JPS58108396A - Protector for heat exchanger - Google Patents

Abstract

PURPOSE:To enable a heat exchanger to be protected by an arrangement wherein even when the heat exchanger is not in use, a predetermined amount of fluid at a high temperature is allowed to flow through a high temperature fluid piping system to effect preheating and the fluid flow is interrupted every predetermined time so that the temperature drop between two points in the system may be detected. CONSTITUTION:When the heat exchanger is operated at a high load, a control circuit 100 transmits a command signal so that a condensate recovery regulating valve 12 leading to a deaerator 13 and a dump valve 15 leading to a condenser 10 are fully shut off, both valves 12 and 15 being connected through a heat exchanger 5 to a water separator 65, and the feed water supplied by a pump 1 flows through a feed water heater 3 and a boiler 6 so that it may be converted completely into steam and supplied into a turbine 9. Under this condition, in order to warm up a starting bypass system, values 14 and 16 are opened to warm up the upstream sides of the valves 12 and 15. If leakage happens in the heat exchanger 5, then the feed water under a high pressure flows backward to cool the water separator 65. To prevent this, the control circuit 100 serves to close the valve 14 for a predetermined time at regular intervals and measure the temperature drop according to the signals from temperature detectors 20, 21 of an inlet bypass pipe 11A of the heat exchanger 5 thereby checking of any leakage occurs or not.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat exchanger maintenance device, in particular a heat exchanger that exchanges heat between a high pressure fluid and a low pressure fluid. is low pressure fluid 11
A heat exchanger with a temperature of 5K can be detected to detect any leakage.

Generally, a heat exchanger is a device that transfers heat between a high temperature fluid and a low temperature fluid, and is installed in a portion of an industrial plant, nuclear power plant, etc. where heat exchange is required. Also, among the above heat exchangers, it can be used in high pressure systems.
It is constructed of thick granite so that it can withstand the high pressure.

By the way, among the heat exchangers used in the high-pressure system Kgl of a die 2 engine equipped with a transverse R unit, there are those that are used only when the plant is stopped or under low load, and are not used during excessive rolling. be.

However, even during this long rolling, the heat exchanger is under high pressure Kl, so if the high-pressure low-temperature fluid (for example, feed water) leaks, the steam-water separation tank of the once-through boiler, etc. There is a risk of rapid cooling, which could lead to a major accident.In addition, a sudden drop in main steam temperature may cause damage to the plant, etc.
There is a possibility that this could lead to an accident involving the turbine.

Furthermore, as is well known, the rate of load change in thermal power plants is becoming faster year by year. Therefore, depending on the change in load, the heat exchanger can be rapidly changed from a used state of 1 m (heat exchange state It) to an unused state (heat exchange not required state), or conversely be changed from an unused state to a used state. It turns out. As a result of being used in a state where heating and cooling are repeated in this way, high thermal stress is applied to the heat exchanger as a thick-walled container, resulting in heat exchange 4! ! There is a risk that ivy may occur.

The purpose of the present invention is to eliminate the disadvantages of the above-mentioned prior art,
The present invention provides a heat exchanger protection device that protects a heat exchanger by suppressing the occurrence of thermal stress and detecting leakage of high-pressure fluid.

In order to achieve the above object, the present invention preheats a predetermined amount of high-temperature fluid by flowing it into a high-temperature fluid piping system including a heat exchanger even when the heat exchanger is not in use, and the flow of the high-temperature fluid is stopped at regular intervals, and the temperature drop of the high-temperature fluid at at least two different points in the high-temperature fluid piping system near the heat exchanger at this time is detected.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

Iris 18 is a heat exchanger maintenance device related to the book: i&WAK.
lIIIAf! Between strains showing 4! be. As shown in FIG. 1, the first embodiment of the present invention is constructed as follows. Reference numeral 1 denotes a pump, and this pump l has its discharge side connected to the inflow part of the high-pressure feed water heater 3 via piping 2,
The pump IK increases the pressure of feed water as a low-temperature fluid and supplies it to the high-pressure feed water heater 3. This high-pressure water supply heating ls3 is a device that heats the high-pressure water supplied from the inflow part to a constant temperature and supplies it from the outflow part,
Water supply pipe 4A whose outflow part is a high-pressure low-temperature fluid pipe
The high-pressure water supply is made to flow into the water supply pipe 4AK. The heat exchanger @5 connected to the water supply pipe 4At and the low-temperature side inflow part Kil has its low-temperature side outflow part connected to the [boi I) 6 via the water supply pipe 4B, and during heat exchange, K
), high-pressure feed water flows through the heat exchanger lIs. The heat exchange @lI has a high-temperature side inflow and a high-temperature side outflow in addition to the above-mentioned 9 low-temperature side inflow and This is a device that can only be replaced. The water supply pipe 4A and the water supply pipe 48, which have a heat exchanger of 5 km in length, have a pipe diameter of 5.

