JP3819161B2 - Feed water heater drain discharge device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a feed water heater drain discharge device for discharging drain from a feed water heater.
[0002]
[Prior art]
In general, in a thermal power plant or a nuclear power plant, feed water supplied from a boiler or a nuclear reactor is heated by a plurality of feed water heaters in order to increase the thermal efficiency of the plant. This feed water heater heats feed water by extracting air from a turbine.
[0003]
The structure of the feed water heating system provided in the power plant is shown in FIG. In FIG. 7, the water supplied from the condenser 1 sequentially flows into the plurality of water heaters 3, 4, 5 through the water supply pipe 2. The plurality of feed water heaters 3, 4, and 5 have successively higher internal pressures, and the feed water heater 5 has the highest internal pressure. The feed water heated by each feed water heater 3, 4, 5 is sent to a boiler or nuclear reactor (not shown).
[0004]
On the other hand, the extracted steam extracted from the turbine is supplied to each of the feed water heaters 3, 4, and 5 through the extraction pipes 6 a, 6 b, and 6 c, where they are condensed and drained after heat exchange with the feed water. . Each of the feed water heaters 3, 4, 5 is connected to a low-pressure side next-stage feed water heater by a drain pipe 8 having a control valve 7. The drain condensed by exchanging heat with the feed water is used as a heat source medium. 8 is sent to the low-pressure side next-stage feed water heater and used as part of the feed water heating source. Further, the non-condensable gas remaining when the steam in the main body of the feed water heater becomes drainage is discharged from each of the feed water heaters 3, 4 and 5 to the condenser 1 through the vent pipe 9 through the orifice 10. .
[0005]
The feed water heaters 3, 4, and 5 generally employ a multi-tube heat exchanger because the feed water has a high pressure, and heat the feed water flowing through the feed water heater from outside the pipe by the extracted steam and its drain. . Accordingly, since the drain stays in the feed water heater cylinder, a water level controller is provided for appropriately controlling the drain water level and performing heat exchange efficiently.
[0006]
In other words, the drain pipe 8 is provided with a control valve 7, and in each of the feed water heaters 3, 4, and 5, when the drain water level becomes abnormally high, the drain is directly discharged to the condenser 1. A drain pipe 11 is provided, and an emergency control valve 12 is provided in the emergency drain pipe 11.
[0007]
Each feed water heater 3, 4, 5 is provided with a reference water level detector 13 and a high water level detector 14, and a detection signal from the reference water level detector 13 is input to a controller 15 where the standard water level is detected. The opening of the control valve 7 is controlled by the deviation signal, and the detection signal from the high water level detector 14 is input to the controller 16 where it is compared with the high water level setting signal and the deviation thereof. The opening degree of the emergency control valve 12 is controlled by the signal.
[0008]
[Problems to be solved by the invention]
In general, the fluid at the valve inlet flows into the control valve 7 as a single-phase subcooled saturated drain. However, if a non-condensable gas is present in the drain pipe 8 or in the feed water heaters 3, 4, and 5, the fluid is saturated. The pressure of the drain is reduced by the partial pressure of the noncondensable gas. As a result, the subcooled saturated drain flashes below the drain saturation pressure, and a gas-liquid two-phase flow of non-condensable gas mixture of drain and steam is formed.
[0009]
When this gas-liquid two-phase flow flows into the control valve 7, the required valve opening increases as the gas passes through the control valve 7. For this reason, when the gas flow rate increases, even if the control valve 7 is fully opened, the drain cannot be completely discharged, and the water levels of the feed water heaters 3, 4, and 5 rise. Further, when the water level of the feed water heaters 3, 4, and 5 rises, the emergency control valve 12 is opened by the signal from the high water level detector 14, and the drain that is the heat source medium is discharged to the condenser 1.
[0010]
For example, taking a drain flow from the feed water heater 4 to the feed water heater 3 as an example, the gas-liquid two-phase flow of the non-condensable gas mixture of drain and steam is an unstable flow, and the control valve 7 The passing drain amount fluctuates, interlocking with the drain water level fluctuation of the feed water heater 3, causing an opening change of the control valve 7, and the controllability of the control valve 7 is deteriorated.
[0011]
On the other hand, even if the opening degree of the control valve 7 changes, if gas is present inside the drain pipe 8, the change in the flow rate of the passing drain through the control valve 7 is replaced as the volume change of the gas inside the drain pipe 8. A delay occurs in the water level change of the heater 3. As a result, there is a problem that the drain level change of the feed water heater 3 cannot follow the change in the opening degree of the control valve 7 and the controllability of the control valve 7 is impaired.
[0012]
Drawing 8 is an explanatory view of the flow of the drain in the conventional feed water heater drain discharge device. The drain flow in the drain pipe 8 shows an extremely diverse state depending on the type of drain and gas in the pipe, the pipe line condition and the flow rate, and generates an unstable flow. This unstable flow causes the controllability of the control valve 7 to deteriorate.
[0013]
In an experiment in which the amount of air, which is representative of water and a non-condensable gas, was changed by simulating the feed water heater drain discharge device shown in FIG. 8, the relationship of FIGS. 9 and 10 was obtained. In FIG. 9, Q1 shows the flow rate of water, Q2 shows the flow rate of air, and P shows the pressure fluctuation in the piping. FIG. 9 shows that the pressure fluctuation increases as the water flow rate Q1 increases and the ratio of the air flow rate Q2 increases. In FIG. 10, similarly to FIG. 9, Q1 indicates the flow rate of water, Q2 indicates the flow rate of air, and H indicates the fluctuation level of the water level of the tank simulating the feed water heater. FIG. 10 shows that the fluctuation of the water level increases as the water flow rate Q1 increases and the ratio of the air flow rate Q2 increases.
[0014]
Further, FIG. 11 shows the results selected in a test in which water and saturated drain were flowed in the same amount and the air amount Q2 was changed. Q1 represents the flow rate of water, and Q3 represents the flow rate of saturated drain. In the case of saturated drain, as the air flow rate Q2 increases, the partial pressure of the gas phase due to air decreases and the amount of drain flushing increases, so it has been confirmed from experiments that the fluctuation range in the pipe is much larger than that of water It was done.
[0015]
FIG. 12 is a diagram illustrating an example of a flow in the pipe before the control valve 7 in FIG. 8. When the plant is lightly loaded and the drain flow rate is small, the control valve 7 is also throttled, so that the drain flow rate becomes slow. If it does so, the non-condensable gas which flowed together with the drain inside the horizontal pipe will rise by buoyancy, resulting in a flow in which the liquid phase and the gas phase are separated. As shown in FIG. 12, in the downward vertical pipe, the non-condensable gas does not resist buoyancy when entrained by the shearing force of the drain, but accumulates at an elbow (bent portion). Then, the flow path in the elbow portion is narrowed, the pressure loss is increased, and the partial pressure of the non-condensable gas occupying the drain flow is increased.
[0016]
Moreover, if there is gas in the pipe in the vertical portion of the drain pipe 8, the drain falls in a waterfall shape. For this reason, in the downstream piping, the indentation pressure due to the drain hydrostatic head in the vertical part of the pipe cannot be expected, so the experiment has shown that the pressure loss becomes excessive by flushing below the drain saturation pressure due to pipe pressure loss and flow disturbance. Observed.
[0017]
In order to prevent the gas from flowing into the drain pipe 8, the noncondensable gas is discharged from the vent pipe 9 through the orifice 10 to the condenser 1. That is, the non-condensable gas remaining when the extracted steam is drained inside the feed water heaters 3, 4, and 5 passes through the orifice 10 through the vent pipe 9 provided in the main body of the feed water heaters 3, 4, and 5. It is discharged to the condenser 1.
