JPH0211806A - Moisture separating heater anomaly detector - Google Patents

Abstract

PURPOSE:To improve the safety of equipment by outputting a deviation signal on the basis of a heating steam flow rate signal which flows into one heater, the sum of a drain flow rate signal supplied from said heater and a vent flow rate signal, or a heating steam flow rate signal which flows into an another heater. CONSTITUTION:When one heat transmission pipe of the first stage heater 6 is broken, and the heating steam which flows inside passes through the broken part and is jetted into the heated steam, the stream quantity which is introduced into the vent pipe 27 of the first stage heater 6 sharply reduces, and also the drain quantity which flows in a drain recovery pipe 19 reduces. Therefore, the value of the first stage heating steam outlet flow rate signal (g) reduces, and a deviation signal (h) which is transmitted to a flow rate anomaly detecting circuit 40 from a calculator 39 increases. Since this deviation signal (h) exceeds a previously set value in the detecting circuit 40, the first stage heating steam quantity anomaly signal (i) is inputted into a timer 41 in continuation, and the first stage heater heat transmission pipe anomaly generation signal (j) as alarm is transmitted from a moisture separating heater anomaly detecting circuit 34 into an outside device.

Description

Detailed Description of the Invention [Objective of the Invention 1] (Industrial Application Field) The present invention relates to a steam turbine plant, and particularly to a steam turbine plant located between a high-pressure turbine and a low-pressure turbine to remove moisture contained in cycle steam. The present invention relates to an abnormality detection device attached to a moisture separation heater configured to remove moisture and further heat the moisture separation heater.

(Prior art) Generally, in a steam turbine plant for nuclear power generation, the steam generated in the nuclear reactor is saturated steam or slightly moist steam, and when this steam expands in the high-pressure turbine, the humidity level is less than 10%. The value is so large that it exceeds the limit. If this steam containing a large amount of moisture is directly sent to the low-pressure turbine, the flow of steam will be significantly inhibited by the moisture1, leading to a decrease in efficiency and the rotor blades etc. being eroded by the moisture. To avoid problems, various measures have been taken to keep the moisture content within 1%. A typical mechanism is a method in which a moisture separation heater is provided in the path of a reheat steam pipe connecting a high-pressure turbine and a low-pressure turbine, and the structure is approximately as follows.

That is, in FIG. 4, steam generated in a nuclear reactor 1 is led to a high-pressure turbine 3 via a main steam pipe 2, expands there, and then passes from the high-pressure turbine 3 through a reheat steam pipe 4 to a moisture separator. 5. First stage heater 6 and second stage heater 7
is introduced into a moisture separating heater 8 having a In the moisture separator 5, most of the moisture in the steam is removed, and then in the first and second stage heaters 6.7, the remaining moisture is evaporated by the heated steam, and the moisture is separated. At the outlet of the heater 8, it becomes superheated steam. Here, as the heating steam of the first stage heater 6, steam extracted from a suitable pressure stage of the high pressure turbine 3 and sent through the first stage heating steam pipe 9 may also be used as the heating steam of the second stage heater 6.
Steam extracted from the main steam pipe 2 and sent through the second stage heating steam pipe 10 is used as the heating steam for the stage heater 7, respectively.

The steam is then led from the moisture separation heater 8 through the reheat steam pipe 4 to the low pressure turbine 11 where it expands to perform work and is discharged as exhaust to the condenser 12 where it is condensed. Condensate is extracted from the condenser 12 by the condensate pump 13, sent to the low-pressure feedwater heater 1.4, and further sent to the high-pressure feedwater heater 16 by the feedwater pump 15, becoming high-temperature feedwater and supplied to the reactor 1. be done.

In addition, since the heated steam is condensed in the first and second stage heaters 6.7 and drain is generated, a first stage heated steam drain tank 17 and a second stage heated steam drain tank 18 are provided. The drain collection pipes] 9 and 20 are connected between them so that the drain can be collected.

