Gas turbine suction air-cooling system

A gas turbine suction air cooling system includes a gas turbine, a suction air cooler for cooling the outside air to be drawn into the gas turbine, an air-cooling coil for feeding chilled water so as to cool the outside air drawn into the suction air cooler, and absorption chillers for feeding the chilled water to the air-cooling coil. The air-cooling coil is divided into a plurality of coil lines, and the air-cooling coil, disposed closest to the outside air, is connected to the absorption chiller for feeding the chilled water of highest temperature, and the other air-cooling coil, disposed closest to the gas turbine, is connected to the absorption chiller for feeding the chilled water of lowest temperature. The system having such as a construction can be made small in size and high in efficiency.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 This invention relates to a gas turbine suction air-cooling system for
 cooling the air to be drawn into a gas turbine.
 2. Description of the Related Art
 Generally, a gas turbine suction air-cooling coil is formed as a single
 line, and therefore chilled water of a single temperature is supplied to
 the suction air-cooling coil so as to cool the suction air.
 Such a construction is disclosed, for example, in Japanese Patent
 Unexamined Publication No. 2-78736.
 Recently, in view of an advantage that waste heat of a gas turbine can be
 used as a drive source, countermeasures for dealing with a power
 consumption peak in the summer season, and the protection of the earth
 environment, absorption chillers have been more and more used as a source
 of supply of chilled water for cooling suction air in order to enhance the
 efficiency of the gas turbine. However, an absorption chiller uses water
 as a heating medium therein, and the operation in the chiller is effected
 at a pressure below the atmospheric pressure, and therefore, generally,
 the absorption chiller is larger in size than a mechanical-type chiller,
 and therefore has been required to be formed into a compact design, and
 also a higher efficiency of the overall system has been required.
 Furthermore, an air cooler itself has been eagerly required to have a
 compact design.
 SUMMARY OF THE INVENTION
 It is an object of this invention to provide a gas turbine suction air
 cooling system which has a compact design, and achieves a high efficiency.
 According to one aspect of the present invention, there is provided a gas
 turbine suction air cooling system comprising a gas turbine, a suction air
 cooler for cooling the outside air to be drawn into the gas turbine, an
 air-cooling coil for feeding chilled water so as to cool the outside air
 drawn into the suction air cooler, and absorption chillers for feeding the
 chilled water to the air-cooling coil; in which
 the air-cooling coil is divided into a plurality of coil lines; and the
 air-cooling coil line, disposed closest to the outside air, is connected
 to the absorption chiller for feeding the chilled water of highest
 temperature, whereas the other air-cooling coil line, disposed closest to
 the gas turbine, is connected to that absorption chiller for feeding the
 chilled water of lowest temperature.
 According to another aspect of the invention, there is provided a gas
 turbine suction air cooling system comprising a gas turbine, a suction air
 cooler for cooling the outside air to be drawn into the gas turbine, an
 air-cooling coil for feeding chilled water so as to cool the outside air
 drawn into the suction air cooler, absorption chillers for feeding the
 chilled water to the air-cooling coil, and means for feeding chilled water
 to absorbers and condensers of the absorption chillers; in which
 the air-cooling coil is divided into a plurality of air-cooling coil lines;
 and the air-cooling coil line, disposed closest to the outside air, is
 connected to the absorption chiller for feeding the chilled water of
 highest temperature, whereas the other air-cooling coil line, disposed
 closest to the gas turbine, is connected to that absorption chiller for
 feeding the chilled water of lowest temperature; and the chilled water is
 caused to flow in series to the absorption chiller for feeding the chilled
 water of the lowest temperature and the absorption chiller for feeding the
 chilled water of the highest temperature.
