Fluid filter separator and method

A filter separator and method, including an annular microfilter and a separation chamber within the microfilter including a plurality of mixing blades circulating fluid upwardly and downward within the chamber. When the apparatus is used to purify syngas, adherent metal oxide particles are circulated in the chamber to adsorb waste oxides. The apparatus is purged by injecting hot CO2 free gas into the chamber through the filter and the filter pores may be expanded during purging.

FIELD OF THE INVENTION

This invention relates to a fluid filter separator, mixer and method particularly, but not exclusively for purifying syngas and other gases and liquids.

BACKGROUND OF THE INVENTION

Municipal, industrial and agricultural wastes and biosolids are potentially a rich source of carbon for power generation, as well as a primary source for the reformed synthesis gas (syngas), a mixture of carbon monoxide and hydrogen. These resources are discharge limit regulated. Such solids represent a significant percentage of a municipality's waste management budget which may be offset by converting these waste solids to energy. The demand for renewable and alternative energy sources is a growing industry.

Carbon-based dry solids are currently convertible by gasification and turbo-electric power generation at a rate of three pounds per kilowatt (kW) at approximately 30% efficiency. However, if these gasifier fuel gases or syngas were to be used in a fuel cell operating at high temperatures, the efficiencies approximate 70%. The barriers to bringing a high temperature solid oxide fuel cell (SOFC) to market include the high cost of stacked ceramic discs, their interconnects and exotic elements, which are subject to corrosion from CO2/H2O formed in the oxidation process. Further, the syngas or fuel gas (CO/H2) source must be free of contaminating nitrogen and sulfur oxides which requires a fuel gas scrubber preceding the fuel cell. The method and apparatus of this invention includes a separator filter for fuel gas or syngas.

SUMMARY OF THE INVENTION

As set forth above, the separator filter of this invention may be utilized, for example, to purify syngas feed for the modified Fischer-Tropsch synthesis process or synthesis described in a later embodiment and application, which is a catalyzed chemical reaction in which synthesis gas (syngas), a mixture of carbon monoxide and hydrogen, is converted into hydrocarbons in various forms. The most common catalysts are based on iron and cobalt, although nickel and ruthenium have also been used. The principle purpose of this process is to produce a synthetic petroleum substitute, typically from coal, natural gas or biomass, for use as a synthetic lubrication oil or as a synthetic fuel. This synthetic fuel may then be used to generate hydrocarbons including fuels for engines. The most important reactions using syngas can be described by the chemical equations of the form:
(2n+1)H2+nCO→CnH(2n+2)+nH2O
wherein small “n” is a positive integer. As would be understood, the simplest form of this equation results in a formation of methane. However, octane and other fuels may also be generated.

The fluid separator filter of this invention includes an inlet receiving fluids under pressure, including waste fluids, and waste particulates. The apparatus includes an annular filtration chamber receiving fluid and waste particulates from the inlet. The apparatus further includes an annular microfilter defining an inner wall of the annular filtration chamber filtering particulates from the fluid and a fluid separation chamber located within the annular microfilter receiving filtered fluid from the annular microfilter including fine adsorbent particles and a plurality of radial mixing blades continuously circulating the fine adsorbent particles and filtered fluid vertically upwardly and downwardly adsorbing and removing waste fluid from the filtered fluid, and an outlet removing the filtered selected fluid from the fluid separation chamber.

In one preferred embodiment, the fluid separator filter is a gas separator which may be utilized, for example, to purify syngas. As will be understood by those skilled in this art, a mixture of carbon monoxide and hydrogen is sometimes referred to as fuel gas to define the ultimate use of the gas. However, as used herein, the term “syngas” includes primarily a mixture of carbon monoxide and hydrogen and includes fuel gas. However, as discussed further below, the separator filter of this invention may also be used to filter, separate and purify various gases and liquids. In the disclosed embodiment, where the gas separator filter is utilized to purify syngas, the suspended metal oxide particles may be fine particles of calcium oxide, such as cement kiln dust, which is relatively inexpensive and efficient. Further, in the disclosed embodiment of the gas separator filter, the radial mixing blades are fixed to a rotating central shaft and each blade includes a radial central portion extending perpendicular to the central shaft, a first side portion adjacent the central shaft extending radially and circumferentially from the central shaft at an obtuse angle to the radial central portion circulating fluid upwardly adjacent the central shaft and a second side portion extending from an opposite side of the central radial portion, radially spaced from the first side portion, adjacent a distal end of a central portion extending radially and circumferentially at an obtuse angle to the radial central portion, circulating fluid downwardly adjacent a distal end of the radial mixing blades. This configuration of the radial blades is very efficient to circulate the suspended adsorbent particles upwardly adjacent the central axis of the fluid separation chamber and downwardly adjacent the distal ends of the radial mixing blades, removing unwanted fluids.

In the disclosed embodiment, the central shaft supporting the radial mixing blades is hollow and gas may be directed through the hollow shaft into the mixing chamber, such as heated nitrogen to heat the metal oxide particles sufficiently to desorb the waste fluid periodically for removal.

In the disclosed embodiment, the annular microfilter is a continuous flexible resilient helical coil having a regular sinusoidal shape in the direction of the helix, including flat top and bottom surfaces having circumferentially space radial notches defining filter micropores having a diameter less than a particle size of the suspended waste particulates. Further, in the disclosed embodiment of the separator filter, the apparatus includes an actuator motor connected to the continuous helical coil rotating at least one coil relative to a second coil into an outer registry to close the loop-shaped filter pores between adjacent coils during filtering, such that the circumferentially spaced radial notches or laser etched micropores are the only pores through the filter during filtering of gases. However, the actuator motor may also be operated to rotate the coils out of registry during purging and cleaning of the filter.

