DE2342403A1 - NUCLEAR POWER PLANT - Google Patents

Description

WpL Ing. Θ. Koch / J ^ '*

Dr.T. Halbach *, ... _{r 1071}

8 MiIChMi 2 7 2nd AW 1973

240275

British Nuclear Design, ft Construction Limited Whetstone, Leicester, England

Nuclear power plant

The invention relates to nuclear power plants and in particular Such systems of this type »in which a nuclear reactor core not only has one or more main steam boilers but also one or more auxiliary «steam boilers are assigned» whereby both the main and auxiliary boilers with heat from the Nuclear reactor core are charged.

In such nuclear reactor systems, as described for example in patent ........,.> .. (patent application P 21 43 026.2 of the same applicant), it can be provided for important reasons that the auxiliary steam boiler or boilers approximately 20 % the projected max: to absorb the initial output heat output of the reactor core; and the steam generated in this way can be used partly for the reactor algae requirement and auxiliary drives and partly for driving Hi. If s turbo generators are used, which increase the electrical output power of the main turbo generators operated with the steam from the main steam keesela.

With increasing size of such a nuclear power plant however, the size and / or number of such auxiliary

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turbogenerator «!, if they are in the form of steam from the Auxiliary steam ponds are able to absorb available energy should »be increased to an extent at which the advantages originally intended by the arrangement of both main and auxiliary steam boiler and turbo-generator systems are no longer fully achieved *

This disadvantageous tendency can be mitigated to a certain point by the fact that one significant part the energy of the steam generated by the auxiliary steam boiler to drive the main KUhlmlttelumwälzvorrichtungen for the circulation of the cooling gas, which the heat from the heater core exhaust and the main steam room supplies, used; such a device is in patent ........... (patent application

P 23 18 111 * 5) suggested.

However, in the case of reactor systems with a really large output power in particular, there is a considerable excess energy Steam »which the auxiliary steam boilers produce preferentially should »on, compared with the oe and energy generated by the Main coolant circulation devices and through other reactor auxiliary drives and auxiliary functions can; and this excess is foreseen too great to be to be able to be used in auxiliary turbo-generators, provided that these are not provided in an undesirably large or undesirably numerous manner.

The invention thus relates to a power plant with a Nuclear reactor core that supplies heat to a main boiler and an auxiliary boiler, the main boiler being a Main turbo generator, which feeds a steam turbine with several, one after the other with the one coming from the main steam boiler Steam flowed through turbine stages as well as one between two Steam reheating or reheating unit provided for turbine stages for reheating or reheating the steam from the Has main boiler.

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The invention aims at an advantageous utilization of the the auxiliary steam boilers of such a system generated steam be made possible, while avoiding the difficulties outlined above, especially in large power plants.

For this purpose it is provided in a power plant of the type mentioned above according to the invention that the auxiliary steam boiler the reheating or reheating unit with steam for reheating or Reheating the steam from the main boiler feeds.

According to the basic idea of the invention it is thus provided that at least a part of the supplied by the auxiliary dsjnpfkessel Steam for steam »Steam reheating or reheating in the den The steam circuit of the system assigned to the main steam boiler is used will.

Steam-steam reheating or reheating is a matter of course known in the main steam boiler-turbo-generator-steam circuit of a nuclear reactor plant by generating steam from an between High and intermediate pressure stages of the turbo generator located point branches off and this branched off Danpf one between the intermediate pressure stage and a low pressure stage or reheater supplies. In this case, however, the high pressure stage and the one acting on this cooking pressure stage must then Steam boilers are designed so that they are able to generate or absorb the additional steam to be branched off. By doing now, according to the invention, that for steam reheating or post-heating used steam according to the basic idea of the invention is obtained from the auxiliary steam boiler and not from the High pressure stage of the main turbo generator flows, this main turbo generator can, for a given size of its high pressure stage and the main steam boiler, get a greater output power.

