JPS6017963B2 - Heat exchanger secondary fluid temperature control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates primarily to improvements in a secondary fluid temperature control device for a heat exchanger applied to a steam generation plant.

As a steam generation plant equipped with a countercurrent heat exchanger and using a nuclear reactor or the like as a heat source, the one shown in FIG. 1 is known.

In the figure, 16 is a heat source such as a nuclear reactor or an intermediate heat exchanger, which heats the heating fluid to a high temperature.

The heating fluid heated to a high temperature here is transported to the steam generator through the pipe 25. The steam generator is composed of a superheater 1, a steamer 2, and pipes 27 and 28 that connect these, and the heated fluid that is transported passes through the superheater 1 and then passes through the pipe 2.
8 to the evaporator 2. On the other hand, the water supply pump 14
Water is supplied to the steam generator through 23.
This water exchanges heat with the heating fluid in the evaporator 2 to generate steam, and this steam is sent to the superheater 1 via piping 27, where it further exchanges heat with the heating fluid to increase the degree of superheating. . The obtained superheated steam is supplied to load equipment such as a turbine via the steam pipe 24, and the pressure is normally adjusted to a predetermined pressure value by providing a pressure regulating valve 15 in the steam pipe 24. Further, the heated fluid that has completed heat exchange in the evaporator 2 becomes low temperature and is returned to the heat source 16 through the pipe 26.

In such a steam generation plant, a large fluctuation in the steam temperature at the outlet of the evaporator 2 will adversely affect material strength and operation, so it is necessary to appropriately adjust the steam temperature.

For this reason, temperature control operations such as those described below have conventionally been performed.

The output request signal generator 3 issues an output request signal in accordance with the magnitude of the load on the turbine, etc., and the water supply flow rate control valve 9 adjusts the water supply flow rate so as to match the output request signal.

In the illustrated example, the output request signal is transmitted after being converted into a steam flow rate, that is, a feed water flow rate, and therefore, before being corrected by the adder 6, it is equal to the feed water flow rate target signal. by the way,
When changing output or receiving other disturbances, evaporator 2
Outlet steam temperature fluctuates.

Therefore, the temperature signal detected by the temperature detector 4 is fed back to the temperature target signal transmitter 17, and the PI controller (hereinafter referred to as
The P regulator is a proportional action controller, and the 1 regulator is an integral action controller).5 adjusts the feed water flow rate, thereby controlling the steam temperature at the outlet of the evaporator 2. In this case, P
The signal generated by the I regulator 5 is added to the output request signal by an adder 6, the flow rate signal of the feed water flow rate detector 8 is negatively fed back to the signal generated by the adder 6, and the PI regulator 7 controls the operation of the feed water control valve 9. send a signal.

On the other hand, for the heating fluid, a flow rate target signal is transmitted from the function generator 10 in accordance with the steam generator partial load characteristics.
A signal from the heating flow rate detector 11 is fed back to this, and the flow rate regulator 12 operates the rotation speed of the circulation pump 13. In the above-mentioned control operation, since the regulator 5 performs the control after the vapor temperature at the evaporator 2 outlet fluctuates due to a change in the flow rate of the heating fluid or the inlet temperature, etc., the control operation tends to be delayed. There is a problem that sufficient temperature fluctuation prevention effect cannot be obtained.

In particular, if an accident occurs in which the circulation pump 13 stops and the heating fluid flow rate rapidly decreases, the balance between the water supply flow rate and the heating fluid flow rate will be greatly impaired, and the steam temperature at the evaporator 2 outlet will fluctuate greatly, which will cause the above problem. becomes even more pronounced. Note that in order to improve the control performance, it is possible to incorporate differential operation into the regulator 5, but in reality, this poses a problem in terms of noise and is not a practical countermeasure. This invention was made in view of the above circumstances. For example, if we take the above-mentioned steam generation plant as an example, even if it is subjected to a disturbance that has a strong influence on the heating fluid flow rate or the heating fluid inlet temperature, the evaporator Provided is a secondary fluid temperature control device for a heat exchanger that can suppress large fluctuations in outlet steam temperature and keep it within design tolerances, and can avoid damage to a steam generator due to sudden changes in steam temperature. It is something to do.

