JPS6213488B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of operating a cold power generation facility, and particularly relates to a method of operating a cold power generation facility suitable for continuous operation of a Rankine cycle LNG cold power generation facility in a favorable manner and over a long period of time. It is something.

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

The operating method of a conventional Rankine cycle type LNG cold-thermal power generation facility will be explained with reference to FIG.

In Fig. 1, the Rankine cycle LNG cryogenic power generation equipment includes an LNG evaporator 10 and a medium pump 11.
, a medium evaporator 12 , a medium turbine 13 , and a generator 14 .

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

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 connected to is connected. Conduits 50 and 51 are connected to the inlet and outlet of the heat exchanger tube 32, respectively, and the NG heater 15 is connected to a conduit 42 connected to a separate use, for example, a combustion boiler (not shown). Further, conduit pipes 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 pipes 52 and 53, respectively.

In the closed cycle, a predetermined amount of fluorine compounds such as Freon R-22 and Freon R-13B1, and hydrocarbons whose main components are propane are sealed as Rankine media.

The vaporized Rankine medium (hereinafter referred to as vaporized medium) in the LNG evaporator 10 is transferred from the LNG storage tank.
The LNG is supplied to the heat exchanger tube 30 from the conduit 40 via the LNG pump, is condensed and liquefied by the LNG flowing through the heat exchanger tube 30, and is temporarily retained at the bottom of the LNG evaporator 10. On the other hand, LNG is vaporized by condensing and liquefying the vaporization medium and passes through the conduit 41 to the NG heater 15.
supplied within. This vaporized LNG (hereinafter referred to as NG
) is supplied to the heat exchanger tube 32 from the conduit 50, flows through the heat exchanger tube 32, and is discharged to the outside of the system from the conduit 51. After being heated to a predetermined temperature by a heat source, for example, seawater, it is passed through the conduit 42 and used separately. Sent to destination.

The condensed and liquefied Rankine medium (hereinafter abbreviated as liquefied medium) is transferred from the LNG evaporator 10 to the medium pump 1.
1 to the medium evaporator 12 via conduits 20, 21. The liquid medium supplied to the medium evaporator 12 and retained therein is supplied to the heat exchanger tube 31 through the conduit 52, flows through the heat exchanger tube 31, and then is heated by a heat source such as seawater, which is discharged to the outside of the system through the conduit 53. be done. This heating causes the liquefied medium to boil, and a portion of it is evaporated and vaporized. After passing through the demister, this vaporized medium is fed via conduit 22 to medium turbine 13 .

The vaporized medium is expanded to atmospheric pressure in the medium turbine 13, and the energy generated at this time is converted into mechanical energy by rotating the medium turbine 13, and further converted into electrical energy by driving the generator 14. will be collected. The vaporized medium, whose temperature and pressure have decreased by being expanded to atmospheric pressure in the medium turbine 13, is circulated and supplied to the LNG evaporator 10 via the conduit 23, where it is condensed and liquefied again by the cold heat of the LNG.

This method of operating cold power generation equipment has the following drawbacks.

In order to prevent the vaporized medium from leaking into the atmosphere from the shaft seal of the media turbine, a shaft seal mechanism such as an oil film seal or mechanical seal is generally employed on the shaft of the media turbine that is in contact with the atmosphere. . 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, it is unavoidable that a small amount of lubricating oil from the shaft seal mechanism gets mixed into the vaporized medium. Due to problems such as damage to the lubricating oil, a large amount of lubricating oil may temporarily become mixed into the vaporizing medium. 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 liquid 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, droplets are generated when the liquefied medium boils, and the height of the droplets increases as the lubricating oil concentration increases. If the boiling surface foam height increases and the foam reaches the demister, the liquefied medium will be entrained in the vaporized medium supplied to the medium turbine. The amount of entrained liquefied medium increases as the lubricating oil 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 properly. Incidentally, such a situation also occurs when other oils having low vapor pressures are mixed in.

Conventionally, when such a situation occurs, the solution is to temporarily stop the operation and replace it with a new Rankine medium, which makes it impossible to operate the cold power generation equipment continuously for a long period of time. At the same time, a large amount of Rankine media is required, which increases Rankine media costs.

An object of the present invention is to provide a method for operating a cold power generation facility that can operate the cold power generation facility smoothly and continuously over a long period of time by eliminating the drawbacks of the prior art described above.

The feature of the present invention is to reduce the oil concentration in the liquefied medium remaining in the medium evaporator to such a concentration that the height of the foam generated when the liquefied medium boils is smaller than the distance between the liquid level of the liquefied medium and the lower surface of the demister. By adjusting
without temporarily stopping the operation of cold power generation equipment.
The object of the present invention is to suppress entrainment of the liquefied medium into the vaporized medium supplied to the medium turbine.

An embodiment of the present invention will be described with reference to FIGS. 2 to 4. Note that in FIG. 2, the same equipment as in FIG. 1 is indicated by the same reference numerals, and the explanation thereof will be omitted.

In FIG. 2, the medium evaporator 12 and, for example, the oil separator 16 installed at a lower position are connected to the valve 60.
are connected by a conduit 70 provided with. The oil separator 16 and, for example, the LNG evaporator 10 are connected to the valve 6
1 is connected by a conduit 71 provided with the same. Further, a conduit 72 provided with a valve 62 is connected to the oil separator 16, and, for example, a heat transfer tube 33 is connected to the oil separator 16.
is installed inside. Conduits 54 and 55 are connected to the inlet and outlet of the heat exchanger tube 33, respectively.

In FIG. 3, a demister 80 is installed in the medium evaporator 12 at a position above the level of the liquefied medium remaining at a predetermined distance H from the surface of the liquefied medium.

Figure 4 is a diagram showing the relationship between the oil concentration in the liquefied medium in which the experiment was conducted and the height of foam generated during boiling, showing Freon R-22 and Freon R-
13B1 and propane are used.

In FIG. 4, regardless of the type of Rankine medium, foam is generated when the oil concentration is approximately 0.2 (volume %), and as the oil concentration increases beyond this level, the height of the foam increases proportionally.

The entrainment of the liquefied medium into the vaporized medium supplied from the medium evaporator 12 to the medium turbine 13 via the conduit 22 occurs due to the gap H between the liquid level of the liquefied medium in the medium evaporator 13 and the lower surface of the demister 80, as described above. It is determined by the relationship between the foam height and the foam height. In other words, in order to suppress the entrainment of the liquefied medium into the vaporized medium, it is necessary to suppress the foam height to below the interval H.
The oil concentration must be adjusted to at most the concentration shown in equation (1).

Q=2.7×10 ^-3 H+0.2 ...(1) Where, Q: Oil concentration (volume %) H: Distance between the liquid level of the liquefied medium in the medium evaporator and the bottom surface of the demister (mm) In this case , the oil concentration is properly adjusted as follows.

The valve 60 is opened and the liquefied medium is extracted and supplied from the medium evaporator 12 to the oil separator 16 via the conduit 70 using the liquid head difference. In the oil separator 16, the liquefied medium is supplied to the heat exchanger tubes 33 through the conduit 54.
It is heated by a heat source, for example, seawater, which is discharged from the system through a conduit 55 after passing through the water. This heating evaporates and vaporizes the liquefied medium and separates it from the oil.
Thereafter, by opening the valve 60, the vaporized medium is transferred from the oil separator 16 to the LNG evaporator 10 via the conduit 71.
Here, after being condensed and liquefied again by LNG, it is passed through the medium pump 11 to the conduits 20, 2.
1 to the medium evaporator 12. on the other hand,
The separated oil is discharged from the oil separator 16 via the conduit 72 by opening the valve 62.

Such oil concentration adjustment operation may be carried out periodically or depending on the oil concentration in the liquefied medium in the medium evaporator.
This can be done ad hoc or continuously.

In the operating method of the cold power generation equipment as in this embodiment, the oil concentration in the liquefied medium that remains in the medium evaporator, boils, partially evaporates, and vaporizes, and the height of the bubbles generated at the time of boiling increases the oil concentration in the liquefied medium in the medium evaporator. By appropriately adjusting the concentration so that the distance between the liquid level and the bottom surface of the demister is below, it is possible to suppress entrainment of the liquefied medium into the vaporized medium supplied to the medium turbine without replacing the Rankine medium. It is possible to prevent the occurrence of vibrations and abnormal noises in the medium turbine, allowing the medium turbine and, by extension, the cold power generation equipment to operate smoothly and continuously over a long period of time. Furthermore, since there is no need to replace the Rankine medium, the cost of the Rankine medium can be significantly reduced.

As explained above, the present invention aims to reduce the oil concentration in the liquefied medium that stays in the medium evaporator, boils, partially evaporates, and vaporizes, and the height of the bubbles generated when the liquefied medium boils. By adjusting the concentration to be smaller than the distance between the surface and the lower surface of the demister, entrainment of the liquefied medium into the vaporized medium supplied to the medium turbine can be suppressed without replacing the Rankine medium. This has the effect of preventing the generation of vibrations and abnormal noises, allowing the medium turbine and, by extension, the cold power generation equipment to operate smoothly and continuously over a long period of time.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of a conventional Rankine cycle type LNG cryogenic power generation facility, Figs. 2 to 4 illustrate an embodiment of the present invention, and Fig. A system diagram showing an example of a cycle type LNG cryogenic power generation facility, FIG. 3 is a longitudinal cross-sectional view of a medium evaporator, and FIG. 4 is a diagram showing the relationship between oil concentration and foam height. 10...LNG evaporator, 11...medium pump,
12...Medium evaporator, 13...Medium turbine, 1
4... Generator, 16... Oil separator, 80... Demister.

Claims (1)

[Claims] 1. In a Rankine cycle type LNG cryothermal power generation facility, the oil concentration in the Rankine medium retained in the medium evaporator is determined by the height of the bubbles generated when the Rankine medium boils, the liquid level of the Rankine medium, and the liquid level of the Rankine medium. A method of operating a cold power generation facility, characterized by adjusting the concentration to be smaller than the distance between the demister and the lower surface of the demister installed in the evaporator. 2 The oil concentration in the Rankine medium should be increased at most.
2.7×10 ^-3 H+0.2 (volume %) (where H: the distance between the liquid level of the Rankine medium in the medium evaporator and the lower surface of the demister), according to claim 1. How to operate cold power generation equipment.