密闭空间内有机化学品挥发动力学在线检测系统

An online system for determining the volatilization kinetics of volatile organic compounds (VOCs) is constructed to solve the problem that it is difficult to dynamically determine the concentrations of VOCs in the atmosphere of nuclear power containment and to evaluate the consequent fire disaster risk during pressure test. A seal cavity is used as the volatilization container, and a gas chromatograph is used to determine the gaseous concentrations of chemicals in the atmosphere. A gas pump is used to circulate the gas with the gas flow rate controlled by a mass flow controller to offer convection condition for chemical volatilization. The gas chromatograph samples gas via a six-way automatic injection valve to determine the concentrations of VOCs online. Components of the system except for gas chromatograph are placed in an incubator for temperature and pressure control. The stability and accuracy of the proposed system are tested based on the volatilization curves and equilibrium vapor pressure values using n-butanol and ethylbenzene as the model chemicals. The results show that the volatilization curves of n-butanol and ethylbenzene fit pseudo-first-order kinetics in the range of 20℃-30℃, and the equilibrium concentrations are close to the theoretical data. These results show that the online system is stable and accurate, and its resulting volatilization rates could be used to evaluate the VOCs accumulation and fire disaster risk.