JPH01163408A - Method for controlling operation of steam turbine - Google Patents

Abstract

PURPOSE:To prevent turbines from being damaged due to fluctuation in loading by incorporating a control system based on the measurement of the temperature of the front and rear thrust bearings of the turbines. CONSTITUTION:Temperature sensors t1 and t2 are provided for the front and rear sections of a thrust bearing 5 arranged at the outside shaft end of a high pressure stage turbine 1, and the detected front section temperature (i) and rear section temperature (j) are constituted to be outputted to a controller 6. When the front section temperature (i) exceeds an upper limit set in advance, those operations to decrease high pressure steam inflow fed to the high pressure stage turbine 1, to decrease mixed air inflow fed to a medium pressure stage turbine 2 and to increase bleed air outflow blown out of a low pressure stage turbine 3 are prohibited. And when the rear section temperature (j) exceeds an upper limit, those operations to increase high pressure steam inflow, to increase mixed air inflow and to decrease bleed air outflow are prohibited. Thus, the incorporation of a control system based on the temperature of the thrust bearing enables quick response against fluctuation in loading, thereby remarkably improving the protection of the turbines.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a method for controlling the operation of a steam turbine.

Conventional technology There are various types of steam turbines, and especially when low-pressure steam for working is required in addition to power in a factory, in order to effectively utilize the high-pressure steam generated in a boiler, air-fuel mixture,
An extraction turbine is used.

However, when extracting steam after use in an intermediate-pressure turbine in a power generation steam turbine, for example, the amount of extracted steam constantly fluctuates depending on the operating state of the demand equipment. Therefore, when the amount of extracted air increases, the output of the generator becomes insufficient due to a decrease in the number of rotations of the turbine, and conversely, when the amount of extracted air decreases, the rated operation is exceeded, damaging the turbine and causing a failure.

In order to eliminate such inconveniences and ensure rated operation, various measures have been taken, and in particular, in the operation of air-fuel mixture and extraction turbines, the amount of main steam inflow, middle stage steam inflow, air-fuel flow rate,
It is necessary to set the flow rates within predetermined conditions for the bleed air outflow, condensate outflow, power generation output, etc., and control operation within the set values.

As a new control method, the output of the generator or the shaft power of the turbine is detected, the detected value is compared with the set value to find a deviation value, and the amount of high-pressure steam flowing into the turbine is determined based on this deviation value. Adjustment/subtraction output control method (Unexamined Japanese Patent Publication No. 53-9
0544>, detect the temperature of the inner and outer surfaces of the tardon rotor,
There is a method of calculating the difference between the detected values and controlling the temperature of a heater installed in the rotor so that the calculated value becomes a preset target value (Japanese Patent Laid-Open No. 61-218705).

Problems to be Solved by the Invention The general control method described above performs control based on the installed capacity. The output control method described above controls the output so as to maintain a predetermined output by adjusting the amount of steam inflow, and the latter method of controlling the temperature of the heater installed in the turbine rotor Although the life of the rotor is increased by minimizing the temperature difference between the inside and outside, neither of these measures can be used to prevent overload from changes in thrust force due to changes in steam flow rate.

Steam turbines are usually designed to ensure thrust force commensurate with turbine output.

However, because the relationship between output and thrust force changes due to aging, there is no guarantee that simply limiting output will not affect turbine operation.

The temperature of the thrust bearing can be measured and monitored to avoid overloading the thrust bearing due to changes in thrust force. However, simple temperature measurement alone cannot cope with frequent changes in steam flow rate.

In view of the current situation, the present invention proposes a method of controlling operation based on temperatures continuously and intermittently measured on both the front and back surfaces of a thrust bearing.

Means for Solving the Problems This invention provides that during operation of a turbine, the front and rear temperatures of the thrust bearing of the turbine are measured separately and compared with a preset upper limit, and the front temperature is determined to be the upper limit. If the value is exceeded, operate to reduce the amount of main steam inflow, reduce the amount of mixed air inflow,
The purpose is to stop the bleed air outflow amount increasing operation and, if the rear temperature exceeds the upper limit value, stop the main steam inflow amount increasing operation, the mixed air flow increasing operation, and the bleed air outflow amount decreasing operation.

Example An embodiment of this invention will be described based on the drawings.

