JPS6239647B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a steam turbine plant, and more particularly to a steam turbine plant having a turbine bypass device.

[Technical background of the invention]

FIG. 1 is a schematic system diagram of a steam turbine plant having a general turbine bypass device, in which steam generated in a boiler 1 is introduced into a high-pressure turbine 3 via a main steam pipe 2, where work is performed and the high-pressure The steam that has performed work in the turbine 3 is introduced into a reheater 5 via a low temperature reheat steam pipe 4. The steam reheated in the reheater 5 is transferred to a high temperature reheat steam pipe 6
The water is then sequentially supplied to an intermediate pressure turbine 7 and a low pressure turbine 8, where each performs work and drives a generator 9. The steam that has completed its work in the low-pressure turbine 8 flows into a condenser 10 and is condensed there, and the condensed water is sequentially passed through a plurality of low-pressure feed water heaters 12a, 12b, and 12c by a condensate pump 11. Thereafter, the condensate is sent to a deaerator 13 where gas components in the condensate are removed.

The condensate from which the gas components have been removed is sent to the water supply pump 14
After being sequentially supplied to a plurality of high-pressure feed water heaters 15a, 15b, and 15c arranged in series and heated, the water is returned to the boiler 1.

By the way, the main steam pipe 2 and the low temperature reheat steam pipe 4
means a first bypass conduit 1 having an on-off valve 16
7, and a second bypass conduit 18 connected to the condenser 10 is connected to the high temperature reheat steam pipe 6. The second bypass conduit 18 includes an on-off valve 19 and a desuperheater 20.
A part of the condensate discharged from the condensate pump 11 is supplied to the desuperheater 20 as cooling water through a valve 21.

Therefore, in the above plant, the steam generated in the boiler 1 when the plant is started up or when the load is interrupted passes through the first bypass conduit 17 connected to the main steam pipe 2 and flows into the low temperature reheat steam pipe 4. inflow,
It is recovered to the condenser 10 via the reheater 5, the high temperature reheat steam pipe 6 and the second bypass conduit 18.

[Problems with background technology]

However, in this type of plant, the steam generated in the boiler 1 when the plant is started up or when the load is off is introduced into the condenser through the bypass pipe, so the steam energy generated in the boiler is transferred to the condenser. This causes problems such as wasteful release of thermal energy.

In particular, the electricity demand pattern in recent years is mainly daytime demand.
Demand at night is relatively low, and demand tends to fluctuate sharply. Therefore, as a way to address the imbalance between demand between day and night, an increasing number of power plants are equipped with a turbine bypass device to quickly start up and shut down each day.

However, in the above plants, the steam energy generated in the boiler is released to the condenser without driving the steam turbine during startup and shutdown every day, resulting in a considerable loss of thermal energy. It's inconvenient.

[Purpose of the invention]

In view of these points, an object of the present invention is to provide a steam turbine plant that can effectively utilize the energy of steam bypassing a steam turbine.

[Summary of the invention]

The present invention provides, in a steam turbine plant equipped with a turbine bypass device, a steam storage device for storing steam that has bypassed the steam turbine, and the steam stored in the steam storage device.
For example, it is characterized in that the steam is supplied to the feed water heater via a steam supply pipe.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 2 and 3. Note that the same parts as in FIG. 1 are given the same reference numerals, and detailed explanation thereof will be omitted.

In FIG. 2, a high-temperature reheat steam pipe 6 that supplies the steam reheated in the reheater 5 to the intermediate pressure turbine 7 has a pipe that bypasses the intermediate pressure turbine 7 and the like to flow the reheated steam. One end of the second bypass conduit 18 is connected to the other end of the second bypass conduit 18, and a steam storage device 22 is connected to the other end of the second bypass conduit 18. The second bypass conduit 18 is provided with an on-off valve 19 and a desuperheater 20, and hot water in the steam storage device 22 is supplied to the desuperheater 20 as cooling water by a pump 23. It is set as.

