JPS582795Y2 - liquid storage tank - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a liquid storage tank.

In general, pure water used in thermal or nuclear power plants and chemicals used in petrochemical plants must be stored completely isolated from impurities, air and other gases, and water and other liquids. No.

Here, a conventional liquid storage tank will be explained based on FIGS. 1 to 4.

(A) FIG. 1 shows a floating roof elastic seal type tank 1', and this sealing mechanism is basically the same as that normally used in oil tanks and the like.

That is, the structure is such that the surface of the stored liquid 2 is covered with a roof 3' and an elastic sealing material 4 to block air.

Also, due to the inflow and outflow of the stored liquid 2, the floating roof 3'7. When i and W move up and down, the elastic sealing material 4 attached to the floating roof 3' is in close contact with the inner surface of the tank side plate 5, and the floating roof 3'
It moves up and down.

However, the floating roof elastic seal type tank 1' has the following drawbacks.

(i) It is impossible to expect a perfect sealing effect (air-tight sealing effect) between the elastic seal 4 and the inner surface of the tank side plate 5.

That is, when the depth of the stored liquid 2 changes, etc., the seal becomes incomplete and air is likely to enter the stored liquid 2 from this portion.

(ii) For this reason, it seems impossible to use it when high purity is required for the storage liquid.

(B) FIG. 2 shows a diaphragm type tank 1' using an elastic thin film.

In this type of tank, a part of the surface and side surfaces of the stored liquid 2 are covered with a synthetic resin type diaphragm 6 to block air.

Further, the diaphragm 6 is bent at the position of the weight ring 8 due to the buoyancy of the floating loop 7 and the weight of the weight ring 8.

When the depth of the stored liquid 2 changes, the weight ring 8 changes its position by rotating over the diaphragm 6 by means of a rotating collar 9 attached to it.

The water seal 10 has the role of preventing and reducing friction at this time.

However, the diaphragm tank 1' has the following problems.

(i) Since the weight ring 8 rotates at the folded portion of the diaphragm 6, wear may occur due to insufficient water injection of the sealing water 10 or mold temperature, which may cause cracks in the diaphragm 6 and impair the sealing effect.

(ii) Since the film of the diaphragm 6 is thin, there is a risk of air penetration.

(iii) Conversely, if the film thickness of the diaphragm 6 is made thicker, there is a contradiction in that folding back by the weight ring 8 becomes impossible.

(C) FIGS. 3 and 4 show a floating roof bellows type tank 1'.

In this type of tank, a bellows 12 is provided between the floating roof 3' and the pedestal 11, and the stored liquid 2 is placed inside the bellows 12.
A balance sealing liquid 13 is put into the space between the bellows 12 and the tank side plate 5.

The role of this balancing sealing liquid 13 is to balance the pressure between the inside and outside of the bellows 12, keep the bellows 12 in a free state, and ensure its expansion and contraction operation.

When a difference occurs in the liquid pressure inside and outside the bellows 12 due to a change in the liquid depth of the stored liquid 2, this pressure difference is detected by the differential pressure detection valve 14, and the liquid injection valve and liquid injection device 15 operate as a drain valve. and drainage device 1
Since the automatic control mechanism for injecting and discharging the balance sealing liquid 13 by operating the bellows 12 is activated, the hydraulic pressure inside and outside the bellows 12 is always maintained in a balanced state.

However, the floating roof bellows type tank 1' has the following problems.

(i) Since the bellows 12 is used, the tank construction cost increases.

(ii) The hydraulic pressure inside and outside the bellows 12 must be balanced, and an automatic pressure control mechanism is required for this purpose, which increases tank construction costs and makes maintenance more complicated when the tank is in use.

The purpose of the present invention is to provide a solution to the various problems mentioned above.

Next, an example of implementing the present invention will be described with reference to FIGS. 5 to 8.

(I) Tank Structure In the tank 1 of the present invention, an airtight sheet 17 is stretched on the inside of the tank side plate 5 between the floating roof 3 and the pedestal 11, and the stored liquid 2 is stored inside the airtight sheet 17. Ru.

