Technical Field of the Invention

The present invention relates to a fresh tea withering system with fluidized bed and microwave, which enables the withering process to be performed in a shorter time, even in low temperature applications.

The present invention relates to a fresh tea withering system with fluidized bed and microwave, which uses fluidized bed and microwave technology together and can also perform homogeneous moisture determination.

State of the Art

The withering process is the mandatory and most important step in the black tea production. In general, black tea production consists of 5 basic processes: withering, rolling, oxidation, drying, and sorting. Withering, in simple terms, is the process of physically transforming the tea leaf, the moisture content of which is reduced by hot air, into a suitable condition for rolling process. In the process, it is aimed to reduce the moisture content of the tea leaves from 70-80% to 58-62%. As a result of withering, the sap of the leaves becomes more dense and an elastic structure suitable for the rolling process is provided. Appropriate reduction of the moisture content of the leaves expected without withering completely affects the final quality of black tea production. Namely, in case fresh leaves are directly rolled without withering, or in case withering is inefficient, sap outflow and cell fractionation will not be completed. As a result, the leaves break rather than rolling, and the active substances in the tea are thrown out with the water flowing without rolling, during pressing.

Withering can be performed in two ways, natural or artificial (forced). In natural withering, tea shoots are withered under natural weather and temperature conditions. For this purpose, the leaves are laid on shelves with 10-15 cm intervals at a certain mass value per m2 and left to the natural withering process, which takes about 16-20 hours. Although it is stated in some sources that natural withering has a positive effect on the quality of tea, recent studies emphasize that tea comes out more colorful in long withering times, however, tea begins to lose its odor and aroma properties as a result of increased bacterial activity thereof. The obvious disadvantage of natural withering is that withering is completely dependent on the weather. It does not seem possible to achieve the daily tea processing capacity, especially in today's factories by means of the natural withering method. In this sense, all of the factories in our country produce black tea with the forced withering method. The main purpose of artificial (forced) withering is to provide a uniform and good withering by contacting the tea leaf with air with sufficient drying power at the appropriate temperature. Although there are various forced withering techniques, the most common withering method in today's factories is the withering on the movable trafs. In the movable system, the amount of fresh tea that the automatic fresh tea loading machine will take to the bunkers is adjusted to be proportional to the band speed and pouring thickness. By arranging these bands according to the tea processing conditions, regular feeding of the withering troughs in appropriate thickness is ensured. The movable withering system should not be stopped during production, except for mandatory situations. The main goal of withering is the same withering degree of the leaves. The withering time of the leaves varies according to the freshness and wetness of the fresh tea, weather, and working conditions.

The fact that the tea leaf is damaged by crushing and breaking before withering and deformation in various ways during transport to the factory causes some chemical events to start beforehand. This is undesirable and causes the oxidation mechanism to start prematurely. In addition, the wetness of the tea is an important parameter for the leaf condition. In case the tea coming to the factory is fresh, evaporation of the moisture in the leaves with hot air should be performed in a short time. On the other hand, while hot air reduces the moisture level of the leaf, it also destroys the bacterial activity. If the bacterial activity continues, the brew of the tea becomes cloudy and weak. In summary, the condition of the leaf greatly affects the final performance with withering.

Whether the tea leaves brought to the factory for processing are duly collected or not has a significant effect on withering. The number, size, and thickness of the leaves on the collected shoot are important in terms of withering performance. If the tea consists of three leaves and buds, the withering process becomes easier. On wizened leaves, the withering time is prolonged. Laying thickness: Laying too thick or thin has a negative effect on the uniformity of fading. For withering to be good, the thickness of the fresh tea laid on the withering troughs should not exceed 25 cm. Withering time: In the withering process of tea leaves, it is impossible to specify a specific withering time that can generally be applied. While this period takes 16-20 hours in natural withering, it is shorter in forced withering. It is applied around 6 hours in mobile withering systems in available factories in Turkey. Drying capacity of air: The drying capacity is closely related to the laying thickness of the tea, temperature, humidity, and air velocity. If sufficient moisture transfer is not achieved during withering, oxidation does not occur completely in the fermentation process. However, although such a system does not exist in the available factories, the withering efficiency is determined empirically. Since the same amount of fresh tea is not supplied to the factory every hour and it is not ensured that it continues uninterruptedly for 24 hours, there are fluctuations in the withering trafs, and this situation causes some tea leaves to wither and dry more, and some leaves not to wither. Again, the tea leaves cannot be laid on the trafs in a smooth and equal thickness, and there are differences between the withering degrees of the teas that are not laid properly.

The invention, which is the subject of the application numbered "CN209198330U" in the state of the art comprises a tea leaf withering moisture sensing device used to collect image and spectrum detection tea, which comprises an image and a spectrum acquisition module, an industrial camera near-infrared spectroscopy sensor, a light source, and a camera mounting frame. However, it is not mentioned designing fluidized bed and microwave technology for the withering process in black tea production in a single system.

