JPS60219404A - Stabilizing device of deaerator output - Google Patents

Abstract

PURPOSE:To stabilize saturated water in the outlet of a deaerator, by controlling a control valve, arranged in a rapid follow-up substitute pipe, in accordance with the pressure and the temperature in a down take pipe, in a steam turbine power plant. CONSTITUTION:A down take pipe 14, provided in an outlet 7a of a deaerator 7, connects with a high pressure feed water pipe 15 connected to a boiler 1. This high pressure feed water pipe 15 arranges a booster pump 20 and a feed water pump 21. The high pressure water pipe 15 provides a rapid follow-up substitute pipe 23 connected to a condenser 5, while this rapid follow-up substitute pipe 23 arranges a control valve 24. This control valve 24 additionally provides a comparator 27 to which a signal is transmitted from a pressure oscillator 29 through an arithmetic device 26 while from a temperature detector 30. In this way, the down take piece can be cleaned up by enabling saturated water in the outlet of the deaerator to be stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a deaerator outlet stabilization device for stabilizing and supplying deaerator outlet feed water in a steam turbine power plant.

[Technical background of the invention]

This type of steam turbine power plant that has already been proposed is configured as shown in FIG. That is, a boiler 1 in a power generation plant is provided with a main steam pipe 2 connected to a steam turbine 4 directly connected to a generator 3, and a condenser 5 is disposed below the steam turbine 4. There is. Further, at the outlet of the condenser 5, a condensate pipe 6 is connected to a deaerator 7 that removes dissolved oxygen from the water supply. A pump 8, a water treatment device 9, and a low pressure feed water heater 10 are arranged in this order.

Furthermore, an air extraction pipe 11 connected to the deaerator 7 is provided on the inlet side of the condenser 5, and this air extraction pipe 11 degasses the heated steam from the intermediate stage of the steam turbine 4. The water is supplied to the vessel 7. Furthermore, on one side of the deaerator 7, there is an auxiliary steam pipe
3, and the steam of this auxiliary boiler 12 is supplied as required.

On the other hand, a downcomer pipe 14 is provided vertically at the outlet of the deaerator 7, and a high-pressure water supply pipe 15 is connected to the boiler 1 at one end of the downpipe pipe 14. Further, a circulation pipe 17 equipped with a deaerator circulation pump 16 is provided in a part of the downcomer pipe 14 and is connected to the condensate pipe 6. A clean-up pipe 19 having an on-off valve (clean-up valve) 18 is connected to the condenser 5.

Furthermore, a booster pump 20, a water supply pump 21A, and a high-pressure feed water heater 22 are arranged in this order in the high-pressure water supply pipe 15, which heats the water supplied from the deaerator 7 to the boiler L. It is designed to provide water.

Therefore, the above-mentioned steam turbine power generation plant supplies high-temperature, high-pressure steam generated in the boiler base to the steam turbine 4 through the main steam pipe 2, rotates the steam turbine 4 here, and generates power directly connected to the steam turbine 4. Drive machine 3 to generate electricity.

However, the steam that has completed its work in the steam turbine 4 is
The steam transferred to the condenser 5 is reconstituted by heat exchange, and the condensate is transferred to the water treatment device 9 of the condensate pipe 6 by the condensate pump 8, Feed water heater 10. and is transferred to the deaerator 7. The condensate supplied to the dehydrator 7 removes dissolved oxygen in the feed water, which causes corrosion, and is returned to the boiler 1 from the downpipe 14 through the high-pressure water supply pipe 15. .

On the other hand, in the start-up process of the power plant, the condensate pipe 6 equipped with the low-pressure feed water heater 10 and the high-pressure water supply pipe 15 equipped with the high-pressure feed water heater 4 are operated until the water quality standard value of the feed water allowed by the boiler 1 is reached. , be sure to perform a cleaning process (cleanup).

Generally, in the cleaning step, the condensate pipe 6 from the condenser 5 to the deaerator 7, the downcomer pipe 14, and the high-pressure water supply pipe 15 are sorted and cleaned in order from the upstream side.

Note that the cleanup pipe 19 provided with the on-off valve 18 constitutes a part of the circulation route of the deaerator 7 and the condensate pipe 6, and is provided for cleaning up.

In this case, of course, since this is a startup process, the steam turbine 4 is in a stopped state. Therefore, the bleed pipe 11 greatly affects the deaeration efficiency of the deaerator 7.
You cannot expect heating steam from.

Therefore, in the startup step described above, heating steam to the deaerator 7 is configured such that steam from the auxiliary boiler 12 is supplied through the auxiliary steam pipe 13.

On the other hand, the degassing function of the deaerator 7 has the ability to make the outlet water of the deaerator 7 O, <7 ppb in the rated operating state of the power plant. Also, the deaerator 7 has a rated state of approximately 251 liters of water, which is the amount of water to be circulated during cleanup.
There is sufficient room for degassing the air. moreover,
In order to effectively utilize the heated steam supplied from the auxiliary boiler 12, the circulation pipe 17 equipped with the deaerator circulation pump 16 operates effectively.

Next, when the power generation plant is suddenly cut off or reduced in load from normal operation, the deaerator 7 uses extracted steam from the bleed pipe 11 to fill a container corresponding to the load of the steam turbine 4. Maintaining pressure. Further, the condensate from the condensate pump 8 passes through the low-pressure feed water heater 10 and flows into the deaerator 7, and its flow rate is set at the same rate as that from the feed water used in the boiler 1 to the deaerator 7. bleed air flow rate and high pressure feed water heater 15 to deaerator 7
The flow rate is approximately equal to the drain flow rate.

On the other hand, the water level in the water storage tank of the deaerator 7 is controlled to be constant, and the fluid in the water storage tank is also kept balanced at a saturated temperature state corresponding to the pressure inside the container.

In such a state, if the load is suddenly changed due to an emergency stop due to an earthquake or lightning strike, for example, it will be difficult to effectively maintain the extracted steam from the steam turbine 4. Furthermore, due to the sudden decrease in the amount of water required to be supplied to the boiler 1, the amount of water sent by the booster pump and the water supply pump 21 is reduced.

On the other hand, the flow rate of the condensate from the condensate pump 8 is adjusted depending on the water level of the water storage tank of the deaerator 7.
The flow rate of water supplied to the boiler 1 decreases, which in turn decreases following the rising trend of the water level in the water storage tank of the deaerator 7. Additionally, these phenomena cause a time lag in response to a reduction in water supply. Furthermore, since the heating steam source of the low-pressure feed water heater 10 disappears at the same time as the load is cut off, the temperature of the condensate flowing into the deaerator 7 gradually decreases under the above-mentioned situation. .

In this way, the deaerator 7 and the downcomer pipe 14 described above maintain equilibrium with the pressure and temperature of the fluid, the inflow into the deaerator 7, and the outflow failure under normal operating conditions, but when load shedding occurs, The internal pressure of the deaerator 7 rapidly decreases to a low F, and the temperature of the condensate flowing into the deaerator 7 also decreases, which promotes the decrease in the internal temperature.

On the other hand, the hot water in the deaerator 7 and the downcomer pipe 14 stays at the initial temperature before the transition because the water supply to the boiler 1 is reduced. As a result, the fluid flowing into the deaerator 7 and the downcomer pipe 14 loses the pressure and temperature balance, causing a flash phenomenon (self-evaporation phenomenon), similar to boiling water at a temperature below 100°C in a high mountain. This causes an unstable gas-liquid two-phase state.

In such an unstable state, the fluid flow in the downcomer pipe 14 changes four times, inducing a water hammer phenomenon, and in severe cases, the centering of the booster pump 20 may be shifted, or the connection of the high pressure water supply pipe 15 may be interrupted. There is a risk of leakage from the department. Furthermore, in the water storage tank of the deaerator 7, a similar flash phenomenon occurs, the liquid level in the tank is disturbed, and the output signal of the water level detector that controls the flow rate of condensate is also disturbed, resulting in the flow of η water. Control becomes difficult. Furthermore, this condensate flow rate control will also have an adverse effect on the other control mechanisms in the power generation plan I. Further, since the above-mentioned power generation plants widely employ automatic control, it is difficult to easily restore the disturbance in the control of the control mechanism even if the operator intervenes.

In addition, in the power generation plants that have already been proposed, a deaerator circulation pump 16 is employed in order to alleviate the above-mentioned flash phenomenon as much as possible. That is, for a series of transient behaviors, this means that the fluid stays at a temperature higher than the saturation temperature corresponding to the pressure, and the hot water in the downcomer pipe 14 is discharged and replaced more quickly, and the saturation temperature corresponds to the pressure. The aim is to make it into a fluid. In other words, the flash phenomenon is such that the deaerator circulation pump 16 is automatically activated by a load signal that detects a load cut-off or a sudden decrease in the load of the power generation plant.

On the other hand, the means for removing hot water above the saturation temperature is intended to maintain the saturation pressure commensurate with the fluid temperature by alleviating the drop in the internal pressure of the deaerator due to loss of extracted steam in the deaerator 12. has also been adopted.

In this way, a method is adopted in which auxiliary steam is used as a heating steam source instead of the steam extracted to the deaerator 7. That is, this is to supply heated steam from the auxiliary boiler 12 to the deaerator 7 through the auxiliary steam pipe 13 during a transient period. Another means is to suppress the flow of cold water into the deaerator 7 in order to reduce the internal pressure of the deaerator 7 during a transient period. However, this method does not prevent the internal pressure of the deaerator 7 from decreasing, but only slows down the pressure decrease. It is difficult to maintain the saturation pressure of hot water.

Therefore, when the above-mentioned flash phenomenon occurs, attempts are made to solve the problem by using the above-mentioned means in combination.

Specifically, the control of the condensate flow rate regulating valve (not shown) provided in the condensate pipe 6 is controlled in a transient-specific manner, for example, by lowering the water level setting of the deaerator 7 and setting it in advance. The condensate flow rate is adjusted to be constant.

[Problems with background technology]

However, since the deaerator circulation pump 16 is used in the circulation pipe 17, the deaerator output stabilizing device described above cannot effectively and appropriately stabilize the flash phenomenon that occurs during transient periods without a time lag. Not only is this difficult, but the deaerator circulation pump 16 must be installed so as to communicate with the rainwater 114 of the deaerator 7, which may increase the size of the entire device.

[Purpose of the invention]

Does the present invention address the above-mentioned circumstances? ffi, and when the load is cut off or when the load drops at a high rate of load change,
Stabilizes the saturated water inside the deaerator and at the deaerator outlet, eliminates water hammer in downcomer pipes and disturbances in the control system due to flash phenomena, and improves reliability and stability in power plants. The present invention provides a deaerator outlet stabilizing device that aims to improve the performance of the deaerator.

[Summary of the Invention] The present invention connects a high-pressure water supply pipe connected to a boiler to a downcomer pipe provided at the outlet of a deaerator, and arranges a booster pump and a water supply pump in this high-pressure water supply pipe, so that both pumps can be connected to each other. A rapid follow-up displacement pipe connected to the condenser is provided in the high-pressure water supply pipe located between, and a control valve is provided in this rapid follow-up displacement pipe,
A comparator equipped with a computing unit is attached to the control valve, a pressure detector is provided in the downcomer pipe so as to transmit signals to the computing unit, and a temperature detector is provided below the downcomer pipe to transmit signals to the comparator. It is provided and configured in this way.

[Embodiments of the invention]

Hereinafter, the present invention will be described with reference to an illustrated embodiment.

It should be noted that the present invention will be described with the same reference numerals attached to the same constituent members as in the above-described specific example.

In FIG. 2, reference numeral 7 denotes a deaerator installed in the power generation plant, and a downcomer pipe 14 is vertically installed at the outlet lower a of the deaerator 7. A high pressure water supply pipe 15 is connected to the boiler 1. Also, this high pressure water supply pipe 15 is equipped with a booster pump 2.
0 and a water supply pump 21 are arranged, and both pumps 2
The high-pressure water supply pipe 15 located between 0 and 21 is provided with a rapid follow-up displacement pipe 23 connected to the condenser 5. Further, this rapid follow-up displacement pipe 23 is provided with a control valve (current control valve) 24 and an on-off valve 25, respectively. It is attached and connected to. Note that the comparator 27 is provided with a bias setting device a for preventing malfunction. Furthermore, a pressure detector 29 is provided on the downcomer pipe 14 via a lead wire 29a to the arithmetic unit 26, and a pressure detector 29 is provided at a lower position of the downcomer pipe 14 than the mounting position of the pressure detector 29. , temperature sensor (
Temperature sensor) 30 is the lead wire 30a to the comparator 27
It is provided through. Note that the temperature detector 30 becomes hotter as it goes downstream of the downcomer pipe 14, so this is effective in detecting signs of self-evaporation and eliminating the time lag of the temperature detector 30. It is. Furthermore, since the bias setting device path can be set arbitrarily, the control valve 24 is opened only when the output deviation signal of the comparator 27 exceeds a certain set point, so that noise-like pressure disturbances are avoided. This is effective in preventing malfunction of the valve and manually opening the adjustment valve during cleanup.

Therefore, the present invention provides the following advantages when a flash phenomenon occurs.

The opening and closing of the control valve arm is controlled based on the deviation signal from the comparator 27.

That is, the downcomer pipe 14 provided at the outlet lower 8 of the deaerator 7
The pressure detector 29 detects the fluid pressure at the downcomer pipe 14, and transmits this detection signal to the computer station via the lead wire 29a. The fluid temperature is detected and this detection signal is sent to the comparator 27 via the lead wire JOa, and the comparator 27 compares the signal from the arithmetic unit 26 and determines whether the deviation signal is equal to the reference value (set value). When the deviation exceeds the deviation signal, the control valve 14 is controlled to open or close in accordance with this deviation signal, thereby preventing the occurrence of a flash phenomenon.

When the load drops from a constant state to a certain load at a high rate of change.

In the initial state where the load is constant, the saturation temperature determined by the calculator 26 from the pressure detected by the pressure detector 29 and the temperature detected by the temperature detector 30 are the difference in hydrostatic head up to the pressure detection. The former is larger by the amount corresponding to . Furthermore, since the bias setting device A is bias-set, the negative deviation from the comparator 27 becomes even larger. Therefore, the control valve 24 is maintained in a closed state.

Therefore, when the load is reduced from the above-mentioned state, the internal pressure of the deaerator 7 is reduced. However, it takes about 20 seconds at about 100% load for the fluid to reach the inlet of the booster pump from the deaerator 7. The fluid has an initial temperature.

On the other hand, the flow rate of water supplied to the boiler 1 by the water supply pump 21 decreases as the load decreases. Since this is K,
The time it takes to reach the booster pump 20 from the deaerator 7 becomes longer as the load decreases. In this way, as the load decrease progresses, a series of these phenomena progresses, and the internal pressure of the deaerator 7 is low, causing the downcomer pipe 14 of the deaerator 7 to
The process progresses when the fluid temperature inside is high.

Therefore, the higher the load drop rate, the more severe the above-mentioned phenomenon becomes, and the most severe one is a load shedding condition.

As the unstable condition progresses, the downpipe 1
The fluid in 4 becomes more than saturated and cannot maintain a liquid state, resulting in a self-evaporation phenomenon. That is, the self-evaporation phenomenon described above is caused by the load curve L11 as shown in the graph of FIG.
When the direction line P1 is the saturation temperature curve To and the fluid detection temperature is T, the self-evaporation phenomenon occurs in the range A shown by the chain line with a time delay from the start of the load drop, but in the present invention,
As described above, this is immediately detected and the control valve arm is opened to properly discharge the required flow rate from the rapid follow-up displacement pipe to the condenser 5 to maintain the stability of the downcomer pipe 14. It has become.

That is, as the load decrease progresses, the pressure detector 29
Subsequently, the pressure state value is input to the calculator 26, which immediately calculates and outputs the saturation temperature. or,
The comparator 27 compares the saturation temperature and the fluid temperature from the temperature detector 30, and outputs the result according to the deviation value. In addition,
Since the comparator 27 is inputted with the signal of the bias setting device set to the reference value in advance, when the deviation value exceeds the reference value (set value), the beak is adjusted based on this deviation value. Valve 24 is opened.

