JPH0377402B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a warming method and a warming device for preventing sudden changes in the temperature of a feed water heater of a steam power plant.

[Background of the invention]

BACKGROUND OF THE INVENTION Conventionally, a water supply system for a steam power plant is generally constructed as follows using a device as shown in FIG.

After the boiler is ignited, the water in the deaerator 2 is supplied to the boiler via the water supply pipe 5 by the boiler water supply pump 4 at a flow rate corresponding to the minimum flow rate of the boiler. At this time, the water supply in deaerator 2 is in a vacuum deaeration state, and approximately 60
kept at ℃. Therefore, the high pressure water heater is also at about 60°C. When the turbine is ventilated, the amount of water supplied to the boiler increases to a flow rate corresponding to the amount of steam generated by the boiler, but the temperature of the supplied water at this time gradually rises from about 60°C. After turbine ventilation, when the turbine load is approximately 20%, the feed water heaters on the low-pressure low temperature side are It will be in-service sequentially from then on. In the figure, 1 is a condensate pipe, and 3 is a Pousta pump. 6, 7, and 8 are the third, second, and first high-pressure feed water heaters, respectively, and 9, 10, 11, and 12 are the first, second, third, and fourth air bleed pipes, respectively. 13 is a deaerator circulation pump, 14 is a deaerator circulation pipe, 15 is a water supply pump bypass pipe, 16 is a boiler clean-up pipe,
17 is a boiler water filling pipe, 18 is an auxiliary steam header, 19 is an in-house boiler, 20 is a deaerator auxiliary steam pipe, and 27 is a high-pressure feed water heater bypass pipe.

Figure 2 shows the temperature change during the above in-service operation, where t ₁ is the time of ventilation, t ₂ is the time of addition, t ₃ is the time of in-service of the third high-pressure feed water heater, and t ₄ is the time of the second
T 6 represents the in-service time of the high-pressure feed water heater, and T ₆ represents the feed water temperature at the inlet of the third high-pressure feed water heater,
T ₇ is the feed water temperature at the inlet of the second high pressure feed water heater, T ₈
respectively represent the feed water temperature at the inlet of the first high-pressure feed water heater.

As mentioned above, the inlet temperature T ₆ of each high-pressure feed water heater,
T ₇ and T ₈ are maintained at 60°C until the turbine ventilation time t ₁ , and from this state (temperature) the required temperature for high pressure feed water heater in service (third high pressure feed water heater: approx.
Raise the temperature to 130℃ (second high-pressure water heater: approx. 148℃, first high-pressure feedwater heater: approx. 187℃). In this case, the temperature increase rate in the third high-pressure feed water heater is approximately
210℃/H, approximately 227℃/H with the second high pressure water heater
H. In the first high-pressure feed water heater, the temperature changes rapidly by approximately 286°C/H. Therefore, localized thermal stress is generated in the water chamber of the high-pressure feed water heater.

FIG. 3 shows an example of the life consumption rate of a conventional high-pressure water heater. The above temperature change rate (third high-pressure feed water heater; approx. 210°C/H, second high-pressure feed water heater; approx.
227℃/H, 1st high pressure water heater; approx. 286℃/H)
According to the figure, the life consumption rate of the high pressure feed water heater per cycle of plant start-up and stop is as shown in this figure: 3rd high pressure feed water heater: about 0.011%, 2nd high pressure feed water heater: 0.013%, 1st high pressure feed water heater ; Approximately 0.018%.

As mentioned above, conventional high-pressure water heaters have a spherical water chamber with R
It is necessary to design and manufacture parts with large dimensions, making the high-pressure feedwater heater larger, and the life of the high-pressure feedwater heater is shortened due to the increase in the number of plant starts and stops due to daily start-stop operations. , which has a significant impact on reducing the reliability of the entire plant. Furthermore, in the ultra-supercritical pressure plants currently being considered and planned for practical use, the required feed water temperature will be relatively high, making it increasingly difficult to deal with the thermal stress described above. For the above reasons, reducing the thermal stress of the high-pressure feed water heater has become an important issue in order to put an ultra-supercritical pressure steam power plant into practical use.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned circumstances, and is a warming method capable of preventing sudden changes in temperature of a high-pressure feedwater heater during the period from boiler ignition to high-pressure feedwater heater in-service in a steam power plant (hereinafter referred to as startup process). , and a warming device.

