无机灰分对餐厨沼渣中有机质热解特性的影响

Effect of inorganic ash on pyrolysis characteristics of organic matter of biogas residue from food waste

针对餐厨垃圾厌氧处理所产生的沼渣具有产量大、灰分质量分数高的特点,研究沼渣中无机灰分对其热解过程的影响.通过热重分析和热裂解−气相色谱质谱联用技术(Py-GC/MS)分析沼渣热解动力学特性及其产物.动力学分析结果表明,沼渣除灰后,失重速率显著提高,热解起始温度由180℃降至160℃.除灰沼渣的总表观活化能比沼渣的略高,原因可能是除灰使沼渣内部孔隙增加,在促进挥发分析出的同时,削弱了部分组分在热解过程中的催化裂解作用.产物分析结果表明,NaCl能够促进油相产物中烃类向酮类的转化,ZnCl2通过促进酸类的脱羧作用,使烃类质量分数提高至66.8%;Fe2O3和Al2O3使烃类物质的质量分数分别提高至66.8%和72.7%,CaO和MgO可以促进酸类脱羧生成酮,使产物中酮类的质量分数高达46.5%和39.4%.

The effect of inorganic ash in biogas residue on the pyrolysis of its organic matter was studied,aiming at the biogas residue produced by anaerobic treatment of food waste has the characteristics of large yield and high ash mass fraction.The kinetics characteristics and products of pyrolysis were analyzed by thermogravimetric analysis and pyrolysis-gas chromatography/mass spectrometry technology(Py-GC/MS).Kinetic results show that the weight loss rate increases significantly,and the pyrolysis initiation temperature decreases from 180℃to 160℃after ash was removed.The total activation energy of the ash-removed biogas residue is slightly higher than that of the biogas residue,the possible reason is that the ash removal treatment can increase the internal pores of the biogas residue,which can promote the release of volatiles,weaken the catalytic cracking effect of the ash in the pyrolysis.According to the analysis results of pyrolysis products,the NaCl can promote the conversion of hydrocarbons to ketones,and the ZnCl2 promotes the decarboxylation of acids to produce hydrocarbons,which increased to 66.8%in the oil product.The presence of metal oxides such as Fe2O3 and Al2O3 increases the content of hydrocarbons to 66.8%and 72.7%respectively,while the CaO and MgO promote the formation of ketones through the decarboxylation of acids,which are high up to 46.5%and 39.4%respectively.