The Key Technology Research Of Rapeseed Low Dehumidification Drying

China is the largest contry of rape planting in the world, both the planting area and the annual output are rank the first. Rapeseed oil can be used as a cooking oil to improve people’s diet, but also can be used to make biodisel, with the food safty and the energy issues becoming increasingly prominent, enhance the rapeseed production technology is significant. The origin of rapeseed mainly concentrated in the Yangtze River region, the harvest time is in the rainy season, the weather conditions of high temperature and high humidity, excessive humidity prone to mildew during storage of rapeseed, which makes drying and storage become important in the canola processing chain. So we need to make some drying equipment for rapeseed drying, and make the equipment adapt to the environment, we need to do some research on the drying charactiristics of rapeseed, provide some theoretical basis to make drying equipment.This paper intended to use low-temperature drying dehumidification method, on the basic of understanding the rapeseed drying theory, Improved the low-temperature desiccant rapeseed test program. Choosed different hot air drying temperature, relative humidity test factors, conducted a thin layer drying characteristics test of rapeseed under different temperature gradient, humidity gradient. Analyzed different temperature, humidity drying properties of rapeseed and studied the effects of different temperature on rapeseed quality; According to the near-infrared quality analysis and germination rate test of rapeseed to determine reasonable drying temperature range; designed the dehumidification device for air dehumidification needs, and selected the appropriate desiccant, conducted a test of dehumidifier’s dehumidifying effect, the main conclusions obtained are as follows1. In the understanding of the main rape planting raea in China, air dehumidification equipment was improved. And developed a set of low temperature drying system which was suitable for rapeseed. The device can do dehumidification performance analysis for the liquid desiccant, dehumidify rapeseed at low temperature. According to the requirements of the test, it can provided the test with temperature at40-60℃, humidity at50%-70%. The whole device has the characteristics of compact structure and convenient operation.2. In the study of drying characteristics of rapeseed, set four temperature gradient respectively correspond to the three kinds of humidity, the initial moisture content of28%of canola were tested for the study, and analyzed it as followed:.(1)When the temperature of hot wind was constant, the lower the relative humidity was, the faster the drying rate. The influence of relative humidity on drying speed decreased with the increased of temperature. And the drying curves in the relative humidity of50%,60%and70%are in good agreement under high humidity condition. The advantage of dehumidification was not obvious under high temperature conditions. So the low temperature condition contributed to the drying rate of rapeseed.(2)When the relative humidity was constant, the higher the temperature was, the faster the drying rate became. Under the relative humidity of50%and60%, the drying curves in the temperature of55℃and60℃were in good agreement during the initial period of drying. It shows that under the low humidity, the influence of temperature on the drying speed was not evident. And the relative humidity influenced more greatly on the drying rate.(3) Rapeseed drying process was different from general materials drying process. There was no obvious speed stage during the process. Usually drying rate attained to its maximum after60minutes of drying and then flated. Finally it stabilizes after180minutes of drying.3.The influence of temperature on the quality of rapeseed was studied by near infrared analysis and germination rate experiment. It concluded that:under the temperature range of45to60℃, with the increase of temperature, two indexes-sulfur glucoside and erucic acid fall slightly. On the whole, the harmful substances were controlled in the range of national standards under low temperature of dehumidification. And the protein and oleic acid content was slightly higher compared to the high temperature drying. Temperature affected little on the germination rate during this temperature range. When the temperature rasied to80℃, germination percentage declined significantly as the temperature increased, even converged to zero. Germination rate increased gradually with the increase of temperature during45to55℃, then gradually reduced.4.Through the statistical analysis, the multivariate linear regression analysis was carried out on the drying curves. The results showed that the low temperature of rapeseed drying process can be described by the Page model. Its Page equation was as followed:...