Generation of phosphine gas for the control of grain storage pests

Abstract

The phosphine generator is a device for rapid production of phosphine (PH₃) gas to be introduced into grain storage. The aluminum phosphide (ALP) tablets are used as raw material and its effective constituent is 56%. When the aluminum phosphide and water are brought into contact a hydrolyzation reaction takes place to produce the phosphine gas. Controlling the reaction temperature, reaction pressure and the dosage of aluminum phosphide immersed in the water, the hydrolyzation reaction can be controlled or the output speed of phosphine generated can be controlled. If phosphine concentration exceeds the explosive limit, the phosphine easy catches fire and causes explosion. The carbon dioxide is an inert gas. Before the high concentration phosphine is released into air, using carbon dioxide dilute it to make the phosphine concentration diminution, until phosphine concentration is very low than the phosphine explosion limit. According to the amount of phosphine generated in unit time, mixing an amount  of carbon dioxide with it at the same time, controlling both proportion between phosphine and carbon dioxide can be realized. weight ratio between phosphine and carbon dioxide has been proved to be safe by practice. This ratio is 2% phosphine to 98% carbon dioxide. If the generation of phosphine gas can be controlled, the phosphine generator can be used for phosphine recirculation fumigation at low or high concentrations. The generator is operated outside of the storage structure and the phosphine gas is introduced into the structure, either directly through the gas distributor or through recirculation system which has a recirculation fan.

Keyword: Phosphine, Generator, Fumigation, Grain, Storage, Pests