JPH04140403A - Steam turbine device and cooling operation thereof - Google Patents

Abstract

PURPOSE:To decrease steam turbine metal temperature so as to shorten the cooling time to the temperature at which the turbine disassembling work is enabled, by lowering the temperature of the steam introduced into the steam turbine by utilizing the throttle effect of a steam governor valve, when the steam turbine is brought into stop. CONSTITUTION:The main steam supplied from a steam generator 1 is introduced into a steam turbine 3 through a steam governor valve 2. In this case, a throttle controller 4 for controlling the valve opening degree is installed on the steam governor valve 2, and a pressure controller 5 for increasing the pressure of the main steam is installed on the steam generator 1. The opening degree of the steam governor valve 2 is made smaller than the ordinary operation value by increasing the main steam pressure characteristic higher than the ordinary operation value during the steam turbine stop process. Accordingly, the throttle effect of the steam governor valve 2 is improved, and the temperature of the steam which is expanded after passing through the steam governor valve 2 is lowered. Accordingly, the steam whose temperature is lowered is introduced into the steam turbine 3, and the metal temperature of the steam turbine 3 is lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a steam turbine device, and in particular, to a cooling operation suitable for stopping a steam turbine while cooling it when stopping the steam turbine for periodic inspection or the like. Regarding the method.

[Conventional technology]

When regularly inspecting a steam turbine, it is necessary to cool the metal temperature of the steam turbine, which has already risen to 500 to 600 degrees Celsius, to about 150 degrees Celsius, which is workable. What are the cooling methods that have been used in the past?

The rotating steam turbine was first stopped and left to cool naturally. but.

This natural cooling takes time and could lead to social problems in situations where power supplies are tight as has been the case in recent years. Therefore, conventionally, as described in Japanese Patent Publication No. 61-5523, for example, after the steam turbine is stopped, cooling air is introduced into the steam turbine to forcibly cool the steam turbine.

[Problem to be solved by the invention]

In the above-mentioned conventional technology, cooling air is introduced into the steam turbine after the steam turbine is stopped to perform forced cooling, but this forced cooling also suddenly pumps cold air at 500°C.
If introduced into a steam turbine at ~600°C, the steam turbine will be damaged due to thermal stress, etc., so it is recommended to warm the cooling air to some extent before introducing it into the steam turbine, or to allow it to cool naturally for a while after the steam turbine is stopped. After that, measures such as forced cooling are required. this is,
This is because the conventional approach to cooling a steam turbine only considered cooling after the rotation of the steam turbine was stopped.

An object of the present invention is to stop the steam turbine while cooling it in the process of stopping the steam turbine.

It is an object of the present invention to provide a steam turbine device and a cooling operation method thereof that can lower the temperature when stopped by about 100° C. than before.

[Means to solve the problem]

The above purpose is to reduce the temperature of the steam introduced into the steam turbine using the throttling effect of the steam control valve when stopping the steam turbine, and to allow the steam with this reduced temperature to flow into the steam turbine. And it will be achieved.

[Effect]

It is a well-known law of nature that when a high-pressure gas is expanded through a throttle valve, the temperature of the gas decreases. The present invention attempts to cool the steam turbine by utilizing this natural law.

In other words, when the steam turbine is stopped, the steam introduced into the steam turbine is expanded to lower the steam temperature, and the lower temperature steam is passed through the steam turbine to lower the metal temperature of the steam turbine. . By operating in this way when the steam turbine is stopped, the
It becomes possible to stop the steam turbine at a temperature as low as ℃.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a configuration diagram of a steam turbine apparatus according to an embodiment of the present invention. Main steam from a steam generator 1 is introduced into a steam turbine 3 via a steam control valve 2. The steam control valve 2 is provided with an aperture control device 4 that controls the valve opening degree, and the steam generator 1 is provided with a pressure control device W5 that increases the pressure of main steam.

The opening degree of the steam control valve 2 is determined by the main steam pressure and the main steam temperature, but the main steam pressure is particularly dominant.When operating at a certain specified steam amount, if the main steam pressure is high, the steam control valve 2 is determined by the main steam pressure and the main steam temperature. The opening degree of the valve 2 is small, and if the main steam pressure is low, the opening degree becomes large.

In this embodiment, by making the main steam pressure characteristic higher than the normal operating value (increasing the pressure) during the steam turbine shutdown process, the opening degree of the steam control valve 2 becomes smaller than the normal operating value. Therefore, the throttling effect of the steam control valve 2 is enhanced, and the temperature of the steam expanded through the steam control valve 2 is reduced. By introducing this steam whose temperature has been reduced into the steam turbine 3, the metal temperature of the steam turbine 3 is reduced.

Conventionally, the main steam pressure has been determined by considering the operating efficiency of the plant. In particular, in the normal load operation zone (minimum load to rated load), the main steam pressure is changed to minimize the throttling effect of the steam control valve 2, and the opening degree of the steam control valve 2 is
During this time, it is customary to maintain a substantially constant opening degree.

Normally, during variable pressure operation, the opening degree of the steam regulator valve 2 is approximately constant, so the throttling characteristics of the steam regulator valve 2 are constant, and the high-pressure turbine inlet steam temperature is not affected by the throttle of the steam regulator valve 2. Ta.

