JPH0234591B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a vacuum belt dryer, particularly a vacuum belt dryer for vacuum drying raw materials prepared in a liquid, slurry or paste form and taking out a dried product in the form of granules. This invention relates to a method and device for supplying liquid to a machine.

BACKGROUND ART In recent years, with the diversification of dietary habits, many types of processed food materials and instant foods have become commercially available. In this field of food processing, it is important to maintain the solubility and ready-to-ready properties at a specified level when consumers use the product as a cooking ingredient, and to ensure that the final product does not suffer from deterioration in quality or alteration of ingredients. Various normal pressure drying devices and vacuum drying devices are used for the purpose of imparting restorability. Among such drying devices, attention has been paid to the fact that it is relatively easy to maintain the solubility of products as cooking ingredients at a good level, and the field of use of vacuum drying devices is rapidly increasing.
Spray dryers and freeze dryers are known as general-purpose vacuum drying equipment, but while the former has low drying costs, it has somewhat poor performance in maintaining product solubility and quality or preventing changes in components. On the other hand, the latter method employs freezing and sublimation processes, resulting in problems such as a complicated structure and a rise in drying costs. At this time, there has been a demand for the development of a vacuum belt dryer as a means of solving the practical problems observed in the above-mentioned spray dryers and freeze dryers. A vacuum belt dryer is equipped with a heating zone and a belt conveying device in a vacuum container, and feeds food material in the form of a liquid, slurry, or paste onto an endless conveyor belt in the form of a thin film, and rotates the endless conveyor belt. The food material is introduced into a heating zone by means of a heating zone, and is vacuum-dried under drying conditions at a relatively low temperature. At this time, the food material placed in a thin film form on the belt undergoes a violent evaporation phenomenon of the water contained inside, causing the food material to swell and form numerous vent holes inside. Then, it is sent to a crusher as a porous intermediate product. Vacuum belt dryers are thus increasingly being recognized as an alternative technology to conventional spray dryers and freeze dryers.

Problems that the invention aims to solve Vacuum belt dryers have significantly superior performance to known spray dryers and freeze dryers in terms of quality retention, composition change prevention, and drying cost reduction. However, in order to respond to the diversification of food materials to be subjected to drying processing, there are many points that require further improvements in terms of structure and function.

For example, when feeding food raw materials prepared in the form of a slurry or paste, in a conventional raw material supply device, the raw material discharge nozzle swings at a substantially constant oscillating speed and moves at a constant speed. Raw materials are placed on the conveyor belt, so
As shown in FIG. 4, a striated portion of the raw material is formed at a point where the direction of the swing motion changes. In this way, the raw material placed on the endless conveyor belt while forming a thickened part that is thicker than other parts,
If the drying treatment is performed under the same heating conditions as other thinner parts, the increase in thickness will reduce the drying effect of the gristlelic part, leading to problems such as deterioration due to poor drying. On the other hand, if the heating temperature is set high to suit the above-mentioned keratinous portion, other thinner portions will become excessively dry, resulting in problems such as deterioration and deterioration of quality.

In addition, the drive timings of the endless conveyor belt and the raw material discharge nozzle are synchronized, and the endless conveyor belt is caused to perform a feeding motion at the point where the direction of the oscillating motion of the raw material discharge nozzle changes, thereby suppressing the occurrence of gravies in the raw material. A method has also been proposed, but implementing this method requires the use of a complicated tuning device, which imposes major restrictions on maintenance management and capital investment.

The main object of the present invention is to solve the above-mentioned problems found in conventional vacuum belt dryers.
An object of the present invention is to provide a vacuum belt dryer having a simple structure and a stable drying function.

Means for Solving the Problems As a means for solving the above-mentioned problems, the present invention provides an inner cylinder in which a linear liquid discharge groove is opened along the axial direction in the peripheral wall surface, and a spiral liquid discharge groove in the peripheral wall surface. A vacuum system that discharges raw materials onto an endless conveyor belt that moves at a constant speed from a liquid supply mechanism consisting of an outer cylinder with an open opening, and forms a liquid supply trace that forms a predetermined inclination angle with respect to the direction of movement of the endless conveyor belt. Liquid supply method in a belt dryer, a vacuum comprising an endless conveyor belt rotatably mounted in a vacuum container, and a liquid supply mechanism disposed on the upper surface of the raw material introduction side of the endless conveyor belt In a belt dryer, the liquid supply mechanism is composed of an inner cylinder and an outer cylinder that are relatively rotatable, the axis of which is substantially perpendicular to the moving direction of the endless conveyor belt, and the inner cylinder is supported in a stationary state. A linear first liquid discharge groove is opened in the peripheral wall surface along the axial direction in a state facing the endless conveyor belt, and the first liquid discharge groove is formed in the peripheral wall surface of the rotatably supported outer cylinder. The present invention provides a liquid supply device for a vacuum belt dryer in which a spiral second liquid discharge groove is opened for causing raw material discharged from the vacuum belt to flow down onto an endless conveyor belt.

Function During the liquid supply process to the endless conveyor belt that moves at a constant speed, the processed food raw material discharged from the first liquid discharge groove of the inner cylinder supported in a stationary state forms a coaxial shape with the inner cylinder. , and is supplied onto the endless conveyor belt through the second liquid discharge groove of the rotatably supported outer cylinder. Since the intersection point of the first liquid discharge groove and the second liquid discharge groove changes continuously along the axial direction of the liquid supply device as the outer cylinder rotates, the intersection point of the first liquid discharge groove and the second liquid discharge groove continuously changes along the axial direction of the liquid supply device, The raw material is uniformly fed while maintaining a predetermined inclination angle with respect to the material without forming a thickened portion.

Embodiment FIG. 1A is a schematic front view of the device of the present invention in an exploded state, and FIG. 1B is a schematic plan view of the device of the present invention in an assembled state. Further, FIG. 2 is a partially sectional front view of a vacuum belt dryer equipped with a liquid supply device according to the present invention. FIG. 3 is a plan view showing a liquid supply trace of the material to be dried, which is fed onto the endless conveyor belt by the apparatus of the present invention.

In FIG. 2, the main body 18 of the vacuum container is equipped with a vacuum generating device 2 consisting of a known vacuum pump 19, a cold trap 20, and a chiller unit 21.
8 is disposed, and by operating the vacuum generator, a vacuum level of approximately 10 Torr can be maintained inside the main body 18 of the vacuum container during drying of raw materials.

On the other hand, inside the main body 18 of the vacuum container, there are first to third heating channels formed inside of the body 18 of the vacuum container, with hot water flow paths formed inside the moving path of the endless conveyor belt 1 from the raw material supply side to the product delivery side. Plates 6a, 6b, 6c
A cooling plate 7 having a cooling water passage formed therein is sequentially arranged, and a vacuum drying device 8 constituted by the heating plate and the cooling plate 7 is heated to a predetermined temperature. In order to supply hot water and cooling water adjusted to A heating medium and cooling medium circulation device is connected thereto, including an expansion tank 23 that promotes circulation of the heating medium and a circulation pump 24 connected to a temperature control circuit (not shown).

The endless conveyance device 5 is composed of a motor (not shown), a drive roller 26, a driven roller 27, and a mesh belt 1 formed by endlessly connecting knitted or woven fabrics made of synthetic fiber threads, for example, polyester fiber threads. By configuring a drive system in which the mesh belt is wound around the drive roller 26 and driven roller 27,
It forms a constant speed moving type endless conveyance device with a conveyance speed of 0.5 m/min. mesh belt 1
is manufactured from a knitted fabric made of synthetic fiber yarn that has excellent strength, coefficient of friction, heat resistance, and heat conductivity, taking into consideration the general characteristics required for endless conveying equipment. Endless conveyor belts are manufactured from polyester multifilament yarn woven fabric in order to maintain the peelability of dried intermediate products, the prevention of leakage of raw materials and intermediate products from weaves and stitches, and the washability at a specified level. are doing. Note that, in view of the above-mentioned required characteristics, the mesh belt 1 is preferably surface-treated with a resin such as silicone or polytetrafluoroethylene.

The liquid supply device 2 is placed on the raw material introduction side of the endless conveyor belt 1 with an appropriate distance from the raw material loading surface of the endless conveyor belt 1, and its axial direction is substantially perpendicular to the moving direction of the endless conveyor belt 1. It is arranged in.
This liquid supply device 2 is composed of an inner cylinder 40 and an outer cylinder 41 that are coaxially fitted and supported and are relatively rotatable. A linear first liquid discharge groove 42 is formed facing the raw material mounting surface of the endless conveyor belt 1 along the axial direction. An inlet 43 is formed at one end of the inner cylinder 40 for introducing raw materials for processed foods sent from a liquid supply tank (not shown) provided outside the system. Corresponding to the first liquid discharge groove 42, the raw material discharged from the first liquid discharge groove 42 is placed on the peripheral wall surface of the rotatably supported outer cylinder 41 on the raw material placement surface of the endless conveyor belt 1. Two second liquid discharge grooves 44a and 44b for upwardly flowing liquid are formed while maintaining a spiral opening shape. still,
Reference number 45 in the figure is an O-ring for preventing liquid leakage disposed between the inner cylinder 40 and the outer cylinder 41, and 46
is a motor for rotating the outer cylinder 41.

Hereinafter, the operating procedure of the apparatus of the present invention will be explained based on FIG. The processed food raw material discharged from the linear liquid discharge groove 42 of the inner cylinder 40 supported in a stationary state is transferred to two spiral liquid discharges formed on the side wall surface of the rotatably supported outer cylinder 41. Grooves 44a, 44b
is fed onto the endless conveyor belt 1. During the liquid supply process onto the endless conveyor belt 1, the first linear liquid discharge groove 42 and the second spiral liquid discharge groove 4
4a and 44b changes continuously along the axial direction of the liquid supply device 2 as the outer cylinder 41 rotates. On the other hand, while forming a predetermined inclination angle θ, the raw material of the processed food to which the liquid is to be supplied flows down uniformly without forming a thickened portion. The inclination angle θ and the interval between the liquid supply traces T can be freely adjusted by adjusting the moving speed of the endless conveyor belt 1 and the rotational speed of the outer cylinder 41 according to the amount of raw material discharged per unit time. .

On the other hand, in the vacuum drying path formed by the endless conveyor belt, heating plates 6a, 6b, 6 with built-in hot water channels are installed along the lower surface of the mesh belt 1.
A hot water circulation type vacuum drying/cooling device 8 consisting of a cooling plate 7 having a built-in cooling water flow path is disposed.

Although the thin film material to be dried introduced into the first heating zone constituted by the first heating plate 6a contains a large amount of moisture, the heating plate 6a
It is dried by the thermal energy transmitted from the high-temperature hot water flowing inside, and the water starts to evaporate on the surface and inside at the same time, so the material to be dried, which is spread in a thin film, expands vigorously and undergoes vacuum drying. Ru.
Since this first heating zone is maintained at a constant drying rate, the temperature of the material to be dried hardly increases, and the material to be dried is sent to the subsequent second heating zone with approximately half of its moisture content evaporated. It will be done.

Hot water at a slightly lower temperature than the hot water supplied to the first heating plate 6a is introduced into the second heating plate 6b forming the second heating zone, and the material to be dried is constant-rate dried. evaporates most of the retained moisture. Therefore, the expanded thickness and surface shape of the material to be dried hardly change, and as the surface hardens to some extent, the temperature of the material to be dried itself begins to rise. In this first heating zone, the thermal conductivity of the material to be dried decreases to some extent, so the temperature of the hot water introduced into the heating plate 6b is set slightly lower than that in the first heating zone, and the heat flux is The drying conditions are adjusted so that the size of the particles becomes somewhat smaller. In this manner, the material to be dried is sent from the first heating zone to the subsequent second heating zone in a state in which approximately 90 percent of the moisture content has been evaporated.

The material to be dried introduced into the third heating zone formed by the third heating plate 6c has an even lower moisture content than the first heating zone and the second heating zone, and the material to be dried is dried without any swelling phenomenon. It is slowly vacuum dried until the moisture content is reduced. That is,
In the first heating zone, the material to be dried is dried at a reduced rate, hardening the surface and increasing its temperature. In this first heating zone, the thermal conductivity of the material to be dried is significantly reduced, so the temperature of the hot water to be introduced into the heating plate 6c is set lower than in the first and second heating zones. , the raw material is subjected to vacuum drying under the action of a small heat flux and sent to a subsequent cooling zone.

The material to be dried, fed into the cooling zone, is cooled by the low temperature water introduced into the cooling plate 7, reducing its own temperature and increasing its hardness, thereby reducing the peeling of the intermediate product. A final drying state suitable for improving properties and reducing hygroscopicity is obtained. The intermediate product, that is, the expanded product heated and cooled under vacuum in this manner becomes a porous cake and reaches the end of the endless conveyance path while forming a trace corresponding to the shape of the supplied liquid on the mesh belt 1. The intermediate product that has reached the end of the endless conveyance path is first crushed by the vertical movement of the shearing blade 10 of the pre-crusher 11 while protruding from the reversing part of the mesh belt 1, and is then crushed by the rotating blade and the mesh wire mesh (both not shown). The main crusher 15 is configured to perform secondary crushing.
The granular product thus obtained falls into a product removal chamber 17 having a vacuum lock mechanism 1 and is taken out of the system in batches.

Effects of the Invention As can be understood from the above explanation, by employing the apparatus of the present invention, raw materials for processed foods prepared in liquid, slurry, or paste form can be
It is fed onto an endless conveyor belt that moves at a constant speed while forming a constant inclination angle. By using the apparatus of the present invention, the raw material flows down as a thin film having a uniform liquid supply thickness over the entire discharge region without forming a heavy cast area where the thickness of the raw material is increased. Therefore, according to the device of the present invention, uniform heating and cooling conditions are maintained throughout the entire vacuum drying section, which significantly improves the quality of processed foods compared to when conventional vacuum drying devices are used. It is possible to achieve the desired effect.

Furthermore, since the device of the present invention has a simple structure consisting of an outer cylinder and an inner cylinder, it greatly exceeds the level of conventional devices in terms of operational stability and ease of maintenance. can do.

[Brief explanation of drawings]

FIG. 1A is a schematic front view of the device of the present invention in an exploded state, and FIG. 1B is a schematic plan view of the device of the present invention in an assembled state. Further, FIG. 2 is a partially sectional front view of a vacuum belt dryer equipped with a liquid supply device according to the present invention. FIG. 3 is a plan view showing a liquid supply trace of the material to be dried, which is fed onto the endless conveyor belt by the apparatus of the present invention. FIG. 4 is a plan view illustrating a serpentine trace of a material to be dried in a conventional apparatus. 1...Endless conveyor belt, 2...Liquid supply device, 40
...Inner cylinder, 42...Outer cylinder, 42...First liquid discharge groove, 44...Second liquid discharge groove.

Claims (1)

[Scope of Claims] 1. A liquid supply mechanism consisting of an inner cylinder having a linear liquid discharge groove opened along the axial direction on the peripheral wall surface, and an outer cylinder having a spiral liquid discharge groove opened on the peripheral wall surface. from,
1. A liquid supply method in a vacuum belt dryer, characterized in that raw material is discharged onto an endless conveyor belt that moves at a constant speed, and a liquid supply trace is formed at a predetermined angle of inclination with respect to the moving direction of the endless conveyor belt. 2. In a vacuum belt dryer equipped with an endless conveyor belt rotatably mounted in a vacuum container and a liquid supply mechanism disposed on the upper surface of the raw material introduction side of the endless conveyor belt, the liquid supply The mechanism is composed of an inner cylinder and an outer cylinder that are relatively rotatable with the axial direction substantially perpendicular to the moving direction of the endless conveyor belt, and a straight line is formed along the axial direction on the peripheral wall surface of the inner cylinder that is supported in a stationary state. The first liquid discharge groove is opened facing the endless conveyor belt, and the raw material discharged from the first liquid discharge groove is transferred onto the peripheral wall surface of the rotatably supported outer cylinder onto the endless conveyor belt. A liquid supply device for a vacuum belt dryer, characterized in that a spiral second liquid discharge groove is opened to allow the liquid to flow down.