The Study on Low Concentration Carbon Dioxide Controlled Atmosphere Storage

摘要

The CO2 controlled atmosphere granary in Shanghai Grain Depot (China State Grain Reserve) was built in 2003. The minimum value of gas impermeability test in empty/full granary is 5.75 min and 4.87 min respectively. These values meet the design requirement. Furthermore, a package of methods to deal with gas impermeability solves the problems of soft groundwork and arch bar rips, which result from the sedimentation of full granary. On April 4th 2005, we began a study on wheat reserve under CO2 controlled atmosphere. Specifically,this work took placce in a CO2 controlled atmosphere granary and a normal granary. Through comparison, it found that : 1. In the wheat granary with the content of more than 3000 tonnes,it took 56 days for the content of CO2 to decrease from 81.3% to 34.1%. This data can meet the requirement of maintaining effective CO2 concentrations over the required duration. 2. In the reserved wheat under CO2 controlled atmosphere,no pests were found, including immature stages. Furthermore,no poison was left. Consequently, it was feasible to use CO2 as an innoxious insecticide. 3. In a following study,CO2 was decreased; under the environment of about 30% CO2, if the duration was more than 60 days or 80 days it could still restrain insects effectively. As a resuit,insect pests could be inhibited with the long CO2 duration and the cost could be reduced. In comparison with a normal granary,the CO2 controlled atmosphere granary has longerterm prevention of insect pests and slower quality deterioration of reserved wheat. 4. The cost of a CO2 controlled atmosphere granary is higher than in a normal granary. But if CO2 is held in low concentration and long duration, the cost could be reduced. Compared with phosphine, CO2 controlled atmosphere can not only kill insect pests but also avoid the harm and pollution of chemical fumigants.