JPH0255715B2 - - Google Patents

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,
The present invention relates to a condenser equipped with means for degassing condensate and make-up water stored in a hot well and means for controlling its operation.

[Background of the Invention] Condensers for steam turbines are operated in a fairly high vacuum state in order to reduce turbine back pressure and increase efficiency. Turbine exhaust flows into the condenser, and in the process of condensing in the condenser tube nest, it comes into contact with a large amount of steam, and is taken out of the system as a non-condensable gas by an air extraction device, so the dissolved oxygen in the condensate is As is well known, the concentration is controlled to be sufficiently low, and even if relatively high concentration make-up water is introduced, it will be degassed under this operating condition, ultimately suppressing the dissolved oxygen concentration at the condenser outlet. It is.

However, when the plant starts up, the turbine exhaust does not flow into the condenser, and the condensate stored in the hot well at the bottom of the condenser is maintained at room temperature under atmospheric pressure.
The dissolved oxygen concentration is high at around 8000 ppb, and it cannot be used to prevent corrosion of boiler water pipes if it is directly supplied to the boiler.As mentioned above, the specified concentration of general boiler feed water is
It must be rapidly degassed to near 7ppb. Next, while supplying the degassed water to the boiler, even if make-up water flows into the condenser, the dissolved oxygen concentration at the condensate outlet is kept low until the turbine exhaust stably flows into the condenser. It needs to last.

Conventionally, in a condenser equipped with a deaeration function, the condensate in the hot well is recirculated to a spray device installed upstream of the tube nest, and oxygen is released from the liquid interface as the vacuum pressure inside the vessel increases. is discharged from the system using an air extraction device. 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 the time required for degassing is long.
Moreover, the dissolved oxygen concentration of the condensate that reaches the condensate is also unstable. For this reason, it has been considered to take additional measures by introducing heated steam into the condenser. For example, the condensate sprinkled in the condenser is received by a tray or the like and the falling liquid is brought into contact with the heated steam. in this case,
Since the heated steam rapidly attenuates until the temperature corresponds to the vacuum pressure inside the vessel, it is necessary to install trays in multiple stages to provide flow resistance and create atmospheres with different vacuum conditions within the vessel. This has the disadvantage of being large in size despite its deaeration effect. In addition, when operating a condenser, cooling water normally flows through the tube nest, and the air extraction device operates to create a vacuum inside the condenser.
Gradually, it is retained. However, the cooling water of the condenser is
Generally, since seawater is used, the temperature varies seasonally, and it can be extremely cold in the winter. Therefore, as in the conventional example, condensate sprayed by a spray device installed upstream of the tube nest passes through the tube nest at a low temperature, even if additional measures such as introducing heating steam are taken.
The deaeration effect is likely to be inhibited by a drop in liquid temperature.
In other words, when the pressure in the vessel gradually decreases and the temperature of the liquid falls below the saturation temperature corresponding to the pressure, it is inhibited and the pressure in the vessel reaches the pressure corresponding to the temperature of the liquid. At that time, the deaeration effect will proceed. This is also true when introducing make-up water into a condenser without the presence of steam turbine exhaust, and considering that the dissolved oxygen in the make-up water is generally higher than the concentration to be degassed, conventional spray equipment There is also the possibility that the dissolved oxygen concentration at the final condensate outlet cannot be lowered by introducing make-up water.

[Purpose of the invention]

An object of the present invention is to provide a deaeration means for quickly deaerating condensate stored in a condenser at the time of plant startup, and a control means for suppressing the influence of make-up water flowing in at the time of startup. It is to provide equipped condenser.

[Summary of the invention]

In order to achieve the above object, the condenser of the present invention has a continuous flow path that terminates at the outlet of condensate using a partition plate and a ceiling plate in the hot well to flow condensate in one direction. An auxiliary steam injection pipe is installed in the water flow on the upstream side of the flow path to blow steam directly into the condensate to increase the liquid noise, and a deaeration nozzle is installed in the space below the condenser tube nest and above the ceiling board. The condensate once discharged from the condensate outlet is guided to this degassing nozzle and is ejected into the vessel to promote self-evaporation as the vacuum pressure inside the vessel decreases. This is to quickly degas the condensate in the condenser. Furthermore, the make-up water introduced at the time of plant start-up is supplied to the circulation system of the deaeration nozzle,
This suppresses the dissolved oxygen concentration in condensate at the condenser outlet until steam turbine exhaust flows into the condenser.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2, a partition plate 21 and a ceiling plate 22 are constructed inside a hot well 5 at the bottom of the condenser 1, and the partition plate 21 covers the bottom of the hot well as shown in FIG. 2, for example. As in, condensate outlet 8
A continuous condensate flow path is divided into parts and covered with a ceiling plate 22 so as to form a condensate flow path that opens at a position opposite to the condensate outlet 8. The auxiliary steam injection pipe 23 is installed at a position below the hot well water level. And condensate outlet 8
is connected to the condensate system 11, and a circulation system 27 branched from the system 11 on the downstream side of the condensate pump 7 in the system is connected to a deaeration nozzle 28 installed below the tube nest 2 of the condenser. Further, the circulation system 27 includes a make-up water system 41
The make-up water system 41 branches from the make-up water system 13 that leads to the make-up water sprinkler 6 that is operated during normal operation. Here, the control valve 24 in the steam system 25 leading to the auxiliary steam injection pipe 23 may be adjusted according to changes in the internal pressure P, or the control valve 24 may be controlled to introduce auxiliary steam at the time of plant startup using a timer or the like. Can be adjusted by opening.

Next, the operation and deaeration effect will be explained. When starting up the plant, the condensate in the condenser is drawn out by the pump 7 and transferred from the circulation system 26 to a plurality of deaeration nozzles 28.
The condensate is introduced into the vessel, returns to the vessel, passes through the flow path formed by the ceiling plate 22 and the partition plate 21, and is recirculated again through the above-mentioned path from the condensate outlet 30. Then, when the air extraction device 4 operates, the air in the condenser 1 is removed by the system 10 through the extraction port 3 provided in the tube bundle 2, and the pressure is gradually reduced to maintain a vacuum state. During this depressurization process, auxiliary steam is introduced into the injection pipe 23 to increase the condensate temperature in the hot well, and at the same time, the steam injection promotes stirring of the condensate to promote good deaeration. Since the downstream side after passing through is divided by the partition plate 21, the degassed and high temperature condensate is successively pushed to the condensate outlet 8 side without mixing, and then degassed. The nozzle 28 returns to the upstream region of the area where the steam is being injected and the deaeration is repeated. Then, the heated condensate is degassed to some extent from the surface layer on the downstream side after passing this area.
It has the additional effect of replacing the gas component formed by the water surface and the ceiling plate 22 with the generated steam, and further,
Since the heated condensate returning to the degassing nozzle 28 has been depressurized in the vessel, the water sprinkling from the degassing nozzle 28 also induces self-evaporation and additionally increases the degassing rate. That is, in FIG. 3, the internal pressure first decreases according to curve a, and in the process, auxiliary steam is introduced to raise the condensate temperature. This condensate temperature c
If it is made to be slightly higher than the saturation temperature corresponding to the pressure of curve a, from the point when the saturation temperature curve b is reached, as mentioned above, the flow path surface layer in the hot well, then the degassing nozzle At 28, self-evaporation is induced in conjunction with a drop in the pressure inside the vessel, promoting the deaeration effect. At this time, the introduction of auxiliary steam at
As shown in the figure, the pressure P inside the vessel is detected, and the control unit 33 sets the opening timing of the valve 24 to suppress the peak of the condensate temperature as shown by curve c, which in turn prevents a drastic temperature rise inside the vessel. It is better to suppress Alternatively, if a pressure drop within the vessel can be obtained, the opening timing of the valve 24 may be set in advance using a timer or the like. Then, the settings are changed according to seasonal changes in water temperature.
The apex can also be adjusted to a constant value. Once this peak is exceeded, deaeration progresses rapidly, and eventually, as the internal pressure becomes constant, the temperature reaches equilibrium with that pressure, and the dissolved oxygen concentration of the condensate can be lowered in a short time. Next, the condensate with a low concentration is transferred to the condensate system 11.
All you have to do is open the valve 12 and start supplying water to the boiler. When new make-up water is introduced into the vessel following this water supply, it is supplied from the system 41 to the circulation system 27, sprayed into the vessel by the deaeration nozzle 28, and deaerated as the pressure drops. This action and the degassing action in the region of the auxiliary steam injection pipe 23 located downstream thereof suppress the increase in the condensate concentration. This condition is maintained until the steam turbine exhaust has steadily flowed into the vessel, and then valves 42 and 14 are switched to introduce make-up water from a conventional spray system to maintain dissolved oxygen at the condenser outlet.

FIG. 4 shows another embodiment of the present invention, in which a heater 50 is provided in the circulation system 27, and auxiliary steam etc. can be supplied from the condensate of the circulation system 27 or from the system 41 by opening the valve 52. Increase the temperature of the make-up water. Then, the pressure P in the container is detected so as to be at the saturation temperature corresponding to the pressure in the container or several degrees higher than that, and the amount of heating is adjusted by the control section 34 to keep the liquid temperature T constant. As a result, firstly, the degassing action of the degassing nozzle 28 is promoted without changing the degassing performance at the time of plant startup, and the load on the injection pipe 23 may be reduced accordingly. Furthermore, even if the new make-up water is at a low temperature, a good deaeration effect can be maintained, and changes in concentration when the make-up water is introduced can be sufficiently suppressed. Here, the effect is the same even if the heating means in the circulation system 27 is brought into contact with steam.

〔Effect of the invention〕

According to the present invention, the release of dissolved oxygen from the liquid phase to the gas phase is promoted, and low concentration condensate can be rapidly degassed. Next, even if makeup water with a relatively high concentration is introduced, the steam turbine operates without increasing the concentration of condensate, and the concentration of water fed to the boiler is suppressed to the point where the exhaust gas flows into the boiler, allowing steady operation. can be quickly transitioned to

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a condenser for a power plant according to an embodiment of the present invention and its deaeration system, FIG. 2 is a configuration diagram of the lower part of the hot well in FIG. 1, and FIG. An explanatory diagram showing an example of a state change in
FIG. 4 is a condenser configuration and its deaeration system diagram according to another embodiment of the present invention. 5...hotwell, 21...partition plate, 22...
...Ceiling board, 23...Auxiliary steam injection pipe.

Claims (1)

[Claims] 1. A condenser, a condensate system that supplies condensate in this condenser to a boiler by a pump, and a condenser that returns condensate branched from this condensate system to the condenser. A system comprising a water circulation system and a deaeration nozzle for ejecting condensate in the condensate circulation system to degas the condensate, wherein a partition plate and a ceiling plate are provided in a hot well of the condenser. a continuous flow path ending at the outlet of the condensate; an auxiliary steam injection pipe is provided in the water flow on the upstream side of the flow path; A condenser with a degassing mechanism, characterized in that the degassing nozzle is provided in an upper space. 2. A condenser with a degassing mechanism according to claim 1, characterized in that a make-up water system is connected to the condensate circulation system leading to the degassing nozzle, and a heater is provided downstream thereof. . 3. In claim 1 or 2, the amount of steam supplied to the auxiliary steam injection pipe located in the flow path in the hotwell of the condenser in response to pressure changes in the condenser. A condenser with a degassing mechanism, characterized in that it is provided with a control means for controlling.