JPH03267690A - Vacuum adjusting device of condenser - Google Patents

Abstract

PURPOSE:To prevent any vibration from being produced owing to the degree of vacuum by detecting the high degree of vacuum of a condenser and the rate of a change in the degree of the vacuum based upon each operation parameter, and predicting the change in the degree of vacuum to match it to a pattern of an operation state change, and hereby keeping the degree of the vacuum within a predetermined value. CONSTITUTION:There is provided a control device 31 for monitoring a state change of a plant, and detecting the state change, and hereby predicting a change in the degree of vacuum of a condenser and issuing a control signal. In the case where a load is steeply lowered or raised, the degree of vacuum is steeply raised or lowered linking with the load, whereby the change in the degree of vacuum goes over a predetermined value of the width of the change in the degree of vacuum being a factor of generation of turbine vibration, and influences the vibration generation and turbine interruption. The control device 31 evaluates the rate of the change in the degree of vacuum and condenser characteristics based upon the rate of the change in the plant load and hereby previously draws an air extractor inlet valve 10 and an air extractor inlet bypass valve 22.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a thermal power plant and an atomic coupler comprising a steam generator, a turbine, a condenser, etc. Concerning monitoring, regulating and regulating devices.

[Conventional technology]

FIG. 2 shows a system diagram of the prior art described in, for example, Japanese Unexamined Patent Publication No. 1-98895.

Steam generator! Exhaust steam from the turbine 1 driven by steam generated in (not shown) is collected in the condenser shell 2,
The circulating water pump 4 exchanges heat with the cooling water sent to the condenser water chamber 3 through the cooling water supply pipe 5, and after condensation, it circulates within the plant and returns to the steam generator again to form a closed circuit shell. ing.

The degree of vacuum within the condenser shell 2 is also ensured by this cooling water.

This cooling water passes through a cooling water outlet valve 6 and a cooling water discharge pipe 7.
is discharged by

On the other hand, the non-condensable gas in the condenser shell 2 is sucked through the air extraction pipe 9 by the air extractor 11, and in the case of an atomic couplant, is discharged to the exhaust stack 13 via the exhaust gas treatment device 12. In the case of a thermal power plant, an exhaust gas treatment device 12. No exhaust stack 13 is installed, and the gas is directly exhausted to the atmosphere.

The degree of vacuum in the condenser is maintained by the extraction of the non-condensable gas and the cooling action of the cooling water.

The characteristics of the vacuum degree change of the condenser are shown in Figs. 3 to 6.

FIG. 3 shows the change in condenser vacuum degree with respect to the plant load using the cooling water temperature as a parameter when the amount of cooling water to the condenser is constant. The degree of vacuum in the condenser becomes higher as the cooling water temperature becomes lower T2 than the higher temperature T1, and at the same cooling water temperature, the lower the plant load is, the higher the degree of vacuum becomes.

FIG. 4 shows changes in the condenser vacuum degree with respect to the cooling water amount and the cooling water inlet temperature when the plant load is constant. FIG. 5 shows the change in condenser vacuum degree with respect to the amount of cooling water. FIG. 6 shows the change in condenser vacuum degree with respect to the amount of noncondensable gas extracted.

From Figures 3 to 6, the factors that change the degree of vacuum in the condenser are determined by external factors such as the cooling water temperature, which is influenced by the outside temperature, and plant operation, and the plant load, which can be controlled manually.
There are two types: the amount of cooling water and the amount of non-condensable gas extracted.

Problems with the degree of vacuum include the fact that at high degrees of vacuum (more than 740 mnHg), vibrations occur due to instability of the rotor (not shown) in the turbine 1, and the tubes (not shown) in the condenser ice chamber 3. There is tube vibration due to the high flow rate of steam flowing outside, and it is necessary to operate the tube to adjust it to the specified vacuum level.

Conventionally, this method of adjusting the degree of vacuum has been carried out using the characteristics of the condenser as described below.

(1) Changing the blade angle of the li-ring water pump 4 or throttling the cooling water outlet valve 6 to reduce the amount of cooling water flowing into the condenser, thereby worsening the degree of vacuum.

(2) Slightly open the air suction valve 8 and drain the air from the atmosphere into the condenser shell 2.
The amount of noncondensable gas increases and the degree of vacuum deteriorates.

(3) Throttle the air extractor inlet valve 10 to limit the amount of non-condensable gas extracted to the air extractor 11, thereby increasing the amount of non-condensable gas and worsening the degree of vacuum.

[Problem to be solved by the invention]

Conventional adjustment methods have the following drawbacks.

(1) If the amount of cooling water is reduced, the temperature rise of the cooling water in the condenser will exceed the design value, resulting in an impact on the environment and failure to comply with the regulation values.

(2) Air injection increases radioactivity in the atmosphere, especially in the case of atomic couplants.

(3) The air extractor inlet valve 10 has a large diameter and the valve opening is several percent, making it extremely difficult to operate.

In addition, other vacuum degree change rates (approximately 10+um
New findings have revealed that turbine vibration is induced when Hg/H) is large, making it more difficult to respond using conventional adjustment methods (manual operation).

Even if the vibration phenomenon is slight, once it occurs, it increases at an accelerated rate and causes the turbine to stop.

The purpose of the present invention is to constantly monitor the operating status of a plant in order to prevent vibrations caused by the degree of vacuum, detect changes in the operating status in advance, and automatically take measures to prevent changes in the degree of vacuum in advance. The purpose of the present invention is to provide a condenser vacuum adjustment device that enables

[Means to solve the problem]

The above purpose of the present invention is to detect the high degree of vacuum and the rate of change in the degree of vacuum of the condenser, which are factors that cause the generation of turbine vibration, using various operating parameters, predict changes in the degree of vacuum in advance, and adjust the rate of change in the degree of vacuum to the pattern of changes in the operating state. This is achieved by a proactive control type control device that maintains the degree of vacuum within a specified value.

[Effect]

This is possible by timely commanding the parameters shown in FIGS. 3 to 6, which are factors for changing the degree of vacuum in the condenser, from the control device.

〔Example〕

FIG. 1 shows a system diagram of the present invention.

An air extraction bypass pipe 21 with a smaller capacity is branched from the air extraction pipe 9, and an air extractor inlet bypass valve 22 is installed in the middle of the piping.
Set up.

Further, an exhaust gas recirculation pipe 23 that bypasses the air extractor 11 and the exhaust gas treatment device 12, and an exhaust gas recirculation valve 24 that adjusts the amount of exhaust gas are installed in the middle of the pipe. The plant operation status is at startup and when the load increases.

There are various operation cases such as emergency situations such as during load fluctuation, constant load operation, load drop, and load cutoff, and changes in cooling water temperature, which is another external factor for this state change, are affected by each operation case. all of which affect condenser vacuum changes. A control device 31 is installed that constantly monitors changes in the status of these plants, detects the changes in status, predicts changes in the degree of vacuum in the condenser, and issues control signals. This control device 31 takes in plant load, cooling water outlet/inlet temperature, condenser vacuum degree, cooling water amount, load cutoff, etc. as a time function, calculates condenser characteristics from state changes, and calculates the condenser vacuum degree. Before the change occurs, predict what will happen after the vacuum level changes, adjust the air extractor inlet valve, adjust the W water return flow rate, etc. according to the pattern of the change in state.
Commands signals for exhaust gas recirculation valve adjustment, etc., and performs individual adjustment and joint adjustment.

Before the initial load of the turbine or when the load is extremely low, high vacuum operation is performed, so the plant load is taken into the control device 31, and the optimum exhaust gas recirculation valve adjustment for condenser vacuum adjustment is selected. opens the exhaust gas recirculation valve 24,
The high vacuum capability of the air extractor 11 is killed and the degree of vacuum is automatically adjusted to below the high vacuum degree limit value while being recirculated. In the case of a thermal power plant, similar operation is possible by slightly opening the air intake bypass valve 14 for the same reason.

When the plant load is continuously operated at a low load or a rated load, the control device 31 determines the load change rate and controls the air extractor inlet valve 10 and the air extractor bypass so that the rate of change is below the high vacuum limit value. Adjustment is made by opening and closing the valve 22. This state is caused by a change in the temperature of the cooling water inlet, which is an external factor, and the vacuum degree generally changes gradually, so it is sufficient to operate with a high vacuum limit. Therefore, the driving trajectory is shown by the solid line in FIG.

When suddenly lowering or increasing the load due to power supply command or daily load follow-up operation from constant load operation, the load is suddenly linked to the load as shown in Figure 3 Condenser Characteristics. The degree of vacuum increases or decreases, exceeding the specified value of the vacuum degree change width, which is a factor in generating turbine vibrations, which causes vibrations and causes the turbine to stop. In order to solve this problem, the control device 31 calculates the condenser characteristics and the rate of change in the degree of vacuum based on the rate of change in the plant load, and throttles the air extractor inlet valve 10 and the air extractor inlet bypass valve 22 in advance. Perform operations.

This preliminary throttling operation makes it possible to keep the degree of vacuum variation at the time of load drop below a specified value, and to prevent the delay in response due to manual operation in the prior art and the occurrence of turbine vibration due to poor operation. In this case, for backup and fine adjustment of the degree of vacuum, the control device 31 uses a command to adjust the blade angle of the circulating water pump 4 and adjust the circulating water flow rate as a secondary signal.
Send more information. Cooling water outlet valve 6 to adjust circulating water flow rate
The opening degree may be adjusted. When performing this circulating water flow rate adjustment, an interlock is installed so that the condenser cooling water temperature rise value is below a specified value from the cooling water inlet temperature detector 27 and the cooling water outlet temperature detector 28, and the cooling water outlet valve. The control device 31 also has an interlock for preventing cavity formation due to the aperture of No. 6.