Figure 1 is a flow sheet when using air-fuel mixture, extraction, and condensation turbines for power generation.
The high-pressure turbine (1) is supplied with main high-pressure steam from the high-pressure steam pipe via a flowmeter (9) and a control valve (10), and the intermediate-pressure turbine (2) is supplied with a flowmeter ( 11)
, the mixed air steam is supplied through the control valve (12), and the power 2 working steam is extracted through the control valve (14) and the flow meter (13). A condenser (8) is installed in the low-pressure turbine.
Outflow piping is provided. In the figure, (4) is the R electric machine, and (5) is the thrust bearing.

The high-pressure steam inflow rate setting a is performed via the controller (15), the air mixture inflow rate setting is performed via the controller (16), and the extraction air outflow rate setting C is performed via the controller (17). Both are provided so that they can be automatically set by the command value d that is revealed in the energy balance calculation by the computer (7), or can be set manually by the operator.

In addition, the high pressure steam inflow amount e measured by the flow meter (9), the air mixture inflow amount f measured by the flow meter (11), and the flow meter (1
The extracted air outflow amount q measured in 3) is determined by the controller (6).
), and the condensate outflow ih and the output 2 of the generator (4) are also output to the controller (6).

A temperature sensor (tl) is installed at the front of the thrust bearing installed at the outer shaft end of the high-pressure turbine (1), and a temperature sensor (t2) is installed at the rear.
), and the detected front temperature 1 and rear temperature j are controlled by a controller (
6).

As mentioned above, the high-pressure steam inflow setting a, the mixed air inflow setting, and the extraction air outflow setting C are all automatically set by the command value d based on the energy balance calculation by calculation FM (7), or manually set by the operator. However,
The steam turbine is operated according to the upper limits set for each of the high-pressure steam inflow amount e, mixed air flow rate f, extracted air outflow amount Q, condensate outflow 1h, steam inflow amount k to the intermediate pressure turbine, and power generation output 2. The set values a, b, and c are determined so as to fall within the allowable range of the value and the lower limit value.

In addition, the following conditions are taken into consideration based on the temperature measurement results of the front temperature i and rear temperature j of the thrust bearing.

If the front temperature i exceeds the upper limit, high pressure steaming is performed.

Operations that reduce the amount of air inflow, operations that reduce the amount of mixed air flow, and operations that increase the number of bleed air outlets are prohibited, and if the rear temperature j exceeds the upper limit, the amount of high-pressure steam inflow is increased. operations, operations that increase the amount of mixed air flow, and operations that reduce the amount of bleed air flow are prohibited.

The apparatus having the above configuration and consisting of a steam turbine with a capacity of 123,000 k and a generator with a maximum output of 20,000 k was controlled and operated so as to satisfy the conditions shown in Table 1 below.

The upper limit of safe operating temperature for thrust bearings is 80℃.
If either the measured front temperature i or rear temperature j exceeds the upper limit value, each setting value a, b is set by operating the controller (6) so that the above-mentioned prohibition condition is satisfied. , c are changed and commanded to each controller (15), (16), and (17).

Effects of the Invention In the operation of the above-mentioned turbine, the present invention provides a control system based on the thrust bearing temperature, in addition to the control operation based on the normally performed high-pressure steam inflow rate setting, mixed air inflow rate setting, and extraction air outflow rate setting. Therefore, even when load fluctuations occur frequently, it is possible to quickly change to the best condition. Therefore, turbine protection is significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a flow sheet of an air-fuel mixture, extraction air, and condensation turbine for power generation in one embodiment of the present invention. 1...High pressure stage turbine 2...Intermediate pressure stage turbine 3
...Low pressure stage turbine 4...Generator 5...Thrust bearing 6...Controller 7...Computer
8...Condenser 9, 11.13...Flowmeter 10, 12.14...Control valve 15, 16.17...Controller applicant Sumitomo Metal Industries, Ltd.

Claims (1)

[Claims] During turbine operation, the front and rear temperatures of the turbine's thrust bearing are measured separately and compared with a preset upper limit. If the front temperature exceeds the upper limit, main steam inflow reduction operation is performed. Stop the operation to reduce the amount of air mixture inflow and increase the amount of extracted air outflow, and if the rear temperature exceeds the upper limit, stop the operation to increase the amount of main steam inflow, the operation to increase the amount of mixed air inflow, and the operation to decrease the amount of extracted air outflow. A steam turbine operation control method characterized by: