JPS5932760B2 - Nuclear power generation equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to equipment for nuclear power generation, and in particular includes one or more main steam generation boilers associated with a reactor core as well as one or more auxiliary steam generation boilers, It relates to a type of equipment in which the main and auxiliary steam generation boilers receive heat from the core.

For example, as described in Japanese Patent Publication No. 55-12558, in such nuclear power generation equipment, the auxiliary boiler can absorb approximately 20% of the maximum design thermal output of the reactor core from the design and safety standpoints. For example, if the main boiler system fails, a considerable amount of heat energy will be generated even if the reactor operation is stopped immediately, so there is no risk of causing serious damage to the reactor power generation equipment itself. Become.

Therefore, serious damage (accidents) due to considerable heat energy generated in emergency situations such as when the main boiler system breaks down.
To prevent this, auxiliary boilers must be designed to absorb some of such thermal energy and reduce it to a safe degree.

The steam thus generated is used in part to operate the reactor, and in part to drive an auxiliary turbine generator that increases the electrical output from the main turbine generator, which is driven by steam from the main boiler. It can be done.

However, as the size of such nuclear power generation facilities increases, the size and/or number of auxiliary turbine generators becomes such that they can absorb available energy such as steam from auxiliary boilers. In some cases, the need increases to the point that the benefits obtained from providing main and auxiliary boiler-turbine-generator systems can no longer be obtained to a sufficient degree.

As the size of nuclear power generation equipment increases, the need to increase the size and/or number of auxiliary turbine generators increases the need to increase the size and/or number of auxiliary turbine generators. can be alleviated to some extent by utilizing a significant portion of the energy of the steam from the auxiliary boiler to drive the auxiliary boiler.

Such a device is described in Japanese Patent Application No. 48-41206.

However, especially in nuclear reactor installations that have practically large power outputs, it is desirable for the auxiliary boiler to generate steam with sufficient energy to match the total energy that can be absorbed by the main refrigerant circulator and other reactor accessories. , it seems that there is actually substantial excess energy in this generated steam,
This excess cannot then be utilized effectively in the auxiliary turbogenerator unless it is undesirably large or undesirably large.

The object of the invention is to make advantageous use of the steam generated by the auxiliary boiler of such an installation, and the object of the invention is to use at least a portion of the steam from the auxiliary boiler to advantageous use. This is achieved by making the steam available for reheating in the associated steam circuit of the main boiler of the facility.

Therefore, according to the present invention, a reactor core and a main steam generation boiler and an auxiliary steam generation boiler each receiving heat from the core are provided, the main steam generation boiler driving the main turbine generator, and the main turbine generator driving the main turbine generator. A steam turbine having a number of turbine stages through which steam from the main steam generation boiler passes in sequence, and a steam reheater device connected between two of these turbine stages to reheat the steam from the main steam generation boiler. and connected to the steam reheater device, which is the auxiliary steam generation boiler, to reheat the steam from the main steam generation boiler in the steam reheater device with steam supplied from the auxiliary steam generation boiler. Provided is nuclear power generation equipment characterized by the following.

Naturally, the main power of the reactor equipment is to flow out steam from a point between the high pressure stage and the intermediate pressure stage of the turbine generator and to supply the flowed steam to a steam reheater between the intermediate pressure stage and the low pressure stage. It is known to reheat steam with steam in a boiler-turbine-generator circuit, in which a high-pressure stage passes the drawn steam to be discharged and a boiler feeding the high-pressure stage generates said drawn steam. must be designed.

According to the invention, therefore, the steam to be used for steam reheating is drawn off from the auxiliary boiler and does not pass through the high-pressure stage of the main turbine-generator, which supplies the high-pressure stage and the steam to it. A relatively large power output can be provided for a given size of the main boiler.

Each auxiliary boiler in an installation according to the invention may be of the free-flow type, but in a preferred embodiment of the invention each auxiliary boiler is of the recirculating type having an evaporator section associated with a steam drum; The drum is supplied with saturated steam, the water separated from such steam is recycled from the steam drum to the evaporator section, and each auxiliary boiler is not equipped with an economizer but is connected directly to the associated steam drum. It is equipped with a water supply inlet device.

Three embodiments of a steam circuit for a nuclear reactor according to the invention will be described below as examples.

Referring to FIG. 1, the reactor, which may be a helium-cooled high-temperature gas-cooled nuclear reactor, has a reactor core 9 that is housed within a pressure vessel 10 and that passes through the core to a main high pressure boiler and an auxiliary low pressure boiler. The boiler is preferably housed in a cavity 10A within the thickness of the wall of the pressure vessel.

The arrangement may be as shown, for example, in the patent application mentioned above.

One of the main boilers is designated at 11 in FIG. 1, and likewise one of the auxiliary boilers is designated at 12.

Refrigerant gas passing through the main boiler 11 is returned to the core by a gas circulator 13, and refrigerant gas passing through the auxiliary boiler 12 is returned to the core by a circulator 14, which is also electrically driven.

The circulator 13 is driven by a steam turbine 13A, and steam to this steam turbine 13A is supplied by an auxiliary boiler 12. A part of this steam exits from the steam turbine 13A and passes through the rear low-pressure steam turbines 15, 16, 17. used to drive (these low pressure steam turbines 15.1
6 and 17 drive the feedwater pumps for the main and auxiliary boilers, respectively, and the station load generator 18 which provides essential power to the reactor equipment.

) Another (usually major) portion of the steam from the steam turbine 13A is passed through a steam line 20 to a heater and air separator (not shown) provided for the feed water supplied to the main and auxiliary boilers 11, 12. The steam is then sent to a reheater 19 which reheats the steam before being sent through.

Any remaining excess of steam from the auxiliary boiler 12, some of which may bypass the steam turbine 13A through the pressure reducing bypass valve 21 and regulator 22, is transferred to the dump line 2.
It is released externally via 3.

The high pressure steam generated in the main boiler 11 is transferred to the steam turbine 24.
high pressure, intermediate pressure and low pressure stages 24A, 24B.

24C, which steam turbine 24 discharges to a condenser 25 and drives a main generator 26.

Before entering the low pressure stage 24C, the steam from the intermediate pressure stage 24B is reheated through a reheater 19, where this steam is converted into a portion of the steam from the auxiliary boiler 12 that is fed to the reheater 19. absorb heat from

Steam from steam turbines 15, 16, 17 is also routed to line 2.
7 to the reheater 19 to increase the reheated steam supplied to the low pressure stage 24C of the steam turbine 24, or can be discharged to the outside through the dump line 28.

Alternatively, steam line 27 may be connected directly to the downstream end of reheater 19, ie to the input of low pressure stage 24C.

The apparatus shown in FIG. 2 is similar to that shown in FIG. 1, except for the changes described below, and corresponding parts are designated by the same reference numerals as in FIG.

However, in the device shown in FIG. 2, the refrigerant gas circulator 13 associated with the main boiler 11 is electrically driven, and the steam from the auxiliary boiler 12, generated at correspondingly low pressure, is transferred to the steam turbines 15, 16, 17 and directly to a reheater 19 which reheats the steam with steam.

Also as shown, a variable frequency turbine generator consisting of a generator 29 is additionally provided, which generator is driven by a turbine 30 with a portion of the steam from the auxiliary boiler 12.
driven at variable speed.

Power from this variable frequency turbine generator may be used to drive the main and auxiliary refrigerant gas circulators 13,14.

As already explained, the main boiler 11 and the main turbine 24
By reheating the steam with the steam from the auxiliary boiler 12 in the main circuit consisting of the main boiler 11 and the high pressure stage 24A of the turbine 24 of given dimensions, a relatively large electrical power is derived from this main circuit. be able to.

Also as already indicated, the transfer of energy from the auxiliary boiler 12 to the main steam circuit in the reheater 19 can occur in the reactor without the need for the auxiliary boiler to correspondingly enlarge the turbine generator set 17.18. Approximately 20% of the maximum heat amount
(as desirable for safety).

Powering the main and auxiliary feedwater pumps and also the main and auxiliary refrigerant gas circulators (as shown in FIG.
3A or indirectly by a turbine generator set 29, 30 as shown in FIG. These ancillary functions and the high degree of assurance that continuous operation of the reactor can be maintained under emergency conditions not only help to reduce the will be done.

