DE2516378A1 - ARRANGEMENT FOR CONTROLLING THE PRESSURE OF THE PRESERVED STEAM IN AN HTGR POWER PLANT - Google Patents

Description

PATENT LAWYERS

DIPL.-ING. LEO FLEUCHAUS DR.-ING. HANS LEYH

DIPL.-ING. ERIfoT RATHMANN

β MÖNCHEN 71. April 14, 1975

McfcMoratrae «42

WS4P-1274

Westinghouse Electric Corporation Westinghouse Building Gateway Center Pittsburgh, Pennsylvania, V. St. A.

Arrangement for controlling the pressure of the reheated

Steam in an HTGR power plant

The invention relates to an arrangement for controlling steam turbines in a power plant, which is equipped with a gas-cooled High-temperature reactor is provided (HTGR power plant) and has several steam generators, each with a reactor cooling gas circuit Extract heat and transfer superheated steam to a common main steam collector and reheated steam give a common collector for reheated steam.

In an HTGR power plant, a cooling gas (helium) is constantly circulated through the reactor while the reactor is in operation. In an HTGR power plant with an indirect circuit

flows

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the reactor cooling gas flows from the reactor to the primary side of several steam generators, which extract heat from the gas and

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reheated steam can be fed with steam. Of the Steam flow through line 131 is through a spill valve 132 controlled. An auxiliary overflow line 133 leads from the collector 125 for reheated steam Another point at which steam can be released, in the embodiment shown in Fig. 1 to the outside. Of the Steam flow in line 133 is controlled by an auxiliary spill valve 134. The overflow valve 132 is by means of a preferably electro-hydraulic actuator 135 hydraulically moved into a position by an electrical signal is determined which is applied to the actuator 135 via a line 136. The valve 134 is by means of a preferably electro-hydraulic Actuator 137 is moved to a position which is determined by an electrical input signal transmitted via the line 138 is applied to the actuator 137.

In the present description it is assumed that the quick-acting closing valve 126 and the throttle valve 106 are open, if nothing else is said. As a result, the flow of steam through the turbines 111 and 112 is controlled by the medium pressure regulating valve 127 and the steam flow through the turbine 108 controlled by the high pressure regulating valve 107. A signal generator 170 gives a load signal that corresponds to the target output power of the turbo generator A corresponds, via the line 171 to a loading control system 172, the emits a signal via a line 173 which corresponds to the setpoint value of the application steam flow rate through the turbines 111 and 112 or the medium pressure control valve 127 corresponds, and also emits a signal via a line 174 that the The desired position of the high pressure control valve 107 corresponds. An electro-hydraulic actuator 175 brings the valve 127 in such a position that the flow of steam by the turbines 111 and 112 that by the signal in FIG Line 173 corresponds to the setpoint shown. An electro-hydraulic actuator 176 brings that

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Adjustment of a medium pressure control valve controlled. Simultaneously the overflow valves, which are arranged in the overflow lines, must be those of the medium and low pressure turbines are assigned, are set so that the desired minimum steam flow through the reheater the steam generator is maintained even if the Steam flow through the medium and low pressure turbine is less than said minimum steam flow.

In a known system for controlling the application of a turbo generator in an HTGR power plant are a control valve and an overflow valve connected to one another in such a way that one valve opens when the other closes. in the Ideally, the two valves are designed so that their total steam flow resistance is the same in every setting, so that with a constant amount of the steam discharged from the reheaters, the steam pressure in the collector for the reheated steam remains essentially constant. In practice, the output from the reheaters The amount of steam may vary or the total steam resistance of the control valve and the overflow valve fluctuate, so that the steam pressure in the collector for the reheated Steam fluctuates. In the event of a sudden discharge to a turbo generator, a safety valve can open to relieve the Relieve the collector for the reheated steam from excessive steam pressure. This safety valve closes again when the vapor pressure has dropped to a predetermined value. However, this on-off control can lead to that after the sudden discharge of the turbo generator, the steam pressure in the collector for the reheated Steam fluctuates, which can affect the accuracy of controlling the flow of the reactor coolant gas.

The object of the invention is now to provide an arrangement that can be used in any turbine provided HTGR power plant to control the steam pressure in the collector

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can be used for the superheated steam, whereby undesirable differences between the steam flow rates occur through the overflow lines assigned to the turbines.

To solve this problem, the invention creates an arrangement for controlling the steam pressure in a collector, to which reheated steam is fed from a reheater of a steam generator, which can extract heat from a reactor cooling gas flow and deliver superheated and reheated steam to a turbo generator, which has at least one high-pressure turbine and at least has a medium or low pressure turbine, the gas being circulated through a high temperature nuclear reactor and the steam generator by means of a circulating fan which is rotated by an auxiliary steam turbine through which a part of the steam to be supplied to the inlet of the reheater passes, and where the Collector for the reheated steam is connected so that steam can flow from the collector to a condensing device along a first path, which has the medium or low-pressure turbine, and along a second path, which has an overflow line, and wherein the Control arrangement has a valve device which is used to regulate the steam flow through the overflow line, a signal generator for generating a first signal that indicates a setpoint for the steam flow through the medium or low pressure turbine, a pressure transmitter for generating a second signal that corresponds to the Actual value of the steam pressure in the collector for the reheated steam corresponds, and a signal generator for generating a third signal indicating a setpoint value for the steam pressure in the collector for the reheated steam, characterized in that a control system is provided which is dependent on the The first signal by adjusting the valve device controls the steam flow through the overflow line so that the steam flow through the reheater is the same

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is a predetermined minimum flow when the actual and the desired steam pressure correspond to a predetermined low load value and the desired value of the steam flow through the medium or low pressure turbine is less than the predetermined minimum steam flow, and when there is a difference between the second and the third signal as a function of the second and third signal changes the vapor flow through the main overflow line proportionally to the difference between the second and the third signal in the sense of reducing this difference.

If the setpoint of the steam flow through the middle or Low-pressure turbine is below a predetermined minimum value, the arrangement according to the invention regulates the steam flow through an overflow line arranged between the collector for the reheated steam and a condensation device in such a way that the total amount of steam emerging from the collector for the reheated steam corresponds to the predetermined minimum steam flow. At a lower output power, the predetermined minimum steam flow through the reheater is maintained so that the steam generator can work properly and is protected. To control the steam pressure in the collector for the reheated steam, the steam flow through the overflow line is changed in a predetermined ratio to a difference between the actual and the desired value of the steam pressure in the collector for the reheated steam in the sense of reducing this difference, so that the control of the amount of reactor cooling gas circulated per unit of time is facilitated.

A preferred embodiment of the invention is described below with reference to the accompanying drawings. In these shows

1 shows a block diagram of two turbo-generators

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having HTGR power plant, which with the invention Arrangement for controlling the steam pressure in the collector for the reheated steam an embodiment of the invention is provided, and

Figure 2 is a block diagram of an overflow control system according to one embodiment of the invention.

