JPS5828099A - Structure of tank level gauge maintenance nozzle - Google Patents

Abstract

PURPOSE:To form a complete seal against volatile gas stored in an upper part of a tank by press-supplying inert gas into scattered microscopic gaps formed despite an attempt to bring a seal plate and a hatch cover plate into a metal- to-metal-touching state. CONSTITUTION:N2 gas is press-supplied from an inert gas supplying pipe 24 at the flow rate of about 200cc/sec and at the pressure of 2,000mm.H2O that is higher than that of volatile gas, 300mm. to 1,500mm. H2O, stored in an upper part of a tank 1, and it is branched after passing an inert gas supplying pipe 23 and press- supplied into a recessed groove 21. Thus through scattered microscopic gaps between a seal plate 3 and a hatch cover 11, the N2 gas is press-supplied to an upper part of the tank 1 and to the inside of a maintenance nozzle 2. Accordingly, owing to the N2 gas pressure as well as a metal-to-metal-touching state, the volatile gas stored in the upper space of the tank does not leak into the maintenance nozzle 2, being kept in a complete seal.

Description

DETAILED DESCRIPTION OF THE INVENTION The disclosed technology belongs to the structure technology of a nozzle for repairing a float-type liquid level gauge having a membrane cut, such as an LPG storage tank.

Accordingly, the present invention is such that a repair nozzle fixed to the roof of the LPG storage tank is fixed to the bottom of the tank via a guide nozzle, and a lift lid is raised at the bottom of the tank using a pulling wire, and a ring-shaped nozzle fixed to the lower part of the nozzle is fixed. A maintenance nozzle that is placed in close contact with the seal plate 1, and after replacing the gas inside the nozzle with air using an inert gas through a purge nozzle, the nozzle is opened, and the float and tape that have been lifted and placed on the lifting lid are repaired. This relates to the structure, and in particular, a tank level gauge in which a concave groove is provided around the lower surface of the seal plate so that inert gas is fed from an inert gas pipe through which a nozzle penetrates the metal contact area with the lifting lid. This relates to a maintenance nozzle structure.

As is well known, when operating a tank for storing LPG, etc., it is necessary to measure the amount of stored liquid when receiving and discharging the liquid, and there are various measuring devices, but in general, a float tape type is used. Liquid level measuring types are widely used.
A measurement tape is connected to a liquid level following float and then stretched, and the tape is suspended and lowered from a maintenance nozzle installed on the tank roof for measurement.

However, if the tape unexpectedly breaks during a predetermined period of open inspection due to fatigue, excessive horizontal load due to sloshing, etc., the maintenance nozzle is generally opened unconditionally to repair it due to the gas above the liquid level in the tank. There is a problem where you can't pull up the float and replace the tape.

To deal with this, various techniques have been devised, developed and improved to repair the nozzle by sealing it at the bottom while the tank is in operation; for example, there is a means as shown in FIG.

That is, the tank roof part 1 (this liquid level gauge maintenance nozzle 2
A ring-shaped seal plate 3 is fixed on the inner surface of the ring-shaped seal plate 3, and a guide wire 6.6 is fixedly stretched between the seal plate 3 and the anchor bracket 5 provided on the tank bottom 4. A float 7, which is a plane meter, is floated to follow the liquid level 10 by a tape 9 hanging from an instrument nozzle 8, and is stretched along the guide wire 6.6 to the lifting lid 11, which is settled and seated on the anchor bracket 5. Can it be slid onto the lifting wire 13.13 guided by the guide nozzle 12.12? This is locked.

If the tape 9 unexpectedly breaks due to fatigue, sloshing, etc., the elevating lid 11 is raised via the lifting wire 13, 13, and its upper surface is brought into contact with the seal plate 3 for a tight seal. At the same time, the float 7 is housed in the nozzle 2, and the purge nozzle 14 is opened to expel the volatile gas stored in the upper part and replace it with air.
The user opens the tape and performs certain tasks such as changing the tape.

However, the surface contact between the elevating lid 11 and the seal plate 3 is a so-called metal touch between the two metal surfaces, or at most a surface contact seal between metal surfaces coated with Teflon. , we cannot fully guarantee that
During repair, there may be a leak of, for example, 200 cc/see, and there is a drawback that there is a risk of explosion due to static electricity sparks caused by the operation of equipment jigs during repair.

