| The energy consumption on drying process amounts to a considerable ratio in total energy consumed in industry, the research of drying technology on the process for different materials has been in emphasized in terms of energy conservation. The drying quality of incense largely depends on the thermal physical parameters such as temperature, humidity and flow rate of the circulating air. The research into the drying process of the incense has always been a focus of public attention for a long time, but there still exists a bottleneck on matching the process control and the quality of the incense product. Because of its special ingredients, the drying characteristics of the incense were quite different and it is prone to bending or cracking, so the research of influences of the running conditions on the quality of incense product is crucial.Based on above ideas, the heat pump drying method is employed to set up an experimental unit for drying test. The volume of drying box is designed about 160 litters, and about 1.2kg incense in length of 0.97m and diameter were 0.025m. Experiments were carried out at different running conditions(air temperature:40~45℃, 45~50℃, 50~55℃, air volume: 14m3/min, 16m3/min, 18m3/min). Results demonstrated even temperature increments and a moderate amount of the circulating air were important to that's, the quality of the product incense in the drying setup designed, the appropriate duration of warm-up process is approximately 1.5hours, the optimum temperature increasing rate should be controlled less than 0.25℃/min, and speed of the circulating air should be below 1.7m/s.Experiment data were to use the relationship between the temperature of the circulating air and the circulating time, and ANSYS was employed to calculate temperature distribution within the pillar like incense at typical period. Results showed that, the even warm-up process was beneficial to the smaller temperature and gradient within the pillar like incense. Results also revealed that there was no large fluctuation of temperature and moisture content within incense at the drying process. Compared with the product of incense dried at different conditions, it demonstrated that the simulation meets well with the experiments. That is to say under the condition 2(the appropriate duration of warm-up process is approximately 1.5hours, the optimum temperature increasing rate should be controlled less than 0.25℃/min, and speed of the circulating air should be below 1.7m/s), the pillar like incense dried well with this setup will not crack.Experiments under different conditions were carried out to locate better values of running parameters for drying quality of the pillar-like incense. A conclusion was drawn that an even temperature increasing rate and air flow rate( as mentioned condition2 above)was preferable for the pillar-like incense drying. The temperature variation curves of the circulating air were fitted for finite element analyzing by using ANSYS software. It clarified that both results from the experiment and simulation fairly well. Moreover, the study in this dissertation can also be developed for investigation of the drying quality of the other kinds of incense. |
