WO2020255692A1 - Power generation plant and method for storing excess energy in power generation plant - Google Patents

Abstract

The purpose of the present invention is to efficiently store (preserve) and utilize excess heat energy generated in a power generation plant. A power generation plant (100) is provided with: a boiler (110); a steam turbine (120); a heat storage device (200) for recovering and storing internally passing excess energy; and a control device (150) which effects control so that excess energy generated during an operation including when started and stopped is stored in the heat storage device (200). The excess energy comprises excess heat energy comprising an excess portion of heat energy of superheated steam generated in the boiler (110), and/or excess power energy comprising excessive power energy.

Description

Power plant and surplus energy heat storage method in power plant

The present invention relates to a steam power plant that utilizes the heat of combustion of various fuels, and in particular, stores (heat storage) a part of the heat of steam and a part of surplus power as heat energy, and stores (heat storage) as needed. The present invention relates to a technology for supplying thermal energy to a power plant.

There are thermal power plants that make effective use of thermal energy, improve the performance of the power plant from start to stop, and supply the necessary thermal energy regardless of the operating status of the power plant. For example, Patent Document 1 states, "A boiler for generating steam, a steam turbine, a condenser, a water supply pump, a steam control valve, a turbine bypass pipe, a turbine bypass valve, and a turbine bypass temperature reduction. A thermal power plant including a device, a heat storage device installed in a turbine bypass pipe, a supplementary water tank, a pipe connecting the supplementary water tank and the heat storage device, and an auxiliary boiler is disclosed.

Japanese Unexamined Patent Publication No. 8-3198005

According to the technique disclosed in Patent Document 1, surplus heat energy, which is the heat energy discarded when the power plant is started and stopped, can be stored in the heat storage material and used as a heat source at the time of starting. Further, a heat storage device provided with heat storage materials having different melting points is provided, and steam is passed in order from the one having the highest melting point to store excess heat energy. Therefore, the surplus heat energy can be recovered separately as the high temperature heat energy and the low temperature heat energy, and the heat can be effectively used.

However, the temperature of the steam output from the boiler gradually rises at startup. Therefore, a method of passing steam from a heat storage device having a heat storage material having a high melting point to store excess heat energy is not always appropriate, and it is not always possible to efficiently store heat energy.

Also, for example, when a power generation device using renewable energy such as solar power or wind power is incorporated into the power grid, it is necessary to adjust the output on the power plant side in order to maintain the stability of the power system. However, it is desirable for the power plant to maintain the minimum load in order to be able to cope with rapid load fluctuations. However, when the power plant maintains the minimum load, surplus power may be generated, and at present, this surplus power cannot be fully utilized.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a technique for efficiently storing and utilizing surplus energy generated in a power plant.

The power plant of the present invention has a boiler that heats supplied water to generate superheated steam, a steam turbine that is rotationally driven by the superheated steam heated by the boiler to drive a generator, and surplus energy that passes through the inside. It is characterized by including a heat storage device for recovering and storing heat, and a control device for controlling the excess energy generated during operation including the start and stop so that the surplus energy is stored in the heat storage device.

Further, the power plant of the present invention stores heat in a boiler that heats the supplied water to generate superheated steam, a steam turbine that is rotationally driven by the superheated steam heated by the boiler to drive a generator, and surplus energy. The boiler includes a first boiler heat exchange unit that generates a fluid having a temperature in the first temperature range by heat exchange, and the heat storage device stores heat energy in the first temperature range. The first heat storage unit that stores heat and a part of the fluid generated by the first boiler heat exchange unit are guided to the first heat storage unit, and after the heat energy is recovered by the first heat storage unit, the first boiler It is characterized by including a first heat recovery tube that leads to the outlet side of the heat exchange unit.

According to the present invention, surplus energy generated in a power plant can be efficiently stored and used. Issues, configurations and effects other than those described above will be clarified by the description of the following embodiments.

(A) is an explanatory diagram for explaining the relationship between the turbo generator load, boiler heat generation and steam temperature at each time change when the power plant is started and (b) is when the power plant is stopped. .. It is explanatory drawing for demonstrating the relationship between a turbine generator load, boiler heat output and steam temperature with time change at the time of pumping operation of a power plant. (A) is a system configuration diagram of the power plant of the first embodiment, and (b) is a configuration diagram of the control device of the first embodiment. It is explanatory drawing for demonstrating the structure of the heat storage apparatus of 1st Embodiment. It is explanatory drawing for demonstrating the control of the open / closed state of each on-off valve by the control device at the time of starting and stopping of the power plant of 1st Embodiment. It is explanatory drawing for demonstrating the control of the open / closed state of each on-off valve by the control device at the time of pumping operation of the power plant of 1st Embodiment. (A) is an explanatory diagram for explaining the open / closed state of the on-off valve of the power plant of the first embodiment in (b) in the first start-up operation mode, respectively, in the second start-up operation mode. (A) is an explanatory diagram for explaining the open / closed state of the on-off valve of the power plant of the first embodiment, respectively, in the third start operation mode and (b) in the first stop operation mode. .. It is explanatory drawing for demonstrating the open / closed state of the on-off valve of the power plant of 1st Embodiment in the pumping operation mode. (A) is an explanatory diagram for explaining the open / closed state of each on-off valve of the heat storage device of the first embodiment, respectively, in the first start-up operation mode (b) in the second start-up operation mode. .. (A) is an explanatory diagram for explaining the open / closed state of each on-off valve of the heat storage device of the first embodiment, respectively, in the first stop operation mode and (b) in the pumping operation mode. It is explanatory drawing for demonstrating the open / closed state of each on-off valve of the heat storage apparatus of 1st Embodiment in an emergency operation mode. (A) is a system configuration diagram of the power plant of the second embodiment, and (b) is an explanatory diagram for explaining the configuration of the heat storage device of the second embodiment. It is explanatory drawing for demonstrating the control of the open / closed state of each on-off valve by the control device at the time of starting and stopping of the power plant of 2nd Embodiment. It is explanatory drawing for demonstrating the control of the open / closed state of each on-off valve by a control device at the time of pumping operation of the power plant of 2nd Embodiment. (A) is an explanatory diagram for explaining the open / closed state of each on-off valve of the heat storage device of the second embodiment, respectively, in the first start-up operation mode (b) in the second start-up operation mode. .. (A) is an explanatory diagram for explaining the open / closed state of each on-off valve of the heat storage device of the second embodiment, respectively, in the first stop operation mode and (b) in the pumping operation mode. It is explanatory drawing for demonstrating the open / closed state of each on-off valve of the heat storage apparatus of 2nd Embodiment in an emergency operation mode. (A) is an explanatory diagram for explaining the configuration of the heat storage device of the modified example of the present invention, and (b) and (c) are control of each on-off valve by the control device of the modified example 1 of the present invention. It is explanatory drawing for demonstrating. It is explanatory drawing for demonstrating an example of the relationship between the turbine generator load, the boiler heat output and the steam temperature with time change at the time of starting a power plant of the modification of this invention. (A) and (b) are explanatory views for demonstrating the structure of the heat storage apparatus of the modification of this invention. (A) and (b) are explanatory views for demonstrating the structure of the heat storage apparatus of the modification of this invention. It is explanatory drawing for demonstrating an example of the relationship between a turbine generator load, a boiler heat output and a steam temperature with time change when a power plant of a modification of this invention is stopped. (A) describes the design temperature of each heat exchanger of the boiler of the power plant of the third embodiment, and (b) describes an example of connection at the time of heat recovery from the heat storage device of the third embodiment. It is explanatory drawing for this. (A) and (b) are explanatory views for explaining the recovery opportunity of the heat energy stored in the heat storage device of the third embodiment, respectively. It is explanatory drawing for demonstrating another example at the time of recovery of the heat energy stored in the heat storage apparatus of 3rd Embodiment. It is explanatory drawing for demonstrating another connection example at the time of heat recovery from the heat storage apparatus of the modification of 3rd Embodiment. It is explanatory drawing for demonstrating connection to the heat storage apparatus including the system block diagram of the power generation plant of 4th Embodiment. (A) is an explanatory diagram for explaining a configuration example of a heat storage device, respectively, of a fourth embodiment and (b) of a modified example thereof. (A) to (c) are explanatory views for explaining ON / OFF control of the electric heater of 4th Embodiment. (A) is an explanatory diagram for explaining a connection example at the time of heat recovery, respectively, of the fourth embodiment and (b) of the modified example. It is explanatory drawing for demonstrating the structural example of the heat storage apparatus of the modification of 4th Embodiment. It is a system block diagram of the power plant of the fifth embodiment. It is explanatory drawing for demonstrating the structural example of the heat storage apparatus of 5th Embodiment. It is explanatory drawing for demonstrating the connection example at the time of heat recovery of 5th Embodiment. It is explanatory drawing for demonstrating the structural example of the heat storage apparatus of the modification of 5th Embodiment. It is explanatory drawing for demonstrating the connection example at the time of heat recovery of the modification of the 5th Embodiment. It is explanatory drawing for demonstrating connection to the heat storage apparatus including the system block diagram of the power generation plant of the modification of 5th Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Prior to the detailed description of each embodiment, the outline of the first to third embodiments of the present invention will be described. In these embodiments, in order to effectively utilize the surplus heat energy in the power plant, heat is stored in the heat storage layer corresponding to the temperature zone of the surplus heat energy. Then, the stored heat is recovered from the optimum temperature range at an appropriate timing during operation of the power plant and used. In addition, the specific temperature and the like described in this specification below are examples for explanation.

Generally, a power plant includes a boiler that generates steam by heat obtained by burning fuel and a steam turbine that generates power by rotating a turbine using the steam generated by the boiler. The surplus heat energy of the embodiment is generated by the difference between the amount of heat generated by the steam generated by the boiler (referred to as boiler output heat or boiler load) and the amount of heat required by the steam turbine (referred to as turbine generator load). To do.

For example, when the power plant is started, as shown in FIG. 1A, the entire amount of boiler heat output is not used in the steam turbine after the boiler is ignited and before the boiler starts the once-through operation. This is to warm up the equipment that composes the steam cycle and to stabilize each equipment from the start to the cruise operation. During this time, excess thermal energy is generated.

Further, even when the power plant is stopped, as shown in FIG. 1 (b), similarly, a difference occurs between the boiler heat output and the steam turbine generator load, and surplus thermal energy is generated. This means that the boiler load must be maintained at about 20% for a predetermined period even when the power plant is stopped, while the turbine generator load is monotonically reduced. Therefore, excess thermal energy is generated during this period.

Further, as shown in FIG. 2, the power plant may operate with the turbine generator load smaller than the minimum load of the boiler by a predetermined amount α. Such an operating state occurs, for example, when the system side absorbs fluctuations in the amount of power generation due to natural energy. Hereinafter, in the present specification, such an operating state of the power plant is referred to as pumped storage operation. As shown in this figure, surplus thermal energy is generated due to the difference between the boiler heat output and the steam turbine generator load even during this pumping operation.

In the first to third embodiments of the present invention described below, excess heat energy that is output from the boiler in the state of steam and is not used in the steam turbine is stored in a heat storage layer according to the steam temperature at the time of generation. Also, when using it, collect it from the optimum temperature range and use it. As a result, excess heat energy is efficiently stored and used.

<< First Embodiment >>
The first embodiment of the present invention will be described. First, an example of a power plant to which the heat storage device of the present embodiment is applied will be described. The heat storage device 200 of this embodiment is used, for example, in the power plant 100 shown in FIG. 3A. FIG. 3A is a fluid system diagram of the power plant 100 of the present embodiment.

In the power generation plant 100 of the present embodiment, the boiler 110 that burns fuel and generates steam (superheated steam) by the heat of the combustion, and the generator 109 by rotating a turbine using the steam generated by the boiler 110. Of the steam turbine 120 that drives and generates power, the water supply line 130 that returns the exhaust steam from the steam turbine 120 to water and supplies it to the boiler 110, and the thermal energy of the steam that is overheated by the boiler 110, the excess thermal energy is used. It includes a heat storage device 200 for storing heat and a control device 150 (see FIG. 3B).

The boiler 110 includes an economizer (ECO) 111, a fireplace water cooling wall 112, a brackish water separator 113, a superheater 114, and a reheater 115. In the present embodiment, the superheater 114 and the reheater 115 are provided in a plurality of stages from the downstream to the upstream. The number of superheaters 114 and reheaters 115 may be one.

The steam turbine 120 includes a high-pressure steam turbine (HPT) 121, a medium-pressure steam turbine (IPT) 122, and a low-pressure steam turbine (LPT) 123, which perform predetermined tasks for rotationally driving the generator 109, respectively. To be equipped. The medium-pressure steam turbine 122 and the low-pressure steam turbine 123 are also collectively referred to as a medium-low pressure steam turbine.

On the water supply line 130, a condenser 131, a condenser pump 132, a low-pressure feed water heater (low-pressure heater) 133, a deaerator 134, a water supply pump 135, and a high-pressure feed water heater (high-pressure heater) 136. And are provided.

In the power plant 100 having the above configuration, the economizer 111 preheats the supplied water by heat exchange with the combustion gas. The water preheated by the economizer 111 produces a water-steam two-phase fluid in the furnace water cooling wall 112 by passing through a furnace wall pipe (not shown) formed on the wall. The water-steam two-phase fluid generated in the furnace water cooling wall 112 is sent to the brackish water separator 113 and separated into saturated steam and saturated water. Here, the saturated steam is guided to the superheater 114, and the saturated water is guided to the condenser 131 through the saturated water pipe 161.

The saturated steam separated by the steam water separator 113 is superheated by the superheater 114 by heat exchange with the combustion gas, and the generated superheated steam is introduced into the high-pressure steam turbine 121 via the main steam pipe 162. As described above, the superheater 114 is provided in a plurality of stages. From the front of the superheater 114 in the final stage, some steam is guided to the condenser 131 through the boiler bleeding pipe 165. The boiler extraction pipe 165 is provided with a boiler activation extraction air adjustment valve (heater bypass valve; EC) 175.

The steam that has performed the predetermined work in the high-pressure steam turbine 121 is guided to the reheater 115 via the low-temperature reheat steam pipe 163. The reheater 115 reheats the steam that has performed the predetermined work in the high pressure steam turbine 121. The steam superheated by the reheater 115 is supplied to the medium-pressure steam turbine 122 and the low-pressure steam turbine 123 via the high-temperature reheat steam pipe 164, where they perform work and drive the generator 109. The main steam pipe 162 is provided with a main steam on-off valve 172. Further, the high temperature reheat steam pipe 164 is provided with a reheat steam on-off valve 174.

The steam that has finished its work in the low-pressure steam turbine 123 is introduced into the condenser 131 by the turbine exhaust pipe 166. The condensate condensed by the condenser 131 is sent to the deaerator 134 after passing through the low pressure heater 133 by the condensate pump 132 together with the saturated water sent from the brackish water separator 113, and the gas component in the condensate is removed. Will be done. The condensate that has passed through the deaerator 134 is further boosted by the water supply pump 135, then fed to the high-pressure heater 136 to be heated, and finally returned to the boiler 110.

Further, the power plant 100 includes a main steam bypass pipe 167 that branches from the main steam pipe 162 and guides the steam to the condenser 131 by bypassing the high-pressure steam turbine 121. The main steam bypass pipe 167 is provided with a main steam bypass on-off valve 177.

The heat storage device 200 of the present embodiment is arranged on the saturated water pipe 161, the boiler bleeding pipe 165, and the main steam bypass pipe 167. The heat storage device 200 stores the thermal energy of steam or saturated water flowing in the saturated water pipe 161 and the boiler extraction pipe 165 and the main steam bypass pipe 167 by heat exchange. The steam or saturated water after heat exchange in the heat storage device 200 is introduced into the condenser 131 via the respective pipes.

Further, temperature sensors 181, 185, and 187 (see FIG. 3B) for detecting the temperature of steam passing through the inside of the saturated water pipe 161 and the boiler extraction pipe 165 and the main steam bypass pipe 167 are appropriately provided.

As shown in FIG. 3B, the control device 150 is instructed from the outside (control table 151 or the like placed in the power plant), or the temperature sensors 181, 185, and the temperature sensors 181 and 185 installed in the power plant 100. The opening and closing of each on-off valve in the power plant 100 is controlled according to signals from various sensors including 187. For example, the main steam on-off valve 172, the reheated steam on-off valve 174, the boiler start bleed air adjusting valve 175, and the main steam bypass on-off valve 177 of the present embodiment are opened and closed according to the operation mode. The details of the opening / closing timing of each on-off valve will be described later. The on-off valve whose opening / closing is controlled by the control device 150 also includes an on-off valve included in the heat storage device 200, which will be described later.

The control device 150 includes, for example, a CPU, a memory, and a storage device, and the CPU loads a program stored in the storage device in advance into the memory and executes the control to realize the above control.

[Heat storage device]
Next, the heat storage device 200 of the present embodiment will be described with reference to FIG. Hereinafter, in the present specification, the steam, water, etc. that return in the power plant 100 will be referred to as a fluid when it is not necessary to distinguish them.

The heat storage device 200 of the present embodiment stores excess heat energy of the fluid in the power plant 100 according to the instruction from the control device 150. The heat storage device 200 of the present embodiment includes a plurality of heat storage layers composed of heat storage materials having temperature characteristics (melting points) in different temperature ranges, a heat exchange unit provided in each heat storage layer, and the heat storage device 200. It regulates the inflow of fluid into each flow path and the flow path that connects and guides the fluid in the pipe to the heat exchange section or bypasses the heat storage device 200 and guides the fluid in the pipe to the water condensing device 131. It is equipped with an on-off valve (valve).

In the present embodiment, when heat is stored in the heat storage device 200, the path through which the fluid passes is changed according to the temperature of the fluid flowing into the heat storage device 200. As a result, heat is efficiently stored. The route change is realized by a command from the control device 150 to the on-off valve (valve) provided in each flow path described later.

Hereinafter, in the present embodiment, the heat storage device 200 has a high temperature heat storage layer 210 (hereinafter, also simply referred to as a high temperature layer 210), a medium temperature heat storage layer 220 (medium temperature layer 220), and a low temperature heat storage layer 230 (low temperature) as heat storage layers. A case where the three heat storage layers of the layer 230) and the three heat storage layers are provided will be described as an example.

The high temperature layer 210 is a heat storage layer composed of a heat storage material having a temperature characteristic (melting point) in a temperature range (first temperature range) centered on 500 ° C. The medium temperature layer 220 is a heat storage layer composed of a heat storage material having a temperature characteristic in a temperature range (second temperature range) centered on 400 ° C. Further, the low temperature layer 230 is a heat storage layer composed of a heat storage material having a temperature characteristic in a temperature range (third temperature range) centered on 300 ° C.

Further, in the heat storage device 200 of the present embodiment, as a heat exchange unit, as shown in FIG. 4, a high temperature heat exchange unit 211 arranged in the high temperature layer 210 and a first medium heat exchange unit arranged in the medium temperature layer 220. It includes an exchange unit 221 and a second medium temperature heat exchange unit 222, and a first low temperature heat exchange unit 231, a second low temperature heat exchange unit 232, and a third low temperature heat exchange unit 233 arranged in the low temperature layer 230.

Each heat exchange unit (high temperature heat exchange unit 211, first medium temperature heat exchange unit 221, second medium temperature heat exchange unit 222, first low temperature heat exchange unit 231, second low temperature heat exchange unit 232, third The low temperature heat exchange unit 233) exchanges heat with the inflowing fluid. When a fluid having a temperature equal to or higher than the melting point of the arranged heat storage layer flows in, it functions as a heat storage unit that stores heat energy in the heat storage layer. On the other hand, when a fluid having a temperature lower than the melting point of the arranged heat storage layer flows in, the heat energy stored in the heat storage layer is dissipated.

The heat storage device 200 has a main steam first flow path 371, a main steam bypass flow path 372, a main steam third flow path 373, a boiler exhaust flow path 351 and a boiler exhaust bypass flow as flow paths used during heat storage. A path 352, a saturated water flow path 311 and a saturated water bypass flow path 312 are provided.

The main steam first flow path 371 is connected to the main steam bypass pipe 167. In the present embodiment, the main steam bypass pipe 167 is branched at the branch point 301, and the high temperature heat exchange section 211, the first medium temperature heat exchange section 221 and the first low temperature heat exchange section 231 are connected in this order, and at the confluence point 302. Connect to the main steam bypass pipe 167. As a result, the main steam first flow path 371 passes the fluid flowing from the main steam bypass pipe 167 into the heat storage device 200 in the order of the high temperature heat exchange unit 211, the first medium heat exchange unit 221 and the first low temperature heat exchange unit 231. And discharge from the heat storage device 200. During this time, the fluid passing through the main steam first flow path 371 exchanges heat in each heat storage layer and stores heat in each heat storage layer. When the temperature of the supplied fluid is higher than the melting point of the high temperature layer 210, the thermal energy of the fluid is stored in the order of the high temperature layer 210, the medium temperature layer 220, and the low temperature layer 230. The fluid discharged from the heat storage device 200 returns to the condenser 131 via the main steam bypass pipe 167.

The main steam bypass flow path 372 bypasses the heat storage device 200 with the fluid in the main steam bypass pipe 167. The fluid bypassing the heat storage device 200 returns to the condenser 131 via the main steam bypass pipe 167. The main steam bypass flow path 372 branches at the branch point 301, bypasses the high temperature heat exchange section 211, the first medium temperature heat exchange section 221 and the first low temperature heat exchange section 231, and becomes the main steam bypass pipe 167 at the confluence point 302. Meet.

The main steam third flow path 373 branches from the main steam bypass flow path 372, bypasses the high temperature heat exchange section 211, and joins the main steam first flow path 371. As a result, the main steam third flow path 373 allows the fluid flowing into the heat storage device 200 from the main steam bypass pipe 167 to pass through the first medium temperature heat exchange section 221 and the first low temperature heat exchange section 231 in this order, and the heat storage device 200. Discharge from. When the temperature of the supplied fluid is higher than the melting point of the medium temperature layer 220, the heat energy of the fluid is stored in the order of the medium temperature layer 220 and the low temperature layer 230. The fluid discharged from the heat storage device 200 returns to the condenser 131 via the main steam bypass pipe 167.

The boiler exhaust flow path 351 is connected to the boiler bleeding pipe 165. The boiler exhaust flow path 351 branches from the boiler bleeding pipe 165 at a branch point 303, connects the second medium temperature heat exchange section 222 and the second low temperature heat exchange section 232 in this order, and connects to the boiler bleeding pipe 165 at the confluence point 304. To do. As a result, the boiler exhaust flow path 351 passes the fluid flowing into the heat storage device 200 from the boiler extraction pipe 165 in the order of the second medium temperature heat exchange unit 222 and the second low temperature heat exchange unit 232, and discharges the fluid from the heat storage device 200. .. The fluid passing through the boiler exhaust flow path 351 exchanges heat in each heat storage layer and stores heat in each heat storage layer. The fluid discharged from the heat storage device 200 returns to the condenser 131 via the boiler extraction pipe 165.

The boiler exhaust bypass flow path 352 bypasses the heat storage device 200 for the fluid in the boiler extraction pipe 165. The fluid bypassing the heat storage device 200 returns to the condenser 131 via the boiler extraction pipe 165. The boiler exhaust bypass flow path 352 branches at a branch point 303, bypasses the second medium temperature heat exchange section 222 and the second low temperature heat exchange section 232, and joins the boiler exhaust flow path 351 at the confluence point 304.

The saturated water flow path 311 is connected to the saturated water pipe 161. It branches from the saturated water pipe 161 at the branch point 305 and is connected to the saturated water pipe 161 at the confluence point 306 via the third low temperature heat exchange unit 233. As a result, the saturated water flow path 311 allows the fluid flowing into the heat storage device 200 from the saturated water pipe 161 to pass through the third low-temperature heat exchange unit 233 and is discharged from the heat storage device 200. The fluid passing through the saturated water flow path 311 exchanges heat in the low temperature layer 230 and stores heat in the low temperature layer 230. The fluid discharged from the heat storage device 200 returns to the condenser 131 via the saturated water pipe 161.

The saturated water bypass flow path 312 bypasses the heat storage device 200 and returns the fluid in the saturated water pipe 161 to the condenser 131. The saturated water bypass flow path 312 branches at the branch point 305, bypasses the third low temperature heat exchange section 233, and joins the saturated water flow path 311 at the confluence point 306. When the temperature of the supplied fluid is higher than the melting point of the low temperature layer 230, the thermal energy of the fluid is stored in the low temperature layer 230.

In addition, each flow path is equipped with an on-off valve (valve). In the present embodiment, as the on-off valves, the main steam first on-off valve 376, the main steam second on-off valve 377, the main steam third on-off valve 378, the exhaust first on-off valve 356, and the exhaust second on-off valve 357 A saturated water first on-off valve 316 and a saturated water third on-off valve 317 are provided.

The main steam first on-off valve 376 is provided downstream of the branch point 301 of the main steam first flow path 371 and controls the inflow of fluid into the high temperature heat exchange unit 211.

The main steam third on-off valve 378 is provided downstream of the branch point of the main steam third flow path 373 with the main steam bypass flow path 372, and controls the inflow of fluid into the main steam third flow path 373.

The main steam second on-off valve 377 is provided downstream of the branch point of the main steam bypass flow path 372 with the main steam third flow path 373, and controls the inflow of fluid into the main steam bypass flow path 372.

The exhaust first on-off valve 356 is provided downstream of the branch point 303 of the boiler exhaust flow path 351 and controls the inflow of fluid into the second medium heat exchange unit 222.

The second exhaust on-off valve 357 is provided in the boiler exhaust bypass flow path 352 and controls the inflow of fluid into the boiler exhaust bypass flow path 352.

The saturated water first on-off valve 316 is provided downstream of the branch point 305 of the saturated water flow path 311 and controls the inflow of fluid into the third low temperature heat exchange unit 233.

The saturated water third on-off valve 317 is provided in the saturated water bypass flow path 312 and controls the inflow of fluid into the saturated water bypass flow path 312.

Each on-off valve is opened and closed according to a command from the control device 150. The control device 150 detects the temperature of the fluid flowing into the heat storage device 200 according to the instruction input via the control console 151, and opens and closes each on-off valve according to the temperature, so that the fluid inflow path To control. For example, when controlling the opening and closing according to the temperature, the opening and closing of the on-off valve is controlled so that the heat is stored in the heat storage layer of the heat storage material which is lower than the temperature and has the closest melting point according to the temperature of the inflowing fluid. To do. Specific examples of on-off valve control will be described later.

As the heat storage material used for each heat storage layer, for example, a latent heat storage material utilizing the phase transformation latent heat of the substance can be used. The temperature characteristic of the heat storage layer is a characteristic determined based on the melting temperature (melting point) of the latent heat storage material. Further, as the heat storage material used for each heat storage layer, an alloy-based material having a heat storage temperature (melting point) exceeding 500 ° C. may be used. Further, the structure may include the alloy-based material in ceramics or metal. For example, the latent heat storage microcapsules disclosed in International Publication No. 2017/200021 can be used.

By using a heat storage material having a structure in which the latent heat storage material is included in each heat storage layer by ceramics or the like, it is possible to obtain a heat storage unit that operates only by inputting and receiving heat using the phase transformation of the latent heat storage material. Since the melting temperature can be controlled by the composition of the latent heat storage material at the time of manufacture, the temperature range of the fluid can be set more finely.

As the heat storage material used for each heat storage layer, a material having a melting point in the temperature range is selected according to the temperature range of the heat energy stored in the heat storage device 200. Further, the heat storage capacity of each heat storage layer is determined based on the assumed amount of surplus heat energy. As a result, heat can be efficiently stored without wasting the generated excess heat energy. This also leads to optimization of capital investment.

In the heat storage device 200, a flow path for connecting a heat exchange unit in the same heat storage layer is further provided as a flow path used for heat recovery described later. As a flow path for heat recovery, the heat storage device 200 includes a first heat recovery tube 410 that passes through the high temperature heat exchange section 211 of the high temperature layer 210, and a first medium temperature exchange section 221 and a second medium heat exchange of the medium temperature layer 220. A second heat recovery tube 420 that passes through section 222, and a third heat recovery tube 430 that passes through the first low temperature heat exchange section 231 of the low temperature layer 230, the second low temperature heat exchange section 232, and the third low temperature heat exchange section 233. To be equipped with.

The first heat recovery tube 410 recovers heat only from the high temperature layer 210 by passing the fluid through only the high temperature layer 210 at the time of heat recovery. The second heat recovery tube 420 recovers heat only from the middle temperature layer 220 by passing the fluid through only the middle temperature layer 220. The third heat recovery tube 430 recovers heat only from the low temperature layer 230 by passing the fluid through only the low temperature layer 230.

The first heat recovery tube 410, the second heat recovery tube 420, and the third heat recovery tube 430 have a first heat recovery on-off valve 411 and a second heat recovery on-off valve 421 on the inlet side of each heat storage layer, respectively. , A third heat recovery on-off valve 431 is provided. The opening and closing of these heat recovery on-off valves 411, 421 and 431 is controlled by the control device 150. The control device 150 controls the opening and closing of these heat recovery on-off valves 411, 421 and 431 so that heat can be recovered from the heat storage layer in the optimum temperature range during heat recovery.

[Control of on-off valve by control device]
Hereinafter, control of the on-off valve by the control device 150 in the power plant 100 including the heat storage device 200 of the present embodiment will be described.

The control device 150 of the present embodiment stores the surplus heat energy in the steam state generated when the power plant 100 is started, stopped, or during pumping operation, etc., in the heat storage device 200 for each temperature range. Controls the opening and closing of each on-off valve.

For example, the power generation plant 100 of the present embodiment has a start operation mode which is an operation mode at the time of start, a normal operation mode which is an operation mode at the normal time, a pumping operation mode which is an operation mode at the time of pumping operation, and a stop. It has a stop operation mode, which is an operation mode at the time, and an emergency operation mode, which is an operation mode when a system fails. Of these, excess thermal energy in the steam state is generated during operation in the start operation mode, the pumping operation mode, the stop operation mode, and the emergency operation mode.

Hereinafter, in each of the on-off valves in the power plant 100 for storing heat in the heat storage device 200 of the present embodiment by the control device 150 in these start operation mode, pumped storage operation mode, stop operation mode and emergency operation mode. Open / close control will be described.

As described above, in the present embodiment, the control device 150 controls the on-off valve so as to store heat in different heat storage layers depending on the temperature of the surplus heat energy. Here, in the start-up operation mode, as shown in FIG. 1A, there are events such as ignition of the boiler 110, start of ventilation to the steam turbine 120, incorporation of the generator 109 into the system, and equilibrium, from the boiler 110. The temperature of the output steam rises monotonically over time. Further, in the stop operation mode, as shown in FIG. 1B, there are events such as equilibrium end and stop, and the temperature of steam output from the boiler 110 decreases monotonically. On the other hand, in the pumping operation mode, as shown in FIG. 2, there are events of equilibrium end and equilibrium, and during that time, the steam temperature output from the boiler 110 is substantially constant.

In this specification, the equilibrium refers to a state in which the amount of heat generated by the boiler per unit time and the load on the turbine generator are in equilibrium. In addition, the end of equilibrium refers to the time when the amount of heat output from the boiler becomes dominant and a difference occurs between the amount of heat output from the boiler and the load on the turbine generator, which have been balanced after receiving the instruction to stop.

In the present embodiment, in order to realize heat storage according to the temperature range, the control device 150 divides the start operation mode and the stop operation mode into a plurality of operation modes according to the steam temperature, and opens / close control different for each operation mode. I do. In the pumping operation mode, since the steam temperature is substantially constant, opening / closing control is performed as one operation mode.

For example, in the present embodiment, as shown in FIG. 1A, in the start-up operation mode, the first start-up operation mode is from the ignition of the boiler 110 to the start of ventilation to the steam turbine 120, and the second is from the start of ventilation to the equilibrium. The start operation mode, from equilibrium to normal operation, is set as the third start operation mode. Further, in the stop operation mode, as shown in FIG. 1B, the first stop operation mode is set from the end of equilibrium to the stop.

Note that each operation mode shifts to each operation mode by receiving an instruction from the operator via the control console 151. The control device 150 may make a determination based on the temperature detected by the temperature sensors arranged in each pipe. For example, in the start-up operation mode, from the first start-up operation mode to the second start-up operation mode, the temperature detected by the temperature sensor 187 arranged on the main steam bypass pipe 167 or the like is set to a predetermined threshold value (for example, 500 ° C.). ) It may be configured to shift when the above is reached.

In the present embodiment, the opening and closing of the on-off valve provided in each pipe of the power plant 100 is controlled according to the operation mode. Further, the opening / closing of the on-off valve provided in each flow path of the heat storage device 200 is controlled according to the temperature of the fluid on the inlet side of each flow path detected by the temperature sensors 181, 185, and 187.

The open / closed state of each on-off valve for each operation mode is stored in advance in the storage device of the control device 150 as an open / close state table.

In the following explanation, it is assumed that each on-off valve is in the closed state in the initial state unless otherwise specified.

The time chart of opening and closing of each on-off valve by the control device 150 for each operation mode and event is shown in FIGS. 5 and 6. 7 (a) to 9 are views for explaining the open / closed state of the on-off valve in the power plant 100 for each operation mode.

Upon receiving the activation command from the control console 151 or the like, that is, the operation command in the first activation operation mode, the control device 150 and the boiler activation extraction air adjusting valve 175, as shown in FIGS. 5 and 7A. , An open command is output to the main steam bypass on-off valve 177, and these on-off valves are opened. As a result, the steam generated in the boiler 110 is guided to the heat storage device 200 via the boiler extraction pipe 165 and the main steam bypass pipe 167.

Next, upon receiving the operation command in the second start operation mode, the control device 150 issues a close command to the boiler start bleed air adjusting valve 175 as shown in FIGS. 5 and 7 (b), while the main An open command is issued to the steam on-off valve 172 and the reheat steam on-off valve 174. As a result, the steam generated in the boiler 110 is supplied to the steam turbine 120. At this time, a part of the surplus steam is guided to the heat storage device 200 via the main steam bypass pipe 167.

After that, when the operation command in the third start operation mode is received, the control device 150 outputs a close command to the main steam bypass on-off valve 177 as shown in FIGS. 5 and 8A, and the state is closed. To do. As a result, the steam generated in the boiler 110 is supplied to the steam turbine 120. After that, when the mode shifts to the normal operation mode, steam and water circulate between the boiler 110, the steam turbine 120, and the water supply line 130, and the generator 109 is driven.

Further, upon receiving the operation command in the first stop operation mode, the control device 150 outputs an open command to the main steam bypass on-off valve 177 as shown in FIGS. 5 and 8 (b), and the open state is set. To do. As a result, the steam generated by the boiler 110 is supplied to the steam turbine 120 as in the second start operation mode. At this time, a part of the surplus steam is guided to the heat storage device 200 via the main steam bypass pipe 167.

Further, when a command for operation in the pumping operation mode is received during normal operation, the control device 150 causes the main steam on-off valve 172 and the reheated steam on-off valve 174 to move as shown in FIGS. 6 and 9. Leave it open. In addition, an open command is output to the main steam bypass on-off valve 177 to open the valve. Then, the boiler start bleeding adjustment valve 175 is closed as it is. As a result, the steam generated in the boiler 110 is supplied to the steam turbine 120. Further, the surplus steam is guided to the heat storage device 200 via the main steam bypass pipe 167.

Next, the control of the on-off valve of the heat storage device 200 by the control device 150 in the first start operation mode, the second start operation mode, the first stop operation mode, and the pumping operation mode in which the fluid is guided to the heat storage device 200 will be described. .. As described above, the control device 150 controls the opening and closing of each on-off valve according to the temperature of the surplus heat energy generated in each operation mode. The opening and closing of each on-off valve is controlled so that the generated excess thermal energy flows into the flow path that first passes through the heat storage unit having the temperature characteristic in the temperature range to which the temperature belongs in the form of a fluid.

Here, the control of the on-off valve of the heat storage device 200 in the emergency operation mode will also be described. The emergency operation mode is an emergency operation mode such as a system failure.

Since the control of the on-off valve of the heat storage device 200 during heat storage is described here, the heat recovery on-off valves 411, 421, and 431 are omitted. At the time of heat storage, these heat recovery on-off valves 411, 421 and 431 are basically kept in a closed state.

In the first start-up operation mode, as shown in FIG. 1A, the steam temperature is 400 ° C. or higher and less than 500 ° C. Therefore, the control device 150 controls the opening and closing of the on-off valve so that it flows into the flow path that first passes through the heat storage unit having the temperature characteristic in this temperature range.

That is, as shown in FIGS. 5 and 10A, the control device 150 opens the main steam third on-off valve 378, the exhaust first on-off valve 356, and the saturated water first on-off valve 316, and other main steam. The first on-off valve 376, the main steam second on-off valve 377, the exhaust second on-off valve 357, and the saturated water third on-off valve 317 are closed. As a result, as shown by the thick line in this figure, the fluid below 500 ° C. flowing into the heat storage device 200 is guided to the heat exchange section in the medium temperature layer 220 and the low temperature layer 230.

The fluid flowing in from the main steam bypass pipe 167 enters the first medium heat exchange section 221 via the main steam bypass flow path 372 and the main steam third flow path 373. After heat exchange in the first medium heat exchange unit 221, the fluid whose temperature has dropped flows into the first low temperature heat exchange unit 231. After heat exchange in the first low temperature heat exchange unit 231, the fluid whose temperature has dropped further is discharged from the heat storage device 200 to the condenser 131 via the main steam bypass pipe 167.

The fluid flowing from the boiler bleeding pipe 165 into the boiler exhaust flow path 351 enters the second medium heat exchange section 222. After heat exchange in the second medium heat exchange unit 222, the fluid whose temperature has dropped flows into the second low temperature heat exchange unit 232. After heat exchange in the second low temperature heat exchange unit 232, the fluid whose temperature has dropped further is discharged from the heat storage device 200 to the condenser 131 via the boiler extraction pipe 165.

Water always flows through the saturated water pipe 161 that guides water from the brackish water separator 113 to the condenser 131. That is, a fluid of 100 ° C. or lower flows. Therefore, the fluid flowing into the saturated water flow path 311 connected to the saturated water pipe 161 enters the third low temperature heat exchange unit 233. After heat exchange in the third low temperature heat exchange unit 233, the fluid whose temperature has dropped is discharged from the heat storage device 200 to the condenser 131 via the saturated water pipe 161.

In the second start-up operation mode, as shown in FIG. 1 (a), the steam temperature is 500 ° C. or higher. In addition, the boiler start bleeding adjustment valve 175 is closed. Therefore, as shown in FIGS. 5 and 10B, the control device 150 opens the main steam first on-off valve 376 and the saturated water first on-off valve 316, and opens the main steam second on-off valve 377 and the main steam first on-off valve. (3) The on-off valve 378, the exhaust first on-off valve 356, the exhaust second on-off valve 357, and the saturated water third on-off valve 317 are closed. As a result, as shown by the thick line in this figure, the fluid having a temperature of 500 ° C. or higher flowing into the heat storage device 200 is guided to the heat exchange section in the high temperature layer 210, the medium temperature layer 220, and the low temperature layer 230. Further, the water below 100 ° C. flowing from the brackish water separator is guided to the low temperature layer 230 as in the first start operation mode.

The fluid flowing from the main steam bypass pipe 167 into the main steam first flow path 371 enters the high temperature heat exchange section 211. After heat exchange in the high temperature heat exchange unit 211, the fluid whose temperature has dropped enters the first medium heat exchange unit 221. After heat exchange in the first medium heat exchange unit 221, the fluid whose temperature has dropped flows into the first low temperature heat exchange unit 231. After heat exchange in the first low temperature heat exchange unit 231, the fluid whose temperature has dropped further is discharged from the heat storage device 200 to the condenser 131 via the main steam bypass pipe 167.

The fluid flowing into the saturated water flow path 311 from the saturated water pipe 161 that guides water from the steam separator 113 to the condenser 131 enters the third low-temperature heat exchange unit 233 and enters the third low-temperature heat exchange unit 233 as in the first start-up operation mode. After heat exchange in the low temperature heat exchange unit 233, the heat is discharged to the condenser 131 via the saturated water pipe 161.

FIG. 11A shows the state of the on-off valve in the first stop operation mode. As shown in FIG. 1 (b), the steam temperature is 500 ° C. or higher in the first stop operation mode. Therefore, as shown in FIGS. 5 and 11A, the control device 150 controls the opening and closing of each on-off valve as in the second start-up operation mode.

The state of the on-off valve in the pumping operation mode is shown in FIG. 11 (b). As shown in FIG. 2, the steam temperature is 500 ° C. or higher in the pumping operation mode. Therefore, as shown in FIGS. 6 and 11B, the control device 150 basically controls the opening and closing of each on-off valve in the same manner as in the second start-up operation mode. However, the saturated water first on-off valve 316 is closed.

FIG. 12 shows the state of the on-off valve in the emergency operation mode. In the emergency operation mode, it is necessary to flow the fluid through the condenser 131 as soon as possible regardless of the steam temperature to lower the temperature of the entire power plant 100. Therefore, in this case, the control device 150 controls to bypass the heat storage device 200 and guide the fluid to the condenser 131 without guiding the fluid to the heat storage device 200.

That is, as shown in FIG. 12, the main steam second on-off valve 377, the exhaust second on-off valve 357, and the saturated water third on-off valve 317 are opened, and the other on-off valves, the main steam first on-off valve 376, and the main The steam third on-off valve 378, the exhaust first on-off valve 356, and the saturated water first on-off valve 316 are closed. As a result, as shown by the thick line in this figure, the fluid does not flow into the heat exchange section in the heat storage device 200, but is discharged to the condenser 131.

The temperature range of each heat storage layer is determined according to the steam temperature at the time of events such as ignition, ventilation start, merge, equilibrium, equilibrium end, and stop in each operation mode. Further, the heat storage capacity of each heat storage layer is such that the amount of surplus heat energy generated in each heat storage period can be stored.

As described above, the power plant 100 of the present embodiment is provided with a pipe for guiding the fluid having thermal energy to the heat storage device 200 and a pipe for guiding the fluid to the heat storage device 200 only when excess heat energy is generated. A control device 150 for controlling an on-off valve is provided. Further, the heat storage device 200 includes a plurality of heat storage layers each having temperature characteristics in a plurality of different temperature ranges, a flow path for passing a fluid through each heat storage layer, and an on-off valve provided in the flow path. When the control device 150 controls to guide the fluid to the heat storage device 200, the control device 150 controls the heat energy of the fluid flowing into the heat storage device 200 to be stored in the heat storage layer according to the temperature range of the fluid.

Therefore, according to the present embodiment, the surplus heat energy generated in the power plant 100 can be stored in a mode in which it can be used efficiently.

In particular, according to the present embodiment, the surplus heat energy generated during the period when the boiler heat output at the start and stop of the power plant 100 exceeds the turbine generator load is appropriate according to the steam temperature and the temperature of the saturated water. Heat can be stored in the heat storage layer in the temperature range.

Although the temperature of the surplus steam was low, the total amount of heat was large during the period until the start-up. In the conventional power plant 100, all the surplus steam generated is returned to the condenser 131. Therefore, not only is there a lot of waste, but also a large receiving capacity is required on the condenser 131 side. However, according to the present embodiment, most of the heat of the fluid returned to the condenser 131 is stored in the heat storage device 200, so that the capacity of the condenser 131 can be suppressed. Therefore, the equipment cost can be suppressed.

Further, even during the pumping operation in which the generator load of the steam turbine 120 is suppressed to the amount of heat output of the boiler 110 or less, the excess heat energy generated by the boiler 110 during that period can be efficiently stored.

Further, in the heat storage device 200 of the present embodiment, as the heat storage material of each heat storage layer, a latent heat storage material that utilizes the phase transformation latent heat of the substance and has a different melting point is used. As a result, the generated surplus heat energy can be stored in each heat storage layer according to the melting point of the latent heat storage material forming the heat storage layer. Further, since such a latent heat storage material is used, it is possible to realize a heat storage unit capable of high-density heat storage that operates only by input / output of heat. Further, a high heat storage temperature can be realized by using an alloy-based material having a high melting point as the latent heat storage material. As a result, for example, a high-temperature fluid such as main steam can be stored at the same high temperature. In addition, it is possible to produce steam in the highest temperature range during heat recovery.

Further, in the heat storage device 200 of the present embodiment, a flow path is provided so as to flow into the heat storage layer of the heat storage material having a melting point lower than the temperature and having the closest melting point according to the temperature of the fluid flowing into the heat storage device 200. Controls the opening and closing of the on-off valve. Therefore, it is possible to realize heat storage for each of a plurality of temperature ranges with a simple configuration.

Further, each flow path in the heat storage device 200 is provided so that the fluid that has passed through the heat storage layer also passes through the heat storage layer if there is a heat storage layer composed of the heat storage material having the next highest melting point after the heat storage material. Be done. That is, by arranging the heat storage layers in the order of high temperature, medium temperature, and low temperature in one flow path, the heat of the fluid can be completely recovered. According to the power generation plant 100 having the heat storage device 200 of the present embodiment, the efficient operation of the power generation plant 100 can be realized, including the utilization of the fully recovered thermal energy for startup and the like.

Further, according to the heat storage device 200 of the present embodiment, a heat storage layer having a performance that is not excessive or insufficient with respect to the temperature range of the fluid is arranged for each temperature range of the fluid. For example, when used for heat storage of excess heat energy at startup, the temperature range of each heat storage layer is determined according to the steam temperature after a predetermined time has elapsed after ignition of the boiler 110. Further, the heat storage capacity of each heat storage layer is determined according to the amount of surplus heat energy after the lapse of each time.

This enables efficient heat recovery. For example, if the heat storage unit is prepared according to the highest expected temperature of the fluid flowing into the heat storage device 200, the heat recovery of the medium-temperature or low-temperature fluid becomes over-specification and wasteful. However, according to the present embodiment, since heat is stored in an appropriate heat storage layer for each temperature range, such waste can be avoided.

As described above, in the power plant 100 including the heat storage device 200 of the present embodiment, in order to recover the heat of the fluid completely in the heat storage device 200, the fluid discharged from the heat storage device 200 to the condenser 131 The temperature goes down. Therefore, the amount of heat returned to the condenser 131 can be suppressed.

<< Second Embodiment >>
Next, a second embodiment of the present invention will be described. In the first embodiment, the main steam bypass pipe 167 branching from the main steam pipe 162 is provided, and the heat storage device 200 stores the heat of the fluid passing through the main steam bypass pipe 167. However, the present embodiment further includes a reheat steam bypass pipe branching from the high temperature reheat steam pipe 164. Then, the heat storage device 200 also stores heat of the fluid passing through the reheat steam bypass pipe.

Hereinafter, this embodiment will be described with a focus on a configuration different from that of the first embodiment.

FIG. 13A is a fluid system diagram of the power plant 101 of the present embodiment. The power generation plant 101 of the present embodiment has the configuration of the power generation plant 100 of the first embodiment, and further branches from the reheat steam bypass pipe 168 branching from the high temperature reheat steam pipe 164 and the main steam pipe 162, and high-pressure steam. A high-pressure steam turbine bypass pipe 169 that bypasses the turbine 121 and connects to the low-temperature reheat steam pipe 163 is provided. That is, in the present embodiment, the main steam pipe 162 and the low temperature reheat steam pipe 163 are connected to each other via the high pressure steam turbine bypass pipe 169.

The reheat steam bypass pipe 168 is provided with a reheat steam bypass on-off valve 178. The high-pressure steam turbine bypass pipe 169 is provided with a high-pressure steam turbine bypass on-off valve 179. Further, the reheated steam bypass pipe 168 is provided with a temperature sensor 188 that detects the temperature of steam passing through the inside.

Further, the heat storage device 201 of the present embodiment is arranged on the saturated water pipe 161, the boiler bleeding pipe 165, the main steam bypass pipe 167, and the reheat steam bypass pipe 168. The steam after heat exchange in the heat storage device 201 is introduced into the condenser 131.

Even in the present embodiment, as in the first embodiment, the control device 150 is instructed from the outside (control table 151 or the like placed in the power plant) or is installed in the power generation plant 101 at the above temperature. It controls the opening and closing of each on-off valve according to signals from various sensors including sensors 181, 185, 187, and 188.

Since the other configurations are the same as the configurations of the same name in the first embodiment, the description thereof will be omitted here. Hereinafter, the same shall apply in this embodiment.

[Heat storage device]
Next, the heat storage device 201 of this embodiment will be described with reference to FIG. 13 (b).

Like the heat storage device 200 of the first embodiment, the heat storage device 201 of the present embodiment is also provided with a plurality of heat storage layers composed of heat storage materials having temperature characteristics (melting points) in different temperature ranges, and in each heat storage layer. A flow path that connects to the heat exchange unit and the heat storage device 201 to guide the fluid in the pipe to the heat exchange unit, or bypasses the heat storage device 200 and guides the fluid in the pipe to the condenser 131. It is provided with an on-off valve (valve) that regulates the inflow of fluid into the flow path.

Then, as in the first embodiment, in the heat storage device 201, the path through which the fluid passes is changed by opening and closing the on-off valve according to the command from the control device 150 according to the temperature of the fluid flowing into the heat storage device 201. And store heat in an appropriate temperature range.

In the present embodiment as well, as in the first embodiment, a case where the high temperature layer 210, the medium temperature layer 220, and the low temperature layer 230 are provided as the heat storage layer will be described as an example.

Further, as the heat exchange unit, as in the first embodiment, the high temperature heat exchange unit 211 arranged in the high temperature layer 210, the first medium heat exchange unit 221 arranged in the medium temperature layer 220, and the second medium heat exchange unit The exchange unit 222 includes a first low-temperature heat exchange unit 231, a second low-temperature heat exchange unit 232, and a third low-temperature heat exchange unit 233 arranged in the low-temperature layer 230. Further, in the present embodiment, the high temperature layer 210 is provided with the reheat high temperature heat exchange unit 214, the medium temperature layer 220 is provided with the reheat medium heat exchange unit 224, and the low temperature layer 230 is provided with the reheat low temperature heat exchange unit 234.

Further, as the flow paths used during heat storage, as in the first embodiment, the main steam first flow path 371, the main steam bypass flow path 372, the main steam third flow path 373, and the boiler exhaust flow path 351 , The boiler exhaust bypass flow path 352, the saturated water flow path 311 and the saturated water bypass flow path 312 are provided. The heat storage device 201 of the present embodiment further includes a reheated steam first flow path 381, a reheated steam bypass flow path 382, and a reheated steam third flow path 383.

The reheated steam first flow path 381 is connected to the reheated steam bypass pipe 168. In the present embodiment, the reheat steam bypass pipe 168 is branched at the branch point 307, and the reheat high temperature heat exchange unit 214, the reheat medium heat exchange unit 224, and the reheat low temperature heat exchange unit 234 are connected in this order, and the confluence point is reached. Connect to the reheat steam bypass pipe 168 at 308. As a result, the reheated steam first flow path 381 allows the fluid flowing into the heat storage device 201 from the reheated steam bypass pipe 168 to be reheated to the high temperature heat exchange unit 214, the reheated medium heat exchange unit 224, and the reheated low temperature heat exchange unit 234. It is discharged from the heat storage device 201, passed through the reheat steam bypass pipe 168, and returned to the condenser 131. During this time, the fluid passing through the reheated steam first flow path 381 exchanges heat in each heat storage layer and stores heat in each heat storage layer. When the temperature of the supplied fluid is higher than the melting point of the high temperature layer 210, the thermal energy of the fluid is stored in the order of the high temperature layer 210, the medium temperature layer 220, and the low temperature layer 230.

The reheat steam bypass flow path 382 bypasses the heat storage device 201 and returns the fluid flowing through the reheat steam bypass pipe 168 to the condenser 131. The reheat steam bypass flow path 382 branches at the branch point 307, bypasses the reheat high temperature heat exchange unit 214, the reheat medium heat exchange unit 224, and the reheat low temperature heat exchange unit 234, and reheat steam bypass at the confluence point 308. It joins tube 168.

The reheated steam third flow path 383 branches from the reheated steam bypass flow path 382, bypasses the reheated high temperature heat exchange section 214, and joins the reheated steam first flow path 381. As a result, the reheated steam third flow path 383 allows the fluid flowing into the heat storage device 201 from the reheated steam bypass pipe 168 to pass through the reheated medium-temperature heat exchange section 224 and the reheated low-temperature heat exchange section 234 in this order, and the reheated steam storage device It is discharged from 201 and returned to the condenser 131 via the reheat steam bypass pipe 168. When the temperature of the supplied fluid is higher than the melting point of the medium temperature layer 220, the heat energy of the fluid is stored in the order of the medium temperature layer 220 and the low temperature layer 230.

Further, as the on-off valve, the heat storage device 201 includes a main steam first on-off valve 376, a main steam second on-off valve 377, a main steam third on-off valve 378, and an exhaust first on-off valve 356, as in the first embodiment. The exhaust second on-off valve 357, the saturated water first on-off valve 316, and the saturated water third on-off valve 317 are provided. Further, the reheated steam first on-off valve 386, the reheated steam second on-off valve 387, the reheated steam third on-off valve 388, the first heat recovery on-off valve 411, the second heat recovery on-off valve 421, and the like. A third heat recovery on-off valve 431 is provided.

The reheat steam first on-off valve 386 is provided downstream of the branch point 307 of the reheat steam first flow path 381, and controls the inflow of fluid into the reheat high temperature heat exchange unit 214.

The reheated steam third on-off valve 388 is provided downstream of the branch point of the reheated steam third flow path 383 with the reheated steam bypass flow path 382, and the fluid flows into the reheated steam third flow path 383. To control.

The reheat steam second on-off valve 387 is provided downstream of the branch point of the reheat steam bypass flow path 382 with the reheat steam third flow path 383, and allows fluid to flow into the reheat steam bypass flow path 382. Control.

Also in the present embodiment, as in the first embodiment, each on-off valve is opened and closed in response to a command from the control device 150 issued according to the temperature of the fluid flowing through the installed flow path. Since the heat storage material and the like used for each heat storage layer are the same as those in the first embodiment, the description thereof will be omitted here.

Further, each flow path used at the time of heat recovery, the first heat recovery tube 410, the second heat recovery tube 420 and the third heat recovery tube 430 are further described as a reheat high temperature heat exchange unit 214 and a reheat medium heat exchange unit, respectively. 224 and the reheat low temperature heat exchange unit 234 also pass through.

[Control of on-off valve by control device]
Hereinafter, control of the on-off valve by the control device 150 in the power plant 101 including the heat storage device 201 of the present embodiment will be described. Each operation mode is the same as that of the first embodiment.

Also in this embodiment, the opening and closing of the on-off valve provided in each pipe of the power plant 101 is controlled according to the operation mode. Further, the opening and closing of the on-off valve provided in each flow path of the heat storage device 201 is controlled according to the temperature of the fluid on the inlet side of each flow path. Further, the open / closed state of each on-off valve for each operation mode is stored in advance in the storage device of the control device 150 as an open / close state table. In the initial state, each on-off valve is in a closed state unless otherwise specified.

The operation mode of each on-off valve and the opening / closing time chart for each event are shown in FIGS. 14 and 15.

The opening / closing timing of the on-off valve included in the power plant 100 of the first embodiment is the same as that of the first embodiment. The reheated steam bypass on-off valve 178, the reheated steam first on-off valve 386, the reheated steam second on-off valve 387, and the reheated steam third on-off valve 388 of the present embodiment are of the first embodiment. It is the same as 177, 376, 377, 378. Further, the high-pressure steam turbine bypass on-off valve 179 is opened when heat is stored in the heat storage device 201. That is, it is opened and closed at the same timing as the reheat steam bypass on-off valve 178.

Also in the present embodiment, the control device 150 controls the opening and closing of each on-off valve according to the instruction from the control table 151 and the like. In the present embodiment as well, as in the first embodiment, the control device 150 may control the opening and closing according to the detection result of each temperature sensor. The open / closed state of each on-off valve for each operation mode is stored in advance in the storage device of the control device 150 as an open / close state table.

Next, the control of the on-off valve of the heat storage device 201 in the first start operation mode, the second start operation mode, the first stop operation mode, and the pumping operation mode in which the fluid is guided to the heat storage device 201 will be described. Here, the control of the on-off valve of the heat storage device 201 in the emergency operation mode will also be described.

Also in this embodiment, since the control of the on-off valve of the heat storage device 201 at the time of heat storage is explained, the heat recovery on-off valves 411, 421 and 431 are omitted. At the time of heat storage, these heat recovery on-off valves 411, 421 and 431 are basically kept in a closed state.

In the first start operation mode, the control device 150 includes a main steam third on-off valve 378, a reheated steam third on-off valve 388, an exhaust first on-off valve 356 and saturation, as shown in FIGS. 14 and 16 (a). The water first on-off valve 316 is opened, and the other main steam first on-off valve 376, main steam second on-off valve 377, reheated steam first on-off valve 386, reheated steam second on-off valve 387, exhaust second on-off valve 387. The valve 357 and the saturated water third on-off valve 317 are closed. As a result, as shown by the thick line in this figure, the fluid below 500 ° C. flowing into the heat storage device 200 is guided to the heat exchange section in the medium temperature layer 220 and the low temperature layer 230.

The fluid flowing in from the reheated steam bypass pipe 168 enters the reheated medium heat exchange section 224 via the reheated steam bypass flow path 382 and the reheated steam third flow path 383. After heat exchange in the reheat medium heat exchange unit 224, the fluid whose temperature has dropped flows into the reheat low temperature heat exchange unit 234. After heat exchange in the reheat low temperature heat exchange unit 234, the fluid whose temperature has dropped further is discharged from the heat storage device 201 to the condenser 131 via the reheat steam bypass pipe 168.

In the second start-up operation mode, the control device 150 sets the main steam first on-off valve 376, the reheated steam first on-off valve 386, and the saturated water first on-off valve 316, as shown in FIGS. 14 and 16 (b). Opened, main steam second on-off valve 377, main steam third on-off valve 378, reheated steam second on-off valve 387, reheated steam third on-off valve 388, exhaust first on-off valve 356, exhaust second on-off valve 357. , And the saturated water third on-off valve 317 is closed. As a result, as shown by the thick line in this figure, the fluid having a temperature of 500 ° C. or higher flowing into the heat storage device 201 is guided to the heat exchange portions in the high temperature layer 210, the medium temperature layer 220, and the low temperature layer 230. Further, the water below 100 ° C. flowing from the brackish water separator is guided to the low temperature layer 230 as in the first start operation mode.

The fluid flowing from the reheat steam bypass pipe 168 into the reheat steam first flow path 381 enters the reheat high temperature heat exchange unit 214. After heat exchange in the reheat high temperature heat exchange unit 214, the fluid whose temperature has dropped enters the reheat medium heat exchange unit 224. After heat exchange in the reheat medium heat exchange unit 224, the fluid whose temperature has dropped flows into the reheat low temperature heat exchange unit 234. After heat exchange in the reheat low temperature heat exchange unit 234, the fluid whose temperature has dropped further is discharged from the heat storage device 201 to the condenser 131 via the reheat steam bypass pipe 168.

FIG. 17 (a) shows the state of the on-off valve in the first stop operation mode. As shown in FIGS. 14 and 17 (a), the control device 150 controls the opening and closing of each on-off valve as in the second start-up operation mode.

The state of the on-off valve in the pumping operation mode is shown in FIG. 17 (b). As shown in FIGS. 15 and 17B, the control device 150 basically controls the opening and closing of each on-off valve in the same manner as in the second start-up operation mode. However, the saturated water first on-off valve 316 is closed.

FIG. 18 shows the state of the on-off valve in the emergency operation mode. In the emergency operation mode, the control device 150 controls to bypass the heat storage device 201 and guide the fluid to the condenser 131 without guiding the fluid to the heat storage device 201 regardless of the steam temperature.

That is, as shown in FIG. 18, the main steam second on-off valve 377, the reheated steam second on-off valve 387, the exhaust second on-off valve 357, and the saturated water third on-off valve 317 are opened, and other on-off valves. Close the main steam first on-off valve 376, main steam third on-off valve 378, reheated steam first on-off valve 386, reheated steam third on-off valve 388, exhaust first on-off valve 356 and saturated water first on-off valve 316. And. As a result, as shown by the thick line in this figure, the fluid does not flow into the heat exchange section in the heat storage device 201, but is discharged to the condenser 131.

In each operation mode, the flow of the fluid flowing into the heat storage device 201 from the main steam bypass pipe 167, the boiler extraction pipe 165, and the saturated water pipe 161 is the same as in the first embodiment.

As described above, the power plant 101 of the present embodiment acquires surplus heat energy from the high temperature reheat steam pipe 164 in addition to the power plant 100 of the first embodiment, and stores the heat in the heat storage device 201.

Therefore, in addition to the effect of the first embodiment, according to the present embodiment, for example, excess steam can be efficiently stored even during FCB (Fast Cut Back) operation.

Generally, during FCB operation, a faster load change is required than during normal stop, and the amount of heat of excess steam is large. In the conventional power plant 100, if the FCB function is provided, all the surplus steam generated will be returned to the condenser 131. For this reason, not only is there a lot of waste, but also a large receiving capacity is required on the condenser 131 side. Large-scale construction is required to realize the large receiving capacity of the condenser 131. However, according to the present embodiment, most of the heat of the fluid returned to the condenser 131 is stored in the heat storage device 201, so that the performance of the condenser 131 is the condenser 131 used when there is no FCB function. It may be almost equivalent to. Therefore, according to the present embodiment, the equipment cost can be further suppressed.

<Modification example 1>
[Modification example of heat storage device]
In each of the above embodiments, the heat storage devices 200 and 201 control the opening and closing of the on-off valve according to a predetermined event. However, it is not limited to this. For example, conversely, a temperature threshold value may be set according to the temperature range of the heat storage layer, and the control device 150 may control the opening and closing of the on-off valve according to the temperature threshold value.

This modification will be described by taking the power plant 100 and the heat storage device 200 of the first embodiment as an example.

As shown in FIG. 19A, the heat storage device 202 of this modification has the configuration of the heat storage device 200 of the first embodiment, and further includes a main steam fourth flow path 374 and a main steam fourth on-off valve 379. The boiler exhaust fourth flow path 354 and the exhaust fourth on-off valve 359 are provided. Here, the heat recovery on-off valves 411, 421, and 431 are omitted. Hereinafter, the same applies to each modification of the heat storage device 200.

The main steam fourth flow path 374 branches from the main steam bypass flow path 372, bypasses the high temperature heat exchange section 211 and the first medium temperature heat exchange section 221 and joins the main steam first flow path 371. As a result, the main steam fourth flow path 374 allows the fluid flowing from the main steam bypass pipe 167 into the heat storage device 202 to pass through the first low temperature heat exchange unit 231 and is discharged from the heat storage device 202, and the main steam bypass pipe 167. After that, it is returned to the condenser 131.

The main steam fourth on-off valve 379 is provided downstream of the branch point of the main steam fourth flow path 374 with the main steam bypass flow path 372, and controls the inflow of fluid into the main steam fourth flow path 374.

The fourth boiler exhaust flow path 354 branches from the boiler exhaust bypass flow path 352, bypasses the second medium heat exchange section 222, and joins the boiler exhaust flow path 351. As a result, the fourth flow path 354 for exhausting the boiler allows the fluid flowing from the boiler extraction pipe 165 into the heat storage device 202 to pass through the second low temperature heat exchange unit 232 and is discharged from the heat storage device 202, and passes through the boiler extraction pipe 165. , Return to the condenser 131.

The exhaust fourth on-off valve 359 is provided downstream of the branch point of the boiler exhaust fourth flow path 354 with the boiler exhaust bypass flow path 352, and controls the inflow of fluid into the boiler exhaust fourth flow path 354.

The control device 150 controls the opening and closing of each on-off valve according to the detection results of the temperature sensor 187 provided in the main steam bypass pipe 167 and the temperature sensor 185 provided in the boiler extraction pipe 165. For example, the timing of opening / closing control when the steam temperature increases monotonically is shown in FIGS. 19 (b) and 19 (c). Since the explanation is for heat storage, the main steam second on-off valve 377 and the exhaust second on-off valve 357 are omitted in these figures.

As shown in FIG. 19B, when the temperature detected by the temperature sensor 187 is less than 400 ° C., the main steam fourth on-off valve 379 is opened in each flow path connected to the main steam bypass pipe 167. The other on-off valves, the main steam first on-off valve 376, the main steam second on-off valve 377, and the main steam third on-off valve 378 are closed. As a result, when the steam temperature is less than 400 ° C., the fluid is guided to the first low temperature heat exchange unit 231 and heat exchanges in the first low temperature heat exchange unit 231 to bypass the main steam from the main steam first flow path 371. It is discharged to the condenser 131 via the pipe 167.

When the temperature detected by the temperature sensor 187 is 400 ° C. or higher and lower than 500 ° C., the main steam third on-off valve 378 is opened in each flow path connected to the main steam bypass pipe 167, and other on-off valves are used. The main steam first on-off valve 376, the main steam second on-off valve 377, and the main steam fourth on-off valve 379 are closed. As a result, when the steam temperature is 400 ° C. or higher and lower than 500 ° C., the fluid is guided to the first medium heat exchange unit 221 and the fluid whose temperature has dropped after heat exchange at the first medium heat exchange unit 221 is released. It flows into the first low temperature heat exchange unit 231. After heat exchange in the first low temperature heat exchange unit 231, the fluid whose temperature has dropped further is discharged from the heat storage device 200 to the condenser 131 via the main steam bypass pipe 167.

When the temperature detected by the temperature sensor 187 is 500 ° C. or higher, the main steam first on-off valve 376 is opened in each flow path connected to the main steam bypass pipe 167, and the other on-off valve, the main steam second, is opened. The on-off valve 377, the main steam third on-off valve 378, and the main steam fourth on-off valve 379 are closed. As a result, when the steam temperature is 500 ° C. or higher, the fluid is guided to the high-temperature heat exchange unit 211, and after heat exchange at the high-temperature heat exchange unit 211, the fluid whose temperature has dropped is transferred to the first medium-temperature heat exchange unit 221. After being guided and exchanging heat in the first medium temperature heat exchange unit 221, the fluid whose temperature has dropped flows into the first low temperature heat exchange unit 231. After heat exchange in the first low temperature heat exchange unit 231, the fluid whose temperature has dropped further is discharged from the heat storage device 200 to the condenser 131 via the main steam bypass pipe 167.

Further, as shown in FIG. 19C, when the temperature detected by the temperature sensor 185 is less than 400 ° C., the exhaust fourth on-off valve 359 is opened in each flow path connected to the boiler bleeding pipe 165. The other on-off valves, the first exhaust on-off valve 356 and the second exhaust on-off valve 357, are closed. As a result, when the steam temperature is less than 400 ° C., the fluid is guided to the second low temperature heat exchange unit 232, heat exchange is performed by the second low temperature heat exchange unit 232, and the boiler exhaust pipe 165 from the boiler exhaust flow path 351. Is discharged to the condenser 131.

When the temperature detected by the temperature sensor 185 is 400 ° C. or higher and lower than 500 ° C., the exhaust first on-off valve 356 is opened in each flow path connected to the boiler extraction pipe 165, and the other on-off valve, the exhaust first on-off valve, is opened. (Ii) The on-off valve 357 and the exhaust fourth on-off valve 359 are closed. As a result, when the steam temperature is 400 ° C or higher and lower than 500 ° C, the fluid is guided to the second medium heat exchange unit 222, and after heat exchange at the second medium heat exchange unit 222, the fluid whose temperature has dropped is released. It flows into the second low temperature heat exchange unit 232. After heat exchange in the second low temperature heat exchange unit 232, the fluid whose temperature has dropped further is discharged from the heat storage device 200 to the condenser 131 via the boiler extraction pipe 165.

For example, when the period from the shutdown of the power plant 100 to the start is vacant, as shown in FIG. 20, the initial steam temperature output from the boiler 110 drops significantly from 500 ° C. The heat storage device 202 of the present modification can efficiently store heat in the heat storage layer in the optimum temperature range even in such a case.

Although the power plant 100 and the heat storage device 200 of the first embodiment have been described here as an example, the same applies to the power plant 101 and the heat storage device 201 of the second embodiment. The opening and closing of each on-off valve is controlled according to the detection result of the temperature sensor 188 installed in the reheat steam bypass pipe 168, and the fluid is first guided to the heat exchange part of the heat storage layer in the temperature zone corresponding to the detection result. ..

<Modification 2>
[Modification example of heat storage device]
As shown in FIG. 21A, the heat exchange portions in each heat storage layer may be provided with a flow path so as to be connected in series and in parallel. In FIG. 21A, each bypass flow path of the main steam bypass flow path 372, the boiler exhaust bypass flow path 352, and the saturated water bypass flow path 312 is omitted.

In this modification, the main steam third flow path 373 allows the fluid flowing into the heat storage device 203 to pass through the first parallel medium heat exchange section 221b and the first parallel low temperature heat exchange section 231b in this order, and is transmitted from the heat storage device 203. Discharge.

Further, the main steam fourth flow path 374 allows the fluid flowing into the heat storage device 203 to pass through the second parallel low temperature heat exchange unit 231c and is discharged from the heat storage device 203.

Further, the boiler exhaust third flow path 353 allows the fluid flowing into the heat storage device 203 to pass through the third parallel low temperature heat exchange unit 232b and is discharged from the heat storage device 203.

The opening / closing control of each on-off valve according to the detected values of the temperature sensors 187 and 185 by the control device 150 is the same as that of the first modification.

<Modification example 3>
[Modification example of heat storage device]
Further, as shown in FIG. 21B, the heat exchange portions in each heat storage layer may be provided with a flow path so as to be connected in parallel. In FIG. 21B, each bypass flow path of the main steam bypass flow path 372, the boiler exhaust bypass flow path 352, and the saturated water bypass flow path 312 is omitted.

In this modification, the main steam third flow path 373 allows the fluid flowing into the heat storage device 204 to pass through the first parallel medium heat exchange unit 221b and is discharged from the heat storage device 203.

Further, the main steam fourth flow path 374 allows the fluid flowing into the heat storage device 203 to pass through the second parallel low temperature heat exchange unit 231c and is discharged from the heat storage device 203.

Further, the boiler exhaust third flow path 353 allows the fluid flowing into the heat storage device 203 to pass through the third parallel low temperature heat exchange unit 232b and is discharged from the heat storage device 203.

The opening / closing control of each on-off valve according to the detected values of the temperature sensors 187 and 185 by the control device 150 is the same as that of the first modification.

<Modification example 4>
[Modification example of heat storage device]
Further, one heat exchange unit of the heat storage device 205 may be provided in each heat storage layer for each inflow path. An example of the heat storage device 205 in this case is shown in FIG. 22 (a).

As shown in this figure, one heat exchange unit is provided in each heat storage layer for each of the main steam bypass pipe 167, the boiler extraction pipe 165, and the saturated water pipe 161 and are connected in series and in parallel.

The opening / closing control of each on-off valve according to the detected values of the temperature sensors 187 and 185 by the control device 150 is the same as that of the first modification.

<Modification 5>
[Modification example of heat storage device]
Further, as shown in FIG. 22B, one heat exchange unit of the heat storage device 205 may be provided in each heat storage layer. The opening / closing control of each on-off valve according to the detected values of the temperature sensors 187 and 185 in this case is the same as that of the first modification. However, in this case, the fluid discharged from the heat storage device 205 is returned to the condenser 131 via any of the main steam bypass pipe 167, the boiler bleeding pipe 165, and the saturated water pipe 161 regardless of the inflow path. ..

As shown in the modified example 4 and the modified example 5, by sharing the heat storage unit, it is possible to obtain the same effect as the other heat storage device 200 with a simpler configuration.

In each of the above-described embodiments and modifications, the case where the heat storage device 200 includes three heat storage layers of a high temperature heat storage layer 210, a medium temperature heat storage layer 220, and a low temperature heat storage layer 230 will be described as an example. However, the number of heat storage layers is not limited to this. As long as there are two or more layers, the number does not matter. Further, with respect to each flow path, it is not always necessary to provide a heat exchange unit (heat storage unit) in each heat storage layer.

For example, when the heat storage device 200 has a two-layer structure of a high temperature layer 210 and a medium temperature layer 220, the heat exchange unit provided in the high temperature layer 210 is the first heat storage unit, and the heat exchange unit provided in the medium temperature layer 220 is. Corresponds to the second heat storage unit. Further, when the heat storage device 200 has a three-layer structure further including the low temperature layer 230, the heat exchange unit provided in the low temperature layer 230 corresponds to the third heat storage unit. When the heat storage device 200 has a two-layer structure consisting of a medium temperature layer 220 and a low temperature layer 230, the heat exchange unit provided in the medium temperature layer 220 is the first heat storage unit, and the heat exchange unit provided in the low temperature layer 230 is the first. (Ii) Corresponds to the heat storage section.

<Modification 6>
Further, in each of the above embodiments, when the plant is stopped, as shown in FIG. 1B, the generator load of the steam turbine 120 is reduced in accordance with the decrease in the output of the boiler 110. Then, the time when the boiler 110 reaches the minimum load is set as the end of equilibrium, and the surplus heat energy generated thereafter is stored. However, the operation mode and heat storage of each configuration when the plant is stopped are not limited to this.

For example, the reduction rate of the generator load of the steam turbine 120 may be increased to be higher than the output reduction of the boiler 110. In this case, as shown in FIG. 23, the equilibrium state ends before the boiler 110 reaches the minimum load. Then, the surplus heat energy generated after the end of this equilibrium may be stored.

As a result, the reduction rate of the generator load of the steam turbine 120 can be controlled independently of the output reduction rate of the boiler 110. That is, the reduction rate of the generator load can be increased as compared with the case where the generator load of the steam turbine 120 is reduced in accordance with the decrease in the output of the boiler 110. Therefore, the period until the power plant 100 is stopped can be shortened, and the power plant 100 can be operated efficiently. In addition, the surplus heat energy generated after the end of equilibrium can be stored in the heat storage device of any of the above-described embodiments and modifications in a manner that can be efficiently used.

<< Third Embodiment >>
Next, a third embodiment of the present invention will be described. This embodiment is an embodiment of recovering heat energy from a heat storage device having a plurality of heat storage layers in different temperature ranges. As the heat storage device, any of the above-described embodiments and modifications (hereinafter, represented by the heat storage device 200) can be used. However, the heat storage device used is not limited to this. Hereinafter, the present embodiment will be described by taking the case of using the heat storage device 200 as an example.

As described above, the heat storage device 200 stores heat energy in a plurality of temperature ranges. Therefore, even when the heat is recovered from the heat storage device 200, it can be recovered for each temperature range and can be provided to the user. Here, as an example, when the heat energy recovered from each heat storage layer is supplied to each heat exchanger (boiler heat exchange unit) in the boiler 110 and the high-pressure heater 136 in the front stage of the boiler 110 according to the design temperature. An example is shown.

An example of the design temperature of each heat exchanger of the boiler 110 is shown in FIG. 24 (a). Here, it is assumed that the boiler 110 includes a primary superheater 114a and a secondary superheater 114b.

As shown in this figure, the design temperature on the outlet side of each of the high pressure heater 136 and the economizer 111 is 290 ° C. and 340 ° C. The design temperatures of the inlet side and the outlet side of the primary superheater 114a are 430 ° C. and 470 ° C., respectively.

In the present embodiment, a part of the fluid supplied to the high-pressure heater 136 is heated by passing through the low-temperature layer 230 and supplied to the outlet side of the high-pressure heater 136 or the outlet side of the economizer 111. Further, a part of the fluid supplied to the economizer 111 is heated by passing through the medium temperature layer 220, and is supplied to the outlet side of the economizer 111 or the outlet side of the furnace water cooling wall 112. Further, a part of the fluid supplied to the primary superheater 114a is heated by passing through the high temperature layer 210, and is supplied to the outlet side of the primary superheater 114a or the outlet side of the secondary superheater 114b.

In this case, as shown in FIG. 24B, the inlet side of the third heat recovery pipe 430 that recovers heat energy from the low temperature layer 230 of the heat storage device 200 is connected to the pipe on the inlet side of the high pressure heater 136. Further, the outlet side of the third heat recovery pipe 430 is branched into two, and is connected to the pipe on the outlet side of the high-pressure heater 136 and the outlet side of the economizer 111, respectively. The third heat recovery pipe 430 after branching is provided with heat recovery on-off valves 433 and 434, respectively. After recovering heat from the low temperature layer 230, these heat recovery on-off valves 433 and 434 are controlled to open and close by the control device 150 according to the operating state (fluid temperature and the like). Specifically, the third heat recovery pipe 430 is provided with a temperature sensor that detects the temperature of the fluid on the outlet side thereof. The control device 150 obtains the fluid temperature after heat recovery from the low temperature layer 230 based on the detected value of the temperature sensor. Then, the opening and closing is controlled so as to return to the boiler heat exchange section having a design temperature higher than the obtained fluid temperature.

The inlet side of the second heat recovery pipe 420 that recovers heat energy from the medium temperature layer 220 of the heat storage device 200 is connected to the pipe on the inlet side of the economizer 111. Further, the outlet side of the second heat recovery pipe 420 is branched into two, and is connected to the outlet side pipe of the economizer 111 and the outlet side pipe of the furnace water cooling wall 112, respectively. The second heat recovery pipe 420 after branching is provided with heat recovery on-off valves 423 and 424, respectively. After recovering heat from the medium temperature layer 220, these heat recovery on-off valves 423 and 424 are controlled to open and close by the control device 150 according to the operating state (fluid temperature and the like). Specifically, the second heat recovery pipe 420 is provided with a temperature sensor that detects the temperature of the fluid on the outlet side thereof. The control device 150 obtains the fluid temperature after heat recovery from the medium temperature layer 220 based on the detected value of the temperature sensor. Then, the obtained control device 150 controls opening and closing so as to return to the boiler heat exchange unit having a design temperature higher than the fluid temperature.

The inlet side of the first heat recovery pipe 410 that recovers heat energy from the high temperature layer 210 of the heat storage device 200 is connected to the pipe on the inlet side of the primary superheater 114a. The outlet side of the first heat recovery pipe 410 is branched into two and is connected to the outlet side pipe of the primary superheater 114a and the outlet side pipe of the secondary superheater 114b, respectively. The first heat recovery pipe 410 after branching is provided with heat recovery on-off valves 413 and 414, respectively. After recovering heat from the high temperature layer 210, these heat recovery on-off valves 413 and 414 are controlled to open and close by the control device 150 according to the operating state (fluid temperature and the like). Specifically, the first heat recovery pipe 410 is provided with a temperature sensor that detects the temperature of the fluid on the outlet side thereof. The control device 150 obtains the fluid temperature after heat recovery from the high temperature layer 210 based on the detected value of the temperature sensor. Then, the obtained control device 150 controls opening and closing so as to return to the boiler heat exchange unit having a design temperature higher than the fluid temperature.

The fluid passing through the third heat recovery tube 430 passes through the first low temperature heat exchange section 231 and the second low temperature heat exchange section 232 and the third low temperature heat exchange section 233 of the low temperature layer 230, and heat is generated in these heat exchange sections. To collect. As a result, a fluid having a temperature in the temperature range of the low temperature layer 230 is generated. Further, the fluid passing through the second heat recovery pipe 420 passes through the first medium heat exchange section 221 and the second medium heat exchange section 222 of the medium temperature layer 220, and recovers heat in these heat exchange sections. As a result, a fluid having a temperature in the temperature range of the medium temperature layer 220 is generated. The fluid passing through the first heat recovery pipe 410 passes through the high temperature heat exchange unit 211 to recover heat. As a result, a fluid having a temperature in the temperature range of the high temperature layer 210 is generated.

As described above, at the time of heat recovery, the control device 150 controls the first heat recovery on-off valve 411, the second heat recovery on-off valve 421, and the third heat recovery on-off valve 431 in an open state. The power plants 100 and 101 include temperature sensors that detect the temperature of each heat storage layer. The control device 150 monitors the temperature of each heat storage layer detected by these temperature sensors, and determines that the heat recovery is completed when the temperature becomes lower than the predetermined set temperature of each heat storage layer. Then, when it is determined that the heat recovery is completed, the control device 150 controls to close these heat recovery on-off valves 411, 421, and 431, respectively.

Further, at the time of heat recovery, the control device 150 opens the main steam on-off valve 172 and the reheat steam on-off valve 174 in the power plant 100 of the first embodiment. Further, the boiler start air extraction adjustment valve 175 and the main steam bypass on-off valve 177 are closed. Further, in the power plant 101 of the second embodiment, the reheat steam bypass on-off valve 178 and the high-pressure steam turbine bypass on-off valve 179 are further closed.

As described above, according to the heat storage device 200 of the present embodiment, it is possible to independently and independently recover a plurality of heat energies having different temperatures according to the melting point in each heat storage layer at the time of heat recovery. Then, the recovered thermal energy of different temperatures can be provided to the usage destination according to the required temperature. That is, according to the heat storage device 200 of the present embodiment, it is possible to realize proper use of heat according to the application.

Further, in the power plant 100 provided with the heat storage device 200 of the present embodiment, the surplus heat energy is independently stored in the heat storage device 200 for each temperature zone. Therefore, when the heat is recovered from the heat storage device 200, the surplus heat energy can be efficiently used by recovering the heat from the heat storage layer in which the heat energy corresponding to the temperature required by the boiler heat exchange unit to be used is stored.

For example, as shown in FIG. 25A as “release of heat storage energy”, by utilizing this surplus heat energy at startup, optimum heat energy can be provided to each heat exchanger of the boiler 110. , Can be launched quickly.

Further, the power generation plant 100 may be operated while recovering the surplus heat energy stored in the heat storage device 200 not only at the time of startup but also during normal operation, for example.

For example, as shown in FIG. 25B, the load on the boiler 110 is reduced while keeping the output of the steam turbine 120 constant (suppression of boiler heat generation). Further, as shown in the figure, the load of the steam turbine 120 is increased while keeping the load of the boiler 110 constant (steam turbine drive promotion). By utilizing the surplus heat energy stored in the heat storage device 200 in this way, the fuel used for combustion of the boiler 110 can be saved.

Further, as shown in FIG. 26, in the pumping operation mode, when the power plant 100 is stopped, the reduction rate of the generator load of the steam turbine 120 is set to be equal to or higher than the output reduction rate of the boiler 110, and occurs during that period. The surplus heat energy to be generated is stored in the heat storage device 200. Further, during the shutdown period of the steam turbine 120, the surplus heat energy from the boiler 110 is stored in the heat storage device 200. Then, at startup, these excess heat energies stored in the heat storage device 200 may be recovered. As a result, the startup efficiency is increased.

By utilizing the heat storage device 200 in this way in the pumping operation mode, not only the heat energy can be efficiently used, but also the period required for stopping and the period required for starting can be shortened. As a result, it is possible to realize a smooth transition from the normal operation mode to the pumping operation mode and a smooth return from the pumping operation mode to the normal operation mode.

For example, by using the heat storage device 200 of the present embodiment for starting and stopping a steam power plant in DSS (Daily Start & Stop), it is possible to shorten the start and stop time. Further, by using the heat storage device 200 of the present embodiment, the fluctuation of the electric power supply amount derived from the regenerated energy can be leveled in total even when the steam power generation plant and the regenerated energy power generation plant are used in combination. As a result, the number of occurrences of a state in which the overall power supply exceeds the system requirement is reduced.

Further, according to the present embodiment, the heat storage energy stored in the heat storage device 200 can be utilized not only at the time of normal startup but also at the time of system return after FCB or at the time of rapid load increase of the power plant 100. As a result, the system return time and the load increase time can be shortened.

Note that the rapid load increase is, for example, a case where a load change that is faster than that at the start / load change / stop during normal operation is required. For example, when the system side requires a load increase higher than that of normal startup, such as when returning after the system becomes unstable. For example, in the case of a boiler 110, the rate of increase is 5% / min or more, and in the case of a gas turbine, the rate of increase is 10 to 20% / min or more.

Further, in the equipment constituting the power plant 100, when the load change rate exceeds the load change rate defined by the limit corresponding to the calorific value change of the equipment other than the steam turbine 120, or the load change in which the boiler 110 cannot meet the system requirements. It also includes cases where it is required.

Note that the connection of each heat recovery pipe (first heat recovery pipe 410, second heat recovery pipe 420, and third heat recovery pipe 430) is not limited to the above-mentioned pipes depending on the temperature range of each heat storage layer. For example, with respect to each boiler heat exchange section provided in the water supply line 130 and the boiler 110, a heat recovery pipe passing through a heat storage layer in a temperature range higher than and closest to the inlet side temperature of the boiler heat exchange section branches from the inlet side pipe and exits. The heat recovery pipe that has passed through the heat storage layer in the temperature range lower than and closest to the side temperature may be connected to the outlet side pipe.

For example, the boiler 110 has a first boiler heat exchange unit that generates a fluid having a temperature in the first temperature range by heat exchange, and a second temperature range that is lower than the first temperature range by heat exchange. A second boiler heat exchange section (or a high-pressure heater 136 of the water supply line 130) for generating fluid, and a first heat storage section (high temperature layer) in which the heat storage device 200 stores heat energy in the first temperature range. When a second heat storage section (heat exchange section in the middle temperature layer 220) for storing heat energy in the second temperature range is provided, the second heat recovery tube 420 is provided with a second boiler. After guiding a part of the fluid generated in the heat exchange section to the second heat storage section and recovering the heat energy in the second heat storage section, the first boiler heat exchange section or the first boiler heat exchange section or higher in the boiler 110 Lead to the boiler heat exchange section with the design temperature. Further, the first heat recovery tube 410 is a boiler having a design temperature higher than that of the boiler heat exchange section (for example, the first boiler heat exchange section or the first boiler heat exchange section) into which the fluid guided by the second heat recovery tube 420 flows. A part of the fluid generated in the heat exchange section) is guided to the first heat storage section, and after the heat energy is recovered in the first heat storage section, it is guided to the outlet side of the boiler heat exchange section.

<Modification 7>
[Modification example during heat recovery]
In the power plants 100 and 101 (hereinafter, represented by the power plant 100) of the above embodiment, the heat energy stored in the heat storage devices 200 to 206 (hereinafter, represented by the heat storage device 200) is stored in each heat storage layer. By supplying the heat exchanger of the boiler 110 corresponding to the temperature range of the heat storage layer, the energy supply when the load of the boiler 110 rises is efficiently supported.

However, the heat recovery method from the heat storage device 200 is not limited to this. For example, as shown in FIG. 27, the fluid may be passed through each layer in order from the low temperature layer 230, the entire heat energy stored in the heat storage device 200 may be recovered, and then returned to the system of the power plant 100.

The return destination of the fluid after the thermal energy is recovered is, for example, the main steam pipe 162. Further, the fluid to the heat storage device 200 is supplied from, for example, the water supply line 130. In this case, for example, a fourth heat recovery pipe 440 that connects the water supply line 130 and the main steam pipe 162 is provided, and the heat storage device 200 is arranged on the fourth heat recovery pipe 440.

By piping in this way, the water charged into the heat storage device 200 is heated in the order of the low temperature layer 230, the medium temperature layer 220, and the high temperature layer 210. As a result, high-temperature, high-pressure steam is generated only in the heat storage device 200, and it can be directly input to the high-pressure steam turbine 121.

In this modification, the return destination of the fluid after the heat energy is recovered by the heat storage device 200 may be the low temperature reheat steam pipe 163 during high load operation.

<< Fourth Embodiment >>
Next, a fourth embodiment of the present invention will be described. In the present embodiment, unlike the first to third embodiments, surplus electric power is stored in the heat storage device. Surplus electric power is generated when a power generation device using renewable energy (hereinafter referred to as renewable energy) such as wind power or solar power is incorporated into the power grid.

These regenerative energy power generations depend on natural phenomena such as the weather, and the amount of power generation fluctuates rapidly. When regenerative energy power generation is incorporated into the power grid of thermal power generation, fluctuations in the amount of power generation due to regenerative energy power generation are absorbed by adjusting the power generation amount of the thermal power generation plant in order to maintain the stability of the power system. Therefore, when the amount of power supplied by the regenerated energy power generation increases, a power supply command for suppressing the amount of power generation is issued to the thermal power plant. However, thermal power plants have a minimum operational load (eg, 30%). In a thermal power plant, even if the amount of power generation below the minimum load is instructed, the thermal power plant side cannot respond, and the amount of power generation may be surplus. In the present embodiment, this surplus electric power is stored.

There is a system that stores electrical energy as heat energy and releases it as needed. For example, Japanese Patent Application Laid-Open No. 2016-142272 (Reference 2) states that "an electric energy storage and release system for storing electric energy as heat energy includes a heat pump cycle including a first working fluid and a second working fluid. A steam cycle including, a first heat storage system including a first thermal fluid, a second heat storage system including a second thermal fluid, an electric heater, and a power regulator, which are fluidly connected to each other. The first heat storage system includes a first low-temperature heat storage tank and a high-temperature heat storage tank that are fluidly connected, and the second heat storage system includes a second low-temperature heat storage tank and a high-temperature heat storage tank that are fluidly connected. The electric heaters are operatively connected between the heat storage tanks. The power regulator adjusts to supply some of the excess electrical energy of the power supply to the electric heaters and heat pump cycle (summary excerpt). ) ”Technology is disclosed.

However, since the technology disclosed in Reference 2 does not assume regenerative energy power generation incorporated in the power grid, the boiler 110 can store surplus power in the power grid or use the stored heat energy when starting a power plant. There is no mention of using it when the load rises.

In the fourth embodiment of the present invention, the surplus electric power generated when the amount of electric power generated by the power supply command falls below the minimum load of the power plant 100 is stored in the heat storage device. Then, as in the other embodiments described above, the stored heat is recovered from the optimum temperature range at an appropriate timing during operation of the power plant and used.

The fluid system of the power plant 100 of the present embodiment basically has the same configuration as that of the first embodiment. However, as shown in FIG. 28, the heat storage device 207 of the present embodiment stores surplus electric power of the electric power generated by the regenerative energy power generation device 600 or the generator 109. Therefore, a feeder line is provided to supply the surplus electric power generated by the generator 109 or the regenerative energy power generation device 600 to the heat storage device 207. In this embodiment, the saturated water pipe 161, the boiler extraction pipe 165, the main steam bypass pipe 167, the boiler start extraction air adjustment valve 175, and the main steam bypass on-off valve 177 may not be provided.

[Heat storage device]
FIG. 29A shows an example of the heat storage device 207 of this embodiment. The heat storage device 207 of the present embodiment stores the surplus electric power from the power plant 100 and the regenerative energy power generation device 600 as surplus heat energy according to the instruction from the control device 150.

The heat storage device 207 includes a plurality of heat storage layers composed of heat storage materials having temperature characteristics (melting points) in different temperature ranges, and a heat exchange unit provided in each heat storage layer.

Hereinafter, in the present embodiment, as in the first embodiment, the heat storage device 207 uses the high temperature heat storage layer 210 (high temperature layer 210), the medium temperature heat storage layer 220 (medium temperature layer 220), and the low temperature heat storage layer 230 as heat storage layers. (Low temperature layer 230) and the case where the three heat storage layers are provided will be described as an example.

Similar to the first embodiment, the high temperature layer 210 is a heat storage layer composed of a heat storage material having a temperature characteristic (melting point) in a temperature range (first temperature range) centered at 500 ° C. The medium temperature layer 220 is a heat storage layer composed of a heat storage material having a temperature characteristic in a temperature range (second temperature range) centered on 400 ° C. Further, the low temperature layer 230 is a heat storage layer composed of a heat storage material having a temperature characteristic in a temperature range (third temperature range) centered on 300 ° C.

Further, as the heat exchange unit, the heat storage device 207 of the present embodiment uses an electric heater 510 that heats an object by passing an electric current through a resistor to generate heat, as shown in FIG. 29 (a). The electric heater 510 includes a high temperature layer electric heater 511 arranged in the high temperature layer 210, a medium temperature layer electric heater 521 arranged in the medium temperature layer 220, and a low temperature layer electric heater arranged in the low temperature layer 230. 531 and. It may be a device that heats an object by induction heating by passing an electric current through the coil. The electric heater 510 may be any device as long as it can heat an object using electric power.

The electric heater 511 for the high temperature layer, the electric heater 521 for the medium temperature layer, and the electric heater 531 for the low temperature layer use the surplus power supplied by the feeder lines 512, 522, and 532, respectively, to provide each heat storage layer (high temperature layer 210, The medium temperature layer 220 and the low temperature layer 230) are heated.

The heat storage material used for each heat storage layer is basically the same as that of the first embodiment. For example, a latent heat storage material that utilizes the phase transformation latent heat of a substance can be used. The temperature characteristic of the heat storage layer is a characteristic determined based on the melting temperature (melting point) of the latent heat storage material. Further, as the heat storage material used for each heat storage layer, an alloy-based material having a heat storage temperature (melting point) exceeding 500 ° C. may be used. Further, the structure may include the alloy-based material in ceramics or metal. For example, the latent heat storage microcapsules disclosed in International Publication No. 2017/200021 can be used.

Further, the heat storage material may be a molten salt in which the salt (solid) is in a molten state (liquid). The molten salt can store a very large amount of heat by heating it to a high temperature. As the molten salt, for example, a mixture of potassium nitrate and sodium nitrate can be used. However, it is not limited to this. It can be appropriately selected according to the required heat storage capacity, temperature, and the like.

As in the first embodiment, the heat storage device 207 is used as a flow path for heat recovery, and further, a flow path for connecting heat exchange units in the same heat storage layer (first heat recovery tube 410 and second heat recovery). A tube 420 and a third heat recovery tube 430) are provided inside the tube 420.

The first heat recovery tube 410, the second heat recovery tube 420, and the third heat recovery tube 430 have a first heat recovery on-off valve 411 and a second heat recovery on-off valve 421 on the inlet side of each heat storage layer, respectively. , A third heat recovery on-off valve 431 is provided. The opening and closing of these heat recovery on-off valves 411, 421 and 431 is controlled by the control device 150. The control device 150 controls the opening and closing of these heat recovery on-off valves 411, 421 and 431 so that heat can be recovered from the heat storage layer in the optimum temperature range during heat recovery.

[ON / OFF control of electric heater by control device]
In general, a power plant generates power in response to a power supply command received from a power supply command center that monitors the power system under its jurisdiction. The power supply command center sends a power supply command to each power plant and controls it so that the total power generation amount of all the power plants under its jurisdiction and the electricity usage amount (demand amount) are equal.

Hereinafter, it is assumed that photovoltaic power generation is used as the regenerative energy power generation and the demand for electricity is constant, and ON / OFF control of the electric heater 510 will be described with reference to FIGS. 30 (a) to 30 (c).

In photovoltaic power generation, as shown in FIG. 30 (b), the amount of power supplied greatly changes due to events such as sunrise and sunset. Here, the time TA is sunrise and the time TD is sunset. The amount of power supplied by photovoltaic power generation, which was initially 0, starts to increase from time TA and reaches the maximum value. Then, after maintaining the maximum value for a predetermined period, it starts to decrease and becomes the minimum (0) at the time TD.

In response to such changes in the amount of power supplied by photovoltaic power generation, a power supply command is issued to the thermal power plant so that the amount of power supplied from the power grid matches the amount of demand. The temporal change in the amount of power generation due to the power supply command is shown by a dotted line in FIG. 30 (a). A power supply command is issued to the power plant 100 to reduce the amount of power generated until the amount of power supplied by photovoltaic power generation is maximized. After that, the amount of power generated by solar power generation begins to decrease, and a power supply command is issued to increase the amount of power generation.

FIG. 30A shows the turbine generator load of the power plant 100 that changes in response to this power supply command. In the power plant 100, when the load of the boiler corresponding to the amount of power generated by the power supply command reaches the minimum load, the load of the turbine generator cannot be reduced any more. Therefore, surplus power is generated at this timing.

As shown in FIG. 30C, the control device 150 monitors the power supply command and the load of the boiler generator corresponding to the power supply command, and when the power supply command falls below the minimum load of the boiler generator, the electric heater 510 is turned on. Outputs an ON command. Further, when the power supply command exceeds the minimum load of the boiler generator, an OFF command is output to the electric heater 510.

That is, at time TA (for example, sunrise), as the amount of power supplied from the regenerated energy power generation increases, the suppression of the power supply command of the thermal power begins to receive the regenerated energy. Then, at time TB, the power supply command falls below the minimum load. However, in the thermal power generation plant 100, the minimum load is predetermined for each plant. Therefore, even if a power supply command below this minimum load is received, the load cannot be further reduced. That is, since the power plant 100 continues to operate at the minimum load, the amount of power supplied by the operation at the minimum load exceeds the amount of power supplied by the power supply command in the power grid, and surplus power is generated.

At this point (time TB), the electric heater 510 is turned on in order to store the surplus electric power in the heat storage device 207. After that, when the power supply amount of the regenerated energy starts to decrease and no surplus power is generated, in other words, when the power supply command to the thermal power generation plant 100 reaches the minimum load (time TC), the electric heater 510 is turned off. Will be done.

The control device 150 compares the received power supply command with the minimum load of the power plant 100 each time the power supply command is received, and when the power supply amount according to the power supply command falls below the minimum load, the electric heater 510 is turned on. Output the command. On the other hand, when the amount of power supplied by the power supply command exceeds the minimum load, an OFF command is output to the electric heater 510.

When the ON command is received, the heat storage by the electric heater 510 is started, and when the OFF command is received, the heat storage by the electric heater 510 is stopped.

In the present embodiment, the high temperature layer electric heater 511, the medium temperature layer electric heater 521, and the low temperature layer electric heater 531 heat the high temperature layer 210, the medium temperature layer 220, and the low temperature layer 230, respectively. Therefore, the control device 150 may also monitor the temperature of each heat storage layer and control the heater 510 to be turned off when the melting point of the heat storage layer is reached. For example, when the low temperature layer 230 reaches 300 ° C., the low temperature layer electric heater 531 is turned off, and when the middle temperature layer 220 reaches 400 ° C., the middle temperature layer electric heater 521 is turned off.

[Heat recovery]
The connection at the time of heat recovery is shown in FIG. 31 (a). Since the connection of each heat recovery tube is the same as that of the first embodiment, the description thereof is omitted here. The same applies to the opening / closing control of the heat recovery on-off valve.

As described above, the power plant 100 of the present embodiment is rotationally driven by the boiler 110 that heats the supplied water to generate superheated steam and the superheated steam heated by the boiler 110 to drive the generator 109. The steam turbine 120, the heat storage device 207 that recovers and stores the surplus energy that passes through the inside, and the control device 150 that controls the surplus energy generated during operation including the start and stop to be stored in the heat storage device 207. And.

The surplus energy includes surplus power energy, which is surplus power energy, and the heat storage device 207 is provided inside a plurality of heat storage units (high temperature layer 210, medium temperature layer) each having temperature characteristics in different temperature ranges. 220, the low temperature layer 230) is provided with an electric heater 510 heated by surplus electric energy, and when the control device 150 receives a power supply command below a predetermined load (for example, the minimum load) of the power plant 100, electricity is supplied. Operate the heater 510.

As described above, in the present embodiment, surplus electric power energy is stored. When excess heat (steam) is stored as surplus energy, the heat storage layer that supplies the surplus heat may be limited because the temperature higher than the steam cannot be stored in the heat storage material. However, when the surplus power is stored as surplus energy, the heat is stored by supplying the power to the electric heater 510, and the temperature can be raised without limit as long as the surplus power energy is available. Therefore, the heat storage layer to be installed / stored. Can be selected arbitrarily. Therefore, according to the present embodiment, the surplus electric power energy generated in the power plant 100 can be stored in a mode in which it can be used efficiently.

Further, according to the heat storage device 207 of the present embodiment, it is possible to independently and independently recover a plurality of heat energies having different temperatures according to the melting point in each heat storage layer at the time of heat recovery. Then, the recovered thermal energy of different temperatures can be provided to the usage destination according to the required temperature. That is, according to the heat storage device 207 of the present embodiment, it is possible to realize the proper use of heat according to the application.

Further, in the power plant 100 provided with the heat storage device 207 of the present embodiment, the surplus heat energy is independently stored in the heat storage device 207 for each temperature zone. Therefore, when the heat is recovered from the heat storage device 200, the surplus heat energy can be efficiently used by recovering the heat from the heat storage layer in which the heat energy corresponding to the temperature required by the boiler heat exchange unit to be used is stored.

<Modification 8>
In the above embodiment, the heat storage device 207 includes a plurality of heat storage layers composed of heat storage materials having temperature characteristics in different temperature ranges, and stores heat only up to the temperature range. However, the heat storage in the heat storage device 207 is not limited to this.

For example, as in the heat storage device 207a shown in FIG. 29B, all of them may be configured to be capable of storing heat up to the same temperature and may be configured to store heat up to that temperature. Here, as an example, a case where heat is stored in all the heat storage layers to a temperature corresponding to the high temperature layer 210 of the above embodiment will be illustrated.

FIG. 31 (b) shows the connection at the time of heat recovery when the heat storage device 207a is used. In this modification, the inlet side of each heat recovery pipe (first heat recovery pipe 410, second heat recovery pipe 420, and third heat recovery pipe 430) is connected to the inlet side pipe of the primary superheater 114a. .. A heat recovery on-off valve 411 is provided between the primary superheater 114a and each heat recovery pipe. Further, the outlet side is branched into two and is connected to the outlet side pipe of the primary superheater 114a and the outlet side pipe of the secondary superheater 114b, respectively. The first heat recovery pipe 410 after branching is provided with heat recovery on-off valves 413 and 414, respectively. The control of each heat recovery on-off valve is the same as that of the third embodiment.

In the case of this modification, since heat is stored in all the heat storage layers up to the temperature corresponding to the high temperature layer 210, the temperature of each heat storage layer is monitored and the electric heater of each heat storage layer is turned off as in the above embodiment. There is no need.

According to this modification, surplus power energy can be efficiently stored as heat energy with a simple configuration.

In this modified example, the number of heat storage layers of the heat storage device 207 does not matter. For example, it may be a single layer as in the heat storage device 207b shown in FIG. 32.

<< Fifth Embodiment >>
Next, a fifth embodiment of the present invention will be described. In the present embodiment, the surplus electric power energy and the surplus heat energy are stored in the heat storage device as surplus energy.

The surplus thermal energy is the steam generated by the boiler 110 generated when the power plant 100 is started or stopped, and is not used in the steam turbine 120, as in the first embodiment. Further, the surplus power energy is the power generated when the power supply command value falls below the minimum load of the power plant 100, as in the fourth embodiment.

The fluid system diagram of the power plant 100 of this embodiment is shown in FIG. 33. The fluid system of the present embodiment basically has the same configuration as that of the first embodiment. Further, in the present embodiment, since the surplus electric power energy is also stored in the heat storage device 208, a power supply line for supplying the surplus electric power energy generated by the power generation by the generator 109 or the regenerative energy power generation device 600 to the heat storage device 208 is provided. ..

[Heat storage device]
FIG. 34 shows an example of the heat storage device 208 of the present embodiment. An example of the heat storage device 208 of this embodiment is shown. Similar to the first embodiment, the heat storage device 208 of the present embodiment stores the surplus power energy of the power plant 100 and the regenerative energy power generation device 600 as surplus heat energy according to the instruction from the control device 150.

The heat storage device 208 of the present embodiment has the same configuration as the heat storage device 200 of the first embodiment shown in FIG. Further, the heat storage device 208 of the present embodiment includes the electric heater 510 described in the fourth embodiment as a heat exchange unit. Similar to the fourth embodiment, the electric heater 510 is arranged in the high temperature layer electric heater 511 arranged in the high temperature layer 210, the medium temperature layer electric heater 521 arranged in the medium temperature layer 220, and the low temperature layer 230. It has an electric heater 531 for a low temperature layer. Further, the electric heater 511 for the high temperature layer, the electric heater 521 for the middle temperature layer, and the feeding lines 512, 522, and 532 for supplying surplus power to the electric heater 531 for the low temperature layer are provided.

The heat storage material used for each heat storage layer is the same as that of the fourth embodiment.

Further, the control of the on-off valve and the ON / OFF control of the electric heater 510 by the control device 150 of the present embodiment are performed independently, respectively, and are the same as those of the first embodiment and the fourth embodiment. Also in the present embodiment, the control device 150 may monitor the temperature of each heat storage layer and control the heater 510 to be turned off when the melting point of the heat storage layer is reached.

[Heat recovery]
The connection at the time of heat recovery of this embodiment is shown in FIG. Heat recovery depends on the temperature characteristics of the heat storage layer. Therefore, since the connection of each heat recovery tube is the same as that of the first embodiment, the description thereof is omitted here. The same applies to the opening / closing control of the heat recovery on-off valve.

As described above, the power plant 100 of the present embodiment is rotationally driven by the boiler 110 that heats the supplied water to generate superheated steam and the superheated steam heated by the boiler 110 to drive the generator 109. The steam turbine 120, the heat storage device 208 that recovers and stores the surplus energy that passes through the inside, and the control device 150 that controls the surplus energy generated during operation including the start and stop to be stored in the heat storage device 208. And.

Then, the surplus energy includes the surplus heat energy which is the surplus heat energy of the superheated steam generated by the boiler 110, and the heat storage device 208 recovers heat from the fluid passing through the flow path provided inside. A plurality of heat storage units (high temperature layer 210, medium temperature layer 220, low temperature layer 230) each having temperature characteristics in different temperature ranges and operating according to instructions from the control device 150, inflow of fluid into the flow path. The control device 150 includes an on-off valve for controlling the temperature of the surplus heat energy generated at at least one of the start-up time and the stop-time state, and has a temperature characteristic in a temperature range to which the temperature of the surplus heat energy belongs in a fluid manner. The opening and closing of the on-off valve is controlled so that it flows into the flow path that first passes through the heat storage unit. Further, the surplus energy further includes surplus power energy, which is surplus power energy, each heat storage unit includes an electric heater 510 heated by the surplus power energy, and the control device 150 is predetermined for the power plant 100. When a power supply command below the applied load (for example, the minimum load) is received, the electric heater 510 is operated.

Therefore, according to the present embodiment, the surplus heat energy and the surplus power energy generated in the power plant 100 can be stored in a mode in which they can be used efficiently. That is, the same effects as those of the first embodiment and the fourth embodiment can be obtained.

Here, as a configuration for storing excess heat energy, the heat storage device 200 of the first embodiment has been described as an example, but the present invention is not limited to this. For example, the heat storage device 201 of the second embodiment or the heat storage devices 200, 201, 202, 203, 204, 205 of other modifications may be used.

<Modification 9>
Further, as in the fourth embodiment, as in the heat storage device 208a shown in FIG. 36, all the heat storage devices may be configured to be capable of storing heat up to the same temperature and may be configured to store heat up to that temperature. Here, as an example, a case where heat is stored in all the heat storage layers to a temperature corresponding to the high temperature layer 210 of the above embodiment will be illustrated.

On the other hand, since heat is stored in all the heat storage layers up to the temperature corresponding to the high temperature layer 210, it is not necessary for the control device 150 to monitor the temperature of each heat storage layer and perform OFF control of the electric heater 510 in this modification. ..

[Heat recovery]
The connection at the time of heat recovery when the heat storage device 208a is used is shown in FIG. 37 (a). As described above, the control of the piping and the heat recovery on-off valve during heat recovery depends on the temperature characteristics of the heat storage layer. Therefore, in this case, it is the same as FIG. 31 (b) of the fourth embodiment.

According to this modification, surplus power energy and surplus heat energy can be efficiently stored as heat energy with a simple configuration.

When storing excess heat energy, heat storage material that matches the temperature of the steam is placed in each layer, and heat is stored / dissipated in the phase change region (latent heat region, constant temperature). When the surplus electric energy is stored in the electric heater 510, the heat storage material can be heated up to the upper limit temperature of the electric heater 510, so that the heat can be stored up to a temperature higher than the phase change region. In this case, heat is stored in the sensible heat region.

<Modification example 10>
In the above modification, the case where heat is stored in all the heat storage layers up to the temperature corresponding to the high temperature layer 210 is illustrated, but the heat storage temperature in each heat storage layer is not limited to this. The combination of heat storage temperatures is arbitrary. Furthermore, the number of heat storage layers does not matter.

For example, heat may be stored in the upper two layers to a temperature corresponding to the high temperature layer 210, and in the lowermost layer to a temperature corresponding to the medium temperature layer 220. Further, heat may be stored in the uppermost layer to a temperature corresponding to the high temperature layer, and in the lower two layers to a temperature corresponding to the medium temperature layer 220. In this case, in heat dissipation (heat recovery), the first heat recovery tube 410 is also connected to the medium temperature layer 220 and the low temperature layer 230, and the second heat recovery tube 420 is also connected to the low temperature layer 230, and each line is connected. A valve is provided in. By opening and closing these valves, heat can be dissipated according to the situation during heat storage.

Further, the heat storage device 200 for storing the surplus heat energy and the heat storage device 207 for storing the surplus electric power energy may be separately provided as shown in FIG. 38. In this case, the heat storage device 207 that stores the surplus electric power energy can freely set the arrangement position. In particular, the heat storage device 207 for storing surplus electric power energy may be arranged at an arbitrary position for each heat storage layer. Further, the heat storage device 208 for storing the surplus electric power energy and the surplus heat energy can also be arranged in an appropriate combination with at least one of the heat storage devices 200 and 207. The heat storage device 200 may be the heat storage device 201 of the second embodiment or the heat storage devices 200, 201, 202, 203, 204, 205 of other modifications as described above. Further, the heat storage device 207 may be the heat storage devices 207a and 207b. Further, the heat storage device 208 may be the heat storage device 208a. Further, the number of heat storage layers of each heat storage device does not matter.

The present invention is not limited to the above embodiments and modifications, and various modifications can be made according to the design and the like as long as the technical idea of the present invention is not deviated. For example, it is not always necessary to provide all the flow paths and feed lines used for heat storage in the heat storage devices 200 to 208a and the flow paths used for heat recovery.

100: Power plant, 101: Power plant, 109: Generator,
110: Boiler, 111: Economizer, 112: Fireplace water cooling wall, 113: Brackish water separator, 114: Superheater, 114a: Primary superheater, 114b: Secondary superheater, 115: Reheater,
120: Steam turbine, 121: High pressure steam turbine, 122: Medium pressure steam turbine, 123: Low pressure steam turbine,
130: Water supply line, 131: Condensate, 132: Condensate pump, 133: Low pressure heater, 134: Deaerator, 135: Water supply pump, 136: High pressure heater,
150: Control device, 151: Control console,
161: Saturated water pipe, 162: Main steam pipe, 163: Low temperature reheat steam pipe, 164: High temperature reheat steam pipe, 165: Boiler bleed pipe, 166: Turbine exhaust pipe, 167: Main steam bypass pipe, 168: Reheat Steam bypass pipe 169: High pressure steam turbine bypass pipe,
172: Main steam on-off valve, 174: Reheat steam on-off valve, 175: Boiler start bleeding adjustment valve, 177: Main steam bypass on-off valve, 178: Reheat steam bypass on-off valve, 179: High-pressure steam turbine bypass on-off valve,
181: Temperature sensor, 185: Temperature sensor, 187: Temperature sensor, 188: Temperature sensor,
200: Heat storage device, 201: Heat storage device, 202: Heat storage device, 203: Heat storage device, 204: Heat storage device, 205: Heat storage device, 206: Heat storage device,
207: Heat storage device, 207a: Heat storage device, 207b: Heat storage device, 208: Heat storage device, 208a: Heat storage device,
210: High-temperature heat storage layer (high-temperature layer), 211: High-temperature heat exchange unit, 214: Reheat high-temperature heat exchange unit,
220: Medium heat storage layer (medium temperature layer), 221: 1st medium heat exchange unit, 221b: 1st parallel medium heat exchange unit 222: 2nd medium heat exchange unit, 224: Reheat medium heat exchange unit,
230: Low temperature heat storage layer (low temperature layer), 231: First low temperature heat exchange unit, 231b: First parallel low temperature heat exchange unit, 231c: Second parallel low temperature heat exchange unit, 232: Second low temperature heat exchange unit, 232b: Third parallel low temperature heat exchange unit, 233: Third low temperature heat exchange unit, 234: Reheat low temperature heat exchange unit,
301: branch point, 302: confluence, 303: branch point, 304: confluence, 305: branch point, 306: confluence, 307: branch point, 308: confluence,
311: Saturated water flow path, 312: Saturated water bypass flow path, 316: Saturated water first on-off valve, 317: Saturated water third on-off valve,
351: Boiler exhaust flow path, 352: Boiler exhaust bypass flow path, 353: Boiler exhaust third flow path, 354: Boiler exhaust fourth flow path, 356: Exhaust first on-off valve, 357: Exhaust second on-off valve, 359 : Exhaust fourth on-off valve,
371: Main steam first flow path, 372: Main steam bypass flow path, 373: Main steam third flow path, 374: Main steam fourth flow path, 376: Main steam first on-off valve, 377: Main steam second on-off valve Valve, 378: Main steam third on-off valve, 379: Main steam fourth on-off valve,
381: Reheat steam first flow path, 382: Reheat steam bypass flow path, 383: Reheat steam third flow path, 386: Reheat steam first on-off valve, 387: Reheat steam second on-off valve, 388: Reheat steam third on-off valve,
410: First heat recovery tube, 411: First heat recovery on-off valve, 413: Heat recovery on-off valve, 414: Heat recovery on-off valve, 420: Second heat recovery tube, 421: Second heat recovery on-off valve, 423: Heat recovery switch valve, 424: Heat recovery switch valve, 430: Third heat recovery tube, 431: Third heat recovery switch valve, 433: Heat recovery switch valve, 434: Heat recovery switch valve, 440: Fourth heat recovery tube 510: Electric heater, 511: Electric heater for high temperature layer, 512: Power supply line, 521: Electric heater for medium temperature layer, 522: Power supply line, 531: Electric heater for low temperature layer, 532: Power supply line, 600: Regenerated energy power generation device

Claims (22)

1. A boiler that heats the supplied water to generate superheated steam,
   A steam turbine that is rotationally driven by superheated steam overheated in the boiler to drive a generator, and
   A heat storage device that recovers and stores excess energy that passes through the interior,
   A control device that controls the excess energy generated during operation including start-up and stop so that the heat storage device stores heat.
   A power plant characterized by being equipped with.
2. The power plant according to claim 1.
   The surplus energy is surplus heat energy, which is the surplus heat energy of the superheated steam generated by the boiler.
   The heat storage device is
   A plurality of heat storage units, each of which has temperature characteristics in different temperature ranges, recovers heat from a fluid passing through an internal flow path and stores heat.
   It is provided with an on-off valve that operates according to an instruction from the control device and controls the inflow of the fluid into the flow path.
   The control device first uses the heat storage unit in which the excess heat energy generated at at least one of the start-up time and the stop time has a temperature characteristic in the temperature range to which the temperature of the surplus heat energy belongs in the form of a fluid. A power plant characterized in that the opening and closing of the on-off valve is controlled so as to flow into the passing flow path.
3. The power plant according to claim 2.
   A water supply line that returns the exhaust steam from the steam turbine to water and supplies it to the boiler.
   A main steam bypass pipe that branches from the main steam pipe that supplies the superheated steam from the boiler to the steam turbine and discharges the superheated steam to the water supply line is further provided.
   The heat storage unit
   The first heat storage unit, which has temperature characteristics in the first temperature range,
   A second heat storage unit having temperature characteristics in a second temperature range, which is a temperature range lower than the first temperature range, is provided.
   The flow path is
   The main steam first, which is connected to the main steam bypass pipe and allows the fluid flowing into the heat storage device to pass through the first heat storage section and the second heat storage section in this order and is discharged from the heat storage device to the main steam bypass pipe. With one flow path,
   The control device is operated from the start of ventilation until the load of the boiler matches the generator load of the steam turbine, and in a state where the generator load of the steam turbine is a predetermined amount smaller than the minimum load of the boiler. A power generation plant characterized in that the opening and closing of the on-off valve is controlled so that the fluid flows into the main steam first flow path in at least one of them.
4. The power plant according to claim 3.
   Further provided with a boiler bleeding pipe that branches from the piping in the boiler provided in the boiler and discharges the superheated steam in the boiler to the water supply line.
   The flow path is
   The main fluid connected to the main steam bypass pipe and flowing into the heat storage device bypasses the first heat storage unit, passes through the second heat storage unit, and is discharged from the heat storage device to the main steam bypass pipe. Steam third flow path and
   Further provided is a boiler exhaust flow path which is connected to the boiler bleeding pipe and allows the fluid flowing into the heat storage device to pass through the second heat storage unit and be discharged to the boiler bleeding pipe.
   In the control device, the fluid flows into the main steam third flow path and the boiler exhaust flow path from the ignition of the boiler to the start of ventilation, and the fluid does not flow into the main steam first flow path. A power plant characterized by controlling the opening and closing of the on-off valve.
5. The power plant according to claim 3 or 4.
   The control device controls the opening and closing of the on-off valve so that the fluid flows into the main steam first flow path when the generator load of the steam turbine is less than the load of the boiler when the power plant is stopped. A power plant featuring.
6. The power plant according to claim 3.
   The steam turbine includes a high-pressure steam turbine and a medium-low pressure steam turbine.
   The boiler includes a reheater that reheats the steam after rotationally driving the high-pressure steam turbine.
   The main steam pipe supplies the superheated steam to the high-pressure steam turbine.
   The power plant
   A low-temperature reheat steam pipe that supplies steam after rotational drive to the reheater,
   A high-temperature reheat steam pipe that supplies steam after reheating with the reheater to the medium-low pressure steam turbine, and
   A high-pressure steam turbine bypass pipe that branches from the main steam pipe and supplies the superheated steam to the low-temperature reheated steam pipe by bypassing the high-pressure steam turbine.
   A reheat steam bypass pipe that branches from the high temperature reheat steam pipe and discharges the steam in the high temperature reheat steam pipe to the water supply line is further provided.
   The flow path is
   The fluid connected to the reheat steam bypass pipe and flowing into the heat storage device is passed through the first heat storage unit and the second heat storage unit in this order, and is discharged from the heat storage device to the reheat steam bypass pipe. Hot steam first flow path and
   The fluid connected to the reheat steam bypass pipe and flowing into the heat storage device bypasses the first heat storage unit, passes through the second heat storage unit, and is discharged from the heat storage device to the reheat steam bypass pipe. Further equipped with a third flow path of reheated steam
   The control device is operated from the start of ventilation until the load of the boiler matches the generator load of the steam turbine, and in a state where the generator load of the steam turbine is a predetermined amount smaller than the minimum load of the boiler. A power generation plant characterized in that the opening and closing of the on-off valve is controlled so that the fluid flows into the first flow path of the reheated steam in at least one of them.
7. The power plant according to claim 6.
   In the control device, the on-off valve prevents the fluid from flowing into the reheated steam third flow path and the fluid from flowing into the reheated steam first flow path from the ignition of the boiler to the start of ventilation. A power plant characterized by controlling the opening and closing of.
8. The power plant according to claim 6 or 7.
   When the generator load of the steam turbine is less than the load of the boiler when the power generation plant is stopped, the control device causes the fluid to flow into the main steam first flow path and the reheat steam first flow path. A power plant characterized by controlling the opening and closing of on-off valves.
9. The power plant according to claim 3.
   The heat storage unit further includes a third heat storage unit having temperature characteristics in a third temperature range, which is a temperature range lower than the second temperature range.
   The control device is a power plant that controls the opening and closing of the on-off valve so that the fluid that has passed through the second heat storage unit is discharged from the heat storage device by passing through the third heat storage unit.
10. The power plant according to claim 9.
    A saturated water pipe for discharging the saturated water generated by the brackish water separator provided in the boiler to the water supply line is further provided.
    The flow path is
    A power generation plant further provided with a saturated water flow path which is connected to the saturated water pipe and allows the saturated water flowing into the heat storage device to pass through the third heat storage unit and be discharged to the saturated water pipe.
11. The power plant according to claim 3.
    Further provided with a temperature sensor for detecting the temperature of the superheated steam in the main steam pipe,
    The control device is a power plant characterized in that an event for controlling the opening and closing of the on-off valve is specified by the output of the temperature sensor.
12. The power plant according to claim 11.
    A power plant characterized in that the first temperature range and the second temperature range are each determined in association with the temperature at the time of the event to be specified.
13. The power plant according to claim 11.
    A power plant characterized in that the capacities of each of the first heat storage unit and the second heat storage unit are determined according to the thermal energy generated during the event.
14. A boiler that heats the supplied water to generate superheated steam,
    A steam turbine that is rotationally driven by superheated steam overheated in the boiler to drive a generator, and
    Equipped with a heat storage device that stores heat energy
    The boiler
    The first boiler heat exchange section that generates a fluid with a temperature in the first temperature range by heat exchange,
    A second boiler heat exchange unit that generates a fluid having a temperature in a second temperature range, which is a temperature range lower than the first temperature range, by heat exchange is provided.
    The heat storage device is
    The first heat storage unit that stores heat energy in the first temperature range,
    A second heat storage unit that stores heat energy in the second temperature range,
    A part of the fluid generated in the second boiler heat exchange section is guided to the second heat storage section, the heat energy is recovered by the second heat storage section, and then the second heat is led to the first boiler heat exchange section. With the recovery pipe
    A part of the fluid generated in the first boiler heat exchange section is guided to the first heat storage section, the heat energy is recovered by the first heat storage section, and then guided to the outlet side of the first boiler heat exchange section. A power plant characterized by having a first heat recovery pipe.
15. The power plant according to claim 14.
    With more control devices
    The heat storage device is
    Further provided with a heat recovery on-off valve that operates according to an instruction from the control device and controls the inflow of the fluid into each of the first heat recovery pipe and the second heat recovery pipe.
    The control device is
    The fluid flows into the first heat recovery pipe and the second heat recovery pipe at the time of starting the power plant, suppressing the heat output of the boiler, and at least one event at the time of promoting the drive of the steam turbine. A power plant characterized by controlling the opening and closing of the heat recovery on-off valve.
16. The power plant according to claim 1 or 2.
    The surplus energy includes surplus power energy which is surplus power energy.
    The heat storage device includes a heater provided in the heat storage unit, which is heated by the surplus electric power energy.
    The control device is a power plant, characterized in that the heater is operated when a power supply command lower than a predetermined load of the power plant is received.
17. The power plant according to claim 16.
    The heat storage device includes a plurality of the heat storage units.
    Each heat storage unit is a power plant characterized by having temperature characteristics in different temperature ranges.
18. A boiler that heats the supplied water to generate superheated steam,
    A steam turbine that is rotationally driven by superheated steam overheated in the boiler to drive a generator, and
    Equipped with a heat storage device that stores excess energy
    The boiler includes a first boiler heat exchange unit that generates a fluid having a temperature in the first temperature range by heat exchange.
    The heat storage device includes a first heat storage unit that stores heat energy in the first temperature range.
    A part of the fluid generated in the first boiler heat exchange section is guided to the first heat storage section, the heat energy is recovered by the first heat storage section, and then guided to the outlet side of the first boiler heat exchange section. A power plant characterized by having a first heat recovery pipe.
19. The power plant according to claim 18.
    The boiler further includes a second boiler heat exchange unit that generates a fluid having a temperature in a second temperature range, which is a temperature range lower than the first temperature range, by heat exchange.
    The heat storage device is
    A second heat storage unit that stores heat energy in the second temperature range,
    A part of the fluid generated in the second boiler heat exchange section is guided to the second heat storage section, the heat energy is recovered by the second heat storage section, and then the second heat is led to the first boiler heat exchange section. A power plant characterized by further equipped with a recovery pipe.
20. A boiler that heats the supplied water to generate superheated steam,
    A steam turbine that is rotationally driven by superheated steam overheated in the boiler to drive a generator, and
    A method for storing excess energy in a power plant equipped with a heat storage device that recovers and stores excess energy that passes through the inside.
    A method for storing surplus energy in a power plant, characterized in that when the surplus energy is generated during operation including start-up and stop, the surplus energy is controlled to be stored in the heat storage device.
21. The method for storing excess energy in the power plant according to claim 20.
    The surplus energy is surplus heat energy, which is the surplus heat energy of the superheated steam generated by the boiler.
    The heat storage device is
    A plurality of heat storage units, each of which has temperature characteristics in different temperature ranges, recovers heat from a fluid passing through an internal flow path and stores heat.
    It is provided with an on-off valve that operates according to an instruction from the control device and controls the inflow of the fluid into the flow path.
    The surplus thermal energy generated at at least one of the start and stop of the power plant first passes through the heat storage unit having a temperature characteristic in the temperature range to which the temperature of the surplus thermal energy belongs in the form of a fluid. A method for storing excess energy in a power plant, which controls the opening and closing of the on-off valve so as to flow into the flow path.
22. A method for storing excess energy in a power plant according to claim 20 or 21.
    The surplus energy includes surplus power energy which is surplus power energy.
    The heat storage device includes a heater provided in the heat storage unit, which is heated by the surplus electric power energy.
    A method for storing excess energy in a power plant, which comprises controlling the heater so as to operate the heater when a power supply command lower than a predetermined load of the power plant is received.
    

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