JPS6134044B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a water sealing device in a gas flow path. The device of the present invention is particularly useful as equipment for preventing flashbacks in flare devices.

When applying a water seal to a gas flow path, if the gas is unevenly dispersed in the liquid or bubbles form during the gas passage through the water sealing device, this will cause large waves on the liquid surface. , when the gas flow rate increases further, a large upwelling wave is reached. As a result, the gas flow in the discharge pipe from the water seal device becomes a large pulsating flow. I want to prevent this kind of phenomenon as much as possible. For example, a water seal drum is placed in the flow path of the gas sent to the flare device to prevent backfire, but if the drum does not work properly, a phenomenon of breathing occurs in which the flame of the burner increases or decreases. There are social and environmental problems such as noise pollution and discontinuous noise, which can make local residents feel uneasy.

In general, a water seal device basically consists of a tank that houses the water seal liquid, a gas inlet pipe that extends downward from the top of the tank and opens below the liquid level, and a gas discharge pipe at the top of the tank. The lower end of the gas inlet pipe is made with sawtooth notches or a number of vertical slits from which the gas is blown out into the liquid.

When the water-sealing effect was observed in detail, the following phenomena were observed. That is, when the gas flow rate is relatively low, the bubbles become large and rise intermittently, so that the liquid level tends to move up and down near the center of the tank where the gas introduction pipe is located. When the gas flow velocity becomes medium, the liquid level becomes tilted and begins to vibrate from side to side. When the gas flow rate increases further, parts of the droplets are blown up intermittently. At this time, the gas flow in the gas exhaust pipe becomes a pulsating flow, which causes a breathing phenomenon in which the combustion flame of the flare device becomes larger and smaller, and generates discontinuous noise. When the blow-up becomes severe, a large amount of water-sealing liquid rises and falls in the discharge pipe, which causes a vibration phenomenon. Therefore, such a phenomenon must be avoided in a water sealing device.

In order to eliminate these drawbacks in water sealing devices, it was found that the gas should be uniformly blown out into the water in the form of as small bubbles as possible to minimize undulations on the liquid surface. Therefore, various efforts have been made to improve the gas introduction pipe, such as making a large number of holes in the part below the liquid level, and installing a perforated plate that spreads in the radial direction at the lower end and blowing out the gas from below. There have been proposals for structures that allow this. However, none of them could be said to be sufficiently effective.

In view of these circumstances, the present invention has devised a method to uniformly blow out the small gas bubbles described above,
This was created as a result of research on water seals that do not cause liquid level waves over a wide range of gas flow velocities.

The gas water sealing device of the present invention will be described with reference to FIG. In a water seal device 1 which is provided with a gas introduction pipe 4 that opens below the surface and also has a gas discharge pipe 5 above the tank 3, the lower end 4 of the gas introduction pipe 4
1 and below the liquid level WL, a gas dispersion box 6 is installed around the gas introduction pipe 4 in the shape of a concentric hollow disk and having a large number of gas outlets at the top. Features.

The details of the gas distribution box 6 are as shown in FIGS. 2 to 4, and the bottom and sides of the hollow disc-shaped box are closed, and the gas outlet ports 61, 61, . . . are closed only at the top. ... are provided in large numbers. The gas introduction pipe 4 and the gas distribution box 6 are connected through slits 7, 7, . . . . 62 is
It is a radiation partition plate that divides the inside of the box into equal parts (8 parts in the figure), and is provided corresponding to the slit 7.
This helps in equalizing the amount of gas blown out between each compartment. The stay 63 is for the purpose of reinforcement and may be provided below, but if it is provided above, it can be expected to have some effect of inhibiting the lateral wave motion near the liquid surface of the water-sealing liquid 2.

Gas outlet ports 61, 6 on the top surface of the gas distribution box 6
From the standpoint of uniformly dispersing the gas over the entire surface even when the amount of gas is small, the opening ratio of 1,...... increases as the distance from the gas introduction pipe 4 in the center increases, that is, toward the periphery of the box. It is preferable to gradually increase the distance as you get closer. There are two methods: a method in which holes of the same diameter are provided closer to the outside, and a method in which the density of holes is the same but the diameter of each hole is made larger toward the outside.

In general, it is preferable that the hole diameter of the gas outlet be small, since large bubbles tend to cause waves in the water ring liquid surface. However, the smaller the hole diameter, the more holes need to be drilled, which not only increases the labor involved in machining, but also reduces the distance between adjacent air outlets, causing bubbles to coalesce.
You won't get the effect you expected. According to experience, a diameter of 3 to 20 mm, particularly 5 to 10 mm, is suitable. Note that the fact that the range of suitable hole diameters is limited means that there are restrictions on changing the hole diameter of the gas outlet as a means of providing the aperture ratio that varies along the radial direction of the gas distribution box. means. Further, porous plates having holes in the size range described above are in high demand as parts of various devices and are available on the market. When using it, the aperture ratio cannot be changed, but it is also wise to use an off-the-shelf product to reduce the manufacturing cost of the device.

The amount of gas supplied to the gas distribution box 6 can be determined by the width of the slit 7 provided in the gas introduction pipe 4. From the viewpoint of gas dispersibility, it is better to narrow down the gas passage area a little here, but if the degree of opening of the slit is too small, the pressure loss will naturally increase. Therefore, the degree of opening of the slit should be determined in consideration of the allowable pressure loss. When the tolerance for pressure loss is very small, the opening degree of the slit will be increased, but excessively increasing it will not help in reducing pressure loss, and conversely, it may cause drifting when the gas amount is small. , which will cause waves on the water ring liquid surface. According to experience, it is appropriate to keep the total area of the slits 7 to about one or two times the cross-sectional area of the gas introduction pipe.

The lower end 41 of the gas introduction pipe is open as in conventional water sealing devices, but this may increase pressure loss even if a large amount of gas temporarily flows for some reason. It is intended to be sent quickly through the water seal. lower end 41
The serrated cutout shown in the figure is used to divide the gas into as many small parts as possible so that the gas can be dispersed and released into the water-sealing liquid. The leg length H is designed so that the gas is discharged through the outlet 61 of the dispersion box 6 and does not reach the lower end 41 of the introduction pipe 4 in the normal gas flow rate range.

The above description of the gas water sealing device of the present invention is directed to the case where the tank is vertical and has a circular cross section and there is one gas introduction pipe in the center. Other aspects are also possible.
For example, as shown in FIG.
By attaching ......, it is possible to create a large-capacity device. In addition, as shown in FIGS. 6A and 6B, a horizontal water seal tank 3 is used, and the gas introduction pipe is branched into several pipes as shown in the figure as three pipes 42, 42, and 42. Good too. In this case, it is recommended to partition each distribution box 6, 6, 6 with partition plates 8, 8. Thereby, it is possible to prevent the water sealing liquid 2 from flowing in the lateral direction, and to prevent vibrations in the liquid surface, particularly in the longitudinal direction of the tank.

In the gas water seal device of the present invention, the gas is divided into small bubbles and released uniformly into the tank, so waves in the liquid level are hardly a problem, and even if the flow rate of passing gas fluctuates, the water seal There is no need to worry about the device pulsating. Even if the gas flow rate fluctuates widely, it has great flexibility and can always perform water sealing in a stable state.

Because it is difficult for liquid surface waves to occur, the liquid depth of the water seal liquid is
WSL can be made extremely small. With conventional equipment
Although a WSL of 10 cm or more was required, according to the present invention, a WSL of 5 cm or less is sufficient. The inventors have actually confirmed that the smaller the WSL, the smaller the wave. Therefore, a small WSL not only reduces the pressure loss of the passing gas, but also contributes further towards the objective of the present invention of a stable water seal.

Another advantage is that even if a large amount of gas suddenly reaches the device, its structure allows it to pass through smoothly.

The device of the present invention is easy to manufacture due to its structure, and construction costs are low. It can be applied to any gas that is subject to water sealing, but it is especially applicable to oil refineries, petrochemicals, and other plants that produce flammable surplus gas in amounts that fluctuate depending on the process. It best performs its function as a water sealing device for the flow path leading to the device.

Further, since the device of the present invention uniformly forms a fine bubble layer, the gas-liquid contact efficiency is very high, and it also functions as a gas-liquid contact device.

Example Assemble a water sealing device of the type shown in Fig. 1 equipped with a gas dispersion box having the structure shown in Figs. 2 to 4,
Fluctuation data were measured by flowing air at various flow rates. The data includes the range of fluctuations in air pressure at the inlet of the water seal device, the range of fluctuations in air pressure at the outlet, and the range of fluctuations in water seal liquid pressure, which are considered to be able to express the wave situation, and the relationship with each gas flow velocity in the tank. I tried to organize it. (The gas outlet hole diameter is 3mm.
The pitch is 5mm, and the WSL is 100mm. ) For comparison, we have prepared a gas inlet pipe with a number of holes with a diameter of 3 mm in the lower part and sawtooth cuts at the lower end (prior art 1), and a gas inlet pipe with a disk extending in the radial direction at the lower end. Similar air circulation experiments were conducted using a disk with a number of holes of 3 mm in diameter and a short skirt extending downward around the periphery of the disk (prior art 2), both at WSL = 100 mm.

Plots of the data are shown in Figures 7A, B and C. From these graphs, it is clear that according to the present invention, stable water sealing can be performed over a wide range of gas flow rates.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an outline of a typical embodiment of the gas water sealing device of the present invention. 2, 3 and 4 are views showing an example of a gas dispersion box which is a characteristic part of the device of the present invention, in which FIG. 2 is a longitudinal sectional view, and FIG. − direction arrow view,
FIG. 4 is a cross-sectional view in the - direction of FIG. 2.
FIG. 5 is a perspective view showing an embodiment of the apparatus of the present invention having a plurality of gas distribution boxes. FIG. 6 is a diagram showing another embodiment of the apparatus of the present invention having a plurality of gas dispersion boxes, in which A is a vertical sectional view and B is a horizontal sectional view. FIG. 7 is a graph showing the performance of the gas water sealing device of the present invention in comparison with that of the prior art, where A is the range of gas pressure fluctuation at the device inlet, and B is the gas pressure fluctuation range at the device outlet. The width and C are the fluctuation widths of the water ring liquid pressure, both of which are arranged in terms of the gas flow velocity. DESCRIPTION OF SYMBOLS 1...Water seal device, 2...Water seal liquid, 3...Water seal tank, 4...Gas introduction pipe, 5...Gas discharge pipe, 6...
...Gas distribution box, 61...Gas outlet, 7...
Slits.

Claims (1)

[Scope of Claims] 1. A tank containing water sealing liquid is provided with a gas introduction pipe that extends downward from the top of the tank and whose lower end opens below the liquid level, and a gas discharge pipe is provided above the tank. In a water sealing device for gas, a slit is provided in the gas introduction pipe at a position above the lower end and below the liquid level. A device characterized in that it is equipped with a gas dispersion box which is closed at one side and has a large number of gas outlets at the top. 2. The device according to claim 1, wherein the gas distribution box is in the shape of a hollow disc concentric with the gas introduction pipe, and has radial partitions provided inside the box. 3. The device according to claim 1, wherein the gas outlet is provided so that its aperture ratio increases as the distance from the gas introduction pipe increases. 4 The slit is 1 of the pipe cross-sectional area of the gas introduction pipe,
2. The device of claim 1 having a total aperture area of up to twice that. 5. The device according to claim 1, wherein the diameter of the gas outlet is in the range of 3 to 20 mm, preferably 5 to 10 mm. 6. The device according to claim 1, which has a plurality of gas introduction pipes, each of which is equipped with a gas distribution box. 7. The device according to claim 1, which is a gas water seal device as a flashback prevention device for a flare device.