On the other hand, the steam storage device 22 has a steam extraction pipe 2
4 is provided. Steam supply pipes 25a, 25b, and 25c are branched out from the steam extraction pipe 24 in correspondence with the respective low-pressure feedwater heaters 12a, 12b, and 12c, and their tips are connected to the low-pressure feedwater heaters 12a, 12b, and 12c, respectively. connected and
Each of the steam supply pipes 25a, 25b, 25c includes
On-off valves 26a, 26b, 26c and check valves 27a, 27b, 27c are provided, respectively.

FIG. 3 shows the on-off valves 26a, 26b, 26c.
This is a control system diagram for controlling the opening and closing of the check valves 26a, 27c, in which a closing operation signal for each of the check valves 27a, 27b, and 27c is inputted to the control device 28, and the control device 28 controls each of the opening and closing valves 26a, 26b, 26c
The opening/closing operation command signal is output at the same time.

That is, each low pressure feed water heater 12a, 12b,
The check valve 27c of the steam supply pipe 25c connected to the low-pressure feedwater heater 12c on the high-pressure side of the steam storage device 12c controls the pressure inside the steam storage device 22 and the low-pressure feedwater heater 1.
2c, a closing operation command signal is generated from the control device 28 to the on-off valve 26c based on the closing operation signal, and the feedwater heater 12b on the lower pressure side than the low pressure feedwater heater 12c is closed. An opening operation signal is generated to the on-off valve 26b of the steam supply pipe 25b connected to the steam supply pipe 25b. Thereafter, similarly, the opening and closing operations of the on-off valves are sequentially performed in response to the closing operations of each check valve.

Thus, in the above plant, the on-off valves 16 and 19 are opened, for example, when the plant is started up. Therefore, only the necessary amount of steam is vented to the high pressure turbine 3, intermediate pressure turbine 7, and low pressure turbine 8 by the control valve (not shown), and the boiler 1
Most of the steam generated in the first bypass conduit 17, the reheater 5, and the second bypass conduit 18
, the temperature is reduced in the attemperator 20 and the steam storage device 2
2. It is stored as hot water.

In this way, when the load on the steam turbine increases and reaches the set load, both bypass conduits 17, 18
The on-off valves 16 and 19 provided in the boiler 1 are closed, the steam generated in the boiler 1 is sequentially supplied to each turbine, the load on the steam turbine is increased, and the steam turbine shifts to rated operation.

On the other hand, when the plant is stopped, if the steam turbine load falls below the set load, both bypass conduits 1
The on-off valves 16 and 19 of 7 and 18 are opened, and the steam that has bypassed the steam turbine is stored in the steam storage device 22.

By the way, when the steam turbine plant is in rated operation, the low pressure feed water heaters 12a, 12b, 12c
Steam supply pipes 25a, 25b, 25c connected to
The on-off valves 26a, 266b, and 26c are sequentially opened from the high-pressure feed water heater side, and the hot water stored in the steam storage device 22 is depressurized and becomes approximately saturated steam.
The steam is supplied to the feedwater heaters 12a, 12b, and 12c together with extraction air from a normal turbine as steam for heating condensate.

That is, when the steam turbine plant enters rated operation, the on-off valve of the steam supply pipe connected to the feedwater heater with the highest pressure among the internal pressures of the feedwater heater that are lower than the pressure of steam generated from the steam storage device 22. will be released first.

