JPH07117549B2 - Gas-liquid two-phase flow experimental device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a gas-liquid two-phase flow experimental apparatus, and more specifically, when a high pressure air is stored underground, a submerged method for compensating the atmospheric pressure with hydrostatic pressure is used. The present invention relates to a gas-liquid two-phase flow test device for testing the so-called champagne effect that occurs.

[Prior Art] Recently, in order to improve thermal efficiency in a power generation system using a gas turbine, high pressure air is generated by electric power on holidays or at night and stored in an underground tank (underground 500m to several 1000m) for peak power during daytime. It is considered to use the stored high pressure air as combustion air for a gas turbine. In this case, there are a pressure change method in which the pressure in the tank decreases due to the use of the stored high pressure air and a constant pressure method in which the pressure change due to the use of the high pressure air is compensated by using a water head. It is necessary to improve the pressure resistance of the tank itself due to a drastic change in the pressure of, and there is a problem in durability. On the other hand, the latter is advantageous in terms of equipment because it utilizes water pressure at that position underground to balance it, and this constant pressure system is said to be preferable.

However, in this constant pressure system, part of the high-pressure air stored in the tank dissolves in water, and when this water rises in the downcomer, it suddenly changes to gas and expands in volume, the so-called "champagne effect". Not only does this lead to a loss of stored energy, but the stability of the cavities that make up the tank is also affected.

Specifically, as shown in FIG. 7, high pressure air is supplied to the underground tank 1 from the compressed air supply device 2 for gas turbine combustion used for gas turbine power generation via the high pressure air pipeline 3. On the other hand, water is supplied from the reservoir 4 through the downcomer pipe 5 into the underground tank 1. The pressure in the underground tank 1 is kept constant by the water head difference between the reservoir 4 and the underground tank 1.

By the way, in the water in this underground tank 1, compressed air will melt | dissolve in water according to the pressure in the water surface under pressure. Then, the hydrostatic pressure becomes water saturated with air according to the water temperature, and a saturated layer is formed. If compressed air is further fed into the underground tank 1 in this state, the water level will decrease, while the water between the tank 1 and the downcomer pipe 5 will rise through the downcomer pipe 5. At this time, as the water in the underground tank 1 and the passage communicating with the underground water rises in the downcomer pipe 5, the air that has been dissolved in the high-pressure water is melted and bubbles are generated along with the decrease in pressure. When the bubbles ascend in the downcomer 5, the volume of the bubbles rapidly expands to form a large amount of bubbles, which causes a champagne effect. As a result, it is known that the amount of bubbles that have escaped into the atmosphere results in a loss of stored energy, while the air blows out instantly, affecting the stability of the underground tank 1 and the cavity communicating with it. (For example, see No. 219 Electric Power Civil Engineering 1989.3).

[Problems to be Solved by the Invention]

However, the actual condition of this champagne phenomenon has not been sufficiently clarified. That is, the dissolution of the compressed air is affected by the pressure and temperature, and the dissolution rate is unknown.

On the other hand, regarding the gas-liquid two-phase flow in the downcomer, it is necessary to clarify various points such as water flow velocity, air flow velocity, air holdup, and flow state. However, in the present situation, there is no suitable experimental device for clearly knowing the champagne phenomenon.

[Means for Solving the Problems]

The present invention has been made in order to solve the above-mentioned problems of the prior art, and a downcomer pipe is provided between an upper water tank installed on the ground and a lower water tank installed underground. An ascending pipe is connected, a water pump is provided in the descending pipe, and an air pump is provided in the lower water tank. The lower part of the ascending pipe is connected to the lower water tank, and a means for supplying pressurized air is provided. It is a gas-liquid two-phase flow experimental device provided with means for detecting the state of the water flow.

More specifically, the upper water tank is provided with a downcomer having a circulation generator in the middle, and an upcomer having an air supply device at the lower end and a detector in the middle, and the downcomer has an inlet and a lower water tank. One end of the pipeline is connected to each other via a valve between the circulation generator and the inlet of the lower water tank, and the outlet of the lower water tank and the other end of the pipeline are connected to the rising pipe via a valve. It is a gas-liquid two-phase flow experimental device that is connected and has a pressurized air supply device in the lower water tank.

[Work]

Air is dissolved in the lower water tank and the water in the lower water tank is caused to flow into the rising pipe, so that the generation state and flow state of bubbles can be observed.

〔Example〕

An embodiment of the gas-liquid two-phase flow experimental apparatus according to the present invention will be described below with reference to FIGS. 1 to 6.

FIG. 1 is a schematic side view, and 11 is an upper water tank installed on the ground or at a position where it can be handled in the same manner as the ground.
And a lower water tank 14 and a pipe 15 for bypassing the lower water tank 14 are provided underground.

The lower water tank 14 and the pipeline 15 are, for example, a vertical shaft that has been abandoned, and are installed about 500 m underground.

More specifically, as shown in FIG. 2, a water pump 16 as a “circulator” and a three-way valve 17 are provided at the lower part of the downcomer 12, and a lower water tank is provided at the lower end thereof.
14 inflow ports 18 are connected. On the other hand, at the lower end of the rising pipe 13, an air pump 19 as an “air supply device” is provided with a valve 20.
Located through and through valve 21 lower water tank
It is connected to 14 outlets 22.

As shown in FIG. 3, a pressure gauge 23 and an observation window 24 are provided in the middle of the ascending tube 13. Further, the outlet side of the water pump 16 provided in the descending pipe 12 and the lower end of the ascending pipe 13 are connected by a pipe line 15 so as to bypass.

Further, an air pump 25 for supplying pressurized air as dissolved air to the lower water tank 14 is connected via a valve 26.

A deflector plate 27 is provided in the lower water tank 14 for blocking the water flow and causing the water flow to meander.In the lower water tank 14, a kind of agitation for quickly dissolving the air supplied by the air pump 25. Acts as a device.

[Experiment with air-dissolved water]

In the above structure, as shown in FIG.
The bypass pipe 15 is closed by operating 17 to connect the descending pipe 12 and the lower water tank 14 and close the valve 20, and open the valve 21 to connect the lower water tank 14 and the ascending pipe 13.

After that, the air pump 25 is operated and 50 + αatm (this pressure is for dissolving air in water, usually 50 ~
It is preferred to use pressures in the range of 51 atm. ) High pressure air is supplied into the lower water tank 14. Then, after holding for a predetermined time to dissolve the air into the water according to the pressure and the temperature, the water pump 16 is operated to generate the water flow in the arrow F direction. Then, the water in which air is dissolved in the lower water tank 14 rises in the rising pipe 13. As the water rises,
Although the pressure drops, the air dissolved in the high-pressure water melts out and bubbles are generated.

The observation window 24 shown in FIG.
Then, the data of the pressure change is taken into the pressure gauge 23 while observing with a monitor TV etc.
Actually, by providing a plurality of detecting devices in the vertical direction of the rising pipe 13, the data can be properly fetched.

[Experiment with compressed air inflow]

FIG. 5 is an explanatory view of the situation in which the growth and flow velocity of bubbles are simply tested. First, the three-way valve 17 and the valve 2 are shown.
By operating 0 and 21, the ascending pipe 13 and the descending pipe 12 are communicated with each other using the conduit 15. Then, the air pump 19 is operated and the rising pipe 13
Inject microscopic bubbles into the bottom of the.

When the water pump 16 is further operated, the water flow F'in this pipe line 15
Occurs, and the fine-grained bubbles B rise in the ascending tube 13 along with the water flow F ', and the pressure thereof gradually decreases, and the bubbles B grow in accordance with this pressure decrease. The growth state, the flow velocity state, or the pressure change of the bubble B can be detected by the detection device and the data can be taken in as in the above.

[Experiment with compressed air inflow]

FIG. 6 shows another embodiment, in which the downcomer pipe 12 and the upcomer pipe 13 are provided with pressurizing means 28 and 29, respectively, to generate a large water pressure as compared with the lengths of the downcomer pipe 12 and the upcomer pipe 13. It is designed to work.

According to the above configuration, the lower water tank 14 is
Since the internal pressure is not obtained, it is not necessary to install the lower water tank 14 in the deep underground, and the required pressure is obtained by the pressurizing means 28 and 29. Therefore, these pressurizing means 28, 29
Experiments for observing bubble growth, flow velocity state, etc. at various pressures are possible depending on the operating conditions.

The upper water tank is usually installed on the ground, but in some cases, it can be installed underground near the ground. In this sense, the installation at a portion closer to the ground surface than the lower water tank was explained as an upper water tank installed on the ground.

〔The invention's effect〕

As is clear from the above description, in the gas-liquid two-phase flow experimental apparatus according to the present invention, the upper water tank installed on the ground and the lower water tank installed underground are connected by the downcomer pipe and the upcomer pipe. Then, a water pump is provided in the descending pipe, an air pump is provided in the lower water tank, the lower part of the ascending pipe is connected to the lower water tank, a means for supplying pressurized air, and a state of rising water flow. Is provided.

Therefore, there is an effect that the champagne phenomenon that occurs in the rising pipe due to the air dissolved in the pressurized water can be easily confirmed by an extremely simple means.

[Brief description of drawings]

1 to 6 show an embodiment of a gas-liquid two-phase flow experimental apparatus according to the present invention. FIG. 1 is a schematic side view and FIG.
The drawing is an enlarged view of an A portion of FIG. 1, and FIG. 3 is an enlarged view of a B portion of FIG.
4 and 5 are explanatory views of the operation, FIG. 6 is a side view of another embodiment, and FIG. 7 is a schematic view of a constant pressure type high pressure gas storage system. 1 ... Underground tank, 2 ... Compressed air supply device 3 ... High-pressure air pipeline, 4 ... Reservoir 5 ... Precipitation pipe, 11 ... Upper water tank 12 ... Down pipe, 13 ... Rise pipe 14 ... … Lower water tank, 15 …… Pipe 16… Water pump, 17 …… Three-way valve 18 …… Inlet, 19,25 …… Air pump 20,21,26 …… Valve, 22 …… Outlet 23… … Pressure gauge, 24 …… Observation window 27 …… Drift plate, 28 …… Pressurizing means 29 …… Depressurizing means

Claims (1)

[Claims] 1. An upper water tank installed on the ground and a lower water tank installed underground are connected by a downcomer pipe and an upcomer pipe, and a water pump is installed in the downcomer pipe and an air is installed in the lower water tank. A gas-liquid two-phase flow experimental apparatus comprising a pump, a lower portion of the rising pipe connected to the lower water tank, means for supplying pressurized air, and means for detecting a rising water flow state.