Process and Apparatus for Mechanically Mixing Two Immiscible Liquids and One or More Other Substances

The present invention relates to a process and apparatus for the continuous mechanical mixing of disparate substances, such as oil, water, gas and fine particulate material, in successive steps and ultimately under shearing to produce evenly distributed mixtures of emulsions.

The mixtures produced with the present invention, typically fuel emulsions and colloid fuel in emulsion, have conventionally been produced using emulsification processes requiring an emulsifying agent with attendant chemical reactions and resulting impurities. The present invention, by way of contrast, discloses a process and apparatus which continuously and mechanically produce emulsions and suspensions more simply than, and as effectively as, the prior art while obviating the need for emulsifying agents.

The process and apparatus of the present invention are modifications of and improvements upon those described in U.S. Pat. Nos. 3,871,625 and 3,998,433 issued to one of the co-inventors of the present invention.

The present invention involves the creation in a suitable apparatus of a dual-layer liquid film, composed of upper and lower layers of immiscible liquids such as oil and water, into which film one or more substances in the gas, liquid, powder, or a combined phase are dispersed, and the resulting dispersed mixture is emulsified by mixing under shearing.

The mixing apparatus comprises an upper mixing section in the form of a cylindrical tank containing a concentrically disposed inverted truncated overflow cone, and a lower section in the form of a mixing or emulsifying chamber containing a mixing disk. A rotatable shaft extending concentrically through the two sections is driven at its lower end and has a mixing cone fixed to its upper end for rotation in the upper portion of the overflow cone. The dual-layer liquid film is created on the inner surface of the overflow cone by introducing a flow of two immiscible liquids, such as oil and water, into the cylindrical tank that overflows the upper rim of the overflow cone. An inlet pipe for the gas, liquid, powder, or combinations to be dispersed into the film is disposed concentrically above the mixing cone and may be adapted to conduct a swirling flow of, for example when producing a fuel, a gas, such as air, premixed with a fine powder or particulate matter, such as coal, for impingement upon the rotating surface of the mixing cone. The impinging material is centrifugally dispersed by the mixing cone into the dual-layer liquid film. The film dispersed with the gas and particulate solids then passes through the lower open end of the overflow cone into the mixing compartment. The mixing disk in the compartment is mounted for rotation on the central portion of the rotary shaft and has circular arrays of upstanding pins on its upper surface which cooperate with similar arrays of pins on the bottom of the stationary cylindrical tank to produce a shearing action on the incoming mixture to mix and emulsify it. Scraper blades are provided on the lower surface of the mixing disk to further mix and move the resulting emulsion out through an exhaust or delivery port in the side of the mixing compartment. An additional oil inlet may be provided in the mixing compartment to add further oil to the mixture to create a two-step emulsification process between the oil and water.

It is accordingly an object of the present invention to provide a process and apparatus for mechanically mixing two immiscible liquids and one or more other substances.

It is a further object of the present invention to provide a process and apparatus for the continuous mechanical mixing of disparate substances such as oil, water, gas and fine particulate matter.

It is a particular object of the present invention to provide a process and apparatus for producing emulsion fuel and colloid fuel in emulsion without the use of an emulsifying agent.

Other objects, features and advantages of the present invention will be readily appreciated by those skilled in the art upon consideration of the following detailed description taken in connection with the accompanying drawings.

FIG. 1 is a sectional view in elevation of a continuous flow jet mixer in accordance with the present invention.

FIG. 2 is a sectional view taken along the lines II--II in FIG. 1.

FIG. 3 is a sectional view taken along the lines III--III in FIG. 1.

A mixing apparatus in accordance with the present invention is shown in FIG. 1. The upper section of the mixing apparatus comprises an upstanding cylindrical vessel of tank 8 with upper and lower concentrically apertured end walls 8a, 8b and containing a concentrically arranged inverted truncated overflow cone 9. A feed pipe 4 extends through the aperture or opening in the upper wall 8a of tank 8 into the upper portion of overflow cone 9 and acts as a flow chute or inlet for the inflow of gas, liquid, powder or other material in a downward jet. Directly beneath pipe 4 at a level below the upper edge 9a of the overflow cone 9 is a spreader cone 10 secured to the upper end of an axially disposed rotary shaft 20. Shaft 20 extends through the lower section of the apparatus and has a pulley 19 on its lower end by means of which it is driven in rotation through a belt 18 and pulley 17 connected to a drive motor M mounted on the mixing apparatus support frame 21. The opening in the lower wall 8b of tank 8 communicates the lower portion of overflow cone 9 with the lower section of the apparatus which comprises a cylindrical mixing compartment 16.

The mixing compartment 16 contains a mixing disk 11 which is mounted for rotation with the shaft 20 and has a larger diameter than the opening in the lower wall 8b of tank 8, which opening is disposed immediately above it. A plurality of short pins 12 are fixed on the upper surface of the mixing disk 11 in circular arrays and project upwardly into the space between the disk and the lower wall 8b of the tank 8. A plurality of similar short pins 13 are fixed on the lower wall 8b of tank 8 in circular arrays at different radial spacings from the pins 12 (see FIG. 2) and project downwardly from the lower wall 8b to substantially intermesh with the pins 12 in the space above the upper surface of mixing disk 11. Scraper blades 14 and 15 are fixed circumferentially to the underside of the mixing disk 11 for rotation therewith and the mixing compartment 16 is provided with an exhaust or delivery port 7.

In operation, the inlet pipe 4 conducts a flow of one or more substances to be mixed downwardly into the interior of tank 8, which flow impinges upon the upper surface of spreader cone 10. The impinging substance or material is centrifugally dispersed by the rotating cone 10 into the liquid film flowing downwardly on the interior surface of overflow cone 9. The liquid film with the other material dispersed therein then passes into the mixing compartment 16 for subsequent mixing by the shearing action of the mixing disk 11 and its cooperating pin structure. The resulting mixture is then passed, with the help of scraper blades 14 and 15, out through the exhaust or delivery port 7.

It will be seen that the above-described structure and operation incorporates many essential features of the mixing apparatuses disclosed in U.S. Pat. Nos. 3,871,625 and 3,998,433 issued to one of the co-inventors of the present invention.

Unlike the previously-disclosed mixing apparatuses, however, the cylindrical tank 8 of the present invention is provided with two inlets 1 and 2 to permit the continuous feeding of two different immiscible liquids, such as oil and water, each at a constant feed rate into the chamber in the interior of tank 8. Inlets 1 and 2 are preferably tangential so that the two liquids, flowing into the tank chamber tangentially, circulate about the outer surface of the inverted overflow cone 9 and rise in level to the upper edge or rim 9a of cone 9. Upon reaching the level of the cone rim, the liquids flow over it and move over the inner surface of the cone 9 in a descending flow creating a continuous liquid film on the inner surface which passes downwardly through the central opening at the base of the cone 9. The form and thickness of the liquid film will be a function of the qualities of the materials to be mixed and can be determined by the skilled artisan using known factors. Similarly, the respective flow rates may be controlled to maintain a continuous film-like flow of the liquids. As the liquids are immiscible, with proper control the film may be formed of two layers. If, for example, oil is fed through inlet 1 and water through inlet 2 at the proper rates, the liquid film will comprise two layers, a layer of water against the inner surface of cone 9, and a layer of oil over the water layer. For best results, individual metering pumps (1a, 2a) are used to continuously feed the oil or other immiscible liquid through inlet 1 and to feed the water through inlet 2. It will be seen that in order to create and sustain a continuous dual-layer liquid film on the internal surface of the overflow cone 9, the tank 8 is preferably first filled with water to near the rim of the overflow cone 9 prior to the subsequent simultaneous operation of the metering pumps for the water and oil.

Further, in accordance with the present invention, the feed pipe 4 is provided with a plurality of inlets, for example a gas inlet pipe 5, and an inlet pipe 6 for the introduction of particulate matter, typically fine solid powders such as pulverized coal, stabilizer, or the like. The powders may be continuously fed into the induced gas stream, typically air, from inlet 5. The gas-powder mixture will accordingly be fed to the spreader cone 10 through feed chute 4 for subsequent dispersion and mixing into the liquid film flowing downwardly on the inner surface of the overflow cone 9.

The inlet pipe 5 for introducing the gas or air into feed pipe 4 is preferably connected tangentially to pipe 4, as shown in FIG. 3, to provide a circular flow of gas which will tend to mix with the powder or particulate matter introduced from inlet pipe 6. The downward flowing mixture of gas and particles impinges upon the surface of the rotating spreader cone 10 which will impart a centrifugal force to the mixture that may already possess substantial energy by reason of being discharged downwardly in a circulating stream through inlet 4. The kinetic energy of the whirling powder particles aids in their intermixture with and dissolving into the dual-layer liquid film. As the mixture of liquid, gas, and solids descends onto the rotating mixing disk 11, centrifugal force expels the mixture through the pin arrays, 12 and 13, effecting a second phase of intermixture and dissolving. Also in the process the mixture is emulsified by the shearing action of the cooperating pins. The speed of rotation of shaft 20, and thereby of cone 10 and disk 11, may be adjusted to provide optimum mixing and emulsifying actions for the various substances used with the process, as will be understood by those skilled in the art.

A further feature of the present invention involves the incorporation of a secondary oil inlet 3 in the mixing compartment 16 for feeding further oil to the emulsion in the chamber of the mixing compartment. The oil or other immiscible liquid is preferably divided into two supplies to further the emulsification so that a second oil stream is supplied through inlet 3 into the mixing chamber 16. The feed rates of the oil in the two supplies depends on the feed rate of the water, desired emulsion type and other physical and chemical factors as will be familiar to the artisan. With this arrangement the first supply of oil through inlet 1 is emulsified with the water, gas and solids before being mixed with the second supply of oil through inlet 3 and a more stable emulsion is ultimately produced. As a result, the apparatus is able to continuously and mechanically produce an emulsion or emulsified particulate suspension very simply and effectively and without the use of an emulsifying agent, which has been the conventional means for emulsification in the prior art. In the mixing compartment 16 the mixture of liquid, gas and solids is subjected to a shearing force caused by the relative movement of the pins 12 and 13, and the mixture is discharged from the chamber through outlet or delivery port 7 by the action of the scrapers 14 and 15.

Using the present mixing apparatus an extremely stable emulsion comprising 70 parts oil and 30 parts water by weight with suspended droplets of less than 3 micron diameter has been continuously produced with no emulsifying agent by feeding 30 parts of water through inlet 2 at the rate of 150 kg/hr and appropriate portions of oil through inlets 1 and 3 at the respective rates of 135 and 215 kg/hr. This emulsion remained stable for several months at room temperature.

Using the mixing apparatus of the present invention a stabilized colloid fuel in emulsion has been continuously produced by feeding 40 parts of oil through inlet 1 at the rate of 180 kg/hr, 20 parts of water through inlet 2 at 90 kg/hr, and 40 parts of pulverized coal through inlet 6 at 180 kg/hr. The coal was continuously dispered into the airflow from inlet 5, which dispersion was subsequently dispersed into the dual-layer liquid film of oil and water. This emulsion also remained stable for several months at room temperature.

Thus, the apparatus and process of the present invention facilitates the mixing and emulsifying of suitable substances in the liquid, gaseous and particulate phases to produce, in appropriate cases, emulsion fuels, or colloid fuels in water-oil type emulsions by using mechanical means obviating the use of emulsifying agents.