[Summary of the invention]

In order to achieve the above object, the warming method of the present invention preheats the feed water by introducing a high-temperature fluid other than the bleed steam of the steam engine into the water supply system during the startup process of the steam engine, and from the start of ventilation to the feed water heater. It is characterized by suppressing the temperature rise rate (per hour) of the high-pressure feed water heater until it enters service.

In addition, the warming device of the present invention is used in a water supply system of a steam engine plant, and includes a pipe line that introduces high-temperature fluid other than extracted steam from the steam engine into the water supply system, and a heat exchange between the introduced steam and the water supply. The present invention is characterized in that a means for causing the same is provided.

[Embodiments of the invention]

FIG. 4 shows an example of the apparatus of the present invention configured to carry out the warming method of the present invention.

This embodiment is an improvement by applying the present invention to the conventional device shown in FIG.
The components are the same as those in Figure).

In this embodiment, high-temperature steam from the in-house boiler 19 or another can 30 is introduced into the third high-pressure feed water heater 6 via the auxiliary steam header 18. 22 is a temperature control valve provided in the warming steam pipe 21. This temperature control valve 22 has a third
Temperature detector 2 installed at the outlet of the high-pressure feed water heater 6
The opening/closing is controlled by 3.

When the boiler is ignited, water corresponding to the minimum flow rate of the boiler is supplied from the deaerator 2 to the booster pump 3,
Water is supplied to the boiler by the boiler feed water pump 4 via the water supply pipe 5 and the high-pressure feed water heater bypass pipe 27. At this time, the high-pressure feed water heater side is shut off by the outlet valve 31 and the inlet valve 32 to prevent the feed water from passing through. On the other hand, the high-pressure feedwater heater warming steam (in this embodiment, steam from the auxiliary steam header 18 is used) is transferred to the third high-pressure feedwater heater 6 via the warming steam pipe 21 at the time of boiler ignition. The third high-pressure water heater 6 is warmed. The warming steam that has absorbed heat during warming becomes drain and is recovered to the condenser through a drain pipe (not shown) of the third high-pressure feed water heater 6. In addition, the amount of warming steam is determined by the temperature sensor 2 installed on the water chamber side of the outlet of the third high-pressure feed water heater 6.
3, and adjust the temperature to the target temperature using the temperature control valve 22 installed in the warming steam pipe 21. When the turbine enters the ventilation state, the amount of water supplied to the boiler increases, but water is supplied with the high-pressure feedwater heater bypassed by the bypass pipe 27, and the load increases to about 10 to 20%, causing a difference between the target warming temperature of the high-pressure feedwater heater and the input temperature. When there is almost no difference in the temperature required for service, switch the high-pressure feed water heater from bypass to water flow and stop warming. When the turbine load reaches about 20%, the third high-pressure feed water heater 6, the second high-pressure feed water heater 7, and the first high-pressure feed water heater 8 are brought into service in this order.

When warming is performed as described above, when the high-pressure feed water heater is switched from the bypass state to the water flow state, the high-pressure feed water heater has been warmed in advance, so no sudden change in temperature occurs. Therefore, there is no risk of locally generating large thermal stress. As described above, the warming method of the present invention preheats the feed water by introducing a high-temperature fluid other than the extracted steam from the steam engine into the water supply system during the start-up process of the steam engine plant, and from the start of ventilation to the feed water heater. Since it is possible to suppress the temperature rise rate (per hour) of the high-pressure feed water heater until it is in service,
It is possible to prevent excessive local thermal stress from occurring due to sudden changes in temperature.

