JPH0246762B2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains] Two steam supply systems each having a main steam stop valve and a steam control valve as a pair are arranged, and the steam supplied from the steam source is divided into two series. The present invention relates to a method for starting a steam turbine that is controlled and operated by a control valve.

[Prior art and its problems]

Generally, when starting a steam turbine, the main steam stop valve is opened first, and then the steam control valve is opened and the opening degree of the steam control valve is controlled to increase the speed of the turbine. However, for inlet valves with low inlet pressure such as those in geothermal turbines, the diameter of the valve is 300 to 700 mm, so a butterfly valve is often used as a steam control valve. A gap is created between the main steam stop valve and the valve body, and when the main steam stop valve opens, steam flows into the turbine due to leakage from the butterfly valve, which acts as a steam control valve.
Since this increases the rotational speed of the turbine, there is a need for a startup method that can control the turbine speed more stably.

Figures 1 to 3 show conventional embodiments, where Figure 1 is a control system diagram of the main parts of the steam turbine, Figure 2 is a sectional view of the main parts of the inlet valve in Figure 1, and Figure 3 is the FIG. 2 is a diagram showing the starting characteristics of the turbine shown in FIG. 1; In the figure, 1 is a steam turbine, and the steam turbine 1 is provided with two steam supply systems in which a main steam stop valve and a steam control valve are paired. 10 is the first steam supply system, and 20 is the Two series are shown. Reference numeral 11 designates a main steam stop valve provided in the first series 10, 12 a steam control valve paired with the main steam stop valve 11, and 13 a pipe line thereof. 21 is a main steam stop valve provided in the second train 20, 22 is a steam control valve that pairs with the main steam stop valve 21, and 23 is a pipe line thereof. 2 is a governor impeller of a rotation speed detector directly connected to the rotor shaft of the steam turbine 1; 3 is a rotation speed setting device; 4 is a secondary oil pressure setting device for the steam control valve 12; 5
is a secondary oil pressure setting device for the steam control valve 22. Note that 6 represents a generator and 7 represents a condenser.

Next, a method of starting the steam turbine 1 using this device will be explained. Steam supplied from a steam source (not shown) flows through the first series of pipes 13 and the second series of pipes 23, and at the same time flows from the main steam stop valves 11 and 12, which are fully opened by the opening operation, to the steam control valves 12 and 22. be guided. The rotation speed setting device 3 is manually operated so that the steam control valves 12 and 22 can be slightly opened. As a result, the secondary oil pressure is set in the pipes 14 and 15 of the secondary oil pressure setting devices 4 and 5, and the steam control valve 1 is set by the oil pressure.
2 and 22 open slightly, and the turbine 1 starts rotating.
When the rotational speed of the turbine 1 increases to about 1000 rpm, the operation of the rotational speed setting device 3 is temporarily stopped, and the turbine 1 is warmed up. After the warm-up operation is completed, the rotational speed of the turbine 1 is further increased. This is done by operating the rotational speed setting device 3 again as described above, and the rotational speed of the turbine 1 is set to the rated speed (50Hz).
(approximately 3000rpm for 60Hz, approximately 3600rpm for 60Hz)
After that, control operation of the steam control valve is shifted. As a result, primary oil pressure is established in the conduit 16 via the rotation speed detector 2 by the governor impeller directly connected to the rotor shaft, and the primary oil pressure is transmitted to the rotation speed setting device 3. When the load on the turbine 1 increases and the rotation speed decreases, the primary oil pressure decreases, and the secondary oil pressure setting devices 4 and 5 are operated via the lever 3a, and the secondary oil pressure pipes 14 and 15 are operated.
The oil pressure increases, increasing the opening angle of the steam control valves 12 and 22. Also, when the load on the turbine decreases and the rotational speed increases, the behavior is opposite to that described above.
As the secondary oil pressure decreases, the opening angles of the steam control valves 12 and 22 become smaller.

