JPS5926764B2 - Turbine oil supply temperature control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an oil supply temperature control device for a turbine bearing.

Due to the formation of an oil film on the bearing lubricating surface, the oil supply temperature to the turbine differs during turning operation and rated speed operation, and the oil supply temperature during turning must be lower than that at rated speed.

Conventionally, in order to perform such temperature control, an oil supply temperature control device having a configuration as shown in FIG. 1 has been used.

That is, in FIG. 1, oil is supplied to turbine bearings and the like from an outlet 2 of an oil cooler 1, and a temperature detector 3 for detecting the temperature of the supplied oil is connected to the outlet.

Therefore, a regulator 4 is provided to control the oil supply temperature, and the regulator compares the signal of the temperature detector 3 with the signal of the manual setting device 5, and according to the deviation signal, performs electro-pneumatic conversion. The cooling water amount adjusting valve 7 is opened or closed via the device 6 to adjust the amount of cooling water to the oil cooler 1.

The oil cooler 1 is attached to an oil tank 8, and oil is supplied from the tank.

In the configuration as described above, in order to control the oil supply temperature according to the operating conditions of the turbine as described above, an operator has to adjust the setting value of the manual setting device 5.

FIG. 2 is an explanatory diagram showing the direction of the oil supply temperature and the opening degree of the cooling water amount control valve with respect to the turbine rotation speed when using the conventional oil supply temperature control device shown in FIG.

When the setting value of the setting device 5 is increased from the oil supply temperature during turning to the oil supply temperature during rated speed operation which is higher than this temperature, the output of the regulator 4 becomes a signal in the direction of closing the control valve 7, and the amount of cooling water is increased. As the oil supply temperature is reduced or cut off, the oil supply temperature gradually increases due to the heat generated in the bearing.

On the other hand, since the regulator 4 operates as a proportional integral in order to eliminate any control deviation, the output of the regulator 4 is controlled by the control valve while the oil temperature in the oil tank 8 rises to the oil supply temperature at the rated speed. 7 is saturated at the limit in the direction of fully closing.

In other words, reset windup occurs.

As a result, even if the oil supply temperature rises to the specified set value, it takes time for the regulator output to return to the signal that starts opening the control valve, and during that time the oil supply temperature exceeds the set value.

In other words, overshoot occurs.

The difference between the upper limit of the allowable range of oil supply temperature and the control temperature is small, and therefore the above-mentioned overshoot may exceed the allowable range, which must be prevented.

Therefore, when the fuel supply temperature approaches the temperature at the specified rated speed, the operator increases the set value little by little and operates while monitoring it until it reaches the specified value.

This significantly increases the burden on the operator at monitoring points and during the start-up phase, which involves many operations.

Further, although there have been some examples of proportional and integral action regulators that have been provided with the following functions in order to prevent the reset windup effect, these have not been sufficient.

One of them is to limit the regulator output range to prevent it from exceeding a value equivalent to fully closing the regulating valve.

However, with this method, the control valve starts opening only after the oil supply temperature rises to the set value of the regulator, so the control valve opens until the required opening allows the cooling water flow to pass through (while the oil supply temperature rises). Therefore, overshoot cannot be completely eliminated.

Another method is to enable only proportional operation in a temperature range within the proportional band of the regulator and a certain degree below the control set temperature (fuel supply temperature at rated speed).
Some devices are designed to enter proportional-sufficient integral operation when the temperature approaches the control set temperature.

However, when such a regulator is used, when the oil supply temperature enters the proportional operating range of the regulator, the control valve opens in proportion to the oil temperature (so that the cooling water flows to the oil cooler). The rate of increase in the fuel supply temperature will slow down.

Here, since the proportional band must have a value that allows stable control, its value cannot be made small just for the purpose of avoiding a slowdown in the increase in fuel temperature.

Also, in order to raise the turbine to the rated speed, it is necessary that the oil supply temperature reaches a certain tolerance value or above, so a slowdown in the increase in the oil supply temperature delays raising the turbine to the rated speed, prolonging the plant start-up time. As a result,
Undesirable.

The present invention aims to eliminate the drawbacks of the conventional oil supply temperature control device described above, and automatically adjusts the oil supply temperature according to the operating condition over the entire operating range from turbine turning operation to rated speed. In a device that can control the oil temperature as the turbine speed increases, when it reaches the specified oil supply temperature when maintaining the rated speed, there is an overshoot (such as one that can smoothly settle down to the specified oil temperature). The purpose of this invention is to provide a highly reliable oil supply temperature control device.