In addition, the drain tank] 7.18 has a water level gauge of 21.22.
are provided respectively, and the opening degree of the control valve 25.26 provided in the path of the drain pipe 23.24 connecting the tren tank 17.18 and the high-pressure feed water heating 16 is set to this water level = 121.
．． The water level is regulated by the water level signal sent from 2B and kept constant. In addition, the first and second stage heaters 6.7 and the high pressure feed water heater 16 are connected by a first stage heating steam vent pipe 27 and a second stage heating steam vent pipe 28, so that a small amount of The heated steam is allowed to flow through these vent pipes 27, 28 to the high pressure feed water heater 16. Note that reference numerals 29 and 30 in the figure indicate first-stage and second-stage heating steam stop valves, respectively.

(Problem to be solved by the invention) By the way, the first stage and second stage heaters 6.7 are a type of so-called multi-tubular heat exchanger, and heat exchanger tubes are used as elements constituting the heat transfer surface. are used a lot. In this case, the heated steam flows inside the heat transfer tube and releases heat to the steam on the cycle side separated by the heat transfer surface, causing the temperature to drop. However, if a breakage accident occurs in the heat transfer tube for some reason, Due to the pressure difference, the heated steam passes through the broken part and blows out into the steam on the cycle side, and both steams mix, pass through the moisture separation heater 8, and flow into the reheat steam pipe 4. If such an unexpected situation occurs and is left as it is, the following problems will occur in the low pressure turbine 11 and the moisture separation heater 8.

That is, although one moisture separation heater 8 is simplified in FIG. 4, a plurality of moisture separation heaters 8 may be incorporated, and separate reheat steam pipes 4 may be installed. When the steam flowing through is combined at the inlet of the low-pressure turbine 11, it passes through the area of the low-pressure turbine 11 that is in contact with the high-temperature steam from which there was a leak of heating steam, and the moisture separation heater 8 which is functioning normally. There is a risk that the temperature distribution will be uneven between the area that comes into contact with the steam at the appropriate temperature that flows through the area.

Therefore, there is a concern that non-uniform thermal expansion occurs in the low-pressure turbine 11, particularly the casing, which may cause contact with rotating parts.

On the other hand, the fracture of one heat exchanger tube exerts an excitation force due to high pressure steam on other adjacent heat exchanger tubes. At this time, the vibrations of the other heat exchanger tubes become intense, and if the natural frequency of the heat exchanger tube were to match, resonance would be caused and the other heat exchanger tubes would be damaged in a short period of time. .

Conventionally, no effective countermeasures have been taken against such abnormal situations of heat transfer tubes that cause damage to the moisture separation heater 8 and abnormal thermal expansion of the low pressure turbine 11, and no consideration has been given to the safety of these devices. It has been demanded.

SUMMARY OF THE INVENTION An object of the present invention is to provide a moisture separation heater abnormality detection device that promptly detects the occurrence of an abnormality in a heat transfer tube outside the moisture separation heater and improves the safety of the equipment.

[Structure of the Invention] (Means for Solving the Problems) The moisture separation heater abnormality detection device according to the present invention detects a heated steam flow rate signal flowing into one detected heater and flowing out from the other heater. a calculation device that performs calculations based on the sum of the drain flow rate signal and the vent flow rate signal, or the detected heated steam A amount signal flowing into another heater, and outputs a deviation signal, and a calculation device that outputs a deviation signal; The present invention is characterized by comprising a flow rate abnormality detection device that outputs a heating steam flow rate abnormality signal when the deviation signal generated exceeds a predetermined value.

(Operation) In the present invention, the arithmetic device receives the signal from the detector and generates a deviation signal based on the sum of the heated steam flow rate signal flowing into the - heater and the drain flow rate and vent flow rate signal flowing out from the heater. The device is configured to obtain a deviation signal based on a heating steam flow rate signal flowing into one or - heaters and a heating steam flow rate signal flowing into another heater, and is also output from this arithmetic device. Upon receiving the deviation signal, the flow rate abnormality detection device does not output the signal while the level is within a predetermined value range, but outputs a heating flow abnormality signal when the level exceeds the specified value. or each configured.

As a result, rupture of the heat transfer tube can be detected depending on whether there is an abnormality in the flow rate of heating steam between the inlet side and the outlet side of the - heater or between the - heater and other heaters. It becomes possible.