[0018]
The original purpose of discharging the non-condensable gas by the vent pipe 9 is to eliminate the non-condensable gas in the feed water heaters 3, 4, 5 because it hinders heat exchange. Therefore, the controllability of the control valve 7 cannot be ensured sufficiently. That is, when discharging the non-condensable gas from the main body of the feed water heaters 3, 4, and 5 through the vent pipe 9 to the condenser 1, the extracted steam at the time of low-grade operation is taken into account in consideration of the heat exchange rate of the plant. The non-condensable gas in an amount of about 1% of the amount can be discharged. The specifications of the orifice 10 installed in the vent pipe 9 are also selected and used so as to satisfy the conditions. For this reason, a large amount of non-condensable gas cannot be discharged using the vent pipe 9.
[0019]
The total amount of non-condensable gas and non-condensable gas remaining when the extracted steam is drained from the upper stage feed water heater through the drain pipe 8 depends on the condenser 1 through the vent pipe 9 depending on the operation state of the plant. Is expected to exceed the amount that can be discharged. Since the feed water heaters 3, 4, and 5 are much larger than the vent pipe 9, it is structurally impossible to discharge all the non-condensable gas in the feed water heater to the condenser 1 through the vent pipe 9. The remaining noncondensable gas is mixed with the drain and flows into the drain pipe 8.
[0020]
Further, in order to prevent the drain discharged from the feed water heaters 3, 4, and 5 from flashing to form a vapor phase, a drain cooling device is provided inside the feed water heaters 3, 4, and 5, It has also been proposed to cool the drain below the saturation temperature by exchange. However, in order to provide this drain cooling device and lower the drain temperature, it is necessary to increase the cooling area accordingly, and the fluid resistance increases accordingly, leading to a decrease in drain pressure. Considering these facts, the drain temperature is actually set to a relaxation temperature of about −5 ° C. to −10 ° C. Therefore, in the drain pipe 8, it is predicted that the pipe pressure is partially lower than the saturation pressure of the drain due to the pressure fluctuation due to the pipe pressure loss and the disturbance of the drain flow.
[0021]
Further, when the pressure before the valve decreases due to a sudden change in the opening degree of the control valve 7 and the drain partially falls below the saturation pressure, the drain is flushed and steam is generated, the volume increases rapidly, An unstable flow of gas-liquid two-phase flow is formed. On the other hand, when the saturated drain is cooled by the cooling device, it is predicted that the gas dissolved in the drain is separated and flows into the drain pipe 8 together with the drain.
[0022]
In addition, the phenomenon described above does not occur at 100% rated revolving, especially in power plants, and is expected to occur when the differential pressure between each feedwater heater is small during partial load operation such as trial operation, and is a temporary phenomenon There are many features.
[0023]
The objective of this invention is providing the feed water heater drain discharge device which can stabilize the flow of the drain in the drain pipe of a feed water heater.
[0028]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a drainage apparatus for draining drainage from a first feedwater heater that stores drainage containing noncondensable gas to a second feedwater heater on a low-pressure side. And a drainage device for draining water heater comprising a control valve that adjusts the flow rate of drain that is provided in the drain pipe and flows out of the first feedwater heater, and recovers the drain from the first feedwater heater. An emergency drain pipe for discharging directly to the water device, an emergency control valve for adjusting the flow rate of drain that is provided in the emergency drain pipe and flows out of the first feed water heater, and start-up operation or low-load operation And a water level controller for raising the water level inside the first feed water heater.
[0029]
In the feed water heating air drain discharge apparatus according to the first aspect of the invention, the water level controller operates to raise the water level inside the first feed water heater during the start-up operation or the low load operation.
[0030]
According to a second aspect of the present invention, there is provided a feed water heating air drain discharge device according to the first aspect of the invention, wherein the water level controller operates the control valve in a closing direction when a drain flush occurs. And
[0031]
In the feed water heating air drain discharge device according to the invention of claim 2 , in addition to the action of the invention of claim 1 , the water level controller operates the control valve in the closing direction when the drain flush occurs to discharge the drain. Reduce the water level inside the feed water heater.
