JPS6158157B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention maintains the wet bulb temperature in the drying chamber at a substantially constant value throughout the entire drying process, and adjusts the drying temperature every time the amount of water removed from the leaf tobacco, that is, the amount of intake and exhaust in the drying chamber reaches an equilibrium state. The present invention relates to an automatic drying method for leaf tobacco that is raised in constant steps, and an apparatus therefor.

Unlike the drying of general agricultural products, leaf tobacco drying involves not only simple dehydration and drying, but also a curing process that promotes chemical changes in the tobacco content in order to bring out the distinctive color and aroma of leaf tobacco. It is also necessary to dehydrate and dry the back bone portion. Therefore, the drying process can be roughly divided into
Drying is progressed in three stages: the yellowing stage, which maintains the mesophyll temperature at an appropriate level, the color fixation stage, which mainly dehydrates the mesophyll, and the midbone drying stage, which dries the midbone.

By the way, as a drying control method to ensure that the drying process as described above runs well, the wet bulb temperature in the drying chamber is maintained at a constant value (for example, 38°C) throughout the entire drying process, and the dry bulb temperature is adjusted every time a certain drying time elapses. A drying method has been developed in which the temperature is gradually increased by a predetermined value.
However, in this method, the dry bulb temperature is increased at preset intervals, so no matter how carefully you set the time, the timing of the rise in the dry bulb temperature will depend on the progress of the drying of the leaf tobacco. In reality, this method is not necessarily suitable as an automatic control method for drying leaf tobacco. Furthermore, a thermistor temperature detection element is generally used as a detector to extract changes in the wet bulb temperature and dry bulb temperature in the drying chamber as an electrical signal. Since the response to temperature changes is slow, adjusting the intake/exhaust amount, etc. based on this response often leads to malfunctions or inappropriate control.

In view of the above, the present invention maintains the wet bulb temperature at a substantially constant value and maintains the intake and exhaust amount in the drying chamber at the value at that time during the progress of the drying process, at the start of drying, and after the dry bulb temperature rise time has elapsed. The drying process is continued in this state, and when the wet bulb temperature decreases by a certain value, the dry bulb temperature is increased by a predetermined value, until the amount of dehydration of the leaf tobacco, that is, the amount of intake and exhaust in the drying chamber is balanced. The amount of water removed from the leaf tobacco, that is, the amount of intake and exhaust air in the drying chamber, is at equilibrium due to the ability to accurately detect the drying state and raise the dry bulb temperature accurately by fully adapting to the drying progress state of the leaf tobacco during drying. When this condition approaches, the intake/exhaust volume is temporarily fixed, and the timing of temperature rise is detected by the drop in wet bulb temperature, thereby reliably preventing malfunctions in the temperature rise control of the dry bulb temperature. The purpose is to provide a method and device for automatically drying leaf tobacco that can perform drying satisfactorily under complete automation. A preferred embodiment will now be described.

