JPS63247591A - Air leak detector - Google Patents

Abstract

PURPOSE:To assist the operation under conditions that the condenser vacuum level becomes lower by alerting the operator to air leak into the condenser by sensing the air delivery rate from an aftercooler, which is then compared with the computed air delivery rate based on the operation load. CONSTITUTION:The air delivered from an aftercooler enters into a delivered air tank 1, and the delivery rate is detected by an orifice 2 disposed in the delivery air tank 1. The power generator 5 is detected by a power generator load sensor 6, and the rate of air leak relative to the power generator load is determined by a function generator 11. A comparator 8 compares the allowable air delivery rate set in advance by an allowable air delivery rate setting unit with the value determined by a deviation operator, and, if the air leakage rate is great and the vacuum level in a condenser is below the specification, a warning is set off by a warning generator 10 to alert the operator.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an air leak detection device in a steam injection air ejector for maintaining a vacuum in a condenser in a power plant.

[Conventional technology]

As described in JP-A-61-119993 [Vacuum degree control device for main condenser], as an example of a device that does not discharge air discharged from an aftercooler into the atmosphere, a condenser is installed to prevent the vacuum height of the condenser. One example is a device that returns part of the air discharged from the aftercooler to the condenser so as to keep the vacuum level constant. However, like this device, there is no other diagnostic device similar to an air leakage detection device that causes a decrease in the degree of vacuum in a condenser.

FIG. 2 shows a system diagram of a typical conventional steam injection ejector.

Air and gas from the condenser 1 pass through an extraction air system 3, are extracted by the first stage ejector 2, and enter the cooler together with driving steam whose pressure is controlled to be constant by a pressure regulator. The cooler is divided into an intercooler 4 and an aftercooler 5, and what is discharged from the first stage ejector 3 enters the intercooler 4. The air and gases separated by the intercooler 4 are extracted by the second stage ejector 6.

It enters the aftercooler 5 together with the driving steam. Similarly to the intercooler 4, in the aftercooler 5, steam is condensed using cooling water, drain is collected in a recovery tank, and air and gases are discharged to the atmosphere. The decrease in condenser vacuum level is detected by PI3, but it is detected as "condenser vacuum decrease due to air leakage".
It cannot be detected as such.

In the figure, 7 is a cooling water line, and 9 is a driving steam pressure controller.

[Problem that the invention seeks to solve]

In the conventional technology, when the degree of vacuum in the condenser decreases, an alarm is generated when the degree of vacuum falls below a specified value, and when the degree of vacuum decreases further, the system causes the turbine to trip.

The cause of the decrease in the vacuum level of the condenser is abnormal air leakage into the condenser (open valve, improper closing of the valve, defective valve).

Joint surface abnormality), condensate system abnormality (condensate pump abnormality, high condenser water level), steam injection ejector performance abnormality (low working steam pressure, low cooling water volume, high cooler drain water level), circulating water system abnormality (circulating water pump abnormality, Screen system abnormality, condenser abnormality)
Many factors can be cited, such as abnormalities in the gland steam system (abnormal gland steam pressure, abnormal gland steam pressure regulator, abnormal labyrinth seal, and abnormal gland steam exhaust fan).

(This factor can be divided into many more factors by subdivision.) When the "condenser vacuum level drop" alarm occurs, the operator must identify the cause of the condenser vacuum level drop in order to take countermeasures. It is necessary to confirm for each factor whether it is caused by If the cause of the condenser vacuum level drop is due to air leakage into the condenser, the operator should check the opening/closing lamp on the panel or at the site for valve opening failure to determine air leakage. ing. However, air leakage from joint surfaces and air leakage due to valve closure failure can be determined by measuring the vacuum rise time when the turbine is started and the vacuum fall time when the turbine is stopped. It was not possible to determine that the cause of the decrease in the vacuum level of the vessel was air leakage due to failure of the joint surface or valve to close.

The purpose of the present invention is to provide operational support when the vacuum level of the condenser decreases by notifying operators when the cause of the condenser vacuum decrease is air leakage during plant operation. be.

