The Influence Of Ventilating In The Bulk Curing Barn On The Curing Environment And Curing Effect

The influence of ventilation condition to cured tobacco leaves quality during the process of flue-curing in the bulk curing barn of 800cm×270cm×330cm was studied in this paper. The trial was carried out in the experimental points of Luoyang city Henan province and Baoji city Shanxi province during 2007-2008. Main results are as follows.1. With the condition of the same loading density, the greater of circulating fan power in bulk curing barn, the smaller of temperature and humidity difference in each curing stage. If the circulating fan power was same, the bigger of loading density, the greater of temperature and humidity difference in the bulk curing barn. The plane temperature difference were all the least in yellowing stage for each treatment, between 2.1-2.9℃, but it was the most in color-fixing stage, between 2.2-3.2℃. As far as the same treatment at the same burning stage were concerned, the vertical temperature was bigger than plane temperature difference, the most temperature difference was 3.6℃, the least temperature difference was 2.1℃. The most plane humidity difference of each treatment during the flue-curing was 1.1℃, the least was 0.2℃, the most vertical temperature difference of them was 2.4℃, the least was 0.9℃.2.If the pilot was near the heating chamber, the wind speed of it was bigger, and the farer of it being away from heating chamber, the smaller of vertical wind speed and plane wind speed. Meanwhile, the wind speed in bulk curing barn had great relationship with loading density and circulating fan disposition, if the fan disposition was same, the bigger of loading density, the smaller of wind speed, or otherwise. If the loading density was same, the bigger of circulating fan power, the bigger of wind speed in the barn. The vertical wind speed in the barn of each treatment was between 0.03-0.20m/s in yellowing stage, and plane wind speed was between 0.08-0.93m/s. The vertical wind speed was between 0.1-0.47m/s in color-fixing stage, and plane wind speed was between 0.13-0.93m/s. The vertical wind speed was between0.12-0.35m/s in stem drying stage, and plane wind speed was between0.15-0.56m/s. The wind speed of moisture removing ostium was between 0.11-0.73m/s in each treatment in yellowing stage, and it was between 0.12-1.32m/s in color-fixing stage, and it was between 0.14-1.12m/s in stem drying stage. 3.The treatment (D3P1) had too large loading density and too small circulating fan power in this experiment, the cured tobacco leaf color of it was light, and the cured tobacco leaf of it was thin, the proportion of smooth leaf was bigger, the proportion of first-class tobacco was smaller, the average price of it was lower. The treatment (D1P3) had too small loading density and too large circulating fan power, the cured tobacco leaf of it had bluish tendon. Combined with the cured tobacco leaf quality of each treatments, we found it was suitable wind speed at tobacco leaf clearance during the flue-curing, that the vertical wind speed was between 0.1-0.47m/s and the plane wind speed was between 0.41-0.75m/s in yellowing stage, the vertical wind speed was between 0.3-0.32m/s and the plane wind speed was around 0.55m/s in color-fixing stage, the vertical wind speed was around 0.26m/s and the plane wind speed was around 0.49m/s in stem drying stage, and the cured tobacco leaf of these treatments had a good comprehensive assessment of appearance quality, and the color of them was orange, the oil was sufficient, and the cured tobacco leaf was moderate, and had a bright luster and evenly leaf surface, and had a good aroma and taste.4.The analysis of cured-leaf intrinsic chemical composition of each bulk curing barn showed that the cured-leaf of treatments loading density of 35-40㎏/m3 equipping 1.1kW circulating fan and loading density of 50-55㎏/m3 equipping 1.5kW circulating fan had a proper content of routine chemical components, such as reducing sugar, total sugar, starch, total nitrogen, protein, etc., and the sugar-nicotine ratio and nitrogen-nicotine ratio were all relatively higher.5. The analysis of economic running situation of each treatment showed that the coal consumption and electricity consumption had no inevitable links with loading density and circulating fan power. Given the conditions that loading density not change, even the large power circulating fan could cost much electricity, but large power circulating fan could make the wind speed at tobacco leaf clearance strong, which could shorten the curing course in some degree, the coal consumption relatively reduced when the electricity consumption increased in some sort. Given the circulating fan power not change, the coal consumption of each treatment had less difference. Big difference was the difference of loading density and fan-location of each treatment induced the difference of temperature, humidity and ventilation during the flue-curing process, which made a big influence on the curing course. The results indicated that the treatments with less difference in temperature and humidity, and with proper wine speed at tobacco leaf clearance had high quality, because the cured tobacco leaves of them had higher proportion in first-class tobacco and had high average price.6.As far as the bulk curing barns with difference air motion direction were concerned, the conditions of temperature and humidity, the wind speed at tobacco leaf clearance and moisture removing ostium in the barns had less difference during flue-curing process, meanwhile, the difference of appearance quality and internal quality of cured tobacco leaves was little.