FIGS. 3 A and 3 B illustrate certain signals generated by the The spill control system shown in Fig. 2 is generated will.

In Fig. 1 three circulation fans are shown, which the helium used as cooling gas through a gas-cooled high-temperature reactor 100 and a steam generator assigned to it

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turn the helium circulation fan 102 B or 102 0. Through the dashed line which the auxiliary steam turbine ASTC rait connects the helium circulation fan 102 0, it is indicated that these two parts are connected to one another in rotation are. A control valve is assigned to each auxiliary steam turbine, which the steam flow through the auxiliary steam turbine and thus also controls the flow of the reactor cooling gas through the corresponding helium circulation fan. From the auxiliary steam turbine ASTA, the exhaust steam is fed to the inlet of the reheater RHA. From the auxiliary steam turbines ASTB and ASTC, the exhaust steam is fed to the inlets of the associated reheater RHB and RHC. Between the exhaust steam collector 109 and the inlet of each of the reheaters RHA, RHB, RHC an overflow line is connected, which is provided with an overflow valve. If the the total amount of steam supplied to the exhaust steam collector 109 is greater is than the total steam flow through the auxiliary steam turbines, the overflow valves assigned to these are set in such a way that the excess steam from the overflow lines is fed directly to the inlets of the reheater. A collector 125 for the reheated steam is fed from the outlets of the reheater with reheated steam. When using more than three Steam generators are the reheater, the helium circulation fan and the auxiliary steam turbine associated with each additional steam generator also in the above switched manner.

This can from the collector 125 for reheated steam The inlet of the medium-pressure turbine 111 is fed through a quick-acting closing valve 126 and a medium-pressure control valve 127 will. The exhaust steam of the turbine 111 is in the line 128 fed to the inlet of the low-pressure turbine 112. Exhaust steam from the turbine 112 is via a line 129 a Condenser 130 is supplied. The condenser I30 can flow from the collector 125 for

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designated. Overflow lines 114 and 115 lead from the main steam collector 105 to the Ab dam ^ s animier 109. The steam flow in the lines 114 and 115 is controlled by an overflow valve 116 and 117, respectively. From the main steam collector 109, steam can also flow to the exhaust steam collector 109 via a throttle valve 118, a high-pressure regulating valve 119 and a high-pressure turbine. The high pressure turbine rotates on the same shaft 121 as the medium pressure turbine 122, the low pressure turbine 123 and a generator 124. These parts are referred to as turbo-generator B below. The steam generator works most advantageously when the steam flow through the superheater does not drop below a desired minimum value. If the total steam flow through the turbines 108 and 120 is less than this minimum value, the overflow valves 116 and 116 are adjusted so that the steam flow through the superheaters is kept at the desired minimum value. If, on the other hand, the total steam flow through the turbines 108 and 120 is greater than the desired minimum value, the valves 116 and 117 are closed. The flow through the reheater must also not fall below a certain desired minimum value. In the present description it is assumed that the desired minimum steam flow rate is selected so that the power plant can generate 25 ° of its maximum output with this steam flow rate. Of course, depending on the design of the steam generator, the desired minimum steam flow rate can also correspond to a different output power. It should also be noted that instead of each of the throttle valves 106 and 118 and each of the control valves 107 and 119, a group of such valves is provided in practice.

An auxiliary steam turbine ASTA is supplied with steam from the exhaust steam collector and rotates the helium circulation fan 102 A. The auxiliary steam turbines ASTB and ASTC are also fed with steam from the exhaust steam collector 109

- · · ' turn

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rotate the helium circulation fan 102 B or 102 G. The dashed line which connects the auxiliary steam turbine ASTC with the helium circulation fan 102 G indicates that these two parts are connected to one another in rotation. Each auxiliary steam turbine is assigned a control valve which controls the flow of steam through the auxiliary steam turbine and thus also the flow of the reactor through the corresponding helium circulation fan. The exhaust steam is fed from the auxiliary steam turbine ASTA to the inlet of the reheater RHA. Of the Hilfsdampfturbi- ASTB and ASTC NEN the exhaust steam is fed to the inlets of the associated reheater RHB and RHC. An overflow line, which is provided with an overflow valve, is connected between the exhaust steam collector 109 and the inlet of each of the reheaters RHA, RHB, RHC. If the Abdampfsammler the 109 total amount of steam supplied is greater than the Gesamtdampfdurchfluß "by the Hilfsdampfturbi- NEN _s associated with these relief valves are set so da2 the excess steam is fed from the overflow lines directly to the entrances of the reheater. A collector 125 for the reheated steam is fed with reheated steam from the outlets of the reheater. If more than three steam generators are used, the reheater, the helium circulation fan and the auxiliary steam turbine, which are assigned to each additional steam generator, are also switched in the manner described above.

From the collector 125 for reheated steam, this can be fed to the inlet of the medium-pressure turbine 111 through a quick-action valve 126 and a medium-pressure regulating valve 127. The exhaust steam from the turbine 111 is fed in the line 128 to the inlet of the low-pressure turbine 112. Exhaust steam from the turbine 112 is fed to a condenser 130 via a line 129. The condenser 130 can flow from the collector 125 for

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Deliver superheated steam and reheated steam to a turbo generator. To ensure proper operation and protection of the steam generator, a certain minimum steam flow rate must be maintained in the superheater and the reheater of each steam generator. Usually the minimum steam flow in all steam generators is equal to the steam flow required to produce 25% of the maximum output of the power plant. Overflow lines are therefore connected in parallel to the various turbines, which make it possible to maintain the total minimum steam flow in the steam generators even if the steam flow through the turbines is less than said minimum steam flow.

A helium circulation purape is assigned to each steam generator, which circulates a cooling gas through the reactor and the steam generator and which circulates a rotary drive from an auxiliary steam turbine can get. When using auxiliary steam turbines for this purpose, part of the steam is consumed in the auxiliary turbine used to drive each helium circulation pump, which flows to the reheater of the associated steam generator. The reheaters are on the outlet side with connected to a collector for the reheated steam. From this the reheated steam can along three Because of pouring. The first route includes a control valve and a reduced pressure turbine. The second way contains a main overflow line, which leads through a condenser, and a main overflow valve. The third way involves an auxiliary overflow line in which a valve is arranged. By regulating the steam pressure in the collector for Reheated steam, the control of the speed of the auxiliary steam turbines is improved, so that the flow of the cooling gas for the reactor can be better controlled.