The gap between the airtight sheet 17 and the tank side plate 5 is filled with a sealing liquid 18, and the liquid depth (hydraulic pressure) is equal to or smaller than that of the stored liquid 2.
The liquid depth (hydraulic pressure) is always maintained to some extent higher than the liquid depth (hydraulic pressure) of the airtight sheet 17, and provides pressure that constantly pushes the airtight sheet 17 toward the center of the tank 1.

The central concave portion of the floating roof 3 is formed as a reservoir 19 of the sealing liquid 18, and the sealing fluid 18 in the reservoir 19 flows through the floating roof 3.
The sealing liquid 18 outside the liquid reservoir 19 is communicated with the sealing liquid 18 through a liquid guide pipe 20 provided in the liquid reservoir 19, and can freely flow in and out.

The airtight sheet 17 has a certain appropriate interval ((II)(
(see i)), the slidable shaping ring 21 is attached to the mounting band 2.
2, it is mounted approximately horizontally.

When the air tight sheet 17 is contracted together with the above-mentioned pressure acting on the air tight sheet 17, this shaping ring 21
The airtight sheet 17 is pressed and bent toward the center of the tank to form a well-shaped sealed liquid storage bag.

Further, this hollow shaping ring 21 uses its hollow space to adjust its buoyancy.

This buoyancy is adjusted so that the total converted specific gravity, taking into account the shaping ring 21 and the airtight sheet 17 in the area controlled by the shaping ring 21, is slightly heavier (or lighter) than the specific gravity of the stored liquid 2. The most convenient ((II
) (see (ii)).

Note that there is a guide 23 on the outside of the floating roof 3 and the shaping ring 21.
．． 24 are attached to each.

In particular, in the guide 24, the airtight sheet 17 is connected to the tank side plate 5.
This is to prevent direct contact with and damage to the product.

Here, in detail how to install the guide 24, the head of the bolt 25 is locked inside the shaping ring 21, and the shaping ring 2
A bolt 25 protrudes from the side plate 5 side of the shaping ring 21, and also passes through the airtight sheet 17 on the side plate 5 side of the shaping ring 21, and a nut 26 in the guide 24 is screwed onto the tip of the bolt 25. Ru.

(II) Tank Operating Principle In a liquid storage tank similar to the tank of the present invention,
As the stored liquid comes in and out, there is an excess or shortage of sealing liquid.

That is, when the depth of the stored liquid changes, the difference in liquid pressure between the inside and outside of the partition wall (in the case of the tank of the present invention, the airtight sheet) becomes significantly large, inhibiting the expansion and contraction of the partition wall and causing the tank to lose its function.

Therefore, in liquid storage tanks similar to the tank of the present invention, automatic control mechanisms (pressure difference detection valves between the storage liquid side and sealing liquid side, automatic injection/draining of sealing liquid, A liquid device, etc.) must be installed to balance the pressure inside and outside the bulkhead and protect it.

However, in the tank of this invention, the pressure difference between the inside and outside of the airtight sheet is kept constant using the unique method described below.
Even when the stored liquid 2 flows in and out, there is no need for the sealing liquid to flow out or flow out of the tank 1.

(i) Pressure difference holding mechanism No. 1 (Seal liquid storage bag and shaping ring attachment interval) FIG. 8 shows a state in which the stored liquid 2 has decreased and the lower part of the airtight sheet 17 has protruded inward.

Shaping rings 21 a , 21 b , 21 at the bottom of the figure
The airtight sheet 17 stretched between each of the sealing liquid storage bags 27a and 2 completely overhangs the inside of the tank 1.
7b is formed.

The airtight sheet 17 stretched between the shaping rings 21e and 21f is completely stretched.

Further, the liquid storage bags 27C and 27d in the intermediate portion are in the process of extending the airtight sheet 17 to the inside of the tank 1.

S1 to S5 indicate the distance between the centers of each shaping ring.

Here, the total volume of the sealing liquid 18 (8th
It is theoretically possible to make equal the total volume of the sealing liquid 18 present in the section S5 when the airtight sheet 17 is fully expanded (the volume indicated by the diagonal lines in FIG. 8). and experimentally possible.

