JPH0143124B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method of operating a cold power generation facility, and particularly to a method of operating a cold power generation facility of a Rankine cycle type LNG cold power generation facility that is suitable for good and long-term continuous operation. It concerns driving methods.

[Prior art]

Rankine cycle LNG cryogenic power generation equipment has traditionally been used as a cold power generation facility that recovers the cold energy from LNG vaporization as power and generates electricity.

Rankine cycle LNG cold thermal power generation equipment is
an LNG evaporator that evaporates and vaporizes LNG and condenses and liquefies Rankine medium; a medium pump that pumps Rankine medium (hereinafter abbreviated as liquefied medium) condensed and liquefied in the LNG evaporator to the medium evaporator; A medium evaporator that evaporates and vaporizes the liquefied medium using a heat source such as seawater, a medium turbine that is driven by the Rankine medium (hereinafter referred to as vaporized medium) that has been evaporated and vaporized in the medium evaporator, and a medium turbine that is connected to the medium turbine. It consists of a generator, and as a Rankine medium, fluorine compounds such as Freon-22 and Freon R-13B1,
Hydrocarbons, mainly propane, are recycled.

In such cold-heat power generation equipment, a shaft seal mechanism such as an oil film seal or a mechanical seal is generally used for the shaft seal in order to prevent the vaporized medium from leaking into the atmosphere from the shaft seal of the medium turbine. has been done. By adopting such a shaft seal mechanism, it is possible to prevent the vaporized medium from leaking into the atmosphere, but on the other hand, as the operation continues, the lubricating oil used in the shaft seal part may be mixed into the vaporized medium in small amounts. Unavoidably, a large amount of lubricating oil may temporarily become mixed into the vaporized medium due to trouble such as damage to the shaft seal mechanism. Due to its low vapor pressure, this lubricating oil does not evaporate or vaporize even when the liquefied medium is evaporated or vaporized in the medium evaporator, and most of it is accumulated in the liquefied medium. In this way, the lubricating oil concentration in the liquefied medium gradually increases in the medium evaporator.

When the lubricating oil concentration in the liquefied medium in the medium evaporator increases in this manner, foam is generated when the liquefied medium boils, and the height of the foam increases as the lubricating oil concentration increases. If the height of the boiling surface foam increases and the foam reaches the lower surface of the demister installed in the medium evaporator, the liquefied medium will be entrained in the vaporized medium supplied to the medium turbine. The amount of entrained liquefied medium increases as the lubricant concentration in the liquefied medium increases. As a result, vibrations and abnormal noises occur in the medium turbine, making it impossible to operate the medium turbine satisfactorily. Note that such a situation occurs even when oil having a low vapor pressure is mixed in with the lubricating oil.

Conventionally, when such a situation occurs, it has been dealt with by temporarily stopping the operation and replacing the Rankine medium with a new Rankine medium. In addition, a large amount of Rankine media is required, which increases the cost of Rankine media.

[Purpose of the invention]

The purpose of the present invention is to improve cold power generation equipment and to
The object of the present invention is to provide a method for operating cold power generation equipment that can be operated continuously over a long period of time.

[Summary of the invention]

The present invention involves extracting a liquefied medium mixed with oil from a medium evaporator to an oil separator, separating it into Rankine medium and oil using a heat source generated within the system, and returning the separated Rankine medium to the Rankine cycle. The oil concentration in the liquefied medium in the medium evaporator is adjusted to a concentration that does not allow the foam generated when the liquefied medium boils to reach the lower surface of the demister, without replacing or replenishing the Rankine medium. It is something.

[Embodiments of the invention]

An embodiment of the present invention will be described with reference to the drawings.

In the drawing, the LNG evaporator 10 and the medium pump 11 are connected by a conduit 20, and the medium pump 11 and the medium evaporator 1 are connected by a conduit 20.
2 is a conduit 21, and a conduit 22 is connected to the medium evaporator 12 and the medium turbine 13.
The LNG evaporator 10 is connected to the LNG evaporator 10 through a conduit 23 in a closed cycle, and the medium turbine 1
3 is connected to a generator 14.

Heat exchanger tubes 30 and 31 are installed inside the LNG evaporator 10 and the medium evaporator 12, respectively. For example, a conduit 40 connected to an LNG storage tank (not shown) and provided with an LNG pump (not shown) is connected to the inlet of the heat transfer tube 30, and a heat transfer tube 32 is installed at the outlet. NG heater 15
A conduit 41 is connected thereto. Conduits 50 and 51 are connected to the inlet and outlet of the heat transfer tube 32, respectively, and the NG heater 15 is connected to a conduit 42 that is connected to a separate use, for example, a combustion boiler (not shown). Further, conduits 52 and 53 are connected to the inlet and outlet of the heat transfer tube 31, respectively, and a demister (not shown) is installed in the medium evaporator 12 at a position above the conduit.

The medium evaporator 12 and, for example, an oil separator 16 installed at a lower position are connected by a conduit 70 in which a valve 60 is provided. an oil separator 16;
For example, it is connected to the LNG evaporator 10 through a conduit 71 provided with a valve 61. Further, a conduit 72 provided with a valve 62 is connected to the oil separator 16, and a heat transfer tube 33 is installed therein. The inlet of the heat exchanger tube 33 and the shaft seal portion of the medium turbine 13 are connected by a conduit 73, and the outlet of the heat exchanger tube 33 and the oil tank 17 are connected by a conduit 74. The oil tank 17 and oil pump 18 are
Conduit 75 connects oil pump 18 and cooler 19; conduit 76 connects cooler 19 and media turbine 13.
are connected to the shaft seal portions through conduits 77, respectively.

In the LNG evaporator 10, the vaporized medium is condensed and liquefied by the cold heat of the LNG flowing through the heat transfer tubes 30.
On the other hand, LNG that has been evaporated and vaporized by condensing and liquefying the vaporization medium is heated by the NG heater 15 and then separately sent to the user.

The liquefied medium accumulated at the bottom of the LNG evaporator 10 is
A medium pump 11 supplies a medium evaporator 12 . In the medium evaporator 12, the liquefied medium is evaporated by a heat source such as seawater flowing through the heat transfer tube 31. After passing through the demister, this vaporized medium is supplied to the medium turbine 13 and drives it.

The generator 14 is driven by the drive of the medium turbine 13, and as a result, the cold heat of the LNG is converted into electrical energy and recovered. On the other hand, media turbine 1
3, the vaporized medium whose temperature and pressure have both decreased is circulated and supplied to the LNG evaporator 10, where it is condensed and liquefied again by the cold heat of the LNG.

As this operation continues, the media turbine 1
A small amount of the lubricating oil used in the shaft seal part 3 mixes into the vaporizing medium. The lubricating oil mixed in the vaporized medium is supplied from the LNG evaporator 10 to the medium evaporator 12 while being mixed in the liquefied medium. Medium evaporator 1
In No. 2, the liquefied medium evaporates and vaporizes, but the lubricating oil does not evaporate or vaporize due to its low vapor pressure, and is accumulated in the liquefied medium temporarily retained in the medium evaporator 12. In this way, in the medium evaporator 12,
The lubricating oil concentration in the liquefied medium gradually increases.

As the lubricating oil concentration in the liquefied medium increases, foam begins to form upon boiling of the liquefied medium, the height of which increases in proportion to the lubricating oil concentration in the liquefied medium. If this foam reaches the lower surface of the demister, the liquefied medium will be entrained in the vaporized medium supplied to the medium turbine 13, resulting in trouble in the operation of the medium turbine 13.

Therefore, in this case, before the foam reaches the lower surface of the demister, a predetermined amount of liquefied medium mixed with lubricating oil is poured from the medium evaporator 12 into the conduit 70 by opening the valve 60.
The oil is then discharged to an oil separator 16. The oil separator 16 is used in the shaft seal of the medium turbine 13 and has a temperature of 50°C.
The liquefied medium evaporates and vaporizes using the lubricating oil flowing through the discharged heat transfer tubes 33 as a heat source. This vaporized medium is transferred to the conduit 71 by opening the valve 61.
The LNG is returned to the LNG evaporator 10, where it is condensed and liquefied again by the cold heat of the LNG. Further, the separated lubricating oil is extracted from the conduit 72 by opening the valve 62. In addition, the lubricating oil whose temperature has been lowered by evaporating and vaporizing the liquefied medium and separating it from the oil is supplied to the oil tank 17, where it is temporarily stored and then extracted by the oil pump 18 and cooled to a predetermined temperature by the cooler 19. After being cooled, it is circulated and supplied to the shaft seal of the medium turbine 13 for use.

The method of operating a cold power generation facility as in this embodiment provides the following effects.

(1) Since the foam generated when the liquefied medium boils in the medium evaporator does not reach the bottom of the demister,
The liquefied medium is not entrained in the vaporized medium supplied to the medium turbine, and the operation of the medium turbine can be continued without any hindrance.

(2) Since the operation of the medium turbine can be continued without any trouble, the cold power generation equipment can be operated continuously for a long period of time.

(3) Since the lubricating oil is separated and the Rankine medium from which the lubricating oil has been separated is returned to the Rankine cycle, there is no need to replace or replenish the Rankine medium, thus reducing the increase in Rankine medium costs. It can be prevented.

(4) Since the lubricating oil used and discharged from the shaft seal of the media turbine is used as a heat source to separate the Rankine medium and the lubricating oil, there is no need to install a special heat source generator, and therefore the operation It is possible to reduce costs and equipment costs.

(5) Since the lubricating oil used and discharged from the shaft seal of the medium turbine can be cooled by separating the Rankine medium and the lubricating oil, the capacity of the cooler can be reduced.

〔Effect of the invention〕

As explained above, the present invention allows the liquefied Rankine medium mixed with oil to be heated before the foam generated when the liquefied Rankine medium boils in the medium evaporator reaches the lower surface of the demister installed in the medium evaporator. After being extracted from the evaporator to the oil separator, the lubricating oil discharged from the shaft seal of the medium turbine in the system is used as a heat source to separate the Rankine medium and the oil, and the lubricating oil heat-exchanged by the separation is sent to the medium turbine. At the same time, by returning the separated Rankine medium to the Rankine cycle, the operation of the medium turbine can be continued without any trouble without replacing or replenishing the Rankine medium. It has the effect of being able to drive.

[Brief explanation of drawings]

The drawing shows a Rankine cycle system implementing the present invention.
It is a system diagram of LNG cold power generation equipment. 10...LNG evaporator, 11...medium pump, 12
...medium evaporator, 13...medium turbine, 14...generator, 16...oil separator.

Claims (1)

[Scope of Claims] 1. Rankine cycle type having a medium turbine driven by Rankine medium evaporated in a medium evaporator and a generator connected to the medium turbine.
In the operating method of LNG cryothermal power generation equipment, the liquefied Rankine medium mixed with oil is evaporated before the foam generated when the liquefied Rankine medium boils in the medium evaporator reaches the bottom surface of the demister installed inside the medium evaporator. After extracting from the vessel to the oil separator,
The lubricating oil discharged from the shaft seal of the medium turbine in the system is used as a heat source to separate the Rankine medium and oil, and the lubricating oil that has been heat exchanged by the separation is returned to the medium turbine, and the separated Rankine medium is transferred to the Rankine medium. A method of operating a cold power generation facility characterized by returning to a cycle.