Patent Application
20110079044
The present invention relates to a technique for separating a liquid/liquid mixture or a liquid/solid mixture.
A technique for separating liquid/liquid mixtures and solid/liquid mixtures includes filtration (Perry Robert H. Perry's Chemical Engineers' Handbook, 6th ed., pp. 19.65-19.89, 1984) (this hand book is referred to as the “Perry document” hereinafter). In the filtration, a mixture to be separated (solid-liquid mixture or liquid-liquid mixture) is supplied to a filter layer made of a porous material (diatomaceous earth), a fibrous material, or the like, and a liquid is passed through the filter layer due to differential pressure (such as centrifugal force) while a solid is captured in the filter layer. Alternatively, a low-viscosity liquid is passed through the filter layer, while a high-viscosity liquid and/or a solid are captured in the filter layer and separated. With respect to the low-viscosity liquid and the high-viscosity liquid, a liquid and a liquid immiscible therewith (hereinafter referred to as an “immiscible liquid”) (a plurality of immiscible liquids may be contained) in a liquid-liquid mixture are regarded as the low-viscosity liquid and the high-viscosity liquid, respectively, by a relative comparison of viscosities.
In the filtration, it is a difficult problem to improve recovery and a recovery rate (=recovery amount/capture amount) of substances captured in the filter layer. The filtration also includes separation by a membrane (such as ultra filtration membrane). Methods for improving a recovery rate of captured substances include a method using an organic solvent (such as hexane) (Perry, pp. 15 1-15 20). However, this method may cause deterioration of the captured substances. In addition, a solvent is generally recovered by an evaporation method, thereby increasing the cost of the method (a large quantity of heat energy is required for evaporating the solvent).
It is considered that filter crystals described below can be used as filter media for capturing viscous solutions and solids. The filter crystals are the followings:
a) Fine crystals (which may be grains), needle/rod-like crystals, dendrite-like crystals, or flake/plate-like crystals produced in a liquid; crystals produced by removing or scraping the crystals formed by contact between a cooled solid material such as metal and a liquid; or crystals by grinding (such as impact grinding using rotation centrifugal force) or crystals by crushing after their formation.
b) Crystals produced by mixing a mother liquid in a gas by low-temperature evaporation, heating evaporation, spraying, or liquid dropping, forming crystals by contact between the resultant mixture and a cooled solid (such as metal) or a solid (such as plastic), and removing or scraping the crystals from the cooled solid or the solid.
c) A crystal group including the above-described crystals a) and/or b).
The filter crystals are deliquescent single crystals and/or polycrystals. Possible substances for the filter crystals include materials such as ice.
It is known from documents below that filter crystals can be formed in liquid by rapid crystallization of single-component liquids or rapid crystallization of multi-component liquids.
With respect to formation of ice crystals from an aqueous solution, Thijssen, H. A. C., A. Spicer ed., Applied Science Pub. LTD., London UK, p. 117-121, 1974 (hereinafter referred to as the “Thijssen document”) discloses the followings:
1. In cooling from a cooled surface (unidirectional cooling), needle-like or rod-like ice crystals having branches crossing perpendicularly to the cooled surface are formed.
2. In a liquid, an amount of fine crystals increases (the occurrence rate of crystal nuclei (fine ice) increases) with increasing cooling rate or increasing solute concentration.
3. Ice crystals increase in size over time.
With respect to freezing of water, Y. FURUKAWA and E. YOKOYAMA, JASMA Vol. 21, 217-223 2004 discloses that an amount of dendrite crystals increases with increasing cooling rate.
In addition, PETER V. HOBBS, CLARENDON PRESS OXFORD, p. 580-581 1974 discloses that dendrite crystals are easily formed from an aqueous solution as compared with water.
Examples of materials other than water that can be used for filter crystals of the present invention include clathrate hydrates (U.S. Pat. No. 6,237,346 B1) and the like.
U.S. patents (U.S. Pat. No. 3,845,230 and U.S. Pat. No. 3,320,153) disclose techniques in which a solid-liquid mixture or a liquid passes through a layer composed of ice crystals. The U.S. Pat. No. 3,845,230 discloses a centrifugal dehydration (filtration) method for forming an ice crystal layer using a rotating basket described below in “Detailed Description of the Invention”. Also it is described that spherical ice crystals are formed by extending a residence time during slow freezing and that fine ice crystals are produced by shortening a residence time during rapid freezing. The U.S. Pat. No. 3,320,153 relates to a technique for separating oil and a mixture of ice crystals and solidified wax.
A type of formation of filter crystals in a gas includes natural snow.
It is known that filter crystals can be formed in an artificial gas as follows: A liquid is mixed in a gas by low-temperature evaporation, heating evaporation, spraying, or liquid dropping, and the resultant mixture is put into contact with a crystal forming material or a cooled crystal forming material to produce a liquid solidified product (artificial snow) (Mitsuo, et al. Trans. of the JSRAE, Vol. 25, pp. 325-335 2008).
Documents explaining a filter layer and a fluid mixture to be passed through the filter layer according to the present invention are described below. According to these documents, the following matters are found. 1) A filtration is considered as a method capable of separating a liquid-liquid (a high-viscosity liquid and a low-viscosity liquid) mixture by capturing the high-viscosity liquid by a crystal-filter layer and passing the low-viscosity liquid through the crystal-filter layer. 2) A filtration has the function to coalesce immiscible droplets or small solids.
a) Based on research of freeze concentration (separation between ice crystals and concentrate), the Thijssen document describes on pp. 130-132 the following. In a method for separating between ice crystals and a liquid (squeezing, centrifugal dehydration, and washing), a permeation rate of the liquid (filtrate amount per unit area and time) is inversely proportional to the viscosity of the liquid and the filter layer thickness (filter layer passage distance of a mixture to be separated) and is proportional to the square of a mean crystal diameter. The Thijssen document also describes that in centrifugal filtration of ice crystals and a liquid, the amount of a liquid remaining in the filter layer is proportional to the viscosity of the liquid, and that the amount of remaining liquid decreases with increasing centrifugal effect (G).
b) In regard to centrifugal filtration, Masao et al., AlChEJ, Vol. 33, pp. 109-120 1987 and Perry document 19.96-19.103 describe the following: The permeation flow rate decreases as the viscosity of a liquid increases and the filter layer thickness increases (the filter layer passage distance of a mixture to be separated increases). In addition, the permeation flow rate increases with increasing centrifugal effect (G) and with increasing rotation time.
In Spielman, L. A. and Goren, S. L., Ind. Eng. Chem., Vol. 62, No. 10, p. 10-24 (1970), U.S. Pat. No. 4,335,001, and S. D. Rege, H. S. Fogler, AlChE Vol. 34, 1988, it is described that the filtration has the function to coalesce small solids or immiscible droplets (such as emulsion) in a mixture to be separated.
In the document of Spielman, L. A. and Goren, it is also described that the larger solids or droplets (the larger aggregates), the more easily the solids or droplets are captured in a filter layer.
In the present invention, considering the coalescing function (facilitating subsequent separation) of the filter layer, the coalescing function may be used as pre-treatment for separation of the mixture to be separated regardless of the presence of capture in the filter layer.
The document of Spielman and Goren further describes that a difference in permeability occurs between a high-viscosity liquid and a low-viscosity liquid when a mixture of these liquids is passed through the filter layer.
The present invention provides a method and an apparatus using a deliquescent filter medium for separating a mixture to be separated (solid-liquid or liquid-liquid mixture). The mixture to be separated is separated into a liquid passing through a crystal-filter layer which is made of the deliquescent filter medium and a captured material captured in the crystal-filter layer.
The present invention relates to a method having advantages such as the followings:
1. A filter medium and a captured material are separated by melting the filter medium. Thus, the capturing material and the captured material are easily separated.
2. Further, when a low-temperature material such as ice, snow, or the like is used as the filter medium, corruption and deterioration can be delayed in treatment of natural products and the like.
3. In a preferred embodiment of the present invention, components with a small difference in specific gravity in a mixture to be separated can also be separated.
Typical examples of a method using a deliquescent filter medium of the present invention are described below.
A method according to the present invention is a method for separating a mixture to be separated including a) a step of forming mother liquid crystals from a mother liquid, b) a step of forming deliquored filter crystals by deliquoring the mother liquid crystals, c) a step of forming a crystal-filter layer of the deliquored filter crystals and supplying a mixture to be separated to a surface of the formed crystal-filter layer to separate the mixture to be separated into a passing liquid passing through the crystal-filter layer and a crystal-filter layer supporting wall having holes, and a captured material captured in the crystal-filter layer, d) a step of melting the crystal-filter layer among the crystal-filter layer and the captured material captured in the crystal-filter layer, and e) a step of separating, by gravity settling, the melted crystal-filter layer and the captured material captured in the crystal-filter layer.
Another method according to the present invention is a method for separating a mixture to be separated including a) a step of forming filter crystals from a mother liquid, b) a step of forming a crystal-filter layer of the filter crystals and supplying a mixture to be separated to a surface of the formed crystal-filter layer to separate the mixture to be separated into a passing liquid passing through the crystal-filter layer and a crystal-filter layer supporting wall having holes, and a captured material captured in the crystal-filter layer, c) a step of melting the crystal-filter layer among the crystal-filter layer and the captured material captured in the crystal-filter layer, and d) a step of separating, by gravity settling, the melted crystal-filter layer and the captured material captured in the crystal-filter layer.
Outlines of apparatuses constituting a system are described.
Each of the apparatuses constituting the systems is described below.
The crystal generator 2 is an apparatus for forming mother liquid crystals 2a. The crystal generator 2 produces the mother liquid crystals 2a by cooling a mother liquid 1a.
The mother liquid crystals 2a are crystals, a mixture of crystals and the mother liquid 1a, filter crystals 100, or a mixture of the filter crystals 100 and the mother liquid 1a. When the mother liquid 1a is a multi-component liquid, a liquid in the mixture has a solute concentration different from the mother liquid 1a.
The mother liquid crystals 2a are transferred to the deliquoring device 3, the separator 6, or a deliquoring separator described below.
The deliquoring device 3 is an apparatus that forms deliquored filter crystals 3a.
The mother liquid crystals 2a are deliquored by passing through a mother liquid crystal supporting wall (a basket- or drum-like wall, a filter cloth, a screen, or the like) having holes in the deliquoring device 3 (due to centrifugal force, differential pressure, or combination thereof). Alternatively, the deliquoring is combined with high-speed rotation crystal impact (ejection) grinding, crystal crushing, or the like to form the deliquored filter crystals 3a (removed liquid is referred to as a “deliquored liquid 4a”). The deliquored filter crystals 3a are filter crystals, or a mixture of filter crystals and the mother liquid 1a.
The deliquoring efficiency may be low.
The deliquored liquid 4a is transferred to a deliquored liquid tank 4.
The deliquored liquid 4a may be reused as the mother liquid 1a (to the crystal generator 2). Reuse of the deliquored liquid 4a has the possibility as a supply for a new mother liquid 1a to the mother liquid tank 1, energy for cooling (or heating) the mother liquid 1a, or low-cost, energy-saving method and apparatus due to the reduction of disposal of the deliquored liquid 4a and the like. When the mother liquid 1a is a multi-component liquid, the deliquored liquid 4a has a solute concentration different from the mother liquid 1a. In this case, the deliquored liquid 4a may be adjusted to the same solute concentrated as the mother liquid 1a.
The deliquored filter crystals 3a are transferred to the separator 6.
The separator 6 is an apparatus that separates a mixture to be separated (liquid-liquid, solid-liquid) by a crystal-filter layer 6a and a crystal-filter layer supporting wall 600 having holes.
The crystal-filter layer supporting wall 600 having holes is a basket- or drum-like supporting wall, a filter cloth, a screen, or the like.
The deliquored filter crystals 3a from the deliquoring device 6 or the mother liquid crystals 2a from the crystal generator 2 are transferred to the separator 6, forming a filter layer (hereinafter the “crystal-filter layer 6a”) including the crystals as a filter medium in the separator. Natural snow or the like may be transferred as the filter crystals to the separator. The deliquored filter crystals 3a, the mother liquid crystals 2a, or the filter crystals 100, which are transferred to the separator, may be accompanied by a liquid.
Next, a mixture 5a to be separated is supplied to a surface of the crystal-filter layer 6a (in which centrifugal force, differential pressure, or combination thereof is exerted in the separator 6).
The mixture 5a to be separated is separated into a passing liquid 7a which passes through the crystal-filter layer 6a and the crystal-filter layer supporting wall having holes, and a captured material captured in the crystal-filter layer.
When the mixture to be separated is a liquid-liquid mixture, a low-viscosity liquid (an aqueous solution or the like) in the mixture to be separated passes through the crystal-filter layer 6a and the crystal-filter layer supporting wall 600 having holes, and discharged to the outside of the crystal-filter layer supporting wall, while a high-viscosity liquid 8b (oil or the like) is captured in the crystal-filter layer.
On the other hand, when the mixture 5a to be separated is a solid-liquid mixture, a liquid in the mixture to be separated passes through the crystal-filter layer 6a and the crystal-filter layer supporting wall 600 having holes, and discharged to the outside of the crystal-filter layer supporting wall, while a solid 8c is captured in the crystal filter-layer 6a. Further, when a liquid in a solid-liquid mixture includes a liquid and an immiscible liquid like in the liquid-liquid mixture, the high-viscosity liquid 8b may be or not be captured in the crystal-filter layer according to applications of the present invention.
Further, for the purpose of separating a plurality of immiscible liquids in liquid-liquid and liquid-solid mixtures, the present invention may be used as a method and apparatus for separating a high-viscosity liquid and a low-viscosity liquid in immiscible liquids on the basis of the same principle (a difference in viscosity between immiscible liquids) as in the liquid-liquid mixture.
Also, the present invention may be used as a separation (wintering or the like) method and apparatus utilizing a difference in freezing point.
In addition, the mother liquid crystals 2a formed by the crystal generator 2 may be transferred to a deliquoring separator. The deliquoring separator continuously performs the operations of the deliquoring device 3 and the separator 6 in a single apparatus. Through (a) a step of supplying mother liquid crystals, (b) a deliquoring step, (c) a step of supplying the mixture to be separated, and (d) a step of discharging a capturing crystal-filter layer (described below), in the deliquoring separator, a low-viscosity liquid in the mixture 5a to be separated which is supplied in step (c) passes through the crystal-filter layer and the crystal-filter layer supporting wall having holes, while a high-viscosity liquid 8b and/or a solid are captured in the crystal-filter layer.
In the present invention, before supply, the temperature of the mixture 5a to be separated may be decreased to produce a solidified matter (the same material as the filter crystals, solidified oil, or the like) in the mixture 5a to be separated. An example of the present invention method where a solidified matter in the mixture 5a to be separated is the filter crystal is described with reference to a filter aid.
After the above-described operations, the liquid 7a passing through the crystal-filter layer 6a and the crystal-filter layer supporting wall 600 is transferred to a passing liquid tank 7. In addition, the crystal-filter layer 6a and the captured material are transferred to an apparatus (melting tank 8 or the like) for melting the crystal-filter layer.
The captured material includes the high-viscosity liquid 8b and/or the solid 8c captured in the crystal-filter layer 6a. Hereinafter, the crystal-filter layer 6a containing the captured material is referred to as a “capturing crystal-filter layer 6b”.
In addition, in the present invention, the same as the passing liquid 7a or components thereof may be captured in the capturing crystal-filter layer 6b within a range in which the intended purpose of the system of the present invention can be achieved.
The crystal-filter layer in the capturing crystal-filter layer is melted with an apparatus for melting the crystal-filter layer (hereinafter, a material containing a melt of the crystal-filter layer as a main component is referred to as a “melt”). The melting is performed by heating (due to a difference in temperature between the inside and outside of a heater, a melting device, or the like).
During melting of the crystal-filter layer, a solid (solidified oil or the like) in the capturing crystal-filter layer may be or not molten according to the intended purpose of the system according to the present invention.
The separated melt 8a may be used (reused) as the mother liquid 1a of the crystal generator 2. In this case, reuse has the possibility as a supply for a new mother liquid 1a to the mother liquid tank 1, energy for cooling (or heating) the mother liquid 1a, or a low-cost, energy-saving method and apparatus due to the reduction of disposal of the melt 8a and the like. Also, the reuse of the melt 8a has the possibility of decreasing the filter medium cost for changing the filter medium and/or the cost for treating (disposal or the like) the filter medium after use as compared with conventional filtration.
Details of the apparatuses constituting the system are described below.
The crystal generator is an in-liquid or in-gas type apparatus. In the in-liquid type apparatus, crystals are generated (solidification of a mother liquid) using a cooled solid (metal or the like) or a cooled fluid (gas, liquid) (brought into contact with a mother liquid) in a mother liquid, and the crystals are removed or scraped. In the in-gas apparatus, a mother liquid is mixed in a gas by low-temperature evaporation, heating evaporation, spraying, or liquid dropping, the resultant mixture is brought into contact with a cooled solid (metal or the like) or a solid (plastic or the like) to produce crystals (solidification of the mother liquid), and the crystals are removed or scraped.
In-liquid type apparatuses for generating crystals on a cooled solid include a rotating drum type 21 (
The cooled solid is generally cooled using a refrigerator. However, when the mother liquid is at high temperature, the cooled solid may be cooled by fan cooling, water cooling, or the like without using a refrigerator. When the cooled solid is cooled with a refrigerator, a cooling medium may be either refrigerant or brine.
In the in-liquid type apparatus for producing crystals (solidification of a mother liquid) using a cooling fluid (gas or liquid), examples of a cooling gas include normal butane gas and iso-butane gas (Herbert, F., Advance in Chemistry Series, No. 27, pp. 82-89 1960), and examples of a cooling liquid include hydrofluoroether (inert antifreezing liquid) (3M Co., USA).
The in-gas type apparatus includes an evaporation type, a spraying type, a dropping type, and the like, and methods thereof include a low-temperature evaporation method, a heating evaporation method, an ultrasonic method, a centrifugal method, a high-pressure spraying method, a two-fluid spraying method, and the like. The general characteristics of these in-gas apparatuses are described, together with the low-evaporation method (
Also, an apparatus of a type in which the mother liquid 1a is dispersed on a cooled surface to produce a solidified matter, which is then scraped, can be used as the crystal generator 2.
The crystal generator 2 may be a crushing-type apparatus in which large or small crystal lumps (lamps of ice or the like) are crushed.
The mother liquid 1a may be continuously or discontinuously supplied in a necessary amount to the crystal generator 2 from the mother liquid tank 1. The mother liquid temperature in the mother liquid tank 1 may be controlled to a necessary temperature by a heater or the like.
The shape and size of crystals produced by the crystal generator are adjusted by controlling the temperatures of the cooled solid, a solid, or the cooled fluid (gas or liquid) used for forming crystals (solidification of the mother liquid) in the crystal generator, the moving velocity of the cooled solid, a solid, or the cooled fluid (gas or liquid), the removal or scraping rate of crystals, and the like. Devices for moving or scraping crystals include a rotating brush, a scraper, a gas spray type device, and the like.
Any one of the deliquoring device 3, the separator 6, and the deliquoring separator can use methods and apparatuses using various filtration techniques (gravitation, pressure application, and pressure reduction) including centrifugal filtration (Perry document, pp. 19.65-19.103).
Among the various filtration techniques, a centrifugal method (Perry document, pp. 19.96-19.100) using a rotating basket as the crystal-filter layer supporting wall 600 having holes and a centrifugal method (Perry document, p. 19.79) using a rotating drum as a crystal-filter layer supporting wall having holes are described below.
The crystal-filter layer supporting wall have many or plural holes which may be elongated holes.
The centrifugal method uses a discontinuous or continuous apparatus described below. Discontinuous types include a filter cloth inverting type 61 (
The general characteristics of these apparatuses are described in the documents below. The filter cloth inverting type 61 (
On the other hand, the drum filtration method includes a pressure method, a pressure reduction method (
The drum filtration method can use a crystal generator for producing filter crystals in a liquid tank in which a drum is immersed, the crystal generator and a deliquoring device, or an apparatus used as the crystal generator, a deliquoring device, and a separator. In this case, as means for generating filter crystals in the liquid tank, a crystal forming cooled surface and a cooled surface scraping blade are provided in the liquid tank, or a cooled gas or an antifreezing liquid is introduced into the liquid tank.
When the crystal-filter layer supporting wall 600 having holes is used in the separator 6 or the deliquoring separator, the average distance between the holes (between the hole outer edges) of the supporting wall 600 is preferably longer than the average thickness (the distance between the surface of the filter layer and the wall surface having the hole) of the filter layer to which the mixture 5a to be separated is being supplied. In this case, the total opening area of the holes of the supporting wall surface having holes is smaller than the wall surface area excluding the opening area of the holes of the wall surface having holes.
This is clearly explained with reference to
The conditions of the supporting wall surface having the holes bring about the following phenomena:
1. The flow rate and distance of the mixture to be separated, which is supplied to the surface of the filter layer, along the supporting wall surface (after flowing through the filter layer from the filter layer surface and reaching the supporting wall surface) are increased. This increases the average flow distance of the mixture to be separated (per unit volume) in the filter layer.
2. The crystal-filter medium is compressed to the supporting wall surface due to differential pressure (centrifugal force or the like). Therefore, after reaching the supporting wall surface from the filter layer surface (without escaping), the mixture to be separated at the above-described flow rate is forced to be moved along the supporting wall surface through the gap between the supporting wall surface and the crystal-filter media, and through the crystal-filter media near the supporting wall surface, the gap being narrowed by compression.
These phenomena significantly increase the capture rate of materials captured in the crystal-filter layer (=amount of materials captured in crystal-filter layer/amount of crystal-filter layer/supply amount of mixture to be separated). This indicates that the amount of the crystal-filter medium for the desired capture rate of the separator or the deliquoring separator can be decreased. In addition, the phenomena have the possibility of enhancing the effect of coalescing immiscible droplets and/or fine solids in the mixture to be separated.
The mother liquid crystals 2a, the deliquored filter crystals, or the filter crystals are preferably supplied to the deliquoring device 3, the separator 6, and the deliquoring separator using a screw feeder or a tube conveyor.
In addition, the mixture 5a to be separated is preferably supplied to the crystal-filter layer in the separator or the deliquoring separator by spraying.
When the centrifugal method is used in the deliquoring device 3, the separator 6, and the deliquoring separator, a screen, a filter cloth, or the like, which rotates together with a basket, may be provided inside the basket. When the drum filtration method is used, a screen, a filter cloth, or the like, which rotates together with a drum, may be provided outside the drum.
The shape and size of the deliquored filter crystals 3a produced by using the centrifugal method in the deliquoring device are preferably controlled by selecting the conditions such as the amount of the mother liquid crystals 2a supplied, the discharge rate of the deliquored filter crystals, the rotational speed of the basket, and the like according to purposes of use of the system.
Besides the conditions of the crystal-filter layer supporting wall, the preferred operation conditions of the separator and the deliquoring separator are preferably selected so as to increase the capture rates by the crystal-filter layer. The operation conditions include the supply amounts and supply rates of the mother liquid crystals 2a, the deliquored filter crystals, the filter crystals, and the mixture 5a to be separated, the differential pressure (centrifugal force or the like) of the crystal-filter layer, and the like. When the separator or the deliquoring separator using the centrifugal method is used for separating a liquid-liquid mixture, the time required for one filtration is preferably short (several seconds or minutes) in order to increase the capture rate of a high-viscosity liquid captured in the crystal-filter layer (to decrease the discharge of the captured high-viscosity liquid from the filter layer). The “time required for one filtration” represents the time required from supply of the mixture to be separated to the crystal-filter layer to discharge of the crystal-filter layer from the basket.
In the present invention, the filter crystals may be used as a filter aid in the separator 6 and the deliquoring separator (pre-coating method or body feed method) (Perry 19.85).
After the above-described operations, the liquid 7a passing through the crystal-filter layer and the crystal-filter layer supporting wall is transferred to the passing liquid tank 7. The crystal-filter layer of the capturing crystal-filter layer is melted using a crystal-filter layer melting device. The melting may be performed by the melting tank 8 or a system including the heater or the like provided in the course thereof without using the melting tank. Further, the melting may be performed in the separator. When the melting is performed in the separator, the melting may be accompanied with gravity settling separation.
After the melting, the mixture can be separated (into the melt, the high-viscosity liquid, and solids) by a gravity settling separation method (gravity separation due to a difference in specific gravity), a disk-type centrifugal separation method (19.92-19.94), a drum-type centrifugal separation method, a continuous decanter separation method (19.94), or a method and apparatus using a membrane, a filter (19.65-19.89), a coalescer, or the like (Perry).
When the melting tank 8 is used, the gravity settling separation method can be performed in the tank.
The melt 8a, the low-viscosity liquid, the high-viscosity liquid 8b, and the solid 8c separated by the above-described separation technique may be contaminated with materials contained in the mixture to be separated and/or in the melt (in amounts within a range in which the object of the preset invention can be achieved). In the whole description of this patent, even when the melt 8a, the low-viscosity liquid, the high-viscosity liquid 8b, and the solid 8c separated by the system of the present invention are contaminated with other materials (in amounts within a range in which the object of the preset invention can be achieved), the same expression (the melt 8a, the low-viscosity liquid, the high-viscosity liquid 8b, and the solid 8c) is used.
The crystal generator 2, the deliquoring device 3, the separator 6, the deliquoring separator, the crystal-filter layer melting device, and the device for separating the mixture after separation may be used in any one of the above-described combinations.
The combination may be used as pre-treatment means for the above-described various separation means such as the disk-type centrifugal separation method, the drum-type centrifugal separation method, the continuous decanter separation method, and a method and apparatus using a membrane, a filter, a coalescer, or the like. For example, the disk-type centrifugal separation method may be used for increasing the purity of a material separated from the mixture to be separated by the gravity settling separation method or the purity of the passing liquid passing through the crystal-filter layer supporting wall. Further, the separation means may be used for separating a mixture containing a mixture in the passing liquid tank and a capturing crystal-filter layer mixture after melting of the crystal-filter layer.
The disk-type centrifugal separation method includes applying (strong) centrifugal force, which is produced by a high-speed rotor (separation disk), to a mixture to be separated, thereby causing a difference in movement velocity between components in the mixture to be separated and separating the components. Therefore, the separating ability is proportional to a difference in specific gravity between a dispersion medium and an immiscible liquid in the dispersion medium and solid in the mixture to be separated, and is reversely proportional to the viscosity of the dispersion medium. This technique is well known as a separation technique for liquid-liquid (light liquid and heavy liquid) and solid-liquid (solid and liquid or solid, light liquid, and heavy liquid). The structure and principle of the technique of disk-type centrifugal separation method (Disk-centrifuge) are described in, for example, the Perry document, p. 19.89-103.
The system of the present invention may be a system for continuous treatment or batch treatment of the mixture 5a to be separated according to purposes of use. In addition, the system and the method may be various sizes according to purposes of use.
Preferred modes 1 and 2 of the system are described below.
Preferred mode 1 (
In addition, the mother liquid 1a is a NaCl solution (sterilized seawater), and the filter crystals are ice crystals. The mixture to be separated is a liquid-liquid mixture.
The mother liquid 1a is transferred from the mother liquid tank 1 to the in-liquid rotating drum-type crystal generator 21 (
In this mode, the rotating drum-type crystal generator 21 (
The mother liquid crystals 2a formed by the crystal generator 2 are transferred to the conveyor-type deliquoring device 31 (
In this mode, the conveyor-type deliquoring device 31 operates as described below. In this case, a basket 310 having holes is a vertical type with a conical shape widening upward.
(a) The mother liquid crystals 2a are introduced from the crystal generator 2 to the bottom of the rotating basket 310 having holes. The charged mother liquid crystals 2a receive centrifugal force of the rotating basket 310 having holes and diffuse on the inner wall of the basket 310. The diffused mother liquid crystals 2a are deliquored by rotation centrifugal force of the basket 310 while being moved upwardly on the inner wall of the rotating basket by a screw-shaped scraping blade 311 which rotates (at a differential rate from rotation of the basket) near the inner surface of the basket 310. The deliquored filter crystals 3a are discharged from an outlet in an upper portion of the basket. The discharged deliquored filter crystals 3a are placed in a deliquored filter crystal tank disposed below the deliquoring device 31. On the other hand, the deliquored liquid 4a is transferred to the deliquored liquid tank 4. The deliquored liquid 4a in the deliquored liquid tank 4 is transferred to the mother liquid tank 1 after adjustment of the concentration and is reused as the mother liquid 1a.
The deliquored filter crystals 3a in the deliquored filter crystal tank are transferred to the filter cloth inverting type separator 61 (
In this mode, the filter cloth inverting type separator operates as described below. The general characteristics of the filter cloth inverting type separator are described in U.S. Pat. No. 7,168,571 B2.
(a) The deliquored filter crystals 3a in the deliquored filter crystal tank are transferred to a filter cloth 612 (the filter cloth rotates together with a basket) attached to the inner side of a rotating basket (crystal-filter layer supporting wall having holes) 611 by a screw feeder 613. The transferred deliquored filter crystals 3a form the crystal-filter layer 6a on the filter cloth (
(b) The mixture 5a to be separates is sprayed on the surface of the formed rotating crystal-filter layer 6a through a supply pipe 614 for the mixture to be separated. The low-viscosity liquid in the sprayed mixture 5a to be separated passes through the crystal-filter layer and the crystal-filter layer supporting wall having holes, while the high-viscosity liquid 8b is captured in the crystal-filter layer (
(c) The supply of the mixture 5a to be separated is stopped. Then, the capturing crystal-filter layer 6b is separated from the filter cloth (due to centrifugal force) by inverting (turning inside out) the filter cloth 612 among the rotating basket 611 and the filter cloth 612. The separated capturing crystal-filter layer 6b is discharged from the bottom of the separator 61 (
After the above-described operations, the passing liquid 7a (low-viscosity liquid) passing through the crystal-filter layer and the crystal-filter layer supporting wall having holes is transferred to the passing liquid tank 7. The capturing crystal-filter layer 6b is transferred to the melting tank 8. The crystal-filter layer is melted by heating (heater) in the melting tank 8. The mixture heated in the melting tank 8 is separated into the high-viscosity liquid 8b and the melt 8a due to a difference in specific gravity (gravity settling separation).
Preferred mode 2 (
In addition, the mother liquid 1a is water, and the filter crystals are ice crystals. The mixture to be separated is a solid-liquid mixture.
In this mode, the low-temperature evaporation-type crystal generator 22 includes a humidifier 221, a rotary ventilation filter 222, a crystal scraping device 223, and a cooling chamber 224. The operations thereof are as follows.
A gas is cooled in the cooling chamber 224. The cooled gas is introduced into the humidifier 221 by a fan 226. The cooled gas introduced into the humidifier 221 is mixed with a mother liquid vapor (and/or fine droplets) evaporated from a mother liquid 1a at a temperature of 40° C. The cooled gas mixed with the mother liquid 1a is introduced into the rotary ventilation filter 222 on which crystals are produced to form filter crystals 100 (solidification of the mother liquid 1a). The crystals formed on the ventilation filter 222 are removed with the crystal scraping device 223. The cooled gas (which may contain an unsolidified mother liquid) passing through the ventilation filter 222 is returned to the cooling chamber 224. The cooled gas (and the unsolidified mother liquid) is circulated by the above-described step.
The rotary ventilation filter 222 is made of a gas-permeable material such as synthetic resin fibers. The cooling chamber 224 is provided with a cooler and also provided with the function to control the temperature of cold air to the ventilation filter 222. The mother liquid 1a in the humidifier 221 is supplied from a mother liquid tank 1, and the mother liquid is controlled to a necessary temperature by a heater. The crystal scraping device 223 is a scraper provided near the ventilation filter 222.
The filter crystals 100 formed in the crystal generator 22 are transferred to a crystal reservoir 623 of the drum filtration-type separator 62 (
In this mode, the drum filtration-type separator 62 (
The present invention is suitable for a case in which ice is used as filter crystals, and a natural product (mixture of an aqueous solution and oil or solid, or mixture of all of the above) is used as a mixture to be separated. Utilization of natural products is rapidly extending in the various fields such as energy, raw materials, medicines, and foods. However, relating techniques frequently have difficulty in separating natural products and face high cost and low quality of a product.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008-120011 | Apr 2008 | JP | national |
| 2009-041440 | Feb 2009 | JP | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2009/057042 | Mar 2009 | US |
| Child | 12896448 | US | |
| Parent | PCT/JP2009/067452 | Sep 2009 | US |
| Child | PCT/JP2009/057042 | US |
