JPS6383802A - Process controller - Google Patents

Abstract

PURPOSE:To improve a back-up function with a process controller by adding a circuit in parallel to a main control arithmetic circuit of an emergency control system to directly calculate the signal received from a detecting part and applies it to a control part. CONSTITUTION:In an emergency control system a circuit containing a function computing element 22.5 is set in parallel to a main control arithmetic circuit containing a deviation arithmetic part 22.1, a control arithmetic part 22.2 and an integration saturation preventing arithmetic part 22.3. The input signal of a controller 22, i.e., the signal received from a water level detector 3 is applied to the element 22.5 via a signal line 21.1. A higher-rank signal selector 22.6 compares the signal received from the main control arithmetic circuit with the signal received from the element 22.5 and delivers the larger signal to the controller 22 as an output. When the water level of a drain tank showing the control value has an extraordinary rise, the output of the element 22.5 is selected with preference and given to a control valve 8 serving as a control part. Thus the discharge value of the train tank is increased to prevent the rise of the water level.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a process control device, and more particularly to a process control device having a regular control system and an emergency control system to back up the regular control system as one control target.

[Conventional technology]

In process control where the state variables of industrial processes such as temperature, pressure, flow rate, liquid level, and concentration are controlled variables, a regular control system and an emergency control system may be installed in parallel for one control target. It can be seen a lot. The regular control system is generally used to manage control during normal operation, and the emergency control system is used to: ■ act on behalf of the regular control system when it is inactive; If the process status changes and the regular control system is unable to control it, this system will take over. ■If the process status exceeds the normal range and becomes abnormal, the regular control system alone will not be able to adequately handle the situation. It is installed for the purpose of backing up this with an emergency control system.

Although there are various examples of process control, here, drain water level control of a feed water heater drain tank for power generation equipment will be taken up and explained below.

Various control methods have been adopted for the feed water heater drain tank water level control device, and one of the most recent ones is the Japanese Patent Application Laid-open No. 56-1.
There is one described in No. 55305.

A typical example of a conventional feed water heater drain tank water level control device is shown in FIG. Drain from the feed water heater is introduced into the feed water heater drain tank 2 through a drain pipe 1. A water level detector 3 is attached to the drain tank 2 to detect the water level of this drain. The drain once stored in the drain tank 2 is pressurized by a drain pump 5 installed in a drain pipe 4 and is sent to a condensate pipe (not shown). Furthermore, when the drain pump 5 stops operating, water is sent to the condenser via the drain pipe 7. Control valves 6.8 are installed in the drain pipes 4 and 7, respectively, to control the water level in the drain tank 2. The water level in the drain tank 2 is detected by the water level detector 3 described above, converted into a signal, and sent to the controller 12 via the signal line 11. The controller 12 sets the water level in the drain tank 2 to NWL.
Control calculations (for example,
This is then sent to the control valve 6 via the signal line 13 to control the valve opening and adjust the amount of drain discharged to the condensate pipe. Further, the output signal of the water level detector 3 is branched from the signal line 11 and sent to the controller 22 via the signal line 21. The controller 22 adjusts the water level of the drain tank 2 by NWL+α (α is often between 50 and Loom, but
For ease of explanation, control calculations are performed to maintain the α=50+ms), and the signal is sent to the control valve 8 via the signal line 23 to adjust the amount of drain discharged to the condenser.

In this feed water heater drain tank water level control device, the regular control system mainly consists of the water level detector 3. Controller 12. It is composed of a control valve 6 and is in charge of control during normal operation. The emergency control system mainly consists of a W/4ffi'i meter 22 and a control valve 8 (the water level detector 3 is shared with the regular control system), and when the drain pump 5 stops operating, this emergency control system drains the water. The drain water level of tank 2 is kept constant (NW L + 50 nn). This emergency control system includes ■the drain pump 5
In addition to when the regular control system stops operating, the emergency control system performs control when the regular control system is inoperable due to a failure of the regular controller 12 or the regular control valve 6. Because the amount of drain from the feed water heater is small,
Considering economic considerations, the operation of the drain pump 5 is stopped. In this case, operation using the normal control system becomes impossible, so control is performed using the emergency control system. When the drain water level in the drain tank 2 rises, the emergency control system functions as a backup to maintain the water level at NWL+50+m.

