JPS5910714A - Feed water heating equipment - Google Patents

Abstract

PURPOSE:To improve the efficiency of normal operation, by providing a passage for supplying one of the bled steam and exhaust steam of a steam turbine as a heat source for an added feed water heater and another passage for recovering a heating-side fluid to the feed water heater and by efficiently using the added heater. CONSTITUTION:Superheated steam bled from a reheating turbine 5 is supplied as a heat source for an added heater 14 through a passage 16. A passage 17 is provided so that a heating-side fluid having finished heat exchange in the added heater 14 is introduced into a first high-pressure heater 12 and thus recovered. When the steam bled from the reheating turbine 5 is superheated, an automatic controller 23 opens a shutoff valve 19 so that the superheated steam flows into the added heater 14 through the passage 16. At that time, the heating-side fluid having finished heat exchange for heating feed water is recovered in a lowered degree of superheat to the first high-pressure heater 12 through the passage 17. The temperature of the feed water supplied to an evaporating section 1 is heightened by the added heater 14 so that the efficiency of a plant is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a feed water heating device for a power plant using a steam turbine as a prime mover.

In a once-through boiler without a drum, there is a risk of burnout of the evaporator tubes due to uneven flow of the feed water inside the evaporator due to a drop in the amount of water feed during startup or low-load operation. To prevent this, it is necessary to supply water to the evaporator at a minimum or constant flow rate.

An additional heater system is used as one of the means to ensure the above-mentioned minimum flow rate.

FIG. 1 is a system diagram of the additional heater system. In normal operation, the steam generated in the evaporator section 1 passes through the superheater 2 to perform the work that has been completed by supplying it to the high-pressure turbine 3, and then is given a high degree of superheating in the reheater 4, and is then transferred to the reheating turbine 5 and the low-pressure turbine. 6
The water does work, is condensed in a condenser 7, and is sent to a deaerator 10 by a condensate pump 8 via a low-pressure heater 9. Deaerator 1
The feed water degassed at o is boosted in pressure by the feed water pump 11, sequentially passed through the first high pressure heater 12 and the second high pressure heater 13, heated, and then passed through the additional heater 14 to the evaporation section 1.
Reflux to. In the additional heater 14 described above, heat exchange is not performed during normal operation.

At startup or under low load, water is supplied by the water supply pump IOK to ensure the minimum flow rate of the evaporator, and the supplied water passes through the additional heater 14 and flows through the evaporator 1 to form a two-phase supply flow. The steam is separated into drain and steam in the steam separator 15.

After the separated drain undergoes heat exchange with the additional heater 14, it flows into the deaerator 1o via the valve 24. As mentioned above,
Deaerator i during start-up or low load.

→ Water pump 11 → Additional heater 14 (heated side J → Evaporator 1 → Brackish water separator 15 → Additional heater 14 (heating side) → Deaerator 1o) By performing a closed cycle operation, the minimum flow rate of the evaporator L can be reduced. At this time, the additional heater 14 performs heat exchange between the water supply and the drain.

As described above, conventionally, heat exchange is performed using an additional heater or when the load is low, but there is no effect during normal operation. That is, the additional heater did not contribute at all to improving the thermal efficiency of the plant during normal operation.

The present invention has been made in view of the above-mentioned circumstances, and provides a feed water heating system that can improve the efficiency of the plant during normal operation by utilizing a heater in a steam power plant equipped with a once-through boiler equipped with an additional heater. The purpose is to provide equipment.

-J-, objective f: In order to achieve this, the feedwater heating device of the present invention includes a once-through steam generator, a steam turbine that can be driven by the steam from the steam generator, and a generator connected to a nuclear steam turbine. , a feed water heater for heating the feed water supplied to the steam generator by 710 hot steam supplied from the steam turbine, and a feed water heater installed between the steam generator and the feed water heater. In a power generation plant equipped with an additional feed water heater for heating the above feed water using fluid supplied from a fresh air generator as a heat source, either the extracted air or the exhaust air of the steam turbine is used for additional feed water heating. The present invention is characterized by providing a pipe line for supplying the water as a heat source to the water heater, and a pipe line for collecting the fluid on the heating side that has completed heat exchange in the additional feed water heater to the feed water heater.

