Study On The Mathematical Model Of ClO₂ Preparation And The Indoor Disinfection System

Air is essential for human survival.But the pathogenic microorganisms in the air can enter the body by respiratory system,resulting in the spread of disease.Air disinfection is one of the important means to control indoor air pollution and improve indoor air quality.Chlorine dioxide disinfection is the most ideal in currently used methods of air disinfection.It has no stimulating smell,no carcinogenicity and teratogenicity.It is listed as Al level disinfectant by the United Nations World Health Organization(the WHO).When the concentration of chlorine dioxide in EPA(U.S.Environmental Protection Agency)regulations within the range of 0.1~0.28 mg/m~3,continuous sterilization can be conducted with not leaving people.It is especially suitable for large indoor public places.The ultimate goal of chlorine dioxide disinfection dynamic system is to prepare high purity chlorine dioxide and air mixed gas in 0.1~0.28 mg/m~3concentration.This paper is supported by the technology innovation fund for small and medium-sized enterprises of Jinan Technology Bureau and Science(201403044)and Technology Program of Higher Education of Shandong Province Education Department(J15LG05).The mathematic model of material balance is established theoretically for the chlorine dioxide generator of common structure.In the mathematical model,the reaction rate and the mass transfer coefficient are required.Therefore,the reaction rate equation is first determined by experiment.And then a safe and reliable chlorine dioxide disinfection system and compact equipment are designed,as the basis for the determination of the total mass transfer coefficient.The mathematical model is improved.Based on the mathematic model,the influencing factors of the concentration of chlorine dioxide and the yield of chlorine dioxide are analyzed.The operating conditions of the sterilization process are optimized and the control scheme is determined.The structure and parameters of the gas mixer are determined by CFD simulation,and the disinfection effect of the disinfection system is determined.The main research contents of this thesis are as follows:(1)Based on the the mass conservation of chemical reaction and the theory of gas-liquid mass transfer,the mathematical model of material balance of chlorine dioxide generator is established theoretically.(2)According to the experiment research of preparation of chlorine dioxide by sodium chlorite and hydrochloric acid at low concentration,the influence on the rate of sodium chlorite conversion is analyzed about the concentration of reactants,ratio,time and temperature.The reaction dynamics equation is derived according to the experimental data.The macroscopic dynamic equation provides theoretical guidance for the perfection of mathematical model and the design and operation of disinfection system and equipment.(3)A safe and reliable chlorine dioxide disinfection system and a compact structure of generator are designed.According to this system,by combination of experimental determination and MATLAB iterative calculation method,the expression of total mass transfer coefficient formula is derived.(4)The mathematical model is perfected according to the kinetic equation and the expression of total mass transfer coefficient.Factors to the operation of the disinfection system are orthogonally simulated using the mathematical model.Factors affecting the vapor phase concentration of chlorine dioxide and the eventual yield of chlorine dioxide are analyzed.Operating conditions are optimized and the control scheme is determined.(5)The the structure and parameters of the mixer of chlorine dioxide and air is identified.The mixer is an important equipment determining the effect of mixing in the disinfection system.The CFD(computational fluid dynamics)numerical simulation method is used to design the structure and parameters of mixer.Porous type venturi mixer is selected.The best operation parameter of the mixer is determined by means of orthogonal experiment simulation.(6)The effect of sterilization disinfection system is determined through experiment.The disinfection system is enabled and the bactericidal effect of the disinfection system is determined.Indoor air is up to biological standard after 30minutes sterilization.After 240 minutes,sterilization rate is nearly 90%.The mathematical model established in this paper can be used to guide the design and operation of chlorine dioxide preparation and disinfection system.This dynamic disinfection equipment is stable,convenient,low cost and it does not produce harmful residues.Its disinfection effect is good and it can meet the requirements of modern dynamic disinfection.The chlorine dioxide dynamic disinfection as a new air disinfection method,should have a broad market prospect in the air disinfection industry.