JPS5874804A - Controlling device for controlling steam turbine having turbine bypass system - Google Patents

Abstract

PURPOSE:To reduce the quantity of steam per unit life of an intercept valve and increase the stability upon starting the turbine by using an assembled reheating steam check valve incorporating a bypass small valve in a main valve, as a reheating stream check valve. CONSTITUTION:The assembled reheating steam tight valve 21 is interposed at the intermediate part of a high-pressure reheating pipe causing steam to flow out toward a middle pressure turbine, and a valve box 22 contains therein an intercept valve 23, a main valve 24 and a bypass small valve 25. Upon starting the turbine, the bypass small valve 25 is first raised by a suitable driving source, and a point (the valve 25 fully open) where the head part of the small valve 25 makes contact with the shoulder part 24b of the main valve 24, is detected by a differential transformer 23. By this detection signal, an open signal to a reheating steam tight valve is locked and held, and valves 23 and 24 are fully closed and held. Thereafter, the intercepted surface 23 is gradually opened, and by the double throttling of the valves 23 and 25, the steam quantity 35 to the intermediate pressure turbine is controlled, and the turbine is raised to the rated rotational speed.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to an improvement of a steam turbine control device having a turbine bypass system. By using the lK combination reheat steam stop valve! -Regarding a steam turbine control device that is designed to stably perform control when starting a bin.

d) Prior art steam turbines are equipped with a turbine bypass system to perform start-up control and output control.

A conventional turbine bypass system is configured as illustrated in FIG. In the same figure, the steam generated at the boiler passes through the main steam pipe.

High pressure turbine via main steam stop valve J and steam control valve L! will be introduced in The steam that worked here is in the high pressure exhaust pipe 4
, high-pressure exhaust check valve 7, low-temperature reheat pipe t, and then led to the boiler reheat pipe, and after being heated, it passes through high-temperature reheat pipe 10 and is connected to reheat steam stop valve /l and I/tacept valve l. After that, medium pressure! -Pin/jK is introduced.・The steam that has done work in the intermediate pressure turbine 13 is transferred to the crossover pipe l.
One low pressure turbine/! The water is divided into t* and i3b to perform their respective work, and then flows into condenser/4.

In the above, the high-pressure bypass system branches from the upstream side of the main steam pipe (main steam stop valve J), passes through the high-pressure bypass valve I and desuperheater/I, and is then reduced in temperature and pressure. On the downstream side of the stop valve 7, the low temperature reheat pipe tK joins. Further, the low pressure bypass system branches from the upstream side of the reheat steam stop valve /l of the high temperature reheat pipe 10, and the low pressure bypass system branches from the reheat steam stop valve /l of the high temperature reheat pipe 10. The temperature and pressure are reduced by the desuperheater 20, and the mixture flows into the condenser/4.

In a steam turbine equipped with an L-bin bypass system configured as described above, the steam generated from the boiler L at startup is passed through the high-pressure bypass that controls the pressure in the main steam pipe until the steam reaches conditions that allow the turbine to start. It passes through valve I and is introduced into condensate @/4 via a low-temperature reheat pipe T, a boiler reheater D, a high-temperature reheat pipe 10, and a low-pressure bypass valve 19 that controls the pressure of this high-temperature reheat pipe.

What is the steam pressure in the main steam pipe 10 and the high temperature reheat steam pipe 10 when the steam turbine is started? - Bypass operation is controlled to be maintained at a predetermined steam pressure corresponding to the pressure at load, and when conditions for starting the turbine are reached, the steam control valve and intercept valve are opened, allowing the high-pressure turbine to operate. and medium pressure turbine/JK steam is introduced to start the turbine.

J) Problems with conventional technology In the conventional steam turbine/control device described above.

Turbine startup is controlled by adjusting the opening of the steam control valve and intercept valve 1, but since the intercept valve has a large valve diameter, the steam flow rate changes significantly with respect to the unit lift, resulting in stability during turbine startup. However, due to the mechanism of the intercept valve, it is virtually impossible to control the lift to a very small degree in order to maintain the intercept valve.

For this reason, a method is sometimes used in which a small-capacity intercept bypass valve is installed in the intercept valve and this intercept bypass valve controls the steam flow rate at I-bi/startup. There are disadvantages in that the installation space increases and the piping system becomes complex.

4I) Purpose of the Invention The present invention has been made in order to eliminate the above-mentioned inconveniences in conventional devices.It is also an object of the present invention to provide a steam turbine control device that is capable of stably controlling the turbine startup. purpose.

Structure of the invention This invention is! - A steam turbine control device having a bin bypass system, characterized by the use of a combination reheat steam stop valve in which a small bypass valve is built into the main valve.

t) Examples of the invention The present invention will be described in detail below with reference to one drawing.

In FIG. 2, the combination reheat steam stop valve 1 has an intercept valve, a main valve, and a small bypass valve built into a valve box n. The valve stems 27 attached to the intercept valve and the small bypass valve JjK each protrude outside the valve box n, and are each driven by a drive mechanism (not shown).

