| With the rapid development of economy and urbanization,China surpassed America and produced the most amount of municipal solid waste(MSW)in the year of 2004,the treatment for MSWwas huge challenge for many cities and regions.In Chongqing landfill sites in city regions have limited capacity for landfilling,and in rural areas even worse many landfill sties are overwhelmed.Sewage sludge(SS)is unavoidable by-product in waste water treatment processes,the amount of SS accounts for 540 thousand tons per year in Chongqing,which need be treated properly.This investigation took MSW in Chongqing as an example,and combined with SS to produce refuse derived fuel-5(RDF-5),which was aimed to provide fundamental theory,“collection in village-producing in county-transregional treatment” for the structure of MSWM in rural areas,at the same time to find a novel approach for SS treatment.Firstly,in order to know the current situation of MSW management and to figure out the possibility of producing RDF-5,we explored an investigation about MSW treatment in Chongqing city regions and rural areas.Secondely,some pre-treatment processes were undertaken based on the specific characteristics of MSW in Chongqing,moisture,compact pressure,raw materials rate were taken into consideration for producing RDF-5;then we added SS into raw materials to produce SS-RDF-5 and explored the optimism technological parameters.Thirdly,Synthetical thermal analyzer was conducted to investigate the TG of raw materials and RDF-5 under various conditions,and based on kinetic theory subsection models for incineration and pyrolysis of RDF-5 and raw materials were simulated and checked,which resulted in thermal reactions and kinetic parameters.Fourthly,we applied flue gas analyzer(testo 350)to detect gas pollutants in flue gas of RDF-5 incineration;scanning electron microscope(SEM)and Fourier transformation infrared spectrum(FTIR)were applied for analyzing heavy metals in ashes of RDF-5.Finally,this thesis focused on the environment impact and economical efficiency of RDF-5 producing,life cycle assessment(LCA)and guidelines for greenhouse gas of Intergovernmental Panel on Climate Change(IPCC)were conducted to evaluate the side impact of producing RDF-5 and the economical efficiency.Some conclusions were drawed as following:(1)Organic matters in MSW of Chongqing is high,low heating value(LHV)is satisfied with the require of incineration,therefore,MSW has the possibility to produce RDF-5 after removing non-combustible materials.(2)15% of plastic,6% of paper,15% of bamboo and wood,9% textiles,and 55% of kitchen waste mixed with 8% moisture and then compacted under the pressure of 10 MPa could get fine RDF-5 pellets,which has good physical characteristics,expansion rate of RDF-5 was only 41.18%,7 day impact resistance index(IRI)was 61.(3)Using SS to replace kitchen waste to produce RDF-5 is possible,SS,plastic,paper,textiles,and bamboo and wood were mixed with 32.8%,39.54%,15.72%,6.24%,and 5.71% with 10% moisture and 15 MPa compact pressure would get RDF-5,which satisfied with long time and distance transportation.(4)Subsection models for incineration and pyrolysis were properly simulated RDF-5 and its raw materials incineration and pyrolysis reactions.For plastic four subsection reactions(2,1/2,2/3,and 2 orders reaction respectively)could fitted its incineration,only one 2 orders reaction could fit its pyrolysis;for paper,four subsection reactions(1,1/2,2/3,and 1/3 orders reaction)fitted its incineration as well as pyrolysis(1/2,1,2,1,and 2 orders reaction);for bamboo and wood,1/3 and 1/2 orders reactions could stand its incineration,2,1,and 2 orders reactions fitted its pyrolysis well;for textiles,two first order reactions could simulate its incineration,three reaction(1/3,2 and 2 orders reactions)fitted its pyrolysiss;for kitchen waste,6 squence first order reactions fitted its incineration,1,3/2and 3/2 orders reactions fitted pyrolysis;for SS,there 2/3 and two 2 orders reactions could match ist incineration,there reactions(1/3,3/2,and 3/2 orders)fitted its pyrolysis;for RDF-5,there are 7 subsection reactions(1/3,3/2,3/2,2,2,1/2,and 1 orders reactions respectively),four pyrolysis reactions(1/3,1,2,and 2 order reactions).(5)Combustible possibilities with the order of kitchen waste >textiles >RDF-5 > bamboo and wood >plastic >paper >SS.And the comprehensive index of combustion with the order of kitchen waste >textiles >SS >RDF-5 >bamboo and wood > plastic >paper.(6)To mix calcium with RDF-5 could reduce concentration of HCl in flue gas and amount of tar in pyrolysis,which resulted from the reaction between HCl and Ca2+.In the ash of RDF-5,with calcium there exist some compounds with carbonyl and C-Cl-1 groups,which absords heavy metals;with calcium in RDF-5 some stable heavy metals transfer to gas and unstable heavy metals could be fixed in ash,and increase the index of bio-availability of Cr and Pb,reduce the index of bio-availability of Zn.(7)Comparing to landfill and incineration,to produce RDF-5 would emit less greenhouse gas,the emission factor were 0.68,0.56,and 0.42 respectively.Therefore,MSW for RDF-5 producing has lower side effect(contribution for greenhouse gas)to environment. |
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