To control the loading of the turbo generator, the steam flow through the high pressure turbine is controlled by appropriate

j. setting

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Control valve 107 in a position which corresponds to the signal in line 174. As indicated below, effected the application control system 172 by the delivery of the application setpoint signal via the line 173 and the Valve position setpoint signal via line 174 that the output power of the turbo generator A corresponds to the load signal in the line 171. The signal generator 170 can over the line 171 emit a manually adjustable output signal, or it can come from a program-controlled digital computer exist, which calculates a power requirement, which is implemented by an assigned digital-to-analog converter and is then delivered to line 171. A signal generator 142 emits a signal to line 143 which corresponds to the setpoint steam pressure in the collector 125 for the reheated steam is equivalent to. The signal generator 142 can use the line 143 emit a manually adjustable output signal or he can consist of a program-controlled digital computer that calculates the target steam pressure, which is then assigned by an assigned Digital-to-analog converter is implemented and delivered to line 143. The actual vapor pressure in the collector 125 for the reheated steam is measured with a pressure transducer 144, the output via line 145 Output signal corresponds to the actual steam pressure. Dependent on from the target pressure signal emitted via line 143, the actual pressure signal output via line 145 and the application setpoint signal output via line 173 An overflow control system 146 generates the input signals provided on lines 136 and 138 for the actuators.

A quick-acting valve 147 and a medium-pressure control valve 148 allow steam to enter the medium-pressure turbine 122 flock. Exhaust steam from the turbine 122 flows through a line 149 to the inlet of the low-pressure turbine 123. The steam emerging from the low-pressure turbine 123 is fed to a condenser 151 in a line 150.

• 12 - Condensed

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Condensed feed water flows from the condensers 130 and 151 via a line 152 of a series of (not shown) Pumps and preheaters closed. The preheated and pressurized feed water is via line 103 the Supplied to steam generators.

A main overflow line 153 is located between the collector 125 for the reheated steam and the condenser I51 arranged, to which a main overflow valve 154 is assigned, which controls the flow of steam in the line 153. One Auxiliary overflow line 155 leads from the collector 125 for the reheated steam to another point at which Steam can be given off, in the embodiment according to Pig. 1 outdoors. The auxiliary overflow line 155 is a Auxiliary overflow valve 156 assigned to the steam flow in line 155 controls. With the help of an electro-hydraulic Actuator 157, the valve 154 is brought into a position which is determined by a signal that is applied via an input line I58. With help of a Electro-hydraulic actuator 159, the valve 156 is brought into a position which is determined by a signal which is applied via an input line 160.

In the following description it is assumed that the trip valve 147 is open, unless otherwise specified is. As a result, the intermediate pressure control valve 148 controls the flow of steam through the turbines 122 and 123. A signal generator 161 emits a signal via a line 162 which corresponds to the setpoint value of the steam flow through the turbines and 123 corresponds. Depending on the one on the line 162 emitted signal sirells an electro-hydraulic Actuator 163 sets the medium pressure control valve I48 in such a way that that the steam flow through the turbines 122 and 123 is effective is equal to the setpoint. The signal generator 161 can emit or emit a manually adjustable output signal

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be a program-controlled digital computer with a digital-to-analog converter assigned. A signal generator 163 that emits a manually adjustable output signal or from a program-controlled one There is a digital computer with a digital-to-analog converter assigned to it, is via a line 164 from a signal which corresponds to a desired value of the steam pressure in the collector 125 for the reheated steam. In Dependence on the actual pressure signal in line 145 »dem Setpoint pressure signal in line 164 and the steam flow setpoint signal on line 162 creates a spill control system 165 those delivered via lines 15Ö and 160 Input signals for the actuators. This is shown below described.

The quick-closing valves 126 and 147 and the medium pressure control valves 127 and 143 are shown in Figure 1 as individual valves shown, but it will be understood that in practice each of these valves will usually be replaced by a valve group is provided.

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2 shows that the overflow control system 146 controls the steam flow in the main overflow line 131 and the auxiliary overflow line 133 as a function of the overflow setpoint signal in the line 173 such that the total steam flow through the turbines 111 and 112 and the overflow lines is equal to Half the desired minimum steam flow through the intermediate superheaters is when the steam flow through the turbines 111 and 112 is less than half the desired minimum steam flow. Since the desired minimum steam flow rate is sufficient to generate 25 7 ° of the maximum output of the power plant, and the two turbo-generators A and B have the same maximum output, half of the desired minimum steam flow rate is sufficient to produce 25 % of the maximum output of one of the turbo-generators. The steam flow through the turbines 111 and 112 is therefore less than half the desired minimum steam flow when the turbo generator A is switched off, or when the turbo generator A is accelerated to the synchronous speed, or when the output power of the turbo generator A is less than 25 i in synchronous operation » Is its maximum output and after a sudden unloading of the turbo generator A producing more than 25 # of its maximum output. the overflow control system 146 changes the steam flow through one of the overflow lines 131 and 133 in the sense of reducing this difference. Typically, the spill control system 146 keeps the auxiliary spill valve 134 closed and alters the steam flow through the main spill line 133 to reduce the difference between the setpoint and actual pressure signals. However, the spill control system I46 can also open the auxiliary spill valve 134 if necessary so that the steam flow through the main spill line 13I does not exceed a limit

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exceeds. When the auxiliary overflow valve 134 is open control system 146 main spill valve 132 in FIG such a position that the steam flow through the main overflow line 131 is kept at the limit value, and the system 146 changes the flow of steam through the Auxiliary overflow line 133 in the sense of reducing the difference between the setpoint and actual pressure signal.

According to FIG. 2, the application setpoint signal is over the line 173 and a multiplier 209 are supplied to a first input of a summer 206. A preload signal generator 207 applies a constant bias signal to a second input of summer 206. A comparator 201 applies a signal to line 203 which is the difference between the actual pressure signal in line 145 and corresponds to the setpoint pressure signal in line 143. The signal is sent to a proportional controller via line 203 which applies its output signal via a line 205 to a third input of the summator 206. The summator 206 subtracts the output of the multiplier of the constant bias signal and adds to the difference between these two signals the applied via line 205, third input signal. The output signal thus obtained and emitted via the line 210 corresponds to the setpoint value of the total overflow steam flow rate which is generated by the Main overflow line 131 must occur when this flow is below the predetermined limit, or through the Main overflow line 131 and the auxiliary overflow line 133 if it is above the limit value.

The line 210 has a first input of a low-value selection element 211 connected A puncture transducer 213 generates a signal that the limit value of the steam flow corresponds in the main overflow line 131, and places this Signal via the line 212 to a second input of the low-value selection element 211. If that

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Total overflow setpoint signal is less than the overflow limit value signal, the selector 211 applies the total overflow setpoint signal to the actuator 135, which brings the valve 132 into such a position that the steam flow through the main overflow line 131 is practically equal to the total overflow steam flow, when the vapor pressure in the accumulator 125 corresponds to a low load value. If, on the other hand, the total overflow setpoint signal is greater than the overflow limit value signal, the selection element 211 applies the overflow limit value signal to the actuator 135. A comparator 216 then generates an output signal which corresponds to the excess of the total overflow setpoint signal over the overflow limit value signal, and applies this signal to the actuator 137, which now adjusts the auxiliary overflow valve 134 so that the steam flow through line 133 is practically equal to that Is the flow rate corresponding to the output of the comparator 216. The actuator 135 brings the main spill valve 132 into such a position that the steam flow through the line is effectively equal to the limit value applicable to the steam flow in this line. The total steam flow through lines 131 and 133 is therefore effectively equal to the setpoint of the total overflow steam flow when the steam pressure in the collector 125 corresponds to the low load value. If the desired value of the overflow steam unit flow rate is less than the limit value of the steam flow rate through the main overflow line, the comparator 216 generates the output signal zero and the actuator 137 keeps the auxiliary overflow valve 134 closed.

In the case of the two overflow valves 132 and 134, with a constant pressure drop across the valve, there is a linear dependence of the steam flow through the valve on its position. Each overflow valve is moved by its associated actuator in a position with the actuator controlling input signal in a

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linear relationship. However, overflow valves with a non-linear characteristic can also be used. In this case it is modified each actuator so that it is assigned to it The overflow valve is moved to a position that is non-linear with the input signal of the corresponding actuator Relationship stands. Instead of the main overflow valve .132 or the auxiliary overflow valve 134, one can use use a group of valves. In this case, a separate actuator is provided for each valve in a group and cause the actuators together that the steam flow through the corresponding overflow line effectively corresponds to the flow of steam obtained with a single valve and a single actuator.

If the actual value of the vapor pressure in the collector 125 for the reheated steam corresponds to the setpoint, are the input and output signals of the proportional controller 204 is zero and is the total overflow setpoint signal only depends on the setpoint of the steam flow through the medium pressure control valve. If against it If the actual value of the vapor pressure in the collector 125 deviates from the setpoint value, the comparator 201 outputs a pressure difference signal via the proportional controller 204 to the summator 206, which now receives the total overflow setpoint signal changed as a function of the output signal of the controller 204. According to the changed total overflow setpoint signal the overflow valves 132 and 134 are then im Adjusted to reduce the pressure difference.

The function generator 213 operates according to the following equation:

^K 1

In it is

-U-

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the largest permissible amount of heat that may be given off from the main overflow line 131 to the condenser 130 per unit of time,

K _{1 is} a constant of proportionality,

F is the largest steam flow corresponding to Q the main overflow line 131, and

HRHP is the vapor pressure in the collector 125 for the reheated Steam.

It is therefore F _m " _v = (2 / (K.,. HRHP), ie that the greatest max max: ι

Steam flow in the main overflow line 131 is inversely proportional to the steam pressure in the collector 125. In response to the output from the pressure transducer 144 output signal, which corresponds to the Istdarapfdruck in the header 125, hence the function generator 213 outputs to the line 212 a signal which according to the above relationship ^F max ^SADR ^ falls.

In FIG. 3 A, the dependence of the application setpoint signal output via line 173 on the output power of turbo generator A is graphically represented by line 300. The application setpoint signal with values between 0 and 1.0 is plotted on the vertical axis. The output power of the turbo generator A is plotted on the horizontal axis as a percentage of the maximum power of this turbo generator. When the output power increases from 0 to 25 #, the setpoint of the application steam flow increases from 0 to 1.0. At the setpoint value 0 of this flow rate, the actuator 175 (see FIG. 1) completely closes the medium pressure regulating valve 127. At a setpoint value of this flow rate of 1.0, the actuator 175 controls the medium pressure regulating valve 127 completely. With an output power in the range of 25 f ° to $ 100

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If the setpoint value of the impingement steam flow rate is constant 1.0 and the actuator 175 keeps the medium pressure control valve 127 completely open. With an output power between 0 and 25 f » , the steam pressure in the collector 125 for the reheated steam is kept at a low load value, so that when the medium pressure control valve 127 is fully open, the steam flow through the turbines 111 and practically equal to half the desired minimum steam flow through the Reheater is (see Pig. 1). With an increase in the output power of the turbo generator A from 0 to 25 f » , the corresponding steam flow through the turbines 111 and 112 increases from zero to half the desired minimum steam flow.

In FIG. 3 A, the relationship of the output signal of the multiplier 209 (see FIG. 2) to the output power of the turbo-generator A is graphically represented by the dashed line 301. The multiplier 209 multiplies the application setpoint signal by a constant factor of 0.5 »so that when the output power rises from 0 to 25 fo, the output signal of the multiplier 209 rises from 0 to 0.5. With an output power above 25 fo , the output signal of the multiplier 209 remains constant at 0.5.

In Fig. 3B is the relationship between the total spill setpoint signal on line 210 (see FIG. 2) and the output of turbo generator A through line 302 graphically represented. The total overflow setpoint signal is on the vertical axis plotted with values between 0 and 0.5. On the horizontal axis is the output power of the turbo generator A plotted in percent. The bias signal generated by the signal generator 207 (see FIG. 2) has according to the output signal of the multiplier 209 », which is represented by the dashed line 301 in FIG. 3A, has a constant value of 0.5. If now the Actual value and the setpoint of the vapor pressure in the collector for

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the partially superheated steam are equal to zero, the comparator 201 (see FIG. 2) emits an output signal zero via the line 203, so that the signal in the line 205 is also equal to zero. The total overflow setpoint signal is now generated by the summator 206 (see Pig. 2) corresponding to the difference between the bias signal with the constant value of 0.5 and the output signal of the multiplier 209. According to FIG. 3B, when the output power of the turbo generator A increases from 0 to 25 %, the total overflow setpoint signal decreases from 0.5 to zero. With an output power above 25 ^ the total overflow setpoint signal remains constant at zero. If the steam pressure in the collector 125 for the reheated steam corresponds to the low-load value and the limit value of the steam flow in the main overflow line is greater than half of the desired minimum steam flow, the actuator 135 brings the main overflow valve 132 into one with a total overflow steam setpoint signal of 0.5 Position that the steam flow through the main overflow line 131 is practically equal to half of the desired minimum steam flow. Otherwise, with a total overflow setpoint of 0.5, the actuators 135 and 137 adjust the overflow valves 132 and 134 so that the total steam flow through the main overflow line 131 and the auxiliary overflow line 133 is practically half of the desired minimum steam flow rate, provided that the pressure in the collector for the reheated steam corresponds to the low load value. When the total overflow setpoint is 0, the actuators 135 and 137 keep the overflow valves 132 and 134 closed. Therefore, the total steam flow through the overflow lines 131 and 133 decreases from half the desired minimum steam flow to zero, while the output of the turbo generator A increases from 0 to 25 $ , provided that the comparator 201 does not generate a pressure difference signal.

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The thick line 300 in FIG. 3A represents a linear relationship which exists between the output power and the application setpoint signal when the output power is between 0 and 25 fo the maximum power. This assumption facilitates the explanation, but the invention is not limited thereto. The overflow control system 146 can also work properly if there is a nonlinear relationship between this output power and the application setpoint signal in this range of output power, provided that the medium pressure control valve is fully open at 25 $> the maximum output power.

Other values can of course also be selected for the gain factor of the multiplier 209 and the bias signal than 0.5 · For example, the bias signal and the gain of the multiplier can both be the value Have 1.0. In this case the line 173 is connected directly to the Suinraator 206 and the actuators 135 are and 137 arranged to be activated by adjusting the valves 132 and 134 cause the total steam flow through lines I3I and 133 effectively equal half that desired The minimum steam flow rate is when the total overflow setpoint signal has the value 1.0 and the steam pressure is in the collector for the reheated steam corresponds to the low load value. The value 0.5 is appropriately chosen, when the condenser 135 can fully condense the minimum desired vapor flow rate, provided that the pressure in the Collector for the reheated steam corresponds to the low load value.

In the output power range from 0 to 25 ° , the output signal of the signal generator 142 is a constant setpoint pressure signal which corresponds to the low-load value. From the above explanation it can be seen that in this output "range, the overflow control system I46 the steam flow through, the main overflow line I3I and the

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Auxiliary overflow line 133 controls so that the total steam flow through these overflow lines and the turbines 111 and 112 is effectively equal to half the desired minimum steam flow rate, provided that the actual and desired steam pressure in the collector for the reheated steam are the same. In the output power range from 0 to 25 ° , an increase in the steam flow through the turbines 111 and 112 is accompanied by a corresponding decrease in the steam flow through the overflow lines 131 and 133. Effectively, the overflow control system 146 causes steam previously carried through the overflow lines to enter the turbines 111 and 112 is supplied when the output of the turbo-generator A increases, and that the steam pressure in the accumulator 125 for the reheated steam is regulated.

If the actual value of the steam pressure in the collector for the reheated steam deviates from the setpoint, changes the spill control system 146 controls the flow of steam through one of the overflow lines 131 and 133 in the sense of reducing the difference. In practice, this pressure difference cannot be reduced to zero because the proportional controller 204 allows a residual pressure differential. That has a bias signal generated by the signal generator 207 however, such a value that this residual pressure difference is very small.

At an output power between 0 and 25 fa, the highest total output power of the power plant, the reactor 100 and the helium circulation fans 102 A to 102 C are controlled with the help of operating elements (not shown) so that the reheaters of the steam generator can generate a steam quantity corresponding to the desired minimum steam flow, when the pressure in the receiver for the reheated steam equals the low load value. In this case, the spill control system 146 maintains and controls the vapor pressure in the header 125 at the low load level

- 23 ' system 146

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at the same time the steam flow through the overflow lines 131 and 133 such that the total steam flow through these lines and through the turbines 111 and 112 practically equal to half the desired minimum steam flow rate is. If the reactor 100 and the Heliurn circulation fans 102 A to 102 C do not operate so that the desired minimum flow obtained from reheated steam under pressure corresponding to the low load value, the spill control system 146 changes the steam flow rate therethrough the overflow lines I3I and 133 such that the vapor pressure in the collector 125 for the reheated steam corresponds to the low load value. In this case, however, the total steam flow through the overflow lines 131 and 133 deviates and turbines 111 and 112 from one half of the minimum desired steam flow rate by an amount that depends on operation of the reactor and the helium circulation fan.

In Fig. 2, the reference numerals of the turbo generator B are associated overflow control system 165 in brackets. The parts and connections of the spill control system 165 are shown in dashed lines in FIG. The above description of the circuit and mode of operation of the overflow control system also applies to the control system 165 if the reference numbers in brackets are used instead of corresponding reference numbers are used in the text and the Term "turbines 111 and 112" through the term "turbines 122 and 123 "is replaced.

In one operating mode, the turbo generators A and B are simultaneously loaded with between 0 and 25 i ° of the maximum load of the power plant after they have run up to the synchronous speed. Each of the signal generators 142 and 163 generates an output signal that corresponds to the low load pressure. It goes without saying that in the operating mode just described, a single signal transmitter can be used to send the signal for the setpoint steam pressure in the lines 143 and 164

- 24 - collectors

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Collector for the reheated. To give off steam. As will be explained below, both signal transmitters 142 and 163 must be connected to lines 143 and 164 in other operating modes emit signals that are independent of each other. The application setpoint signals on lines 140 and 162 take between 0 and 1 simultaneously with such a speed that the turbines from an undesirable thermal stress are protected. As a result, the actuators 141 and 163 control the medium pressure control valves 127 and 148 increasingly so that the steam flow in the associated medium and low pressure turbines 111 and 123 depending on the Application setpoint signals increases. The multiplier sets each application setpoint signal between 0 and 1 209 in the assigned overflow control system with the gain factor 0.5 to the summator 206, the subtracts the output of the. multiplier from the constant bias signal (provided the vapor pressure in the Receiver for reheated steam corresponds to the low load value) and therefore the total overflow setpoint signal generated, which is assigned to the respective application target value signal. The sum of the setpoint of the impingement steam flow and the total overflow steam flow rate setpoint represents a steam flow rate setpoint equal to half the minimum desired steam flow it through the reheater. In any spill control system, the low level selector is the total overflow setpoint signal to the actuator for the main overflow valve. This actuator brings then the main overflow valve in such a position that the steam flow through the main overflow line is the same is the setpoint of the total overflow damjf flow rate, if

this setpoint is smaller than the limit value for the overflow steam flow in the main overflow line and the steam pressure in the collector for the reheated steam corresponds to the low load value. If the setpoint for the total overflow steam flow rate is above the limit value for the

- 25 - ' steam flow 509845/0353

WS4P-1274

Steam flow is in the main overflow line, the low-value selection element forwards the signal corresponding to the limit value for the steam flow in the main overflow line to the actuator for the main overflow valve, and the comparator 216 sets the difference between the total overflow setpoint signal and the limit value signal for the steam flow in the main overflow line to the actuator for the auxiliary overflow valve. The actuators for the main and the auxiliary overflow valve bring these valves into such a position that the steam flow in the corresponding overflow line corresponds to the input signal of the actuator in question and that the total steam flow through the overflow lines is practically equal to the setpoint for the total overflow steam flow, provided that the Steam pressure in the collector for the reheated steam corresponds to the low load value. If steam also has to be passed through the auxiliary overflow line to achieve the setpoint of the total overflow steam flow, the steam flow through the main overflow line is kept at the corresponding limit value so that as little steam as possible is blown out through the auxiliary overflow line. At every output power between 0 and 25 f <> the maximum power, the overflow control system controls the overflow valves together in such a way that the steam flow through each overflow system consisting of a main and an auxiliary overflow line is practically half the difference between the desired minimum steam flow and the Total steam flow through turbines 111 and 122 is. The overflow control system therefore controls the associated overflow valves in such a way that at an output power between 0 and 25 i ° of the maximum output of the plant, the desired minimum steam flow through the reheater is maintained when the steam pressure in the collector for the reheated steam corresponds to the low load value.

