United States Patent [191
`Prochaska et a1.
`
`1111111111llllillllllllllllllll
`USOO5083423A
`[11] Patent Number:
`5,083,423
`[45] Date of Patent:
`Jan. 28, 1992
`
`[54]
`
`APPARATUS AND METHOD FOR
`OPTIMIZING THE AIR INLET
`TEMPERATURE OF GAS TURBINES
`
`1751
`
`Inventors:
`
`[73]
`
`Assignee:
`
`121]
`122]
`
`Appl. No.:
`Filed:
`
`James K. Prochaska, Houston; Mark
`H. Axford, Katy, both of Tex.
`Stewart & Stevenson Services, Inc.,
`West Houston, Tex.
`514,743
`Apr. 26, 1990
`
`[62]
`
`Related US. Application Data
`Division of Ser. No. 295,869, Jan. 11, 1989, Pat. No.
`4,951,460.
`
`[51]
`152]
`[58]
`
`[561
`
`.... .. W2C 7/08
`Int. Cl.5 ............................... .. .
`US. Cl. ............................................. .. Gil/39.02
`Field of Search ............. .. 60/3902, 39.07, 39.161,
`60/39.!82, 39.511, 39.52, 266, 267
`References Cited
`U.S. PATENT DOCUMENTS
`2,312,605 12/1939
`2,625,012 1/19_53
`3,150,487 9/1964
`3,418,806 12/1968
`3,422,811) 1/1969
`
`Wagner et a1. ................ .. 60/39.511
`La Haye .......................... .. 60/39.07
`
`3,609,967 10/1971 Waldman ....................... .. 60/39.511
`3,703,807 11/1972 Rice ......... ..
`(SO/39.182
`3,785,145 l/l974 Amann ..... ..
`60/39.5l1
`4,418,527 12/1983 Schlom et a]. ................... .. 60/3905
`
`FOREIGN PATENT DOCUMENTS
`3002615 6/1981 Fed. Rep. of Germany 60/39.]82
`
`OTHER PUBLICATIONS
`Donaldson Company, Inc. Brochure, 1976.
`An Analysis of the Performance of a Gas Turbine Co—
`Generation Plant by .1. W. Baughn; Transactions of
`ASME, 1983.
`Tatge et a1, “Gas Turbine Air Inlet Treatment”, Gen
`eral Electric Co., 1980, pp. 21 and 24.
`Primary Examiner-Louis J. Casaregola
`Attorney, Agent. or Firm—-A. Triantaphyllis
`[57]
`ABSTRACT
`A heat exchanger is disclosed for heating air entering a
`combustion gas turbine to increase the power output of
`the turbine when the turbine operates in a cold environ
`ment. The heat exchanger may be used also as a cooler
`to cool air entering the turbine to increase the power
`output of the turbine when the turbine operates in a hot
`environment.
`
`8 Claims, 2 Drawing Sheets
`
`28
`
`57
`
`40x42l 44 46 4a
`26
`-
`’
`/ ’
`
`PAGE 1 of 8
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`PETITIONER'S EXHIBIT 1231
`
`

`
`US. Patent
`
`Jan. 28, 1992
`
`Sheet 1 of 2
`
`5,083,423
`
`5 N o
`
`30
`
`40
`
`50
`
`6O
`
`70
`
`80
`
`90
`
`I00
`
`32000
`
`3! 000
`
`30000
`
`29000
`
`28000
`
`27000
`
`26000
`
`25000
`
`24000
`
`23000
`
`22000
`
`2| 000
`
`20000
`0
`
`25000
`
`24000
`
`23000
`
`22000
`
`2! 000
`
`20000
`
`19000
`
`[8000
`
`O
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`N O
`
`40
`
`60
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`80
`
`I00
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`F/G. 2
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`PAGE 2 of 8
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`PETITIONER'S EXHIBIT 1231
`
`

`
`US. Patent
`
`Jan. 28, 1992
`
`Sheet 2 of 2
`
`5,083,423
`
`54000
`53000
`52000
`51 000
`50000
`49000
`48000
`47000
`46000
`45000
`44000
`43000
`42000
`4l000
`40000
`39000
`
`F/GZ
`
`28
`
`57
`
`42 44 45
`4o‘ 2
`I
`I [48
`26
`
`I
`
`F/G. 4
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`PAGE 3 of 8
`
`PETITIONER'S EXHIBIT 1231
`
`

`
`1
`
`5,083,423
`
`APPARATUS AND METHOD FOR OPTIMIZING
`THE AIR INLET TEMPERATURE OF GAS
`TURBINES
`
`This is a divisional of copending application Ser. No.
