JPH04298602A - Steam turbine starting equipment - Google Patents

Abstract

PURPOSE:To shorten the time required for starting until a steam turbine reaches target load by supplying low temperature steam to a low pressure turbine after a boiler is ignited to start the steam turbine, and by supplying steam to an intermediate pressure turbine and a high pressure turbine sequentially in accordance with rise of boiler steam temperature. CONSTITUTION:A high pressure bypass control valve 15 which is opened or closed to control the amount of main steam which is bypassed from an inlet of a high pressure turbine 3 to a boiler 1 when a steam turbine is started in accordance with the temperature of main steam is installed in a high pressure bypass pipe 14. Also, an intermediate pressure bypass control valve 17 which is opened or closed to control the amount of reheated steam at an inlet of an intermediate pressure turbine 6 which is bypassed to an outlet and supplied to a low pressure turbine 8 when the steam turbine is started in accordance with the temperature of reheated steam at the inlet of the intermediate pressure turbine 6 is installed in an intermediate pressure bypass pipe 16. Since it is possible to supply low temperature steam to the low pressure turbine 8 after the boiler 1 is ignited to start the steam turbine and to the intermediate pressure turbine 6 and the high pressure turbine 3 sequentially in accordance with rise of steam temperature of the boiler 1, the time required for starting can be shortened.

Description

[Detailed description of the invention]

[Object of the invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam turbine starting device for starting a steam turbine of a power plant in a short time.

0002

2. Description of the Related Art FIG. 5 shows a conventional steam turbine starting device for a power plant.

[0003] Steam generated in the boiler 1 is introduced into a high pressure turbine 3 through a main steam pipe 2, and drives the high pressure turbine 3. The steam whose pressure and temperature have been lowered by doing work in the high-pressure turbine 3 passes through the high-pressure turbine outlet steam pipe 4 and is led to the boiler 1 again.

[0004] Steam whose temperature has been raised by being reheated in the boiler 1 is led to an intermediate pressure turbine 6 through a reheat steam pipe 5, and drives the intermediate pressure turbine 6. Steam whose pressure and temperature have been reduced by performing work in the intermediate pressure turbine 6 is introduced into the low pressure turbine 8 through the connecting steam pipe 7, and drives the low pressure turbine 8.

[0005] A large steam turbine usually has two low-pressure turbines 8, and there are two types of steam turbines, one having two connecting steam pipes 7, and the other having a structure in which one connecting steam pipe branches.

[0006] Thereafter, the outlet steam of the low pressure turbine 8 is guided to a condenser 9.

[0007] A main steam stop valve 10 and a steam control valve 11 are installed at the inlet of the high pressure turbine 3.
A reheat steam stop valve 12 is installed at the inlet. Furthermore, a generator 13 is connected to the main shaft of the turbine.

[0008] Next, the procedure for starting the turbine from a stopped state until it ventilates and reaches the rated power generation output will be explained.

First, the boiler 1 is ignited to raise the temperature of the feed water in the boiler 1 and generate steam. The condition for ventilating the turbine is that the steam generated in the boiler 1 must reach a predetermined temperature. The reason for this is to reduce the difference between the metal temperature of the turbine parts, especially the turbine rotating shaft, and the steam temperature to suppress the thermal stress generated during ventilation to within limits.

After the steam generated by the boiler 1 reaches a predetermined temperature, the steam is vented to the high-pressure turbine 3. Prior to this venting, the steam control valve 11 and the reheat steam stop valve 12 are fully opened. Gradually open the main steam stop valve 10. As a result, steam is vented to the high-pressure turbine 3, and the high-pressure turbine 3 starts rotating. After the turbine starts rotating, in low-load operation of 10% or less of the rated power output, the main steam stop valve 1
Operation is performed with the steam amount controlled by 0. Since this amount of steam is small, many methods are used to provide a small sub-valve inside the main steam stop valve 10 and use this sub-valve to control the amount of steam with high precision.

In order to perform load operation of 10% or more of the rated power generation output, a steam control valve 11 is used instead of the main steam stop valve 10.
Switch to operation where the amount of steam is controlled by restricting the amount of steam. This steam control valve 11 is composed of several valves, and is capable of controlling the flow rate of a large amount of steam with high precision. This switching operation is called FA/PA switching (switching from full-circle injection to partial injection). After switching between FA and PA, the steam control valve 11 is gradually opened to increase the load.

