JPS6212362B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for storing and extracting steam using a vertical steam accumulator.

A steam accumulator uses a steam injection nozzle to inject steam into the water filled in a pressure vessel from the outside, and uses the latent heat generated when the steam condenses inside the vessel to raise the temperature of the water inside the vessel. The steam is stored as high-temperature, high-pressure saturated water by increasing the pressure (as the pressure rises with It self-evaporates and is released to the outside.

By the way, there are two types of steam accumulators: horizontal type where the pressure vessel is installed horizontally and vertical type where the pressure vessel is installed vertically. They have the advantage of being able to store large amounts of steam, and are often used to reduce site space.

Fig. 1 shows a conventional vertical acumulator without internal devices, which is very simple and includes a vertical pressure vessel 1, a steam injection pipe 2, and a steam injection nozzle 3.
and a steam outlet pipe 4, and water W inside the pressure vessel 1.
is accommodated.

In the case of this accumulator, if steam P is injected into the container 1 from the nozzle 3 via the steam injection pipe 2, the water W above the nozzle 3 is warmed first, and the steam space around the nozzle or above the container is heated. Part 5
The pressure of is gradually increased and steam injection ends when the pressure becomes equal to the pressure of the injected steam. At this time, the water W below the nozzle 3 is warmed to some extent by natural convection, but it stagnates and remains at a temperature considerably lower than the saturation temperature corresponding to the pressure in the steam space 5. Moreover, not only such a temperature difference occurs in the vertical direction, but also a temperature difference occurs in the radial direction in the pressure vessel 1 having a large diameter.

If such a temperature difference occurs at the end of steam injection, only a small amount of heat can be stored relative to the volume of the container 1, resulting in a low heat storage density. In addition, if the above temperature difference remains within the container, even when steam is extracted, the position of bubbles generated by self-evaporation of saturated water due to reduced pressure will be unstable, and the container 1
The flow of water inside becomes irregular. This irregular water flow makes the bubble generation position even more unstable.

When steam stored in a steam accumulator is sent to a steam turbine for power generation, etc., the steam must be as dry and saturated as possible, and if the steam contains water droplets, they may dissolve. Solid content settles in the steam turbine, causing problems such as vibration. In order to prevent such a phenomenon in which water droplets are entrained with steam (carry over), it is desirable that the position of steam bubbles generated in the steam accumulator be as close to the water surface as possible. If this occurs, the bubble becomes a large bubble as it rises to the water surface, and when the bubble bursts on the water surface, it produces many water droplets, resulting in the water droplets being entrained along with the steam.

As mentioned above, if the position where bubbles are generated is unstable, there is a high probability that bubbles will be generated at a deep position, and the rise of the liquid level will increase the number of carryovers.

In order to eliminate such drawbacks when steam is injected and when steam is released and taken out, conventional methods as shown in Fig. 2 are used.
Circulation tubes 6, 7 and a cap 8 are provided in the container 1, and when the water W in the container 1 is injected with steam, a water circulation as shown by the solid line arrow occurs, and when the steam is released and taken out, a water circulation as shown by the dotted line arrow occurs. Let it flow like this,
Efforts have been made to always maintain a uniform temperature. To explain the mechanism of this water circulation in detail, first, during steam injection, when steam P is blown from the steam blowing nozzle 3 provided inside the circulation cylinder 6, the water inside the circulation cylinder 6 is rolled up, which is the so-called injector effect. The water in the circulation cylinder 6 rises due to the presence of air bubbles in the circulation cylinder 6.
The difference in density between the inside and outside (surroundings) causes circulation as shown by the solid arrows. In addition, when steam is released and taken out, air bubbles generated in the accumulator are collected by the cap 8, and a difference in density occurs between the center and the outer circumference of the container 1, so that the circulation cylinder 7 becomes an ascending pipe as indicated by the dotted line arrow. Circulation as shown in is generated, and bubbles are generated near the top of the circulation cylinder 7.

However, even in the case of a steam accumulator equipped with an internal device as shown in Fig. 2, when the pressure of the injected steam approaches the internal pressure of the steam accumulator and the amount of injected steam gradually decreases, the circulation of water W stops. It becomes very gradual, and at the end of steam injection, a temperature difference of several degrees occurs within the accumulator, which also deteriorates the heat storage density.

In addition, during steam release and extraction, while water circulation is occurring as shown by the dotted line arrow in Figure 2, bubbles generated by self-steam are generated from inside the circulation cylinder 7, and are generated from a position relatively close to the water surface. Therefore, it is possible to stably obtain steam with high purity.However, if the pressure is reduced when water circulation has not yet occurred at the start of steam release, bubbles will be generated everywhere in the accumulator at once, resulting in a bumping condition. , a phenomenon similar to that of the accumulator of FIG. 1 without internal devices occurs. If this state continues for a while, water circulation as shown by the dotted line arrow in Figure 2 will gradually occur and a transition will occur to stable self-evaporation. The generated steam contains many water droplets, resulting in poor steam purity.

Furthermore, the above-mentioned transient time tends to become longer as the difference in water temperature within the accumulator immediately before the start of steam release and extraction is larger, and this has been confirmed through visualization model experiments as shown in FIG. 3.

As is clear from the above explanation, the water circulation in the conventional vertical steam accumulator is a natural circulation.
At the end of steam injection, a temperature difference occurs in the water temperature within the accumulator, reducing the heat storage density.
At the start of steam release and extraction, there was a problem in that there was no water circulation and the difference in water temperature within the accumulator resulted in unstable evaporation, which deteriorated the purity of the steam.

This invention was made in order to solve the above-mentioned conventional problems, and the water in the accumulator is forcibly circulated from the bottom to the top just before the end of steam injection and just before the start of steam release extraction. This system is characterized in that the water temperature is made uniform, the heat storage density is increased, and the discharged steam is of high quality and does not contain water droplets.

Hereinafter, an example of the method of the present invention will be explained with reference to the drawings of FIGS. 4 to 6.

FIG. 4 is a schematic explanatory diagram of a vertical steam accumulator for carrying out the method of the present invention, and its structure is similar to that shown in FIG. Attaching the nozzle 9,
The difference is that warm-up steam can be blown upward from near the bottom of the pressure vessel 1 (common parts with FIG. 2 are given the same reference numerals). The storage of steam in the above-mentioned accumulator is carried out by injecting steam P into the water W filled in the pressure vessel 1 using the steam injection nozzle 3, as in the conventional case. Immediately before the end of the heating process, high pressure steam P' is injected from the heating steam injection nozzle 9 to cause the water in the accumulator (pressure vessel) to flow from below to above and from above to below, as shown by the solid line arrows in Figure 4. The temperature of the water W is made uniform in the end so that there is no temperature difference as in the conventional method, and the amount of heat storage (heat storage density) is
I'm trying to increase that. In addition, when releasing and taking out the steam stored in this way, high-pressure steam P' is blown from the steam blowing nozzle 3 for a short period of time (for example, about 10 to 60 seconds) just before the start of the release and removal. Water (saturated water) is circulated in advance so as to generate a water flow as shown by the dotted arrow in Figure 4 (this flow direction is the same as the flow shown by the solid arrow when steam is injected), and then the water is circulated in the container as before. The pressure is reduced and the stored steam is released and removed. If the above-mentioned method is carried out before releasing and taking out the stored steam, water circulation is already occurring in the accumulator when steam release starts, so the bumping phenomenon that occurs in the conventional case does not occur, and the start of steam release is prevented. At the same time, saturated water self-steams stably, and high-quality steam containing no water droplets can be obtained.

FIG. 5 shows a system in which the upper water W inside the accumulator is sucked out by a circulation pump 10 installed outside the accumulator, and can be blown upward from the outlet 11 at the bottom of the container. Water circulation as described above is carried out immediately before the end of steam injection into the container 1 and immediately before the start of release and withdrawal of stored steam. In this case, the pump 10 does not have to be installed externally, but a submersible pump installed inside the accumulator can be used instead.

FIG. 6 shows an axial flow rotary vane 13 rotatably driven by a motor 12 at the bottom of the circulation cylinders 6 and 7 of the accumulator.
is provided, and the rotating blade 13 is rotated immediately before the end of steam injection and immediately before the start of steam release extraction,
This forces water circulation as shown by the dotted arrows.

As explained above, in the method for storing and extracting steam using the vertical steam accumulator of the present invention, the water in the accumulator is caused to flow from below to above immediately before the end of steam injection and immediately before the start of discharging and extracting stored steam. Since it is forced to circulate so that it occurs, it has the following effects.

(1) The temperature of the water in the accumulator is made uniform by forced water circulation just before the end of steam injection.
Heat storage density can be increased.

(2) Forced water circulation immediately before the start of release of stored steam can prevent the conventional bumping phenomenon, and at the same time as the start of release of steam, saturated water stably self-evaporates, forming water droplets. You can get high-quality steam that does not contain

[Brief explanation of the drawing]

Figures 1 and 2 are schematic explanatory diagrams showing the method of storing and extracting steam using a conventional vertical steam accumulator, and Figure 3 shows the upper and lower sides of the accumulator in which the problems of the above conventional method were confirmed through visualization model experiments. Figures 4 to 6 are schematic diagrams showing the method for storing and extracting steam using the vertical steam accumulator of the present invention. FIG. 4 is an explanatory diagram, in which the water circulation immediately before the end of steam injection is performed by blowing high-pressure steam from the warmer steam injection nozzle, and the water circulation immediately before the start of releasing and taking out the stored steam is performed by blowing steam from the steam injection nozzle. FIG. 5 shows an embodiment in which the water circulation is carried out by a circulation pump immediately before the end of steam injection and immediately before the start of steam discharge and withdrawal, and FIG. shows an embodiment in which water circulation as described above is performed by a rotary blade provided in an accumulator. DESCRIPTION OF SYMBOLS 1... Pressure vessel, 2... Steam injection pipe, 3... Steam blowing nozzle, 4... Steam outlet pipe, 5... Steam space, 6, 7... Circulation tube, 8... Umbrella, 9... …
Warmer steam injection nozzle, 10...Circulation pump, 1
2...Motor, 13...Rotating blade, W...Water (saturated water).

Claims (1)

[Claims] 1. By injecting steam with a steam injection nozzle into water filled in a pressure vessel, storing this steam as high temperature, high pressure saturated water, and reducing the pressure inside the vessel, In a vertical steam accumulator in which a part of the saturated water self-evaporates and the stored steam can be released and taken out, immediately before the end of steam injection into the pressure vessel and just before the start of releasing and taking out the stored steam. A method for storing and extracting steam using a vertical steam accumulator, characterized in that water in the accumulator is forcibly circulated so that water flows from below to above.