JPS6057191A - Condenser having deaerating means - Google Patents

Abstract

PURPOSE:To shorten the deaerating time at the time of a startup so as to improve the economy of a power generating plant that frequently repeats the startup and shutdown by an arrangement in which the condensate in a condenser is recirculated, and the interior of a hot well is divided to enhance the fluidity with the heating steam pipe suitably disposed in the water flow. CONSTITUTION:As the interior of a condensor 1 is maintained in a vacuum condition, the sprinkled condensate is deaerated in the vacuum and is gathered in a passage 50a as it drops from pipe nests 15 to a ceiling plate 42. The condensate in a hot well, when violently contacted by the steam which is inducted from an auxiliary boiler etc. and is jetted out of a heating steam pipe 40a, is boiled to separatee gaseous components in it. The deaerated condensate does not mix with the high-concentration condensate that is flowing down the ceiling plate 42, and the condensate with the lowest concentration drips into a passage 50b. The condensate that flows in the downstream without being deaerated is prevented from mixing with the condensate that has been deaerated as it is separated by a separator 41, whereby, by recirculating the condensate the deaerating time can be shortened.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a condenser for a steam turbine, and in particular, deaerates condensate in the condenser at plant start-up, and supplies a low amount of dissolved oxygen to a boiler, etc. The present invention relates to a condenser equipped with a degassing means suitable for supplying water.

[Background of the invention]

Since steam turbine condensers are operated in a fairly high vacuum state to reduce turbine back pressure and increase efficiency, they have the ability to remove dissolved oxygen from condensate. During plant operation, turbine exhaust gas flows into the condenser, and the condensed water comes into contact with a large amount of steam and is taken out of the system as non-condensable gas by an air extraction device, so that dissolved water in the condensate Oxygen concentration is suppressed to a sufficiently low level. Furthermore, it is well known that even if relatively high concentration make-up water is supplied, it is degassed as described above during plant operation.

However, at the time of plant start-up, the condensate stored in the condenser hotwell is initially stored under atmospheric pressure and room temperature, and the dissolved oxygen concentration is high at around 5ooopppb, so it is directly used as boiler feed water. In order to supply boiler water, pitting may occur in the boiler water pipes, causing an accident, making it unusable5.In addition, many power plants start and stop frequently in response to the gradual reduction in power, and as mentioned above, The steam turbine must be restarted without the presence of exhaust gas, and in order to prevent corrosion of the boiler water pipes and reduce losses during startup, the dissolved oxygen in the boiler feed water must be quickly removed to near the standard value of 7 ppb. You are required to care.

Conventionally, in an example of a condenser equipped with a deaeration function, as shown in FIG. Connect the condensate pipe 6 and condensate recirculation pipe 5 (not shown).
Then, the water is supplied to the spray device 14 and water is sprinkled into the container, flowing down the tube nest 15 and returning to the hot well 17 again. Then, the vacuum pump 11 is operated to maintain the inside of the vessel in a vacuum state, and while the above steps are repeated, the oxygen released from the liquid interface is discharged to the outside of the system via the air extraction pipe 16. However, this is simply due to movement from the liquid interface to the gas phase side, and is easily affected by the pressure and liquid temperature inside the vessel, and it takes several hours to obtain the necessary degassed condensate. It has the disadvantage of being unstable, such as not being able to lower the dissolved oxygen in the condensate. For this purpose, it has been considered to take additional measures by introducing heated steam into the lower part of the condenser. For example, a tray or the like is used to receive the condensate sprinkled in the condenser and to bring the falling liquid into contact with the heated steam. However, 1 - When heated steam is introduced into a vacuum, such as in a condenser, the steam rapidly attenuates and reaches a temperature equivalent to the pressure inside the vessel, so it cannot be heated sufficiently and the degassing effect cannot be achieved. do not have. In such cases, complex structural members must be installed in the narrow vessel, such as installing trays in multiple tiers to provide flow resistance and prolonging the gas-liquid contact time with different vacuum conditions within the vessel. , the deaeration efficiency is poor and the disadvantage is that it becomes a dog house.