As described above, according to the present invention, by using a part of the steam from the auxiliary boiler to reheat the steam from the main boiler, even if the reactor power generation equipment becomes larger, the auxiliary turbine There is no need to increase the size or number of generators, and the steam from the auxiliary boiler is effectively utilized.

For example, in the conventional equipment described in the above-mentioned Japanese Patent Publication No. 55-12558, the electrical output of the main turbine generator is increased by an auxiliary turbine generator. As the size increases, it is necessary to increase the size or number of auxiliary turbine generators.

As mentioned above, the size of the auxiliary boiler is usually determined based on the designed maximum thermal output of the reactor core, so as the equipment becomes larger, the amount of steam generated by the auxiliary boiler also increases.

It is therefore a feature of the present invention to avoid undesirable increases in the size and/or number of auxiliary turbine generators and to obtain efficient use of excess energy.

That is, this excess energy is used to reheat the steam from the main boiler to ensure stable output from the main turbine generator.

In addition, as described in the above publication, the conventional method of extracting steam from a position between two stages of a multistage turbine generator and returning it to the pressure vessel in the reactor core for reheating does not allow pressure It is necessary to provide an insertion hole in the container, which is undesirable from the viewpoint of leakage prevention.

In contrast, the present invention does not require the provision of an insertion hole in the pressure vessel for reheating, and moreover, it effectively utilizes the excess heat energy generated from the auxiliary boiler. A special effect can be obtained compared to the previous one.

If an alternative or back-up steam source is available, such as an in-house legacy fuel boiler, it may be coupled via a steam line 31 with a normally closed valve as shown (and or 1 (in the case of the installation shown in FIG. 1, correspondingly at high pressure and connected via a further line 32 also equipped with a normally closed valve), steam is supplied instead of the steam normally supplied by the auxiliary boiler 12. be made available for supply.

This eliminates the need for back-up diesel- or gas-turbine-driven generators as would normally be required to maintain power supply to the equipment in the event of a power grid failure.

The apparatus shown in Figures 1 and 2 can be started up quickly without the need for substantial power from the grid.

At startup, the refrigerant gas main circulator 13 is connected to the auxiliary boiler 12.
is kept inactive until it supplies adequate steam to drive the steam turbines 15, 16, 17 (in the system of FIG. 1 this is done by bypassing the steam turbine 13A).

In general, the benefits resulting from having both main and auxiliary boilers driving main and auxiliary turbine generators are retained in the device according to the invention.

That is, for example, following operation of a nuclear reactor, the auxiliary boiler continues to function and the steam generated continues to drive the auxiliary boiler feedwater pump and the auxiliary turbine generator, but with appropriate pressure reductions and adjustments to avoid undesirable transients. bypasses the turbine driving the main refrigerant gas circulator (in the case of the apparatus of FIG. 1) and all excess steam is sent via dump line n to the appropriate dump condenser or flash tank.

In the installation shown in Figures 1 and 2, the auxiliary boiler 12 is shown to be of the once-through type.

This type of boiler has the benefit of minimizing the number of through holes required in the wall of the reactor pressure vessel 10, and typically each of the economizer, evaporator and superheater sections of such a boiler. Four holes per boiler are saved compared to high pressure boilers of the recirculation type (eg Liamont type) which require separate holes for the water supply lines to and from the equipment.

Such high-pressure recirculating boilers operate with a steam drum that is fed with saturated steam generated in the evaporator section of the boiler and that removes unevaporated water from evaporation for recycling to the evaporator section. Due to the high saturation temperatures associated with the steam drum as a result of the high pressures in the equipment it is constructed, direct water supply to the steam drum as a means of (indirectly) supplying water to the evaporator section is impractical and therefore the water supply is supplied to the steam drum via an economizer section of the boiler which preheats the feed water before entering the steam drum; the provision of this economizer section of the boiler for this purpose requires two through-holes in combination with the evaporator section. In addition, it is necessary to provide two combined insertion holes in the reactor pressure vessel.

If the steam from the steam drum is to be superheated, the boiler must further include a superheater section which requires two separate holes.

However, if the steam generated in the auxiliary boiler is mainly used to reheat the steam from the main boiler as in the case of Figures 1 and 2, the auxiliary boiler may be a high-pressure type. Therefore, the temperature in the steam drum (which is the saturation temperature and is related to the pressure) can be fed directly to the steam drum without first preheating it in the water saving section of the water supply. I can get it low enough so that I can do it.

It is therefore possible to provide a recirculating auxiliary boiler without an economizer section, thereby saving two pressure vessel openings associated with such an economizer.

An embodiment of the invention in which each auxiliary boiler of the power generation facility is of this recirculation type is shown in FIG.

This embodiment is the same as the embodiment shown in FIG.
The same symbols are used to represent corresponding components.

However, as shown in FIG.
is of the recirculating type (typically with a recirculation percentage in the range % to X) and is associated with a steam drum 12A in which water and saturated steam are in equilibrium.

The water supply inlet 12B to the auxiliary boiler is connected to the steam drum 12A, and the water from the steam drum (including make-up water from the inlet 12B) is fed to the auxiliary boiler 12, which simply consists of the evaporator section.
It is sent to by circulation pump 12C.

In the auxiliary boiler 12 the water is heated to form a mixture of water and saturated steam, and this mixture is transferred to the steam drum 1
2A, in which the saturated steam is separated from the water which is recycled by pump 12C.

The main portion of the steam from the steam drum 12A is normally sent to the steam reheating unit 19 described above, where the steam exits the intermediate pressure stage 24B of the main turbine before entering the low pressure stage 24C of the main turbine. used for reheating.

From the reheater unit 19, this main part of the steam from the steam drum 12A is fed via line 20 to the feedwater heater and to the air separator, in which its residual energy is utilized separately.

The remainder of the steam from the steam drum 12A is transferred to a low pressure steam turbine 15 (not shown) to a low pressure steam turbine 15 (not shown) to the main boiler 11, as shown in FIG. 16 (drives a water pump, not shown, which supplies water to the inlet 12B to the auxiliary boiler 12), 17 (drives the on-site load generator 18 that supplies essential power to the reactor equipment). It can be used to drive.

Utilization of the main part of the steam from the auxiliary boiler 12 in the steam reheater unit 19 and the turbine 15° 16.17
can be a low-pressure turbine driven with fully saturated evaporation, which means that the auxiliary boiler 12 can consist only of an evaporator section without any superheater section and also without an economizer section, i.e. the auxiliary boiler 12 and steam drum 12
The pressure (and therefore temperature) in A is low enough to allow the feed water inlet 12B to be connected directly to the steam drum 12A rather than through a boiler economizer, so each auxiliary boiler 12 has only one inlet. and an outlet (to which the evaporator section is connected), and the six through holes required per boiler if each boiler includes, in addition to the evaporator section, an economizer section and a superheater section. In comparison, only two through holes need to be provided in the pressure vessel surrounding the core and boiler.

Therefore, the evidence shown in Figure 3, where the auxiliary boiler is of the recirculating type and without the economizer and superheater section, is the same as that shown in Figures 1 and 2, where the auxiliary boiler is of the once-through type. It can be seen that compared to such installations there is no disadvantage in terms of the required number of through holes in the pressure vessel of the nuclear reactor.

On the other hand, as discussed with respect to FIG. 3, the use of a recirculation boiler as an auxiliary boiler provides certain practical benefits.

One benefit is that the provision of the steam drum 12A provides an improved energy storage system for the system, thereby providing a valuable additional safety margin in the event of an unscheduled reactor shutdown; This is particularly advantageous if the outage is caused by an unscheduled depressurization of the coolant circuit of the nuclear reactor.

Another benefit is that the heat absorption in the auxiliary boiler is primarily done in a latent manner, allowing the reactor coolant fluid to actually flow through the auxiliary boiler either against or parallel to the flow of water and steam. arises from that.

This greater flexibility in designing the circuit arrangement is particularly important for nuclear reactors such as high temperature reactors where the reactor coolant flows downward through the reactor core, and therefore where the nuclear coolant flows upward through the boiler. is the easiest to do.

