efficiency of gas turbine cycles especially in modern increased efficiency gas turbine cycles, hot compressor air is extracted for cooling any hot components in the turbine section or combustor section.
Conversely, reliability concerns, control difficulty and the high cost of current cooled cooling air (CCA) systems have made it obvious that there is a need for an improved CCA system design.
It would be desirable to have a simple and effective cooling method for the gas turbine parts with efficient use of cooling air.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a process of efficient use of cooling air for gas turbine component cooling in accordance with the present invention.
The present invention could apply to gas turbines that employ a cooled cooling air (CCA) system for cooling hot compressor air extracted for cooling turbine or combustor parts. The invention described herein proposes to use nitrogen available from an integrated gasification combined cycle (IGCC) process (i.e., nitrogen source) to cool compressor discharge air that can be used to cool any section of the turbine. As in the IGCC application, nitrogen is produced from an air separation unit and available as diluent injection in gas turbine to reduce mono-nitrogen oxide (NOx) emissions.
The nitrogen is compressed to a pressure level that is comparable to ga...