`07/295,869, ?led on Jan. 11, 1989, now US. Pat. No.
`4,951,460.
`TECHNICAL FIELD OF THE INVENTION
`The present invention relates to the ?eld of combus
`tion gas turbines, and more particularly, to a method
`and an apparatus for optimizing the inlet temperature of
`the air ?owing to a combustion gas turbine to improve
`the performance thereof. Still more particularly, the
`present invention discloses a method and an apparatus
`for raising the inlet temperature of the air when the
`ambient temperature is low to increase the power out
`put of the combustion gas turbine in a cold environ
`ment. The apparatus may be used, not only as a heater
`to raise the inlet temperature of the air when the turbine
`is operated under cold conditions, but also, it may be
`used as a cooler to decrease the inlet temperature of the
`air to increase the power output of the turbine when the
`turbine is operated under hot conditions. Furthermore,
`the apparatus may be used in connection with a gas
`turbine as a heater only together with a separate cooler,
`the heater being placed into operation when the ambi
`ent temperature is low and the cooler being placed into
`operation when the ambient temperature is high.
`
`5
`
`10
`
`20
`
`25
`
`40
`
`45
`
`50
`
`35
`
`BACKGROUND OF THE INVENTION
`Combustion gas turbines are well known in the art. In
`general, those turbines include a compression section
`for compressing air entering the turbine, a combustion
`section following the compression section where the
`compressed air is combusted with fuel, and an expan
`sion section, following the combustion section, where
`the combustion mixture from the combustion section is
`expanded to generate shaft work. The shaft work is
`transferred to an outside user that utilizes such shaft
`work. In many applications, the shaft work is trans
`ferred to an electrical generator that transforms the
`shaft work to electricity. The hot exhaust from the
`expansion section flows to a waste heat recovery unit
`where heat is recovered by generating steam or by
`providing heat to other media or heat utilizers.
`Combustion gas turbines are constructed as single,
`double or triple shaft turbines. Single shaft turbines
`include only one shaft utilized by both compression and
`expansion section at the same speed. A double shaft
`turbine includes two shafts, one shaft transferring work
`from the expansion section to the compression section
`and another shaft transferring work from the expansion
`section to a driven load. A triple shaft turbine includes
`one shaft transferring work from the expansion section
`to a portion of the compression section, a second shaft
`transferring work from the expansion section to another
`portion of the compression section, and a third shaft
`transferring work from the expansion section to the
`driven load. Although, single shaft turbines were used
`more often to generate work in the past, the use of
`double and triple shaft turbines has recently increased.
`Several factors affect the performance and the work
`output generated by combustion gas turbines. One
`65
`major factor is the inlet temperature of the air entering
`the compression stage of the turbine. Its effect on the
`power output of the gas turbine depends on the number
`
`60
`
`2
`of shafts of said turbine. In single shaft turbines, the
`output increases in a substantially linear fashion until it
`reaches a plateau as the inlet air temperature decreases.
`This correlation results from the fact that as the inlet
`temperature decreases, the density of the air increases
`whereby a larger mass of air flows through the turbine
`to generate an increased amount of work. FIG. 1 shows
`the above correlation of electricity generated versus
`inlet temperature of air for a single shaft combustion gas
`turbine operating with natural gas fuel at sea level, sixty
`(60) percent relative humidity, 60 hz, inlet loss of 4
`inches of H20, exhaust loss of 10 inches of H20, and
`with no steam or water injection for control of nitrogen
`oxides emissions. The abscissa shows the inlet tempera
`ture of the combustion air in degrees Fahrenheit ('F.)
