【作者】 刘涛；

【导师】 张亚宁；

【作者基本信息】 哈尔滨工业大学 ， 能源动力（专业学位）， 2023， 硕士

【摘要】 随着社会经济的发展,塑料制品产量呈现递增趋势,为实现氢能的低碳化、清洁化发展,考虑将塑料热解转化为氢气对于氢能的清洁化发展和废塑料的资源化和高值化利用具有双重意义。本文先以未经加工的低密度聚乙烯、高密度聚乙烯和聚丙烯颗粒为实验原料、以四氧化三钴为微波吸收剂和催化剂,采用实验的方式探究了塑料颗粒/四氧化三钴的微波加热特性和微波热解制氢特性。考虑到实际生产生活中塑料制品与塑料原料可能有所差异,还以六种常见塑料制品为实验对象,探究废弃塑料与四氧化三钴混合物在微波场中用于制氢的可能性,并与塑料颗粒结果进行对比分析。对实验原料微波加热和微波热解制氢过程进行能量分析,对实验装置整体能耗有了更清晰的认识。塑料颗粒、四氧化三钴和塑料颗粒/四氧化三钴混合的微波加热特性如下——塑料颗粒在微波场中的升温性能很差:微波功率为350～550 W时,低密度聚乙烯颗粒和高密度聚乙烯的平均升温速率分别为1.600～3.280℃/min和2.430～4.220℃/min;微波功率为450～650 W时,聚丙烯颗粒的平均升温速率为1.920～4.230℃/min。四氧化三钴在微波场中具有优异的升温性能:微波功率为350～650W时,平均升温速率为5.426～20.936℃/s。四氧化三钴能明显改善塑料颗粒的升温特性:微波功率为350～550 W时,低密度聚乙烯颗粒/四氧化三钴和高密度聚乙烯/四氧化三钴的平均升温速率分别为45.215～85.800℃/min和25.117～147.150℃/min;微波功率为450～650 W时,聚丙烯颗粒/四氧化三钴的平均升温速率为26.638～147.150℃/min。各原料升温曲线拟合精度高,并通过拟合曲线得出各塑料颗粒的瞬时升温速率。反应终温、微波功率和四氧化三钴与塑料颗粒质量比在微波热解制氢时对氢气体积分数、氢气产率和氢气效率的影响如下——低密度聚乙烯颗粒在反应终温850℃、微波功率450 W、质量比为1时,氢气体积分数（81.428 vol.%）、氢气产率(47.812 mmol/g _LDPE)和氢气效率（61.070%）最高;高密度聚乙烯颗粒在反应终温850℃、微波功率400 W、质量比为1时,氢气体积分数（76.895 vol.%）、氢气产率(32.851 mmol/g _HDPE)和氢气效率（43.564%）最高;聚丙烯颗粒在反应终温850℃、微波功率500 W、质量比为1时,氢气体积分数（68.160 vol.%）、氢气产率(28.784 mmol/g _PP)和氢气效率（38.399%）最高。六种常见塑料制品的微波热解制氢特性如下——以低密度聚乙烯为主要成分的一次性塑料袋和塑料薄膜的氢气体积分数、氢气产率和氢气效率分别为65.561vol.%和79.840 vol.%、28.536 mmol/g_塑料袋和47.812 mmol/g_薄膜、55.652%和67.465%;以高密度聚乙烯为主要成分的洗发水瓶和牛奶瓶的氢气体积分数、氢气产率和氢气效率分别为66.416 vol.%和69.681 vol.%、24.926 mmol/g_洗发水瓶和27.578 mmol/g_牛奶瓶、37.145%和39.538%;以聚丙烯为主要成分的透明容器和一次性口罩的氢气体积分数、氢气产率和氢气效率分别为61.415 vol.%和61.785 vol.%、23.536 mmol/g_容器和22.474 mmol/g_口罩、34.027%和32.369%。对于塑料颗粒微波加热的过程,低密度聚乙烯、高密度聚乙烯和聚丙烯颗粒的能量效率分别为0.039%～0.077%、0.087%～0.117%和0.036%～0.085%;对于四氧化三钴的微波加热过程,能量效率为3.991%～7.961%;对于塑料颗粒/Co₃O₄混合物的微波加热过程,低密度聚乙烯、高密度聚乙烯和聚丙烯颗粒与四氧化三钴混合的能量效率分别为2.579%～4.694%、2.248%～7.737%和1.580%～5.574%。对于颗粒微波热解制氢过程,低密度聚乙烯颗粒在不同反应终温、微波功率和质量比的能量效率为27.071%～36.828%、27.071%～32.303%和22.610%～34.150%;高密度聚乙烯颗粒在不同反应终温、微波功率和质量比的能量效率为28.913%～37.913%、27.247%～29.229%和28.913%～34.453%;聚丙烯颗粒在不同反应终温、微波功率和质量比的能量效率为6.101%～24.537%、22.942%～28.689%和18.496%～26.401%。六种塑料制品的热解制氢能量效率均高于相同成分的塑料颗粒。更多还原

