JPS5993906A - Steam turbine plant - Google Patents

Abstract

PURPOSE:To make the recovery of heating steam by a reheater ever so easy as well as to prevent a temperature of feed water from dropping, by installing an on-off valve in piping which interconnects the reheater and a high pressure feed water heater, and also installing the on-off valve in another piping which interconnects the feed water heater at the low temperature side and the reheater through. CONSTITUTION:An atomic power generation plant consists of a reactor and a steam generator 1, a high pressure turbine 3, a reheater 5, a low pressure turbine 6, a condenser 8, etc. An on-off valve 24 is installed in piping 16 which interconnects the reheater 5 and a high pressure feed water heater 12 through. Likewise, the on-off valve 24 is also installed in another piping 22 which interconnects a low pressure feed water heater 10 and the reheater 5 through. In time of partial load operation, an on-off valve 19 opens while another on-off valve 23 closes, switching an extraction steam point from X to Y. At this time, these on-off valves 24 and 23 turn to open and close respectively whereby the accompanying steam of heating steam in the reheater 5 is led by the low temperature feed water heater 10. Doing like this, flowing of the heating steam in the reheater is also stabilized so that a reaction core is stabilized too.

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 with improved operating conditions during partial load operation.

[Technical background of the invention]

For example, in nuclear power plants, full-capacity turbine binoculars are used to stabilize the power system. In the event of a power system accident, nuclear power plants are operated at an output equivalent to the on-site load.

That is, in the event of an accident, the full capacity turbine bypass is operated to reduce the amount of steam sent to the steam turbine, and the steam turbine is operated by reducing its output to less than half of its rated output.

However, in the water supply system of a nuclear power plant that uses extracted steam from a steam turbine as heating steam, when the amount of steam sent to the steam turbine decreases, the temperature of the feed water decreases to compensate for the decrease in heating steam, and the temperature inside the reactor decreases. Temperature rise increases.

As a result, temperature differences become large locally within the nuclear reactor, creating conditions that are unfavorable in terms of plant life, and in some cases creating a need to restrict the operating time of the full-capacity turbine bypass.

There is a nuclear power generation plant shown in Figure 1 that improves this point. In FIG. 1, reference numeral 1 indicates a nuclear reactor and a steam generator. In the plant shown in FIG. 1, high-temperature, high-pressure steam (main steam) generated by a steam generator 1 is sent to a high-pressure turbine 3 through a main steam pipe 2 equipped with a steam control valve 18, where the steam Energy is converted into mechanical work.

Next, the steam that has passed through the high-pressure turbine 3 is sent to the reheater 5 via the connecting pipe 4, where the steam is introduced into the reheater 5 via the bleed pipe 14 from point Y in the middle of the high-pressure turbine 3. Heated by heated steam.

Next, the steam heated in the reheater 5 is sent to the low pressure turbine 6, where the kinetic energy of the steam is again converted into mechanical work. The energy converted into mechanical work and the energy converted into mechanical work are used to drive the generator 7.

Further, the steam that has passed through the low-pressure turbine 6 is sent to a condenser 8, where the steam is cooled and condensed to become condensed water. This condensate is sucked by the pump 9 and sent to the low pressure feed water heater 10, where it is heated.

Next, the heated condensate is pressurized by the pump 11 to become feed water and is sent to the high-pressure feed water heater 12, where the feed water is passed from point It is heated by the introduced bleed steam. Thus, the heated feed water is returned to the steam generator 1.

On the other hand, a portion of the heated steam introduced into the reheater 5 becomes drain and is recovered to the high-pressure feed water heater 12 through the connecting pipe 15. The heated steam that is not drained becomes accompanying steam and is recovered to the high-pressure feed water heater 12 through the connecting pipe 16.

The above is a case of normal operation, but the full capacity bypass valve 17a installed in the pipe 17 that branches from the main steam pipe 2 on the upstream side of the steam control valve 18 and reaches the condenser 8 is activated. When going to partial load G, the opening degree of the steam control valve 18 is narrowed, a part of the main steam is bypassed to the condenser 8, and the remaining main steam is sent to the high-pressure turbine 3. As a result, the steam sent from the high-pressure turbine 3 to the high-pressure feedwater heater 12 via the bleed pipe 13 decreases, and the temperature of the feed water inevitably falls considerably compared to the rated operation. The on-off valve 19 is closed, and the on-off valve 1 is branched from the bleed pipe 14.
The water supply to the steam generator 1 is increased by opening the on-off valve 21 disposed in the bypass bleed pipe 9 that communicates with the bleed pipe 13 on the downstream side of the 9, and increasing the pressure of the heated steam supplied to the high-pressure feed water heater 12. Suppresses temperature drop.

[Problems with background technology]

However, if the point of air extraction to the reheater 5 of the high-pressure turbine 3 and the point of air extraction to the high-pressure feedwater heater 12 are the same point Y, or the point of air extraction to the reheater 5 is the same as the point of extraction to the high-pressure feedwater heater 12. If the pressure is on the lower pressure side than the point, the following problem will occur.

In other words, the pressure loss due to the accompanying steam of the reheater heating steam passing through the reheater is greater than the pressure loss of the high-pressure feed water heater bleed steam, so the pressure of the heating steam of the reheater 5 is The internal pressure of the high-pressure feed water heater 12 may become higher, and as a result, recovery of the accompanying steam becomes unstable, and the flow of heated steam in the reheater 5 becomes unstable.

