JPH0133770Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to LNG cryogenic power generation equipment, and particularly relates to LNG cryogenic power generation equipment using the Rankine cycle.

[Background of the idea]

Figure 1 shows a system diagram of a conventional LNG cryogenic power generation facility using the Rankine cycle. In Figure 1
LNG enters the LNG evaporator 1 through the conduit 20, condenses Rankine medium gas from the conduit 30, and the LNG is vaporized by the heat of condensation and sent out through the conduit 21. In practice, vaporized LNG from conduit 21
is further heated to a temperature of 0° C. or higher using a heater (not shown) using seawater or the like as a heat source, and then supplied as fuel gas. On the other hand, in the Rankine cycle,
The Rankine medium condensed in the LNG evaporator 1, e.g.
Freon-13B1 (hereinafter abbreviated as Freon) is approximately -60℃,
The liquid becomes atmospheric pressure and the pressure is increased to approximately 16 kg/cm ² by the Rankine medium pump 2 through the conduit 22, and the Freon is supplied to the Rankine medium evaporator 3 while controlling the liquid level of the Freon in the Rankine medium evaporator 3 using the liquid level control valve 6. be done. Here, seawater is supplied as a heat source from the conduit 30, and the fluorocarbon becomes a gas at 10Kg/cm ² and 10℃, and the conduit 2
The medium enters the turbine 4 from 6 and expands to atmospheric pressure.
The temperature reaches 55°C and returns to the LNG evaporator 1 through the conduit 30 for recirculation. While the medium turbine 4 is in operation,
The flow rate of freon is controlled by a medium pressure regulator 12 of the LNG evaporator 1 and a turbine control valve 9. Further, when the medium turbine 4 is stopped, the control valve 10 is switched to perform turbine bypass operation, and the pressure regulator 12 has a function of maintaining the condensing force of fluorocarbon at a constant level. The main purpose of LNG cryogenic power generation equipment is to vaporize LNG and play an important role in supplying it as fuel gas to power plants, etc.
When the media turbine 4 trips, the control valve 10 installed in the bypass line of the media turbine 4 switches to turbine bypass operation so that the operation can continue.Also, a backup pump is installed in the Rankine media pump 2, so that if the pump fails, the backup pump can be activated. It also has a device that automatically starts the . In addition, if the Rankine medium pump breaks down during turbine bypass operation and the backup pump is malfunctioning, the turbine bypass shutoff valve 11 and the bypass control valve 7 of the Rankine medium pump 2 are operated to reduce the LNG evaporator 1 medium pressure and the Rankine medium evaporator pressure. 3 is equalized and natural circulation of fluorocarbons due to liquid head pressure allows LNG to continue vaporizing. However, with such conventional equipment, if the Rankine media pump breaks down while the media turbine is operating, it is necessary to bypass the turbine or open the valve.
The Rankine medium pressure of the LNG evaporator, which had been operating near atmospheric pressure, was reduced to 10% in 1 to 2 minutes by pressure equalization operation.
Kg/cm ² , and even if the 4-turbine shearing device is activated, it will continue to rotate for several minutes due to inertia. Normally, the shaft of a media turbine is sealed with a mechanical seal to prevent Rankine media from leaking to the outside, and lubricating oil is supplied to the mechanical seal to form an oil film, but the seal oil pressure is about 3 to 5 kg/ ^cm2 . If an attempt is made to equalize the pressure in the Rankine cycle by cutting off the media turbine due to a Rankine media pump failure, the exhaust pressure of the media turbine will rise rapidly and the media turbine will stop if the Rankine cycle is equalized within 1 to 2 minutes. By this time, the hydraulic pressure will exceed the mechanical seal pressure, and a reverse pressure will be applied to the mechanical seal, making it impossible to secure a seal oil film and potentially damaging the mechanical seal. From the above, conventionally, if the Rankine medium pump fails during operation of the medium turbine, LNG supply is stopped to protect the mechanical seal of the medium turbine, and the exhaust pressure of the medium turbine is controlled by the medium pressure regulator of the LNG evaporator. This is to prevent the exhaust pressure of the medium turbine from increasing. For this reason
There was a drawback that LNG vaporization had to be stopped.

[Purpose of invention]

The purpose of this invention is to equalize the pressure of the Rankine cycle without applying back pressure to the mechanical seal of the medium turbine even if the Rankine medium pump fails during operation of the medium turbine, and to form a natural circulation of the Rankine cycle, and to vaporize LNG. The purpose of this project is to provide LNG cold power generation equipment that can be used intermittently.

[Summary of the idea]

The present invention is designed to equalize the pressure of the Rankine cycle and shift to natural circulation when the Rankine medium pump fails during operation of the medium turbine.
This is to prevent the exhaust pressure of the medium turbine from increasing.

[Embodiment of the invention] An embodiment of the invention will be described with reference to FIG.
In FIG. 2, the same devices as those in FIG. 1 are designated by the same reference numerals and their explanations will be omitted.

In FIG. 2, the outlet pipe 27 of the medium turbine 4 includes:
During operation of the media turbine 4, the Rankine media pump 2
If the Rankine medium pump 2 fails while the medium turbine 4 is in operation, it is provided with means for closing the outlet pipe 27 in the event of a failure, such as a stop valve or a check valve 31. At the same time, for example, the turbine bypass valve 31 is activated and closed, and then the turbine bypass valve 11 is opened to stop the medium pump. The control valve 7 of the bypass line is switched to the liquid level control 13 of the Rankine medium evaporator 3 to equalize the pressure of the Rankine cycle.
As a result, the Rankine cycle is divided between the Rankine medium liquid level in LNG evaporator 1 and the Rankine medium liquid level in Rankine medium evaporator 3.
The natural circulation of the Rankine medium begins due to the height difference between the liquid level of the Rankine medium and the LNG vaporization. At this time, the exhaust pressure of the medium turbine 4 and the valve 31 are closed, so the Rankine cycle becomes pressure equalized, and even if the Rankine medium pressure of the LNG evaporator 1 increases, the pressure of the outlet pipe 27 of the medium turbine 4 remains near atmospheric pressure. Since the seal is held in place, it is possible to prevent back pressure from being applied to the mechanical seal in about 1 to 2 minutes.

[Effect of idea]

According to the present invention, even if the Rankine medium pump fails during operation of the medium turbine, LNG vaporization can be continued without adversely affecting the medium turbine shaft seal, and the system prioritizes LNG vaporization ability. It can contribute to improving the reliability of LNG cryogenic power generation equipment.

[Brief explanation of the drawing]

Figure 1 shows the results using the conventional Rankine cycle.
A system diagram of the LNG cold power generation facility is shown. FIG. 2 is a system diagram showing an embodiment of an LNG cryogenic power generation facility using the Rankine cycle according to the present invention. 1... LNG evaporator, 2... Rankine medium pump, 3... Rankine medium evaporator, 4... medium turbine, 5... generator, 27... outlet pipe, 31...
non-return valve.

Claims (1)

[Claims for Utility Model Registration] 1. In an LNG cold power generation facility using the Rankine cycle, when a Rankine medium pump that constitutes the LNG cold power power generation facility fails, the outlet pipe of the medium turbine that constitutes the LNG cold power power generation facility and is in operation is 1. An LNG cryogenic power generation facility, characterized in that the outlet pipe is provided with a means for closing. 2. The LNG cryogenic power generation equipment according to claim 1, wherein the means is a shutoff valve or a check valve.