JP7044341B2 - Tencha furnace and its temperature control method - Google Patents

Description

The present invention relates to a temperature control method in a drying chamber of a tencha furnace for producing tencha, which is a raw material for matcha.

Tencha is made by steaming the coated tea leaves and then drying them without kneading, which is the raw material for matcha. The shape is thin as the leaves unfold and are transparent, the color is bright green, and the flavor has a unique fire pot scent.

Conventional tencha production is steaming 71 → sprinkling cooling 72 → drying 73 → separation → finish drying. It is also characterized by using a tencha furnace for drying, and a unique scent is obtained by this tencha furnace. The tencha furnace for drying is a large size with a length of about 10 to 15 meters, a width of about 2 meters, and a height of about 2 to 4 meters (see FIG. 6). Further, since the combustion portion 74 is provided underground, a pit 75 (dent) having a length of about 10 to 15 meters, a width of about 2 meters, and a depth of about 1 meter is provided.

Since the above-mentioned Tencha furnace has a high temperature of more than 200 degrees, the side wall is formed of heat-resistant and heat-retaining bricks. Therefore, in the manufacture of Tencha furnaces, parts other than bricks and bricks are brought to the tea factory where the Tencha furnace is installed, and bricks on the side walls are piled up and parts other than bricks are assembled at the tea factory.

The above-mentioned Tencha furnace is provided with a combustion unit 74 in an underground pit 75 portion, and the combustion air of the combustion unit 74 passes through the flue 77 and the inside of the Tencha furnace. The inside of the Tencha furnace is warmed by the flue 77.

The present applicant has applied for a mechanical device tencha furnace as in Patent Document 1 in order to solve the problem of a brick tencha furnace.

Japanese Patent Application 2015-214511

In general tea making machines (coarse kneaders, medium kneaders, dryers, etc.) other than the Tencha furnace, the tea leaves are dried directly with hot air, and the temperature of the hot air is controlled. To raise the temperature of the hot air, the output of the heat source (for example, combustion of the burner) is increased, and to lower the temperature of the hot air, the output of the heat source (for example, combustion of the burner) is weakened. These could be dealt with by so-called ON / OFF control and PID control.

In Tencha furnace, unlike other tea making machines, the tea leaves are not dried directly with hot air, but the combustion air is passed through the flue and the tea leaves are dried by the radiant heat emitted from the flue. It is the temperature inside the Tencha furnace that affects the drying of the tea leaves, but when measuring the temperature inside the Tencha furnace to control the output of the heat source (for example, the amount of combustion of the burner), the combustion air and flue can be used along the way. Due to the influence of the outside air temperature and the size of the Tencha furnace, it took time to change the temperature inside the Tencha furnace after controlling the output of the heat source. If the control was performed in the same manner as when the tea leaves were dried directly with hot air, the control was delayed, the temperature could not be controlled well, and it was difficult to stabilize the temperature in the Tencha furnace.

An object of the present invention is to provide a control method for stabilizing the inside of a tencha furnace to a desired temperature and a tencha furnace to be stabilized at a desired temperature.

The tea furnace of the first means of the present invention is a tea furnace in which combustion air is passed through a flue provided in a drying chamber to dry tea leaves in the drying chamber by radiant heat, and a temperature detecting means is provided in the drying chamber to obtain the temperature. A control means for changing the output of the heat source of the combustion air is provided so that the measured value of the detection means becomes a set value, and after changing the output of the heat source, a waiting time is provided, and the inside of the drying chamber during the waiting time is provided. It has a function of measuring a change in temperature and changing the output of the heat source according to the change in temperature and the measured value after the waiting time.
In the second means of the tea furnace temperature control method of the present invention, the temperature in the drying chamber is measured in the tea furnace in which combustion air is passed through a flue provided in the drying chamber and the tea leaves in the drying chamber are dried by radiant heat. After changing the output of the heat source of the combustion air and changing the output of the heat source so that the measured value becomes the set value, a waiting time is set and the change in the temperature in the drying chamber during the waiting time is measured. After the waiting time, the output of the heat source is changed according to the change in temperature and the temperature.

According to the present invention, the temperature in the drying chamber of the tencha furnace can be kept constant at all times, and the quality of the producted tencha is stabilized. Since the extreme output change of the heat source of the combustion air is eliminated, wasteful fuel is not consumed, which leads to energy saving.

