JPS5942235B2 - Condenser oxygen injection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for injecting oxygen into a condenser of a boiling water nuclear power generation facility to prevent rust from forming on the inner surface of the condenser.

Generally, in boiling water nuclear power generation equipment, steam generated in the reactor pressure vessel is introduced into a turbine to drive the turbine, which drives a generator to generate electricity, and the steam discharged from the turbine is recycled. The water is introduced into a water tank and condensed to form condensate, which is then supplied to the reactor pressure vessel again.

By the way, such condensers and condensate. When rust occurs on the inner surface of the piping in the water supply system, this rust dissolves in the condensate and forms so-called crud, which is carried into the reactor pressure vessel and adheres to equipment inside the reactor pressure vessel, threatening its integrity. This will have an adverse effect and cause the cladding to become radioactive.

For this reason, conventional condensers and condensate were used. Oxygen is injected into the condensate in the water supply system to control the dissolved oxygen concentration in the condensate. It is configured to form a stable oxide film on the inner surface of the water supply system piping to prevent the occurrence of rust, and to remove crud, etc. from the condensate by providing a condensate purification system to purify the condensate.

However, the inside of the condenser is always maintained at a vacuum level of about 40 mmHg in order to exhaust the gas decomposed in the coolant.

Therefore, even if oxygen is injected into the condensate in the condenser, the concentration of dissolved oxygen in the condensate cannot be increased, and a sufficient rust prevention effect cannot be achieved.

Therefore, the amount of crud generated in this condenser is large.
There was a problem in that the load on the condensate purification system increased, the crud removal rate decreased, and the amount of crud brought into the reactor pressure vessel increased.

The present invention was made based on the above circumstances, and its purpose is to reduce the amount of crud generated in the condenser, reduce the burden on the condensate purification system, and reduce the pressure of the reactor. An object of the present invention is to obtain an oxygen injection device for a condenser that can reduce the amount of crud carried into a container.

That is, the present invention provides a condenser for a boiling water nuclear power generation facility, including: a condensate jet pipe arranged near a wall surface in a hot well of the condenser and having a jet hole opening toward the wall surface; a circulation pump that supplies condensate in the hot well into a condensate spout pipe and spouts the condensate from the spout hole toward the wall of the hot well; It is equipped with an oxygen injection mechanism that mixes the oxygen injected into the water jet pipe and the condensate.

Therefore, the injected oxygen is stirred and mixed with the condensate in this condensate jet pipe, and the condensate in this condensate jet pipe becomes a state in which oxygen is dissolved in a supersaturated state.

Then, the condensate containing supersaturated dissolved oxygen and the undissolved oxygen bubbles are ejected from the ejection hole of the condensate ejection pipe toward the wall surface of the hot well.

Therefore, the condensate in contact with the wall of this hot well flows, and near this wall there are condensate containing supersaturated dissolved oxygen and oxygen bubbles, and the surface of the wall of this hot well flows. It forms a stable oxide film and effectively prevents corrosion.

The present invention will be explained below according to an embodiment shown in the drawings.

First, the overall configuration of the boiling water nuclear power generation facility will be explained with reference to FIG.

In the figure, 1 is a reactor pressure vessel, and a reactor core is accommodated within this reactor pressure vessel 1.

The coolant, i.e. water vapor, generated within the reactor pressure vessel 1 is sent to the turbine 3 via the main steam pipe 2, driving this turbine 3, and driving the generator connected to this turbine 3 (Fig. (not shown) to generate electricity.

The steam discharged from this turbine 3 is then transferred to a condenser 4.
It is configured so that it is sent to the water and condensed to become condensate.

The condensate accumulated in the condenser 4 is sent to the condensate purification system 6 by the condensate pump 5 for purification, heated by the feed water heater 7, and then supplied to the reactor pressure vessel 1. It is composed of

Note that 8 is a water supply pump, 9... is a reactor recirculation pump, and 10 is a reactor coolant purification system.

The condenser 4 is provided with an oxygen injection device as shown in FIGS. 2 and 3.

The configuration will be explained below. In the figure, reference numeral 11 denotes the main body of the condenser 40, the lower part of which is formed into a hot well 12 for storing a predetermined amount of condensate.

In addition, in the upper part of this main body shell 11, a large number of cooling pipes 13,
...... are provided, and these cooling pipes 13
. . . It is configured so that cooling water, such as seawater, can flow therein.

The steam flowing in from the inlet 14 is then transferred to these cooling pipes 1.
3, it exchanges heat with seawater through
It is configured so that it flows out from 5.

Further, the inside of the condenser 4 is constantly maintained at a vacuum of about 40 mmHg in order to exhaust gas mixed in the steam.

This condenser 4 is provided with a condensate circulation mechanism 16.

The condensate jet pipe 17 is provided horizontally along the inner surface of the hot well 12, for example, the inner surface of the side wall of the hot well 12.

In the peripheral wall of this condensate jet pipe 17, there are a large number of jet holes 18, which are opened to face the inner surface of the side wall of the hot well 12. It is formed.

Reference numeral 19 denotes a circulation pump which sucks the condensate in the hot well 12 and supplies the condensate to each condensate jet pipe at a predetermined pressure.
7......... is configured to be supplied within.

Therefore, condensate is ejected from the ejection holes 18 of each condensate ejection pipe 17 toward the inner surface of the side wall of the hot well 12, and this side wall It is configured so that condensate near the inner surface flows.

Further, 20 is an oxygen injection mechanism, and 21...
... is the oxygen injection tube.

These oxygen injection pipes 21 are inserted into the condensate jet pipe 17, and a large number of injection holes 22 are formed in the peripheral wall thereof. ...is formed.

Reference numeral 23 denotes an oxygen supply source, which connects each of the oxygen injection pipes 21...
. . . is configured to supply oxygen at a predetermined pressure inside.

The oxygen supplied into these oxygen injection pipes 21 is ejected from the injection holes 22, and the condensate ejection pipes 17... ...The condensate flowing inside the condensate is mixed in the form of fine bubbles, and some of the oxygen dissolves in the condensate, and the oxygen that cannot be completely dissolved flows into the condensate jet pipe 17 along with the condensate.・・・・Blowout hole 1
8. It is configured to eject from.

Further, a dissolved oxygen concentration detector 26 is provided in the condensate in the hot well 12 and is configured to detect the dissolved oxygen concentration in the condensate.

Further, 27 is a control circuit, to which signals from the dissolved oxygen concentration detector 26 and flow rate detector 24 are input, and in response to these signals, the control circuit 27 adjusts the flow rate. A control signal is sent to the valve 25, which is configured to maintain the dissolved oxygen concentration in the condensate within the hot well 12 at a predetermined value.

One embodiment of the present invention configured as described above has the jet holes 18 of the condensate jet pipe 17.
Condensate spouts out from the hot well 12, and the condensate near the inner surface of the side wall of the hot well 12 flows.

Further, from the oxygen supply source 23, each oxygen injection pipe 21...
. . . Oxygen is supplied to the condensate jet pipe 17 from the injection hole 22 .
・・・・・・・・・It is spouted out and dissolved in the condensate flowing inside,
Maintain the dissolved oxygen concentration in condensate at a predetermined value.

Since the inside of this condenser 4 is maintained at a vacuum of about 40 mmHg, the above-mentioned dissolved oxygen concentration cannot be made very high, but the condensate jet pipe 17...
Since the condensate ejected from the ejection holes 18 . . . flows near the inner surface of the side wall of the hot well 12, it has a great anticorrosion effect and prevents rust, i.e., crud. occurrence can be reduced.

The reason will be explained below. First, the condenser 40 body shell 11
When we calculated the corrosion rate of carbon steel materials commonly used in carbon steel materials by varying the dissolved oxygen concentration in the water and the flow rate when this water was given a flow, we obtained the results shown in Figure 5. .

As is clear from this result, the dissolved oxygen concentration was reduced to 103pp.
If it is more than b, the corrosion rate can be reduced, but such a high dissolved oxygen concentration cannot be achieved in the condenser.

However, when the dissolved oxygen concentration is in the range of several tens to hundreds of pI), the flow rate is lower when the flow rate is 1.0 m/sec (shown by curve a in Figure 5) than when the flow rate is Q, 42 m/sec (shown by curve a in Figure 5). 5) shows a tendency for the corrosion rate to be lower, and the range of dissolved oxygen concentration that can be achieved with the condensate in the condenser 4 overlaps with this range of tens to hundreds of ppb. .

For example, when the relationship between the flow rate and the corrosion rate was determined when the dissolved oxygen concentration was 73 ppb, the results shown in FIG. 6 were obtained.

As is clear from the results shown in FIG. 6, the corrosion rate decreases as the flow rate increases within the above dissolved oxygen concentration range.

Therefore, as in this embodiment, the condensate jet pipe 17...
The corrosion rate is reduced by ejecting condensate from the jet holes 18 and giving flow to the condensate near the inner surface of the hot well 12, thereby reducing the amount of crud generated. It is possible to reduce the

In addition, in this embodiment, the condensate jet pipe 17...
Since the oxygen injection pipe 21 was inserted into the condensate, the oxygen injected in the form of bubbles into the condensate flows from the nozzle 18 along with the condensate. The condensate that is spouted out, sufficiently stirred, supersaturated and fully dissolved in the condensate, and the oxygen bubbles that remain undissolved are mixed into the inner surface of the side wall of the hot well 12. The corrosion rate can be further reduced because the corrosion rate is ejected.

As described above, the present invention provides a condenser for a boiling water nuclear power generation facility, including a condensate jet pipe that is arranged near a wall in a hot well of the condenser and has a jet orifice that opens toward the wall. , a circulation pump that supplies condensate in the hot well into the condensate spout pipe and spouts the condensate from the spout hole toward the wall of the hot well; and a circulation pump that injects oxygen into the condensate spout pipe. It is equipped with an oxygen injection mechanism that mixes the oxygen injected into the condensate jet pipe and the condensate.

Therefore, the injected oxygen is stirred and mixed with the condensate in this condensate jet pipe, and the condensate in this condensate jet pipe becomes a state in which oxygen is dissolved in a supersaturated state.

Then, the condensate containing supersaturated dissolved oxygen and the undissolved oxygen bubbles are ejected from the ejection hole of the condensate ejection pipe toward the wall surface of the hot well.

Therefore, the condensate in contact with the wall of this hot well flows, and near this wall there are condensate containing supersaturated dissolved oxygen and oxygen bubbles, and the surface of the wall of this hot well flows. Its effects, such as forming a stable oxide film and effectively preventing corrosion, are outstanding.

[Brief explanation of the drawing]

1 to 4 show one embodiment of the present invention, in which FIG. 1 is a schematic diagram of the overall configuration, FIG. 2 is a vertical sectional view of the condenser, and FIG.
The figures are a cross-sectional view of the condenser and a vertical cross-sectional view of a part of the condensate jet pipe in FIG. 4. Further, FIG. 5 is a diagram showing the relationship between the flow rate and the corrosion rate with respect to the dissolved oxygen concentration, and FIG. 6 is a diagram showing the relationship between the flow rate and the corrosion rate. 1... Reactor pressure vessel, 3... Turbine, 4... Condenser, 12... Hot well, 16... Condenser Water circulation mechanism, 17...
・Condensate jet pipe, 18...Blowout hole, 19...
...Circulation pump, 20...Oxygen injection mechanism, 21
... Oxygen injection tube, 22 ... Injection hole, 2
3...Oxygen supply source.

Claims (1)

[Scope of Claims] 1. In a condenser for a boiling water nuclear power generation facility, a condensate jet pipe that is arranged near a wall in a hot well of the condenser and has a jet hole that opens toward the wall. a circulation pump that supplies condensate in the hot well into the condensate spout pipe and spouts the condensate from the spout hole toward the wall of the hot well; and a circulation pump that injects oxygen into the condensate spout pipe. An oxygen injection device for a condenser, comprising an oxygen injection mechanism that mixes the oxygen injected into the condensate jet pipe with condensate. 2. The oxygen injection mechanism includes an oxygen injection tube inserted into the condensate injection pipe and having a plurality of injection holes, and sprays oxygen from the injection holes of the oxygen injection pipe into the condensate flowing inside the condensate injection pipe. A patented oxygen injection device featuring: