Research On Incinerating VOCs By Fluidized Bed Incinerator

Atmospheric environment is the foundation that its quality will have a direct impact on human health. VOCs are major sources of pollution of atmosphere and its impact on the atmosphere has been worse and worse with the industrial development. People are paying more attention to it. Our country also has introduced emission limit standards to toluene and xylene. For this reason, this paper proposed disposal of VOCs with fluidized bed incineration technology. The technical study includes experiments and calculation base on mechanisms of chemical reaction kinetics in addition. At last, a number of important findings and conclusions are achieved.Small hollow balls of aluminum oxide are used as beds materials which reduces the flow rate of wind significantly. It has good effects on increasing the residence time, reducing chamber size and reducing flue gas heat loss.The experiments of incinerating ethylene and toluene have been done separately on bubbling fluidized bed and circulating fluidized bed. Several conclusions have been accomplished through studying on the concerned factor such as temperature, residence time and pollutant concentration. When burning ethylene on bubbling fluidized bed, conversion rates are over 95% under 600℃ and 700℃ as chamber temperature and the air flow rate is 30 m³.h^-1. 700℃ is better; The higher furnace temperature, the higher ethylene conversion rates is achieved. Temperature plays a more important role on conversion rate under high concentration; The combustion condition is worse and the concentration of CO is high under small flow rate. But it becomes better with the increase of wind speed. Long residence time benefits the conversion of ethylene. However, the impact is weaker when the time increases and can be ignored when time reaches some value. In order to get high conversion rate, longer residence time is necessary because its obvious effect under high pollutant concentrations. When incinerating toluene in circulating fluidized bed, the decomposition rate of toluene is over 94% under the condition 50m³.h^-1 and 850℃. Temperature is the key factor of conversion rate which will get better results among 970℃ -1000 ℃. Low temperature leads smoke which indicates poor combustion condition. The combustion turns better at 750℃ which is a critical temperature. The longer residence time the better combustion between 0.63s～0.75s under 850℃. Fluid bed performs better than fixed bed for the combustion of toluene because of the disturbance and better heat transfer caused by bed materials; CO concentration generally suggests the burning condition. Both used bubbling and circulating fluidized bed have the low NO_X emissions.The mechanisms proposed by P. Dagaut et al are used to calculate high temperature oxidation of toluene in Homogeneous Batch Reactor model embedded in CHEMKIN4.0. A series of conclusions have been achieved on different initial conditions. Many intermediate species are produced in the early time which will converse to CO₂ later. So it is a delay between decomposition of toluene and generation of CO₂; The higher reaction temperatures, the shorter residence time is...