Patent Publication Number: US-2015068205-A1

Title: Steam turbine plant

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2013-185682 filed on Sep. 6, 2013, the entire contents of which are incorporated herein by reference. 
     FIELD OF THE INVENTION 
     An embodiment of the present invention relates to a steam turbine plant. 
     BACKGROUND ART 
     A steam turbine plant using a coal fired boiler  7  is described with reference to  FIG. 13 . A feed water  42  is transported to the coal fired boiler  7  by a feed pump  6 , and is heated therein to change to a steam  2 . Since the coal fired boiler  7  heats the feed water  42  by an exhaust combustion gas  13  that is generated by burning a coal  43 , the coal fired boiler  7  is a heat source derived from a fossil fuel.  FIG. 13  simply illustrates the exhaust combustion gas  13 , the coal  43  flowing into the coal fired boiler  7  and a combustion air  12 . 
     The steam  2  flows into a steam turbine  1  and expands inside the steam turbine  1 , so that a pressure and a temperature thereof lower. A turbine exhaust gas  3  flows into a condenser  4 . The turbine exhaust gas  3  is cooled by a cooling water in the condenser  4  to become a condensation  5 . The condensation  5  merges with a drainage water  10  described below to become a feed water  42  so as to be circulated. Although not shown, the cooling water is drawn up by a not-shown cooling water pump from sea, and is then transported to the condenser  4 . After heated in the condenser  4 , the cooling water is returned to the sea. 
     A rotating shaft of the steam turbine  1 , which is rotated by the expanding steam  2 , is connected to a not-shown generator. Power is generated in the generator by using a generated shaft power. An extraction steam  8  extracted from a middle location of the steam turbine  1  flows into a feed water heater  9  so as to heat the feed water  42  transported by the feed pump  6 . At this time, the extraction steam  8  condenses to become the drainage water  10 , and finally merges with the condensation  5 . When no steam is extracted from the steam turbine  1 , the condensation  5  becomes the feed water  42  as it is. 
     A steam turbine plant constituting a part of a combined cycle is described with reference to  FIG. 14 . The same part as the technique shown in  FIG. 13  is shown by the same reference number and detailed description thereof is omitted. Only a part different from the technique shown in  FIG. 13  is described. A gas turbine exhaust gas  14  from a not-shown gas turbine, which has a sufficiently high temperature, is caused to flow into an exhaust gas boiler  15 . A feed water  42  is transported to the exhaust gas boiler  15  by a feed pump  6 , and is heated therein by the gas turbine exhaust gas  14  to change to a steam  2 . Since a gas turbine generates an exhaust combustion gas by burning a natural gas or a town gas so as to be driven by the gas turbine exhaust gas  14 , the exhaust gas boiler  15  is a kind of a heat source derived from a fossil fuel. After a temperature of the gas turbine exhaust gas  14  lowers, the gas turbine exhaust gas  14  flows out from the exhaust gas boiler  15 . An extraction steam  8  is not extracted from a middle location of the steam turbine  1  in  FIG. 14 . However, similarly to  FIG. 13 , the extraction steam  8  may be extracted from a middle location of the steam turbine  1  and may be caused to flow into a feed water heater  9  so as to heat a feed water  42 . 
     In a Rankine cycle, the higher the temperature and the pressure of a steam turbine inlet steam are, the higher the efficiency, i.e., the value of a steam turbine output with respect to a heat quantity received from a heating source is. A value obtained by multiplying a generator efficiency by the output is a power generation quantity.  FIG. 18  shows a TS line diagram in which an axis of ordinate shows a temperature of a working fluid and an axis of abscissa shows an entropy. Curves  32  and  33  are a saturated liquid line and a saturated steam line. A steam turbine inlet, a steam turbine outlet (condenser inlet), a condenser outlet (feed pump inlet), and a feed pump outlet are shown by the reference characters e, f, a and b in  FIG. 18 . An area A is an area that is surrounded by “a, b, c, d, e and f”, and an area B is an area that is surrounded by “f, j, k and a”. A received heat quantity, a heat quantity to be released to a cooling water and a steam turbine output correspond to superficial dimensions of the areas A+B, the area B and the area A, respectively. The efficiency corresponds to an area ratio A/(A+B). 
     When a steam turbine inlet has a higher temperature and a higher pressure, a steam turbine inlet is “i” in  FIG. 18 , and the area A is an area A′ that is surrounded by “a, b, c, g, h, i and f”. The area B corresponding to a heat quantity to be released to a cooling water is unchanged. The areas A+B and the area A corresponding to a received heat quantity and a steam turbine output are changed to areas A′+B and an area A′, respectively. Thus, the area ratio A′/(A′+B) is larger than A/(A+B). For this reason, an efficiency improves. 
     A general waste power generation is described with reference to  FIG. 15 . The same part as the technique shown in  FIG. 13  is shown by the same reference number and detailed description thereof is omitted. Only a part different from the technique shown in  FIG. 13  is described. A waste boiler  18  burns a waste, so as to heat water by a waste exhaust combustion gas  44 . The waste exhaust combustion gas  44 , a waste  11  flowing into the waste boiler  18  and a combustion air  12  are briefly illustrated. A feed water  42  is transported to the waste boiler  18  by a feed pump  6 , and is heated therein to change to a steam  2 . Since the waste exhaust combustion gas  44  contains a corrosive gas such as hydrogen chloride, a heat cannot be recovered only at a temperature that does not cause a high temperature corrosion in a boiler heat exchanger tube. In many cases, when a tube wall temperature of a boiler heat exchanger tube exceeds about 320° C., a high temperature corrosion is more likely to occur therein. Thus, a steam temperature is generally 300° C. or less, for example. For this reason, a steam turbine inlet temperature cannot be raised only up to 300° C., for example. Although there is a case in which a steam turbine inlet temperature can be raised more, a steam turbine inlet temperature can be raised only up to 400° C. or less at most. In the Rankine cycle, when the temperature and the pressure of the steam turbine inlet are higher, an efficiency can be raised. That is to say, a power generation efficiency cannot be raised. The waste power generation produces electricity after a waste has been appropriately treated. In order to make good use of an exhaust gas generated by the waste treatment, power generation is carried out although the efficiency is low. 
     A general geothermal power generation is described with reference to  FIG. 16 . The same part as the technique shown in  FIG. 13  is shown by the same reference number and detailed description thereof is omitted. Only a part different from the technique shown in  FIG. 13  is described. A geothermal steam  19  taken out from a ground  21  is caused to flow into a steam separator  45 , so that the geothermal steam  19  is separated into a steam  2  and a hot water  20 . The steam  2  flows into a steam turbine  1 . The steam  2  expands inside the steam turbine  1 , so that a pressure and a temperature thereof lower. A turbine exhaust gas  3  is released outside. Since a steam temperature is not more than 350° C. in most cases, a steam turbine inlet temperature cannot be raised so that a power generation efficiency cannot be raised. In addition, a heat held by the hot water  20  is not efficiently used. 
     A general solar heat power generation is described in described with reference to  FIG. 17 . The same part as the technique shown in  FIG. 13  is shown by the same reference number and detailed description thereof is omitted. Only a part different from the technique shown in  FIG. 13  is described. A heating medium  24  receives a radiant heat of solar light so as to be heated in a solar heat collector  23 . The heated heating medium  24  is diverged into two. One heating medium flows into a solar heat heater  22 , and the other heating medium flows into a heat storage tank  25 . A heating medium pump  27  is adjusted such that the heating medium flows in a direction drawn by a solid line on the left side of the heat storage tank  25 . A part of the heating medium  24  flows into the solar heat heater to heat a feed water  42  to lose its temperature, and flows out therefrom. When a remaining part of the heating medium  24 , which has heated the feed water  42 , flows into the heat storage tank  25 , the heating medium, which has been already therein and has a lower temperature, flows out from the heat storage tank  25 , so that the heating medium  24  of a higher temperature is stored in the heat storage tank  25  in the end. After the heating medium  24  has been stored, valves  30  and  31  are totally closed. The heating medium  24  is transported by heating medium pumps  26  and  27 . The feed water  42  is transported to the solar heat heater by a feed pump  6 , and is heated therein to change to a steam  2 . During a nighttime when no solar light exists or a time zone when only weak solar light exists, valves  28  and  29  are closed and the heating medium pump  26  is stopped, while the valves  30  and  31  are opened and the heating medium pump  27  is operated, so that the heating medium flows in a direction drawn by dotted lines on the right side of the heat storage tank  25 . The feed water  42  is heated by circulating the heating medium  24  between the heat storage tank  25  and the solar heat heater  22 , without circulating the heating medium  24  through the solar heat collector  23 . 
     PRIOR ART DOCUMENTS 
     Patent Documents 
     Patent Document 1: JP2008-39367A 
     Patent Document 2: JP2008-121483A 
     SUMMARY OF THE INVENTION 
     In the techniques shown in  FIGS. 15 and 16 , since a steam turbine inlet temperature cannot be raised, a power generation efficiency cannot be raised like the techniques shown in  FIGS. 13 and 14 . Thus, improvement in power generation efficiency is desired. In addition, in the technique shown in  FIG. 16 , a heat held by the hot water  20  is desired to be efficiently used for power generation. 
     A fuel battery is a power generation method that is different from a turbine. The fuel battery releases a large amount of exhaust heat. However, an exhaust heat temperature is considerably lower than a temperature suited for a working fluid of a steam turbine. In addition, an industrial exhaust heat from factories and offices is discharged without being efficiently used. In most cases, a temperature of the exhaust heat is considerably lower than a temperature suited for a working fluid of the steam turbine  1 . It is desired that these exhaust heats are efficiently used to generate power. 
     The object of the present invention is to carry out a highly efficient power generation by using a heat source whose steam turbine inlet temperature cannot be raised, and to generate power by efficiently using an exhaust heat having a considerably low temperature. 
