JPS6357802A - Control device for expansion turbine - Google Patents

Abstract

PURPOSE:To improve operational reliability of an expansion turbine, by providing three function generators which respectively control the inlet valve of the turbine, the first one for the starting, the second one for the normal stopping, and the third one for the emergency stopping of said expansion turbine, and selectively using these function generators. CONSTITUTION:A gas passage 1 is provided with a temperature sensor 2, for detecting a turbine inlet temperature, turbine inlet valve 3, the first expansion turbine 4, a pressure detecting sensor 5 for detecting the pressure between the expansion turbines, and the second expansion turbine 6 in this order from the upstream side. And a control system is provided with the first function generator 8 to control said inlet valve 3 in the starting stage of said expansion turbines, the second function generator 12 to control said inlet valve 3 in the normal operation of said turbines, and the third function generator 13 to control said inlet valve 3 in the emergency stopping of said turbines. The first and the second signal switching device 10, 11 are provided to transmit to said inlet valve 3 an output from one of said generators 8, 12, 13 or from a pressure regulating meter 7, whichever corresponding to the operational state of said turbines.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control device for an expansion turbine, and more particularly to a control device for an expansion turbine that is arranged in two stages in series and generates cooling.

[Prior art]

Conventionally, when controlling such a series two-stage expansion turbine, the inlet temperature of the first expansion turbine 25 and the inlet pressure of the second expansion turbine 26 have been detected, as shown in FIG. Then, the turbine inlet valve 27 provided on the upstream side of the first expansion turbine 25 is controlled using the inlet temperature of the first expansion turbine 25 as a parameter, and the inlet pressure of the second expansion turbine 26 is sequentially increased. Expansion turbines 25 and 26 were started. In addition, when stopping the expansion turbines 25 and 26, normally the inlet pressure is gradually lowered, but in an emergency, the air pressure of the actuator that operates the turbine inlet valve 27 is rapidly lowered using a solenoid valve to stop the expansion turbine 25.・26 was stopped.

However, by increasing the setting of the turchinine pressure regulator from O as in the above conventional method, the turbine inlet valve 2
7 to start the expansion turbines 25 and 26, the valve opening when the turbine starting torque is exceeded and the rotor begins to rotate is different from the valve opening when setting the target intermediate stage pressure. Therefore, when the turbine is started, the large mouth valve of the turbine hunts, causing large pressure fluctuations. Therefore, the rotation of the expansion turbine fluctuates, resulting in a problem of lowering the reliability of the expansion turbine. In addition, when stopping the expansion turbine by lowering the set value of the turbine intermediate stage pressure as in the above conventional method, the turbine intermediate stage pressure was fed back to control the turbine inlet valve. There is a risk of hunting. Therefore, there was a problem in that it was difficult to stop the rotor smoothly, and the reliability of the expansion turbine was reduced.

[Object of the Invention] The present invention has been made in consideration of the above-mentioned conventional problems, and provides optimal control of an expansion turbine not only during normal operation of the expansion turbine but also during startup and shutdown. Accordingly, an object of the present invention is to provide an expansion turbine control device that can improve the reliability of the expansion turbine.

[Structure of the invention]

In order to achieve the above object, an expansion turbine control device according to the present invention is provided with a turbine inlet valve provided on the upstream side of the expansion turbine to adjust the flow rate of gas transported to the expansion turbine. a first function generator that controls the turbine inlet valve when the expansion turbine is started; a pressure regulator that controls the turbine inlet valve during steady operation of the expansion turbine; and a pressure regulator that controls the turbine inlet valve when the expansion turbine is normally stopped. a second function generator for controlling the turbine inlet valve at the time of emergency stop of the expansion turbine; and a signal output from any of the three function generators or a pressure regulator. A signal switching device is provided to output a signal to the turbine inlet valve according to the operating state of the expansion turbine. The rotor is characterized in that it is configured so that the rotor can be stopped smoothly at the time of stoppage or emergency stop of the expansion turbine.

〔Example〕

An embodiment of the present invention will be described below based on FIGS. 1 to 4.

As shown in FIG. 1, in order from the upstream side of the gas passage 1, a temperature detector 2 detects the temperature at the inlet of the expansion turbine, a turbine inlet valve 3 adjusts the flow rate of gas transported to the expansion turbine, and a first expansion turbine. 4, a pressure detector 5 that detects the pressure between the expansion turbines, and a second expansion turbine 6 are provided. The temperature sensor 2 is connected to a pressure regulator (PIC) 7 and a first function controller (f(T,P)) 8 that controls the expansion turbine when the expansion turbine is started. Also,
The pressure detector 5 is connected to the pressure regulator 7 and the first function generator 8, and is also connected to a pressure switch (PA') 9. A first signal switch (SSI) 10 is provided which outputs either a signal from the first function generator 8 or a signal from the pressure regulator 7 based on the signal from the pressure switch 9.

The signal from this first signal switch 1-0 is used to control the expansion turbine when the expansion turbine is normally stopped.
f(t)1) 12 or a third function generator (f
(t)2) A second signal switch (SS2) 11 is provided which outputs a signal from 13 in response to an input signal from the stop switch 19 or the emergency stop switch 20.

Further, a turbine rotation speed controller 15 which controls the turbine rotation speed by a signal from this second signal switch 11 or a signal from turbine speed detectors 17 and 18 provided in both expansion turbines 4 and 6 is provided. A third signal switch 14 is provided which outputs a signal from the turbine inlet valve 16 to the turbine inlet valve 3 to adjust the opening degree of the turbine inlet valve 3. Furthermore,
The third signal switch 14 is connected to the pressure regulator 7, the second function generator 12, the third function generator 13, and the turbine speed regulators 15 and 16.

In the above configuration, the expansion turbine is controlled as follows.

First, when both expansion turbines 4 and 6 are started, an input signal from the first function generator 8 is output from the first signal switch 10 to the second signal switch 11 in response to a signal from the pressure switch 9. . As shown in FIG. 2, this signal increases the output when the temperature detected by the temperature sensor 2 reaches a certain temperature (a in the figure), and then increases the output when the temperature detected by the temperature sensor 5 reaches a certain temperature (a in the figure). When the intermediate pressure reaches a certain level (b in the diagram), the increase in output is stopped, and when the temperature reaches a certain level again (c in the diagram), the output is increased. This is a signal that repeats. Next, since both stop switches 19 and 20 are in the off state, the second function generator 12
The output signals from the third function generator 13 and the second signal switch 1
1, but the output signal from the first signal switch 10 is sent from the second signal switch 11 to the turbine inlet valve 3 via the third signal switch 14.

On the other hand, when the predetermined pressure is reached, the pressure switch 9
The signal from the pressure regulator 7 is output from the first signal switch 10 to the second signal switch 11 in accordance with the signal from the pressure regulator 7 .

Next, since both switches 19 and 20 are in the off state as described above, the second signal switch 11 is connected to the turbine inlet valve 3 from the first signal switch 10 via the third signal switch 14. An output signal is sent out.

By the way, when the stop switch 19 is turned on, the signal from the pressure regulator 7 is output from the first signal switch 10 to the second signal switch 11, or the signal from the first function generator 8 is output from the first signal switch 10 to the second signal switch 11. Even if , the signal from the second function generator 12 is output from the second signal switch 11 . As shown in FIG. 3, this signal is a signal that quickly reduces the output when the output is high, and gradually reduces the output when the output is low, that is, when the turbine inlet valve 3 is fully closed. Such a signal is output to the turbine inlet valve 3 via the third signal switch 14.

Therefore, since the large mouth valve 3 of the turbine is controlled without feeding back the turbine intermediate stage pressure until the expansion turbine stops, it is possible to prevent the pressure of the expansion turbines 4 and 6 from becoming excessive. Similarly, when the emergency stop switch 20 is turned on, the signal from the third function generator 13 is output from the second signal switch 11 regardless of the signal from the first signal switch 10. Ru. As shown in FIG. 4, this signal is a signal that performs the same control as the second function generator 12, but the output is controlled to be lowered in a shorter time than this signal.

By outputting such a signal to the turbine inlet valve 3, it is possible to prevent the pressure in the expansion turbines 4 and 6 from becoming excessive.

Note that the signal output from the third signal switch 14 to the turbine inlet valve 3 is transmitted to the turbine rotation speed controllers 15 and 16, the second function generator 12, the third function generator 13, and the pressure controller 7.
is not selected, it is input to each device as a feedback signal (fm). As a result, each of the above-mentioned devices can be synchronized to output at the same rate as the opening degree of the turbine inlet valve 3, so it is possible to prevent delays in operating time when each device is selected. . Therefore, the expansion turbines 4 and 6 can be controlled continuously.

Further, the third signal switch 14 and the second signal switch 11,
Signals from turbine speed controllers 15 and 16 are input,
One of the signals is selected depending on the conditions and output to the turbine inlet valve 3. However, in the present invention, the third signal switch 1
4 and the turbine speed controllers 15 and 16 are not necessarily required, and the third signal switch 14 and the turbine speed controllers 15 and 16 are not necessarily required.
16, the same i control as above can be performed. In this case, the pressure regulator 7 and the second
The feedback signal output to the third function generators 12 and 13 is the output signal from the second signal switch 11.

〔Effect of the invention〕

As described above, the expansion turbine control device according to the present invention includes a first function generator that controls the turbine inlet valve during startup of the expansion turbine, and a pressure regulator that controls the turbine inlet valve during steady operation of the expansion turbine. a second function generator that controls the turbine inlet valve during a normal stop of the expansion turbine; a third function generator that controls the turbine inlet valve during an emergency stop of the expansion turbine; This configuration includes a signal switching device that outputs either the signal output from the pressure regulator or the signal output from the pressure regulator to the turbine inlet valve depending on the operating state of the expansion turbine.

Therefore, hunting of the turbine inlet valve can be prevented when the expansion turbine is started, and the rotor can be stopped smoothly during the normal stop of the expansion turbine and during the emergency stop of the expansion turbine. The expansion turbine can be optimally controlled not only during operation but also when starting and stopping.

As a result, the reliability of the expansion turbine can be improved.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram showing an embodiment of the present invention, Fig. 2 is a graph showing the relationship between time and output in the first function generator, and Fig. 3 is a graph showing the relationship between time and output in the second function generator. FIG. 4 is a graph showing the relationship between time and output in the third function generator, and FIG. 5 is a schematic configuration diagram of a conventional expansion turbine control device! 3 is a turbine inlet valve, 7 is a pressure regulator, 8 is a first function generator, 10 is a first signal switch (signal switch), 11 is a second signal switch (signal switch), 12 is a second signal switch function generator,
13 is a third function generator. Patent applicant: Kobe Steel, Ltd. Figure 2 Figure 3 Figure 4 Figure 0 Cocoon Figure 5

Claims (1)

[Claims] 1. In an expansion turbine control device in which a turbine inlet valve for regulating the flow rate of gas transported to the expansion turbine is provided on the upstream side of the expansion turbine, a first function is generated for controlling the turbine inlet valve at the time of startup of the expansion turbine. a pressure regulator that controls the turbine inlet valve during steady operation of the expansion turbine; a second function generator that controls the turbine inlet valve during normal stop of the expansion turbine; and a second function generator that controls the turbine inlet valve during emergency stop of the expansion turbine. A third function generator to control and any signal output from the three function generators,
1. A control device for an expansion turbine, comprising: a signal switching device that outputs a signal output from a pressure regulator to a turbine inlet valve depending on an operating state of the expansion turbine.