In this way, the accumulated water at the time of load drop is discharged to the condenser 5, and the fluid temperature of the temperature sensor 30 is maintained below the eroding temperature, so that the stability around the deaerator 70 is maintained. It has become. When one more load reaches the target load,
The output deviation from the comparator 27 becomes smaller and approaches the reference value set by the bias setting device 4, and the control valve arm gradually closes.

On the other hand, when the load increases, the above-described situation is reversed. Therefore, the temperature detected by the temperature detector 30 is always smaller than the saturation temperature determined by the arithmetic unit 26, and the output signal from the comparator 27 keeps the control valve 24 closed. .

The graph shown in FIG. 4 shows that the fluid temperature T of the first temperature detector 30 is adjusted and controlled to be equal to or lower than the saturation temperature To corresponding to the pressure of the pressure detector 29, as described above. be.

Next, another embodiment of the present invention shown in FIG. 5 has two series of booster pump 20 and water supply pump 21,
The present invention shown in FIG. 1 and FIG. 2 is applied to these two series.

That is, in the case of the two series shown in FIG. 5, this means that one booster pump 20a is stopped and the suction valve 31a is stopped.

31b and the discharge valves 32a, 32b are separated, and the power plant is operated by the other system.

Even if the load drops in such a state, the deaerator 7 of one of the stopped systems will be
As the temperature decreases, a self-evaporation phenomenon occurs in the tubes 14a and 14b. Therefore, the rapid follow displacement tube 23a.

5b is provided with respective auxiliary follow-up displacement pipes 33a, 33b, and respective take-out valves 34a, 34bs and check valves 35a, 35b are attached to this container pipe.

As a result, even if a plurality of lines are provided at the outlet of the deaerator 7, the above-mentioned flash phenomenon can be effectively and appropriately eliminated, and the water at the outlet of the deaerator 7 can be stabilized.

〔Effect of the invention〕

As described above, according to the present invention, the outlet lower a of the deaerator 7
A high-pressure water supply pipe 15 connected to the boiler 1 is connected to a downcomer pipe 14 provided in A rapid follow-up displacement pipe 23 connected to the condenser 5 is provided in the high-pressure water supply pipe 15, a control valve 24 is disposed in the rapid follow-up displacement pipe 23, and a comparator 27 equipped with a computing unit 26 is provided in the control valve 24. Attached to the above downcomer pipe 1
A pressure detector 29 is provided at the lower part of the downcomer pipe 14 so as to send a signal to the comparator 27, so there is no time lag. Not only can the deaerator 7 be stabilized (1.18 IC 1'), but the entire device can be made smaller and lighter, and it also has excellent features such as being able to clean up the downpipe described in [4] above. It is effective.

[Brief explanation of the drawing]

FIG. 1 is a diagram of a deaerator outlet stabilizing device in a power plant that has already been proposed, FIG. 2 is a diagram of a deaerator outlet stabilizing device according to the present invention, and FIGS. Figure 4 is
Graphs showing the relationships between pressure, temperature, load, and time, FIG. 5, are diagrams showing other embodiments of the present invention. l... Boiler, 4... Steam turbine, 5... Condenser, 7... Deaerator, 14... Downpipe, 15...
High pressure water supply pipe, 20... Booster pump, 21...
Water supply pump, c...high-speed follow-up displacement pipe, 24...control valve, 25...on/off valve, 26...computer, 27...
Comparator, 29...pressure detector, 30...temperature detector. Applicant's agent: Ino Mata) ＠ ＄2 Figure

Claims (1)

[Claims] 1. A high-pressure water supply pipe connected to the boiler is connected to a downpipe provided at the outlet of the deaerator, a booster pump and a water supply pump are arranged in this high-pressure water supply pipe, and a booster pump and a water supply pump are arranged between the two pumps. A rapid follow-up displacement pipe connected to the condenser is installed in the above-mentioned high-pressure water supply pipe installed vertically, a control valve is installed in this rapid follow-up waste pipe, and a comparator equipped with a computing unit is attached to this control valve. , a deaerator characterized in that a pressure detector is provided in the downcomer tube so as to send a signal to the arithmetic unit, and a temperature sensor is provided below the downcomer so as to send a signal to the comparator. Exit stabilizer. 2. The deaerator outlet stabilizing device according to claim 1, characterized in that a bias setting device is attached to the comparator.