The method of purifying syngas consisting essentially of carbon monoxide and hydrogen, of this invention thus includes filtering an inlet gas, including syngas, waste gaseous oxides of sulfur, nitrogen or carbon and suspended fine particulates through an annular microfilter having a pore size less than the particle size of the fine particulates. The method then includes continuously circulating the filtered gas and fine particles of an adsorbent metal oxide upwardly and downwardly in a gas separation chamber located within the annular microfilter, wherein the metal oxide particles adsorb waste gas, including gaseous oxides of sulfur, nitrogen or carbon. The method then includes removing the purified and filtered syngas from the separation chamber. The method of this invention also includes periodically heating the fine particles of adsorbent metal oxide in the gas separation chamber to the calcination temperature to desorb the waste gases from the fine metal oxide particulates. As set forth above, in the disclosed embodiment of the apparatus of this invention, the apparatus includes a plurality of radial mixing blades in the separation chamber, wherein the method of this invention includes rotating the blades to circulate the gas and fine particles of metal oxide upwardly adjacent a rotational axis of the radial mixing blades and downwardly adjacent the annular microfilter. Further, in the disclosed embodiment of the apparatus of this invention, the annular microfilter is a continuous helical coil including a plurality of helical coils each having a regular sinusoidal shape in a direction of the helix, wherein the method includes periodically spacing the coils axially and backwashing the microfilter.

As will be understood by those skilled in this art, various modifications may be made to the fluid separator filter apparatus and method of this invention within the purview of the appended claims. The following description of the preferred embodiments of the filter separator apparatus, mixing device and method disclosed in the appended drawings are for illustrative purposes only and do not limit the scope of this invention except as set forth in the appended claims. Further advantages and meritorious features of the filter separator apparatus of this invention will be more fully understood from the following description of the preferred embodiments, the appended claims and the drawings, a brief description of which follows.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As set forth above, the embodiments of the filter apparatus and method of this invention disclosed in the following description of the preferred embodiments are for illustrative purposes only and various modifications may be made to such embodiments within the purview of the appended claims. Referring to the figures, wherein like numerals indicate like or corresponding parts throughout the several views, one embodiment of a filter apparatus for filtering a fluid is generally disclosed at10inFIGS. 1 to 6. In the Figures, it is understood that the filter apparatus10and method of this invention are capable of filtering both liquids and gases as the fluid. However, the embodiment of the filter apparatus10of the subject invention is more preferably used to filter fluids having solid particles including, without limitation, slurries of biological or organic waste, including oils. As such, the filter apparatus10may be used in combination with other devices, including ion exchange or chelation affinity apparatus or a filter press as discussed further below.

FIGS. 1 to 6illustrate one embodiment of the filter assembly10of this invention which may be utilized to perform the methods of filtration described herein. The filter assembly10shown inFIGS. 1 and 2includes an annular filter element12including a continuous generally cylindrical helical coil having a plurality of circular interconnected helical coils14as best shown inFIG. 3, wherein each generally circular helical coil has a plurality of regular sinusoidal wave forms or shapes including circumferentially spaced peaks and troughs as shown inFIG. 3. The peaks “p” and troughs “t” of adjacent coils4are in contact to provide enlarged “loop-shaped” or eyelet-shaped filter pores between adjacent coils as shown inFIG. 4, or the peaks “p” and troughs “t” of adjacent coils14may be aligned as shown for example inFIG. 6as described below.

The filter assembly10shown inFIGS. 1 and 2includes a lower housing18having an inlet20and an outlet22for receiving a fluid stream to be filtered, such as a waste gas or liquid stream as described above. The filter assembly10further includes a cover24which is supported on the lower housing member18by circumferentially spaced inner and outer retention posts26and28, respectively. A filtration chamber30is defined between the lower housing member18and the cover24by a cylindrical housing wall32. Thus a fluid stream received through inlet20is received under pressure in the filtration chamber30for filtration by the filter element12. The fluid stream including contaminants is then received through the filter pores or the radial grooves as described below through the filter element12into the axial center of the filter element12and the filtrated fluid is then discharged through the outlet22. As described above, the particles, molecules or material removed by the filter element are removed by backwashing as further described below.

This embodiment of the filter assembly10shown inFIGS. 1 and 2further includes a pneumatic cylinder34attached to and supported on the cover24of the housing having an air inlet36and an air outlet38. A piston assembly40is reciprocally supported in the pneumatic cylinder or chamber34including a piston head42having an O-ring44, such that the piston assembly40is sealingly supported within the pneumatic cylinder34. The piston assembly40has a stroke “S” as shown inFIG. 1. Pneumatic pressure supplied through air inlet36of the pneumatic cylinder34will thus drive the piston assembly40downwardly from the position shown inFIG. 1to the position shown inFIG. 2as described in more detail hereinbelow.