     A steam turbine plant according to one embodiment is a steam turbine plant including: a steam turbine; and a heating unit configured to heat a working fluid to be supplied to the steam turbine; wherein: the heating unit is configured to heat the working fluid by a first heat source using a fossil fuel or a second heat source using an extracted steam from the steam turbine; and the heating unit is configured to further heat the working fluid in a low temperature zone by a third heat source other than a solar heat, the third heat source not using a fossil fuel. 
     A steam turbine plant according to another embodiment is a steam turbine plant including: a steam turbine; and a heating unit configured to heat a working fluid to be supplied to the steam turbine; wherein: the heating unit is configured to heat the working fluid by a fourth heat source using a solar heat or a second heat source using an extracted steam from the steam turbine; the heating unit is configured to further heat the working fluid in a low temperature zone by a fifth heat source other than a solar heat; and the fifth heat source includes an industrial exhaust heat. 
     A steam turbine plant according to yet another embodiment is a steam turbine plant including: a steam turbine; and a heating unit configured to heat a working fluid to be supplied to the steam turbine; wherein: the heating unit is configured to heat the working fluid by a fourth heat source using a solar heat or a second heat source using an extracted steam from the steam turbine; the heating unit is configured to further heat the working fluid in a low temperature zone by a fifth heat source other than a solar heat; and the fifth heat source includes an exhaust heat of a fuel battery or an internal combustion engine. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a conceptual view showing a steam turbine plant according to a first embodiment. 
         FIG. 2  is a conceptual view showing a steam turbine plant according to a second embodiment. 
         FIG. 3  is a conceptual view showing a steam turbine plant according to a third embodiment and a fourth embodiment. 
         FIG. 4  is a conceptual view showing a steam turbine plant according to a fifth embodiment. 
         FIG. 5  is a conceptual view showing a steam turbine plant according to a sixth embodiment. 
         FIG. 6  is a conceptual view showing a steam turbine plant according to a seventh embodiment. 
         FIG. 7  is a conceptual view showing a steam turbine plant according to an eighth embodiment and a ninth embodiment. 
         FIG. 8  is a conceptual view showing a steam turbine plant according to a tenth embodiment. 
         FIG. 9  is a conceptual view showing a steam turbine plant according to an eleventh embodiment. 
         FIG. 10  is a conceptual view showing a steam turbine plant according to a twelfth embodiment and a thirteenth embodiment. 
         FIG. 11  is a conceptual view showing a steam turbine plant according to a fourteenth embodiment. 
         FIG. 12  is a conceptual view showing a steam turbine plant according to a fifteenth embodiment. 
         FIG. 13  is a conceptual view showing a steam turbine using a coal fired boiler. 
         FIG. 14  is a conceptual view showing a steam turbine of a combined cycle. 
         FIG. 15  is a conceptual view showing a technique of waste power generation. 
         FIG. 16  is a conceptual view showing a technique of geothermal power generation. 
         FIG. 17  is a conceptual view showing a technique of solar power generation. 
         FIG. 18  is a TS line diagram of a Rankine cycle. 
         FIGS. 19(   a ) and ( b ) are conceptual views showing an effect of the embodiments. 
     
    
    
     EMBODIMENTS FOR CARRYING OUT THE INVENTION 
     First Embodiment 
     A steam turbine according to a first embodiment is described with reference to  FIG. 1 . 
     As shown in  FIG. 1 , a gas turbine exhaust gas  14  from a not-shown gas turbine, which has a sufficiently high temperature, is caused to flow into an exhaust gas boiler  15 . A feed water  42  is transported to the exhaust gas boiler  15  by a feed pump  6 , and is heated therein by a gas turbine exhaust gas  14  to change to a steam  2 . Since the gas turbine generates an exhaust combustion gas by burning a natural gas or a town gas so as to be driven by the gas turbine exhaust gas  14 , the exhaust gas boiler  15  is a heat source derived from a fossil fuel (first heat source). 
     After a temperature of the gas turbine exhaust gas  14  lowers, the gas turbine exhaust gas  14  flows out from the exhaust gas boiler  15 . The steam  2  flows into the steam turbine  1 , and expands inside the steam turbine  1 , so that a pressure and a temperature thereof lower. A turbine exhaust gas  3  from the steam turbine  1  flows into a condenser  4 . The turbine exhaust gas  3  is cooled by a cooling water in the condenser  4  to become a condensation  5 . Although not shown, the cooling water is drawn up by a not-shown cooling water pump from sea, and is then transported to the condenser  4 . After heated in the condenser  4 , the cooling water is returned to the sea. A rotating shaft of the steam turbine  1 , which is rotated by the expanding steam  2 , is connected to a not-shown generator. Power is generated in the generator by using a generated shaft power. 
     As shown in  FIG. 1 , a waste boiler  18  is installed as a heater. To be specific, the feed water  42  is diverged into a second feed water  35  and a third feed water  36 . The second feed water  35  is transported to the exhaust heat boiler  15 , and is heated therein by the gas turbine exhaust gas  14  so as to have a higher temperature. The third feed water  36  flows into the waste boiler  18  as a heater, and is heated by a waste exhaust combustion gas (third heat source)  44 , which is generated by burning a waste  11  and a combustion air  12 , so as to have a higher temperature. Since a pressure of the third feed water  36 , which is equal to a pressure of the second feed water  35  for a high-temperature high-pressure turbine, is higher than a pressure for a waste, power generation, the third feed water  36  does not basically boil. Thus, the waste boiler  18  functions only as a hot water boiler. After that, the third feed water  36  flows into a middle location of the exhaust heat boiler  15 , and merges with the second feed water  35 , which has been heated by the exhaust heat boiler  15 , at a merging point  34 . A temperature of the third feed water  36  is restricted in terms of high temperature corrosion. It is preferable that the merging point  34  is located such that the temperature of the second feed water  35  and the temperature of the third feed water  36  are substantially equal to each other, but it is not a must. 
     In the waste boiler  18 , a composition of the waste  11  and an amount of the waste  11  to be treated may considerably vary, but a property of the steam  2  flowing into the steam turbine  1  should not considerably vary. In a general steam turbine plant, a temperature and a pressure of the steam  2  are measured, and the temperature and the pressure should not considerably vary. In addition, in a general steam turbine plant, a flow rate of the steam  2  is obtained by measuring a flow rate of the feed water  42 , for example, and the flow rate of the steam  2  should not considerably vary. 
     For this reason, it is preferable that an output of the feed pump  6  is adjusted so as to adjust a flow rate and a pressure of the feed water  42 , that a flow rate ratio between the second feed water  35  and the third feed water  36  is adjusted by adjusting opening degrees of the valves  37  and  38 , and that, depending on cases, an amount of the waste  11  to be treated is increased or decreased, in order that the temperature, the pressure and the flow rate of the steam  2  do not considerably vary. At this time, although not shown, a flow-rate adjusting valve may be installed on a downstream of the feed pump  6 , so as to adjust the flow rate and the pressure of the feed water  42  by adjusting an opening degree of the flow-rate adjusting valve. A pressure of the third feed water  36 , which is a working fluid of the waste boiler  18 , is adjusted by the feed pump  6 . The pressure of the third feed water  36  is a pressure for a high-temperature high-pressure turbine, similarly to the technique shown in  FIG. 14 . Thus, the pressure of the third feed water  36  is higher than that in the technique shown in  FIG. 15 . In  FIG. 18 , the merging point  34  is shown by  1 . If the pressure of the third feed water  36  at the merging point  34  is higher and the third feed water  36  is changed to a saturated steam, it is preferable that a wetness of the second feed water  35  and a wetness the third feed water  36  are substantially equal to each other, but it is not a must. The merged water is further heated by the exhaust heat boiler  15  so as to change to the steam  2 . Then, the steam  2  flows into the steam turbine  1 . In  FIG. 18 , the water is heated in parallel by two kinds of heat sources from b to l, and is heated by one kind of heat source from l to i. When the third feed water  36  is not circulated because the waste boiler  18  is stopped and the like, the valves  37  and  38  are totally closed. In general, since a steam flow rate in the waste power generation is sufficiently smaller than a steam flow rate in the combined cycle, even if the flow rate of the steam  2  somewhat lowers, the steam turbine  1  can be operated. 
     Suppose that the exhaust heat boiler  15  and the waste boiler  18  are connected in series with respect to the water. In this case, since a temperature of the gas turbine exhaust gas  14  does not lower down to a water temperature at an outlet of the waste boiler  18 , a heat of the gas turbine exhaust gas  14  cannot be recovered at a temperature lower than that. On the other hand, according to this embodiment, since an upstream side of the exhaust heat boiler  15  and the waste boiler  18  are in parallel with respect to the feed water, a heat recovery from the gas turbine exhaust gas  14  will not be restricted for its existence. In addition, an outlet temperature of the exhaust gas of the exhaust heat boiler  15  is equal to the technique shown in  FIG. 14 , a received heat quantity from the exhaust heat boiler  15  is equal to the technique shown in  FIG. 14 . Thus, as the Rankine cycle, a received heat quantity is increased by a heat received from the waste boiler  18 , so that a flow rate of the steam  2  is increased to increase an output, while a steam turbine inlet temperature is unchanged. An efficiency of the Rankine cycle is determined only by the area ratio in the TS line diagram, regardless of a flow rate. Since all the steam constitutes the Rankine cycle of a high temperature and a high pressure, an efficiency according to this embodiment is equal to the technique shown in  FIG. 14 . In addition, as compared with a case in which the technique shown in  FIG. 14  and the technique shown in  FIG. 15  separately exist, an output of this embodiment is large and an efficiency is high even if the same received heat quantity is generated. Thus, a highly efficient power generation can be carried out by using the heat from the waste boiler  18  from which a highly efficient power generation was impossible. Since the operation of the gas turbine is not influenced, there is no possibility that a power generation output and an efficiency of the gas turbine are degraded. 
     The structure shown in  FIG. 1  is nothing more than an example, and the merging point at which the second feed water  35  and the third feed water  36  merge with each other may not the middle location of the exhaust heat boiler  15 , but may be a location that is downstream of the outlet thereof. In addition, similarly to  FIG. 13 , an extraction steam  8  extracted from a middle location of the steam turbine  1  may be caused to flow into a feed water heater  9  so as to heat the feed water  42 . 
