JPH08165905A - Bleed steam turbine - Google Patents

Abstract

PURPOSE: To cope with a large required quantity of exhaust steam of a high pressure part supplied to a low pressure part through an extraction control valve in order to cool the blade turbine stage part of the low pressure part of the turbine at the time of keeping a turbine rotor at a steady state speed during no-load operation of a bleed steam turbine after load shutdown. CONSTITUTION: A piston 42 of a piston rod 33 of a hydraulic cylinder 30 for reciprocating a valve rod 21 through a lever 41 to open and close an extraction control valve 8 is brought into contact with an upper plate 35 of a cylinder 37 to limit the position of the piston 42, and the valve opening of a valve element 20 is set to an opening where the steam quantity of exhaust steam of a high pressure parat required for cooling the blade turbine stage part of a low pressure part flows by the position of the piston 42.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an extraction steam turbine equipped with an extraction control valve for controlling the pressure of extraction steam extracted from the middle of a blade stage.

[0002]

2. Description of the Related Art A high pressure section having a blade section and a low pressure section are provided, and the pressure of the extracted steam extracted from the exhaust steam of the high pressure section is
A system shown in FIG. 3 is known as an extraction steam turbine in which the extraction pressure control valve provided at the steam inlet of the low pressure portion controls the pressure to a predetermined pressure required by the process.

In FIG. 3, the extraction steam turbine 1 comprises a high pressure section 2 whose main body has a blade section and a low pressure section 3 which has a blade section following the high pressure section 2, and is connected to an exhaust chamber of the high pressure section 2. A bleed air supply system 6 for supplying bleed steam extracted from the exhaust steam of the high pressure section 2 to the process 5 is provided.
The steam inlet of the high-pressure section 2 is provided with a main steam control valve 7 for controlling the amount of main steam flowing into the high-pressure section 2, while the steam inlet of the low-pressure section 3 is provided with the pressure of extraction steam supplied to the process 5. A bleed air control valve 8 for controlling is provided.

The rotation speed detector 10 is a turbine rotor 11
Is installed in the vehicle and detects the rotation speed of the turbine rotor 11. The extraction pressure detector 12 is provided in the extraction supply system 6 and detects the pressure of extraction steam supplied to the process 5. The speed control device 14 receives the signal of the detected rotation speed of the turbine rotor 11 at the rotation speed detector 10 and the signal of the detected pressure of the extracted steam at the extraction air pressure detector 12, and inputs the main steam control valve 7 and the extraction control valve. 8 is controlled to control the rotation speed of the turbine rotor 11, the steam amount corresponding to the turbine load and the extraction load, and the process 5 is controlled by controlling the extraction control valve 8.
The bleed air pressure supplied to is controlled to the predetermined pressure required by the process.

With such a configuration, the main steam supply system 15
After passing through the main steam, the main steam control valve 7 whose valve opening is controlled by the control action of the speed governor 14 is controlled to a steam amount corresponding to the turbine load and the extraction load, and flows into the high-pressure unit 2 to perform work. To do. The extracted steam extracted from the exhaust steam of the high pressure unit 2 is supplied to the process 5 so that the pressure detected by the extraction pressure detector 12 by the speed governor 14 becomes the predetermined pressure required by the process 5. It is controlled by the extraction control valve 8. The remaining extracted steam of the high-pressure part 2 flows into the low-pressure part 3 for work, and is then discharged to the outside via the exhaust system 16. Then, electric power is generated from a turbine load corresponding to the work amount of the steam flowing through the high pressure portion 2 and the low pressure portion 3, for example, a generator directly connected to the turbine.

When the load of the extraction steam turbine 1 is cut off, the main steam control valve 7 and the extraction control valve 8 are once fully closed by the control action of the speed governor 14, but the turbine rotor during no-load operation. In order to maintain 11 at the set rotational speed, only the main steam control valve 7 is opened so that the steam flow amount required for the no-load operation of the turbine is opened.
After passing through the main steam, the main steam flows through the high pressure part 2 and the turbine rotor 1
1 is rotated, but the extraction control valve 8 remains fully closed.
At this time, the exhaust vapor of the high pressure section 2 flows toward the extraction air supply system 6.

However, in this state, the extraction control valve 8
Since steam does not flow to the low pressure portion 3 on the further downstream side, the temperature of the blade stage portion of the low pressure portion 3 excessively rises due to the rotation of the turbine rotor 11, and the blades and the like are rubbed due to thermal deformation and thermal expansion of the casing and the turbine rotor. Or vibration occurs. Therefore, conventionally, in order to prevent the temperature rise of the blade section of the low pressure portion 3,
Means as shown in FIG. 4 are provided.