In the above startup method, the steam control valves 12, 2
As shown in Fig. 2, 2 is a butterfly valve with a diameter of about 700 mm whose valve body rotates in the direction of arrow 25, so the main steam stop valves 11 and 21 move in the direction of arrow 24 and the steam 26 is passed into the body 27,
In butterfly valves, even when the valve body is closed, steam leaks from the gap δ between the valve body and the valve body, and the steam is transferred to the turbine 1.
and increases the rotational speed of the turbine 1. This rising speed is about 2000 rpm as shown by the dotted line 31 in FIG. 3, which exceeds the heat soak rotation speed of 1000 rpm shown at 32 necessary for warm-up operation, and the disadvantage is that the heat soak rotation speed cannot be controlled.

[Purpose of the invention]

An object of the present invention is to provide a method for starting a steam turbine, which eliminates the above-mentioned drawbacks, and allows stable turbine speed control that allows a heat soak rotational speed to be obtained and reliable warm-up operation. shall be.

[Key points of the invention]

According to the present invention, the above object is achieved by arranging two steam supply systems each having a main steam stop valve and a steam regulating valve as a pair, and controlling the steam supplied from the steam source by the steam regulating valve of each series. In a steam turbine that is operated as a steam turbine, the main steam stop valve of the first series is fully opened, and the steam control valve of this series is slightly opened so that the rotational speed of the turbine reaches a warm-up operation speed lower than the rated rotational speed. After the warm-up operation is completed, the steam control valve is further opened to increase the rotational speed of the turbine, and when the rotational speed of the turbine exceeds a predetermined value, the main steam of the second train is Fully open the stop valve, and after fully opening the main steam stop valve, open the steam control valves of the first and second series to increase the rotational speed of the turbine and shift to controlled operation using the steam control valves. It is achieved by doing.

[Embodiments of the invention]

Embodiments of the present invention will be described below based on the drawings. 4 and 5 show an embodiment of the present invention, and FIG. 4 is a control system diagram of the main parts of the steam turbine,
FIG. 5 is a diagram showing the starting characteristics of the steam turbine shown in FIG. 4. In the figure, the same components as those shown in FIG. 1 are given the same reference numerals and their explanations will be omitted. The steam turbine 1 is provided with two steam supply systems, 10 is the first system, 30 is the second system, and 31 is the main steam stop valve of the second system. 32 is the main steam stop valve switching device of the second series;
The main steam stop valve switching device 32 is connected to the rotation speed detector 2
The main steam stop valve 31 is set to be able to be opened when the turbine 1 reaches a rotational speed slightly higher than the heat soak rotational speed of 1000 rpm in response to a signal from the main steam stop valve 31. Reference numerals 34 and 35 designate secondary oil pressure setting devices, each of which has a built-in spring force (not shown) with a difference in spring force, and the secondary oil pressure setting device 35 of the steam control valve 22 is , the main steam stop valve switching device 32 is the main steam stop valve 3 of the second series.
It is adjusted so that the secondary oil pressure is set when the valve 1 is opened.

With the above configuration, the main steam stop valve 1 of the first series
Perform the opening operation in step 1. Steam from a steam source (not shown) is supplied to the steam control valve 12 by opening the main steam stop valve 11.
guided by. The rotation speed setting device 3 is manually operated so that the steam control valve 12 can be slightly opened. As a result, the pipe line 14 of the secondary oil pressure setting device 34 of the first series
The secondary oil pressure is set, the steam control valve 12 is slightly opened by the pressure oil, and the turbine 1 starts rotating. When the rotational speed of the turbine 1 increases to a heat soak speed of approximately 1000 rpm, the operation of the rotational speed setting device 3 is temporarily stopped, and the turbine 1 is warmed up. After the warm-up operation is completed, the rotation speed setting device 3 is further operated to increase the rotation speed of the turbine 1. At this time, the pipe line 1 of the secondary oil pressure setting device of the first series is
4, the rotational speed of the turbine 1 increases, and when the rotational speed of the turbine 1 reaches a point slightly higher than the heat soak rotational speed of 1000 rpm, the rotational speed detector 2 detects the preset rotational speed, and the rotational speed of the pipe 37 increases. The primary oil pressure is established, and the secondary oil pressure is set in the pipe line 36 of the main steam stop valve switching device 32 of the second series, and the main steam stop valve 31 of the second series is fully opened by the pressure oil.
After the main steam stop valve 31 is fully opened, the rotation speed setting device 3 is further operated to increase the rotation speed of the turbine 1. At this time, the secondary oil pressure is also set in the conduit 15 of the secondary oil pressure setting device 35 for the steam control valve, and the steam control valves 12 and 22 are both opened to increase the rotational speed of the turbine 1. When the rotational speed of the turbine 1 exceeds 90% of the rated speed, the control operation of the steam control valve is started.

