APPARATUS FOR CONTINUOUS THERMAL SEPARATION OF A MULTI-COMPONENT SUBSTANCE

Abstract

A separation apparatus for continuous thermal separation of a substance is fed into a treatment chamber. The substance includes two or more components where at least one of the components is evaporable at an evaporation temperature (T.sub.e). The separation apparatus includes a vessel including a vessel wall with an inner surface enclosing the treatment chamber having a length I.sub.C, a height H and a width W, a substance inlet for feeding the substance into the treatment chamber, a first outlet for releasing non--evaporated parts of the substance from the treatment chamber, a second outlet for releasing evaporated parts of the substance from the treatment chamber, and a rotary mechanism. The rotary mechanism includes a rotatable axle arranged within the treatment chamber having an orientation directed along the treatment chamber's length L and a mixing device fixed to, and extending perpendicular from, the rotatable axle. A radial outermost part of the mixing device includes a plurality of radially separated mixing protrusions, a rotary drive operatively connected to the rotatable axis, and a heating device arranged outside the treatment chamber. The heating device is configured to transfer thermal energy to a minimum peripheral volume (Vp) of the treatment chamber via the inner surface. The minimum peripheral volume (V.sub.p) is defined as a volume between the inner surface and outer radial boundaries of the mixing device. The mixing device includes a plurality of rotary discs fixed with axial offsets to the rotatable axle. The heating device and the rotary drive are configured such that, when both the heating device and the rotary drive are operated at their respective operational input powers (P.sub.hd, P.sub.rm,), a resulting operational temperature (T.sub.op) is obtained within at least part of the minimum peripheral volume (V.sub.p) which is equal or higher than the evaporation temperature (T.sub.e).

Claims

1. A separation apparatus for continuous thermal separation of a substance being fed into a treatment chamber, the substance comprising two or more components where at least one of the components is evaporable at an evaporation temperature (T.sub.e), wherein the separation apparatus comprises a vessel comprising: a vessel wall with an inner surface enclosing the treatment chamber having a length l.sub.c, a height H and a width W, a substance inlet for feeding the substance into the treatment chamber; a first outlet for releasing non-evaporated parts of the substance from the treatment chamber, a second outlet for releasing evaporated parts of the substance from the treatment chamber, and a rotary mechanism comprising a rotatable axle arranged within the treatment chamber having an orientation directed along the treatment chamber's length l.sub.c and a mixing device fixed to, and extending perpendicular from, the rotatable axle, wherein a radial outermost part of the mixing device comprises a plurality of radially separated mixing protrusions, a rotary drive operatively connected to the rotatably axis, and a heating device arranged outside the treatment chamber, wherein the heating device is configured to transfer thermal energy to a minimum peripheral volume (Vp) of the treatment chamber via the inner surface, wherein the minimum peripheral volume (V.sub.p) is defined as a volume between the inner surface and outer radial boundaries of the mixing device wherein the mixing device comprises: a plurality of rotary discs fixed with axial offsets to the rotatable axle, and wherein the heating device and the rotary drive are configured such that, when both the heating device and the rotary drive are operated at their respective operational input powers (p.sub.hd, P.sub.rm), a resulting operational temperature (T.sub.op) is obtained within at least part of the minimum peripheral volume (V.sub.p) which is equal or higher than the evaporation temperature (T.sub.e).

2. The method according to claim 1, wherein a ratio between the radial diameter (d.sub.md) of the mixing device and a radial diameter (d.sub.c) of the treatment chamber is between 0.8 and 1.0.

3. The separation apparatus according to claim 1, wherein the plurality of radially separated mixing protrusions is divided into one or more sets distributed axially along the rotatable axle, across the axial length (l.sub.md) of the mixing device, the number of mixing protrusions in each set being defined as the number of mixing protrusions in a complete circle around the rotatable axle when seen along the direction of the rotatable axle, and wherein the number of radially separated mixing protrusions in each set is determined according to the relation
#.sub.mp=C (d.sub.md/v.sub.p,min), where C is a constant equal to, or higher than, 12π, #.sub.mp is the number of the radially separated mixing protrusions in each set, d.sub.md [m] is the radial diameter of the mixing device, and v.sub.p,min [m/s] is a minimum peripheral rotation velocity at a location on each of the mixing protrusions closest to the inner surface.