A corresponding degree of flexibility is not readily available in once-through boilers.

That is, in that case the steam must be sufficiently dry and saturated as it exits the boiler, and the elevated temperature difference between the refrigerant and the steam in a saturated steam boiler is such that film boiling becomes a serious problem. type generator scheme to increase the heat transfer flux level.

A further benefit of using a recirculating type as an auxiliary boiler is the wide power range, which is particularly important when the steam from the auxiliary boiler is used for auxiliary (safety) function in some installations, as mentioned above. Overall, this type of boiler is inherently stable.

This invention can be implemented as follows.

(1) It has a reactor core, receives heat from the core, has a main steam generation boiler and an auxiliary steam generation boiler, has a large number of turbine stages through which steam from the main steam generation boiler passes sequentially, and has two turbine stages. A main turbine generator is driven by the main steam generation boiler, and the main turbine generator is connected between the main steam generation boiler and has a steam reheater unit that reheats the steam from the main steam generation boiler. A nuclear power generation facility in which an auxiliary steam generation boiler is connected to supply the steam to the steam reheater unit that reheats the steam.

(2) The equipment according to item 1 above, wherein the auxiliary boiler is a once-through boiler.

(3) The auxiliary boiler is of the recirculating type having an evaporator section combined with a steam drum, the steam drum being supplied with saturated steam and water separated from such steam being passed from the steam drum to the evaporator section. Recirculated to 1. 2. Installation according to claim 1, in which the auxiliary boiler is not equipped with an economizer and the water inlet device for the auxiliary boiler is connected directly to the steam drum.

(4) The reactor is a gas-cooled reactor, and there is a main refrigerant gas circulator that recirculates the refrigerant gas sent from the reactor to the main boiler to the core, and a main refrigerant gas circulator that recirculates the refrigerant gas sent from the reactor to the auxiliary boiler. 4. The installation according to any one of the preceding clauses, comprising an auxiliary refrigerant gas circulator adapted to recirculate the refrigerant to the reactor core.

(5) The installation of claim 4, wherein the main refrigerant gas circulator is powered by at least a portion of the steam supplied by the auxiliary boiler and is connected to discharge such steam to a reheater unit.

(6) at least one further steam turbine coupled to receive a portion of the steam supplied by the auxiliary boiler, with the reheater unit receiving a major portion of such steam; The equipment according to any of the above items 1 to 5, which is adapted to drive an auxiliary generator or a water supply pump for a main boiler or an auxiliary boiler.

Equipment according to paragraph 6 above, in which the steam discharged from the steam turbine on said side is mixed with steam from the main boiler immediately before or after the passage of the steam from the main boiler through the reheater unit. .

[Brief explanation of drawings]

Figure 1 is a schematic diagram showing the main and auxiliary steam circuits associated with a nuclear reactor, in which the refrigerant gas is circulated by a circulator driven by a steam turbine, and Figure 2 is a modified arrangement in which the refrigerant is circulated by an electrically driven circulator. FIG. 3 is a schematic diagram showing an arrangement similar to that of FIG. 2, using a different type of boiler arrangement as the auxiliary boiler. In the drawing, 9 is the reactor core, 10 is the pressure vessel, and 11 is the main boiler (
12 is an auxiliary boiler (auxiliary steam generation boiler), 13.14 is a gas circulator, 19 is a reheater unit, 26 is a main turbine, 24A is a high pressure stage, 24B is an intermediate pressure stage, 24C is a The low pressure stage, 26, is the main generator.

Claims (1)

[Claims] 1 has a reactor core and a main steam generation boiler and an auxiliary steam generation boiler that each receive heat from the core, the main steam generation boiler drives a main turbine generator, and the main turbine generator generates heat from the main steam generation boiler. a steam turbine having a number of turbine stages through which steam is passed sequentially and a steam reheater device connected between two of these turbine stages to reheat the steam, and a steam reheater device for reheating the steam; A nuclear reactor characterized in that a boiler is connected to the steam reheater device, and the steam from the main steam generation boiler is reheated in the steam reheater device with steam supplied from the auxiliary steam generation boiler. Equipment for power generation.