WO2020158941A1 - Heat storage device, power generation plant, and operation control method during fast cut back - Google Patents

Abstract

Provided is technology to efficiently store and use, in a plurality of different temperature ranges, excess energy generated at a power generation plant. A heat storage device 140 that has a plurality of heat storage units to recover and accumulate heat from a fluid passing through a channel provided therein is characterized by comprising a first heat storage unit that has temperature characteristics in a first temperature range, a second heat storage unit that has temperature characteristics in a second temperature range, which is a lower temperature range than the first temperature range, a first channel 241 that causes inflowing fluid to pass through the first heat storage unit and the second heat storage unit in order, a second channel 242 that causes the inflowing fluid to bypass the first heat storage unit and pass through the second heat storage unit, a first on-off valve 251 that is provided on the first channel 241, and a second on-off valve 252 that is provided on the second channel 242, wherein the first on-off valve 251 is in an open state if the fluid temperature is at a first temperature threshold or higher and the second on-off valve 252 is in an open state if the fluid temperature is less than the first temperature threshold.

Description

Heat storage device, power generation plant, and operation control method during fast cutback

The present invention relates to a steam power generation plant that uses combustion heat of various fuels, and in particular, a part of heat of steam is stored (heat storage) as heat energy, and the stored heat energy (heat storage) is stored in a power generation plant as needed. Regarding supply technology.

Patent Document 1 discloses a solar power generation system in which a plurality of heat storage tanks are connected in parallel to store and radiate heat.

There is also a technology that stores heat energy in a heat storage device that has two heat storage units that have different temperature ranges of temperature characteristics and that is used during operation of a power plant. For example, Patent Literature 2 discloses a solar thermal power generation plant having a heat storage unit in which a high-temperature heat storage device and a low-temperature heat storage device each having a different heat storage medium are connected in series. In the system disclosed in Patent Document 2, part of the superheated steam is stored in the high temperature heat storage device and the low temperature heat storage device in this order in the heat storage operation mode. On the other hand, in the heat radiation operation mode, the water supplied from the water supply pump flows in the order of the low-temperature heat storage device and the high-temperature heat storage device to recover the heat stored in each heat storage device, and superheated steam is generated to the steam turbine. Supplied.

JP, 2017-155667, A International Publication No. 2014/014027

According to the technique disclosed in Patent Document 1, when storing heat, saturated steam is sequentially supplied from the solar thermal power generation system to each heat storage tank one by one. Specifically, the temperature of each heat storage tank is monitored, and when the saturation temperature of the heat medium is reached, the heat storage tank is switched. Similarly, at the time of heat radiation, water is sequentially supplied to each heat storage tank one by one to generate a gas-liquid two-phase fluid containing saturated steam by heat exchange and supply it to the solar thermal power generation system. However, in the heat storage layer, sensible heat storage is performed by a solid heat storage material such as concrete, so that the temperature of the heat storage material also decreases with heat dissipation, making it difficult to control the temperature of the gas-liquid two-phase fluid.

According to the technique disclosed in Patent Document 2, although two types of heat storage devices of high temperature and low temperature are provided, since the high temperature heat storage device is sensible heat storage by molten salt, the stored heat is stored as in Patent Document 1. When used, the output temperature of the steam also decreases with the temperature decrease due to the radiation of the molten salt. In addition, since two types of heat storage devices, high temperature and low temperature, are connected in series, when the temperature of the inflowing steam decreases, the steam conversely absorbs heat from the high temperature heat storage device and cannot efficiently store heat.

Latent heat storage uses latent heat of phase transformation of a substance, and is characterized in that it can store and supply heat at a constant temperature according to the melting point of the heat storage material. However, in general, in a power plant, water and steam in different temperature ranges flow for each component device, and thus the technique disclosed in Patent Document 2 uses only a heat storage material having temperature characteristics in one temperature range. Therefore, water and steam in different temperature ranges cannot be supplied to each device of the power plant. Further, since only one type of latent heat storage material is used, the amount of heat storage is determined by the temperature characteristics of the latent heat storage material, and heat cannot be stored efficiently.

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

The present invention is a heat storage device having a plurality of heat storage units for recovering and accumulating heat from a fluid passing through a channel provided inside, wherein the heat storage unit has a temperature characteristic in a first temperature range. One heat storage part, and a second heat storage part having a temperature characteristic in a second temperature range that is a lower temperature range than the first temperature range, the flow path, the fluid flowing into the heat storage device, A first heat storage part, a first flow path that passes through the second heat storage part in this order and is discharged from the heat storage device, and a first branch part upstream of the first heat storage part of the first flow path branches to the heat storage device. A second flow path for flowing the fluid into the heat storage device by bypassing the first heat storage section and passing through the second heat storage section, and opening/closing for controlling the inflow of the fluid into the flow path. A valve, the opening/closing valve is provided on the first flow path, and is provided on the second flow path, and a first opening/closing valve that controls the inflow of the fluid to the first heat storage unit, A second on-off valve that controls the inflow of the fluid into the second heat storage unit, wherein the first on-off valve has a temperature of the fluid that is equal to or higher than a first temperature threshold value determined by the first temperature range. The second opening/closing valve is opened when the temperature of the fluid is lower than the first temperature threshold.

Further, the present invention is a heat storage device having a plurality of heat storage units for recovering and accumulating heat from a fluid passing through a flow path provided inside, wherein the heat storage unit has a temperature characteristic in a first temperature range. A first heat storage unit having, and a second heat storage unit having a temperature characteristic in a second temperature range that is a temperature range lower than the first temperature range, the flow path, the fluid flowing into the heat storage device. , A first flow path that passes through the first heat storage section and is discharged from the heat storage apparatus, and a fluid that branches at a first branch section upstream of the first heat storage section of the first flow path and flows into the heat storage apparatus A second flow path that passes through the second heat storage section and is discharged from the heat storage device, and an on-off valve that controls the inflow of the fluid into the flow path, wherein the on-off valve is the first flow path. A first opening/closing valve provided on the road for controlling the inflow of the fluid to the first heat storage unit, and a second on the second flow passage for controlling the inflow of the fluid to the second heat storage unit. An opening/closing valve, wherein the first opening/closing valve is in an open state when the temperature of the fluid is equal to or higher than a first temperature threshold value determined by the first temperature range, and the second opening/closing valve is the fluid When the temperature is less than the first temperature threshold value, the open state is established.

Furthermore, a boiler that heats the supplied water to generate superheated steam, a steam turbine that is rotationally driven by the superheated steam that has been overheated in the boiler, drives a generator, and exhaust steam from the steam turbine is returned to water. In a power plant including a water supply line for supplying to the boiler, a superheated steam generated in the boiler is provided with a heat storage device that stores excess heat energy, and the heat storage device is the heat storage device described above. The heat energy stored in the heat storage device is used when the power generation plant is operating.

In addition, a heat storage having a steam turbine that drives a generator, a boiler that generates a fluid to be supplied to the steam turbine, and a plurality of heat storage units that recover and store heat from a fluid that passes through a flow path provided inside. An apparatus, a turbine bypass pipe that guides a fluid generated by the boiler to the heat storage device by bypassing the steam turbine, and a turbine bypass opening/closing valve that controls a flow rate of the fluid flowing into the turbine bypass pipe. A method for controlling operation during fast cutback in a power plant, wherein the plurality of heat storage units have temperature characteristics in different temperature ranges, and the flow path includes the fluid flowing into the heat storage device in each heat storage unit. A plurality of branch flow paths, each branch flow path is provided with an on-off valve for controlling the inflow of the fluid into the heat storage section in which the flow path guides the fluid, and when a system cutoff instruction is received, While narrowing down the load of the boiler, the turbine bypass opening/closing valve is opened, the temperature of the fluid passing through the turbine bypass pipe is measured, and the heat storage unit having the temperature characteristic in a temperature range to which the temperature of the fluid belongs. It is characterized in that the on-off valve provided in the branch flow path for guiding the fluid to is opened and the other on-off valves are closed.

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

(A) is a system block diagram of the power generation plant of embodiment of this invention, (b) is a block diagram of the control apparatus of embodiment of this invention. (A) And (b) is explanatory drawing for demonstrating the open/close state of the on-off valve at the time of the operation of the power generation plant of embodiment of this invention. It is a block diagram of the heat storage apparatus of embodiment of this invention. (A) is an explanatory view for explaining changes in boiler load and generation of excess steam during FCB operation, and (b) is a table showing correspondence between boiler load and steam temperature. (A) is a graph showing the relationship between the manner in which the steam temperature changes and the operating mode, and (b) is a table showing the transition conditions depending on the operating mode and temperature. (A) And (b) is explanatory drawing for demonstrating the open/close state of each on-off valve for every operation mode of the heat storage apparatus of embodiment of this invention. (A) And (b) is explanatory drawing for demonstrating the open/close state of each on-off valve for every operation mode of the heat storage apparatus of embodiment of this invention. It is explanatory drawing for demonstrating the design temperature of each heat exchanger of the boiler of a power generation plant. It is explanatory drawing for demonstrating an example of the connection at the time of heat recovery from the heat storage apparatus of embodiment of this invention. It is a block diagram of the heat storage apparatus of the modification of this invention. (A) And (b) is explanatory drawing for demonstrating the open/close state of each on-off valve for every operation mode of the heat storage apparatus of the modified example of this invention. (A) And (b) is explanatory drawing for demonstrating the open/close state of each on-off valve for every operation mode of the heat storage apparatus of the modified example of this invention. (A) And (b) is a block diagram of the heat storage apparatus of the other modified example of this invention. (A) And (b) is a block diagram of the heat storage apparatus of the other modified example of this invention. (A) And (b) is a block diagram of the heat storage apparatus of the other modified example of this invention. (A) And (b) is a system block diagram of the modification of this invention. It is explanatory drawing for demonstrating the other connection example at the time of heat recovery from the heat storage apparatus of embodiment of this invention.

An example of a power plant to which the heat storage device according to the embodiment of the present invention is applied will be described. The heat storage device of the present embodiment is used, for example, in the power generation plant 100 shown in FIG.

FIG. 1A is a fluid system diagram of the power generation plant 100 of this embodiment. The power generation plant 100 of the present embodiment combusts a fuel and generates steam by the heat of the combustion, and a steam generator 110 drives the generator 101 by rotating a turbine using the steam generated by the boiler 110. Steam turbine 120, a water supply line 130 that supplies water to the boiler 110, a heat storage device 140 that stores the heat energy of the steam overheated in the boiler 110, and a control device 150 (FIG. 1B). ..

The boiler 110 includes a economizer (ECO) 111, a furnace water cooling wall 112, a brackish water separator 113, a superheater 114, and a reheater 115. The superheater 114 may be provided in a plurality of stages from downstream to upstream.

The steam turbine 120 includes a high pressure steam turbine (HPT) 121, an intermediate pressure steam turbine (IPT) 122, and a low pressure steam turbine (LPT) 123, each of which performs a predetermined work for driving the generator 101. Prepare

On the water supply line 130, a condenser 131, a condensate pump 132, a low pressure water superheater (low pressure heater) 133, a deaerator 134, a water supply pump 135, and a high pressure water superheater (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 in the economizer 111 passes through a furnace wall pipe (not shown) formed in the wall of the furnace water cooling wall 112 to generate a water-steam two-phase fluid. 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 led to the superheater 114, and the saturated water is led to the condenser 131 through the first pipe 161.

The saturated steam separated by the brackish water separator 113 is superheated by the superheater 114 by heat exchange with the combustion gas, and is introduced into the high-pressure steam turbine 121 via the main steam pipe 162. The steam that has performed a 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 heats the steam that has performed a predetermined work in the high-pressure steam turbine 121. The steam superheated in 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 their work and drive the generator 101. The main steam pipe 162 is provided with a first stop valve 176. Further, the high temperature reheat steam pipe 164 is provided with a second stop valve 177.

The main steam pipe 162 and the low temperature reheat steam pipe 163 are connected to each other via a high pressure bypass steam pipe 165 having a first opening/closing valve 171.

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

Further, the power generation plant 100 includes a turbine bypass steam pipe 167 that branches from the high temperature reheat steam pipe 164 and guides the steam to the condenser 131 by bypassing the intermediate pressure steam turbine 122. The turbine bypass steam pipe 167 is provided with a turbine bypass opening/closing valve 172.

The heat storage device 140 of this embodiment is arranged on the turbine bypass steam pipe 167. The thermal energy of the steam guided to the heat storage device 140 via the turbine bypass steam pipe 167 is stored in the heat storage device 140. The steam after heat exchange in the heat storage device 140 is introduced into the condenser 131.

Note that the turbine bypass steam pipe 167 may further include a second bypass steam pipe 168 that bypasses the heat storage device 140 and guides steam to the condenser 131. In this case, a third opening/closing valve 173 and a fourth opening/closing valve 174 are provided downstream of the branch point between the turbine bypass steam pipe 167 and the second bypass steam pipe 168, respectively.

Further, the turbine bypass steam pipe 167 is provided with a temperature sensor 181 for detecting the temperature of steam passing through the inside.

As shown in FIG. 1( b ), the control device 150 receives an instruction from the outside (a control console 151 or the like placed in a power plant) or various types of devices including the temperature sensor 181 installed in the power plant 100. The opening and closing of each on-off valve is controlled according to the signal from the sensor.

For example, the power plant 100 of the present embodiment is generated in the boiler 110 without supplying the steam to the steam turbine 120 and the normal operation mode in which the normal operation mode in which the generator 101 is driven is performed. It has two kinds of operation modes: a heat storage operation mode in which the heat energy of the vapor is stored in the heat storage device 140.

Upon receiving an operation command in the normal operation mode from the control console 151 or the like, the control device 150 outputs a close command to the turbine bypass on-off valve 172 and the first on-off valve 171 as shown in FIG. To do. As a result, the turbine bypass opening/closing valve 172 and the first opening/closing valve 171 are closed, steam and water circulate between the boiler 110, the steam turbine 120, and the water supply line 130, and the generator 101 is driven.

On the other hand, when receiving the operation command in the heat storage operation mode, the control device 150 causes the turbine bypass opening/closing valve 172, the third opening/closing valve 173, and the first opening/closing valve 171 to open as shown in FIG. 2B. Is output. Further, it outputs a close command to the fourth on-off valve 174, the first stop valve 176 and the second stop valve 177. As a result, the turbine bypass opening/closing valve 172 and the third opening/closing valve 173 are opened, and the steam in the high temperature reheat steam pipe 164 is guided to the heat storage device 140.

Further, the control device 150 of the present embodiment also controls the opening/closing of the opening/closing valve provided in each flow path of the heat storage device 140 described later. Details of the control will be described later.

[Heat storage device]
Next, the heat storage device 140 of this embodiment will be described with reference to FIG. Hereinafter, in the present specification, steam, water, and the like that recirculate in the power generation plant 100 are referred to as fluids when there is no need to distinguish them.

The heat storage device 140 of the present embodiment includes a plurality of heat storage layers each made of a heat storage material having temperature characteristics (melting points) in different temperature ranges. A heat exchange unit is provided in each heat storage layer.

A channel is provided in the heat storage device 140 so that the heat exchange units in each heat storage layer are connected in series and in parallel. When heat is stored in the heat storage device 140, the path through which the fluid passes is changed according to the temperature of the fluid supplied to the heat storage device 140. This efficiently accumulates heat. The path change is realized by a command from the control device 150 to an on-off valve provided for each fluid described later.

Hereinafter, in the present embodiment, as the heat storage layer, the high temperature heat storage layer 210 (hereinafter, simply referred to as the high temperature layer 210) formed of a heat storage material having a temperature characteristic (melting point) in a temperature range (first temperature range) centered at 580°C. (Also referred to as "."), a medium temperature heat storage layer 220 (medium temperature layer 220) composed of a heat storage material having a temperature characteristic in a temperature range (second temperature range) centered at 500°C, and a temperature range centered at 400°C. An example will be described in which three heat storage layers, a low temperature heat storage layer 230 (low temperature layer 230) formed of a heat storage material having a temperature characteristic in the (third temperature range), are provided.

The heat storage device 140 includes a first flow path 241, a second flow path 242, and a third flow path 243 as flow paths used during heat storage. The first flow path 241 allows the fluid to pass through the high temperature layer 210, the intermediate temperature layer 220, and the low temperature layer 230 in this order. The fluid passing through the first flow path 241 exchanges heat in each heat storage layer and accumulates heat in each heat storage layer. The second flow path 242 allows the fluid to pass through the intermediate temperature layer 220 and the low temperature layer 230 in this order. The fluid passing through the second flow path 242 exchanges heat with each heat storage layer and accumulates heat in each heat storage layer. The third flow path 243 allows the fluid to pass only through the low temperature layer 230. The fluid passing through the third flow path 243 exchanges heat with the low temperature layer 230 and accumulates heat in the low temperature layer 230.

Heat exchange is performed in the heat exchange section provided in each heat storage layer. In the present embodiment, as shown in FIG. 3, the high temperature layer 210 has a high temperature heat exchange section 211, the intermediate temperature layer 220 has a first intermediate temperature heat exchange section 221 and a second intermediate temperature heat exchange section 222, and the low temperature layer 230. The first low-temperature heat exchange section 231, the second low-temperature heat exchange section 232, and the third low-temperature heat exchange section 233 are provided in each.

Each heat exchange section (high temperature heat exchange section 211, first medium temperature heat exchange section 221, second medium temperature heat exchange section 222, first low temperature heat exchange section 231, second low temperature heat exchange section 232, third The low temperature heat exchange section 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, each 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 radiated.

The first flow path 241 is branched from the turbine bypass steam pipe 167 at a branch point 271, and the high temperature heat exchange section 211, the first intermediate temperature heat exchange section 221 and the first low temperature heat exchange section 231 are connected in this order, and a confluence point 272 is obtained. To the turbine bypass steam pipe 167. The first flow path 241 allows the fluid flowing into the heat storage device 140 to pass through the high temperature heat exchange unit 211, the first intermediate temperature heat exchange unit 221, and the first low temperature heat exchange unit 231 in this order, and discharges the fluid from the heat storage device 140. When the temperature of the supplied fluid is higher than the melting point of the high temperature layer 210, the heat energy of the fluid is stored in the high temperature layer 210, the intermediate temperature layer 220, and the low temperature layer 230 in this order.

The second flow path 242 is branched from the turbine bypass steam pipe 167 at a branch point 271, the second intermediate temperature heat exchange section 222 and the second low temperature heat exchange section 232 are connected in this order, and the turbine bypass steam pipe is joined at a confluence point 272. 167. The second flow path 242 allows the fluid flowing into the heat storage device 140 to pass through the second intermediate-temperature heat exchange unit 222 and the second low-temperature heat exchange unit 232 in this order, and discharges from the heat storage device 140. When the temperature of the supplied fluid is higher than the melting point of the intermediate temperature layer 220, the heat energy of the fluid is stored in the intermediate temperature layer 220 and the low temperature layer 230 in this order.

The third flow path 243 is branched from the turbine bypass steam pipe 167 at a branch point 271 and is connected to the turbine bypass steam pipe 167 at a confluence point 272 via the third low temperature heat exchange section 233. The third flow path 243 allows the fluid flowing into the heat storage device 140 to pass through only the third low-temperature heat exchange section 233 and discharge from the heat storage device 140. When the temperature of the supplied fluid is higher than the melting point of the low temperature layer 230, the heat energy of the fluid is stored in the low temperature layer 230.

A high temperature on-off valve 251, an intermediate temperature on-off valve 252, and a low-temperature on-off valve 253 are provided on the inlet side of the heat storage device 140 of the first flow path 241, the second flow path 242, and the third flow path 243, respectively. These on-off valves are opened/closed in response to a command from the control device 150 issued according to the temperature of the fluid flowing in the turbine bypass steam pipe 167 upstream of the heat storage device 140.

The control device 150 detects the temperature of the fluid flowing into the heat storage device 140 and opens/closes each on-off valve according to the temperature to control the inflow path of the fluid. For example, the opening and closing of the on-off valve is controlled according to the temperature of the inflowing fluid so that heat is stored in the heat storage layer of the heat storage material having a melting point that is lower than the temperature and has the closest melting point. A specific example of the 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 that utilizes the latent heat of phase transformation 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 this latent heat storage material. The heat storage material used for each heat storage layer may be an alloy-based material having a heat storage temperature (melting point) of more than 500°C. Further, the alloy-based material may have a structure containing ceramics or a metal. For example, the latent heat storage microcapsules disclosed in WO 2017/200021 can be used.

By using a heat storage material having a structure in which a latent heat storage material is included in each heat storage layer by means of ceramics, etc., it is possible to obtain a heat storage section that operates only by heat input/output, utilizing the phase transformation of the latent heat storage material. Since the melting temperature can be controlled by the composition at the time of manufacturing the latent heat storage material, the temperature range of the fluid can be set more finely.

The heat storage material used for each heat storage layer is selected according to the temperature range of the heat energy stored in the heat storage device 140 and having a melting point within the temperature range. Further, the heat storage capacity of each heat storage layer is determined based on the estimated amount of surplus heat energy. As a result, the excess energy generated can be efficiently stored without wasting it. This also leads to optimization of capital investment.

Note that, in the heat storage device 140, as a flow path used at the time of heat recovery, a flow path that connects the heat exchange parts in the same heat storage layer is further provided. As a flow path for heat recovery, the heat storage device 140 includes a first heat recovery pipe 261 that passes through the high temperature heat exchange section 211 of the high temperature layer 210, a first intermediate temperature heat exchange section 221 and a second intermediate temperature heat exchange of the intermediate temperature layer 220. A second heat recovery pipe 262 passing through the portion 222, and a third heat recovery pipe 263 passing through the first low temperature heat exchange part 231, the second low temperature heat exchange part 232 and the third low temperature heat exchange part 233 of the low temperature layer 230. Equipped with.

The first heat recovery pipe 261 recovers heat from only the high temperature layer 210 by allowing the fluid to pass through only the high temperature layer 210 during heat recovery. The second heat recovery pipe 262 recovers heat from only the intermediate temperature layer 220 by passing the fluid through only the intermediate temperature layer 220. The third heat recovery pipe 263 recovers heat from only the low temperature layer 230 by allowing the fluid to pass through only the low temperature layer 230.

As described above, according to the heat storage device 140 of the present embodiment, at the time of heat recovery, it is possible to individually and independently recover the heat energy of a plurality of different temperatures according to the melting points in each heat storage layer. Then, the recovered thermal energy of different temperatures can be provided to the users according to the required temperatures. That is, according to the heat storage device 140 of the present embodiment, it is possible to properly use heat according to the application.

[Example of use]
Hereinafter, a usage example of the power generation plant 100 including the heat storage device 140 of the present embodiment will be described.

For example, in the power generation plant 100, when an accident occurs in the transmission line system or the like, the generator 101 is disconnected from the system, and the generated power is reduced to the auxiliary power for the office, which corresponds to several% of the normal operation. Back (Fast Cut Back (FCB)) operation is performed. When shifting to this FCB operation, the steam turbine 120 that drives the generator 101 is put into an unloaded state. The input of water supply or the like to the boiler 110 is rapidly narrowed down to the minimum load, and the operation is shifted to the single load operation in the plant.

An outline of control during FCB operation by the power generation plant 100 including the heat storage device 140 of the present embodiment will be described with reference to FIG.

After the system is shut down, for example, in a coal combustion plant, by stopping the operation of the mills that supply coal to the boiler 110 one by one at the timing indicated by the star on the broken line, the load on the boiler 110 is, for example, 5%. It is narrowed down to the extent. Even if the operation of the mill is stopped in this way, the steam generated by the boiler 110 continues to be generated as excess energy, as indicated by the shaded area.

When the load on the boiler 110 is narrowed down, the temperature of the steam passing through the turbine bypass steam pipe 167 also drops. For example, FIG. 4B shows changes in the temperature of the steam passing through the turbine bypass steam pipe 167 when the load of the boiler 110 is gradually reduced.

In the present embodiment, the heat quantity of the surplus energy that continues to be generated after the system is cut off is stored in the heat storage device 140. At this time, each on-off valve is controlled to open/close according to the temperature of the steam flowing through the turbine bypass steam pipe 167, and heat is stored in the heat storage layer of the heat storage material having a melting point which is lower than the temperature and has the closest melting point.

After the system is restored, the heat energy stored in the heat storage device 140 is recovered and used to operate the boiler 110. At this time, according to the design temperature of each heat exchanger (furnace water cooling wall 112, brackish water separator 113, superheater 114) included in the boiler 110, a part of the fluid supplied to the heat exchanger is branched and designed. Heat energy is recovered from the heat storage layer of the heat storage material having a melting point corresponding to the temperature and returned to the inside of the boiler 110.

