JPS60200086A - Condenser stopping method and condenser mechanism utilized in stopping method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a method for shutting down a condenser and a condenser system used to adopt and implement the shutoff method. In particular, when using a condenser configured to condense steam from a steam turbine in a steam condensing section and store the condensed water in a hot well, there is a method for stopping the condenser, and a condenser used to implement this method. Concerning the water system.

[Background of the invention]

Conventionally, in a condenser configured to store condensed water in a hot well as described above, when the condenser is stopped due to a shutdown of a steam turbine plant, the condensate stored in the hot well is Care must be taken to prevent oxygen from entering the solution. When oxygen dissolves in condensate,
This is because plant structures are oxidized and corroded when the condensate circulates.

For this reason, plants have conventionally been equipped with a deaerator and used to degas, but this increases the cost. In addition, the deaerator is generally installed on top of the plant building, which is structurally unfavorable, and the piping route becomes complicated. Moreover, a pump is also required downstream of the deaerator, which means that an additional pump is required.

Therefore, in steam turbine plants where a deaerator is not installed, the following two shutdown methods have been conventionally used.

FIG. 1 shows a condenser structure and its surrounding system according to a first conventional technique. 2 is a steam condensing section consisting of a group of cooling pipes;
3 is a hot well for storing condensate. In this prior art, the vacuum inside the condenser 1 is completely destroyed when the plant is stopped.

That is, when the plant is shut down, the valve forming the vacuum breaking device 6 is opened to introduce atmospheric air into the condenser. According to this method, by introducing atmospheric air into the cough condenser 1 when the plant is stopped,
Oxygen from the atmosphere dissolves into the condensate stored in the hot well 3, resulting in a maximum dissolved oxygen amount of about 5ooopppb at the time of restart.

In order to supply this condensate to the boiler when restarting the plant, the amount of dissolved oxygen contained in the condensate must be 5 to 10 ppb. For this reason, the air in the condenser 1 is extracted while circulating the condensate to reduce the amount of dissolved oxygen. That is, by operating the condensate pump 4, the condensate in the hot well 3 is transferred to the condenser via the condensate recirculation pipe 21 branched from the condensate pipe 5 at the outlet of the grand condenser 20 and the condensate recirculation valve 22. Return to 1 and cycle. In one direction, the air inside the condenser 1 is removed by the air extraction device 30 through the air extraction pipe 31 to maintain the condenser 1 in a vacuum. In this way, this prior art performs vacuum deaeration by keeping the condenser 1 under vacuum while circulating condensate containing a large amount of dissolved oxygen, and keeps the amount of dissolved oxygen in the condensate below a specified value. It is something to do. However, this method requires a long time for degassing, and generally it takes about 3.75 hours to degas the amount of dissolved oxygen in the condensate to a specified value or less. Therefore, it takes a long time to start the four-turn plan. The linework in Figure 3 shows the change in dissolved oxygen concentration in this case, and since the oxygen concentration at the time of restart is approximately so o o p p'b,
The temperature changes from point A to point A in the figure, and it takes about 225 minutes to reach the specified value, which is the time indicated by a in the figure.

In order to shorten the time until plant operation resumes, using the same basic configuration as shown in Fig. 1, condensate is circulated as shown by the symbol α, and when it enters the condenser 1, it is 7 lashes, thereby increasing the deaeration efficiency. There are ways to increase it.

In this case, heat the inlet near the entrance of the pipe 21 to the condenser 1, which is indicated by the reference numeral 21' in the diagram, so that the condensate is at a temperature slightly higher than the air temperature in the condenser 1. If configured to flash, the effect of flashing will be even greater. However, even if we do this, the change in oxygen concentration will be as shown by line ■ (A to C) in Figure 3, and the time required will be about line B (less than 1 hour), so it is impossible to restart operations immediately. I can't hope.

Another method, B. The second prior art continues to drive the air extraction device 30 even during plant shutdown in the configuration shown in FIG. 1, and also continues to supply auxiliary steam for the shaft seal of the steam turbine. In particular, this method prevents oxygen from dissolving into the condensate stored in the hot well 3 by keeping the pressure in the condenser 1 below a specified degree of vacuum. However, in this method, it is necessary to continue supplying auxiliary steam for the steam turbine shaft seal and to continue driving the air extraction device 30 even when the steam turbine plant is stopped. For this reason, the auxiliary power required for this is large, which is extremely disadvantageous economically.

As mentioned above, in steam turbine plants where a deaerator is not installed, although it is advantageous in terms of cost and structure because a deaerator is not installed, it takes a long time to bring the amount of dissolved oxygen below the specified value. Problems remain, such as the large amount of auxiliary machinery power required during plant shutdown.