The bypass valve is vertically movably inserted into a bypass valve housing u formed between the intermediate protrusion y1 and the shoulder yb of the main valve. Main valve small valve storage part U and bottom @SaK
: are each provided with a through-hole trowel 30, and a through-hole 31 is also provided in the inter-dragon buttobenko.

A protrusion 32 for position detection is attached to the valve stem of the small bypass valve j, and a differential transformer 33 is connected to this protrusion.

The combination reheat steam stop valve configured as described above is inserted in the middle of the high-pressure reheat pipe (at a position corresponding to the reheat steam stop valve // and the interchange valve l in Figure 1), and is Outflow towards the turbine.

The small bypass valve j further rises and becomes fully open at the point where its head contacts the shoulder of the main valve y: blIbK. The differential transformer 33 detects that the small bypass valve has reached the fully open state, and this detection signal locks and holds the open signal to the reheat steam stop valve. Accordingly, small bypass valve j is fully open.

The main valve ME and the intermediate valve J are fully closed.

From this state, when an opening signal is given to the intercept valve 1 and it is gradually opened, the amount of steam 3S to the intermediate pressure turbine is controlled by the intercept valve force and the double throttling of the bypass small valve j.

From this state, when the opening signal is set to 4 to gradually open the intermediate valve, the amount of steam 3S to the intermediate pressure turbine is controlled by the double throttling of the I/tacept valve and the bypass small valve. .

In such a double throttling state, the steam turbine rotational speed is increased to the rated rotational speed, and then the steam turbine is connected to the electric power system and operated under load.

Under the condition that this no-load operation state has been entered, the aforementioned opening instruction signal to the reheat steam stop valve is unlocked, and the main valve J of the reheat steam stop valve is gradually opened. As the opening degree increases, the amount of steam flowing into the intermediate pressure turbine increases, and the number of rotations or turbine load tends to increase beyond the specified rate of increase.This is detected by the number of rotations and load control capacity, and an intercept valve is installed. Operate the switch in the closing direction. Eventually, the reheat steam stop valve main valve y is fully opened, and load control is performed by the inter-rotating valve 0 until the turbine bypass operation end load point pressure is reached.

The graphs in Figure 3+47 to (f) show the turbine load, turbine rotational speed, ear 1-sept valve opening, bypass small valve W#, main valve opening, and high-temperature reheat steam pressure between the above operating points. 7) Modified example of the invention In the embodiment shown in FIG. 2, an example was described in which the position # of the bypass small valve j is detected by the differential transformer 33. The present invention is not limited to this, and it is also possible to use a seat switch or other weight detection means that responds to the three protrusions.

Further, the shape of the reheat steam stop valve is not limited to the illustrated embodiment, and it goes without saying that various modifications may be made.

t) Effects of the invention As mentioned above, the steam of the present invention! - In the bin control system, a combination reheat steam stop valve with a built-in small bypass valve in the main valve is used as a reheat steam stop valve, and a dual-function control valve and bypass small valve are used for control when starting the turbine. Since this is done through the throttle K, the amount of steam per unit lift of the inter-rotating valve is small, and stability at the time of turbine startup can be maintained.

Furthermore, since the small bypass valve is connected to the main valve as an inner pipe, the installation space does not increase and the piping system does not need to be double-tracked.

[Brief explanation of drawings]

Fig. 1 is a system diagram showing an example of a steam turbine control load having a turbine bypass system, and Fig. 2 is a system diagram showing the actual installation
FIG. 3 is a longitudinal cross-sectional view showing a specific example of the combined reheat steam valve in IIK, and is an explanatory diagram of the operation at the time of turbine startup in this actual interfacing fK. C...Boiler, G...Main steam pipe, J...Main steam stop valve, Part...Steam control valve! ...High pressure turbine, t...
・High-pressure exhaust pipe, 7... High-pressure exhaust check valve, t... Low-temperature reheat pipe, De... Boiler reheat pipe, io... High-temperature reheat pipe, //... Reheat steam stop valve, /J...Interval valve, 13...Intermediate pressure turbine, /4C...Crossover pipe, /jlL, /31:J...Low pressure turbine, 16...Drainer, lfu...・・High pressure bypass valve, /l
...Desuperheater, l...Low pressure bypass valve, I...Desuperheater, V...Combination reheat steam stop valve, n...Valve box, Co...Interval valve, Me...Main valve, j...Bypass small valve, Easy, Core...Valve stem, Co...Bypass small valve housing, knob, JO, J/...Through hole, 3 pieces...・Protrusion, 33...Differential transformer. Applicant's agent Inomata Seigayu 1 Figure'#! Jz diagram

Claims (1)

[Scope of Claims] l) is a reheat steam stop valve inserted in a high temperature reheat pipe connecting between the ira reheat pipe and the intermediate pressure turbine, and the main valve has a built-in bypass small valve, and a combination of reheat steam A steam turbine control device having a turbine bypass system comprising a stop valve. J) A reheat steam stop valve has an intercept valve, a main valve, and a bypass small valve located in the west-east direction within the control area, and the bypass small valve is vertically movable in a bypass small valve storage area formed in the main valve. A steam system with a turbine bypass system according to claim 1, characterized in that it can be easily stored! - Bin control device.