[0032]
According to a third aspect of the present invention, there is provided the feed water heating air drain discharge device according to the first aspect , wherein the water level controller operates the emergency control valve in the opening direction when a drain flush occurs. It is characterized by.
[0033]
In the feed water heating air drain discharger according to the invention of claim 3 , in addition to the action of the invention of claim 1 , the water level controller operates the emergency control valve in the opening direction when a drain flush occurs, and is not condensed. Discharge the sex gas to the condenser.
[0040]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below. FIG. 1 is an explanatory view of a feed water heater drain discharge device according to an embodiment of the present invention.
[0041]
Now, the feed water heater 4 is a first feed water heater, and the subsequent feed water heater 3 is a second feed water heater. The first feed water heater 4 stores drain containing non-condensable gas, and drains from the first feed water heater 4 to the second feed water heater 3 on the low pressure side via drain pipes 8a and 8b. Leaks. The control valve 7 is provided in the drain pipe 8 near the drain outlet of the first feed water heater 4, and the drain pipe 8a is short and the drain pipe 8b is long.
[0042]
That is, the drain passes through the short drain pipe 8a and is fed to the second feed water heater 3 on the low pressure side of the next stage through the control valve 7 for adjusting the drain flow rate. In this 1st Embodiment, since it has comprised so that the control valve 7 may be installed in the exit vicinity of the 1st feed water heater 4, the downstream of the control valve 7 is lower than the 1st feed water heater 4 Due to the pressure of the second feed water heater 3, the depressurized flash state is forced. As a result, the volume expands, resulting in a high-speed saturated two-phase flow. Since this flow does not become a two-phase flow in a laminar flow state in which the gas phase and the liquid phase are separated from each other by buoyancy, non-condensable gas is also accompanied and discharged to the second feed water heater 3.
[0043]
In the above description, the control valve 7 is provided in the vicinity of the feed water heater 4, but the control valve 7 may be provided integrally with the feed water heater 4.
[0044]
As described above, in the first embodiment, the control valve 7 is provided in the vicinity of the feed water heater or integrated with the feed water heater, and the depressurization flash is intentionally performed by the low pressure of the feed water heater downstream of the control valve 7. A two-phase flow is generated by, and a high-speed flow is generated by volume expansion by a vacuum flash. Then, the non-condensable gas inside the drain pipe 8 is discharged together with the second feed water heater 3. Therefore, even if non-condensable gas flows into the drain pipe 8, it does not stay. That is, the non-condensable gas that has flowed into the drain pipe 8 from the feed water heater 4 is immediately introduced into the control valve 7 and discharged as a high-speed saturated two-phase flow downstream of the control valve 7. The stable flow in the drain pipe 8 and the stable control of the control valve 7 are achieved.
[0045]
Next, a second embodiment of the present invention will be described. FIG. 2 is an explanatory view of a feed water heater drain discharge device according to the second embodiment of the present invention. This second embodiment is different from the first embodiment shown in FIG. 1 in that an emergency drain pipe 11 for directly discharging drain from the first feed water heater 4 to the condenser 1 A connection pipe 11a for branching from a drain pipe 8a in the vicinity of the drain outlet of the first feed water heater 4 and connecting the drain outlet to the emergency drain pipe 11 in a horizontal or upward gradient, and provided in the emergency drain pipe 11. An emergency control valve 12 for adjusting the flow rate of the drain flowing out from the first feed water heater 4 is additionally provided, and an emergency control valve 16 based on the detection signals from the high water level detector 14 and the differential pressure gauge 25 The valve opening of the control valve 12 is adjusted.
[0046]
In FIG. 2, the drain discharged from the first feed water heater 4 is fed to the second feed water heater 3 in the next stage on the low pressure side through the drain pipes 8 a and 8 b. The drain pipe 8b is provided with an adjustment valve 7 that controls the water level of the first feed water heater 4 by adjusting the drain flow rate. Here, the drain pipe 8a is a short horizontal pipe, and the connection pipe 11a for connecting to the emergency drain pipe 11 is branched. The branch direction of the connecting pipe 11a is at the same level as the outlet of the first feed water heater 4 or upward (upward gradient).
