JPH0246317Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field The invention relates to a vacuum belt dryer, and more specifically, it vacuum-dries raw materials prepared in liquid, slurry, or paste form, and converts them into granular dry products. This invention relates to a liquid supply device for a vacuum belt dryer for taking out liquid.

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 the field of processed foods, it is important to maintain the solubility and ready-to-eat 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 operations 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 the heating zone by the 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 strong evaporation phenomenon of the water contained inside, causing the food material to swell and form numerous ventilation holes inside. , and sent to the 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 while moving the raw material onto an endless conveyor belt. As the raw material is placed, a striated portion of the raw material is formed at the point where the direction of the oscillating motion changes, as shown in FIG. In this way, if the raw material placed on the endless conveyor belt while forming a thickened part that is thicker than other parts is subjected to drying treatment under the same heating conditions as other thinner parts, Due to the increase in thickness, the drying effect of the keratinized portion decreases, and problems such as deterioration due to insufficient drying occur. 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.

The main purpose 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 In view of this objective, the present invention provides a liquid supply device 5 disposed on the upper surface of the raw material introduction side of the endless conveyor belt 1 rotatably mounted in the vacuum container 18. In the
The liquid supply device 5 is attached to a drive shaft 2 that is swingably installed vertically.
A first swinging arm 5a is fixed to the lower end of the endless conveyor belt and extends along the moving direction of the endless conveyor belt, and a fixed support arm 5b is pivotally connected to a fixed support arm 5b hanging from the tip of the first swinging arm 5a. A second swing arm 5c swings along a plane V substantially orthogonal to the swing surface H of the first swing arm, and a second swing arm 5c is formed on an upper end surface of the second swing arm 5c near the drive shaft. Pressure receiving part 5d
, a fixed guide 5f that is disposed opposite to each other on both sides of the moving path of the endless conveyor belt 1, and has an inclined sliding surface 5e that gradually increases the amount of pushing down toward the outside with respect to the pressure receiving portion 5d, and the second rocker. The gist of the present invention is a liquid supply device for a vacuum belt dryer, which is constituted by a liquid supply nozzle 3 fixed to the tip of a movable arm 5c.

Function Raw materials for processed foods prepared in liquid, slurry, or paste form are transferred to the first swing arm 5.
A double oscillating motion formed by combining the horizontal oscillating motion of a and the vertical oscillating motion of the second swinging arm 5c forms a heavy folded portion with an increased placement thickness on the endless conveyor belt 1. It is supplied in the form of a thin film while drawing a meandering trace T, and is vacuum-dried in the drying/cooling device 8 by the constant speed movement of the endless conveyor belt 1. Thereafter, it is processed into granules by the pre-crusher 11 and the main crusher 15. crushed into
The product is taken out of the system in batches from a product take-out chamber 17 having a vacuum lock mechanism 16.

Embodiment FIG. 1 is a partially sectional front view illustrating the overall structure of the device of the present invention, and FIG. 2 is a perspective view of the liquid supply device. FIG. 3 is a plan view illustrating the meandering trace of the raw material fed onto the endless conveyor belt by the apparatus of the present invention.

In FIG. 1, the main body of the vacuum vessel 18 is equipped with a vacuum generator 2, which includes a known vacuum pump 19, a cold trap 20, and a chiller unit 21.
8 is disposed, and by operating the vacuum generator, a degree of vacuum of around 10 Torr can be maintained inside the vacuum container 18 during drying of raw materials.

On the other hand, inside the vacuum container 18, there is a first pipe which has a hot water flow path formed therein, extending along the movement path of the endless conveyor belt 1 from the raw material supply side to the product delivery side.
to third heating plates 6a, 6b, 6c, and a cooling plate 7 having a cooling water flow path formed therein;
are arranged in sequence, and correspondingly, in order to supply hot water and cooling water adjusted to a predetermined temperature to the vacuum drying device 8 constituted by the heating plate and the cooling plate, the vacuum container is Main body 18
includes a known tube or plate heat exchanger 22 which functions as a hot water circulation line heater;
A heating medium and cooling medium circulation device is connected, which includes an expansion tank 23 that promotes circulation of hot water by pressurizing air, and a circulation pump 24 connected to a temperature control circuit (not shown).

The endless conveyance device basically includes 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 of synthetic fiber threads, such as polyester fiber threads, and a drive system formed by winding the mesh belt around the drive roller 26 and driven roller 27. By doing,
A constant speed conveying device having a conveying speed of 0.05 to 0.5 m/min is formed. The mesh belt 1 is manufactured from a knitted fabric made of synthetic fiber yarn with excellent strength, coefficient of friction, heat resistance, and heat conductivity in consideration of the general characteristics required for an endless conveying device. In order to maintain the peelability of vacuum-dried intermediate products, the prevention of leakage of raw materials and intermediate products from the weave and stitches, and the washability at a specified level, an endless conveyor belt is made from a woven fabric of polyester multifilament yarn. is being produced. 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 5 is disposed on the upper surface of the raw material introduction side of the endless conveyor belt 1 at an appropriate distance from the raw material loading surface of the endless conveyor belt 1 . In the liquid supply device 5, the lower end of the swingable drive shaft 2 extending substantially vertically downward from the swing speed control device 4 includes:
A first belt extending along the moving direction of the endless conveyor belt 1
A swing arm 5a is fixedly attached to the swing arm 5a. A fixed support arm 5b is provided at the tip of the first swing arm 5a.
is fixed so as to be oriented substantially vertically, and a pivot shaft 5g is fixed to the upper part of the fixed support arm 5b so that its axial direction coincides with the width direction of the endless conveyor belt 1. The second swinging arm 5c is pivotally connected to the pivot shaft 5g via a bearing device (not shown), and has a vertical axis substantially perpendicular to the horizontal swinging surface H of the first swinging arm 5a. Its swinging posture is controlled so that it can swing along plane V. Further, a pressure-receiving portion 5d is formed on the upper end surface of the second swing arm 5c near the drive shaft 2, and correspondingly, on both sides of the movement path of the endless conveyor belt 1, an outer side, that is, a A fixed guide 5f having an inclined slide surface 5e whose inclination gradually increases toward the edge of the endless conveyor belt 1 is provided. When the first swing arm 5a swings, the fixed guide 5f is configured to swing the first swing whose amplitude is controlled by two sets of proximity switches 33 and 34 incorporated in the swing speed control device 4. The direction change point of the swinging motion of the movable arm 5a along the swinging surface H (reference mark P in FIG. 3)
), the second swing arm 5 engages with the pressure receiving portion 5d for a predetermined period of time, and
c, an additional swinging motion along a vertical plane V substantially perpendicular to the swinging plane H is generated. On the other hand, a liquid supply nozzle 3 is attached to the tip of the second swing arm 5c, and a liquid supply nozzle 3 is provided between the second swing arm 5c and the fixed support arm 5b, which is not engaged with the fixed guide 5f. As a posture control mechanism for the second swing arm 5c in the aligned state, a tension spring 5h and a pin 5i are used.
is installed.

In this way, the first swinging arm 5a, the second
The swinging arm 5c and the liquid supply nozzle 3 are swingably supported at a predetermined distance from the upper surface of the endless conveyor belt 1, and the raw material stored in the raw material tank 36 is transferred to the raw material tank 36. reaches the liquid supply nozzle 3 through the connected raw material supply valve 37,
The first swing arm 5a and the second swing arm 5
Due to the combined oscillation motion with c, the material is meanderingly placed on the endless conveyor belt 1 while maintaining a liquid, slurry, or paste state.

In the device of the present invention, it is possible to prevent the occurrence of duplicate supply of raw materials as shown in Fig. 4 at the turning point P of the meandering liquid supply trace, that is, a portion of increased thickness due to the placement of the serpentine. Therefore, under the amplitude control of the liquid supply nozzle 3 by the two sets of proximity switches 33 and 34, the first swinging arm 5a continues for a predetermined period of time before reaching the direction change point P of the swinging motion. The pressure-receiving portion 5d is engaged with the inclined sliding surface 5e of the fixed guide 5f, and the relative sliding motion between the two is used to cause the second swinging arm 5c to perform additional vertical swinging around the pivot shaft 5g. Generate movement. As a result, the liquid supply nozzle 3 has a horizontal swinging motion based on the swinging of the first swinging arm 5a around the drive shaft 2, and a second swinging arm 5c around the pivot shaft 5g. The liquid supply nozzle 3 moves in the direction of movement of the endless conveyor belt 1 (denoted by reference symbol F) near the edge of the endless conveyor belt 1. After moving laterally along the width direction of the endless conveyor belt 1 while forming a predetermined inclination angle with respect to and move in the opposite direction. In this way, the liquid supply trace T1 when the liquid supply nozzle 3 moves from the center in the width direction of the endless conveyor belt ₁ toward the edge, and the trace T1 when the liquid supply nozzle 3 moves from the center in the width direction of the endless conveyor belt 1 to the center in the width direction There is a pressure receiving part 5 between the liquid supply trace _T2 when the liquid supply nozzle 3 moves toward the
d and the inclined sliding surface 5e of the fixed guide 5f, the interval for preventing caries formation is maintained. Therefore, the raw material supplied from the liquid supply nozzle 3 acquires a meandering form that is spaced apart from each other, with almost no increase in thickness caused by the gravitational arrangement even in the vicinity of the direction change point P of the oscillating motion. be able to.

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 raw material introduced into the first heating zone constituted by the first heating plate 6a contains a large amount of moisture, the thermal energy transferred from the high temperature hot water flowing inside the heating plate 6a As the raw material is dried, water begins to evaporate on the surface and inside at the same time, so the raw material spread into a thin film is subjected to vacuum drying while expanding vigorously. Since this first heating zone is maintained in a constant dry state, the temperature of the raw material itself hardly rises, and the raw material is sent to the subsequent second heating zone in a state in which approximately half of its retained moisture has been evaporated.

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 raw materials are subjected to constant rate drying. Most of the retained moisture is evaporated. For this reason, the expanded thickness and surface shape of the raw material hardly change, the surface of the raw material slightly hardens, and the temperature of the raw material itself begins to rise. In this first heating zone, the thermal conductivity of the raw material 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 also set to a certain level. Adjust the drying conditions so that the size is reduced by 30 minutes. In this way, the raw material 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 raw material introduced into the third heating zone formed by the third heating plate 6c has a lower moisture content than the first heating zone and the third heating zone, and has a final moisture content without swelling phenomenon. It is vacuum dried slowly until the end. That is, in the first heating zone, the raw material is dried at a reduced rate, hardening the surface and raising its own temperature. In this first heating zone, the thermal conductivity of the raw material is significantly reduced, so the heating plate 6c is lower than that in the first heating zone and the third heating zone.
The temperature of the hot water introduced into the chamber is set even lower, and the raw material is subjected to vacuum drying under the influence of a small heat flux and sent to the subsequent cooling zone.

The raw material fed into the cooling zone is cooled by low-temperature water introduced into the cooling plate 7, lowering the temperature of the raw material itself and increasing its hardness, thereby improving the peelability of the intermediate product. as well as obtaining a final drying condition suitable for reducing hygroscopicity. 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 leaving 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
The mesh belt 1 protruding from the reversing part is first crushed by the vertical movement of the shearing blades 10 of the pre-crusher 11, and then crushed by the main crusher 5 consisting of a rotating blade and a mesh wire mesh (both not shown). Next, it is crushed. The granular product thus obtained is transferred to the vacuum lock mechanism 16.
falls into the product removal chamber 17 having a
It is taken out of the system in batches.

Effects of the invention As can be understood from the above explanation, by adopting the device of the invention, raw materials for processed foods prepared in liquid, slurry or paste form can be
At the direction change point of the oscillating motion of the liquid supply nozzle, the nozzle is arranged in a meandering manner at a predetermined interval between the forward path and the return path, without creating a heavy groove on the endless conveyor belt, and is spread over the entire surface of the endless conveyor belt. As a result, a substantially uniform spreading thickness can be maintained. 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.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional front view illustrating the overall structure of the device of the present invention, and FIG. 2 is a perspective view of the liquid supply device. Furthermore, FIGS. 3 and 4 are plan views illustrating the meandering trace form of the raw material fed onto the endless conveyor belt. 1... Endless conveyor belt, 2... Rotating arm, 3
... Raw material discharge nozzle, 4... Rocking speed control mechanism, 5... Liquid supply device, 18... Vacuum container.

Claims (1)

[Scope of utility model registration request] In a liquid supply device disposed on the upper surface of the raw material introduction side of an endless conveyor belt rotatably mounted in a vacuum container, the liquid supply device is connected to the lower end of a drive shaft vertically disposed in a swingable manner. a first swinging arm fixed to the section and extending along the moving direction of the endless conveyor belt; a second swinging arm that swings along a plane substantially orthogonal to the swinging surface of the arm; a pressure-receiving portion formed on the upper end surface of the second swinging arm near the drive shaft; and an endless conveyor belt. fixed guides that are arranged opposite to each other on both sides of the movement path and that form inclined sliding surfaces that push down gradually toward the outside with respect to the pressure-receiving region; and a liquid supply fixed to the tip of the second swinging arm. A liquid supply device for a vacuum belt dryer, comprising: a nozzle; and a nozzle.