US3893004A

US3893004A - Apparatus for reducing the strength of electrostatic fields in an oil tanker

Info

Publication number: US3893004A
Application number: US390801A
Authority: US
Inventors: Julian H Dancy
Original assignee: Texaco Inc
Current assignee: Texaco Inc
Priority date: 1973-08-23
Filing date: 1973-08-23
Publication date: 1975-07-01
Anticipated expiration: 1992-07-01
Also published as: NL7506003A

Abstract

The apparatus permits an electrostatic field strength of an initial mist in a substantially empty hold of a tanker to be reduced safely. The apparatus includes a manifold having nozzles receiving a supply of water and a supply of air at a predetermined location in the hold of the tanker. The water is converted to a generated mist and the air from each nozzle aids in the distribution of the generated mist throughout the hold of the tanker. As the water is converted to the generated mist, the water acquires a charge opposite in polarity to the polarity of the electrostatic field of the initial mist. The generated mist is distributed throughout the hold so that the generated mist effectively reduces the strength of the electrostatic field except for a low residual field within safety limits.

Description

"United States Patent 1 Dancy [451 July 1, 1975 APPARATUS FOR REDUCING Tl-IE STRENGTH OF ELECTROSTATIC FIELDS IN AN OIL TANKER [75] Inventor: Julian H. Dancy, Richmond, Va.

[73] Assignee: Texaco Inc., 'New York, NY.

22 Filed: Aug. 23, 1973 [2]] Appl. No.: 390,801

[52] US. Cl 317/2 R; 134/22 R; 239/15 [51] Int. Cl. H05f 3/00 [58] Field of Search 239/3, 15; 244/1 A; 317/2 R, 2 D, 2 E; 134/10, 22 R, 24; 118/621, 629, 627

[56] References Cited UNITED STATES PATENTS 632,185 8/1899 Jones 317/2 R X 2,065,462 12/1936 3,121,027 2/1964 Galanor 134/10 3,164,747 l/l965 Yahnke 317/2 R 3,188,238 6/1965 Lyon 134/22 R X 3,384,446 5/1968 Ziems et al. 239/3 X PUMP FILTER 3,460,988 8/1969 Kennedy et al 134/24 X Primary ExaminerR0bert S. Ward, .lr.

Assistant ExaminerRandolph A. Reese Attorney, Agent, or FirmT. H. Whaley; C. G. Ries;

Ronald G. Gillespie [57] ABSTRACT The apparatus permits an electrostatic field strength of an initial mist in a substantially empty holdof a tanker to be reduced safely. The apparatus includes a manifold having nozzles receiving a supply of water and a supply of air at a predetermined location in the hold of the tanker. The water is converted to a generated mist and the air from each nozzle aids in the distribution of the generated mist throughout the hold of the tanker. As the water is converted to the generated mist, the water acquires a charge opposite in polarity to the polarity of the electrostatic field of the initial mist. The generated mist is distributed throughout the hold so that the generated mist effectively reduces the strength of the electrostatic field except for a low residual field within safety limits.

10 Claims, 2 Drawing Figures AIR SUPPLY OF TANKER i-mm. 1 me Q 3.893; 004

l5 1 7 AIR PUMP FILTER REG. FILTER SUPPLY APPARATUS FOR REDUCING THE STRENGTH OF ELECTROSTATIC FIELDS IN AN OIL TANKER BACKGROUND QETHE INYENTION l.'Field of the Invention The present invention relates to apparatus for reducing the strength of ane ectrostatic field of an initial mist. I

SUMMARY OF THE INVENTION The apparatus reduces the strength of an electrostatic field of an initial mist in a substantially enclosed volume. The apparatus comprises a source providing a The objects and advantages of the invention will appear more fully hereinafter from a consideration of the detailed description which follows, taken together with the accompanying drawings wherein one embodiment of the aforementioned invention is illustrated by way of example It is to be expressly understood, however, that the drawings are for illustration purposes only and are not to be construed as defining the limits of the inventron.

DESCRIPTION OF THE DRAWINGS FIG.-1 depicts apparatus, constructed in accordance with the present invention, for substantially reducing the strength of an electrostatic field of an initial mist in a hold of a tanker.

FIG. 2 is a detailed drawing of a nozzle shown in FIG. 1.

DESCRIPTION OF THE INVENTION In recent years several mammoth oil tankers have experienced explosions. The most probable cause of the explosions has been traced to the existence of a mist, having an electrostatic field, in a-substantially empty hold of a tanker, and a subsequent electrical discharge of that field in the presence of an explosive atmosphere. The apparatus of the present invention combines a mist, having an electrostatic opposite charge, with the initial mist to substantially reduce the net strength of the electrostatic field of the combined mists to a level such that a subsequent discharge, if any, will not cause an explosion.

Referring now to FIG. 1, there is shown a field reduction system. A manifold 1, having nozzles 3, is lowered into the hold of a tanker through one of several openings, generally available, to a predetermined depth. For large holds several manifolds with nozzles may be used simultaneously at difierent locations in the holds. A nozzle 3 is shown in greater detail in FIG. 2. A pump 7 pumps sea Water or fresh water through a filter 9 which filters out particles which may clog nozzles 3. Filter 9 may be of the type manufactured by Dayton Electric Manufacturing Company as their part number 1 P 635.

A conventional type regulator 14 reduces the pres- 216 3. By way of example, the pressure of the water provided by regulator 14 may be within the range of 15 to 30 pounds per square inch.

Referring also to FIG. 2, the water leaving each nozzle 3 is initially a fine stream 17 of water before breaking into droplets 18, forming a mist. Due to the presence' of the strong electrostatic field, water stream 17 is inductively charged to an opposite polarity from that of the field. As stream 17 separates into droplets 18, each droplet 18 has trapped its charge so that it is charged opposite to that of the field.

Each nozzle 3 provides air to help generate the mist and to move the mist away from nozzle 3. When the mist is not moved away the collection of charged droplets 18 acts as a space charge to reduce the charging of water stream 17 until very little opposite charge is being induced in water stream 17.

A supply 28 of air provides air to a conventional type air filter 29 which filters out particles from the air to prevent clogging of nozzles 3. The air pressure is not critical and, as such, no regulator is required. Generally, the tanker has a compressed air line which may be used as supply 28. The air from filter29 is provided to manifold l, by way of hose 35, which in turn provides the air to each nozzle 3. I

Referring now to FIGS. 1 and 2', each nozzle 3 has an inner tubing 37, connected to a hose 39, partially enclosed by outer tubing 38 and a T-fitting 40. Tubing 37 has an inner diameter selected to facilitate the creation of a mist. Tubing 37 may, by way of example, be /s-inch diameter brass tubing. Tubing 38 may be fit-inch diameter brass tubing, having one end soldered to fitting 40 and the other end rolled to create an orifice 44 with respect to tubing 37 so that compressed air in between

tubings

37 and 38, as hereinafter explained, leaves through orifice 44. Tubing 37 is separated from tubing 38 by spacers 45.

Tubing 37 projects a predetermined distance from tubing 38, as shown in FIG. 2. The projection is used to increase the efficiency of the induction of the charge in water stream 17. If tubing 37 did not project out of tubing 38, the electrostatic field would induce a charge on tubing 38 taking away from the induced charge of water stream 17.

Fitting 40 has a threaded end which is perpendicular to the longitudinal axis of

tubings

37 and 38; each nozzle 3 is threaded into manifold l by using that threaded end. The air in manifold 1 enters fitting 40 through the threaded end and leaves by way of orifice 44. The remaining end of fitting 40, not yet discussed, is welded to tubing 37 so that the air can only leave through orifice 44. Another fitting 48 connects hose 39 to the last mentioned end of fitting 44 so that water in hose 39 enters tubing 37. l-Ioses 39 are connected to manifold blocks 50 in groups of three each. Block 50 is connected to tube 15 and facilitates the passage of the water from tube 15 to each nozzle 3 through a corresponding hose 39.

Referring again to FIG. 1, manifold 1, as used, may be a length of brass pipe having tapped holes at predetermined intervals to facilitate the mounting of nozzles 3. The design of manifold l is determined by the volume to be filled with mist. Manifold 1 can carry fifteen nozzles 3, which are mounted in groups of three. The direction of discharge of nozzles 3, about the longitudinal axis of manifold 1, for one group is opposite to the direction of discharge for an adjacent group of nozzles 3 to reduce the rotational effect imparted to manifold 1 by the discharging water from nozzles 3. Nozzles 3 are spatially arranged with manifold so as to achieve the maximum distribution of the mist.

The combined strength of the electrostatic field of the initial mist and sprayed mist is substantially less than the strength of the electrostatic field of the initial mist alone.

The apparatus of the present invention as heretofore described provides a mist in the presence of an electrostatic field in such a manner so that the mist assumes an opposite polarity to the polarity of the electrostatic field of the initial mist. The net strength of the electrostatic field is reduced to a safe value, thus eliminating the probability of an explosion due to the accidental discharge of the electrostatic field.

What is claimed is:

1. Apparatus for reducing the strength of an electrostatic field in a substantially enclosed volume comprising means for providing a supply of liquid at a predetermined pressure at a predetermined location in the volume, means for converting the liquid to droplets to provide a mist, utilizing the electrostatic field to charge the droplets during the converting step to an opposite polarity to the polarity of the electrostatic field, and means for, distributing the oppositely charged mist throughout the volume so that the net strength of the electrostatic field is substantially reduced.

2. Apparatus as described in claim 1 further comprising means for converting the liquid to mists at different providing an air current, having a predetermined direction of flow, through each orifice in such a manner as to carry the mist away from the orifices.

4. Apparatus as described in claim 3 in which the converting means convertsthe liquid to droplets having a size of 30 microns or less.

5. Apparatus as described in claim 4 in which the predetermined liquid pressure may be within a range of 15 to 30 pounds per square inch.

6. Apparatus for reducing the strength of an electrostatic field in a substantially empty hold in an oil tanker, which comprises means for providing a supply of liquid at a predetermined pressure at a predetermined location, in the hold of the tanker, means for converting the liquid to droplets to provide a mist, utilizing the electrostatic field to charge the droplets during the converting step to an opposite polarity to the polarity of the electrostatic field, and means for distributing the oppositely charged mist throughout the hold so that the net strength of electrostatic field and mist is substantially less than the strength of the electrostatic field alone.

7. Apparatus as described in claim 6 further comprising means for converting the liquid to mist at different locations, and means for blowing the mist away from each location.

8. Apparatus as described in claim 7 in which the converting means includes means for providing the liquid through an orifice of a predetermined size, and the blowing means includes means for providing air current, having a predetermined direction, by a corresponding orifice in such a manner as to carry the mist away from the orifice.

9. Apparatus as described in claim 8 in which the converting means includes means for converting the liquid to droplets having a size of 30 microns or less.

10. Apparatus as described in claim 9 in which the predetermined liquid pressure is within a range of '15 to 30 pounds per square inch.

Claims

1. Apparatus for reducing the strength of an electrostatic field in a substantially enclosed volume comprising means for providing a supply of liquid at a predetermined pressure at a predetermined location in the volume, means for converting the liquid to droplets to provide a mist, utilizing the electrostatic field to charge the droplets during the converting step to an opposite polarity to the polarity of the electrostatic field, and means for distributing the oppositely charged mist throughout the volume so that the net strength of the electrostatic field is substantially reduced.

2. Apparatus as described in claim 1 further comprising means for converting the liquid to mists at different locations, and means for blowing the mist away from each location.

3. Apparatus as described in claim 2 in which each converting means includes means having an orifice for providing the liquid through an orifice of a predetermined size, and the blowing means includes means for providing an air current, having a predetermined direction of flow, through each orifice in such a manner as to carry the mist away from the orifices.

4. Apparatus as described in claim 3 in which the converting means converts the liquid to droplets having a size of 30 microns or less.

10. Apparatus as described in claim 9 in which the predetermined liquid pressure is within a range of 15 to 30 pounds per square inch.