In this disclosed embodiment, the filter assembly10further includes a drive assembly engaging the helical coil filter element12moving adjacent coils14, thereby modifying and controlling a volume of the loop-shaped filter pores between adjacent coils as now described. In this disclosed embodiment, the filter assembly10includes a stepper motor46attached to and supported by the upper end of the piston assembly40as shown inFIGS. 1 and 2. As will be understood by those skilled in this art, a stepper motor is a brushless, synchronous electric motor that can divide a full rotation into a large number of steps. When commutated electronically, the motor's position can be controlled precisely, without any feedback mechanism. Although a stepper motor has several advantages for this application, any other type of rotary drive may also be utilized. The driveshaft48of the stepper motor46is connected in the disclosed embodiment to an upper end of the cylindrical helical filter element12to relatively rotate the filter coils to accurately control the volume of the loop-shaped filter pores60as described below. The driveshaft48of the stepper motor46in the disclosed embodiment is connected to a coupling50as shown inFIGS. 1 and 2. A shaft52connected to the coupling50is connected to a clamp assembly connected to the upper end of the filter element12. The lower end of the filter element12is rigidly connected to the lower housing member18such that, upon rotation of the clamp assembly54by the stepper motor46, the coils14of the filter element12are rotated relative to each other as described below.

In the first disclosed embodiment, the circular interconnected coils14of the filter element12are initially aligned crest or peak “p” to trough “t” as shown inFIG. 4with the filter pores or openings60enlarged to their maximum. Alternatively, it would also be possible to initially align the coils peak to peak and trough to trough. It is important to understand, however, that the width or amplitude of the sinusoidal wave or curve has been greatly exaggerated inFIGS. 1,3and4for a better understanding of the filter assembly of this invention and the method of filtration. As set forth above, the volume of the openings or loop-shaped filter pores60of the filter element12in the filter apparatus of this invention may be accurately controlled to filter different fluids. First, the piston assembly40may simply be extended to compress the filter element, thereby reducing the size or volume of the filter pores60by supplying air under pressure through the inlet36of the pneumatic cylinder34. However, in one preferred embodiment, the drive46rotates at least one of the coils14relative to the remainder of the coils, thereby relatively sliding the opposed flat top and bottom surfaces of adjacent coils relative to each other into and out of registry, thereby accurately controlling the volume of the loop-shaped pores60. Further, because the filter element12is formed of a stiff resilient metal, such as stainless steel, the loop-shaped filter pores60are all modified simultaneously, such that all filter pores have essentially the same volume, which is important for accurate control.

As best shown inFIG. 5, rotation of the upper coil of the continuous cylindrical helical coil filter element12, by rotation of the driveshaft48of the stepper motor46causes the peaks “p” of adjacent coils to rotatably slide on the flat upper and lower surfaces62relative to the remaining coils, reducing or expanding the apertures or filter pores60. Finally, as shown inFIG. 6, the sinusoidal-shaped coils may be moved or rotated into full registry, such that the peaks “p” and troughs “t” are fully aligned. Again, however, the spacing between adjacent coils14has been exaggerated inFIG. 6for clarity. In fact, the adjacent coils may be in full contact, such that the filter pores60between adjacent filter coils is reduced to essentially zero. However, in the disclosed embodiment, at least one of the opposed flat surfaces62of the filter coils14includes circumferentially spaced radial grooves64, which may be formed by laser etching permitting the flow of fluids through the filter element when the filter pores60between adjacent coils are reduced to substantially zero. Thus the radial grooves or notches64significantly increase the applications for the filter assembly10of this invention.

Having described the embodiment of the filter assembly10of this invention as shown inFIGS. 1 to 6, the operation of the filter assembly10may now be described. In one embodiment of the filter apparatus10of this invention, the filter element12is a continuous substantially cylindrical resilient helical coil having a regular sinusoidal shape including regular peaks “p” and troughs “t” as described above. The filter element may be formed of stainless steel, such as 316 stainless steel, which is stiff and resilient. However, the helical coil filter element may also be formed of a Hastaloy or other steel or even plastic. Another advantage of stainless steel is corrosion resistance. The coil preferably is formed from flat metal stock having flat top and bottom surfaces62, such that the flat surfaces of adjacent coils will slide against each other during rotation as best shown inFIGS. 4 to 6. A suitable thickness between the flat top and bottom surfaces62is 0.4 to 2 mm having a width of between 3 and 6 mm. The preferred number of sinusoidal waves of each coil will depend upon the application. However, it has been found that between 3 and 10 sinusoidal curves or waves for each coil14will be very suitable for most applications. Further, the “width” of the loop-shaped openings or filter pores will also depend upon the application, but it has been found that filter pores having a maximum width of about 0.5 mm is suitable for most applications. Finally, the depth of the radial grooves64, which may be formed by laser etching, is preferably between about 0.1 to 10 microns. However, in the embodiment of the organic filtration apparatus210described below, the radial grooves or laser etched micropores may have a diameter in the nanometer range.

The filter assembly10is thus operated by adjusting the apertures or loop-shaped filter pores60to the desired volume for filtration depending upon the fluid to be filtered by either extending the shaft52using pneumatic pressure through inlet port36, driving the piston assembly40downwardly inFIG. 1to compress the coils against each other, thereby reducing the volume of the filter pores60or by retracting the shaft52using pneumatic port38to increase the volume of the filter pores. However, in one preferred embodiment, the stepper motor46may be simultaneously rotated to bring the peaks “p” and troughs “t” into and out of registry as shown, for example, inFIG. 5. As described above, rotation of the upper coil will simultaneously rotate all coils relative to the bottom coil because the filter element is formed of a stiff resilient material, such as 316 stainless steel. The coils may be rotated into full registry, as shown inFIG. 6, wherein the filter pores are reduced to substantially zero and wherein the fluid flow is only through the radial grooves64. The fluid to be filtered is then received through the housing inlet20into the filter chamber30and flows through the filter element12as shown inFIG. 2. As will be understood, the filter apparatus may be used to filter almost any fluid depending upon the filter pore size including, for example, residential, industrial and agricultural waste and sludges to produce, for example, potable water from waste and may be used for the clarification and refinement of waste oil from waste water-oil mixtures, etc. Upon completion of the filtering process or when the filter element12becomes clogged with the particles or media suspended in the fluid, the filter element12may be easily flushed by opening the filter pores60as shown inFIG. 1and flushing solution is then received through the outlet22and flushed through the filter element12. In the disclosed embodiment, backwashing may be facilitated by rotating the stepper motor in the opposite direction from the direction used to compress the coils14of the filter coil while maintaining the clamp assembly54in the extended position as shown inFIG. 2. Then, upon completion of the filtering process, the filter element is “opened” by simply retracting the clamp54to the open position shown inFIG. 1which can be accomplished in a second or two.