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The auxiliary steam boiler or boilers in a power plant system according to the invention can be of the one-time direct throughput type ;, However, according to a preferred embodiment of the invention it can also be provided that the auxiliary steam boiler is a recirculation steam boiler with an evaporator section is in association with an upper boiler to which the auxiliary steam boiler Saturation steam supplies and from which the water separated from the saturation steam into the evaporator section of the auxiliary steam boiler is recirculated, and that the feed water supply line Auxiliary steam boiler designed for the oil preheater is connected directly to the upper boiler.

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In the following, three exemplary embodiments of the steam circuits of nuclear reactor power plants according to the invention are based on
the drawing described; in this show:

1 shows the main and auxiliary steam in a schematic representation circuits in association with a nuclear reactor, in which the cooling gas is driven by steam turbines Circulating devices (circulators);

Flg. 2 shows a corresponding representation of the main and auxiliary steam circuits in a modified version, in which the circulation of the cooling gas is electrically powered circulators takes place;

FIG. 5 shows an arrangement corresponding to the arrangement from FIG. 2, however, using a different cauldron system as auxiliary or additional darning kettle "

The nuclear reactor shown in Fig. 1, which is
can act a helium-gas-cooled high-temperature reactor, has a reactor core 9 arranged in a pressure vessel 10, which is cooled with cooling gas that is circulated through the core and from here to high-pressure main steam boilers and low-pressure auxiliary steam boilers, which are preferably in recesses 10A housed in the wall of the pressure vessel
are. The arrangement can be in detail, for example, as in the patents mentioned at the beginning (patent applications P 21 4, 5, 02, 2). One of the main steam boilers is shown in FIG. 1 and denoted by the reference number 11; accordingly, one of the auxiliary steam boilers is also shown and denoted by the reference number 12
designated. The cooling gas which the main boiler has flowed through 11, or a blower IJ returned through a aasumwäl ζ device in the Roaktorcore; that through the auxiliary

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Steam boiler 12 conducted cooling gas is carried out in the same way a Wnwäl ζ before direction or a fan 14, which is electrically driven is fed back into the core.

The circulation device or the fan 15 is from a steam turbine IJA driven for which the steam from the auxiliary boiler 12 is delivered. After leaving the turbine 13A, part of this steam is used to drive further low-pressure steam turbines 15, 16 and 17 (which feed water pumps for the main and auxiliary steam boilers as well as a "house load" generator 18 drive, which generates essentially ele tric power for the reactor system). Another (and usually bigger) Part of the steam from the turbine 13A goes to a steam-steam re- or reheater unit 19 supplied (to the next will be returned below) before it is preheated and degassed for the feed water through a line 20 (not shown) the main and auxiliary steam boilers 11 and 12 are supplied. Any remaining excess steam from the auxiliary steam boiler 12 (some of this steam can be via a pressure reducing bypass valve 21 and a float 22 are bypassed the turbine 13A) is via a drain line 23 drained.

The one generated in the main steam keeeel 11 High-pressure steam, in turn, is fed to the high, intermediate and low-pressure stages 24A, 24b and 24C of a steam turbine 24, which opens on the output side in a condenser 25 and a main electric generator 26 drives. The one from the intermediate pressure stage 24b Incoming steam is used for reheating or reheating by a reheater 19 before it enters the low-pressure stage 24C passed, in which it absorbs heat from that part of the steam from the auxiliary drip boiler 12, which this reheater 19 is fed. The steam from turbines 15, 16 and 17 can also be fed to the reheater 19 via a line 27 to that of the low pressure stage 24c of the turbine 24 supplied reheated steam, or it can alternatively be discharged via a discharge line 28. Aiter-

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can line 2? also with the outlet end of the reheater 19 «i.e. directly with the inlet side of the low pressure stage 24C connected.

That in Pig. 2, with the exception of the system shown in « the following changes to the system from Flg. 1, and each other Corresponding parts are denoted by the same reference numerals in the two figures. In the arrangement according to Flg. 2 however, the cooling gas circulating devices assigned to the main Darapfkesseln II are 13 electrically driven, and the one generated by the auxiliary steam boiler with a correspondingly lower pressure Steam is fed directly to the turbines 15, 16 and 17 and the steam-steam Reheater 19 supplied. As also shown a turbo generator with variable frequency is also provided, which has a generator 29 with the variable Speed is driven by a turbine 30, which in turn is driven by part of the steam from the auxiliary steam boiler 12 is «The one from this turbo generator with changeable Frequency supplied electrical power can be used to drive the main and auxiliary cooling gas circulation devices 13 and 14.

