AU2002311399B2 - High voltage power transformer oil spill fire extinguishment and drainage - Google Patents

Description

AUSTRALIA

Patent Act 1990 COMPLETE SPECIFICATIONS STANDARD PATENT No 2002311399 OIL SPILL CONTAINMENT SYSTEM By John Owen Williams The following statement is a full description of this invention including the best method of performing it known to me.

DETAILED DESCRIPTION [001] This invention relates to a system for the collection and secure containment of oil spilt from equipments containing oil when the equipment is installed within a bund arrangement, after it was discovered that the design and/or construction of existing oil spill systems are inconsistent and in most cases totally inadequate, especially so during adverse weather conditions where in some circumstances, some of the systems cease to function due to the formation of ice.

[002] This invention was developed to overcome both the design and/or construction problems with existing and new bund systems, when it was seen that most existing systems contained the spilt oil and rain water in a bund arrangement, where the spilt oil would catch on fire and further destroy the equipment and accessories attached to it, where in some cases attempts were made to overcome this problem by filling the bund with crushed rock to smother the oil, but in most cases the arrangement did not work because too little crushed rock was used because of the limited height of the bund walls, or the height of the equipment plinth was too low within the bund which prevented the bund from being filled with crushed rock.

[003] Another system has been developed where layers of oil absorbent materials are laid on the ground around the transformer plinth for the purpose of temporally containing the spilt oil, where any oil spill incident would require the laborious task of quickly removing and replacing the absorbent materials containing the spilt oil, before the oil had time to percolate into the ground below the containment arrangement.

[004] However another problem exists with the oil absorbent system in that during very cold winters, the absorbent materials which would most likely have retained some water moisture, would freeze solid and therefore would not absorb any spilt oil, thus making the system inoperable.

[005] This invention overcomes these known problems with existing spilt oil containment systems as it uses a different approach where the spilt oil and any rain water that is collected in the bund arrangement is immediately drained to an in-ground containment tank located adjacent to, or remote from the bund, where any excess rain water in the in-ground containment tank is automatically discharged to drain by gravity.

[006] This invention requires that the volume of the bund containment system be calculated to contain the maximum volume of spilt oil, when the bund has been filled with crushed rock to a level of just below the top of the equipment plinth when installed for iceless climatic weather conditions or alternatively, when not filled with crushed rock, except for over the entrance to the hollow rectangle steel section so as to prevent the ingress of flames from burning oil, as required when installed for freezing climatic weather conditions.

[007] When required to be filled with crushed rock, the ideal calculated height for the crushed rock would be such that the top of the maximum oil spill in the bund would be 75 mm below the top surface of the crushed rock, therefore preventing the continued ignition of the spilt oil as the oil surface has been starved of air.

[008] The bund must have a concrete floor or slab so that no oil will escape into the ground, and that the concrete slab slope downwards towards the hollow rectangle steel section drain device mounted through the bottom of the bund wall, or when existing bunds have level concrete slabs, it should be sloped towards the draining device using a mortar mix so as to ensure the rapid draining of both oil and water.

[009] The bund draining device is constructed to form a hollow rectangle galvanized steel section which is mounted through the bottom and adjacent to a corner of the bund wall, with the larger of the two rectangle measurements in the horizontal plane, so as to allow maximum liquid flow through the device for any given height of liquid.

[010] The drainage device is fitted with a galvanized steel pipe stub for connection to pipes which connect to the inlet of the in-ground containment tank, where the size of the pipes used would be 100 mm or 150 mm I.D, the later being more suited for installations with equipments containing larger volumes of oil.

[011] It is necessary to ensure that no burning oil can flow from the bund to the in-ground containment tank by ensuring that there is sufficient level of crushed rock in the bund to starve the oil of air, thus preventing its continued ignition as it enters the drain device.

[012] The dimensions of the in-ground containment tank must take into consideration the depth of the ground water table in the area, as this restricts the depth that can be used, in addition tank dimensions must also take into account the maximum volume of an oil spill, and also for a volume of rain water below the oil as shown in the figures in order to prevents the discharge of oil, and a free space above the in-ground tank drain tee so that the top of the tank will be above ground level.

[013] In order for the system to operate in countries with freezing weather conditions, a pump sump arrangement is installed under or adjacent to the in-ground containment tank which allows all the water in the containment tank to be pumped out when a temperature of below zero degrees centigrade is detected so as to prevent the water from freezing, while still maintaining a much smaller volume of water within the sump which is kept warm by electric element/s, which are also switched on when an ambient temperature of below zero degrees centigrade is detected.

[014] The submersible pump in the pump sump is controlled by a water sensor and float switch which maintains the water level within the sump without allowing oil to be pumped out, the pump could be further controlled by being switched off when a transformer internal explosion is detected.

[015] All non return valves in the pump and connecting pipes are removed so that no water is retained in the pumping circuit, which would freeze in icy conditions and render the pumping system inoperative.

[016] All connecting pipes between the bund drain device and the inlet to the in-ground containment tank, must slope downwards towards the inground containment tank so as to ensure that no water, oil or sediment is allowed to settle in the pipes which could contribute to a blockage in the pipes, especially during freezing weather.

[017] In addition, all pipe/s between the drain tee drain outlet and the outlet at the drain, should also slope downwards towards the drain so as to ensure that no blockages occur.

[0181 The same precautions must also be taken with drain pipes in sump pump installations, so to ensure that no blockages occur in the pump discharge pipe/s.

[019] Stainless steel wire mesh caps and sacks are necessary over the drain outlets and anti syphoning vent, for protection against the ingress of vermin.

[020] The gravity drainage arrangement comprising of pipes and pipe fittings which connect between the in-ground containment tank or the sump tank discharge outlets and drain, where the highest point of the arrangement is terminated above ground to form an anti syphoning vent.

[021] The arrangement and measurements of the gravity drainage system are critical, and must be observed for installations to function correctly.

[022] This invention allows the in-ground containment tank to fill to the overflow point of the drain tee with water without any detrimental effect on the normal operation of the system, as any spilt oil that enters the inground containment tank will float on top of the water and increase the height of the total liquids contents and in doing so, will push water out from the bottom of the tank until the top of the oil is level with the bottom of the drain tee outlet, when the water ceases to overflow.

[023] Further characteristics and advantages of this invention will become apparent from the following detailed description and the accompanied drawings, wherein: Figure 1 Shows a cross section view through the bund arrangement, connecting pipe/s, in-ground containment tank and drain pipes.

Figure 2 Shows a cross section view through the bund arrangement, connecting pipe/s, in-ground containment tank, optional sump tank and drain pipe/s.

Figure 3 Shows a cross section of the hollow rectangle galvanised steel bund draining device inserted through the bottom of the bund wall.

Figure 4 Shows a plan view of suggested locations for the in-ground containment tank where the sump tank is installed under the in-ground containment tank which positions this arrangement clear of any overhead busbars and underground cables.

Figure 5 Shows a plan view of a suggested location for sump tank mounted adjacent to the in-ground containment tank.

[024] With reference to Fig 1, this shows a power transformer 12 mounted on a concrete plinth 10 and mounted within a bund arrangement comprising of; concrete slab 11, bund fire wall 7, normal bund wall 8, anti blockage grill 13, gravel 9 and the hollow rectangle galvanized steel draining device 1, mounted through the bottom of the bund fire wall 7.

[025] With reference to Fig 1, this also shows the in-ground containment tank 2 with connecting pipe/s 6 from the bund draining device 1, the anti syphoning water draining system, comprising of a discharge elbow/bend vertical riser 21, discharge tee 22, anti syphoning vent pipe 18, stainless steel anti vermin vent cap 5, discharge tee 22 outlet to drain pipe/s 3 and the large area anti vermin stainless steel sack 5 over the open discharge.

[026] With reference to Fig 1 which shows the location of the pump sump 4 attached to the bottom of and connecting to the in-ground containment tank 2 with an electric submersible pump 14 mounted in the sump 4, when required by freezing weather conditions, to pump out all the water in the in-ground containment tank 2 which would otherwise freeze, thus making the system inoperable.

[027] With reference to Fig 1 a water detection probe and float switch are installed attached to the submersible pump 14 to pump out all of the water in the in-ground containment tank 2 to drain, while leaving water in the pump sump 4, when an ambient temperature of zero degrees centigrade is detected, in addition electric heating element/s are installed in the pump sump 4 which are energised when an ambient temperature of zero degrees centigrade is detected, so as to prevent the small volume of water in the pump sump from freezing [028] With reference to Fig 1 which shows the maximum volume of oil "0" that is allowable in the in-ground containment tank 2 for the system to operate automatically during ice free weather conditions, while shows the remaining volume of water, after surplus water has been discharged to drain by gravity.

[029] With reference to Fig 1 the maximum allowable volume of oil for the size of in-ground containment tank 2, is calculated so that the maximum oil volume be such that while the top of the oil volume is level with the bottom of the discharge tee 22 outlet, the bottom of the oil will be plus 10 percent of the oil volume from the top of the discharge elbow thus preventing the oil from discharging to drain.

[030] With reference to Fig 1 the automatic draining device comprising of items 20, 21, 22, 3, 18 and 5 will continue to operate correctly even when the in-ground containment tank if full of rain water to the overflow point of the discharge tee 22, as any spilt oil that enters the tank will increase the total liquid height thus allowing water to be discharged until the top of the total liquid level, lowers to the bottom of the drain tee 22 outlet, when water discharge will cease.

[031] With reference to Fig 2 which shows sump tank 19 installed adjacent to the in-ground containment tank 2.

[032] With reference to Fig 2 where an electric submersible pump 14 is installed in the pump sump 4, where a water detection probe and float switch for the control of the pump are installed attached to the pump to pump out all the water out of the in-ground tank when an ambient temperature of below zero degrees centigrade is detected, in addition electric heating element/s are installed in the pump sump 4 which are also energised when an ambient temperature of below zero degrees centigrade is detected, so as to prevent the small volume of water in the pump sump from freezing.

[033] With reference to Fig 2 which shows the maximum allowable volume of oil "0 in the in-ground containment tank 2 for the system to operate automatically during ice free weather conditions, while shows the remaining volume of water after surplus water has been discharged to drain by gravity.

[034] With reference to Fig 2 where the maximum volume of oil in containment tank 2, is calculated so that the maximum oil volume be such that while the top of the oil volume is level with the bottom of the discharge tee 22 outlet, the bottom of the oil level will be plus 15 percent of the oil volume from the bottom of the containment tank 2, thus preventing oil being discharged to drain.

[035] With reference to Fig 3 which shows the construction and installation of the bund draining device 1 with the steel drain pipe connection 16 welded to the outside and underside of the device, where the whole assembly is firmly bolted in place with raw bolt 23 and if required, also by raw bolt 24, where the whole assembly is sealed within the bund wall and concrete slab to prevent water and oil leakage, the entry into the drain device 1 is protected from blockage by crushed rock by the angled expanded metal deflector 13, with the whole assembly comprising of the drain device 1 and deflector 13 being hot dipped galvanized.

[036] With reference to Fig 4 which shows a plan view of an installation with the recommended location for the in-ground containment tank 2 in a typical substation, where the in ground containment tank 2 is located at the end of a row of transformer bunds so as to be clear of overhead busbars and underground cables which is essential when installing the inground containment tank in a substation which is energised and in operation..

[037] With reference to Fig 4 and Fig 5 showing that a bund fire wall 7 is required between the in-ground containment tank and the adjacent transformer plinth.

[038] With reference to Fig 5 which shows the suggested location for the sump tank 19, where the anti syphoning gravity discharge arrangement may be from the sump tank 19 or from the side of the in-ground containment tank 2, this also shows the outline of a square or rectangle reinforced concrete in-ground containment tank 17 when constructed at site, which shows a larger containment area when compared to a circular tank for a given space.

[039] This invention is susceptible of numerous modifications and variations, all of which are within the scope of this same inventive concept.

[040] Where technical features mentioned in the detailed description section are followed by reference numbers, these reference numbers have been included for increasing the intelligibility of the description and claims and accordingly, such reference numbers do not have any limiting effect on the interpretation of each element identified by way of example by such reference number.

Claims (18)

1. A system for the collection and containment of oil spilt from equipment containing oil which are mounted in existing or new wall arrangement, where the bund is filled with crushed rock as required for iceless climatic weather conditions, in addition, the bund wall is fitted with a hollow rectangle steel section inserted through the bottom of the bund wall to drain both the rain water and spilt oil contents of the bund into an in-ground containment tank/s through connecting pipe/s, where surplus rain water is automatically discharged to drain by gravity through an arrangement of pipes and pipe fittings, or/and an electric submersible pump.

2. A system as defined in claim 1 wherein the hollow rectangle steel section is mounted through the bottom of the bund wall so that the larger of the two rectangle measurements is in the horizontal plane.

3. A system as defined in claim 2 wherein the hollow rectangle steel section is provided with a steel pipe stub for connection to drain pipe/s.

4. A system as defined in claim 3 wherein the drain pipe/s then connect to the inlet of the in-ground containment tank.

A system as defined in claim I wherein the outlet of the in-ground containment tank connects to an arrangement of pipes and pipe fittings, to form an automatic anti syphoning gravity discharge system through which, surplus water is discharged to drain, when the electric submersible pump is not required to function due to non freezing climatic weather conditions.

6. A system as defined in claim 5 wherein a system comprising of, a degree elbow or bend with a vertical riser connecting through the drain tee and terminating above ground as an anti syphoning vent, while the drain tee horizontal outlet connects through pipe/s to drain.

7. A system as defined in claims 5 and 6 wherein the measurement from the top of the in-ground containment tank outlet connection to the bottom of the drain tee horizontal outlet, must be greater than the height taken up by the largest possible oil spill from equipment containing the largest volume of oil, plus a safety margin of percent of the oil volume, in order that the oil be contained within the in-ground containment tank, while allowing surplus water to overflow by gravity to drain.

8. A system as defined in claim 1 wherein a pump sump is installed under or adjacent to the in-ground containment tank when required by freezing climatic weather conditions.

9. A system as defined in claim 8 wherein an electric submersible pump and water heating element/s (not shown) are installed in the selected pump sump location.

A system as defined in claim 9 wherein the electric submersible pump is controlled by a sensor (not shown) which detects the presence of water (but not oil) and a float switch (not shown) to detect water level, so as to empty the in-ground containment tank of water, while maintaining a much smaller volume of water within the pump sump which is being kept warm by the heating element/s during freezing climatic weather conditions.

11. A system as defined in claim 9 wherein all non return valves in the electric submersible pump and connecting pipes are removed, so as to prevent water being retained in the pump and pipe/s during freezing climatic weather conditions.

12. A system as defined in claim 1 wherein a pump sump is installed adjacent to the in-ground containment tank and connected by pipe to the outlet in the base of the in-ground containment tank, when required during freezing climatic weather conditions.

13 .A system as defined in claim 12 wherein the outlet of the pump sump connects to an arrangement of pipes and pipe fittings, to form an automatic anti syphoning gravity discharge system which allows surplus water in the system to overflow by gravity to drain, when the electric submersible pump is not required to function because freezing climatic weather conditions are not being detected.

14. A system as defined in claim 13 wherein a 90 degree elbow or bend and a vertical riser connecting through the drain tee and terminating above ground as an anti syphoning vent, while the drain tee horizontal outlet connects through pipe/s to drain.

A system as defined in claim 14 wherein the measurement from the bottom of the in-ground containment tank to the bottom of the drain tee horizontal outlet must be greater than the height taken up by the largest possible oil spill from equipment containing the largest volume of oil, plus a safety margin of 15 percent of the oil volume, in order that all the oil will be contained in the in-ground containment tank while allowing surplus water to overflow by gravity to drain.

16. A system as defined in claims 5, 8 and 12 wherein the gravity discharge systems may be used in conjunction with the electric submersible pump arrangement where the later is use during freezing climatic weather conditions.

17. A system as defined in claim 1 wherein the bund wall arrangement is filled with crushed rock to a height of not less than 75 mm above the maximum possible oil spill, only when the bund wall arrangement is required to function in iceless climatic weather conditions.

18. A system as defined in claim 17 wherein the bund wall arrangement is not filled with crushed rock, except for over the entrance to the hollow rectangle drain device so as to prevent the ingress of burning oil, when the bund arrangement is required to function in freezing climatic weather conditions. John Owen Williams 1 s' July 2002