JPH0141359B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a method and apparatus for drying fabrics by substantially cyclically feeding a drying medium into a drying box.

<Prior art> The conventional drying methods are the so-called open type, which draws in outside air and heats it, sends it as a drying medium into a rotary drying box, and exhausts the high temperature, high humidity hot air directly outside the machine, and the rotary drying method. There are two types of dehumidifiers, which use a heat exchanger to cool and dehumidify the humidified air that leaves the room, and then reheat it.

FIG. 1 schematically shows the structure of an open type. In this case, air taken in through an intake port 1 is heated to approximately 60° C. by a heater 2 and sent into a cylindrical rotary drying box 4 by an electric fan 3. This drying medium comes into contact with the moisture-containing fabric being stirred in the rotary drying box 4, and the humidified high-temperature, high-humidity air passes through a filter 5 and a circulation duct 6 and is exhausted to the outside of the machine from an exhaust port 7. Ru. In this way, the open type is not a circulation type, so
Exhausts high-temperature, high-humidity hot air outside the aircraft, worsening the environment outside the aircraft. Furthermore, the drying time is affected by the humidity outside the machine, and the drying time becomes longer when the humidity is high, such as during the rainy season.

Further, FIG. 2 schematically shows the structure of a dehumidifying type. In this case, air sucked in through an intake port 1 is heated to about 60°C by a heater 2 and sent as a drying medium into a rotary drying box 4 by an electric fan 3, and the air is humidified by contact with the fabric. The air passes through a filter 5 and a circulation duct 6, enters a heat exchanger 10, is cooled and dehumidified, and a portion of this air is circulated to the rotary drying box 4. That is, this dehumidification type has a heat exchanger 10 for dehumidification in addition to the open type.
Equivalent to the addition of This dehumidifying type does not worsen the environment outside the machine, but it is not a complete circulation type, only a portion of it is circulated, and like the open type, the drying time is affected by the humidity outside the machine. . Furthermore, an extra heat exchanger 10 for dehumidification is required, making the structure complicated.

As mentioned above, all the conventional drying methods have the above-mentioned drawbacks, and since heated air of 100° C. or less is used as the drying medium, the drying time is long, and the drying efficiency is only around 60%.

Furthermore, as a drying method using superheated steam, for example, the method disclosed in JP-A-51-62451 is known.
This is intended for clay, sludge, etc.
Its structure is such that first, steam from a high-pressure boiler is supplied to the drying chamber, then it is turned into superheated steam by a heater, and the steam pressure must also be adjusted.This uses superheated steam at a high temperature and pressure of over 200℃, Not suitable for drying fabrics after washing.

<Purpose> The present invention aims at reducing approximately 100
By drying the fabric by supplying highly humid air controlled to a predetermined temperature (varies depending on the quantity and quality of the fabric) to the fabric in a nearly cyclical manner over ℃, the process is faster than conventional drying using heated air below 100℃. , increase drying speed,
The purpose of the present invention is to provide a fabric drying method and device that achieves high efficiency and energy savings by shortening the drying time, and also allows the fabric after drying to have a finish with a softer texture than before.

<Structure> Generally, when drying fabrics after washing, convection heat transfer is the most widely used method of introducing heat, and heated air has been used as the medium for a long time. It is thus recognized as a matter of course that at temperatures below 100°C and without superheated steam, the drying rate decreases as the humidity of the air increases. However, there is a limit to this, 100
When the temperature exceeds a certain temperature above ℃, the proportion of superheated steam increases in the mixed gas of air and superheated steam (hereinafter referred to as highly humid air), and as it approaches the state of superheated steam of 100℃, the drying rate increases. It is confirmed that it will.

FIG. 3 shows the relationship between evaporation (drying) rate and temperature in air, superheated steam, and a gas mixture thereof (high temperature moist air). As shown in the figure, if the evaporation (drying) rate is plotted on the vertical axis and the temperature is plotted on the horizontal axis, the evaporation curves intersect at a point corresponding to a certain temperature point. These highly humid airs start from the dew point temperature. Superheated steam draws an evaporation curve that slopes upward to the right starting at 100°C. This point of intersection is named the reversal point temperature, and as it is generally accepted that on the low temperature side from this temperature point, as the amount of water vapor in the air increases, the rate of evaporation and drying of water in the air increases. At temperatures above the inversion point, as the proportion of superheated steam increases, the evaporation (drying) rate of water increases contrary to that of air. This reversal point temperature varies depending on the air volume, the structure of the drying device, the gas radiation of superheated steam, etc., but it has been confirmed by experiments and calculations to be around 100 to 170°C. Furthermore, unlike air, heat transfer by superheated steam includes gas radiation in addition to convection heat transfer, so it is possible to transfer more heat than by air alone.