 According to a further aspect of the invention, there is provided a gas
 turbine suction air cooling system comprising a gas turbine, a suction air
 cooler for cooling the outside air to be drawn into the gas turbine, an
 air-cooling coil for feeding chilled water so as to cool the outside air
 drawn into the suction air cooler, absorption chillers for feeding the
 chilled water to the air-cooling coil, and means for feeding chilled water
 to absorbers and condensers of the absorption chillers; in which
 the air-cooling coil is divided into a plurality of air-cooling coil lines;
 and the air-cooling coil line, disposed closest to the outside air, is
 connected to that absorption chiller for feeding the chilled water of
 highest temperature, whereas the other air-cooling coil line, disposed
 closest to the gas turbine, is connected to the absorption chiller for
 feeding the chilled water of lowest temperature; and the chilled water is
 caused to flow in parallel to the absorption chiller for feeding the
 chilled water of the lowest temperature and the absorption chiller for
 feeding the chilled water of the highest temperature.
 With the above construction, the following operation is achieved.
 The gas turbine suction air-cooling coil is divided into a plurality of
 (for example, two) coil lines, and the absorption chiller for supplying
 higher-temperature cooling chilled water (for example, of 9.degree. C.) is
 connected to the coil line disposed close to the outside air, whereas the
 absorption chiller for supplying lower-temperature cooling chilled water
 (for example, of 6.degree. C.) is connected to the coil line disposed
 close to the suction air of the gas turbine. With this construction, an
 evaporation temperature within an evaporator of the absorption chiller
 (which feeds the higher-temperature chilled water), connected to the coil
 line disposed close to the outside air, is higher than an evaporation
 temperature of an evaporator of the absorption chiller (which feeds the
 lower-temperature chilled water) connected to the coil line disposed close
 to the suction air of the gas turbine, and therefore a temperature
 difference, required for absorbing heat, is smaller in the former
 absorption chiller. Therefore, the former absorption chiller can be made
 smaller in size and higher in efficiency than the latter absorption
 chiller connected to the coil disposed close to the suction air of the gas
 turbine.
 The suction air-cooling coil is divided into a plurality of coil lines, and
 the cooling chilled water of higher temperature is fed to the coil line
 disposed at the air inlet side (i.e, the higher-temperature side) whereas
 the cooling chilled water of lower temperature is fed to the coil line
 disposed at the air outlet side (i.e., the lower-temperature side), and by
 doing so, the heat exchange between the air and the cooling chilled water
 can be effected in a counterflow manner, and therefore the overall
 construction of the cooling coil can be made small.
 In the present invention, a predetermined amount of air is cooled to a
 predetermined temperature, using the suction air-cooling coil and the
 chiller each of which is divided into not less than two, and with this
 construction, the suction air cooling system of the invention can be
 reduced in overall construction, and can achieve a higher efficiency as
 compared with the type of system in which one coil and one chiller are
 used.

DESCRIPTION OF THE PREFERRED EMBODIMENTS
 A first embodiment of the present invention will now be described with
 reference to FIGS. 1 and 2.
 FIG. 1 is an overall system diagram of a gas turbine suction air cooling
 system. Fuel 2 is supplied to a gas turbine 1, and the outside air
 (ambient air) 3 is drawn into a suction air cooler 4. The cooled air 5,
 decreased in temperature when passed through the suction air cooler 4,
 assists in the combustion of the fuel 2, and becomes combustion exhaust
 gas 6. An internal coil of the suction air cooler 4 is divided into two
 lines, i.e., two coils, and an absorption chiller 11 for supplying
 higher-temperature cooling chilled water 9, for example, of 9.degree. C.
 is connected to the coil 7 disposed close to the outside air 3, whereas an
 absorption chiller 12 for supplying lower-temperature cooling chilled
 water 10, for example, of 6.degree. C. is connected to the coil 8 disposed
 close to the suction air 5 of the gas turbine.
 The exhaust gas 6 from the gas turbine 1 is fed to a waste heat boiler 13,
 and steam 14, produced in the boiler 13, is used as a drive source for the
 absorption chillers 11 and 12.
