Technical status and research progress of tea drying machinery
The basic principle of tea drying is that hot air is used as a medium to remove excess water from tea, so as to achieve the purpose of tea drying. Microwave drying machinery, from the invention of the first automatic tea dryer in 1879 to the Empire dryer designed by Jackson in 1910, has already possessed three major components of modern tea dryer, namely stove, blower and drying chamber. Since then, the development of tea dryer has gone through more than 130 years, and many types have been developed. However, the basic structure of tea dryer has not changed much. It only makes full use of heat, saves fuel, improves work efficiency and drying uniformity. At present, the automatic chain tea dryer is widely used in China, compared with the early manual tea dryer.
Great improvements and advantages have been made to improve the efficiency and quality of tea production, which has played an important role in the development of tea industry. However, there are few improvements in this type of aircraft since its invention, but its basic structure is still made in the 1980s by imitating foreign prototypes, and its performance and standards remain basically at the level of the 1980s. With the development of modern production and the improvement of technological level, there are higher requirements for tea processing quality, working environment, automation and other aspects. This type of machine needs to be improved in structure, control and performance standards. Based on the data and the investigation and analysis of the actual production situation of tea dryer manufacturing and application, this paper summarizes and analyses the technical status and progress of tea dryer, aiming at finding out the research direction of technical improvement.
As one of the most important factors affecting tea quality, tea drying technology and operation have been continuously improved. From original manual operation to automatic operation, from traditional hot air drying to radiation drying, the production efficiency and quality of tea have been continuously improved. From the original drawer dryer to the present automatic chain dryer, there are many types of tea dryer, which can be divided into manual, semi-automatic and automatic according to the degree of automation; according to the drying method, it can be divided into hot air drying, metal conduction drying and radiation drying.
In order to improve the automation of tea dryer, Yin Hongfan et al. realized the computer real-time control of 6CH-20A tea dryer by establishing control model, wind temperature feedback system and leaf temperature feedback system in order to obtain a stable and real-time control dryer. The control system consists of main control board, power supply, interface, transmitter, speed detection and regulation, blade thickness, hot air temperature and outlet blade temperature detection devices. The experimental study proves that the computer control of tea dryer is possible and valuable. It can be applied in large and medium-sized tea factories, and is conducive to improving the quality of tea. However, the control system does not use anti-interference measures, there is a certain deviation in the temperature of the main cabinet when working, and long-term operation will affect the control accuracy. This control system has not been popularized in actual production. In the aspect of automation control, there are still some other researches worth reference in the tea processing.