(Example) An example of the present invention will be described with reference to FIGS. 1 and 2. Note that in FIG. 1, the same components as those shown in FIG. 5 are denoted by the same reference numerals, and explanations thereof will be omitted.

In FIG. 1, the flow rate of heating steam extracted from the high-pressure turbine 3 and guided to the first stage heater 6 through the first stage heating steam pipe 9 is measured by a flow rate detector 31 and the first stage heater 6.
The flow rate of the drain introduced from the drain tank 17 to the drain tank 17 via the drain recovery pipe 19 is further determined by the flow rate detector 32.
The high pressure feed water heater 1 is passed from the stage heater 6 to the vent pipe 27.
6 is detected by the flow rate detector 33, and the first stage heating steam pipe 9 signal a1, the first stage drain flow rate signal S, and the first stage vent flow rate signal C are detected by the moisture separation heater abnormality detection device. 34. Further, the flow rate of the heated steam extracted from the main steam pipe 2 and guided to the second stage heater 7 through the second stage heating steam pipe 10 is detected by the flow rate detector 3.
5, and the flow rate of condensate led from the second stage heater 7 to the drain tank 8 via the condensate collection pipe 20 is determined by the flow rate detector 36, and further from the second stage heater 7 through the vent pipe 28, the high pressure is The flow rate of the vent guided to the feed water heater 16 is detected by the flow rate detector 37, and the moisture separation heater Abnormality detection device 34
is output to.

In FIG. 2, the moisture separation heater abnormality detection device 34 executes the following calculation based on these detected signals. That is, the first stage flow rate signal G and the first stage vent flow rate signal C are added by the computing unit 38, and the output thereof is outputted to the computing unit 39 as the first stage heated steam outlet flow rate signal g. In the computing unit 39, the first stage heated steam outlet flow rate signal g,
Based on the detected signal a of the first stage heating steam pipe 9, a calculation for determining the deviation is performed, and a first stage heating steam flow section difference signal is generated. This first stage heated steam flow rate difference signal is output to the flow rate abnormality detection circuit 40, and when the signal level is determined and exceeds a certain level, the first stage heated steam flow rate abnormal signal i is output to the timer 41. Output. Here, the timer 41 is configured as a time-limited return type, and outputs the first stage heater heat exchanger tube abnormality occurrence signal j when the human input signal is continuously applied for a certain period of time, and outputs this when the input time is not continued. It is designed not to.

On the other hand, the second-stage train flow rate signal e and the second-stage vent flow rate signal f are added by a computing unit 42, and the output thereof is outputted to a computing unit 43 as a second-stage heating steam outlet flow rate signal. The calculator 43 performs a calculation to obtain a deviation based on the second-stage heating steam outlet flow rate signal and the detected second-stage heating steam flow rate signal d, and calculates the deviation from the second-stage heating steam outlet difference signal 1. It will be done.

] 0 This second-stage heated steam flow rate difference signal l is output to the flow rate abnormality detection circuit 44, and when the signal level is determined and exceeds a certain level, the second-stage heated steam flow rate abnormal signal m is output to the timer 45. Served. Here, the timer 41 is configured as a time-limited return type, and when the second-stage heated steam flow rate abnormality signal m is continuously input for a certain period of time, the second-stage heater heat exchanger tube abnormality occurrence signal n is output.

Next, the operation of the moisture separation heater abnormality detection device having the above configuration will be explained. When there is no abnormality in the heat exchanger tube of the first stage heater 6, the first stage heating steam flow double number a added to the computing unit 39
and the first stage heated steam outlet flow signal g in the opposite direction are almost the same value, and the deviation signal sent from the computing unit 39 to the flow rate abnormality detection circuit 40 is almost zero, and is output by the flow rate abnormality detection circuit 40. It does not reach the point where it occurs. Therefore, the first stage heating steam flow rate abnormality signal i is not output to the timer 41 at this time.

