JPH0257916B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for drying leaf tobacco, and particularly to a method for controlling moisture absorption during drying after completion of drying.

(Prior Art) Conventionally, leaf tobacco has been dried using human's five senses with reference to a drying temperature table.

However, in recent years, the level of technology related to microcomputers has advanced, and leaf tobacco drying control methods and devices have been introduced. Specifically, a drying program as shown in Figure 4 is stored in a microcomputer, Control devices that are programmed with optimal operating conditions have become popular.

When drying leaf tobacco using a leaf tobacco dryer controlled by a microcomputer, as shown in the drying program in Figure 4, the drying temperature is 68°C, the wet bulb temperature is 40°C, and the relative humidity is 14%. Drying is completed after the final temperature conditions have been met, but the dried leaves immediately after drying have a moisture content of about 8%, which is over-dried, and there is a risk of them crumbling when removed from the drying room. Dry leaves cannot be removed.

For this reason, conventionally, after drying, the intake damper of the warm air generator is fully opened and the blower fan is turned to bring in natural outside air into the drying chamber for about 3 to 4 hours. I'm trying to take it out.

However, the effectiveness of moisture absorption using the natural outside air is greatly affected by the temperature and humidity conditions of the outside air, so it is mainly carried out early in the morning when the outside air conditions are good, and the dryer is not kept in the drying room until the next morning after drying is completed. It is often left hanging with dried leaves,
It is difficult to operate the dryer efficiently.

Furthermore, the effectiveness of the moisture absorption operation is greatly affected by the weather conditions after drying, which often causes problems with the quality of the dried leaves.

On the other hand, the optimal condition for dry leaves to absorb moisture is relative humidity.
It is known that the moisture content of dry leaves is 12% to 13%, with a dry bulb temperature of 25°C or less.

(Problems to be Solved by the Invention) The problem to be solved by the present invention is to artificially create optimal temperature and humidity conditions in a drying room to absorb moisture instead of absorbing moisture by natural outside air.

(Means for Solving the Problems) In order to solve the above problems, in the tobacco drying method of the present invention, after all processes for curing and drying are completed, the blower continues to operate and the tobacco is brought into the drying chamber. Forcibly supply outside air and use a cooling device if necessary to lower the temperature inside the drying chamber to 25℃, then humidify the drying chamber using a humidifier, and check the relative humidity sensor installed in the room or the dry bulb temperature. A sensor and a wet bulb temperature sensor monitor the relative humidity in the drying chamber and control the humidifier to maintain the relative humidity in the room at 70%, while a moisture sensor attached to the leaf tobacco monitors the moisture content of the leaf tobacco. Humidification and ventilation are stopped when the equilibrium moisture content of leaf tobacco reaches 12 to 13%.

(Function) According to the above technical means of the present invention, moisture absorption operation is performed under optimal conditions immediately after drying is completed,
By the end of the operation, the moisture content of the dried leaves will be the optimum moisture content that will not hinder removal.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

The method of the present invention is carried out using a leaf tobacco drying apparatus as shown in FIG.

In Fig. 1, A is a drying room, and B is a hot air generator. The drying room A and the hot air generator B are integrally installed adjacent to each other, and are opened at the bottom of a partition wall 1 that partitions them. They communicate with each other via a warm air outlet 2 and a circulation port 3 provided at the top of the partition wall 1.

The hot air generator B is equipped with a blower a, a furnace 4 constituting a heating device b, a heat exchanger 5, etc., and one of the side walls 6
is provided with an intake port 8 having an intake damper 7 at its upper part.

The drying chamber A is located at the same height level as the upper edge of the hot air outlet 2, or at a position slightly above it.
A floating floor 10 having a gap between the floor surface 9 and the floating floor 10 is provided, and the gap between the floor surface 9 and the floating floor 10 is used as a hot air introduction space 11.
That's what I'm saying.

The floating bed 10 has a large number of rectifying holes 1 over the entire surface.
2 is opened.

Further, the drying chamber A has an exhaust port 14 at the top of one of the side walls 13.

The hot air generated by the hot air generator B is blown into the hot air introduction space 11 between the drying room A floor surface 9 and the floating bed 10 from the hot air outlet 2, and then flows through the rectifying holes 12 of the floating bed 10. The flow is rectified through the drying chamber A, spreads uniformly throughout the drying chamber A, and flows upward, and part of it is discharged to the outside from the exhaust port 14, but the rest returns to the hot air generator B from the circulation port 3 and flows upward through the air intake port. It is heated again together with freshly drawn outside air from 8, and sent to the drying chamber A again.

That is, the drying chamber A is configured so that warm air circulates and flows inside the drying chamber A.

Further, a humidifier c is disposed in the warm air introduction space 11.

The humidifier c can be of various types such as an ultrasonic type, an evaporative type, a centrifugal type, a spray type, etc., but in the illustrated example, it is composed of a spray nozzle 16 connected to a water supply source via a water supply pipe 15. The nozzle tip is provided so as to face a hot air introduction space 11 between a drying chamber floor surface 9 and a floating floor 10 from a hot air outlet 2.

The water supply pipe 15 of the humidifier C is pulled out from the hot air generator B and connected to the water supply source, but in the middle of the pipe, a solenoid valve 17 for control and a strainer 1 are installed from the downstream side.
8, a pressure gauge 19 and a main valve 20 are provided.

When the control solenoid valve 17 and the main valve 20 are opened, water is sprayed from the spray nozzle 16 into the hot air introduction space 11. Therefore, if the blower a of the hot air generator B is operated at this time, the moisture caused by the fog will be transferred into the drying room A through the rectifying hole 12 along with the wind blown into the hot air introduction space 11 from the hot air outlet 2. will be sent to.

Further, in this dryer, a dry bulb temperature sensor 21, a wet bulb temperature sensor 22, a relative humidity sensor 23, and a moisture sensor 24 are provided in the drying chamber A, and each of these sensors 21, 22, 23, and 24 is equipped with a microcomputer 25. The control unit C is notified. The moisture sensor 24 is attached to a leaf tobacco rod suspended in the drying chamber A.

Therefore, in such a leaf tobacco dryer, the leaf tobacco is suspended from the leaf tobacco hanging device 26 and hung in two or three levels above and below inside the drying chamber A, and the temperature and humidity inside the drying chamber A are controlled. curing and drying.

The temperature and humidity are controlled by conventionally known methods until the end of the drying process.

That is, temperature control is performed by comparing the dry bulb temperature detected by the dry bulb temperature sensor 21 with a set value and controlling ON/OFF of the burner 27 of the furnace 4.
Humidity control is performed by comparing the wet bulb temperature detected by the wet bulb temperature sensor 22 with a set value and performing PI control on the intake damper 7 based on the deviation.

The burner 27 serves as a heat generation source for a hot air generator B that generates hot air and circulates the hot air inside the drying chamber A.The burner 27 is a heat generation source for a hot air generator B that generates hot air and circulates the hot air inside the drying chamber A.The burner 27 is a solenoid valve 29 provided in a fuel supply pipe 28 that sends fuel to the burner 27. by doing
The damper 7 controls the intake of outside air into the drying chamber A, and its opening degree is varied by rotating the motor 30 in forward and reverse directions.

Control of temperature and humidity by the burner 27 and damper 7 is performed by the microcomputer 25 based on a basic program.

Several types of basic programs are permanently stored in the ROM, depending on leaf formation position conditions and soil conditions, and the necessary basic programs are called up on the RAM according to the conditions.

Heat exchanger A is operated based on this basic program, gradually raising the temperature as time passes, and performing the fermentation process, yellowing process, color fixing process, and bone drying process. This is carried out sequentially, but after the completion of drying, that is, the back bone drying process, the burner 2
7 is stopped, intake damper 7 is fixed at 10% opening and operated for 30 minutes, then intake damper 7 is fully closed and only blower a is operated for 10 minutes, as shown in Figure 4. There is no difference.

However, in contrast to the conventional method, which operates the blower a for 10 minutes with the intake damper 7 fully closed, the program implementing the present invention completely stops the operation of the dryer and ends the program. Continue the program further.

That is, as shown in FIG. 2, the method of the present invention does not stop the operation of the dryer even after the intake damper 7 is fully closed and continues to rotate the blower a, and at the same time, the damper 7 is fully opened again to introduce outside air into the drying chamber A. , the temperature inside the drying chamber A is brought into equilibrium with the outside air temperature.

In this case, the outside air temperature is the temperature of the natural outside air around 5 to 6 a.m. in the early morning around July, which is the optimal condition for moisture absorption operation.
℃, and if the outside temperature during operation is 25℃ or higher, use a cooling device etc. to lower the temperature inside drying room A to 25℃.
Allow to cool down to ℃.

When the dry bulb temperature sensor 21 detects 25°C, the solenoid valves 20 and 17 of the water supply pipe 15 are opened to operate the humidifier c, and the humidifier c is then controlled to keep the relative humidity in the drying room A. maintain at 70%.

The humidifier c is controlled by opening and closing the control solenoid valve 17 based on detection by the relative humidity sensor 23.

As a result, the equilibrium moisture content of the dried leaves gradually increases from 8% at the end of the bone drying process.

Then, when the moisture sensor 24 attached to the leaf tobacco car detects the equilibrium moisture content of the leaf tobacco car to be 12 to 13%, the humidifier c and the blower a are stopped, all operations of the dryer are stopped, and the program ends.

After that, the leaf tobacco is taken out from the drying room A.

Note that the relative humidity can also be calculated based on the dry bulb temperature and the wet bulb temperature without using the relative humidity sensor 23.

(Effects) Since the present invention is configured as described above, the moisture absorption operation can be performed immediately after the end of the leaf tobacco drying process, and there is no need to wait until the next morning for the moisture absorption operation as in the conventional method. Operation rate can be improved.

In addition, because the optimal conditions for leaf tobacco to absorb moisture are artificially created in the drying chamber, quality problems are not affected by external conditions such as weather, and the quality is uniform and high-quality drying is achieved. You can get leaves.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of an apparatus for carrying out the leaf tobacco drying method of the present invention, Fig. 2 is an explanatory diagram showing an example of an implementation program of the main part of the present invention, and Fig. 3 is a diagram showing relative humidity and the equilibrium moisture content of leaf tobacco. FIG. 4 is an explanatory diagram showing an example of an implementation program for all steps of a conventional leaf tobacco drying method. A: drying room, a: blower, c: humidifier, 21:
Dry bulb temperature sensor, 22: Wet bulb temperature sensor, 2
3: Relative humidity sensor, 24: Moisture sensor.

Claims (1)

[Claims] 1 In a leaf tobacco drying method in which the drying process of leaf tobacco is controlled by a microcomputer based on a set program, after all processes for curing and drying are completed, the blower continues to operate and is forced into the drying chamber. Supply outside air and, if necessary, use a cooling device to lower the temperature inside the drying chamber to 25°C, then humidify the drying chamber using a humidifier, and connect the relative humidity sensor or dry bulb temperature sensor installed in the chamber. A wet bulb temperature sensor monitors the relative humidity in the drying chamber and controls the humidifier to maintain the indoor relative humidity at 70%, while a moisture sensor attached to the leaf tobacco monitors the moisture content of the leaf tobacco. The equilibrium moisture content of is 12
A leaf tobacco drying method characterized by stopping humidification and air blowing when the temperature reaches ~13%.