the rapid development of economy also accelerates the throughput of cargoes transmission in the port. In the process of loading and  unloading cargoes, there are easily flammable and explosive cargos taking up more than 80% of the throughput. Take a port as an example, over the years, the annual oil (crude oil) amount loaded and unloaded takes up ober 50%, and other cargoes such as propylene, wood, rubber, linen and grain takes up over 30&. therefore, there is a larger risk to cause fire and explosion accidents in the process of port operation. The consequences are also more serious.