 FIG. 2 shows temperature conditions within the suction air cooler 4 and the
 absorption chillers 11 and 12.
 The coil within the suction air cooler 4 is divided into the two lines, and
 by doing so, the heat exchange between the air and the cooling chilled
 water is effected in a counterflow manner, and the overall construction of
 the coil can be made small. And besides, an evaporation temperature within
 an evaporator of the absorption chiller 11, connected to the coil 7
 disposed close to the outside air 3, is higher than an evaporation
 temperature 16 in an evaporator of the absorption chiller 12 connected to
 the coil 8 disposed close to the suction air 5 of the gas turbine 1, and
 therefore a temperature difference, required for absorbing heat, is
 smaller in the chiller 11. Therefore, the overall size of the chiller can
 be made small, and the efficiency thereof can be further enhanced.
 Next, a second embodiment of the invention will be described with reference
 to FIGS. 3 and 4.
 FIG. 3 is an overall system diagram of a gas turbine suction air cooling
 system. Fuel 2 is supplied to a gas turbine 1, and the outside air 3 is
 drawn into a suction air cooler 4. The cooled air 5, decreased in
 temperature when passed through the suction air cooler 4, assists in the
 combustion of the fuel 2, and becomes combustion exhaust gas 6. An
 internal coil of the suction air cooler 4 is divided into two lines, and
 an absorption chiller 11 for supplying higher-temperature cooling chilled
 water 9, for example, of 9.degree. C. is connected to the coil 7 disposed
 close to the outside air 3, whereas an absorption chiller 12 for supplying
 lower-temperature cooling chilled water 10, for example, of 6.degree. C.
 is connected to the coil 8 disposed close to the suction air 5 of the gas
 turbine.
 The exhaust gas 6 from the gas turbine 1 is fed to a waste heat boiler 13,
 and steam 14, produced in the boiler 13, is used as a drive source for the
 absorption chillers 11 and 12. Cooling water 21 for the chillers,
 decreased in temperature when passed through a cooling tower 20, is first
 fed to the absorption chiller 12 for supplying the cooling chilled water
 10 of 6.degree. C., and then is fed to the absorption chiller 11 for
 supplying the cooling chilled water 9 of 9.degree. C.
 FIG. 4 shows temperature conditions within the suction air cooler 4 and the
 absorption chillers 11 and 12.
 The coil within the suction air cooler 4 is divided into the two lines, and
 by doing so, the heat exchange between the air and the chilled water is
 effected in a counterflow manner, and therefore the overall construction
 of the coil can be made small. And besides, the air-cooling chilled water
 9 and the air-cooling chilled water 10, supplied respectively from the
 absorption chillers 11 and 12 connected respectively to the coils 7 and 8
 disposed close respectively to the outside air 3 and the suction air 5 of
 the gas turbine, are combined with the chilled water 21 for the chillers
 in a counterflow manner, and with this construction, a temperature
 difference between an evaporation temperature 15 and a condensation
 temperature 22 in the absorption chiller 11 is equal to a temperature
 difference between an evaporation temperature 16 and a condensation
 temperature 23 in the absorption chiller 12, and the heat exchange can be
 effected without any waste. Therefore, the overall size of the chiller can
 be made small, and the efficiency thereof can be further enhanced.
 Next, a third embodiment of the invention will be described with reference
 to FIGS. 5 and 6.
 FIG. 5 is an overall system diagram of a gas turbine suction air cooling
 system. Fuel 2 is supplied to a gas turbine 1, and the outside air 3 is
 drawn into a suction air cooler 4. The cooled air 5, decreased in
 temperature when passed through the suction air cooler 4, assists in the
 combustion of the fuel 2, and becomes combustion exhaust gas 6. An
 internal coil of the suction air cooler 4 is divided into two lines or
 circuits, and an absorption chiller 11 for supplying higher-temperature
 cooling chilled water 9, for example, of 9.degree. C. is connected to the
 coil 7 disposed close to the outside air 3, whereas an absorption chiller
 12 for supplying lower-temperature cooling chilled water 10, for example,
 of 6.degree. C. is connected to the coil 8 disposed close to the suction
 air 5 of the gas turbine.
