JPH0620481B2 - Vacuum belt dryer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a vacuum belt dryer, and more specifically, a liquid, slurry or paste raw material is vacuum dried and taken out as a granular dry product. Vacuum belt dryer for.

2. Description of the Related Art In recent years, many kinds of processed food materials and instant foods have been marketed along with the diversification of eating habits. In such a food processing field, the consumer maintains the solubility and instantness when using the product as a cooking ingredient at a predetermined level, and the final product is not deteriorated in quality and the components are not deteriorated. Various atmospheric dryers and vacuum dryers are used for the purpose of imparting restoration properties. Focusing on the fact that it is relatively easy to maintain the solubility of a product as a cooking ingredient at a good level among such dryers, the fields of use of vacuum dryers are rapidly increasing. As a general-purpose vacuum dryer, a spray dryer and a freeze dryer are known, but the former has a low drying cost, but on the other hand, the solubility and quality retention performance of the product or the component change prevention performance is somewhat. Inferiorly, the latter is accompanied by problems of complicated structure and high drying cost due to the use of the freezing / sublimation process. Here, the development of a vacuum belt dryer has been demanded as a means for solving the practical problems recognized in the spray dryer and the freeze dryer. The vacuum belt dryer is provided with a heating zone and a belt transfer device in a vacuum container, supplies liquid, slurry, or paste food material in a peritoneal fashion onto the endless transfer belt, and rotates the endless transfer belt. Guide the food ingredients to the heating zone,
It is configured to perform vacuum drying under relatively low temperature drying conditions. At this time, the food material placed in a thin film on the belt undergoes a vigorous evaporation phenomenon of water contained therein, and the food material swells and forms a large number of vent holes inside. , Sent to the crusher as a porous intermediate product. In this way, the vacuum belt dryer is
Its usefulness is gradually being recognized as an alternative technical means to conventional spray dryers and freeze dryers.

Problems to be Solved by the Invention A vacuum belt dryer has a performance far exceeding that of a known spray dryer or freeze dryer in terms of quality retention performance, component change prevention performance, or drying cost reduction performance. However, in order to cope with the diversification of food materials to be dried, further improvement in structure and function is required in many cases.

First, as a first problem, in the case of supplying a raw material for a food prepared in the form of a slurry or a paste, in a conventional raw material supply device, the raw material discharge nozzle makes a swinging motion at a substantially constant rocking speed. On the other hand, since the raw material is placed on the endless conveyor belt, as shown in FIG. 8, an overlapping portion of the raw material is formed at the direction change point of the swing motion.
In this way, on the raw material placed on the endless conveyor belt while forming a superposed portion having a large thickness compared to other portions,
If the drying process is performed under the same heating condition as that of the other thin portion, the increase in the thickness reduces the drying effect of the superposed portion, which causes a problem such as deterioration due to poor drying. On the other hand, if the heating temperature is set to a high level so as to match the overlapping portion, other thin portions fall into an excessively dry state, which causes problems such as deterioration of quality and deterioration.

A second problem is that the endless conveying means consisting of the endless conveying belt and its driving roller moves at a constant speed from the raw material supply station toward the drying station to convert the thin film raw material supplied on the endless conveyor belt. Although it is configured to be able to transfer thermal energy for drying, as a practical matter, the endless conveyor belt is often placed in an unstable driving state with meandering and curling. Once such a phenomenon occurs, the conditions for supplying the raw materials onto the endless conveyor belt become extremely unstable, and the final product may suffer defects such as deterioration of quality and alteration of components due to fluctuations in drying conditions.

A third problem is that an end product of the endless conveying means is usually provided with a peeling and crushing device for intermediate products such as a rotary blade, but the existing device has a complicated structure but has a peeling and crushing ability. Insufficiently caused defects such as non-uniform particle size and reduced yield in the final product.

A main object of the present invention is to provide a vacuum belt dryer having a simple structure and stability of a drying function, which can solve the above-mentioned problems recognized in a conventional vacuum belt dryer. It is in.