[Problem that the invention seeks to solve]

In the above-described conventional technology, the emergency control system has the advantage of performing control in place of the regular control system when it is inoperable, but the emergency controller 22 has the same function as the regular controller 12 (the fourth
In the example shown in the figure, the content of the control calculation is not specified, but it is 1 (for example, proportional/integral calculations are performed), so if the water level in the drain tank 2 rises suddenly, the emergency controller 2
2 is delayed, the transmission of the full valve open command to the emergency control valve 8 is delayed, the drain tank 2 becomes full, and the water level of the feed water heater (not shown) connected to it rises, causing the turbine (not shown) to The problem was that it caused water induction (backflow to the turbine).

An object of the present invention is to strengthen and enhance the backup function that an emergency control system should originally have. The present invention provides a process control device with a function of fully opening the valve 8.

[Means for solving problems]

The above purpose is to achieve the above objective when a control target has a regular control system and an emergency control system that backs up the regular control system. This can be achieved not only by having a circuit, but also by installing in parallel a circuit that can calculate the signal from the detection part and give the signal to the operating part preferentially when the controlled variable becomes abnormal.

In the above example of the feed water heater drain tank water level control device, the function of the emergency controller 22 is to send an input signal from the water level detector 3 to the main control calculation circuit that performs proportional and integral calculations to control NWL + 50 mm. This can be achieved by branching off and adding a circuit (installed in parallel) to generate a signal for fully opening the emergency control valve 8 when the water level in the drain tank 2 rises abnormally.

[Effect]

The control unit of the emergency control system is installed in parallel with the main control calculation circuit.When the control amount exceeds the specified range and becomes abnormal, the signal from the detection unit is calculated and the signal is sent to the operation unit with priority. 6. The above-mentioned feed water heater drain tank water level control circuit operates to operate the operation unit in the direction of alleviating the abnormality of the control amount without being subject to any restrictions on the main control calculation circuit. In the example of the device, drain tank 2
In response to an abnormal rise in the water level [7, the valve opening command can be issued by directly calculating the water level signal of the drain tank 2 instead of the output signal from the proportional/integral calculation of the controller 22, so the control valve 8 can be opened at the specified water level. Since it becomes possible to fully open the control valve 8, a delay in response of the control valve 8 can be prevented, the possibility of water induction to the turbine can be reduced, and the reliability of the plant can be improved.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1, 2, and 3.

FIG. 3 is a system diagram showing the feed water heater drain tank water level control device. Since the same parts as in FIG. 4 are given the same reference numerals, repeated explanation will be omitted. Water level detector 3 and controller 1
2.22 is electrical, so the signal line], 1,
13, 2.1, and 23 are electrical signals. The output signals of the controllers 12.22 are converted into pneumatic signals by electro-pneumatic converters 14.24, and the signals are sent to the control valves 6 and 8 via signal lines (pneumatic) 15.25. ing. Fig. 3 shows the pneumatic control device in Fig. 4 changed to an electric type, but since an electric type can be an embodiment of the present invention, it is specifically described as Fig. 3. In FIG. 3, the regular control system mainly consists of water level detector 3. Controller 12. It is composed of an electro-pneumatic converter 14 and an i11 control valve 6, and the emergency control system is mainly composed of a controller 22. Electropneumatic converter 24. It consists of a control valve 8 (the water level detector 3 is shared with the regular control system).

FIG. 1 illustrates the control device of FIG. 3 with the functions of the controllers 12 and 22 as the main components. Recently, many electric controllers are digital, and various calculations are processed by software programs, but here the main calculation processing contents are expressed in the form of a block diagram.