A method of simply blowing heated steam into the condensate has also been considered. For example, in FIG. 2 extracted from Japanese Patent Application Laid-open No. 53-72903, a bottom plate 18 is provided which isolates the degassing function from the hot well 17, and between them, water sprinklers 25 and 26, an overflow pipe 27, and a limb pipe 27 are provided. This is shown to be carried out using a degassing device 24 constructed of a heated steam injection pipe 20 provided at the top.

However, in the re-deaerator-24, water is sprayed at 25°2.
A pressure difference is created by 6, and further 1. Oxygen released by steam injection in the condensate passes through the ivy atmosphere with a rise in pressure. By mixing with the unaerated condensate and flowing into the hot well, and by mixing the degassed condensate with the condensate stored in the hot well before the plant starts up, the result shown in Figure 1 is generated. Although it is effective, it cannot shorten the deaeration time at plant start-up. Furthermore, when the plant is started up without the presence of steam turbine exhaust, installing a member in the vessel that causes such a pressure difference or pressure increase has the disadvantage of prolonging the deaeration time.

[Purpose of the invention]

An object of the present invention is to completely overcome the drawbacks of the prior art, and to provide a deaeration means capable of quickly deaeration of condensate stored in a condenser at the time of plant start-up, thereby shortening the power plant start-up time. The purpose of the present invention is to provide a condenser structure that has the following characteristics.

[Summary of the invention]

The present invention has been developed in the hot well of the condenser, taking into account that dissolved oxygen in the liquid can be removed by blowing steam directly into the liquid, and that the deaeration effect differs greatly depending on the condenser structure and steam introduction means. By partitioning the condensate stored in the hot well, the stored condensate flows uniformly, and a steam injection part is formed in a part of the circulating water flow to increase steam heat exchange and water flow agitation. By suppressing the mixing of condensate before being degassed or condensate with high oxygen concentration stored in the hot well and degassed condensate with low oxygen concentration, there is no need for turbine exhaust at the time of plant startup. This is to quickly degas the condensate in the condenser.

Embodiments of the present invention will be described below with reference to the drawings.

In Figure 3, the hot well 1 located at the bottom of the condenser 1
A partition plate 41 and a ceiling plate 42 are configured inside the hot well 7, and the partition plate 41 forms continuous condensate flow paths 50a and 50b with the bottom of the hot well facing the condensate outlet 30 as shown in FIG. split it and install it vertically on the bottom of the hotwell. The upper part of the partition plate 41 is covered with the ceiling plate 42, and the condensate channel 5 opens the ceiling plate at a position opposite to the condenser 1130.
Form 0a. Further, the opened heating steam pipe 40a is installed in the condensate flow path 50a and below the hot well water level, and the flow path is installed in the condensate flow path 50b whose one end is covered with the ceiling plate 42. Constructed toward the entrance.

Next, the operation and deaeration effect will be explained. When starting up the plant, the condensate in the hot well 17 is drawn out by the pump 4 and introduced from the condensate piping 6 into the condensate circulation piping 5, where it is sprayed into the spray device 14.
Water is sprinkled into the container. At this time, the vacuum pump 11 is activated, and the air inside the condenser L is expelled from the system, reduced in pressure, and maintained in a vacuum state. 15 onto the ceiling plate 42, flows down the upper surface thereof, and collects in the flow path 50a. Then, the condensate in the hot well is produced by first introducing steam obtained from the auxiliary boiler 2 or another plant from the steam pipe 21a, and then
Heat is transferred through intense contact with the steam blown into the condensate from 0a, resulting in a boiling state, separating the gas components in the condensate, and diffusing with some steam from the condensate water surface into the condenser. The air is then discharged out of the system through the air extraction pipe 16. and,
The degassed condensate immediately flows down on the ceiling plate 42, so that the condensate with the lowest concentration is
It sequentially flows down into the covered channel 50b.

That is, the inside of the flow path always presents a water flow toward the condensate outlet 30, and since the steam injection pipe 40a is installed in the middle of the flow, stirring of the condensate by steam injection is promoted, resulting in high thermal efficiency. Successful deaeration can be achieved by ensuring that condensate passes through the area. Furthermore, on the downstream side after passing this area, the condensate that has been slightly degassed from the surface layer but has not yet been degassed is divided by the partition plate 41, so that the degassed condensate is sequentially condensed. Since the water is forced to the outlet 30 side without being mixed, the condensate is recirculated and degassed in a short time. Therefore, it is sufficient to repeat this process and, when the dissolved oxygen in the condensate has sufficiently decreased, switch the condensate piping to the boiler side and start water supply.

5 and 6 show other embodiments having features of the invention. A heating steam pipe 40b is constructed below the condensate water surface of the condensate flow path 50b surrounded by the partition plate 41 and the ceiling plate 42, and the steam introduced from the steam pipe 21b is blown into the condensate water flow, as described above. The water vapor generated in that area and the gas components that escaped have the additional effect of displacing the gas components in the space formed by the water surface and the ceiling plate 42, reducing the concentration of condensate to a low concentration. As the process progresses, its self-cleaning action will drive out the gas in the space and suppress the re-dissolution of oxygen. In addition, a heated steam injection pipe 408 provided on the flow path inlet side
By arranging these appropriately, the deaeration time can be additionally shortened.

As described above, according to the present invention, the condensate in the condenser is recirculated, the inside of the hot well is divided and fluidized, and the heating steam pipe is appropriately placed in the water flow. Degassing time at startup can be shortened. In addition, before the turbine exhaust gas flows in, that is, during the water sb process of the boiler, make-up water is supplied into the condenser by maintaining the water level (9) in the condenser and gradually increasing the condensation water into the condenser. Since both water and make-up water can be degassed, water can be consistently and continuously supplied to the boiler at plant start-up, reducing start-up time. Therefore, it is suitable for improving economic efficiency in power generation plants that are frequently started and stopped.

[Brief explanation of drawings]

Figure 1 is a condenser system diagram with a conventional degassing function;
Fig. 2 shows a structural diagram of a condenser equipped with a conventionally published deaeration device, Fig. 3 shows an internal structural diagram of a condenser constituting an embodiment of the present invention, and Fig. This is a sectional view taken along the line A-A. Further, FIG. 5 is a diagram showing the internal structure of a condenser constructed in another embodiment of the present invention, and FIG. 6 is a sectional view taken along the line BB in FIG. 5. DESCRIPTION OF SYMBOLS 1... Condenser, 4... Pump, 5... Condensate recirculation piping, 6... Condensate piping, 11... Vacuum pump, 14
... Spray device, 15... Tube nest, 16... Air extraction tube, 17... Hot well, 21a, 21b...
・Steam piping, 40a. 40b... Heating steam injection pipe, 41... Partition plate, 42
...Ceiling board, 50a, 50b...Condensate channel. Agent Akio Takahashi Patent Attorney B Momme Tsu 2 Ri R Fu L Otsu J Hayabusa 4 - Ro Fue S Notebook 6 Figure 1 Page 1 Continued 0 Inventor Yoshikuni Oshima 3-1-1 Saiwaimachi, Hitachi City Stock Company Hitachi Ltd. Hitachi Factory -ζsuζ-

Claims (1)

[Claims] 1. In a condenser for a steam turbine, a partition plate is provided inside the botwell of the condenser and extends vertically upward from the bottom of the hotwell to form a continuous condensate condensate outlet. The condensate flow path is formed and divided and arranged, most of the upper part of the condensate flow path is covered with a ceiling plate, and the condensate flowing down on the ceiling plate is introduced into one of the condensate flow paths to be released, and the condensate flow path is Under the surface of the water held within,
Moreover, a condenser equipped with a degassing means is characterized in that a steam injection pipe is provided in the water flow at the entrance of the condensate flow path covered by the ceiling plate. 2. Claim 1 - C1 A condenser equipped with a degassing means, characterized in that the steam injection pipe is provided in the condensate mt of a condensate flow path covered with a ceiling plate. .