US3355271A - Gas holder - Google Patents

Description

NOV. 28, 1967 5 SQAN ETAL GAS HOLDER 2 Sheets-Sheet 1 Filed Aug. 17, 1964 FIG. 1.

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Momeys United States Patent 3,355,271 GAS HOLDER Brian S. 80211, Addlestone, Weyhridge, and Roy A. Waller, Carshaltou, England, assignors to Kins Developments Limited Filed Aug. 17, 1964, Ser. No. 389,942 Claims priority, application Great Britain, Aug. 16, 1963, 32,463/ 63 2 Claims. (Cl. 48174) This invention relates to gas holders which include a piston movable within an outer tank and have a seal attached between the piston and the outer tank in the form of a flexible diaphragm which rolls on or off the piston or tank as the piston moves. Such a gas holder will be referred to as of the type specified. The present invention provides improvements in such gas holders to enable these gas holders to be used at pressures higher than those normally used at present. Normal gas holders of the type specified operate at pressures up to 20 ins. water gauge; gas holders according to the invention may be operated at up to about 300 ins. water gauge.

In order that the invention may be more clearly understood, several embodiments thereof will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 shows in part section a gas holder of the type specified;

FIG. 2 shows one form of guide for the piston;

FIG. 3 shows a partial view of a guide rod for the piston;

FIG. 4 shows a section on IV-IV in FIG. 3;

FIG. 5 shows a partial view of a gas holder having a safety device;

FIG. 6 shows an optical system which can be used to check accurate balancing of the piston.

In FIG. 1 is shown a gas holder of the type specified. It comprises a circular vertical wall 10 with a roof 11 mounted on foundations 12. Within the wall is arranged a piston 13 of slightly smaller diameter than the internal diameter of the wall 10. The piston 13 is largely hollow so that its centre of gravity 14 lies close to its lower surface 15. Fixed to both the wall 10 and the piston 13 is a gas-impervious rubberised fabric seal 16 which rolls on and off the piston as it moves up and down. Gas is stored within the holder below the piston 13, which floats on the gas, and the gas passes up between the piston and the wall as far as it is allowed by the loop 17 of the seal.

In one embodiment the gas holder is fabricated from pre-stressed concrete which provides a basic structure which is more economical than steel when using the higher pressures. Concrete also has the advantage of providing automatically a large proportion of the ballasting required for the piston 13, providing a smooth and flush surface on which the seal 16 may roll and providing an intrinsically stiff structure which can withstand local forces from guide wheels without additional stiflening.

In an arrangement seen in FIG. 2 the piston 13 is guided by a number of cushion treaded wheels 18 arranged around the top perimeter 20 of the piston 13 and which run on the inner surface of the outer wall 10.

In another embodiment of the invention shown in FIGS. 3 and 4 the movement of the piston 13 is guided by a rigid rod 22 projecting downwardly from the piston into a well 23 in the gas holder foundation 12. This rod is guided by a number of wheels 24 located in the well. The well 23 may be flooded with water to obviate the necessity to provide a gas seal for the well.

A particularly advantageous self-centering action is obtained by arranging effectively that the piston is always floating in a certain minimum depth of gas. The piston is at any time floating to a depth determined by the height of the top of the seal 17 above the base 15. The choice of this height can ensure that the piston is selfstabilising without any other guidance. In practice it is the height (H in FIG. 1) to which gas pressure acts on the sides of the piston above the level of the centre of gravity which is relevant, and this should be greater than where r is the radius of the piston. For a 96 ft. diameter piston H should at no time be less than 11 ft. The limiting position is when the piston is at the top of its travel.

The perimeter of the seal 17 which is attached to the wall 10 and to the piston 13 should preferably be the same at the wall and at the piston. This is usually achieved by increasing the piston perimeter, for example by corrugations, to equal that of the wall. In one embodiment of this invention the piston is made perfectly cylindrical and the seal is formed by a fabric woven to be particularly elastic in the circumferential direction so that the seal accommodates the dilference in perimeter between the tank and the piston. The seal may also be reinforced by e.g. nylon ropes Woven into the fabric, or placed alongside.

In the event of a failure of the seal 16, it is necessary to ensure that the piston 13 will not fall unrestrained. This is achieved as seen in FIG. 5 by providing a skirt 25 at the top of the piston which normally lies close to the piston and which will be forced outwardly into a substantially horizontal position 25" if the piston starts to descend faster than a certain predetermined rate. In the horizontal position 25 this skirt effectively closes the gap between the piston and the tank wall and the gas is then only able to escape slowly so that the piston descends gently to the ground. The skirt 25 may be made, for example, of mild steel and may be hinged to the piston in any convenient fashion. The bottom of the wall of the piston may have a number of wheels or sleds which are normally clear of the walls of the tank (in certain positions these walls will be covered by the seal of the holder). These wheels or sleds will prevent the piston from becoming grossly out of perpendicular should the seal break. They will thus prevent the jamming of the piston between the tank walls.

It is necessary to ballast the piston to counteract the upward force of the gas pressure and this may be provided by a material such as sand. The sand is advantageously fed to the inside of the piston in fluidized form. In order that the piston may be balanced sufliciently accurately to avoid excessive forces on the guiding system, balancing must be effected with any guide wheels retracted and the piston slightly raised from the ground by gas pressure. In the embodiment shown in FIG. 6 correct balancing can be achieved by adjusting the balance until a light beam 27 reflected by a concave mirror 28 on the piston 13 is focussed at a fixed point 30 under the roof of the gas holder. This method of balancing is accurate to an acceptable degree.

If this light beam is received by a photo-electric cell the balance of the piston can be permanently monitored. In cases where guide wheels (as 18 in FIG. 2) are used, the balance can be monitored by the use of load cells in series with the wheels or by devices measuring the deflections of the wheels themselves. The load cells indicate any variation in the pressure between the guide wheels and the wall 10.

In one embodiment of the gas holder the height of the outer wall 10 is minimised by using a roof 11 which is not attached to the outer wall but which rests on the outer wall by virtue of its own weight when the piston 13 is in the lower part of its travel. As the piston 13 3 travels upwards it reaches the roof and carries it upwards for the remaining part of its travel.

In a further embodiment of the invention the gas holder foundations include energy absorption units (32 in FIG. 1) as disclosed in the specification of British Patent No. 876,341. The provision of these units 32 avoids the necessity for specially prepared foundations and if any mis-match occurs between the bottom of the piston and the top of the foundations due, for example, to shrinkage of the concrete or ground movement, then one or more of the units will distort by yielding plastically when the piston descends so that the distribution of the load remains uniform over the foundation.

What we claim is:

1. A gas holder comprising a tank having an inner wall; a piston having an outer wall and movable up and down in the tank; a flexible diaphragm seal attached between said walls, the seal rolling on one of said walls and off the other as the piston moves and defining at all floating positions of the piston an inverted U-shaped gasconfining pocket; the top of said pocket being at a height above the center of gravity of the piston suflicient to render the piston self-stabilizing, the height of said pocket being always greater than where r is the radius of the piston.

2. The gas holder specified in claim 1 comprising a light source on the inner wall of the tank and a mirror on the piston so that the orientation of the piston can be monitored and corrected by observing the reflection in the mirror of the beam from the light source.

References Cited UNITED STATES PATENTS 619,510 2/1899 Sergeant 48178 1,703,783 2/1929 Schmidt 52-3 1,825,639 9/1931 Shanor 22026 2,778,719 1/1957 Wiggins 48--176 FOREIGN PATENTS 320,162 10/ 1929 Great Britain.

JOSEPH SCOVRONEK, Primary Examiner.

JAMES H. TAYMAN, IR., Examiner.

Claims (1)

1. A GAS HOLDER COMPRISING A TANK HAVING AN INNER WALL; A PISTON HAVING AN OUTER WALL AND MOVABLE UP AND DOWN IN THE TANK; A FLEXIBLE DIAPHRAGM SEAL ATTACHED BETWEEN SAID WALLS, THE SEAL ROLLING ON ONE OF SAID WALLS AND OFF THE OTHER AS THE PISTON MOVES AND DEFINING AT ALL FLOATING POSITIONS OF THE PISTON AN INVERTED U-SHAPED GASCONFINING POCKET; THE TOP OF SAID POCKET BEING AT A HEIGHT ABOVE THE CENTER OF GRAVITY OF THE PISTON SUFFICIENT TO RENDER THE PISTON SELF-STABILIZING, THE HEIGHT OF SAID POCKET BEING ALWAYS GREATER THAN R/PI + 4/PI WHERE R IS THE RADIUS OF THE PISTON.

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