[0012] Nowadays, the demand for electricity is high during the day and low at night, and the difference in demand has been increasing in recent years. For this reason, the steam turbines for thermal power generation mentioned above are operated at rated load during the day and are stopped at night, which is called DSS.
Many operations (Daily Start Stop operations) are being carried out.

[0013]

However, the conventional steam turbine starting device described above has the following problems.

[0014] In DSS operation, there is a strong need to shorten the startup time of the steam turbine, but there is a problem in that conventional steam turbine startup devices cannot adequately respond to DSS operation. That is, in this case, since the stop time from decoupling to the next start-up is usually about 8 hours, which is a short time, the temperature of the rotating shaft of the high-pressure turbine 3 and the rotating shaft of the intermediate-pressure turbine 6 is high. Therefore, it is necessary to ignite the boiler 1 and wait for ventilation until a predetermined steam temperature is reached.

To explain this with reference to FIG. 6, the boiler 1 is ignited at time t0, and vented when the main steam temperature T reaches a predetermined steam temperature at time t1. The time required from ignition to ventilation of the boiler 1 is about 1 hour. Next, the turbine is ventilated, and the rotational speed N of the turbine gradually increases until t.
The rated rotation speed is reached at point 2. Subsequently, at time t3, it joins the load, and as the load P increases, at time t4, FA・
Switch the PA. Thereafter, the load P further increases and reaches the rated load at time t5.

By the way, when the turbine is vented while the steam temperature of the boiler 1 is low, the metal temperature of the rotating shafts of the high-pressure turbine 3 and the intermediate-pressure turbine 6 is cooled immediately after the venting, and then the boiler 1 is raised. The temperature of the steam also increases due to the increased temperature, and as a result, the temperature of the metal of the rotating shaft also increases. In this way, the metal temperature of the rotating shaft of the turbine once drops immediately after ventilation, and then rises to the rated temperature, which increases the temperature change width and temperature change rate during the startup process, and the generated thermal stress increases. This will limit the rate of increase. Therefore, as a result, it takes longer to reach the rated load.

As described above, the conventional apparatus has a problem in that it takes a long time from ignition of the boiler until the target load is reached when the apparatus is restarted after a nighttime shutdown.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a steam turbine starting device that can shorten the time required for starting the boiler from ignition to reaching the target load.

[Configuration of the invention]

[Means for Solving the Problems] The present invention provides a high-pressure turbine that is driven by steam generated in a boiler, and an intermediate-pressure turbine that reheats the outlet steam of the high-pressure turbine in the boiler and is driven by the reheated steam. In a steam turbine startup device for thermal power generation equipment, which consists of a low-pressure turbine driven by the outlet steam of this intermediate-pressure turbine and a generator that converts the motive power of these turbines into electrical output, the main steam at the inlet of the high-pressure turbine is A high-pressure bypass pipe that connects the pipe and the outlet steam pipe of the high-pressure turbine, and a system that opens and closes the amount of main steam bypassed from the inlet of the high-pressure turbine to the boiler depending on the temperature of the main steam when the steam turbine is started. a high-pressure bypass control valve for controlling; an intermediate-pressure bypass pipe that connects the reheat steam pipe at the inlet of the intermediate-pressure turbine and the outlet of the intermediate-pressure turbine; An intermediate pressure bypass control valve is provided for controlling the opening and closing of the amount of reheated steam at the inlet of the turbine bypassed to the outlet of the intermediate pressure turbine and vented to the low pressure turbine in accordance with the temperature of the reheated steam at the inlet of the intermediate pressure turbine. This is how it was done.

[0020]

[Operation] With the above configuration, when the steam turbine is started in a hot state, after the boiler is ignited, the low-temperature main steam is bypassed to the boiler and reheated, and when the reheat temperature reaches a relatively low predetermined temperature. , the reheated steam is vented to the low pressure turbine for startup. Further, as the steam temperature of the boiler increases, the intermediate pressure turbine and the high pressure turbine are sequentially vented and operated. As a result, the reheated steam immediately after ignition of the boiler can be vented when the temperature is relatively low, thereby reducing the time required for startup.

