Experiment of parameter optimization of fiber roller-scraping device for banana stalk

Abstract: Banana stalk is the main byproduct of banana after harvest. According to statistics, the annual banana production is more than 9 000 000 t in China, and the banana stalk is about 36 600 000 t. Traditionally, quantities of banana stalk are discarded in the field to naturally decay in the main banana planting areas in China, which leads to serious environment pollution, disease spread, waste of resources and other problems due to thick and large banana stalk as well as its high moisture content. Recent studies find that the banana stalk not only contains a variety of nutrients and organic matter, which can effectively increase the organic content of soil, but also is rich in high-quality plant fiber that is light-weight with good moisture absorption and heat dissipation, so it suits for the production of high-grade paper, clothes, ties, and so on. But nowadays domestic and foreign researches most focuse on the immersion method and the biochemical method, and the development of banana stalk fiber extracting device is rarely reported both at home and abroad. Based on the above issues, a fiber roller-scraping device for banana stalk was put forward in this paper, which is mainly composed of clamping device, scraping anvil, scraping roller, cabinet, grid plate, smoothing device, output belt, rack, and recycling box. Before experiment, the roller scraping device needs to be installed in the platform of fiber scraping device for banana stalk, and the banana stalk needs to be cut into slices. After the machine operates steadily, the slices of banana stem are continuously brought into the space between scraping roller and scraping anvil (the distance is 5 mm) in the scraping device with the transmission of the clamping device. Scraping roller rotates with high speed by means of adjustable-speed electric motor power through conveyor belt, and when it scraping, the constant hit makes the banana stem fiber's biological tissue broken, and separates the disintegrating slag from banana stalk fiber. Meanwhile the disintegrating slag will drop into the recycling box along the tangent direction of scraping roller's motion under wind force created by scraping roller's rotation. After that, banana stalk fiber is brought into smoothing device by its own gravity. Then the remaining moisture of banana stalk fiber is exhausted in recycling box, and banana stalk fiber is output through output belt. In order to get the optimal parameter combination, the fiber extraction rate and fiber trash content were set as experimental indices and the scraping roller rotating speed, scraper number and scraping anvil arc length were set as test factors, and the single factor test was performed to get the best value range of factors and the change law. Then an orthogonal experimental design of response surface methodology (RSM) was employed to find the optimum technical parameter combination for preparing fiber from banana stalk. The results indicated that the optimum combination was that the scraping roller rotating speed was 1 800 r/min, the scraper number was 16, and the scraping anvil arc length was 60 mm. According to the results of verification test on experimental index, the output was 207.6 kg/h, the fiber extraction rate was 93.2%, the fiber trash content percentage attained was 15.7% and the energy consumption was 22.1 kW·h/100 kg. The device meets the standards of agronomic production and raw material in related industries.