Liquid purification or separation – With alarm – indicator – register – recorder – signal or... – Material level or thickness responsive
Reexamination Certificate
1999-04-05
2002-08-13
Popovics, Robert J. (Department: 1723)
Liquid purification or separation
With alarm, indicator, register, recorder, signal or...
Material level or thickness responsive
C210S512100, C210S521000, C210S532100, C210S540000
Reexamination Certificate
active
06432298
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to separating liquids such as petroleum based oils, fuels oils and gasolines from organic and inorganic substances such as water, algae and solids.
BACKGROUND OF THE INVENTION
Petroleum products are the mainstay of modern industry. Produced as oils they are used in lubrication, as power transfer mediums. In distillate forms such as diesel oil and gasolines they are used in the combustion engine. Because of their importance in every phase of commerce and industry new and improved processes and apparatuses for insuring the quality of petroleum products is vitally important to the industrial sector.
Keeping fuel and other oils free from contamination while storage tanks is a constant challenge for users of petroleum products. Contaminants such as water, salt, rust, and other unwelcome ingredients, even bacteria, invade fuel supply tanks and eventually wreck havoc on an engine or power plant. Managing this problem may take a combination of technologies from centrifuges to an arsenal of water strippers, fuel/water separators, media filtration, mesh screens and chemicals.
Other machinery that benefits from devices that can remove water and other unwanted constituents are those that burn fuel oil such as generators of electricity and oil burners. These machines and burners typically utilize heavy fuel oils generally known by various grades of heating oils and diesel fuels. Marine engines, diesel automobiles and trucks, stationary generators and home oil burners burn differing qualities of fuel oils that can benefit from devices that can remove foreign constituents. Many devices exist for separating fuel from foreign constituents, however, most of these are expensive and rely on mechanical mechanisms and filtration media.
For example, reliable operation internal combustion engines and power generation stations depend on fuels free from contaminants such as water and organic and inorganic solids. Additionally, fuel oil that contains water can freeze fuel lines when temperatures drop below 32 degrees Fahrenheit. Water in oil or fuel also reduces the efficiency of engine performance since at least some energy is dissipated in the process of heating the water and not in combustion as well as the water contributing to the oxidation of metal parts. In many instances, water particulate contribute to engine failure, specifically in engines that utilize injectors to atomize fuel for the combustion chambers. Solid particulate in fuel decreases the efficiency and increases the wear due to frictional forces on internal engine parts. When oil is used as a hydraulic fluid it is important that water and other contaminants be kept to a minimum to reduce wear on components and to maintain the action of the fluid in for its intended purpose.
For ships, it is not uncommon for fuel to remain in storage or service tanks for weeks and for sea water to be carried as ballast in emptied fuel tanks. Bunkering, transport, and long storage periods coupled with the intentional introduction of water, create the perfect environment for water and algae which can clog filters, fuel and injector pumps and start a chain of events which may lead to catastrophic engine failure. In the diesel engine, contamination, whether bacteria, sediment or water, can blow injector tips and cause immediate cylinder scoring.
Selecting the processes that provide treatment of water contaminated fuel and oil supply for modern gas turbine and diesel engines depends on properly assessing competing tradeoffs such as: cost, reliability, performance and importantly, application. Not surprisingly, the process of purification relates strongly to the application, that is, the device or engine technology, together with the grade of oil or fuel it will use and how the fuel is stored.
A best engineered solution for fuel purification considers both cost and performance. Electromechanical centrifuges are a popular solution, performance-wise, for purifying fuels in the light crude oil and heavy fuel oils category because these are only partly refined before delivery to the ship's tanks. But, distillates do not need the same level of purification, because they are already highly refined. Electromechanical centrifuges may not be the most cost efficient here, because distillates only require that contaminates introduced in transport or during storage, need removal.
Especially for distillate fuels such as No. 2 Diesel, products now exist to eliminate water and sediment by combining centrifugal fuel flow with a sedimenter technology. Unlike their electomechanical centrifugal counterparts, these products contain no filter media or moving parts, except for the fuel pump needed to keep the fuel flowing. These products have the advantages of: low investment cost, low maintenance costs, high reliability, and the ability to employ cross connected links, permitting various real time configurations to suit a ship's immediate purification needs.
It is well known that impurities such as the presence of an electrolyte or soap in the fluid will cause the water and oil mixture to stabilize. For example, when soap is added to water and oil the result is a stable emulsion that permit the combination to easily be separated from metal and other surfaces, but difficult to separate from each other. But, water and oil can exist in three different states. Free water and oil can remain separate constituents, so called immiscible. In this combination water flows freely in the body of generally greater viscosity oil. The second is the unstable emulsification of oil and water that generally forms droplets of the combination. Here the water/oil forms globules which flow separate from the free water and oil. Thirdly, there is the stable mixture of water and oil.
In the second case, where oil and water are mixed, for example by agitation when oil and water are contained in the same storage tank being used to fill a supply tank, an unstable colloidal dispersion may result. The first colloid is of water in oil and the second oil in water. Coalescing of these colloidal droplets separate into a top layer of oil and a bottom layer of oil. In a tank or sump the water generally settles to the bottom and the oil on the top of the water. And, because oil and water are relatively immiscible, if there is a positive pressure applied during the flow of oil and water the two constituents can be separated into different paths.
The dynamics of the so called emulsified droplets depend to a large degree upon the drag coefficients and flow characteristics of the liquid, ranging from laminar flow to turbulence and defined by the Reynolds number. In defining the values of the energy undertaken by the emulsified particle in a fluid flow we look to the relative value between the emulsified droplet and the bulk fluid.
According to Stokes law, a particle such as an emulsified oil/water particle, falling under the action of gravity will accelerate until the frictional drag of the fluid just balances the gravitational acceleration after which it continues to fall under constant velocity, know as the free settling velocity. To capitalize on the Stokes principle in separating a water particle from an oil particle, the flow of the oil/water mass should remain relatively laminar.
U.S. Pat. No. 4,986,907 describes a diesel fuel refining apparatus that works on a principle of centrifugal forces from a motion the fuel is forced to undergo as it is drawn through the apparatus under the pressure of a pump. In this disclosure claimed centrifugal forces are created when the fuel discharges from an interior pipe and impacts against a pre heated generally flat rectangular metal plate which runs diametrically across a cylindrical container and also substantially longitudinally the length of the interior of the cylinder housing. Due to the preheating of the plate and the angular relationship maintained by the conduit and the plate, the fuel that leaves the pipe and hits the plate is projected to create a turbulence that is claimed to facilitate separation of the
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