[Purpose of the invention]

The present invention was made in view of the above-mentioned circumstances, and its purpose is to improve the condenser stop method and condenser system in steam turbine plants where a deaerator is not installed. To reduce the power of auxiliary equipment while the plant is stopped, and to supply condensed water with a small amount of dissolved oxygen in a short time when restarting the plant, thereby shortening the start-up time of the plant.

[Summary of the invention]

In order to achieve this object, the first invention of the present invention condenses steam from a steam turbine in a steam condensing section, and stores the condensed section condensed in the steam condensing section in a hot well. In the method of stopping the water heater, a partition plate is installed on the top of the hot well to separate the space inside the condenser into a space next to the steam condensing section and a space next to the hot well. Inert gas should be introduced into the space next to the hot well.

A second aspect of the present invention is a condenser configured to condense steam from a steam turbine in a steam condensing section and store condensed water condensed in the steam condensing section in a hot well. In the condenser system, by providing a partition plate above the hot well, the space inside the condenser is divided into the space next to the steam condensing section and the space next to the hot well, and one part of the partition plate The space next to the steam condensing part and the space next to the hot well are connected by a vent mechanism, and the space next to the hot well is provided with an inert gas supply device installed outside the condenser. The structure shall be configured to communicate with

As a result of this configuration, inert gas can be introduced into the space around the hot well during plant shutdown, so that at least a large portion of the condensate stored in the hot well comes into contact with air (WR element). Therefore, almost no oxygen dissolves in the condensate. Therefore, even when restarting the plant, dissolved oxygen can be suppressed to an allowable value in a short time, making it possible to resume operation at an early stage. It also requires less power when restarting. In addition, it is not necessary to constantly bleed air while the plant is stopped, and the power of the auxiliary equipment can be reduced after all.

[Embodiments of the invention]

Below, some embodiments of the present invention will be described with reference to the drawings.

FIGS. 2(a) and 2(b) show a condensate system according to a first embodiment of the present invention. The condenser 1 includes a condensing section 2 that condenses steam from a steam turbine, and a hot well 3 that holds condensed water (condensed water) condensed in the condensing section 2. In addition, this condenser 1 has a partition plate 8 provided above the hot well 3 to divide the space inside the condenser 1 into a space 1a around the steam condensing section and a space 1b around the hot well. It is configured to separate them. When the condenser 1 is stopped due to plant shutdown, an inert gas is introduced into the hot well space 1b thus defined. As a result of introducing an inert gas into the space 1b next to the hot well, the condensate held in the hot well is prevented from coming into contact with air (oxygen), and the amount of dissolved oxygen becomes extremely small.

As the inert gas, nitrogen gas, rare gases such as argon, and helium can be used, but nitrogen is generally used from the viewpoint of cost.

In this condenser 1, the rain space 1a.

1b, a sealing mechanism 9 is provided in a part of the partition plate-8. In the example shown in FIG. 2, the sealing mechanism 9 is a water seal formed by hanging the central portion of the partition plate 8 and bringing it into contact with condensate. Also, the space 1 next to the steam condensing part
A and the hot well side space 1b are connected through a vent mechanism 10. This vent mechanism 10 is for maintaining equal pressure in the rain spaces 1a and ib. In order to introduce the above-mentioned inert gas, the hot well side space 1b is configured to communicate with an inert gas supply device 11 installed outside the condenser 1.

The detailed structure and operation of this embodiment are as follows.

The condenser 1 has a box shape as shown in FIG. 2(b), and has a condensing section 2 at the top and a hot well 3 at the bottom. The condensing unit 2 of this example is composed of a group of cooling pipes, and condenses steam to condensate using cooling water 7. The partition plate 8 includes four partition pieces 81 to 84 that extend slightly downwardly from each side of the condenser 1 toward the center.
Consists of. The central part of this partition plate 8 has a rectangular tube shape and hangs down to form a tube section 85, which forms a water seal by coming into contact with the condensed water in the hot sea urchin v3, and thus forms a seal section 9. .

When the plant is stopped, the condenser 1 is stopped as follows. That is, when the plant is stopped, the atmosphere is introduced into the space 1a next to the steam condensing section through the condenser vacuum break valve 6, and the vacuum is broken. However, at the same time, an inert gas is introduced into the hot well side space 1b from an inert gas supply device 11 installed outside the condenser 1 via a connecting pipe 12 and a valve 13. As mentioned above, nitrogen is generally used as the inert gas.

According to this embodiment, when the condenser vacuum is destroyed and the plant is shut down, the condensate stored in the hot well comes into contact with the atmosphere only by the area of the cylindrical portion 85 forming the seal mechanism 9. The area is so small that it hardly causes any problems.

For example, when the structure of this example is applied to a plant with a steam turbine output of 40 MW class, the area where the condensate stored in the hot well comes into contact with the atmosphere is approximately 0.2 compared to when a condenser without a partition plate is used. % is sufficient. Therefore, the amount of oxygen dissolved in the condensate stored in the hot well can be significantly reduced compared to a condenser with a conventional structure. In addition, in the figure, the cylindrical portion 85 forming the sealing mechanism 9 is shown with a wide opening.
It should be about the same size as the diameter of pipe 5, so at most 0.
．． It only takes about 2 inches.

According to this embodiment, the time required for condensate recirculation, which is performed to reduce the amount of dissolved oxygen contained in condensate to a specified value or less when the plant is restarted, becomes unnecessary or can be significantly shortened. It becomes possible to significantly shorten the startup time.

This effect of this embodiment will be described next with reference to FIGS. 3 to 5.

First, the effect of shortening the time required for degassing will be explained with reference to FIG. Figure 3 shows the relationship between the oxygen concentration at the condenser outlet (vertical axis) and the required time for deaeration (horizontal axis). Line I is the data for the conventional example in Figure 1, as already outlined. Line 2 and line 2 are data when the example of FIG. 1 is combined with flash α during circulation. The line ■ is the data of this example. 40MW each
This is a study of the time required for degassing in a class plant.

As shown in Figure 3, in the conventional condenser structure, the oxygen concentration in the condensate at the start of deaeration is high (approximately 5
ooopppb). When the conventional technology shown in Figure 1 is adopted to reduce this high concentration of oxygen level to a level that allows water to be supplied to the boiler, the oxygen concentration changes as shown from A to B in the figure, and the time required for degassing becomes A and A. It is a long one (approximately 225 minutes). Furthermore, by devising a condensate recirculation method and adopting a method of promoting the deaeration effect using flash α, the time required for deaeration can be shortened by bt;
Previously, no further reduction could be expected.

On the other hand, by adopting the method of introducing nitrogen into the hot well space in the condenser when the plant is stopped, the oxygen concentration in the condensate at the start of degassing can be kept low as shown in 2. Therefore, the time required for degassing is extremely short as shown in C, and therefore the time required for degassing can be significantly shortened.

In this way, according to this embodiment, the time required for deaeration can be significantly shortened compared to the case of using the conventional example shown in FIG. can be significantly reduced.

In addition, in the past, as an alternative method, in order to prevent oxygen from leaking into the condensate in the hot well during plant shutdown, steam was supplied for the steam turbine shaft seal, and an air extraction device (reference numeral 30 in Fig. 1) was used. There is a technology that maintains a vacuum by continuously driving the air pump (shown by . Therefore, it is possible to significantly reduce the power of auxiliary equipment while the plant is stopped.

The effect of reducing operating costs will be explained next with reference to FIGS. 4 and 5.

FIG. 4 shows the required amount of electric power and auxiliary steam when the plant is stopped and restarted when each method is used as a plant operation method. The following methods are available: 1) A conventional vacuum retainer that continues to supply the sealing steam and bleed gas even when the plant is shut down; 2) A conventional vacuum retainer shown in Figure 1 that breaks the vacuum and releases the vacuum when the plant is restarted. This section compares and contrasts the following three methods: one in which air is removed, and one in which the vacuum is broken and nitrogen is introduced and degassed upon restart, as applied in this practical example. In both cases, a 100 MW class combined plant was shut down for 8 hours and then restarted.

As can be understood from Fig. 4, in the conventional technique (2) that continues to maintain the vacuum, power is required for operation for a while from the time when the line is disconnected and the plant is stopped (remaining stoppage time 8 hrg). After that, even while the plant is shut down, steam for the steam turbine shaft seal must flow to prevent oxygen from leaking into the hot well, so fuel is required as shown in diagram A, and electric power is required during operation as shown in diagram B. Kana is required at a much higher rate than in Japan. In addition, in the conventional example of vacuum degassing before startup after the vacuum rises in (2), when the plant is stopped, air is introduced into the condenser, so there is no need for sealing steam. After stopping, as shown in C in the diagram,
No fuel is required.

As for electric power, as shown by D, only a small amount of electric power is required for other parts and is essential even at night. However, as explained in Figure 3, this conventional example takes time to degas, so
Vacuum deaeration must be started about 4 hours before the merging, so the auxiliary boiler should be started 5 hours before the annexation. Therefore, as shown in Figure E, from this point on, the fuel will be drained and the vacuum will start rising for 4 hours. Electric power is required for this purpose (see diagram F).

As mentioned above, both of the conventional techniques (1) and (2) require electricity and fuel, and are expensive.

However, in this embodiment, no fuel is needed once the sealing steam is stopped as shown in Figure G, and it only takes a short time to start up after the vacuum rises, so the auxiliary boiler only needs to be started up after about an hour. From this point on, only fuel is required (see H in the diagram), and the fc power is small as shown by I until the vacuum rises, and the vacuum rise power required for starting and joining is also short.

As a result, compared to the conventional example, this embodiment can significantly reduce costs. Figure 5 shows a conventional example of vacuum maintenance (method ■ above)
Based on this, a comparison was made using the above-mentioned required electric power and auxiliary steam amount as the annual operating cost difference, and the number of startups as a parameter.A study example is shown, assuming 300 startups per year, such as a combined plant that has many startups and stops. By adopting this embodiment, it is possible to save approximately 50 million yen in annual operating costs, and the energy saving effect is extremely large.

In the above estimation, the unit price of electricity is 15 yen/KWH.

The fuel cost for auxiliary steam generation was assumed to be 7 yen/10"Kd. Both prices are standard prices.

Next, another embodiment of the present invention will be described with reference to FIG. In the above example, as shown in FIG. 2, the sealing mechanism is constituted by a cylindrical part 85 hanging from the center of the partition plate 8, whereas in this embodiment, the space 1a and the hot well are connected to the steam condensing part. A sealing mechanism 9 with the space 1b is constructed between the wall of the condenser 1 and portions 8a and 8b hanging down from both sides of the partition plate 8.

In this example, the seal mechanisms 9 are installed at a plurality of locations. In some cases, the entire interior can be configured as such a water seal. The other components are the same as those in the previous example, so detailed explanations will be omitted.

FIG. 7 shows another embodiment according to the invention. This example:
The pressure difference between the pressure in the steam condensing section space 1g and the pressure in the hot well space 1b is measured with a differential pressure gauge 15, and based on the signal 16 of the error pressure gauge 15, the pressure difference is adjusted to zero. , the opening degree of the inert gas supply valve 140 is adjusted.

With this configuration, when the vacuum breaker valve 6 is opened to bring the inside of the condenser 1 to atmospheric pressure when the plant is stopped, the pressure balance between the steam condensing section side space 1a and the hot well side space 1b is quickly balanced. Both pressures can be equalized quickly, and the condenser 1 can be stabilized quickly. This makes it possible to stabilize the level of condensate in the hot well 3 when the plant is stopped. In this example, the other components are the same as the example explained in FIG. 2, so detailed explanation will be omitted.

Although air under atmospheric pressure comes into contact with the condensate in the sealing mechanism 9 to a small extent, each of the above-mentioned sides may be configured to prevent oxygen from being dissolved as much as possible due to this.

An example of such a configuration is shown in FIG. This configuration is applied to the embodiment shown in FIG. 2, and in this example, a shielding plate 40 having a float 42 and a connecting rod 41 is installed in the seal portion 9. One end of this blocking plate 40 is connected to the partitioning plate 8 through a rotating part 43, so that this blocking plate 40 can be freely rotated in the circuit 43.
The space in the seal portion 9 is configured to open and close. During brat operation, the condensate level in the hot well 3 is adjusted such that the shielding plate 40 does not block the seal portion 9.
It is controlled to the level shown by the broken line in FIG. At this level, the float 42 is positioned above this level, thereby pushing up the shielding plate 40 as shown by the broken line, thereby allowing the space to communicate. On the other hand, when the plant is stopped, the condensate level is set to a lower level than during plant operation, as shown by the solid line. As a result, the float 42 is lowered, the shield plate 40 is also lowered, and the lid is closed.
It will be completely blocked. In this way, the shielding plate 40 and the float 42 that opens and closes it depending on the condensate level are provided, and the condensate level in the hot well 3 is kept at a lower level when the plant is stopped than during normal operation. By controlling, this cutoff plate 40 is closed when the plant is stopped.
This blocks the rain space 1a, lb between the steam condensing part and the hot well, and the air that could potentially give oxygen to the condensate is kept in an extremely narrow area between the sealing mechanism 9 and this blocking plate 40. It can be limited only to According to this configuration, the amount of dissolved oxygen is extremely small, the time required for deaeration is further shortened, and it is also advantageous in terms of cost.

Such a blocking structure for suppressing the amount of dissolved oxygen can also be applied to the example shown in FIG. 6 and the example shown in FIG. 7.

Although water seals are used as the seal mechanisms on each side and the seals are configured to open and close automatically depending on the level of condensate, mechanical seals such as valves may also be used as the seal mechanisms. An example of such a configuration is shown in FIG. As schematically shown in the figure, a valve is installed in the center of the partition plate 8, which serves as a sealing mechanism 631, and a water level gauge 9' is separately provided, and this valve is opened and closed according to the water level. It functions as a sealing mechanism 9.

Further, on each side, a water vent may be used as the vent mechanism 10, or a mechanical vent such as a valve may be used.

〔Effect of the invention〕

As described above, according to the present invention, by providing a partition plate above the hot well that holds condensate, the space inside the condenser is divided into the space next to the steam condensing section and the space next to the hot well. Since inert gas is introduced into the space next to the hot well when the water tank is stopped, the amount of oxygen dissolved into the condensate in the hot well can be minimized while the plant is stopped. Auxiliary power can be saved when the plant is stopped,
Moreover, when the plant is restarted, condensate water with a low amount of dissolved oxygen can be supplied in a short time, and the plant startup time can be shortened.

It goes without saying that the present invention is not limited to the illustrated embodiments.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing a conventional condenser. Figure 2 (a
) is a system diagram showing a condenser according to an embodiment of the present invention;
Figure (b) is a schematic perspective view of the condenser of the same example. Figures 3 to 5 explain the effects of the same example. Figure 3 shows the effect of shortening the time required for deaeration, Figure 4 shows the cost saving effect, and Figure 5 shows the cost gain. FIG. 2 is a diagram showing a comparison with a conventional example. 6 to 9 are system diagrams showing other embodiments of the present invention. 1... Condenser, 1a... Space beside the steam condensing section, 1b
...Space next to the hot well, 2. Steam condensing section (cooling pipe group), 6. Vacuum breaker (vacuum breaker valve), 8.
... Partition plate, 9 ... Seal mechanism, lO ... Pressure adjustment vent mechanism, 11 ... Inert gas supply device, 14.
...Inert gas supply adjustment valve, 15...Pressure detection device,
30... Air extraction device, 31... Air extraction piping, 4
0...Break plate. Agent Patent attorney Masami Akimoto 2nd day C○ $2nd (, b) I-\ Reed 3 Figure 4 Prisoner □ □ Itch 5 Ward; Kaya 8 eyes 9th figure

Claims (1)

[Claims] 1. Condensing steam from a steam turbine in a steam condensing section,
In a method for stopping a condenser configured to store condensed water condensed in the steam condensing section in a hot well, a partition plate is provided at the top of the hot well to prevent the internal space of the condenser from steam. Separated into a space next to the condensation section and a space next to the hot well,
A method for stopping a condenser, characterized by introducing an inert gas into a space next to a hot well when the condenser is stopped. 2. The method for stopping a condenser as set forth in claim 1, wherein the partition plate has a water seal or a mechanical seal. 3. Claims 1 or 2, characterized in that a communicating vent mechanism using a water vent or a mechanical vent is provided between the space next to the steam condensing section and the space next to the hot well. How to stop the condenser as described in . -4. The method for stopping a condenser according to any one of claims 1 to 3, characterized in that nitrogen gas is employed as the inert gas. 5. When introducing inert gas into the space next to the hot well,
Claim 1, characterized in that the introduction of inert gas into the space around the hot well is controlled so that the pressures in the space around the steam condensing section and the space around the hot well are equalized.
A method for stopping a condenser according to any one of items 1 to 4. 6. Condensing the steam from the steam turbine in the steam condensing section,
In a condenser system equipped with a condenser configured to store the condensed water condensed in the steam condensing section in a hot well, it is possible to The space is divided into a space next to the steam condensing section and a space next to the hot well, and a sealing mechanism is provided in a part of the partition plate, and a vent mechanism is provided between the space next to the steam condensing section and the space next to the hot well. A condenser system characterized in that the space next to the hot well is connected to an inert gas supply device installed outside the condenser. 7. The condensate system according to claim 6, wherein the sealing mechanism is a water seal or a mechanical seal. 8. The condensate system according to claim 6 or 7, wherein the vent mechanism is a water vent or a mechanical vent. 9. The condensate system according to any one of claims 6 to 8, characterized in that nitrogen gas is employed as the inert gas. 10=) When introducing an inert gas into the space between the hot wells, the inert gas is introduced into the space between the hot wells so that the pressures in the spaces between the vapor condensation section and the spaces between the hot wells are equal. 10. The condensate system according to claim 6, further comprising a control valve. 11. The sealing mechanism is provided with a blocking plate to isolate the space between the steam condensing section and the hot well. Condensate system.