The present disclosure relates generally heating or heating and drying materials, such as drilling cuttings. More particularly, the present disclosure relates to heating or heating and drying materials through induction heating.
In association with earth drilling, for example drilling a wellbore for oil and gas well drilling, drilling fluid is circulated down the wellbore and across the face of the drill bit, and drilling fluid along with drilling cuttings (for example shale) circulated back up the wellbore to surface.
The drilling cuttings and drilling fluid are separated to some degree, and the drilling fluid re-used.
However, the drilling cuttings with residual drilling fluid must be further treated, processed, or disposed of. The drilling cuttings may contain residual invert drilling fluid, gel or chemical, or bitumen or combination thereof. Government regulation often require such drilling cuttings cannot remain on the location, and must be transported (e.g. by trucking) to a disposal site. It is not uncommon for the drilling cuttings to be so wet and sloppy (i.e. with drilling fluid) that the drilling cuttings must be mixed with a stabilizer, such as wood sawdust, until the mixture is able to satisfy a stability slump test before it can be hauled away from the drilling location to the disposal site. If sawdust is not readily available, trees may be cut down and shredded to prepare sawdust at the location.
At the disposal site, the disposal site operator may record where the drilling cuttings originated, for example a specific rig on a specific geographic location (e.g. GPS location or other identifier such as legal subdivision (LSD) as used in Alberta and British Columbia, Canada) along with the well site information and all of the information of that load whether it is from surface hole with gel/chemical mud or when they switch to invert mud or whether it is from the production or sand zone etc. Depending on the type of material, the disposal site may require the load be dumped in certain places on the disposal site.
The long term effects and responsibility for these materials may be a concern for the oil and gas company and others involved with the drilling operation.
It is, therefore, desirable to provide method and apparatus for drying drilling cuttings. It is also desirable to provide a method and apparatus for heating or drying or heating and drying other feed materials.
It is an object of the present disclosure to obviate or mitigate at least one disadvantage of previous techniques for handling drilling cuttings.
In a broad aspect, the present disclosure provides a heater or dryer or both using induction heating and rotary agitation or tumbling.
In a further aspect, the present disclosure provides an induction heater for processing a feed material including a main tube having an internal conveyor, at least one of the main tube or conveyor providing an at least partly ferrous part, one or more electric induction coils for heating the at least partly ferrous part to heat the feed material to provide heated outlet material, and a conveyor drive for driving the conveyor.
In an embodiment disclosed, the conveyor includes a drag chain.
In an embodiment disclosed, the conveyor is an auger, rotatable relative to the main tube by the conveyor drive.
In a further aspect, the present disclosure provides an induction heater for processing a feed material including a rotatable main tube having an internal auger or flighting, at least one of the main tube or internal auger or flighting providing an at least partly ferrous part, one or more electric induction coils for heating the at least partly ferrous part to heat the feed material to provide heated outlet material, and a main tube drive for rotating the main tube.
In an embodiment disclosed, the main tube and the internal auger or flighting are substantially ferrous.
In an embodiment disclosed, the main tube and the internal auger or flighting are steel, stainless steel, or graphite.
In an embodiment disclosed, the induction heater includes a gear crusher for crushing the feed material, the gear crusher including spaced-apart gears, at least one of the spaced-apart gears driven by a gear drive.
In an embodiment disclosed, a gap between the spaced-apart gears is adjustable to provide an adjustable size for the crushed feed material, the particle size between a fine particle dust and a course shale.
In an embodiment disclosed, the induction heater includes a stack adapted to vent or flare at least a portion of outlet vapors from the outlet material.
In an embodiment disclosed, the induction heater includes a cooler adapted to cool outlet vapors from the outlet material.
In an embodiment disclosed, the cooler includes a condenser adapted to condense recovered water from the outlet vapors.
In an embodiment disclosed, the induction heater includes a fire box adapted to cool outlet solids from the outlet material.
In an embodiment disclosed, the induction heater includes a blower adapted to convey the outlet material from the main tube.
In an embodiment disclosed, the induction heater includes a scrubber system adapted to clean outlet vapors from the outlet material.
In an embodiment disclosed, the cooler comprises an air cooler, further including a blower adapted to provide ambient air to the air cooler; a stack or chimney at or near a base of the stack or chimney; or both.