     An effect of this embodiment is described with reference to  FIG. 19 . As shown in  FIG. 19(   a ), a feed water is heated from a condensation temperature to a steam turbine inlet temperature in the following manner. The feed water of a lower temperature zone of a lower temperature is heated by the exhaust heat boiler  15  using the heat source derived from a fossil fuel (first heat source) and the waste exhaust combustion gas which is the heat source other than a fossil fuel (third heat source). The feed water of a higher temperature zone of a higher temperature is heated by the exhaust heat boiler  15  using the heat source derived from a fossil fuel (first heat source). 
     In this manner, since the feed water of the lower temperature zone is heated also by the waste exhaust combustion gas, and a high temperature steam flowing into the the steam turbine  1  is reliably generated by the the exhaust heat boiler  15  derived from a fossil fuel, the waste exhaust combustion gas of a lower temperature, which has not been used heretofore in the steam turbine  1 , can be efficiently used to improve a power generation efficiency. 
     Second Embodiment 
     Next, the steam turbine plant according to a second embodiment is described with reference to  FIG. 2 . 
     In the steam turbine plant shown in  FIG. 2 , the same part as that of the steam turbine plant shown in  FIG. 1  is shown by the same reference number and detailed description thereof is omitted. 
     As shown in  FIG. 2 , there is installed a heater  47  for heating a steam  2  by a geothermal steam  19 . Differently from the technique shown in  FIG. 16 , in  FIG. 2 , the geothermal steam  19  (third heat source) taken out from a ground  21  is caused to flow directly into a heater  47 . A third feed water  36  flows into the heater  47  and is heated by the geothermal steam  19  so as to have a higher temperature. Since a pressure of the the third feed water  36  is equal to a pressure of the second feed water  35  for a high-temperature high-pressure turbine, the third feed water  36  does not basically boil. After that, the third feed water  36  flows into a middle location of an exhaust heat boiler  15 , and merges with the second feed water  35 , which has been heated by the exhaust heat boiler  15 . A temperature of the third feed water  36  is not raised to a temperature of the geothermal steam  19 . It is preferable that the merging point  34  is located such that the temperature of the second feed water  35  and the temperature of the third feed water  36  are substantially equal to each other, but it is not a must. 
     A flow rate and a temperature of the geothermal steam  19  may considerably vary, but a property of the steam  2  flowing into the steam turbine  1  should not considerably vary. In a general steam turbine plant, a temperature and a pressure of the steam  2  are measured, and the temperature and the pressure should not considerably vary. In a general steam turbine plant, a flow rate of the steam  2  is obtained by measuring a flow rate of the water  42 , for example, and the flow rate of the steam  2  should not considerably vary. 
     For this reason, it is preferable that an output of the feed pump  6  is adjusted so as to adjust a flow rate and a pressure of the feed water  42 , that a flow rate ratio between the second feed water  35  and the third feed water  36  is adjusted by adjusting opening degrees of valves  37  and  38 , and that, depending on cases, a flow rate of the geothermal steam  19  is increased or decreased by a not-shown flow-rate adjusting valve, in order that the temperature, the pressure and the flow rate of the steam  2  do not considerably vary. At this time, although not shown, a flow-rate adjusting valve may be installed on a downstream of the feed pump  6 , so as to adjust the flow rate and the pressure of the feed water  42  by adjusting an opening degree of the flow-rate adjusting valve. Since a pressure of the third feed water  36 , which is adjusted by the feed pump  6 , is a pressure for a high-temperature high-pressure turbine similarly to the technique shown in  FIG. 14 , the pressure of the third feed water  36  is higher than a pressure of the geothermal steam  19  in the technique shown in  FIG. 16 . Thus, the third feed water  36  does not boil even partially. A merging point  34  is shown by m in  FIG. 18 . The merged water is heated by the exhaust heat boiler  15  so as to change to a steam  2 . Then, the steam  2  flows into the steam turbine  1 . In  FIG. 18 , when the merging point  34  is shown by m, the water is heated in parallel by two kinds of heat sources from b to m, and is heated by one kind of heat source from m to i. When the third feed water  36  is not circulated through a heater  47  for some reason or other, the valves  37  and  38  are totally closed. Since a flow rate of the third feed water  36  is sufficiently smaller than a flow rate of the second feed water  35 , even if the flow rate of the steam  2  somewhat lowers, the steam turbine  1  can be operated. 
     In the technique shown in  FIG. 16 , a temperature of the steam  2  separated by a steam separator  45  is the same as a temperature of the geothermal steam  19 . On the other hand, according to this embodiment, since the third feed water  36  is heated by the geothermal steam  19 , a temperature of the third feed water  36  is lower than the temperature of the geothermal steam  19 . However, since a heat of the hot water  20 , which is thrown away in the technique shown in  FIG. 16 , is recovered in this embodiment, a heat recovery quantity from the geothermal steam  19  is larger. In addition, according to this embodiment, since all the steam constitutes the Rankine cycle of a high temperature and a high pressure, an efficiency according to this embodiment is equal to the technique shown in  FIG. 14 . As compared with a case in which the technique shown in  FIG. 14  and the technique shown in  FIG. 15  separately exist, an output of this embodiment is large and an efficiency is high even if the received heat quantity is the same. Further, the received heat quantity in Example 2 is larger. Thus, a highly efficient power generation can be carried out by using the geothermal steam from which a highly efficient power generation was impossible. Since the operation of the gas turbine is not influenced, there is no possibility that a power generation output and an efficiency of the gas turbine are degraded. 
     The structure shown in  FIG. 2  is nothing more than an example, and the merging point  34  at which the second feed water  35  and the third feed water  36  merge with each other may not the middle location of the exhaust heat boiler  15 , but may be a location that is downstream of the outlet thereof. 
     An effect of this embodiment is described with reference to  FIG. 19 . As shown in  FIG. 19(   a ), a feed water is heated from a condensation temperature to a steam turbine inlet temperature in the following manner. The feed water of a lower temperature zone is heated by the exhaust heat boiler  15  using the heat source derived from a fossil fuel (first heat source) and the geothermal steam which is the heat source other than a fossil fuel (third heat source). The feed water of a higher temperature zone is heated by the exhaust heat boiler  15  using the heat source derived from a fossil fuel (first heat source). 
     In this manner, since the feed water of the lower temperature zone is heated also by the geothermal steam, and a high temperature steam flowing into the steam turbine  1  is reliably generated by the exhaust heat boiler  15  derived from a fossil fuel, the geothermal steam of a lower temperature, which has not been used heretofore in the steam turbine  1 , can be efficiently used to improve a power generation efficiency. 
     Third Embodiment 
     Next, the steam turbine plant according to a third embodiment is described with reference to  FIG. 3 . 
     In the steam turbine plant shown in  FIG. 3 , the same part as that of the steam turbine plant shown in  FIG. 1  is shown by the same reference number and detailed description thereof is omitted. 
     As shown in  FIG. 3 , there is installed a heater  47 . In  FIG. 3 , the heater  47  is configured to heat a third feed water  36  by a heat recovery water (third heat source)  40  which recovers an industrial exhaust heat. The industrial exhaust heat is an exhaust heat generated from a factory or an office building. In general, the industrial heat is recovered by the heat recovery water  40  that circulates up to a cooling water, and is released to an atmospheric air from the cooling tower. The heat recovery water  40  is caused to circulate, not through the cooling tower, but through the heater  47 . The heat recovery water  40 , which recovers heat from an industrial exhaust heat source  39 , is circulated by a recovery water pump  41 . A temperature of the heat recovery water  40  upon recovery of the industrial exhaust heat is lower, as a circulation flow rate thereof is larger. It is preferable that the flow rate of the heat recovery water  40  is higher than a flow rate of a feed water  42 . Since a pressure of the heat recovery water  40 , which is a pressure for a high-temperature high-pressure turbine, is high, the heat recovery water  40  is not generally heated to a temperature as a boiling point at its pressure. The third feed water  36  flows into the heater  47 , and is heated by the heat recovery water  40  so as to have a higher temperature. After that, the third feed water  36  flows into a middle location of an exhaust heat boiler  15 , and merges with a second feed water  35 , which has been heated by the exhaust heat boiler  15 . It is preferable that the merging point  34  is located such that a temperature of the second feed water  35  and a temperature of the third feed water  36  are substantially equal to each other, but it is not a must. 
     A heat quantity of the industrial steam may considerably vary, but a property of the steam  2  flowing into the steam turbine  1  should not considerably vary. In a general steam turbine plant, a temperature and a pressure of the steam  2  are measured, and the temperature and the pressure should not considerably vary. In a general steam turbine plant, a flow rate of the steam  2  is obtained by measuring a flow rate of the water  42 , for example, and the flow rate of the steam  2  should not considerably vary. 
     For this reason, it is preferable that an output of the feed pump  6  is adjusted so as to adjust a flow rate and a pressure of the feed water  42 , that a flow rate ratio between the second feed water  35  and the third feed water  36  is adjusted by adjusting opening degrees of the valves  37  and  38 , and that, depending on cases, a flow rate of the heat recovery water  40  is increased or decreased by adjusting an output of the recovery pump water  41 , in order that the temperature, the pressure and the flow rate of the steam  2  do not considerably vary. At this time, although not shown, a flow-rate adjusting valve may be installed on a downstream of the feed pump  6 , so as to adjust the flow rate and the pressure of the feed water  42  by adjusting an opening degree of the flow-rate adjusting valve. The merged water is heated by the exhaust heat boiler  15  so as to change to the steam  2 . Then, the steam  2  flows into the steam turbine  1 . In  FIG. 18 , the water is heated in parallel by two kinds of heat sources from b to n, and is heated by one kind of heat source from n to i. When the third feed water  36  is not circulated through a heater  47  for some reason or other, the valves  37  and  38  are totally closed. Since a flow rate of the third feed water  36  is sufficiently smaller than a flow rate of the second feed water  35 , even if the flow rate of the steam  2  somewhat lowers, the steam turbine  1  can be operated. 
