JPH09122401A - Drying and recovering method for solid content in liquid material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To recover the efficiently of a solid content in a liquid material by making the liquid material to be treated adhere to medium particle surfaces to dry the liquid material, peeling off the solid content of the liquid material remaining and adhering on the medium particle surfaces and recovering the same when a medium particle group is moved while being heated and agitated. SOLUTION: The temperature of a jacket 3 and a hollow rotating body 15 is set to be constant by feeding a heat exchange medium, and then a quantitative feed device 20 is actuated to feed medium particles into a casing 1, and the medium particles are heated up to the constant temperature, and when the height of a medium particle layer reaches up to the upper sections of a hollow rotating body 15 and the jacket 3, a liquid material in a raw material tank 22 is introduced. Then the liquid material adheres successively on the medium particle surfaces, and is heated and dried, and an adhered solid content is peeled off the medium particle surfaces by the peeling action generated by the collision, friction and the like with the surface of the hollow rotating body 15, discharged out of a discharge opening 24, and then separated into the solid content and the medium particles by a separator 25.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a liquid substance, which is used in various industrial fields, for continuously drying liquid or slurry substances, and continuously recovering solid components contained in these substances as powders. The present invention relates to a method for drying and recovering solid components therein.

[0002]

2. Description of the Related Art There are several methods for recovering solid components from the above substances. That is,
Using a spray drier (spray dryer), the solution and fine particle slurry are sprayed in hot air and dried to obtain a dried product all at once, and particles (granules) of 20 to 500 μm are obtained. In addition, a contact heating type cylindrical dryer (drum dryer) is used to heat the rotary drum with steam or other heat medium, and a liquid or mud-like substance is attached to the surface of the rotary drum in a thin film form. The product is obtained in the form of flakes, by drying in a spin and scraping it with a scraper. Further, a medium fluidized bed dryer (Japanese Patent Laid-Open No. 232801/1988, Japanese Utility Model Laid-Open No. 2-61401, etc.) is used.
When a liquid substance is supplied to the place where it is fluidized by hot air, the liquid substance adheres to the surface of each medium particle, and the dispersion medium or solvent is rapidly evaporated by the hot air,
The solid content remaining on the surface of the medium particles is separated from the surface of the medium particles by collision or friction between the medium particles and between the medium particles and the fluidized chamber inner wall, and is collected in the form of powder particles. Obtained as a powder (primary particles).

[0003]

In the method using the spray dryer, the heat transfer capacity coefficient is small, the apparatus becomes large, and
The initial cost and running cost are high, and in the case of a liquid substance having a high viscosity, there is a drawback that it cannot be sprayed and cannot be processed. Further, the method using the cylindrical dryer has high heat efficiency because it uses heat transfer heating. The muddy substance can be treated, but the product becomes flakes, so a separate crusher and crusher are required to convert it into powder. Furthermore, in the method using a medium fluidized bed dryer, the water content of the obtained product is difficult to control because it is determined by the water content at the time of peeling from the medium and the exhaust temperature, and a product with a particularly low water content is obtained. I can't. Therefore, another dryer is required for the post process. Further, in the case of a liquid substance having strong adhesion or a liquid substance having an extremely high viscosity, these substances serve as a binder, and it is difficult to form a stable and constant fluidized bed due to agglomeration or unity phenomenon of medium particles. is there. In addition, there is a problem that a liquid substance adheres and grows on the tip portion of the supply nozzle, is dried and becomes a large solid content, and is not discharged as a product. Further, in any of the drying methods, a long residence time cannot be taken, so that there is a big problem that it cannot be dried until the reduced rate drying period. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for drying and recovering a solid component in a liquid substance that solves the above problems.