The boiler 6 supplies water supplied from the water supply pipe 4B to an economizer 61, a water wall pipe 62, and a cage wall pipe 6s.

The steam separated from steam and water by the steam separator 65 is further supplied to a primary superheater 66, a secondary superheater 67, and a tertiary superheater 68. The steam is superheated and supplied to the turbine 9 via the steam pipe 8. This turbine 9 has a condenser lO on its exhaust side.
This is a continuation of Part II.

The condensate separated in the steam/moisture III device 65 of the boiler 6 is supplied to the heat exchanger 5 from the high-temperature side inlet of the heat exchanger 5 via the startup bypass piping 11A as a low-pressure high-temperature fluid piping system, The hot water after being heat exchanged in this heat exchange III is transferred from the high temperature takide part to the bypass pipe 11B.
In other words, the condensate 11 is circulated to the deaerator 13 via the condensate recovery valve 12. In other words, the condensate 11*joint valve 12 is connected to the high temperature side outflow part KIII of the axillary heat exchanger 5. Condensation water is distributed between the terminal end of the bypass pipe 11B as a high-temperature fluid piping system and the deaerator 13, and when the valve 12 is closed when no heat exchange is performed, the high-temperature fluid is condensed into the heat exchanger 5. ’.

The piping near the front and back of the condensate wJ collection control valve 12 has a first
Connect opening/closing 5P14 and open when no heat exchange is performed to allow a predetermined amount of high-temperature fluid to flow into the high-temperature fluid piping system that covers the bypass piping 11A, the heat exchanger 5, the armpit bypass piping 11B and the wrinkle IIIfIs valve 12, These are set to 1114. Moreover, the -bypass piping 11A is
The dump valve IsK is connected to its end, and the dump valve Is is connected to the condenser 10. The bypass piping 11A is
A second control valve 16 is connected near the furrow between the armpit dump valve 15 and the cough bypass pipe 11A, and the second control valve 16
is mmb for degassing 1B131. Incidentally, the deaerator 13 is designed to absorb water from the pump 1 and supply water.

Furthermore, the control circuit 100 monitors the load state by taking in signals related to the rotational speed of the turbine 9, the condition MK of the generator, and other signals, closes the bypass valve 7 at startup, and closes the bypass valve 7 when the load is below the boiler minimum water supply amount. At times, the control valve 12 and the dump valve IS are controlled to open and close, and the first and second on-off valves 14 and 16 are controlled to close, and when the load is high, the control valve 12 and the dump valve 15 are closed, and the pipe/spring valve IS is controlled to close. 7
is released, and the first and second on-off valves 14 and 16 are controlled to open. The operation of the first embodiment configured as described above will be explained below.

First, the feed water pressurized by the feed water pump IK is supplied to the boiler 6 through the high-pressure feed water heating tank 3, but during this time it is passed through the heat exchanger 5 in order to recover the heat of the high temperature fluid flowing through the startup bypass arrangement 111A. west,! Dentsu and setback device 61
supply to. The water supply is provided through a wall pipe 62, a cage wall pipe 63,
It is supplied to a steam/moisture meter 65 via a ceiling wall pipe 64. This air and water separation! The condensate separated into steam and water at 65 is supplied to the heat exchanger IK via the startup bypass piping IIA. The hot water after this heat exchange is circulated through the deaerator ISK via the bypass pipe 11B and the control valve 12.

On the other hand, the steam separated in the steam separator 65 is superheated in the primary superheater @@@, the secondary superheater 6γ, and the tertiary superheater 68, and is supplied to the turbine 9 via the pipe 8.

In addition, when the load is lower than the boiler minimum water supply amount and the control circuit 10
If it is determined to be 0, the control valve 12 and dump valve 15 are controlled by the control circuit 100 according to the load state.

When the control circuit 100K determines that the load is high,
The condensate recovery adjustment valve 12 and the dump valve 1s to the deaerator 13 are completely closed by a command from the control circuit 10G, and all the water supplied to the boiler 6 becomes steam and is supplied to the turbine 9. Therefore, this state type is St
In order to warm up the startup bypass system, the on-off valves 14 and 16 are opened to warm up the entire startup bypass system. That is, the steam separator 65, the startup bypass piping 1
1A, the heat exchanger 5, the control valve 12, and the upstream side of the dump valve 15 are warmed up by flowing fluid, and the fluid after warming up is collected in the deaerator 13. According to this embodiment, heat loss is small and noodles can be prepared with as much heat as the amount of heat dissipated.