FIG. 1 is an explanatory diagram showing the whole of the Tencha furnace. FIG. 2 is an explanatory diagram showing the flow of tea leaves in the Tencha furnace. FIG. 3 is an explanatory diagram showing the flow of combustion air in the Tencha furnace. FIG. 4 is an explanatory diagram showing a control screen of the Tencha furnace. FIG. 5 is an explanatory diagram showing a flowchart of the Tencha furnace. FIG. 6 is an explanatory diagram showing a control rule of the Tencha furnace. FIG. 7 is an explanatory diagram showing a control rule of the Tencha furnace. FIG. 8 is an explanatory diagram showing a control rule of the Tencha furnace. FIG. 9 is an explanatory diagram showing a conventional Tencha furnace.

The tencha furnace of the present invention is divided into a lower radiant heat drying section 1 and an upper hot air drying section 3. The radiant heat drying unit 1 is further divided into a first drying chamber 11 and a second drying chamber 21, with the first drying chamber 11 being the upper stage and the second drying chamber 21 being the lower stage. In this embodiment, the drying chambers 11 and 21 are separated by a partition plate 2. The partition plate 2 does not have to be installed, but it is better to install it in order to adjust the temperature of each of the drying chambers 11 and 21. The number of drying chambers is not limited to this.

A tea leaf supply section 4 is provided for supplying the tea leaves T to the first drying chamber 11. The tea leaf feeding unit 4 includes a hopper 42 for receiving the tea leaves T, a blower fan 41 for blowing the tea leaves in the hopper 42, and a tea leaf tea room 43. The tea-scattering chamber 43 has a side wall having good ventilation (wire mesh 44 in this embodiment) so that the air blown from the blower fan 41 can escape.

The first drying chamber 11 is provided with two stages of breathable endless transporters at the top and bottom, and the tea leaves T are separately transported by the tea leaf feeding unit 4 into these two stages of endless transporters (this embodiment). Then, it is 2 steps, but it may be 1 step or 3 steps or more). In this embodiment, net conveyors 12 and 13 are used as endless transporters. When the tea leaves T are conveyed in two stages, the total length of the net conveyors 12 and 13 may be half the normal length, respectively, and in this embodiment, the total length is about 6 m, the total length of the first drying chamber is about 5 m, and the width is about 2 m. .. Rotating brushes 12A and 13A are provided at the lower end of the net conveyors 12 and 13 so as to be in contact with the net conveyors 12 and 13. The first drying chamber 11 is provided with a combustion unit 16 provided with a burner as a heat source, and the inside of the flue 14 is filled with combustion air. As for the burner used for the combustion unit 16, the gas burner is easier to adjust the combustion and the exhaust than the heavy oil burner. In this embodiment, two gas burners 61 are provided in parallel in the width direction, but the number of gas burners is not limited to this.

Four to six flues 14 are provided horizontally from the combustion unit 16. If the first drying chamber 11 is evenly and sufficiently warmed, the number of flues 14 is not limited to this. The combustion air produced by the combustion unit 16 passes through the flue 14 and is guided to the flue 24 of the second drying chamber 21 through the flue 51 arranged outside the machine. Thermometers 18 and 19, which are temperature detecting means, are provided in the first drying chamber 11. The tea leaves T at the ends of the net conveyors 12 and 13 of the first drying chamber 11 naturally fall onto the net conveyor 22 of the second drying chamber 21.

The second drying chamber 21 is provided with one stage of a breathable endless transporter and six flues 24 in the horizontal direction. Again, in this embodiment, the net conveyor 22 is used as the endless transporter. The net conveyor 22 goes against the net conveyors 12 and 13 of the first drying chamber 11. A rotary brush 22A is provided so as to be in contact with the lower end of the net conveyor 22. An adjusting damper 54 and a damper lever 55 are arranged in the flue 51 arranged outside the machine in order to adjust the flow rate of the combustion air. By adjusting the flow rate of the combustion air, the temperature of each of the drying chambers 11 and 21 is adjusted. A thermometer 23, which is a temperature detecting means, is provided in the second drying chamber 21. A trough conveyor 25 for taking out is provided at the end of the net conveyor 22 of the second drying chamber 21, a hopper 26 is provided at the end of the trough conveyor 25, and the tea leaves T in the hopper 26 are chute 29 at the upper part of the hot air drying unit 3. A blower fan 27 and a blower pipe 28 for sending to the air are provided.

