Process Parameters Research Of Food-grade Inert Dust Circulation In Grain Storage

The food-grade inert dust aerosol technology is a high degree of mechanization,low cost,long-time protection and green environmental protection technology against stored-grain insects.At present,many grain depots in northern China have equipped with an internal circulation ventilation system,which provides convenience for the study of process parameters of food-grade inert dust circulation in grain storage.This paper provided a device and method for the detection of food-grade inert dust aerosol concentration in grain bulk.It studied the effect of food-grade inert dust circulation process in grain storage on the ecological factors of grain bulk,the lethal effect of temperature and relative humidity on stored-grain insects treated by food-grade inert dust circulation in grain storage,as well as the application of the food-grade inert dust circulation in a complete large warehouse and a partial filming large warehouse.The main research contents and results were as follows:In order to evaluate the distribution of food-grade inert dust inside the grain bulk,a device and a method for aerosol concentration detection inside the grain bulk ware provided.The device could sample the food-grade inert dust aerosol inside the grain bulk for a long-distance and a long-time from the outside of warehouses,and the concentration of food-grade inert dust aerosol in grain bulk could be detected by means of eliminating impurities.The food-grade inert dust circulation application process was carried out in vertical ventilation simulation test silo with ventilation speed of per unit area 0.0364 m/s,0.0816 m/s and 0.1253 m/s:the relative humidity inside the grain bulk were decreased by 7.9%,14.1%,21.4%respectively;the temperature inside the grain bulk decreased firstly and then increased,and finally were increased by 3.6℃,4.6℃,5.5℃respectively;wheat moisture content were decreased by 0.59%,1.03%,1.63%respectively;food-grade inert dust aerosol could penetrate the grain bulk of 0.4 m depth,the concentration of the space above the grain bulk>space inside the grain bulk>the space below the grain bulk.Changes of temperature,relative humidity and wheat moisture content in the food-grade inert dust circulation process were clarified,which proved the feasibility of applying food-grade inert dust in combination with the circulation ventilation system.After being treated by the food-grade inert dust circulation process,the test adults of Cryptolestes turcicus（Grouville）,Sitophilus zeamais（Motschulsky）and Tribolium castaneum（Herbst）at different temperatures（16℃,22℃,28℃）,relative humidity（45%,60%,75%）:the higher the temperature,the lower the relative humidity,the better the lethal effect of the process on the test adults;the LT₉₉ of the adults of C.turcicus was between 6.0 h and 26.3 h,and the temperature effect was extremely significant,and relative humidity was significant;the LT₅₀ of the adult of S.zeamais was between 32.7 h and 87.8 h,and the effect of temperature and relative humidity were extremely significant;the LT₅₀ value of the T.castaneum was 22.3 h to 119.3 h,and the temperature was significant,and the relative humidity was extremely significant.The influence of temperature and relative humidity on the control effect of food-grade inert dust circulation process was clarified,which had reference value for the application timing.The food-grade inert dust circulation process in a complete large warehouse and a partial filming large warehouse were carried out with a unit area of 0.0016 m/s and 0.0015 m/s,respectively:the food-grade inert dust was able to penetrate 0.3 m depth of grain bulk,and could not be detected at the depth of 0.6 m and 0.9 m;after 7 days’treatment,the corrected mortality rate of the adult of C.turcicus,Cryptolestes ferrugineus（Stephens）,and Cryptolestes pusillus（Oliver）reached 100%;the corrected mortality rates of the adults of S.zeamaisand,Rhyzopertha dominica（Fabricius）and T.castaneum were 84.8%,56.5%,65.0%respectively in whole warehouse circulation,while they were 86.2%,60.0%,68.5%in partial filming circulation;food-grade inert dust had no significant difference in the lethal effect of the adults of C.turcicus collected from grain depot or laboratory;2 processes had no significantly differences in the comparison of the detection indexes.The real large warehouse test verified the feasibility and effectiveness of the food-grade inert dust circulation process,contributed to a further promotion and application of food-grade inert dust aerosol prevention technology.This paper had clarified the influence of key parameters in the food-grade inert dust circulation process,which enabled the process to be controlled more finely,providing more theoretical basis and data support for further research,and providing research ideas for other stored-grain insects control technologies.This research was of great significance to the development of food-grade inert dust aerosol technology.