Multi-Scale Experimental Study On The Fire Risk And Combustion Characteristics Of Impregnated Activated Carbon

As excellent adsorbent,activated carbon is widely used in wastes treatment of food,agriculture,national defense and industrial.The global demand for activated carbon is large each year and it keeps growthing.However,a large amount of activated carbon is often one of the important fire loads in industrial plants and fire accidents of activated carbon occur frequently in the process of production,transportation and storage.,especially for the nuclear grade impregnated activated carbon whose calorific value is high.On the one hand,the addition of impregnant can lower ignition point of active carbon,on the other hand,to ensure the adsorption efficiency of activated carbon,an electric heater is put into air purification systems for inlet air heating to control of air humidity in a nuclear power plant.Therefore,it greatly increases the fire risk of the nuclear power plant with tons of activated carbon using.Once impregnated activated carbon burns,the burning activated carbon not only makes a lot of heat released,which will cause equipments and building structure damaged,but also makes filtering system failure and causes radiation gas leak.Both of the harm is immeasurable.In this paper,multi-scale experiments are used to analyze and evaluate the combustion performance of activated carbon.Based on the thermogravimetric experiment,a(T_P,DTG_p)map method and the relative fire safety model are developed to qualitatively and quantitatively analysis materials’ relative fire risk.In addition,a homemade adjustable penetrating air flow for the activated carbon combustion performance test platform was used to simulate of the air flow running environment of the nuclear plant iodine adsorption.A series of different wind speed through air flow spread of activated carbon ignition experiments were carried out to reconstruct the temperature field,study the influence of the wind speed on smoldering fire spread,condition for smoldering becoming fire and combustion reaction development process.Results of(T_P,DTG_p)map method and the relative fire safety model are consistent,namely the fire safety performance of impregnated activated carbon is only higher than that of XPS foam,but lower than that of charcoal and other three kinds of activated carbon.Although the activation energy of impregnated activated carbon is lower than the XPS foam’s,its fire risk is not necessarily greater than the XPS foam’s.Experimental study on activated carbon smoldering spread with different wind speed of air flow shows that the introduction of down-flow of air can promote the combustion reaction.The introduction of down-flow of air can largerly increase the longitudinal velocity and greatly shorten the total length of smoldering though it slows the horizontal smoldering spread velocity to some extent in the early stage.Furthermore,the introduction of down-flow of air can not only increase the area of the smoldering combustion,improve the temperature and area of the high-temperature field,but also plays a key role in transition from smoldering to open fire.