The portion where the tea leaves T fall from the net conveyors 12 and 13 of the first drying chamber 11 to the net conveyor 22 of the second drying chamber 21 does not have a partition plate 2, and the first drying chamber 11 and the second drying chamber 21 are connected to each other. , The moist air that forms the wind tunnel 17 and evaporates from the tea leaves T rises and is discharged by the upper exhaust port 15. (See the dashed line in Fig. 3)

The hot air drying unit 3 is provided with a stirrer 35 for thinly spreading the tea leaves T coming out of the chute 29, and is provided with four stages of breathable endless transporters 32A, 32B, 33A, 33B in the hot air drying chamber 31. ing. The number of endless transporters is not limited to this. The combustion air that has passed through the second drying chamber 21 is guided from the flue 52 outside the machine to the smoke exhaust control chamber 36 between the hot air drying unit 3, and the combustion air inside the smoke exhaust control chamber 36 is guided to the flue 53 outside the machine. , It is introduced into the hot air drying chamber 31 by the supply fan 37. An exhaust fan 38 for exhausting the hot air used for drying is provided above the hot air drying chamber 31. The outputs of the supply fan 37 and the exhaust fan 38 are adjusted by an inverter (not shown). This makes it possible to control the temperature inside the aircraft. The thermometer 30 (temperature detecting means) passes through the smoke exhaust adjusting chamber 36, the temperature of the hot air supplied to the hot air drying chamber 31 is measured by the supply fan 37, and the thermometer 40 (temperature detecting means) is inside the hot air drying chamber 31. Measure the temperature of. A screw conveyor 39 for taking out the tea leaves T is provided at the end of the endless transporter 33B.

Next, the movement of starting the Tencha furnace and putting the tea leaves T into it will be described. The tea leaves T that have been subjected to the blue-killing treatment are transported to the hopper 42 of the tea-spraying leaf feeding section 4. The tea leaves T that have entered the hopper 42 are blown to the tea-spreading chamber 43 by the blower of the blower fan 41, and when they fall, they are placed on the upper net conveyor 12 or the lower net conveyor 13. On the net conveyors 12 and 13, the tea leaves T are dried by the radiant heat.

The tea leaves T dried on the net conveyors 12 and 13 of the first drying chamber 11 fall onto the net conveyor 22 of the second drying chamber 21. At the time of falling, the position of the tea leaf T above and below, the position of the adjacent tea leaf T, and the contact with the net conveyor change.

Similarly to the first drying chamber 11, the net conveyor 22 of the second drying chamber 21 is also dried by radiant heat. The tea leaves T dried on the net conveyor 22 are taken out on the trough conveyor 25 and collected in the hopper 26. The tea leaves T are blown to the tea leaves T in the hopper 26 by the blower fan 27, passed through the blower pipe 28, and the tea leaves T are thrown into the leaf supply portion 34 by the chute 29.

The tea leaf T in the leaf feeding portion 34 is thinly flattened by a stirrer 35 and placed on the endless transporter 32A. The hot air in the smoke exhaust control chamber 36 is taken into the hot air drying chamber 31 by the flue 53 by the supply fan 37, and dried by the hot air. The temperature of the hot air drying chamber 31 at this time is about 80 degrees, and this temperature can be changed by the rotation speed of the supply fan 37. The moist air that evaporates from the tea leaves T rises and is exhausted by the upper exhaust fan 38. The tea leaves dried in the hot air drying chamber 31 are discharged to the screw conveyor 39, and are conveyed to the next machine (or transfer device) by the screw conveyor 39.

With the above flow, the net conveyors 12 and 13 are on the net conveyor 12 and 13 for about 1 minute to about 2 minutes and 30 seconds, the net conveyor 22 is on the net conveyor 22 for about 2 minutes and 30 seconds to about 5 minutes, and the endless transporters 32A, 32B, 33A and 33B are about. The tea leaf T can be satisfactorily dried in about 10 to about 40 minutes.