Furthermore, in the process of evaporation of moisture from moisture-containing fabric, the fiber temperature is only the wet bulb temperature relative to the ambient temperature.
Even if the temperature is 100℃ or higher, it cannot exceed 50℃.

The present invention was made based on the above-mentioned technical idea, and consists of placing moist fabric inside a drying box,
Next, the air, which is the drying medium in the drying box, is circulated and the temperature is rapidly raised using a heater, thereby converting the steam evaporated from the fabric into superheated steam in a short period of time, raising the drying medium to approximately 100℃ or higher. Highly humid air (including a state extremely close to 100% superheated steam in the present invention) is supplied to the drying box almost cyclically, and the temperature of the highly humid air in the drying box is set to a set temperature. The present invention is characterized in that automatic fabric drying is stopped when the temperature rise rate reaches 0 or when the rate of temperature rise rapidly increases from approximately zero.

<Example> Hereinafter, an example of the present invention will be described based on the drawings. First, the structure of a nearly circulating type fabric drying device will be explained using the schematic diagram in Figure 4. a cylindrical drying box 4; a heater 2 for heating the drying medium;
An electric fan 3 for circulating the drying medium, an outlet 4a with a filter 5 of the drying box 4, and an annular inlet 4
A drying medium circulation circuit is constituted by the circulation duct 6 which connects b. 4c is the fabric input port of the drying box 4, 8 is the door, and 9 is the main case, which is connected to the drying box 4.
is supported around a horizontal axis and forms a water recovery chamber B between it and the drying box 4. The drying box 4, circulation duct 6, and door 8 are each covered with a heat insulating material 11. Further, the door 8 is attached to the main body case 9 so as to be able to be sealed and closed, and a constant pressure valve P made of a gasket is provided between the outer periphery of the inlet 4b of the drying box 4 and the main body case 9. When the drying medium in the drying box 4 reaches one atmosphere or more, enough drying medium to maintain the pressure at one atmosphere is led out from the drying box 4 to the water recovery chamber B through the constant pressure valve P. 1
2 is a guide for guiding the condensation of highly humid air, which is a drying medium, through the main body case 9 in the water recovery chamber B;
3 is a water storage tank provided at the bottom of the main body case, and 14 is its drain port, which communicates the water recovery chamber B with the atmosphere, and these parts and the water recovery chamber B constitute a water recovery device. .

C is a temperature sensor for detecting the automatic drying completion temperature at the inlet 4b, and a temperature control circuit including this sensor C is constructed as shown in FIG. In other words, when drying with highly humid air, the drying speed increases as the temperature approaches or exceeds the reversal point temperature, but if the temperature rises too high, there is a risk of damaging the fabric being dried, and there is little moisture content. At about 97% dry, the temperature shows a rapid temperature rise of about 5 to 15 degrees Celsius. Therefore, in the present invention, the temperature sensor C is used to constantly detect the temperature of the superheated steam, and the temperature can be determined by the quantity and quality of the fabric. Different automatic drying completion temperature settings, for example, when reaching 185~195℃, automatic drying is completed. Furthermore, since the resistance of the thermistor R1 constituting the sensor C decreases as the temperature rises, the variable resistor R2 can be set to be smaller than the resistance value of the thermistor R1 at, for example, 185°C. That is, until the set temperature is reached, the value of variable resistor R2 is smaller than the resistance value of thermistor R1, and comparator IC1 that performs voltage control
The output of transistor Tr2 is in the "H" state.
ON, and relay RY becomes ON. When the set temperature is reached, the resistance value of thermistor R1 changes to variable resistance R.
2, the output of comparator IC1 becomes "L", relay RY turns OFF, and heater 2 turns off. At this time, transistor Tr1
turns ON, comparator IC1 remains "L" regardless of the resistance value of thermistor R1, and relay RY becomes OFF. Also, at this time, the capacitor C1 is charged. When drying is completed and the power is turned off, the relay RY remains OFF, and when the power is turned on again, the capacitor C1 is discharged, the comparator IC1 becomes "H", and the relay RY is turned ON. state.

As shown in Figure 6, the temperature of the sensor part C during drying increases greatly at the beginning, and then remains almost constant, reaching a dry state with almost no moisture.
% shows a rapid temperature rise of about 5-15°C. The temperature that has risen at this point is the set temperature for automatic drying completion.

In this way, the temperature control circuit keeps the temperature of the superheated steam below the set temperature, so that the material to be dried is not damaged.
Moreover, drying is performed without reducing the drying speed.