[Means for solving problems]

The above purpose is that the extracted air from the condenser enters the cooler together with driving steam, but the air discharged from the aftercooler is not discharged to the atmosphere, but is placed in a discharge air tank, and the amount of discharged air is detected by an orifice. This is achieved by comparing the amount of discharged air calculated based on the load during operation and notifying the operator of air leakage into the condenser.

[Effect]

In order to prevent pulsation of the discharge air flow rate, the discharge air from the aftercooler, which was conventionally released into the atmosphere, is received in a discharge air tank, and the discharge air flow rate is detected by an orifice provided in the discharge air tank. The driving steam pressure of the ejector is controlled to be constant by a pressure regulator, and the relationship between the driving steam pressure and the suction vacuum is as shown in FIG. 3. When the driving steam pressure is constant, the suction vacuum is constant. In addition, when the condenser is operated at a constant vacuum, if the amount of leakage air increases due to valve opening or joint surface abnormality, the suction vacuum will decrease from the relationship between the suction air amount and the suction vacuum shown in Figure 4. According to
The amount of intake air increases, and the amount of air discharged from the aftercooler increases. Additionally, as a function of the generator load, the turbine steam displacement and the amount of ground steam leaking to the condenser are uniquely determined, and the amount of steam discharged without being condensed by the intercooler and aftercooler is also determined. .

The performance of the intercooler and aftercooler is constant and is given as a function of the generator load.

Therefore, the amount of air discharged from the after-condenser is detected, and at the same time, it is compared with the amount of air discharged calculated from the condenser vacuum degree 2 generator output, and the specified value of the large leakage air amount of the condenser for the load is determined in advance. If the specified value is exceeded, an alarm will alert the operator that the condenser vacuum level has decreased due to air leakage.
to announce.

〔Example〕

FIG. 1 shows a steam injection type air leak detection device of the present invention. The discharge flow rate from the aftercooler enters the discharge air tank 7, and the flow rate is detected by the orifice 2 installed in the discharge air tank. Further, the generator load 5 is detected by the generator load detector 6, and the amount of air leakage with respect to the generator load is detected by the function generator 11.
The deviation between the actual measurement value obtained by the flow rate transmitter 3 and the flow rate obtained by the function generator 6 is determined by the deviation calculator 7. In advance, the comparator 8 compares the allowable discharge air amount set by the allowable discharge air amount setting device with the value obtained by the deviation calculator, and determines whether the leakage air amount is large and the condenser vacuum degree. When the value is below the specified value, the alarm generator 10 issues an alarm and notifies the operator.

Operators who observe a decrease in condenser vacuum during plant operation must check the possible causes individually.
If the amount of air leaking into the condenser is confirmed by the alarm, Operator 5 should immediately take the following actions.

(1) Regarding the valves in contact with the condenser and the atmosphere, confirm that there are no blockage defects in the valve release valves.

(2) If (1) is confirmed, there is air leakage from the joint surface, so lower the generator output and try to maintain a vacuum.

(3) If it is impossible to maintain the vacuum according to (2) and the turbine trips, the air leakage location can be inspected and maintenance can be carried out quickly.

〔Effect of the invention〕

According to the present invention, in a power generation plant that maintains the degree of vacuum in the condenser, it is possible to detect the amount of air leaking into the condenser, and it is effective as one of the abnormal operation support systems.

[Brief explanation of drawings]

Fig. 1 is a system diagram of an air leak detection device in a steam injection air ejector according to an embodiment of the present invention, Fig. 2 is a schematic diagram of a conventional steam injection type ejector, and Figs. FIG. 3 is a diagram showing extractor performance.乎 l Kuni Haya 2 Mouth S

Claims (1)

[Claims] 1. Air extraction method using a steam injection air ejector,
In a power generation plant that maintains a vacuum in a condenser, means for detecting the flow rate of air discharged from an after-condenser, means for comparing the amount of discharged air calculated based on the generator load during operation, and the condenser An air leak detection device characterized by comprising means for notifying an operator of air leakage into the air.