[0021]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a steam turbine starting device showing a first embodiment of the present invention. The same reference numerals as in FIG. 5 indicate the same or equivalent parts. The differences from FIG. 5 include a high-pressure bypass pipe 14 that connects and bypasses the main steam pipe 2 and the high-pressure turbine outlet steam pipe 4, a high-pressure bypass control valve 15, and a high-pressure bypass control valve 15 that connects the reheat steam pipe 5 and the outlet of the intermediate-pressure turbine 6. It is equipped with an intermediate-pressure bypass pipe 16 for bypassing, an intermediate-pressure bypass control valve 17, a main steam thermometer 18, and a reheat steam thermometer 19.

Next, the procedure for starting the turbine will be explained with reference to the starting pattern of this embodiment shown in FIG. First, when starting up in a hot state after shutting down at night, boiler 1 is set to t0.
At this point, the steam is ignited, the steam control valve 11 is opened, and the reheat steam stop valve 12 is fully closed. Also, keep all other valves fully closed. By the way, at this time, the reheat steam stop valve 12 was also open in the conventional startup explained in FIG.

Immediately after the boiler 1 is ignited and low-temperature steam is generated, the high-pressure bypass control valve 15 is opened, and this low-temperature steam is returned to the boiler 1 and reheated. This reheated steam is also initially at a low temperature, but its temperature is raised to about the metal temperature of the rotating shaft of the low-pressure turbine 8 (about 200° C. at the inlet) in a short time.

After the reheated steam reaches a temperature of about 200° C. as measured by the reheated steam thermometer 19, the intermediate pressure bypass control valve 17 is immediately opened at time t1, and the reheated steam is transferred to the intermediate pressure turbine 6. The low pressure turbine 8 is vented through the outlet. At this time, the opening degree of the intermediate pressure bypass control valve 17 is controlled while monitoring the increase in the turbine rotational speed N. The capacities of the high-pressure bypass control valve 15 and the intermediate-pressure bypass control valve 17 are determined so that the steam vented to the low-pressure turbine 8 increases the rotational speed N of the turbine to the rated rotational speed. This turbine speed up usually takes 20 to 30 minutes. During this period as well, the temperature of the main steam increases with time. Furthermore, the main steam is bypassed by the high-pressure bypass control valve 15 and the flow rate of the main steam is increased, so that the heat transfer coefficient becomes faster and the temperature of the main steam increases faster.

When the turbine rotational speed N reaches the rated rotational speed at time t2, and the main steam temperature T and the reheated steam temperature measured by the main steam thermometer 18 are equal to the metal temperature of the rotating shaft of the high-pressure turbine 3 and the intermediate-pressure turbine The metal temperature of the rotating shaft of No. 6 (approximately 30
(approximately 0°C), the high pressure bypass control valve 15
Reheat steam stop valve 1 while controlling the rotation speed by controlling the opening of
Gradually open 2 until fully open. At the same time, the intermediate pressure bypass control valve 17 is gradually closed to be fully closed.

Subsequently, the sub-valve of the main steam stop valve 10 is gradually opened. At the same time, the high pressure bypass control valve 15 is gradually closed to be fully closed. Are the above operations performed prior to annexation?
Or, whether it will be carried out at the initial load after joining, which is selected depending on the temperature of the steam generated in the boiler 1. That is, the main steam thermometer 18 and the reheat steam thermometer 19 are monitored, and when the temperature approaches the metal temperature of the rotating shaft of the high-pressure turbine 3 and the metal temperature of the rotating shaft of the intermediate-pressure turbine 6, the above-mentioned valve is activated. Perform the switching operation.

After this valve switching is completed, the conventional start-up operation is performed, and as explained in FIG.
A is switched to control using the steam control valve 11,
The output is increased until the target load (usually the rated load) is reached at time t5.

As can be seen from the hot state starting pattern using the steam turbine starting device according to the present embodiment described above, when compared with FIG. Since ventilation is possible, the time t1 required for ventilation is short. Furthermore, since the low-pressure turbine 8 can be increased to its rated rotational speed by ventilation, it can be used immediately. Furthermore, the main steam is bypassed by the high pressure bypass control valve 15 when starting the turbine. This increases the flow rate of the main steam of the boiler 1, increasing the heat transfer coefficient and increasing the temperature of the main steam faster than before. In this way, the time required for starting up the boiler 1 from ignition to reaching the rated load is shortened.

