JPS594884A - Method and device for controlling operating number of condenser vacuum pump - Google Patents

Abstract

PURPOSE:To manage and control most economically the number of vacuum pumps by a method wherein the load coefficient of a steam turbine, the cooling water temperature of a condenser and the vacuum degree of the condenser are detected, and at least two data among said detected data are inputted into an automatic calculator, then the optimum vacuum pump operating number is calculated. CONSTITUTION:A operating number change-over limit vacuum degree calculating part 23.3 storing the curve of a vacuum pump operating number change-over limit vacuum degree VL=f(L), and a reference vacuum degree calculating part 23.4 storing the curve of a reference vacuum degree VB=f(L, T), are formed in a calculator 23. A load coefficient L from a load transmitter 21 is inputted into said calculating part 23.3, and the change-over limit vacuum degree VL is calculated. Then the reference vacuum degree VB is calculated after said load coefficient L and cooling water temperature T are inputted into the calculating part 23.4. An optimum operating number deciding part 23.5 compares the VL with the VB, when VL>=VB is held, the decision is the single operation, while when VL<VB is held, the decision is the dual operation. The result of said decision is displayed on a display 24 and a control signal is trasmitted to control automatically vacuum pump driving motors 12a, 12b.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention determines the appropriate number of operating vacuum pumps installed in a steam turbine condenser of a thermal power plant or a nuclear power plant, and performs operation/stop control of the vacuum pumps. The present invention relates to a method and an apparatus for performing the same.

Conventionally, when water ring rotary vacuum pumps were installed to extract all gas from a condenser, ``generally, two to three units were installed, and when the plant was started, all units were operated to rapidly prepare for startup. During normal operation, one unit is normally shut down and used as a spare unit.

However, even during normal operation, the
Especially during low-load operation, the air extraction capacity of the vacuum pump tends to be insufficient, resulting in a decrease in the degree of vacuum in the condenser.
Therefore, the degree of vacuum on the turbine exhaust side may decrease, resulting in a decrease in thermal efficiency. In such a situation, it is considered appropriate to operate the idle vacuum pump to maintain a high degree of vacuum in the condenser and improve thermal efficiency.

The inventors have found through recent research that when operating a power generation plant using a steam turbine at a load of 25% of the rated load, the degree of vacuum increases by 10wHz when two vacuum bottles are operated compared to when operating 11 vacuum bottles. It was confirmed that the thermal efficiency improved by 1%, and it was therefore found that controlling the number of vacuum pumps in operation has an important economic significance.

FIG. 1 is a chart in which the degree of vacuum is plotted on the horizontal axis and the air flow rate is plotted on the vertical axis, with the bleed air flow rate of the vacuum pump shown as a solid line and the amount of leaked air shown as a broken line.

The amount of air extracted from the vacuum pump draws two curves, one when one pump is operating and the other when two pumps are operating, and the leakage air amount is 100%, 75%, and 50% at the turbine load rate.

Four curves are shown for the 25% case.

The horizontal axis coordinate of the intersection of the solid line and the broken line means the degree of vacuum under the operating conditions.

Regarding the question of how many vacuum pumps should be operated depending on various operating conditions, it is also necessary to consider the temperature of the cooling water in the condenser. In Figure 2, the horizontal axis shows the load factor, and the vertical axis shows the vacuum degree of the condenser. , T: Cooling water temperature CC) is an example of a chart showing each cooling water temperature with a solid line.

Under the operating conditions at each point on the coordinate plane above, if we evaluate the optimal number of vacuum pumps to operate based on economic efficiency, we find that in the upper left part of the figure it is appropriate to operate two vacuum pumps, and in the lower right part it is suitable to operate one vacuum pump. is suitable, and its boundary is as shown by the number switching limit vacuum degree curve Vt=f(L) shown by a broken line.

By taking the cooling water temperature on the vertical axis, the limit vacuum degree curve V in the above chart is obtained.
When t is transferred, the number of units switching limit cooling water temperature T is obtained as shown in Fig. 3. = f (L>curve is obtained.

The upper right corner of this curve is the load factor-cooling water temperature range suitable for one-unit operation, and the lower left corner is the load factor-cooling water temperature range suitable for two-unit operation.

Based on the above research results, the present invention provides a method for managing and controlling the number of vacuum pumps in operation in the most economical manner for a steam turbine condenser equipped with a plurality of vacuum pumps;
and the same equipment.