4. The separation apparatus according to claim 1, wherein the mixing device further comprises a plurality of elongated objects interconnecting the plurality of rotary discs.

5. The separation apparatus according to claim 1, wherein the radially separated mixing protrusions comprises a plurality of radially protruding elements distributed with offsets along the length lc of the treatment chamber.

6. The separation apparatus according to claim 5, when dependent on claim 4, wherein the plurality of radially protruding elements are replaceably connected to the plurality of elongated objects.

7. The separation apparatus according to claim 5, wherein the plurality of radially protruding elements is arranged radially symmetric around the rotatable axle.

8. The separation apparatus according to claim 5, wherein at least one of the plurality of radially protruding elements comprises a disturbing means at or near the end closest to the inner surface, designed to enhance mixing rate of the substance.

9. The separation apparatus according to claim 1, wherein the plurality of radially separated mixing protrusions is divided into one or more sets distributed axially along the rotatable axle, across the axial length (l.sub.md) of the mixing device, the number of mixing protrusions in each set being defined as the number of mixing protrusions in a complete circle around the rotatable axle when seen along the direction of the rotatable axle and wherein the number of radially separated mixing protrusions in each set is determined according to the relation
#.sub.mp=C (d.sub.md/v.sub.p,min), where C is a constant equal to, or higher than, 457E, #.sub.mp is the number of the radially separated mixing protrusions in each set, d.sub.md [m] is the radial diameter of the mixing device, and v.sub.p,min [m is] is a minimum peripheral rotation velocity at a location on each of the mixing protrusions closest to the inner surface.

10. The separation apparatus according to claim 1, wherein the heating device is configured to provide at least 60% of the total thermal energy required to reach and maintain the operational temperature (T.sub.op) within the at least part of the minimum peripheral volume (V.sub.p).

11. The separation apparatus according to claim 1, wherein the treatment chamber has a cylindrical shape with a radial diameter dc, wherein the ratio between the treatment chamber's length l.sub.c and the treatment chamber's radial diameter d.sub.c is equal or less than 4.0.

12. The separation apparatus according to claim 1, wherein at least one of the plurality of rotary discs displays at least one through-going opening for allowing the evaporated parts of the substance flow through during operation.

13. The separation apparatus according to claim 12, wherein the at least one through-going opening is designed radially symmetric around the rotational axis.

14. The separation apparatus according to claim 1, wherein the vessel further comprises: a plurality of inner ribs ananged on at least part of the inner surface, wherein each inner rib is protruding radially into the treatment chamber.

15. The separation apparatus according to claim 14, wherein the plurality of inner ribs are distributed with offsets around the circumference of the inner surface.

16. The separation apparatus according to claim 1, wherein the heating device further comprises: an enclosure arranged around the vessel such that a void is created between an outer surface of the vessel wall and an inner surface of the enclosure, wherein the enclosure comprises a heat inlet for feeding heated fluid into the void and a heat outlet for releasing said heated fluid from the void.

17. The separation apparatus according to claim 1, wherein at least a part of the void comprises a plurality of outer fins (16) extending in direction perpendicular to the length direction of the treatment chamber.

18. The separation apparatus according to claim 1, wherein the heated fluid is at least one of steam, hot vapor, molten matters, heated liquid, surplus exhaust from a generator and surplus exhaust from an engine.

19. The separation apparatus according to claim 1, wherein the heating device comprises at least one heating elements arranged within the vessel wall.

20. The separation apparatus according to claim 1, wherein the separation apparatus further comprises: a feeding device for feeding the flow of the substance into the treatment chamber, a scrubber for scrubbing evaporated parts of the substance released from the second outlet during operation and a solid discharge tank for collection of non-evaporated parts of the substance released from the first outlet during operation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0222] Following drawings are appended to facilitate the understanding of the invention. The drawings show embodiments of the invention, which will now be described by way of example only, where:

[0223] FIG. 1 is a schematic side view of a separation apparatus according to the invention.

[0224] FIG. 2 is a schematic side view of a separation assembly according to the invention.

[0225] FIG. 3 is a perspective cut-off side view of a first embodiment of a separation apparatus according to the invention.

[0226] FIG. 4 is a perspective cut-off side view of the separation apparatus of FIG. 3, wherein inner ribs are arranged on the vessel's inner surface.