The display screen of the control device of the Tencha furnace is shown in FIG. Set the time and temperature and display the current temperature.

Next, a method of controlling the temperature in the Tencha furnace will be described with reference to the flowchart of FIG. First, turn on the power and operate the burner output at 100%. When the thermometer 18 reaches a predetermined temperature A set value (150 degrees as shown in FIG. 4 in this embodiment), the burner output is reduced to 80%. After that, the initial waiting time is set to 10 minutes in this embodiment. Even during this initial waiting time, the temperature A of the thermometer 18 and the temperature B of the thermometer 19 are measured every minute to monitor the temperature change. After 10 minutes of the initial waiting time, the burner output is changed according to the temperature changes of the thermometer 18 and the thermometer 19. After that, a quiet time (5 minutes in this embodiment) is provided, and the temperature A of the thermometer 18 and the temperature B of the thermometer 19 are continuously measured every minute during the quiet time to monitor the temperature change during the quiet time. Then, after the waiting time is over, the burner output is changed according to the amount of change in temperature and the difference between the measured temperature and the measured temperature. By continuing this, both temperatures A and B approach the set value.

The control conditions (conditions for changing the burner output) are shown in FIGS. 6, 7, and 8. By switching the display screen shown in FIG. 4, fine control conditions can be arbitrarily changed. By making the conditions finer, it is possible to automatically set almost the same settings as the worker's settings. For example, if the temperature A of the thermometer 18 is rising, the temperature B of the thermometer 19 is also rising, and the temperature B is 1 degree or more higher than the setting, the burner output is lowered according to the temperature. For example, if the temperature A of the thermometer 18 and the temperature B of the thermometer 19 are both rising and the temperature B of the thermometer 19 is the same as or lower than the setting, the output is set as it is and is not changed.

In this embodiment, control is performed by measuring the thermometers 18 and 19, but the number and position of the thermometers and the control method are not limited to this.

1 Radiant heat drying part 2 Partition plate 3 Hot air drying part 4 Tea powder leaf supply part 11 1st drying part 12 Endless transporter 12A Rotating brush 13 Endless transporter 13A Rotating brush 14 Flue 15 Exhaust port 16 Combustion part 17 Wind tunnel 18 Thermometer 19 Thermometer 21 2nd drying unit 22 Endless transporter 22A Rotating brush 23 Thermometer 24 Flue 25 Traf conveyor 26 Hopper 27 Blower fan 28 Blower pipe 29 Chute 30 Thermometer 31 Hot air drying chamber 32A Endless transporter 32B Endless transporter 33A Endless Transporter 33B Endless Transporter 34 Leaf Feed 35 Stirrer 36 Smoke Evacuation Adjustment Room 37 Supply Fan 38 Exhaust Fan 39 Screw Conveyor 40 Thermometer 41 Blower Fan 42 Hopper 43 Tea Scattering Room 44 Wire Net 51 Flue 52 Flue 53 Flue 54 Adjustment Damper 55 Damper Lever 56 Adjustment Damper 57 Damper Lever 71 Steam Heat 72 Scatter Cooling 73 Dry 74 Combustion Unit 75 Pit 76 Fukiage 77 Flue T Tea Leaves

Claims (2)

In a tea furnace where combustion air is passed through a flue provided in a drying chamber and the tea leaves in the drying chamber are dried by radiant heat, a temperature detecting means is provided in the drying chamber so that the measured value of the temperature detecting means becomes a set value. Is provided with a control means for changing the output of the heat source of the combustion air, and after changing the output of the heat source, a waiting time is provided, the change in temperature in the drying chamber during the waiting time is measured, and after the waiting time. A tea furnace having a function of changing the output of the heat source according to a change in temperature and a measured value . In a tea furnace where combustion air is passed through a flue provided in the drying chamber and the tea leaves in the drying chamber are dried by radiant heat, the temperature in the drying chamber is measured, and the heat source of the combustion air is set so that the measured value becomes a set value. After changing the output of the heat source and changing the output of the heat source, a waiting time is set, the change in the temperature in the drying chamber during the waiting time is measured, and after the waiting time, the temperature change and the temperature indicate the heat source. A method of controlling the temperature of a heat-reservoir, which is characterized by changing the output of .

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