Mechanism And Experimental Research On Thermal Treatment Of Organic Solid Waste

With the rapid growth of China's economy,the biogas residue,sewage sludge and industrial organic waste have increased sharply.Especially after the implementation of the classification policy of MSW,the production of biogas residue has increased rapidly.The co-incineration of multi-source organic solid waste based on municipal solid waste(MSW)incineration facilities is a major demand for our country's ecological civilization construction and sustainable urban development.This research paper is supported by the National Key Research and Develpoment Project of"Solid Waste Recycling"and the Key Research and Develpoment Program of Shandong Province.The thermal conversion characteristics of MSW with biogas residue,sewage sludge and industrial solid waste were studied,and the co-incineration was carried out based on large-scale MSW incineration equipment and pilot test platform.Based on the mechanism research and experiment results,the feasibility of co-incineration of MSW with biogas residue,sewage sludge and industrial solid waste was discussed.Firstly,the biogas residue produced by the anaerobic generation of food waste and waste plastic components(PE,PP)were selected to investigate the pyrolysis characteristics of single samples and the blends of the two,using TGA and GC/MS.The results showed that PE could greatly promote the removal of oxygen in the pyrolysis oil.However,the addition of PP did not promote the complete conversion of ketones.The Fe₂O₃ and Al₂O₃ in biogas residue significantly reduced the proportion of oxygenated components,and the content of hydrocarbon products increased from 55.1%to 66.8%and 72.7%,respectively,which was contributed to the catalytic deoxygenation activity and high selectivity to hydrocarbon products of Fe₂O₃ and Al₂O₃.Ca O and Mg O,as typical alkaline earth metal oxides,promoted partial decarboxylation,converted acids to ketones,and reduced the acid content from 35.0%to 1.7%and 3.2%.Secondly,the thermal conversion interaction of the typical biomass in MSW and rubber-plastic components was studied in this work.Xylan was used as the hemicellulose compound,and PVC was used as the representative component of typical waste plastics.The occurrence and influence of interactions were investigated,the results showed that the interaction between xylan and PVC reduced the activation energy by 26.2 k J/mol.The interaction between the two reduced the content of aromatic hydrocarbons in the pyrolysis oil,and promoted the content of oxygenated components such as alcohols and ketones.Based on the above pyrolysis mechanism research,using simulated MSW components,sludge,biogas residue and industrial waste(industrial waste paper and waste fabrics)as raw materials,the combustion characteristics experiments were carried out.The results showed that the incorporation of sludge,biogas residue and the two industrial wastes affected the reaction rate and the burnout rate,but no obvious effect was detected on the reaction temperature.The increase of the mixing ratio of sludge and industrial fabrics promoted the emission of CO,NO and SO₂flue gas pollutants,and the increase of the mixing ratio of industrial waste paper could reduce the emission of flue gas pollutants.Using the grate furnace of the domestic waste incineration treatment plant,the co-incineration of MSW,sludge and food waste was carried out,and the influence of co-incineration of sludge and food waste on the parameters of power plant equipment and flue gas emission was discussed.With the increase of the sludge in MSW,the average main steam volume and furnace temperature increased,and the ash reduction rate has increased.When the sludge ratio was less than 8.8%,the flue gas pollutant emission index fully meets the requirements of the EU emission standard.When the blending rate continued to increase,the SO₂ emission index exceeds the EU standard more times,but still meets the requirements of the GB18485-2014 emission standard.Due to the high moisture content of the food waste,the co-incineration of MSW and food waste decreased the main steam volume and the furnace temperature.NOx and SO₂ increased with the mixing of biogas residue,and the instantaneous emission concentration of CO increased too.Due to the high chlorine content in the food waste,the emission concentration of HCl increased significantly with the mixing of food waste.However,the emission concentrations of various flue gas pollutants were all below the emission limit of GB18485-2014,indicating the feasibility to mix sludge and food waste into MSW for co-incineration.The co-incineration of MSW and industrial waste was carried out based on the grate furnace platform.The results showed that when the industrial waste paper and fabric waste were mixed into MSW at a ratio of 6.25%(the total blending ratio of industrial solid waste was 12.5%),the flame temperature of the primary grate and the combustion status of the grate did not change significantly.In addition,the co-incineration had no obvious effect on the exhaust gas temperature.From the results of this work,interactions exist in the thermal conversion of multi-source organic solid wastes,which will affect the pyrolysis characteristics,pyrolysis product composition,combustion rate,burnout rate,flue gas composition and waste heat utilization steam parameters.For large-scale incineration systems,when the proportion of co-incineration is controlled below10%,this effect is generally controllable.