Furthermore, as described above, in a water supply system of a steam engine plant, the device of the present invention includes a pipe line for introducing high temperature fluid other than extracted steam from the steam engine into the water supply system, and By providing a means for performing heat exchange with the water supply, the method of the present invention described above can be easily carried out and its effects can be fully exhibited.

FIG. 5 is a water supply system diagram for explaining an embodiment different from the above.

In this embodiment, compared to the embodiment shown in FIG.
The basic configuration of the devices is the same, and the operating methods are also basically the same. The difference from the embodiment shown in FIG. 4 is that each high-pressure feed water heater is provided with a warming steam pipe 21 and a temperature control valve 22, respectively.

As in the embodiments shown in FIGS. 4 and 5 above,
In addition to using auxiliary steam as a preheating fluid for the feedwater heater, when preheating the feedwater heater with the auxiliary steam mentioned above, controlling the high-temperature steam flow rate based on the feedwater temperature at the outlet of the high-pressure feedwater heater, it is possible to The method of the present invention can be carried out without significantly increasing the number of components, and temperature control is easy.

FIG. 6 shows a system configuration of an embodiment different from the above. Similar to the embodiment shown in FIG. 4, when the boiler is ignited, water is supplied by the boiler minimum flow rate from the deaerator 2, the booster pump 3, the boiler feed water pump 4, the water supply pipe 5, and the high pressure feed water heater bypass pipe 27. The water is then supplied to the boiler. At this time, the high-pressure feed water heater side is shut off by the inlet/outlet valve to prevent the feed water from passing through. On the other hand, the high-pressure feed water heater warming water is already being fed to the high-pressure feed water heater via a warming pipe 25 that branches from the deaerator circulation piping 14, which is the discharge side of the deaerator circulation pump 13 that is in operation, for deaeration of the feed water. Water is passed to the water supply side inlet. This warming water is heated by introducing superheated steam (in this embodiment, auxiliary steam is used) into the warming heater 24 installed in the warming pipe 25 to obtain the amount of heat necessary for warming, which is then heated to the high-pressure feed water heater water supply side. Water is passed to the entrance. High pressure water heater 6, 7, 8
The warming water that has passed through is collected into the condenser through the preboiler clean-up pipe 16 at the outlet of the first high-pressure feed water heater 8. Further, the amount of warming water is adjusted to a target temperature by a temperature control valve 22 installed in the warming pipe 25 and a temperature detector 23 installed in the water supply pipe at the outlet of the first high-pressure water heater 8.

When the turbine is ventilated, the amount of water supplied to the boiler increases, but water is supplied to the boiler while the high-pressure feedwater heater is bypassed. When the load increases (10-20%) and there is almost no difference between the target warming temperature of the high-pressure feedwater heater and the required in-service temperature at the inlet of the high-pressure feedwater heater, warming is stopped and the high-pressure feedwater heater is bypassed. When the turbine load reaches about 20%, the third high-pressure feed water heater 6, the second high-pressure feed water heater 7, and the first high-pressure feed water heater 8 are brought into service in this order.

Because the high-pressure water heater is warmed in advance, large thermal stress does not occur.

FIG. 7 shows a system configuration of a further different embodiment. The basic configuration and operating method of this embodiment are the same as the embodiment shown in FIG. The difference from the embodiment in FIG. 6 is that in the embodiment in FIG.
In the embodiment shown in FIG. 7, the steam heat exchanged in the warming heater 24 is collected as drain into the water storage tank of the deaerator 2. This is what I did.

As in the embodiments shown in FIGS. 6 and 7 described above,
A part of the deaerator circulating water is extracted and used as water supply,
Preventing sudden changes in the temperature of the high-pressure feed water heater by heating the feed water with high-temperature steam and performing the above heating using a heat exchanger installed separately from the high-pressure feed water heater. I can do it.

FIG. 8 shows a system configuration of a further different embodiment. This embodiment is the same as the embodiment shown in FIG. 6 in terms of both the basic system and the operating method. The difference from the embodiment shown in FIG. 6 lies in the installation position of the warming heater 24. In the embodiment shown in FIG. 6, the warming heater 2
4 is installed in the warming pipe 25, this embodiment is characterized in that it is installed in the deaerator circulation pipe 14 on the discharge side of the deaerator circulation pump 13.

In this embodiment, by heating the entire deaerator circulating water, it can be expected that it can be used not only for warming the high-pressure feed water heater but also for warming the boiler feed water pump.

FIG. 9 shows a system configuration of a further different embodiment. As in the previous embodiment, water is supplied by boiler ignition.
The minimum flow rate of the boiler is transferred from the deaerator 2 to the booster pump 3 and the boiler water supply pump 4 to the water supply pipe 5,
Water is supplied to the boiler via the high-pressure feed water heater bypass pipe 27. At this time, the high-pressure feed water heater side is shut off by the inlet/outlet valve to prevent the feed water from flowing. On the other hand, the warming water of the high-pressure feed water heater passes through the boiler feed water pump bypass pipe 15 that branches from the connection pipe between the booster pump 3 and the boiler feed water pump 4, and some of the water is used as warming water on the high-pressure feed water heater water supply side. Water is passed to the entrance. This warming water is heated by introducing superheated steam (in this example, auxiliary steam is used) into the warming heater 24 installed in the boiler feed water pump bypass pipe 15 to obtain the amount of heat necessary for warming and heat the high-pressure feed water. Water is passed through the water supply side inlet of the vessel. The warming water that has passed through the high-pressure feedwater heaters 6, 7, and 8 is recovered to the condenser through the preboiler clean-up pipe 16 at the outlet of the first high-pressure feedwater heater 8.
Further, the amount of warming steam is adjusted to a target temperature by a temperature control valve 22 installed in the warming steam pipe 21 and a temperature detector 23 installed in the water supply pipe at the outlet of the first high-pressure feed water heater 8. Ru.

When the turbine is ventilated, the amount of water supplied to the boiler increases, but water is supplied to the boiler while the high-pressure feedwater heater is bypassed. When the load increases (10 to 20%) and there is almost no difference between the target warming temperature of the high-pressure feedwater heater and the required in-service temperature at the inlet of the high-pressure feedwater heater, stop warming and switch the high-pressure feedwater heater from bypass. Switching to water flow operation, when the turbine load drops to about 20%, the third high-pressure feed water heater 6, the second high-pressure feed water heater 7, and the first high-pressure feed water heater 8 are brought into service in this order.

This embodiment also provides the same effects as the previous example.

FIG. 10 shows a system configuration of a further different embodiment. The basic concept and operating method are the same as the embodiment shown in FIG. 9 above. The feature of this embodiment is that the warming heater 24 is installed in the boiler water filling pipe 17, and warming water is supplied by a water pump. This embodiment also provides the same effects as the previous example.

FIG. 11 is a chart showing temperature changes in the embodiment of the present invention, and corresponds to FIG. 2 in the prior art.

t ₁ -t ₅ and T ₆ -T ₈ using the same drawing reference symbols as in FIG. 2 represent the same meanings as in FIG. 2. In the above example, the warming temperature is approximately
If controlled at 160℃, the high pressure feed water heater temperature reaches approximately 160℃ during turbine ventilation, and by putting the high pressure feed water heater in service, the temperature of the third high pressure feed water heater T ₆ reaches approximately 90℃/H. , the temperature changes at approximately 31°C/H in the second high-pressure feed water heater T ₇ and approximately 61°C/H in the first high-pressure feed water heater T ₈ , which is the temperature change range of the conventional technology (see Figure 2). Compared to
It is possible to significantly reduce thermal stress.

FIG. 12 shows the life consumption rate of the high-pressure feed water heater according to the embodiment of the present invention. As shown in this figure, compared to the life consumption rate of the conventional technology (see Figure 3), the first, second, and third
The lifetime consumption rate of any high-pressure feed water heater
It can be reduced by more than 50%, and the service life of high pressure water heater will be significantly increased.

〔Effect of the invention〕

As detailed above, according to the warming method of the present invention, it is possible to prevent sudden temperature changes in the high-pressure feedwater heater during the startup process from boiler ignition to high-pressure feedwater heater in-service in a steam power plant. Accordingly, local thermal stress can be reduced. This naturally makes it possible to reduce the cost of the high-pressure feed water heater, and also to reduce the lifetime consumption rate, which greatly contributes to the practical application of ultra-supercritical pressure plants.

[Brief explanation of drawings]

Fig. 1 is a schematic system configuration diagram of the prior art, Fig. 2 is a temperature state diagram of the high pressure feed water heater of the prior art, Fig. 3 is a chart showing the life consumption rate of the high pressure feed water heater of the prior art, and Figs. FIG. 10 is a water supply system diagram of one embodiment of the present invention, FIG. 11 is a temperature state diagram of the high-pressure feed water heater in the embodiment of the present invention, and FIG. 12 is a chart showing the life consumption rate. 1... Condensate pipe, 2... Deaerator, 3... Booster pump, 4... Boiler feed water pump, 5... Water supply pipe, 6... Third high pressure feed water heater, 7... Second high pressure feed water heating device, 8...first high pressure water heater, 9...
1st bleed pipe, 10...2nd bleed pipe, 11...3rd
Air bleed pipe, 12... Fourth bleed pipe, 13... Deaerator circulation pump, 14... Deaerator circulation piping, 15... Water pump bypass pipe, 16... Preboiler clean up pipe, 17... Boiler Water piping, 18...
...Auxiliary steam header, 19...In-house boiler, 20...
... Deaerator auxiliary steam pipe, 21 ... Warming steam pipe, 22 ... Temperature control valve, 23 ... Temperature detector,
24...warming heater, 25...warming pipe, 26...warming drain pipe, 27...
…High-pressure feed water heater bypass pipe, t ₁ …At the time of ventilation,
t ₂ ... At the time of merging, t ₃ ... When the third high pressure feed water heater is in service, t ₄ ... When the second high pressure feed water heater is in service, t ₅ ... ... When the first high pressure feed water heater is in service, T ₆ ...Third high pressure feed water heater inlet feed water temperature, _T7 ...Second high pressure feed water heater inlet feed water temperature,
T ₈ ...The first high-pressure feed water heater inlet feed water temperature.

Claims (1)

[Claims] 1. In the startup process of a steam engine plant, before the feed water is passed through the high pressure feed water heater, high-temperature steam other than the extracted steam of the steam engine is directly introduced into the high pressure feed water heater, or Preheating the high pressure feed water heater by introducing high temperature fluid heated by high temperature steam,
When the temperature of the high-pressure feedwater heater reaches a predetermined temperature, the introduction of the high-temperature steam or the high-temperature fluid to the high-temperature feedwater heater is cut off, and then the feedwater is passed through the high-temperature feedwater heater to cool the feedwater. A warming method for a high-pressure water heater that is characterized by heating. 2. A method for warming a high-pressure feedwater heater according to claim 1, characterized in that high-temperature steam is directly introduced into the high-pressure feedwater heater to preheat it. 3. In the water supply system of a steam engine plant, the high-pressure feedwater heater is preheated by directly introducing high-temperature steam other than the extracted steam from the steam engine, or by introducing high-temperature fluid whose temperature has been raised by the high-temperature steam. It is characterized by comprising a warming pipe, a temperature detection means for detecting the temperature of the high-pressure feed water heater, and a control valve that shuts off the warming pipe when the temperature detection means detects that the temperature has reached a predetermined temperature. Warming device for high pressure water heater. 4. A warming device for a high-pressure feedwater heater according to claim 3, characterized in that a warming pipe is connected to the steam inlet of the high-pressure feedwater heater and the high-pressure feedwater heater is directly preheated with high-temperature steam. .