That is, the present invention provides an apparatus including a primary fluid circulation system and a secondary fluid circulation system that maintain a heat exchange relationship via a countercurrent heat exchanger, in which a fluid circulation system provided in the primary fluid circulation system and connected to a central controller is provided. a secondary fluid flow rate controller including a first flow rate controller provided in the secondary fluid circulation system, a second flow rate controller provided in the secondary fluid circulation system, and a flow rate detector provided in the primary fluid circulation system; a temperature compensator including a temperature detector provided on the heat exchanger outlet side of the fluid circulation system; and a temperature compensator that is connected to the temperature compensator and the flow rate command unit to receive outputs from both, and a second flow rate controller that is connected to the temperature compensator and the flow rate command unit. It is characterized by having a phase adjuster connected to it, and a whale.

Hereinafter, the present invention will be explained in detail based on the embodiment of the steam generation plant shown in FIG.

Note that the behavior of water supply, steam generation, superheated steam, and heating fluid is the same as in FIG. 1, so a description thereof will be omitted. 1
0 is a heated fluid flow rate target signal generator, which receives a generated signal from the output request signal generator 3 and controls the heated fluid flow rate regulator 1.
2 control target values are generated.

12 is a heating fluid flow rate regulator; heating fluid flow rate detector 11;
The signal from the circulation pump 1 is fed back by negative feedback, and the PI operation
Operate the rotation speed in step 3.

21 is a function generator which receives the heated fluid flow rate signal from 11 and generates a feed water flow rate target signal.

A function generator 19 similarly generates a heated fluid temperature target signal.

The signal of the heated fluid temperature detector 18 and the target signal of the heated fluid temperature indicator signal generator 19 are sent to the P regulator 20 . The P regulator 20 transmits a signal that is amplified by a predetermined factor for the deviation between the signal 18 and the signal 19, and this signal is added and corrected to the water supply flow rate target signal of the function generator 21 in the adder 29. Add. Adder 6 adds the signals from adder 29 and PI controller 5. 22 is a phase lead compensator;
This is where phase lead compensation is applied to the water supply flow rate target signal transmitted by the adder 6.

The PI regulator 7 sends an operation signal for the water supply control valve 9 by negatively feeding back the flow rate signal from the water supply flow rate detector 8 to the water supply flow rate target signal transmitted by the phase lead compensator 22.
Adjust the water supply flow rate. According to the above-described device configuration, the function generator 10 provides a heating fluid flow rate target value that matches the steam generator partial load characteristics according to the required output, so that the heating fluid flow rate is controlled close to the target value.

At the same time, the function generator 21 provides a feed water flow rate target value that is balanced between the heating fluid flow rate and the evaporation generator partial load characteristics, and the feed water flow rate is additionally controlled to this target value.
Therefore, the heating fluid flow rate and the feed water flow rate are always kept in balance in terms of steam generator partial load characteristics, and the balance between heat input and heat output of the steam generator is also maintained. When the steam generator receives a control error or other disturbance and the steam temperature at the evaporator 2 outlet fluctuates, the PI control operation of the temperature controller 5 is activated to adjust the feed water flow rate, thereby changing the steam temperature at the evaporator 2 outlet. Fluctuations can be kept to a minimum. On the other hand, if the heating fluid temperature at the evaporator 2 inlet fluctuates, the steam temperature at the evaporator 2 outlet fluctuates significantly. a standard heating fluid temperature consistent with the function generator 19 is transmitted;
Based on the deviation between the detected heating fluid temperature value and the standard temperature, the P regulator 20 corrects the target water flow rate value.

This correction provides a proactive corrective adjustment of the water supply flow rate, so that the fluctuating response is effectively suppressed. In addition, if the heating fluid flow rate fluctuates significantly due to a failure of the circulation pump 13, etc., the target value of the water supply flow rate is given by the function generator 21 at a value corresponding to the actual fluctuation of the heating fluid flow rate. A balance between the heating fluid flow rate and the feed water flow rate is always ensured, and a balance between heat input and output from the evaporator 2 is also ensured, and as a result, fluctuations in the steam temperature at the outlet of the evaporator 2 are suppressed to a minimum.

On the other hand, in order to obtain a water supply flow rate that follows the corrected water supply flow rate target value generated from the adder 6, it is necessary to compensate for the delay in the water supply flow rate response caused by the delay in the control operation of the water supply flow rate regulator 7. be.

This compensation action is performed by the phase lead compensator 22 in the present invention. For example, the PI regulator transfer characteristic when there is no delay in the valve and negative feedback is applied to the water supply flow rate is typically given by the following equation.