As already mentioned, the steam reheating or reheating provided according to the invention in the main circuit containing the main steam boiler 11 and the main turbines 24 by means of steam from the auxiliary steam boilers 12 enables a greater electrical output power to be drawn from this main circuit for a given size of the main steam boiler 11 and the high pressure stage 24A of the turbine 24. As already indicated, the transfer of energy from the auxiliary steam boiler 12 to the main steam circuit in the reheater 19 means that the auxiliary steam boiler is able to absorb about 20 % of the maximum heat generated by the nuclear reactor can be designed as desired for safety reasons, without the turbo generator sets or sets 17 «18 having to be correspondingly large.

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The use of steam from the auxiliary steam pots 12 to drive the main and auxiliary feedwater pumps as well as to drive the main and auxiliary cooling gas circulation devices (either directly by means of steam turbines IJA as in Fig. 1, or indirectly by means of turbo generator sets 29, 30 as in Pig 2) not only has a supporting effect in the sense of reducing the required size of the auxiliary turbo generator sets 17 ”. ₄ IB but also provides an advantage hinsich ¹ borrowed security and reliability, in that thereby a continuous operation of these additional functions and of the nuclear reactor is ensured under emergency with a high degree of safety. Palis an alternative or emergency Darapfquelle such as a fossil fuel-operated steam boiler for the power plant's own needs is available, this can be in the manner shown via a steam line 31 - with a normally closed valve (and in the case of Pig high pressure via a further line 32 (which in the same way has a normally closed valve) in order to optionally supply steam normally supplied by the auxiliary steam boiler 12 as a representative. Emergency generators with diesel or gas turbine drives can then be dispensed with, as are normally required to maintain the electrical energy supply for the system under certain circumstances where it is disconnected from the electrical network system.

The in Figs. 1 and 2 allow arrangements shown a quick start-up of the system without any significant Supply of electrical power from the network is required. In the start-up state, the main cooling gas circulation devices 13 kept switched off (in the device according to FIG this is done by shunting the steam turbines 13A) until the auxiliary steam boilers 12 supply sufficient steam to drive the steam turbines 15 »16 and 17. In general, the

(in the patents mentioned. Patent applications

P 21 43 026.2 and P 23 18 111.5 described) advantages such as

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they result from the presence of both main and auxiliary steam pressure boilers result as a drive for main and auxiliary turbo-generators, obtained in the arrangements according to the invention. So would, for example, the auxiliary steam boiler after a reactor trip continue to function and the steam they generate continues to serve as the feedwater purapen for the auxiliary steam boilers and drive the auxiliary turbo-generators; however, the steam would shunted past the drive turbines for the main cooling gas circulation devices (in the arrangement according to Pig. I) under suitable pressure reduction and temperature control, in order to avoid undesirable jumping processes, and excess Steam would pass through drain line 23 to a suitable drain condenser or Kondeusat collector.

In the case of the FIGS. In the systems shown in FIGS. 1 and 2, the auxiliary steam pressure boilers 12 are shown as those of the single throughput type. This type of steam boiler has the advantage that the number of necessary passages in the wall of the nuclear reactor pressure vessel 10 can be largely reduced; In the typical case, there is a saving of k bushings per steam boiler compared to high pressure steam boilers with recirculation (for example of the Lamont type), which require separate bushings for the feed lines to and from the preheater, evaporator and superheater sections of such steam boilers. Such high-pressure recirculation steam boilers are operated in connection with an upper boiler to which saturation steam is supplied from the evaporator section of the steam boiler and in which non-evaporated water is separated from the steam for return to the evaporator section. Because of the high saturation temperature prevailing in the upper boiler as a result of the high pressure in the system, the direct feed water supply to the upper boiler, as a means of (indirect) supply to the evaporator section, is impractical; the

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Feed water is therefore fed to the upper boiler via a preheater section supplied to the steam boiler, in which the feed water is preheated before it enters the upper boiler; the preheater section of the steam boiler provided for this purpose requires two associated bushings through the Reactor pressure shell «in addition to the two the evaporator section assigned bushings. Palis the steam from the upper boiler is to be overheated, the steam boiler must also have a superheater section, for which two more Implementations are necessary.

However, if the steam generated in the auxiliary boilers is mainly for steam-steam reheating or heating of the steam from the main boilers is to be used, as shown in Figs. I and 2, the auxiliary boilers do not need the high pressure type to be and the temperature in the upper boiler (at which it is the saturation temperature dependent on the pressure) can therefore be sufficiently low that the feed water can be fed directly to the upper boiler without a previous one Preheating in a pre-heater section of the steam boiler. In this case, an auxiliary steam boiler from the recirculation

provided type, but without a preheater section, y be such that the two bushings otherwise associated with such a preheater section through the pressure envelope can be saved.

An embodiment of the invention in which the or the Auxiliary steam boiler of a power plant is designed in this way as a recirculation boiler, is illustrated in FIG. 3. This embodiment corresponds globally to that in FIG. 2, and parts of the two embodiments that correspond to one another are denoted by the same reference numerals. As can be seen, however, the individual auxiliary steam boilers are shown in FIG 12 of the recirculation type (where the recirculation ratio typically in the range of 2/1 to 4/1),

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and each auxiliary steam boiler is assigned an upper boiler 12A, in which water and saturated steam are in equilibrium with each other stand. A feed water supply line 12B for the auxiliary steam boiler is connected to the upper boiler 12A; water from the upper boiler (including replacement water from the inlet pipe 123) is connected to the auxiliary steam boiler by an ISnwälzpurape 12C 12 supplied, which consists only of an evaporator section. In the steam boiler 12, water is generated a mixture of water and saturated steam is heated; this mixture is returned to the top kettle 12A t, where the saturation steam and water are separated; the water is returned by means of the pump 12C. A main part of the steam coming from the upper boiler 12A normally goes to the above-mentioned steam-steam reheater unit 19 supplied, where it is necessary to reheat or reheat the emerging from the intermediate pressure stage 24B of the main turbine Steam before it enters the low-pressure stage 24C of the Steam turbine is used. Of the reheating or reheating this main part of the steam supplied by the upper boiler 12A is fed via a line 20 feed water preheating and degassing, in which its remaining energy is more widely used. The remaining part of the steam from the upper boiler 12A can as indicated in Fig. 3 (and corresponding to the preceding Descriptions of Fig. 1 and 2) to drive corsetry pressure turbines 15 (which in turn drive not shown feed water pumps for the main steam boiler 11) 16, (the For their part, pumps, not shown, for the feed water supply to the EInIaB 12B of the. Drive auxiliary steam boiler 12) and 17 serve (which in turn drive "house load" or internal demand generators 18, which the essential electrical power requirement for the reactor plant) *

The use of a major part of the steam from the auxiliary boilers 12 in the steam reheater unit I9, as well as the

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it said that the turbines 15, 16 and 17 were easily saturated with steam can be driven low-pressure turbines, mean that the auxiliary steam boiler 12 can only consist of evaporator sections, without superheater sections and even without preheater sections, since the pressure prevailing in the steam boiler 12 and in the upper boiler 12A (mad thus the Temperature) can be sufficiently low, around the feed water inlet pipe 12B to be connected directly to the upper boiler 12A instead of via a preheater section of the steam boiler. Each auxiliary steam boiler 12 has only one inlet and one outlet (to or from its evaporator section). and accordingly only requires two passages through the pressure envelope surrounding the reactor core and the steam boiler, compared with the six passages required for each steam boiler would be, if each steam boiler, in addition to the evaporator section, a preheater section and a superheater section exhibited.