In FIG. 1, 1 is a wet bulb temperature sensor, 2 is a dry bulb temperature sensor, and these wet bulb temperature sensors 1
The dry bulb temperature sensor 2 is composed of a thermistor temperature detection element and is disposed inside the drying chamber. Reference numeral 3 denotes a proportional control circuit, 4 a damper, and 5 a hot air generator. The damper 4 controls the opening and closing of the intake and exhaust ports of the drying chamber. The hot air generator 5 has a built-in burner as a heat source, and the It supplies hot air for drying to. The proportional control circuit 3 controls the opening degree of the damper 4 and the heat source of the hot air generator 5 to maintain the wet bulb temperature and dry bulb temperature in the drying chamber at set values. That is, the proportional control circuit 3 is equipped with a wet bulb temperature setter 3a and a dry bulb temperature setter 3b, and receives signals from the wet bulb temperature detector 1 and the dry bulb temperature detector 2 in the drying chamber. The opening degree of the damper 4 and the heat source of the hot air generator 5 are controlled so that the wet bulb temperature and dry bulb temperature in the drying chamber are maintained at the set values by comparing with the respective set values. Reference numeral 6 denotes a temperature increasing circuit, and this temperature increasing circuit 6 operates to automatically operate the dry bulb temperature setter 3b of the proportional control circuit 3 in the temperature increasing direction to increase the set value of the dry bulb temperature. The temperature increasing circuit 6 has a temperature of about 2°C from the start of drying to the yellowing period throughout the entire drying time.
A temperature increase control timer 6a is provided to raise the temperature by approximately 2° C. to 5° C. during the color gloss fixing period, and again to approximately 2° C. to 5° C. during the midbone fixing period. 7 is a damper fixing circuit; 8 is a timer for setting the time (for example, 3 hours) for fixing the damper 4; the timer 8 is equipped with a timer reset mechanism 8a, In response, timer 8 is reset. The damper fixing circuit 7 operates to fix the damper 4 in the same position until it receives a reset signal from the temperature increasing circuit 6 after the time set by the timer 8 from the start of drying and when the dry bulb temperature increases. It is. 9 is a temperature increase command circuit, and this temperature increase command circuit 9 is connected to the proportional control circuit 3.
receives a damper opening/closing control signal from the damper, and when it detects the temperature set in the built-in temperature setting device 9a (for example, approximately 36°C), it sends one temperature increase command signal to the temperature increase circuit 6. do. Note that the set temperature of the temperature setting device 9a is a value slightly lower (for example, approximately 36°C) than the wet bulb temperature (for example, 38°C).
℃).

Next, the operation of the present invention will be explained.

Now, when drying the leaf tobacco stored in the drying chamber, in the proportional control circuit 3, the wet bulb temperature setter 3a is set to a constant temperature (for example, 38°C), and the dry bulb temperature setter 3b is set to the initial temperature (for example, approximately 38°C). 40℃) and start drying. Changes in the wet bulb temperature and dry bulb temperature in the drying chamber are detected by the wet bulb temperature detector 1 and the dry bulb temperature detector 2, and the signals are sent to the proportional control circuit 3. The heat sources of the damper 4 and the hot air generator 5 are controlled so as to maintain the wet bulb temperature set by the wet bulb temperature setting device 3a and the dry bulb temperature set by the dry bulb temperature setting device 3b.

When the drying progresses in the above state and the time set by the timer 8 (for example, 3 hours) has elapsed, the damper fixing circuit 7 is activated and the damper 4 is fixed at the opening degree at that time. Then, when the wet bulb temperature in the drying chamber decreases by a certain value (for example, from approximately 38°C to 36°C), a signal is sent from the proportional control circuit 3 to the temperature increase command circuit 9, and a single temperature increase command is sent to the temperature increase circuit 6. When the signal is sent, the temperature increasing circuit 6 automatically operates to increase the set temperature of the dry bulb temperature setting device 3b in the proportional control circuit 3 by one step. Therefore, the dry bulb temperature in the drying chamber is increased by a certain value, and the dehydration rate of the leaf tobacco increases again, and drying progresses. At the same time, a reset signal is sent from the temperature increase circuit 6 to the reset mechanism 8a of the timer 8, so the damper fixing circuit 7 releases the fixation of the damper 4, and the damper 4 sets the wet bulb temperature in the drying chamber to the set value (for example, The opening degree of the intake and exhaust ports is automatically adjusted to maintain a constant temperature (38℃). When the set time of the timer 8 has elapsed since the above-mentioned increase in the dry bulb temperature, the damper 4 is fixed again, and the dry bulb temperature is increased by one step in the same manner as described above, and this is repeated until the end of drying (second figure).

Note that the temperature increase value for each stage is the temperature increase value of the temperature increase circuit 6.
It is predefined by the temperature increase control timer 6a.

