Patent Publication Number: US-2015075133-A1

Title: Gas turbine engine system that uses organic medium

Description:
CROSS REFERENCE TO THE RELATED APPLICATION 
     This application is based on and claims Convention priority to Japanese patent application No. 2012-086210, filed Apr. 5, 2012, the entire disclosure of which is herein incorporated by reference as a part of this application. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a complex gas turbine engine system equipped with an organic Rankine cycle engine which uses organic substance as a working medium. 
     2. Description of Related Art 
     In recent years, as a solution to the environment problems or the energy problems, a distributed energy supply system has been proposed in which relatively small power plants are installed near electric power consumers and supply electric power. As one power source which is part of the distributed energy supply system, use of a middle-sized or small-sized gas turbine engine has been suggested (e.g., Patent Document 1). For a distributed power source, it is particularly an important issue to improve the efficiency. 
     PRIOR ART DOCUMENT 
     Patent Document 
     [Patent Document 1] JP Laid-open Patent Publication No. 2007-159225 
     SUMMARY OF THE INVENTION 
     However, as a method for improving the efficiency of a middle-sized or small-sized gas turbine, increasing of a temperature or increasing of a pressure ratio is difficult due to restrictions in size. In addition, conventionally, a regenerative cycle in which exhaust heat from a gas turbine is used for preheating a working gas is established, or a cogeneration system using exhaust heat from a gas turbine as a heat source for a steam turbine is established, thereby comprehensively improving the efficiency of the entire system. However, it is very difficult to further increase the efficiency by developing an engine with a low pressure ratio suitable for a regenerative cycle or developing a low-output and high-efficient steam turbine for use in a cogeneration system. 
     Therefore, in order to solve the above-described problems, an object of the present invention is to provide a combined-type gas turbine engine system which achieves high efficiency by very effectively utilizing heat from a gas turbine engine. 
     In order to achieve the above-described object, a gas turbine engine system according to the present invention includes: a compressor configured to compress a first working medium; a heater configured to heat the compressed first working medium utilizing an external heat source; a turbine configured to output power from the first working medium; an intermediate cooler provided at the compressor and configured to cool the first working medium compressed by a low-pressure compression part of the compressor and supply the first working medium to a high-pressure compression part of the compressor; and an organic Rankine cycle engine using, as a second working medium, an organic substance which serves as a cooling medium of the intermediate cooler. 
     With this configuration, by using a low-boiling-point organic substance as the working medium of the Rankine cycle engine combined with a gas turbine engine, it is possible to effectively use the heat of the relatively-low-temperature working medium passing through the compressor, and thus it is possible to obtain very high efficiency for the entire engine system. 
     In one embodiment of the present invention, the gas turbine engine system may further include: a heat exchanger provided on a discharge path for discharging the first working medium discharged from the turbine, the heat exchanger using, as a heating medium, the first working medium discharged from the turbine; and an organic Rankine cycle engine using, as a third working medium, an organic substance which serves as a heat receiving medium of the heat exchanger. With this configuration, the organic media are used, and not only the heat of the working medium passing through the compressor but also the heat of the working medium discharged from the turbine are used to output power, and thus it is possible to obtain further high efficiency for the entire engine system. 
     In one embodiment of the present invention, as the heater, a solar heater configured to heat the first working medium utilizing sunlight as a heat source may be provided. With this configuration, it is possible to increase the efficiency of the engine system while suppressing a load on the environment by using sunlight which is natural energy. 
     Any combination of at least two constructions, disclosed in the appended claims and/or the specification and/or the accompanying drawings should be construed as included within the scope of the present invention. In particular, any combination of two or more of the appended claims should be equally construed as included within the scope of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In any event, the present invention will become more clearly understood from the following description of embodiments thereof, when taken in conjunction with the accompanying drawings. However, the embodiments and the drawings are given only for the purpose of illustration and explanation, and are not to be taken as limiting the scope of the present invention in any way whatsoever, which scope is to be determined by the appended claims. In the accompanying drawings, like reference numerals are used to denote like parts throughout the several views, and: 
         FIG. 1  is a block diagram showing a schematic configuration of a gas turbine engine system according to an embodiment of the present invention; and 
         FIG. 2  is a block diagram showing a modification of the gas turbine engine system in  FIG. 1 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments of the present invention will be described with reference to the drawings.  FIG. 1  is a schematic configuration diagram showing a gas turbine engine system (hereinafter, referred to simply as “engine system”) E according to an embodiment of the present invention. The engine system E includes three engine units, namely, a gas turbine engine unit GU, a first Rankine cycle engine unit RU 1 , and a second Rankine cycle engine unit RU 2 , and those engine units GU, RU 1 , RU 2  drive respective loads such as generators GE 1 , GE 2 , GE 3 . 
