JPS58110986A - Condenser system - Google Patents

Abstract

PURPOSE:To prevent lowering in the output of a condenser which is divided into two or more bodies when it is operated without supplying water into one body thereof by an arrangement wherein the degree of vaccum of condenser is lowered to reduce the pressure differential between the bodies under such an operating condition. CONSTITUTION:In case the supply of water through a condenser body A2a is stopped, the load of the plant is reduced to a specified value and then a cooling water inlet valve 10a and cooling water outlet valve 11a are fully closed. Further, in order to prevent high temperature steam from an air extraction main pipe 7a from being drawn into the condenser body A2a, a valve 15a installed in the air extraction pipe is usually fully closed. Under this condition, a valve opening regulating means 24 is actuated, and if the minimum vaccum preset value is set, for example, to 680mm.Hg, then the degree of opening of an air extractor inlet valve 16 is reduced until the degree of vacuum of 680mm.Hg is obtained in the condenser in which water supply is stopped, whereby reducing the amount of air to be extracted. Thereafter, the output of the plant can be increased under the condition the deviation in the degree of vacuum between the condenser bodies or the deviation in water level between the hot well water level detectors 25a, 25b and 25c is within a specified value.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a condenser system for a power plant, and more particularly to a method for operating an air extraction system to ensure a vacuum level in a condenser.

The condenser system of a conventional plant, its operating method, and problems will be explained using Figure 1.

Steam from a steam generator (not shown) of the power plant works in a steam turbine 1, enters condensate IS2, is condensed in a cooling pipe set 5, and is sent to the steam generator again as condensate. On the other hand, the cooling water passed through the cooling pipe set is supplied by the circulating water pump 9, heat exchanged in the pipe set 5, and then discharged to the water outlet 13. The body of the condenser 2 is usually divided into 28 pils or three bodies, and a pressure equalizing duct 8 is installed between the bodies for the purpose of equalizing the pressure.

In such a divided condenser 2, if seawater leaks due to damage or cracks in the cooling pipe nest 5 or water chamber 4 (6), the water flow to the condenser 1 body must be stopped. Then, the remaining two cylinders are operated continuously, and the turbine exhaust gas from the first cylinder where the water flow is stopped passes through the pressure equalization duct 8 and enters the cylinder in which the water is flowing and is condensed.

However, in such an operation in which the water flow to the l-shell is stopped, a pressure difference occurs between each shell, resulting in a turbine trip due to deterioration of the vacuum level of the condenser 2, an alarm due to the water level deviation hole in the hot well 3, or a trip on the condensate pump 30. , it will be necessary to drastically reduce the output of the plant, resulting in a decrease in the operating rate.

An object of the present invention is to eliminate the above-mentioned operational disadvantages when water flow to one body of the condenser is stopped, and to provide a method and control device for operating a condenser system with high reliability and availability.

The feature of the present invention is that when the condenser is divided into two or more cylinders (four tube nests) and one cylinder (t or one tube nest) of nine condensers is operated with water flow stopped, the condenser 2 drains. The objective is to minimize the pressure difference between the can bodies by reducing the extraction capacity of the air extractor for extracting condensed gas and degrading the degree of vacuum in the condenser.

In other words, as shown in Figure 2, the pressure loss (differential pressure between shells) in the pressure equalizing duct increases by the square ratio of the flow rate passing through the duct, but by deteriorating the degree of vacuum, it changes from the high vacuum daily differential pressure curve 31 to the low vacuum Move to the time differential pressure surface @33. This can be understood from the following equation, where ΔP: Duct pressure loss coefficient: Duct pressure loss coefficient V: Duct flow velocity G: Duct weight flow A: Duct cross-sectional area V: Steam specific volume. Since it is proportional, the differential pressure can be reduced by lowering the accuracy.

By adopting this operating method, water flow to one body of the condenser is stopped during maintenance of pipe leaks or when one circulation water pump (usually three) is stopped.

Since the differential pressure between the condenser bodies can be minimized without significantly reducing the plant load, the plant operation rate will be improved.

In addition, by installing a device that detects the pressure of the condenser and controls the performance of the air extractor, it is possible to prevent main turbine trips and alarms, as well as condensate pump trips and alarms, improving reliability. Twist. In addition, it is possible to simplify the operation when water flow to the first cylinder is stopped.

One embodiment of the present invention will be explained with reference to FIG. here,
The case where the condenser is divided into three cylinders will be taken as an example, but the same effect can be obtained when the condenser is divided into two cylinders.

The difference from conventional condenser systems is that a pressure selection device is installed to select the minimum vacuum level (maximum pressure) of the pressure detectors installed on each side of the condenser, and this minimum vacuum level is controlled to the set vacuum level. In order to achieve this, a valve opening degree adjusting device 24 is provided to adjust the opening degree of the air extractor artificial valve 16. These devices have the same effect whether the air extractor is a steam air extractor or a mechanical vacuum pump.

Here, Fusui i! ! The operating method will be described below, taking as an example the case of No. 2, where water flow is stopped in one shell (here, water flow is stopped in the condenser shell (A) 2M).

When stopping water flow to the condenser body (42a), after lowering the plant load to the specified value, open the cooling water valve 1 of the cooling pipe nest 5a.
0a and the cooling water outlet valve 11a are fully closed. Further, the air extraction piping valve 15a is normally fully closed to prevent high temperature steam from being sucked in from the air extraction main pipe 7a.

In this state, if the valve opening adjustment device 24 is operated and the minimum vacuum set value is set to, for example, 680 smHg vacuum (the set value with some margin since the turbine exhaust alarm vacuum is 660 smHg vacuum), the normal Vacuum level when water is stopped is 680w
The amount of air extracted is reduced by throttling the air extractor artificial valve 16 until a Hg vacuum is achieved. After this, detect the vacuum degree deviation between the condenser shell or the hot well water level of the can body 6253~25C
Increase the plant output as long as the deviation is within the specified value.

By adopting such an operating method and device, even when the water flow to one body of the condenser is stopped, the plant can be operated without significantly reducing the plant output, improving the operating rate and Ik! This results in improved rust resistance. In addition, it is possible to improve reliability by preventing alarms or tripping of equipment during operation when water flow is stopped in the first cylinder.

FIG. 4 shows another embodiment of the invention. The difference from the embodiment shown in FIG. 3 is that this embodiment is applicable only to a steam type air extractor.

A general steam type air extractor reduces the pressure of steam from the main steam supply pipe 22 to a specified pressure by a pressure regulating valve 27, and
It is used as driving steam for the stage steam ejector 17 and the second stage steam ejector 19 to extract non-condensable gas in the condenser. The mixed steam in the first stage steam type ejector 17 is condensed in the intercooler 218, and the residual gas is guided to the exhaust treatment equipment by the second stage ejector. Here, the minimum degree of vacuum detected by the pressure detection ff1I21a to 21C is set to a specified pressure (for example, 680-Hg vacuum).

□ Pressure reducing valve adjusting device 2 that controls the outlet pressure of the pressure regulating valve 27
Install 6.

With such equipment, air extraction performance can be changed by controlling the pressure regulating valve 27 and changing the driving steam pressure of the steam type ejector during the condensate iS1 cylinder water flow stop operation.
The same effect as the embodiment shown in FIG. 3 can be obtained.

Further, according to this method, the drive steam of the steam ejector is not flown unnecessarily, resulting in an improvement in plant efficiency. In addition, less steam flows into the exhaust treatment equipment, resulting in a reduction in treatment costs.

According to the present invention, it is possible to continuously operate a plant with one condenser shell (or one tube nest) stopped from flowing water without significantly reducing the output, resulting in improved operating efficiency and economic efficiency. Specifically, when water flow to one of the three condenser shells is stopped, 20% of the rating
Although it is necessary to reduce the output to ~30%, by employing the present invention, the output can be increased by 50% to 70%.

In addition, by employing one device, it is possible to prevent alarms due to a decrease in the degree of vacuum, or problems such as turbine tripping and water pump tripping, which improves the fg axis of the plant and simplifies operation in a single device operating state.

[Brief explanation of the drawing]

Figure 1 is a diagram explaining a conventional condenser system, Figure 2 is a diagram explaining differential pressure characteristics of a pressure equalizing duct, Figure 3 is a diagram showing an embodiment of the present invention, and Figure 4 is a diagram showing the present invention. It is a figure which shows another Example of.

Claims (1)

[Claims] 1. Condensing steam turbine exhaust steam of a power generation plant 2.
A condenser system consisting of a condenser divided into nine or more bodies, a cooling water system that supplies cooling water to a cooling pipe nest that condenses steam, and an air extraction system that extracts non-condensable gas from the condenser. In the way you drive. In operating conditions where cooling water is not flowing through some tubes of the condenser, the opening of the valve at the air extraction device or vacuum pump inlet is restricted to limit the air extraction capacity and deteriorate the vacuum level of the condenser. It is characterized by minimizing the differential pressure between the cylinders. How to operate a condenser system. A pressure sensor installed in the can body of the can body monitors the pressure in the can body, and in order to reduce the pressure in the can body to a specified value, the opening degree of the air extractor artificial valve is limited. A method of operating a condenser system according to claim 1, characterized in that: The pressure sensor installed in the can body of the condenser monitors the pressure in the can body, and in order to reduce the pressure in the can body to a specified value, the steam air extraction 6's drive IIh# air supply valve is opened. A method for operating a condenser system according to claim 1fj.