     According to this embodiment, when an outlet temperature of the gas turbine exhaust gas  14  of the exhaust gas boiler  15  is equal to the technique shown in  FIG. 14 , a received heat quantity from the exhaust gas boiler  15  is equal to the technique shown in  FIG. 14 . Thus, as the Rankine cycle, a received heat quantity is increased by a heat received from the heat recovery water  40 , so that a flow rate of the steam  2  is increased to increase an output, while a steam turbine inlet temperature is unchanged. An efficiency of the Rankine cycle is determined only by the area ratio in the TS line diagram, regardless of a flow rate. In addition, according to this embodiment, since all the steam constitutes the Rankine cycle of a high temperature and a high pressure, an efficiency according to this embodiment is equal to the technique shown in  FIG. 14 . Moreover, according to this embodiment, a highly efficient power generation can be carried out by using the industrial exhaust heat which is discharged without being efficiently used. Since the operation of the gas turbine is not influenced, there is no possibility that a power generation output and an efficiency of the gas turbine are degraded. 
     An effect of this embodiment is described with reference to  FIG. 19 . As shown in  FIG. 19(   a ), a feed water is heated from a condensation temperature to a steam turbine inlet temperature in the following manner. The feed water of a lower temperature zone is heated by the exhaust heat boiler  15  using the heat source derived from a fossil fuel (first heat source) and the heat recovery water which is the heat source other than a fossil fuel (third heat source). The feed water of a higher temperature zone is heated by the exhaust heat boiler  15  using the heat source derived from a fossil fuel (first heat source). 
     In this manner, since the feed water of the lower temperature zone is heated also by the heat recovery water, and a high temperature steam flowing into the steam turbine  1  is reliably generated by the exhaust heat boiler  15  derived from a fossil fuel, the heat recovery water of a lower temperature, which has not been used heretofore in the steam turbine  1 , can be efficiently used to improve a power generation efficiency. 
     Fourth Embodiment 
     Next, the steam turbine plant according to a fourth embodiment is described with reference to  FIG. 3 . 
     In the third embodiment, the heat recovery water (third heat source)  40  recovers the industrial exhaust heat. On the other hand, in the fourth embodiment, the heat recovery water  40  recovers all or a part of an exhaust heat of a fuel battery  46 . As shown in  FIG. 3 , when the fuel battery  46  generates power by using a fossil fuel, a large amount of exhaust heat is generated. The exhaust heat of the large-sized fuel battery  46 , which generates power of a large capacity, is recovered by the heat recovery water  40 . In general, the heat recovery water  40  is variously used so that a temperature thereof lowers, and the heat recovery water  40  is finally released to an atmospheric air from a cooling tower so as to be circulated. The heat recovery water  40  is caused to circulate, not through the cooling tower, but through a heater  47 . At this time, the heat recovery water  40  may not be variously used but may be caused to circulate directly through the heater  47 . A temperature of the heat recovery water  40  upon recovery of the industrial exhaust heat is lower, as a circulation flow rate thereof is larger. It is preferable that the flow rate of the heat recovery water  40  is higher than a flow rate of a feed water  42 . Since a pressure of the heat recovery water  40 , which is a pressure for a high-temperature high-pressure turbine, is high, the heat recovery water  40  is not generally heated to a temperature as a boiling point at its pressure. A heat quantity of the exhaust heat of the fuel battery  46  may vary depending on an operation of the fuel battery  46 , but a property of a steam  2  flowing into a steam turbine  1  should not considerably vary. In a general steam turbine plant, a temperature and a pressure of the steam  2  are measured, and the temperature and the pressure should not considerably vary. In a general steam turbine plant, a flow rate of the steam is obtained by measuring a flow rate of the water  42 , for example, and the flow rate of the steam  2  should not considerably vary. For this reason, it is preferable that an output of the feed pump  6  is adjusted so as to adjust a flow rate and a pressure of the feed water  42 , that a flow rate ratio between a second feed water  35  and a third feed water  36  is adjusted by adjusting opening degrees of valves  37  and  38 , and that, depending on cases, a flow rate of the heat recovery water  40  is increased or decreased by adjusting an output of a recovery water pump  41 , in order that the temperature, the pressure and the flow rate of the steam  2  do not considerably vary. At this time, although not shown, a flow-rate adjusting valve may be installed on a downstream of the feed pump  6 , so as to adjust the flow rate and the pressure of the feed water  42  by adjusting an opening degree of the flow-rate adjusting valve. 
     Similarly to the third embodiment, a highly efficient power generation can be carried out by using all or a part of the exhaust heat of the fuel battery  46  which is discharged without being efficiently used. Since the operation of the gas turbine is not influenced, there is no possibility that a power generation output and an efficiency of the gas turbine are degraded. 
     Fifth Embodiment 
     Next, the steam turbine plant according to a fifth embodiment is described with reference to  FIG. 4 . 
     In the steam turbine plant shown in  FIG. 4 , the same part as that of the steam turbine plant shown in  FIG. 3  is shown by the same reference number and detailed description thereof is omitted. 
     As shown in  FIG. 4 , a heater  47  is installed. In  FIG. 5 , the heater  47  is a heater configured to heat a steam  2  by a heat recovery water  40  that recovers an industrial exhaust heat. A feed water  42  is transported to the heater  47 , and is heated by the heat recover water (third heat source)  40  so as to have a higher temperature. The feed water  42  flowing out from the heater  47  flows into an exhaust heat boiler  15 . The feed water  42  is heated by a gas turbine exhaust gas  14  so as to change to a steam  2 . 
     When the gas turbine exhaust gas  14  heats the feed water  42 , a temperature thereof lowers. However, a surface temperature of a metal of the exhaust heat boiler  15  in contact with the gas turbine exhaust gas  14  should not lower down to a low temperature corrosion temperature zone. Depending on a composition of a natural gas or a town gas, the temperature is 150° C., for example. If a temperature of the industrial exhaust heat is higher than the temperature, when the exhaust heat boiler  15  and the heater  47  are connected in series with respect to the feed water  42 , a temperature of the gas turbine exhaust gas  14  does not lower down to the temperature of the feed water  42  at an outlet of the heater  47 . Thus, a heat cannot be received from the gas turbine exhaust gas  14  subsequently. However, since the temperature of the industrial exhaust heat is generally lower than the low temperature corrosion temperature zone, there is no possibility that a heat received from the gas turbine exhaust gas  14  decreases. Since the industrial exhaust heat has a relatively lower temperature but an amount thereof is large, it is preferable that heat is exchanged between the industrial exhaust heat and the feed water  42 , while a temperature difference between the industrial exhaust heat and the feed water  42  is sufficiently maintained. The arrangement of the heater  47  is effective in terms thereof. 
     A heat quantity of the industrial exhaust heat may considerably vary, but a property of the steam  2  flowing into the steam turbine  1  should not considerably vary. In a general steam turbine plant, a temperature and a pressure of the steam  2  are measured, and the temperature and the pressure should not considerably vary. In a general steam turbine plant, a flow rate of the steam is obtained by measuring a flow rate of the water  42 , for example, and the flow rate of the steam  2  should not considerably vary. For this reason, it is preferable that an output of the feed pump  6  is adjusted so as to adjust the flow rate and the pressure of the feed water  42 , and that, depending on cases, a flow rate of the heat recovery water  40  is increased or decreased by adjusting an output of a recovery water pump  41 , in order that the temperature, the pressure and the flow rate of the steam  2  do not considerably vary. At this time, although not shown, a flow-rate adjusting valve may be installed on a downstream of the feed pump  6 , so as to adjust the flow rate and the pressure of the feed water  42  by adjusting an opening degree of the flow-rate adjusting valve. 
     Although the industrial exhaust heat is used in this embodiment, a heat to be used is not limited thereto. In addition, the number of the feed water heaters  9  may be one. 
     Sixth Embodiment 
     Next, the steam turbine plant according to a sixth embodiment is described with reference to  FIG. 5 . 
     In the steam turbine plant shown in  FIG. 5 , the same part as that of the steam turbine plant shown in  FIG. 1  is shown by the same reference number and detailed description thereof is omitted. 
     As shown in  FIG. 5 , a waste boiler  18  is installed as a heater. A feed water  42  is diverged into a second feed water  35  and the third feed water  36 . The second feed water  35  is transported to a group of one or more feed water heaters  9  (two in  FIG. 5 ) that are connected in series. The second feed water  35  is heated therein by an extracted steam  8  to have a higher temperature. The third feed water  36  flows into the waste boiler  18  as a heater  47 , and is heated by a waste exhaust combustion gas  44  so as to have a higher temperature. 
     Since a pressure of the third feed water  36 , which is equal to a pressure of the second feed water  35  for a high-temperature high-pressure turbine, is higher than a pressure in a waste power generation, the third feed water  36  does not basically boil. Thus, the waste boiler  18  functions only as a hot water boiler. Thereafter, the third feed water  36  flows into an outlet or a middle location of the group of the feed water heaters  9 , and merges with the second feed water  35  which has been heated by the feed water heater  9  disposed on an upstream thereof. 
     A temperature of the third feed water  36  is restricted in terms of high temperature corrosion. It is preferable that the merging point  34  is located such that the temperature of the second feed water  35  and the temperature of the third feed water  36  are substantially equal to each other, but it is not a must. 
     In the waste boiler  18 , a composition of the waste  11  and an amount of the waste  11  to be treated may considerably vary, but a property of the steam  2  flowing into the steam turbine  1  should not considerably vary. In a general steam turbine plant, a temperature and a pressure of the steam  2  are measured, and the temperature and the pressure should not considerably vary. In addition, in a general steam turbine plant, a flow rate of the steam  2  is obtained by measuring a flow rate of the feed water  42 , for example, and the flow rate of the steam  2  should not considerably vary. For this reason, an output of the feed pump  6  is adjusted so as to adjust a flow rate and a pressure of the feed water  42 , and a flow rate ratio between the second feed water  35  and the third feed water  36  is adjusted by adjusting opening degrees of valves  37  and  38 , in order that the temperature, the pressure and the flow rate of the steam  2  do not considerably vary. In addition, it is preferable that an output of a coal fired boiler  7  is increased or decreased, and that, depending on cases, an amount the waste  11  to be treated is increased or decreased. At this time, although not shown, a flow-rate adjusting valve may be installed on a downstream of the feed pump  6 , so as to adjust the flow rate and the pressure of the feed water  42  by adjusting an opening degree of the flow-rate adjusting valve. 
