Study On The Design And Experiment Of Biomass Fluidized Bed Gasifier

Biomass is an important primary and renewable energy resource, and how to utilize it reasonably, efficiently and cleanly has been attracted much attention. Biomass gasification technique, one of the most promising approaches of biomass treatment, is still limited in the laboratory. Many researchers have been carried out to study the biomass gasification technique and biomass fluidized bed gasifier. However, the patterns of fluidized beds are mainly biomass incinerator, and few biomass fluidized bed were used to biomass gasification. In this study, a 100 t/d fluidized bed gasifier was designed and heating calculation was calculated. And the cold-condition experiment, biomass incineration and gasification experiment was studied on a fluidized bed. Some conclusions were drawn as follows:(1) In this study, a 100 t/d fluidized bed gasifier was designed using corncob as raw material. Based on this, the parameters of critical fluidization velocity, gasifier structure, and number of blast cap, air distribution plate opening rate and fluidized bed resistance were designed and calculated.(2) The heat balance and efficiency of system were calculated of the designed gasifier. It is concluded that the total heat loss of the fluidized bed gasifier is 10.05% and the efficiency of system obtained 89.95%. The low heating value of gasification gas is 4.2 MJ/m3 and nitrogen heat loss is 1.5 MJ/m3.(3) The cold-condition experimental results showed that it was the optimal parameter for the fluidization of fluidized bed when the weight of bed material (quartz sand) was 1 kg and critical air volume was 36.02 m3/h. The material feeding experiment found that material feeding rate and control rate is into a linear dependence.(4) Biomass incineration and gasification study on a fluidized bed gasifier. Bed material (quartz sand) quality and corncob particle sizes as different effect factors were studied on incineration stability. The experimental results showed that 1 kg particle sizes 0.5 mm quartz sand bed material and corncob particle sizes 5-8 mm are most suitable for incineration. The effects of gasification temperature and equivalence ratio (ER) were investigated. The results showed that the concentration CO and H2 reached maximum and CO2 and O2 concentration are minimum when ER is 0.28. And gas low heating value maximum was 4.1 MJ/m3. With the gasification temperature varying from 700 ℃ to 850 ℃, the concentration of CH4 and CO were increased and CO2 and O2 concentration were decreased. The gas low heating value maximum was 5.8 MJ/m3.