The invention, which is the subject of the application numbered "CN209251606U" in the state of the art comprises a withering machine for tea production, consisting of a moisture-proof base and cabinet, in which the moisture-proof base of the upper outer wall is fixed with a frame and the frame on one side of the outer wall is machine- welded. However, it is not mentioned designing fluidized bed and microwave technology for the withering process in black tea production in a single system. There is a need for a system that can respond to the aforementioned problems in the moving withering trafs, which are widely used in today's factories, and thereby increasing the final quality in black tea production by reducing unit energy costs. In this innovative withering system, where the moisture content of tea leaves will be monitored by automatic control systems throughout the process, a homogeneous withering process is aimed by directing the withering air gradually obtained from the conditioning chamber to the fluidized bed tank at optimum blowing speed and angles. Since the moisture content and leaf conditions of the tea leaves coming to the factory will differ, a secondary miniature fluidized bed unit is being designed right next to the primary fluidized bed system in order to confirm the withering output characteristics declared in the standards and the enzyme values effective in withering under continuous production conditions, and thus, it is aimed to prevent performance fluctuations in withering, which is commonly encountered in withering operations in classical moving trafs.

Consequently, the disadvantages disclosed above and the inadequacy of available solutions in this regard necessitated making an improvement in the relevant technical field.

Objects of the Invention

The present invention relates to a fresh tea withering system with fluidized bed and microwave, which enables the withering process to be performed in a shorter time, even in low temperature applications.

The most important object of the present invention is to obtain a uniform moisture content and elasticity in the tea leaves at the withering outlet by means of the fluidized bed system; and to perform the withering in a very short time and with low unit energy costs with the help of the power-controlled microwave unit.

Another object of the present invention is to monitor the moisture content of tea leaves with automatic control systems throughout the process.

Yet another object of the present invention is to provide a secondary miniature fluidized bed unit right next to the primary fluidized bed system. Thus, performance fluctuations in withering, which are commonly encountered in withering operations in conventional moving trafs, are prevented.

Yet another object of the present invention is to complete the withering process of tea leaves suspended in the vertically positioned fluidized bed, which loses moisture thereof homogeneously with low withering temperatures, in very short time periods by means of the microwave unit integrated with the fluidized bed system.

Yet another object of the present invention is to reduce the unit energy costs by means of very low withering temperatures.

Yet another object of the present invention is to provide time dependent monitoring of the moisture content in the leaves before, during and after withering with the help of the automation unit integrated into the system.

Structural and characteristic features of the present invention as well as all advantages thereof will become clear through the attached figures and the following detailed description provided by making references thereto. Therefore, the assessment should be made by taking these figures and the detailed description into consideration.

Description of the Figures

Figure -1 illustrates the fresh tea withering system with fluidized bed and microwave, which is the subject of the invention.

Reference Numerals:

1. Gradual conditioning chamber

2. Primary suction line

3. Fan

4. Secondary suction line

5. Fan

6. Secondary outlet line

7. Primary outlet line

8. Air filter 9. Air filter

10. Secondary line

11. Primary line

12. Primary fluidized bed unit

13. Secondary fluidized bed unit

14. Leaf loading channel to the primary fluidized bed

15. Primary fluidized bed cyclone

16. Microwave generator mounted on secondary fluidized bed

17. Microwave generator mounted on primary fluidized bed

18. Primary fluidized bed cyclone

19. Air discharge unit

20. Blowing nozzle

21. Discharge line

22. Infrared sensor

23. Control Unit

Description of the Invention

The present invention relates to a next-generation automation-based hybrid withering system with fluidized bed and microwave that performs the withering process, which is the essential and first step in black/green tea production that most affects the average quality, in a fast, efficient, cost-effective, and environmentally friendly manner.

The fresh tea withering system with fluidized bed and microwave consists of gradual conditioning chamber (1 ), primary suction line (2), fan (3), secondary suction line (4), fan (5), secondary outlet line (6), primary outlet line (7), air filter (8), air filter (9), secondary line (10), Primary line (11 ), primary fluidized bed unit (12), secondary fluidized bed unit (13), leaf loading channel (14) to the primary fluidized bed, primary fluidized bed cyclone (15), microwave generator (16) mounted on secondary fluidized bed, microwave generator (17) mounted on primary fluidized bed, secondary fluidized bed cyclone (18), air discharge unit (19), blowing nozzle (20), discharge line (21 ), infrared sensors (22), and an automatic control unit (23) that feeds the entire system. A certain amount of fresh tea leaves is taken to the primary fluidized bed unit (12) from the leaf loading channel (14) to the primary fluidized bed with the help of the control panel connected to the control unit (23) according to the desired process capacity. Leaf condition, moisture content, and elasticity thereof are detected by infrared sensors (22) and pre-withering data is directed to the information panel in the automatic control unit (23). The characteristics of optimum withering air are determined by the feedback to the gradual conditioning chamber (1 ). Withering air, which is conditioned to appropriate dry bulb temperature and relative humidity come to the primary discharge line (7) via the primary suction line (2), and from there to the air filter (8) of the primary line by means of the fan (3) that is connected to the primary line and that feeds a primary suction line with volumetric flow control. The post-filtration withering air, after a filtration, reaches the primary fluidized bed unit (12) through the primary line (11 ). Withering air from the blowing nozzles (20) at the optimum blowing speed and angle is delivered to the fresh tea leaves. The fresh tea leaves suspended in the primary fluidized bed unit (12) begin to lose moisture in a uniform manner, and simultaneously, a mass transfer occurs from the system to the external environment with the help of the air discharge unit (19) connected to the fluidized bed unit. Energy is transferred to the suspended fresh tea leaves simultaneously with the microwave generator (17), which is mounted on the power- controlled primary fluidized bed mounted on the side walls of the primary fluidized bed, and by means of this process, which directly targets the moisture content in the leaves, mass transfer occurs in a remarkably fast manner. Thus, long process times for withering that are encountered in conventional applications are avoided. During withering, there is a primary fluidized bed cyclone (15) in order to keep the wastes that may cause environmental pollution such as dust, particles, etc. that may enter into the discharge line. Infrared sensors (22) are utilized to measure leaf condition, moisture content, and elasticity during and after withering. After the final withering target is obtained in the primary fluidized bed unit (12), the withered tea leaves are transferred to the secondary fluidized bed unit (13). Here, both the final color, moisture content, and elasticity characteristics of withered tea leaves are checked before rolling, and it is ensured that the tea leaves retain their existing internal structure, effective enzyme, and withering characteristics for a certain period of time without being affected by open environment conditions during possible disruptions in the rolling step or in a further process step. When needed, the secondary fluidized bed unit (13) is also connected to the gradual conditioning chamber (1 ), and in this part, withering process also can be continued by means of the additional secondary fluidized bed unit (13) and the microwave generator (16) mounted on secondary fluidized bed. Similarly, in such a case, air, which is filtered from the secondary suction line (4) to the secondary discharge line (6), and then the air filter (9) with a second power-controlled fan (5), is directed to the secondary fluidized bed unit (13) through the secondary line (10). At the end of the process, the withered tea leaves are delivered for the rolling process through a discharge line (21 ).

The gradual conditioning chamber (1 ) allows for supplying withering air with different dry bulb temperature and relative humidity at a given volumetric flow capacity, to the primary fluidized bed unit (12) and the secondary fluidized bed unit (13), simultaneously.

Fan (3) has a stepped electric motor that supplies withering air at optimum volumetric flow rate to the primary fluidized bed unit (12) by the feedback it receives from the automatic control unit (23). Fan (5) has a stepped electric motor that supplies withering air at optimum volumetric flow rate to the secondary fluidized bed unit (13) by the feedback it receives from the automatic control unit (23).

The primary fluidized bed unit (12) has a vertical cylindrical geometry in order to avoid dead volume in the unit and to obtain a uniform withering when the tea leaves are suspended. The primary fluidized bed unit (12) has on its inner side walls the microwave generator (17) mounted on power controlled primary fluidized bed. A primary fluidized bed unit (12) is characterized by having infrared sensors (22) on the upper wall that can measure the leaf condition, moisture content, and elasticity of the tea leaves, before, during, and after withering

The secondary fluidized bed unit (13) has the microwave generator (16) that is mounted on the power-controlled secondary fluidized bed, and that is integrated in the upper wall. Primary fluidized bed unit (12) and secondary fluidized bed unit (13) have a primary fluidized bed cyclone (15) and a secondary fluidized bed cyclone (18) integrated into the fluidized bed outlet in order to retain dust, dirt, etc. particles that may enter into the discharge line during the process.

The air discharge unit (19) allows for discharging bad air from the system continuously or periodically. The blowing nozzles (20) can supply withering air to the fluidized bed at the optimum blowing angle and speed. The discharge line (21 ) ensures that the withered tea leaves with optimum characteristics come to the rolling step without being affected by the outdoor conditions. The control unit (23) provides information transfer with artificial intelligence algorithm between gradual conditioning chamber (1 ), primary line fan (3), secondary line fan (5), blowing nozzles (20), microwave generator (17) mounted on primary fluidized bed, microwave generator (16) mounted on secondary fluidized bed, infrared sensors (22), and air discharge unit (19).