[0047]
In the second embodiment, the branched connection pipe 11 a stands vertically and is connected to the emergency drain pipe 11 via the emergency control valve 12. Although not shown in FIG. 2, the emergency drain pipe 11 downstream of the emergency control valve 12 is connected to a condenser.
[0048]
In the case where the drain exiting the first feed water heater 4 is a gas-liquid two-phase mixed flow containing non-condensable gas, the horizontal portion of the drain pipe 8a at the outlet of the first feed water heater 4 is described above. In this way, most of the non-condensable gas rises due to buoyancy due to buoyancy, resulting in a two-phase flow in a laminar flow state in which the gas phase and the liquid phase are split up and down. Non-condensable gas enters and is stored in the connecting pipe (vertical pipe) 11a of the emergency drain pipe 11. The accumulated non-condensable gas is recovered from the emergency control valve 12 through the emergency drain pipe 11 into a low-pressure container such as a condenser.
[0049]
In addition, a differential pressure gauge 25 is installed in the connection pipe 11a of the emergency drain pipe 11, and detects a differential pressure that changes depending on the amount of noncondensable gas accumulated in the connection pipe (vertical pipe) 11a. Further, the high water level detector 14 detects that the water level in the water heater 4 has become a high water level. The controller 16 receives the differential pressure from the differential pressure gauge 25 and the detection signal from the high water level detector 14 and controls the emergency control valve 12 according to the amount of non-condensable gas. Instead of the differential pressure gauge 25, a void gauge may be provided.
[0050]
Here, if the load increases in the plant or the like and the flow velocity becomes high, the gas does not flow into the emergency drain pipe 11 but flows along the main drain pipe 8. At this time, since the non-condensable gas does not accumulate in the connecting pipe (vertical portion) 11a of the emergency drain pipe 11, the emergency control valve 12 is not opened.
[0051]
In the second embodiment, even when non-condensable gas flows or stays in the drain pipe 8a, it flows into the connection pipe 11a of the emergency drain pipe 11, and the emergency control valve 12 is finely adjusted. By opening it, it is possible to discharge a part of the non-condensable gas and drain. As a result, a stable drain flow in which almost no non-condensable gas is present at the inlet of the control valve 7 is obtained, and the controllability of the control valve 7 can be maintained.
[0052]
Next, a third embodiment of the present invention will be described. FIG. 3 is an explanatory view of a feed water heater drain discharge device according to the third embodiment of the present invention. In the third embodiment, the water level in the feed water heater 4 is raised so that the drain does not flush in the drain pipe 8, and the drain pressure in the feed water heater or the piping is saturated by the pushing pressure by the drain hydrostatic head. It is intended to prevent the pressure from falling below.
[0053]
In FIG. 3, normal water level control is performed by the water level controller 24 as follows. That is, the water level in the drain cooling zone 30 of the feed water heater 4 is detected by the differential pressure gauge 25 and input to the water level controller 24. Then, in the water level controller 24, when the water level detected by the differential pressure gauge rises, the control valve 7 is operated in the opening direction to allow the drain to flow to the downstream feed water heater 3, and when the water level further rises, the emergency control valve 12 is turned on. Open and drain into condenser 1.
[0054]
On the other hand, the void meter 23 detects that drain flush has occurred due to non-condensable gas, and the detection signal of the void meter 23 is input to the water level controller 24. When the drain flush occurs, the water level controller 24 stops normal water level control and operates the control valve 7 in the closing direction to increase the water level inside the feed water heater 4. Here, instead of the void meter 23, a thermometer or a pressure gauge may be used.
