Effect of Sealing Treatment for Warehouse and Grain Surface in High Flat Warehouse on Natural Oxygen Reducing

摘要

The tested warehouse was the No. 8 warehouse of Beihai Grain Depot, State Grain Reserves, the reference warehouse was the No. 6 warehouse of Beihai Grain Depot, State Grain Reserves,the walls of the warehouses were brick-concrete structure and the thickness was 0.7m, the roof of the warehouse was steel roof truss structure, the length of warehouse was 56m, the width was 21 m, the height of grain pile was 6m;the warehouses have been equipped with grain temperature detection system and external fixed recirculation fumigation system. The sealing treatment process for warehouse and grain surface was as follows:performed repairing for cracks on terrace, wall surface and at wall corners with "two cloth and three times coating" method before warehouse-entry of corns; filled and sealed the gaps between vents of ventilating ducts and walls and crevices on wall-passing openings of cables;soft rubber gaskets were changed in the vents of ventilating ducts; after grain loading, performed sealing between the door of the warehouse and grain blocking plate and sealing for grain surface with "doubleslot and double-film" and "doubleslot and one-film" separately, the grain film was five-layer nylon co-extrusion film. After sealing, performed field airtightness test by negative pressure method with airtightness tester, the average 300Pa half-life was 275s. The average 280Pa half-life of the reference warehouse was 53.7s;it showed that the airtightness of the grain pile after treatment has been improved obviously. Sealed the grain pile of the tested warehouse for 45 days, and the concentration of oxygen in the grain pile was reduced from 20.5% to 9.7%, while the concentration of carbon dioxide increased to 4%. However, for the reference warehouse which has been also sealed for 45 days, the concentration of oxygen was only reduced to 16. 1%. It showed that under the. conditions of higher grain temperature and better airtightness, the corns produced that year and a higher pest density (23pcs/kg), the respirations of various organisms in the grain pile could reduce the concentration of oxygen in the grain pile and increased the concentration of carbon dioxide obviously. Although it could not kill the pests and microorganisms completely, it could have certain inhibition for growth of entomomycete. This research provides reference for application of low oxygen pest controlling and killing technology.