Next, one embodiment of the present invention will be described with reference to FIG. Conventional device f (evaporator section 1, superheater 2, high-pressure turbine 3, reheater 4, reheat turbine 5, low-pressure turbine 6, condenser 7, with the same drawing reference numbers as in Figure 1) Condensate pump 8
, low pressure heater 9, deaerator 10, water supply pump 11. A first high pressure heater 12, a second high pressure heater 13, an additional heater 14,
The steam separator 15 and valve 24 are the same or similar components as in conventional systems.

The first difference between this embodiment and the conventional apparatus is that a conduit 16 is provided for supplying superheated steam extracted from the reheat turbine 5 as a heat source to the additional heater 14.

When the present invention is actually applied, a conduit (not shown) that supplies the exhaust gas of the reheat turbine 5 as a heat source for the additional heater 14
may be provided.

The second difference between this embodiment and the conventional device is that a conduit 17 is provided for introducing and recovering the heating-side fluid that has undergone heat exchange with the additional heater 14 into the first high-pressure heater 12.

This embodiment is equipped with an electromagnetically actuated stop valve 19 in the above-mentioned steam supply pipe line 16, and an automatic control device 23 for controlling this stop valve 19. ,
The output signals of the pressure detector 21 and the temperature detector 22 are input, and the stop valve 19 is opened when the steam supplied to the pipe line 16 is superheated steam, and closed when it is wet steam. Configure for controlled operation.

In the feed water heating device configured as described above, when the extracted air from the square heat turbine 5 becomes superheated steam, the pressure detector 21
The automatic control device 23 which receives the detection output signal of the temperature detector 22 opens the stop valve 19, and the superheated steam flows into the additional heater 14 through the pipe line 16. The inflowing superheated steam exchanges heat with the feed water to heat the feed water, and the fluid on the heating side that has completed the heat exchange is recovered to the first high pressure heater 12 via the pipe 17 in a state where the degree of superheat has decreased.

When the operation is performed as described above, the temperature of the water supplied to the evaporator 1 is raised by the additional heater 14, and this effect is carried out during normal operation of the steam motor plant. It is obvious that raising the temperature of the feed water in this way increases the Rankine cycle efficiency and improves the plant efficiency.

In conventional technology, a triheater using superheated steam as a heat source is installed between the final stage feedwater heater and the boiler in order to improve plant efficiency by increasing Rankine citral efficiency. According to the embodiment, it is possible to achieve the same efficiency improvement as when a dry heater is provided using the additional heater 14 by adding a simple configuration without separately providing a dry heater.

As in this embodiment, a stop valve 1 is provided in the pipe line 16 for supplying superheated steam.
9, and the stop valve 19 is equipped with an automatic control device 23 that operates to open when the steam supplied to the pipe line 16 is superheated steam. When the bleed air from the turbine 5 becomes superheated steam, the steam system is automatically switched to operate the additional heater 14 as a dry heater, making it easy to make two military changes.

Next, a description will be given of an embodiment shown in FIG. 2, which is different from the above. A pressure detector 25 and a temperature sensor 26 are provided in the outflow pipe of the heating fluid of the additional heater 14, and the detection output signal is inputted to the automatic control device 23, so that the heating fluid diverted from the additional heater 14 is wet steam or When it becomes a liquid, the stop valve 19 and the stop valve 20 interposed between the UPA fluid outflow pipe of the additional heater 14 and the heat flow fluid inflow pipe of the first high pressure heater 12 are closed. In addition, at the same time as the above-mentioned valve closing operation, a stop valve 18 provided in a conduit supplying the extracted air from the reheat turbine 5 to the first high-pressure turbine 12 is opened. Configure. As in this embodiment, the stop valve 19 is provided with a control means so that the stop valve 19 is closed when the hot side fluid of the additional heater 14 is leaked steam or liquid after heat exchange. If this is done, when the load decreases during plant operation and the steam at the outlet of the additional heater 14 becomes wet steam or liquid, the additional heater 14 will be automatically connected as a dry heater.
Operation is easy because the existing pipe system can be switched over to operate as the original additional heater.

A further different embodiment will now be described with reference to FIG.

A load detection line 27 is provided in the reheat turbine 5, and its detection output signal is inputted to the automatic control system 23, and when the load becomes lower than a preset value, the stop valve 19 and the stop valve 2 are activated.
0'r - The stop valve 24 is configured to open when the valve is closed.

According to this embodiment, when the load of the plant suddenly decreases, drain is generated from the brackish water 'R' device 15 and the water is drained from the additional heater 14.
When the flow reaches the state, the additional heater 14 is automatically turned on.
The operation is easy because the additional heater 14, which was acting as a dry heater, can be automatically made to function as the original additional heater by switching the heating side fluid conduit.

In the above embodiment, the extracted air from the reheat turbine 5 is used as a heat source for the additional heater 14, but when the present invention is actually applied, superheated steam that is oil or exhaust gas other than the reheat turbine is added. It can also be used as a heat source for a heater.

Figure 3 shows the absorption rate of superheat in the additional heater (shown in % on the horizontal axis) and the improvement in plant efficiency (shown in % on the vertical axis).
This is a chart showing the relationship between the superheating degree and the enthalpy of 142 kcat/Kg+ when superheated steam is used. Under these conditions, 9 of the superheat
It can be seen that increasing the feed water temperature by 0% of the heat amount improves the plant efficiency by 0.34%.

For example, in a 700,000 KW power generation facility, the fuel unit price is 8 yen/
Based on a trial calculation based on kca7, the annual fuel cost savings due to an efficiency improvement of 0.34% will be 290 million yen.

As described above, the feedwater heating device of the present invention includes a quality flow steam generator, a steam turbine driven by the steam from the steam generator, a generator connected to the steam turbine, and the above-mentioned steam generator. A feed water heater for heating the feed water supplied to the steam generator by heated steam supplied from the turbine, and a feed water heater installed between the above steam generator and the feed water heater to heat the liquid supplied from the steam generator. In a power generation plant equipped with an additional feedwater heater for heating the above-mentioned feedwater as a heat source, a conduit is provided for supplying either the bleed air or exhaust air of the steam turbine as a heat source to the additional feedwater heater, By providing a pipe line for recovering the heating side fluid that has completed heat exchange in the above-mentioned additional feedwater heater, the additional heater can be used in a steam power plant equipped with a once-through boiler equipped with an additional heater. It has an excellent practical effect of improving the efficiency of plants during normal operation, and it greatly contributes to the social demand of not only reducing operating costs but also saving energy resources.

[Brief explanation of the drawing]

FIG. 1 is a steam system diagram of a steam power plant equipped with a once-through steam generator and an additional feedwater heater, and FIG. 2 is a steam system diagram of a steam power plant equipped with an embodiment of the feedwater heating device of the present invention. FIG. 3 is a chart showing the relationship between the absorption rate of superheat degree and efficiency improvement. DESCRIPTION OF SYMBOLS 1... Regeneration part, 5... Reheat turbine, 1o... Deaerator, 11... Water supply pump, 12... First high ξE heater, 13... Second high pressure heater, 14...Additional heater, 15...Brackish water separator, 16.17...Pipeline, 1
8,19.20...Stop valve, 21.25...Pressure detection 5.22.26...Temperature detector, 23...Automatic control device, 27...Load detector Lb device. Figure Z ■ 3 Figure 1 Old

Claims (1)

[Claims] 1. A once-through steam generator, a steam turbine driven by steam from the steam generator, a generator connected to the steam turbine, and heated steam supplied from the steam turbine. A feedwater heater for heating the feedwater supplied to the steam generator; and a feedwater heater installed between the steam generator and the feedwater heater to heat the feedwater using the fluid supplied from the steam generator as a heat source. In a power generation plant equipped with an additional feedwater heater for the purpose of the present invention, a pipeline is provided for supplying either the bleed air or the exhaust gas of the steam turbine as a heat source for the additional feedwater heater, and in the additional feedwater heater, A feed water heating device characterized by being provided with a conduit for collecting the fluid on the heating side after heat exchange to the feed water heater. 2. The pipe line that supplies either the extracted air or the exhaust air from the steam turbine to the additional feed water heater shall have a stop valve, and the stop valve shall be used to prevent the steam supplied to the pipe line from being overheated. The feed water heating device according to claim 1, further comprising a control means that opens the valve when the water is steam. 3. The pipe line that supplies either the extracted air or the exhaust gas from the steam turbine to the additional feedwater heater shall have a stop valve, and the stop valve shall terminate heat exchange in the additional feedwater heater. Claim 1 or 2 is characterized in that it is equipped with a control means that operates to close the valve when the fluid on the heating side is stagnant steam and when it is fluid. Feed water heater as described in. 4. The steam turbine is equipped with a load detector, and the pipe that supplies either the bleed air or the exhaust air from the steam turbine to the additional feedwater heater is equipped with a stop valve, Claim 1, further comprising a control means that operates to close the stop valve when the detected value of the load detector is lower than a preset value. The feed water heating device according to Item 2 or Item 3 of the same.