As described above, according to the present invention, after a certain period of time has passed from the start of drying and the rise in dry bulb temperature, the intake and exhaust amount in the drying chamber is fixed at the value at that time, and the wet bulb temperature is kept at a constant value. Wet bulb temperature detector 1 increases the dry bulb temperature by a predetermined value when the temperature drops to
Even if the response speed of the drying chamber is slow, malfunctions caused by this can be eliminated, and the dry bulb temperature can be increased by accurately determining the point when the amount of water removed from the tobacco during drying, that is, the amount of intake and exhaust in the drying chamber, is balanced. By completely adapting the timing of raising the dry bulb temperature to the progress of drying of leaf tobacco, it is possible to properly dry leaf tobacco.

In short, the present invention maintains the wet bulb temperature in the drying chamber at a substantially constant value throughout the entire drying process by adjusting the amount of intake and exhaust, and gradually increases the dry bulb temperature in the drying chamber by controlling the drying heat source. In the method of drying leaf tobacco, after a certain period of time has elapsed from the start of drying and the rise in dry bulb temperature, the intake and exhaust volume in the drying chamber is fixed at the value at that time, and drying is continued in this state to increase the wet bulb temperature. Since the dry bulb temperature is increased by a predetermined value when the temperature decreases by a certain value, it is possible to accurately detect the state in which the amount of dehydration of the leaf tobacco, that is, the amount of intake and exhaust air in the drying chamber has reached equilibrium, and increase the temperature of the leaf tobacco during drying. The dry bulb temperature can be raised accurately by fully adapting to the drying progress of the leaf tobacco, but once the amount of water removed from the leaf tobacco, that is, the amount of intake and exhaust in the drying chamber approaches an equilibrium state, the amount of intake and exhaust is temporarily reduced. To securely prevent malfunctions in controlling the increase in dry bulb temperature by detecting an equilibrium state based on a decrease in wet bulb temperature after fixing the temperature, and to perform drying of leaf tobacco successfully under complete automation. It produces the effect that can be achieved.

[Brief explanation of the drawing]

The drawings show one embodiment of the invention,
FIG. 1 is a block diagram showing the configuration of the apparatus, and FIG. 2 is an operating characteristic diagram showing the relationship between drying time, dewatering amount (suction/exhaust amount), and wet/dry bulb temperature. 1... Wet bulb temperature detector, 2... Dry bulb temperature detector, 3... Proportional control circuit, 4... Damper, 5...
Hot air generator, 6... Temperature increasing circuit, 7... Damper fixing circuit, 8... Timer, 9... Temperature increasing command circuit.

Claims (1)

[Claims] 1. The wet bulb temperature in the drying chamber is maintained at a substantially constant value throughout the entire drying process by adjusting the amount of intake and exhaust, and the dry bulb temperature in the drying chamber is gradually increased by controlling the drying heat source. In the method of drying leaf tobacco while drying, the intake and exhaust volume in the drying chamber is fixed at the value at that time after a certain period of time has passed from the start of drying and the rise of the dry bulb temperature, and drying is continued in this state to increase the moisture content. An automatic leaf tobacco drying method characterized by increasing the dry bulb temperature by a predetermined value when the bulb temperature decreases by a predetermined value. 2. In a drying chamber equipped with a damper that adjusts the opening and closing of the intake and exhaust ports and a hot air generator that supplies hot air into the drying chamber, the wet bulb temperature inside the drying chamber can be controlled by adjusting the degree of opening of the damper during the entire drying process. and a proportional control circuit that maintains the dry bulb temperature at a set value by controlling the heat source of the hot air generator and increasing the dry bulb temperature set value of the proportional control circuit step by step by a predetermined value. In addition to providing a temperature increasing circuit, a timer and damper fixing circuit are also provided to fix the damper after a certain period of time has elapsed from the start of drying and when the dry bulb temperature has increased. An automatic leaf tobacco drying device characterized in that the temperature increasing circuit is provided with a temperature increasing command circuit that sends a temperature increasing command signal for each step.