The output of the water level detector 3 (I is the signal line) is sent to the regular controller 12 via the -1-.In the controller 12, first, the deviation calculation unit 12.1 calculates the set value (signal value corresponding to NWL). This deviation is calculated by the next control calculation section 12/2.
7 Integral calculations perform proportional/integral calculations (not shown in Figure 1, but may also perform differential calculations and add to these). If the deviation continues, the output signal will drop to the upper limit value (or lower limit value). ), which may impair the responsiveness of the control, so the upper and lower limit values are limited to appropriate values in integral saturation prevention calculation section ]-2 and 3. Manual/automatic switch 12
・Normally, automatic is selected for 4, and the above calculation result is sent to controller 1.
However, if manual intervention is required, the signal is switched to the manual side, the signal generated by the control calculation is cut off, and an arbitrary output signal is manually selected and output.

On the other hand, the emergency control system sends the output signal of the water level detector 3 to the emergency controller 22 via the signal line 21. In the controller 22, the deviation calculation section 22.1 calculates the set value (NWL+50m
The control calculation unit 2 calculates the deviation from the signal value corresponding to
Proportional and integral calculations are performed in 2.2, and integral saturation prevention calculation section 2
In steps 2 and 3, limit the upper and lower limits to appropriate values. In the conventional technology, this calculation result is generally manually calculated as in the regular controller 12.
Although outputted via the automatic switching device 22.4, in the present invention, the deviation calculation section 22.1. Control calculation unit 22.2.
A circuit having a function calculator 22.5 is installed in parallel to the main control calculation circuit of the integral saturation prevention calculation section 22.3. The input signal of the controller 22, that is, the signal from the water level detector 3, is passed through the signal line 21.1 to the function calculation $22.5.
to be introduced.

In the function operator 22.5, Fig. 2 f(X) (function operator)
As shown in the characteristic diagram, the output signal is 0% (fully open) below NWL + 200 wm, and the output signal increases linearly at 1ml of NWL + 200 to 350I, and NWL + 3F)
In the f(x) characteristic diagram in Figure 2, which outputs a 100% (fully open) output signal at Om, the input signal O~100% is the drain tank water level N W L -150-N W L +
350 mm, the set value NWL of the regular controller 12 and the set value NWL of the emergency controller 22
0III11 is also shown here, and the function operator (f(x))
The relationship with the output signal of 22.5 is clearly shown. The output signal of the function calculator 22.5 is transmitted via the signal line 21.2.
Output signal line 2 of the main control calculation circuit of the controller 22
The signals are transmitted to high-level signal selectors 22 and 6 installed at ports 1 and 3. The high-level signal selector 22.6 compares the signal from the main control calculation circuit with the signal from the function calculation circuit 22.5, selects the larger value and outputs it, and the manual/automatic switch 22.4 1 to be output as the output of the controller 22 via
According to the present invention, the output of the function generators 22.5 installed in parallel is not limited to the main 22 control circuit of the Wsjr5 total 22, so when the water level of the drain tank 2, which is a controlled variable, rises abnormally, the output of the function generators 22. 5 output (for example, N W
When it is more than L + 350 + m, the valve fully open signal) is preferentially selected and applied to the control valve 8, which is the operating section, increasing the amount of water discharged from the drain tank 2 and producing the effect of preventing the water level from rising.

The effects of the embodiment of the present invention shown in FIGS. 1 to 3 will be specifically explained with reference to FIGS. 7 and 8. 7th
The figure is an explanatory diagram showing the output signal characteristics of the controllers 12 and 22 in Figure 1 in terms of the relationship between the drain tank water level and the valve opening. Line A is the proportional operation characteristic of the controller 12, with the normal valve opening at 50%. , Characteristics when the proportional band setting value is assumed to be 300%. Line B is the proportional operation characteristic of the control calculation unit 22/2 of the controller 22 when the drain tank water level rises, assuming the proportional band setting value is 300%. (The valve opening is fully closed when NWL + 50 pus, and the valve opening increases as the water level rises.) Line C is the controller 2.
The characteristics of the function calculator 22.5 according to the present invention in No. 2 are copied from the characteristics shown in FIG.
%). Figure 8 is an explanatory diagram showing an example of control characteristics when the amount of drain flowing into the drain tank increases rapidly, and shows the relationship between changes in the water level in the drain tank and changes in the valve openings of the control valves 6 and 8 with respect to the time axis. This is shown in .