Therefore, the operating locus shown by the solid line in FIG. 8 is maintained within the specified vacuum degree change range based on the initial load during the load change.

In addition to the operations described above, there is a need to safely operate the turbine and shift the plant to a shutdown operation even in an emergency where the plant load is suddenly stopped due to load shedding or malfunction of the steam generator.

In the case of this phenomenon, the rate of change in the degree of vacuum in the condenser is large and there is a high possibility that it will affect the turbine vibration. The control device 31 commands a narrowing operation to a fixed opening degree.

In addition, as another example, the vibration change of the turbine or the steam flow rate in the condenser is detected, and if the vibration change changes drastically or the steam flow speed changes extremely, the vacuum state before the change is detected. Track changes, minimize the rate of change in vacuum level, vibration,
Vacuum adjustment is performed to eliminate factors that cause fluctuations in steam flow rate.

As another example, when the range of change in the cooling water temperature is large, the degree of vacuum in the condenser changes due to the rise and fall of the cooling water temperature, and the state of the entire plant changes accordingly, impeding stable operation. There may be cases. In this way, in the case of a plant where the range of variation in cooling water temperature is large, stable plant operation can be maintained by constant vacuum operation.

Additionally, if there is an operational requirement to significantly change the degree of vacuum in the condenser, it is possible to adjust the vacuum while maintaining the rate of change in vacuum level within the specified rate of change while monitoring vibration changes in the turbine. .

These vacuum adjustment operations can be performed by inputting state values to the control device 31.

〔Effect of the invention〕 According to the present invention, there are the following effects.

(1) During plant start-up, load increase, constant continuous operation, descent, and during emergencies, within high vacuum limits,
Operation within the permissible rate of vacuum change is ensured, and turbine vibration and condenser tube vibration can be prevented.

(2) The control device for adjusting the vacuum level takes in the status values of each plant and calculates a prediction of changes in the condenser vacuum level.

Automatic advance control is possible.

[Brief explanation of drawings]

Fig. 1 is a system diagram of an embodiment of the present invention, Fig. 2 is a system diagram of the prior art, Figs. 3 to 6 are characteristic diagrams of the condenser, and Fig.
8 are characteristic diagrams showing examples of changes in the degree of vacuum during load operation. Turbine, 2... Condenser body, 3. Condenser ice chamber, 4.
Circulating water pump, 5... Cooling water supply pipe, 6... Cooling water outlet valve, 7... Cooling water discharge pipe, 8... Air suction valve, 9
... Air extraction pipe, 10 ... Air extractor artificial valve, 11
... Air extractor, 12 ... Exhaust gas treatment device, 13
...Exhaust pipe, 14...Air suction bypass valve, 21.
... Air extraction bypass pipe, 22 ... Air extractor input bypass valve, 23 ... Exhaust gas recirculation piping, 24 ... Exhaust gas recirculation valve, 25 ... Condenser vacuum detector, 26.・
・Plant load detector, 27...Cooling water inlet temperature detector, 28 Figure 1 Figure 2 Figure 5 Figure 5 ” (z) Figure 3 θ !;0 /l) ρfu0u: JIt
Shout) - (Name y + Irumizubendo ('c) Figure

Claims (1)

[Claims] 1. In a condenser that maintains a degree of vacuum by cooling the exhaust of a turbine driven by steam generated from a steam generator of a power plant, the plant load, the cooling water inlet temperature, the cooling The control device detects the water outlet temperature, the degree of vacuum of the condenser, the plant operating conditions such as load shedding, evaluates the contents of the state changes, calculates the predicted degree of vacuum of the condenser, and calculates the degree of vacuum. Condenser vacuum adjustment characterized by prior control of air extractor inlet valve adjustment, circulating water flow rate adjustment, exhaust gas recirculation valve adjustment, etc. in order to keep the reference value and vacuum degree change rate within specified values. Device. 2. A vacuum adjustment device for a condenser according to claim 1, which monitors extreme changes in vibration of the turbine and performs control to suppress vibration. 3. A condenser vacuum adjustment device according to claim 1, which monitors changes in the steam flow rate within the condenser and controls it for the purpose of protecting tubes of the condenser. 4. In claim 1, the degree of vacuum of the condenser is always set to
A condenser vacuum adjustment device that suppresses changes in the overall condition of the plant and maintains stable operation by maintaining constant operation. 5. The condenser vacuum adjustment device according to claim 1, which controls the condenser while monitoring vibration changes even when there is an operation request to significantly change the degree of vacuum of the condenser.