JPH0247596B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improved overpressure prevention device for geothermal power generation equipment that prevents overpressure in a main steam piping system in geothermal power generation equipment.

[Technical background of the invention and its problems]

Geothermal power plants use natural steam, and the fumes contain large amounts of scale and impurities, so they have different characteristics from regular thermal power plants. The thermal cycle of geothermal power generation also differs depending on the nature of the ejected steam, but the plant configuration is as shown in Figure 1, where the ejected steam from steam well 1 is guided to steam generator 3, and the source water is supplied from the source well. 2, the main steam is supplied to the steam turbine 4 through the main steam stop valve 7 and the steam control valve 8 using the main steam piping 6, and the steam turbine 4 is made to work to drive the generator 5. and is configured to generate electric power.

The main steam stop valve 7 has the function of completely stopping the inflow of steam to stop the turbine 4, and the steam control valve 8 adjusts the amount of steam flowing into the turbine 4 to an amount commensurate with the load of the generator 5. It has the function of controlling.
The steam control valve 8 is controlled by a speed governor that operates according to the rotational speed of the turbine 4. That is, the steam control valve 8 in a typical thermal turbine power generation plant is used when there is a sudden load drop in the power system to which the power generator 5 is connected, or when the generator 5 is separated from the system, such as a so-called load failure. When this occurs, it is abruptly closed by the action of a governor or other overspeed prevention device, which controls the steam flowing into the turbine 4 to prevent overspeed. When the steam control valve 8 closes rapidly in this way, in a thermal turbine power plant, the boiler combustion is controlled to reduce the amount of steam generated, thereby supplying only the amount of steam necessary for the turbine 4. The main steam piping 6 on the upstream side of the steam control valve 8
can prevent the pressure from rising rapidly.

However, in geothermal turbine power plants, steam is generated not by a boiler but by natural jet steam, so it is not possible to directly apply the method of controlling the amount of steam generated by the boiler to prevent overpressure in the pipes. Can not. Therefore, in order to protect the system piping and equipment in an overpressure state, an atmosphere release valve 10 is installed at the end of the piping 9 branched from the main steam piping 6, as shown in Fig. 1, to detect an increase in the main steam pressure. The excess steam is then released to the atmosphere.

Geothermal steam generally contains many impurities, and scale often forms and adheres to or accumulates in steam passages. For this reason, sliding parts such as valve stems of steam valves used in geothermal turbine equipment become stuck due to the scale, which may cause problems such as valves not opening or closing when necessary. For this reason, for example, the main steam stop valve 7 is normally provided with a test function that tests the opening and closing of the valve during normal operation to check for the possibility that the valve will become stuck. Atmospheric release valve 1 that detects main steam pressure and releases excess steam to the atmosphere
0 also needs to have a similar test function.

However, adding a separate test function to the atmosphere release valve 10 naturally increases the work of the operator, since the steam valve on the turbine side also has the same function, and also requires testing during normal operation. When the atmosphere release valve 10 is opened for
This causes the turbine to have more opportunities to support load fluctuations, which is unfavorable for turbine operation.

[Purpose of the invention]

An object of the present invention is to provide a highly reliable overpressure prevention device for geothermal power generation equipment that can reliably prevent the occurrence of overpressure in the main steam piping system in geothermal power generation equipment.

[Summary of the invention]

The present invention provides an atmospheric release valve that releases excess steam to the outside of the system due to fluctuations in overpressure in the main steam piping, and an atmospheric release valve that releases surplus air to the outside of the system when a pressure relief membrane is destroyed by the overpressure in the main steam piping. This invention relates to an overpressure prevention device for geothermal power generation equipment that prevents the generation of overpressure in the main steam piping system by the coordinated operation of the atmosphere release valve and the atmosphere release plate.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. In FIG. 2, the configuration of the geothermal power plant according to the present invention is the same as in FIG.
The main steam is supplied to the steam turbine 4 through the main steam stop valve 7 and the steam control valve 8 using the main steam piping 6, and the steam turbine 4 is made to work to drive the generator 5. configured to generate electrical power. In the geothermal power generation plant configured as described above, the present invention provides a branch pipe 9 of the main steam pipe 6 in order to prevent overpressure of the main steam pipe 6.
An atmosphere release valve 10 is provided in a, and this atmosphere release valve 10
is controlled by a controller 11 that responds to the pressure of the main steam pipe 6, and furthermore, an atmosphere release plate 13 having an escape pressure membrane is provided in the branch pipe 9a, and the so-called atmosphere release valve 10 and the atmosphere release plate 13 cooperate. An overpressure prevention operation is performed.

That is, the atmosphere release valve 10 is a normal valve whose opening and closing are controlled by the output of the controller 11, and the atmosphere release plate 13 releases a portion of the main steam from the branch pipe 9b of the main steam pipe 6, as shown in FIG. The open end of the pipe 13a through which the water is sent is sealed with a pressure-reducing membrane 13b made of a lead plate, an aluminum plate, or the like. This pressure relief membrane 13b breaks and releases steam to the atmosphere when the differential pressure between the pressure in the main steam pipe 6 and the atmosphere becomes excessive. The advantage of this atmosphere release plate 13 is that unlike the atmosphere release valve 10, there is no sliding part of the valve stem, so there is no fear that it will become stuck due to scale. However, when the atmospheric release plate 13 is used in a geothermal turbine power generation plant in a power grid with a relatively small power system capacity and frequent sudden load fluctuations, the pressure relief film 13b is used to prevent the air from being connected to the atmosphere every time the load fluctuates. If the differential pressure increases, it will deteriorate and, in the worst case, may be destroyed.

For this purpose, the operations of the atmosphere release valve 10 and the atmosphere release plate 13 must be coordinated with each other. FIG. 4 shows the operating pressure settings for the atmosphere release valve 10 and the atmosphere release plate 13. That is, in Figure 4,
P ₁ is the system pressure under rated operating conditions, and P _MAX is the maximum allowable system pressure. Under such operating pressure conditions, the burst pressure P _RD of the atmospheric release plate 13 is set to a value extremely close to the allowable maximum pressure P _MAX as the last protection device that protects the system from overpressure. on the other hand,
The pressure at which the atmospheric release valve 10 begins to open _PRVO and the pressure at which it begins to close _PRVC are set in a range above the system pressure P1 and below the bursting pressure _PRD of the atmospheric release plate ₁₃ .
These set values are stored in the controller 11 shown in FIG. 2, and the atmospheric release valve 10 is controlled based on the set values by a command from the controller 11 corresponding to the pressure of the main steam pipe 6.

Next, the overpressure prevention operation of the geothermal power generation equipment of the present invention will be explained. In a geothermal power generation facility equipped with an atmospheric release valve 10 and an atmospheric release plate 13 having the functions described above, the main steam pipe 6 operates when the steam control valve 8 operates in the closing direction during normal load fluctuations or load interruptions. In response to the pressure rise, the atmosphere release valve 10 operates as the first protection device based on the pressure settings shown in FIG.
Hold pressure. If the atmosphere release valve 10 stops working due to scale adhesion, the pressure in the main steam pipe 6 will further increase and the atmosphere release plate 1
When the burst pressure _PRD of No. 3 is reached, the last protection device, the pressure relief film 13b of the atmosphere release plate 13, is destroyed, releasing steam to the outside of the system and preventing overpressure in the main steam pipe 6. That is, the atmosphere release valve 10 performs a first protective operation, and the atmosphere release plate 13 performs a back-up protection operation when the atmosphere release valve 10 becomes immovable due to adhesion of scale or the like.

In this way, in the geothermal power generation plant of the present invention, the atmosphere release valve 10 and the atmosphere release plate 13 are provided together, and their operating pressures are coordinated as shown in FIG. When it is not in a stuck state and its function is complete, the release valve 10 itself prevents the pressure from rising in the main steam pipe 6 without destroying the atmosphere release plate 13.
Therefore, unlike the case where only the discharge plate 13 is installed, there is no need to stop the steam turbine each time the discharge plate 13 is broken.