If the steam generators are unable to do that

- 26 - desired

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to generate the desired minimum steam flow corresponding amount of reheated steam below the low load value, is the comparator 201 in each spill control system a pressure difference signal via the proportional controller 204 to the summator 206, which now the total overflow setpoint signal corrected depending on the output signal of the controller. When the relief valves are set so ensure that the total overflow darapf flow corresponds to the corrected total overflow setpoint signal thereby the pressure difference is reduced. For example, if the actual pressure is higher than the low load value, the correction signal is positive in line 205, so that the total overflow setpoint signal is increased and the adjustment the overflow valves causes a reduction in the pressure difference in accordance with this increased setpoint signal. Of the Pressure transmitter 144, comparator 201 and proportional controller 204 thus provide a pressure feedback system for correction of the total overflow setpoint signal (line 302, FIG. 3 B) in the sense of reducing a difference between represents the actual and the setpoint of the steam pressure in the collector for the reheated steam. If that corrected Total overflow setpoint signal is greater than the limit value signal for the steam flow in the corresponding Main spill line, the low level selector causes the steam flow in the main spill line to be on the corresponding limit value is held and to achieve the total overflow steam flow corresponding to the corrected setpoint value the auxiliary overflow line is also used, as described above. The overflow control systems therefore operate the overflow valves assigned to them in such a way that the from the collector for the reheated steam coming total overflow steam flow in the sense of reducing a difference between the actual and the target value for the vapor pressure in the Collector for the reheated steam is changed.

- 27 -509845/0353

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When each of the regulators 204 acts integrally, the output signals give way the integrators (these output signals are in Ideally the same) in practice increasingly diverge from one another, because the individual integrators integrate disturbance variables that may influence only one, but not both, of the integrators. This increasing deviation leads to an undesirable one Difference between the total overflow setpoint signals that are otherwise simultaneous with the one described above Load of two turbo-generators are equal. The steam pressure in the collector for the reheated steam is effectively controlled even in the case of such a difference, but such a difference can lead to that one of the total overflow setpoint signals is the limit value signal for the steam flow through the corresponding main overflow line exceeds, so that unnecessary and undesirable steam is blown into the open. Because the regulator 204 does not work proportionally-integrally, but proportionally, occur between the total overflow setpoint signals advantageously no differences that can be attributed to the integration of different disturbance variables are. It is true that the proportional controllers 204 generally allow a residual difference between the actual value and the setpoint value of the steam pressure in the collector for the reheated steam, but these residual differences are caused by the bias signals kept as small as possible.

If, in the example given above of the simultaneous loading of two turbo-generators, the output power increases, the medium-pressure control valves are increasingly opened until they are fully opened at 25 i ° of maximum output. Accordingly, the overflow valves are increasingly closed until they are practically completely closed at 25 ° of maximum output. At more than 25 fo the maximum load, the pressure in the collector 125 for the reheated steam can increase in accordance with the load increase and the overflow control systems 146 and 165 operate in the

- 28 - follow-up operation,

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Tracking mode, so that the output signals of the signal transmitters 142 and 163 correspond to the output signal of the pressure transmitter 144. With reference to Fig. 2 it should be noted that that with more than $ 25 of the maximum performance by the tracking operation it is ensured that the overflow valves 132, 124, 154 and 156 remain closed, because "with such Power is the setpoint for the total overflow steam flow (see Fig. 3B) is zero when there is no pressure differential signal in line 203.

If both turbo-generators are working and one turbo-generator is suddenly relieved, control devices (not shown) cause that the quick-closing valve assigned to the relieved turbo generator is closed. Now · the still working turbo generator only has half of the steam flow through the reheater and the rest has to be reheated steam overflow so that the steam pressure in the collector for the reheated steam after the sudden relief is kept constant. If before the sudden discharge of a turbo generator every turbo generator worked with more than 25 / ° of its maximum output has, the overflow control system assigned to the still working turbo generator continues to operate in tracking mode, so that no excess reheated steam through the Overflows condenser, which is assigned to the still working turbo generator. After the sudden relief poses the set pressure signal that is sent to the overflow control system of the unloaded turbo generator is assigned, further represents the steam pressure, which immediately before the sudden unloading in prevailed in the collector for the reheated steam. In contrast, the overflow control system that generates the suddenly relieved turbo generator is assigned, accordingly the application setpoint value zero, which corresponds to the output power zero according to the line 300 in FIG. 3A Total overflow setpoint signal with the value 0.5 if the Pressure difference is zero. The low value selector

- 29 - ' there

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now gives flow rate setpoint signals in the manner noted above to one or both of the actuators for the main and auxiliary overflow valves, and these two Depending on their input signals, actuators bring the overflow valves into such a position that the Overflow steam flow is practically equal to half of the desired minimum steam flow rate, provided that the pressure in the collector for the reheated steam corresponds to the low load value. When the overflow steam flow obtained in this way is not practically equal to that part of the flow of reheated steam that is not occurs through the still working turbo generator, there is a difference between the actual and the setpoint of the steam pressure in the collector for the reheated steam and generates the comparator 201 in the unloaded turbo generator associated overflow control system a differential signal. The summer 206 now corrects the total spill setpoint signal corresponding to the output signal of the controller 204 »so that the overflow valves according to the corrected Total overflow setpoint signal can be adjusted to reduce the pressure difference. The low-choice electoral member has the effect that the auxiliary overflow valve is only opened when the setpoint for the total overflow steam flow is greater than the applicable limit value for the steam flow through the main overflow line, so As little steam as possible is blown into the open air. As a result, after the sudden release, the vapor pressure in the collector for the reheated steam is kept constant at a value which approximates that before the sudden discharge corresponds to the existing vapor pressure. The stabilization of the vapor pressure after a sudden discharge has the advantage that the still working turbo generator continues to generate power according to its power requirement, without that the control valves assigned to the working turbo generator are suddenly adjusted and without transient processes to fluctuations in the output power of the

- 30 - working people

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working turbo generator lead, as this could be the case if the steam pressure in the collector for the reheated Steam after a sudden discharge of a turbo generator due to transient processes fluctuates. Due to this pressure stabilization, the after the sudden relief as a result of transient fluctuations in the speeds of the auxiliary steam turbines (see Fig. 1) avoided and thereby the change in the flow rates of the reactor cooling gas is avoided a sudden discharge of a turbo generator.