The flow of control relating to heat storage in the heat storage device 140 by the control device 150 during FCB operation will be described below.

When the control device 150 receives the system cutoff instruction, it narrows down the load on the boiler 110 and outputs an open command to the turbine bypass on-off valve 172 to open the turbine bypass on-off valve 172. As a result, the fluid generated in the boiler 110 is guided to the heat storage device 140 via the turbine bypass steam pipe 167.

After that, the control device 150 detects the temperature of the fluid flowing through the turbine bypass steam pipe 167, and controls the opening/closing of the high temperature opening/closing valve 251, the intermediate temperature opening/closing valve 252, and the low temperature opening/closing valve 253 according to the detected temperature.

Note that, in this case, the temperature range of each heat storage layer is determined according to the bypass steam temperature after a lapse of a predetermined time after the system is shut off. Furthermore, regarding the heat storage capacity of each heat storage layer, the amount of surplus energy after the passage of each time is set to a capacity capable of storing heat.

In the following, when the latent heat storage material having a melting point of 580° C. is used for the high temperature layer 210, the latent heat storage material having a melting point of 500° C. is used for the intermediate temperature layer 220, and the latent heat storage material having a melting point of 400° C. is used for the low temperature layer 230. As an example, a specific example of the opening/closing instruction of each on-off valve by the control device 150 will be described. Here, the second bypass steam pipe 168 will also be described.

Note that the steam temperature in the turbine bypass steam pipe 167 (turbine bypass steam temperature) due to the load reduction of the boiler 110 changes as shown in FIG. 5(a).

Here, the temperature thresholds T1 and T2 are set to values that allow a margin of about 10° C. for the melting point of each latent heat storage material. For example, T1 is 590°C and T2 is 510°C. Further, T3 (=410° C.) is set as a temperature threshold value for bypassing the heat via the second bypass steam pipe 168 without storing heat in the heat storage device 140.

The control device 150 of the present embodiment controls the opening and closing of each on-off valve of the heat storage device 140 each time the turbine bypass steam temperature reaches the temperature threshold value. In the present embodiment, the operation of each on-off valve in different opening/closing modes is called an operation mode. Therefore, the controller 150 shifts the operation mode every time the turbine bypass steam temperature reaches the temperature threshold value.

The relationship between the turbine bypass steam temperature T (hereinafter referred to as bypass steam noise and T) and the temperature thresholds T1, T2, T3 during execution of each operation mode is shown in the table of FIG. 5(b). As shown in the figure, the operation mode 1 is an operation mode when the bypass steam temperature T is equal to or higher than the first temperature threshold value T1. The operation mode 2 is an operation mode when the bypass steam temperature T is lower than the first temperature threshold T1 and higher than or equal to the second temperature threshold T2. Operation mode 3 is an operation mode when the bypass steam temperature T is lower than the second temperature threshold value T2 and higher than or equal to the third temperature threshold value T3. The operation mode 4 is an operation mode when the bypass steam temperature T is lower than the third temperature threshold value T3. The operation mode 4 includes, for example, an emergency such as a failure of the power generation plant 100.

In the operation mode 1, that is, when the bypass steam temperature T is equal to or higher than T1, the control device 150 opens only the high temperature on-off valve 251 and opens the other on-off valves 252, 253, as shown in FIG. 174 is closed. As a result, the fluid flowing into the heat storage device 140 flows in the order of the high temperature heat exchange section 211, the first intermediate temperature heat exchange section 221, and the first low temperature heat exchange section 231, as indicated by the thick line in the figure.

In this case, the fluid whose temperature has dropped due to heat exchange in the high temperature heat exchange section 211 flows into the first intermediate temperature heat exchange section 221. The fluid that has undergone heat exchange in the first medium-temperature heat exchange section 221 and has its temperature further lowered flows into the first low-temperature heat exchange section 231. Then, the fluid whose temperature is further lowered by the heat exchange in the first low temperature heat exchange section 231 is discharged from the heat storage device 140 to the condenser 131 via the turbine bypass steam pipe 167.

In the operation mode 2, that is, when the bypass steam temperature T is lower than T1 and higher than T2, the control device 150 opens only the medium temperature on-off valve 252 and the other on-off valves 251 as shown in FIG. 6(b). 253 and 174 are closed. As a result, the fluid flowing into the heat storage device 140 flows in the order of the second intermediate temperature heat exchange section 222 and the second low temperature heat exchange section 232, as indicated by the thick line in this figure.

In this case, the fluid whose temperature has dropped due to heat exchange in the second medium temperature heat exchange section 222 flows into the second low temperature heat exchange section 232. Then, the fluid whose temperature has been further lowered by the heat exchange in the second low temperature heat exchange section 232 is discharged from the heat storage device 140 to the condenser 131 via the turbine bypass steam pipe 167.

In the operation mode 3, that is, when the bypass steam temperature T is lower than T2 and higher than T3, the control device 150 opens only the low temperature on-off valve 253 and opens the other on-off valves 251 as shown in FIG. , 252, 174 are closed. As a result, the fluid flowing into the heat storage device 140 flows into the third low temperature heat exchange section 233, as indicated by the thick line in this figure.

In this case, the fluid whose temperature has dropped due to heat exchange in the third low temperature heat exchange section 233 is discharged from the heat storage device 140 to the condenser 131 via the turbine bypass steam pipe 167.

In the operation mode 4, that is, when the bypass steam temperature T is lower than T3, the control device 150 opens only the fourth opening/closing valve 174 and opens the other opening/closing valves 251, 252, as shown in FIG. 7B. 253 is closed. As a result, the fluid in the turbine bypass steam pipe 167 is discharged to the condenser 131 via the second bypass steam pipe 168, and the fluid does not flow into the heat storage device 140, as indicated by the thick line in this figure.

[When recovering heat]
Next, an example of heat recovery from the heat storage device 140 will be described. As described above, the heat storage device 140 of this embodiment can store heat energy in a plurality of temperature ranges. Therefore, even when heat is recovered from the heat storage device 140, it can be recovered for each temperature range and provided to the user. Here, as an example, an example is shown in which the heat energy recovered from each heat storage layer is supplied to each heat exchanger of the boiler 110 according to the design temperature thereof.

Fig. 8 shows an example of the design temperature of each heat exchanger of the boiler 110. Here, the boiler 110 shall be provided with the primary superheater 114a and the secondary superheater 114b.

As shown in this figure, the inlet side and the outlet side design temperatures of the furnace water cooling wall 112, the primary superheater 114a, and the secondary superheater 114b are 330° C., 430° C., 430° C., 470° C., 460° C., 560° C., respectively. ℃.

Therefore, in the present embodiment, a part of the fluid supplied to the furnace water cooling wall 112 is heated by passing through the low temperature layer 230 and supplied to 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 intermediate temperature layer 220, and is supplied to the outlet side thereof. Further, a part of the fluid supplied to the secondary superheater 114b is heated by passing through the high temperature layer 210 and supplied to the outlet side thereof.

In this case, as shown in FIG. 9, the inlet side of the third heat recovery pipe 263 for recovering heat energy from the low temperature layer 230 of the heat storage device 140 is connected to the inlet side pipe of the furnace water cooling wall 112. Further, the outlet side of the third heat recovery pipe 263 is connected to the outlet side pipe of the furnace water cooling wall 112. The inlet side of the second heat recovery pipe 262 for recovering heat energy from the intermediate temperature layer 220 is connected to the inlet side pipe of the primary superheater 114a. The outlet side of the second heat recovery pipe 262 is connected to the outlet side pipe of the primary superheater 114a. The inlet side of the first heat recovery pipe 261 for recovering heat energy from the high temperature layer 210 is connected to the piping on the inlet side of the secondary superheater 114b. The outlet side of the first heat recovery pipe 261 is connected to the outlet side pipe of the secondary superheater 114b.

As described above, the power plant 100 according to the present embodiment includes the heat storage device 140 having a plurality of heat storage layers each formed of a latent heat storage material having a different melting point. Then, when the surplus energy is generated, the heat energy corresponding to the melting point of the latent heat storage material forming the heat storage layer is stored in each heat storage layer of the heat storage device 140.

With this, according to the power generation plant 100 including the heat storage device 140 of the present embodiment, surplus energy can be stored independently for each temperature zone. Therefore, when recovering the heat from the heat storage device 140, the heat can be recovered from the heat storage layer that stores the heat energy according to the temperature required by the heat exchanger of the use destination, and the surplus energy can be efficiently used. For example, by utilizing this surplus energy at the time of system restoration after FCB, it is possible to provide optimum heat energy to each heat exchanger of the boiler 110, and it is possible to quickly start up.

In addition, in the heat storage device 140 of the present embodiment, a latent heat storage material that uses the latent heat of phase transformation of a substance is used as the heat storage material of each heat storage layer. As a result, it is possible to realize a heat storage unit capable of high-density heat storage, which operates only by heat input/output. 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. Thereby, for example, high temperature fluid such as turbine bypass steam can be stored at the high temperature as it is. In addition, it becomes possible to produce steam in the highest temperature range during heat dissipation.

Further, in the heat storage device 140 of the present embodiment, according to the temperature of the fluid flowing into the heat storage device 140, a flow path is provided so as to flow into the heat storage layer of the heat storage material having a melting point closest to and lower than the temperature. 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 140 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 a heat storage material having the next highest melting point. To be That is, by disposing the heat storage layers in the order of high temperature, medium temperature, and low temperature in one flow path, it is possible to recover the heat of the fluid completely. According to the power generation plant 100 having the heat storage device 140 of the present embodiment, it is possible to realize efficient operation of the power generation plant 100, including using the recovered heat energy for starting and the like.

Further, according to the heat storage device 140 of the present embodiment, a heat storage layer having sufficient performance for each temperature range of the fluid is arranged for each temperature range of the fluid. For example, when used for the storage of surplus energy during FCB operation, the temperature range of each heat storage layer is determined according to the bypass steam temperature after a lapse of a predetermined time after the system interruption. Further, the heat storage capacity of each heat storage layer is determined according to the amount of surplus energy after the passage of time.

This will enable efficient heat recovery. For example, if the heat storage section is prepared in accordance with the assumed highest temperature of the fluid flowing into the heat storage device 140, the heat recovery of the medium or low temperature fluid will be over-specified 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.

Further, in the power generation plant 100 including the heat storage device 140 of the present embodiment, the heat storage device 140 recovers the heat of the fluid without exhaustion, so the temperature of the fluid discharged from the heat storage device 140 to the condenser 131 becomes low. .. Therefore, the amount of heat returned to the condenser 131 can be suppressed.

　Especially during FCB operation, the heat quantity of excess steam is large. In the conventional power plant 100, when the FCB function is provided, all the generated excess steam is returned to the condenser 131. Therefore, not only is there a large amount of waste, but also a large receiving capacity is required on the condenser 131 side. Large-scale construction is required to achieve a large capacity of the condenser 131. However, according to the present embodiment, most of the heat quantity of the fluid returned to the condenser 131 is stored in the heat storage device 140, so the performance of the condenser 131 is the condenser 131 used when the FCB function is not provided. Can be approximately the same as. Therefore, the equipment cost can be suppressed.

The power generation plant 100 including the heat storage device 140 of the present embodiment can efficiently store heat during FCB, and can also efficiently recover the stored heat energy when returning to the system. Further, the heat storage energy stored in the heat storage device 140 can be utilized not only when the system is restored after the FCB but also when the power is normally started or when the load of the power generation plant 100 is rapidly increased. As a result, the start-up time and the load rise time can be shortened.

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

In addition, when the load change rate is a device that constitutes the power generation plant 100 and exceeds a load change rate defined by a limit corresponding to a change in heat quantity of a device other than the steam turbine 120, or a load change that the boiler 110 cannot meet the system requirements. Includes cases where required.

Further, in the power plant 100 of the present embodiment, the heat storage device 140 is arranged on the turbine bypass steam pipe 167 having the turbine bypass opening/closing valve 172. As a result, the switching to the heat storage operation mode can be immediately performed only by instructing the turbine bypass on-off valve 172 to open and close. The switching process when the system is forced to be shut off such as FCB can be easily performed, and the generated surplus energy can be easily recovered.

For example, by using the heat storage device 140 of the present embodiment for starting and stopping a steam power generation plant in DSS (Daily Start & Stop), it is possible to shorten the starting and stopping time. Further, by using the heat storage device 140 of the present embodiment, even when the steam power generation plant and the renewable energy power generation plant are used together, it is possible to level the fluctuation of the power supply amount derived from the renewable energy in total. As a result, the number of occurrences of a state in which the overall power supply amount exceeds the demand of the system is reduced.

<Modification>
[Modification of heat storage device]
In the above-described embodiment, the heat storage device 140 is configured such that the heat storage units that are the heat exchange units of the heat storage layers are connected in series and in parallel by the internal flow paths, but the configuration is not limited to this. It suffices that the heat can be stored in the optimum heat storage layer according to the temperature of the fluid flowing into the heat storage device 140, and the heat can be stored in a mode that can be used for each temperature during heat dissipation. A modified example of the heat storage device 140 will be described below.

FIG. 10 shows another example of the heat storage device 140 of the present embodiment (hereinafter, referred to as heat storage device 140a). Here, similarly to the above embodiment, a case where three heat storage layers of a high temperature layer 210, an intermediate temperature layer 220, and a low temperature layer 230 are provided will be described as an example. As shown in the figure, in the heat storage device 140a, the heat exchangers of each heat storage layer are connected in series.

The heat storage device 140a includes a high temperature heat exchange section 211, a first intermediate temperature heat exchange section 221, a first low temperature heat exchange section 231, a first flow path 241, a second flow path 342, and a third flow path 343, High temperature open/close valve 251, first medium temperature open/close valve 352, low temperature open/close valve 353, second intermediate temperature open/close valve 354, first heat recovery pipe 261, second heat recovery pipe 262, and third heat recovery pipe 263. 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 the same as the heat storage device 140, respectively. Further, the first flow path 241 and the high temperature on-off valve 251 are also similar to the heat storage device 140. Hereinafter, the configuration different from that of the heat storage device 140 will be mainly described.

The second flow path 342 branches from the turbine bypass steam pipe 167 at a branch point 271, bypasses the high temperature heat exchange section 211, and merges with the first flow path 241 at a downstream junction point 375 of the high temperature heat exchange section 211. The second flow path 342 allows the fluid flowing into the heat storage device 140a to pass through the first intermediate temperature heat exchange unit 221 and the first low temperature heat exchange unit 231 in that order, and discharges the fluid from the heat storage device 140a.

The third flow path 343 branches from the second flow path 342 at a branch point 372 downstream of the first middle temperature heat on-off valve 352, bypasses the first middle temperature heat exchange section 221, and passes through the first middle temperature heat exchange section 221. It joins the first flow path 241 at the downstream joining point 376. The third flow path 343 allows the fluid flowing into the heat storage device 140a to pass only through the first low-temperature heat exchange section 231, and discharges the fluid from the heat storage device 140a.

Downstream of the branch points 271 and 372, a high-temperature on-off valve 251, a first medium-temperature on-off valve 352, and a second medium-temperature on-off valve 354, which are opened and closed according to a command from the control device 150 to control which flow path the fluid is to flow. And a low temperature on-off valve 353 is provided. The control device 150 outputs an opening/closing command to each on-off valve according to the temperature of the fluid flowing in the turbine bypass steam pipe 167 on the upstream side of the heat storage device 140a.

To explain using the temperature thresholds T1 and T2 similar to the heat storage device 140, the control device 150 determines that the temperature of the fluid flowing upstream of the heat storage device 140 in the turbine bypass steam pipe 167 is equal to or higher than the first temperature threshold T1. The high temperature on-off valve 251 is opened and the first medium temperature on-off valve 352 is closed. When the temperature of the fluid is lower than T1, the high temperature on-off valve 251 is closed and the first medium temperature on-off valve 352 is opened. When the temperature of the fluid is equal to or higher than the second temperature threshold value T2, the second medium temperature on-off valve 354 is opened and the low temperature on-off valve 353 is closed. When the temperature of the fluid is lower than the second temperature threshold value T2, the second medium temperature on-off valve 354 is closed and the low temperature on-off valve 353 is opened.

The control of the on-off valve by the control device 150 in each of the operation modes 1 to 4 in this case will be described with reference to FIGS. 11(a) to 12(b). Here, the operation including the second bypass steam pipe 168 and the fourth on-off valve 174 will be described. In the heat storage device 140a of the present modification, the second bypass steam pipe 168 branches at the branch point 373 on the third flow path 343, bypasses the first low temperature heat exchange section 231, and at the confluence point 272, the first flow. It joins the path 241 (turbine bypass steam pipe 167).

The control device 150 controls the opening/closing of each on-off valve so that the fluid passes through the first flow path 241 in the operation mode 1, that is, when the bypass steam temperature T is T1 or more. That is, as shown in FIG. 11A, the control device 150 outputs a command signal to open only the high temperature opening/closing valve 251 and close the other opening/closing valves 174, 352, 353, 354. As a result, the fluid flowing into the heat storage device 140a flows in the order of the high temperature heat exchange part 211, the first medium temperature heat exchange part 221, and the first low temperature heat exchange part 231 as shown by the thick line, and is discharged from the heat storage device 140a. ..

In the operation mode 2, that is, when the bypass steam temperature T is lower than T1 and higher than T2, the control device 150 controls opening/closing of each on-off valve so that the fluid passes through the second flow path 342. That is, as shown in FIG. 11B, the control device 150 opens the first medium temperature on-off valve 352 and the second medium temperature on-off valve 354, and closes the other on-off valves 251, 353, 174. Output a signal. As a result, the fluid flowing into the heat storage device 140a flows in the order of the first medium temperature heat exchange unit 221 and the first low temperature heat exchange unit 231 as shown by the thick line, and is discharged from the heat storage device 140a.

In the operation mode 3, that is, when the bypass steam temperature T is lower than T2 and higher than T3, the control device 150 controls opening/closing of each on-off valve so that the fluid passes through the third flow path 243. That is, as shown in FIG. 12A, the controller 150 outputs a command signal to open the first medium temperature on-off valve 352 and the low temperature on-off valve 353 and close the other on-off valves 251, 354, 174. To do. As a result, the fluid flowing into the heat storage device 140a passes through only the first low temperature heat exchange section 231 and is discharged from the heat storage device 140, as indicated by the thick line.

In the operation mode 4, that is, when the bypass steam temperature T is lower than T3, the bypass steam is controlled so as to bypass each heat storage layer of the heat storage device 140a and pass through the second bypass steam pipe 168. That is, as shown in FIG. 12B, the control device 150 sends a command signal to open the first medium temperature on-off valve 352 and the fourth on-off valve 174 and close the other on-off valves 251, 354, 353. Output. As a result, the fluid flowing into the heat storage device 140a is guided to the condenser 131 without releasing heat to the heat storage device 140a, as indicated by the thick line.

According to this modification, as in the above embodiment, it is possible to store heat energy in a plurality of heat storage layers having different temperature characteristics. Further, when used, it is possible to recover the heat energy for each of the stored temperature levels. Therefore, surplus energy can be efficiently accumulated and recovered.

[Other modified examples of heat storage device]
Further, in the heat storage device 140, a heat exchange unit may be arranged in parallel with each heat storage layer. FIG. 13A shows a configuration example of the heat storage device 140b in this case. As shown in the figure, similar to the heat storage device 140, the first flow path 241, the second flow path 242, and the third flow path 243 are provided. The first flow path 241 passes through only the high temperature heat exchange section 211 and discharges the fluid after heat exchange from the heat storage device 140. The second flow path 242 passes only through the second intermediate temperature heat exchange section 222, and discharges the fluid after heat exchange from the heat storage device 140. Similar to the above embodiment, the third flow path 243 passes only through the third low temperature heat exchange section 233 and discharges the fluid after heat exchange from the heat storage device 140.

According to the heat storage device 140b, the same effect as the heat storage device 140 can be realized with a simple configuration.

Further, each heat exchange section of the heat storage device 140 may be provided in each heat storage layer, and may be connected in series and in parallel as in the above embodiment. That is, in each flow path, each heat storage layer may share the heat exchange unit. FIG. 13B shows a configuration example of the heat storage device 140c in this case.

As shown in the figure, the first flow path 241 passes through the high temperature heat exchange section 211, the first medium temperature heat exchange section 221, and the first low temperature heat exchange section 231. Further, the second flow path 242 passes through the first intermediate temperature heat exchange section 221 and the first low temperature heat exchange section 231. The third flow path 243 passes through the first low temperature heat exchange section 231. That is, the fluid flows into the first intermediate temperature heat exchange section 221 through the first flow channel 241 and the second flow channel 242. Further, the fluid flows into the first low temperature heat exchange section 231 through the first flow channel 241, the second flow channel 242 and the third flow channel 243.

In this way, the same effect as that of the heat storage device 140 can be obtained with a simple configuration by sharing the heat storage unit for each flow path instead of providing it individually.

Note that the number of heat storage layers is not limited as long as it is plural. For example, it may have two layers. FIG. 14A shows an example of the heat storage device in the case where the heat storage layers are two layers and the heat exchange units in each heat storage layer are connected in parallel.

The heat storage device 140d shown in FIG. 14A is provided in the high temperature layer 210 and performs high temperature heat exchange part 211 for heat exchange, and the second intermediate temperature heat exchange part 222 provided in the intermediate temperature layer 220 for heat exchange. And In addition, the fluid flowing into the heat storage device 140d is branched at a branch point 271 upstream of the high temperature heat exchange portion 211 of the first flow path 241 that passes through the high temperature heat exchange portion 211 and is discharged from the heat storage device 140d. The second flow path 242 is configured to allow the fluid flowing into the heat storage device 140d to pass through the second intermediate temperature heat exchange unit 222 and be discharged from the heat storage device 140d. Further, a high-temperature on-off valve 251 that is provided on the first flow path 241 and controls the inflow of the fluid to the high-temperature heat exchange section 211, and a fluid that is provided on the second flow path 242 and that flows to the second intermediate-temperature heat exchange section 222. A medium temperature on-off valve 252 for controlling the inflow of the gas.

In the heat storage device 140d, the high temperature on-off valve 251 is in the open state when the temperature of the fluid is equal to or higher than the predetermined first temperature threshold T1 according to the instruction from the control device 150, and the medium-temperature on-off valve 252 changes the temperature of the fluid. When it is less than the first temperature threshold value T1, the open state is established.

The control of the on-off valve by the control device 150 when the power plant 100 includes the second bypass steam pipe 168 and the fourth on-off valve 174 will be described using the heat storage device 140e of FIG. 14(b).

The configuration of the heat storage device 140e shown in FIG. 14B is the same as that of the heat storage device 140d. However, the second bypass steam pipe 168 branches from the branch point 271 and joins with the turbine bypass steam pipe 167 at the joining point 272. Further, the second bypass steam pipe 168 is provided with a fourth on-off valve 174.

In the heat storage device 140e, similar to the heat storage device 140d, the high temperature on-off valve 251 is in the open state when the temperature of the fluid is equal to or higher than the predetermined first temperature threshold T1 according to a command from the control device 150, and the medium temperature on-off valve is opened. 252 is in the open state when the temperature of the fluid is lower than the first temperature threshold value T1.

Further, in the heat storage device 140e, the medium-temperature on-off valve 252 is in the closed state according to the command from the control device 150 even if the temperature of the fluid is less than the first temperature threshold T1 but less than the second temperature threshold T2. .. When the temperature of the fluid is lower than the second temperature threshold value T2, the control device 150 opens the fourth opening/closing valve 174 and causes the fluid flowing through the turbine bypass steam pipe 167 to store the fluid in the heat storage device 140e (the high temperature heat exchange unit 211 and the first heat exchange unit 211). (2) Bypasses the intermediate temperature heat exchange section 222).

Fig. 15(a) shows an example of the heat storage device in the case where the heat storage layers are two layers and the heat exchange units in each heat storage layer are connected in series.

The heat storage device 140f shown in FIG. 15(a) is provided in the high temperature layer 210 and performs high temperature heat exchange section 211 for heat exchange, and the first intermediate temperature heat exchange section 221 provided in the intermediate temperature layer 220 for heat exchange. And Further, the fluid flowing into the heat storage device 140f passes through the high temperature heat exchange part 211 and the first medium temperature heat exchange part 221 in this order and is discharged from the heat storage device 140f, and the high temperature heat exchange of the first flow channel 241. The second flow in which the fluid branched at the branch point 271 upstream of the portion 211 and flowing into the heat storage device 140f bypasses the high temperature heat exchange part 211, passes through the first intermediate temperature heat exchange part 221, and is discharged from the heat storage device 140f. And a path 342. Further, a high temperature on-off valve 251 which is provided on the first flow path 241 and controls the inflow of the fluid to the high temperature heat exchange section 211, and a fluid which is provided on the second flow path 242 and which flows to the first intermediate temperature heat exchange section 221. A first medium temperature on-off valve 352 for controlling the inflow of the gas.