     A pressure of the third feed water  36 , which is a working fluid of the waste boiler, is adjusted by the feed pump  6 . The pressure of the third feed water  36  is a pressure for a high-temperature high-pressure turbine similarly to the technique shown in  FIG. 14 . Thus, the pressure of the third feed water  36  is higher than a pressure of the technique shown in  FIG. 15 . In  FIG. 18 , the merging point  34  is shown by  1 . If there is the feed water heater  9  downstream of the merging point  34 , the merged water is heated by the same. After that, the merged water flows into the coal fired boiler  7 , and is heated by the coal fired boiler  7  so as to change to a steam  2 . Then, the steam  2  flows into the steam turbine  1 . When the third feed water  36  is not circulated for some reason or other, the valves  37  and  38  are totally closed. Since a flow rate of the third feed water  36  is sufficiently smaller than a flow rate of the second feed water  35 , even if the flow rate of the steam  2  somewhat lowers, the steam turbine  1  can be operated. 
     Similarly to the embodiment shown in  FIG. 1 , since all the steam constitutes the Rankine cycle of a high temperature and a high pressure, an efficiency according to this embodiment is equal to the technique shown in  FIG. 13 . In addition, as compared with a case in which the technique shown in  FIG. 13  and the technique shown in  FIG. 15  separately exist, an output of this embodiment is large and an efficiency is high even if the same received heat quantity is generated. Thus, a highly efficient power generation can be carried out by using the heat from the waste boiler  18  which from which a highly efficient power generation was impossible. 
     The structure shown in  FIG. 5  is nothing more than an example, and the merging point  34  at which the second feed water  35  and the third feed water  36  merge with each other may not be located between the most downstream feed water heater and the coal fired boiler  7 , but may be a middle location of the group of two or more feed water heaters  9 . Namely, the feed water heater may be provided downstream of the merging point  34 . In addition, the number of the feed water heaters  9  may be one. 
     Further, the one or more feed water heaters  9  may be disposed not only on an upstream side of the diverging point of the second feed water  35  and the third feed water  36 , but also on a downstream side thereof. 
     Seventh Embodiment 
     Next, the steam turbine plant according to a seventh embodiment is described with reference to  FIG. 6 . 
     In the steam turbine plant shown in  FIG. 6 , the same part as that of the steam turbine plant shown in  FIG. 5  is shown by the same reference number and detailed description thereof is omitted. 
     As shown in  FIG. 6 , there is installed a heater  47  configured to heat a steam  2  by a geothermal steam  19 . According to this embodiment, the geothermal steam  19  (third heat source) directly flows into the heater  47 . A third feed water  36  flows into the heater  47 , and is heated by the geothermal steam  19  so as to have a higher temperature. Since a pressure of the third feed water  36  is equal to a pressure of a second feed water  35  for a high-temperature high-pressure turbine, the third feed water  36  does not basically boil. Thereafter, the third feed water  36  flows into an outlet or a middle location of a group of feed water heaters  9 , and merges with the second feed water  35  which has been heated by the feed water heater  9  disposed on an upstream thereof. A temperature of the third feed water  36  does not raise up to a temperature of the geothermal steam  19 . It is preferable that the merging point  34  is located such that the temperature of the second feed water  35  and the temperature of the third feed water  36  are substantially equal to each other, but it is not a must. 
     A flow rate and a temperature of the geothermal steam  19  may considerably vary, but a property of the steam  2  flowing into a steam turbine  1  should not considerably vary. In a general steam turbine plant, a temperature and a pressure of the steam  2  are measured, and the temperature and the pressure should not considerably vary. In a general steam turbine plant, a flow rate of the steam is obtained by measuring a flow rate of a water  42 , for example, and the flow rate of the steam  2  should not considerably vary. For this reason, an output of the feed pump  6  is adjusted so as to adjust a flow rate and a pressure of the feed water  42 , a flow rate ratio between the second feed water  35  and the third feed water  36  is adjusted by adjusting opening degrees of valves  37  and  38 , in order that the temperature, the pressure and the flow rate of the steam  2  do not considerably vary. At this time, although not shown, a flow-rate adjusting valve may be installed on a downstream of the feed pump  6 , so as to adjust the flow rate and the pressure of the feed water  42  by adjusting an opening degree of the flow-rate adjuting valve. In addition, it is preferable that an output of the coal fired boiler  7  is increased or decreased, and that, depending on cases, a flow rate of the geothermal steam  19  is increased or decreased by a not-shown flow-rate adjusting valve. A pressure of the third feed water  36 , which is adjusted by the feed pump  6 , is a pressure for a high-temperature high-pressure turbine similarly to the technique shown in  FIG. 13 . Thus, the pressure of the third feed water  36  is higher than a pressure of the geothermal steam  19  in the technique shown in  FIG. 16 . Therefore, the third feed water  36  does not boil even partially. A merging point  34  is shown by m in  FIG. 18 . If there is the feed water heater  9  downstream of the merging point  34 , the merged water is heated by the same. After that, the merged water flows into the coal fired boiler  7 , and is heated by the coal fired boiler  7  so as to change to a steam  2 . Then, the steam  2  flows into the steam turbine  1 . When the third feed water  36  is not circulated for some reason or other, the valves  37  and  38  are totally closed. Since a flow rate of the third feed water  36  is sufficiently smaller than a flow rate of the second feed water  35 , even if the flow rate of the steam  2  somewhat lowers, the steam turbine  1  can be operated. 
     In the technique shown in  FIG. 16 , a temperature of the steam  2  separated by a steam separator  45  is the same as a temperature of the geothermal steam  19 . On the other hand, according to this embodiment, since the third feed water  36  is heated by the geothermal steam  19 , a temperature of the third feed water  36  is lower than the temperature of the geothermal steam  19 . However, since a heat of the hot water  20 , which is thrown away in the technique shown in  FIG. 16 , is recovered in this embodiment, a heat recovery quantity from the geothermal steam  19  is larger according to this embodiment. In addition, similar to the embodiment shown in  FIG. 5 , since all the steam constitutes the Rankine cycle of a high temperature and a high pressure, an efficiency according to this embodiment is equal to the technique shown in  FIG. 13 . In addition, as compared with a case in which the technique shown in  FIG. 13  and the technique shown in  FIG. 15  separately exist, an output of this embodiment is large and an efficiency is high even if the same received heat quantity is generated. Thus, a highly efficient power generation can be carried out by using the heat from the waste boiler  18  from which a highly efficient power generation was impossible. 
     The structure shown in  FIG. 6  is nothing more than an example, and the merging point  34  at which the second feed water  35  and the third feed water  36  merge with each other may not be located between the most downstream feed water heater and the coal fired boiler  7 , but may be a middle location of the group of two or more feed water heaters  9 . Namely, the feed water heater may be provided downstream of the merging point  34 . In addition, the number of the feed water heaters  9  may be one. 
     Further, the one or more feed water heaters  9  may be disposed not only on an upstream side of the diverging point of the second feed water  35  and the third feed water  36 , but also on a downstream side thereof. 
     Eighth Embodiment 
     Next, the steam turbine plant according to an eighth embodiment is described with reference to  FIG. 7 . 
     In the steam turbine plant shown in  FIG. 7 , the same part as that of the steam turbine plant shown in  FIG. 5  is shown by the same reference number and detailed description thereof is omitted. 
     As shown in  FIG. 7 , a heater  47  is installed. The heater  47  shown in  FIG. 7  is the heater  47  configured to heat a third feed water  36  by a heat recovery water (third heat source)  40  which recovers an industrial exhaust heat. A temperature of the heat recovery water  40  upon recovery of the industrial exhaust heat is lower, as a circulation flow rate thereof is larger. It is preferable that the flow rate of the heat recovery water  40  is higher than a flow rate of a feed water  42 . The third feed water  36  flows into the heater  47 , and is heated by the heat recovery water  40  so as to have a higher temperature. After that, the third feed water  36  flows into an outlet or a middle location of a group of feed water heaters  9 , and merges with a second feed water  35 , which has been heated by the feed water heater  9  disposed on an upstream thereof. A temperature of the third feed water  36  does not raise up to a temperature of the geothermal steam  19 . It is preferable that the merging point  34  is located such that the temperature of the second feed water  35  and the temperature of the third feed water  36  are substantially equal to each other, but it is not a must. 
     A heat quantity of the industrial steam may considerably vary, but a property of the steam  2  flowing into the steam turbine  1  should not considerably vary. In a general steam turbine plant, a temperature and a pressure of the steam  2  are measured, and the temperature and the pressure should not considerably vary. In a general steam turbine plant, a flow rate of the steam is obtained by measuring a flow rate of the water  42 , for example, and the flow rate of the steam  2  should not considerably vary. 
     For this reason, an output of the feed pump  6  is adjusted so as to adjust a flow rate and a pressure of the feed water  42 , and a flow rate ratio between the second feed water  35  and the third feed water  36  is adjusted by adjusting opening degrees of valves  37  and  38 , in order that the temperature, the pressure and the flow rate of the steam  2  do not considerably vary. In addition, it is preferable that an output of a coal fired boiler  7  is increased or decreased, and that, depending on cases, a flow rate of the heat recovery water  40  may be increased or decreased by adjusting an output of a recovery water pump  41 . At this time, although not shown, a flow-rate adjusting valve may be installed on a downstream of the feed pump  6 , so as to adjust the flow rate and the pressure of the feed water  42  by adjusting an opening degree of the flow-rate adjusting valve. 