Next, to explain the drying method using the above-mentioned drying device, a cloth containing moisture is put into the drying box 4,
Next, the drying box 4 is rotated to agitate the fabric. The air heated by heater 2 is then transferred to electric fan 3.
into the drying box 4. When this heated air comes into contact with the fabric being stirred in the drying box 4, it becomes air containing evaporated moisture from the fabric, which passes through the filter 5 and enters the circulation duct 6.
It is heated by the heater 2 and circulated into the drying box 4 again. The circulation duct 6, the drying box 4 and the door 8 are equipped with insulation material 1 to prevent heat radiation of the heated air.
1. Through this heating circulation process, as shown by K1 in Fig. 6, the air that initially filled the drying box 4 is replaced with steam that has evaporated from the fabric due to the rapid temperature rise, and the air containing a large amount of superheated steam is It becomes humid air. This highly humid air is heated to a temperature near or above the reversal point temperature to increase the drying rate, but this highly humid air is
As shown in the figure, while steam evaporates from the fabric at a constant rate, it automatically maintains a nearly constant temperature (temperature rise rate is almost zero). This temperature is detected by a temperature sensor C at the entrance of the drying box in order to avoid damaging the fabric to be dried.

Note that during drying, the pressure inside the drying box 4 becomes high by the amount of water that evaporates, but that amount passes through the constant pressure valve P and blows out into the water recovery chamber B, and the steam in the highly humid air in this chamber is cooled. Water drops form and adhere to the inside of the case 9, flow down the inside of the case 9, are stored in a water storage tank 13, and are drained from a drain port 14.

When the moisture in the fabric is almost gone and the dry state reaches approximately 97%, the rate of temperature rise of the highly humid air in the drying box 4 increases rapidly, as shown by K3 in Fig. 6, and the automatic drying completion temperature or Since the set temperature is reached, this is detected by temperature sensor C and relay RY is activated.
and turn off the power.

Next, when the door 8 is opened and the fabric is taken out into the atmosphere manually (or by an automatic removal device), the residual water vapor in the fibers evaporates into the air in 1 to 2 minutes, and drying is completely completed.

Note that, if the fabric is to be used immediately, it is better to take it out immediately after the automatic drying is completed, but if it is not necessary, it is not necessary to take it out immediately.

In the above drying process, highly humid air is heated to 100°C.
This is a high temperature, and unlike air, heat transfer by superheated steam adds gas radiant heat in addition to convection heat transfer, so it is possible to transfer more heat than by air alone. The water in the fibers evaporates rapidly, and as in the drying blanket of the present invention shown as S on the left side of the photograph in Figure 8, the ejection force during evaporation loosens not only the bristles but also the base fabric fibers. Even if it is a thick blanket, it will have a fluffy texture. In addition, what is shown by A on the right side of FIG. 8 is a drying blanket made by a conventional method.

In addition, in the process of evaporation of moisture from moisture-containing fabric, the fiber temperature is only the wet bulb temperature relative to the ambient temperature.
Even if the temperature is over 100℃, it will not exceed 50℃.

Next, a water recovery device according to another embodiment of the present invention will be explained with reference to FIG. The water recovery device is constructed by taking advantage of the fact that the pressure is slightly higher than one atmosphere, and leading out highly humid air into the water in the condensation container 16 through the discharge pipe 15. 17 is a float for keeping the outlet of the discharge pipe 15 above the water surface.

In this embodiment, the highly humid air whose pressure inside the drying box 4 exceeds one atmosphere during drying enters the water recovery chamber B, and then passes through the discharge pipe 15 into the condensation container 1.
6, where the vapor phase cools and becomes condensate,
The air phase is dispersed into the atmosphere. In this manner, in this embodiment, there is no heat exchange through the main body case 9, so the outer circumferential surface does not reach a high temperature.

In addition, in the present invention, since the highly humid air used as the drying medium is high temperature and efficient, it is not necessary to rotate the drying box, and static drying is also possible. If the capacity of the drying box is increased, drying is possible without necessarily leading out a portion of the highly humid air that is the drying medium in the drying box to the water recovery device.

Furthermore, in the present invention, the rate of temperature rise is constantly detected, not only when the temperature of the highly humid air in the drying box reaches the set temperature, so that the temperature rises rapidly from almost zero (K2 in Figure 6). Increase (K3 in Figure 6)
The automatic fabric drying may be stopped by determining that the automatic drying is completed when the automatic fabric drying is completed.

Next, a comparative experiment will be explained between the circulation type drying apparatus shown in FIG. 4 according to the method of the present invention, the conventional open type drying apparatus shown in FIG. 1, and the conventional dehumidification type drying apparatus shown in FIG.

[Drying efficiency experimental conditions] Fabric 2.5Kg, Water 2Kg Drying efficiency = Evaporation amount of water (Kg) x Latent heat of evaporation of water (K〓/Kg) / 860
(K〓/KWh) × Total power consumption (KWh) Latent heat of vaporization of water = 560Kcal/Kg Total power consumption: Total power consumption of electric motor, heater, and electric fan for rotary drying box [Experimental results] Fourth method using the method of the present invention The drying efficiency of the circulating dryer shown in the figure is 78 to 82% The drying efficiency of the conventional open type dryer shown in Fig. 1 is 62% The drying efficiency of the conventional dehumidifying type dryer shown in Fig. 2 is 56% [After drying] Experimental conditions for texture of fabric] Dry 30 sheets of toweling, stack the 30 sheets of dried toweling, and measure the height to compare the texture.

