US3862427A - Apparatus and method for diminishing electric fields within containers of flammable material - Google Patents
Apparatus and method for diminishing electric fields within containers of flammable material Download PDFInfo
- Publication number
- US3862427A US3862427A US395042A US39504273A US3862427A US 3862427 A US3862427 A US 3862427A US 395042 A US395042 A US 395042A US 39504273 A US39504273 A US 39504273A US 3862427 A US3862427 A US 3862427A
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- container
- ray
- sources
- gaseous
- ions
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05F—STATIC ELECTRICITY; NATURALLY-OCCURRING ELECTRICITY
- H05F3/00—Carrying-off electrostatic charges
- H05F3/06—Carrying-off electrostatic charges by means of ionising radiation
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
- H01T23/00—Apparatus for generating ions to be introduced into non-enclosed gases, e.g. into the atmosphere
Definitions
- the present invention relates to an apparatus and a method for diminishing .to spark-free levels the intensity of undesirable electrostatically-generated electric fields within the gaseous spaces of large containers of flammable liquids and gases.
- Flammable products in both liquid and gaseous form are stored in large storage containers and transported over waterways in large tankers.
- One crucial safety concern is the formation of electrostatically induced electric fields withinthe container. If these fields reach the intensity which causes sparking, and if the gaseous regions contain oxygen, the flammable products could ignite or detonate.
- the surface motion in a rolling sea of a large fluidfilled system can likewise cause charge separation and the attainment of dangerous sparking conditions.
- the region surrounding isolated electric charge of a given polarity is filled with an electric field due to that charge.
- This electrically stressed region extends until the field lines can terminate on an equal number of chargesof the opposite polarity. This means that in closed system the field will fill the entire volume extending to everysurface and corner thereof.
- the distribution (intensity) of electric stress of the field is affected by the geometry of the container including the relative distance of the walls from the isolated charge and by projections from the walls which would serve to intensify the field.
- a plurality of modular X ray sources are affixed in a distributed array to the upper surface of acontainer hous ing a vaporizable liquid and its vapor.
- Each source includes a high voltage generator, an electron accelerating tube and a grounded anode X-ray target. Electric power is supplied to the sources to maintain them in operation during extended periods when electrostatic hazards exist.
- the X-rays emerge from said sources into the interior of said container as wide angle beams to produce free ions of both polarities throughout the 7 portion of the container housing the vapor.
- FIG. 1 is a schematic diagram of a modular X-ray source in accordance with the present invention
- FIG. 2 is a diagram depicting an array of X-ray sources in a liquid fuel tank
- FIG. 3 is a diagram in perspective of a storage tank having X-ray sources according to the present inventron
- FIG. 4 is a diagram depicting the electric field arising from electrical charges in the storage tank of FIG. 3;
- FIG. 5 is a diagram depicting the reduction in the electric field of FIG. 4 by the X-ray source according to the present invention.
- a modular X-ray source represented generally by the reference numeral 10
- a container 12 of the flammable fluids typically, this container 12 is made of steel, and when the container is a tanker, such as in FIG. 2, it may be about one inch thick.
- the source is enclosed within a dome-shaped upper cover 14 which is suitably secured to a lower plate 16. By this arrangement, the components of the X-ray source 10 are maintained in a water and gas tight manner.
- the components of the X-ray source 10 include a high voltage generator 24, an electron accelerating tube 26 and an X-ray target 28.
- the target 28 extends into an X-ray permeable aperture in the container 12.
- the X-rays are produced by electrons with energies less than 300 kiloelectron volts.
- a source of electrical power (not shown) operates the high voltage generator 24.
- the X-ray source 10 develops wide angle beams of X-rays which radiate into the region within the container as shown at 30 in FIG. 1
- the energy of the X-rays and the X-ray stopping power of the upper container and of the modular sources are designed so that above one meter from the upper surface of the container the X-ray intensity is below the internationally accepted safe limit for human exposure.
- the X-ray target is maintained no higher than 60C above the temperature of the container 12; this is accomplished by thermal conduction of the buildup of heat in the target through metal to the container 12.
- the resultant average density of free ions of both polarities within the gaseous space is at least two orders of magnitude higher than the average free ion density produced therein by naturally available ionizing processes.
- FIG. 2 there is shown an array of X-ray sources 10 for a liquid fuel tanker 32.
- the lines indicate the various liquid compartments within the fuel tanker 32.
- the tanker might be full, partly full, or virtually empty. There can in all cases be electrically dangerous fields.
- FIG. 3 shows a large storage tank 12 and an array of deck-mounted X-ray sources 10 which irradiate the gaseous region below.
- Wide angel beams 32 of X-rays are produced so that the X-rays are absorbed by as large a volume of the gas within the tank 12 as possible.
- FIGS. 4 and 5 show a typical storage tank, such as in FIG. 3.
- the container 12 which is grounded, is partially filled with a flammable liquid 50.
- the region above the liquid 50 which is represented generally by the reference numeral 52, contains some oxygen and vapors from the fluid 50.
- friction produced by relative motion between the fluid 50 and other forms of matter, such the walls of the container 50 and fluid transfer pipes. creates an accumulation of electrical charges in the fluid 50.
- FIGS. 4 and 5 the fluid has a net accumulation of negative charges, which means the fluid has an overabundance of electrons, it is also conceivable that the fluid could also have a net positive charge.
- the negative charge is distributed throughout the volume of the fluid 50.
- the liquids with which the invention is concerned are insulating liquids.
- An insulating liquid is one that resists the flow of electric charge. This means that charge which may have been frictionally supplied to the volume of the liquid will tend to stay trapped therein for long periods of time. These times could be of the order of minutes, hours and days.
- insulating liquid we mean one which has a resistivity higher than 10 ohms/cm.
- a good insulating oil may have a resistivity of 10 and an excellent insulating oil of 10 ohms/cm. It would take the latter fluid nearly a year to conduct to the surface of the metal container within which it is placed. Since the liquid resists the flow of electrical charge, the electrons cannot readily migrate to the grounded metal container whereby they would otherwise be neutralized. Thus, other means must be provided for neutralizing the effect of the net charge in the liquid.
- the region surrounding an isolated electric charge of a given polarity is filled with an electric field due to that charge.
- This field is represented in FIG. 4 by an array of electric field lines 54 which extend from one side of the container, through the gaseous region 52 and the fluid 50, to the other side of the container. For the reasons previously stated, the danger created by this field is greatest in the gas-filled region.
- the effect. of the introduction' of X-rays is to substantially neutralize the electric field in the gaseous part of the system.
- the X-rays produce ions of both polarities in the gaseous space within the container.
- the present invention comprehends the formation of ions in the gaseous region of a container housing a flammable liquid which has an electrical charge, the effect of the ions being to neutralize the electric field in the gaseous region created by the charge.
- the hazardous electric field may be produced by the injection of matter in the form of airborne particles into a large container or in transfer through a large conduit. Typical examples are the transfer and storage of combustible materials such as coal and coal dust, and the conveying of flour through a mill.
- Apparatus for diminishing to spark-free levels the intensity of unwanted electric fields within the gaseous spaces of large containers of flammable liquids and gases including: at least one container housing a vaporizable liquid subject to accumulation of unwanted charge of one polarity and its vapor, a plurality of mod- X-rays emerging from said sources into theinterior of said container as wide angle beams to produce free ions of both polarities throughout said gaseous spaces, those of said ions which have a polarity opposite to that of said unwanted charge moving toward said unwanted charge to neutralize the field effects of said unwanted charge.
- the apparatus according to claim 1 further including water-tight and gas-tight metallic enclosures for the X-ray sources.
- a method of diminishing'to spark-free levels the intensity of unwanted electric fields within the gaseous spaces of a large container of flammable liquids and gases including .the steps of:'
- each source consisting of a high voltage generator, an electron accelerating tube and a grounded anode X-ray target,
- the method according to claim 8 further including producing electrons within the X-ray source with energies less than 300 kiloelectron-volts.
- the method according to claim 8 further includ ing maintaining the level of X-ray intensity one meter above the upper surface of the container below the internationally accepted safe limitfor human exposure.
- X-ray sources being mounted above theseregions ions of both polarities within the gaseous space at least two orders of magnitude higher than the average free ion density produced therein by naturally available ionizing processes.
- a container adapted to be at least partially filled with a flammable liquid or with airborne solid particles, said liquid or said particles having a net unwanted electric charge of one polarity, said charge creating an electric field within the container which extends through the gaseous regions of said container, and an X-ray source to ionizing at least a portion of said gaseous region, said X-rays producing mobile free ions of both polarities, those of said ions which have a polarity opposite to that of said unwanted charge being attracted towards said charge to reduce the electric field within the gaseous region of said container to sparkfree levels.
- said ionization adapted to create mobile ions of both polarities which migrate within said container to neutralize the electric fields produced by the unwanted accumulation moderate amounts of X-ray energy to continuously ionof charges.
Abstract
Description
Claims (17)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US395042A US3862427A (en) | 1973-09-07 | 1973-09-07 | Apparatus and method for diminishing electric fields within containers of flammable material |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US395042A US3862427A (en) | 1973-09-07 | 1973-09-07 | Apparatus and method for diminishing electric fields within containers of flammable material |
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US3862427A true US3862427A (en) | 1975-01-21 |
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US395042A Expired - Lifetime US3862427A (en) | 1973-09-07 | 1973-09-07 | Apparatus and method for diminishing electric fields within containers of flammable material |
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Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4194124A (en) * | 1977-10-11 | 1980-03-18 | Gardner Howard S | Method of preventing vapor explosions caused by contact of two liquids having different temperatures |
EP0671871A1 (en) * | 1992-08-14 | 1995-09-13 | Takasago Netsugaku Kogyo Kabushiki Kaisha | Appararus and method for producing gaseous ions by use of x-rays, and various apparatuses and structures using them |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1754950A (en) * | 1924-06-05 | 1930-04-15 | Henocque Victor Albert | Process and apparatus for obtaining new radiations |
US2463569A (en) * | 1943-11-17 | 1949-03-08 | Raytheon Mfg Co | Apparatus for treating gaseous media |
US2972086A (en) * | 1954-07-28 | 1961-02-14 | Ct Tech Ind Dit I Textile De F | Removal of static electricity in fibers, textile materials, and other materials capable of being charged with static electricity |
-
1973
- 1973-09-07 US US395042A patent/US3862427A/en not_active Expired - Lifetime
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1754950A (en) * | 1924-06-05 | 1930-04-15 | Henocque Victor Albert | Process and apparatus for obtaining new radiations |
US2463569A (en) * | 1943-11-17 | 1949-03-08 | Raytheon Mfg Co | Apparatus for treating gaseous media |
US2972086A (en) * | 1954-07-28 | 1961-02-14 | Ct Tech Ind Dit I Textile De F | Removal of static electricity in fibers, textile materials, and other materials capable of being charged with static electricity |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4194124A (en) * | 1977-10-11 | 1980-03-18 | Gardner Howard S | Method of preventing vapor explosions caused by contact of two liquids having different temperatures |
EP0671871A1 (en) * | 1992-08-14 | 1995-09-13 | Takasago Netsugaku Kogyo Kabushiki Kaisha | Appararus and method for producing gaseous ions by use of x-rays, and various apparatuses and structures using them |
EP0671871A4 (en) * | 1992-08-14 | 1997-05-21 | Takasago Thermal Engineering | Appararus and method for producing gaseous ions by use of x-rays, and various apparatuses and structures using them. |
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Legal Events
Date | Code | Title | Description |
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AS | Assignment |
Owner name: MARINE MIDLAND BANK, N.A. Free format text: SECURITY INTEREST;ASSIGNOR:HIGH VOLTAGE ENGINEERING CORPORATION;REEL/FRAME:005009/0952 Effective date: 19880801 |
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AS | Assignment |
Owner name: FIRST NATIONAL BANK OF BOSTON Free format text: SECURITY INTEREST;ASSIGNORS:COMFAB TECHNOLOGIES, INC.;HIGH VOLTAGE ENGINEERING CORPORATION;REEL/FRAME:005258/0013;SIGNING DATES FROM |
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AS | Assignment |
Owner name: FLEET NATIONAL BANK Free format text: SECURITY INTEREST;ASSIGNOR:HIGH VOLTAGE ENGINEERING CORPORATION, A MA CORPORATION;REEL/FRAME:005748/0283 Effective date: 19910607 |
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AS | Assignment |
Owner name: SANWA BUSINESS CREDIT CORPORATION AS COLLATERAL AG Free format text: COLLATERAL ASSIGNMENT OF COPYRIGHTS, PATENTS, TRADEMARKS AND LICENSES;ASSIGNORS:HIGH VOLTAGE ENGINEERING CORPORATION;DATCON INSTRUMENT COMPANY;HALMAR ROBICON GROUP, INC.;AND OTHERS;REEL/FRAME:008013/0660 Effective date: 19960509 |