[0004]

According to the present invention, in accordance with the above object, a medium particle group is sequentially moved in one direction while being heated and stirred, and a liquid substance to be treated is supplied to the medium particle group to form a surface of the medium particle. The above problem was solved by a method for drying and recovering the solid component in the liquid substance in which the solid substance of the liquid substance remaining and adhering to the surface of the medium particles is separated and collected while the liquid substance adhered to the medium is sequentially dried. The present invention also includes a hollow rotating shaft having a large number of hollow rotating bodies provided in the casing in the axial direction, and a stirring / drying device that supplies a heat medium to the hollow rotating shaft and the hollow rotating body. While supplying and moving the medium particle group and the liquid substance to be treated from one end to the other end, heating and stirring are applied to the medium particle group to which the liquid substance is adhered, and the liquid substance adhered to the surface of the medium particle is dried. The above problem is solved by a method for drying and recovering the solid component in the liquid substance by peeling and recovering the solid component in the liquid substance remaining and adhering to the surface of the medium particles. Further, the present invention controls the residence time of the solid component in the dryer by controlling the supply amount of the medium particles, the dry matter recovery method of the solid component in the liquid substance to adjust the water content of the solid component, the above problems. Resolved.

According to the present invention, the liquid substance adhered to the surface of the medium particles is continuously dried, and the solid component contained therein remains adhered to the surface of the medium particles and is peeled off by friction by stirring or the like. It is recovered together with the powder. Also, the water content of the recovered powder can be adjusted.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of an apparatus used for carrying out the method of the present invention. A conduction heat transfer type groove type stirring dryer with a jacket equipped with a stirring mechanism and a heating mechanism, and before and after the dryer. Shows the device. Reference numeral 1 denotes a casing composed of a container which is relatively long in the lateral direction. The casing 1 is supported by support bases 2 and 2 ', and a jacket 3 for heat exchange is provided on the bottom surface and the side surface of the casing 1 (Fig. 2). For the sake of convenience, the support base 2 side will be referred to as the front part of the device, and the support base 2'side will be referred to as the rear part of the device. Reference numeral 4 denotes a heat exchange medium supply pipe to the jacket 3, and 5 denotes a heat exchange medium discharge pipe. Two hollow shafts 6 penetrate in parallel inside the casing 1 and are rotatably supported by a bearing 7 provided at a front portion of the casing 1 and a bearing 8 at a rear portion of the casing 1. A gear 9 is provided at the front of each shaft so that they mesh with each other and rotate in opposite directions. A sprocket 10 is provided on one of the hollow shafts 6, and a chain (not shown) is provided on this sprocket 10. , And is connected to a separately provided motor. The tip of each shaft 6 has a rotary joint 11
Is connected to the heat exchange medium supply pipe 12 and the rear end is connected to the heat exchange medium discharge pipe 14 via a rotary joint 13. A large number of heat exchangers are arranged on each hollow shaft 6 at regular intervals. This heat exchanger comprises, for example, a hollow rotating body 15, which is formed in a wedge shape so that the rotation direction side becomes narrower toward the tip side, and a scraping plate 16 is provided at a wide rear end portion. The scooping plate 16 has a function of scooping up the medium particles described later in the rotation direction. The hollow shaft 6 is not limited to two, and may be, for example, a plurality of four or more or a single shaft.

Reference numeral 17 denotes a cover which closes and closes the upper part of the casing 1. A front end portion of the cover 17 has a medium particle supply port 1
8 is provided, and this supply port 18 is connected to a fixed amount supply device 20 of medium particles via a supply pipe 19. Reference numeral 21 is a supply port for a liquid, slurry, or mud substance to be treated (hereinafter, these are collectively referred to as a liquid substance), and a liquid substance stored in a raw material tank 22 is supplied by a constant supply pump 23. A fixed amount is supplied from the supply port 21 into the dryer. The supply port 21 is provided behind the supply port 18 so as to supply the liquid substance after the medium particles supplied from the supply port 18 are heated and heated. In addition, this supply port 18
May be provided on the rear side of the supply port 21 or at the same position. A weir plate (not shown) for retaining a certain amount of the processed material in the casing 1 at the rear end of the casing 1.
And a discharge port 24 for discharging solid particles (that is, a dried product) in the liquid particles from which the medium particles that have passed over the barrier plate and water and other dispersion mediums or solvents have been removed. There is. This outlet 24 has a separator 2
For example, a vibrating screen or the like is connected as 5, and the separator 25 is provided with a mesh 26 having an opening smaller than the minimum particle size of the medium particles. In the separator 25, 27 is a dry product discharge port, 28 is a medium particle discharge port, and 28 is a discharge port.
The medium particles discharged from are again supplied to the quantitative supply device 20 and reused. It is preferable that the separator 25 not only has a function of separating the medium particles and the dried product but also has a function of peeling off the solid content adhering and remaining on the surface of the medium particles. For example, in addition to the vibrating screen described above, a combination of a flow separator, various disintegrators and a (vibrating) screen, etc. can be considered. Reference numerals 29 and 30 denote gas inlets provided in the front and rear portions of the cover 17, and a carrier gas for delivering the dispersion medium or the solvent evaporated from the liquid substance in the casing 1 to the outside to the inlets 29 and 30. Is discharged and discharged from the discharge port 31. The exhaust port 31 is connected to an exhaust blower 34 via an exhaust pipe 32 and a powder separator 33 such as a cyclone.

