WO2012107938A2

WO2012107938A2 - A method and system for ground pollution free and minimum oil burning oil storage tank farm

Info

Publication number: WO2012107938A2
Application number: PCT/IN2012/000090
Authority: WO
Inventors: Sridebi BASU; Bhagu Ram CHAHAR
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-02-10
Filing date: 2012-02-10
Publication date: 2012-08-16
Anticipated expiration: 2013-08-10
Also published as: WO2012107938A3; WO2012107938A4

Abstract

Accordingly it is a principle object of the present invention to overcome the disadvantages and limitations of prior art methods and systems and provide a method and system for fire extinguish and rescue, constituted in accordance with the principles of the present invention which will be a oil storage tank farm, wherein burn damage proof and easy to operate fire extinguish and rescue are archived out of the same structure. It is yet another object of the present invention to achieve ground pollution free and minimum oil burning oil storage tank farm.

Description

A METHOD AND SYSTEM FOR GROUND POLLUTION FREE AND MINIMUM OIL

BURNING OIL STORAGE TANK FARM

BACKGROUND

A. Technical Field

[0001] The present invention relates generally to the martial rescue and in resultant fire extinguishing. More particularly the invention relates to a method and system for ground pollution free and minimum oil burning oil storage tank farm with improved tank safety.

B. Background of the Invention

[0002] Generally, the most common and traditional way of storing Inflammable liquid or oil are to store in Oil storage tanks(OST's). These tanks typically hold thousands of gallons of oil. These tanks usually store diesel, crude oil, petrol, kerosene, aviation oil, LPG etc. The stored oil then is transported on need basis, via pipelines, truck tanker's or railway to diff. destinations.

[0003] In India, all refineries are supposed to follow OISD (Oil Industries Safety Directorate) norms. As per OISD norms the total dyke capacity in a tank farm should be enough to contain the fluid of the largest capacity tank within the dyke and all the individual tanks located within the same dyke should be separated by fire walls as shown in Fig. la. As per Petroleum Rules, 2002 the maximum height of the tank dyke is restricted to 2.0 m including 200 mm free board as shown in Fig2a. Same is for National Fire Protection Association (NFPA) NFPA-30 regulation. NFPA- 30 allows for maximum of 1.8 m of dyke height without free board. Thus the prescribed heights for dyke and fire wall are 2 m and 600 mm respectively. For example Fig. 1 a shows a layout of a typical tank farm having four oil tanks of different capacities as per classical design method. Let Tank A and Tank B are of same capacity of j m³ and two small Tanks C and D have capacity of y and z m³ each. As per OISD guidelines the tank dyke capacity is equal to x m³ and not equal to total capacity of four tanks i.e. (2x+y+z) m

[0004] The height of fire wall is 600 mm and the fire wall checks any normal seepage from any tank. The dyke height is 2 m and the enclosed capacity is equal to the capacity of largest tank. When the largest tank A or B catches fire, it may burst. The oil within this tank will spill over the fire walls and will spread within the entire dyke leading to spread of fire over the entire tank farm area. As the fire spreads within the entire dyke, the cooling system stops working and subsequently the other tanks in the farm catch fire. Due to excessive heat if another tank (B, C or D) ruptures, the oil will spill out of the dyke as the dyke capacity is insufficient to hold extra oil above the capacity of largest tank A or B. The extra quantity of oil will spread in the surrounding areas. This excess oil will spread fire and will cause obstruction and delay to fire protection measures and pose danger to the nearest tank farms and other piping manifolds. The occurrences of this type of situation are infrequent as per implicit assumption of OISD. However, when the oil spills from the tanks it is contained inside the dyke until its capacity and beyond that the oil spreads outside into adjoining areas. As the dykes are made of compacted earth and adjoining area may be pervious, the spilled oil seeps into aquifer and will contaminate both groundwater and soil in due course of time. During fire fighting foam solutions are used which come into contact of soil and their harmful chemicals pollute the soil as well as ground water. Therefore, the tank fires not only critically pollutes environment by polluting air, it also pollutes soil and groundwater. [0005] Further, from the view of fire extinguishing, these tanks have fitment of foam fielding system but it is very rare practice. Foam fielding system has a fire detection system, enabling it to sense fire and to pump layer of foam over the tank upper end for creating a layer of foam between liquid and air, hence extinguishing the caused fire. Due to heat detection the cooling system starts working automatically. The cooling systems are connected with charges fire water line. With visual fire detection foam tanker comes and gets attached with the foam couplings available on the roadside on the tankfarm. Then the foams are pumped from foam tankers to the top of tank on fire. This is the general practice of fire fighting with foam solution in oil tanks.

[0006] In case of large scale fires in flammable liquid storage tanks, foam is practically used as an efficient fire extinguishing agent. Foam is an aggregate of air-filled bubbles formed from aqueous solutions and is lower in density than the lightest flammable liquids. Foam is known for its fire knock-down capability and for blanketing the flammable liquid surface on which it is applied. It is principally used to form a coherent floating blanket on flammable and combustible liquids lighter than water and prevents or extinguishes fire by excluding air and cooling the oil. It also prevents reignition by suppressing formation of flammable vapors. It has the property of adhering to surfaces, providing a degree of exposure protection from adjacent fires. Foam may be used as a fire prevention, control, or extinguishing agent for flammable liquid storage tanks or processing areas.

[0007] Further, one way of extinguishing fire is through the use of Dry chemical powder extinguishant. Dry chemical powder extinguishant is used mainly for knocking down the flammable liquid fires. Dry chemical powder is a fine amorphous mixture which is used as a fire extinguishing agent. The principal base chemicals used in the production of currently available dry chemical extinguishing agents are sodium bicarbonate, potassium bicarbonate, potassium chloride, urea potassium bicarbonate, and mono ammonium phosphate.

[0008] Further, the presently available fire extinguishing solutions for oil storage tanks are: combination of foam and dry chemical powder for extinguishment of flammable liquid fires in storage tanks is presently being used, either by top surface application or by subsurface/semi-subsurface applications.

[0009] The drawback of top surface application is that when the roof of the fixed/floating roof tank gets blown off, the top surface application device(s) gets damaged and is unable to perform its function.

[0010] Further, In case of subsurface/semi-subsurface application, the foam bubbles carry along with them the flammable liquid and thus add to the fire and moreover the foam bubbles get broken off due to immediate heat contact and increase in the surface tension of the bubble surface because of the embedded flammable liquid; thus fueling the fire and, ultimately, rendering themselves ineffective in extinguishing the fire.

[0011] Further, in another way of extinguishing fire through the use of Dry chemical powder extinguishant, the major drawback is that it cannot be applied by using subsurface/semi subsurface application methods.

[0012] If the fire is not extinguished in proper time, the fire spreads and burns the other tanks nearby and the complete stored oil gets burned.

[0013] The oil output valves are fixed on the outer lower surface of the tanks. During fire, the overall temperature of the zones rises high and 'hence it becomes, impossible to reach and operate the valve, hence in view of failure of release of valve, the overall tank oil gets burned.

[0014] During emergencies if the electrically operated fire firefighting system fails to operate, then the overall oil is burned.

[0015] For the reasons stated above, which will become apparent to those skilled in the art upon reading and understanding the specification, there is a need in the art for ground pollution free and minimum oil burning oil storage tank farm.

SUMMARY OF THE INVENTION

A method and system for ground pollution free and minimum oil burning oil storage tank farm, wherein fire extinguish and rescue are archived out of the same structure. It is yet another object of the present invention to achieve burn damage - proof and easy to operate fire extinguish and rescue method and system.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Reference will be made to embodiments of the invention, examples of which may be illustrated in the accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in the context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.

[0017] The above and other objects, features and advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: [0018] FIG. 1 is a typical tank farm area with pipes having non returning valves.

[0019] FIG. la is a typical tank farm area with tanks as per conventional method.

[0020] FIG. 2a is the schematic cross section view of tank farm at normal condition.

[0021] FIG. 2b is the schematic cross section view of tank farm at valve opening condition.

[0022] FIG. 2c is the schematic cross section view of tank farm at valve closing condition.

[0023] FIG. 3a is the cross section view of new tank farm along with geomembrane location, fire wall location and valve arrangement.

[0024] FIG. 3b is the cross section view of modified existing tank farm along with geomembrane location, fire wall location and valve arrangement.

[0025] FIG. 3c is the cross section view of new tank farm along with geomembrane location, fire wall location and valve arrangement along with gravel filled, open type trapezoidal ditch drain.

[0026] FIG. 3d is the cross section view of modified existing tank farm along with geomembrane location, fire wall location and valve arrangement along with gravel filled, open type trapezoidal ditch drain. [0027] FIG. 3e is the cross section view of new tank farm along with geomembrane location, fire wall location and valve arrangement along with gravel or sand filled, closed type tile drain.

[0028] FIG. 3f is the cross section view of modified existing tank farm along with geomembrane location, fire wall location and valve arrangement along with gravel or sand filled, closed type tile drain.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

[0029] The embodiments herein provide a method and system for ground pollution free and minimum oil burning oil storage tank farm. Further the embodiments may be easily implemented in various fire extinguishing techniques and setups. The method of the invention may also be implemented as application performed by a stand alone or embedded system.

[0030] The invention described herein is explained using specific exemplary details for better understanding. However, the invention disclosed can be worked on by a person skilled in the art without the use of these specific details.

[0031] References in the specification to " one embodiment" or " an embodiment" means that a particular feature, structure, characteristic, or function described in connection with the embodiment is included in at lest one embodiment of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment. [0032] Hereinafter, the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Reference now should be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components. For clear description of the present invention, known constructions and functions will be omitted.

[0033] Parts of the description will be presented in terms of operations performed by a system, using terms such as valve, seamless pipe, tank, viscosity, force, flammability and the like, consistent with the manner commonly employed by those skilled in the art to convey the substance of their work to others skilled in the art. As is well understood by those skilled in the art, these quantities are capable of being, transferred, combined, and otherwise manipulated through components of the system; and the term system includes general purpose as well as special purpose rescue, fire extinguish and the like components, that are standalone, adjunct or embedded.

[0034] As per one of the embodiment of the present invention, the system for fire extinguish and rescue of inflammable liquid or oil at oil storage wherein the groups of tanks are located in a single tank farm.

[0035] As per one of the embodiment of the present invention the dyke is having the holding capacity of the largest tank volume excluding freeboard.

[0036] As per one of the embodiment of the present invention the fire wall have height same as dyke without freeboard. The fire wall is uncracked, liquid retaining structure to prevent seepage while holding oil in tank burst case. One layer of fire clay brick shall be laid all along the exposed surface of the firewall.

[0037] As per another embodiment each segment of fire wall have opening for minimum two or multiple of two non return valves to cater flow from both directions. The openings in firewall for non return valve is monolithic casting to prevent seepage of oil during tank burst case. The non return valves are fire rated as per liquid handled, leak proof and tight shut off. These non return valves are operated through hydraulic pressure difference on both sides of the fire walls on which the valves are be installed. Due to tank leakage or tank burst case the liquid level may keep increasing in one chamber. Due to pressure difference in the non return valve opens and the liquid starts flowing from high liquid level to low liquid level.

[0038] As per one of the embodiment of the present invention each firewall segment may be having minimum two or multiple of two valves to cater flow from both directions. Tank A starts leaking and the liquid level starts rising with the compartment of tank A. The valves with tag no 1 and 3 may open due to hydraulic pressure and may liquid starts transferring from tank A compartment to tank C compartment and tank B compartment respectively. The valves with tag no 1 and 3 may be operating in hydraulic pressure difference and the conjugate valves with tag no 2 and 4 may get closed with pneumatic operation or with any other means. It makes the valves with tag no 2 and 4 may be inactive for hydraulic pressure difference.

[0039] As per one of the embodiment of the present invention, as the liquid levels may start increasing in tank B and tank C compartments the valves with tag no 5 and 7 may open hydraulically and liquid may starts flowing from tank B and tank C compartment to may be tank D compartment. On the similar fashion the valves with tag no 6 and 8 may get closed with pneumatic operation or with any other means. It makes the valves with tag no 6 and 8 may inactive for hydraulic pressure difference.

[0040] As per one of the embodiment of the present invention, In case of tank B starts leaking the valves with tag no 4 and 5 may start operating in hydraulic pressure and conjugate valves with tag no 3 and 6 may get closed with pneumatic operation or with any other means. It makes the valves with tag no 3 and 6 may inactive for hydraulic pressure difference. The liquid flows from tank B to tank A and tank D compartments. Due to hydraulic pressure difference the valves with tag no 1 and 8 may start operating and transferring fluid from tank A and tank D compartment to may be Tank C compartment. The conjugate valves with tag no 2 and 7 may get closed with pneumatic operation or with any other means. It makes the valves with tag no 2 and 7 may inactive for hydraulic pressure difference.

[0041] As per one of the embodiment of the present invention, due to flow of liquid from high level to low level the liquid level may reach the same level. Thus the valves may shut off as there may be no pressure difference. One set of valves may shuts off the other set of valve which may be intended to work on reverse flow direction already may be inactive by pneumatic operation or any other means.

[0042] As per one of the embodiment of the present invention the non burning liquid may flow from bottom of the burning oil chamber to non burning chambers. As a result fire may not spread only the oil may get separated from burning oil chamber to non burning oil and may be stored using 45 deg bend on the piping arrangement. Only the oil captured within the burning oil segment may get burned other than all the oils from all oil tanks. Thus much less oil may burns from the conventional method.

[0043] As per one of the embodiment of the present invention Oil may stores with the tank dyke. The geomembrane may be spread below the tank farm area upto the oil height of the dyke. The geomebrane may be spread over locally available compacted good earth or sand. The drainage layer may be laid over the geomembrane on flat ground alone with gravel pit at convenient place to collect the percolated water or oil. The drainage layer may have the proper slope towards the pit for ease of drainage. Where sand is not locally available then second layer of geotextile sheet may be used for drainage purpose. The compacted earth along with one layer of fire clay bricks at top may be spread over drainage layer and on embankments to protect the geomembrane from fire situation. The fire walls, drains and sand traps may be constructed over the geomembrane.

[0044] As per one of the embodiment of the present invention At the junction of dyke wall and fire wall the extra geomembrane sheet may be provided upto the liquid limit and earth and one layer of fire clay brick may be covered over the geomembrane to protect the same from fire situations. The geomembrane may protect the ground soil and ground water to get polluted from storage of liquid in the tank farm area and the chemicals used for fire protection.

[0045] As per one of the embodiment of the present invention Open type gravel fill Ditch drain may be provided outside of the tankfarm while water table is higher than geomembrane level to protect deformation of geomembrane from uplift.

[0046] As per one of the embodiment of the present invention Closed type sand filled Tile drain may be provided outside of the tankfarm while water table is higher than geomembrane level to protect deformation of geomembrane from uplift.

[0047] As per one of the embodiment of the present invention The Ditch drain/ Tile drain shall be provided in such a spacing, location and depth so that the water table is below 300mm from bottom of geomembrane in all points of the tank farm

[0048] As per one of the embodiment of the present invention the dyke enclosure is designed for the largest capacity of the tank within the tank farm. The more area acquisition to hold the total capacity of all the tanks are not required in line with present practice.

[0049] As per another embodiment of the present invention no back pumping is required to avoid spillage. But it is ensured that pumping should be stopped to any other tanks when any tank within the tank farm is on fire.

[0050] As per one of the embodiment of the present invention huge amount of oil burning could be stopped as the system segregates the oil from the ruptured tank and it is stored in the other part of the dyke. The volume of oil that will burn will be always less that the tank volume, as the oil is transferred to other areas within the tank farm. It saves oil from burning and reduces air pollution and noise pollution. It also saves the limited natural resources of to get burned without any meaning use. [0051] As per one of the embodiment of the present invention this system can be implemented easily by modifying the firewalls, and tank farm flooring of the existing tank farms without disturbing the tank locations.

[0052] As per one of the embodiment of the present invention The fire walls are designed as uncracked liquid retaining structure. The tank farm flooring is having geomembrane to protect ground soil and groundwater. It protects contamination of ground soil and ground water from accidental liquid spillage and intentional use of foam solution during fire fighting.

[0053] As per another embodiment of the present invention in any interface two non return valves are installed to cater flow from both sides. The nonreturn valves are fire rated as per liquid handled. The valves are leak proof and tight shut off. The valves have failsafe operation during hydrostatic pressure difference on both side of the firewall.

[0054] As per one of the embodiment of the present invention less foam solution is required with this prevention method. With this prevention method less manpower is required as only one tank will be required to be doused instead of all tanks within the tank farm area.

[0055] As per one of the embodiment of the present invention the proposed method poses less danger of fire spread out side of the tank farm and hence reduces associated losses. It also includes indirect benefits such as increased time to react and more time for counter and control measures to such disasters. No underground storage is required to store the oil during fire. No gravity flow of oil from burning tank to any underground tank. The oil will be transmitted by hydrostatic pressure from burning oil chamber to non burning oil chamber. [0056] As per one of the embodiment of the present invention all the non burning tanks shall be kept cool by the cooling water spray system to avoid getting heated. Foam shall be spread over the entire tank farm so that the oil stored in the other part of the fire wall but within the same dyke shall not catch fire.

[0057] As per one of the embodiment of the present invention the dyke enclosure may be designed for the largest capacity of the tank within the tank farm. So may not be necessary to go for more area acquisition to hold the total capacity of all the tanks.

[0058] As per one another embodiment of the present invention no back pumping may be required to avoid spillage. But it may be ensured that pumping may be stopped to any other tanks when any tank within the tank farm may be on fire.

[0059] Further, huge amount of oil burning may be stopped as the system segregates the oil from the ruptured tank and it may be stored in the other part of the dyke. The volume of oil that may burn may be always less that the tank volume, as the oil may be transferred to other areas within the tank farm. This may save oil from burning and reduce air pollution and noise pollution.

[0060] This system may be implemented easily by modifying the firewalls of the existing tank farms without disturbing the tank locations. It may not require more area to be acquired for the tank farm. In any interface at least two non return valves may be installed so that flow from both sides can be accommodated. Less foam solution is required with this prevention method. [0061] With this prevention method less manpower may be required as only one tank may be required to be doused instead of all tanks within the tank farm area. The proposed method may poses less danger of fire spread out side of the tank farm and hence may reduces associated losses. It may also include indirect benefits such as increased time to react and more time for counter and control measures to such disasters.

[0062] As this method may anticipate the oil storage in dyke area so the dyke compound and tank farm should be leak proof and should be such treated so that ground soil and ground water may not get contaminated due to oil storage and foam application.

[0063] Further, on extinguishing fire, the oil from the dyke will be transported / transferred through appropriate means further required processing.

[0064] It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in .all respects .as illustrative and not restrictive.

Claims

We Claim:

1. A system for fire extinguish and rescue of inflammable liquid or oil at oil storage tank farm comprises : a group of tanks located in the a tank farm

a leak proof dyke compound and tank farm

a Dyke having holding capacity of largest tank volume excluding freeboard. fire wall having opening for minimum two or multiple of two non return valves

a layer of fire clay brick along the surface of the firewall minimum two or multiple of two non return valves

45 deg bend piping arrangement

geomembrane spread below the tank farm area

a drainage layer laid over the geomembrane on flat ground alone with gravel pit at convenient place to collect the percolated water or oil

compacted earth along with one layer of fire clay bricks at top spread over drainage layer and on embankments to protect the geomembrane from fire situation.

fire walls, drains and sand traps are constructed over the geomebrane.

geomembrane sheet and one layer of fire clay brick covered over the geomembrane at the junction of dyke wall and fire wall

drain(s) provided outside of the tankfarm.

2. The system as claimed in claim 1 , wherein the fire wall have height same as dyke without freeboard

3. The system as claimed in claim 1 , wherein the firewall is uncracked, liquid retaining structure preventing seepage.

4. The system as claimed in claim 1 , wherein the opening in firewall for

nonreturn valve is monolithic casting to prevent seepage of oil during tank burst case.

5. The system as claimed in claim 1, wherein the nonreturn valves are fire rated as per liquid handled, leak proof and tight shut off.

6. The system as claimed in claim 1 , wherein the geomembrane is spread below the tank farm area upto the oil height of the dyke.

7. The system as claimed in claim 1, where in the geomembrane is spread over compacted .goo.d .earth and sand.

8. The drainage layer as claimed in claim 1 shall have the proper slope towards the pit for ease of drainage.

9. The drainage layer as claimed in claim 1, also alternatively laid by using another layer of geotextile sheet that is used for drainage purpose.

10. The extra geomembrane sheet as claimed in claim 1 is provided upto the liquid limit and earth, at the junction of dyke wall and fire wall.

11. The drains provided outside of the tank farm as claimed in claim 1 are open .type,gravel .fill Ditch drains.

12. The drains provided outside of the tank farm as claimed in claim 1 are Closed type sand filled Tile drains.

13. The Ditch drain/ Tile drain as claimed in claim 11 and claim 12 are provided in such a spacing, location and depth, that the water table is below 300mm from bottom of geomembrane in all points of the tank farm.

14. The method for fire extinguish and rescue of inflammable liquid or oil at oil storage tank farm, the method comprising steps of

Constructing a system as claimed in one of the preceding claims;

Operating the system during the burst or fire at the tank farm, wherein the functioning the system comprising steps of :

pumping is stopped to all or any other tanks along with tank with fire when any tank within the tank farm is on fire.

Operating/opening the non return valves through hydraulic pressure difference and maintaining closed / closing conjugate valves of the opened valves with pneumatic operation or with any other means to make them inactive for hydraulic pressure difference.

Shutting off the open non return valves on equalization of levels and observed no pressure difference in the two compartment linked through the valve and the conjugate set of valve which is intended to work on reverse flow direction already made inactive by pneumatic operation or any other means. draining the non burning liquid from bottom of the burning oil chamber to non burning chambers and storing using 45 deg bend on the piping arrangement.

All the non burning tanks are kept cool by the cooling water spray system to avoid getting heated.

Foam is spread over the entire tank farm so that the oil stored in the other part of the fire wall but within the same dyke shall not catch fire.

Draining the inflammable liquid or oil stored at dyke to secure storage