Next, a second embodiment of the present invention will be described. The second example is
This embodiment has the same structure and functions as the first embodiment, and has the following additional features. That is, at least two high-temperature fluid temperature detectors 20 and 21 are disposed at two different points on the bypass pipe 11A as the high-temperature fluid piping system on the inlet side of the heat exchanger 5.
1 to detect the temperature, and to input the detection signal to the control circuit 100. The control circuit H)0 fully closes the first N4 closing valve 14 at regular intervals, and detects and compares the degree of temperature drop for a specified time based on the temperature detection signals from the temperature detectors 20 and 21. , and the difference exceeds a predetermined value, a IIIK report signal or a signal for stopping the device is generated. As described above, the control enclosure 10G has the configuration of the i1th example, and further has the ** added as described above. 1Ili2Kit, and the diagram showing the configuration for this additional lj is a vine diagram. In this II, the code 10
1 is the grogtsumu timer, and this pugasugugumumeima 1
01 sends a signal to the solenoid part 14 of the mist closing valve 14 to close the on-off valve 14 of the bird type only when the constant period Tl1K is specified.
When the solenoid 14A is activated and the valve body 14B is closed by the close signal of the timer 101, this MwA valve 14ffC$9 outputs AK.
The contact 14C of the attached switch is closed,
Conversely, the valve 14B is opened (and the contact 14C is released. This contact 14C connects one electric current m to the DC power supply 2).
The auxiliary relay 102 is energized by the negative 11(-) KIIaL of the DC current g and the z configuration of the negative 414C through the auxiliary relay 102 connected to the other electrode.

This auxiliary relay 102 has contacts 102A, 102B, and 102C, and is configured to move in the direction of the arrow in the figure when the coil of the auxiliary relay 102 is energized.

-j) 103 and 104 are amplifier circuits, and these amplifier circuits 103 and 104 take in the detection signals from the temperature detection m2o and 21, and amplify them to a constant /Tr voltage signal. The output end of the extension 411 circuit 10m is connected to the normally closed contact of the relay contact 102A, and a signal is supplied to the analog memo V garden path 105 via this contact. This Anatomy Memory Encirclement 105 is
The output end is connected to the partial MIL calculation circuit 106, and the contact point 102 is connected to the terminal 106. Connect to the IN contact. This deviation calculation circuit 1()lt is configured to input the output signal of the amplification circuit #&104 and output it with a deviation from the signal from the 7pg memory circuit 105, and its output terminal is compared. It is connected to the s circuit 107. This proportional rotation ji1107 is.

The output terminal is connected to the normally #I contact Km of the relay contact 102B, and when the normally open contact is closed, it is connected to the analog-to-digital conversion circuit 108 K is configured to provide an output signal.

This AD conversion circuit 10B digitizes the input signal, and when the input signal exceeds a predetermined value, an I.D.
k so as to close the KII point 1611. This contact 10G is connected in series with the contact 102C and the coil of the auxiliary relay 110 to connect DC current 11Kii, and both contacts 10G
and 102C are closed at the same time, the coil of auxiliary relay 11G is energized. Auxiliary relay 11G
When the power is turned on, the alarm 11II and the tread 111 are designed to issue an alarm. Further, the contact 110A may be used to generate a signal to stop the device. Note that the reference numeral 112 is 111 勺 1ilJLI! And its output end is the normally closed IF of relay contact 102B! AKIi installation, AD conversion circuit 1
08 is constantly supplied with an 0% flaw signal to prevent malfunction when not in use. Therefore, the signal generation @112 is not necessary if countermeasures are taken against the - operation.

The operation of the second embodiment configured as described above will be explained below.

In the heat exchanger 5, the pressure on the water supply side is high, so if there is a leak, the water supply as a high-pressure low-temperature fluid will flow backwards and become steam/moisture @Mackerel S
S will be cooled down. Therefore, in this embodiment, the fixed time T
The on-off valve 14 is fully closed for a specified time t every time, and the heat exchanger 5 is closed.
Temperature sensor 2 provided with bypass piping 11AK on the inlet side of
Based on the detection signals of 0 and 21, we determined the temperature failure in those parts and confirmed that there was no leakage in the heat exchanger for 5 km.
It is something to do.

In other words, high load operation occurs and the control valve 12 and dump valve 1
5 is closed by the command of the control circuit jl100, and the first
and the second battle closing jf14 and l. Then,
The on-off valve 14 is
is closed for a constant time t at a constant time T*. Then,
Contact 14C is closed (auxiliary relay 102 is energized).

When the auxiliary V-102 is energized, 4! r111 points 10
2A, 10j! B and 102C each move in the direction of the arrow in the figure.

The analog memory (b) path 105 stores the detection signal of the moisture detector 20 at the time when the on-off valve 14 is closed, and performs the deviation calculation 11.
Supply to jlllG@. The deviation calculation circuit lO6 uses the signal from the temperature detector 21 and the analog memory circuit 10.
Subtract 1 or 1 and convert the result of the calculation to the proportional - 10
7 to the ADfR conversion circuit 108. When the deviation signal from the deviation calculation circuit lO6 is large, it is assumed that KgII leakage has occurred in the heat exchanger 5, and the contact 1 (l
is closed, and on condition that relay contact 102C is closed, auxiliary relay 1101 is energized, and relay contact 110 is energized.
A is closed, the alarm S circuit 111 is activated, and an alarm is issued. Furthermore, if the deviation signal from the deviation calculation circuit 106 is small, the contact 1011 remains open at tK. In other words, in this control circuit 100, the temperature detection signal from the temperature detection amount 20 that occurs when the on-off valve 14 is closed is stored, and the temperature is detected for a specified time t! ) 21 temperature detection signals are compared with the above-mentioned stored values, and if the deviation signal is below the temperature of normal heat dissipation, the contact 109 is not closed, and if there is a leakage of 11 Kml from the heat exchanger, teeth,
Temperature sensor 20 drops faster than it would with normal heat dissipation, and then temperature sensor 21 drops in temperature quickly.

However, since the detected temperature signal from the detector 20 immediately after closing the on-off valve 14 is stored and compared with the quantity temperature sensor 21 for the specified time t, the deviation can always be detected.

The second embodiment operates as described above. Furthermore, since the configuration is as described above, the temperature detectors 20 and 2
1 warm 1ILpI! Since the approximate amount of leakage can be determined from the time difference between starting # and the volume of the piping 11A during this time, it is extremely advantageous for the subsequent #6 filling.

When the load is high, the bypass valve 7 of the heat exchanger 5 is fully open, but a small amount of water supplied by the valve 7 flows through the heat exchanger 5 to compensate for the pressure loss, so the thick walled portion on the water supply side is warmed up.

As described above, according to the present invention, it is possible to warm up the
Since the generation of thermal stress can be suppressed and leakage of high-pressure fluid can be detected, the heat exchanger has an excellent effect of being able to be protected.

Table drawing simple it32811

Claims (2)

[Claims] (1) A heat exchanger that is connected to a low temperature fluid piping system and a high temperature fluid piping system and exchanges heat between the fluid flowing in the piping, and a heat exchanger that is connected to the low temperature fluid piping system and is connected to the heat exchanger when heat exchange is not required. a bypass valve for bypassing the low-temperature fluid; a control valve for controlling the high-temperature fluid piping system Kli on the outlet side of the heat exchanger so as not to flow the high-temperature fluid to the heat exchanger when heat exchange is not required; 1131 There is an on-off valve that allows a predetermined amount of high-temperature fluid to flow even when heat exchange is not required, and a shut-off valve that monitors the heat load condition and opens the bypass valve and on-off valve when heat exchange is not required. 1. A heat exchanger protection device comprising: a control circuit for controlling opening and closing of a one-section valve. (2) A heat exchanger connected to the low temperature fluid piping system and the hot fluid piping Jl& for exchanging heat between the fluids flowing in the piping, and a heat exchanger connected to the low temperature fluid piping system when heat exchange is not required. a bypass valve for bypassing the low-temperature fluid flowing into the high-temperature fluid piping system on the outlet side of the heat exchanger; a control valve for preventing the high-temperature fluid from flowing through the heat exchanger when heat exchange is not required; an on-off valve connected before and after the heat exchanger to allow a predetermined amount of high-temperature fluid to flow even when heat exchange is not required; at least two temperature detectors disposed at different parts of the elevated fluid piping on the inlet side of the heat exchanger; When heat exchange is not required, the bypass valve and the on-off valve are opened, and the on-off valve is fully closed for a specified time at regular intervals, and the temperature is detected at this time. 41. A control circuit that generates an alarm or a device stop signal based on the temperature detection signal from the device.
Hk heat exchanger protection device.