In order to achieve the above object, the method of the present invention detects the steam turbine load factor, condenser cooling water temperature, and condenser vacuum degree, and sends at least two of the above detected values to an automatic calculator. The system is characterized in that the optimal number of vacuum pumps to be operated is calculated by the arithmetic unit based on the input information, and the operation of the pumps is controlled based on this.

FIG. 4 is a system diagram of a steam turbine power generation plant equipped with an example of a device for controlling the number of vacuum pumps in operation configured to carry out the method of the present invention.

1 is a steam generator, 2 is a steam supply pipe, 3 is a steam turbine, 4 is a generator, 5 is a condenser, 6 is a cooling water supply pipe, 7 is a water supply pump, and 8 is a water supply pipe. Two vacuum pumps lla and llb are connected to the condenser 5 through an air extraction pipe 10.

12a and 12b are drive motors, respectively.

A load signal transmitter 21 is provided in the generator 4 to control the load of the generator,
That is, the load factor of the steam turbine 3 is detected, and the cooling water supply pipe 6 is
A cooling water temperature transmitter 22 is provided in the condenser 5 to detect the condenser cooling water temperature, and a condenser vacuum degree transmitter 25 is provided in the condenser 5 to detect the condenser vacuum degree.

A computing unit 23 is provided to input the output signals of the respective transmitters described above, and the optimum number of vacuum pumps to be operated is calculated as described later.

24 is a display attached to the arithmetic unit 23.

FIG. 5 is a control principle diagram in an example in which the method of the present invention is implemented using the apparatus shown in FIG. 4.

Number switching limit cooling water temperature calculation unit 23 in automatic calculation unit 23
．． 1 and store the 'ro=r(L) curve shown in FIG. As described above, this curve is derived from the diagram of FIG. 2, so the factors related to the degree of vacuum of the condenser are included as values on the vertical axis of FIG.

According to the curve in FIG. 3, ie, the curve 23.1 in FIG. 5, when a load factor is given, the corresponding limit cooling water temperature To for switching the number of vacuum pumps can be calculated.

The output signal of the load signal transmitter 21 is given to the arithmetic unit 23.1 to calculate the switching limit temperature To, and this is input to the optimum operating number determining unit 23.2. The optimum operating number determination units 23 and 2 are inputted with the actually measured coolant temperature T from the coolant temperature transmitter 22, and are made to compare the switching limit temperature To with the actually measured coolant temperature T.

However, if we simply compare To and T, ToL=l
In the case of T, the comparison result will change many times in a short period of time and the vacuum pump will have to be started and stopped frequently, so set an appropriate constant C to provide a dead zone and calculate the actual water temperature. Actual measured water temperature in operation of 91 units due to the establishment of T>To+C
If r<'ro -c holds true, the optimum number of machines to be operated is determined by the above two equations.

The determination result may be displayed on the display unit 24, and the operator may operate or stop the vacuum pumps lla and llb according to the display, or the operator may send the vacuum pump drive motor control signals 26a and 26a to the calculator 23 based on the determination result. 26b to the drive motor 12a.

12b may be automatically controlled.

FIG. 6 is a control principle diagram in an embodiment different from the above-mentioned disaster.

The calculation unit 23.3 stores the curve of the vacuum pump number switching limit vacuum degree Vb=f(L) in the chart of FIG. 2 described above, and the reference vacuum degree Vb.
A reference vacuum calculation unit 23.4 is configured in which the curve of m = f (L, T) is stored, and the load factor from the load transmitter 21 is inputted to the calculation unit 23.3 to determine the switching limit vacuum. degree VL is calculated, and the above load factor and cooling water temperature T are inputted into the calculating section 23.4 to calculate the reference degree of vacuum vIl, and the above Vt and Vm are calculated by the optimum operating number determining section 23.5. If VL≧■1 holds true, it is determined that one unit is in operation, and VL<
When Vl is established, it is determined that two units are in operation, the result is displayed on the display 24, and a control signal is transmitted to drive the vacuum pump drive motor 12a.

12b is automatically controlled.

FIG. 7 shows a further different embodiment. In this embodiment, the unit number switching limit vacuum calculation unit 2 is similar to the previous example (Fig. 6).
3.3 to calculate the switching limit vacuum degree VL in the same manner as in the previous example, and compare the actual vacuum degree V of the vacuum degree transmitter 25 and the above calculated value Vy- in the optimum operation number determination unit 23.6. let

V-) When VL, it is determined that the air extraction capacity of the vacuum pump exceeds the amount of leaked air, so it is determined that one pump is in operation, and when Va≧VL, it is determined that two pumps are in operation.

