Optimization Of Curing Process And Replacement Of Energy For Tobacco Bulk Curing

Focusing on improving the quality of tobacco bulk curing, optimization of curing process and replacement of energy were studied for tobacco bulk curing. First, the straw gasification technology was adopted to replace coal in tobacco bulk curing. From the perspective of biomass energy utilization, straw gasification saved a large number of precious coal resources, alleviated pollution from coal burning, and greatly reduced curing cost. The selected gas supplying modes showed different superiority, the "one to three" mode was obviously showed higher efficiency than "one to one" or "one to two" mode, and furthermore, it was more suitable for a tobacco farm to grow tobacco of about 10 hm2. Second, the effects of different loading modes of tobacco bulk curing were comparatively studied. Loose leaves mode and clip leaves mode saved the employment and time of loading and unloading leaves, meanwhile, they increased the capacity of installing leaves and obviously improved tobacco quality. The clip leaves mode was the most ideal one, its advantages were mainly embodied in the larger loading capacity, the higher efficiency and the less cost. In addition, its curing technique was similar to rod mode, it could replace the traditional rod mode and be widely applied. The mode of loose leaves curing was the development direction in the future. Third, the technology of air-curing tobacco before loading and changing three-layer to four-layer bulk barn was studied. By the mode of "change three layers to four layers", the density of loading leaves was increased, the curing times were reduced, the curing cost per acre was effectively reduced, the apparent quality of cured tobacco leaves was obviously improved, and the proportion of orange leaves was increased. Before loading tobacco, the fresh tobacco leaves were hanged to naturally become wilt and yellow, the average capacity of bulk curing barn was increased by more than 15%, meanwhile, the average curing time of tobacco were shortened by 6-7 hours and the average curing cost was reduced 0.23 yuan per kilogram dry tobacco leaves. Last, the key parameters of temperature and humidity of each stage was studied for tobacco bulk curing. When the main temperature of tobacco leaves turning yellow was appropriately raised, the time of steady temperature in late color fixed stage was extended, the humidity in early color-fixing stage was properly decreased, and the humidity in late color-fixing stage and stem-drying stage was properly raised, there were some good changes:the proportion of orange leaves was increased, the proportion of low-grade tobacco leaves was reduced, and the leaf structure was improved, as a result, the economic benefit was finally increased. The apparent and inherent quality of cured tobacco would be more ideal if the following approaches were adopted. The dry ball temperature of 38-40℃was suitable for tobacco leaves to become yellow. The wet ball temperature was controlled on 36℃in early color-fixing period, the duration was about 20 h and the wet ball temperature was controlled on 38-40℃when the dry ball temperature was 50-54℃. And the wet ball temperature was controlled on 40-42℃at stem-drying stage.In conclusion, the new approach of straw gasification instead of coal to cure tobacco was applied. The new loading modes of scattered leaves and cliped leaves in bulk curing barn were built. The key parameters of temperature and humidity of each stage was clarified for tobacco bulk curing. The technology of air-curing tobacco before loading and changing three-layer to four-layer bulk curing barn was explored. The study was beneficial to improve the quality of bulk cured tobacco.