Typical substances which can be dried by the method of the present invention include various foods such as starch, resins such as vinyl chloride, polyethylene and polypropylene, slurries or solutions of organic substances such as organic chemicals, titanium dioxide, lime, Calcium carbonate, slurry of inorganic substances such as inorganic chemicals, iron,
Slurries of metals such as lead and copper and oxides and hydroxides thereof, but not limited to the substances described here, can be applied to various organic, inorganic and metal liquid substances. . As the medium particles, physical properties of the liquid substance to be dried, operating temperature (heat resistance), wear resistance,
Also, the shape and the material are selected according to the density of the medium particles. As for the shape, usually, spherical particles having a diameter of about 0.5 to 10 mm, preferably 2 to 5 mm are most preferable, but various shapes having at least a curved surface such as an ellipsoid or a cylinder having a major axis in this range. It is preferably a particle. For example, the material size (3 x 4 mm) shown in Fig. 4
Oval columnar (strand cut-polyester) particles are preferred. Further, in the case of the medium particles composed of only a plane such as a cube or a rectangular parallelepiped, the treated material (liquid substance) may act as a binder to cause the mutual aggregation of the medium particles or the cohesion phenomenon. There is no problem because these phenomena are eliminated by the forced stirring action by. The medium particles may be a mixture of particles having various shapes as described above.

The material of the medium particles is an inorganic material containing various ceramics such as alumina and zirconia, stainless steel,
Metals such as carbon steel and alloy steel, and various plastics are used. It should be noted that various plastics belonging to the thermoplastic resin are preferable, but the medium particles and the medium particles and the hollow rotating body,
Any material that does not break due to collision or abrasion with the inner surface of the casing, that is, a material having sufficient impact strength can be used. Specific material names of the thermoplastic resin include polyethylene, polypropylene, poly-4-methylpentene-1, ionomer, polyvinyl chloride, ABS resin, polystyrene, AS which are general-purpose resins.
Resin, methacrylic resin, cellulosic plastic, etc.
Polyamide resins, polyacetals, polycarbonates, modified polyphenylene ethers, thermoplastic polyester resins, etc. classified as engineering plastics (above, general-purpose engineering plastics), and fluororesins such as polytetrafluoroethylene, polyphenylene sulfide, polysulfone, polyarylate,
Polyether imide, polyether sulfone, polyether (ether) ketone, liquid crystal polymer, polyamide imide, polyimide, polyamide bismaleimide, polybisamide triazole, etc. (special engineering plastics). In addition to the above various resins, a composite material (polymer alloy) in which two or more kinds of polymers are physically mixed, or a composite material (fiber in which the above various resins are mixed and reinforced by mixing glass fiber, carbon fiber, etc. Reinforced resin).

