Experimental Study Of VOCs Removal In Duct Photocatalytic Reactor

With the continuous improvement of people's living standards, coupled with China is currently in the purchase renovation boom, making large amounts of volatile organic compounds(VOCs) in the room, such as formaldehyde? benzen? toluene etc, seriously affect the indoor air quality(IAQ),cause harm to human health or even carcinogenic effect, indoor air purification treatment is imminent. Photocatalytic oxidation(PCO) technology energy saving, high catalytic activity, non-selective degradation, is an effective means of removing indoor VOCs. Now, the development of PCO technology involves reforming catalyst?optimization of reactor design and combined use of a variety of purification technology and so on, these modifications increase the reaction efficiency to a certain extent, but the lack of using PCO technology purifiers on the market, especially a purifier which can be applied to the heating, ventilation and air conditioning(HVAC) systems and an environmental chamber used in experiments, the relevant research literature is not much at home and abroad. Once the HVAC system is contaminated, contamination can fill the entire building through the air duct quickly, so it is very necessary to purify the HVAC system.Firstly, the article introduced a self-designed environmental chamber which can achieve different kinds of experimental conditions flexibly and the air duct air cleaner which can be used for HVAC system; secondly, we designed experimental program, and carried out experimental research carefully using the self-designed experimental system which is composed of an environmental chamber and a purifier; then determine the factors within a set range that influence on the formaldehyde degradation performance based on the experimental results, at the same time, determine the level of significance of various influencing factors and the optimum operating condition in the experiment of formaldehyde degradation utilizing the variance analysis; finally, conduct single-component experiment and two-component mixing experiments under the best operating conditions for formaldehyde, benzene and toluene, compare the experimental results, determine the mutual influence between some coexistence pollutants,at the same time analyze the reaction byproducts of toluene and benzene simply. The main conclutions of this research are as follows:(1) For self-designed duct air purifier, when the flow velocity is less than 3 m/s, the pressure drop of prototype is less than 60 Pa, under the same test conditions, the purification effect of Duct cleaner is 3.5 times as good as that of conventional flatbed reactor by comparing laboratory results.(2) Within a set range of each factor designed in this paper, with the aggrandizing of illumination intensity, the once-through efficiency?clean air delivery rate?conversion rate and reaction rate of formaldehyde are increased; when increasing the catalyst loading, four degrade performance of this purifier emerged slightly decreasing trend; once-through efficiency, clean air delivery rate and conversion rate are decreased with aggrandizing flow velocity, however the reaction rate has little variation.(3) We select clean air delivery rate as laboratory parameters, the orthogonal laboratory results indicate that: the magnitude of impact for Duct cleaner of three influencing factors in order, light intensity, flow rate, and catalyst loading, the optimum reaction conditions are A1B3C1, that are the catalyst loading 0.6mg/cm2, light intensity 320 lux, the flow rate of 0.9m/s, and proceed purification comprehensive performance evaluation to determine that this cleaner belongs to grade A in the best operating conditions, it has a better practical application.(4) The duct air purifier conversion rate of formaldehyde, toluene and benzene can be achieved 55%-69% within 1 hour after starting the experiments, its purification performance is good, the degradation property of toluene and benzene for the cleaner is similar, but the degradation property of formaldehyde is better.(5) The effect results of toluene and benzene are similar as either affect component or target component; when formaldehyde was selected as target component, its concentration rise, not fall within 2 hours after starting the reaction; the interaction effects between toluene and benzene were different from the influence of formaldehyde on them and the inhibition of formaldehyde was bigger.(6) It was found that benzene?benzaldehyde and benzoic acid were toluene primary reaction intermediates, and phenol was the major intermediate in benzene degradation; mineralization rate of toluene and benzene will decrease due to the effect of the presence of components, that is the degree of degradation weaken,and the effect of formaldehyde is even more.