JPS62220774A - Shaft seal device using visco seal - Google Patents

Abstract

PURPOSE:To effectively prevent the leak of sealing liquid by controlling the pressure difference between the sealed fluid and cover gas to a constant value. CONSTITUTION:A generator is installed on the right of the revolution shaft 2 of a potassium vapor turbine 1, and visco seals 3 and 4 are arranged on the revolution shaft 2. When the vapor pressure on the vapor turbine 1 side increases, the pressure difference between the cover gas pressure in a shielding chamber 8 and the vapor pressure in the turbine casing 1 is detected by a differential pressure detecting sensor 12, and a signal is supplied into a pressure controller 14. Said pressure controller 14 operates a solenoid valve 13 to supply the cover gas into the shielding chamber 8 and the space of a liquid tank 6, and the pressure is increased, and the equilibrium with the vapor pressure on the casing 1 side is maintained, and the solenoid valve 13 is closed. On the contrary, when the pressure on the turbine 1 side lowers, a solenoid valve 18 on the decompression side operates to maintain the equilibrium.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a qIl! using visco seal. +Regarding sealing devices, in detail, among shaft seals that prevent leakage of sealed fluid from the rotating shaft of a steam turbine or pump, etc., this article relates to a shaft sealing device using a visco seal suitable for use with chemically active substances. It is something.

[Prior Art and Background of the Invention] Conventionally, in the case of a shaft seal for a steam turbine, for example, a contact mechanical seal or a non-contact labyrinth seal that reduces steam pressure has been used as a shaft seal. Since mechanical seals are contact type, they have the advantage of high sealing pressure and being able to achieve a nearly complete seal. However, depending on the type of fluid to be sealed, such as steam, the seal material may corrode. However, in the case of extremely chemically active substances such as metallic potassium vapor, it cannot be used for long periods of time, and is subject to considerable limitations. On the other hand, since the labyrinth seal is a non-contact type, corrosion by the sealed fluid is not so severe, but due to its structure, it cannot completely prevent leakage.

In contrast to these shaft seals, there are almost no practical examples of opposed visco seals, and only a few examples are known, such as shaft seals for sodium pumps for fast breeder reactors and NASA in the United States planning to use them in space power generators. It is the extent that

Opposed visco seals can provide almost complete sealing even when the sealed fluid is a chemically very active substance, but the drawbacks are that the sealing pressure per shaft seal length is small and that it leaks when the shaft stops rotating. be. In addition, with Visco Seal, it is possible to increase the sealing pressure by reducing the distance between the rotating shaft and the fixed part (housing) or by increasing the shaft rotation speed, but in reality, there are limits to these. , and it cannot be made that large. It has been confirmed that the problem of rotation stoppage when using this opposed visco seal can be sufficiently covered by the seal system and system operating method.

[Problems to be Solved by the Invention] It is an object of the present invention to eliminate the drawbacks of the double opposed visco seal, and to provide a cover so that the pressure difference between the fluid to be sealed and the cover gas is equal to or a certain constant pressure difference. It is an object of the present invention to provide a shaft sealing device using a visco seal capable of controlling gas pressure in accordance with pressure fluctuations of a fluid to be sealed.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a system in which the fluid to be sealed in the rotating equipment is connected to the rotating shaft of the rotating equipment, and the visco seal is connected to the fluid on the opposite side of the rotating equipment. It is characterized by comprising an inert gas supplied to the end and means for controlling the pressure of the inert gas in accordance with the pressure of the fluid to be sealed.

[Function] In the shaft seal device using the Visco seal of the present invention, for example, when the pressure on the sealed fluid side rises, a number plate is installed at a position opposite to the sealed fluid side of the Visco seal opposing part. The pressure difference between the cover gas supplied to the shielded chamber and the pressure on the sealed fluid side is detected, the pressure of the cover gas is increased, and the pressure on the sealed fluid side is increased to the gas pressure inside the shielded chamber. When it gets lower, gas escapes and its pressure is lowered,
Inside the visco seal, the pressure is always maintained between the sealed fluid side and the shielded chamber side through the filled sealing fluid, so that even high-pressure sealed fluids can be protected. It can effectively exhibit the characteristics of Visco Seal and maintain a good sealing state.

[Examples] Examples of the present invention will be described in detail below based on the drawings.

FIG. 1 shows an embodiment of the present invention, in which the present invention is applied to a rotating shaft of a potassium steam turbine.

Here, 1 is a potassium steam turbine, 2 is its rotating shaft, and, although not shown, for example, a generator is mounted on the right side of the figure. Reference numerals 3 and 4 are visco seals that are installed on the rotating shaft 2 and have threads facing in opposite directions.The pumping action of these visco seals 3 and 4 causes the central part (hereinafter referred to as the opposing part) to be (No screws are provided) The sealant of the sealing fluid supplied to the turbine 5 is pressurized to prevent steam from the turbine 1 side. Such a device is called an opposed visco seal, and the present invention relates to a shaft sealing device using such an opposed visco seal.

6 is a liquid tank provided above the facing part 5 and storing potassium liquid as a sealant; from the liquid tank 6 to the facing part 5
The sealant 7 is filled toward the area. Reference numeral 8 denotes a shielding chamber provided at the right end of the opposing visco seal, and an inert gas (hereinafter referred to as cover gas) is supplied to the shielding chamber 8 at a predetermined pressure as will be described later.

In such an opposed visco seal, potassium vapor, which is the fluid to be sealed, flows from the turbine casing IA side to the shaft 2.
In this case, the air-liquid interfaces 9 and 10 are maintained between the left side visco seal 3 and the right side visco seal 4 by the pumping action of the opposing visco seals. The gas-liquid interface 9 occurs at a position where the sum of the water head in the liquid tank 6 and the cover gas pressure is balanced with the sum of the potassium vapor pressure and the pump pressure in the left visco seal 3, and A communication pipe 11 is used to communicate between gas and liquid, and a differential pressure detection sensor 12 is provided to detect the pressure difference between the shielding chamber 8 and the turbine casing IA. Cover gas is replenished via the solenoid valve 13 from a supply source such as a tank of the solenoid valve 1.
3 is opened and closed by a pressure controller 14 having a computer function.

In this way, the opening and closing operations of the electromagnetic valve 13 are controlled via the pressure controller 14 so that the difference between the pressure of potassium vapor, which is the fluid to be sealed, and the pressure of the cover gas is always maintained at a predetermined condition. 15 is a manual valve such as a knee valve, and manual valve 1
5 makes it possible to adjust the flow rate when the solenoid valve 13 is opened. Reference numeral 16 denotes a pressure reducing valve for previously reducing the pressure of gas from the gas supply source to the pressure required for supply.

In addition, in the shielding chamber 8, a solenoid valve 18 and a manual adjustment valve 19 are provided in a passage that leads gas to a low pressure tank (not shown) through a drain reservoir 17 for one control of lowering the pressure of the cover gas. 20 and 21 are mechanical seals provided between the shielded chamber 8 side and the generator side, and a bearing (not shown) is further provided between them, but there is no lubrication between the mechanical seals 20 and 21. It is designed to circulate oil 22.

In addition, here, in the sealant 7, 4, and 6, in order to ensure that the water head is always kept constant regardless of fluctuations in the steam pressure in the turbine casing IA, the liquid (1! It is preferable to make the inner diameter of the tank 6 large and to provide a replenishment tank 23 or the like as shown in this example so that the liquid level can be adjusted.

In the shaft seal device configured using the Visco seal in this way, the left gas-liquid interface 9 moves in response to fluctuations in the steam pressure on the turbine 1 side, but the permissible range of this movement is limited to the left side Visco seal. 3 from the casing IA side end to the opposing part 5, and in order to maintain the gas-liquid interface 9 during this period, a cover in the shielding chamber 8 is installed so that the pump pressure does not exceed its fluctuation range. Gas pressure on the turbine 1 side -
Now, in FIG. 1, if the steam pressure on the turbine 1 side drops to the upper level for some reason, the differential pressure detection sensor 12 detects the cover gas pressure in the shielding chamber 8 and the steam in the turbine casing 1. The pressure difference between the pressure and
It is supplied to the pressure controller 14 as an electrical signal. Yo)
The pressure controller 14 uses the signal to operate the solenoid valve I3 in accordance with the pressure difference and the speed of its fluctuation. By this operation, the cover gas is supplied to the shielding chamber 8 and the space of the liquid M6, and the pressure is increased, so the electromagnetic valve 13 is closed when equilibrium with the steam pressure on the turbine casing 1 side is maintained.

Further, when the steam pressure on the turbine 1 side becomes lower than the cover gas pressure in the shielded chamber 8, a negative differential pressure signal is supplied from the differential pressure detection sensor 12 to the pressure controller 14, and the pressure controller 14 reduces the pressure. An operating signal is output to the side electromagnetic valve 18 to reduce the pressure in the space of the shielding chamber 8 and the liquid tank 6, so that an equilibrium can be obtained between the pressure and the vapor pressure. Note that the low-pressure tank side (not shown) is designed to obtain a pressure lower than the expected minimum steam pressure on the turbine 1 side, and if the turbine steam and sealant are potassium, the vacuum A combination of tank and vacuum pump is expected.

Further, the solenoid valves 13 and 1B may be either one that operates on and off using a plurality of solenoid valves, or one that operates continuously and variablely. Furthermore, although the above is an example of a steam turbine, the application of the present invention is not limited to this, but for example, the present invention may be applied to a case where the gas-liquid interface 9 is not generated due to the inside of the turbine casing IA being filled with fluid. Pressure control can also be carried out in a similar manner, and in this case, the fluid in the same chamber as the fluid to be sealed is used as the sealant.

Furthermore, by installing a sensor that directly detects the pressure of the sealed fluid and a sensor that detects the pressure of the cover gas, and detecting the differential pressure from the information from both sensors, even more appropriate control can be achieved. It is also possible to do so.

[Effects of the Invention] As explained above, the present invention is not only applicable to cases where the pressure of the fluid to be sealed is large and cannot be sealed only by the pump pressure of the opposed visco seal, but also a non-contact seal. Therefore, the friction loss is much smaller than that of mechanical seals. Due to its structure, it goes without saying that it can be applied to chemically active sealed fluids, and since the pressure of the cover gas is electrically controlled, the response is fast.
Moreover, since a computer can be used for the control, it can be precisely controlled.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of the configuration of a shaft seal device using the Visco seal of the present invention. DESCRIPTION OF SYMBOLS 1... Turbine, IA... Turbine casing, 2... Rotating shaft, 3.4... Visco seal, 5... Opposing part, 6... T & 4th grade, 7... Sealant, 8 ... Shielding chamber, 9, lO... Gas-liquid interface, ll... Communication tube, 12... Differential pressure detection sensor, 13.18... Solenoid valve, 14... Pressure controller, 15 .19...Manual valve, 16...Pressure reducing valve, 17...Tren reservoir, 20.2+...Mechanical seal, 22...Lubricating oil, 23...Replenishment tank.

Claims (1)

[Scope of Claims] A shaft sealing device using a visco seal that prevents sealed fluid in a rotating device from leaking along the rotating shaft of the rotating device, comprising: the visco seal with the threads in opposite directions; a sealing fluid with a constant water head supplied to the opposite part of the visco seal to the screw; and an inert gas supplied to the end of the visco seal opposite to the rotating equipment. A shaft sealing device using a visco seal, comprising: a means for controlling the pressure of the inert gas in accordance with the pressure of the fluid to be sealed.