Means for Solving the Problems In view of such an object, the present invention provides a vacuum belt dryer for vacuum-drying a mixed raw material in a liquid form, a slurry form, or a paste form, and taking it out as a granular dry product. Therefore, the rotary arm (2), the nozzle (3), and the shaking of the nozzle are provided in the moving path of the endless conveyor belt (1) made of the synthetic fiber yarn from the raw material supply side toward the product delivery side. Raw material supply device (5) consisting of dynamic speed control mechanism (4) and a plurality of heating plates (6a), (6b), (6)
c) and a vacuum drying / cooling device (8) formed by a single cooling plate (7) and a hydraulic cylinder mechanism (9)
And a pre-crusher (11) consisting of a shear blade (10) and a shearing blade (10) are sequentially arranged, and a meandering and warping prevention mechanism (12) is attached to the drive unit of the endless conveyor belt (1).
Further below the pre-crusher (11), the rotary blade (1
3) and a main crusher (15) consisting of a mesh wire net (14) arranged so as to surround the periphery of the product and a surrounding area of the product, and a product take-out chamber (17) having a vacuum lock mechanism (16). The main purpose is the vacuum belt dryer.

Action Raw materials for processed foods that have been prepared in liquid, slurry or paste form are supplied in a thin film with a meandering trace drawn without forming overlapping parts on the endless conveyor belt (1), suppressing meandering and warping. The endless conveyor belt (1) is vacuum-dried by the drying / cooling device (8) by moving the endless conveyor belt (1) at a constant speed, and then crushed into granules by the pre-crusher (11) and the main crusher (15), and the vacuum lock mechanism ( The product is taken out of the system by the batch method from the product taking-out chamber (17) having 16).

Example FIG. 1 is a front view with a part in section illustrating the overall structure of the device of the present invention. 2 to 6 are explanatory views of the detailed structure of the device of the present invention.

In FIG. 1, a vacuum generator (28) including a known vacuum pump (19), a cold trap (20), and a chiller unit (21) is provided in the main body (18) of the vacuum container. By operating the vacuum generator, the inside of the main body (18) of the vacuum container can maintain a vacuum degree of about 10 Torr when the raw material is dried.

On the other hand, inside the main body (18) of the vacuum container, first to first hot water flow paths are formed inside the endless conveyor belt (1) along the moving path from the raw material supply side to the product delivery side. 3 heating plates (6a), (6b), (6c) and a cooling plate (7) having a flow path for cooling water formed therein are sequentially arranged. Correspondingly, the heating plate In order to supply hot water and cooling water adjusted to a predetermined temperature to a vacuum drying device (8) constituted by a cooling plate and a cooling plate, the main body (18) of the vacuum container functions as a hot water circulation line heater. Heating consisting of a well-known tube or plate heat exchanger (22), an expansion tank (23) that promotes circulation of hot water by air pressurization, and a circulation pump (24) connected to a temperature control circuit (not shown) The circulation device for the medium and the cooling medium is connected It

As shown in FIG. 2, the endless conveying device basically comprises a motor (25), a drive roller (26), a driven roller (27), and a synthetic fiber yarn, for example, a polyester fiber yarn endless woven fabric. 0.05 to 0.5 m / m by comprising a mesh belt (1) that is connected in the shape of a circle and constructing a drive system that is formed by winding the mesh belt around the drive roller (26) and the driven roller (27). mi
forming a constant velocity transport device having a transport speed of n. The mesh belt (1) is manufactured from a knitted or woven fabric of synthetic fiber yarn having excellent strength, friction coefficient, heat resistance and heat transfer in consideration of general characteristics required for an endless conveying device. In order to maintain the peelability of vacuum-dried intermediate products, the leakage prevention of raw materials and intermediate products from weaves and stitches, and the washability to a prescribed level, weaving of polyester multifilament yarn We manufacture endless conveyor belts.

In view of the above-mentioned required characteristics, it is desirable that the mesh belt (1) be surface-treated with a resin such as silicon or polytetrafluoroethylene.

The drive roller (26) and driven roller (27)
It is necessary to be able to ensure a stable transporting posture in the main body (18) of the vacuum container without causing the mesh belt (1) to meander. For this reason, the drive roller (26) and the driven roller (27) have their surfaces crowned so that the diameter of the center part is slightly larger than the diameter of the end parts, and the pivot of the driven roller (27) is fluidized. Pressure cylinder mechanism (2
9), for example, it is connected to a belt tension unit having an air cylinder mechanism to form a tension adjusting mechanism for the mesh belt (1). Drive rollers (26)
And mesh belt (1) to driven roller (27)
On the retracting side of the mesh belt (4), when a meandering phenomenon occurs in the mesh belt (1), a 4 for transferring a pressing force for inward restoration to the edge portion of the mesh belt (1), so-called ear, is transmitted.
A set of two door rollers (30) are rotatably opposed to each other. These constituent members are assembled into an integral structure to form a meandering prevention mechanism (12) for an endless conveyor belt.

On the other hand, when the mesh belt (1) is warped due to uneven tension or thermal contraction, the heating plate (6a),
The spacing between (6b), (6c) and the cooling plate (7) and the mesh belt (1) fluctuates along the width direction of the mesh belt (1), causing deterioration in quality of the product due to uneven drying. To do. In order to avoid such obstacles, the heating plate (6) is moved along the moving direction of the mesh belt (1).
Between a), (6b), (6c) and the cooling plate (7),
A plurality of pressing rollers (31) for pressing the mesh belt (1) are provided at appropriate intervals with respect to the raw material mounting surface of the mesh belt (1), and the axial direction thereof is the drive roller (26) and driven roller (27). It is rotatably supported via a support bracket (not shown) in a state where it coincides with the axial direction of. The pressing roller (31) is provided with the meandering prevention mechanism (12).
Cooperates with the mesh belt (1) to function as a warp prevention member. The raw material supply device (5) is arranged on the most upstream side of the moving path of the endless conveyor belt (1), and serves as a swing speed control mechanism (4) of the nozzle (3) as a rotating shaft of a motor (32). As shown in FIG. 3, there are two sets of proximity switches (33), (34) for detecting the amplitude of the nozzle (3), and the proximity switches (33), (3).
A forward / reverse rotation speed reducer (35) for converting the direction of the swinging motion of the nozzle (3) by detecting the amplitude of 4) is connected in series. The rotating arm (2) and the nozzle (3) are swingably supported at a predetermined distance from the upper surface of the mesh belt (1) via the swing speed control mechanism (4) as described above. The raw material stored in the tank (36) reaches the nozzle (3) through the raw material supply valve (37) connected to the raw material tank, and is liquefied, slurry or paste by the swinging motion of the nozzle. It is placed in a meandering manner on the mesh belt (1) while maintaining its state.

In the device of the present invention, the two sets of proximity switches (33) are provided so that overlapping feed portions of the raw material, that is, portions where the thickness increases due to the overlapping arrangement do not occur at the folding points of the meandering feed traces. When the direction change point of the swinging stroke of the nozzle (3) is detected by (34), the forward / reverse rotation speed reducer (35) of the swing speed control mechanism (4) is temporarily stopped, and as shown in FIG. As shown in the figure, the raw material supplied to the edge portion of the mesh belt (1) has a composite supply trace formed by the combination of the rotation of the mesh belt (1) and the temporary stoppage of the nozzle (3), that is, The form of the meandering supply trace is controlled so that the raw material is provided with a supply trace oriented in the longitudinal direction of the mesh belt (1) near the edge of the mesh belt (1).

Further, in the feeding device of the present invention, the forward / reverse rotation speed reducer (3
By adjusting the reduction ratio of 5) with respect to the running speed of the mesh belt (1), even when the conventional feed trace shown in FIG. 8 is drawn, the raw material is superposed at the turning point of the meandering feed trace. It is possible to obtain a meandering form of the raw material in which a thickness-increased portion due to is hardly generated.

On the other hand, in the vacuum drying path formed by the endless conveyor belt (1), heating plates (6a), (6) having the hot water passages built in along the lower surface of the mesh belt (1),
A hot water circulation type vacuum drying / cooling device (8) consisting of b) and (6c) and a cooling plate (7) with a cooling water passage built-in.
Are arranged.

The thin-film raw material introduced into the I-th heating zone constituted by the first heating plate (6a) contains a large amount of water, but was transferred from the high-temperature hot water flowing in the heating plate (6a). Since the evaporation of water begins at the same time on the surface and inside of the raw material due to the thermal energy, the raw material spread in a thin film is subjected to vacuum drying while vigorously expanding. Since the No. I heating zone is kept in a constant rate dry state,
The temperature of the raw material itself hardly rises, and the raw material is sent to the succeeding No. II heating zone in a state where almost half of the water content is evaporated.

In the second heating plate (6b) forming the second heating zone, hot water having a temperature slightly lower than that of the hot water supplied into the first heating plate (6a) is introduced, and the raw material is Most of the retained water is evaporated by constant rate drying. Therefore, the expanded thickness and surface shape of the raw material hardly change, the surface of the raw material is slightly hardened, and the temperature of the raw material itself starts to rise. In this II heating zone, the thermal conductivity of the raw materials is somewhat reduced, so the temperature of the hot water introduced into the heating plate (6b) is set slightly lower than in the I heating zone, and The drying process conditions are adjusted so that the heat flux is also somewhat reduced. Thus, the raw material is allowed to evaporate approximately 90% of its water content from the second heating zone to the subsequent second.
III Delivered to heating zone.

The raw material introduced into the third heating zone formed by the third heating plate (6C) has a water content lower than those of the first heating zone and the second heating zone and is free from swelling phenomenon. It is gently vacuum dried to the final moisture content. That is, in the III heating zone, the raw material is dried at a reduced rate, which hardens the surface and raises the temperature of itself. In this III heating zone,
Since the thermal conductivity of the raw material is significantly reduced, the heating plate (6c) is more than the first heating zone and the second heating zone.
The temperature of the hot water to be introduced therein is set lower, vacuum drying is carried out under the action of a small heat flux, and it is sent to the subsequent cooling zone.

The raw material fed into the cooling zone is cooled by the low temperature water introduced into the cooling plate (7), which lowers the temperature of the raw material itself and increases its hardness,
As a result, the final dry state suitable for improving the peelability of the intermediate product and reducing the hygroscopicity is obtained. In this way, the intermediate product heated and cooled by the vacuum bristles, that is, the expanded product, becomes a porous cake, and arrives at the end of the endless conveyance path while leaving a trace corresponding to the liquid supply shape on the mesh belt (1). To do. Here, at the end of the endless transport path,
A fluid pressure cylinder mechanism (9) as seen in FIG.
A pre-crusher (11) including a shearing blade (10) fixed to the reciprocating piston (38) of the fluid pressure cylinder mechanism is provided. Therefore, the intermediate product that has reached the end of the endless conveyance path is primary crushed by the vertical movement of the shearing blade (10) while protruding from the reversing part of the mesh belt (1), and is then introduced into the lower body outlet duct (39). Fall as crushed pieces of porous cake. At the end of the endless conveyance path, the mesh belt (1) is turned upside down and turned over.
A scraper (40) is provided for peeling off the remaining cake adhering to the surface of the. As shown in FIG. 5, the scraper (40) is a main body (1
A shaft (42) rotatably supported on a support bracket (41) fixed to the bearing 8) via a louron bearing (49),
Fluororesin cake scraping blade (46) fixed to arms (43) and (44) extending from the shaft via a blade pressing plate (45), and the cake scraping blade (46)
Since the blade edge of the is elastically pressed against the mesh belt (1), the arm (43) and the support bracket (41)
It consists of a tensile spun ring (48) suspended between a base plate (47) supporting the base end of
The cake scraping blade (46) is pushed over the substantially whole width of the mesh belt under the bias of the tension spring (48) below the reversal part of the mesh belt (1) to remove the remaining cake from the mesh belt (1). Is peeled from the surface.

On the other hand, in the lower body outlet duct (39) located below the pre-crusher (11), as shown in FIG. 6, a support plate (on a shaft (51) rotatably driven by an external motor (50) is provided. 52) The plate-shaped rotary blade (13) made of fluororesin fixed via the blade and the blade edge of the rotary blade (13) is surrounded by a predetermined distance so as to surround the lower half of the rotation path of the rotary blade. A main crusher (15) composed of mesh wire nets (14) arranged in the above is provided. Intermediate product, which was primary crushed by pre-crusher (11)
That is, the crushed pieces of the porous cake are pressed into contact with the mesh wire net (14) having a predetermined mesh size by the rotation of the rotary blade (13), and the vacuum lock mechanism (16) as finely divided granules.
The product is dropped into the product take-out chamber (17) and stored under a vacuum. Placed here, the vacuum lock mechanism (16) includes a product take-out chamber (17), a first air lock valve (53) provided at the upper part thereof, and a first air lock valve (53) provided at the lower part of the product take-out chamber (17). It is composed of two air lock valves (54), and if necessary,
As a means for preventing moisture absorption or oxidation of the product, a supply valve for an inert gas such as nitrogen gas is attached to the product take-out chamber (17).

The product crushed into granules is the first airlock valve (53).
Open the product and close the second airlock valve (54) to keep the product in a vacuum (17)
It is stored inside, but the first airlock valve (53) is closed and the second airlock valve (54) is opened when the stored amount of the product reaches a predetermined level, and the product is taken out. The vacuum inside the chamber (17) is released, and the product take-out operation is started under atmospheric pressure. When the product take-out operation is completed, the main body (18) of the vacuum container is washed, and then the first air lock valve (53) and the second air lock valve (54) are operated to take out the product. The inside of the chamber (17) is restored to a vacuum state, and at the same time, the vacuum generator (28) including the vacuum pump (19), the cold trap (20), and the chiller unit (21) is activated to activate the main body ( Adjust the degree of vacuum in 18) to the predetermined level required for restarting the vacuum drying process. In this state, the drying conditions by the vacuum drying / cooling device (8) are adjusted according to the same operating range as described above, and the vacuum drying operation of the raw material is restarted.

The preferred embodiments of the present invention have been described above based on the examples of the drawings, but the gist of the present invention should not be construed as being limited by such exemplary explanations, but the basics specified in the claims. It can include various application examples based on the physical configuration requirements. For example, when the capacity of the product take-out chamber (17) is large, it is dedicated to the product take-out chamber (17) to prevent air from outside the system from flowing into the main body (18) of the vacuum container from the product take-out chamber. A second vacuum generator can be provided. Further, a steam heating sterilizer or a cleaning device for sterilizing or cleaning the inside of the main body (18) of the vacuum container when changing the in-process brand can be attached. In carrying out the present invention, the capacity of the vacuum pump (19, cold trap (20), chiller unit (21), vacuum drying / cooling device (8), etc. is not limited to not only the degree of vacuum and the retention of degree of dryness, It is desirable to determine it by also taking into consideration the dew condensation prevention function in the main body (18) of the vacuum container.

Further, as an application example of the present invention, a vacuum belt dryer can be constructed by mounting a plurality of stages of endless conveyor belts (1) inside a main body (18) of a vacuum container.

EFFECTS OF THE INVENTION As can be understood from the above description, by adopting the device of the present invention, the endless conveyor belt can maintain a stable raw material conveying posture without meandering or warping for a long period of time. In addition, the raw material discharge nozzle has an overlapping portion at the direction change point of the swinging movement of the discharge nozzle in the raw material supplied on the endless conveyor belt in the state of being mixed in liquid, slurry or paste form. A thin film-like mounting form is provided without maintaining the substantially uniform supply thickness over the entire surface of the endless conveyor belt. Therefore, according to the apparatus of the present invention, uniform heating / cooling conditions can be maintained over the entire vacuum drying section formed along the movement path of the endless conveyor belt. Further, in the device of the present invention, a multistage crushing device consisting of a pre-crusher and a main crusher is provided at the terminal end of the endless conveying means, and the particle size can be easily adjusted by cooperating with a vacuum drying / cooling device.
In addition, it constitutes a granulating device having a simple structure. Therefore, it is possible to manufacture a final product having a uniform particle size, for example, a granular processed food such as instant coffee, powder soup, and powdered miso according to stable operating conditions.

As is clear from the above description, the vacuum belt dryer according to the present invention is capable of completely eliminating various drawbacks recognized in the conventional apparatus, and is particularly noted for improving the quality of processed foods and reducing manufacturing costs. It can exert the desired effect.

[Brief description of drawings]

FIG. 1 is a front view with a part in section illustrating the overall structure of the device of the present invention. 2 to 6 are explanatory views of the detailed structure of the device of the present invention. Further, FIG. 7 illustrates the meandering supply state of the raw material by the device of the present invention, and FIG. 8 shows the meandering arrangement state of the raw material by the conventional device. (1) …… Endless conveyor belt, (2) …… Rotary arm,
(3) ... Nozzle, (4) ... Nozzle rocking speed control mechanism, (5) ... Raw material supply device, (6) ... Heating plate, (7) ... Cooling plate, (8) ... Vacuum drying / cooling device, (9) ...... Fluid pressure cylinder mechanism, (10) ...... Shearing blade, (11) ...... Pre-crusher, (12) …… Mechanism for preventing meandering and warping of endless conveyance means, ( 13)……
Rotating blade, (14) …… Mesh wire mesh, (15) …… Main crusher, (16) …… Vacuum lock mechanism, (17) …… Product ejection chamber.

Claims (1)

[Claims] 1. A vacuum belt dryer for vacuum-drying a mixed raw material in a liquid form, a slurry form, or a paste form, and taking it out as a dry product in a granular form, which is manufactured from a knitted fabric of synthetic fiber yarn. In the movement path of the endless conveyor belt, from the raw material supply side to the product delivery side, the rotating arm,
A raw material supply device including a nozzle and a swing speed control mechanism for the nozzle, a vacuum drying / cooling device formed by a plurality of heating plates and a single cooling plate, and a pre-crusher including a liquid pressure cylinder mechanism and a shearing blade. And a mechanism for preventing meandering and warping are attached to the drive device for the endless conveyor belt, and further arranged below the pre-crusher so as to surround the rotary blade and its periphery over approximately a half circumference. A vacuum belt dryer characterized in that a main crusher consisting of a mesh wire mesh and a product take-out chamber having a vacuum lock mechanism are sequentially arranged.