     As shown in  FIG. 7 , if there is the feed water heater  9  downstream of a merging point  34 , a merged water is heated by the same. After that, the merged water flows into the coal fired boiler  7 , and is heated by the coal fired boiler  7  so as to change to a steam  2 . Then, the steam  2  flows into the steam turbine  1 . In  FIG. 18 , the water is heated in parallel by two kinds of heat sources from b to n, and is heated by one kind of heat source from n to i. When the third feed water  36  is not circulated through the heater  47  for some reason or other, the valves  37  and  38  are totally closed. In general, since a steam flow rate in the waste power generation is sufficiently smaller than a steam flow rate in the combined cycle, even if the flow rate of the steam  2  somewhat lowers, the steam turbine  1  can be operated. 
     As the Rankine cycle, a received heat quantity is increased by a heat received from the heat recovery water  40 , so that a flow rate of the steam  2  is increased to increase an output, while a steam turbine inlet temperature is unchanged. An efficiency of the Rankine cycle is determined only by the area ratio in the TS line diagram, regardless of a flow rate. Although a temperature difference between an extracted steam  8  and the second feed water  35  slightly varies, all the steam constitutes the Rankine cycle of a high temperature and a high pressure. Thus, an efficiency according to the eighth embodiment is equal to the first conventional technique. A highly efficient power generation can be carried out by using the industrial exhaust heat discharged without being efficiently used. 
     The structure shown in  FIG. 7  is nothing more than an example, and the merging point  34  at which the second feed water  35  and the third feed water  36  merge with each other may not be a middle location of the group of two or more feed water heaters  9 , but may be located between the most downstream feed water heater and the coal fired boiler  7 . In addition, the number of the feed water heaters  9  may be one. 
     Further, the one or more feed water heaters  9  may be disposed not only on an upstream side of the diverging point of the second feed water  35  and the third feed water  36 , but also on a downstream side thereof. 
     Ninth Embodiment 
     Next, the steam turbine plant according to a ninth embodiment is described with reference to  FIG. 7 . 
     In the eighth embodiment, the heat recovery water  40  recovers the industrial exhaust heat. On the other hand, in this embodiment, the heat recovery water  40  recovers all or a part of an exhaust heat of a fuel battery or an internal combustion engine  46 . Herein, the internal combustion engine means a gas engine or a diesel engine, for example. When the fuel battery or the internal combustion engine  46  generates power by using a fossil fuel, a large amount of exhaust heat is generated. The exhaust heat of the large-sized fuel battery or the large-sized internal combustion engine  46 , which generates power of a large capacity, is recovered by the heat recovery water  40 . In general, the heat recovery water  40  is variously used so that a temperature thereof lowers, and the heat recovery water  40  is finally released to an atmospheric air from a cooling tower so as to be circulated. The heat recovery water  40  is caused to circulate, not through the cooling tower, but through the heater  47 . At this time, the heat recovery water  40  may not be variously used but may be caused to circulate directly through the heater  47 . A temperature of the heat recovery water  40  upon recovery of the industrial exhaust heat is lower, as a circulation flow rate thereof is larger. It is preferable that the flow rate of the heat recovery water  40  is higher than a flow rate of a feed water  42 . Since a pressure of the heat recovery water  40 , which is a pressure for a high-temperature high-pressure turbine, is high, the heat recovery water  40  is not generally heated to a temperature as a boiling point at its pressure. A heat quantity of the exhaust heat of the fuel battery or the internal combustion engine  46  may vary depending on an operation of the fuel battery or the internal combustion engine  46 , but a property of the steam  2  flowing into the steam turbine  1  should not considerably vary. In a general steam turbine plant, a temperature and a pressure of the steam  2  are measured, and the temperature and the pressure should not considerably vary. In a general steam turbine plant, a flow rate of the steam is obtained by measuring a flow rate of the water  42 , for example, and the flow rate of the steam  2  should not considerably vary. 
     For this reason, an output of the feed pump  6  is adjusted so as to adjust a flow rate and a pressure of the feed water  42 , and a flow rate ratio between a second feed water  35  and a third feed water  36  is adjusted by adjusting opening degrees of valves  37  and  38 , in order that the temperature, the pressure and the flow rate of the steam  2  do not considerably vary. In addition, it is preferable that an output of a coal fired boiler  7  is increased or decreased, and that, depending on cases, a flow rate of the heat recovery water  40  is increased or decreased by adjusting an output of a recovery water pump  41 . At this time, although not shown, a flow-rate adjusting valve may be installed on a downstream of a feed pump  6 , so as to adjust the flow rate and the pressure of the feed water  42  by adjusting an opening degree of the flow-rate adjusting valve. 
     According to this embodiment, a highly efficient power generation can be carried out by using all or a part of the exhaust heat of the fuel battery  46  which is discharged without being efficiently used. 
     The structure shown in  FIG. 7  is nothing more than an example, and the merging point  34  at which the second feed water  35  and the third feed water  36  merge with each other may not be a middle location of the group of two or more feed water heaters  9 , but may be located between the most downstream feed water heater and the coal fired boiler  7 . In addition, the number of the feed water heaters  9  may be one. 
     Further, the one or more feed water heaters  9  may be disposed not only on an upstream side of the diverging point of the second feed water  35  and the third feed water  36 , but also on a downstream side thereof. 
     Tenth Embodiment 
     Next, the steam turbine plant according to a tenth embodiment is described with reference to  FIG. 8 . 
     In the steam turbine plant shown in  FIG. 8 , the same part as that of the steam turbine plant shown in  FIG. 7  is shown by the same reference number and detailed description thereof is omitted. 
     As shown in  FIG. 8 , a heater  47  is disposed in series with a group of feed water heaters  9  with respect to a feed water  42 . In this embodiment, the heater  47  is configured to heat the feed water  42  by a heat recovery water  40  which recovers an industrial exhaust heat. The feed water  42  is transported to the heater  47 , and is heated therein by the heat recovery water  40  so as to have a higher temperature. The feed water  42  flowing out from the heater  47  sequentially flows into the group of feed water heaters  9  and a coal fired boiler  7 , and is heated respectively by an extracted steam  8  and an exhaust combustion gas  13 , so as to become a steam  2 . 
     Since the industrial exhaust heat has a relatively lower temperature but an amount thereof is large, it is preferable that heat is exchanged between the industrial exhaust heat and the feed water  42 , while a temperature difference between the industrial exhaust heat and the feed water  42  is sufficiently maintained. The arrangement of the heater is effective in terms thereof. 
     A heat quantity of the industrial exhaust heat may considerably vary, but a property of the steam  2  flowing into the steam turbine  1  should not considerably vary. In a general steam turbine plant, a temperature and a pressure of the steam  2  are measured, and the temperature and the pressure should not considerably vary. In a general steam turbine plant, a flow rate of the steam is obtained by measuring a flow rate of the water  42 , for example, and the flow rate of the steam  2  should not considerably vary. For this reason, it is preferable that an output of the feed pump  6  is adjusted so as to adjust a flow rate and a pressure of the feed water  42 , that an output of the coal fired boiler is increased or decreased, and that, depending on cases, a flow rate of the heat recovery water  40  is increased or decreased by adjusting an output of a recovery water pump  41 , in order that the temperature, the pressure and the flow rate of the steam  2  do not considerably vary. At this time, although not shown, a flow-rate adjusting valve may be installed on a downstream of the feed pump  6 , so as to adjust the flow rate and the pressure of the feed water  42  by adjusting an opening degree of the flow-rate adjusting valve. 
     Although the industrial exhaust heat is used in the tenth embodiment, a heat to be used is not limited thereto. 
     In addition, the heater  47  may be disposed on a middle location of the group of two or more feed water heaters  9 , or may be disposed on a downstream side of the group of the feed water heaters  9 . 
     Further, the one or more feed water heaters  9  may be disposed not only on an upstream side of the diverging point of the second feed water  35  and the third feed water  36 , but also on a downstream side thereof. 
     Eleventh Embodiment 
     Next, the steam turbine plant according to an eleventh embodiment is described with reference to  FIG. 9 . 
     In the steam turbine plant shown in  FIG. 9 , the same part as that of the steam turbine plant shown in  FIG. 8  is shown by the same reference number and detailed description thereof is omitted. 
     As shown in  FIG. 9 , a waste boiler  18  is installed as a heater. In  FIG. 9 , no air is extracted from a steam turbine  1 , and no feed water heater  9  is included. A feed water  42  flows into the waste boiler  18  as a heater, and is heated by a waste exhaust combustion gas  44  so as to have a higher temperature. A temperature of an outlet water of the waste boiler  18  is restricted in terms of a high temperature corrosion. Since a pressure of the outlet water is higher than a pressure in a waste power generation, the outlet water does not basically boil. Thus, the waste boiler  18  functions only as a hot water boiler. 
     A pressure of a working fluid of the waste boiler  18 , which is adjusted by a pump, is a pressure for a high-temperature high-pressure turbine similarly to the technique shown in  FIG. 14 . Thus, the pressure of the working fluid of the waste boiler  18  is higher than that in the technique shown in  FIG. 15 . In  FIG. 18 , an outlet of the waste boiler  18  is shown by  1 . 
     Thereafter, the feed water  42  flows into a coal fired boiler  7 , and is heated by the coal fired boiler  7 . Then, the feed water  42  flows into the steam turbine  1 . In the waste boiler  18 , a composition of the waste  11  and an amount of the waste  11  to be treated may considerably vary, but a property of the steam  2  flowing into the steam turbine  1  should not considerably vary. In a general steam turbine plant, a temperature and a pressure of the steam  2  are measured, and the temperature and the pressure should not considerably vary. In addition, in a general steam turbine plant, a flow rate of the steam  2  is obtained by measuring a flow rate of the feed water  42 , for example, and the flow rate of the steam  2  should not considerably vary. 