[0227] FIG. 5 is a perspective cut-off front view of the separation apparatus of FIG. 3, wherein the cut-off plane is located further into the apparatus' vessel.

[0228] FIG. 6 is a perspective cut-off side view of a peripheral part of the separation apparatus shown in FIG. 3, wherein one radially protruding element is shown in further details in a separate drawing.

[0229] FIG. 7 is a perspective side view of the separation apparatus of FIG. 3-5.

[0230] FIG. 8 is a perspective cut-off side view of a second embodiment of a separation apparatus according to the invention, wherein one turbulence generating elongated object is shown in further details in a separate drawing.

[0231] FIG. 9 is a perspective cut-off side view of the separation apparatus of FIG. 8, wherein inner ribs are arranged on the vessel's inner surface.

[0232] FIG. 10 is a perspective side view of a rotary mechanism of a separation apparatus according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0233] In the following, embodiments of the invention will be discussed in more detail with reference to the appended drawings. It should be understood, however, that the drawings are not intended to limit the invention to the subject-matter depicted in the drawings.

[0234] It is appreciated that certain features of the invention, which, for clarity, are described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which, for brevity, have been described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination. In particular, it will be appreciated that features described in relation to one particular embodiment may be interchangeable with features described in relation to other embodiments.

[0235] With particular reference to FIG. 1 showing a first embodiment of the invention, the separation apparatus 100 is configured to perform continuous thermal separation of a substance 12 flowing into a treatment chamber 2 inside a cylindrical vessel 1 having an inner surface 1a and an outer surface 1b. The vessel includes a cylindrical wall of inner length 1, and two circular end walls of inner diameter d, (or alternatively oval or rectangular or squared with height H and width W) arranged on each ends of the cylindrical wall.

[0236] The substance 12 fed into the substance inlet 3 by use of a feeding device 20 (FIG. 2) is composed of multi-components (A.sub.n, where n>1), where one or more of these components 12b (A.sup.e.sub.m, where m≤n) are evaporable with distinct evaporation temperatures (T.sup.e.sub.i, where i=1 . . . m). Hence, a part 12a of the substance 12 (A.sub.n-m) may be considered non-evaporable within a set operational temperature (T.sub.op≥T.sup.e.sub.i) inside the treatment chamber 2. The non-evaporable and the evaporable parts 12a,12b are released from the vessel 1 through a first and second outlet 4,5, respectively. During operation a vapor cloud 12c is formed comprising a mix of non-evaporable parts 12a and evaporable parts 12b. Said vapor cloud 12c includes both fluids (gas and/or liquids) and solids/particles.

[0237] The vessel 1 contains a rotatory mechanism 7 having a rotatable axle 7a aligned with a central, longitudinal axis C of the vessel 1. The axle 7a extends across the length L of the vessel 1 and through at least one of the end walls, preferably both.

[0238] The rotatory mechanism 7 further includes a mixing device 7b-d fixed to the rotatable axle 7a inside the treatment chamber 2. The mixing device 7b-d comprises at least one, preferably at least two, rotary sheaves or discs 7b rigidly fixed perpendicularly onto the axle 7a and a plurality of mixing protrusions/protruding elements 7d fixed at the outer radial end of the discs 7b. In case of a plurality of discs 7b, these are arranged with spacings/offsets along the axle's 7a longitudinal direction (i.e. along axis C). In FIG. 1, a total of seven spaced-apart discs 7b are shown, where all discs except the leftmost disc displays openings 7b 1 near the axle 7a, thereby allowing evaporated components 12b to flow therethrough. The main purpose of the single closed disc 7b arranged nearest the end wall displaying the substance inlet(s) 3 (see FIG. 7) is to hinder the solids from the vapor cloud 12c to enter the volume between the rotatable axle 7a and the protruding elements 7d, thereby avoiding solids to mix with evaporated parts 12b and to be released through the second outlet 5.

[0239] To further prevent solids from escaping the second outlet 5, a narrow slit composed of two circumferentially extending plates 23 have been fixed to the disc 7b nearest the second outlet 5 and the adjacent inner wall 1a, respectively.