The diagrams in Figure 2 and Figure 3 stored in the calculator 23 change as the amount of leaked air changes due to aging of the steam turbine plant, so the amount of leaked air is measured periodically. Although it is desirable to correct the stored values, it is sufficient to carry out the above periodic measurement and correction once or twice a year. The above correction can also be made by constantly measuring the amount of air extracted by the vacuum pump and making corrections based on changes in the amount of air extracted by the vacuum pump.

Since the functions and storage capacity required for the arithmetic unit 23 described above are relatively small, if it is installed as a dedicated arithmetic unit, a small microcomputer is sufficient and the equipment cost is not expensive. Furthermore, as mentioned above, since a small-capacity computer is insufficient, it is easy to incorporate the system into a large-sized computer for controlling and monitoring the entire power plant, for example, by taking advantage of its extra capacity.

In the above-mentioned embodiment, the degree of vacuum of the condenser in the low turbine load range is 5 to 10 mH compared to the conventional one.

The heat consumption rate was improved by 1 to 2%.

However, if the vacuum pump drive elements are controlled by transmitting the vacuum pump operation/stop command signal based on the calculation result of the calculator 23 as shown above, the method for controlling the number of operating condenser vacuum pumps of the present invention can be performed. It is convenient because it can be done completely automatically.

As described in detail above, the method for controlling the number of operating condenser vacuum pumps of the present invention applies to the steam turbine load, the condenser cooling water temperature, and the The degree of vacuum in the condenser is detected, at least two of the above detected values are input into an automatic calculator, and the automatic calculator calculates the optimum number of the plurality of vacuum pumps to be operated. management and control.

Further, the condenser vacuum pump operation number control device of the present invention has the following features:
In a steam turbine condenser equipped with a plurality of vacuum pumps, a steam turbine load detection means, a condenser cooling water temperature detection means, and a condenser vacuum degree detection means are provided, and the detection means for each of the above detection means are provided. By providing an automatic calculator for inputting signals and allowing the automatic calculator to calculate the optimal number of operating vacuum pumps in the front and rear, the method of the present invention described above can be easily implemented and its effects can be achieved. can be demonstrated.

[Brief explanation of the drawing]

Figure 1 is a chart showing an example of the relationship between vacuum pump vacuum and air flow rate, Figure 2 is a chart showing an example of the relationship between steam turbine load factor and condenser vacuum, and Figure 3 is steam Chart showing an example of the relationship between turbine load factor and cooling water temperature, No. 4
The figure is a system diagram showing one embodiment of the apparatus of the present invention, and each of FIGS. 5 to 7 is a control principle diagram of an embodiment of the method of the present invention. 3... Steam turbine, 4... Generator, 5... Condenser, 6... Cooling water supply pipe, 10... Air extraction pipe, i
ta. flb...Vacuum pump, 12a, 12b river drive motor, 21...Load signal transmitter, 22...Cooling water temperature signal, 23...Arithmetic unit, 24...Display unit, 25...
...Condenser vacuum transmitter, 26a, 26b...Motor control signal. Agent Patent Attorney Masami Akimoto #l Eyes fθ 7Meθ 7Jθ
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Claims (1)

[Claims] 1. In a steam turbine condenser equipped with a plurality of vacuum pumps, the steam turbine load, condenser cooling water temperature, and condenser vacuum degree are detected, and the above detected values are A method for controlling the number of condenser vacuum pumps in operation, characterized by inputting at least two values into an automatic calculator and calculating the optimum number of operating vacuum pumps of the plurality of vacuum pumps by the automatic calculator. 2. In a steam turbine condenser equipped with a plurality of vacuum pumps, a steam turbine load detection means. A condenser cooling water temperature detection means and a condenser vacuum degree detection means are provided, and an automatic calculator is provided to input at least two of the detection signals of each of the detection means, and the automatic calculator is used to detect the plurality of units. A device for controlling the number of condenser vacuum pumps in operation is characterized by calculating the optimum number of vacuum pumps to be operated. 3. The automatic calculator has a function of issuing an operation/stop command signal to the plurality of vacuum pumps based on the calculated optimum number of operating units. A device for controlling the number of condenser Makabe pumps in operation according to item 1 of the Aokimu scope.