If both turbo-generators are suddenly unloaded at the same time at more than 25 'f <> of the maximum output, after the sudden unloading each of the signal transmitters 142 and 163 generates an output signal which corresponds to the steam pressure prevailing in the collector for the reheated steam immediately before the sudden unloading. After the sudden relief, the application setpoint signals in lines 140 and 162 are equal to zero and the pressure transmitter generates an output signal which corresponds to the steam pressure present in the accumulator for the reheated steam after the sudden relief. The overflow control systems 146 and 165 control the overflow of the steam coming from the reheaters by means of the overflow valves assigned to them in such a way that the pressure in the collector for the reheated steam is kept at the value present before the sudden discharge. Sudden unloading of one or both turbo-generators can occur even when the output power is less than $ 25 of the maximum power. In this case, the steam pressure in the receiver for the reheated steam after the sudden discharge is also controlled by the spill control systems by means of the spill valves, but after a sudden discharge of such a small capacity, the pressure is kept at the low load level.

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One can use the overspray control system shown in FIG can also be used to operate the overflow valves in a main and an auxiliary overflow line, which are a single Turbo generator of a power plant are assigned. In this case, the medium pressure control valve is dimensioned so that it the Medium and low pressure turbines with the desired minimum steam flow applied when the medium pressure Hegel valve is fully opened and the steam pressure in the collector for the reheated steam the low load value corresponds, and the actuators for the main and the auxiliary overflow valve are set up so that the desired Minimum steam flow occurs through the overflow lines, when the total overflow setpoint signal has the value 0.5 and the vapor pressure in the collector for the reheated one Steam corresponds to the low load value.

If the only turbo generator of a power plant is loaded with between 0 and 25 i ° of the maximum load after ramping up to the synchronous speed, the pressure in the collector for the reheated steam is kept at the low load value. The setpoint signal in line 145 (see FIG. 2) for the steam pressure in the accumulator for the reheated steam corresponds to the low load value, and the application setpoint signal in line 140 increases from 0 to 1 at such a rate that the Turbo generator is not exposed to undesirably high thermal loads. The medium-pressure regulating valve is adjusted in accordance with the application setpoint signal, so that the steam flow through the medium and low-pressure turbines increases in accordance with this signal. If the admission setpoint value has the value 1.0 and the steam pressure in the collector for the reheated steam corresponds to the low load value, the steam flow through the medium and high pressure turbines is practically equal to the desired minimum steam flow. When the steam pressure in the collector for the reheated steam

- 32 - ' dem

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corresponds to the low load value, a total overflow setpoint signal (see Fig. 3 B) is generated on the basis of the admission setpoint signal 3 that the sum of the setpoint value of the admission steam flow rate and the setpoint value for the total overflow target flow rate is equal to the desired minimum discharge rate. The low value »selection element 211 (see Pig. 2) outputs the total overflow setpoint signal to the actuator for the main overflow valve when the setpoint for the total overflow darap flow is less than the minimum value for the steam flow in the main overflow line; Otherwise, the low-value selector 211 outputs the signal for the limit value of the steam flow through the main overflow line to the actuator for the main overflow valve and the comparator outputs the difference between the total overflow setpoint signal and the signal for the limit value of the steam flow through the main overflow line to the actuator for the auxiliary overflow valve. The main overflow valve is set in such a way that the steam flow through the main overflow line is practically the same as the setpoint for the total overflow steam flow, provided that this setpoint is less than the limit value for the steam flow through the main overflow line and the steam pressure in the collector for the temporarily superheated steam corresponds to the low load value. The auxiliary overflow valve is closed. If, on the other hand, the setpoint for the total overflow steam flow is greater than the limit value for the steam flow through the main overflow line, the steam flow through the main overflow line is kept at this limit value and the auxiliary overflow valve is set so that the total steam flow through the main and auxiliary overflow lines is equal to the setpoint for is the total overflow steam flow rate when the steam pressure in the receiver for the reheated steam corresponds to the low load value. As a result, as little steam as possible is blown into the open when the auxiliary overflow valve has to be opened. At any setpoint between 0 and 1.0 for the

- 33 - Floor steam flow, 509845/0353

W34P-1274

BeaufBhlagungsdainpfdurchfluß, depending on this setpoint, the overflow control system 146 actuates the main and the auxiliary overflow valve such that such a total overflow steam flow it is achieved that the total amount of the discharged from the collector for the reheated steam Steam practically equal to the desired minimum steam flow is provided the steam pressure in the collector for the reheated Steam corresponds to the low load value.

If, when the turbo generator is loaded between 0 and 25 tfo of the maximum load, the steam generators are unable to generate the amount of steam corresponding to the desired minimum steam flow under the low load pressure, the comparator 201 (see Pig. 2) generates a pressure difference signal and the summator 206 corrects the total overflow Setpoint signal corresponding to the correction signal emitted by the proportional controller 204 via the line 205. Depending on the corrected total overflow setpoint signal, the main and auxiliary overflow signals are adjusted to reduce the pressure difference. If the corrected total overflow setpoint signal is greater than the signal that corresponds to the limit value for the steam flow in the main overflow line, the steam flow through the auxiliary overflow line is changed in the sense of reducing the pressure difference, because the input signal of the actuator for the main overflow valve is then constant. The proportional controller 204 allows a residual difference between the actual and the setpoint of the steam pressure in the collector for the reheated steam, but this residual difference is kept as small as possible by the bias signal (see Figure 2).

At 25 f ° of maximum output, the main and auxiliary overflow valves are practically completely closed. At more than 25 fi of the maximum output, the steam pressure in the collector for the reheated steam increases with increasing

- 34 - Last

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3Γ

The load increases and the overflow control system 146 (see FIG. 2) operates in tracking mode, ie the actual and setpoint pressure signals in the line 145 and 143, respectively, are the same. This ensures that the main and auxiliary overflow valves remain closed. After the turbo generator is suddenly relieved of load at more than 25 ° F. of the maximum output, the setpoint pressure signal in line 143 continues to correspond to the steam pressure present in the collector for the reheated steam immediately before the sudden relief. In contrast, the actual value signal in line 145 corresponds to the steam pressure which is present as a result of the sudden relief in the collector for the reheated steam. After the turbo generator is suddenly relieved of load, the quick-acting valve assigned to the medium and low-pressure turbines is closed by means not shown and the steam supplied to the collector for the reheated steam must flow over completely. After the sudden relief, the application setpoint signal has the value zero corresponding to the output power zero (see Fig. 3 A) and the total overflow setpoint signal (see Fig. 3 B) has the value 0.5, provided there is no pressure difference signal in line 203 ( see Fig. 2) is present. As a result, the overflow valves are set so that the total overflow steam flow is equal to the desired minimum steam flow, provided that the steam pressure in the collector for the reheated steam corresponds to the low load value. If the total overflow steam flow rate is not equal to the flow rate of the reheated steam, a difference occurs between the actual and the desired value of the steam pressure in the collector for the reheated steam and the comparator 201 outputs a pressure difference signal via line 203, which is obtained from the proportional controller 204 is output to the summator 206. The summator 206 corrects the total overflow steam setpoint signal in accordance with the output signal emitted by the proportional controller 204 via the line 205. According to the corrected total overflow

- 35 - Setpoint signal

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Setpoint signal, the main and auxiliary overflow valves are adjusted to reduce the difference. By regulating the steam pressure in the collector for the reheated steam after a sudden discharge, changes in the speeds of the shafts of the auxiliary steam turbines (see Fig. 1) and thus the changes in the flow values of the reactor cooling gas that occur after the sudden discharge are reduced. The overflow control system also actuates the overflow valves in such a way that after a sudden discharge of the turbo generator at less than 25 i ° of the maximum output, the steam pressure in the collector for the reheated steam is changed as little as possible. In this case, the steam pressure in the receiver for the reheated steam is kept at the low load value.