`and the ordinate shows the output at the generator
`terminals in kilowatts (kw).
`In multi-shaft, i.e., double or triple shaft gas turbines,
`the correlation between output and inlet air temperature
`is different in that although the output increases as the
`air inlet temperature decreases in a particular tempera
`ture range, the output reaches a maximum at the lowest
`point of that range and decreases as the temperature
`decreases below that point. Referring now to FIG. 2,
`there is shown a graph depicting the correlation be
`tween electrical output versus air inlet temperature of a
`double shaft General Electric LM2500 gas turbine gen
`erating electricity and operating with natural gas fuel at
`sea level, sixty (60) percent relative humidity, 60 hz,
`inlet loss of 4 inches of H20, exhaust loss of 10 inches of
`H20, and with water injection for control of nitrogen
`oxides emissions, the amount of the water being suffi
`cient to meet the typical regulatory emission require
`ments of nitrogen oxides of about 42 parts per million on
`a dry basis. The abscissa shows the inlet temperature of
`the combustion air in degrees Fahrenheit (°F.), and the
`ordinate shows the output at the generator terminals in
`kilowatts (kw). FIG. 2 shows that the electrical output
`increases from about 18,500 kilowatts to about 24,300
`kilowatts as the inlet temperature of the air decreases
`from 100° F. to 35° F. As the temperature decreases
`below 35° F., the electrical output decreases with such
`temperature decrease. Therefore, it appears from FIG.
`2 that the most desirable air inlet temperature for that
`particular turbine is about 35° F.
`Triple shaft gas turbines have a similar maximum
`electrical output achieved at a particular air inlet tem
`perature. Referring now to FIG. 3, there is shown a
`graph depicting the correlation between electrical out
`put and inlet temperature of air in a triple shaft General
`Electric LM5000 gas turbine generating electricity and
`operating with natural gas fuel at sea level, sixty (60)
`percent relative humidity, 60 hz, inlet loss of 4 inches of
`H20, exhaust loss of 10 inches of H20, with steam injec
`tion for control of oxides of nitrogen emissions (about
`42 parts per million on a dry basis), and additional steam
`injection for power augmentation. The abscissa shows
`the inlet temperature of the combustion air in degrees
`Fahrenheit (°F.), and the ordinate shows the output at
`the generator terminals in kilowatts (kw). There is
`shown that the electrical output increases from about
`39,500 kilowatts to about 53,000 kilowatts as the tem
`perature decreases from 100° F. to 40° F. The electrical
`output starts decreasing beyond that point (40° F.) as
`the inlet temperature of the air decreases. Therefore, it
`is apparent that it is desirable to operate the gas turbine
`with an air inlet temperature of about 40° F.
`
`PAGE 4 of 8
`
`PETITIONER'S EXHIBIT 1231
`
`

`
`5,083,423
`4
`3
`In the past, because gas turbines have been more
`cooling source also utilizes steam available in the cogen
`commonly used to generate power in hot climates, only
`eration plant. Other heating and cooling sources may
`coolers have been used to decrease the inlet tempera
`also be utilized depending on the energy availability in
`the particular operation.
`ture of the air to increase the power output. Heaters
`have not been used to increase the air inlet temperature
`BRIEF DESCRIPTION OF THE DRAWINGS
`towards the optimum air inlet temperature, a demon
`strated by the above graphs, to increase the power out
`For a detailed description of the embodiments of the
`put towards its maximum. As a result, the multishaft gas
`apparatus and the method of the present invention,
`turbines previously used in cold environments did not
`reference will now be made to the accompanying draw
`ings wherein:
`produce the maximum output achievable by those tur
`bines.
`FIG. 1 is a graph showing the electrical output of a
`typical single shaft gas turbine generating electricity in
`According to the present invention, a method and an
`apparatus are disclosed to increase the inlet temperature
`kilowatts (kw) as a function of the inlet temperature of
`of the air in cold climates to obtain the optimum air inlet
`the combustion air ?owing to such turbine in degrees
`temperature by heating the air in a heater. The heater
`Fahrenheit (°F.);
`may be the same apparatus that is used to cool the air to
`FIG. 2 is a graph showing the electrical output of a
`reach the optimum air inlet temperature when the ambi
`double shaft gas turbine (General Electric LM-ZSOO)
`ent temperature is high due to hot weather conditions.
`generating electricity in kilowatts (kw) as a function of
`In those instances, the apparatus is sometimes referred
`the inlet temperature of the combustion air entering
`such turbine in degrees Fahrenheit (°F.);
`to herein as the heater/cooler. The heater may also be a
`separate apparatus which is operated only during the
`FIG. 3 is a graph showing the performance of a triple
`cold periods while a separate cooling apparatus is used
`shaft gas turbine (General Electric LM-SOOO) generat
`alone during the hot periods.
`ing electricity in kilowatts (kw) as a function of the inlet
`Another problem encountered in the past in cold
`temperature of the combustion air entering such turbine
`climates has been the formation of ice at the inlet of the
`in degrees Fahrenheit (°F.); and
`gas turbine caused by the condensation of water
`FIG. 4 is a ?ow sheet showing a cogeneration process
`thereon. The accumulation of such ice is oftentimes
`generating electrical power and steam and the method
`very rapid and causes plugging of the ?lter surface,
`and apparatus of the present invention wherein a heat
`possible engine damage from ice formed at the engine
`exchanger is used to heat the air entering the gas turbine
`bellmouth, and a total shutdown of the gas turbine. In
`when the ambient temperature is low and to cool the air
`the past, this problem has been addressed by ?owing
`entering the gas turbine when the ambient temperature
`is high.
`hot exhaust gases from the outlet of the turbine through
`a heat exchanger and over the inlet thereof to prevent
`such icing. One disadvantage of that method was that it
`required the addition of special equipment such as jack
`ets around the inlet. Another disadvantage was that the
`hot gases were available at substantially high tempera
`tures whereby they formed hot spots around the inlet of
`the turbine. Still another disadvantage was that the
`temperature at the inlet of the gas turbine could not be
`easily controlled. The addition of the heater disclosed
`by the present invention prevents the fonnation of ice at
`the inlet of the gas turbine while eliminating the prob
`lems of previous deicing techniques.
`These and other advantages of the present invention
`will become apparent from the following description
`and drawings.
`
`20
`
`15
`
`25
`
`30
`
`35
`
`40
`
`45
`
`SUMMARY OF THE INVENTION
`A method and an apparatus are disclosed for heating
`the air entering a multi-shaft gas turbine to increase the
`output of such turbine in cold climates. The heater may
`be the same apparatus used to cool the air to increase
`the output of the gas turbine when the turbine is oper
`ated in a hot ambient environment. Furthermore, the
`heater may be a separate apparatus which is used only
`for heating when the ambient temperature is low while
`a separate cooler is used to cool the air when the ambi
`ent temperature is high.
`In cogeneration plants i.e., when a combustion gas
`turbine is used to generate electricity and steam, steam
`is used to supply heat to a heating medium that ?ows to
`the heater to heat the air entering the gas turbine. When
`the heater is the same apparatus used also as a cooler
`when the ambient temperature is high, the heater/
`cooler is connected to a cooling source that provides
`cooling to a cooling medium passing therethrough
`when cooling, rather than heating, is required. The
`
`55
`
`60
`
`65
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENT
`The power output of a combustion gas turbine is a
`function of the temperature of the air ?owing into the
`turbine. In single shaft turbines, the power output of the
`turbine increases as the inlet air temperature decreases.
`In multishaft combustion gas turbines, the power output
`thereof increases as the air inlet temperature decreases
`but only over a certain temperature range. The power
`output reaches a maximum at the lowest point of that
`rang and begins to decrease as the air inlet temperature
`decreases beyond that point. FIGS. 2 and 3 show that
`relationship. The lowest point of the range in which the
`power reaches a maximum is hereinafter sometimes
`referred to as the optimum inlet temperature. Accord
`ingly, when a multishaft gas turbine operates in a hot
`environment wherein the ambient temperature is above
`the optimum inlet temperature, it is desirable to cool the
`air ?owing to the turbine towards that optimum inlet
`temperature to increase its power output. Similarly,
`when a multishaft turbine operates in a cold environ
`ment where the ambient temperature is less than the
`optimum inlet temperature, it is desirable to increase the
`air inlet temperature up to such optimum inlet tempera
`ture to increase the power output thereof.
`According to the present invention, when a multi
`shaft combustion gas turbine is operated in an environ
`ment where the ambient temperature is less than the
`optimum inlet temperature for the turbine, the air is
`heated in a heat exchanger by exchanging heat with a
`heating medium such as a hot ?uid or the like being
`heated by heat which is available from the gas turbine.
`Preferably, the heat exchanger may be utilized also as a
`cooler to cool the air entering the turbine when the
`ambient temperature is above the optimum inlet temper
`
`PAGE 5 of 8
`
`PETITIONER'S EXHIBIT 1231
`
`

`
`10
`
`25
`
`6
`24 to electrical generator 22 to generate electricity.
`Exhaust gas stream 5 containing hot gases ?ows from
`the outlet of turbine 20 to steam generator 28 where it
`heats and vaporizes boiler feed water entering steam
`generator 28 via line 6 to generate saturated high pres
`sure steam exiting through steam stream 7 for appropri~
`ate utilization.
`Condensate which is available from the utilization of
`steam stream 7 is returned to the steam generator via
`stream 8. Makeup water is provided by water stream 9.
`Although heat exchanger 42 can be any heat ex
`changer that is suitable for heating or cooling an air
`stream, it is preferred that a coil heat exchanger having
`coils of ?nned tube type construction be used. Air ?ows
`through the exterior of the tubes and the heating or
`cooling medium flows through the tubes.
`In the heating mode, i.e., when the ambient tempera
`ture is less than the optimum inlet temperature of tur
`bine 20 and air stream 1 requires heating to increase the
`output of turbine 20, a hot heating medium comprised of
`water, glycol or other similar heat transfer media or
`mixtures thereof flows from heating source 30 to heat
`exchanger 42 via streams 10 and 11 to heat air stream 1.
`The cold heating medium exits heat exchanger 42 via
`stream 11 and returns to heating source 30 via stream 12
`for further heating and recirculation to heat exchanger
`42. A steam stream 13 supplies steam from steam stream
`7 to heating source 30 via line 16 to heat the circulating
`heating medium.
`In the cooling mode, i.e., when the ambient tempera
`ture is greater than the optimum inlet temperature and
`the performance of turbine 20 can be improved by cool
`ing air stream 1 towards that temperature, a cold cool
`ing medium such as water, glycol or other similar heat
`transfer media or mixtures thereof is circulated from
`cooling source 32 to heat exchanger 42 through streams
`14 and 11 to cool air stream 1. Following the cooling of
`air stream 1, the hot cooling medium exits heat ex
`changer 42 via stream 11 and returns to chiller 32 via
`stream 15 for further cooling and recirculation to heat
`exchanger 42. Cooling source 32 is an absorption type
`chiller which utilizes steam from stream 7 flowing to
`chiller 32 a steam lines 13 and 17.
`In the event that the ambient temperature is substan
`tially equal to the optimum inlet temperature 20, no
`cooling or heating media are circulated in heat ex
`changer 42 via stream 11. The flow of heating or cool
`ing medium in stream 11 is controlled in response to the
`temperature of air stream 1 entering turbine 20 and a
`predetermined optimum inlet temperature. Accord
`ingly, well known flow control techniques and instru
`ments may be used. Control valves 51, 52, 53, 54, 55, 56,
`and 57 control and regulate the ?ow in streams and lines
`10, 12, 14, 15, 16, 17, and 13, respectively.
`The following examples further illustrate the inven
`tion, but are not to be construed as limitations on the
`scope of the process and apparatus contemplated
`herein.
`
`20
`
`5,083,423
`5
`ature to increase the performance of the turbine. Alter
`natively, the heat exchanger may be used alone as a
`heater for applications wherein the ambient tempera
`ture does not exceed the optimum inlet temperature or
`it may be used in combination with a separate heat
`exchanger which operates as a cooler for those in
`stances wherein the ambient temperature exceeds the
`optimum inlet temperature.
`Referring now to FIG. 4, there is shown a cogenera
`tion apparatus for generating electricity and steam hav
`ing a heat exchanger for optimizing the temperature of
`the air entering a combustion gas turbine in accordance
`with the present invention. The heat exchanger is used
`as a heater to heat the air ?owing to the combustion gas
`turbine when the ambient temperature is below the
`optimum inlet temperature and as a cooler to cool the
`air flowing to the combustion gas turbine when the
`turbine is operated in an environment where the ambi
`ent temperature is above the optimum inlet tempera
`ture. The cogeneration apparatus includes a gas turbine
`20 being connected to an electrical generator 22 via
`shaft 24, an air ?lter/coil module 26 for treating the air
`inlet to turbine 20, a steam generator 28, a heating
`source 30 and a cooling source 32. Turbine 20 includes
`a compression section 34 a combustion section 36, and
`an expansion section 38. Air ?lter/coil module 26 in
`cludes a pre?lter 40, a heat exchanger 42, a demister 44,
`?nal ?lters 46 and silencer 48. An air stream 1 enters air
`?lter/coil module 26 and flows, in sequence, through
`pre?lter 40, heat exchanger 42, demister 44, ?nal ?lters
`46 and silencer 48 for preparation prior to entering
`turbine 20. Pre?lter 40 removes large particulates from
`air stream 1.
`Heat exchanger 42 heats or cools air stream 1 in ac
`cordance with the present invention, depending on the
`temperature of the air entering air ?lter/coil module 26
`and the optimum inlet temperature of gas turbine 20.
`More particularly, if the ambient air temperature is less
`than the optimum inlet temperature of turbine 20, heat
`exchanger 42 heats air stream 1 to raise its temperature
`up to the optimum inlet temperature by exchanging heat
`between air stream 1 and a hot heating medium pro
`vided in stream 11, as hereinafter described. Alterna
`tively, if the ambient temperature of air stream 1 is
`greater than the optimum inlet temperature of gas tur
`bine 20, heat exchanger 42 cools air stream 1 to reduce
`its temperature towards the optimum inlet temperature
`by providing cooling from a cold cooling medium pro
`vided through stream 11, as hereinafter described. In
`the event that the ambient temperature of air stream 1 is
`about equal to the optimum inlet temperature of turbine
`20, no cooling or heating of air stream 1 is necessary in
`heat exchanger 42.
`Demister 44 removes water that may be entrained in
`air stream 1, ?nal ?lters 46 remove any ?ne particles
`that may be present in said air stream 1, and silencer 48
`reduces the noise being generated by the flow of air
`stream 1.
`Upon exiting air ?lter/coil module 26, air stream 1
`enters compression section 36 where air stream 1 is
`compressed. The compressed air flows into combustion
`section 38 where it is combusted by combustion fuel gas
`?owing therein via combustion gas stream 2 in the pres
`ence of water ?owing therein via water stream 3. Water
`is provided via water stream 3 to reduce the nitrogen
`oxiges emissions to the allowable level. The combustion
`gases being generated flow into expansion section 38
`and generate shaft work which is transferred via shaft
`
`40
`
`45
`
`50
`
`EXAMPLE 1
`An LMZSOO gas turbine manufactured by the General
`Electric Aircraft Engine Group of Evendale, Ohio, was
`placed in operation in accordance with the ?ow scheme
`shown in FIG. 4 in which the ambient temperature of
`air was 80° F. and its relative humidity was 80%. No
`heat exchange fluid was circulated in stream 11. The air
`?owed through air ?lter/coil module 26 with a total
`pressure drop of about 4 inches of H10 and entered
`
`65
`
`PAGE 6 of 8
`
`PETITIONER'S EXHIBIT 1231
`
`

`
`8
`condensate return available at 200° F. and make-up
`water. Exhaust gas stream 5 exited steam generator 28
`at 306° F. No cooling or heating medium' was circulated
`via stream 11 and no steam was utilized from steam line
`7.
`
`5
`
`5,083,423
`7
`compression section 36 of turbine 20 at 80° F. and 80%
`relative humidity. The air was compressed in compres
`sion section 36 and ?owed to combustion section 38
`where it was burned by 207.9 MMBTU per hour of
`lower heating value gas in the presence of 7205 pounds
`per hour of water. The exhaust gases were expanded in
`expansion section 38 and exited turbine 20 at 997° F. at
`a rate of 143.5 pounds per second. Shaft 24 transferred
`work to electrical generator 22 which generated 20,682
`kilowatts of electricity. Exhaust stream 5 supplied heat
`in steam generator 28 and generated 91,800 pounds per
`hour of 150 psig saturated steam in steam line 7 by
`vaporizing return condensate returned by stream 8 at
`200' F. and make up water provided by stream 9. Ex
`haust gas stream 5 exited steam generator 28 at 280° F.
`No steam was allowed to flow through steam stream 13
`to either cooling source 32 or heating source 30.
`
`EXAMPLE 4
`The gas turbine of Example 3 was placed in the same
`environment as in Example 3 at an ambient temperature
`of 0° F. and 60% relative humidity. Air stream 1 was
`heated in heat exchanger 42 to 35° F. and 18% relative
`humidity by hot water which circulated therethrough
`at the rate of 800gallons per minute with an inlet tem
`perature 100° F. and an outlet temperature of 75° F. via
`stream 11. The heated air stream 1 was compressed in
`compression section 34 and combusted in combustion
`section 36 by 238.9 MMBTU per hour of low heating
`value gas in the presence of 10.785 pounds per hour of
`water. The exhaust gases were expanded in expansion
`section 38. The shaft work that was transmitted to elec
`tric generator 22 via shaft 24 generated 24,378 kilowatts
`of electricity. Exhaust stream 5 exited turbine 20 at 964°
`F. at a rate of 160.2 pounds per second and generated
`86,700 pounds per hour of 150 psig saturated steam in
`steam generator 28 by evaporating condensate return
`available in at 200° F. and make-up water. Exhaust
`stream 5 exited steam generator 28 at 288° F. The circu
`lating water was heated from 75° F. to 100° F. in heat
`ing source 30 by 9,900 pounds per hour of steam avail
`able from stream 7 and flowing to heating source 30 via
`streams 13 and 16. Examples 3 and 4 show that the
`preheating of air stream 1 from 0° to 35° F. increased
`the output of turbine from about 23,560 to about 24,378
`kilowatts.
`While a preferred embodiment of the present inven
`tion has been shown and described, various modi?ca
`tions of the apparatus and the process of the invention
`may be made by one skilled in the art without departing
`from the spirit of the invention and it is to be understood
`that the invention is limited only as de?ned in the fol
`lowing claims.
`What is claimed is:
`1. A method of increasing the power output of a
`combustion gas turbine which utilizes air and has a
`compression section, a combustion section and an ex
`pansion section, comprising the step of heating the air
`indirectly prior to ?owing the air to the compression
`section of the turbine.
`2. A method of increasing the power output of a
`multi-shaft combustion gas turbine which utilizes air
`and has a compression section, a combustion section
`and an expansion section, comprising the step of heating
`the air indirectly prior to ?owing the air into the com
`pression section of the turbine.
`3. A method according to claim 2 wherein the heating
`step includes the step of exchanging heat with a heating
`medium.
`4. In a multi-shaft combustion gas turbine which has
`a compression section, a combustion section and an
`expansion section and whose power output is affected
`by the temperature of air entering the turbine so that the
`power output reaches its maximum at an optimum tem
`perature of the air entering the turbine and decreases as
`the temperature of the air entering the turbine decreases
`below or increases above the optimum temperature, a
`method of increasing the power output of the turbine,
`comprising the step of heating the air indirectly prior to
`entering the compression section of the turbine to in
`
`20
`
`25
`
`EXAMPLE 2
`The turbine of Example 1 was placed in operation in
`the same environment as Example 1 where the ambient
`temperature was 80° F. and the relative humidity was
`80%. Air stream 1 was cooled in heat exchanger 42 by
`water circulating at 1200 gallons per minute being avail
`able at 45' F. Air stream 1 exiting air ?lter/coil module
`26 was cooled to 61.9’ F. and a relative humidity of
`99%. The cooling water exiting heat exchanger 42 was
`at 55° F. and was returned to cooling source 32 for
`further cooling and/or circulation. The cooled air
`stream 1 was compressed in compression section 34 and
`30
`combusted in combustion section 36 by 223.5 MBTU
`per hour of low heating value gas in the presence of
`8,738 pounds per hour of water which was injected for
`control of nitrogen oxides emissions. The shaft work
`generated in expansion section 38 was transmitted to
`electrical generator 22 via shaft 24 and generated 22,637
`kilowatts of electricity. Exhaust stream 5 exited turbine
`20 at 981° F. at a rate of 152.2 pounds per second. Ex
`haust stream 5 generated 85,600 pounds per hour of 150
`psig saturated steam in steam generator 28 by vaporiz
`ing condensate return provided at 200° F. by stream 8
`and make-up water provided by stream 9. Exhaust
`stream 5 exited steam generator 28 at 285° F. The circu
`lating water in stream 11 was cooled in cooling source
`32 from 55° to 45° F. by an absorption process utilizing
`9000 pounds per hour of steam available from steam
`stream 7 through steam lines 13 and 17. Example 2
`shows that the cooling of the air inlet to turbine 20 from
`80' F. to 61.9° F. increased the output of electric gener
`ator 22 from about 20,682 to about 22,637 kilowatts.
`
`45
`
`55
`
`EXAMPLE 3
`The turbine of Example 1 was placed in operation in
`an environment where the ambient temperature was 0°
`F. and the relative humidity was 60%. No heating or
`cooling was provided in heat exchanger 42. Air stream
`I entered turbine 20 at 0' F. and 60% relative humidity,
`was compressed in compression section 34 and was
`combusted in combustion section 36 by 228.1 MMBTU
`per hour of a low heating value gas in the presence of
`60
`9686 pounds per hour of NO, water. The exhaust
`stream was expanded in expansion section 38 and gener
`ated shaft work which was transmitted to electrical
`generator 22 by shaft 24 to generate 23,560 kilowatts of
`electricity. Exhaust stream 5 exited turbine 20 at 869° F.
`and at a rate of 165.5 pounds per second. Exhaust
`stream 5 generated 82,800 pounds per hour of 150 psig
`saturated steam in steam generator 28 by vaporizing
`
`65
`
`PAGE 7 of 8
`
`PETITIONER'S EXHIBIT 1231
`
`

`
`5,083,423
`crease the temperature of the air towards the optimum
`temperature, if the temperature of the air is below the
`optimum temperature.
`5. In a multi-shaft combustion gas turbine which re
`ceives air and whose power output is affected by the
`temperature of the air, a method of maximizing the
`power output of the turbine comprising the step of
`raising or lowering the temperature of the air being
`received by the turbine prior to ?owing the air to a
`compression section of the turbine.
`6. A method according to claim 5 wherein the raising
`or lowering step includes the step of exchanging heat
`between the air and a heating or a cooling medium in a
`heat exchanger.
`7. In a combustion gas turbine wherein the air inlet
`temperature of the air ?owing into the turbine has an
`effect on the power output of the turbine, the effect
`being characterized by a maximum power output at an
`optimum air inlet temperature and a decrease as the air
`inlet temperature increases above or decreases below
`
`10
`
`5
`
`10
`the optimum air inlet temperature, a method of increas~
`ing the power output of the turbine, comprising the step
`of cooling the air, if the temperature of the air is above
`the optimum air inlet temperature or heating the air, if
`the temperature of the air is below the optimum air inlet
`temperature.
`8. A method of increasing the power output of a
`combustion gas turbine which has a compression sec
`tion, a combustion section and an expansion section and
`wherein the air inlet temperatu