JPS6017607A - Reheater - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an atomic turbine plate 7 equipped with a reheater, and more particularly to an improvement in the drainage system for drainage generated in the reheater.

[Background of the invention]

In a nuclear power plant using a boiling water reactor or a pressurized water reactor, the steam generated in the reactor or steam generator is either saturated steam or slightly superheated. Therefore, the moisture content of the steam fed into the turbine increases as it expands in the turbine, but this moisture content is unfavorable in terms of turbine performance and safety. For this reason, various methods for removing moisture from steam have been proposed. One method is to install a moisture separator in the middle of the connecting pipe between the high-pressure turbine and the low-pressure turbine to remove moisture, and then reheat it using high-temperature, high-pressure steam such as main steam. . As a result, erosion of the p-side pressure turbine portion by water droplets can be reduced, and turbine efficiency can be improved. By the way, the reheater is a multi-tube heat exchanger consisting of a group of U-shaped tubes, and the steam that has produced the moisture separation gain does not rise in temperature by passing through the outside. On the other hand, inside the pipe, heated steam such as main steam loses its latent heat during condensation and exchanges heat. Therefore, the flow within 'a flows into the population area in a nearly saturated state2,
The amount of condensed liquid increases as it progresses in the longitudinal direction of the tube, and at the outlet of the tube, most of it is condensed water, and a part of it is a 7ζ flow with non-condensable gas and the like.

In order to prevent the deterioration of heat transfer performance in the reheater, the flow in the piping from the reheater to the drain tank should be saturated to prevent overcooling as much as possible. This takes into account the flow of water and blockages caused by 7-layer pipes, etc. in the pipes.

There is also the possibility that the operation of Kinba and nuclear power plants will be more diverse, from conventional base load operation to load following operation,
It is conceivable that there will be an increase in nighttime partial load operations and operations with load changes at daytime rated loads. Furthermore, when an abnormality occurs in nuclear couplant equipment, sudden load changes may occur in order to protect the reactor from shutdown. During such plant operation, as the pressure of the heating steam source decreases, the pressure in the reheater #Ff: occurs, but in the drain tank, the drain temperature υ is close to 5F before the pressure decreases. Because of this condition, the pressure inside the drain tank increases due to the internal pressure inside the drain tank, and this causes a reverse pressure phenomenon with the internal pressure, making it impossible to drain the drain. As a result, there is a back pressure between the heat exchanger tube inlet and outlet! J! In other words, the condensed water in the heat transfer tubes may become clogged or cause pulsation, which may lead to deformation, fatigue, and other damage to the heat transfer tubes, so avoid reverse pressure between the reheater and the drainer. It is necessary to prevent this phenomenon.

A specific example thereof is disclosed in Japanese Unexamined Patent Publication No. 1) ['i 54-108302. This system uses a water level detector installed at the outlet of the reheater to detect when condensate flows back into the drain tank when the heating steam gradient fluctuates drastically.
It consists of a system configuration that excludes the discharge system from a separately attached discharge system. In this case, at the time when the water level is detected, a back pressure phenomenon cannot be avoided with respect to the heat transfer tube, and the prevention effect can be enhanced.

OBJECTS OF THE INVENTION The object of the present invention is to provide a reheating device that can prevent reverse pressure phenomena between the inside of the ladle/heater and the inside of the drain tank for all load operations of the atomic bomb.

[Summary of the invention]

The main point of the present invention is that in a reheating device equipped with piping connected to a drain tank, a piping for discharging condensate, a check valve, an output relief pipe, and a pressure equalizing pipe with a valve are installed between the reheater and the fin/tank. It depends on what it consists of.

[Embodiments of the invention]

Examples of the present invention will be described below.

Fig. 1 shows the system configuration of a steam turpin circuit in a nuclear power generation plant.
It will be destroyed. The exhaust gas after being expanded in the high-pressure turbine 3 and releasing mechanical energy is sent to a moisture separation reheater 5 through a connecting pipe 4.
The steam that flows into the water, removes the moisture in the steam, and is reheated,
It again flows into the low pressure turbine 6 via the connecting pipe 4. After expanding in the low-pressure turbine 6 and releasing mechanical energy, the steam is condensed in a condenser or the like.

FIG. 2 shows the equipment and system configuration of a five-turn moisture separator/heater according to the present invention. Moisture Ii! The 1ic reheater 5 is composed of a moisture separator 7 and a reheater 8 in one container. The exhaust gas of the cylinder turbine 3 is usually 1O to 1
By mechanically separating the moisture in the steam in the moisture separator 7, it enters the reheater 8 as saturated steam with a moisture content of 0 to 2 percent,
After being superheated by about 8 to 8 oc, it is led to the low pressure turbine 6.

, IJ) The main steam header 1 is usually used as the heating steam source for the heater 8! Although it is assumed that the air is extracted from t2 or from the high-pressure turbine 3, the following description will be made on the case where the air is supplied from the main steam header pipe 2 as a heater. The heated steam is guided to the reheater 8 via the heated steam piping 22, the cutoff valve 23, and the control valve 24, and passes through a plurality of heat transfer tubes 9 for heat exchange. The water flows out from the outlet of the heat exchanger tube 90, and is discharged to the drainer/liter via the drain discharge pipe 10 connected to the outlet of the reheater 8, from the drain tank 11 whose water level is controlled. Furthermore, it is collected in a feed water heater or the like. In addition, a vent pipe 13 is provided to discharge noncondensable gas concentrated in the heat transfer g9 of the reheater 8 or a small amount of steam to stabilize the flow in the heat transfer tube 9, and the feed water heating Collected in containers, etc. On the other hand, drain discharge pipe 1
In order to make the flow in the reheater 8 a gravity flow, a pressure equalizing pipe 12 is provided to balance the pressure in the reheater 8 and the pressure in the drainer/well. In order to prevent the pressure in the drainer/tube 11 from rising higher than the pressure in the reheater 8 due to flushing of the water in the drainer/tuber 11, etc., in the middle of the pressure equalizing pipe 12,
A check valve 14 is provided, and the check valve 14 and the drain tank 1
A pressure relief valve 1 provided in a pressure relief pipe 15 connected between
6 is operated to open by the valve opening setting device 17 which uses the closing operation signal of the check valve 14 as the opening operation signal.

According to this embodiment, when a nuclear power plant is in a load following operation like a thermal power plant, the control valve 24 provided in the heating steam pipe 22 is operated in accordance with the amount of load change.
Although the amount of heating steam is controlled, the control valve 24 may not be closed when the load drops.Depending on the amount of load drop, the pressure You can also use the closing operation to tighten it. At this time, the water in the drain tank 11 is not water at the saturated temperature before the pressure is reduced, and as the pressure of the heated steam decreases, the water in the reheater 8 and the drain tank 11 The pressure decreases, accompanied by a flash of water, and the interior of the drain/liquid is pressurized due to the flashed steam.
In the case where pressure is propagated into the reheater 8, a reverse pressure phenomenon occurs at the entrance and exit of the heat exchanger tube 9, the inside of the heat exchanger tube 9 is blocked by condensed condensate, and supercooling etc. occurs. Drenta/ri1
When the internal pressure of the reheater 8 becomes higher than the internal pressure of the reheater 8, the check valve 14 is automatically closed to prevent the reverse pressure phenomenon inside the reheater 8. By opening the pressure relief valve 16 provided in the pressure relief pipe 15 using the valve opening setting device 17 based on the closing operation signal of the stop valve 14, the pressure in the drain tank 11 is prevented from increasing, and the drain discharge pipe is closed. It is effective in preventing backflow of condensate in IO.

As another embodiment, FIG. 3 shows a system configuration of a moisture separator and reheater circuit. The pressure equalizing pipe 12 is provided with a check valve 14 that operates based on a signal from a valve opening setting device 21, and a valve opening setting device 17.
．． 21 converts the pressure difference between the pressure in the reheater 8 and the pressure in the drainer/liter into a stain signal by the transmitter 18, and sends the setting device 1
9 and the comparator 20, and the output signal is used as the input signal.

According to this embodiment, by installing the setting device 19,
While ensuring the reliability of the equipment, the check valve 14 can be minimized.

〔Effect of the invention〕

According to the present invention, due to the phenomenon of reverse pressure between the inside of the reheater and the inside of the drain tank, it is possible to avoid clogging of condensed water in the heat transfer tubes, and to continuously A stable flow can be obtained within the heat exchanger tube.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of the atomic turbine, Fig. 2 is a system diagram of the reheating device layers according to an embodiment of the present invention, and Fig. 3 is a system diagram of the reheating device layers according to another embodiment of the present invention. be. lO...Drain discharge pipe, 11...Drain tank, 1
2... Pressure equalization pipe, 13... Bottom pipe, 14... Check valve, 15... Pressure relief pipe, 16... Pressure relief valve, 1
7...Valve opening setting device, 18<...Differential pressure transmitter, 19.
...Setting device, 20:112 picture book 3rd

Claims (1)

[Scope of Claims] 1. A reheating device in a reheating atomic couplant, characterized in that a check valve and a pressure relief system are provided in the piping connecting the reheater and the drain tank. 2. The reheating device according to claim 1, wherein a valve provided in the pressure relief system is operated to close or open in response to an opening or closing operation signal of the check valve. & Claims characterized in that the check valve and the valve of the pressure relief system are opened and closed by the difference between the pressure of the reheater and the pressure of the drain tank. The reheating device according to item 1. 4. Compare the differential pressure transmitter signal between the pressure of the reheater and the pressure of the drainer and the setter signal and use the comparator signal' to open and close the reverse valve and the valve provided in the pressure relief system. 4. The reheating device according to claim 3, wherein the reheating device is an operation signal.