Fuel and related compositions – Liquid fuels – Inorganic component
Reexamination Certificate
2002-02-27
2004-05-18
Toomer, Cephia D. (Department: 1714)
Fuel and related compositions
Liquid fuels
Inorganic component
C044S437000, C044S439000, C044S451000
Reexamination Certificate
active
06736868
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and a compound for imparting anti-static characteristics to non-conductive fluids, and more particularly, this invention relates to a method and an additive for reducing and/or eliminating electrostatic charge build-up in non-conductive fluids stored in a container or flowing through a conduit.
2. Background of the Invention
Non-conductive hydrocarbon fuels are the most common fluids utilized to generate Power. These hydrocarbon fuels include, but are not limited to, gasoline, diesel fuel and jet fuel.
A hydrocarbon fuel flowing through a conduit accumulates static charge due to impurities in the fluid or due to friction whereby electrons are sheared from molecules by adjacent molecules or by engine conduit components, resulting in localized pockets of charge in the fuel. These phenomena are referred to as “Flow-Charging”, “Contact Electrification” and “Charge Separation.”
FIG. 1
depicts the phenomenon of fuel charging, generally designated as numeral 10. In this scenario, fuel
12
having ionic impurities
13
is shown. When the fuel is at rest (FIG.
1
A), the impurities adsorb at the interface between the fuel and a surface, such as a pipe wall
14
. One part of the fuel (either a positive or a negative ionic component) has a stronger affinity for the wall
14
than the fuel. If the conduit is comprised of metal, the negative portion of the fuel
12
is more attracted to the wall
14
as noted in FIG.
1
A. (It should be noted, however, that a wall comprised of a different material may attract positive-ion components of any fuel impurities.)
Once the fuel begins to travel through the conduit
14
(in the direction of the arrow in FIG.
1
B), the wall-adsorbed negative ions are left behind. The resulting flowing fuel has a positive charge. The negative charge imparted to the conduit wall
14
is shunted to ground
16
The loci of static charge which accumulate in a flowing hydrocarbon fuel, and the formation of these charges, are impacted by the velocity of fuel flow, the size of the fuel conduit, the dissimilar materials comprising the fuel handling systems (i.e.; metal, plastic, composites and/or elastomers), operating characteristics and componentry of fuel filters and fuel pumps, and the viscosity, temperature and type of fuel. These pockets of static charge can reach magnitudes well in excess of 30,000 volts, which is the voltage where a spark to ground normally occurs. This voltage is known as the breakdown potential.
Numerous fires and explosions have been caused by static spark ignitions from charges generated in hydrocarbons during switch loading operations. Switch loading occurs when fuel is transferred from one location to another, such as from a tanker to storage tanks, from a fuel nozzle to a vehicle, and even when a fuel is sloshing around in a container. This creates the potentially explosive conditions, as discussed supra. In addition, the more pure the fuel, the greater the charge build-up.
Aside from the explosive hazards associated with static electricity build up in fuel, fuel efficiency and power also is compromised. In theory the fuel is supposed to atomize into small homogenous droplets as it is injected into the intake port and/or cylinder/combustion chamber for more efficient combustion. In actuality, less efficient combustion occurs due to was is known as “Wall Wetting.” Wall wetting occurs when a portion of the fuel sticks to metal surfaces of the engine, perhaps due to charged fuel being attracted to an oppositely-charged engine surface.
Wall wetting plays a significant role in the creation of carbon deposits on the intake valves, piston tops and combustion chambers. These deposits adsorb and desorb fuel during combustion. As such, this trapped fuel is not available to produce power, but rather increases carbon build-up, and also increases emissions of carbon monoxide, nitrous oxides and unburnt hydrocarbons. This additional, unburnt fuel situation is known as over-fueling.
The carbon deposits can cause an increase in the pressure of the fuel-gas mixture during the compression cycle of the piston. Also, the carbon deposits create hot spots. The increased pressure and/or the hot spot can cause the fuel-gas mixture to self ignite resulting in lost power and possible damage to the engine.
There have been many attempts and experiments to prevent flow-charging, from flowing the fuel over grounded metal plates, hanging metal chains in the liquid, to conductivity additives. U.S. Pat. No. 5,898,560, awarded to the inventors in the instant matter, includes a device inserted in a fuel line to electrically discharge a flowing hydrocarbon fuel. The device causes the fuel to contact a plurality of metallic pellets stationed inside a metallic enclosure. The metallic enclosure is grounded.
Generally, the utilization of metal substrate to disburse localized charge build-up in fuel has not proven entirely satisfactory. For example, the device disclosed in the '560 patent is expensive to fabricate, expensive to install, and removes less than 50 percent of the static charge from the flowing fuel.
Conductivity additives are available as an alternative to the use of metallic substrates to minimize static build up. While these additives do shorten the time of relaxing the fuel, they also allow the fuel to charge up faster and to greater voltages, as noted in U.S. Pat. No. 3,160,785. Indeed, these fluids have been found to actually promote static electricity build-up, as reported in Naval Research Lab (NRL) Report 8484 and Society of Automotive Engineers (SAE) Report J1645.
There are many types of fuel additives. U.S. Pat. No. 5,522,905 discloses a method whereby an exhaust filter is regenerated by adding organic compounds to diesel fuel in amounts to facilitate burn off of soot which is clogging the filter. U.S. Pat. No. 4,668,247 discloses a method whereby hydrogen energy is released by adding a catalyst to hydrocarbon fuel. U.S. Pat. No. 5,912,190 discloses the use of metal-containing organic compounds to improve the oxidation of carbonaceous products caused by diesel fuel pyrolysis. U.S. Pat. No. 6,102,975 discloses a method whereby a fuel conditioner and improver is added to a hydrocarbon fuel. None of the prior art additives address the problem of static charge in hydrocarbon fuel.
To exacerbate the problem of static build-up, certain gasoline-oxygenation compounds (namely MTBE and Ethanol) used to minimize air pollution, also are pro-static agents. Fire hazard is particularly acute with these compounds given their relatively high Reid vapor pressure (i.e., high volatility characteristics measured in psi at 100° F.).
A need exist in the art for a method and additive that reduces or eliminates static charge from hydrocarbon fuel before the fuel enters a storage vessel, thereby removing the possibility for sparks and an explosion. Also, a need exists in the art for a method and additive that reduces or eliminates static charge hydrocarbon fuels before the fuel is combined with air to generate an explosive mixture. Removal of the static charge would promote a more complete burn of the fuel with corresponding reductions in hydrocarbon particulate matter, carbon monoxide and nitrous oxide emissions to the atmosphere.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method and additive for imparting anti-static characteristics to fuel that overcomes many of the disadvantages of the prior art.
It is another object of the present invention to provide a method for removing static charge from fluid fuel. A feature of the method is mixing fuel with a substance to reduce the electrical resistance of the fuel. An advantage of the method is the realization of increased fuel flow, thereby creating the opportunity to recalibrate/tune engine air/fuel ratios for better power, fuel economy and lower emissions.
Yet another object of the present invention is to provide an additive for minimizing static charge accumulations in fluid fuel. A feature of the add
Colburn Michael R.
Flaynik, Jr. Donald G.
Cherskov & Flaynik
Toomer Cephia D.
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