(2) The control valve 6 is opened at 50 degrees by the output signal of the controller 12.
% indicates a state of NWL control; ■ indicates a rapid increase in the amount of inflow drain, and the water level in the drain tank begins to rise. As the water level rises, the valve opening of the control valve 6 increases according to the A characteristic shown in FIG.
Due to the integral action in 2.2, the valve opening is slightly larger than the A characteristic (proportional operation valve)). When the water level reaches NWL + 50 m at ■, the control valve 8 begins to open, and when the water level rises further, The valve opening of the control valve 8 increases according to the characteristics (Similarly, the valve opening becomes slightly larger than the B characteristic due to the integral operation). When the water level reaches NWL + 200 m at ■, the signal of the C characteristic in Fig. 7 The output starts from the function calculator 22/5. The higher one of the B characteristic and C characteristic signals is selected by the high level signal selectors 22 and 6 shown in FIG. 1, and the control valve 8 is controlled. In characteristic C, compared to characteristics A and B, the rate of increase in valve opening with respect to water level rise is large, and the valve opening increases rapidly. When the amount of inflow drain and the amount of discharge drain from control valve 6.8 are balanced, the water level will stop rising, but in general, in a control loop with a high control system gain, an overshoot phenomenon will occur, causing a hunting phenomenon. 5 Figure 8 shows this tendency. It is shown as a change in water level and a change in the opening degree of the control valve 8.

On the other hand, according to the present invention, when the function calculator 22.5 is not installed, the valve opening degree of the i6 valve 8 remains at 20% when the water level reaches NWL + 350 m at ■, and the water level continues to be shown by the dotted line at ■. The drain tank 2 will continue to rise, and the water level in the feed water heater (not shown) connected to it will rise, potentially inducing water induction into the turbine (not shown). The valve opening degree of the control valve 6 is approximately 73%, and after that, the water level rises beyond the detection range, so the signal does not increase due to the proportional action component, and the output signal of the controller increases only due to the integral term. As shown in FIG. 8, there is a tendency for the increase in valve opening degree to further decrease.

).

However, according to the present invention, the function operation 17. When the water tank 22.5 is added, the water level tends to hunt because it is controlled by the C characteristic, which has a high gain, but in general, the emergency control valve 8 can be fully opened when the water level rises abnormally, and it is used as a backup. It becomes possible to demonstrate the function as a system.

Next, other embodiments of the present invention will be shown. 5 and 6 show an example in which the control method of the regular controller 12 and emergency controller 22 in FIG. 1 is changed. FIG. 5 is a control block diagram of the regular controller 12, and FIG. 6 is an emergency controller The control system of the regular controller 12 and the emergency controller 2, which shows a control block diagram of the regular controller 22.
Describing the details of the main control arithmetic circuit in No. 2 is not directly related to the present invention, so we will only describe its outline.
Since the effects of the present invention are particularly noticeable in the figures, the main points will be described below. Similar to the regular controller 12 shown in FIG. 11, FIG. 5 includes a deviation calculation section 1-2.1, a control calculation section 12.2, an integral saturation prevention calculation section 12.3, and performs normal control calculations. , input the condition of [drain pump in operation], and when the drain pump 5 starts, the control valve 6 is gradually opened.
A circuit is additionally installed to receive signals from the gradual opening signal generators 12 and 11 and close the control valve 6 when the drain pump 5 stops. FIG. 6 is a control block diagram of the emergency controller 22 shown in FIG.
Based on the interlock condition of "drain pump in operation", the output parts of the control calculation section 22.2 and the integral saturation prevention calculation section 22.3 control the control valve 8 to "sudden open" and "slow open" when the pump is stopped and started. This is an additional circuit that closes the battery. At the time of plant startup, the drain pump 5 is not operated, and when the water level of the drain tank 2 reaches NWI, +50 re, the control calculation circuit section (22.1 to 22.1) of the emergency controller 22 is activated.
- The control valve 8 is opened to the required opening degree by the action of 3). When the load of the plant reaches 25%, the drain pump 5 is started. At this time, the signals from the gradual opening signal generators 12 and 11 shown in FIG. To go. When the valve opening degrees of the control valves 6 and 8 become equal, the gradual opening operation ends, and the control valve 6 is transferred to the control of the control calculation section 12.2 (the control calculation section 12.2 The output is corrected according to the opening degree to prevent disturbances during switching.