FIG. 4 is a configuration diagram schematically showing the configuration of a hydraulic cylinder and a main part of a bleed air control valve that is opened and closed by the hydraulic cylinder. A conventional technique will be described with reference to the drawing. 4, the extraction control valve 8 has a valve body 20 as a main part, a valve rod 21 connected to the valve body 20, and a valve seat 2 on which the valve body 20 is seated.
2 and a valve box 24 that houses the valve body 20 and the valve seat 22 and has a guide portion 23 that houses the gland packing that surrounds the valve rod 21 when the valve rod 21 reciprocates. Here, in the valve body 20, the steam that has flowed into the valve box 24 is transferred to the valve seat 22.
Is provided with a cooling steam hole 27 that flows into the valve outlet 26.

The hydraulic cylinder 30 includes a piston rod 33 composed of a rod 31 and a piston 32, a cylinder 34 surrounding the piston 32 of the piston rod 33, and the rod 3.
The cylinder 37 is composed of an upper plate 35 and a lower plate 36 through which 1 passes, and supply and discharge pipes 38 and 39 for supplying and discharging pressure oil are connected to the upper and lower portions of the cylinder 37, respectively. The rod 3 of the piston rod 33 of the hydraulic cylinder 30
A lever 41 that rotates around a fulcrum 40 is connected to 1 and the valve rod 21 of the extraction control valve 8 by pin connection.

With such a configuration, during the no-load operation after the load is cut off, the turbine rotor 11 is controlled to the settling speed by the opening degree of the main steam control valve 7 as described above, but the extraction control valve 8 is completely operated. Closes. The bleed air control valve 8 is fully closed as follows. The pressure oil is supplied to and discharged from the hydraulic cylinder 30 through the supply and discharge pipes 38 and 39 by the control action of the speed governor 14, and the piston rod 33 moves upward. By this movement of the piston rod 33, the valve body 20 of the extraction control valve 8 is seated on the valve seat 22 via the lever 41, and the valve is fully closed.

In the fully closed state of the extraction control valve 8 as described above, from the high pressure section 2 after flowing into the high pressure section 2 from the main steam control valve 7 to perform work in order to set the turbine rotor 11 to a set rotational speed. Of the exhaust steam flows into the low pressure portion 3 through the cooling steam hole 27 provided in the valve body 20 of the extraction control valve 8 to flow, and cools the blade stage portion of the low pressure portion 3.

[0012]

After the load is cut off, when the set rotational speed of the turbine rotor is maintained, the extraction control valve 8 is fully closed as described above. At this time, the low pressure part 3 of the extraction steam turbine 1 is closed. In order to cool the blade section, the exhaust steam of the high pressure section 2 is caused to flow into the low pressure section 3 via the cooling steam hole 27 provided in the valve body 20 of the extraction control valve 8.

However, since the size of the cooling steam hole 27 is restricted by the structure of the valve body 20, there is a problem that the amount of cooling steam is limited and it cannot be dealt with when a large amount of cooling steam is required. An object of the present invention is to maintain the settled rotation speed of the turbine rotor after load shedding, when cooling the blade paragraph of the low pressure part of the extraction steam turbine by the exhaust steam of the high pressure part supplied via the extraction control valve, An object of the present invention is to provide an extraction steam turbine capable of cooling without limiting the amount of cooling steam.

[0014]

A high pressure part and a low pressure part having blade sections, a main steam control valve provided at a steam inlet of the high pressure part for controlling the amount of steam flowing into the high pressure part, and an exhaust steam of the high pressure part. Is provided at the steam inlet of the low-pressure part into which the inflow is generated, controls the pressure of the extracted steam extracted from the exhaust steam, and reciprocates the piston rod of the hydraulic cylinder to reciprocate the valve rod through the lever mechanism to open the valve. In the extraction steam turbine equipped with the extraction control valve, the valve opening that allows the amount of exhaust steam from the high pressure section to cool the blade section of the low pressure section when the turbine rotor is maintained at the settling speed after the load is cut off. Each time, a degree-of-opening limiting means for mechanically limiting the valve rod position of the extraction control valve is provided.