The second embodiment of the filter apparatus110of this invention illustrated inFIGS. 7 to 12may be characterized as a centrifugal filter apparatus or more specifically a dual-chambered centrifugal and compressive filtration apparatus for separating waste solids from fluids including, for example, waste solids in oils, water and gas. The elements of the centrifugal filter apparatus110are numbered where appropriate in the same sequence as the filter apparatus10described above, but in the 100 series to reduce the requirement for a detailed description of like components. The disclosed embodiment of the filter apparatus110includes a central annular filter element112which, in the disclosed embodiment, is a continuous flexible resilient generally cylindrical helical coil including a plurality of interconnected generally circular helical coils114as described above with reference to the filler element12. However, the centrifugal filter apparatus of this invention may alternatively include any conventional annular generally cylindrical filter element although the helical filter element112is preferred in many applications.

The filter apparatus110includes a lower housing member118and a base member119, an inlet120, a supernatant outlet121and a solids outlet122through base member119. The disclosed embodiment of the filter apparatus110further includes upper housing members123,124and125, which are retained to the lower housing member118by circumferentially spaced retention posts. This disclosed embodiment includes a first annular filtration chamber130surrounding the annular filter element112and a second filtration chamber131within the annular filter element112as further described below. The first filtration chamber130is defined by the cylindrical housing wall132defining a cylindrical inner surface133. In the centrifugal filter apparatus110of this invention, the internal wall133of the canister housing is preferably cylindrical to accommodate the centrifugal fins described below.

The disclosed embodiment of the filter apparatus110includes a first pneumatic port136adapted to compress the helical filter element112and a second pneumatic port138adapted to expand the helical filter element as described below. The apparatus further includes a pneumatic cylinder134receiving a piston140actuated by pneumatic pressure through the pneumatic ports136and138as described below. The disclosed embodiment of the filter apparatus110further includes a motor142, such as a stepper motor described above, for rotating one or more of the helical coils114relative to a remainder of the helical coils into and out of registry to finely adjust the eyelet-shaped filter pores160between adjacent helical coils114as also described above. In this embodiment, the motor142includes a drive shaft assembly144connected to a drive gear146. The drive gear146rotatably engages a driven gear148which is connected to a tubular driven shaft150connected to the upper helical coil114as described above with regard to the filter apparatus10.

In one preferred embodiment, the helical filter element112includes both a first filter drive compressing or expanding the helical filter element and a second drive rotating one or more of the helical coils114into and out of registry for very accurately controlling the volume of the filter pores116between adjacent helical coils114. In the disclosed embodiment, the first drive is a pneumatic drive, wherein pneumatic pressure received through inlet pneumatic port136drives the piston140downwardly inFIG. 7to compress the helical filter element112. Alternatively, the first drive may be hydraulic. An advantage of a pneumatic filter drive is that the compression on the helical filter element112may be released quickly during purging. Detailed or accurate control of the volume of the filter pores116in this embodiment is controlled by the second drive which, in the disclosed embodiment, is a stepper motor142. The stepper motor142rotates the drive shaft144, which rotates the drive gear146. The drive gear146rotates the driven gear148and the tubular drive shaft150connected to the upper end of the helical filter element112to rotate at least one of the helical coils114relative to a remainder of the helical coils, thereby rotating the helical coils into and out of registry as described above.FIG. 8illustrates the filter apparatus110after closing the filter pores160using the pneumatic adjustment mechanism and rotating the helical filter coils114into registry as described above with reference toFIG. 2.

In the disclosed embodiment of the centrifugal filter apparatus110of this invention, the apparatus includes external rotating centrifugal radial fins162shown inFIGS. 7 and 8and internal rotating centrifugal radial fins164shown inFIGS. 9 and 11. As described below, the external and internal centrifugal radial fins162and164, respectively, cooperate during filtration and purging of the helical filter element112to significantly improve filtering by the filtering apparatus of this invention. In the disclosed embodiment of the centrifugal filter apparatus110, the external centrifugal radial fins162are rigidly supported by upper bracket members166and lower bracket members168by bolts170as shown inFIGS. 7 and 8. The upper bracket member166is also rigidly connected by bolts170to the upper spindle172and the lower bracket members are rigidly connected to the lower spindle member174by bolts170. The upper spindle172is rotatably driven by electric motor176. The drive shaft178of the electric motor is fixed to an external drive gear180, which drives a driven gear182fixed to the upper spindle172. Thus, the electric motor176rotatably drives the upper spindle172which rotates the external centrifugal radial fins162within the outer or first filtration chamber130.

In the disclosed embodiment of the centrifugal filter apparatus110, the external centrifugal radial fins162are also driven by pneumatic pressure as also shown inFIG. 9. As shown inFIG. 9, the upper housing member123, which serves as a cover for the filter canister, includes two pneumatic channels184and186, which have a circular cross-section as shown inFIGS. 7 and 8. Air under pressure is injected into the pneumatic channels184and186in opposite directions as shown by the arrows188to turn the turbine blade190at the outer surface of the spindle172as shown at190inFIG. 7. Thus, pneumatic pressure injected through pneumatic ports184and186rotate the external centrifugal radial fins162. In the disclosed embodiment, the lower spindle174is also pneumatically driven. The lower spindle includes pneumatic channels192,194which drive a turbine196as described above with regard to the pneumatic channels184,186and turbine190.

As will be understood from the above description of the drives for the external centrifugal radial fins162, the fins may be rotatably driven by the motor176or pneumatic pressure injected through pneumatic ports136and138in the upper spindle172and through ports192and194through the lower spindle174. As will be understood by those skilled in this art, the motor drive and the pneumatic drives may be used in combination depending upon the type of motor176or independently depending upon the conditions. For example, where the waste being filtered by the centrifugal filter apparatus110must be continuous, the pneumatic drive may be used as a back-up in the event of an electrical power failure.

In the disclosed embodiment of the centrifugal filter apparatus110of this invention, the internal centrifugal radial fins164as shown inFIGS. 9 and 11, are rotatably driven by electric motor198shown inFIGS. 7 and 8. The motor198is supported in a housing200. The drive shaft of the motor198rotatably drives rod202and the internal centrifugal radial fins164are mounted on the rod202as shown inFIG. 9. Thus, the motor198rotates the internal centrifugal radial fins164independently of the external centrifugal radial fins162.

In the disclosed embodiment of the centrifugal filter apparatus110, both the external and internal centrifugal radial fins162and164, respectively, are canted relative to the axis of rotation of the fins to drive liquid in a predetermined direction. In the disclosed embodiment, the external centrifugal radial fins162are pitched or tilted relative to the axis of rotation as best shown inFIG. 12. As will be understood by those skilled in this art, the external centrifugal radial fins162may be formed in a spiral or pitch prior to assembly in the filter apparatus110or the fins may be planar and pitched during assembly by securing the ends into the upper and lower bracket members166and168as shown inFIG. 12. The internal centrifugal radial fins162in the disclosed embodiment are spiral and secured by welding, brazing, or other methods of attachment to the202in a spiral around the rod as shown inFIG. 11. As used herein, the term “canted” includes any tilt or angle, including spiral, generating a radial or axial force on the liquid in a desired direction to improve filtering. To further increase the rotational force on the liquid, the liquid waste is directed through the inlet120tangentially into the first annular filtration chamber130as also shown inFIGS. 9 and 10. The liquid waste is injected under pressure tangentially through the inlet port120into a spiral passage and exits through outlet204into the annual first filtration chamber130generating an additional centrifugal force.

Having described the basic components of the centrifugal filter apparatus110, the method of filtration by the filter apparatus110will now be understood by those skilled in this art. The liquid to be filtered is injected under pressure into the inlet120and the liquid is then directed through the passage in the upper housing member123into the annular first filtration chamber130, tangentially in the disclosed embodiment. The liquid to be filtered is very rapidly rotated in the annular first filtration chamber130by rotation of the external centrifugal radial fins162, driving heavier or denser material in the filtrate radially outwardly under centrifugal force against the cylindrical inner surface133of the housing wall132. The solids are also driven downwardly against the cylindrical inner surface133to the solids outlet122adjacent the cylindrical inner wall133. During filtration, the internal centrifugal radial fins164are rotated to drive supernatant liquid downwardly toward the outlet121, drawing liquid through the helical filter element112into the second filtration chamber131, providing a final filter for the liquid waste. As will be understood from the above description of the filtration apparatus10inFIGS. 1 to 6, the filter pores60between adjacent coils may be adjusted to filter solids of any dimension or size. Further, in this embodiment of the centrifugal filter apparatus110, much of the filtration is accomplished by the external centrifugal radial fins162which drive solids radially outwardly to the solids outlet122. The helical filter element112of the centrifugal filter apparatus110of this invention may be easily backwashed quickly by injecting air through pneumatic port138, raising the piston140, opening the filter pores and driving backwash liquid through the supernatant outlet121. This reversal in the direction of rotation of the internal centrifugal radial fins162, driving backwash liquid through the helical filter element and the external radial fins162then drives the liquid radially outwardly through the solids outlet122.

The dual chambered centrifugal and compressive filtration apparatus110will separate fluids and suspended solids into components based upon their respective densities by an integrated combination of centrifugal and filtration mechanisms. Incoming fluids containing solids are rotated at selected velocities, for example, 10,000 revolutions per minute, to achieve waste solids liquids separation in the millisecond to second range. This generates G-forces in the 13,000 range in a canister whose radius is 15 cm. Solids separate from suspended fluid in this gravitational field at clearing times proportional to their densities and masses. The suspension introduced at the inlet120deposits on the canister inner cylindrical surface133. Upon clarification, liquid media is forced through the helical filter element112. Heavy particles will clear quickly into the space between the external centrifugal radial fins162and the filter canister's wall133. It will be noted that the direction of rotation of the external fins162corresponds to the direction of flow of the incoming solids and fluid suspension through inlet120. This parallel flow, where the suspended solids are introduced adjacent the outer surface subjects the dense and more massive particles to maximum G-forces, at the point of greatest radial distance from the center of rotation. The solids dewater and collect at the inner surface133of the canister housing, thereafter continuing to rotate downward toward the solids output or exit122. The aspect ratio cross-section to canister height may vary from 4:20 to 4:1 depending on volume throughput and time sedimentation time requirements. The solids clearing (sedimentation) time (T) is proportional to radial distance from the center of rotation (r), velocity (vf) and density (dm) of fluid medium, particle density (dp), diameter (D2) and a rotational velocity (RPM2). From calculations using T=r/vf×D2(dm−dp)xRPM2, where r and D are in cms., the clearing times for waste particles are calculated to be in the millisecond to second ranges at 104RPMs, well within the dwell times within this centrifugal filtration device, if the volume is 20 gallons and the flow rate were to be 60 gallons per minute.

As set forth above, the external and internal centrifugal radial fins162and164, respectively, may be canted with pitch values to reduce materials drag at high G-forces and to facilitate uniform radial transport in that field with maximum sheer and solid particulates. As used herein, “canted” includes angle or pitch as shown, for example, by the angled external centrifugal radial fins162inFIG. 12or the fins may be spiral as the internal centrifugal radial fins164spirally surround the central drive rod202. The pitch values may also vary from top to bottom of the canister in a spiral manner, for example, to further reduce shear of incoming solids. The solids introduced at120are subjected to centrifugal forces acting on the solids; the suspending fluids, however, are driven by both centripetal (central orienting pressures) forces and negative (pull) pressures exerted by the internal centrifugal radial fins164. The suspended fluids are thus clarified. The combination rapidly and completely separates solids and liquids, without the use of thickening or flocking chemistries. It is apparent that the internal and external centrifugal radial fins162and164, respectively, along with line pressure force clarified fluids and solids to exit that their respective outlets121and122, respectively. The centrifugal fins simulate a conventional centrifuge head, except that the canister (head equivalent) is stationary and the fluids or solids are in motion. The non-sedimentation solids rotate in a neutral zone surrounding the helical filter112to be removed and combined with the solid fraction upon periodic backwash. These sedimented solids exit the canister or housing adjacent the cylindrical inner surface133of the canister housing132through solids outlet122.

As will be understood, the centrifugal filter apparatus110of this invention may be used to remove microscopic and submicroscopic particles from an industrial stack, combination engine exhaust, syngases generated by gasifiers and valuable machine oils. To extend the range of the filtration to submicroscopic levels, the helical coils114may include radial grooves or micropores as shown at64inFIG. 3for filtration of submicroscopic particles when the helical filter element112is substantially fully closed as shown inFIG. 8. The backwash will take no longer than three seconds and may only infrequently be required due to the continuous removal of essentially all of the suspended solids by the centrifugal action of the external centrifugal radial fins162. The backwash cycle is either called through computer-activated relays in response to an in-line pressure transducer at the inputs or is routinely set to occur at some time interval. Backwash cycles in a dual chambered centrifugal of this invention is capable of flow reversal of clean filtrate back thought its core, through its filter, and out through the solids outlet carrying retentate with it, may be initiated in any sequence, either though individual units or in pairs or simultaneously through all units in parallel. If the central flow reversing internal radial fins162are not included in the filter unit, backwash may still be accommodated, whereby diverting a portion of the clean fluid of one filter of a pair to its parallel sister though split stream valves momentarily flushes the second unit. Repeat of the shared cleansing cycle completes the paired backwash. In the disclosed embodiment of the centrifugal filter apparatus110, filtration and driver shaft units are pressure sealed internally with seals206as shown inFIGS. 7 and 8. Further, because the external centrifugal radial fins162are rotated at very substantial velocities, the spindles bearings208, such as fully caged brass or ceramic bearings.

The centrifugal filter apparatus110may be used for clarifying used machine or vehicle oils, which are known to contain a wide distribution of metallic, silicone and plastic solids contaminants from millimeter to micron size. Rancid oils also contain colonial bacterial forms with cross-sections exceeding ten microns. Clarification improves the ability of reprocessing plants to recycle such waste products for reuse as machine or engine lubricants or as fuel blends for power plants. Most oils contain polar emulsifying agents to assist in the suspension of solid particulates, water and chlorinated paraffins. These emulsifying water-oil-particulate fractions, referred to as micelles are found to form size-specific cross-sections in the range of 250 microns and 50 microns. The flat wire helical filter element of this invention is found to break up these micelles as a consequence of frictional forces, assisted by heating. The flat wire helical coil filter element112breaks the emulsions in three phases, which the centrifugal filter will separate. After a micelle break-up with heat and passage through the helical filter element112, the micelle cracks, releasing contained water, polar emulsifying agents, particulates, chlorinated paraffin, which all separate from useful oil in the centrifugal filter apparatus of this invention by a three-phase split.

The centrifugal filter apparatus110of this invention may also be combined with ancillary equipment for further clarification of the liquid and drying of the solids. For example, the liquid or supernatant outlet121of the filter canister may be directed to a chelating or ion exchange adsorbent column to remove soluble (waste) chemicals. The liquid supernatant may be passed through a resin column, further purifying the liquid. To achieve further drying and sterilization of the solids exiting the filtration apparatus through solids outlet122, the partially dry solids may be directed into a filter press consisting of a compressive element as shown at54inFIG. 2having a piston compression, for example, wherein the partially dried solids are heated and compressed depending upon the application. This compression element is not, in this instance, used to adjust the filter's pores or apertures but to apply pressure to the solids fed to the filter's core though22. This modification uses the filter's pores to retain the solids while expressing the liquid phase through20. The base plate18may include a sliding valve which is triggered to open when the piston element driven by the shaft52, below54, has reached maximum extension as measured by the driver motor46.

FIGS. 13 to 18of this application disclose a third embodiment of a filter apparatus or separator filter apparatus210which may be used to filter and separate or purify various fluids, including liquids and gases. In one disclosed embodiment, the filter separator210may be used to purify syngas and remove suspended waste particulates and waste gaseous oxides of nitrogen, sulfur or carbon. It is well known that in the process of gasification of biomaterials, particulates in the micron size range as well as the noted contaminating oxides are generated. These contaminate the syngases (CO/H2). CaO (hot lime) or other metal oxides in the gas separation to form CaCO3, CaSO4and Ca[NO3]2as discussed further below, a metal oxide, such as CaO separates contamination gases from the fuel gases or syngases which can be subsequently stripped of gaseous contaminants and regenerated by periodic heating at calcination temperatures in the 1200° F. range as also discussed below.

The filter separator210shown inFIG. 13includes an annular microfilter212which may be identical to the annual filters12and112described above with respect toFIGS. 1 to 9. The filter separator210includes lower housing members218and219which include a fluid inlet220and fluid outlet222. The filter separator apparatus210further includes a cover224, and inner retention posts226and outer retention bolts228which secure the cover224to the lower housing members218with nuts229. As would be understood from the above description of the filter separator apparatus210, the components of the filter separator apparatus210have been numbered in the same series where possible as the filter apparatus10and110described above but in the 200 series.

The disclosed embodiment of the filter separator apparatus210includes an outer wall232defining an enclosed filter canister defined by the cover224and the lower housing member218,219and the other wall232. However, in this embodiment, the outer wall may be any convenient shape. The disclosed embodiment of the filter separator apparatus210shown inFIG. 13includes a pneumatic cylinder234having a first pneumatic inlet236and a second pneumatic inlet238which move the piston assembly240upwardly or downwardly as described above particularly with reference toFIG. 7. That is, the first pneumatic inlet236drives the piston assembly240downwardly as shown inFIG. 13and the second pneumatic inlet238may be utilized to raise the piston assembly to adjust the compression of the helical coil annular microfilter212as described above. In this embodiment, the filter separator apparatus210also includes an actuator motor246having a shaft connected to a first gear242, driving a second gear244connected to a rotatable shaft or drive shaft248connected to one of the coils, such as the upper coil of the helical annular microfilter212. As described above, the motor246may be a conventional stepper motor, which is a brushless synchronous electric motor that can divide a full rotation into a large number of steps, for rotating one coil of the continuous helical coil relative to the remaining coils for moving the peaks and troughs into and out of registry as described above with reference toFIGS. 4 to 6. In one preferred embodiment, the annular microfilter212includes flat upper and lower surfaces14and a plurality of surfaces circumferentially spaced radially grooves or laser etched microgrooves or pores64as shown inFIG. 3. As discussed below, where the filter separator apparatus210is utilized to filter and purify a gas, the individual interconnected coils of the helical annular microfilter are preferably rotated into registry, such that the filter pores are limited to the radial grooves64shown inFIG. 3.

In the disclosed embodiment, the filter separator apparatus210includes a plurality of radial mixing blades260rotatably mounted on a hollow shaft262as best shown inFIGS. 14 to 16and18. As shown inFIG. 15, the mixing blades260preferably circulate the fluid upwardly adjacent the central shaft as shown by arrows “A” and downwardly adjacent the annular microfilter212. However, the circulation can also be reversed. This vertical circulation results in full mixing of the fluids with adsorbent particles for separating fluids as described below.

In the disclosed embodiment, each of the radial mixing blades260include a radial central portion264extending perpendicular to a rotational axis of the hollow shaft262and generally horizontally, The mixing blades260further include a first side portion266adjacent the hollow shaft262extending radially and circumferentially at an obtuse angle relative to the radial central portion264as shown inFIGS. 16 to 18, and a second side portion268spaced radially from the first side portion266extending from an opposite side of the radial central portion264extending radially and circumferentially at an obtuse angle to the radial central portion. As best shown inFIG. 18, the hollow shaft262includes a plurality of circumferentially spaced mixing blades260which are also spaced axially along the central shaft262. The hollow central shaft also includes a plurality of radial apparatures as best shown inFIG. 18. Upon rotation of the hollow shaft262in a counterclockwise direction as shown inFIG. 16, the first side portions266circulate fluid in the separation chamber272vertically upwardly as shown by arrows “A”, and the second side portions268circulate fluid vertically downwardly as shown by arrows “B” inFIG. 15.

The filter separator apparatus210further includes a second motor274, such as an electric motor, having a drive shaft connected to a drive gear276which drives a driven gear278fixed relative to the hollow shaft262. Thus, the second motor274will rotate the hollow shaft262and the mixing blades260as described above. The disclosed embodiment of the filter separator apparatus210further includes an injector280, such as an air torch, for injecting fluid into the separation chamber272and the apparatus may also include further injection ports282for injecting fluid into the separation chamber272. In the disclosed embodiment, the inlet220also includes a three-way valve284for controlling passage of fluid from the inlet220into the filtration chamber230.

Having described one preferred embodiment of the filter separator apparatus210, the method of filtering and separating various fluids by the method of this invention may now be described. The filter separator apparatus210may be utilized to filter and separate or purify various fluids, including liquids, such as water and various gases, such as syngas. As set forth above, synthesis gas or syngas which is a mixture of carbon monoxide and hydrogen, may be converted into hydrocarbons of various forms by the Fischer-Tropsch process by the formulation above. As will be understood by those skilled in this art, syngas or synthesis gas refers to the final use of the gas and is thus sometimes referred to a fuel gas. Now, with the understanding that the filter separator of this invention may be utilized to filter and separate or purify various fluids, including liquids and gases, the method of this invention will now be described with reference to a method of purifying syngas consisting essentially of carbon monoxide and hydrogen.

Syngas, including waste gaseous oxides of sulfur, nitrogen or carbon and suspended fine waste particulates are received under pressure in the annular filtration chamber230through the inlet220and three-way valve284as shown. In the method of filtering and purifying gases, as opposed to liquids, the annular microfilter is preferably in the “closed” position, wherein the stepper motor246rotates an upper coil (as shown inFIG. 6), such that the coils are in the trough-to-trough position. As will be understood, the spacing between the coils of the annular microfilter212inFIGS. 14 and 15has been exaggerated for clarity. In the closed position, wherein the piston240is extended by air pressure through pneumatic port236as shown inFIG. 13, the coils are in surface-to-surface contact and the only filter pores are through the radial grooves or laser etched micropores64shown inFIG. 3. As would be understood, the size of the radial grooves would depend upon the waste particulates to be filtered; however, it is anticipated that the grooves or laser etched micropores will have a diameter of 10 micrometers or less into the nanometer range. The filtered gas is then transferred through the radial grooves64(seeFIG. 3) of the microfilter212into the separation chamber272. As described above, the gas in the separation chamber272is circulated vertically upwardly and downwardly as shown by arrows “A” and “B” inFIG. 15by the rotating mixing blades260. Where the filter separator apparatus210is used to purify syngas, the separation chamber272includes fine gas adsorbent metal oxide particles, such as calcium oxide particles from kiln dust from a cement kiln. As would be understood by those skilled in this art, various adsorbent metal particles may be used, but calcium oxide particles from kiln dust is inexpensive and effective. The fine adsorbent particles adsorb waste gas in the separation chamber272, including gaseous oxides sulfur, nitrogen or carbon. The rotating mixing blades circulating gas and adsorbent particles upwardly and downwardly as described above, ensure uniform mixing of gas and solid phases for maximum adsorbent efficiency. The oxides, except for carbon monoxide and hydrogen, on passing through the filter bind with the adsorbent. The filtered and purified syngas is forced through the moving adsorbent column and out of the gas outlet222.

The adsorbent, enclosed by the pitched and bidirectional mixing blades260eventually becomes saturated with unwanted gaseous oxides. Carbon dioxide sensors or pressure transducers to monitor adsorbent saturation or filter occlusion may be provided at the outlet222. If the frequency of the saturation events are known, a purging cycle of the filter and adsorbent may be initiated at an appropriate time interval to avoid saturation or occlusion. This may be accomplished with an air torch282which directs a dry and carbon dioxide free gas, such as hot nitrogen, under pressure into the hollow shaft62. This purging gas is forced axially and radially through the radial openings270shown inFIG. 18into the separation chamber272. The purging gas is then forced through the saturated adsorbent, desorbing gaseous oxides of sulfer, nitrogen or carbon, which are forced through the filter and out of the gas inlet220. While the filter during its filtration mode relied upon the laser-etched micropores64shown inFIG. 3, during purging, however, the filter is preferably opened incrementally by reversal of the stepper motor246, thus rotating the spiral coils out of registry preferably to a stop (not shown) while extending the coil through the open position by injecting compressed gas through the pneumatic port238, wherein the apparature openings allow passage of purging gas as indicated at a greater velocity to remove particles adhering to the outer surface of the annular microfilter212and discharge with the purging gas. The purging gas must be preheated in the air torch282to 1200° F. in order to remove bound CO2, NOX, SOXand water from the adherent particles. In this manner, the fuel gas undergoes a self-cleaning cycle.

As set forth above, the fluid separator210may be used for filtering, separating and purifying various gases and liquids. For example, chelating agent resins or ion exchange agent resins may be injected into the column through the outlet ports222and water may be purified of dissolved solid waste or organic ions or cations. Such resins may be regenerated by sequential additions of an acid and base through injection ports282to strip adsorbed substances from the resin and regenerate its preferred surface charges. Further, as would be understood by those skilled in this art, various modifications may be may be made to the filter separator apparatus210, the method of filtering, separating and purifying fluids disclosed herein and the fluid mixing and circulating provided by the mixing blades260within the purview of the appended claims. For example, various mixing devices may be utilized in the separation chamber272; however, in a preferred embodiment, the mixing device circulates the fluid upwardly adjacent either the annular microfilter212or the axis of the separator chamber and downwardly as described to provide thorough mixing of the adsorbent particles and the fluid containing waste. Further, other annular filter elements may be used in place of the helical coil annular microfilter212as disclosed inFIGS. 3 to 6depending upon the fluid being filtered. However, where the filter separator apparatus210of this invention is utilized to filter and separate or purify gases particularly syngas, the annular microfilter212has several advantages as described above. Further, as set forth above the filter canister defined by the annular wall232may be any convenient shape including, but not limited to, cylindrical. Having described an embodiment of the filter separator apparatus, method and fluid mixing and circulating apparatus of this invention, the invention is now claimed as follows.