That is, in the tank 1 of the present invention, the gap between the side plate 5 and the shaping ring 21, the cross-sectional diameter of the shaping ring 21, the hydraulic pressure difference between the inside and outside of the air tight sheet 17, and the air tight sheet 17
The rings 21 are shaped and the mounting intervals of the rings 21 are determined so that the above-mentioned volumes are equal, taking into account elastic elongation and the like.

In addition, due to the above-described mechanism, when the liquid depth of the stored liquid 2 changes, the liquid depth of the sealing liquid changes accordingly, and the difference between the two liquid methods (liquid pressure) does not change significantly.

By the way, shaping ring 21. The floating roof 3 and the like slide as the amount of stored liquid 2 increases or decreases, but the portion of the airtight sheet 17 protruding into the tank 1 increases or decreases as the amount of stored liquid 2 increases or decreases.

In addition, the two-dot chain line in FIG. 5 shows a state in which the stored liquid 2 has decreased to about half of the tank 1.

(ii) Pressure difference retention mechanism part 2 (buoyancy of seal liquid reservoir and shaping ring) As described in (i) above, the formation of the seal liquid reservoir bag 27 causes a large change in the pressure difference between the inside and outside of the airtight sheet 17. is prevented.

However, in the process of the airtight sheet 17 extending from the stretched state to the inside of the tank 1, the liquid storage bags 27 C, 27
d is formed.

The volume of the liquid storage bags 27C and 27d is the same as that of the liquid storage bags 27a and 27b.
It is larger than the volume of , and there is clearly a difference between the same volumes.

That is, when the liquid depth of the stored liquid 2 increases or decreases, an excess or deficiency occurs in the sealing liquid 18 corresponding to the above-mentioned volume difference.
The difference in liquid depth (difference in liquid pressure) between the inside and outside of the airtight sheet 17 repeatedly fluctuates within a certain range.

However, the floating roof 3 of the tank of the present invention is provided with a sealing liquid reservoir 19, and the sealing liquid 18 inside the tank is supplied to the liquid conduit 20.
It communicates with the sealing liquid 18 on the outside of the airtight sheet 17.

That is, the above-mentioned excess or deficiency of the sealing liquid 18 is caused by this liquid storage tank 1.
However, since the diameter of the liquid reservoir 19 is larger than the above-mentioned excess or deficiency of the sealing liquid, the depth of the sealing liquid 18 in the liquid reservoir 19 hardly changes. do not.

Therefore, no matter how much the liquid depth of the stored liquid 2 changes, the liquid depth of the sealing liquid changes with it, and the relative difference between the two liquid methods, that is, the pressure difference between the inside and outside of the airtight sheet 17, remains virtually constant.

By the way, the buoyancy of the shaping ring 21 is
It is most convenient to adjust so that the total converted specific gravity, taking into account the airtight sheet 17 and the like in the range dominated by the shaping ring 21, is slightly heavier (or lighter) than the specific gravity of the stored liquid 2.

This means that when the specific gravity of the two is made equal, when the depth of the stored liquid 2 is between the maximum and minimum depths, the airtight sheets 17 stretched between the shaping rings 21 are all 27 d (Fig. 8). If the liquid storage bag 27 is formed as shown in FIG. 1, the problem arises that the amount of excess or deficiency of the sealing liquid 18 described above becomes large.

Furthermore, if there is an unnecessarily large difference in the specific gravity between the two, there will be a problem in that the tension of the airtight sheet 17 (see section S5 in FIG. 8) in the fully expanded state becomes excessive.

The above is the reason for the description in (I).

Note that if the buoyancy of the shaping ring 21 is adjusted so that the total converted specific gravity considering the shaping ring 21 and the air tight sheet 17 etc. in the vicinity becomes a value close to the specific gravity of the stored liquid 2, the tension acting on the air tight sheet 17 can be reduced. A small comb has the advantage of helping to prolong its lifespan.

Further, the film thickness of the air-tight sheet 17 can be freely increased for reasons such as ensuring the sealing effect of the air-tight sheet 17.

Even if the film thickness is increased, the operation of the airtight sheet 17 will not be hindered due to its structure.

Since the present invention is constructed as described above, it can achieve the following excellent effects.

(1) The stored liquid is isolated from other liquids or gases by the floating roof, airtight sheet, tank side plate, and tank bottom plate, but a complete sealing effect can be expected from any of these members and any joints between them. can.

Note that since there is liquid on both sides of the airtight sheet, there is no risk of gas or liquid penetrating this airtight sheet.

(2) Since the airtight sheet does not come into direct contact with other members, there is no risk of cracks occurring in the airtight sheet due to wear or the like when the tank is used.

(3) Even if the depth of the stored liquid changes, the sealing liquid can be injected and drained from outside the tank, and the unique method of this invention allows the sealing liquid to be kept inside the tank without using any special equipment. automatically changes the liquid depth to maintain a constant liquid pressure difference between the inside and outside of the airtight sheet.

In other words, there is no need for special automatic control equipment to adjust the depth (hydraulic pressure) of the sealing liquid, which reduces tank construction costs and facilitates maintenance when the tank is in use. It is something.

(4) The pressure difference between the inside and outside of the air-tight sheet may be small as long as it is sufficient to bend the air-tight sheet inward.

(5) The tolerance for the pressure difference between the inside and outside of the airtight sheet, that is, the relative depth of the sealing liquid, is relatively large.

This lengthens the replenishment period for the sealing liquid and facilitates maintenance when the tank is in use.

(6) Compared to a tank using a bellows similar to the present invention, the tank construction cost is lower because an airtight sheet is used instead of the bellows.

In addition, all types of liquids are used when storing liquids that must be completely isolated from air and other gases, or water and other liquids, such as pure water used in power plants and chemicals used in petrochemical factories. can do.

[Brief explanation of the drawing]

Figures 1 to 4 show conventional examples. Figure 1 is a schematic longitudinal sectional view of a floating roof elastic seal type tank of the first conventional example, and Figure 2 is a schematic longitudinal sectional view of a diaphragm type tank of the second conventional example. 3 is a schematic longitudinal sectional view of a third conventional floating roof bellows type tank, and FIG. 4 is a sectional view taken along line A--A in FIG. 3. In addition, FIGS. 5 to 8 show an example of the implementation of the present invention, and FIG. 5 is a schematic vertical sectional view of the tank, FIG. FIG. 7 is an enlarged sectional view of the part where the shaping ring is attached, and FIG. 8 is a schematic partial vertical sectional view showing the state of the sheet when the stored liquid is reduced. Hereinafter, the symbols in the figures indicate the following parts. 1.1': Tank, 2: Storage liquid, 3.3': Floating roof,
4: Elastic sealing material, 5: Tank side plate, 6: Diaphragm, 7: Floating loop, 8: Weight loop, 9: Rotating collar,
10: water seal, 11: cradle, 12: bellows, 13: balance sealing liquid, 14: differential pressure detection valve, 15: liquid injection valve and liquid injection device, 16: drain valve and liquid drainage device, 17: sheet, 18
: Seal liquid, 19: Liquid reservoir, 20: Liquid guide pipe, 21.21
a to 21 f: Shaping ring, 22: Ring mounting band, 23 Ni guide, 24 Ni guide, 25: Pol l-, 2
6: Nut, 27, 27a-27d: Liquid storage bag, S1-S
5: Distance between shaping rings.

Claims (1)

[Scope of utility model registration request] 1. A sheet 17 is stretched on the inside of the side plate 5 between the floating roof 3 and the pedestal 11 provided in the storage tank 1, and shaping rings 21 having an appropriate buoyancy are placed approximately horizontally on the inside of the sheet 17 at appropriate intervals. The storage liquid 2 is stored inside the sheet 17, and the gap between the sheet 17 and the side plate 5 is filled with the sealing liquid 18, and the liquid pressure on the outside of the sheet 17 is transferred to the sheet 17.
A liquid storage tank whose pressure is maintained slightly higher than the internal liquid pressure. 2. The system according to claim 1 of the utility model registration claim, in which the sealing liquid 18 in the gap between the sheet 17 and the side plate 5 can freely flow into and out of the sealing liquid reservoir 19 provided on or near the floating roof 3. body storage tank. 3. The sealing liquid 18 in the gap between the sheet 17 and the side plate 5 is applied to the shaping ring 21.2 when the sheet 17 is stretched and extended.
2. A liquid storage tank according to claim 1 or 2, in which the respective volumes of the tanks are approximately equal.