The above-mentioned opening degree restricting means is a structure of a hydraulic cylinder that restricts the movement of the piston rod by bringing the piston of the piston rod of the hydraulic cylinder into contact with the upper plate or the lower plate of the cylinder. Further, the opening degree restricting means is provided with a protrusion on the valve rod that comes into contact with the end face of the valve rod guide portion of the valve box of the extraction control valve.

[0016]

[Operation] A high pressure part and a low pressure part having wing paragraphs, a main steam control valve for controlling the amount of steam flowing into the high pressure part at the steam inlet of the high pressure part, and bleeding from exhaust steam of the high pressure part to the steam inlet of the low pressure part. In an extraction steam turbine equipped with an extraction control valve that controls the pressure of extraction steam, in order to maintain the turbine rotor at the settling speed during no-load operation after the load is cut off, the main steam control valve is The amount of steam required to maintain the settled rotation speed is opened to an opening at which the steam flows to the high-pressure portion, and the steam flows to the high-pressure portion to work at the blade stage.

On the other hand, when the load is cut off, the bleed air control valve faces toward the fully closed position as described below. That is, the bleed air control valve moves the valve rod of the bleed air control valve through the lever mechanism by the movement of the piston rod of the hydraulic cylinder to orient the valve in the closing direction. At this time, the opening degree of the valve limits the valve rod position by the opening degree limiting means so that a sufficient amount of steam for cooling the blade stage of the low pressure portion flows.

Here, the opening degree limiting means limits the movement of the piston of the piston rod of the hydraulic cylinder, that is, the piston of the piston rod is brought into contact with the upper or lower plate of the cylinder of the hydraulic cylinder, or , A protrusion is provided on the valve rod of the extraction control valve, and the protrusion contacts the end face of the valve rod guide part of the valve box to keep the extraction control valve at the time of maintaining the settling speed of the turbine rotor after the load is cut off. The valve opening is maintained as described above, and the exhaust vapor of the high pressure section flows into the low pressure section from this valve opening to cool the blade stage of the low pressure section.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram schematically showing a configuration of a hydraulic cylinder according to an embodiment of the present invention and a main part of a bleed air control valve that is opened and closed by the hydraulic cylinder. In FIG. 1 and FIG. 2 described later, the same parts as those of the conventional example of FIGS. 1 is different from the conventional example of FIG. 4 in the following points, which will be described with reference to FIG.

The piston 42 of the piston rod 33 of the hydraulic cylinder 30 is brought into contact with the upper plate 35 of the cylinder 37 to limit the position of the piston rod 33. Then, the valve opening degree of the valve body 20 of the extraction control valve 8 determined via the lever 41 at this limited position of the piston rod 33 is maintained at the set rotational speed of the turbine rotor 11 during the no-load operation after the turbine load is cut off. At this time, the opening degree is set such that the exhaust vapor of the high-pressure portion 2 flows enough to cool the blade stage portion of the low-pressure portion 3.

Here, the piston 42 is provided with annular grooves 42a on its upper and lower surfaces, and when the piston 42 comes into contact with the upper plate 35 and the lower plate 36 of the cylinder 37, pressure oil is supplied to and discharged from the supply / discharge pipes 38, 39. I am able to do it. With such a configuration, after the load is cut off, the amount of steam sufficient to maintain the settling rotation speed of the turbine rotor 11 during no-load operation from the main steam control valve 7 by the control action of the speed governor 14 as described above is high. To work in the wing paragraph. On the other hand, when the load is cut off, the bleed air control valve 8 moves the valve rod 21 downward through the lever 41 to direct it toward the closing direction by supplying and discharging pressurized oil to and from the hydraulic cylinder 30 as described above. The piston 42 of the piston rod 33 of the cylinder 30 is the upper plate 3 of the cylinder 37.
5 and its position is restricted, and at the position of this piston 42, the valve body 20 of the extraction control valve 8 maintains the above-mentioned valve opening degree. Therefore, the exhaust steam of the high pressure part 2 flows into the low pressure part 3 from the opening degree of the extraction control valve 8 to cool the blade stage part of the low pressure part 3.

In this embodiment, the piston 42 of the piston rod 33 is brought into contact with the upper plate 35 of the cylinder 37 of the hydraulic cylinder 30 to limit the position thereof to determine the valve opening degree of the extraction control valve 8. In the mechanism, if the downward movement of the piston rod 33 is in the closing direction of the extraction control valve 8, the piston 42 of the piston rod 33 is brought into contact with the lower plate 36 of the cylinder 37 to limit the position of the extraction control valve 8. The valve opening will be determined.