     For this reason, it is preferable that an output of the feed pump  6  is adjusted so as to adjust a flow rate and a pressure of the feed water  42 , that an output of the coal fired boiler  7  is increased or decreased, and that, depending on cases, an amount of the waste  11  to be treated is increased or decreased, in order that the temperature, the pressure and the flow rate of the steam  2  do not considerably vary. At this time, although not shown, a flow-rate adjusting valve may be installed on a downstream of the feed pump  6 , so as to adjust the flow rate and the pressure of the feed water  42  by adjusting an opening degree of the flow-rate adjusting valve. 
     Similarly to the embodiment shown in  FIG. 8 , since all the steam constitutes the Rankine cycle of a high temperature and a high pressure, an efficiency according to this embodiment is equal to the technique shown in  FIG. 13 . This embodiment can be applied to the steam turbine  1  which does not extract air. 
     Although the waste boiler  18  is used as a heater in the eleventh embodiment, a water may be heated by using a heat derived from another heat source. 
     Twelfth Embodiment 
     Next, the steam turbine plant according to a twelfth embodiment is described with reference to  FIG. 10 . 
     In the steam turbine plant shown in  FIG. 10 , the same part as that of the steam turbine plant shown in  FIG. 1  is shown by the same reference number and detailed description thereof is omitted. 
     As shown in  FIG. 10 , a heating medium  24  (fourth heat source) receives a radiant heat of solar light so as to be heated in a solar heat collector  23 . The heated heating medium  24  is diverged into two. One heating medium flows into a solar heat heater  22 , and the other heating medium flows into a heat storage tank  25 . A heating medium pump  27  is adjusted such that the heating medium flows in a direction drawn by a solid line on the left side of the heat storage tank  25 . A part of the heating medium  24  flows into the solar heat heater to heat a feed water  42  to lose its temperature, and flows out therefrom. When a remaining part of the heating medium  24 , which has heated the feed water  42 , flows into the heat storage tank  25 , the heating medium, which has been already therein and has a lower temperature, flows out from the heat storage tank  25 , so that the heating medium  24  of a higher temperature is stored in the heat storage tank  25  in the end. After the heating medium  24  has been stored, valves  30  and  31  are totally closed. The heating medium  24  is transported by heating medium pumps  26  and  27 . The feed water  42  is transported to the solar heat heater by a feed pump  6 , and is heated therein so as to change to a steam  2 . During a nighttime when no solar light exists or a time zone when only weak solar light exists, valves  28  and  29  are closed and the heating medium pump  26  is stopped, while the valves  30  and  31  are opened and the heating medium pump  27  is operated, so that the heating medium flows in a direction drawn by dotted lines on the right side of the heat storage tank  25 . The feed water  24  is heated by circulating the heating medium  24  between the heat storage tank  25  and the solar heat heater  22 , without circulating the heating medium  24  through the solar heat collector  23 . The feed water  42  heated by the solar heat is sent to a steam turbine  1  so as to drive the steam turbine  1 . 
     As described above, the steam turbine  1  is a turbine that is driven by a steam manufactured by a heat source derived from solar heat (fourth heat source). In the steam turbine  1 , there is installed a heater  47 , which is configured to heat a third feed water  36  by a heat recovery water (fifth heat source)  40  that recovers an industrial exhaust heat. A temperature of the heat recovery water  40  upon recovery of the industrial exhaust heat is lower, as a circulation flow rate thereof is larger. It is preferable that the flow rate of the heat recovery water  40  is higher than a flow rate of a feed water  42 . Since a pressure of the heat recovery water  40 , which is a pressure for a high-temperature high-pressure turbine, is high, the heat recovery water  40  is not generally heated to a temperature as a boiling point at its pressure. When solar heat can be sufficiently obtained such as a daytime, the steam turbine plant is operated in this manner. 
     The feed water  42  is diverged into the second feed water  35  and the third feed water  36 . The second feed water  35  is transported to a group of feed water heaters  9 , and is heated therein by an extracted steam  8  so as to have a higher temperature. The third feed water  36  flows into the heater  47 , and is heated by the heat recovery water  40  so as to have a higher temperature. Thereafter, the third feed water  36  flows into a middle location or a downstream of the group of the feed water heaters  9 , and merges with the second feed water  35  which has been heated by the feed water heater  9  disposed on an upstream of a merging point  34 . 
     It is preferable that the merging point  34  is located such that the temperature of the second feed water  35  and the temperature of the third feed water  36  are substantially equal to each other, but it is not a must. Both of a heat quantity of a solar heat and a heat quantity of an industrial exhaust heat may considerably vary, but a property of the steam  2  flowing into the steam turbine  1  should not considerably vary. In a general steam turbine plant, a temperature and a pressure of the steam  2  are measured, and the temperature and the pressure should not considerably vary. In a general steam turbine plant, a flow rate of the steam is obtained by measuring a flow rate of the water  42 , for example, and the flow rate of the steam  2  should not considerably vary. 
     For this reason, it is preferable that flow rates of the heating medium are increased or decreased by adjusting outputs of the heating medium pumps  26  and  27 , that an output of the feed pump  6  is adjusted so as to adjust a flow rate and a pressure of the feed water  42 , that a flow rate ratio between the second feed water  35  and the third feed water  36  is adjusted by adjusting opening degrees of the valves  37  and  38 , and that, depending on cases, a flow rate of the heat recovery water  40  is increased or decreased by adjusting an output of a recovery water pump  41 , in order that the temperature, the pressure and the flow rate of the steam  2  do not considerably vary. At this time, although not shown, a flow-rate adjusting valve may be installed on a downstream of the feed pump  6 , so as to adjust the flow rate and the pressure of the feed water  42  by adjusting an opening degree of the flow-rate adjusting valve. 
     If there is the feed water heater  9  downstream of the merging point  34 , the merged water is heated by the same. After that, the merged water flows into the solar heat heater  22 , and is heated by the solar heat heater  22  so as to change to a steam  2 . Then, the steam  2  flows into the steam turbine  1 . When the third feed water  36  is not circulated through the heater  47  for some reason or other, the valves  37  and  38  are totally closed. Since a flow rate of the third feed water  36  is sufficiently smaller than a flow rate of the second feed water  35 , even if the flow rate of the steam  2  somewhat lowers, the steam turbine  1  can be operated. During a nighttime when a solar heat is not obtained at ail or is obtained insufficiently, an operation similar to the fifth conventional technique is carried out. 
     As the Rankine cycle, a received heat quantity is increased by a heat received from the heat recovery water  40 , so that a flow rate of the steam  2  is increased to increase an output, while a steam turbine inlet temperature is unchanged. An efficiency of the Rankine cycle is determined only by the area ratio in the TS line diagram, regardless of a flow rate. Since all the steam constitutes the Rankine cycle of a high temperature and a high pressure, an efficiency according to the this embodiment is equal to the technique shown in  FIG. 17 . 
     According to this embodiment, a power generation can be carried out, without lowering an efficiency from the technique shown in  FIG. 17 , by using the industrial exhaust heat which is discharged without being efficiently used. 
     The heat storage tank  25  may be omitted. However, in this case, the steam turbine plant cannot be operated only when it can receive a solar heat sufficiently. The structure shown in  FIG. 10  is nothing more than an example, and the merging point  34  at which the second feed water  35  and the third feed water  36  merge with each other may not be a middle location of the group of two or more feed water heaters  9 , but may be located between the most downstream feed water heater and the coal fired boiler  7 . In addition, the number of the feed water heaters  9  may be one. 
     Further, the one or more feed water heaters  9  may be disposed not only on an upstream side of the diverging point of the second feed water  35  and the third feed water  36 , but also on a downstream side thereof. In this case, only one feed water heaters  9  may be provided. 
     An effect of this embodiment is described with reference to  FIG. 19 . As shown in  FIG. 19(   b ), a feed water is heated from a condensation temperature to a steam turbine inlet temperature in the following manner. The feed water of a lower temperature zone is heated by a second heating source using an extracted steam, and the heat recovery water  40  which is a heat source other than a solar heat (fifth heat source). The feed water of a higher temperature zone is heated by the solar heat heater  22  using a heat source derived from a solar heat (fourth heat source). 
     In this manner, since the feed water of the lower temperature zone is heated also by the heat recovery water, and a high temperature steam flowing into the steam turbine  1  is reliably generated by the solar heat heater  22  derived from a solar heat, the heat recovery water of a lower temperature, which has not been used heretofore in the steam turbine  1 , can be efficiently used to improve a power generation efficiency. 
     Thirteenth Embodiment 
     Next, the steam turbine plant according to a thirteenth embodiment is described with reference to  FIG. 10 . 
     In the twelfth embodiment, the heat recovery water  40  recovers the industrial exhaust heat. On the other hand, in this embodiment, the heat recovery water  40  recovers all or a part of an exhaust heat of a fuel battery or an internal combustion engine  46 . When the fuel battery or the internal combustion engine  46  generates power by using a fossil fuel, a large amount of exhaust heat is generated. The exhaust heat of the large-sized fuel battery or the large-sized internal combustion engine  46 , which generates power of a large capacity, is recovered by the heat recovery water  40 . In general, the heat recovery water (fifth heat source)  40  is variously used so that a temperature thereof lowers, and the heat recovery water  40  is finally released to an atmospheric air from a cooling tower so as to be circulated. The heat recovery water  40  is caused to circulate, not through the cooling tower, but through a heater  47 . At this time, the heat recovery water  40  may not be variously used but may be caused to circulate directly through the heater  47 . A temperature of the heat recovery water  40  upon recovery of the industrial exhaust heat is lower, as a circulation flow rate thereof is larger. It is preferable that the flow rate of the heat recovery water  40  is higher than a flow rate of a feed water  42 . 
     Since a pressure of the heat recovery water  40 , which is a pressure for a high-temperature high-pressure turbine, is high, the heat recovery water  40  is not generally heated to a temperature as a boiling point at its pressure. A heat quantity of solar heat may considerably vary, and a heat quantity of the exhaust heat of the fuel battery or the internal combustion engine  46  may vary depending on an operation of the fuel battery or the internal combustion engine  46 , but a property of the steam  2  flowing into the steam turbine  1  should not considerably vary. In a general steam turbine plant, a temperature and a pressure of the steam  2  are measured, and the temperature and the pressure should not considerably vary. In a general steam turbine plant, a flow rate of the steam is obtained by measuring a flow rate of a water  42 , for example, and the flow rate of the steam  2  should not considerably vary. 