- 36 -

η f \ η ι r

Claims (1)

VB4P-1274 Claims 1. Arrangement for controlling the steam pressure in a collector, the reheated steam from a reheater a steam generator is supplied, which extract heat from a reactor cooling gas flow and superheat it and reheated steam to a turbo generator which has at least one high pressure turbine and at least one medium or low pressure turbine, the Ga3 being fed through a high temperature nuclear reactor and the steam generator using a circulating fan is circulated, which is rotated by an auxiliary steam turbine through which part of the entry to the reheater to be supplied steam occurs, and wherein the collector for the reheated steam so switched is that steam flows from the header to a condenser along a first path can, which has the medium or low pressure turbine, and along a second path, which is an overflow line having, and wherein the control arrangement comprises a valve device has, which is used to regulate the flow of steam through the overflow line, a signal generator for generating a first signal which is a setpoint value for the steam flow through the medium or low pressure turbine indicates a pressure transmitter for generating a second signal that corresponds to the actual value of the vapor pressure corresponds in the collector for the reheated steam, and a signal transmitter for generating a third Signal that specifies a setpoint for the steam pressure in the collector for the reheated steam, - 37 - by, 509845/0353 WS4P-1274 characterized in that a control system is provided which, as a function of the first signal by adjusting the valve device, controls the steam flow through the overflow line so that the steam flow through the reheater is equal to a predetermined minimum flow when the I3t and the target steam pressure a predetermined low load value match and the target value of the steam flow rate through the middle or low pressure turbine klei _r ner than the predetermined Mindestdampfdurchfluß, and the proportion by Hauptüberströmleitung for a difference between the second and the third signal in response to the second and third signal the steam flow to the difference changed between the second and the third signal in the sense of reducing this difference. 2. Control arrangement according to claim 1, characterized in that the control system has a signal transmitter which is used to generate a fourth signal having a predetermined ratio to the difference between the second and the third signal, furthermore a signal generator for generating a fifth signal, having a predetermined relationship to the first signal, means for generating a sixth Signal which corresponds to the fourth signal reduced by the fifth signal, and an actuator for Adjusting the valve device according to the sixth signal. 3 «control arrangement according to claim 2, characterized in that the signal generator for generating the fourth Signal has a comparator which is used to generate an output signal which is the difference between corresponds to the second and the third signal, and a proportional controller that is dependent on the - 38 - output signal 509845/0353 WS4P-1274 Output signal of the comparator generates the fourth signal, that has a predetermined ratio to the output signal of the comparator. 4. Control arrangement according to claim 2 or 3, characterized in that that the control system has a bias signal generator and the sixth signal of the sum of the bias signal reduced by the fifth signal and the fourth signal. 5. Control arrangement according to one of claims 1 to 4, in which, at a constant pressure difference across the valve device, the valve means the steam flow passing through it changed linearly as a function of the position of the valve device, characterized in that that the associated actuator is suitable to bring the valve device into a position that with has a linear relationship with the sixth signal. 6. Control arrangement according to one of claims 1 to 5 » with an auxiliary overflow line that has a second valve device has and serves to steam from the collector for the reheated steam a further To supply steam emission parts, characterized in that that the control system is arranged to allow the flow of steam through the overflow lines Actuation of the first and the second valve device in dependence on the first signal controls in such a way that the steam flow through the reheater corresponds to a predetermined minimum steam flow rate, when the actual and the target pressure correspond to a predetermined low load value and the desired target value the steam flow through the medium and low pressure turbines is less than the minimum desired. steam flow and that there is a difference between the second and the third signal den - 39 - Total steam flow 509845/0353 WS4P-1274 Gresantdainpfdurehfluis through the overflow lines in the Changes in the sense of reducing this difference. ⁷ S control arrangement according to. Claim 6, characterized in that the control system has a signal generator which serves to generate a signal which corresponds to a limit value for the steam flow through the srst-mentioned overflow line, and that the second Yentilelnrntung is controlled so that it is in the first-mentioned overflow ' Msitung sinen Dainpfäurclifluß maintains the limit value "J while with such a regulation the steam constant flow through the first-mentioned overflow line of the Barapf flow through the auxiliary overflow line in the sense of reducing the-mentioned difference is changed. 3 * control arrangement according to claim I ₁ characterized gsksnn-?, Eichnet that the signal for the limit value of the Dampfdurchflußös is generated as a function of the second signal and the value of the limit value signal is opposite to the actual steam pressure in the collector for the awischen- ΙΓο heated steam is changed. 2, control arrangement according to claim 8, characterized in that that the signal generator sum generating the 5rsna ~ value signal is a function generator to which the sweits Signal applied as input signal v / iro. and the that Limit value signal as output signal. 10. Control arrangement according to claims 6 to 9? characterized in that the control system comprises selectively membered sin off, the τοη a function of the sixth signal and the Durchflußgrenawertsignal selects the smaller of these two signals and the selected signal to an actuator for the first Tentil a direction and to a comparator anlagt ;, fsrner sinen - 40 509845 / C3oS W5AP-1274 HA Actuator for setting the first valve device corresponding to the selected signal, a comparator for generating an output signal that is the difference between the sixth signal and the selected signal and an actuator for setting, of the second valve device in accordance with the output signal of the comparator. 11. Control arrangement according to claim 10, characterized in that that the second valve device is closed is when the sixth signal is less than the limit value signal. 12. Steuerai-ord.r ing according to claim 11, characterized in that that the first valve device is closed is when the sixth signa.! equals zero. 13. Control arrangement according to claim 11, characterized in that that the first and the second valve means operated so that the steam flow through the corresponding overflow line of half of the predetermined one minimum steam flow rate & it corresponds if the corresponding Beaufschlagwigs setpoint signal is the same Is zero and the setpoint and actual steam pressure is a predetermined one Correspond to the low load value. 509845/0353