Study On Combustion Characteristics Of Polyurethane Foam And Preparation Of Derived Fuel(RDF) In Waste Refrigerators

As the sixth largest polymer material,polyurethane foam（PUF）is widely used in refrigerator and freezer insulation materials due to its excellent thermal insulation performance,high mechanical strength and strong adhesion.However,with the iterative upgrading of refrigerators and freezers,more than 14 million units of waste refrigerators and freezers are dismantled every year in China,generating more than 100,000 tons of PUF waste,which has brought great pressure to this type of electronic waste disposal industry.At present,the PUF treatment and disposal methods of waste refrigerators are mainly landfill and incineration,among which the incineration treatment method has the disadvantages of incomplete combustion and polluting the environment with a large number of harmful gases.Therefore,this article focuses on the incineration of PUF waste,studying its thermal and combustion characteristics and process mechanisms,and using this knowledge to produce Refuse-Derived Fuel（RDF）from PUF waste.The article aims to optimize the process parameters for RDF production,analyze its combustion and pollution characteristics,and provide a scientific basis for PUF resource recycling.The results show that 20°C/min is conducive to the pyrolysis and combustion of PUF,and the residual residue is 25.94%and 1.36%,respectively.PUF pyrolysis is divided into two stages:water and small molecule precipitation and volatile decomposition,while PUF combustion is divided into three stages:water and small molecule volatilization,volatile combustion,residual volatile content and fixed carbon combustion.Kinetic analysis showed that the first and second stages of PUF pyrolysis and combustion conformed to the 2nd stage reaction kinetics,and the number of reaction stages in the third stage of combustion was 1/2.There is organic decomposition in the PUF pyrolysis process,which will generate a large number of esters and benzene compounds,but during combustion,aerobic conditions make most of the macromolecular organic matter produced by PUF decomposition be oxidized and burned into CO₂,although aniline compounds will still appear in the process,in addition to some direct volatilization,and eventually will be oxidized and burned to generate HCN,NOx and CO.The orthogonal test results show that the mechanical strength of RDF is best when the moisture content of the raw material is 10%,the particle size is 60-100 mesh,and the molding pressure is 15 MP,and the relaxation density is about 0.965 g/cm3 and the drop strength is about 92.3%.Through comparative experimental analysis,it was found that the high calorific value of RDF after mixing 8%WS,3%Fe₂O₃ and 3%Ca CO₃ reached 23.12 MJ/kg,among which the addition of Fe₂O₃ could reduce CO emissions and Ca CO₃ could promote NOx reduction.The analysis of the combustion characteristics of the final prepared RDF showed that the ignition temperature and maximum weight loss rate temperature of RDF moved to the low temperature region,the maximum weight loss rate was about 5.9743%/min,and the final residual residue was about 15.73%.The activation energies of the three weightlessness stages were 3.452 k J/mol,47.906 k J/mol and 24.201 k J/mol,respectively,and the activation energies of the first and second stages of combustion were lower than that of PUF.The pollution characteristics analysis of RDF,dynamic infrared and GC/MS results showed that when the combustion temperature of RDF was 520°C,there were only 4 products,the relative content was less than 0.5%,and the remaining main product was CO₂,indicating that the combustion pollutants of RDF were less produced,and SEM slag phase analysis showed that the residue particles were finer and the structure was looser,indicating that the RDF combustion was more sufficient.