It can be seen from this that a system of the type shown in FIG shown, in which the auxiliary steam boiler is of the recirculation type but have no preheater or superheater sections, compared with a system according to the Pigg. 1 or 2, in which the auxiliary steam boiler of the type with single direct throughput are not a disadvantage with regard to the required number of passages through the reactor pressure vessel owns. On the other hand, there are very specific advantages that result from the use of borrowing boilers as an auxiliary steam boiler as described with reference to FIG. 3, grown up. One advantage is that the presence of the upper boilers 12A is an improvement in energy storage of the system provides a valuable additional safety measure in the event of an unforeseen reactor shutdown represents; this is particularly advantageous if the shutdown is due to an unforeseen drop in pressure of the

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Reactor cooling circuit resulted Another advantage results from the fact »that, since the heat absorption in the auxiliary steam boiler mainly in the field of latent. Heat takes place, the reactor coolant flow through the auxiliary steam boiler could not be chosen either in countercurrent or parallel to the direction of flow of the water and steam. This greater flexibility when planning the Krelslaufvorrichtungen be of importance, especially in reactors such as the high-temperature reactor ^ at which the reactor coolant flow goes down through the reactor.jore and therefore the easiest way is to flow the reactor coolant upward through the boilers. With steam boilers of the one-time type Direct throughput, a comparable flexibility is less easy to achieve, since in this case the steam at Leaving the boiler must be fully saturated and the increased temperature difference between coolant and dry Steam in the saturation boiler the level of heat transfer flow in the direct flow generator in an area raises where film or boundary layer boiling occurs become a significant problem. Another advantage of using a recirculation steam boiler as an auxiliary steam boiler is due to the stability inherent in this type of steam boiler over wide ranges of output power, which is particularly significant if, as mentioned above, the steam from the auxiliary steam boilers is partly used for auxiliary «{safety) functions the system is used.

Patent claims:

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Claims (1)

Claims (1 .J nuclear power plant with a Kerareaktorcore, the heat to a main steam boiler and an α auxiliary steam boiler. fert, whereby the main steam boiler has a main turbo generator which feeds a steam turbine with several successive units with the steam coming from the main steam boiler through « flowed turbine stages as well as a steam reheater or reheater unit provided between two turbine stages for reheating or reheating the steam from the main steam boiler has “characterized” that the auxiliary steam boiler (12) the reheater or reheater unit (19) with steam for reheating or reheating of the Feeds steam from the main boiler (11). 2. Plant according to claim 1 _# characterized in that the auxiliary steam boiler (12) is a steam boiler with a one-time direct throughput 1st (Pigg. 1 and 2). 5 »System according to claim 1 * characterized without t, that the auxiliary steam boiler (12, Fig. 3) is a recirculation steam boiler with an evaporator section in association with an upper boiler (12A) to which the auxiliary steam boiler (12) Settling steam supplies and from which that of the saturation steam separated water is recirculated into the evaporator section of the auxiliary boiler, and that the feed water supply line (12B) for the auxiliary steam boiler (12A), which is designed without a preheater, is connected directly to the upper boiler (12A) is· 409810/0459 BAD OBJOLNAL 4. Plant according to one or more of claims 1 to 3, characterized in that the nuclear reactor (9 # ¹ O) is a gas-cooled reactor and a main XUhlgasumwälzvörriehtung (13), which circulates the cooling gas through the reactor cora (9) the Hauptdanpfkesaei (11) and through it and back again into the reactor core (9), as well as an Eilfs-Kühlgasumwill ^ device (14-) which circulates the reactor cooling gas through the core and through the auxiliary steam boiler (12). 5. Plant according to claim 4, characterized in that that the main Kühlgasumwälzvorrichkung (13, Fig · I) a Steam turbine (1; 5A) having at least one part of the steam supplied by the auxiliary steam boiler (12) is operated and this steam is used on the outlet side. Reheater unit (I9) supplies " 6. Plant according to one or more of claims 1 to 5 **, characterized in that ^ at least one further steam turbine (15 to 16, y $) , which with a smaller part of the steam supplied by the auxiliary steam boiler (12) (its Main part of the reheater or reheater unit (19) is supplied) and is used to drive an electrical auxiliary generator or a feed water pump for the main or auxiliary steam boiler. 7. Plant according to claim 6, 'characterized by g e k e η η, that the exhaust steam of the additional steam turbine (15 to 17, 30) with the steam from the main steam boiler (11) immediately before or after it has passed through the reheater or reheater unit (I9) is mixed (at 27). 4098 10/04 59 BAD ORiGlNAi Blank page