JP2019100617A - Circulation type boiler system, fire power generation plant, and exhaust heat recovery method - Google Patents

Abstract

To provide a circulation type boiler system which can achieve improvement of the efficiency by utilizing exhaust heat, and to provide a fire power generation plant and an exhaust heat recovery method.SOLUTION: A circulation type boiler system includes: a steam turbine 10 driven by steam S; a condenser 11 which introduces the steam S from the steam turbine 10; a cooling tower 12 which circulates water W between itself and the condenser 11 and condenses the steam S with the condenser 11 to generate the water W; a circulation type boiler 13 which evaporates the water W from the condenser 11 to introduce the water W into the steam turbine 10; a blow pipe 14 which discharges a part of the water W from the circulation type boiler 13; a heat exchanger 20 which conducts heat exchange between the water W discharged from the blow pipe 14 and the water W flowing from the condenser 11 to the circulation type boiler 13 to cause the water W introduced into the circulation type boiler 13 to recover heat; and a cooling tower introduction pipe 15 which introduces the water W that has been subject to heat exchange in the heat exchanger 20 into the cooling tower 12.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a circulating boiler system, a thermal power plant provided with the same, and an exhaust heat recovery method.

  For example, in a thermal power plant, a gas turbine combined cycle power plant is used which recovers the exhaust heat of a gas turbine and drives the steam turbine by the exhaust heat. In such a power plant, a circulating boiler is generally used. In addition to the thermal power plant, the circulating boiler is also used in conventional power plants and the like of coal-fired.

  In circulation type boilers, the upper limit of the impurity concentration of drum water is defined on the specification or in operation, and when the impurity concentration exceeds this upper limit, or when the concentration of the impurity concentration is to be kept low It is necessary to discharge drum water out of the system continuously or periodically. Drum water has high enthalpy because it is high temperature high pressure water. Therefore, when it is discharged, for example, energy loss such as a decrease in power generation efficiency with respect to unit fuel occurs, and a manufacturing cost of makeup water for replenishing water for the discharge occurs. Furthermore, by discharging the high temperature boiler water as it is, there is a possibility that the extrasystem equipment at the discharge position may be adversely affected, so it becomes necessary to provide equipment for reducing the temperature of the boiler water and drainage treatment equipment.

  Here, in the nuclear power plant described in Patent Document 1, water is converted into steam by a steam generator using heat generated in a nuclear reactor, and the steam turbine is driven by the steam to operate a generator. In this plant, the exhaust steam worked in the steam turbine is sent to the condenser and cooled by seawater etc. and then returned to the steam generator via the condenser system connecting the condenser and the steam generator. There is. At this time, in order to prevent accumulation and concentration of impurities in the steam generator, a portion of the water of the steam generator is blown down (discharged) from the steam generator, and the blown down water is condensed I'm back to. The heat of the water blown down from the steam generator is recovered by heat exchange between the water blown down from the steam generator and the water of the condensate system using a heat exchanger.

Unexamined-Japanese-Patent No. 2000-292589

  As described above, the power generation plant is required to improve the power generation efficiency, and various measures have been taken to reduce the exhaust heat. However, as described above, in the current circulation type boiler, at present, sufficient exhaust heat utilization can not be performed by discharging the drum water.

  Therefore, the present invention provides a circulating boiler system, a thermal power plant, and an exhaust heat recovery method that can further improve the efficiency by utilizing exhaust heat.

  A circulating boiler system according to an aspect of the present invention circulates a fluid between a steam turbine driven by steam, a condenser for introducing exhaust steam from the steam turbine, and the condenser. A cooling tower that condenses the exhaust steam with the condenser to generate a condensed fluid from the exhaust steam; a circulating boiler that evaporates the condensed fluid from the condenser and introduces it to the steam turbine; Heat is generated between the blow piping for discharging a part of the condensed fluid from the circulating boiler, the discharged fluid which is the condensed fluid from the blow piping, and the condensed fluid from the condenser toward the circulating boiler A heat exchanger for exchanging heat and recovering heat from the condensed fluid introduced into the circulating boiler; and a cooling tower inlet pipe for introducing the discharged fluid after heat exchange with the heat exchanger into the cooling tower; Equipped with .

  According to such a configuration, even if it is necessary to discharge a part of the condensed fluid from the circulating boiler through the blow piping due to standard or operational restrictions, the thermal energy of the discharged condensed fluid can be output to the outside of the system The condensed fluid can be recovered from the condenser toward the circulating boiler without being discarded. And it can introduce | transduce into a circulation type boiler in the state which preheated the condensed fluid with the thermal energy of the discharge fluid discharged | emitted through blow piping. Therefore, the thermal efficiency of the entire system can be improved. Furthermore, since the exhaust fluid discharged through the blow piping is introduced into the cooling tower after heat exchange in the heat exchanger without being returned to the circulating boiler, the water quality of the circulating boiler can be maintained in a clean state. In addition, since the discharge fluid discharged through the blow piping is not discharged to the outside of the system while the temperature is high, the influence of heat on the equipment outside the system can be reduced. Therefore, there is no need to install equipment for reducing the temperature of the discharged fluid discharged through the blow piping or processing equipment, and it is possible to reduce the manufacturing cost of the system and the environmental load.

  Further, in the above circulation type boiler system, the discharge fluid from the blow piping is introduced to reduce the temperature and pressure of the discharge fluid, and the discharge fluid is separated into a gas phase and a liquid phase before the liquid is separated. It may further comprise a flash tank for introducing a phase to the heat exchanger and for introducing the gas phase to the circulating boiler.

  Effluent fluid discharged through the blow piping is flushed with a flash tank to reduce temperature and pressure. Thereby, it is possible to avoid backflow when introducing the discharge fluid into the cooling tower. Also, the vapor phase can be returned to the circulating boiler after the flash tank has removed impurities from the effluent fluid in the flash tank. Therefore, by discharging through the blow piping, it is possible to reduce the supply amount of the replenishment fluid which is required when the amount of condensed fluid in the circulating boiler is reduced. Thus, the cost of the replenishment fluid can be reduced.

  In a thermal power plant according to an aspect of the present invention, exhaust gas is introduced into the circulating boiler system described above and the circulating boiler in the circulating boiler system, and heat exchange is performed between the exhaust gas and the circulating boiler. And a gas turbine to be carried out.

  In such a thermal power plant, the above-described circulation type boiler system is provided, so that the heat energy of the discharge fluid discharged from the circulation type boiler through the blow piping is not discarded to the outside of the system. Can be recovered in the form of condensed fluid going to the circulating boiler. Therefore, the thermal efficiency of the entire system can be improved. Furthermore, the exhaust fluid discharged through the blow piping can be introduced into the cooling tower after heat exchange in the heat exchanger. Therefore, the exhaust fluid containing the impurities is not introduced into the circulating boiler. Therefore, the water quality of the circulating boiler can be maintained in a clean state. In addition, since the discharge fluid discharged through the blow piping is not discharged to the outside of the system while the temperature is high, there is no need to install equipment for reducing the temperature of the discharge fluid discharged through the blow piping, and the processing equipment It is possible to reduce the production cost of the product and the environmental load.

  A thermal power plant according to one aspect of the present invention includes a steam turbine driven by steam, and a condenser for introducing exhaust steam from the steam turbine and condensing the exhaust steam to form a condensed fluid. A circulating boiler for evaporating the condensed fluid from the condenser and introducing it to the steam turbine, a blow pipe for discharging a part of the condensed fluid from the circulating boiler, and the condensation from the blow pipe A circulating boiler system having a heat exchanger for performing heat exchange between a discharge fluid, which is a fluid, and a fuel to recover heat from the fuel, and introducing exhaust gas into the circulating boiler, and And a gas turbine that exchanges heat with the circulating boiler and burns the fuel after heat recovery by the heat exchanger.

  In such a thermal power plant, the thermal energy of the discharge fluid discharged from the circulating boiler through the blow piping can be recovered to the fuel of the gas turbine without being dumped out of the system. The fuel can be introduced into the combustor in a state in which the fuel of the gas turbine is preheated by the thermal energy of the exhaust fluid discharged through the blow piping. Therefore, the thermal efficiency of the entire plant can be improved.

  In the above-mentioned thermal power plant, a fluid is circulated between the condenser and the cooling tower for condensing the exhaust steam with the condenser to generate a condensed fluid from the exhaust steam, and the heat exchange The cooling apparatus may further include a cooling tower inlet pipe for introducing the discharged fluid after heat exchange with the cooling tower into the cooling tower.

  Exhaust fluid discharged through the blow piping can be introduced into the cooling tower after heat exchange in the heat exchanger. Therefore, the exhaust fluid containing the impurities is not introduced into the circulating boiler. Therefore, the water quality of the circulating boiler can be maintained in a clean state. In addition, since the discharge fluid discharged through the blow piping is not discharged to the outside of the system while the temperature is high, there is no need to install equipment for reducing the temperature of the discharge fluid discharged through the blow piping, and the processing equipment It is possible to reduce the production cost of the product and the environmental load.

  In the above thermal power plant, a high pressure boiler, an intermediate pressure boiler, and a low pressure boiler for evaporating the condensed fluid from the condenser in parallel to each other as the circulating boiler, and the high pressure boiler as the blow piping. A high pressure blow pipe provided in the medium pressure blow pipe, a medium pressure blow pipe provided in the medium pressure boiler, and a low pressure blow pipe provided in the low pressure boiler, and the heat exchanger is provided upstream of the fuel flow The low temperature stage, the medium temperature stage, and the high temperature stage are provided from the lower side toward the downstream side, and the discharge fluid from the low pressure blow piping is introduced to the low temperature stage, and the medium pressure stage is provided with the medium pressure blow piping. The discharge fluid from the high pressure blow pipe may be introduced into the high temperature stage.

  The temperature of the discharge fluid from each boiler is different. Since the stages of the heat exchanger are provided in accordance with the temperature level of the discharge fluid, the heat energy of the discharge fluid can be used to heat the fuel efficiently in stages.

  In the above thermal power plant, a high pressure boiler, an intermediate pressure boiler, and a low pressure boiler for evaporating the condensed fluid from the condenser in parallel to each other as the circulating boiler, and the high pressure boiler as the blow piping. A high pressure blow piping provided in the medium pressure blow piping provided in the medium pressure boiler; and a low pressure blow piping provided in the low pressure boiler; the heat exchanger includes the high pressure blow piping and the middle Heat may be recovered to the fuel by the discharged fluid from the pressure blow piping.

  According to such a configuration, the thermal energy of the discharge fluid from the relatively low temperature (low enthalpy) low pressure blow piping is not recovered by the fuel, and the relatively high temperature (high enthalpy) high pressure blow piping and Only the thermal energy of the fluid discharged from the medium pressure blow piping is recovered to the fuel. Therefore, the fuel can be preheated efficiently.

  In the exhaust heat recovery method according to one aspect of the present invention, a fluid is circulated between a steam turbine driven by steam, a condenser for introducing exhaust steam from the steam turbine, and the condenser. A cooling tower that condenses the exhaust steam with the condenser to produce a condensed fluid from the exhaust steam, and a circulating boiler that evaporates the condensed fluid from the condenser and introduces it to the steam turbine A waste heat recovery method for recovering waste heat with a circulation boiler system comprising a blow piping for discharging a part of the condensed fluid from the circulation boiler, the discharge being the condensed fluid from the blow piping Heat exchange is performed between the fluid and the condensed fluid going from the water condenser to the circulating boiler, and the heat is recovered from the condensed fluid introduced into the circulating boiler, and the heat exchange Heat exchange The exhaust fluid after contains a fluid recovery step of introducing into the cooling tower.

  According to such a configuration, the thermal energy of the discharged fluid discharged from the circulating boiler through the blow piping can be recovered to the condensed fluid from the condenser toward the circulating boiler without discarding it out of the system . Therefore, the thermal efficiency of the entire system can be improved. Furthermore, the exhaust fluid discharged through the blow piping can be introduced into the cooling tower after heat exchange in the heat exchanger. Therefore, the exhaust fluid containing the impurities is not introduced into the circulating boiler. Therefore, the water quality of the circulating boiler can be maintained in a clean state. In addition, since the condensed fluid discharged through the blow piping is not discharged to the outside of the system while the temperature is high, there is no need to install equipment for reducing the temperature of the condensed fluid discharged through the blow piping or processing equipment. It is possible to reduce the production cost of the product and the environmental load.

  Further, an exhaust heat recovery method according to one aspect of the present invention includes a steam turbine driven by steam, and a condenser that introduces exhaust steam from the steam turbine and condenses the exhaust steam to be a condensed fluid. A circulating boiler for evaporating the condensed fluid from the condenser and introducing it to the steam turbine, and introducing exhaust gas into the circulating boiler, and performing heat exchange between the exhaust gas and the circulating boiler A waste heat recovery method for recovering waste heat in a thermal power plant comprising a gas turbine and blow piping for discharging a part of the condensed fluid from the circulating boiler, the condensed fluid from the blow piping Heat exchange between the exhaust fluid and the fuel of the gas turbine to recover the heat to the fuel.

  According to such a configuration, it is possible to recover the fuel of the gas turbine without discharging the thermal energy of the discharge fluid discharged from the circulating boiler through the blow piping to the outside of the system. The fuel can be introduced to the turbine in a state in which the fuel of the gas turbine is preheated by the thermal energy of the exhaust fluid discharged through the blow piping. Therefore, the thermal efficiency of the entire plant can be improved.

  Further, in the above exhaust heat recovery method, the thermal power plant circulates a fluid with the condenser, and condenses the exhaust steam by the condenser to generate a condensed fluid from the exhaust steam. The cooling tower may be further provided, and the exhaust heat recovery step may further include a fluid recovery step of introducing the discharged fluid after heat recovery to the fuel into the cooling tower.

  Exhaust fluid discharged through the blow piping can be introduced into the cooling tower after heat exchange. Thus, the exhaust fluid containing the impurities is not introduced into the circulating boiler. Therefore, the water quality of the circulating boiler can be maintained in a clean state. In addition, since the discharge fluid discharged through the blow piping is not discharged to the outside of the system while the temperature is high, there is no need to install equipment for reducing the temperature of the discharge fluid discharged through the blow piping, and the processing equipment It is possible to reduce the production cost of the product and the environmental load.

  According to the circulating boiler system, the thermal power plant and the exhaust heat recovery method, it is possible to further improve the efficiency by utilizing the exhaust heat.

BRIEF DESCRIPTION OF THE DRAWINGS It is a whole block diagram of the thermal-power-generation plant of 1st embodiment of this invention. It is a whole block diagram of the thermal-power-generation plant of 2nd embodiment of this invention. It is a whole block diagram of the thermal-power-generation plant of 3rd embodiment of this invention. It is a whole block diagram of the thermal-power-generation plant which concerns on the 1st modification of 3rd embodiment of this invention. It is a whole block diagram of the thermal-power-generation plant which concerns on the 2nd modification of 3rd embodiment of this invention. It is a whole block diagram of the thermal-power-generation plant concerning 4th embodiment of this invention. It is a whole block diagram of the thermal-power-generation plant which concerns on the modification of 4th embodiment of this invention.

First Embodiment
Hereinafter, the thermal-power-generation plant 1 of 1st embodiment of this invention is demonstrated.
As shown in FIG. 1, the thermal power plant 1 includes a steam turbine 10 driven by steam S, a condenser 11, a cooling tower 12, a circulating boiler 13 for introducing the steam S into the steam turbine 10, and a circulating boiler 13 And a heat exchanger 20 connected to the blow pipe 14, and a circulating boiler system 2 having a cooling tower inlet pipe 15 connecting the heat exchanger 20 and the cooling tower 12 . The thermal power plant 1 further includes a gas turbine 21 for introducing the exhaust gas EG into the circulation boiler 13.

  Although not shown in detail, the gas turbine 21 has a compressor 22, a combustor 23, and a turbine 24. The gas turbine 21 burns in the combustor 23 together with the fuel F and the compressed air CA generated by the compressor 22. The high pressure gas is introduced into the turbine 24 to drive the turbine 24. Thus, the generator 100 is rotated to generate power.

The combustor 23 is provided with a heater 26 which preheats the fuel F introduced into the combustor 23.
The compressor 22 is provided with an air cooler 27 for cooling the extracted air A. After the extracted air A is cooled by the air cooler 27, it is introduced into the turbine 24 to cool the high temperature parts and the like. The air cooler 27 may not necessarily be provided.
The turbine 24 is provided with a diffuser (not shown). Exhaust gas EG is discharged from the diffuser.

  The steam turbine 10 is driven by the steam S and generates electric power by rotating a generator 101.

  The condenser 11 is connected to the steam turbine 10 and condenses the steam (exhaust steam) S from the steam turbine 10 into water W.

  The cooling tower 12 is connected to the condenser 11 and circulates the water (fluid) W between the condenser 11 and the condenser 11 so as to condense the steam S in the condenser 11. Water W is generated.

The circulation type boiler 13 is a so-called natural circulation type or forced circulation type boiler, and has a boiler body 31 and an evaporator 32 connected to the boiler body 31. The circulation type boiler 13 of this embodiment is a drum type boiler.
The boiler body 31 stores water (condensed fluid) W and steam S. Further, the boiler main body 31 and the steam turbine 10 are connected by a steam introduction pipe 34 so that the steam S in the boiler main body 31 can be introduced into the steam turbine 10.

  The evaporator 32 is connected to the turbine 24 and performs heat exchange between the exhaust gas EG from the turbine 24 and the water W of the boiler body 31 to heat the water W and return it to the boiler body 31 as steam S.

  Here, in the present embodiment, a high pressure boiler 13H, an intermediate pressure boiler 13I, and a low pressure boiler 13L for evaporating water W from the condenser 11 are provided in parallel to each other as the circulation type boiler 13. Exhaust gas EG of the gas turbine 21 is introduced into the evaporator 32 of each boiler 13 in the order of the high pressure boiler 13H, the medium pressure boiler 13I, and the low pressure boiler 13L. That is, the exhaust gas EG flows in series in the evaporator 32 of each boiler 13.

  An exhaust gas pipe 35 is connected to the evaporator 32 in the low pressure boiler 13L. In the present embodiment, the exhaust gas pipe 35 bifurcates downstream of the evaporator 32 and is connected to the heater 26 and the air cooler 27. Thus, the exhaust gas EG having passed through the evaporator 32 is subjected to the preheating of the fuel F in the heater 26 and the preheating of the air A extracted from the compressor 22. The exhaust gas EG is exhausted out of the system after preheating the fuel F and the air A.

  The boiler main body 31 and the condenser 11 in each boiler 13 are connected by a boiler pipe 36. The boiler piping 36 is branched into three in the middle and connected to the boiler main body 31 in each boiler 13. Thereby, the water W from the condenser 11 is introduced in parallel to the boiler main body 31 in each boiler 13.

  The blow piping 14 is connected to the boiler main body 31 in each boiler 13 and discharges a part of the water W in the boiler main body 31 as drainage (discharge fluid) EW. In the present embodiment, the high pressure blow piping 14H provided in the high pressure boiler 13H, the medium pressure blow piping 14I provided in the medium pressure boiler 13I, and the low pressure blow piping 14L provided in the low pressure boiler 13L are provided as the blow piping 14 It is done. Moreover, each blow piping 14 in each boiler 13 is connected by the junction piping 17 and collectively sends the drainage EW from each blow piping 14 to the downstream side.

  The heat exchanger 20 is connected to the junction pipe 17 so that the drainage EW from each blow pipe 14 can be introduced. Further, the heat exchanger 20 is connected to a heat exchange pipe 37 branched from a midway position between the condenser 11 and the boiler main body 31 in the boiler pipe 36. Thus, water W can be introduced from the condenser 11 to the circulating boiler 13 to the heat exchanger 20. Then, the heat exchanger 20 performs heat exchange between the drainage EW from each blow piping 14 and the water W from the condenser 11, heats the water W to recover heat, and heats the water W (exhaust heat recovery) Process), to cool the drainage EW. The water W after heat exchange in the heat exchanger 20 is introduced into the boiler main body 31 in the high pressure boiler 13H through the preheated water pipe 38 connecting the heat exchanger 20 and the high pressure boiler 13H.

  The cooling tower inlet pipe 15 connects the cooling tower 12 and the heat exchanger 20. The waste water EW after heat exchange in the heat exchanger 20 is introduced into the cooling tower 12 through the cooling tower inlet pipe 15 (fluid recovery step).

  In the thermal power plant 1 described above, even if it is necessary to discharge a part of the water W as the drainage EW from the circulating boiler 13 through the blow piping 14 due to the restrictions or operational restrictions, the thermal energy of the drainage EW The heat exchanger 20 can recover the water W from the condenser 11 to the circulating boiler 13 without discarding it outside the system. The water W from the condenser 11 can be preheated by the thermal energy of the drainage EW discharged through the blow piping 14 and introduced into the high pressure boiler 13H.

  Therefore, the thermal efficiency of the entire circulating boiler system 2 can be improved, and the waste heat utilization makes it possible to further improve the power generation efficiency in the thermal power plant 1.

  Here, the water quality level required for the water W in the cooling tower 12 may be lower than the water quality level generally required for the water W in the circulating boiler 13. In this embodiment, the drainage EW discharged through the blow piping 14 is introduced into the cooling tower 12 after heat exchange in the heat exchanger 20 without being returned to the circulating boiler 13, and the drainage EW is discharged out of the system. It can be used effectively without doing. Then, the water quality of the water W in the circulating boiler 13 can be maintained in a clean state.

  In addition, since the drainage EW discharged through the blow piping 14 is not discharged to the outside of the system while the temperature is high, the influence of heat on equipment outside the system can be reduced. For this reason, there is no need to install equipment for reducing the temperature of the drainage EW discharged through the blow piping 14 or treatment equipment for the drainage EW, and it is possible to reduce the manufacturing cost of the circulating boiler system 2 and to reduce the environmental load. Become.

  In the present embodiment, the water W after heat exchange in the heat exchanger 20 is introduced into the high pressure boiler 13H, but the invention is not limited to this. For example, it may be introduced into the medium pressure boiler 13I or the low pressure boiler 13L according to the temperature and pressure of the water W after heat exchange.

  Furthermore, the exhaust gas EG after passing through the evaporator 32 may not be introduced into the heater 26 and the air cooler 27.

  Furthermore, although the water W is heated by the evaporator 32 by the heat of the exhaust gas EG of the gas turbine 21 in the present embodiment, the water W may be heated by the evaporator 32 by another heat source, for example. That is, in this case, the circulation boiler system 2 of the present embodiment may be applied to a heat source other than the gas turbine 21. Specifically, the circulating boiler system 2 of this embodiment may be applied to a conventional power plant etc. of coal fired

Second Embodiment
Next, a thermal power plant 1A according to a second embodiment of the present invention will be described. The same code | symbol is attached | subjected to the component similar to 1st embodiment, and detailed description is abbreviate | omitted.
As shown in FIG. 2, the thermal power plant 1A is different from the first embodiment in that the circulating boiler system 2A further includes a flash tank 40 provided at a midway position of the joining pipe 17 .

  The flash tank 40 is provided in the joining pipe 17 between the boiler body 31 and the heat exchanger 20. The flash tank 40 reduces the temperature and pressure of the drainage EW from the blow piping 14. Further, the flash tank 40 introduces the drainage EW from the blow piping 14 connected to the boiler body 31 of each boiler 13 to separate the drainage EW into the gas phase G and the liquid phase L. Then, the liquid phase L is introduced into the heat exchanger 20, and the gas phase G is introduced through the gas phase introduction pipe 45 into the boiler main body 31 in the medium pressure boiler 13I and the low pressure boiler 13L. In addition, according to the state of the gaseous phase G, the introduction | transduction location of the gaseous phase G can be changed suitably.

  In the thermal power plant 1A of the present embodiment described above, the drainage EW discharged through the blow piping 14 is flushed with the flash tank 40 to lower the temperature (about 100 ° C.) and the pressure. This makes it possible to avoid backflow when introducing the drainage EW into the cooling tower. In addition, after the impurities are removed by the flash tank 40, the gas phase G of the drainage EW can be returned to the circulating boiler 13. Therefore, by discharging | emitting through the blow piping 14, the supply amount of the supplementary water required when the quantity of the water W in the circulation type boiler 13 reduces can be reduced. Therefore, the cost of makeup water can be reduced.

Third Embodiment
Next, a thermal power plant 1B according to a third embodiment of the present invention will be described. The same code | symbol is attached | subjected to the component similar to 1st embodiment and 2nd embodiment, and detailed description is abbreviate | omitted.
As shown in FIG. 3, the thermal power plant 1B is a first embodiment in that the circulating boiler system 2B includes the heat exchanger 50 instead of the heat exchanger 20 and that the cooling tower 12 is not provided. It differs from the form and the second embodiment.

  The heat exchanger 50 is connected to each blow piping 14 by a junction piping 17. Thereby, the drainage EW from each blow piping 14 is collectively introduced into the heat exchanger 50. Further, the fuel F of the gas turbine 21 is introduced into the heat exchanger 50. Then, heat exchange is performed between the drainage EW and the fuel F, the drainage EW is cooled, and the fuel F recovers heat to heat the fuel F (exhaust heat recovery step). The drainage EW cooled by the heat exchanger 50 is discharged out of the system.

  Furthermore, the heat exchanger 50 and the heater 26 are connected by a fuel introduction pipe 55. The fuel F heated by the heat exchanger 50 is introduced into the heater 26 through the fuel introduction pipe 55 and is further heated.

  In the thermal power plant 1B of the present embodiment described above, the heat exchanger 50 does not discard the thermal energy of the drainage EW discharged from the boilers 13 through the blow piping 14, and the fuel of the gas turbine 21 is transferred by the heat exchanger 50. It can be recovered to F. Then, the fuel F can be introduced into the combustor 23 through the heater 26 in a state where the fuel F of the gas turbine 21 is preheated by the thermal energy of the drainage EW discharged through the blow piping 14. Therefore, the thermal efficiency of the entire plant can be improved.

  Further, the drainage EW from the blow piping 14 is discharged out of the system after being cooled by the heat exchanger 50, but the temperature of the drainage EW is relatively low. Therefore, even if the drainage EW is discharged out of the system, a facility for reducing the temperature of the drainage EW is not necessary, and it is possible to reduce the manufacturing cost of the system and the environmental load.

  Here, as shown in FIG. 4, in the present embodiment, even if the heat exchanger 60 has the low temperature stage 61, the middle temperature stage 62, and the high temperature stage 63 from the upstream side to the downstream side of the flow of the fuel F Good. And in the example of FIG. 4, the junction piping 17 is not provided, but the low pressure blow piping 14L is directly connected to the low temperature stage 61, and the drainage EW from the low pressure blow piping 14L is introduced. Further, the medium pressure blow piping 14I is directly connected to the medium temperature stage 62, and the drainage EW from the medium pressure blow piping 14I is introduced. The high pressure blow piping 14H is directly connected to the high temperature stage 63, and the drainage EW from the high pressure blow piping 14H is introduced.

  The temperature of the drainage EW from the boiler main body 31 in each boiler 13 is different from each other. In the example of FIG. 4, since the stages of the heat exchanger 60 are provided in accordance with the temperature level of the drainage EW, the fuel F can be efficiently heated in stages using the thermal energy of the drainage EW.

  Further, as shown in FIG. 5, in the present embodiment, the joining pipe 17 may connect the high pressure blow pipe 14H and the medium pressure blow pipe 14I and may not connect the low pressure blow pipe 14L. In this case, the drainage EW from the high pressure blow piping 14H and the medium pressure blow piping 14I is collectively introduced into the heat exchanger 50, and the fuel F is heated. The drainage EW from the low pressure blow piping 14L is discharged out of the system.

  In the example of FIG. 5, the thermal energy of the drainage EW from the relatively low temperature (low enthalpy) low pressure blow piping 14L is not recovered by the fuel F, and the relatively high temperature (high enthalpy) high pressure blow piping 14H And, only the thermal energy of the drainage EW from the medium pressure blow piping 14I is recovered to the fuel F. Therefore, the fuel F can be preheated efficiently. Only the thermal energy of the drainage EW from the high pressure blow piping 14H may be recovered to the fuel F.

Fourth Embodiment
Next, a thermal power plant 1C according to a fourth embodiment of the present invention will be described. The same code | symbol is attached | subjected to the component similar to 1st embodiment to 3rd embodiment, and detailed description is abbreviate | omitted.
As shown in FIG. 6, the thermal power plant 1C is different from the third embodiment in that the circulating boiler system 2C further includes a cooling tower 12 and a cooling tower inlet pipe 15.

  The cooling tower inlet pipe 15 connects the cooling tower 12 and the heat exchanger 50. The drainage EW cooled by heat exchange with the fuel F in the heat exchanger 50 is introduced into the cooling tower 12 through the cooling tower inlet pipe 15 (fluid recovery step).

  In the thermal power plant 1C of the present embodiment described above, the waste water EW discharged through the blow pipe 14 is introduced into the cooling tower 12 after heat exchange in the heat exchanger 50 without returning to the circulating boiler 13. The drainage EW can be effectively used without being discharged out of the system, and the water W quality of the water W in the circulating boiler 13 can be maintained in a clean state.

  Here, as shown in FIG. 7, the heat exchanger 60 has the low temperature stage 61, the middle temperature stage 62, and the high temperature stage 63 as in the example of the third embodiment shown in FIG. 4 also in the present embodiment. It may be

  The embodiments of the present invention have been described in detail with reference to the drawings, but the respective configurations and the combinations thereof and the like in the respective embodiments are merely examples, and additions and omissions of configurations are possible within the scope of the present invention. , Substitution, and other changes are possible. Further, the present invention is not limited by the embodiments, and is limited only by the scope of claims.

  For example, although three circulation type boilers 13 are provided in each embodiment described above, the number of circulation type boilers 13 is not limited to three, and may be one or two, or four or more. It may be.

Further, instead of the steam turbine 10, a low boiling point medium Rankine cycle having a low boiling point medium turbine in which the working fluid is a low boiling point medium having a boiling point lower than water W as the working fluid may be applied to the above embodiment. . Here, as the low boiling point medium, for example, the following substances are known.
-Organohalogen compounds such as trichloroethylene, tetrachloroethylene, monochlorobenzene, dichlorobenzene, perfluorodecalin-Butane, propane, pentane, hexane, heptane, octane, decane and the like alkanes-Cyclopentane, such as cyclohexane-Cycloalkanes-Thiophene, ketones, Aromatic compounds: Refrigerants such as R134a, R245fa, etc. A combination of the above In this case, the low boiling point medium is also used as a fluid circulating between the cooling tower 12 and the condenser 11.

Also, depending on the temperature of the water W returned to the cooling tower 12, the capacities of the heat exchangers 20, 50, 60 may be designed.
Also, if the heat exchange amount in the heat exchangers 20, 50, 60 becomes too large, a bypass line may be provided to adjust the flow rate of the drainage EW introduced into the heat exchangers 20, 50, 60. Good.

DESCRIPTION OF SYMBOLS 1, 1A, 1B, 1C ... Thermal power plant 2, 2A, 2B, 2C ... Circulating boiler system 10 ... Steam turbine 11 ... Condenser 12 ... Cooling tower 13 ... Circulating boiler 13H ... High pressure boiler 13 I ... Medium pressure boiler 13L: low pressure boiler 14: blow piping 14H: high pressure blow piping 14I: medium pressure blow piping 14L: low pressure blow piping 15: cooling tower introduction piping 17: joining piping 20: heat exchanger 21: gas turbine 22: compressor 23: combustion Unit 24 ... Turbine 26 ... Heater 27 ... Air cooler 31 ... Boiler main body 32 ... Evaporator 34 ... Steam introduction piping 35 ... Exhaust gas piping 36 ... Boiler piping 37 ... Heat exchange piping 38 ... Preheating water piping 40 ... Flash tank 45 ... gas phase introduction piping 50 ... heat exchanger 55 ... fuel introduction piping 60 ... heat exchanger 61 ... low temperature stage 62 ... middle temperature stage 63 ... high temperature stage 100 ... generator 101 ... generation Machine S ... steam W ... water EW ... draining EG ... exhaust gas F ... Fuel CA ... compressed air A ... air G ... vapor L ... liquid

Claims (10)

A steam turbine driven by steam,
A condenser for introducing exhaust steam from the steam turbine;
A cooling tower which circulates a fluid between the condenser and the condenser, and condenses the exhaust vapor in the condenser to generate a condensed fluid from the exhaust vapor;
A circulating boiler for evaporating the condensed fluid from the condenser and introducing it to the steam turbine;
Blow piping for discharging a part of the condensed fluid from the circulating boiler;
Heat exchange is performed between the discharge fluid, which is the condensed fluid from the blow piping, and the condensed fluid going from the condenser to the circulating boiler, and heat is supplied to the condensed fluid introduced into the circulating boiler A heat exchanger to be recovered,
A cooling tower inlet pipe for introducing the discharged fluid after heat exchange in the heat exchanger to the cooling tower;
Circulation boiler system equipped with   Introducing the discharge fluid from the blow piping to reduce the temperature and pressure of the discharge fluid and separating the discharge fluid into a gas phase and a liquid phase, and then introducing the liquid phase to the heat exchanger; The circulation boiler system according to claim 1, further comprising a flash tank for introducing the gas phase into the circulation boiler. A circulation boiler system according to claim 1 or 2;
A gas turbine for introducing exhaust gas into the circulating boiler in the circulating boiler system and performing heat exchange between the exhaust gas and the circulating boiler;
Thermal power plant equipped with A steam turbine driven by steam,
A condenser which introduces exhaust steam from the steam turbine and condenses the exhaust steam into a condensed fluid;
A circulating boiler for evaporating the condensed fluid from the condenser and introducing it to the steam turbine;
Blow piping for discharging a part of the condensed fluid from the circulating boiler;
A heat exchanger for performing heat exchange between a fuel and an exhaust fluid which is the condensed fluid from the blow piping, and recovering heat from the fuel;
A circulating boiler system having
A gas turbine which introduces exhaust gas into the circulating boiler, exchanges heat between the exhaust gas and the circulating boiler, and burns the fuel after heat recovery by the heat exchanger;
Thermal power plant equipped with A cooling tower which circulates a fluid between the condenser and the condenser, and condenses the exhaust vapor in the condenser to generate a condensed fluid from the exhaust vapor;
The thermal power plant according to claim 4, further comprising a cooling tower inlet pipe for introducing the discharged fluid after heat exchange in the heat exchanger into the cooling tower. As the circulation type boiler, a high pressure boiler, an intermediate pressure boiler, and a low pressure boiler for evaporating the condensed fluid from the condenser in parallel to each other;
As the blow piping, a high pressure blow piping provided to the high pressure boiler, a medium pressure blow piping provided to the medium pressure boiler, and a low pressure blow piping provided to the low pressure boiler;
Equipped with
The heat exchanger has a low temperature stage, an intermediate temperature stage, and a high temperature stage from the upstream side to the downstream side of the fuel flow,
The discharge fluid from the low pressure blow piping is introduced to the low temperature stage;
The discharge fluid from the medium pressure blow piping is introduced to the middle temperature stage,
The thermal power plant according to claim 4 or 5, wherein the discharge fluid from the high pressure blow piping is introduced to the high temperature stage. As the circulation type boiler, a high pressure boiler, an intermediate pressure boiler, and a low pressure boiler for evaporating the condensed fluid from the condenser in parallel to each other;
As the blow piping, a high pressure blow piping provided to the high pressure boiler, a medium pressure blow piping provided to the medium pressure boiler, and a low pressure blow piping provided to the low pressure boiler;
Equipped with
The thermal power plant according to claim 4, wherein the heat exchanger recovers heat to the fuel by the discharged fluid from the high pressure blow piping and the medium pressure blow piping. A fluid is circulated between a steam turbine driven by steam, a condenser for introducing exhaust steam from the steam turbine, and the condenser, and the exhaust steam is condensed in the condenser to A cooling tower for producing condensed fluid from exhaust steam, a circulating boiler for evaporating the condensed fluid from the condenser and introducing it to the steam turbine, and discharging a part of the condensed fluid from the circulating boiler An exhaust heat recovery method for recovering exhaust heat with a circulation boiler system comprising blow piping, comprising:
Heat exchange is performed between the discharge fluid, which is the condensed fluid from the blow piping, and the condensed fluid going from the condenser to the circulating boiler, and heat is supplied to the condensed fluid introduced into the circulating boiler Exhaust heat recovery process to recover,
A fluid recovery step of introducing the discharged fluid after heat exchange in the heat exchanger into the cooling tower;
Waste heat recovery method including: A steam turbine driven by steam, a steam condenser for introducing exhaust steam from the steam turbine and condensing the exhaust steam into a condensed fluid, and evaporating the condensed fluid from the condenser; One example of a circulating boiler introduced into a steam turbine, a gas turbine introducing exhaust into the circulating boiler and performing heat exchange between the exhaust and the circulating boiler, and one of the condensed fluid from the circulating boiler An exhaust heat recovery method for recovering exhaust heat in a thermal power plant comprising: blow piping for discharging a part;
An exhaust heat recovery method comprising an exhaust heat recovery step of performing heat exchange between an exhaust fluid which is the condensed fluid from the blow piping and a fuel of the gas turbine to recover heat from the fuel. The thermal power plant further includes a cooling tower that circulates a fluid with the condenser, and condenses the exhaust steam with the condenser to generate a condensed fluid from the exhaust steam,
The exhaust heat recovery method according to claim 9, further comprising: a fluid recovery step of introducing the discharged fluid after heat recovery to the fuel in the exhaust heat recovery step to the cooling tower.

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