In geothermal power plants, the main steam stop valve 7
Since there is a high possibility that the valves and steam control valves 8 become stuck due to scale adhesion, etc., a test function is provided so that opening/closing tests of these valves can be performed while the turbine is operating. In the embodiment of the present invention, the test function of the main steam stop valve 7 can be used to test the atmospheric release valve 10.
That is, in FIG. 5, an oil cylinder 14 is provided to drive the main steam stop valve 7, and the oil pressure of this oil cylinder 14 is released by a test valve 16 linked to a test device 15, so that the valve 7 is closed. Ru. Limit switch 18 detects the closed state of valve 7, limit switch 17 detects the open state of valve 10, and their respective signals are input to control relay 20. On the other hand, the transmitter 19 detects the pressure in the main steam pipe 6 and its signal is also input to the control relay 20.
The operation function of this control relay 20 is based on the AND ₁ condition of the signal S ₁ of the main steam stop valve 7 and the signal S ₂ when the main steam pressure becomes higher than the set value, as shown in FIG. NOT signal _S3 to open the atmosphere release valve 13
condition, and the signal S ₄ of the AND ₁ condition and the signal S ₅ of the NOT condition are set as the AND ₂ condition to issue an alarm. In other words, when the main steam stop valve 7 closes and the pressure in the main steam pipe 6 increases, and even though the atmospheric release valve 10 is closed despite the command to open it, all signal conditions are met and an alarm is issued. emanate.

Now, in FIG. 5, when an operator closes the main steam stop valve 7 using the test device 15 for a daily valve test, the pressure in the main steam pipe 6 increases.
The pressure regulator 11 detects this pressure increase and, when the pressure reaches a preset value, sends an open signal to the atmosphere release valve 10 to open the atmosphere release valve 10. If the atmospheric release valve 10 is in a stuck state and does not open, the signal condition shown in FIG. 6 is satisfied and the control relay 20 is
The system activates and issues an alarm, alerting the operator immediately.

In this way, the main steam stop valve 7 and the atmosphere release valve 10 can be tested simultaneously in one test. Furthermore, even if the steam control valve 8 is provided with a test function, exactly the same effect will be achieved. That is, in the embodiment shown in FIG. 5, there is no need to newly install a test device for the atmosphere release valve 10, and the normally set valve test functions of the main steam stop valve 7 and the steam control valve 8 can be used. By using this, the atmosphere release valve 10 can be tested at the same time, and the stuck state of the atmosphere release valve 10 can be quickly detected, which has the advantage of alerting the operator.

〔Effect of the invention〕

As described above, the present invention includes an atmosphere release valve that releases steam to the outside of the system in response to overpressure in the main steam piping, and an air release valve that releases steam to the outside of the system in response to overpressure in the main steam piping, and an evacuator for the overpressure in the main steam piping that is higher than the operating pressure of the atmosphere release valve. By using an atmosphere release plate that breaks the membrane and releases steam outside the system, the atmosphere release valve performs an overpressure prevention operation against overpressure in the main steam piping within the normal set value range. This prevents unnecessary destruction of the atmosphere release plate, and when the atmosphere release valve is in the static state, the atmosphere release plate performs an overpressure prevention operation. Therefore, overpressure in the main steam system can be reliably prevented.

[Brief explanation of drawings]

Figure 1 is a system diagram showing a schematic configuration of geothermal power generation equipment, Figure 2 is a system diagram showing a schematic configuration of geothermal power generation equipment equipped with an overpressure prevention device according to the present invention, and Figure 3 is a system diagram showing a schematic configuration of geothermal power generation equipment used in the present invention. FIG. 4 is a piping system diagram showing the atmosphere discharge plate; FIG. 4 is a pressure setting diagram for explaining the operation of the atmosphere discharge valve and atmosphere discharge plate used in the present invention; FIG.
The figure is a system diagram with a valve test function added, and FIG. 6 is a functional block diagram of a control relay in the test function. 1...Steam well, 2...Kanmoto well, 3...Steam generator, 4
...steam turbine, 5...generator, 6...main steam piping,
7... Main steam stop valve, 8... Steam control valve, 10... Atmospheric release valve, 11... Controller, 13... Atmospheric release plate, 13
b...Evacuation membrane, 14...Drive oil cylinder, 15...Test device, 16...Test valve, 17, 18...Limit switch, 19...Transmitter, 20...Control relay.

Claims (1)

[Claims] 1 An atmospheric release valve that releases steam to the outside of the system in response to overpressure in the main steam system of geothermal power generation equipment, and an escape pressure membrane that is destroyed by the overpressure in the main steam system and releases steam to the outside of the system. The operating pressure of the atmospheric releasing plate is set slightly lower than the maximum allowable pressure of the main steam system, and the operating pressure of the atmospheric releasing valve is set to be equal to the operating pressure of the atmospheric releasing plate and the rated pressure of the main steam system. An overpressure prevention device for geothermal power generation equipment, characterized by being set between.