[Object of the present invention]

The present invention has been made in view of these points. 2. The purpose of the present invention is to reduce the instability of the accompanying steam recovery of the reheater heating steam caused by switching the extraction point of the bleed steam to the high pressure feed water heater during partial load operation. The object of the present invention is to obtain a steam turbine plant that can be operated stably even under partial load by suppressing the flow of steam heated by a reheater and stabilizing the flow of steam heated by a reheater.

[Summary of the invention]

The purpose is to provide a reheater for reheating the steam flowing out of the high pressure turbine and supplied to the low pressure turbine using extracted air extracted from an intermediate stage of the high pressure turbine;
In a steam turbine plant in which steam heat-exchanged with steam supplied to a low-pressure side turbine is introduced into a high-pressure feedwater heater, an on-off valve is provided in a pipe communicating with the reheater and the high-pressure feedwater heater, and A condenser disposed in a pipe line between the low-pressure side turbine and the high-pressure feedwater heater, or a pipe that communicates the low-pressure side feedwater heater with the reheater, is provided,
Furthermore, this can be achieved by providing an on-off valve in this piping.

[Embodiments of the invention]

The present invention will be explained below based on the embodiment shown in FIG. Note that in FIG. 2, the same reference numerals as in FIG. 1 indicate the same elements, and a description thereof will be omitted.

Furthermore, although the present invention relates to a steam turbine plant using thermal power or nuclear power, a nuclear power plant will be explained here.

In the nuclear power generation ground shown in FIG. 2, the reheater 5 and the high pressure feed water heater 12 are connected to each other, and
A branch pipe 22 that connects to the low-pressure feed water heater 10 is provided in the connecting pipe 16 that guides the accompanying steam to the low-pressure feed water heater 10 . This branch pipe 22 is provided with an on-off valve n, and an on-off valve is provided at a position downstream from the junction of the communication pipe 16 with the branch pipe n.

Next, to explain the operation during partial load operation of the nuclear power plant shown in FIG. 2, the on-off valve 19 of the bleed pipe 13 closes
The on-off valve 21 on the bleed pipe side is opened, and the bleed point is switched from bleed point X during rated operation to bleed point Y. Also, at this time, the on-off valve of the communication pipe 16 is opened and closed, and the on-off valve n of the branch pipe n is opened, and the accompanying air of the heated steam of the reheater 5 is transferred to the branch pipe n.
The water heater 10 is introduced into the h% pressure water heater.

According to the above embodiment, in the 9 part load operation, the recovery destination of the accompanying steam of the reheater heating steam is switched to the lower pressure side, so the recovery of the accompanying steam of the reheater heating steam is facilitated, and the reheater heating The flow of steam is also stabilized.

Further, the above embodiment can also be modified as shown in FIG. That is, the pressure detectors 6 and 26 are connected to the connecting pipe 1.
6. It is provided in the bleed pipe 13, and when the pressure of the bleed steam to the high-pressure feed water heater 12 becomes higher than the pressure of the reheater heating steam, the on-off valve 23 is opened and the on-off valve is closed, and the reheater 5 The accompanying steam of the heating steam may be transferred to the branch pipe 22 by four people, and the collection destination of the accompanying steam may be switched from the high-pressure feed water heater 12 to the low-pressure feed water heater 1o.

In this way, the reheater heating steam can be recovered even more effectively.

In addition, in the present invention, instead of recovering the accompanying steam to the low-pressure feedwater heater as described above, a plurality of steam may be supplied.

Further, in the first embodiment and the second embodiment, the branch pipe 4 is branched from the communication pipe 16.

The present invention is not limited to the examples.

The condenser or the low-pressure side feed water heater and the reheater may be connected directly through piping.

〔Effect of the invention〕

As described above, the steam turbine plant of the present invention provides an on-off valve in the piping that communicates the reheater and the high-pressure feedwater heater, and also provides the piping that communicates the low-pressure side feedwater heater and the reheater, and further This piping is equipped with an on-off valve, which makes it easy to recover the reheater heating steam and stabilizes the flow of the reheater heating steam, which suppresses the drop in feed water temperature and allows the reactor core to move forward. have an effect.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of a conventional nuclear power plant. FIG. 2 is a schematic diagram of an embodiment of the present invention, and FIG. 3 is a schematic diagram of a modification of FIG. 1... Nuclear reactor and steam generator, 3... High pressure turbine, 5... Reheater, Right... Low pressure turbine, 7...
··Generator. 8... Condenser, 10... Low pressure feed water heater, 12...
・High pressure water heater, 16...Connection pipe, 22...Branch pipe, 23.24...Opening/closing valve. Applicant's agent Kiyoshi Inomata

Claims (1)

[Scope of Claims] 1) A reheater is provided to reheat the steam flowing out from the high-pressure turbine and supplied to the low-pressure turbine using extracted air extracted from an intermediate stage of the high-pressure turbine, and the steam is supplied to the low-pressure turbine. In a steam turbine plant in which steam heat-exchanged with steam that is heated is introduced into a high-pressure feedwater heater, an on-off valve is provided in piping that communicates the reheater and the high-pressure feedwater heater, and the low-pressure side turbine and Steam characterized by having a pipe that communicates the reheater with a condenser or a low-pressure side feed water heater arranged in a pipe line between high-pressure feed water heaters, and further providing an on-off valve in this pipe. turbine plant. 2) The piping that communicates the condenser or the low-pressure feedwater heater with the reheater is branched from a position upstream of the on-off valve of the piping that communicates the reheater and the high-pressure feedwater heater. A steam turbine plant according to claim 1, characterized in that: