JPH0682004A - Pipe leakage diagnostic method for feed water heater - Google Patents

Abstract

PURPOSE:To provide a pipe leakage diagnostic device for a feed water heater capable of diagnosing a feed water heater whose heat exchanger tube suffers from leakage of feed water flowing in the feed pipe out of a plurality of feed water heaters laid out in series in a steam turbine plant. CONSTITUTION:The flow rate of feed water flowing in feed water systems for feed water heater 1A and 1B is detected with inlet flow rate detectors 16 and 17 and an outlet flow rate detector 18 where a differential flow rate between the inlet and outlet flow rates is computed based on the detected flow rates and the computed differential-flow rate is compared with a determined value of the differential flow rate which indicates pipe leakage. When it exceeds the determined value, detection flow rates detected with drain flow rate detectors 20 and 21 are compared with a determined value of a drain flow rate which indicates pipe leakage, thereby diagnosing the pipe leakage of a feed water heater.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe leakage diagnosing device for a feed water heater for diagnosing a pipe leak in a feed water heater for heating feed water supplied to a boiler in steam turbine equipment by extraction steam from a steam turbine. .

[0002]

2. Description of the Related Art A steam generator equipped with a boiler and a steam turbine is used to condense steam from a steam turbine into condensate. In a steam turbine facility to be driven, a feed water heater that heats feed water supplied to a boiler in order to improve thermal efficiency by extraction steam extracted from a steam turbine is provided.

The feed water heater is a heat exchanger consisting of a heat transfer tube and a container in which the feed water flows, the feed water flows through the heat transfer tube, and the extraction water is used to heat the feed water flowing through the heat transfer tube inside the container. Steam flows in. Here, the extracted steam that has heated the feed water flowing in the heat transfer tube is condensed and sent as a drain, and is recovered as feed water again. At this time, the level of the drain liquid level in the feed water heater is controlled by the drain control valve.

By the way, when an abnormality such as a crack occurs in the heat transfer pipe of the feed water heater during the operation of the steam turbine facility, the high pressure feed water leaks to the steam side in the container (hereinafter referred to as pipe leakage). The phenomenon occurs. If such a pipe leak occurs, there is no clear method to detect it in the past, and the drain liquid level of the feed water heater is increased due to the increase in the drain flow rate caused by the leak of the feed water from the heat transfer pipe to the steam side in the container. It is estimated from the fact that the drain control valve to be controlled is always fully open.

[0005]

In order to estimate the above-mentioned pipe leakage of the feed water heater by the opening abnormality of the drain control valve, it is necessary for the operators who perform operation and maintenance to have the skill and detailed knowledge of the plant. Therefore, there is a problem that skill and experience for advanced driving are required. Further, the above-mentioned method has a drawback in that it is impossible to judge the pipe leakage in the central control room because confirmation of the opening degree of the drain control valve and the like are carried out by monitoring the field instruments.

To solve this drawback, in order to make it possible to determine pipe leakage in the central control room, the feed water heaters at various locations must be connected to the drain control valve opening transmitters and drains sent from the feed water heaters. It is necessary to install a drain flow meter for measuring the flow rate, which is disadvantageous in terms of cost, and there is a problem that it is difficult to judge pipe leakage unless the operator constantly monitors these meters.

[0007] Recently, there is also known a device in which acoustic sensors are installed at various places of all feed water heaters and a pipe leak is judged from a sound generated at the time of leak, but this method is significantly expensive and costly. There is a problem from the point of. An object of the present invention is to provide a pipe leak diagnosis device for a feed water heater, which is inexpensive in the central control room and can automatically diagnose the presence or absence of a pipe leak in the feed water heater.

[0008]

In order to solve the above-mentioned problems, according to the present invention, a heat transfer pipe through which feed water flows, and this heat transfer pipe are provided internally, and extraction steam from a steam turbine flows into the pipe. The feed water heater consisting of a container for storing drainage generated by heating the feed water is formed in one row or a plurality of rows, and two or more n extraction steams with different vapor pressures are respectively introduced into each row in series. Arranged feed water heaters The drains in the feed water heaters of each row in the water supply system are joined from the feed water heaters of higher steam pressure to the feed water heaters of lower steam pressure that follow, and in this way, the drains are sequentially drained. To a feed water heater with a lower steam pressure to send out the drain of the feed water heater with the lowest steam pressure.A pipe leak diagnosis device for the feed water heater that diagnoses the presence or absence of pipe leakage in the heat transfer pipe of the feed water heater. In the water supply heater The feed water inlet flow rate detector and the feed water outlet flow rate detector that detect the feed water inlet flow rate and the discharge feed water outlet flow rate, respectively, and the feed water heaters from the feed water heaters in each row of the feed water system A drain flow rate detector provided at the number of (n-1) or less for detecting the flow rate of the drain flowing to the feed water heater of steam pressure;
A storage unit that stores the judgment value that the difference between the outlet flow rate and the outlet flow rate indicates the pipe leakage and the judgment value of each drain flow rate that indicates the pipe leakage in each feed water heater, and the flow rate detected by the feed water inlet and outlet flow rate detectors. From the water supply heater provided with the water supply determination means for determining the presence or absence of pipe leakage by comparing the difference flow rate with the determination value of the difference flow rate read from the storage unit, and the drain water flow heater. The drain flow rate detector is equipped with a drain judging means for judging the presence or absence of pipe leakage by comparing the detected flow rate of the drain flow rate with the judgment value of the drain flow rate read from the storage unit. One provided with a computing unit for determining the presence or absence of pipe leakage of the supply water heater of the lower steam pressure from the provided supply water heater of the highest steam pressure by means of the drain determination means, and identifying the supply water heater having the pipe leakage. To

[0009]

Operation: A feed water heater feed water in which one or a plurality of feed water heaters to which bleed steam of two or more different steam pressures from a steam turbine is supplied are arranged in series are arranged. The inlet flow rate and the outlet flow rate of the feed water flowing through the system are detected by the inlet flow rate detector and the outlet flow rate detector, respectively, and the difference flow rate is calculated by the calculation unit. Then, the determination value indicating the pipe leakage of the heat transfer pipe of the feed water heater, which is stored in the storage unit in advance, is read, and the difference flow rate of the supplied water calculated by the water supply determination means is compared with the determination value to determine the pipe. Determine leakage. Then, if there is a possibility of pipe leakage, the drain flow rate from the feed water heater provided with (n-1) or less drain flow rate detectors is detected by the drain flow rate detector in the order of the feed water heater with the highest steam pressure. To do. Here, first, the drain flow rate from the feed water heater having the highest steam pressure provided with the drain flow rate detector is detected. Then, the drain flow rate determination value indicating the pipe leakage of the feed water heater stored in the storage unit is read, and the drain flow rate detected by the drain flow rate detector by the drain determination means is compared with the determination value to detect the pipe leakage. The presence or absence of is determined.

If there is no pipe leakage in this determination, the drain flow rate is the drain flow rate from the feed water heater having a lower vapor pressure subsequent to the steam pressure among the feed water heaters whose drain flow rate is detected by the drain flow rate detector. The detector detects the drain flow rate and compares the detected drain flow rate with the determination value of the drain flow rate read from the storage unit as described above to determine the presence or absence of pipe leakage.

In this way, pipe leakage is determined in order from the high steam pressure feed water heater whose drain flow rate is detected to the lower steam pressure feed water heaters, and the pipe leaking water heater is determined. . At this time, if the number of drain flow detectors attached is (n-1) and the feed water heater has one row of feed water system, the feed water heater having a pipe leak can be specified. If the drain flow rate detector is less than (n-1), depending on the position of the drain flow rate detector or the feed water heater with pipe leakage, or even if the drain flow rate detector is (n-1), the feed water heater When the system has a plurality of rows, the feed water heater including the pipe leak water heater may be specified depending on the position of the feed water heater having the pipe leak.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a water supply system diagram for supplying water to the water supply heater when diagnosing pipe leakage of the water supply heater according to an embodiment of the present invention. In FIG. 1, a water supply system 1 is a system for supplying water to a boiler from a deaerator (not shown), and two pump water supply systems 1a, 1 having two boiler water supply pumps 2 are provided.
b and the feedwater sent from the boiler feedwater pump 2 are divided into two systems and flow, and the feedwater heater is provided with a high-pressure first feedwater heater 3A, a high-pressure second feedwater heater 4A, and a high-pressure third feedwater heater 5A. 1A and high pressure first feed water heater 3B, high pressure second
It is composed of a feedwater heater 4B and a feedwater heater water supply system 1B including a high-pressure third feedwater heater 5B, and a boiler water supply system 1C which joins the feedwater heater water supply systems 1A and 1B to supply water to the boiler.

Extraction steam supply systems 6 and 7 for branching and supplying extraction steam from the steam turbine to the high-pressure first feed water heaters 3A and 3B, respectively, and extraction steam to the high-pressure second feed water heaters 4A and 4B, respectively. The supply systems 8 and 9 are connected to the extraction steam supply systems 10 and 11 to the high-pressure third feed water heaters 5A and 5B. Here, the steam pressure of the extraction steam supplied to the feed water heater is highest in the high pressure first feed water heaters 3A and 3B, and is high in the high pressure second feed water heaters 4A and 4B and the high pressure third feed water heater 5.
It becomes smaller in the order of A and 5B.

High pressure first feed water heater 3A, 3B and high pressure second
The drain systems 13A and 13B are connected to the feed water heaters 4A and 4B to flow the drain, respectively, and are connected to the high pressure second feed water heaters 4A and 4B and the high pressure third feed water heaters 5A and 5B, respectively. Drain systems 14A and 14B are also provided, and drain systems 15A and 15B are provided by connecting the high pressure third feed water heaters 5A and 5B and a deaerator (not shown), respectively.

The feed water inlet flow rate detectors 16 and 17 are provided in the pump water supply systems 1a and 1b, respectively, and the outlet water flow rate detector 18 is provided.
Is installed in the boiler water supply system 1c. Drain flow rate detector 2
0 and 21 are provided in the drain systems 14A and 14B, respectively. With such a configuration, the water supplied by the two water supply pumps 2 is divided into the water supply heaters 1A and 1B via the pump water supply systems 1a and 1b, and the high pressure third water supply heaters 5A and 5B and the high pressure water supply heaters 1A and 1B, respectively. 2 Boiler feed water system 1c through feed water heaters 4A, 4B and high pressure first feed water heaters 3A, 3B
Supplied to the boiler. At this time, the feed water is heated and heated by the high-pressure third feed water heaters 5A and 5B by the extracted steam passing through the extracted steam supply systems 10 and 11, and the extracted steam is condensed and becomes drain. Further, the feed water delivered from the high-pressure third feed water heaters 5A and 5B is heated and heated by the extraction steam passing through the extraction steam supply systems 8 and 9 in the high-pressure second supply water heaters 4A and 4B, and the extraction steam is condensed. Becomes drain, and further high pressure second
The feed water delivered from the feed water heaters 4A and 4B is heated and heated by the extracted steam passing through the extracted steam supply systems 6 and 7 in the high-pressure first feed water heaters 3A and 3B, and the extracted steam is condensed and becomes drain. . The feed water thus heated and heated is supplied to the boiler via the boiler feed water system 1c.

By the way, during the operation of the turbine equipment by supplying water to the boiler by the boiler water supply pump 2, the heat transfer tube of the water heater may be damaged and the water may leak to the steam side, that is, the tube may leak. In this case, it is necessary to identify the feed water heater with pipe leakage during operation. By the way, when a pipe leak occurs, a difference in flow rate occurs between the inlet and outlet flow rates of the feed water heater water supply systems 1A and 1B, and in the feed water heater, the feed water leaks from the heat transfer pipe to the steam side and the drain amount. Therefore, the presence or absence of pipe leakage is diagnosed by a computer by detecting the difference flow rate and the drain flow rate.

FIG. 2 is a block diagram showing the configuration of the above computer. In FIG. 2, the computer 30 is composed of an arithmetic unit 31, a storage unit 32, an input interface 33, an output interface 34, and a data bus shown by a solid line in the figure for transmitting data between them. With such a configuration, the input interface 33 is connected to the feed water inlet flow rate detector 1 provided in the pump water supply systems 1a and 1b.
6, 17 and a signal of the feed water supply flow rate sent by the boiler feed water pump 2 detected by the feed water outlet flow rate detector 18 provided in the boiler water supply system 1c, and the drain system 14A, 1
Drain flow rate detectors 20 and 21 provided in 4B, respectively
The signal of the drain flow rate detected in step 1 and the signal of the stable load are input as will be described later for diagnosis.

The storage unit 32 has a high-voltage first unit arranged in series.
Feed water heaters 3A, 3B, high pressure second feed water heaters 4A, 4
B, a judgment value indicating the difference in flow rate between the inlet flow rate and the outlet flow rate of the feed water at the inlet and the outlet of the feed water heater 1A, 1B provided with the high-pressure third feed water heaters 5A, 5B, respectively. Memorize Here, the difference between the inlet and outlet feed water flow rate is 0 if there is no abnormality such as leakage anywhere.
If there is a difference in flow rate, it means that some abnormality has occurred in the water supply system 1, and the most probable cause is a pipe leakage of the water supply heater. However, this difference flow rate is not a minute flow rate within the measurement error range of the flow rate detector, and is not a minute flow rate that may cause continuous operation of the steam turbine equipment.

Here, the judgment value of the differential flow rate treated as the leakage of the pipe of the feed water heater is a predetermined value calculated by a simulation calculation when the heat transfer pipe has a hole of about several mm. The storage unit 32 also stores a drain flow rate determination value indicating that the feed water leaks to the steam side of the feed water heater and the drain flow rate increases to cause pipe leakage. This determination value is a predetermined flow rate with respect to the feed water flow rate corresponding to the load in the high-pressure second feed water heaters 4A and 4B.

Next, the procedure for determining the presence / absence of leakage of the pipe of the feed water heater, which is carried out by the arithmetic unit 31, will be explained based on the flow chart shown in FIG. 3 and the system diagram of FIG.
As a premise for performing the diagnosis in FIG. 3, the pipe leakage of the feed water heater is diagnosed only when a stable load continues for a certain time as shown in step 41. This is because a difference in flow rate occurs between the inlet and outlet flow rates of the feed water heater feed water systems 1A and 1B shown in FIG.

Therefore, the diagnosis of the pipe leakage is started in a stable load operating condition as shown in step 42. In step 43, the detected flow rates of the feed water inlet flow rate detectors 16 and 17 from the input interface 33 are added, and the added flow rate and the detected flow rate of the feed water outlet flow rate detector 18 from the input interface 33 are subtracted. The difference flow rate Fb between the inlet and outlet flow rates of the feed water heater water supply systems 1A and 1B is calculated.

Next, in step 44, the determination value Fa of the difference in the feed water flow rate indicating the pipe leakage is read from the storage unit 32, and in step 43 the difference in the feed water flow rate Fb is calculated.
Compared to. In this case, unless Fb> Fa, there is no pipe leakage as shown in step 45. However, if Fb> Fa, there is a possibility of pipe leakage, so the process proceeds to the next step.
At step 46, the detected flow rate Fc at the drain flow rate detector 20 of the feed water heater feed water system 1A from the interface 33
And the determination value Fd of the drain flow rate read from the storage unit 32 are compared. In this case, if Fc> Fd, step 47
As shown in, there is pipe leakage in the high-pressure first feed water heater 3A or the high-pressure second feed water heater 4A of the feed water heater water supply system 1A. If Fc> Fd is not satisfied, the high pressure first feed water heater 3
A, since there is no pipe leakage in the high pressure second feed water heater 4A, the process proceeds to the next step.

In step 48, the flow rate Fe detected by the drain flow rate detector 21 of the feed water heater water supply system 1B from the interface 33 is compared with the drain flow rate determination value Ff indicating the pipe leakage read from the storage unit 32. . In this case Fe
If> Ff, as shown in step 49, there is a pipe leak in the high-pressure first feed water heater 3B or the high-pressure second feed water heater 4B of the feed water heater water supply system 1B. However, if Fe> Ff, there is no pipe leakage in the high pressure first feed water heater 3B or the high pressure second feed water heater 4B. Therefore, as shown in step 50, the high-pressure third feed water heater 5A of the feed water heater water supply system 1A, 1B,
Or, there is a pipe leak in the high-pressure third feed water heater 5B.

The above steps 43, 44, 46,
The calculation results of 48 and the like are input to the output interface 34, and from here, the display of the determination of the pipe leakage of each feed water heater is displayed. Since the feed water inlet flow rate detectors 16 and 17, the outlet flow rate detector 18 and the drain flow rate detectors 20 and 21 which are the basis of the above calculation are usually provided in steam turbine equipment, they are special measuring instruments. It is possible to determine whether or not there is a pipe leak in the feed water heater without installing.

Here, the feed water heater in which the leakage of the pipe has been diagnosed is generally bypassed with the feed water heater to continue the operation of the steam turbine facility, but maintenance and inspection are performed at the opportunity. Although the feed water heater water supply system has two rows in this embodiment, it may have one row. In this case, the feed water inlet flow rate detector and the feed water inlet flow rate detector and By providing the outlet flow rate detector of the feed water and the drain flow rate detector which is one less than the number n of the feed water heaters arranged in series (n-1) or less, the number (n-
In the case of 1), it is possible to identify the feedwater heater with a pipe leak, and if it is less than the number (n-1), the feedwater heater with a pipe leak is included depending on the position of the drain flow rate detector and the feedwater heater with a pipe leak. It also occurs when specifying the feed water heater.

Further, although the high-pressure feed water heater for heating the feed water supplied from the deaerator to the boiler has been described in the present embodiment, the low-pressure feed water for heating the condensate water supplied from the condenser to the deaerator is described. The same effect can be obtained in the heater according to the present invention.

[0027]

As is apparent from the above description, according to the present invention, the feed water detected by the inlet and outlet flow rate detectors provided in the feed water heater water feed system of one row or a plurality of rows according to the above-mentioned configuration. Since pipe leakage is diagnosed from the difference between the inlet and outlet flow rates and the drain flow rate from the feed water heater detected by the drain flow rate detector, it is not necessary for a trained operator to estimate it using a field instrument, as in the past. In the control room, it is possible to easily diagnose the feed water heater with pipe leakage.

[Brief description of drawings]

FIG. 1 is a system diagram of a water supply system including a water supply heater for diagnosing pipe leakage according to an embodiment of the present invention.

FIG. 2 is a block diagram showing the configuration of a computer for diagnosing pipe leakage of the feed water heater shown in FIG.

FIG. 3 is a flowchart showing a procedure for diagnosing pipe leakage of a feed water heater by the computer shown in FIG.

[Explanation of symbols]

 1 Water Supply System 1A Water Supply Heater Water Supply System 1B Water Supply Heater Water Supply System 3A High Pressure First Water Supply Heater 3B High Pressure First Water Supply Heater 4A High Pressure Second Water Supply Heater 4B High Pressure Second Water Supply Heater 5A High Pressure Third Water Heater 5B High-pressure third feed water heater 16 Inlet flow rate detector 17 Inlet flow rate detector 18 Outlet flow rate detector 20 Drain flow rate detector 21 Drain flow rate detector 31 Computing section 32 Storage section

Claims (1)

[Claims] 1. A feed water heater comprising: a heat transfer pipe through which feed water flows; and a container for internally storing the heat transfer pipe and for storing drainage generated by heating of the feed water when the extracted steam from a steam turbine flows in. 1 or multiple rows with 2 or more n in each row
Feed water heaters arranged in series in the number of inflows of extracted steam having different steam pressures. The heat transfer pipe of the feed water heater that joins the feed water heater with the steam pressure of 10 and thus sequentially joins the drain to the feed water heater with the lower steam pressure and sends out the drain of the feed water heater with the lowest steam pressure. In the pipe leakage diagnosis device for a feed water heater for diagnosing the presence or absence of pipe leakage, a feed water inlet flow rate detector for detecting an inlet flow rate of feed water flowing into the feed water heater water supply system and an outlet flow rate of the feed water discharged, and Outlet flow rate detector for feed water and feed water heater Detects the flow rate of the drain flowing from the feed water heaters in each row of the feed water system to the feed water heaters of lower steam pressure that follow (n-1). Drain flow rate provided An outlet, a storage unit that stores the inlet and outlet of the water supply, a storage unit that stores a determination value indicating a pipe leak and a determination value of each drain flow rate that indicates a pipe leakage in each water heater, an inlet of the water supply, A water supply determination means and a drain flow rate detector are provided that calculate the difference in flow rate detected by the outlet flow rate detector and compare the difference flow rate with the determination value of the difference flow rate read from the storage unit to determine the presence or absence of pipe leakage. The drain flow rate from each feed water heater was compared with the drain flow rate determination value read from the storage unit to determine the presence or absence of pipe leakage. At this time, from the feedwater heater with the highest steam pressure equipped with the drain flow rate detector, the drain determiner determines the presence or absence of pipe leakage from the feedwater heater with lower vapor pressure in order, and identifies the leaked feedwater heater. Calculation Feedwater heater tube leak diagnostic apparatus characterized by comprising and.