JPS61213594A - Extractor for noncondensing gas of condenser - Google Patents

Abstract

PURPOSE:To maintain a high degree of vacuum even if a cooling water temperature varies in a comperatively wider range by a method wherein a plural number of ejectors having individually different characteristics are arranged in a parallel, besides they are individually connected to a water sealed vacuum pump in a series, which are used individually as a selective system in accordance with the temperature variation of the cooling water. CONSTITUTION:Air ejectors 3, 31 having different types of characteristic properties in suction vacuum rate and also in suction volume rate, are installed at a parallel position, and the respective ejectors are connected in a series to a water-sealed vacuum pump 2. And by the use of the temperature detector 9 for detecting a cooling water temperature, a selective switch 10 permit to actuate for opening and closing operating valves 6, 61, then either ejector 3 or 31 is connected in series to the water-sealed type vacuum pump 2. With this layout, the series operation with the individual ejector and the above pump 2 become in a stable situation, therefore, it is possible to maintain the predetermined degree of vacuum in the condenser 1 within a wider range of the cooling water temperature, as well as to prevent a pump operating efficiency from lowering down and similarly to prevent the pump operation from generating cavitation.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention extracts non-condensable gas in a condenser by cooling and condensing steam containing non-condensable gas by flowing cooling water. This invention relates to a non-condensable gas extraction device for a condenser.

[Prior art and its problems]

A condenser that cools and condenses steam containing noncondensable gases by passing cooling water through it, such as a steam turbine condenser, and condenses the exhaust steam to achieve a predetermined degree of vacuum. edge,
Conventionally, in order to extract the non-condensable gas contained in the exhaust steam from inside the condenser, a device is used in which an ejector driven by air as the non-condensable gas and a water ring vacuum pump are arranged in series. . The prior art will be described below with reference to the drawings.

FIG. 3 is a system diagram of a conventional condenser noncondensable gas extraction device. In Figure 3, cooling water is supplied to condenser 1.
An inlet cooling water pipe and two outlet cooling water pipes are installed to allow water to flow into the interior, and the cooling water pipe is silver.

Exhaust steam of the steam turbine containing air as a non-condensable gas flows into the condenser 1 by the cooling water flowing through the cooling water 21, and is cooled and condensed to condensate. It is discharged to the outside.

The air in the condenser 1 is accompanied by steam, passes through a pipe line by an air-driven ejector 3 (hereinafter referred to as an air ejector), is compressed by the air ejector 3, and is discharged from an outlet 3b, creating a water seal vacuum. guided to pump 2. At this time, the air separated by the separator 4 passes through a conduit provided with an operating valve 6 and is supplied to the air ejector 3 as driving air. The exhaust gas from the air ejector 3 flows into the suction port 2a of the water ring vacuum pump 2 through a pipe n, is compressed to atmospheric pressure, is discharged, and flows into the separator 4 through a pipe n. The cooling water used for the water seal of the water ring vacuum pump 2 rises in temperature and flows into the separator 4 together with the exhaust of the water ring vacuum pump 2.The separator 4 separates the water into air and hot water, and the hot water flows to the bottom. stored.

This hot water passes through a conduit and is distributed to cooling water pipes by a cooler 7.
It is cooled by the cooling water flowing through the cooling water pipe 20a121J branched from 21, and flows through the pipe 5 again as cooling water for the water seal of the water ring vacuum pump 2.

When the internal pressure of the condenser 1 is atmospheric pressure and the inside of the condenser is made into a vacuum from this state, for example when starting a steam turbine, the operating valve 6 is closed and the air ejector 3 is bypassed without being driven. Bypass valve 5 that is easily installed in the pipeline
Open the condenser 1 and operate only the water ring vacuum pump.
Suck out the air inside to create a vacuum. After reaching a predetermined degree of vacuum, the bypass valve 5 is closed by the pressure switch 8 that detects the pressure inside the pipe field, and the operating valve 6 is opened to supply air from the separator 4 and operate the air ejector 3. ,
A predetermined high degree of vacuum is obtained by operating in series with a water ring vacuum pump. This is because a water ring vacuum pump alone cannot achieve a high vacuum at the normal cooling water temperature used in a water ring, so an air ejector is installed on the suction side of the water ring vacuum pump. This is because the suction pressure is increased and the air is compressed in two stages, that is, the air ejector and the water ring pump, thereby obtaining a high degree of vacuum on the suction side of the air ejector, that is, the condenser.

However, the cooling water temperature range for maintaining good performance of the water ring vacuum pump in such noncondensable gas extraction equipment is narrow, and the cooling water temperature of the condenser and water ring vacuum pump is 15% throughout the year. If the temperature changes over a relatively wide range from 0° to 0°, the performance of the water ring vacuum pump may deteriorate or cavitation may occur, especially in areas where the cooling water temperature exceeds 35'O. There is a problem that it becomes difficult to use.

[Purpose of the invention]

In view of the above-mentioned points, the present invention provides a non-condensable gas extraction device for a condenser that can maintain the vacuum of the condenser at a predetermined high degree of vacuum even if the cooling water temperature changes over a relatively wide range. The purpose is to

[Summary of the invention]

According to the present invention, the above object consists of an ejector driven by non-condensable gas passing through a supply pipe, and a vacuum pump that obtains a vacuum by water sealing of cooling water. In a non-condensable gas extraction device for a condenser that extracts the non-condensable gas in the condenser by cooling and condensing steam containing gas to condensate, a plurality of ejectors with different characteristics are arranged in parallel. a valve that can be freely opened and closed provided in each of the pipe lines connected to the ejector and branched from the supply pipe line; a pipe line connecting the plurality of ejectors to the suction port of the vacuum pump; and the cooling water. This is achieved by controlling the valve according to the temperature of the cooling water or the degree of vacuum.

[Embodiments of the invention]

The present invention will be described in detail below based on the drawings.

FIG. 1 is a diagram of the non-condensable gas extraction performance of a condenser according to an embodiment of the present invention. In FIG. 1, the same parts as in the conventional example shown in FIG. 2 are given the same reference numerals. In Fig. 1, a condenser 1, a water ring vacuum pump 2. Separator 4. The operation of obtaining a vacuum in the condenser 1 by means of the air ejector 3 and the water ring vacuum pump 2 connected in series with the air ejector 3 through the system configuration of the bypass valve 5 and the like is the same as that of the prior art, and therefore a description thereof will be omitted. In this embodiment, the air ejector 3 has different characteristics.
1 is installed in parallel with the air ejector 3, and its discharge port 31b
The pipe line 2 connected to the suction port 2a of the water ring vacuum pump 2
2J is connected. Also, the condenser 1's extraction port 1m and the ejector 31's suction port 31a are branched from each other, and the backflow valve 1 is branched.
It is connected by a conduit 23b having a length of 1 m. UnljI
! An operating valve 61 as a valve that can be opened and closed is connected to the air supply port 31c of the air ejector 31 in the conduit 24b branched from the condensable gas supply conduit. Note that the selection switch 10 controls the opening and closing of the operating valve 6.61. Further, a cooling water temperature detector 9 is provided at the inlet cooling water pipe, and a vacuum degree detector 12 is provided at the condenser 1.

When the condenser is made into a vacuum from atmospheric pressure using the above system configuration I, for example, when starting a steam turbine, the operating valves 6 and 61 are closed by the pressure switch 8 and the bypass valve 5 is opened as described above. The condenser is evacuated only by the vacuum pump 2, but when a predetermined degree of vacuum is reached, the bypass valve 5 is closed (rubbed) by the operation of the pressure switch 8.Then, the operating valve is opened to operate the air ejector. However, since the air ejectors 3 and 31 have different characteristics, the selection switch 10 opens only the operating valve of the air ejector to be used. This is done by detecting the vacuum level of the condenser with a vacuum level detector 12, which indicates the vacuum level of the condenser close to the saturated steam pressure.Next, the selection of the air ejector mentioned above will be explained.Figure 2 shows a water ring type vacuum pump. The air ejector 31 is used for high vacuum when the temperature of the cooling water flowing into the vessel 1 is low, and the air ejector 31 is used for low vacuum when the temperature of the cooling water is high.

In FIG. 2, curve A is a characteristic curve of the water-ring vacuum pump when the temperature of the water-sealed cooling water is low, and curve B is a characteristic curve of the water-ring vacuum pump when the temperature of the cooling water is high. The suction flow values shown in the graphs are expressed in terms of weight flow rate, and most of the fluid sucked from the condenser is the air leaking into the vacuum area from the atmosphere 3 and when this air is sucked from the condenser. The weight flow rate does not change significantly depending on the temperature of the cooling water flowing into the condenser.

Next, curve C shows the relationship between the suction flow rate and suction vacuum degree of the air ejector 3 used for high vacuum use, and 11fl#D shows the relationship between the suction flow t of the air ejector 3 and the radiation vacuum degree. Further, the curve E shows the relationship between the suction flow rate and the suction vacuum degree of the air ejector 31 used for low vacuum, and the curve F shows the relationship between the suction flow rate of the air ejector 31 and the radiation vacuum degree. As can be seen from the graph, when the cooling water temperature of the condenser and vacuum pump is low, the suction vacuum degree of the water ring vacuum pump is sufficiently high for high vacuum use, as shown in curve A of the water ring vacuum pump. As shown in the characteristic curve of the ejector 3, the degree of radiation vacuum of the air ejector 3 is sufficiently exceeded. Therefore, the radiation vacuum level discharged by the air ejector 3 is lower than the suction vacuum level of the water ring vacuum pump, and the air ejector and water ring vacuum pump are operated in series in a stable manner. etc. are compressed to atmospheric pressure and discharged from a water ring vacuum pump. Furthermore, when the cooling water temperature is low, the degree of vacuum in the condenser also increases, but there is no problem because the degree of suction vacuum of the ejector 3 for high vacuum is sufficiently low.

However, when the cooling water temperature of the condenser and the water ring vacuum pump is high, the suction performance of the water ring vacuum pump decreases as shown in curve B, and the high vacuum ejector 3 shown in the curve The degree of radiation vacuum becomes lower than that of . In this case, the degree of radiation vacuum discharged by the air ejector 3 is higher than that of the suction vacuum of the water ring pump, so it becomes difficult to compress the air to atmospheric pressure, making stable operation impossible and reducing performance.

In addition, in this case, as the degree of cooling water deviation increases, if the suction A of the water ring vacuum pump decreases below the degree of vacuum indicated by the characteristic curve of the air ejector, the water in the water ring rises and tends to cause cavitation. . At this time, if the air ejector 31 for low vacuum is operated instead of the air ejector 3, the ejector 31
Radiation

Note that although the suction vacuum degree of the air ejector 31 is lower than that of the air ejector 3, this is not a problem because if the cooling water temperature is high, the X vacancy of the condenser will also be low.

Therefore, when the air ejectors 3 and 31 are installed in parallel, the selection of the air ejector to be used is performed using the selection switch 10 using the temperature detector 9 provided in the inlet cooling water pipe hole. In other words, when operating the air ejector and water ring vacuum pump in series, when the cooling water temperature is low, the operating valve 6 is opened and the operating valve 61 is closed, and when the cooling water temperature is high, the operating valve 6 is closed. The air ejector to be used is selected by the selection switch 10 so that the operating valve 61 is closed and the operating valve 61 is opened. In the above case, the bypass operating valve 5 is closed. Note that the temperature of the cooling water that controls the performance of the water ring vacuum pump 2 is the temperature of the cooling water that flows through the pipe 5 cooled by the cooler 7, but the temperature of the cooling water that flows through the cooling water front is determined by the temperature of the cooling water that flows through the pipe 5. Since the temperature is slightly lower than the temperature of the cooling water flowing through the path Z, there is no problem in using the cooling water temperature of the temperature sensor 9 as a signal for opening/closing the operating valve 6.61. Also, since the degree of vacuum in the condenser is a saturated vapor pressure corresponding to a temperature slightly higher than the temperature of the cooling water flowing through the cooling water pipe area, the temperature sensor 9 is installed in the condenser instead of the temperature sensor 9 to measure the cooling water temperature. There is no problem in using the vacuum level of the vacuum level detector 12 as a signal for selecting the operating valve 6.61.

[Effects of the Invention] As is clear from the above description, according to the present invention, a plurality of ejectors having different characteristics of suction vacuum degree and suction flow rate are arranged in parallel, and each ejector is connected to a water ring vacuum pump. The ejector is connected in series to the water ring vacuum pump, and the ejector is selected in response to changes in the suction vacuum degree and suction flow rate characteristics of the water ring vacuum pump due to changes in cooling water temperature. This makes the series operation of the ejector and water ring vacuum pump stable, making it possible to maintain a predetermined degree of vacuum in the condenser over a relatively wide range of cooling water temperatures, and reducing the efficiency and cavitation of the water ring vacuum pump. This has the effect of providing stable performance as a non-condensable gas extraction device with less occurrence of cracks.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of a non-condensable gas extraction device for a condenser according to an embodiment of the present invention, and Fig. 2 is a system diagram of a non-condensable gas extraction device for a condenser according to an embodiment of the present invention. FIG. 3 is a system diagram of a conventional condenser non-condensable gas extraction device. 1: 41 water container, 2: water vacuum pump, 3.31: air ejector, 6+61: valve, 9: temperature/reaction detector, 12: vacuum degree detector. Rho (spirit)

Claims (1)

[Claims] It consists of an ejector that is driven by non-condensable gas passing through a supply pipe, and a vacuum pump that creates a vacuum by water sealing cooling water. A non-condensable gas extraction device for a condenser that extracts the non-condensable gas in the condenser to convert it into water, a plurality of ejectors having different characteristics arranged in parallel, and the supply pipe connected to the ejector. a valve that can be opened and closed on each of the pipes branching from the pipe, a pipe connecting the plurality of ejectors to the suction port of the vacuum pump, and a temperature sensor of the cooling water or the vacuum of the condenser. Equipped with a degree detector,
1. A non-condensable gas extraction device for a condenser, characterized in that the valve is controlled by the temperature of the cooling water or the degree of vacuum.