According to the oil supply temperature control device of the present invention, when the turbine speeds up from turning to the rated speed, the oil supply temperature is increased to the final oil supply temperature without overshoot, so that the final oil supply temperature, that is, the rated At an oil supply temperature that is slightly lower than the specified oil supply temperature under speed operation and that is permissible for the turbine to reach the rated speed, the deviation of the oil supply temperature control is temporarily reduced to zero, and then the actual oil temperature is The set oil temperature can be raised to the final oil supply temperature at a rate that can be followed while maintaining a controlled state with almost no deviation.

Therefore, overshoot does not occur, and completely safe and reliable fuel supply temperature control is possible.

Therefore, it is possible to reduce the burden placed on the operator when starting the turbine, which is a busy and stressful time.

Hereinafter, the configuration and operation of an embodiment of the turbine oil supply temperature control device of the present invention will be described with reference to FIGS. 3 and 4.

The oil supply temperature control device shown in FIG. 3 differs from the conventional similar device shown in FIG. 1 in that the temperature setting section is divided into 5A to 5D.

The settings and operation of the apparatus of the present invention shown in FIG. 3 will be explained below using FIG. 4 as well.

The first temperature setting device 5A is a setting device for controlling the oil supply temperature to T1 during turning operation, and the switch d is in a closed state.

At the same time as the turbine speed increases, the switch d opens and the switch C closes to switch to the temperature T2 set by the second temperature setting device 5B.

T2 is selected to be slightly lower than the oil supply temperature T3 when the turbine is operated at the rated speed (and at a temperature that is permissible for the turbine to reach the rated speed).

When the actual fuel supply temperature rises and reaches T2, switch C opens and switches a and b close, automatically switching to the next setting device, that is, the ramp function signal generator 5C.

The ramp function signal generator 5C generates a ramp function output that gradually increases the set temperature.

The rate of increase in this set temperature is set so that the actual oil supply temperature can sufficiently follow it.

In this way, after the actual oil supply temperature reaches T2, the oil supply temperature control increases moment by moment while maintaining almost no deviation.
Finally, the oil supply temperature T3 that should be maintained at the rated speed is reached.

Incidentally, a selector 9 is connected between the signal generator 5C and the third temperature setting device 5D to select a lower signal among the signals of these setting devices.

With the oil supply temperature control device as explained above, the final oil supply temperature is reached while maintaining control with almost zero +4 deviation, so the temperature change is smooth and the final temperature is not reached, unlike what occurs with conventional control devices. No overshoot occurs at the point where the

Temperature regulator 4 of the oil supply temperature control device of the present invention shown in FIG.
, first to third temperature setting devices 5A, 5B.

Of course, electric meters can be used as the signal generator 5D and the signal generator 5C, but pneumatic meters can also be used based on the same principle.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of a conventional turbine oil supply temperature control device, and Fig. 2 shows the tendency of the oil supply temperature and the opening degree of the cooling water amount control valve with respect to the turbine rotation speed when controlled by the control device of Fig. 1. Explanatory diagram, FIG. 3 is a block diagram showing the configuration of the turbine oil supply temperature control device of the present invention, and FIG. 4 shows the oil supply temperature and cooling water amount control valve opening degree with respect to the turbine rotation speed when controlled by the control device of FIG. 3. It is an explanatory diagram showing a tendency. Explanation of symbols 1... Oil cooler, 2... Oil outlet, 3...
...Temperature detector, 4...(Temperature) regulator, 5A...
First temperature setter, 5B...Second temperature setter, 5C
...Signal generator, 5D...Third temperature setting device, I.
...Cooling water flow control valve, 8...Oil tank, 9...Signal selector.

Claims (1)

[Claims] 1. In a turbine oil supply temperature control device having an oil cooler for supplying oil to a turbine and a control valve for regulating cooling water flowing to the oil cooler, the output 1] of the oil cooler is detected and responsive to the temperature. a temperature sensor that generates a signal, and a first and third temperature setting device that sets the oil supply temperature during turning operation and rated speed operation, respectively; a second temperature setting device that sets an allowable oil supply temperature to reach the speed and automatically switches when the turning operation shifts to speed increase;
a signal generator that generates a signal that gradually increases the set oil supply temperature at a rate that the actual oil supply temperature can follow from the time when the actual oil supply temperature reaches the set temperature of the temperature setting device; A selector that selects the lower value of the output from the third temperature setter, and a selector that selects the lower value of the output from the third temperature setter; a signal selection means for detecting the signal selected by the selector after the actual oil supply temperature reaches the set temperature of the temperature setting device, and comparing the signal detected by the signal selection means with the signal of the temperature detector. and a regulator that controls opening and closing of the control valve according to the amount of deviation.