[Experimental Results] 120 mm when using the circulating dryer shown in Figure 4 according to the method of the present invention 105 mm when using the conventional dehumidifying type dryer shown in Figure 2 <Effects> As is clear from the above explanation, the present invention Moist fabric is placed inside the box, and then the air, which is the drying medium inside the drying box, is circulated and the temperature is rapidly raised using a heater, which quickly superheats the steam that evaporates from the fabric. As steam,
The drying medium is highly humid air at a temperature of approximately 100℃ or higher,
The highly humid air is supplied to the drying box almost cyclically, and when the temperature of the highly humid air in the drying box reaches a set temperature or when the rate of temperature increase rapidly increases from approximately zero, automatic fabric processing is performed. This is a fabric drying method characterized by stopping drying.

Therefore, according to the present invention, compared to the conventional drying method using air drying, since drying is performed using highly humid air that is mostly superheated steam, the influence of radiant heat of superheated steam is also added, increasing the drying speed and shortening the drying time. is shortened. Therefore, even thick materials such as blankets and denim can be dried uniformly, power consumption is reduced, and drying efficiency is improved by approximately 20 to 30% compared to conventional drying methods, making it possible to provide a highly efficient and energy-saving drying method. . Further, in the present invention, since the drying method is almost a circulation type, the drying time is not affected by the humidity outside the drying device. Furthermore, in the present invention, since the drying medium is high-temperature, almost superheated steam, the moisture in the fabric rapidly evaporates from the inside in a vapor state, leaving the fabric fluffy and nice to the touch after drying, and is not sterilized. A clean finish can be obtained.

Further, in the present invention, the fabric drying device includes a drying box having a fabric input port, a heater for heating the drying medium in the drying box, a fan for substantially circulating the drying medium, and the drying box. a water recovery device having a circulation duct connecting an outlet and an inlet of the drying box, and a water recovery chamber connected to a part of the drying box;
a constant pressure valve provided at these connections to lead out a portion of the drying medium in the drying box to the water recovery chamber; and a temperature sensor for detecting the temperature or temperature increase rate of the drying medium in the drying box. If you compose from
Due to the function of the water recovery device, the drying efficiency can be further improved and the drying box and the entire device can be downsized.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of a conventional open type drying device, FIG. 2 is a schematic sectional view of a conventional dehumidifying type drying device, and FIG. 3 is a diagram of the relationship between evaporation rate and drying medium temperature according to the method of the present invention. Fig. 4 is a schematic cross-sectional view of a fabric drying device in which the method of the present invention is carried out, Fig. 5 is a temperature control circuit diagram of the drying device of Fig. 4, and Fig. 6 is a diagram of the relationship between drying medium temperature and time according to the method of the present invention. , FIG. 7 is a schematic cross-sectional view of a second fabric drying apparatus in which the method of the present invention was carried out, and FIG. It is a photograph substituted for a drawing showing the fiber shape of A). B: water recovery chamber, C: temperature sensor, P: constant pressure valve, 2: heater, 3: electric fan, 4: drying box, 4a: its outlet, 4b: same outlet, 4c:
Similarly, fabric input port, 5: filter, 6: circulation duct, 8: door, 9: main body case, 9a, 11:
Heat insulating material, 16: condensation container, R1: thermistor,
R2: variable resistor, RY: relay, IC1: comparator, Tr1, Tr2: transistor.

Claims (1)

[Claims] 1. Putting a moist cloth into a drying box,
Next, the air, which is the drying medium in the drying box, is circulated and the temperature is rapidly raised using a heater, thereby converting the steam evaporated from the fabric into superheated steam in a short period of time, raising the drying medium to approximately 100℃ or higher. The highly humid air is supplied to the drying box almost cyclically, and when the temperature of the highly humid air in the drying box reaches the set temperature or the temperature increase rate rapidly increases from almost zero. A fabric drying method characterized in that automatic fabric drying is stopped when the fabric increases. 2. A drying box having a fabric input port, a heater for heating the drying medium in the drying box, a fan for substantially circulating the drying medium, and a circulation duct connecting the outlet and inlet of the drying box. , a water recovery device having a water recovery chamber connected to a part of the drying box, and a constant pressure valve provided at a connection thereof to lead out a part of the drying medium in the drying box to the water recovery chamber. and a temperature sensor for detecting the temperature or temperature increase rate of the drying medium in the drying box. 3. The fabric drying device according to claim 2, wherein the water recovery device comprises a water recovery chamber and a condensation container connected to the water recovery chamber.