The Study Of Combustible Solid Waste Combustion In A Fluidized Bed Based On Source Separation

Combustion technology of municipal solid waste in a fluidized bed is applied widely dueto its higher combustion efficiency and lower pollution concentration. However, the issue ofsecondary pollutant and low energy conversion exists in the program of immediatecombustion of municipal solid waste. This article researched a fluidized bed combustiontechnology of combustible solid waste combined source separation and atmosphere control,which fulfilled zero emission and efficient energy utilization.Firstly, the effects of different factors on the combustion characteristics for combustiblesolid waste were studied by thermogravimetry. The results showed that: with the increasingaddition of PVC and NaCl, the TG curves all moved to higher temperature area and thebiggest weight loss rate reduced, the activation energy increased which were not constructiveto the combustion, the effect made by NaCl was bigger than PVC; the increasing heating ratewas helpful to the combustion which made the TG curve move to high temperature area andenlarge the biggest weight loss rate; the TG curve moved to lower temperature area with theincreasing oxygen concentration, the biggest weight loss rate increased and the activationenergy decreased which improved the reaction reactivity; the effect of Ca/Cl ratio oncombustion characteristics was little.The investigation was conducted in a fluidized bed which researched the effects ofmaterial ratio, bed temperature and oxygen concentration of furnace exit, CaO addition on thepollutant emissions from refuse derived fue（lRDF） combustion. The results showed that: thecritical fluidization air volume was4.8m³/h got from the cold test of fluidized bed; theincreasing plastic proportion in RDF leaded to lower CO emissions, higher SO₂and NOemissions, the HCl emissions increased more obviously; the higher bed temperature resultedin lower CO emissions and higher SO₂and NO emissions, but they maintained stable whenreached850℃; the bigger the oxygen concentration of furnace exit was, the lower the CO andHCl emissions were and the higher the SO₂and NO emissions were; with the increasing CaOaddition, the removal effect of SO₂and HCl concentration was better until a certain value but the NO emissions increased sharply; for the PCDD/Fs, the toxic emissions of PCDD/Fs washigh when RDF contain45%plastic and the emissions of RDF contained35%plastic was low,the control of plastic is necessary; the higher bed temperature can lessen the PCDD/Fsconcentration dramaticly, the concentration was1.408ng I-TEQ/Nm³at750℃, while theconcentration was0.1469ng I-TEQ/Nm³at850℃; the addition of CaO can lower theemissions, and the more CaO added into RDF, the lower the PCDD/Fs emissions was, theywere lower than the international standard.Finally, simulated the cold flow characteristics of fluidized bed and the combustioncondition of RDF based on FLUENT software. The cold flow field indicated the fluidizationwas well in furnace; the temperature field of RDF combustion showed that the temperaturewent up then decreaed from furnace bottom to top under different setted temperature, theaverage temperature in furnace was lower than setted temperature and the whole temperaturein furnace increased with inceasing setted temperature; the combustion effect was best at850℃from the concentrations field of CO₂and O₂; while combustion velocity field showedthat the higher temperature made the air movement more intense.