However, in this embodiment, the main steam pressure characteristics are changed during turbine cooling operation to increase the pressure, and the opening degree of the steam control valve 2 is changed from that during normal operation to reduce the opening degree, thereby increasing the throttling effect. This reduces the turbine inlet steam temperature. Therefore, when the steam turbine 3 is stopped, its metal temperature is about 400° C., which is about 100° C. lower than before, so it can be cooled down in a short time even if it is naturally cooled thereafter. Furthermore, if the turbine is forcibly cooled after the turbine is stopped, the temperature can be lowered to a level that allows the turbine to be disassembled in a shorter time.

FIG. 2 is a comparative illustration of normal operation and cooling operation according to an embodiment of the present invention. During normal operation, the main steam pressure transformation pattern is the lowest pressure (for example,
80 kg/cli-g) is constant, the rated pressure (for example, 247 kg/csf-g) is operated from B% load to rated load, and the range from A% load to B% load is a so-called transformed pressure operation range. In FIG. 2, the solid line is the characteristic of the steam control valve opening and the high pressure turbine inlet steam temperature. These are the same characteristics as the transformer operation pattern that has been implemented in the past.

On the other hand, what is shown by the broken line is the main steam pressure change pattern when performing the cooling operation in this embodiment. According to this, the minimum pressure from no load to A% load is 8 during normal operation.
0kg/d”g, whereas in this example, it is 160
kg/dg, and the steam control valve opening is narrower than during normal operation. This increases the throttling effect of the steam control valve and lowers the high-pressure turbine inlet steam temperature. Therefore,
When the load is lowered from the rated load and the train is disconnected, the steam turbine cooling operation is such that the high pressure turbine inlet steam temperature is continuously lower than during normal operation from load B% to no load (detraining), and the high pressure turbine metal temperature becomes lower.

Here, the higher the minimum steam pressure during cooling operation, the greater the throttling effect of the steam regulating valve, and the higher the cooling effect.However, if the opening degree of the steam regulating valve is throttled too much, the steam turbine It becomes impossible to control the speed (load) of the engine. Therefore, as shown in FIG. 3, when the steam control valve is throttled down to a certain specified opening, the minimum pressure is controlled to be constant at that point. In other words, when the load is 0% or less, constant pressure control is performed.

〔Effect of the invention〕

According to the present invention, since the steam turbine metal temperature can be lowered to some extent during the process of stopping the steam turbine, there is an effect that the cooling time to a temperature that makes it possible to disassemble the turbine is shortened.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a steam turbine apparatus according to an embodiment of the present invention, and FIGS. 2 and 3 are comparative illustrations of a normal operation and a cooling operation according to an embodiment of the present invention. 1... Steam generator, 2... Steam control valve, 3...
Steam turbine, 4... Throttle control device, 5... Pressure control device.

Claims (1)

[Claims] 1. In a steam turbine that performs work by introducing steam through a steam control valve from a steam inlet and passing the steam through a steam outlet, when the steam turbine is stopped, the main steam pressure is increased to A steam turbine apparatus comprising a steam generator that lowers the temperature of the steam by a throttling effect of a steam control valve and then introduces the steam into the steam inlet. 2. In a steam turbine that performs work by introducing main steam into the interior from the steam inlet and discharging it from the steam outlet, when the steam turbine is stopped, the main steam is throttled to lower the steam temperature by the throttling effect, and then the steam is A steam turbine device comprising a steam control valve for introducing steam into an inlet. 3. In a steam turbine that performs work by introducing main steam into the interior from a steam inlet and discharging it from a steam outlet, a steam generator that increases the pressure of the main steam when the steam turbine is stopped, and a steam generator that increases the pressure. A steam turbine apparatus comprising: a steam control valve that throttles main steam and lowers the steam temperature by its throttling effect before introducing the steam into the steam inlet. 4. A steam turbine comprising a steam generator, a steam control valve that adjusts the flow rate of main steam generated by the steam generator, and a steam turbine that introduces the steam through the steam control valve into the interior to perform work. A steam turbine device characterized in that when the steam turbine is stopped, the pressure of the main steam is increased and the temperature of the steam introduced into the steam turbine is lowered by the throttling effect of the steam control valve. cooling operation method. 5. A steam turbine comprising a steam generator, a steam control valve that adjusts the flow rate of main steam generated by the steam generator, and a steam turbine that introduces the steam through the steam control valve into the interior to perform work. A cooling operation method for a steam turbine device, characterized in that when stopping the steam turbine, the steam control valve is throttled to reduce the temperature of the steam introduced into the steam turbine by its throttling effect. 6. A steam turbine comprising a steam generator, a steam control valve that adjusts the flow rate of main steam generated by the steam generator, and a steam turbine that introduces the steam through the steam control valve into the interior to perform work. A cooling operation of a steam turbine device, characterized in that when the steam turbine is stopped, the pressure of the main steam is increased and the steam control valve is throttled to lower the temperature of the steam introduced into the steam turbine. Method. 7. The cooling operation method for a steam turbine device according to any one of claims 4 to 6 is characterized in that after the steam turbine is stopped, cooling air is introduced into the steam turbine to perform forced cooling. A method of cooling steam turbines. 8. A method for cooling a steam turbine, which comprises stopping the steam turbine using the cooling operation method for a steam turbine device according to any one of claims 4 to 6, and then naturally cooling the steam turbine. 9. In a steam turbine device that operates with a variable pressure pattern in which the main steam pressure is low during low load operation and high during rated operation, the pressure variable pattern is changed to a cooling operation pattern when the steam turbine is stopped. 1. A cooling operation method for a steam turbine device, characterized in that the main steam pressure is increased by a steam control valve, and the steam is throttled to a low temperature by a steam control valve and then introduced into the steam turbine.