[0240] The mixing device 7b-d further comprises a plurality of bars 7c fixed at or near the discs' 7b outer rims 7b2, where each of the bars 7c has a length and an orientation directed along (parallel with) the vessel's 1 central axis C which allows interconnection of two or more of the discs 7b, and preferably interconnections of all of the discs 7b.

[0241] For the first embodiment depicted in FIGS. 1-6, the mixing device 7b-d also comprises a plurality of rods 7d replaceably connected to each bar 7c such that they protrude radially towards the inner surface 1a of the vessel's 1 cylindrical wall, i.e. perpendicular to the vessel's 1 central axis C. The main purpose of the rods 7d is to create intense mixing of the vapor cloud 12c to enhance the heat transfer from the inner wall 1a.

[0242] With the particular configuration shown in FIG. 1, experiments show that an intense mixing of the vapor cloud 12c was achieved with a peripheral velocity v.sub.p of 34.5 m/s measured at the ends of the rods 7d closest to the inner vessel walls. During the experiments, a mixing device 7a-d with sets of eight rods 7d (#.sub.mp=8) distributed with spacings along the entire mixing device length lmd. The eight rods 7d of each set is further distributed with spacings along the entire circumference of the mixing device 7b-d. The mixing device 7b-d had a diameter d.sub.md of 1,1 m and the inner vessel diameter d.sub.c was 1.2 m.

[0243] A peripheral velocity of 34.5 m/s with this particular configuration corresponds to a revolution velocity ω.sub.rev of 600 rounds per minutes (r.p.m). With eight rods 7d along the mixing device's circumference, this corresponds to 4800 sweeps per minute (s.p.m.) across a specific area of the inner vessel wall 11a.

[0244] If one decide to keep the number of sweeps constant, it can be deduced that the minimum peripheral rotation velocity v.sub.p,min at the outer radial boundary of the rods/mixing protrusions can be formulated as follows:

v.sub.p,min=80π(d.sub.md/#.sub.mp),

where d.sub.md is the diameter of the mixing device and #.sub.mp is the number of mixing protrusions.

[0245] Further experiments show that vapor cloud with turbulent characteristics can be achieved with a number of s.p.m. significantly lower than 4800, at least down to 2700 s.p.m. This corresponds to a minimum peripheral rotation velocity of

[0246] v.sub.p,min=45π(d.sub.md/#.sub.mp). With particular reference to FIG. 6, the shape of the end 7d1 of each rod 7d situated nearest the inner surface 1a may be varied to optimize said mixing of the vapour cloud in a minimum peripheral volume V.sub.p delimited by the radial extent of the rotary mechanism 7 and the inner surface 1a. As shown in the detailed drawings within the oval frame of FIG. 6, the termination of the rod 7d may be flat, or near flat, relative to the facing inner surface 1a. However, the ends 7d1 may be of any shape as long as they contribute to the mixing of the vapor cloud 12c present in the minimum peripheral volume V.sub.p. The detailed drawing within the oval frame in FIG. 1 shows various examples of possible shapes of the ends 7d1. Note that the exemplary rods 7d within the oval frame of FIG. 1 are all turned 90° counterclockwise in respect of the rods 7d shown within the vessel 1.

[0247] To ensure rotation of the rotatory mechanism 7, and thereby also the mixing device 7b-d, an end section 7a1 of the axle 7a is connected to a rotary drive 10. As shown in FIG. 2, the latter is powered by an internal and/or external rotary motor 10a. In the exemplary configuration shown in FIG. 2, the rotary drive 10 comprises a rotary motor 10a, a transmission belt 10b and two transmission pulleys 10c arranged around the end section 7a1 and a rotatable axle of the rotary motor 10a, respectively.

[0248] The first outlet 4 is dedicated for releasing solid-state particulates (non-evaporated parts) 12a, while the second outlet 5 is dedicated for releasing the evaporated parts 12b. In order to avoid release of vapor out of the treatment chamber 2 through the first outlet 4, a rotary valve 22 (FIG. 1) is fixed to the first outlet 4, thereby discharging the non-evaporated parts 12a from the first outlet 4.

[0249] After being released from the first outlet 4 through the rotary valve 22, the non-evaporated part 12a may be collected by a dedicated solid discharge container 40 arranged below, or partly below, the vessel 1 (FIG. 2).

[0250] In order to monitor the temperature inside the vessel 1, one or more temperature sensors 19 at various locations may be arranged within or near the treatment chamber 2, for example outside or within the vessel wall and/or within the first outlet 4. The latter position is depicted in FIG. 1.

[0251] The vapor 12b may be fed into a condensing system 30. The latter may be performed in three steps: [0252] The vapor 12b is flowing into a gas scrubber to clean the vapor 12b for minor amounts of solid-state particulates. A small amount of a first liquid such as oil may also be condensed within the gas scrubber. [0253] The cleaned vapor 12b is further flowing into a liquid condenser, for example an oil condenser, to condense the first liquid from the vapor 12b. [0254] Lastly, the cleaned vapor having no or reduced amount of the first liquid (for example lighter oil) is flowing into a steam condenser which condense at least a second type of liquid such as water and, if applicable, the reduced amount of the first liquid.

[0255] In FIG. 1, the first outlet 4 and the second outlet 5 are seen arranged adjacent the end wall distal the rotary drive 10, wherein their openings out of the vessel 1 are directed along the central axis C and tilted down relative to the central axis C, respectively. However, the first and second outlets 4,5 may be configured in any direction as long as they allow release of non-evaporated and evaporated parts 12a,12b during operation. FIGS. 3-5 and 7 of the first embodiment and FIGS. 8-9 of the second embodiment show an alternative configuration of the first outlet 4 having a vertical opening out from the treatment chamber 2 at the vessel's 1 base.

[0256] The total radial diameter d.sub.md of the rotatory mechanism 7/mixing device 7b-d, i.e.

[0257] twice the total radial length from the central axis C to the rotatory mechanism's 7 radial boundary, is preferably more than 95% of the diameter d.sub.c of the treatment chamber 2. For example, if the inner diameter d.sub.c of the cylindrical vessel 1 is 2 meters, the average distant between the end 7d1 of each plurality of rods 7d and the inner surface 1a should preferably be less than 10 cm, for example 3 or 4 cm.

[0258] In all of the exemplary configurations of FIGS. 1 and 3-9, a heating device 6 is depicted as an assembly comprising both [0259] a plurality of resistive heating elements in the shape of poles/rods 6″ arranged within the vessel wall along (i.e. parallel with) the central axis C and [0260] a hot fluid system arranged around the cylindrical wall comprising an enclosure 13 forming a void 14 between an inner surface of the enclosure 13 and the outer surface 1b of the vessel 1. The enclosure 13 further comprises a heat inlet 13a for feeding heated fluid 6′ into the void 14 and a heat outlet 13b for releasing the heated fluid 6′ out of the void 14.

[0261] However, note that the heating device 6 may comprise any types and any number of heating mechanisms capable of heating the inner wall 1a of the vessel 1. For example, in alternative embodiments the heating device 6 may consist of only one or more resistive heating elements within and/or outside the container wall or consist of only said hot fluid system. The heating device 6 may alternatively, or in addition, comprise a microwave heater system and/or an induction heater system arranged on or near the outer surface lb of the vessel 1 and/or inside the treatment chamber 2.

[0262] FIG. 7 shows a separation apparatus 100 where one of the end walls of the vessel 1 displays two substance inlets 3, an opening for the rotatable axle 7a and an inspection/service hatch 18. It should however be understood that this end wall may comprise any number of substance inlets 3 and any number of hatches 18. For the particular configuration shown in FIG. 7, only one of the two substance inlets 3 are used during operation. The other may be closed, for example by the same material as the remaining part of the vessel 1 or with transparent glass. Alternatively, the substance 12 may be fed through both inlets 3 during operation.

[0263] The black arrows 6′ pointing into the heat inlet 13a and out of the heat outlet 13b, respectively, symbolize the flow of hot fluid.

[0264] FIGS. 8 and 9 show a second embodiment of the separation apparatus 100. Compared to the first embodiment, the plurality of rods 7d are omitted. The rotary mechanism 7 thus comprises the rotatable axle 7a and the mixing device 7c-d, where the latter is set up by a plurality of discs 7b and interconnecting bars 7c. The desired mixing of the substance 12 within the minimum peripheral volume V.sub.p is consequently largely ensured by the longitudinally directed bars 7c.

[0265] To enable maximized mixing, preferably to the extent that the vapor cloud 12c experiences a turbulent flow characteristic within V.sub.p, the shape of the bars 7c may be optimized, for example through repeated testing in which various shapes of the bars 7c are inserted and operated, and where the heat transfer is measured during each operation. FIGS. 8-9 show one exemplary configuration of the bars 7c where the longitudinal cross-sectional area displays has a triangular shape. The sharp edges 7c 1 of the triangular bar 7c may induce more turbulence in the minimum peripheral volume and intense mixing of the vapour cloud 12c.

[0266] The above described separation apparatus 100 enables effective removal of liquids and/or gases from a substance 12 by thermal separation, using for example waste heat 6′ as the main indirect energy for separation of waste and bi -products. Due to the combined external heating of the vessel 1 and the fierce mixing of the substance components/vapor cloud 12c, the separation apparatus 100 can operate continuously without the presence of a net internal transport mechanism causing a gradual heating of the substance 12 (as necessary in the currently known indirect separation methods).

[0267] By use of the above described apparatus 100, the heat is not transferred mainly to the solids in the waste, as case is for indirect separation methods. Instead, the heat is transferred to the vapor cloud 12c having much higher heat transfer coefficient. This vapor cloud 12c is composed of mainly (by volume) evaporated liquids/gases, and also hot non-evaporated particles. If water is present in the incoming substance 12, the ‘evaporated’ vapor cloud 12c will necessarily contain steam.

[0268] During operation, the following process steps take place: [0269] The heating device 6 and the rotary mechanism 7 cause the incoming substance 12 to transform into a vapor cloud 12c. [0270] The thermal energy from the heating device 6 is transferred from the inner surface 1a of the vessel 1 to the generated vapor cloud 12c. [0271] The thermal energy is subsequently transferred from this heated vapor cloud 12c onto the incoming substance 12 by intense mixing/turbulence from the rotary mechanism 7.

[0272] The heat transfer from steel to a dried solid typically found in prior art indirect heating separators is experienced to be ca. 75 W/m.sup.2K. In comparison, the heat transfer from steel to steam (which will be a typical main ingredient of the vapor cloud 12c during thermal separation of waste) is significantly higher, typically ca. 6000 W/m.sup.2K.

[0273] Hence, by heating the substance 12 via the above-mentioned heating steps the inventive apparatus achieves a heat transfer capacity significantly higher than 75 W/m.sup.2K (but below 6000 W/m.sup.2K).

[0274] The final heat transfer will depend inter alia on the water content. For example, a heat transfer coefficient between 1000 and 1200 W/m.sup.2K has been verified when thermal separation tests have been performed on a substance containing approx. 15% water, 15% oil and 70% non-evaporable substance (by weight). The latter is typical composition for cuttings after drilling operations.

[0275] As mentioned above, the intense mixing/turbulence mechanism will secure an optimal mixing and heat exchange from the vapor cloud 12c onto the continuously fed substance 12 through the substance inlet 3 and the various components in this substance, thereby causing an almost instant evaporation of in particular liquids within the substance 12. The vessel 1 will thereby—at all times—contain a vapor cloud 12c with optimal heat transfer capabilities, both from the inner surface 1a as well as onto the incoming substance 12.

[0276] Although particles in any created vapor cloud will necessarily be forced to the periphery of the treatment chamber by centrifugal forces, the continuous evaporation of liquids (such as water) will create strong internal forces in all internal directions, thereby securing a high percentage of vapor (steam) at the periphery.

[0277] Tests with the inventive separation apparatus has been performed while treating a waste substance containing 70% mineral solids, 15% water and 15% oil by weight (cuttings from drilling operations). The tests demonstrated a heat transfer rate between approx. 1000 W/m.sup.2K and 1200 W/m.sup.2K. Even higher heat transfer rates are expected for substances containing more water.

[0278] In the preceding description, various aspects of the apparatus and the method according to the invention have been described with reference to the illustrative embodiment. For purposes of explanation, specific numbers, systems and configurations were set forth in order to provide a thorough understanding of the apparatus and its workings. However, this description is not intended to be construed in a limiting sense. Various modifications and variations of the illustrative embodiments, as well as other embodiments of the apparatus and the method, which are apparent to persons skilled in the art to which the disclosed subject matter pertains, are deemed to lie within the scope of the present invention.