FIG. 2 is a schematic diagram showing the construction of a hydraulic cylinder according to another embodiment of the present invention and the construction of the main parts of the extraction control valve which is opened and closed by the hydraulic cylinder. In FIG. 2, FIG.
The difference from the conventional example is as follows, and will be described with reference to FIG. The protrusion ring 44 is attached to the valve rod 21 of the bleeding control valve 8. The mounting position of the protrusion ring 44 is
A sufficient amount of steam for exhaust gas of the high-pressure part 2 to flow into the low-pressure part 3 and cool the blade paragraph of the low-pressure part 3 when maintaining the settling speed of the turbine rotor 11 during no-load operation after the load of the turbine is cut off. Valve box 2 to maintain the valve opening required for the flow
4 to the end face of the guide portion 23.

With this configuration, when the load is cut off, the valve opening of the extraction control valve 8 is controlled by the protrusion ring 44 of the valve rod 21.
4, the position of the valve rod 21 is restricted by contacting the end face of the guide portion 23, and the valve body 20 maintains the valve opening degree as described above. To cool the blade stage of the low pressure part 3.

[0025]

As apparent from the above description, according to the present invention, when the extraction steam control valve is closed, the extraction steam control valve of the high pressure portion of the turbine flows when the extraction control valve moves toward the closing direction. The valve opening is an opening restriction device that allows a sufficient amount of steam to cool the blades in the low-pressure section, and as this means, the piston position of the piston rod of the hydraulic cylinder that opens and closes the extraction valve is restricted, or the extraction amount is adjusted. By limiting the position of the valve stem of the valve, when maintaining the turbine rotor at the set speed during no-load operation after the load is cut off,
Exhaust steam from the high pressure portion can flow into the low pressure portion from the valve opening degree of the extraction control valve to cool the blade stage of the low pressure portion. Since the amount of steam to be cooled can be selected according to the valve opening degree of the extraction control valve, even if the amount of steam to be cooled is large, this can be dealt with.

[Brief description of drawings]

FIG. 1 is a configuration diagram schematically showing a main part of a hydraulic cylinder of an extraction steam turbine according to an embodiment of the present invention and an extraction control valve that is opened and closed by the hydraulic cylinder.

FIG. 2 is a configuration diagram schematically showing the configuration of main parts of a hydraulic cylinder of an extraction steam turbine according to another embodiment of the present invention and an extraction control valve that is opened and closed by the hydraulic cylinder.

[Fig. 3] System diagram of extraction steam turbine

FIG. 4 is a configuration diagram schematically showing a main part of a hydraulic cylinder of a conventional extraction steam turbine and an extraction control valve that is opened and closed by the hydraulic cylinder.

[Explanation of symbols]

 1 Extraction Steam Turbine 2 High Pressure Part 3 Low Pressure Part 7 Main Steam Control Valve 8 Extraction Control Valve 20 Valve Body 21 Valve Rod 23 Guide Portion 24 Valve Box 30 Hydraulic Cylinder 32 Piston 33 Piston Rod 37 Cylinder 41 Lever 44 Projection Ring

Claims (3)

[Claims] 1. A high pressure part and a low pressure part having blade sections, a main steam control valve provided at a steam inlet of the high pressure part for controlling the amount of steam flowing into the high pressure part, and a low pressure to which exhaust steam of the high pressure part flows. Is installed at the steam inlet of the control unit, controls the pressure of the extracted steam extracted from the exhaust steam, and reciprocates the piston rod of the hydraulic cylinder to reciprocate the valve rod through the lever mechanism to obtain the valve opening degree. In an extraction steam turbine equipped with a valve, when the turbine rotor is maintained at the set rotational speed after the load is cut off, the extraction amount is adjusted to the valve opening that allows the amount of exhaust steam from the high pressure part to cool the blade stages of the low pressure part. An extraction steam turbine, characterized in that opening degree limiting means for mechanically limiting the valve stem position of the valve is provided. 2. A structure of a hydraulic cylinder according to claim 1, wherein the opening degree limiting means limits the movement of the piston lot by bringing the piston of the piston rod of the hydraulic cylinder into contact with the upper plate or the lower plate of the cylinder. An extraction steam turbine characterized by being present. 3. The extraction steam according to claim 1, wherein the opening restricting means is provided with a protrusion for contacting an end face of a valve rod guide portion of a valve box of the extraction control valve on the valve rod. Turbine.