JP7039403B2 - Thermal power plant - Google Patents

Description

Embodiments of the present invention relate to a thermal power plant.

Thermal power plants are required to increase generator output when the grid frequency in the power system decreases. In this case, in general, the main steam control valve, which is operated to throttle the opening during normal operation (operation performed when the grid frequency is stable) (throttle operation), is lowered in the grid frequency. Open to the opening according to. As a result, the amount of steam supplied to the steam turbine as an operating medium (the amount of swallowed steam) is increased. As a result, the generator output (load) increases and the system frequency is restored.

However, an increase in power generation by natural energy may cause a sudden change in the amount of power generation, resulting in a sudden decrease in the system frequency. For example, a decrease in system frequency of about 1% may occur in a short time of about 10 seconds. Therefore, it may be difficult to realize the required increase in generator output only by executing the above operations.

Various technologies have been proposed to deal with such problems. For example, it has been proposed to perform a "condensate throttle operation". In the "condensate throttle operation", the flow rate of the extracted steam supplied from the steam turbine to the feed water heater as a heating medium is reduced, and the flow rate of the condensate water supplied to the feed water heater as a heating medium is reduced. By executing the "condensate throttle operation", the steam that performs expansion work in the steam turbine increases, so that the generator output increases. For example, in the "condensation throttle operation", after 30 seconds have passed from the start of the "condensation throttle operation", the power generation output can be increased by 2 to 5% with respect to the power generation output of the normal operation.

Japanese Unexamined Patent Publication No. 2013-53531 Japanese Unexamined Patent Publication No. 62-291402

However, in the above, various problems may occur, so that it may be difficult to sufficiently increase the generator output when the frequency of the power system decreases.

Therefore, the problem to be solved by the present invention is to provide a thermal power generation plant capable of easily realizing a sufficient increase in the generator output on the turbine plant side when the frequency of the electric power system decreases. That is.

The thermal power plant according to the embodiment includes a steam turbine, a condenser, a water supply heating unit, a boiler, and a generator. The condenser cools and condenses the steam exhausted from the steam turbine. The water supply heating unit uses the steam extracted from the steam turbine as a heating medium to heat the condensed water in the condenser. The boiler produces steam by heating the heated water in the water supply heating unit. The steam generated by the boiler is supplied to the steam turbine to drive the generator and generate electricity. The electric power generated by the generator is output to the electric power system. The thermal power plant according to the embodiment further includes an bleed air throttle valve and a control device. The bleed air throttle valve adjusts the flow rate of the heating medium supplied to the water supply heating unit. The control device controls the operation of the bleed air throttle valve. The water supply heating unit is provided with a plurality of water supply heaters, and the pressure of the heating medium supplied to each of the plurality of water supply heaters is configured to be sequentially increased along the flow of the condensed water in the condenser. In addition, the plurality of water supply heaters are configured in multiple stages so that the temperature of the water condensed by the condenser rises by sequentially flowing the water condensed by the condenser through the plurality of water supply heaters. There are a plurality of bleed air throttle valves, and they are provided in each stage of the multi-stage feed water heater. Here, the control device adjusts the opening degree of a plurality of bleed air throttle valves to a predetermined amount in the case of normal operation, and when a decrease in the system frequency in the power system is detected, the heating medium supplied to the water supply heating unit is used. When starting the output increase operation, which increases the output of the generator as compared with the case of the normal operation by adjusting the opening degree of the plurality of bleed air throttle valves so as to reduce the flow rate as compared with the case of the normal operation. When at least one of the bleed air throttle valves is closed and the output increasing operation is being executed, the temperature difference between the temperature of the inflowing water and the temperature of the outflowing water in each of the plurality of water supply heaters is calculated. It is determined whether the calculated value of the calculated temperature difference exceeds the preset upper limit value, and if the calculated value exceeds the upper limit value, the water supply heater that exceeds the upper limit value among the multiple bleed air throttle valves. Open the bleed air throttle valve for adjusting the flow rate of the heating medium to the water supply heater located upstream of.

FIG. 1 is a diagram schematically showing a main part of a thermal power plant according to a first embodiment. FIG. 2 is a diagram showing a detailed configuration of a water supply heating unit in the thermal power plant according to the first embodiment. FIG. 3 is a diagram schematically showing the configuration of a bleed air throttle valve in the thermal power plant according to the first embodiment. FIG. 4 is a diagram schematically showing the contents of calculations performed by the control device in the thermal power plant according to the first embodiment. FIG. 5 is a flow chart showing a flow when the “output increasing operation” is executed in the thermal power plant according to the first embodiment. FIG. 6 shows the temperature difference between the inlet temperature and the outlet temperature of the first high-pressure feed water heater and the second high-pressure bleed air throttle when the “output increasing operation” is executed in the thermal power plant according to the first embodiment. It is a figure which shows the relationship with the opening degree of a valve. FIG. 7A is a flow chart showing a flow when the “output increasing operation” is executed in the modified example 1-1 of the first embodiment. FIG. 7B is a flow chart showing a flow when the “output increasing operation” is executed in the modified example 1-1 of the first embodiment. FIG. 7C is a flow chart showing a flow when the “output increasing operation” is executed in the modified example 1-1 of the first embodiment. FIG. 8 is a diagram showing the relationship between the temperature of the high-pressure feed water heater and the opening degree of the high-pressure bleed air throttle valve when the “output increasing operation” is executed in the modified example 1-1 of the first embodiment. .. FIG. 9 is a diagram showing a detailed configuration of a water supply heating unit in the thermal power plant according to the modified example 1-3 of the first embodiment. FIG. 10 is a diagram showing a detailed configuration of a water supply heating unit in the thermal power plant according to the second embodiment. FIG. 11 is a diagram schematically showing the contents of calculations performed by the control device in the thermal power plant according to the second embodiment. FIG. 12 is a diagram schematically showing the configuration of the bleed air throttle valve in the thermal power plant according to the modified example 2-1 of the second embodiment. FIG. 13 is a diagram showing a detailed configuration of a water supply heating unit in the thermal power plant according to the modified example 2-2 of the second embodiment. FIG. 14 is a diagram schematically showing the content of the calculation performed by the control device in the thermal power plant according to the modified example 2-2 of the second embodiment.

<First Embodiment>
The main part of the thermal power plant according to the first embodiment will be described with reference to FIG.

As shown in FIG. 1, in the thermal power generation plant of the present embodiment, the steam F1 (exhaust steam) exhausted from the steam turbine 1 is cooled by the condenser 2 and condensed. The condensed water F2 (condensed water) in the condenser 2 is heated by the water supply heating unit 3. Then, the water F3 (water supply) heated in the water supply heating unit 3 is heated by the boiler 4, and steam F4 (main steam) is generated. The steam F4 generated by the boiler 4 is supplied to the steam turbine 1 as an operating medium. As a result, the steam turbine 1 drives the generator 14 to generate electricity.

In the present embodiment, the thermal power plant is composed of a steam turbine 1, a condenser 2, a water supply heating unit 3, and a boiler 4 so as to constitute a regeneration cycle and a reheat cycle. The details of each part constituting the thermal power plant will be described below in order.

In the present embodiment, the steam turbine 1 is composed of a high-pressure turbine section 11, a medium-pressure turbine section 12, and a low-pressure turbine section 13. The steam turbine 1 drives a generator 14 by rotating a turbine rotor (not shown) in the high-pressure turbine section 11, the medium-pressure turbine section 12, and the low-pressure turbine section 13. The electric power generated by driving the generator 14 is output to the electric power system (not shown).

Specifically, of the steam turbine 1, the high-pressure turbine section 11 is a single-flow type, and steam F4 flows in from the boiler 4 as an operating medium from the supply port A11, and steam B1b flows out from the exhaust port A11b. Here, the steam F4 generated by the boiler 4 is introduced into the high-pressure turbine section 11 via a steam stop valve (not shown) and a steam control valve (not shown). Then, of the steam B1b flowing out from the exhaust port A11b of the high-pressure turbine section 11, most of the steam B1b_1 flows to the boiler 4 and is heated again by the boiler 4. On the other hand, of the steam B1b flowing out from the exhaust port A11b, the remaining steam B1b_2 flows to the water supply heating unit 3. In addition to this, the high-pressure turbine unit 11 is formed with an air extraction port A11a, steam B1a flows out from the air extraction port A11a, and the steam B1a flows to the water supply heating unit 3.

Of the steam turbine 1, in the medium pressure turbine section 12, steam B4 (reheated steam) reheated in the boiler 4 flows in from the supply port A12 as an operating medium, and steam B1d and B12 flow out from the exhaust ports A12b and A12c. do. Here, the steam B4 reheated in the boiler 4 is introduced into the medium pressure turbine section 12 via an intercept valve (not shown). The steam B1d flowing out from the exhaust port A12b of the medium pressure turbine section 12 flows to the water supply heating section 3. Further, the steam B12 flowing out from the exhaust port A12c of the medium pressure turbine section 12 flows to the low pressure turbine section 13. In addition to this, the medium pressure turbine unit 12 is formed with an air extraction port A12a, steam B1c flows out from the air extraction port A12a, and the steam B1c flows to the water supply heating unit 3.

Of the steam turbine 1, the low-pressure turbine section 13 is a double-flow type, and the steam B12 that has flowed in as a working fluid from the supply port A13 branches and flows inside the low-pressure turbine section 13, and the steam F1 flows out from the exhaust port A13c. .. The steam F1 flowing out from the exhaust port A13c flows to the condenser 2. In addition to this, the low pressure turbine section 13 is formed with a plurality of bleed air ports A13a and A13b. In the low-pressure turbine section 13, the steam B1e flowing out from the bleed air port A13a and the steam B1f flowing out from the bleed air port A13b located downstream of the bleed air port A13a flow to the water supply heating section 3.

The condenser 2 is installed to cool and condense the steam F1 discharged from the exhaust port A13c of the low pressure turbine section 13. The condenser 2 cools the steam F1 by using, for example, seawater or the atmosphere as a cooling medium. The water F2 condensed by the condenser 2 is pressurized by the condenser pump P2 and transferred to the water supply heating unit 3.

The water supply heating unit 3 heats the water F2 condensed by the condenser 2 using the steams B1a, B1b_2, B1c, B1d, B1e, and B1f extracted from the steam turbine 1, and the heated water F3 is used in the boiler 4 It is configured to supply to. That is, the thermal power plant of the present embodiment constitutes a regeneration cycle.

The feed water heater 3 includes a plurality of feed water heaters 31 to 35.

In the feed water heater 3 of the present embodiment, the first high-pressure feed water heater 31 (31a, 31b), the second high-pressure feed water heater 32 (32a, 32b), and the third high-pressure feed water heater 33 (33a, 33b) ) Is installed and constitutes a high-pressure feed water heater (high-pressure feed water heater group). Here, the first high-pressure feed water heater 31a, the second high-pressure feed water heater 32a, and the third high-pressure feed water heater 33a are arranged in series. At the same time, the first high-pressure feed water heater 31b, the second high-pressure feed water heater 32b, and the third high-pressure feed water heater 33b are arranged in series. Then, one set composed of a first high-pressure feed water heater 31a, a second high-pressure feed water heater 32a, and a third high-pressure feed water heater 33a, a first high-pressure feed water heater 31b, and a second high-pressure feed water heater 32b. The other set composed of the third high-pressure feed water heater 33b and the third high-pressure feed water heater 33b are arranged in parallel.

Further, in the feed water heater 3, a first low-pressure feed water heater 34 and a second low-pressure feed water heater 35 are installed to form a low-pressure feed water heater (low-pressure feed water heater group).

Each of the feed water heaters 31 to 35 is, for example, a shell-and-tube heat exchanger in which a tube is housed inside the shell.

Further, in the water supply heating unit 3, a deaerator 311 is provided. The deaerator 311 is, for example, a direct contact heat exchanger.

In the feed water heating unit 3, each of the steams B1a, B1b_2, B1c, B1d, B1e, and B1f (bleed air steam) supplied as heating media to each of the plurality of feed water heaters 31 to 35 and the deaerator 311 is condensate. The pressure is gradually increased along the flow of the water F2 condensed in the vessel 2. Then, in the feed water heater 3, the water F2 condensed by the feed water heater 2 is a low pressure feed water heater (second low pressure feed water heater 35, first low pressure feed water heater 34), a deaerator 311 and a high pressure feed water heater. When sequentially flowing through (third high-pressure feed water heater 33, second high-pressure feed water heater 32, and first high-pressure feed water heater 31), it is heated by the heat of steam B1a, B1b_2, B1c, B1d, B1e, B1f. And the temperature rises.

In the high-pressure feed water heater (third high-pressure feed water heater 33, second high-pressure feed water heater 32, and first high-pressure feed water heater 31), the water F311 flowing out of the deaerator 311 branches into two and flows. .. Here, one of the branched waters F311a is heated by flowing through one set composed of a first high-pressure feed water heater 31a, a second high-pressure feed water heater 32a, and a third high-pressure feed water heater 33a. To. Further, the other branched water F311b is heated by flowing through one set composed of a first high-pressure feed water heater 31b, a second high-pressure feed water heater 32b, and a third high-pressure feed water heater 33b. .. As described above, in the feed water heater 3 of the present embodiment, a plurality of feed water heaters 31 to 35 are configured in multiple stages.

Each part constituting the water supply heating part 3 will be described in more detail.

Among the feed water heaters 3, the first high-pressure feed water heaters 31a and 31b include steam B1a supplied from the bleed air port A11a of the high-pressure turbine section 11 and water F32a supplied from the second high-pressure feed water heaters 32a and 32b. Heat exchange is performed with F32b. By this heat exchange, the waters F32a and F32b flowing out from the second high-pressure feed water heaters 32a and 32b are heated by the first high-pressure feed water heaters 31a and 31b. On the other hand, the steam B1a flowing out from the bleed air port A11a of the high-pressure turbine section 11 is cooled and condensed by heat exchange in the first high-pressure feed water heaters 31a and 31b, and is heated as the second high-pressure feed water heater as drain water B31a and B31b. It flows out to the vessels 32a and 32b.

Among the feed water heaters 3, the second high-pressure feed water heaters 32a and 32b include steam B1b_2 supplied from the exhaust port A11b of the high-pressure turbine section 11 and water F33a supplied from the third high-pressure feed water heaters 33a and 33b. Heat exchange is performed with F33b. By this heat exchange, the waters F33a and F33b flowing out from the third high-pressure feed water heaters 33a and 33b are heated by the second high-pressure feed water heaters 32a and 32b. On the other hand, the steam B1b_2 flowing out from the exhaust port A11b of the high-pressure turbine section 11 is cooled and condensed by heat exchange in the second high-pressure feed water heaters 32a and 32b, and is heated as the third high-pressure feed water heater as drain water B32a and B32b. It flows out to the vessels 33a and 33b.

Of the feed water heaters 3, the third high-pressure feed water heaters 33a and 33b are between the steam B1c supplied from the bleed air port A12a of the medium pressure turbine section 12 and the water F311a and F311b supplied from the deaerator 311. In, heat exchange is performed. Due to this heat exchange, the water F311a and F311b flowing out of the deaerator 311 are heated by the third high-pressure feed water heaters 33a and 33b. On the other hand, the steam B1c flowing out from the bleed air port A12a of the medium pressure turbine section 12 is cooled and condensed by heat exchange in the third high-pressure feed water heaters 33a and 33b, and is used as drain water B33a and B33b in the deaerator 311. Outflow to.

Of the feed water heaters 3, the deaerator 311 is heated by mixing steam B1d supplied from the exhaust port A12b of the medium pressure turbine section 12 with water F34 supplied from the first low pressure feed water heater 34. By doing so, the water F34 is degassed. The deaerator 311 is a kind of feed water heater in a broad sense, and removes the gas dissolved in the water F34 supplied from the first low-pressure feed water heater 34 and heats it. The water F311 degassed by the deaerator 311 is pressurized by the feed water pump P311 and then branched, and the branched waters F311a and F311b are transferred to the third high-pressure feed water heaters 33a and 33b.

Among the feed water heaters 3, the first low-pressure feed water heater 34 is between the steam B1e supplied from the bleed air port A13a of the low-pressure turbine section 13 and the water F35 supplied from the second low-pressure feed water heater 35. Heat exchange takes place. By this heat exchange, the water F35 flowing out from the second low-pressure feed water heater 35 is heated. On the other hand, the steam B1e flowing out from the bleed air port A13a of the low-pressure turbine section 13 is cooled and condensed by heat exchange in the first low-pressure feed water heater 34, and flows out to the second low-pressure feed water heater 35 as drain water B34. do.

In the feed water heater 3, the second low-pressure feed water heater 35 includes steam B1f supplied from the extraction port A13b of the low-pressure turbine section 13 and water F2 supplied from the condenser 2 via the condenser pump P2. Heat exchange takes place between them. Due to this heat exchange, the water F2 flowing out of the condenser 2 is heated by the second low-pressure feed water heater 35. On the other hand, the steam B1f flowing out from the bleed air port A13b of the low-pressure turbine section 13 is cooled and condensed by heat exchange in the second low-pressure feed water heater 35, and flows out to the condenser 2 as drain water B35.

Water F3 heated by the water supply heating unit 3 flows into the boiler 4. Here, in the feed water heating unit 3, after the waters F31a and F31b heated by the first high-pressure feed water heaters 31a and 31b are merged, the merged water F3 is supplied as a heated medium. Then, the boiler 4 evaporates by heating the water F3 supplied from the water supply heating unit 3 by using, for example, the combustion exhaust gas generated by combustion. The steam F4 generated in the boiler 4 is supplied to the high-pressure turbine section 11 as a working medium.

In addition to this, in the boiler 4, most of the steam B1b_1 out of the steam B1b flowing out from the exhaust port A11b of the high-pressure turbine section 11 flows in, and the steam B1b_1 is heated again. The steam B4 reheated by the boiler 4 is supplied to the medium pressure turbine section 12 as an operating medium. As described above, the thermal power plant of the present embodiment is composed of a reheat cycle in which steam is reheated by the boiler 4.

The detailed configuration of the water supply heating unit 3 will be described with reference to FIG.

As shown in FIG. 2, the water supply heating unit 3 of the present embodiment is provided with a plurality of bleed air throttle valves V31 to V35. In the present embodiment, the plurality of bleed air throttle valves V31 to V35 are provided in each stage of the multi-stage feed water heaters 31 to 35.

Specifically, the first high-pressure bleed air throttle valve V31 is installed to adjust the flow rate of the steam B1a supplied to the first high-pressure feed water heaters 31a and 31b as a heating medium. The second high-pressure bleed air throttle valve V32 is installed to adjust the flow rate of the steam B1b_2 supplied as a heating medium to the second high-pressure feed water heaters 32a and 32b. The third high-pressure bleed throttle valve V33 is installed to adjust the flow rate of the steam B1c supplied as a heating medium to the third high-pressure feed water heaters 33a and 33b.

At the same time, the first low-pressure bleed throttle valve V34 is installed to adjust the flow rate of the steam B1e supplied to the first low-pressure feed water heater 34 as a heating medium. The second low-pressure bleed throttle valve V35 is installed to adjust the flow rate of the steam B1f supplied to the second low-pressure feed water heater 35 as a heating medium.

The configuration of the bleed air throttle valve will be described with reference to FIG. In FIG. 3, the cross section of the first high-pressure bleeding throttle valve V31 among the plurality of bleeding throttle valves V31 to V35 is schematically shown, but the same applies to the others.

As shown in FIG. 3, the first high-pressure bleed throttle valve V31 is a butterfly valve, and the disc-shaped valve body 310 rotates together with the valve rod 320 inside the tubular valve casing 300 to open and close the valve. It is configured to be done.

Here, the valve rod 320 is installed so as to extend in a direction orthogonal to the pipe axis direction of the valve casing 300. Then, the valve rod 320 is rotated by the drive device 330 with the extending direction of the valve rod 320 as the rotation axis.

The drive device 330 is a hydraulic drive device in which a piston (not shown) is housed inside the cylinder, and the piston moves by controlling the hydraulic pressure inside the cylinder. In the drive device 330, an operation rod connected to the piston is connected to the valve rod 320 via a link member, and the valve body 310 is rotated together with the valve rod 320 in response to the movement of the piston to obtain a first high pressure. It is configured to open and close the bleed air throttle valve V31. That is, in the present embodiment, the first high-pressure bleeding throttle valve V31 is a hydraulic valve, and is configured so that the opening degree is adjusted according to the hydraulic pressure.

In order to fully open the first high-pressure bleeding throttle valve V31, the valve body 310 rotates so that the disk-shaped valve body 310 is along the pipe axis direction of the valve casing 300. As a result, the outer peripheral surface of the valve body 310 and the inner peripheral surface of the valve casing 300 are in the most distant state (the state shown by the solid line in the figure). As a result, steam B1a flows from the inlet 300A to the outlet 300B in the valve casing 300.

On the other hand, when the first high-pressure bleed throttle valve V31 is fully closed, the valve body 310 rotates so that the disk-shaped valve body 310 is orthogonal to the pipe axis direction of the valve casing 300. do. As a result, the outer peripheral surface of the valve body 310 and the inner peripheral surface of the valve casing 300 are in contact with each other (the state shown by the broken line in the figure). As a result, the steam B1a flowing from the inlet 300A to the outlet 300B is cut off in the valve casing 300.

As shown in FIG. 2, in the water supply heating unit 3 of the present embodiment, a plurality of water supply thermometers T31a to T33a, T31b to T33b, T34, T35, T311a, T311b, and T2 are installed.

Specifically, the feed water thermometers T31a and T31b are installed in the flow paths of the waters F31a and F31b flowing out from the first high-pressure feed water heaters 31a and 31b, and measure the temperatures of the waters F31a and F31b. The feed water thermometers T32a and T32b are installed in the flow paths of the waters F32a and F32b flowing out from the second high-pressure feed water heaters 32a and 32b, and measure the temperatures of the waters F32a and F32b. The feed water thermometers T33a and T33b are installed in the flow paths of the waters F33a and F33b flowing out from the third high-pressure feed water heaters 33a and 33b, and measure the temperatures of the waters F33a and F33b.