In a further aspect, the present disclosure provides a method of processing a feed material including conveying the feed material through a main tube having an internal conveyor, at least one of the main tube or the conveyor providing a ferrous part, the feed material conveyed through the main tube by the conveyor, heating the feed material by induction heating of the ferrous part, at least a portion of the feed material and at least a portion of the ferrous part in contact, wherein the feed material is heated to provide a heated outlet material.
In an embodiment disclosed, the conveying includes rotating or tumbling the feed material.
In an embodiment disclosed, the conveyor includes an internal auger or flighting, and wherein the conveying includes relative rotation between the conveyor and the main tube.
In an embodiment disclosed, the conveyor comprises an internal auger or flighting, and wherein the internal auger or flighting and the main tube are connected, and wherein the conveying comprises rotating the internal auger or flighting and the main tube together.
In an embodiment disclosed, the internal auger or flighting and the main tube are ferrous.
In an embodiment disclosed, the method includes crushing the feed material prior to heating.
In an embodiment disclosed, the outlet material has a lower moisture content than the feed material.
In an embodiment disclosed, the feed material contains polychlorinated biphenyl (PCB), wherein the feed material is heated up to at least 2150 degrees Fahrenheit for a period of time, to remove the PCBs from the feed material.
In an embodiment disclosed, the method includes recovering outlet vapors from the main tube.
In an embodiment disclosed, the outlet vapors are burned to generate electricity to at least partially supply the induction heating.
In an embodiment disclosed, the feed material includes drilling cuttings.
In an embodiment disclosed, the feed material includes gravel.
In an embodiment disclosed, the feed material is selected from the group of geologic material, hazardous waste, and organic waste.
Other aspects and features of the present disclosure will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments in conjunction with the accompanying figures.
Embodiments of the present disclosure will now be described, by way of example only, with reference to the attached Figures. This application includes
Generally, the present disclosure provides an apparatus and method for heating materials, in particular heating and drying of a wide variety of materials, including but not limited to drilling cuttings, by induction heating and tumbling.
Referring to
In an embodiment disclosed, the main tube 50 is rotated at a rate such that the contents (e.g. the feed material 30) are tumbled. In an embodiment disclosed, the main tube 50 is rotated at less than about 10 rpm. In an embodiment disclosed, the main tube 50 is rotated at about 4 rpm.
One or more electric induction heater coils 70 are used to heat the feed material 30. The main tube 50 or an internal conveyor 75 or both are at least partially ferrous and thus heatable by the one or more induction heater coils 70. There is a gap between the main tube 50 and the induction heater coils 70, which may include thermal insulation or an air gap or both. The main tube 50 is rotated while the induction heater coils 70 remain stationary.
The induction heater coils 70 are provided with an alternating current voltage source from a power supply 500 via a coil drive 510 and the frequency (Hz) of the alternating current voltage source may be set or adjusted via coil drive 510 to control the depth of penetration of the oscillating magnetic field and the induced eddy currents. The energy (voltage or current or kW) or the temperature or the frequency (Hz) or combinations thereof may be set or adjusted manually or by an automatic control system. The coil drive 510 drives the induction heater coils 70 to control the temperature or heating of the feed material 30 as it passes through the main tube 50 from the inlet 40 to outlet 90. The induction coil drive 510 drives the induction heater coils 70 of any frequency but the lower the frequency the deeper in the heat goes into the main tube 50 and a spiral auger or flighting 80. For example, using a frequency of about 100 Hz or 500 Hz provides deeper penetration than a frequency of 3000 Hz, and a frequency of 1000 Hz would provide a penetration in-between that of 500 Hz and 3000 Hz. The coil drive 510 may preferably receive alternating current (AC) power, for example from a power line, generator, or other source (for example 480V or 600V, 3-phase, 60 Hz) and the AC power is rectified to provide direct current (DC) power, and then a variable inverter is used to provide the AC drive signal to the induction heater coils 70.
The induction heater coils 70 heat the main tube 50 or the spiral auger or flighting 80 or both by magnetic induction heating, and thus the feed material 30 is heated by the main tube 50 or the spiral auger or flighting 80 or both. The main tube 50 is thermally insulated and electrically insulated from the rest of the induction heater 10.
In an embodiment disclosed, electrical conductors 515 between the coil drive 510 and the induction heater coils 70 or within the induction heater coils 70 or both are liquid cooled. In an embodiment disclosed, the electrical conductors 515 between the coil drive 510 and the induction heater coils 70 are twisted together to reduce or cancel out heat and electrical noise and preferably do not exceed about 25-100 feet in length for greater efficiency.