Next, a second embodiment of the present invention will be described with reference to FIG.

The difference from FIG. 1 is that the intermediate pressure bypass control valve 1
A piping system 20 connected to the condenser 9 is provided upstream of the condenser 7, and a low pressure bypass control valve 21 is provided in the middle thereof.

In this embodiment, the high pressure bypass control valve 15 of the operating procedure shown in FIG.
In addition to opening the intermediate pressure bypass control valve 17, the low pressure bypass control valve 21 is opened. As a result, some steam is vented from the intermediate pressure bypass control valve 17 to the low pressure turbine 8 through the outlet of the intermediate pressure turbine 6, and at the same time, steam is caused to flow from the low pressure bypass control valve 21 to the condenser 9.

In this embodiment, the amount of feed water and steam passing through the boiler 1 can be increased. As a result, the flow rate of the feed water passing through the boiler tube becomes faster, resulting in a larger heat transfer coefficient and a faster temperature rise rate of the boiler. Therefore, the temperature of the steam increases quickly, and the time required for startup can be further shortened compared to the embodiment shown in FIG.

FIG. 4 shows a third embodiment of the present invention.

This embodiment includes a high-pressure bypass stop valve 22 upstream of the high-pressure bypass control valve 15 and an intermediate-pressure bypass stop valve 23 upstream of the intermediate-pressure bypass control valve 17.

In this embodiment, with the high pressure bypass control valve 15 and the intermediate pressure bypass control valve 17 fully closed during load operation, the high pressure bypass stop valve 22 and the intermediate pressure bypass stop valve 2 are closed.
3 and fully closed. As a result, leakage of steam to each bypass system can be reliably prevented.

[0037]

As explained above, according to the present invention, when starting a steam turbine in a hot state, after the boiler is ignited, low-temperature steam is vented to the low-pressure turbine to start the turbine, and as the steam temperature of the boiler rises. The intermediate pressure turbine and high pressure turbine are vented sequentially. As a result, the time required for startup from boiler ignition to target load can be shortened compared to the conventional method.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a steam turbine starting device showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a startup pattern of the device.

FIG. 3 is a configuration diagram of a steam turbine starting device showing a second embodiment of the present invention.

FIG. 4 is a configuration diagram of a steam turbine starting device showing a third embodiment of the present invention.

FIG. 5 is a configuration diagram of a steam turbine starting device showing a conventional example.

FIG. 6 is an explanatory diagram showing a startup pattern of the device.

[Explanation of symbols]

1 Boiler 2 Main steam pipe 3 High pressure turbine 4 High pressure turbine outlet steam pipe 6 Medium pressure turbine 8 Low pressure turbine 9 Condenser 11 Steam control valve 14 High pressure bypass pipe 15 High pressure bypass control valve 16 Medium pressure bypass pipe 17 Medium pressure bypass control valve

Claims (1)

[Claims] Claim 1: A high-pressure turbine driven by steam generated in a boiler, an intermediate-pressure turbine in which the outlet steam of the high-pressure turbine is reheated in the boiler and driven by the reheated steam, and an outlet steam of the intermediate-pressure turbine. In a steam turbine startup device for thermal power generation equipment, which is composed of a low-pressure turbine driven by a low-pressure turbine and a generator that converts the power of these turbines into electric output, a high-pressure bypass pipe connecting the steam pipe; and a high-pressure bypass pipe disposed in the high-pressure bypass pipe for controlling the opening and closing of the amount of main steam to be bypassed from the inlet of the high-pressure turbine to the boiler at the time of starting the steam turbine according to the temperature of the main steam. a high-pressure bypass control valve; an intermediate-pressure bypass pipe that connects a reheat steam pipe at the inlet of the intermediate-pressure turbine and an outlet of the intermediate-pressure turbine; an intermediate-pressure bypass control valve for controlling opening and closing of an amount of reheated steam at an inlet of the intermediate-pressure turbine to be bypassed to an outlet of the intermediate-pressure turbine and vented to the low-pressure turbine according to a temperature of reheated steam at an inlet of the intermediate-pressure turbine; A steam turbine starting device characterized by comprising: