JPS6020267B2 - Floating roof seal mechanism - Google Patents

Description

[Detailed description of the invention] This invention relates to floating roof seal arrangements.

Floating roof type liquid storage tanks are used to store evaporated liquid, and in order to minimize the amount of evaporation, various improvements have been made to the sealing mechanism of the floating roof.

However, when it comes to large-mouth tanks made of thin plates, even if the floating roof sealing mechanism is made highly flexible and airtightness is achieved between the tank side wall and the surrounding wall of the floating roof, there is no loss due to the release of vapor from the stored liquid. I have not yet succeeded in doing so.

Nowadays, as the problem of pollution has become more serious, when the stored liquid is petroleum, even the emission of hydrocarbon vapor, which is technically extremely small from the sealing mechanism of the floating roof, can become a source of air pollution. It has come to be monitored as one of the

As a result of actually measuring the amount of emissions in floating roof oil storage tanks, we found the following facts. That is, the amount of discharge differs depending on the type of seal mechanism, for example, mechanical shoe seal type (see Figure 1) or tube seal type (see Figure 2), and also depends on the size of the seal gap actually created on the seal surface. It also varies depending on the wind speed and the type of oil being stored.

ii The actual amount of emissions is determined by the American Petroleum Institute's booklet "
Approximately 50% of the estimated emission amount listed in API Builtin 2577 (Published in 1962 2)
~60%.誼 In mechanical show seals, there is no correlation between the amount of emission and the seal gap.

In other words, even if the seal gap reaches 5 cm and is visible to the naked eye, the amount of emission will be at the normal seal gap of 3 to 5 cm, or at a place where there is no gap in engineering. There was almost no difference in the amount of emissions. iv Poorly maintained seal mechanisms emit a large amount of emissions.

V Even if the sealing mechanism of the mechanical shoe seal type has a considerable seal gap, the amount of emission should be comparable to that of the tube seal type with no gap or with a small gap.

W Mechanical shoe seal type seal mechanism works more effectively to prevent evaporation than tube seal type.

That's what I was saying.

Among the above, the most noteworthy one is v. In other words, prior to actual measurements, it seems that the tube seal type seal mechanism is superior to the mechanical shoe seal type in terms of flexibility, so it adapts well to the deformation of the tank side wall and has a tight seal. Although it was thought that the sealing effect would be excellent as it would come into contact with the inner wall of the side plate, actual measurements showed the opposite. Also, surprisingly, as shown in Figure 3,
It was a fact that as the wind speed increased, the amount of emissions in the tube seal type became larger than that in the mechanical shoe seal type.

In Figure 3, the liquid stored in the tank was gasoline. However, in our country, which is prone to earthquakes, floating roofs with mechanical shoe seals collide with the inner walls of the side panels during earthquakes.
Due to the soot that can ignite, it has become rare to produce in recent years, and has been replaced by the flexible chew seal type.

However, from the point of view of the amount of emissions, the use of a floating roof sealing mechanism of the chew seal type requires consideration.

Now, in light of the above measurement results, we have considered the superiority of the mechanical show-seal type in terms of emission prevention compared to the tube seal type, and found that the one shown in Figure 1 is a typical one. It is a mechanical shoe seal type seal mechanism, where A is the floating roof, the mouth is the tank side plate, C is the seal fabric, the second is the mechanical shoe, the wood is the Pandagraph hanger, the bottom is the counterweight, and the bottom is the oil surface. However, in the mechanical show seal type,
Because the shoe is sufficiently submerged in oil, even if the floating roof moves due to wind etc., creating a seal gap, evaporation occurs from there, and hydrocarbon emission occurs. Hyde in space A is surrounded by Shuni, Sealfabritsuha, and Crabchi on the floating roof side.

Carbon paper does not participate in the emission, and the long gap between the tank side plate opening and the shoe provides resistance to the emission, so evaporation does not progress much. When the roof moves, creating a seal gap, which induces evaporation and generates hydrocarbon emissions, in the tube seal type shown in Figure 2, the tank side plate opening and tube seal rim The hydrocarbon vapor in space B, which is surrounded by the floating roof sidewall and the side wall of the floating roof, immediately participates in the emission, and the seal gap made up of the tank side slope mouth and the tube seal is short, so it does not react to the emission. It was determined that the amount of evaporation progressed as the wind speed increased because it did not show much resistance. In view of the above facts, this invention does not use a mechanical shoe, but applies the effective structure of the mechanical shoe seal type against emissions to a soft tube seal type, which is safe against ignition and has extremely low emissions. , its purpose is to provide a floating roof sealing mechanism. The structure will be explained based on an embodiment shown in FIG. 4.A ring-shaped elastic aggregate, for example, a European synthetic resin foam such as urethane foam, is used as a core material 3 on the outer peripheral side wall 2 of a floating roof 1. , the surface of the core material 3 is covered with an oil-resistant coating 4 and a ring-shaped body 5 is attached, and the upper surface 6 of the ring-shaped body 5 is provided with a chevron-shaped upper end of a wall curtain 7 made of the same material as the coating 4 or a different material. The wall curtain 7 is not solidified by the ring-shaped body 5 at any point other than the upper end, and the lower end is between the outer periphery of the ring-shaped body 5 and the tank inner wall 8. Let it hang down through the
A hollow hanging part 11 is formed below and fixed below the outer peripheral side wall 2 of the floating roof 1, and the hollow hanging part 11 is extended to the lower part 1 of the narrow surface 9.

If the stored oil is of car quality, the buoyancy will increase as the wall curtain is submerged, so in order to overcome the buoyancy, the weight of the wall curtain is reduced and liquid is sealed inside the wall curtain. The desired shape can be maintained against this buoyant force.

Incidentally, the length of the above-mentioned 1 changes as the floating roof 1 moves up and down, and when the floating roof 1 descends, the wall curtain 7 tends to remain due to the frictional force acting between it and the tank inner wall 8, and the ring-shaped body 5 remains on the wall. Since it easily slides on the inner surface of the curtain 7, most types of drooping parts tend to be shortened quickly. In addition, if the hanging portion 11 has a closed structure, the wall curtain 7
The base of the storage liquid is placed in the space C formed between the upper part of the film and the film 4.
The wall curtain 7 tends to be raised due to the par pressure, but when the hanging part 11 becomes a closed structure,
Paper pressure generated from the stored liquid does not act on the space C. Since this embodiment has the above-mentioned configuration, the floating roof 1 moves due to the wind and the wall curtain 7
Even if a seal gap is created between the inner wall 8 of the wall curtain 7 and the inner wall 8 of the tank, and evaporation is induced from there, and the vapor of the built-in liquid is emitted, the inner side of the lower hanging part 11 of the wall curtain 7, The steam in the space D surrounded by the outer periphery 10 of the floating roof does not participate in the emission, and the upper end of the wall curtain is bent into a chevron shape so that it is fixed only on the upper surface of the ring-shaped body, and the rest is in the shape of an IJ ring. Even if the floating roof 1 moves due to wind pressure and separates from the tank inner wall 8, it is difficult for the wall curtain to separate from the tank inner wall 8 due to the upper chevron-shaped bend, and therefore the ring There is no problem even if the inside of the shaped body 5 is an elastic body and the expansion action is slow.
However, since the length between the wall curtain 7 and the tank inner wall 8 is long, there is resistance to emissions, so evaporation does not proceed much, and the ring-shaped body has an elastic aggregate as its core material and is covered with an oil-resistant film 4. Even if it collides with the tank inner wall 8, there is no possibility of ignition.The hanging part 11 is double and hollow, so it is heavy and the hanging part 11 is well formed. There is also no tendency for paper pressure to act on C to raise the wall curtain 7 particularly.

This invention has the above-mentioned structural action, and provides a floating roof tank that can sufficiently prevent emissions and can safely store stored liquids that generate flammable vapors such as hydrocarbon vapor. A floating roof sealing mechanism can be provided.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a typical example of a mechanical shoe seal mechanism, Fig. 2 is an explanatory diagram of a typical example of a tube seal mechanism, and Fig. 3 is an explanatory diagram of a typical example of a tube seal type and a mechanical shoe type seal mechanism. Fig. 4 shows a vertical cross-sectional front view of a part of an embodiment of the floating roof sealing mechanism according to the present invention, in which 1 is the floating roof, 2 is the outer peripheral side wall, 3 is the core material, and 4 is the oil-resistant part. 5 is a ring-shaped body, 6 is an upper surface, and 7 is a wall curtain. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1 A ring-shaped body 5 is attached to the outer peripheral side surface 2 of the floating roof 1, and the ring-shaped elastic cushion body is used as a core material 3, and the surface of the core material 3 is covered with an oil-resistant film 4. The upper end of a wall curtain 7 made of the same or different material as the coating 4 is fixed to the upper surface 6 by being curved in a mountain shape, and the wall curtain 7 is not fixed to the ring-shaped body 5 at any point other than the upper end. The lower end of the ring-shaped body 5 is left free and hangs down between the outer periphery of the ring-shaped body 5 and the tank inner wall 8, and a hollow hanging part 1 is formed below.
1 and fixed to the lower part of the outer peripheral side wall of the floating roof 1,
A floating roof sealing mechanism characterized in that the lower part of the hanging part 11 is immersed in the storage liquid for a long time.