At the same time, the feed water thermometers T311a and T311b flow the water F311 so as to measure the temperature of the water F311 flowing into the third high-pressure feed water heaters 33a and 33b via the feed water pump P311 after flowing out of the deaerator 311. It is installed on the road.

Further, a feed water thermometer T34 is installed in the flow path of the water F34 so as to measure the temperature of the water F34 flowing out from the first low-pressure feed water heater 34. A feed water thermometer T35 is installed in the flow path of the water F35 so as to measure the temperature of the water F35 flowing out from the second low-pressure feed water heater 35. Further, a feed water thermometer T2 is installed in the flow path of the water F2 so as to measure the temperature of the water F2 flowing into the second low-pressure feed water heater 35 via the condenser pump P2 after flowing out of the condenser 2. ing.

In the present embodiment, each of the plurality of feed water thermometers T31a to T33a, T31b to T33b, T34, T35, T311a, T311b, T2 flows into the feed water heaters 31a to 33a, 31b to 33b, 34, 35, respectively. It is installed to calculate the temperature difference between the inlet temperature of the feed water and the outlet temperature of the outflow water.

Specifically, regarding the temperature difference between the inlet temperature of the water F32a and F32b supplied to the inlet in the first high-pressure feed water heaters 31a and 31b and the outlet temperature of the water F31a and F31b discharged from the outlet, the feed water thermometer It is calculated by performing a difference process obtained by subtracting the temperature detected by the feed water thermometers T32a and T32b from the temperature detected by the T31a and T31b. Regarding the temperature difference between the inlet temperature and the outlet temperature in the second high-pressure feed water heaters 32a and 32b, the difference obtained by subtracting the temperature detected by the feed water thermometers T33a and T33b from the temperature detected by the feed water thermometers T32a and T32b. It is calculated by performing processing. Similarly, regarding the temperature difference between the inlet temperature and the outlet temperature in the third high-pressure feed water heaters 33a and 33b, the temperature detected by the feed water thermometers T311a and T311b is calculated from the temperature detected by the feed water thermometers T33a and T33b. It is calculated by performing the deducted difference processing.

At the same time, regarding the temperature difference between the inlet temperature and the outlet temperature in the first low-pressure feed water heater 34, the difference processing is performed by subtracting the temperature detected by the feed water thermometer T35 from the temperature detected by the feed water thermometer T34. It is calculated by. The temperature difference between the inlet temperature and the outlet temperature in the second low-pressure feed water heater 35 is calculated by subtracting the temperature detected by the feed water thermometer T2 from the temperature detected by the feed water thermometer T35. Will be done.

The thermal power plant of the present embodiment further includes a control device 800. The control device 800 includes an arithmetic unit (not shown) and a memory device (not shown), and the arithmetic unit performs arithmetic processing using a program stored in the memory apparatus to control each part. It is configured.

Here, the control device 800 inputs operation commands, detection data, and the like as input signals. Then, the control device 800 performs arithmetic processing based on the input input signal and outputs the control signal CTL as an output signal to each unit to control the operation of each unit.

The control device 800 adjusts the opening degree of the bleed air throttle valves V31 to V35 to a predetermined amount in the case of normal operation. Then, when the system frequency in the power system rapidly decreases, the control device 800 performs an "output increasing operation" in which the output of the generator 14 is increased more rapidly than in the "normal operation". When the control device 800 executes the “output increasing operation”, the heating medium (steam B1a, B1b_2, B1c, B1e, which is supplied to the water supply heating unit 3 by controlling the operation of the bleed air throttle valves V31 to V35, The flow rate of B1f) is reduced as compared with the case of normal operation.

Although the details will be described later, when the start of the “output increasing operation” is executed, the control device 800 is supplied with water F31a to F33a, F31b from the condenser 2 to the boiler 4 via the water supply heating unit 3. The operation of the bleed air throttle valves V31 to V35 is controlled based on the temperatures of F33b, F34, and F35. That is, the control device 800 adjusts the opening degree of the bleed air throttle valves V31 to V35 according to the temperatures of the waters F31a to F33a, F31b to F33b, F34, and F35 flowing as the heated medium in the water supply heating unit 3.

In the present embodiment, the control device 800 is based on the temperature data obtained by the plurality of feed water thermometers T31a to T33a, T31b to T33b, T34, T35, T311a, T311b, T2, and the feed water heaters 31a to 33a, 31b to At 33b, 34, and 35, the temperature difference between the temperature of the inflowing water and the temperature of the outflowing water is calculated. Then, the control device 800 determines whether or not the calculated value of the temperature difference exceeds the upper limit value set in advance for the temperature difference.

Then, when the calculated value of the temperature difference exceeds the upper limit value, the control device 800 adjusts the opening degree of the bleed air throttle valves V31 to V35. On the other hand, when the calculated value of the temperature difference is not more than the preset upper limit value, the control device 800 maintains the opening degree of the bleed air throttle valves V31 to V35.

The detailed configuration of the control device 800 will be described with reference to FIG. In FIG. 4, the second high-pressure bleed air throttle valve V32 is opened in order to adjust the flow rate of the steam B1b_2 supplied to the second high-pressure feed water heater 32a in the control device 800 when the “output increasing operation” is performed. The part that controls the degree is shown as a typical example.

As shown in FIG. 4, the control device 800 includes a frequency rapid decrease detector 80, a function generator 81, a PID controller 813, and a high price selector 83 (PID; Proportional-Integral-Differential).

As shown in FIG. 4, the frequency rapid decrease detector 80 receives the detection value Sf of the system frequency as an input signal from the outside. The frequency rapid decrease detector 80 obtains a value obtained by subtracting the input detection value Sf of the system frequency from the preset value of the system frequency. Then, when the subtracted value is larger than the threshold value, the frequency rapid decrease detector 80 outputs the output increase command value S0 corresponding to the subtracted value.

As shown in FIG. 4, the function generator 81 receives an output increase command value S0 as an input signal from the frequency rapid decrease detector 80. Then, the function generator 81 outputs the opening command value SV32_0 corresponding to the output increase command value S0 as an output signal. Here, the function generator 81 outputs an opening command value SV32_0 that reduces the opening degree of the second high-pressure bleeding throttle valve V32 according to the output increase command value S0.

As shown in FIG. 4, in the PID controller 813, the calculated value ΔST31a_2 calculated by using the temperature ST31a detected by the water supply thermometer T31a and the temperature ST32a detected by the water supply thermometer T32a is used as an input signal. Entered. Specifically, the temperature difference ΔST31a is obtained by subtracting the temperature ST32a detected by the water supply thermometer T32a from the temperature ST31a detected by the water supply thermometer T31a. This temperature difference ΔST31a is the temperature difference between the temperatures of the waters F32a and F32b supplied to the inlets of the first high-pressure feed water heaters 31a and 31b and the temperatures of the waters F31a and F31b discharged from the outlets. Then, the difference value ΔST31a_1 is obtained by subtracting the temperature difference ΔST31a calculated as described above from the temperature difference upper limit value ΔST_U1 set in advance for the temperature difference. After that, the calculated value ΔST31a_1 is obtained by integrating “-1” into the difference value ΔST31a_1 and inverting the positive and negative. Then, the calculated value ΔST31a_2 obtained is input to the PID controller 813. The PID controller 813 outputs the opening command value SV32_3 corresponding to the calculated value ΔST31a_2 as an output signal.

For example, when the temperature difference upper limit value ΔST_U1 is 20 ° C. and the temperature difference ΔST31a is 22 ° C., the calculated value ΔST31a_2 input to the PID controller 813 is “+ 2 ° C.”. The PID controller 813 outputs an opening command value SV32_3 that increases the opening degree of the second high-pressure bleed air throttle valve V32 according to the calculated value ΔST31a_2.

As shown in FIG. 4, the high value selector 83 inputs the opening command value SV32_0 output by the function generator 81 and the opening command value SV32_3 output by the PID controller 813 as input signals. The high value selector 83 selects the highest value among the opening command value SV32_0 output by the function generator 81 and the opening command value SV32_3 output by the PID controller 813. Then, the high price selector 83 outputs the selected opening command value SV32 to the second high pressure bleed air throttle valve V32 as an output signal.

Although not shown, the control device 800 further adds a PID controller similar to the above PID controller 813 in order to adjust the flow rate of the steam B1b_2 supplied to the second high-pressure feed water heater 32b. I have. Further, in the control device 800, the portion that controls the operation of the bleed air throttle valve other than the second high-pressure bleed air throttle valve V32 is also configured in the same manner as described above.

Hereinafter, the operation of the thermal power plant of the present embodiment will be described separately for the case of performing "normal operation" and the case of performing "output increasing operation".

An example of the operation when performing "normal operation" in the thermal power plant of the present embodiment will be described.

When "normal operation" is performed in the above-mentioned thermal power generation plant, steam F4 is supplied from the boiler 4 to the steam turbine 1 to perform work in the steam turbine 1. In the steam turbine 1, steam F4 is supplied to the high-pressure turbine section 11 as an operating medium to perform work. Then, of the steam B1b exhausted from the high-pressure turbine section 11, most of the steam B1b_1 is reheated by the boiler 4, and then the steam B4 reheated by the boiler 4 is used as an operating medium in the medium-pressure turbine section 12. Be supplied to do the work. After that, the steam B12 discharged from the medium pressure turbine unit 12 is supplied to the low pressure turbine unit 13 as an operating medium to perform work. The steam F1 discharged from the low-pressure turbine section 13 is condensed in the condenser 2, and the water F2 condensed in the condenser 2 is heated in the water supply heating section 3. In the water supply heating unit 3, the water F2 condensed by the condenser 2 is heated by the heat of the steams B1a, B1b_2, B1c, B1d, B1e, and B1f extracted from the steam turbine 1. Then, the water F3 heated in the water supply heating unit 3 is heated by the boiler 4, and the steam F4 is generated by the boiler 4. After that, the steam F4 generated in the boiler 4 is supplied to the steam turbine 1 as a working medium as described above.

In the water supply heating unit 3, the steams B1a, B1b_2, B1c, B1e, and B1f extracted from the steam turbine 1 are supplied as a heating medium via the bleeding throttle valves V31 to V35. In the case of performing "normal operation", in a state where the thermal power plant is operating stably at a constant power generation output (rated output), in order to maintain the maximum power generation efficiency, the control device 800 is a bleed air throttle valve. For example, V31 to V35 are fully opened.

An example of the operation when the "output increase operation" is performed in the thermal power plant of the present embodiment will be described. The "output increasing operation" is performed in order to rapidly increase the output of the generator 14.

An example of the flow when executing the “output increasing operation” will be described with reference to FIGS. 5 and 6.

First, as shown in FIG. 5, a sudden decrease in the system frequency is detected (ST10).

Specifically, when the value obtained by subtracting the set value from the detected value of the system frequency becomes larger than the predetermined threshold value, the output increase command value S0 (see FIG. 4) is output as the operation command of the output increase request. ..

Next, as shown in FIG. 5, the "output increasing operation" is started (ST20).

Here, the control device 800 controls the operation of each unit according to the output increase command value S0, so that the “output increase operation” is started. The "output increasing operation" is an operation of the bleed air throttle valves V31 to V35 so that the flow rate of the heating medium (steam B1a, B1b_2, B1c, B1e, B1f) supplied to the water supply heating unit 3 is reduced as compared with the case of the normal operation. Is started by controlling.

When starting the "output increasing operation", the opening degree is reduced for at least one of the plurality of bleed air throttle valves V31 to V35. In the present embodiment, the opening degree of the second high-pressure bleed throttle valve V32 is changed to a state smaller than that in the fully open state. As a result, the flow rate of the steam B1b_2 supplied to the second high-pressure feed water heaters 32a and 32b as a heating medium is reduced. As a result, the amount of steam that performs expansion work in the medium-pressure turbine section 12 constituting the steam turbine 1 increases, so that the output of the generator 14 can be increased more rapidly than in the case of "normal operation".

Next, as shown in FIG. 5, it is determined whether or not the temperature difference ΔST31a, ΔST31b between the inlet temperature and the outlet temperature of the first high-pressure feed water heaters 31a and 31b exceeds the temperature difference upper limit value ΔST_U1 (ST30). ..

When the flow rate of the steam B1b_2 supplied as a heating medium to the second high-pressure feed water heaters 32a and 32b is reduced as described above for the execution of the "output increasing operation", the water F2 condensed by the condenser 2 is used. In the flow direction, the heat exchange amount is large in the first high-pressure feed water heaters 31a and 31b located downstream of the second high-pressure feed water heaters 32a and 32b. As a result, the temperature difference between the temperatures ST32a and ST32b of the water F32a and F32b supplied to the inlet and the temperatures ST31a and ST31b of the water F31a and F31b discharged from the outlet in the first high-pressure feed water heaters 31a and 31b is ΔST31a and ΔST31b. As the temperature increases, it is more likely that the temperature differences ΔST31a and ΔST31b exceed the preset upper limit of the temperature difference ΔST_U1 (see FIG. 6). Further, in order to increase the amount of heat exchange in the first high-pressure feed water heaters 31a and 31b, the possibility that the flow velocity of the heating medium (bleed air steam) exceeds the limit flow velocity of the pipe increases.

Therefore, in the present embodiment, as described above, the control device performs the difference processing obtained by subtracting the temperatures ST32a and ST32b detected by the feed water thermometers T32a and T32b from the temperatures ST31a and ST31b detected by the feed water thermometers T31a and T31b. By performing 800, the temperature difference ΔST31a, ΔST31b in the first high-pressure feed water heaters 31a and 31b is calculated. Then, the control device 800 performs a comparison process between the temperature difference ΔST31a, ΔST31b in the first high-pressure feed water heaters 31a, 31b and the preset temperature difference upper limit value ΔST_U1. As a result, the control device 800 determines whether or not the temperature difference ΔST31a, ΔST31b in the first high-pressure feed water heaters 31a, 31b exceeds the temperature difference upper limit value ΔST_U1.

As shown in FIG. 5, when the temperature difference ΔST31a, ΔST31b in the first high-pressure feed water heaters 31a, 31b exceeds the temperature difference upper limit value ΔST_U1 (Yes), the opening degree of the second high-pressure bleed air throttle valve V32. (ST41).

Here, the heating medium for the feed water heaters 32a and 32b located upstream of the feed water heaters 31a and 31b, which exceeds the upper limit value in which the opening is smaller than the fully open state due to the start of the "output increasing operation". The control device 800 opens the second high-pressure bleed throttle valve V32 for adjusting. That is, the flow rate of the steam B1b_2 supplied as a heating medium to the second high-pressure feed water heaters 32a and 32b is increased (see FIG. 6).

For example, a difference process is performed by subtracting the temperature difference upper limit value ΔST_U1 from the temperature differences ΔST31a and ΔST31b, and the opening of the second high-pressure bleed air throttle valve V32 is controlled to increase according to the difference value calculated by the difference process. I do.

As a result, the temperature difference ΔST31a, ΔST31b in the first high-pressure feed water heaters 31a, 31b becomes equal to or less than the preset temperature difference upper limit value ΔST_U1.

On the other hand, as shown in FIG. 5, when the temperature difference ΔST31 in the first high-pressure feed water heaters 31a and 31b is equal to or less than the temperature difference upper limit value ΔST_U1 (No), the second high-pressure bleed throttle valve V32 The opening degree is maintained (ST42).

Here, since the opening of the second high-pressure bleed throttle valve V32 is smaller than that in the fully open state by the start of the "output increasing operation", the control device 800 keeps that state. That is, the second high-pressure feed water heaters 32a and 32b are made to hold the flow rate of the steam B1b_2 supplied as a heating medium.

In the above, in order to simplify the explanation, the case where the temperature difference ΔST31a and ΔST31b in each of the two first high-pressure feed water heaters 31a and 31b are the same is illustrated. When the temperature differences ΔST31a and ΔST31b in the two first high-pressure feed water heaters 31a and 31b are different, the larger value of the two temperature differences ΔST31a and ΔST31b is compared with the temperature difference upper limit value ΔST_U1. Then, based on the comparison result, the operation of the second high-pressure bleeding throttle valve V32 is controlled in the same manner as described above.

As described above, in the present embodiment, the temperatures of the waters F31a to F33a, F31b to F33b, F34, and F35 flowing from the condenser 2 to the boiler 4 via the water supply heating unit 3 when the output increasing operation is being executed. The operation of the bleed air throttle valves V31 to V35 is controlled based on the above. Here, the temperature difference between the inlet temperature of the inflowing water and the outlet temperature of the outflowing water in each of the plurality of feed water heaters 31a to 33a, 31b to 33b, 34, 35 constituting the feed water heater 3 is calculated. It is determined whether or not the calculated value of the calculated temperature difference exceeds the preset upper limit value. When the calculated value exceeds the upper limit value, the bleed air throttle valve V32 closed when the output increasing operation is started in the plurality of bleed air throttle valves V31 to V35 (in the present embodiment, the second high-pressure bleed air throttle valve V32). ). As a result, the temperature difference of the feed water heaters (in this embodiment, the first high-pressure feed water heaters 31a and 31b) that exceed the upper limit value becomes the upper limit value or less. Further, the flow velocity of the heating medium supplied to the feed water heater (in this embodiment, the first high-pressure feed water heaters 31a and 31b) can be maintained below the limit flow velocity of the pipe.

The upper limit of the temperature difference between the inlet temperature and the outlet temperature of the feed water heater is set for the protection of the feed water heater. Therefore, in the present embodiment, as described above, the temperature difference between the inlet temperature and the outlet temperature of the feed water heater can be set to the upper limit or less even when the "output increasing operation" is executed. The effect of preventing damage to the heater can be obtained.

In the above embodiment, in order to execute the "output increasing operation", a case where the opening degree of the second high-pressure bleeding throttle valve V32 among the plurality of bleeding throttle valves V31 to V35 is reduced from the fully open state is illustrated. , Not limited to this. A specific modification example will be described below.

(Modification 1-1)
Modification 1-1 will be described with reference to FIGS. 7A, 7B, 7C, and 8. Each of FIGS. 7A to 7C is a flow chart showing a flow when the "output increasing operation" is executed. FIG. 8 is a diagram showing the relationship between the temperature of the high-pressure feed water heater and the opening degree of the high-pressure bleed air throttle valve when the “output increasing operation” is executed.

As shown in FIG. 7A, when the sudden decrease detection of the system frequency is performed (ST10), the “output increase operation” is started (ST20).

When starting the "output increasing operation" in this modification, the opening degree of the first high-pressure bleeding throttle valve V31, the opening degree of the second high-pressure bleeding throttle valve V32, and the third high-pressure bleeding throttle valve V33. Change the opening of to a state smaller than the fully open state.

After starting the "output increasing operation", in this modification, as shown in FIG. 7A, it is determined whether or not the outlet temperature of the first high-pressure feed water heaters 31a and 31b is less than the lower limit of the temperature (ST30a). Here, as shown in FIG. 8, the control device 800 makes the above determination based on the temperature detected by the water supply thermometers T31a and T31b (see FIG. 2).

Then, as shown in FIG. 7A, when the outlet temperature of the first high-pressure feed water heaters 31a and 31b (the temperature detected by the feed water thermometers T31a and T31b) is less than the lower limit of the temperature (Yes), the first Adjustment is made so as to increase the opening degree of the high-pressure bleeding throttle valve V31 (ST41a). As a result, as shown in FIG. 8, the outlet temperature of the first high-pressure feed water heaters 31a and 31b changes from a state of being less than the lower limit of the temperature to a state of being equal to or higher than the lower limit of the temperature.

On the other hand, as shown in FIG. 7A, when the outlet temperature of the first high-pressure feed water heaters 31a and 31b (the temperature detected by the feed water thermometers T31a and T31b) is not less than the lower limit of the temperature (No), the first The opening degree of the high-pressure bleeding throttle valve V31 of 1 is kept smaller than the fully opened state (ST42a).

Further, in this modification, as shown in FIG. 7B, the inlet temperature of the water F32a and F32b supplied to the inlet in the first high-pressure feed water heaters 31a and 31b and the outlet temperature of the water F31a and F31b discharged from the outlet are used. It is determined whether or not the temperature difference ΔST31a and ΔST31b of the above exceeds the preset temperature difference upper limit value ΔST_U1 (ST30b). Here, as shown in FIG. 8, the control device 800 makes the above determination based on the temperature difference ΔST31a, ΔST31b between the temperature detected by the water supply thermometers T31a and T31b and the temperature detected by the water supply thermometers T32a and T32b. (See Fig. 2).

Then, as shown in FIG. 7B, when the temperature difference ΔST31a, ΔST31b in the first high-pressure feed water heaters 31a, 31b exceeds the temperature difference upper limit value ΔST_U1 (Yes), the second high-pressure bleed air throttle valve V32 is opened. Adjust so that the degree increases (ST41b). For example, as shown in FIG. 8, when the temperature difference ΔST31a, ΔST31b in the first high-pressure feed water heaters 31a, 31b exceeds the temperature difference upper limit value ΔST_U1 after increasing the opening degree of the first high-pressure bleed air throttle valve V31. In addition, the opening degree of the second high-pressure bleeding throttle valve V32 is increased. As a result, the temperature difference ΔST31a, ΔST31b in the first high-pressure feed water heaters 31a, 31b becomes the temperature difference upper limit value ΔST_U1 or less from the state where the temperature difference upper limit value ΔST_U1 is exceeded.

On the other hand, as shown in FIG. 7B, when the temperature difference ΔST31a, ΔST31b in the first high-pressure feed water heaters 31a and 31b is equal to or less than the temperature difference upper limit value ΔST_U1, the second high-pressure bleed air throttle valve V32 is opened. The degree is kept smaller than the fully open state (ST42b).

Further, in this modification, as shown in FIG. 7C, the inlet temperature of the waters F33a and F33b supplied to the inlet in the second high-pressure feed water heaters 32a and 32b and the outlet temperature of the waters F32a and F32b discharged from the outlet are used. The control device 800 determines whether or not the temperature difference ΔST32a and ΔST32b of the above exceeds the preset temperature difference upper limit value ΔST_U2 (ST30c). Here, as shown in FIG. 8, the control device 800 makes the above determination based on the temperature difference ΔST32a, ΔST32b between the temperature detected by the water supply thermometers T32a and T32b and the temperature detected by the water supply thermometers T33a and T33b. (See Fig. 2).

Then, as shown in FIG. 7C, when the temperature difference ΔST32a, ΔST32b in the second high-pressure feed water heaters 32a, 32b exceeds the temperature difference upper limit value ΔST_U2 (Yes), the third high-pressure bleed air throttle valve V33 is opened. Adjust so that the degree increases (ST41c). For example, as shown in FIG. 8, when the temperature difference ΔST32a, ΔST32b in the second high-pressure feed water heaters 32a, 32b exceeds the temperature difference upper limit value ΔST_U2 after the opening degree of the second high-pressure bleed air throttle valve V32 is increased. In addition, the opening degree of the third high-pressure bleeding throttle valve V33 is increased. As a result, the temperature difference ΔST32a, ΔST32b in the second high-pressure feed water heaters 32a, 32b becomes the temperature difference upper limit value ΔST_U2 or less from the state where the temperature difference upper limit value ΔST_U2 is exceeded.

On the other hand, as shown in FIG. 7C, when the temperature difference ΔST32a, ΔST32b in the second high-pressure feed water heaters 32a and 32b is equal to or less than the temperature difference upper limit value ΔST_U2, the third high-pressure bleed air throttle valve V33 is opened. The degree is kept smaller than the fully open state (ST42c).

(Modification 1-2)
In the modified example 1-2, when the "output increasing operation" is executed, for example, the opening degree of the second low-pressure bleeding throttle valve V35 is changed to a state smaller than the fully opened state. In this case, there is a high possibility that the amount of heat exchange will increase in the first low-pressure feed water heater 34 located on the downstream side of the second low-pressure feed water heater 35. Therefore, whether or not the temperature difference between the inlet temperature of the water F35 supplied to the inlet and the outlet temperature of the water F34 discharged from the outlet in the first low-pressure feed water heater 34 exceeds a preset upper limit of the temperature difference. Is determined by the control device 800.

When the temperature difference in the first low-pressure feed water heater 34 is equal to or less than the upper limit value of the temperature difference, the opening degree of the second low-pressure bleed air throttle valve V35 is kept smaller than the fully opened state.

On the other hand, when the temperature difference in the first low-pressure feed water heater 34 exceeds the temperature difference upper limit value, the second low-pressure bleed air throttle valve V35 is opened. As a result, the temperature difference between the inlet temperature of the water F35 supplied to the inlet and the outlet temperature of the water F34 discharged from the outlet in the first low-pressure feed water heater 34 becomes equal to or less than a preset upper limit of the temperature difference.

In this modification, when the "output increasing operation" is executed, the flow rate of the heating medium supplied to the second low-pressure feed water heater 35 located on the upstream side of the deaerator 311 is "normal operation". It is less than the case of. Therefore, in the present embodiment, it is possible to effectively prevent the temperature (water supply temperature) of the water F34 flowing into the deaerator 311 from decreasing and flooding in the deaerator 311.

(Modification 1-3)
The detailed configuration of the water supply heating unit 3 according to the modified example 1-3 will be described with reference to FIG.

In the water supply heating unit 3 of this modification, unlike the case of the above embodiment, as shown in FIG. 9, the first high-pressure bleed air throttle valve V31, the second high-pressure bleed air throttle valve V32, and the third high-pressure bleed air throttle valve V31. Each of the bleed air throttle valves V33 is two.

Specifically, the one first high-pressure bleeding throttle valve V31a is installed to adjust the flow rate of the steam B1a supplied as a heating medium to the one first high-pressure feed water heater 31a. The other first high-pressure bleed throttle valve V31b is installed to adjust the flow rate of the steam B1a supplied as a heating medium to the other first high-pressure feed water heater 31b. One second high-pressure bleed throttle valve V32a is installed to adjust the flow rate of steam B1b_2 supplied as a heating medium to one second high-pressure feed water heater 32a. The other second high-pressure bleed throttle valve V32b is installed to adjust the flow rate of the steam B1b_2 supplied as a heating medium to the other second high-pressure feed water heater 32b. One third high-pressure bleed throttle valve V33a is installed to adjust the flow rate of steam B1c supplied as a heating medium to one third high-pressure feed water heater 33a. The other third high-pressure bleed throttle valve V33b is installed to adjust the flow rate of the steam B1c supplied as a heating medium to the other third high-pressure feed water heater 33b.

In this modification, when the "output increasing operation" is executed, for example, the opening degree of the second high-pressure bleeding throttle valve V32b is changed to a state smaller than the fully opened state.

In this case, there is a high possibility that the amount of heat exchange will increase in the first high-pressure feed water heater 31b located on the downstream side of the second high-pressure feed water heater 32b. Therefore, whether or not the temperature difference between the inlet temperature of the water F32b supplied to the inlet and the outlet temperature of the water F31b discharged from the outlet in the first high-pressure feed water heater 31b exceeds a preset upper limit of the temperature difference. Is determined by the control device 800.

When the temperature difference in the first high-pressure feed water heater 31b is equal to or less than the upper limit of the temperature difference, the opening degree of the second high-pressure bleed throttle valve V32b is kept smaller than the fully opened state.

On the other hand, when the temperature difference in the first high-pressure feed water heater 31b exceeds the temperature difference upper limit value, the opening degree of the second high-pressure bleed air throttle valve V32b is increased. As a result, the temperature difference in the first high-pressure feed water heater 31b becomes equal to or less than the preset upper limit value of the temperature difference.

(others)
In the above, the first high-pressure feed water heater 31 (31a, 31b), the second high-pressure feed water heater 32 (32a, 32b), the third high-pressure feed water heater 33 (33a, 33b), the first low-pressure feed water heater 34. , And the case where the second low-pressure feed water heater 35 is provided as the feed water heater by the feed water heater 3 has been described, but the present invention is not limited to this. The number of feed water heaters may be changed as appropriate to a number other than the above-mentioned number.

<Second Embodiment>
The main part of the thermal power plant according to the second embodiment will be described with reference to FIG. As shown in FIG. 10, the present embodiment is the same as the first embodiment described above except for a part of the configuration, and therefore the description of the overlapping portion will be omitted as appropriate.

As shown in FIG. 10, the water supply heating unit 3 of the present embodiment is provided with a plurality of bleed air throttle valves V31 to V35 as in the case of the first embodiment.

The feed water heaters 31a to 33a, 31b to 33b, 34, 35 are, for example, shell and tube heat exchangers. In the feed water heaters 31a to 33a, 31b to 33b, 34, 35, the steam B1a, B1b_2, B1c, B1e, B1f extracted from the steam turbine 1 was supplied to the shell as a heating medium and condensed in the condenser 2. Water F2 is supplied to the tube as a heated medium, and heat exchange is performed between the heated medium and the heated medium. The water F2 is heated by the heat exchange performed in the water supply heating unit 3. Then, the steams B1a, B1b_2, B1c, B1e, and B1f extracted from the steam turbine 1 are cooled and condensed by the heat exchange performed in the water supply heating unit 3, and are converted into drain water.

As shown in FIG. 10, a plurality of drain water thermometers X31a to X33a, X31b to X33b, X34, and X35 (internal thermometers) are installed in the water supply heating unit 3 of the present embodiment. At the same time, a plurality of pressure gauges P31a to P33a, P31b to P33b, P34, and P35 (internal pressure gauges) are installed in the water supply heating unit 3.

Specifically, drain water thermometers X31a and X31b are installed so as to measure the temperature of the drain water existing inside the shell to which the steam B1a is supplied as a heating medium in the first high-pressure feed water heaters 31a and 31b. At the same time, thermometers P31a and P31b are installed so as to measure the pressure inside the shells of the first high-pressure feed water heaters 31a and 31b. Drain water thermometers X32a and X32b are installed and a second high-pressure feed water heater 32a and 32b so as to measure the temperature of the drain water existing inside the shell to which the steam B1b_2 is supplied as a heating medium. 2 Thermometers P32a and P32b are installed so as to measure the pressure inside the shells of the high-pressure feed water heaters 32a and 32b. Drain water thermometers X33a and X33b are installed so as to measure the temperature of the drain water existing inside the shell to which the steam B1c is supplied as a heating medium in the third high-pressure feed water heaters 33a and 33b. 3 Thermometers P33a and P33b are installed so as to measure the pressure inside the shells of the high-pressure feed water heaters 33a and 33b.

At the same time, a drain water thermometer X34 is installed so as to measure the temperature of the drain water existing inside the shell in which the steam B1e is supplied as a heating medium in the first low-pressure feed water heater 34, and the first. A thermometer P34 is installed so as to measure the pressure inside the shell of the low-pressure feed water heater 34. A drain water thermometer X35 is installed so as to measure the temperature of the drain water existing inside the shell to which the steam B1f is supplied as a heating medium in the second low-pressure feed water heater 35, and the second low-pressure feed water heater is heated. A thermometer P35 is installed so as to measure the pressure inside the shell of the vessel 35.

In the present embodiment, the drain water thermometers X31a to X33a, X31b to X33b, X34, X35 and the pressure gauges P31a to P33a, P31b to P33b, P34, P35 are feed water heaters 31a to 33a, 31b to 33b, 34, 35. It is installed to monitor the occurrence of a drain flush where the drain water generated inside the is turned into steam.

Similar to the case of the first embodiment, the control device 800 controls the operation of the bleed air throttle valves V31 to V35 when the "output increasing operation" is executed, so that the heating supplied to the water supply heating unit 3 is performed. The flow rate of the medium is reduced as compared with the case of normal operation. In order to reduce the flow rate of the heating medium, the bleed air throttle valves V31 to V35 should be adjusted in a range where the temperature of the drain water inside the water supply heating unit 3 to which the heating medium is supplied is lower than the saturation temperature of the heating medium. The procedure created in advance based on the past knowledge as to how much the bleed air throttle valves V31 to V35 should be opened after the output increase operation is started is memorized, and the bleed air throttle is squeezed by this predetermined procedure. The opening degree of the valves V31 to V35 is adjusted.

Although the details will be described later, when the "output increasing operation" is being executed, the control device 800 is based on the temperature of the drain water inside the water supply heating unit 3 to which the heating medium is supplied and the pressure inside the water supply heating unit 3. The operation of the bleed air throttle valves V31 to V35 is controlled. That is, the control device 800 is based on the temperature data obtained by the drain water thermometers X31a to X33a, X31b to X33b, X34, and X35, and the pressure data obtained by the pressure gauges P31a to P33a, P31b to P33b, P34, and P35. Then, the opening degree of the bleed air throttle valves V31 to V35 is adjusted.

The detailed configuration of the control device 800 will be described with reference to FIG. In FIG. 11, the second high-pressure bleed air throttle valve V32 is opened in order to adjust the flow rate of the steam B1b_2 supplied to the second high-pressure feed water heater 32a in the control device 800 when the “output increasing operation” is performed. The part that controls the degree is shown as a typical example.

As shown in FIG. 11, the control device 800 includes a frequency rapid decrease detector 80, a steam table T80, a function generator 81, a PID controller 815, and a high price selector 83.

As shown in FIG. 11, in the frequency rapid decrease detector 80, the detection value Sf of the system frequency is input as an input signal from the outside. The frequency rapid decrease detector 80 obtains a value obtained by subtracting the input detection value Sf of the system frequency from the preset value of the system frequency. Then, when the subtracted value is larger than the threshold value, the frequency rapid decrease detector 80 outputs the output increase command value S0 corresponding to the subtracted value.

As shown in FIG. 11, the function generator 81 receives an output increase command value S0 as an input signal from the frequency rapid decrease detector 80. Then, the function generator 81 outputs the opening command value SV32_0 corresponding to the output increase command value S0 as an output signal. Here, the function generator 81 outputs an opening command value SV32_0 that reduces the opening degree of the second high-pressure bleeding throttle valve V32 according to the output increase command value S0.

As shown in FIG. 11, the PID controller 815 inputs the calculated value ΔSC32a calculated by using the temperature SX32a detected by the drain water thermometer X32a and the pressure SP32a detected by the pressure gauge P32a as an input signal. Will be done. Specifically, the saturated steam temperature SS32a corresponding to the pressure SP32a detected by the pressure gauge P32a is obtained by using the steam table T80 composed of a look-up table or the like. Then, the temperature difference ΔSX32a is obtained by subtracting the temperature SX32a detected by the drain water thermometer X32a from the obtained saturated steam temperature SS32a. Then, the calculated value ΔSC32a is obtained by subtracting the temperature difference ΔSX32a calculated as described above from the temperature difference lower limit value ΔSC_L2 (subcool temperature lower limit value) set in advance for the temperature difference. Then, the calculated value ΔSC32a obtained is input to the PID controller 815. The PID controller 815 outputs the opening command value SV32_5 corresponding to the calculated value ΔSC32a as an output signal.

For example, when the temperature difference lower limit SC_L2 (subcool temperature lower limit) is 5 ° C. and the temperature difference ΔSX32a is 3 ° C., the calculated value ΔSC32a input to the PID controller 815 is “+ 2 ° C.”. Become. The PID controller 815 outputs an opening command value SV32_5 that increases the opening degree of the second high-pressure bleeding throttle valve V32 according to the calculated value ΔSC32a.

As shown in FIG. 11, the high value selector 83 inputs the opening command value SV32_0 output by the function generator 81 and the opening command value SV32_5 output by the PID controller 815 as input signals. The high value selector 83 selects the highest value among the opening command value SV32_0 output by the function generator 81 and the opening command value SV32_5 output by the PID controller 815. Then, the high price selector 83 outputs the selected opening command value SV32 to the second high pressure bleed air throttle valve V32 as an output signal.

Although not shown, the control device 800 further adds a PID controller similar to the above PID controller 815 in order to adjust the flow rate of the steam B1b_2 supplied to the second high-pressure feed water heater 32b. I have. Further, in the control device 800, the portion that controls the operation of the bleed air throttle valve other than the second high-pressure bleed air throttle valve V32 is also configured in the same manner as described above.

In this embodiment, an example of the operation when the above-mentioned "output increasing operation" is executed will be described.

When the sudden decrease in the system frequency is detected in the present embodiment, the control device 800 has, for example, about the first high-pressure bleed throttle valve V31, the second high-pressure bleed throttle valve V32, and the third high-pressure bleed throttle valve V33, respectively. , Reduce the opening. Here, all the openings of the first high-pressure bleed throttle valve V31, the second high-pressure bleed throttle valve V32, and the third high-pressure bleed throttle valve V33 are fully opened from the fully open state (K = Kmax = 100%). The opening is changed to a predetermined opening (K = Kx (for example, Kx = 10%)) larger than the closed state. For example, the opening changes to a predetermined opening within 0.5 seconds from the time when the sudden decrease in the system frequency is detected. As a result, the flow rate of the heating medium supplied to the first high-pressure feed water heaters 31a, 31b, the second high-pressure feed water heaters 32a, 32b, and the third high-pressure feed water heaters 33a, 33b is "output increase operation". It is narrowed down from the state before execution of.

As described above, when the "output increasing operation" is being executed, the amount of steam that performs expansion work in the steam turbine 1 increases, so that the output of the generator 14 increases more rapidly than in the case of the "normal operation". Can be made to.

When the "output increasing operation" is being executed, the internal pressure to which the heating medium is supplied in the first high-pressure feed water heaters 31a and 31b increases as the opening degree of the first high-pressure bleed throttle valve V31 decreases. descend. After that, as the opening degree of the first high-pressure bleeding throttle valve V31 increases, the internal pressure to which the heating medium is supplied in the first high-pressure feed water heaters 31a and 31b increases. In this way, when the "output increasing operation" is being executed, the internal pressure to which the heating medium is supplied in the first high-pressure feed water heaters 31a and 31b fluctuates. Inside the first high-pressure feed water heaters 31a and 31b, the saturation temperature of the heating medium also fluctuates as the pressure fluctuates. The temperature inside the first high-pressure feed water heater 31a and 31b to which the heating medium is supplied fluctuates so as to be lower than the saturation temperature of the heating medium. Therefore, drain flush does not occur in the first high-pressure feed water heaters 31a and 31b.

Similarly, in each of the second high-pressure feed water heaters 32a and 32b and the third high-pressure feed water heaters 33a and 33b, the internal pressure to which the heating medium is supplied fluctuates. Along with this, the saturation temperature of the heating medium also fluctuates, but the internal temperature to which the heating medium is supplied fluctuates so as to be lower than the saturation temperature of the heating medium. Therefore, the drain flush does not occur in the second high-pressure feed water heaters 32a and 32b and the third high-pressure feed water heaters 33a and 33b.

Further, in the present embodiment, when the "output increasing operation" is being executed, the first high-pressure feed water heaters 31a, 31b, the second high-pressure feed water heaters 32a, 32b, and the third high-pressure feed water heaters 33a, 33b The control device 800 controls the operation of the bleed air throttle valves V31 to V33 based on the measured temperature of the drain water and the internal pressure. Here, in the first high-pressure feed water heaters 31a, 31b, the second high-pressure feed water heaters 32a, 32b, and the third high-pressure feed water heaters 33a, 33b, the temperature of the drain water is kept lower than the saturation temperature. In addition, the control device 800 controls the operation of the bleed air throttle valves V31 to V33.

Specifically, the pressure measurement measured about the internal pressure to which the heating medium is supplied in the first high-pressure feed water heaters 31a, 31b, the second high-pressure feed water heaters 32a, 32b, and the third high-pressure feed water heaters 33a, 33b. The saturation temperature of the heating medium is calculated from the value. Then, the temperature of the drain water existing inside the first high-pressure feed water heaters 31a, 31b, the second high-pressure feed water heaters 32a, 32b, and the third high-pressure feed water heaters 33a, 33b is saturated as described above. The temperature difference is calculated by subtracting from the temperature. Then, the high-pressure bleed throttle valves V31, V32, according to the calculated value obtained by subtracting the temperature difference calculated as described above from the temperature difference lower limit values ΔSC_L1 to ΔSC_L3 (subcool temperature lower limit value) set in advance for the temperature difference. The opening degree of V33 is controlled.

Then, the high-pressure bleed throttle valves V31, V32, according to the calculated value obtained by subtracting the temperature difference calculated as described above from the temperature difference lower limit values ΔSC_L1 to ΔSC_L3 (subcool temperature lower limit value) set in advance for the temperature difference. The opening degree of V33 is controlled. Here, the opening degree is increased according to the calculated value. As a result, the internal pressure to which the heating medium is supplied in the first high-pressure feed water heaters 31a, 31b, the second high-pressure feed water heaters 32a, 32b, and the third high-pressure feed water heaters 33a, 33b rises, and the pressure rises. As a result, the saturation temperature rises. As a result, it is possible to prevent the occurrence of drain flash.

As described above, in the present embodiment, it is predetermined that the temperature inside the water supply heating unit 3 to which the heating medium is supplied is lower than the saturation temperature of the heating medium when the output increasing operation is performed. In the procedure, the opening degree of the bleed air throttle valves V31 to V35 is adjusted. At the same time, in the present embodiment, when the output increasing operation is being executed, the temperature data of the drain water existing inside the water supply heating unit 3 to which the heating medium is supplied, the pressure data inside the drain water, and the lower limit of the subcool temperature. The operation of the bleed air throttle valves V31 to V35 is controlled based on the value calculated using the value. Here, the internal pressure of the water supply heating unit 3 is detected, the temperature of the drain water existing at the location where the heating medium is supplied in the water supply heating unit 3, is detected, and the saturation temperature of the heating medium is determined based on the internal pressure. The operation of the bleed air throttle valves V31 to V35 is controlled so that the temperature of the obtained and detected drain water becomes lower than the obtained saturated temperature.

Therefore, in the present embodiment, as described above, it is possible to effectively prevent the drain flush from occurring inside the heating medium being supplied in the water supply heating unit 3. In addition, it is easy to increase the output rapidly, and the plant operation can be stabilized.

A modified example of the second embodiment will be described.

(Modification 2-1)
The modified example 2-1 of the second embodiment will be described with reference to FIG. In FIG. 12, the cross section of the first high-pressure bleeding throttle valve V31 among the plurality of bleeding throttle valves V31 to V35 is schematically shown, but the same applies to the others.

In the present embodiment, it is preferable that the first high-pressure bleeding throttle valve V31 is provided with a stopper 310S as shown in FIG. Here, the stopper 310S is installed at a position that prevents the opening degree of the first high-pressure bleeding throttle valve V31 from being fully closed. Here, the stopper 310S is installed at a position where the disc-shaped valve body 310 comes into contact with the stopper 310S when the opening degree of the first high-pressure bleeding throttle valve V31 is reduced when a sudden decrease in the system frequency is detected.

Specifically, when the first high-pressure bleeding throttle valve V31 is closed, the valve body 310 comes into contact with the stopper 310S before the valve body 310 becomes orthogonal to the pipe axis direction of the valve casing 300. As a result, the steam B1a flowing from the inlet 300A to the outlet 300B in the valve casing 300 as a heating medium is not completely shut off, and the steam B1a is supplied to the first high-pressure feed water heaters 31a and 31b as a heating medium.

When the first high-pressure bleed throttle valve V31 is fully closed, the internal pressure to which the heating medium is supplied in the first high-pressure feed water heaters 31a and 31b drops sharply, so that a drain flush may occur. The sex increases. However, in this modification, since the opening degree of the first high-pressure bleeding throttle valve V31 is not fully closed, the opening degree of the first high-pressure bleeding throttle valve V31 is reduced when a sudden decrease in the system frequency is detected. Even so, it is possible to prevent the internal pressure to which the heating medium is supplied in the first high-pressure feed water heaters 31a and 31b from dropping sharply. As a result, in this modification, the occurrence of drain flash can be prevented more effectively.

(Modification 2-2)
A modification 2-2 of the second embodiment will be described with reference to FIG.

FIG. 13 schematically shows the detailed configuration of the water supply heating unit 3. FIG. 13 shows a high-pressure feed water heater (high-pressure feed water heater group) among the feed water heaters 3.

As shown in FIG. 13, in the water supply heating unit 3 of this modification, unlike the case of the second embodiment described above, a plurality of flow meters FT31 to FT33, a plurality of level meters LT31a to LT33a, LT31b to LT33b, and , A plurality of water supply thermometers T31a to T33a and T31b to T33b are further installed.

Specifically, as shown in FIG. 13, the flow meter FT 31 is installed to measure the flow rate of the steam B1a supplied as a heating medium to the first high-pressure feed water heaters 31a and 31b. The flow meter FT 32 is installed to measure the flow rate of the steam B1b_2 supplied as a heating medium to the second high-pressure feed water heaters 32a and 32b. The flow meter FT 33 is installed to measure the flow rate of the steam B1c supplied as a heating medium to the third high-pressure feed water heaters 33a and 33b.

As shown in FIG. 13, the level meters LT31a and LT31b are installed to measure the water level of the drain water existing inside the first high-pressure feed water heaters 31a and 31b. The level meters LT32a and LT32b are installed to measure the water level of the drain water existing inside the second high-pressure feed water heaters 32a and 32b. The level meters LT33a and LT33b are installed to measure the water level of the drain water existing inside the third high-pressure feed water heaters 33a and 33b.

As shown in FIG. 13, the feed water thermometers T31a and T31b are installed in the flow path of the water F31a and F31b flowing out from the first high-pressure feed water heaters 31a and 31b, and measure the temperature of the water F31a and F31b. .. The feed water thermometers T32a and T32b are installed in the flow paths of the waters F32a and F32b flowing out from the second high-pressure feed water heaters 32a and 32b, and measure the temperatures of the waters F32a and F32b. The feed water thermometers T33a and T33b are installed in the flow paths of the waters F33a and F33b flowing out from the third high-pressure feed water heaters 33a and 33b, and measure the temperatures of the waters F33a and F33b.

When the control device 800 is executing the "output increasing operation", the flow rate data obtained by the flow rate meters FT31 to FT33, the water level data obtained by the level meters LT31a to LT33a, the LT31b to LT33b, and the water supply thermometer The opening degree of the bleed air throttle valves V31 to V33 is adjusted based on the temperature data obtained by T31a to T33a and T31b to T33b. That is, the control device 800 further covers the flow rate of steam supplied as a heating medium to the water supply heating unit 3, the water level of the drain water existing inside the water supply heating unit 3 to which the heating medium is supplied, and the water supply heating unit 3. The opening degree of the bleed air throttle valves V31 to V33 is adjusted based on the temperature of the water flowing as the heating medium.

The detailed configuration of the control device 800 of this modification will be described with reference to FIG. In FIG. 14, the second high-pressure bleed air throttle valve V32 is opened in order to adjust the flow rate of the steam B1b_2 supplied to the second high-pressure feed water heater 32a in the control device 800 when the “output increasing operation” is performed. The part that controls the degree is shown as a typical example.

As shown in FIG. 14, the control device 800 includes a frequency sudden decrease detector 80, a steam table T80, a function generator 81, PID controllers 811 to 815, a low value selector 82, and a high value selector 83. ..

As shown in FIG. 14, the frequency rapid decrease detector 80 receives the detection value Sf of the system frequency as an input signal from the outside. The frequency rapid decrease detector 80 obtains a value obtained by subtracting the input detection value Sf of the system frequency from the preset value of the system frequency. Then, when the subtracted value is larger than the threshold value, the frequency rapid decrease detector 80 outputs the output increase command value S0 corresponding to the subtracted value.

As shown in FIG. 14, the function generator 81 receives an output increase command value S0 as an input signal from the frequency rapid decrease detector 80. Then, the function generator 81 outputs the opening command value SV32_0 corresponding to the output increase command value S0 as an output signal. Here, the function generator 81 outputs an opening command value SV32_0 that reduces the opening degree of the second high-pressure bleeding throttle valve V32 according to the output increase command value S0.

As shown in FIG. 14, the PID controller 811 inputs the calculated value ΔSFT32 calculated by using the flow rate SFT32 measured by the flow meter FT32 as an input signal. Specifically, by subtracting the flow rate SFT32 measured by the flow meter FT32 from the preset flow rate upper limit value SFT_U (value determined by designing the bleed air pipe or feed water heater plus a margin), The calculated value ΔSFT32 is obtained. Then, the calculated value ΔSFT32 obtained is input to the PID controller 811. The PID controller 811 outputs the opening command value SV32_1 corresponding to the calculated value ΔSFT32 as an output signal.

For example, when the flow rate upper limit value SFT_U is 50 kg / s and the measured flow rate SFT32 is 55 kg / s, the calculated value ΔSFT32 input to the PID controller 811 is “-5 kg / s”. .. The PID controller 811 outputs an opening command value SV32_1 that reduces the opening degree of the second high-pressure bleeding throttle valve V32 according to the calculated value ΔSFT32.

As shown in FIG. 14, the PID controller 812 inputs the calculated value ΔSLT32a_U calculated using the water level SLT32a measured by the level meter LT32a as an input signal. Specifically, the calculated value ΔSLT32a_U is obtained by subtracting the water level SLT32a measured by the level meter LT32a from the preset water level upper limit value SLT_U (value determined by the device design plus a margin). Be done. Then, the calculated value ΔSLT32a_U obtained is input to the PID controller 812. The PID controller 812 outputs the opening command value SV32_2 corresponding to the calculated value ΔSLT32a_U as an output signal.

For example, when the water level upper limit value SLT_U is "+10 mm" and the measured water level SLT32a is "+12 mm", the calculated value ΔSLT32a_U input to the PID controller 812 is "-2 mm". The PID controller 812 outputs an opening command value SV32_2 that reduces the opening degree of the second high-pressure bleed air throttle valve V32 according to the calculated value ΔSLT32a_U.

As shown in FIG. 14, in the PID controller 813, the calculated value ΔST31a_2 calculated by using the temperature ST31a detected by the water supply thermometer T31a and the temperature ST32a detected by the water supply thermometer T32a is used as an input signal. Entered. Specifically, the temperature difference ΔST31a is obtained by subtracting the temperature ST32a detected by the water supply thermometer T32a from the temperature ST31a detected by the water supply thermometer T31a. This temperature difference ΔST31a is the temperature difference between the temperature of the water F32a supplied to the inlet and the temperature of the water F31a discharged from the outlet in the first high-pressure feed water heater 31a. Then, the difference value ΔST31a_1 is obtained by subtracting the temperature difference ΔST31a calculated as described above from the temperature difference upper limit value ΔST_U1 (value determined from the design of the device plus the margin) set in advance for the temperature difference. Is required. After that, the calculated value ΔST31a_1 is obtained by integrating “-1” into the difference value ΔST31a_1 and inverting the positive and negative. Then, the calculated value ΔST31a_2 obtained is input to the PID controller 813. The PID controller 813 outputs the opening command value SV32_3 corresponding to the calculated value ΔST31a_2 as an output signal.

For example, when the temperature difference upper limit value ΔST_U1 is 20 ° C. and the temperature difference ΔST31a is 22 ° C., the calculated value ΔST31a_2 input to the PID controller 813 is “+ 2 ° C.”. The PID controller 813 outputs an opening command value SV32_3 that increases the opening degree of the second high-pressure bleed air throttle valve V32 according to the calculated value ΔST31a_2.

As shown in FIG. 14, the PID controller 814 inputs the calculated value ΔSLT32a_L calculated using the water level SLT32a measured by the level meter LT32a as an input signal. Specifically, the calculated value ΔSLT32a_L is obtained by subtracting the water level SLT32a measured by the level meter LT32a from the preset lower limit water level SLT_L (value determined by the device design plus a margin). Be done. Then, the calculated value ΔSLT32a_L obtained is input to the PID controller 814. The PID controller 814 outputs the opening command value SV32_4 corresponding to the calculated value ΔSLT32a_L as an output signal.

For example, when the water level lower limit value SLT_L is "-10 mm" and the measured water level SLT32a is "-12 mm", the calculated value ΔSLT32a_L input to the PID controller 814 is "+2 mm". The PID controller 814 outputs an opening command value SV32_4 that increases the opening degree of the second high-pressure bleed air throttle valve V32 according to the calculated value ΔSLT32a_L.

As shown in FIG. 14, the PID controller 815 inputs the calculated value ΔSC32a calculated by using the temperature SX32a detected by the drain water thermometer X32a and the pressure SP32a detected by the pressure gauge P32a as an input signal. Will be done. Specifically, the saturated steam temperature SS32a corresponding to the pressure SP32a detected by the pressure gauge P32a is obtained by using the steam table T80 composed of a look-up table or the like. Then, the temperature difference ΔSX32a is obtained by subtracting the temperature SX32a detected by the drain water thermometer X32a from the obtained saturated steam temperature SS32a. Then, the calculated value ΔSC32a is obtained by subtracting the temperature difference ΔSX32a calculated as described above from the temperature difference lower limit value ΔSC_L2 (subcool temperature lower limit value) set in advance for the temperature difference. Then, the calculated value ΔSC32a obtained is input to the PID controller 815. The PID controller 815 outputs the opening command value SV32_5 corresponding to the calculated value ΔSC32a as an output signal.

For example, when the temperature difference lower limit value ΔSC_L2 (subcool temperature lower limit value) is 5 ° C. and the temperature difference ΔSX32a is 3 ° C., the calculated value ΔSC32a input to the PID controller 815 is “+ 2 ° C.”. Become. The PID controller 815 outputs an opening command value SV32_5 that increases the opening degree of the second high-pressure bleeding throttle valve V32 according to the calculated value ΔSC32a.

As shown in FIG. 14, the low value selector 82 has an opening command value SV32_0 output by the function generator 81, an opening command value SV32_1 output by the PID controller 811 and an opening command output by the PID controller 812. The value SV32_2 is input as an input signal. The low value selector 82 is the lowest of the opening command value SV32_0 output by the function generator 81, the opening command value SV32_1 output by the PID controller 811 and the opening command value SV32_1 output by the PID controller 812. Select a value. Then, the low value selector 82 outputs the selected opening command value SV32L to the high value selector 83 as an output signal.

As shown in FIG. 14, the high value selector 83 has an opening command value SV32L output by the low value selector 82, an opening command value SV32_3 output by the PID controller 813, and an opening command value output by the PID controller 814. The degree command value SV32_4 and the opening command value SV32_5 output by the PID controller 815 are input as input signals. The high value selector 83 includes an opening command value SV32L output by the low value selector 82, an opening command value SV32_3 output by the PID controller 813, an opening command value SV32_4 output by the PID controller 814, and a PID. The highest value among the opening command values SV32_5 output by the controller 815 is selected. Then, the high price selector 83 outputs the selected opening command value SV32 to the second high pressure bleed air throttle valve V32 as an output signal.

Although not shown, the controller 800 is a PID controller similar to the above PID controllers 811 to 815 in order to adjust the flow rate of the steam B1b_2 supplied to the second high-pressure feed water heater 32b. Is further equipped. Further, in the control device 800, the portion that controls the operation of the bleed air throttle valve other than the second high-pressure bleed air throttle valve V32 is also configured in the same manner as described above.

In this modification, an example of the operation when the above-mentioned "output increasing operation" is executed will be described.

In this modification, when the "output increasing operation" is being executed, the temperature of the drain water and the internal pressure measured by the feed water heaters 31a to 33a and 31b to 33b are the same as in the case of the second embodiment described above. The control device 800 controls the operation of the bleed air throttle valves V31 to V33 based on the above. Therefore, it is possible to effectively prevent the drain flush from occurring in the water supply heating unit 3.

Then, in this modification, unlike the case of the second embodiment described above, the control device 800 controls the operation of the bleed air throttle valves V31 to V33 based on the flow rate data obtained by the flow rate meters FT31 to FT33. Here, the flow rates of the steams B1a, B1b_2, B1c (bleed air steam) supplied as a heating medium to the feed water heaters 31a to 33a, 31b to 33b are set in advance based on the flow rate data obtained by the flow meters FT31 to FT33. The control device 800 determines whether or not it is equal to or less than the upper limit value. When the flow rate exceeds the upper limit value, the control device 800 closes the opening degree of the bleed air throttle valves V31 to V33. On the other hand, when the flow rate is not more than the upper limit value, the control device 800 keeps the opening degree of the bleed air throttle valves V31 to V33. Therefore, the flow rate of the steam B1a, B1b_2, B1c (bleed air steam) supplied as a heating medium to the feed water heaters 31a to 33a, 31b to 33b can be adjusted to the upper limit or less.

Further, in this modification, unlike the case of the second embodiment described above, the operation of the bleed air throttle valves V31 to V33 is controlled based on the water level data obtained by the level meters LT31a to LT33a and LT31b to LT33b. Here, based on the water level data obtained by the level meters LT31a to LT33a and LT31b to LT33b, the water levels of the drain water existing inside the feed water heaters 31a to 33a and 31b to 33b are preset upper limit values and lower limit values. The control device 800 determines whether or not it is within the range of. When the water level of the drain water exceeds the upper limit value, the control device 800 closes the opening degree of the bleed air throttle valves V31 to V33. When the water level of the drain water is less than the lower limit value, the control device 800 opens the opening degree of the bleed air throttle valves V31 to V33. On the other hand, when the water level of the drain water is within the range of the upper limit value and the lower limit value, the control device 800 maintains the opening degree of the bleed air throttle valves V31 to V33. Therefore, the water level of the drain water can be adjusted within the range defined by the upper limit value and the lower limit value.

Further, in this modification, the operation of the bleed air throttle valves V31 to V33 is controlled based on the temperature data obtained by the water supply thermometers T31a to T33a and T31b to T33b, as in the case of the first embodiment described above. Here, based on the temperature data obtained by the feed water thermometers T31a to T33a and T31b to T33b, the temperature difference between the temperature of the inflowing water and the temperature of the outflowing water in the feed water heaters 31a to 33a and 31b to 33b is determined. The control device 800 calculates. Then, the control device 800 determines whether or not the calculated value of the temperature difference exceeds the upper limit value set in advance for the temperature difference. Then, when the calculated value of the temperature difference exceeds the upper limit value, the control device 800 adjusts the opening degree of the bleed air throttle valves V31 to V33. On the other hand, when the calculated value of the temperature difference is not more than the preset upper limit value, the control device 800 maintains the opening degree of the bleed air throttle valves V31 to V33. Therefore, since the temperature difference between the feed water heaters 31a to 33a and 31b to 33b can be set to the upper limit or less, it is possible to effectively prevent the feed water heaters 31a to 33a and 31b to 33b from being damaged.

<Others>
Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

1 ... Steam turbine, 2 ... Feed water heater, 3 ... Feed water heater, 4 ... Boiler, 11 ... High pressure turbine section, 12 ... Medium pressure turbine section, 13 ... Low pressure turbine section, 14 ... Generator, 31 (31a, 31b) ) ... 1st high-pressure water supply heater (water supply heater), 32 (32a, 32b) ... 2nd high-pressure water supply heater (water supply heater), 33 (33a, 33b) ... 3rd high-pressure water supply heater (water supply heater) ), 34 ... 1st low pressure feed water heater (feed water heater), 35 ... 2nd low pressure feed water heater (feed water heater), 300 ... valve casing, 300A ... inlet, 300B ... outlet, 310 ... valve body, 310S ... Stopper, 311 ... Deaerator, 320 ... Valve rod, 330 ... Drive device, 800 ... Control device, 81 ... Function generator, 811-815 ... PID controller, 82 ... Low value selector, 83 ... High price selector, FT31 to FT33 ... Flow meter, LT31a to LT33a, LT31b to LT33b ... Level meter, P2 ... Water return pump, P311 ... Feed water pump, P31a, P31b, P32a, P32b, P33a, P33b, P34, P35 ... Pressure gauge, T2 T311a, T311b, T31a, T31b, T32a, T32b, T33a, T33b, T34, T35 ... Feed water heater, V31, V31a, V31b ... 2 high-pressure bleeding squeezing valve (extracting squeezing valve), V33, V33a, V33b ... 3rd high-pressure bleeding squeezing valve (extracting squeezing valve), V34 ... 1st low-pressure bleeding squeezing valve (extracting squeezing valve), V35 ... Low-pressure bleeding throttle valve (bleaching squeezing valve), X31a, X31b, X32a, X32b, X33a, X33b, X34, X35 ... Drain water thermometer, 80 ... Frequency sudden decrease detector 80, T80 ... Steam table

Claims (9)

With a steam turbine,
A condenser that cools and condenses the steam exhausted from the steam turbine,
A water supply heating unit that heats the condensed water in the condenser by using the steam extracted from the steam turbine as a heating medium.
A boiler that generates steam by heating the water heated in the water supply heating unit, and
A thermal power plant that is equipped with a generator that generates electricity by being driven by supplying steam generated by the boiler to the steam turbine, and the power generated by the generator is output to the power system. ,
A bleed throttle valve that adjusts the flow rate of the heating medium supplied to the water supply heating unit, and
It has a control device that controls the operation of the bleed air throttle valve.
The water supply heating unit is
Multiple feed water heaters
Equipped with
The pressure of the heating medium supplied to each of the plurality of feed water heaters is configured to be sequentially increased along the flow of water condensed by the condenser, and the water condensed by the condenser. The plurality of feed water heaters are configured in multiple stages so that the temperature of the condensed water in the condenser rises by sequentially flowing through the plurality of feed water heaters.
The bleed air throttle valve is a plurality, and is provided in each stage of the multi-stage feed water heater.
In the case of normal operation, the control device adjusts the opening degree of the plurality of bleed air throttle valves to a predetermined amount.
The opening degree of the plurality of bleed air throttle valves is adjusted so that the flow rate of the heating medium supplied to the water supply heating unit is reduced as compared with the case of the normal operation when the decrease in the system frequency in the power system is detected. By doing so, when starting the output increasing operation that increases the output of the generator as compared with the case of the normal operation, at least one of the plurality of bleed air throttle valves is closed.
When the output increasing operation is being executed, the temperature difference between the temperature of the inflowing water and the temperature of the outflowing water in each of the plurality of feed water heaters is calculated, and the calculated value of the calculated temperature difference is calculated in advance. It is determined whether or not the set upper limit value is exceeded, and if the calculated value exceeds the upper limit value, the water supply located upstream of the feed water heater exceeding the upper limit value among the plurality of bleed air throttle valves. Open the bleed air throttle valve for adjusting the flow rate of the heating medium to the heater.
Thermal power plant. The water supply heating unit is
The first feed water heater and
The second feed water heater whose pressure of the heating medium is lower than that of the first feed water heater is included as the feed water heater, and the water condensed by the condenser is the second feed water heater and the first feed water heater. It is configured so that the temperature rises by sequentially flowing through the heater.
The bleed air throttle valve is
The first feed water heater has a first bleed throttle valve for adjusting the flow rate of the heating medium, and the first feed water heater.
The second feed water heater includes at least a second bleed throttle valve for adjusting the flow rate of the heating medium.
The control device is
When the output increasing operation is started, the second bleed air throttle valve is closed.
When the output increasing operation is being executed, the temperature difference between the temperature of the water flowing into the first feed water heater and the temperature of the water flowing out from the first feed water heater is calculated, and the calculated temperature difference is calculated. It is determined whether or not the calculated value exceeds the preset upper limit value, and if the calculated value exceeds the upper limit value, the second bleed air throttle valve is opened.
The thermal power plant according to claim 1 . The water supply heating unit is
High-pressure water supply heating unit and
The temperature of the heating medium includes the low-pressure water supply heating unit whose pressure is lower than that of the high-pressure water supply heating unit, and the water condensed by the condenser flows through the low-pressure water supply heating unit and the high-pressure water supply heating unit in sequence. Is configured to rise,
The first feed water heater and the second feed water heater constitute the high-pressure feed water heater.
The thermal power plant according to claim 2 . The water supply heating unit is
High-pressure water supply heating unit and
The temperature of the heating medium includes the low-pressure water supply heating unit whose pressure is lower than that of the high-pressure water supply heating unit, and the water condensed by the condenser flows through the low-pressure water supply heating unit and the high-pressure water supply heating unit in sequence. Is configured to rise,
The first feed water heater and the second feed water heater constitute the low-pressure feed water heater.
The thermal power plant according to claim 2 . With a steam turbine,
A condenser that cools and condenses the steam exhausted from the steam turbine,
A water supply heating unit that heats the condensed water in the condenser by using the steam extracted from the steam turbine as a heating medium.
A boiler that generates steam by heating the water heated in the water supply heating unit, and
A thermal power plant that is equipped with a generator that generates electricity by being driven by supplying steam generated by the boiler to the steam turbine, and the power generated by the generator is output to the power system. ,
A bleed throttle valve that adjusts the flow rate of the heating medium supplied to the water supply heating unit, and
It has a control device that controls the operation of the bleed air throttle valve.
The control device is
By adjusting the opening degree of the bleed air throttle valve so that the flow rate of the heating medium supplied to the water supply heating unit is reduced as compared with the case of normal operation when the decrease in the system frequency in the power system is detected. When performing an output increasing operation that increases the output of the generator as compared with the case of the normal operation, the temperature inside the water supply heating unit to which the heating medium is supplied is higher than the saturation temperature of the heating medium. The opening degree of the bleed air throttle valve is adjusted by a predetermined procedure that determines in what order and how much the bleed air throttle valve is opened after the output increasing operation is started so as to be in a low state.
Thermal power plant. When the output increasing operation is being executed, the control device detects the internal pressure of the water supply heating unit and determines the temperature of the drain water existing at the location where the heating medium is supplied in the water supply heating unit. Detecting, the saturation temperature of the heating medium is determined based on the internal pressure , and the operation of the bleed air throttle valve is controlled so that the temperature of the detected drain water is lower than the determined saturation temperature.
The thermal power plant according to claim 1. The bleed air throttle valve has a stopper installed at a position that prevents the opening degree from being fully closed.
The thermal power plant according to claim 5 or 6 . The control device is
When the output increasing operation is being executed, the flow rate of steam supplied as the heating medium to the water supply heating unit, the water level of the drain water existing inside the water supply heating unit to which the heating medium is supplied, and the water supply. The operation of the bleed air throttle valve is controlled based on one or more of the temperatures of water flowing as a medium to be heated in the heating unit.
The thermal power plant according to claim 6 or 7 . The bleed air throttle valve is a hydraulic valve.
The thermal power plant according to any one of claims 1 to 8 .

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