(Illustration is omitted in FIG. 5).

On the other hand, at the same time as the control valve 6 shifts to control, the control valve 8
The signals from the gradual closing signal generators 22 and 12 shown in the figure are given according to the interlock conditions, and the valve is gradually closed and fully opened. After the gradual closing is completed, the full opening due to the interlock condition is released and the control is transferred to the control calculation unit 22.2, but the drain tank water level remains at N.
Since the control valve 8 is controlled by WL, the control valve 8 remains fully open. If the drain pump 5 trips due to a malfunction while it is in operation, or if the drain pump 5 is stopped as a normal operation when the load of the plant is reduced to 25%, the sudden opening signal shown in Fig. 6 is activated. A signal from the generator 22. ], 1 is given according to the interlock condition, and the opening degree of the control valve 8 increases. When the valve opening degrees of the control valves 6 and 8 become equal, the quick opening operation ends, and the control valve 8 is transferred to the control of the control calculation section 22.2 (as in the case of the controller 12, the switching (Although it is not shown in FIG. 6, it is also used to prevent disturbances at times.) At this time, the control valve 6 receives the valve closing signal 12.1 in FIG.
2 is closed. Signal lines 21・1, 2 in Figure 6
1/2, function calculator 22/5, high level signal selector 22/6
is a circuit of the present invention having the same function as the emergency controller 22 shown in FIG.

Compared to the control method shown in FIG. 1, the control methods shown in FIGS. 5 and 6 are effective control methods that can better control the water level in the drain tank 2 as the drain pump 5 starts and stops. As mentioned above, there are cases where gradual closing is performed under interlock conditions under program control (for example, control based on gradual closing signal generators 22 and 12), and - when the backup function as an emergency control system is temporarily lost. There is. In the present invention, if program control such as gradual opening and closing is included in the main control circuit of the adjustment section of the emergency control system, when the control amount exceeds the specified range and becomes abnormal, Since circuits that can calculate the signal from the detection section and give the signal to the operation section preferentially are installed in parallel, the backup function has the effect of working effectively in any case.

Although the control block diagram in FIG. 1 shows an example of an electric controller, it is of course applicable to both analog and digital controllers.

Furthermore, in the case of a pneumatic type, this can be easily implemented by separating the function calculators 22 and 5 from the controller 22 and preparing a separate meter.

In FIG. 1, the "circuit that can calculate the signal from the detection section and give the signal to the operation section preferentially" according to the present invention is defined as the function calculator 22.5, and its characteristic diagram is specified in FIG. Although the example is shown in which the valve opening is increased proportionally above the water level, it is also possible to increase the valve opening in steps or one step, or to change the characteristics to a broken line, curved line, etc.

Above, we have shown the case of a feed water heater drain tank water level control device for power generation equipment as an example of a process control device, but thermal power plants and nuclear power plants also have various equipment,
There is an example in which two control systems, a regular control system and an emergency control system, are installed in parallel to store water in a container such as a tank and maintain the water level at a specified value, and the present invention can be applied to this system. .

FIG. 9 shows an example of a schematic system diagram of a thermal power plant.

Steam generated by a boiler 101, which is a steam generator, is guided to a high-pressure turbine 102, and the thermal energy of the steam is used to rotate (machine)
It converts into energy and turns a generator (Illustrator 1II8) to generate electricity. After some work has been completed, the steam returns to boiler 101.
to reheat.

This reheated steam is guided to an intermediate pressure turbine 103 to do work, and is further led to a low pressure turbine 104 to finish work (turning a generator). The steam that has completed its work is guided to a condenser 105 and cooled to become condensed water. This condensate is pressurized by a condensate pump 106 and passes through low pressure feed water heaters 111 to 113 to a deaerator 12.
Supply water to 1.

In the deaerator, water is temporarily stored in a water storage tank 122, and then pressurized by a water supply pump 123, and then transferred to high pressure water heaters 131 to 133.
The water is sent to the boiler 101 through. A boiler heats this to generate steam. In the low-pressure and high-pressure feedwater heaters, in order to heat the feedwater to the boiler, steam is introduced from the low-, medium-, and high-pressure turbines to perform heat exchange. The heat-exchanged steam becomes drain and is temporarily stored in the feed water heater, and the water level of the drain is controlled to be maintained at a specified value, and normally is discharged to the next stage feed water heater via the regular control valve 6. . The high-pressure feedwater heater 133 is capable of discharging condensate to the high-pressure feedwater heater 131 via the emergency control valve 8 . Similarly, the high-pressure feedwater heater 132 can be discharged to the deaerator using the emergency control valve 8, and the high-pressure feedwater heater 131 and the low-pressure feedwater heaters 113 and 112 can be discharged to the condenser. In the high-pressure feed water heater 131, hedrine is normally discharged from a deaerator in a high load range, and in a low load range, it is discharged from the low pressure feed water heater 113, and can be discharged to a condenser in an emergency. Also, low pressure water heater 11
1, after the drain is temporarily stored in the feed water heater drain tank 2, it is pressurized by the drain pump 5 and the regular control valve 6 is used.
The water is sent to the outlet-side wood pipe of the low-pressure feed water heater 111 through the water heater 111, and is discharged to the condenser via the non-normal control valve 8 during non-normal times. The entire water level control device for this drain tank 2 is the same as that already explained in FIG. 3, and the details of the control device are as shown in FIG. 1. Controller 12°22 is the fifth
6 may be adopted. In Figure 9, only the regular control valve 6 and emergency control valve 8 are shown as the water level control device for the feed water heater, and the details of the control device are omitted, but the control system shown in Figure 1 is applicable. It is obvious that the present invention can be applied to a water level control device for a feed water heater of a thermal power plant.

FIG. 10 shows an example of a schematic system diagram of a nuclear power plant. The steam generated by the nuclear reactor 101A, which is a steam generator, is guided to the high-air turbine 102 to perform some work, and this exhaust steam is sent to the moisture separator 141 to separate the moisture in the steam. The moisture-separated steam is sent to a low pressure turbine 104 to do work. The steam that has completed its work is led to a condenser 105 and becomes condensate. The high/low pressure turbine generates electricity by driving a generator (not shown), pressurizes condensate (also referred to as feed water) with a condensate pump 106, and sends the water to a feed water pump 123 via low pressure feed water heaters 111 to 114. The feedwater pump 123 further pressurizes the water, passes through the high-pressure feedwater heater];
Supply water to 1A. In a nuclear reactor, this is heated to produce steam. Low-pressure and high-pressure feedwater heaters heat feedwater using steam from a turbine. Drain generated by heat exchange is temporarily stored in the feed water heater, and the drain water level is controlled to be maintained at a specified value.During normal times, it is discharged to the next stage feed water heater via the regular control valve 6, and when used in an emergency. The water is discharged to the condenser 105 via the emergency control valve 8. In the low-pressure feed water heater 111, both the regular control valve 6 and the emergency control valve 8 discharge condenser hedrum, but the regular control valve 6 discharges condensate via a drain cooler (not shown) in the low-pressure feed water heater 111. , the emergency control valve 8 often discharges drain that has bypassed this drain cooler.Although the details of the water level control device of the feed water heater are omitted in Figure 10, similar to thermal power plants, nuclear power plants It is obvious that the present invention can be applied to water level control devices for feed water heaters.

The drain separated by the moisture separator 141 is temporarily stored in the moisture separator drain tank 142, and its water level is controlled to a specified value, and in normal times it is sent to the low-pressure feed water heater 114 via the regular control valve 6. In an emergency, the water is discharged to the condenser via the emergency control valve 8. Although details of the control system are omitted, the first aspect of the present invention
It is obvious that the control system shown in the figure can be applied.

Next, an example of an evaporator is shown. In BWR nuclear power plants, evaporators are installed to obtain steam with low or no radioactivity. Also, to reduce the consumption of high-purity condensate in thermal power plants.

Evaporators are often installed to create steam from low-purity water and consume this steam.

In the example shown in FIG. 10, steam from the turbine is transferred to the evaporator 151.
The drain generated by this heat exchange is temporarily stored in the evaporator drain tank 152, and the water level is controlled to a specified value, and the water level is normally adjusted. Condensate is discharged to the low-pressure feed water heater 113 via the valve 6 and, in an emergency, to the condenser 105 via the emergency control valve 8. Although details of the control system are omitted, it is clear that the control system of the present invention shown in FIG. 1 can be applied.

FIG. 11 is an example of a schematic system diagram when a moisture separator preheater 160 is installed in place of the moisture separator 141 in the nuclear power plant of FIG. 10.

It mainly shows the portion related to the moisture separator reheater 160. The steam generated in the nuclear reactor 101A does some work in the high-pressure turbine 102 and is sent to the moisture separator reheater 160. It is composed of a separation separator 141 (same as that explained in FIG. 10), a first stage reheater 161A, and a second stage reheater 161B. The steam from the high pressure turbine 102 is separated from the moisture in the steam by a moisture separator 141, the separated drain is sent to the moisture separation drain tank 142, and the steam from which moisture has been removed is sent to the first stage reheater 161. Sent. This steam is heated by steam extracted from the high-pressure turbine 102 and sent to the second stage reheater 161B. On the other hand, extracted steam from the high-pressure turbine is condensed through heat exchange and becomes drain, and is sent to the first stage reheater drain tank 162A and stored therein. The steam sent from the first stage reheater 161A to the second stage reheater 161B is further heated by the steam from the nuclear reactor 101A and sent to the low pressure turbine 104 to perform work.

Heating steam from the nuclear reactor 101A is condensed through heat exchange and becomes drain, which is stored in the second stage reheater drain tank 162B. The water levels in the first and second stage reheater drain tanks are controlled to specified values, and are connected to the high-pressure feed water heater 132 via the regular control valve 6 during normal times and via the emergency control valve 8 during emergencies. The condensate is discharged to the condenser 105. Although details of the control system are omitted, it is clear that the control system of the present invention shown in FIG. 1 can be applied.

Figure 12 shows the boiler 10 of the thermal power plant shown in Figure 9.
1 is an example of a schematic system diagram showing the internal configuration of the system. Water is supplied from the high-pressure feed water heater through the energy saver 201 and the furnace wall water pipe section 202.
The water is sent to the steam separator 211 via. Here, steam and water are separated and the steam is separated into the primary superheater 221 and the secondary superheater 2.
22 and a tertiary superheater 223 to the high pressure turbine to do some work.The exhaust gas of the high pressure turbine is sent to the boiler 10 again.
1, is reheated in a primary reheater 231 and a secondary reheater 232, and is sent to an intermediate pressure turbine. Steam water separator 211
The separated drain (moisture) is temporarily stored in the steam/water separator drain tank 212, and the water level is controlled to a specified value.
The boiler recirculation pump 213 pressurizes the drain, and the condensate is recirculated to the economizer 201 via the regular control valve 6. When the amount of drain is small, the boiler recirculation pump 213 is stopped,
Drainage is discharged to the condenser via the emergency control valve 8.

FIG. 12 shows an example of a once-through boiler. Generally, when starting the boiler, the boiler recirculation pump 213 is operated until an evaporation amount of about 10 to 25% is obtained, and the minimum flow rate of the economizer 201 and the furnace wall water pipe section 202 is controlled. 1 and 5 of the present invention, although the details of the water level control device of the steam-water separator drain tank 212 shown in FIG. 12, which is often operated to ensure the same, are omitted.

It is obvious that the control system shown in FIG. 6 can be applied.

〔Effect of the invention〕

According to the present invention, a circuit that can directly calculate the signal from the detection section and provide it to the operation section is installed in parallel to the main control calculation circuit of the emergency control system, so that the control amount exceeds the specified range. When an abnormal condition occurs, the output of this circuit is given priority to the operation unit, so it is possible to avoid a delay in response of the main control calculation circuit, and to strengthen and enhance the backup function that should originally be provided for emergency use. Can be done.

In particular, if the main control calculation circuit of the emergency control system includes a circuit that forcibly operates the operating section due to external interlock conditions, the present invention can provide backup even when forced operation is activated due to the interlock. The function operates and produces a remarkable effect that ensures the safety of the system.

Further, when the present invention is implemented with a digital (electrical) controller, it can be handled by simply adding and changing the software, which has the advantage of improving functionality without increasing costs.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the process control device of the present invention. Fig. 2 is a characteristic diagram of the function generator of this embodiment, Fig. 3 is a diagram showing the feed water heater drain tank water level control device, Fig. 4 is a diagram of a conventional example, and Figs. 5 and 6 are diagrams of the controller. System diagram of program control, Figure 7 is a characteristic diagram of the controller. Figure 8- is an explanatory diagram of the control characteristics during a sudden increase in condensate condensate, Figure 9 is a system diagram of a thermal power plant, Figure 10 is a diagram of a nuclear power plant system, and Figure 11 is a diagram of a moisture separator reheater. Fig. 12 is a system side view of a boiler in a thermal power plant. 2...Drain tank, 3...Water level detector, 4,7.
... Drain pipe, 5... Drain pump, 6, 8... Control valve, 11.13, 15, 21.21, 1.21-2゜21.3, 23.25... Signal line, 12.22・
...Controller, 14,24...Electro-pneumatic converter, 12.1゜22.1...Deviation calculation section, 12.2, 22.2...
Control calculation section, 12.3, 22.3... Integral saturation prevention calculation section, 12.4, 22.4... Manual/automatic switching device, 2
2.5...Function calculator, 22.6...High level signal selector, 12.11...Slow opening signal generator, 12.12...
・Full close signal, 22・11... Rapid open signal generator, 22・
12...Slow closing signal generator.

Claims (1)

[Claims] 1. A detector that detects a controlled variable of a process control target, an adjustment section that receives a signal from the detection section, compares it with a target value, and performs a control operation on the result, and A regular control system consists of an operation unit that receives signals from the control unit and acts on the controlled object, and a regular control system that receives signals from the detection unit (or a detection unit provided independently) during emergencies, compares them with target values, and performs control based on the results. An emergency control system consisting of a control section that performs calculations, an operation section that receives signals from the control section and acts on the controlled object in an emergency; When an abnormal condition occurs, the signal is input to generate a predetermined operation signal, and in place of the signal from the adjustment section in the emergency control system,
A process control device comprising: means for inputting information to the operation section; 2. The process control according to claim 1, wherein the adjustment section within the emergency control system is provided with means for forcibly operating the operation section within the emergency control system according to an interlock condition from the outside. Device. 3. The process control device according to claim 1 or 2, wherein the process control target is a drain tank, and the detection section detects the water level in the drain tank. 4. The process control device according to claim 1 or 2, wherein the process control target is a feed water heater, and the detection section detects the water level in the feed water heater.