Next, a method of drying a liquid substance using this apparatus will be described. First, the two hollow shafts 6 are rotated at a constant rotation speed. Next, the jacket 3 and the hollow shaft 6 are supplied with heat exchange medium such as hot water heated to a predetermined temperature, steam, and heat transfer oil. When the heat exchange medium is steam, after heating the jacket 3, the steam becomes a condensate and is discharged from the discharge pipe 5. On the other hand, the steam supplied to the hollow shaft 6 heats the hollow shaft 6 and the hollow rotating body 15 and then becomes a condensate and is discharged through the discharge pipe 14. After the temperature of the jacket 3 and the hollow rotator 15 becomes constant, or at the same time as the supply of the heat exchange medium, the constant quantity supply device 20 of the medium particles is operated to continuously supply the medium particles into the casing 1. A large number of medium particles, that is, a group of medium particles, supplied to the casing 1 receives a thrust in a direction parallel to the casing 1 due to the rotation of the hollow rotating body 15 and maintains a certain degree of fullness, and from one end to the other end. The inside of the casing 1 is gradually moved to the discharge port 24 side. In this process, the medium particles are agitated as the hollow rotating body 15 rotates, so that the medium particles are uniformly heated to a constant temperature by conduction heat transfer from the hollow shaft 6, the hollow rotating body 15 and the jacket 3. To go. When the initially charged medium particles reach the terminal end of the casing 1, that is, the terminal end, they are blocked by the barrier plate, and the height of the medium particle layer gradually rises. However, when this height reaches the upper end of the weir plate (the retention amount becomes constant), the amount of the medium particles continuously supplied and the amount of the medium particles overflowed from the upper end of the weir plate and discharged. And the height of the medium particle layer cannot be increased any more. When the height of the medium particle layer reaches the upper end of the overflow dam plate and rises to almost the upper parts of the hollow rotor 15 and the jacket 3,
The liquid material to be dried in the raw material tank 22 is forcibly delivered at a constant rate by operating the constant amount supply pump 23. The liquid substance is extruded from the supply port 21 into the casing 1 and is sequentially adhered while being forcibly dispersed on each surface of the medium particles moving in the casing 1 with the rotation of the hollow rotor 15. The particles are continuously and almost uniformly distributed and dispersed on the surface of the medium particles. Since the medium particles are heated to a constant temperature, the solvent or dispersion medium forming the liquid substance and the solid substance (generally, a large amount of fine particles) are used for the conduction heat transfer from the medium particles, the hollow rotating body 15 (rotating shaft). 6) and the conduction heat transfer from the jacket 3 heats up quickly and efficiently and causes a drying action. As described above, the liquid substance supplied into the casing 1 is forcibly dispersed and adhered to the surface of the medium particles by the rotation of the hollow rotating body 15, so that it is not necessary to spray the liquid substance using a two-fluid spray nozzle, for example. Absent. The liquid substance may be supplied to the medium particle quantitative supply device 20, and the liquid substance may be previously distributed and dispersed on the surface of the medium particle in the device 20, and then the medium particle may be put into the dryer.

On the surface of the medium particles, water or other solvent or dispersion medium in the liquid substance evaporated by the drying action is
The carrier gas supplied from the supply ports 29 and 30 and passing through the upper layer of the medium particles in the casing 1 is accompanied, and the discharge port 31.
From the exhaust pipe 32, the powder separator 33, and the exhaust blower 34. As the carrier gas, for example, air or an inert gas is used. The fine solid substance discharged along with the carrier gas is separated from the carrier gas by the powder separator 33 and collected. When various organic solvents are used as the dispersion medium or solvent, the exhaust blower 34
A solvent recovery device (not shown) can be provided in the pipe at the outlet of the carrier gas to recover the solvent, and the carrier gas is again supplied from the supply port into the casing 1. On the other hand, the solid content that has been dried and adhered to the medium particles is subjected to a peeling action due to collision or friction between the medium particles and between the medium particles and the inner surface of the casing 1 or the surface of the hollow rotator 15 to remove the medium particles. By the time it is discharged from the outlet 24, it is almost separated from the surface of the medium particles.
The separated solid content is dried by the conduction heat transfer from the hollow rotor 15 and the jacket 3 while moving along with the medium particles toward the discharge port 24. Then, after being discharged from the discharge port 24, the separator 25 separates the solid content and the medium particles, and the solid content is recovered as a product. In addition,
The solid content which is not peeled from the surface of the medium particles in the casing 1 and is discharged while being attached to the surface is also peeled from the surface of the medium particles by the peeling and separating action of the separator 25.
It is recovered as a product together with the solid content that has already been peeled off. On the other hand, medium particles are
It can be returned to the constant quantity supply device 20 and reused. Here, the residence time of the solid component contained in the liquid substance in the casing 1 changes depending on the supply amount of the medium particles. That is, the solid content adheres to the surface of the medium particles and moves in the casing 1, and moves even after being separated along with the medium particles. Since the volume of the casing 1 is constant, the residence time becomes shorter when the supply amount of the medium particles is increased, and becomes longer when the supply amount is reduced. Therefore, treated products (solid content)
The water content of the product can be controlled by the residence time when the dispersion medium or the solvent is water, although it depends on the physical properties of the product. Further, the casing 1 and the hollow rotating body 1
Since the amount of heat carried into the heat exchange medium supplied to 5 determines the evaporation capacity of the dispersion medium or the solvent, the upper limit of the supply amount of the liquid substance that can be delivered into the casing 1 is naturally determined based on this. As described above, if the solid content can be separated from the medium particles by various methods, the product (solid content) having an arbitrary water content can be taken out by controlling the residence time. That is, it is possible to perform drying in a reduced rate drying period that requires a long residence time, which is impossible with the conventional method, and it is particularly effective as a method for drying a liquid substance to obtain a solid content having a low water content. Further, even when drying a highly viscous liquid substance, which has been considered extremely difficult in the past, the liquid substance (solid content) adhering to the surface of the medium substance is moved while moving the medium particles by a mechanical stirring action in the casing. Since it is dried, stable operation is possible easily. The apparatus used for carrying out the method of the present invention is not limited to the groove-type stirring / drying machine shown in the above-mentioned embodiment, and includes a mechanism for mechanically stirring the material (medium particles) and a heating mechanism. It is enough (generally called a material agitation dryer). That is, as the stirring mechanism, there are a type in which a shaft equipped with a stirring blade rotates and a type in which a cylindrical container rotates. As the stirring blade, there are a general paddle blade, various shapes (hollow) disk type, and the like. On the other hand, as a heating mechanism, a type that receives heat from a heating surface such as a jacket, a hollow rotating shaft, hollow discs of various shapes, and heating pipes concentrically attached in 1 to 3 rows over the entire length of a cylindrical container (conduction) Heat transfer type) and a type of receiving heat from hot air supplied from one side of the container and discharged from the other side (hot air receiving type).
As a device (general name) equipped with any of the above stirring mechanism and heating mechanism, there are a hot-air groove-type stirring dryer, a conduction-type groove stirring dryer, a conduction-type cylindrical stirring dryer, a disk dryer, Direct heating rotary dryers, indirect heating rotary dryers, rotary dryers with steam heating tubes, aeration rotary dryers, etc. ("Drying device manual" edited by Japan Powder Industry Association).

[0012]

EXAMPLES Next, specific examples in which various liquid substances are dried by the method of the present invention will be described. As a drying device, a groove type agitating dryer with an effective volume of 77 liters in the casing, an effective heat transfer area of the jacket 0.87 m ² , and an effective heat transfer area of the hollow rotor 1.83 m ² (total 2.7 m ² ) ((shares )
Made by Nara Machinery Co., Ltd., product name: Paddle Dryer), using media particles as major particles 3 mm, minor axis 2 mm, and length 4 m
A liquid substance (slurry) was dried under the conditions shown in Table 1 by using a crystallized polyester chip of a substantially elliptic cylinder (strand cut) of m. A circular vibrating screener (manufactured by Tokuju Seisakusho Co., Ltd., model: TM-40) was used as a separator for the medium particles and solids. As shown in FIG. 3, the drying device normally penetrates the jacket and the casing from the side and inserts a plurality of resistance temperature detectors (thermometers) into the device at the positions TR-1 to TR-5. The temperature of the processed material was measured. Table 2 shows the relationship between the discharge port and the insertion position of each resistance temperature detector, the distance from one end of the casing (medium particle supply port side), the cumulative heat transfer area, and its ratio to the total heat transfer area.

[0013]

[Table 1]

[0014]

[Table 2]

As described above, the liquid material supply port 21
Is provided closer to the discharge port 24 side than the medium particle supply port 18, and specifically, the position of TR-1 is such that the ratio of the heat transfer area from one end of the casing is about 10%. In the meantime, the medium particles are heated to a predetermined temperature. A sample of the dried product was sampled at the positions of TR-3 and the outlet, and the water content thereof was measured by an infrared moisture meter (manufactured by Kett Scientific Laboratory Co., Ltd.). The results are shown in Table 1. From the measurement results of the water content, it is considered that both treated products were subjected to constant rate drying in a relatively short time (until TR-3), and then to reduced rate drying until the discharge port. In any case, both treated products were sufficiently dried. Normally, when using a fluidized bed dryer, 0.1% W. B. It is discharged to the extent that constant drying is completed. FIG. 5 shows the relationship between each measurement position and the water content when the calcium carbonate slurry is treated.
Shown in Since the water content (reduction period) after TR-3 is so small that it is absorbed in the horizontal axis, a curve is displayed at an enlarged position for convenience. That is, in the moisture content shown in FIG. 5, the display of the moisture standard 69.5 (% WB) is according to the following formula.

[0016]

(Equation 1)

Therefore, 0.14 (% WB), 0.02 (%
W. B. ) Is also the same, and becomes a small value, and is effectively absorbed on the horizontal axis. As shown in the above examples, the water content can be controlled during the rate reduction period after the constant rate (constant rate) drying. In addition, the rotation axis of the processed material (liquid substance),
Adhesion to the hollow rotor and the inner wall of the casing, no adhesion or blockage phenomenon that hinders operation such as cohesion and cohesion of medium particles with the treated material as a binder, and stable operation over a long period of time did it.

[0018]

According to the method of drying and recovering the solid component in the liquid substance according to the present invention, the solid component in the liquid substance can be continuously dried and recovered as a powder in a relatively short time. Further, it becomes possible to control the water content in the powder, and the powder of any quality can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an apparatus used for carrying out a method of the present invention and processing apparatuses before and after the apparatus.

FIG. 2 is an explanatory sectional view taken along line AA of FIG. 1;

FIG. 3 is an explanatory diagram showing an insertion position of a resistance temperature detector in the device.

FIG. 4 is a perspective view showing one embodiment of medium particles used in the present invention.

FIG. 5 is a graph showing the relationship between water content and measurement position in Examples.

[Explanation of symbols]

 1 Casing 2, 2'Supporting stand 3 Jacket 4 Heat exchange medium supply pipe 5 Heat exchange medium discharge pipe 6 Hollow shaft 7, 8 Bearing 9 Gear 10 Sprockets 11, 13 Rotary joint 12 Heat exchange medium supply pipe 14 Heat exchange medium Discharge pipe 15 Hollow rotor 16 Scooping plate 17 Cover 18 Media particle supply port 19 Media particle supply pipe 20 Media particle quantitative supply device 21 Liquid substance supply port 22 Raw material tank 23 Constant supply pump 24 Discharge port 25 Separator 26 Net 27 Dry product outlet 28 Medium particle outlet 29, 30 Carrier gas inlet 31 Carrier gas outlet 32 Exhaust pipe 33 Powder separator 34 Exhaust blower

Claims (3)

[Claims] 1. A medium particle group is sequentially moved in one direction while being heated and stirred, and a liquid substance to be treated is supplied to the medium particle group to sequentially dry the liquid substance adhering to the surface of the medium particle. A method for drying and recovering a solid component in a liquid substance, characterized in that the solid component of the liquid substance remaining on the surface of the particles is separated and collected. 2. A casing is provided with a hollow rotary shaft in which a large number of hollow rotary bodies are provided in the axial direction, and a stirring / drying device in which a heating medium is supplied to the hollow rotary shaft and the hollow rotary body is used.
The medium particles and the liquid substance to be treated are supplied and moved from one end to the other end of the casing, the medium particles to which the liquid substance is attached are heated and stirred, and the liquid substance attached to the surface of the medium particle is dried. A method for drying and recovering a solid component in a liquid substance, characterized in that the solid component in the liquid substance that remains and adheres to the surfaces of the medium particles is peeled off and recovered. 3. The liquid according to claim 1, wherein the water content of the solid component is adjusted by controlling the residence time of the solid component by controlling the supply amount of the medium particles. A method for drying and recovering solid components in a substance.