The conveyor 75 is used to convey the feed material 30 through the main tube 50 which is more important when the main tube 50 is sloped upward (described below). The conveyor 75 may be, for example, a drag chain (not shown). However, the conveyor 75 is preferably a spiral auger or flighting 80 (see
Outlet material 100 exits the main tube 50 at the outlet 90. The outlet material 100 may include outlet vapors 100V, outlet liquids 100L, outlet solids 100S or combinations thereof. The makeup of the outlet material 100 is variable depending on the feed material 30 and the extent of heating and temperature applied by the induction heater 10.
In an embodiment disclosed, the outlet material 100 is substantially outlet solids 100S and outlet vapors 100V with minimal liquids 100L.
Referring to
The feed material 30 is received in a hopper 120 of the gear crusher 110. The gear crusher 110 includes gears 130 spaced apart having an adjustable gap 140. In an embodiment disclosed, the gears 130 are involute gears. In an embodiment disclosed, the gears 130 are herring bone or splines or simple V-shaped or square or shaped to crush the feed material 30 (e.g. shale drilling cuttings) to finer particles. One or more of the gears 130 are driven by a drive 150 (see
Referring to
In some conditions (e.g., temperature and composition of the feed material 30), combustible components may ignite and burn in the main tube 50 (thus the rising slope of the main tube 50). The stack or chimney 180 may include a flare 190, ignited by one or more electric ignitors 530, if the feed material 30 includes flammable components (e.g. hydrocarbons such as diesel fuel based invert drilling fluid or bitumen) such that any flammable vapors, if any, in outlet vapor 100V may be flared (burned) off. The stack or chimney 180 may be releasably connected with the induction heater 10 and one or more portions of the stack or chimney 180 may be hinged or articulated to facilitate transition between a working mode (
The temperature of the outlet material 100 and outlet vapor 100V at the outlet 90 of the main tube 50 may be in the 600 degrees Fahrenheit to 2150 degrees Fahrenheit range. An operating temperature of about 600 degrees Fahrenheit may be used in normal operation, and the higher 2150 degrees Fahrenheit used when the feed material 30 includes polychlorinated biphenol (PCB) components. In an embodiment disclosed, a temperature of about 600 degrees Fahrenheit is suitable for drying sand. In an embodiment disclosed, the air cooler or condenser unit 220 may be used to cool the outlet vapors 100V. The air cooler or condenser 220 reduces the temperature of the outlet vapors 100V to reduce the risk that hot particles released from the stack or chimney 180 could be an ignition source, for example if in the forest a forest fire in the surrounding area. The length 540 of the air cooler or condenser 220 is sized to provide sufficient cooling or condensing of the outlet vapors 100V.
In an embodiment disclosed, the induction heater 10 may be equipped with a fire suppression system to extinguish or prevent the spread of fire. The fire suppression system may utilize one or more of dry chemicals, wet agents, gas, or water. In an embodiment disclosed, the fire suppression system uses an inert gas or halocarbon compounds. In an embodiment disclosed, the fire suppression system uses halon.
If the outlet material 100V includes water vapor, at least some water vapor (steam) may be sufficiently cooled to be condensed by the air cooler or condenser unit 220 to form recovered water 230 at drain 550.
Solid outlet material 100S, (e.g. dried drilling cuttings) may be conveyed from the induction heater 10 by a blower 240. In an embodiment disclosed the blower 240 delivers air 590 through a conduit 250. In an embodiment disclosed, the outlet 90 of the main tube 50 and the conduit 250 are fluidly connected, the flowing air 590 inducing a draft in the main tube 50 though the venturi effect. A further gear crusher (470
Referring to
In an embodiment disclosed the main tube 50 is a 6⅝″ OD pipe with an ID of 5.761″ Inches, and a length of about 40 inches long is heated with induction heater coils 70. In an embodiment disclosed, the main tube 50 has a 30″ OD and 29″ ID and a length of about 72 inches long is heated with induction heater coils 70. In an embodiment disclosed, the main tube 50 is about 9 feet long and the spiral auger or flighting 80 starts at the inlet 40 and runs through the entire main tube 50 to the outlet 90, i.e. length 560 is also about 9 feet.
The spiral auger or flighting 80 has a spiral pitch 570. However, these configurations are just examples. The feed material 30 may be conveyed through the main tube 50 by rotation of the spiral auger or flighting 80, and the spiral auger or flighting 80 may be attached to and rotate with the main tube 50 as the main tube 50 is rotated, or the spiral auger or flighting 80 may be rotated and the main tube 50 stationary. In an embodiment disclosed, the main tube 50 or the internal auger or flighting 80 or both may be made of steel, stainless steel, or graphite (e.g. graphite crucible).
In an embodiment disclosed, the main tube 50 may be welded pipe or seamless pipe. In an embodiment disclosed, the main tube 50 is seamless pipe. This is more important at higher energy rates (kW) levels. Welded pipe may be used, but if the induced eddy currents are high, the eddy currents will attack the internal welds and eat the welds out of the welded pipe. As noted previously, the main tube 50 is electrically isolated/insulated from the other components so that the induced/eddy currents do not damage the other components.
The auger or flighting 80 may be connected to the main tube 50 at non-coil areas of the main tube 50 in order to avoid eddy current damaging fasteners (such as welds or bolts). In an embodiment disclosed, the auger or flighting 80 is seamless without welds and is held in place by one or more fasteners (e.g. bolts), the one or more fasteners at a non-coil areas of the main tube 50, the non-coil areas of the main tube 50 being the portions of the main tube 50 not covered by the induction heater coils 70. The inlet 40 and the outlet 90 for example are shown as non-coil areas. The spiral auger or flighting 80 may be changed out very quickly if need be, for example to change the spiral pitch 570, clear an obstruction, replace the spiral auger or flighting 80, or perform other maintenance.
Referring to
Recovered water 230 (see
The outlet material 100, and in particular the outlet solids 100S may be tested. If within government regulations, the outlet solids 100S (e.g. dried drilling cuttings) may be spread back on the lease road or back on location. Thus avoiding the need for offsite disposal and avoiding the need for stabilizer (e.g. sawdust), personnel to mix the sawdust and the drilling cuttings, the trucking costs, and the long term impact of and responsibility for the drilling cuttings at the disposal site.
In an embodiment disclosed, the induction heater 10 of the present disclosure may be used to remediate a lease or drilling location or drilling cuttings disposal site. Rather than processing drilling cuttings 300 from the shale shaker 310 or centrifuge 320 of a drilling operation in real-time or substantially real-time as they are produced, the previously untreated drilling cuttings (e.g. mixed with sawdust and deposited at a disposal site) are conveyed to the inlet 40 of the induction heater 10 as feed material 30. This provides, for example, for the remediation of drilling cuttings disposal sites or other concentrations or piles or dumps of shale drilling cuttings.
Referring to
In an embodiment disclosed, the feed material 30 is heated such that it becomes at least partially molten. In an embodiment disclosed, the feed material 30 is drilling cuttings 300, which become molten glass. In such operation, the main tube 50 must be selectively set or adjusted to at least a slight downward slope (at least 1 degree downward, e.g. minus 1 degree) as a liquid does not flow uphill. However, the slight downward slope still allows any vapors to escape to the outlet 90 of the main tube 50 due to the venturi effect of the blower 370 and natural convection up the stack or chimney 180. A greater downward slope on the main tube 50 may be used with enough induced or forced air flow to ensure that the fumes or gases (i.e. outlet vapors 100V) exit the outlet 90 of the main tube 50.
Outlet vapors 100V from the outlet 90 of the induction heater 10 are passed through an air cooler or condenser unit 220, through a stack or chimney 180, and a scrubber 360, and a flare 190 is used to burn off any remaining combustibles. The scrubber 360 is configured for the operating conditions, for example but not limited to temperature, outlet vapors 100V, and flowrate, and may include for example a dry type scrubbers, such as a baghouse to filter out particulate or fine particulate in the outlet vapors 100V. The air cooler or condenser unit 220 may be provided with a source of ambient air by a blower 370. The air 375 is routed through the air cooler or condenser unit 220, thereby cooling the outlet vapors 100V, and the air 375 is then routed into the stack or chimney 180 at piping 380 and exits at outlet 390 within the stack or chimney 180. The air 375 induces or enhances the flow of the outlet vapors 100V up the stack or chimney 180. In addition, by cooling the vapors 100V, the temperature is reduced which reduces the risk of starting a forest fire due to hot cinders and reduces the cost of the instrumentation for monitoring the vapors from the stack or chimney 180 (commonly available equipment may be used instead of very expensive high temperature testing equipment). The induction heater 10 and air cooler or condenser unit 220 may be housed in a building (not shown) and the stack or chimney 180 would extend through the roof of the building. In an embodiment disclosed, the outlet vapors 100V from the stack or chimney 180 would be less than about 80 degrees Fahrenheit. Depending on the composition of the outlet vapors 100V at least a portion of the outlet vapors 100V may condense. Condensed liquid may be collected at the drain 550.
The scrubber 360 may be a wet or dry scrubber to clean the particulate and gasses and smoke out of the outlet vapors 100V before exiting the stack or chimney 180.
Referring to
Referring to
Cooling liquid, for example a glycol/water mix, is provided by a coolant system 440 (see
Referring to
In an embodiment disclosed, rather than use the coolant system 440, heat may be recovered from the fire box 410 for example to heat a building or a drilling rig or other purposes. In an embodiment disclosed, heat may be recovered from the fire box 410 or otherwise from the outlet material 100 to drive a generator, for example by creating pressurized steam to power a turbine to drive a generator to produce electricity to at least partially supply the power supply 500 or other electrical needs of the induction heater 10. In addition, combustible vapors may be recovered from the outlet vapors 100V and used to drive a generator, for example by combustion to power an internal combustion engine to drive a generator to produce electricity to at least partially supply the power supply 500 or other electrical needs of the induction heater 10. Heat recovered from the fire box 410 or otherwise from the outlet material 100 to preheat the feed material 30.
Referring to
Referring to
Referring to
Actuators 350 are used to set an incline (
In an embodiment disclosed, the induction heater 10 may be used to reduce the moisture content or increase the temperature of a wide variety of solid, semi-solid, granular, powder, sludge, or slurry materials. The moisture removed may be from within the material, e.g. interstitial, pore space, or otherwise, or may be from the exterior surfaces of the material or combinations thereof.
As mentioned previously, the induction heater 10 may be used to dry drilling cuttings. In an embodiment disclosed, the feed material 30 is drilling cuttings from drilling operations using invert drilling fluids (hydrocarbon based, for example diesel fuel based) or gel shale or chemical shale or bitumen shale. In addition to processing drilling cuttings 300, the feed material 30 may include snow or ice contaminated with hydrocarbons, water, salt water, or hydrocarbons (for example invert drilling fluid which may include about 10-100 percent diesel fuel).
In an embodiment disclosed, the induction heater 10 may be used to reduce the moisture content or increase the temperature of geologic materials or both. The geologic materials may include dirt, soil, rocks, shale, gravel, sand, aggregate, sludge, sediment, sludge or other geologic materials. The geologic materials may be used, for example, in dam construction, building construction, or other earthwork construction. In such an embodiment, the induction heater 10 would not likely require a scrubber 360. The geologic materials may be excavated, processed through the induction heater 10 and redeposited in order to remove contaminants. In an embodiment disclosed, the induction heater 10 may be used to reduce the moisture content or increase the temperature of soil or sediment or sludge obtained from the bottom of a body of water such as a river or lake for example by dredging, suction/vacuum/hydro excavation, or other excavation in order to remove contaminants.
In certain construction operations, such as pouring high-strength or high-performance concrete in cold climates, processing the aggregate through the induction heater 10 (for example as in
In certain construction operations, excavated geologic materials may be processed through the induction heater 10 as the feed material 30 and then the outlet material 100 re-deposited. This excavate-dry-backfill process may be very useful in, for example, excavation or boring of earth in underground tunnel construction.
In an embodiment disclosed, the induction heater 10 may be used to reduce the moisture content of organic waste material, such as manure, animal dung, agricultural wastewater, blackwater, greywater, human feces, urine, or sewage.
In an embodiment disclosed, the induction heater 10 may be used to reduce the moisture content of mining waste, such as tailings. The tailings may be, for example gold mining tailings or oil sands tailings. The oil sands tailings may be mature fine tailings (MFT). The tailings may be processed as they are produced, or the induction heater 10 may be used to process accumulated tailings, for example tailings piles, dumps or settled tailings from tailings ponds.
In an embodiment disclosed, the induction heater 10 of the present disclosure may be used to reduce the moisture content of waste, such as hazardous waste, medical waste, or biomedical waste. In this embodiment, the outlet material 100 (which may include one or more of outlet vapors 100V, outlet solids 100S, and outlet liquids 100L), may still constitute hazardous waste, and if that is the case, must be handled and contained accordingly.
In an embodiment disclosed, the induction heater 10 of the present disclosure may be used to reduce the moisture content or volume or both of mixed waste, such as domestic or industrial garbage.
In an embodiment disclosed, the material dryer 10 of the present disclosure may be used to process waste, selected from one or more or combinations of:
domestic trash;
domestic mud;
industrial mud;
fly ash;
gypsum;
hazardous waste;
domestic solid waste;
industrial waste;
sludges from domestic water treatment;
sludges from industrial water treatment;
mud from biochemical water treatment system;
bottom ash;
dredging spoil containing dangerous substances;
sludges containing dangerous substances from biological treatment of industrial waste water;
sludges containing dangerous substances from other treatment of industrial waste water;
sludges from oil/water separators;
mineral-based chlorinated engine, gear and lubricating oils;
waste fluids;
oil from oil/water separators;
fuel oil, diesel;
oily water from oil/water separators;
wastes containing oil;
waste paint and varnish containing organic solvents or other dangerous substances;
wastes from paint or varnish removal containing organic solvents or other dangerous substances;
synthetic engine, gear and lubricating oils;
fuel oil waste and diesel waste;
waste water containing oil or other hazardous substances;
discarded equipment, electronic components or electronic equipment containing electronic components (except for circuit boards not containing hazardous substances exceeding hazardous waste thresholds);
all types of oil waste;
battery, accumulator waste;
battery, lead accumulator waste;
fluorescent tube and types of activated glass waste;
rubber waste;
hard metal packaging waste including completely empty pressure container;
disposed absorbents, filtering materials (including oil filtering materials), rags, protection fabric contaminated with hazardous elements;
discarded equipment containing hazardous components (except for circuit boards not containing hazardous substances exceeding hazardous waste thresholds);
carbon-based linings and refractory materials originated from the metallurgical process containing hazardous substances;
linings and refractory materials with hazardous substances not originated from the metallurgical process;
other wastes containing hazardous organic substances;
wastes containing hazardous substances from exhaust gas treatment process;
infectious waste (including sharp waste);
emulsion and waste liquids not containing organic halogen waste from shaping process;
ferromagnetic powder solution;
disposed acid clorhidric;
other kinds of disposed acid;
disposed sodium hydroxide, ammonium hydroxide, potassium hydroxide and residues containing sodium hydroxide, ammonium hydroxide, potassium hydroxide;
disposed acid sulfuric;
pickling bases;
disposed printing ink box containing hazardous substances;
metal scrap mixed with oil or coal tar;
disposed thermal insulation materials containing asbestos;
not completely empty pressure containers;
broken, damaged or used devices containing mercury and heavy metals (thermometer, sphygmomanometer);
discarded electronic components or other electrical equipment having electronic components containing hazardous substances (except for circuit boards not containing hazardous substances exceeding hazardous waste thresholds);
discarded electronic components or other electrical equipment having electronic components (except for circuit boards not containing hazardous substances exceeding hazardous waste thresholds);
disposed flexible packaging;
shaping solution;
chemical container;
disposed chemicals and laboratory chemical mixtures having hazardous substances;
used catalyst containing transition metals or their compounds;
water waste having hazardous substances; and
other linings and refractory materials with hazardous substances originated from the metallurgical process.
In an embodiment disclosed, the induction heater 10 and associated components may be provided on a trailer, skid, or in a skid building or shipping container or shipping container frame, for example a DNV or ISO shipping container or shipping container frame.
In the preceding description, for purposes of explanation, numerous details are set forth in order to provide a thorough understanding of the embodiments. However, it will be apparent to one skilled in the art that these specific details are not required. In other instances, well-known structures are shown in block diagram form in order not to obscure the understanding.
The above-described embodiments are intended to be examples only. Alterations, modifications and variations can be effected to the particular embodiments by those of skill in the art. The scope of the claims should not be limited by the particular embodiments set forth herein, but should be construed in a manner consistent with the specification as a whole.
This application claims the benefit of priority of U.S. Provisional Patent Application No. 62/304,897 filed Mar. 7, 2016, which is hereby incorporated by reference.
Number | Date | Country | |
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62304897 | Mar 2016 | US |