     For this reason, it is preferable that flow rates of the heating medium are increased or decreased by adjusting outputs of heating medium pumps  26  and  27 , that an output of the feed pump  6  is adjusted so as to adjust a flow rate and a pressure of the feed water  42 , that a flow rate ratio between the second feed water  35  and the third feed water  36  is adjusted by adjusting opening degrees of valves  37  and  38 , and that, depending on cases, a flow rate of the heat recovery water  40  is increased or decreased by adjusting an output of a recovery water pump  41 , in order that the temperature, the pressure and the flow rate of the steam  2  do not considerably vary. At this time, although not shown, a flow-rate adjusting valve may be installed on a downstream of the feed pump  6 , so as to adjust the flow rate and the pressure of the feed water  42  by adjusting an opening degree of the flow-rate adjusting valve. 
     According to this embodiment, a highly efficient power generation can be carried out by using all or a part of the exhaust heat of the fuel battery  46  which is discharged without being efficiently used. 
     A heat storage tank  25  may be omitted. However, in this case, the steam turbine plant can be operated only when it can receive a solar heat sufficiently. The structure shown in  FIG. 10  is nothing more than an example, and the merging point  34  at which the second feed water  35  and the third feed water  36  merge with each other may not be a middle location of the group of two or more feed water heaters  9 , but may be located between the most downstream feed water heater and the solar heat heater  22 . In addition, the number of the feed water heaters  9  may be one. 
     Further, the one or more feed water heaters  9  may be disposed not only on an upstream side of the diverging point of the second feed water  35  and the third feed water  36 , but also on a downstream side thereof. Only one feed water heaters  9  may be provided. 
     Furthermore, although there is shown in  FIG. 10  the example in which the heat recovery water  40  is heated by an exhaust heat source  39 , or the fuel battery or the internal combustion engine  46 , the present invention is not limited thereto. The heat recovery water  40  may be heated by an exhaust gas of the gas turbine, and the heater  47  may be heated by the heat recovery water  40 . 
     Fourteenth Embodiment 
     Next, the steam turbine plant according to a fourteenth embodiment is described with reference to  FIG. 11 . 
     In the steam turbine plant shown in  FIG. 11 , the same part as that of the steam turbine plant shown in  FIG. 10  is shown by the same reference number and detailed description thereof is omitted. 
     As shown in  FIG. 11 , a heater  47  is disposed in series with a solar heat heater  22  and a group of feed water heaters  9 , with respect to a feed water  42 . As shown in  FIG. 11 , the heater  47  is configured to heat a steam  2  by a heat recovery water  40  which recovers an industrial exhaust heat. A feed water  42  is transported to the heater  47 , and is heated therein by the heat recovery water  40  so as to have a higher temperature. The feed water  42  flowing out from the heater  47  sequentially flows into the group of the feed water heaters  9  and the solar heat heater  22 , and is heated respectively by an extracted steam  9  and a heating medium  24 , so as to become a steam  2 . 
     Since the industrial exhaust heat has a relatively lower temperature but an amount thereof is large, it is preferable that heat is exchanged between the industrial exhaust heat and the feed water  42 , while a temperature difference between the industrial exhaust heat and the feed water  42  is sufficiently maintained. The arrangement of the heater  47  is effective in terms thereof. 
     Both of a heat quantity of a solar heat and a heat quantity of an industrial exhaust heat may considerably vary, but a property of the steam  2  flowing into the steam turbine  1  should not considerably vary. In a general steam turbine plant, a temperature and a pressure of the steam  2  are measured, and the temperature and the pressure should not considerably vary. In a general steam turbine plant, a flow rate of the steam is obtained by measuring a flow rate of the water  42 , for example, and the flow rate of the steam  2  should not considerably vary. 
     For this reason, it is preferable that flow rates of the heating medium are increased or decreased by adjusting outputs of heating medium pumps  26  and  27 , that an output of a feed pump is adjusted so as to adjust a flow rate and a pressure of the feed water  42 , and that, depending on cases, a flow rate of the heat recovery water  40  is increased or decreased by adjusting an output of a recovery water pump  41 , in order that the temperature, the pressure and the flow rate of the steam  2  do not considerably vary. At this time, although not shown, a flow-rate adjusting valve may be installed on a downstream of the feed pump  6 , so as to adjust the flow rate and the pressure of the feed water  42  by adjusting an opening degree of the flow-rate adjusting valve. 
     Although the industrial exhaust heat is used in this embodiment, a heat to be used is not limited thereto. In addition, similarly to the eleventh embodiment, a feed water heater may be omitted. Moreover, a heat storage tank  25  may be omitted. However, in this case, the steam turbine plant can be operated only when it can receive a solar heat sufficiently. 
     In addition, the heater  47  may be disposed on a middle location of the group of two or more feed water heaters  9 , or may be disposed on a downstream side of the group of the feed water heaters  9 . 
     Further, the one or more feed water heaters  9  may be disposed not only on an upstream side of the diverging point of the second feed water  35  and the third feed water  36 , but also on a downstream side thereof. 
     Fifteenth Embodiment 
     Next, the steam turbine plant according to a fifteenth embodiment is described with reference to  FIG. 12 . 
     In the steam turbine plant shown in  FIG. 12 , the same part as that of the steam turbine plant shown in  FIG. 10  is shown by the same reference number and detailed description thereof is omitted. 
     During a daytime or the like when a solar heat can be sufficiently obtained, the steam turbine plant is operated in the following manner. A feed water  42  is diverged into a second feed water  35  and a third feed water  36 . The second feed water  35  is transported to a solar heat heater  22 , and is heated therein so as to have a higher temperature. The third feed water  36  flows into a heater  47 , and is heated by a heat recovery water  40  so as to have a higher temperature. After that, the third feed water  36  flows into a middle location of the solar heat heater  22  and merges with the second feed water  35 , which has been heated at a position in the solar heat hater  22  that is upstream of a merging point  34 . 
     It is preferable that the merging point  34  is located such that the temperature of the second feed water  35  and the temperature of the third feed water  36  are substantially equal to each other, but it is not a must. Both of a heat quantity of a solar heat and a heat quantity of an industrial exhaust heat may considerably vary, but a property of the steam  2  flowing into the steam turbine  1  should not considerably vary. In a general steam turbine plant, a temperature and a pressure of the steam  2  are measured, and the temperature and the pressure should not considerably vary. In a general steam turbine plant, a flow rate of the steam is obtained by measuring a flow rate of the water  42 , for example, and the flow rate of the steam  2  should not considerably vary. 
     For this reason, it is preferable that flow rates of the heating medium are increased or decreased by adjusting outputs of heating medium pumps  26  and  27 , that an output of the feed pump  6  is adjusted so as to adjust a flow rate and a pressure of the feed water  42 , that a flow rate ratio between the second feed water  35  and the third feed water  36  is adjusted by adjusting opening degrees of valves  37  and  38 , and that, depending on cases, a flow rate of the heat recovery water  40  is increased or decreased by adjusting an output of a recovery water pump  41 , in order that the temperature, the pressure and the flow rate of the steam  2  do not considerably vary. At this time, although not shown, a flow-rate adjusting valve may be installed on a downstream of the feed pump  6 , so as to adjust the flow rate and the pressure of the feed water  42  by adjusting an opening degree of the flow-rate adjusting valve. The merged water is heated by the solar heat heater  22  at a position downstream of the merging point  34  so as to change to a steam  2 . Then, the steam  2  flows into a steam turbine  1 . When the third feed water  36  is not circulated through a heater  47  for some reason or other, the valves  37  and  38  are totally closed. Since a flow rate of the third feed water  36  is sufficiently smaller than a flow rate of the second feed water  35 , even if the flow rate of the steam  2  somewhat lowers, the steam turbine  1  can be operated. During a nighttime when a solar heat is not obtained at all or is obtained insufficiently, an operation similar to the seventeenth technique is carried out. 
     As the Rankine cycle, a received heat quantity is increased by a heat received from the heat recovery water  40 , so that a flow rate of the steam  2  is increased to increase an output, while a steam turbine inlet temperature is unchanged. An efficiency of the Rankine cycle is determined only by the area ratio in the TS line diagram, regardless of a flow rate. Since all the steam constitutes the Rankine cycle of a high temperature and a high pressure, an efficiency according to the this embodiment is equal to the technique shown in  FIG. 17 . 
     According to this embodiment, a power generation can be carried out, without lowering an efficiency from the technique shown in  FIG. 17 , by using the industrial exhaust heat which is discharged without being efficiently used. 
     In  FIG. 12 , although an extracted steam  9  from the steam turbine  1  and a feed water heater  8  do not exist, they may exist. In addition, a heat storage tank  25  may be omitted. However, in this case, the steam turbine plant can be operated only when it can receive a solar heat sufficiently. 
     The aforementioned above embodiments are taken by way of examples, and the scope of the invention is not limited thereto.
       1  Steam turbine     2  Steam     3  Turbine exhaust air     4  Condenser     5  Condensation     6  Feed pump     7  Coal fired boiler     8  Extracted steam     9  Feed water heater     10  Drainage water     11  Waste     12  Combustion air     13  Exhaust combustion gas     14  Gas turbine exhaust air     15  Exhaust heat boiler     18  Waste boiler     19  Geothermal steam     20  Hot water     21  Ground     22  Solar heat heater     23  Solar heat collector     24  Heating medium     25  Heat storage tank     26  Heating medium pump     27  Heating medium pump     28  Valve     29  Valve     30  Valve     31  Valve     32  Saturated water line     33  Saturated steam line     34  Merging point     35  Second feed water     36  Third feed water     37  Valve     38  Valve     39  Exhaust heat source     40  Heat recovery water     41  Heat recovery water pump     42  Feed water     43  Coal     44  Waste exhaust combustion gas     46  Fuel battery or internal combustion engine     47  Heater