In the heat storage device 140f, when the temperature of the fluid is equal to or higher than the predetermined first temperature threshold value T1 according to a command from the control device 150, the high temperature on-off valve 251 is in the open state, and the first medium temperature on-off valve 352 controls the fluid temperature. When the temperature is lower than the first temperature threshold T1, the open state is established.

The control of the on-off valve by the control device 150 when the power plant 100 includes the second bypass steam pipe 168 and the fourth on-off valve 174 will be described using the heat storage device 140g of FIG. 15B.

The configuration of the heat storage device 140g illustrated in FIG. 15B is substantially the same as that of the heat storage device 140f. However, the second bypass steam pipe 168 branches from the branch point 372 downstream of the first medium temperature on-off valve 352 of the second flow path 342, and is connected to the turbine bypass steam pipe 167 at the confluence point 272. Further, the second bypass steam pipe 168 is provided with a fourth on-off valve 174. Further, a second intermediate temperature switching valve 354 is provided downstream of the branch point 372 of the second flow path 342.

In the heat storage device 140g, similarly to the heat storage device 140f, when the temperature of the fluid is equal to or higher than the predetermined first temperature threshold value T1 according to a command from the control device 150, the high temperature on-off valve 251 is in the open state and the first medium temperature. The on-off valve 352 is in the open state when the temperature of the fluid is lower than the first temperature threshold value T1.

In response to a command from the control device 150, the second medium temperature on-off valve 354 is in an open state when the fluid temperature is equal to or higher than the second temperature threshold T2, and the fourth on-off valve 174 causes the fluid temperature to be the second temperature threshold T2. If it is less than, it is in the open state.

In this way, the heat storage device 140 can optimize the number (size) of heat storage layers and the route according to the required temperature and the amount of steam. Heat can be stored for each temperature level with a simple configuration in which a heat exchange unit is installed in each heat storage layer and the steam path is controlled by opening and closing the on-off valve.

[Modification of heat storage fluid]
Further, in the above-described embodiment, the heat storage device 140 acquires heat energy from the fluid passing through the turbine bypass steam pipe 167 and stores the heat energy. However, the heat storage target is not limited to the heat energy of this fluid. For example, the heat energy of saturated water returned from the brackish water separator 113 to the condenser 131 may be stored. A system diagram of the power generation plant 100 in this case is shown in FIG.

As shown in the figure, a heat storage pipe 161a is provided in the first pipe 161 for returning saturated water from the brackish water separator 113 to the condenser 131. The heat storage pipe 161 a branches from the first pipe 161 and passes through the heat storage device 140 to join the first pipe 161.

The heat storage pipe 161a is provided with a fifth opening/closing valve 175 on the upstream side of the heat storage device 140. The fifth on-off valve 175 is an on-off valve for controlling whether saturated water supplied from the brackish water separator 113 is returned to the condenser 131 via the heat storage device 140 or directly returned. The control device 150 issues a command to open the saturated water when it flows into the heat storage device 140.

At this time, the heat storage device that stores the heat energy of the saturated water returned from the brackish water separator 113 to the condenser 131 is independent of the heat storage device 140 provided on the turbine bypass steam pipe 167. May be An example of piping in this case is shown in FIG.

In this case, the heat storage device 141 is provided, for example, on the first pipe 161 as shown in this figure. In this case as well, a bypass flow path for returning the saturated water to the condenser 131 by bypassing the heat storage device 141 may be further provided.

As in these modifications, the saturated water returned from the brackish water separator 113 to the condenser 131 is also configured to store heat, whereby excess heat energy generated in the system can be stored without exhaustion. it can. Then, the stored heat energy can be used when the system is restored.

[Modifications during heat recovery]
In the power generation plant 100 of the above-described embodiment, the thermal energy stored in the heat storage device 140 is supplied to the heat exchanger of the boiler 110 corresponding to the temperature range of the heat storage layer for each heat storage layer, so that the boiler 110 rapidly increases. It efficiently supports energy supply when the load rises.

However, the method of recovering heat from the heat storage device 140 is not limited to this. For example, as shown in FIG. 17, the fluid may be passed layer by layer from the low temperature layer 230, and the entire heat energy stored in the heat storage device 140 may be recovered and then returned to the system of the power generation plant 100.

The recovery destination of the fluid after recovering the heat energy is, for example, the main steam pipe 162. The fluid to the heat storage device 140 is supplied from, for example, the water supply line 130. In this case, for example, the fourth heat recovery pipe 264 that connects the water supply line 130 and the main steam pipe 162 is provided, and the heat storage device 140 is disposed on the fourth heat recovery pipe 264.

By piping in this way, the water introduced into the heat storage device 140 is heated in the order of the low temperature layer 230, the intermediate 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 140 and can be directly fed to the high-pressure steam turbine 121.

In this modification, the low temperature reheat steam pipe 163 may be used as the return destination of the fluid after heat energy recovery in the heat storage device 140 during high load operation.

It should be noted that the present invention is not limited to the above-described embodiments and modifications, and various modifications can be made according to the design and the like as long as they do not deviate from the technical idea of the present invention.

100: power generation plant, 101: generator, 110: boiler, 111: economizer, 112: water cooling wall of furnace, 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: Condenser, 132: Condensate pump, 133: Low pressure Heater, 134: Deaerator, 135: Water supply pump, 136: High pressure heater,
140: heat storage device, 140a: heat storage device, 140b: heat storage device, 140c: heat storage device, 140d: heat storage device, 140e: heat storage device, 140f: heat storage device, 140g: heat storage device, 141: heat storage device,
150: control device, 151: control console,
161: First pipe, 161a: Heat storage pipe, 162: Main steam pipe, 163: Low temperature reheat steam pipe, 164: High temperature reheat steam pipe, 165: High pressure bypass steam pipe, 166: First exhaust steam pipe, 167: Turbine bypass steam pipe, 168: second bypass steam pipe,
171: First on-off valve, 172: Turbine bypass on-off valve, 173: Third on-off valve, 174: Fourth on-off valve, 175: Fifth on-off valve, 176: First stop valve, 177: Second stop valve ,
181: temperature sensor,
210: high temperature heat storage layer (high temperature layer), 211: high temperature heat exchange section, 220: medium temperature heat storage layer (medium temperature layer), 221: first medium temperature heat exchange section, 222: second medium temperature heat exchange section, 230: low temperature heat storage layer (Low temperature layer), 231: first low temperature heat exchange section, 232: second low temperature heat exchange section, 233: third low temperature heat exchange section, 241: first flow path, 242: second flow path, 243: third flow. Passage, 251: high temperature on-off valve, 252: medium temperature on-off valve, 253: low temperature on-off valve, 261: first heat recovery pipe, 262: second heat recovery pipe, 263: third heat recovery pipe, 264: fourth heat recovery pipe Pipe, 271: branch point, 272: confluence point,
342: Second flow path, 343: Third flow path, 352: First medium temperature on-off valve, 353: Low temperature on-off valve, 354: Second medium temperature on-off valve, 372: Branch point, 373: Branch point, 375: Confluence point 376: Confluence

Claims (17)

1. A heat storage device having a plurality of heat storage units for recovering and accumulating heat from a fluid passing through a flow path provided inside,
   The heat storage section,
   A first heat storage part having a temperature characteristic in the first temperature range,
   A second heat storage unit having a temperature characteristic in a second temperature range which is a temperature range lower than the first temperature range,
   The flow path is
   The fluid flowing into the heat storage device, the first heat storage unit, a first flow path for passing through the second heat storage unit in this order and discharged from the heat storage device,
   The first branch part upstream of the first heat storage part of the first flow path branches the fluid flowing into the heat storage device, bypasses the first heat storage part and passes through the second heat storage part. A second flow path discharged from the heat storage device,
   An on-off valve for controlling the inflow of the fluid into the flow path,
   The on-off valve is
   A first on-off valve provided on the first flow path, for controlling the inflow of the fluid to the first heat storage section,
   A second on-off valve which is provided on the second flow path and which controls the inflow of the fluid into the second heat storage section,
   The first open/close valve is in an open state when the temperature of the fluid is equal to or higher than a first temperature threshold value determined by the first temperature range,
   The said 2nd on-off valve will be in an open state, when the temperature of the said fluid is less than the said 1st temperature threshold value, The thermal storage apparatus characterized by the above-mentioned.
2. The heat storage device according to claim 1, wherein
   The on-off valve further comprises a third on-off valve provided downstream of the second branch portion downstream of the second on-off valve of the second flow path,
   From the second branch part, the fluid flowing into the second flow path is a bypass flow path that bypasses the second heat storage part and is discharged, and a bypass flow path having a bypass opening/closing valve branches,
   The third on-off valve is in an open state when the temperature of the fluid is equal to or higher than the second temperature threshold value determined by the second temperature range,
   The heat storage device, wherein the bypass opening/closing valve is opened when the temperature of the fluid is lower than the second temperature threshold.
3. A heat storage device having a plurality of heat storage units for recovering and accumulating heat from a fluid passing through a flow path provided inside,
   The heat storage section,
   A first heat storage part having a temperature characteristic in the first temperature range,
   A second heat storage unit having a temperature characteristic in a second temperature range which is a temperature range lower than the first temperature range,
   The flow path is
   The fluid flowing into the heat storage device, a first flow path that passes through the first heat storage unit and is discharged from the heat storage device,
   A second flow path that branches at a first branch portion of the first flow path upstream of the first heat storage unit and that causes the fluid flowing into the heat storage device to pass through the second heat storage unit and be discharged from the heat storage device. When,
   An on-off valve for controlling the inflow of the fluid into the flow path,
   The on-off valve is
   A first on-off valve provided on the first flow path, for controlling the inflow of the fluid to the first heat storage section,
   A second on-off valve which is provided on the second flow path and which controls the inflow of the fluid into the second heat storage section,
   The first open/close valve is in an open state when the temperature of the fluid is equal to or higher than a first temperature threshold value determined by the first temperature range,
   The said 2nd on-off valve will be in an open state, when the temperature of the said fluid is less than the said 1st temperature threshold value, The thermal storage apparatus characterized by the above-mentioned.
4. The heat storage device according to claim 3,
   The second on-off valve, even if the temperature of the fluid is less than the first temperature threshold value, if it is less than the second temperature threshold value determined by the second temperature range, the closed state,
   When the temperature of the fluid is lower than the second temperature threshold value, it is a bypass flow path that branches at the first branch portion, and the fluid flows by bypassing the first heat storage portion and the second heat storage portion. A heat storage device characterized in that a bypass opening/closing valve provided on a bypass flow path is opened.
5. The heat storage device according to claim 3,
   The heat storage unit further comprises a fourth heat storage unit having a temperature characteristic in the second temperature range,
   The first flow path further discharges the fluid that has passed through the first heat storage unit from the heat storage device by further passing through the fourth heat storage unit.
6. The heat storage device according to claim 3,
   The heat storage device, wherein the first flow path allows the fluid that has passed through the first heat storage unit to further pass through the second heat storage unit and to be discharged from the heat storage device.
7. The heat storage device according to any one of claims 1 to 6,
   The heat storage section includes a latent heat storage material that utilizes latent heat of phase transformation of a substance,
   The heat storage device, wherein the temperature characteristics are determined based on a melting temperature of the latent heat storage material.
8. A boiler that heats the supplied water to generate superheated steam,
   A steam turbine that is driven to rotate by superheated steam that is overheated in the boiler, and drives a generator,
   In a power plant comprising a water supply line for returning the exhaust steam from the steam turbine to water and supplying it to the boiler,
   Of the superheated steam generated in the boiler, a heat storage device for accumulating excess heat energy,
   The heat storage device is the heat storage device according to any one of claims 1 to 7,
   A power plant, wherein the heat energy stored in the heat storage device is used during operation of the power plant.
9. The power plant according to claim 8,
   The operation includes a system return operation after system interruption,
   The power plant, wherein the heat energy accumulated in the heat storage device is recovered from the heat storage device for each temperature range.
10. The power plant according to claim 8,
    The steam turbine comprises a high-pressure steam turbine and a medium-low pressure steam turbine,
    The boiler includes a reheater for reheating steam after rotationally driving the high-pressure steam turbine,
    The water supply line includes a condenser that condenses steam that has finished work in the steam turbine and stores it as water,
    The power plant is
    Steam reheated by the reheater, a turbine bypass pipe that bypasses the medium and low pressure steam turbine and leads to the condenser,
    A control device for controlling the opening and closing of the on-off valve,
    The heat storage device is disposed on the turbine bypass pipe,
    The control device controls opening/closing of the opening/closing valve according to a steam temperature in the turbine bypass pipe.
11. The power plant according to claim 10,
    The boiler is
    A furnace for heating the water to produce a water-steam two-phase fluid;
    A steam-water separator for separating the water-steam two-phase fluid superheated in the furnace into saturated steam and saturated water,
    The power plant is
    A first pipe for guiding the saturated water generated by the brackish water separator to the condenser,
    The saturated water is further supplied from the first pipe to the heat storage device.
12. The power plant according to claim 10,
    The boiler is
    A furnace for heating the water to produce a water-steam two-phase fluid;
    A steam-water separator for separating the water-steam two-phase fluid superheated in the furnace into saturated steam and saturated water,
    The power plant is
    A second heat storage device, which is the heat storage device according to any one of claims 1 to 7,
    A first pipe for guiding the saturated water generated by the brackish water separator to the condenser,
    The said 2nd heat storage device is arrange|positioned on the said 1st piping, The power generation plant characterized by the above-mentioned.
13. The power plant according to claim 8,
    The thermal energy stored in the heat storage device is used for heating the water in the boiler during the operation,
    The boiler is
    A first heat exchanging section for generating a fluid having a temperature in the first temperature range by heat exchange,
    A second heat exchange section for generating a fluid having a temperature in the second temperature range by heat exchange,
    During the operation, a part of the fluid generated in the second heat exchange section is guided to the second heat storage section, the second heat storage section recovers the thermal energy, and then the second heat storage section is guided to the first heat exchange section. Two heat recovery tubes,
    During the operation, a part of the fluid generated in the first heat exchange unit is guided to the first heat storage unit, and the thermal energy is recovered in the first heat storage unit, and then the outlet side of the first heat exchange unit. And a first heat recovery pipe leading to the power generation plant.
14. The power plant according to claim 8,
    The thermal energy stored in the heat storage device is used for the rotational drive of the steam turbine during the operation,
    A power generation plant comprising a fourth heat recovery pipe for guiding a part of the water in the water supply line to the steam turbine via the heat storage device during the operation.
15. The power plant according to claim 10,
    Further comprising a turbine bypass opening/closing valve for controlling the inflow of the steam into the turbine bypass pipe,
    The control device opens the turbine bypass opening/closing valve when the system is shut off,
    The first temperature range and the second temperature range of the heat storage device are the outlet side steam of the boiler, which is determined according to the load of the boiler after the first time has elapsed and after the second time has elapsed after the system interruption, respectively. A power plant characterized by being determined in correspondence with the temperature of.
16. The power plant according to claim 15, wherein
    Capacity of each of the first heat storage unit and the second heat storage unit is determined according to the thermal energy generated in the first time and the second time after the system interruption. plant.
17. A steam turbine that drives a generator,
    A boiler that generates a fluid to be supplied to the steam turbine,
    A heat storage device having a plurality of heat storage units for recovering and accumulating heat from a fluid passing through a flow path provided inside,
    A fluid generated by the boiler, a turbine bypass pipe that bypasses the steam turbine and leads to the heat storage device,
    A turbine bypass opening/closing valve for controlling the flow rate of the fluid flowing into the turbine bypass pipe, and an operation control method during fast cutback in a power plant comprising:
    The plurality of heat storage units have temperature characteristics in different temperature ranges,
    The flow path includes a plurality of branch flow paths for guiding the fluid flowing into the heat storage device to each heat storage unit,
    Each branch channel includes an on-off valve that controls the inflow of the fluid into the heat storage unit through which the channel guides the fluid,
    When the system cutoff instruction is received, the load on the boiler is narrowed down, and the turbine bypass opening/closing valve is opened.
    The temperature of the fluid passing through the turbine bypass pipe is measured, and the on-off valve provided in the branch passage that guides the fluid to the heat storage unit having the temperature characteristic in the temperature range to which the temperature of the fluid belongs opens. And a state in which the other on-off valve is closed, and an operation control method at the time of fast cutback.

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