| In this paper,combination process of activated carbon adsorption-microwave desorption with catalytic combustion for VOCs treatment was investigated.The microwave can heat materials quickly,effectively and uniformly,so using a microwave desorption can enhance the efficiency and rate of desorption;after desorption,the VOCs can be eliminated by catalytic combustion,it can avoid secondary pollution.In the experiment,toluene was chosen for object pollutant and granular activated carbon(GAC)was chosen for adsorbent.The investigation of toluene adsorption with GAC was the first study unit in the experiment.The results indicated that the static and dynamic toluene adsorption capacity(30℃)of GAC was about 238 mg/g and 195 mg/g, respectively.The adsorption isotherm was Langmuir model.In the experiment,the GAC heating behavior in microwave filed was investigated. The results indicated that the GAC could be heated quickly in the microwave filed;for different microwave power,different highest temperatures were obtained;for higher thickness of GAC bed,the temperature rising rates and the highest temperatures were lower;when superficial gas velocity of carrier gas(N2)was small,it gave little influence for temperature rising rate,but when the superficial gas velocity was enhanced,the influence was also obvious.The key investigation in the experiment was GAC desorption with microwave irradiation.The results indicated that 400℃was an appropriate for microwave desorption;considered the power and nitrogen consume,7.3 cm/s was the best choice of carrier gas velocity.For higher thickness of GAC bed,the longer desorption time was needed.For different quantity of toluene adsorbed,the desorption time was similar.For bed thickness of 2cm,90%desorption efficency can be obtained in 40 min at the conditions of temperature of 400℃.and nitrogen velocity of 7.3 cm/s.The GAC modification effect by microwave irradiation was founded and investigated.in the experiment.The results indicated that modified GAC had higher toluene adsorption capacity than original GAC,the adsorption capacity increased with heating temperature increased.By analyzing the results,it indicated that the variety of GAC's pore structure and surface function were the main reasons for adsorption capacity enhancing.By comparing microwave irradiation to electrical heating,it indicated that the microwave heating had characters of quickly,uniform and whole heating for materials.Two new techniques:Microwave heating temperatures programmed desorption and microwave heating fluidized bed desorption were developed.The results showed that microwave heating temperature programmed desorption had higher energy utilization efficiency.At 300℃,carrier gas velocity of 73.4cm/s,microwave heating fluidized bed desorption can obtain 90%desorption efficency in 7 min,it can use air as carrier gas,so can save nitrogen.In microwave heating fluidized bed desorption,the arc discharge was found.The arc could decompose the toluene directly and could also cauterize the GAC.By SEM and GC anlysis,these two effects were all not obvious.In the paper,BP neural network was used for microwave desorption simulation.The results indicated that the simulation value had good coherence with measured value,it was showed that this method can be used for microwave desorption forecast.The process of desorption was analyzed in theoretic and a new viewpoint of "3-stage" was developed.The "3-stage" viewpoint was explained and analyzed by using desorption driving force and resistance force,Finally,combination process of microwave desorption with catalytic combustion for toluene abatement was investigated.The results indicated that CuMnOx/γ-Al2O3 had high catalytic activity of toluene combustion.In combination process of microwave desorption with catalytic combustion,the optimum volume flow rate ratio of carrier and air was 1:1. The toluene conversion efficiency was more than 90%,and most of operation time,the conversion efficiency was more than 95%.
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