On the other hand, in the first stage heater 6, when a break occurs in one of the heat transfer tubes and the heated steam flowing inside blows out into the heated steam through the broken part, the vent pipe 27 of the first stage heater 6 The amount of steam introduced decreases rapidly, and the drain recovery pipe 19
The amount of condensate flowing into the area also decreases. Therefore, the value of the first stage heating steam outlet flow rate signal g becomes smaller than before, and the deviation signal outputted from the three computing units to the flow rate abnormality detection circuit 40 becomes larger. Since this large deviation signal f exceeds the value given in advance to the flow rate abnormality detection circuit 40, the first stage heated steam flow rate abnormality signal i is continuously outputted to the timer 41, and the moisture separation heater abnormality is detected. The first stage heater heat exchanger tube abnormality occurrence signal j is issued from the device 34 as an alarm to an external device.

The above explanation is based on the assumption that a rupture occurs in the heat exchanger tube of the first stage heater 6, but the second stage heater 7 is also equipped with an equivalent means, and the rupture of the heat exchanger tube When an accident occurs, a second stage heater heat exchanger tube abnormality occurrence signal n is output.

Furthermore, the timer 41.45 of this embodiment is used to prevent unnecessary control operations from occurring in the event that the amount of drain and vent in the first and second stage heaters 6.7 is transient. The reliability of the device can be increased by setting an appropriate time.

In addition, in a moisture separation heater equipped with a two-stage heater,
The present invention is constructed in a simplified manner as follows. That is,
As shown in FIG. 3, the second stage heated steam flow double number d in the opposite direction is added to the first stage heated steam flow double number a guided by three calculations.

In this embodiment, we focused on the fact that the probability that the heat transfer tubes of both the first stage and second stage heaters 6.7 would break at the same time is extremely low, and the first stage heating steam flow doubles a and the second stage heating The presence or absence of an abnormality in each heat exchanger tube is determined from the deviation from the steam flow double number d. In other words, if there is no abnormality in the heat exchanger tubes of both the first and second stage heaters 6.7, the value output as the deviation signal is almost zero; The heat tube abnormality occurrence signal j-n is not generated.

On the other hand, if a rupture of the heat transfer tube occurs in the first stage heater 6 or the second stage heater 7, the zero pressure at the inlet of the first stage heater 6 or the inlet pressure at the second stage heater 7 will fluctuate. A larger amount of heated steam flows to the first stage heater 6 or the second stage heater 7. As a result, the deviation signal becomes large, and the moisture separation heater abnormality detection device 46 outputs the first stage and first stage heater heat exchanger tube abnormality signal j-n.

[Effects of the Invention] As explained above, the present invention obtains a deviation signal based on the sum of the heated steam flow rate signal flowing into the heater (-), the drain flow rate signal and the vent flow rate signal flowing out from this, and As long as the deviation signal is within a predetermined value range, no signal is output; on the other hand, when the deviation signal exceeds that range, a heated steam flow rate abnormality signal is output, so that it is possible to prevent abnormalities from occurring in the heat exchanger tubes. can be accurately detected outside the moisture separation heater, and can prevent adverse effects on equipment such as the moisture separation heater and the low-pressure turbine.

Therefore, the present invention has an excellent effect of increasing the safety of equipment in a steam turbine plant.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing one embodiment of the moisture separation heater abnormality detection device according to the present invention, FIG. 2 is a circuit connection diagram of the abnormality detection device, and FIG. 3 is a circuit diagram showing another embodiment of the present invention. The connection diagram, FIG. 4, is a system diagram of a conventional steam turbine plant. 6...First stage heater 7...Second stage heater 31.32.3B...Flow rate detector 34...Moisture separation heating Equipment abnormality detection device 35.
36.37...Flow rate detector 38.39.42.43...Arithmetic unit 40.44...Flow rate abnormality detection circuit 41.45...Timer agent Patent attorney Nori Chika Ken Yudo Daishimaru Ken

Claims (1)

[Claims] a detected heating steam flow rate signal flowing into the first heater;
a calculation device that performs calculations based on the sum of a drain flow rate signal flowing out from the one heater and a vent flow rate signal, or a detected heating steam flow rate signal flowing into another heater, and outputs a deviation signal; and a flow rate abnormality detection device that outputs a heating steam flow rate abnormality signal when the deviation signal given from the arithmetic unit exceeds a predetermined value.