T, S+1...'1'GP, (S
)=(10/KP)T, S+1 GP, (S);
PI controller transfer characteristic KP; proportional gain T,; integral time constant S; Laplace operator Therefore, in order to compensate for the delay due to GP, (S), a compensation element with the following characteristic Gc (S) can be used. .

1=GP, (S)・Gc(S).・．． Gc(S) 1 (111/KzuT, S+1 1 GP, 6) T, S+1 .・・・．・・・． ...'21 The compensation characteristic shown by the '21 formula is just an example, and the effect will be the same even if compensation elements based on other transfer function formulas with similar characteristics are used. .

As is clear from the above, in the conventional pupil system, the feed water flow rate target value was given according to the outlet request signal, but according to the device of the present invention, it matches the steam generator partial load characteristics based on the actual heating fluid flow rate. As a result, the balance between heat input and heat output of the steam generator is always maintained during plant transitions such as when changing output.

As a result, it is possible to achieve the effect that fluctuations in the vapor temperature at the evaporator outlet are always suppressed to a minimum. In addition, if the temperature of the heating fluid at the evaporator inlet becomes an abnormal temperature that deviates from the steam generator partial load characteristic, the feed water flow rate is adjusted in advance according to the deviation, so that the heat input and output of the evaporator can be adjusted. The heat balance is always maintained, resulting in the effect that fluctuations in the steam temperature at the evaporator outlet are suppressed to a minimum. Furthermore, unlike the conventional method, the target value of the feed water flow rate is finally compensated for by phase advance, so the delay in operation of the feed water flow rate is eliminated, and the balance between heat input and heat output of the evaporator can be more perfectly maintained. As a result, fluctuations in the evaporator outlet steam temperature can be suppressed to a minimum.

Furthermore, if the flow rate of the heated fluid fluctuates significantly and suddenly due to a malfunction of the heated fluid circulation pump in the secondary,
Because the operation to balance the feed water flow rate was performed as a control operation to recover from temperature fluctuations after fluctuations in the evaporator outlet steam temperature occurred, large fluctuations in the evaporator exit steam temperature were likely to occur. Although there was a problem, according to this invention, the effect of obtaining a water supply flow rate that is always balanced with the actual flow rate of the heating fluid is achieved, so that fluctuations in the steam temperature at the evaporator outlet can be minimized. I can do it.

Therefore, this invention makes an industrially significant contribution not only to the evaporator superheater separated type once-through steam generator for FBR, but also to the general field of heat exchangers combined with countercurrent heat exchangers.

[Brief explanation of the drawing]

The drawings show a steam generation plant; FIG. 1 is a conventional example, and FIG. 2 is a configuration diagram of an embodiment of the present invention. 1... Superheater, 2... Evaporator, 3...
Output request signal generator, 4...Evaporator outlet steam temperature detector, 5...Evaporator outlet steam temperature PI controller, 6...
... Evaporator outlet steam temperature control adder, 7... Feed water flow rate PI controller, 8... Feed water flow rate detector, 9... Water feed flow rate control valve, 10... Heating fluid flow rate target Signal generator, 11... heated fluid flow rate detector, 12... heated fluid flow rate regulator, 13... heated fluid circulation pump,
14... Water supply pump, 15... Steam generator outlet valve, 16... Heating fluid heat source, 17...
...Evaporator outlet steam temperature target signal generator, 18...
Evaporator inlet heating fluid temperature detector, 19... Heating fluid temperature target signal generator, 20... P regulator for heating fluid temperature deviation signal amplification, 21... Water supply flow rate target signal generation 22... Phase lead compensator, 29... Inlet heating fluid temperature correction adder. Figure 1 Figure 2

Claims (1)

[Claims] 1. In a device equipped with a primary fluid circulation system and a secondary fluid circulation system that maintain a heat exchange relationship via a countercurrent heat exchanger, a secondary fluid circulation system provided in the primary fluid circulation system and connected to a central controller. a secondary fluid flow rate controller including a first flow rate controller, a second flow rate controller provided in the secondary fluid circulation system, a flow rate detector provided in the primary fluid circulation system; a temperature compensator including a temperature detector provided on the heat exchanger outlet side of the system;
2 of a heat exchanger characterized in that a phase adjuster is connected to the temperature compensator and the flow rate controller, receives the output thereof, and is also connected to the second flow rate controller. Next fluid temperature control device.