For example, if the internal pressure of the low-pressure feed water heater 12c is the highest and the heat of the steam generated from the steam storage device 22 can be recovered, the on-off valve 26c is first opened, and the other on-off valves 26a and 26b are closed. and the low pressure feed water heater 12 via the on-off valve 26c.
Steam from the steam storage device 22 is supplied to c.
By the way, since the steam generated in the steam storage device 22 is generated by depressurization, the pressure of the generated steam decreases over time, and this steam pressure becomes lower than the internal pressure of the low-pressure feed water heater 12c. When it becomes low, the check valve 27c closes. Therefore, the closing signal of this check valve 27c is applied to the control device 28, and the on-off valve 26c is closed by the output signal from the control device 28, and the next on-off valve 26 is closed.
b is opened. Similarly, when the check valve 27b is closed, the control device 28 closes the on-off valve 26b, opens the on-off valve 26a, and
Steam from the steam storage device 22 is supplied to 2a as heated steam.

In this way, when the steam pressure generated in the steam storage device 22 becomes lower than the internal pressure of the low-pressure feed water heater 12a, the check valve 27a is closed, the control device 28 closes the on-off valve 26a, and the steam storage device 2
The supply of steam to the turbine cycle from 2 is stopped.

In the above embodiment, steam from the steam storage device 22 is supplied to the low-pressure feed water heater, but if the pressure of the steam generated from the steam storage device is high, a deaerator or high-pressure water feed water heater may be used. It is also possible to recover the thermal energy of the generated steam from the steam storage device in the heater. Alternatively, the steam generated by the steam storage device may be simultaneously supplied to a plurality of feed water heaters and the thermal energy thereof may be recovered. It can also be applied to nuclear turbine plants.

Note that in this embodiment, the low-pressure feed water heaters 12a, 1
In order to prevent backflow of steam from 2b, 12c to the low pressure turbine 8, it is desirable to install a device for controlling the flow rate, such as an orifice, downstream of the on-off valves 26a, 26b, 26c.

〔Effect of the invention〕

As explained above, in the present invention, the bypass steam that flows out from the reheater and bypasses the medium/low pressure turbine is temporarily stored in the steam storage device, and during rated operation, the steam is used as part of the heating steam of the feedwater heater. Therefore, in the steam feedwater heater, the amount of extracted steam from the turbine is reduced by the amount of heat of the steam supplied from the steam storage device, and the amount of steam at the turbine inlet, that is, the amount of steam generated by the boiler, is reduced, and the fuel consumption of the boiler is reduced. The amount of steam can be saved and the steam energy that was previously wasted in the condenser can be recovered, greatly improving plant efficiency.

Moreover, since the steam that has passed through the reheater is stored, high-temperature steam can be stored and storage efficiency can be improved.

In addition, since the steam is supplied from the steam storage device in order from the feed water heater on the high pressure side, the usable pressure range of the steam generated from the steam storage device increases, increasing the amount of usable thermal energy. be able to.

As described above, in the present invention, steam that has not been utilized in the past can be used efficiently and effectively, and the efficiency of the plant can be improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic system diagram of a conventional steam turbine plant, FIG. 2 is a schematic system diagram of a steam turbine plant of the present invention, and FIG. 3 is a control system diagram of an on-off valve provided in a steam supply pipe. DESCRIPTION OF SYMBOLS 1...Boiler, 2...Main steam pipe, 3...High pressure turbine, 4...Low temperature reheat steam pipe, 5...Reheater, 6...High temperature reheat steam pipe, 12a, 12b, 12c...Low pressure feed water heater, 17... first bypass conduit, 18...second
Bypass conduit, 20... Attemperator, 22... Steam storage device, 25a, 25b, 25c... Steam supply pipe, 2
6a, 26b, 26c...on/off valve, 27a, 27
b, 27c...Check valve.

Claims (1)

[Claims] 1 In a steam turbine plant having a first bypass conduit that bypasses a high-pressure turbine and a second bypass conduit that causes steam flowing out of a reheater to bypass the intermediate/low pressure turbine, the second bypass conduit is The steam storage device is connected to a plurality of feed water heaters via steam supply pipes each having an on-off valve and a check valve, and the on-off valve is connected to the steam pressure in the steam storage device. A steam turbine plant characterized in that the feedwater heaters connected to the high-pressure side are sequentially opened according to the demand.