To cope with this problem, even if an attempt is made to line the abutting surface with a soft sealing material having appropriate elasticity, the softness cannot be maintained in low-temperature liquid tanks such as LNG tanks, making it difficult to use in reality.

This problem also occurs when a lid is provided at the lower end of the nozzle via a hinge and the lid is opened and closed using a wire for sealing.

The purpose of this invention is to solve the problem of sealing a nozzle equipped with a liquid level gauge of a tank based on the above-mentioned prior art, by providing a concave groove around the sealing surface of a seal plate with which an elevating lid comes into contact, and making the concave groove inert. It is an object of the present invention to provide an excellent tank level gauge maintenance nozzle structure that is capable of gas sealing and purging the volatile gas by pumping gas.

The structure of the present invention in accordance with the above-mentioned objects includes tank liquid level gauge inspection,
When performing repairs, pull the lifting wire through the guide nozzle of the maintenance nozzle on the tank roof, raise the lifting lid along the guide wire stretched between the anchor bracket on the bottom of the tank, and remove the seal at the bottom of the maintenance nozzle. The seal plate is brought into contact with the lower surface of the plate to achieve a primary seal, and then inert gas is force-fed from the inert gas supply pipe inserted through the maintenance nozzle into the groove drilled in the lower surface of the seal plate, and the seal plate and the lifting lid are sealed. The volatile gas in the upper part of the tank is prevented from leaking into the maintenance nozzle by being squeezed out through the irregular micro gaps between The gist of this is to remove the lid and repair and inspect the float and tape.

Next, one embodiment of the present invention will be described below based on the drawings from FIG. 2 onwards. Note that the same aspects as in FIG. 1 will be explained using the same reference numerals.

In the embodiment, a maintenance nozzle 2' is fixed on the roof of the LNG storage tank 1, and a ring-shaped seal plate 3 is welded 16.1 at the bottom of the nozzle 2' as shown in FIG.
6, and its inner upper placket l-17
, 17, a guide wire 6.6 is stretched through the insertion hole 18 of the seal plate 3 between the anchor bracket 5 fixed to the tank bottom surface 4.

Reference numeral 7 denotes a float, which connects a tape 9 passing through an instrument nozzle 8 provided on the lid 15 of the maintenance nozzle 2' to store liquid, float above the NG 10, and follow the liquid level.

Reference numeral 11 denotes an elevating lid, which is smaller than the inner diameter of the maintenance nozzle 2' and larger than the inner diameter of the sealing plate 3, and is lifted by the anchor bracket 5 due to its own weight while the tank 1 is in operation.
The guide wire 6 is loosely inserted into the slide hole 19, and the guide nozzle 1 of the maintenance nozzle 2' is
2, 12, 12 to the lower end of a lifting wire 13.13, 13, which is connected to a hoisting device (not shown).

A ring-shaped groove 21 is bored all around the lower surface 20 of the seal plate 3, and an inert gas supply pipe 23 is connected to the gas hole 22 communicating with the groove 21. The maintenance nozzle 2' is connected to an inert gas supply pipe 241 which is provided through the maintenance nozzle 2' and connected to an inert gas source (not shown), for example, an N2 gas generator.

Note that the inert gas supply pipe 23 is connected to the maintenance nozzle 2.
6 and 4, it is shown as a line.

Further, the clearance between the abutting surfaces of the seal plate 3 and the lifting lid 11 shown in FIG. 5 is for illustration purposes only.

In the above configuration, when the tank 1 stores LNGlQ and is in a receiving and discharging operation, the float 7 moves up and down following the liquid level ζ, and the tape 9 intrudes through the instrument nozzle 8. , an increase or decrease in the amount of stored liquid is measured by a measuring device (not shown).

During this period, if the tape 9 unexpectedly breaks during the regular inspection period due to fatigue, sloshing, etc., the pulling wire 13,
13.13 is pulled by the hoisting device, the lifting lid 11 rises along the guide wire 6.6, enters the maintenance nozzle 2' from the state shown by the dotted line to the state shown by the solid line, and its upper surface touches the lower surface of the seal plate 3. They are brought into contact and finally pulled together tightly.

However, from a microscopic perspective, the metal touch state of both is irregular and has various fine gaps scattered about.

Therefore, it is not completely sealed.

Therefore, from the inert gas supply pipe 24, for example, N2 gas is supplied at a flow rate of about 200 cc/sec to a volatile gas pressure of 300 mm H20 to 1500 mm in the upper part of the tank 1.
When the N2 gas is pumped at 2000 mm H2O, which is higher than H2O, and is branched into the groove 21 from the inert gas feed pipe 23, the N2 gas flows through the seal plate 3 and the lifting lid 11, as shown in FIG.
It is forced out into the upper part of the tank 1 and into the maintenance nozzle 2' through the scattered fine gaps between them.

Therefore, the volatile gas stored in the upper space of the tank due to the N2 gas pressure and the metal touch does not leak into the maintenance nozzle 2' and is completely sealed.

In this way, the volatile gas in the maintenance nozzle 2' is expelled from the purge nozzle 14, and the maintenance nozzle 2' is filled with N2 gas. Then, the lid 15 is opened as appropriate, and a worker wearing an oxygen mask removes the maintenance nozzle 2' filled with N2 gas. Enter inside and repair the tape 9 on the float 7, and when finished, close the lid 15 and continue supplying N2 gas to expel air from the maintenance nozzle 2' through the purge nozzle 14, completely filling it with N2 gas. When this is done, the purge nozzle 14 is closed and the elevating lid 11 is lowered to finish the work.

It goes without saying that the embodiments of the present invention are not limited to the above-mentioned embodiments; for example, it is possible to provide more than one groove in addition to one, and it is also possible to provide an interconnected labyrinth-like arrangement. It is also possible to do so.

Various embodiments can be adopted, such as the inert gas supply pipe being directly connected to the groove from the side wall of the maintenance nozzle.

As described above, according to the present invention, in a tank level gauge maintenance nozzle for an LNG storage tank or the like, the seal plate and the lifting lid have an irregular shape in which they are formed in a metal-touch state when the lifting lid is raised and in close contact with each other. By pumping inert gas into the small scattered gaps to the tank side and nozzle side, a gas seal is created in addition to the metal touch seal, so a complete seal is created against volatile gases stored in the upper part of the tank. Not only that, but also the pressurized seal inert gas has an excellent effect in that it can purge the volatile gas in the meretenance nozzle when the lifting lid is sealed.

The above-mentioned gas seal and gas purge can be achieved by simply connecting the inert gas supply pipe to the groove provided on the bottom surface of the seal plate. The design of the inert gas piping can be changed and the connection can be made, so the structure is not particularly complicated, manufacturing is easy, and there are almost no failures.

Since the concave grooves on the seal plate forcefully feed inert gas into minute gaps, the amount of gas to be fed is small, and therefore the inert gas feed can be connected even when repairing and inspecting floats and tapes. Therefore, there is an effect that repair inspection can be carried out safely.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram of a conventional maintenance nozzle, FIG. 2 and the following diagrams are explanatory diagrams of one embodiment of the present invention, FIG. Figure, Figure 4 is Figure 4 fV-TV
5 is an enlarged explanatory view of section A in FIG. 4. 1...tank, 2'...(maintenance) nozzle,
14... Gas purge nozzle, 7... Float, 11
... Lifting lid, 3... Seal plate, 13.
... Pulling wire, 12 ... Guide nozzle, 4 ...
Bottom of tank, 6... Guide wire, 21...
Concave groove, 23.24...Inert gas feed pipe applicant
Kawasaki Heavy Industries, Ltd. 313 Figure 4

Claims (1)

[Claims] A nozzle hanging down on the tank roof has a gas purge nozzle, and a ring-shaped seal plate for the float-mounted lifting lid is fixed in a circular manner on the lower inner surface of the nozzle, and a guide nozzle for a pulling wire stretched and extended from the lifting lid. In the liquid level gauge maintenance nozzle structure in which a guide wire is stretched between the tank bottom surface and the ring-shaped seal plate 1,
- A tank level gauge maintenance nozzle characterized in that a groove is bored all around the lower surface, and an inert gas supply pipe that penetrates the nozzle is connected to the groove. structure.