JPH0269135A - Multistage band type dryer - Google Patents

Abstract

PURPOSE:To dry a material to be dried without deteriorating the whole material by subjecting the material to be dried to constant-rate drying and then falling-rate drying. CONSTITUTION:A material to be dried is cut with a slicer 10 and fed through a wire net conveyor 1 in the first stage in a constant-rate drying period part, delivered onto a wire net conveyor 2 in the second stage, conveyed and irradiated with far infrared ray from far infrared ray heaters (5a) and (5b) to directly dry the interior thereof. Outside air sucked from an air filter 7 into a blower 6 is heated with a heater 8 and the resultant hot air is then passed in a countercurrent flow relatively to the conveying direction of the conveyor 1 to heat the material to be dried at a temperature so as not to deteriorate the surface thereof. The hot air is subsequently discharged from a blower 9. The material to be dried is then delivered from the lower end on the downstream side of the conveying direction of the conveyor 2 onto wire net conveyors 3 and 4 in the third and fourth stages in a falling-rate drying period part. Outside air sucked from an air filter 12 to a blower 11 is fed to a heater 13 and the hot air is then made to flow in the direction perpendicular to the surfaces of the conveyors 3 and 4 and circulated to dry the material to be dried. The resultant air is subsequently discharged from the side ends on the downstream side in the conveying direction of the conveyor 4.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention is mainly used for drying materials to be dried, such as vegetables, konnyaku potatoes, seafood, etc., which have low heat resistance and require consideration of deterioration due to heating. This relates to a commonly used multi-stage band dryer.

(Prior Art) A conventional band type dryer dries the object to be dried while conveying the object by flowing hot air parallel to or perpendicular to the direction of conveyance of the object.

That is, the surface temperature of the object to be dried is raised by the convection and radiation of the hot air, and the thermal energy is transferred into the object to be dried by the thermal gradient, thereby drying the object while being transported.

(Problems to be Solved by the Invention) As described above, the conventional band type dryer raises the surface temperature of the dried material by convection and radiation of hot air.

Due to the thermal gradient, thermal energy is transferred to the inside of the object to be dried, and the object to be dried is dried while being transported. Drying efficiency is improved by increasing the transfer of thermal energy into the interior of the dried material, so there is no particular problem with drying materials that have high heat resistance and do not need to be concerned about deterioration due to heating. No, but i! It is unsuitable for drying objects to be dried 2, such as vegetables, konjac potatoes, seafood, etc., which have low thermal properties and require consideration of deterioration due to heating. In other words, vegetables such as carrots and seafood are required to have a finish close to their natural color tone, and when reconstituted with water,
Extremely high restoration value (9 when the natural state is 100)
A restoration value of 5 or higher) is required. Konnyaku potatoes are also crushed after drying.

After separation, the mannan substance is extracted, but when drying potatoes, it is required to prevent deterioration of the mannan substance as much as possible. However, conventional band dryers do not The heat resistance is low because drying efficiency is improved by allowing the surface temperature of the material to be dried to rise and increasing the transfer of thermal energy to the interior of the material.

There was a problem in that it was unsuitable for drying vegetables, konnyaku potatoes, seafood, etc., which need to be sensitive to deterioration due to heating.

The present invention has been proposed in view of the above-mentioned problems, and its object is to treat vegetables with low heat resistance.

The object of the present invention is to provide a multi-stage band dryer capable of heating and drying konnyaku potatoes, seafood, etc., from the inside to the surface, without deteriorating the entire structure from the inside to the surface.

(Means for Solving the Problems) In order to achieve the above object, two aspects of the present invention provide a multi-stage band drying system in which a material to be dried is dried while being continuously conveyed. It has a decreasing rate drying period and a constant rate drying depression in the previous stage.

A conveyor for the constant rate drying period, and a hot air supply means for heating the material to be dried from the surface by flowing hot air countercurrently to the conveying direction of the conveyor for the constant rate drying period.

A far-infrared heater is installed that directly heats the inside of the dried material while suppressing the surface temperature of the dried material by irradiating far-infrared rays onto the dried material to excite thermal movement in the dried material. During the drying period, a conveying conveyor for the decreasing rate drying period that increases the thickness of the material to be dried by lowering the conveying speed than the conveying speed of the conveyor for the constant rate drying period, and a conveyor for the decreasing rate drying period that increases the thickness of the material to be dried by lowering the conveying speed than the conveying speed of the conveyor for the constant rate drying period; Hot air supply means is provided for heating the material to be dried by flowing it perpendicularly to the conveyance direction of the conveyor for the drying period.

(Function) The band dryer of the present invention is constructed as described above, and first, the material to be dried is conveyed by the conveyor for the constant rate drying period provided in the constant rate drying recess in the previous stage. At this time, the hot air supply means causes the hot air to flow countercurrently to the conveyance direction of the conveyor for the constant rate drying period to heat the material to be dried, while the far-infrared heater irradiates the material to be dried with far-infrared rays, By exciting the thermal movement of the dried material, the interior of the dried material is directly heated while suppressing the surface temperature of the dried material.Then, the material is transferred to the subsequent stage of the dwindling rate drying stage, where it is transferred to the transport conveyor for the dwindling rate drying stage. Transport by. At this time, the conveyance speed of the conveyor for the constant rate drying period is slower than the conveyance speed of the conveyor for the constant rate drying period. becomes Pl. At this time, the hot air supply means causes hot air to flow perpendicularly to the conveyance direction of the conveyor for the waning rate drying period to heat the material to be dried.

(Example) Next, the multi-stage band dryer of the present invention will be explained with reference to an example shown in Fig. 1.2. First, the three drying periods will be explained. When drying a sufficiently moist material to be dried, (■) preheating period (preparation drying period), (II) constant rate drying period, (1
) M is distinguished into dry periods.

When a sufficiently moist material to be dried is placed under certain drying conditions.

The temperature reaches a point where it is in dynamic equilibrium with the drying conditions, but
The period up to that point is the preheating period (I). Next, all of the incoming heat is used for one shot of water, and the water evaporation rate (drying rate)
There continues to be a period when
This is the constant rate drying period. Next, no moisture exists on the surface of the material to be dried, the temperature of the material to be dried increases, the amount of heat flowing in also decreases, the drying rate gradually decreases, and finally the moisture content and temperature of the material to be dried reach equilibrium with the drying conditions. drying is complete. The period up to that point is the waning rate drying period of (I[[).

The multi-stage band dryer of the present invention has a constant rate drying period section at the front stage and a decreasing rate drying period section at the rear stage. That is, (1) is the first stage wire mesh conveyor, (2) is the second stage wire mesh conveyor, (
3) is the third stage wire mesh conveyor, and (4) is the fourth stage wire mesh conveyor. 2nd stage wire mesh conveyor (1)
(2) is provided in the constant rate drying recess in the first stage, and the third. Fourth
Staged wire mesh conveyors (3) and (4) are provided in the latter stage of the drying period. In addition, these first stage wire mesh conveyors (1)
-The fourth stage wire mesh conveyor (4) is driven by independent variable speed motors (not shown), and the time period during which the dried material remains in the dryer is:

Approximately 20 to 30 minutes in the constant rate drying recess (part of the first stage wire mesh conveyor (1) to the second stage wire mesh conveyor (2)).

It takes about 60 to 120 minutes in the drying period (third-stage wire mesh conveyor (3) to fourth-stage wire mesh conveyor (4)).

Further, (5a) is a far infrared heater arranged along the first stage wire mesh conveyor (1), and (5b) is a far infrared heater arranged along the second stage wire mesh conveyor (2). The heat source of the infrared heaters (5a) (5b) is electricity, steam, heating oil, etc.
) is maintained at a set temperature of 100 to 350° set on a temperature controller (not shown).

The far-infrared heaters (5a) and (5b) have a mechanism (not shown) that can arbitrarily change the irradiation distance to the object to be dried.
It is equipped with The far infrared heaters (5a) (5b) are the first. It may be provided only in the upper part of the second wire mesh conveyor (1) (2), or only in the lower part, or it may be provided in each of the upper and lower parts.

In addition, (6) is a constant rate drying recess (1st and 2nd stage wire mesh conveyor)
1) Air blower for (2)), (7) is the air filter for the carefully dry period, (8) is the air heater for the carefully dry period, (9)
is the carefully dry period exhaust fan, which sucks outside air from the carefully dry period air filter (7) to the constant rate dry period blower (6) and sends it to the carefully dry period air heater (8). Here, it is heated to 70 to 80°C, and the second stage wire mesh conveyor (2) → the first stage wire mesh conveyor (1) → υ for constant rate drying recesses.
It is designed to be released into the atmosphere through a wind blower (9). In addition, (10) is a raw material slicer (cutting machine), and the raw material slicer (10) is equipped with multiple types of replacement blades for cutting the material to be dried into arbitrary shapes. , thickness 2-3 cap width 5-10 m11.
Cut into thin strips of length 50-60 Ll111.

In addition, (11) is a circulation blower for the lapse rate drying period (3rd and 4th stage wire mesh conveyor (3), (4)), and (12) is an air filter for the lapse rate drying period (13) is for the lapse rate drying period. The air heater (14) is a variable damper for adjusting the displacement, and the outside air is sucked from the air filter (12) for the lapse rate dry period to the circulation fan (technique 1) for the lapse rate dry period. It is sent to the period air heater (13), where it is heated to a predetermined temperature, and then transferred from the third stage wire mesh conveyor (3) to the fourth stage wire mesh conveyor (
4)→Return to the circulation blower for dry period (11),
It's supposed to circulate. Also, in this circulatory system, the third
In order to discharge water vapor that evaporates from the conveyed objects on the stage wire mesh conveyor (3) and the fourth stage wire mesh conveyor (4), the opening degree of the variable displacement damper (14) is adjusted, and some Circulated air is vented to the atmosphere.

Next, the operation of the multi-stage band type drying stage shown in FIG. 1.2 will be explained in detail. ■1st stage wire mesh compare (1) to 4th stage
The wire mesh conveyor (4) is driven by a variable motor, and the outside air sucked from the air filter (7) for the careful drying period to the blower (6) for the constant rate drying period is transferred to the air heater (8) for the careful drying period. ), where it is heated to 70 to 80°C and transported from the second stage wire mesh conveyor (2) to the first stage wire mesh conveyor (1) →
The outside air is carefully discharged to the atmosphere through the dry season exhaust fan (9), and is sucked from the lapse rate dry season air filter (12) to the lapse rate dry season circulating fan (11). It is sent to the section air heater (13), where it is heated to a predetermined temperature and transferred from the third stage wire mesh conveyor (3) to the fourth stage wire mesh conveyor (4).
) → Remaining rate Return to the circulation fan (11) for the dry period and circulate.

■When the surface temperature of the far infrared heater (5a) (5b) is maintained at the set temperature of 100 to 350° set on the temperature controller? 11 Put the dried product (raw material) into a raw material sliner (
If the material to be dried is, for example, konjac potatoes, the thickness is 2 to 3 m (width 5 to 10 + all, length 50 to 6 m).
After cutting into thin strips of about 0III, the strips are arranged in a single sheet from the outlet of the raw material slicer (11) onto the first stage wire mesh conveyor (1) in the constant rate drying period. The material is dropped, sent out, and conveyed by the same first stage wire mesh conveyor (1). At this time, far-infrared rays are irradiated from the far-infrared heater (5a) to the material to be dried on the first stage wire mesh conveyor (1), exciting the thermal movement of the material to be dried, and suppressing the surface temperature of the material to be dried. The inside of the material to be dried is directly heated, and the surface of the material to be dried is heated to a temperature that does not alter its quality by means of countercurrent hot air directed toward the carefully drying ventilator (9).

Further, the logs fall from the downstream end of the first stage wire mesh conveyor (1) onto the second stage wire mesh conveyor (2), are sent out, and are transported by the second stage wire mesh 4 conveyor (2).

At this time, far-infrared rays are irradiated from the far-infrared heater (5b) to the material to be dried on the second stage wire mesh conveyor (2), exciting the thermal movement of the material to be dried, and suppressing the surface temperature of the material to be dried. The inside of the object to be dried is directly heated, and the surface of the object to be dried is also heated by hot air flowing countercurrently toward the first stage wire mesh conveyor (1). Then, it enters the lapse rate drying period. That is, the second wire mesh conveyor (2) is dropped from the downstream end in the conveyance direction onto the third stage wire mesh conveyor (3) which performs lapse rate drying in a stacked state and sent out. Conveyor (3
). At this time, the third stage wire mesh conveyor (3
) and the fourth stage metal surface conveyor (4), the surface of the material to be dried is heated by hot air which is passed perpendicularly to the conveyor surface of the fourth stage metal surface conveyor (4). It also fell from the downstream end 031 in the transport direction of the third stage wire mesh conveyor (3) onto the fourth stage wire mesh conveyor (4).

It is sent out and conveyed by the fourth stage wire mesh conveyor (4). At this time, the surface of the material to be dried is heated by the hot air directed toward the circulation blower (11) for the lower wire mesh conveyor. At this stage, the drying of the material to be dried has been completed, and the material is discharged from the downstream end of the fourth wire mesh conveyor (4) in the delivery direction to the outside of the dryer.

(Effects of the Invention) As described above, in the zero-sending band type dryer, the material to be dried is first conveyed by the conveyor for the constant rate drying period provided in the careful drying period in the previous stage. At this time, the hot air supply means causes the hot air to flow countercurrently to the conveyance direction of the conveyor for the constant rate drying period to heat the material to be dried, while irradiating the material to be dried with far infrared rays from two far-infrared heaters, The inside of the material to be dried is directly heated while suppressing the surface temperature of the material to be dried by exciting the thermal movement of the material to be dried.Then, it enters the subsequent stage of the lapse rate drying stage, and is transported by a transport conveyor for the lapse rate drying stage. transport.

At this time, since the conveyance speed of the conveyor for the drying period is slower than that of the conveyor for the careful drying period, the thickness of the material to be dried is It gets thicker. In addition, at this time, the hot air is flowed by the hot air supply means at right angles to the conveyance direction of the conveyor for the waning rate drying period to heat the items to be dried, so vegetables with low heat resistance,
It has the effect of heating and drying konnyaku potatoes, seafood, etc. without altering the entire structure from the inside to the surface.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional side view showing an embodiment of a band type dryer according to the present invention, and FIG. 2 is a longitudinal sectional front view thereof. (1) (2)...Careful drying@conveyor for seasonal use,
(3) (4)...transport conveyor for the decreasing rate drying period,
(5a) (5b) Far infrared heater, (6)...
Air blower for careful drying period, (7) Air filter for careful drying period (8) Air heater for constant rate drying pan section,
(9)... constant rate drying concave air blower, (10) ・
・・Raw material slicer, (11) ・・Circulating blower for the lapse rate drying period, (12) ・・Air filter for the lapse rate drying period, (13) ・・・・Air heater for the lapse rate drying period , (14) ...Variable damper for adjusting displacement

Claims (1)

[Claims] A multi-stage band dryer that dries the material to be dried while continuously conveying it, has a constant rate drying period in the first stage and a decreasing rate drying period in the second stage. A conveyor for the constant rate drying period, a hot air supply means that heats the material to be dried from the surface by flowing hot air countercurrently to the conveyance direction of the conveyor for the constant rate drying period, and far infrared rays to the material to be dried. A far-infrared heater is installed that directly heats the inside of the dried material while suppressing the surface temperature of the dried material by irradiating the material to excite thermal movement in the dried material. A conveyor for the decreasing rate drying period which increases the thickness of the material to be dried by lowering the conveyance speed of the conveyor for the constant rate drying phase, and a conveyor for the decreasing rate drying phase which transfers the hot air at the same rate. A multi-stage band dryer characterized by being provided with hot air supply means that heats the material to be dried by flowing it perpendicularly to the conveying direction.