 The exhaust gas 6 from the gas turbine 1 is fed to a waste heat boiler 13,
 and steam 14, produced in the boiler 13, is used as a drive source for the
 absorption chillers 11 and 12. Cooling water 21 for the chillers,
 decreased in temperature when passed through a cooling tower 20, is fed in
 parallel to the two absorption chillers 1 and 12.
 FIG. 6 shows temperature conditions within the suction air cooler 4 and the
 absorption chillers 11 and 12.
 The coil within the suction air cooler 4 is divided into the two lines, and
 by doing so, the heat exchange between the air and the chilled water is
 effected in a counterflow manner, and therefore the overall construction
 of the coil can be made small. And besides, a temperature difference
 between an evaporation temperature 15 and a condensation temperature 22 in
 the absorption chiller 11, connected to the coil 7 disposed close to the
 outside air 5, is smaller than a temperature difference between an
 evaporation temperature 16 and a condensation temperature 23 in the
 absorption chiller 12 connected to the coil 8 disposed close to the
 suction air 5 of the gas turbine 1, and therefore the efficiency is
 enhanced.
 FIG. 7 is an overall system diagram of a gas turbine suction air cooling
 system incorporating dual-effect absorption chillers. A line for supplying
 fuel 51, a line for feeding cooled air 54 which is decreased in
 temperature when passed through a suction air cooler 53, and a line for
 feeding combustion exhaust gas 55 are connected to a gas turbine 50.
 An internal coil of the suction air cooler 53 is divided into two lines,
 and cooling chilled water 58, cooled, for example, to 9.degree. C. by an
 evaporator 57a of an absorption chiller 57, is supplied by a pump 59 to
 the coil 56 disposed close to the outside air 52, and this cooling chilled
 water 58, when passing through the coil 56, absorbs heat from the outside
 air to be increased in temperature, and then is returned to the absorption
 chiller 57.
 On the other hand, cooling chilled water 62, cooled, for example, to
 6.degree. C. by an evaporator 61a of an absorption chiller 61, is supplied
 by a pump 63 to the coil 60 disposed close to the suction air 54 of the
 gas turbine, and this cooling chilled water 62, when passing through the
 coil 60, absorbs heat from the outside air to be increased in temperature,
 and then is returned to the absorption chiller 61.
 The exhaust gas 55 from the gas turbine 50 is fed to a waste heat boiler
 64, and steam 65, produced in this boiler 64, is supplied to a
 high-temperature generator 57b of the absorption chiller 57 and a
 high-temperature generator 61b of the absorption chiller 61, and is
 condensed into drain water 66 in the high-temperature generators 57b and
 61b, and is returned to the boiler 64 by a pump 67.
 Cooling water 69 for the chillers, cooled in a cooling tower 68, is
 supplied by a pump 70 to an absorber 57c and a condenser 57d of the
 absorption chiller 57 and to an absorber 61c and a condenser 61d of the
 absorption chiller 61, and absorbs heat from the chillers to be increased
 in temperature, and then is returned to the cooling tower 68.
 In this embodiment, the suction air cooler can be reduced into a small
 size, and therefore, the absorption chillers for supplying the cooling
 chilled water to the suction air cooler can be reduced into a small size.
 And besides, the high efficiency of the absorption chillers can be
 achieved.
 Furthermore, the chiller for supplying the cooling chilled water to the
 suction air cooler is divided into a plurality of lines, and even if one
 of the chillers is subjected to malfunction, the air-cooling ability will
 not be totally lost.
 Furthermore, one of the chillers can be selectively operated depending on
 the temperature of the outside air, and by doing so, the system can be
 operated, using a half of the power required for operating the auxiliary
 apparatus of the chillers.