     The gas turbine engine unit GU includes a compressor  1  which compresses a first working medium M 1 , a combustor  3  which is a heater for heating the first working medium M 1  compressed by the compressor  1 , and a first turbine  5  which outputs power from the combusted first working medium M 1 . In the present embodiment, an air may be used as the first working medium M 1 . 
     The compressor  1  includes a low-pressure compression part  1   a  and a high-pressure compression part  1   b , and is provided with an intermediate cooler  9  arranged between the low-pressure compression part  1   a  and the high-pressure compression part  1   b.  By cooling the first working medium M 1 , compressed by the low-pressure compression part  1   a,  with the intermediate cooler  9 , compression work of the high-pressure compression part  1   b  is reduced, and the efficiency is improved. The high-pressure first working medium M 1  discharged from the compressor  1  passes through a regenerative heat exchanger  13  and then is sent to the combustor  3 . The regenerative heat exchanger  13  preheats the first working medium M 1  flowing from the compressor  1  toward the combustor  3  by using the heat of the high-temperature first working medium M 1  discharged from the first turbine  5 . 
     A heat exchanger  15  is further provided on a downstream of the regenerative heat exchanger  13  on a discharge path  11  which discharges the first working medium M 1  discharged from the first turbine  5  to the outside. The first working medium M 1  discharged from the regenerative heat exchanger  13  passes through the heat exchanger  15  as a heating medium and then is discharged to the outside. 
     In the first Rankine cycle engine unit RU 1 , a second turbine  17  is driven by a second working medium M 2  which has been heated into a gaseous state utilizing, as a heat source, the heat of the first working medium M 1  passing through the intermediate cooler  9 , and power is outputted through the second turbine  17 . The second working medium M 2  discharged from the second turbine  17  is condensed by a first condenser  19  and then is supplied to the intermediate cooler  9  and the second turbine  17  again. 
     The first Rankine cycle engine unit RU 1  is configured as an organic Rankine cycle engine using an organic substance as the second working medium M 2 . In particular, the temperature of the first working medium M 1  that is being compressed in the compressor  1  is about 100° C. to 200° C., which is relatively low, thus an organic medium having a low boiling point may be used as the second working medium M 2 . In this example, a fluorocarbon-based organic medium, for example, HFC-134a, HFC-245fa, HFC-365mfc, or the like, may be used. 
     In the second Rankine cycle engine unit RU 2 , a third turbine  21  is driven by a third working medium M 3  which has been heated utilizing, as a heat source, the heat of the first working medium M 1  passing through the heat exchanger  15  as a heating medium as described above, and power is outputted through the third turbine  21 . The third working medium M 3  discharged from the third turbine  21  is condensed by a second condenser  23  and then is supplied to the heat exchanger  15  and the third turbine  21  again. 
     The second Rankine cycle engine unit RU 2  is also configured as an organic Rankine cycle engine using an organic substance as the third working medium M 3 . The first working medium M 1 , which is an exhaust gas discharged from the first turbine  5 , is kept at a relatively high temperature of about 200° C. to 300° C. even after passing through the regenerative heat exchanger  13 , thus it is possible to use an organic medium having a higher boiling point than that of the second working medium M 2 . In this example, a petroleum-based organic medium, for example, butane or pentane, may be used. 
     The second Rankine cycle engine unit RU 2  may be configured as an ordinary steam turbine using water as the third working medium M 3 . Alternatively, the second Rankine cycle engine unit RU 2  may be omitted, but the organic media are used as in the present embodiment, not only the heat of the first working medium M 1  passing through the compressor  1  but also the heat of the first working medium M 1  discharged from the first turbine  5  are used to output power, and thus it is possible to obtain further high efficiency for the entire engine system E. 
     In addition, as a modification of the present embodiment, as shown in  FIG. 2 , a solar heater  31  which uses sunlight SL as a heat source may be additionally provided at the upstream side of the combustor  3  as a heater which heats the first working medium M 1  compressed by the compressor  1 . By providing such a configuration and heating the first working medium M 1  again by using the sunlight SL which is natural energy, the efficiency of the engine system E is further improved. 
     As described above, in the engine system E according to the present embodiment, since the organic substance having a low boiling point is used as the working medium M 2  of the Rankine cycle engine (in particular, the first Rankine cycle engine RU 1 ) combined with the gas turbine engine unit GU, it is possible to effectively use the heat of the relatively-low-temperature working medium passing through the compressor  1 , and thus it is possible to obtain very high efficiency for the entire engine system E. 
     Although the present invention has been described above in connection with the embodiments thereof with reference to the accompanying drawings, numerous additions, changes, or deletions can be made without departing from the gist of the present invention. Accordingly, such additions, changes, or deletions are to be construed as included in the scope of the present invention. 
     REFERENCE NUMERALS 
     
         
           1  . . . Compressor 
           3  . . . Combustor (heater) 
           5  . . . First turbine 
           9  . . . Intermediate cooler 
           13  . . . Regenerative heat exchanger 
           15  . . . Heat exchanger 
           31  . . . Solar heater 
         E . . . Gas turbine engine system 
         GU . . . Gas turbine engine unit 
         RU 1  . . . First Rankine cycle engine unit 
         RU 2  . . . Second Rankine cycle engine unit 
         M 1  . . . First working medium 
         M 2  . . . Second working medium 
         M 3  . . . Third working medium