US3306828A

US3306828A - Method and apparatus for improving the quality of low grade fuel oils

Info

Publication number: US3306828A
Application number: US327976A
Authority: US
Inventors: Mori Sakon
Original assignee: Individual
Current assignee: Individual
Priority date: 1963-12-04
Filing date: 1963-12-04
Publication date: 1967-02-28
Anticipated expiration: 1984-02-28

Description

Feb. 28, 1967 SAKON MORI 3,306,828

METHOD AND APPARATUS FOR IMPROVING THE QUALITY OF LOW GRADE FUEL OILS Filed Dec. 4, 1963 3 Sheets-Sheet 1 INVENTOR Feb. 28, 1967 SAKON MORl 3,306,828

METHOD AND APPARATUS FOR IMPROVING THE QUALITY OF LOW GRADE FUEL OILS Filed Dec. 4, 1963 5 Sheets-Sheet 2 INVENTOR.

Am W

Feb. 28, 1967 SAKON MORI 3,306,828

METHOD AND APPARATUS FOR IMPROVING THE QUALITY OF LOW GRADE FUEL OILS Filed Dec. 4, 1963 3 Sheets-Sheet 5 INVENTOR.

BY lath M United States Patent 3,306,828 METHOD AND APPARATUS FOR IMPROVING THE QUALITY OF LOW GRADE FUEL OILS Sakon Mori, 2394 Kugenuma, Fujisawa-shi, Kanagawa-ken, Japan Filed Dec. 4, 1963, Ser. No. 327,976 3 Claims. (Cl. 196-46) The present invention relates to a method and apparatus for improving the quality of low grade fuel oils, more particularly low grade fuel oils for use in such fuel consumers as internal combustion engines installed on the ship and vehicle, and boilers in steam electric power plants.

Heavy oils comm-only available on the market comprise mixtures of gas oil and residual still bottom fuel oil which is obtained by extracting gasoline, kerosene, gas oil and the like from crude mineral oil. In Japan heavy oils for use as fuel are classified into A fuel, B fuel and C fuel. Generally speaking, higher grade fuel oil contains more gas oil and lower grade fuel oil contains more residual still oil as is illustrated in the following table.

However, in practice, since the viscosity of the residual still bottom fuel oil varies depending upon the origin of the crude oils, the proportions of the ingredients of these mixtures are made somewhat different from those illustrated in the above table taking in considerations such factors as viscosity and the like.

The price of low grade fuel oils such as C fuel containing high percentages of residual still botto-m fuel is cheap. But such low grade fuel oils are infurious to internal combustion engines as well as boilers. More particularly, such low grade oils not only damage cylinder liners and piston rings of diesel engines, but also cause corrosion of preheaters for combustion air, economizers and other components of boilers due to sulphur, vanadium and other impurities as well as contamination or damage of heat receiving surfaces of boilers due to heavy carbon deposit and vanadium attack. It is also recognized that low grade fuel oils such as C fuel and the like containing high percentages of residual still bottom fuel oil Will damage internal combustion engines and boilers due to moisture and other impurities contained in the residual still bottom fuel oil.

It is very diflicult to remove moisture from low grade fuel oils, especially from those having a specific gravity of about 1.0 and high viscosity. Thus the moisture can not be well removed even when the fuel oil is treated by a centrifugal separator. Also by using heat, the moisture cannot be removed unless the fuel oil is heated to a temperature above 100 C. But heating above 100 C. results in bad effects upon cylinders and other components of internal combustion engines. Thus heating of fuel oils is limited to the boiling temperature of water (100 C.) and heating to any higher temperature should be avoided in any case.

The Water that can be removed from fuel oils by centrifugal separators is contained in free state and the quantity thereof is small. Remaining water is mainly contained in the particles of fuel oils as a suspension. Thus, a great number of heavy oil particles are suspended in residual still bottom fuel oils. These oil particles comprise a coating of rubbery or lacquer-like subst-ance around a particle of water, which may be termed as an ice emulsion. Also such impurities as metal, sulphur and the like are attached on said rubbery or lacquer like coating. Low grade fuel oils having hgh viscosity and high specific gravity, for example those having a specific gravity of higher than 0.98 and a viscosity of more than 1000 sec. when measured by Redwood No. 1 viscosimeter at 50 C., cannot be purified by centrifugal separators. Moreover moisture contained in such heavy oil particles cannot be removed by heating at a temperature below the boiling temperature of water C.).

There is also a method of removing water contained in low grade fuel oils called as fuel oil treatment wherein a chemical agent is mixed with them. However this method would merely render unstable the emulsified heavy oil particles but cannot impart any mechanical force to such particles.

The principal object of this invention is to improve the quality of a low grade fuel oil which contains essentially or a large quantity of residual still bottom fuel oil (for brevity, hereinafter the term low grade fuel oil means such oil) by a relatively simple physical means so that it can be satisfactorily used as fuel for various consumer such as internal combustion engines, boilers and gas turbines.

Another object of this invention is to separate and remove such impurities as moisture, iron, copper, vana dium, or other metals, sulphur, salts, asphalt, etc. contained in the low grade fuel oil by a physical means whereby to improve its quality.

Still another object of this invention is to provide a novel apparatus of simple construction adapted to improve the quality of the low grade fuel oil.

Yet another object of this invention is to provide an apparatus for improving the quality of the low grade fuel oil which has a novel oil crusher adapted to destroy the so-called heavy oil particles consisting of nucleus of moisture contained in the fuel oil surrounded by rubbery or lacquer like material.

A further object of this invention is to provide a new apparatus for improving the quality of the low grade fuel oil, which includes a precipitating tank in which moisture and other impurities constituting heavy oil particles that have been crushed are separated by precipitation from th oil.

Still another object of this invention is to provide a novel apparatus for improving the quality of the low grade fuel oil, which is compact and light weight suitable for mounting on ships and vehicles but effective to continuously remove moisture and other impurities contained in said oil.

A still further object of this invention is to provide an apparatus for improving the quality of the low grade fuel oil having a precipitation tank which can prevent the impurities which have been separated by precipitationfrom said oil contained in said tank from being mixed again with said purified oil due to vibration of vehicles or ships. Thus this invention contemplates to provide a method of and apparatus for purifying low grade cheap fuel oil to suit for use asithe fuel for such fuel consumers as internal combustion engines, boilers and gas turbines without any detrimental effect, whereby to save the cost of fuel. While this invention can be applied to the purification of the fuel oils for internal combustion engines, boilers and gas turbines of any kind, it is most suitable for improving the quality of the fuel oil used on ships and vehicles.

One feature of this invention resides in a process of improving the quality of a low grade fuel oil comprising the steps of heating said oil to a temperature within a range from 60 C. to the boiling point of water, applying a mechanical force to said fuel oil under heat to destroy heavy oil particles contained in said fuel oil, and separating by precipitation moisture and other impurities comprising said oil particles from said fuel oil.

Another feature of this invention resides in an apparatus for improving the quality of low grade fuel oil comprising means to heat said fuel oil, an oil crusher which applies a mechanical force to said heated fuel oil to destroy heavy oil particles contained therein, and a precipitating tank wherein moisture and other impurities comprising said heavy oil particles which have been destroyed are separated by precipitation from said fuel oil by the difference in specific gravities.

For better understanding of the invention as well as other objects and further features thereof, reference is had to the following detailed description of the invention to be read in connection with the accompanying drawings, wherein:

FIG. 1 is a schematic representation of an apparatus for improving the quality of a low grade fuel oil, constructed according to this invention;

FIG. 2 is a plan view of an oil crusher used in FIG. 1;

FIG. 3 shows a vertical section of the oil crusher taken along the line 3-3 of FIG. 2 and viewed in the direction indicated by arrows;

FIG. 4 shows a vertical section of a precipitating tank utilized in this invention;

FIG. 5 is a cross-sectional view of the precipitating tank taken along the line 55 of FIG. 4 and viewed in the direction indicated by arrows; and

FIG. 6 shows a vertical section of a modified precipitating tank.

Referring now to FIG. 1 of the accompanying drawings, there is illustrated a schematic diagram of an apparatus which is to be mounted on ships to improve the quality of a low grade fuel oil for continuously supply purified oil to a diesel engine or a boiler on said ship.

The apparatus shown in FIG. 1 comprises an oil tank or reservoir 31, an oil feed pump 32, an oil heater 33, an oil crusher 34 and a precipitating tank 35. Low grade oil contained in the tank 31 is fed to the oil heater 33 by the oil feed pump 32 via

conduits

37 and 38. The oil heater 33 is provided with a heating coil which is supplied with steam from a steam boiler 40 mounted on the ship. The fuel oil from the oil heater is conveyed to the oil crusher 34, which will be described in more detail hereinunder, by a second oil feed pump 42 through

conduits

41 and 43. Emulsified heavy oil particles contained in the fuel oil are destroyed by the crusher and then sent via a conduit 44 to the precipitating tank 35 in which destroyed moisture, rubbery substance and other impurities which have been comprised in said heavy oil particles are separated by precipitation from the main body of the fuel oil.

As diagrammatically shown in FIG. 1, the precipitating tank 35 is provided with an internal heating coil connected to the boiler 40. The purified fuel oil is supplied from the precipitating tank 35 to a main engine, for example, a diesel engine 36 via a conduit 47, by means of a suitable pump, not shown, or by gravity. The purpose of the oil heater 33 is to heat the fuel oil to a temperature which is effective to bring the fuel oil to an unstable condition in which it can be more easily destroyed by the crushers, and the heating coil 45 serves to lower the viscosity of the fuel oil to aid precipitation of said impurities.

As has been described hereinbefore, many heavy oil particles are suspended in a residual still bottom fuel oil or a low grade fuel oil containing it in a large quantity. Each of these particles comprises a nucleus of moisture, a film of rubbery or lacquer-like substance covering said nucleus and copper, iron, vanadium or other metals, sulphur, salts or other impurities adhering to said film. Such heavy oil particles can not be separated by treating them with a centrifugal separator. However when heated they will become unstable and can be destroyed easily. Thus by merely heating them to a temperature below the boiling temperature of water, they can be destroyed by shearing, compressive or percussive force. Therefore in accordance with this invention the heavy oil particles contained in a low grade fuel oil are destroyed by subjecting them to the shearing, compression or percussion action afforded by said oil crusher. When these oil particles are destroyed, their films are broken to release particles of moisture contained therein. These particles of moisture are coagulated to have relatively large diameters by the agitating motion imparted to the fuel oil by the crusher. Since the specific gravity of water is larger than that of the fuel oil coagulated water particles will precipitate in the precipitating tank. Thus, the moisture content as well as the specific gravity of the upper portion of the fuel oil in the precipitating tank will be decreased, and the destroyed rubbery films and impurities attached thereon are also precipitated as a sludge, thus purifying the fuel oil. Purified fuel oil of improved quality can then be supplied to diesel engines, boilers or gas turbines and can be used therein without any deleterious effects mentioned above.

Heating of said fuel oil results in the instability of the heavy oil particles so that they can be easily destroyed, and when the temperature of the fuel oil is lowered formation of said sludge is increased. Therefore by repeating said cycle of operations, the quality and purity of the fuel oil can be greatly improved.

It was found by experiment that the amount of said sludge and other impurities was only 0.1 to 0.3%, by weight, based on the total weight of the fuel oil and that fuel oils that contain 0.3% of sludge and impurities are relatively rare, so that removal of these sludge and impurities does not mean any substantial loss of the fuel oil and the gain provided by improved quality is much larger than such loss. Also reduction of the moisture content to the minimum greatly enhances development of the total potential heat energy of the fuel oil and minimizes the amount of negative work done due to absorption of latent heat by the moisture.

As mentioned above while the temperature to which the fuel oil is heated should be lower than the boiling point of water, at temperatures slightly higher than room temperature destruction of the heavy oil particles are not effective as expected. There-fore it is necessary to heat the fuel oil to at least 60 C. and the more its temperature is close to the boiling point of water the easier the destruction of the heavy oil particles becomes.

When one cycle of operation involving destroy of the heavy oil particles and subsequent separation by precipitation of the components of said particles is not sufficient to purify the fuel oil to the desired extent, a plurality of oil crushers and precipitating tanks may be arranged in series between the oil tank and the fuel consumer such as a diesel engine and the precipitating tank closest to the diesel engine may be used as the daily service tank.

As shown in FIG. 1, a drain pipe 61 is connected to the bottom of the precipitating tank 35. The drain pipe 61 is connected to a water drain pipe 62 leading to a bilge well 66 and a sludge drain pipe 63 leading to a dirty oil tank 67, respectively through

valves

64 and 65. As water and sludge accumulate in the bottom of the precipitating tank 35, water constitutes the bottom layer since it is heavier than sludge, so that at first the valve 64 is opened to drain the water into the bilge well 66 and then the valve 65 is opened to drain the sludge into the dirty oil tank 67 together with dirty oil in the bottom portion of the precipitating tank 35. When water, sludge and dirty oil are completely drained the valve 65 is closed.

As shown in FIGS. 2 and 3, the oil crusher 34 comprises an upper casing 101, a lower casing 102, and a pair of relatively rotating disks 103 and 104. The upper casing is an inverted dish shape having a cylindrical boss 107 at its top having a vertical bore 108 therein. A vertical inlet pipe 109 is connected to the center of the stationary disk 103, the lower end of the inlet pipe 109 being connected to a shallow funnel like

recess

110 and 111a provided at the lower surface of the disk 103, while the upper end thereof being connected to the conduit 43 by a joint .137 in fluid tight relationship thereto. The stationary disk 103 is screwed at 109a to the upper casing 101 and a packing means 113 is provided in the bore 108 to surround the inlet pipe 109. A cup-shaped casing 102 is hermetically connected to the upper casing 101 by their

flanges

105 and 118, a packing 130 and a plurality of bolts 131 positively held by means of nuts 132. The rotary disk 104 is journaled on the upper surface of the casing 102 and is driven by an electric motor 136 con nected to the lower portion 129 of a shaft 126 which is hermetically sealed in the boss 120 by means of a packing means 127, said 'boss 120 being provided with a central vertical bore 121. As stated above the lower surface of the stationary disk 103 is slightly recessed so that the width of the gap 134 between the disks is about 1 to 3 mm. near the center but decreases toward the periphery. The conduit 44 lea-ding to the precipitating tank 35 is connected to an annular space 135 surrounding the periphery of the disks 103 and 104 by means of

flanges

123, 144 and a conduit 122. Heated low grade fuel oil supplied through the conduit 43 and the inlet pipe 109 enters into the center of the (gap 134 and then thrown radially by the rotary disk 104. While passing through the peripheral portions of the disks 103 and 104 which are in sliding contact the fuel oil is subjected to the crushing action to destroy the heavy oil particles contained therein. The heavy oil particles are also destroyed when they are thrown against the surrounding walls of the upper and lower casings by the centrifugal force. The fuel oil containing the destroyed heavy oil particles is discharged into the precipitating tank 35 where the released particles of moisture coagulate into larger droplets and precipitate together with the sludge as described above.

Since the oil crusher applies to the low grade fuel oil four forces of shear, compression, impact and acceleration, the heavy oil particles are destroyed positively. Moreover as this oil crusher discharges the treated oil by centrifugal force, the capacity of the feed pump 42 may be decreased, or this :pump may be omitted, if desired. Thus the oil crusher is especially suitable for use is diesel engines of large horsepower rating which consume relatively large quantities of low grade fuel oil containing high percentage of residual still bottom fuel oil and having relatively large viscosity. In addition, by providing suitable coarse surfaces on the opposing but not contacting inner faces of the disks 103 and 104, it is possible to impart turbulent motion to the treated oil, thus improving the efficiency of the crusher.

It should be understood that this invention is not limited to the use of the oil crusher of the type illustrated, but a centrifugal separator of any suitable design may be used provided that it can impart to the heavy oil particles enough shearing, compressing and/ or impact forces sufficient to destroy them.

Referring now to FIGS. 4 and 5, the precipitating tank 35 comprises a main body 202 of circular or square cross section, a cover 203 having said conduit 44, a conical bottom 206 and a receiver 209 for precipitating impurities. This receiver also has a funnel shape and telescoped over the lower end of the conical bottom 206. A conduit 47 leading to the fuel consumer opens in the lower portion of the main body 202 and a steam coil 45 is positioned beneath the conduit 47. As already described in connection with FIG. 1 the receiver is connected with the water drain pipe 62 and the sludge drain pipe 63 through

valves

64 and 65, respectively. It was found desirable to design the angle of subtend a of the conical bottom 206 to have a value less than 90.

In operation, the fuel oil treated by the oil crusher is discharged into the main body 202 wherein it is heated to a suitable temperature by said steam coil 45 to cause particles of moisture to coagulate and precipitate together with the sludge. The precipitated water and sludge will enter in the receiver through an opening 204 and will be accumulated therein with the layer of water at the bottom. Since the receiver 211 is not affected by the convection caused by the heating coil 45, there is no fear that precipitated impurities are again mixed with the body of fuel oil contained in the main body 202. As previously described, at first collected water is drained by opening the valve 64 and thereafter the sludge is drained by opening the value 65.

FIG. 6 shows a modified precipitating tank with a modified bottom portion from that shown in FIG. 4. For brevity, corresponding parts of FIG. 4 are designated by the same reference numerals and description thereof is omitted. In FIG. 6 the lower end of the conical portion 206 is connected to the funnel shaped receiver 211 via a relatively long tube 251. The operation of the precipitating tank shown in FIG. 6 is similar to that shown in FIG. 4, but with long connecting tube 251, it is more difficult for the collected impurities in the receiver 211 to flow back into the main body 202 upon rolling and pitching of the ship. If desired, the conical bottom 206 may be lined with smooth plate of stainless and the like in order to assure positive falling of the impurities having high viscosity and large adhesive force. Tests made on said B fuel by using the apparatus shown in FIGS. 2 through 5 showed that the purity and quality of the fuel were improved as shown in the following table.

It was found that the capacity of the precipitating tank may be made small, of the order of 2 to 3 tons for ships equipped with a diesel engine of 12,000 horsepower and where two precipitating tanks are cascaded with the last one serving also as the daily service tank, the capacity thereof may be made small enough to store fuel oil of the amount corresponding to 6 hours when they are used for a diesel engine which consumes 40 tons of fuel per 24 hours in order to develop 12,000 hoursepower. Even for the bunker C fuel oil which is available in New York and having a property similar to that of tar oil the capacity of the daily service tank was only 15 tons.

An embodiment of this invention comprising three oil crushers and three precipitating tanks connected in series was actually tested on two ships, each 10,000 shipping tons. More particularly, a low grade fuel oil of Venezuela origin having a viscosity of 1500 seconds when tested at 50 C. by a Redwood No. 1 viscosity meter and a specific gravity of 0.98 to 0.99 was used in the diesel engines of said two ships. Water ranging from to 423 liters was removed per 10 kiloliters of the fuel oil. Although the quantity of the sludge removed was not actually measured, substantial quantity thereof was removed. As the result, the specific gravity was decreased while at the same time the viscosity was also decreased to below 1000 seconds when measured at 50 C. by Redwood No.' 1 viscosity meter so that the oil became satisfactory fuel.

While the method and apparatus have been described with reference to specific embodiments thereof, it will be clear to those skilled in the art that this invention can be embodied in various ways within the scope and spirit of the invention as defined in the appended claims. For example, electric energy or exhaust gas of an internal engine or the like consuming the processed fuel oil may be used to heat the low grade fuel oil instead of steam. However, steam is preferred to purify the fuel oil to be used in steam electric power plants or on ship from the standpoint of cost down. Use of exhaust gas of the main engine is advantageous for small ships as fishing boats. In addition the number, capacity and configuration of the precipitating tank may be varied dependent upon the size of fuel consumers (fuel consumption) and type of the fuel oil used. When applied to ships, a cooling device may be provided for the receiver of the precipitated impurities in order to increase the viscosity of the sludge, thus positively preventing the reverse flow of the precipitated impurities. In the modification shown in FIGS. 6 and 7, it may be possible to utilize the connecting tube 251 as the receiver for the precipitated impurities whereby to omit the receiver 211. Where the apparatus of this invention is used in steam electric power plants such mechanism for preventing reverse flow may be omitted. Also the precipitating tank and the daily service tank are not required to be installed in the same place as in the conventional practice.

This invention can be advantageously used for various internal combustion engines or boilers installed on ships of various size, trains, automobiles, or in steam electric power stations and the like to continuously purify the fuel oil and to save the cost thereof.

What is claimed is:

1. In an apparatus for supplying improved fuel oil from low grade fuel oil wherein oil in an oil tank is pumped through an oil heater to an oil crusher and delivered to a precipitation tank, the water and impurities being separated therein and drained out by precipitation from the main body of fuel oil, while the improved fuel oil is supplied to utilization means, the improvement therein wherein said oil crusher comprises, first conduit means leading to said oil heater; upper and lower dishshaped outwardly flanged casing halves, fastened together at the flanges forming a crushing chamber; an upper stationary disc in said chamber with a slightly recessed center, said recess decreasing towards the periphery thereof; a vertically disposed inlet pipe leading from said conduit means to said upper stationary disc recessed center; a lower rotating disc in said chamber in crushing engagement with said upper stationary disc, including means to rotate said lower disc; a peripheral outlet from said upper and lower discs including second conduit means leading to the upper portion of said precipitation tank; and, said precipitation tank including an elongated main chamber with a conical bottom with a heating coil towards the lower portion of said main chamber and an outlet feed pipe to said utilization means from said main chamber.

2. In an apparatus as claimed in claim 1, said precipitation tank including a receiver for the impurities telescoped over the conical bottom thereof.

3. In an apparatus as claimed in claim 1, said precipitation tank including a long tube connected at the upper end to said conical bottom and at its lower end to a funnel shaped receiver for the impurities.

References Cited by the Examiner UNITED STATES PATENTS 2,862,876 12/1958 Winberg 208370 FOREIGN PATENTS 591,743 4/1925 France.

ALPHONSO D. SULLIVAN, Primary Examiner.

Claims

1. IN AN APPARATUS FOR SUPPLYING IMPROVED FUEL OIL FROM LOW GRADE FUEL OIL WHEREIN OIL IN AN OIL TANK IS PUMPED THROUGH AN OIL HEATER TO AN OIL CRUSHER AND DELIVERED TO A PRECIPITATION TANK, THE WATER AND IMPURITIES BEING SEPARATED THEREIN AND DRAINED OUT BY PRECIPITATION FROM THE MAIN BODY OF FUEL OIL, WHILE THE IMPROVED FUEL OIL IS SUPPLIED TO UTILIZATION MEANS, THE IMPROVEMENT THEREIN WHEREIN SAID OIL CRUSHER COMPRISES, FIRST CONDUIT MEANS LEADING TO SAID OIL HEATER; UPPER AND LOWER DISHSHAPED OUTWARDLY FLANGED CASING HALVES, FASTENED TOGETHER AT THE FLANGES FORMING A CRUSHING CHAMBER; AN UPPER STATIONARY DISC IN SAID CHAMBER WITH A SLIGHTLY RECESSED CENTER, SAID RECESS DECREADING TOWARDS THE PERIPHERY THEREOF; A VERTICALLY DISPOSED INLET PIPE LEADING FROM SAID CONDUIT MEANS TO SAID UPPER STATIONARY DISC RECESSED CENTER; A LOWER ROTATING DISC IN SAID CHAMBER IN CRUSHING ENGAGEMENT WITH SAID UPPER STATIONARY DISC, INCLUDING MEANS TO ROTATE SAID LOWER DISC; A PERIPHERAL OUTLET FROM SAID UPPER AND LOWER DISCS INCLUDING SECOND CONDUIT MEANS LEADING TO THE UPPER PORTION OF SAID PRECIPITATION TANK; AND, SAID PRECIPITATION TANK INCLUDING AN ELONGATED MAIN CHAMBER WITH A CONICAL BOTTOM WITH A HEATING COIL TOWARDS THE LOWER PORTION OF SAID MAIN CHAMBER AND AN OUTLET FEED PIPE TO SAID UTILIZATION MEANS FROM SAID MAIN CHAMBER.