In the above startup method, when the main steam stop valve 11 opens and steam is guided to the steam control valve 12, steam leaking from the gap between the valve body of the steam control valve 12 and the valve body flows into the turbine 1. However, the first
Since only the main steam stop valve 11 of the series is opened, the amount of steam flowing into the turbine 1 is small, and the rising speed of the turbine 1 is approximately 800 rpm, as indicated by the dotted line 51 in FIG. It can be lower than the heat soak rotation speed of 1000 rpm shown in . Furthermore, the main steam stop valve 3 of the second series
1 is opened, steam leaking from the gap between the valve body and the valve body of the steam control valve 22 in the series similarly flows into the turbine 1, but the rotational speed of the turbine 1 is already relatively high, and the comparison A large amount of steam flows into turbine 1.
Since the steam is flowing into the second series steam control valve 22,
Steam leaking from the turbine has almost no effect on increasing the rotational speed of the turbine 1. Therefore, after the main steam stop valve 31 is fully opened, the rotation speed setting device 3 is operated to open the steam control valves 12 and 22 to open the turbine 1.
The speed of the turbine 1 can be increased until the rotational speed of the turbine 1 reaches 90% of the rated speed, and the operation can be shifted to steam control valve control operation.

〔Effect of the invention〕

As described above, the present invention operates by fully opening the main steam stop valve of the first series and slightly opening the steam control valve of this series so that the rotational speed of the turbine reaches a warm-up operation speed lower than the rated rotational speed. After the warm-up operation is completed, the steam control valve is further opened to increase the rotational speed of the turbine;
When the rotational speed of the turbine exceeds a predetermined value, the main steam stop valve of the second series is fully opened, and after the valve is opened, both the steam control valves of the first and second series are opened. By increasing the rotational speed of the turbine and shifting control operation using the steam control valve, it is possible to control the turbine speed more stably than with conventional startup methods, achieving heat soak rotational speed and ensuring warm-up. A method for starting a steam turbine that can be operated can be provided.

[Brief explanation of the drawing]

Figures 1 to 3 show conventional embodiments, where Figure 1 is a control system diagram of the main parts of the steam turbine, Figure 2 is a sectional view of the main parts of the inlet valve in Figure 1, and Figure 3 is the Fig. 1 is a diagram showing the startup characteristics of the turbine, Figs. 4 and 5 show embodiments of the present invention, Fig. 4 is a control system diagram of the main parts of the steam turbine, and Fig. 5 is the diagram shown in Fig. FIG. 3 is a diagram showing the starting characteristics of the steam turbine shown in FIG. 1... Steam turbine, 10... First train, 1
1, 13...Main steam stop valve, 12, 22...Steam control valve, 30...Second series.

Claims (1)

[Scope of Claims] 1. Two series of steam supply systems each consisting of a main steam stop valve and a steam control valve are arranged, and the steam supplied from the steam source is controlled by the steam control valve of each series. In a steam turbine that performs a warm-up operation, the main steam stop valve of the first series is fully opened, and the steam control valve of this series is slightly opened so that the rotational speed of the turbine reaches a warm-up operation speed lower than the rated rotational speed. After the warm-up operation is completed, the steam control valve is further opened to increase the rotational speed of the turbine, and when the rotational speed of the turbine exceeds a predetermined value, the main steam stop valve of the second series is opened. After the main steam stop valve is fully opened, the steam control valves of the first and second series are opened to increase the rotational speed of the turbine and shift to a controlled operation using the steam control valves. A distinctive method of starting a steam turbine. 2. The method for starting a steam turbine according to claim 1, wherein the steam control valve is a butterfly valve.