[0055]
Further, the emergency control valve 12 of the emergency drain pipe 11 is fully opened and discharged to the condenser 1. In this operation, the function of the feed water heater 4 is reduced, but the phenomenon that the drain cannot be discharged from the control valve 7 by the drain flush with the non-condensable gas is a specific phenomenon that occurs at the time of partial load such as a trial operation particularly in the case of a nuclear power plant. Since this phenomenon does not occur during 100% rated operation, it is effective as an opposite method.
[0056]
In this way, by raising the water level inside the feed water heater 4 when drain flush occurs, the pushing pressure is applied to the drain cooling zone 30 and the flash voids generated in the drain cooling zone 30 disappear. Therefore, it is possible to prevent an unstable drain flow from flowing into the control valve 7.
[0057]
Next, a fourth embodiment of the present invention will be described. FIG. 4 is an explanatory view of a feed water heater drain discharge device according to the fourth embodiment of the present invention. In the fourth embodiment, when a drain flush occurs, a cooling water pipe 33 for supplying cooling water to the drain pipe 8 is provided, and a cooling water adjustment valve 32 is provided in each bypass pipe 31. is there.
[0058]
That is, the drain pipe 8 and the cooling water pipe 33 of another system are connected by the bypass pipe 31, and the cooling water adjustment valve 32 is provided in each bypass pipe 31. The cooling water pipe 33 is a system having a pressure higher than that of the emergency drain pipe 11 and lower than the drain temperature from the feed water heater 3 having the lowest drain temperature downstream.
[0059]
Now, it is assumed that the drain flush by the non-condensable gas occurs in the main body of the feed water heater 4 or inside the drain pipe 8 coming out of the feed water heater 4 and the drain cannot be discharged from the control valve 7. In this case, the cooling water adjustment valve 32 is slightly opened to supply cooling water from the cooling water pipe 33 to the drain pipe 8. That is, the water supply flows into the bypass pipe 31 from the cooling water pipe 33 toward the drain pipe 8. Thereby, the temperature in the drain pipe 8 is lowered, the drain temperature convection to the drain cooling zone in the drain pipe 8 or the feed water heater 4 is lowered by several degrees C., and the drain flash can be turned off. The amount of cold water necessary to turn off the drain flash is sufficient, so the balance of the system by injection is not lost.
[0060]
Next, a fifth embodiment of the present invention will be described. FIG. 5 is an explanatory view of a feed water heater drain discharge device according to the fifth embodiment of the present invention. This fifth embodiment is different from the fourth embodiment shown in FIG. 4 in that the drain pipe 8 in which the non-condensable gas stays in the cooling water from the cooling water pipe 33 when the drain flush occurs. It is made to supply to a convex bending part.
[0061]
As shown in FIG. 5, the bypass pipe 31 is connected to the convex bent part (elbow part) of the upper part of the drain pipe 8. In the fifth embodiment, a void meter 23 is installed in the vertical portion of the drain pipe 8, and the controller 22 detects the drain flash based on the detection signal of the void meter 23, and performs the drain flash. When it is detected, the opening degree of the cooling water adjustment valve 32 is controlled, and the cooling water is supplied to the convex bent portion of the drain pipe 8. Thereby, the drain flush can be effectively erased.
[0062]
Here, the void meter 23 may be installed in the drain cooling zone 30 in the feed water heater 4 so as to detect a flush of saturated drain in the drain cooling zone 30. Further, instead of detecting the void by the void meter 23, the saturation temperature of the drain may be detected by a thermometer, or the head of the water head may be detected by a pressure system.
[0063]
Next, a sixth embodiment of the present invention will be described. FIG. 6 is an explanatory view of a feed water heater drain discharge device according to the sixth embodiment of the present invention. In the sixth embodiment, when drain flush occurs, cooling water is supplied to the drain pipe 8 from the water supply pipe 2 that supplies water to the water heater.
[0064]
In FIG. 7, the drain pipe 8 and the water supply pipe 2 are connected by a bypass pipe 31, and a cooling water adjustment valve 32 is provided in the bypass pipe 31. Now, it is assumed that the drain flush by the non-condensable gas occurs in the main body of the feed water heater 4 or inside the drain pipe 8 exiting from the feed water heater 4 and the drain cannot be discharged from the control valve 7. In this case, when the cooling water adjustment valve 32 is opened, the feed water flows from the feed water pipe 2 toward the drain pipe 8 through the inside of the bypass bus 31. This is because the pressure of the feed water pipe 2 is higher between the same feed water heaters with respect to the drain pipe 8, and the feed water temperature in this case is lower by several tens of degrees Celsius than the drain temperature. The drain flash can be turned off.
[0065]
【The invention's effect】
As described above, according to the present invention, the non-condensable gas can be sent to the downstream feed water heater without flowing or staying in the drain pipe. Further, by collecting and discharging the non-condensable gas in the emergency drain pipe, the drain flow in the drain pipe can be stabilized.
[0066]
In addition, in the case of nuclear power plants, drain flushing occurs especially during partial loads when the load is rising, so the plant start-up operation can be performed by letting the non-condensable gas escape from the emergency drain pipe to the condenser via the control valve. Is possible. Further, by operating the control valve downstream of the feed water heater in the closing direction, the drain water level is raised and the drain flash generated in the feed water heater and the drain pipe is turned off, so that the flow can be stabilized. Furthermore, the drain flow in the drain pipe can be stabilized by installing a system for injecting a small amount of cold water from another system into the feed water heater or the drain pipe.
[Brief description of the drawings]
FIG. 1 is an explanatory view of a feed water heater drain discharge device according to a first embodiment of the present invention.
FIG. 2 is an explanatory diagram of a feed water heater drain discharge device according to a second embodiment of the present invention.
FIG. 3 is an explanatory view of a feed water heater drain discharge device according to a third embodiment of the present invention.
FIG. 4 is an explanatory diagram of a feed water heater drain discharge device according to a fourth embodiment of the present invention.
FIG. 5 is an explanatory diagram of a feed water heater drain discharge device according to a fifth embodiment of the present invention.
FIG. 6 is an explanatory view of a feed water heater drain discharge device according to a sixth embodiment of the present invention.
FIG. 7 is a system diagram of a conventional feed water heating system.
FIG. 8 is an explanatory diagram of a conventional feed water heater drain discharge device.
FIG. 9 is a characteristic diagram of pressure fluctuation depending on the gas ratio when the water flow rate in the drain pipe is a variable.
FIG. 10 is a characteristic diagram of the container water level fluctuation depending on the gas ratio when the water flow rate in the drain pipe is a variable.
FIG. 11 is a characteristic diagram of pressure fluctuation depending on the gas ratio when the air flow rate in the drain pipe is a variable.
FIG. 12 is a block diagram showing an embodiment according to the prior art.
2 Water supply pipes 3, 4, 5 Water heater 7 Control valve 8 Drain pipe 11 Emergency drain pipe 12 Emergency control valve 23 Void gauge 24 Water level controller 25 Differential pressure gauge 32 Cooling water control valve 33 Cooling water pipe 30 Drain cooling zone

Claims (3)

A drain pipe for allowing the drain to flow from the first feed water heater storing drain containing non-condensable gas to the second feed water heater on the low pressure side, and the first feed water heater provided in the drain pipe In the feed water heater drain discharge device comprising a control valve for adjusting the flow rate of the drain flowing out from the emergency drain pipe for directly discharging the drain from the first feed water heater to the condenser, An emergency control valve that is provided in an emergency drain pipe and adjusts the flow rate of the drain that flows out of the first feed water heater, and the water level inside the first feed water heater during start-up operation or low-load operation. A feed water heater drain device comprising a water level controller for raising . The feed water heater drain discharge device according to claim 1, wherein the water level controller operates the control valve in a closing direction when a drain flush occurs . The feed water heater drain discharge device according to claim 1, wherein the water level controller operates the emergency control valve in an opening direction when a drain flush occurs .

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