【Abstract】 With the development of social economy,the production of plastic products gradually increased.In order to realize the low carbon and clean development of hydrogen energy,it is doubly significant to consider the pyrolysis of plastics into hydrogen for the clean development of hydrogen energy and the resourceful and high-value utilization of waste plastics.In this study,the microwave heating performances of plastic particles and hydrogen production by microwave-assisted pyrolysis were investigated by using unprocessed low-density polyethylene,high-density polyethylene,and polypropylene particles as experimental feedstock and cobalt oxide was selected as the microwave absorbent and catalyst.Considering the possible differences between plastic particles and plastic products in practical production and life,six common plastic products were also used to explore the possibility of the mixture of waste plastic and cobalt oxide for hydrogen production in a microwave field and to compare and analyze the results with those of plastic particles.The energy analysis of the microwave heating process of experimental feedstock and the microwave-assisted pyrolysis process of hydrogen production provided a clearer understanding of the overall energy consumption of the experimental device.The microwave heating performances of plastic particles,cobalt oxide and plastic particles/cobalt oxide mixture are as follows.The heating performances of plastic particles in the microwave field were very poor.When the microwave power varied in the range of 350 W to 550 W,the average heating rates of low-density polyethylene and high-density polyethylene varied in the range of 1.600℃/min to 3.280℃/min and2.430℃/min to 4.220℃/min,respectively,and when the microwave power varied in the range of 450 W to 650 W,the average heating rate of polypropylene varied in the range of 1.920℃/min to 4.230℃/min.In the microwave field,the heating performance of cobalt oxide was excellent,when the microwave power varied in the range of 350 W to650 W,the average heating rate varied in the range of 5.426℃/s to 20.936℃/s.The heating performance of plastic particles could be improved by using cobalt oxide,when the microwave power varied in the range of 350 W to 550 W,the average heating rates of the mixture of cobalt oxide and low-density polyethylene and the mixture of cobalt oxide and high-density polyethylene varied in the range of 45.215℃/min to 85.800℃/min and25.117℃/min to 147.150℃/min,respectively,and when the microwave power varied in the range of 450 W to 650 W,the average heating rate of the mixture of cobalt oxide and polypropylene varied in the range of 26.638℃/min to 147.150℃/min.The temperature rise curves of each material were fitted with high accuracy,and the transient temperature rise rates of each plastic particles can be obtained from the fitted curves.The effects of reaction end temperature,microwave power and mass ratio of cobalt oxide and plastic particles on hydrogen volume fraction,hydrogen yield,and hydrogen efficiency during microwave-assisted pyrolysis for hydrogen production are as follows.It can be shown that for the low-density polyethylene,when the reaction end temperature,microwave power,and mass ratio were fixed at 850℃,450 W,and 1,respectively,the hydrogen volume fraction（81.428 vol.%）,hydrogen yield(47.812 mmol/g _LDPE)and hydrogen efficiency（61.070%）were the highest.For the high-density polyethylene,when the reaction end temperature,microwave power,and mass ratio were fixed at 850℃,400W,and 1,respectively,the hydrogen volume fraction（76.895 vol.%）,hydrogen yield(32.851 mmol/g _HDPE)and hydrogen efficiency（43.564%）were the highest.For the polypropylene,when the reaction end temperature,microwave power,and mass ratio were fixed at 850℃,500 W,and 1,respectively,the hydrogen volume fraction（68.160vol.%）,hydrogen yield(28.784 mmol/g _PP)and hydrogen efficiency（38.399%）were the highest.The microwave-assisted pyrolysis hydrogen production characteristics of six typical plastic products are as follows.The hydrogen volume fraction,hydrogen yield,and hydrogen efficiency of garbage bags and plastic films with low-density polyethylene as the main component were 65.561 and 79.840 vol.%,28.536 and 47.812 mmol/g_plastic,55.652 and 67.465%,respectively.The hydrogen volume fraction,hydrogen yield and hydrogen efficiency of shampoo bottles and milk bottles with high-density polyethylene as the main component were 66.416 and 69.681 vol.%,24.926 and 27.578 mmol/g_plastic,37.145 and 39.538%,respectively.The hydrogen volume fraction,hydrogen yield and hydrogen efficiency of transparent containers and disposable masks with polypropylene as the main component were 61.415 and 61.785 vol.%,23.536 and 22.474 mmol/g_plastic,34.027 and 32.369%,respectively.During the microwave heating process,the energy efficiency of low-density polyethylene,high-density polyethylene,and polypropylene varied in the range of 0.039%to 0.077%,0.087%to 0.117%,and 0.036%to 0.085%,respectively,and the energy efficiency of cobalt oxide varied in the range of 3.991%to 7.961%,and the energy efficiency of the mixture of cobalt oxide and low-density polyethylene,the mixture of cobalt oxide and high-density polyethylene,and the mixture of cobalt oxide and polypropylene varied in the range of 2.579%to 4.694%,2.248 to 7.737%,and 1.580%to 5.574%,respectively.During the microwave-assisted pyrolysis hydrogen production process,the energy efficiency of low-density polyethylene at different reaction end temperatures,microwave powers and mass ratios varied in the range of 27.071%to36.828%,28.470%to 32.303%,and 22.610%to 34.150%,respectively,and the energy efficiency of high-density polyethylene at different reaction end temperatures,microwave powers and mass ratios varied in the range of 28.913%to 37.913%,27.247%to 29.229%,and 28.913%to 34.453%,respectively,and the energy efficiency of polypropylene varied in the range of 6.101%to 24.537%,22.942%to 28.689%,and 18.496%to 26.401%,respectively.The energy efficiency of hydrogen production by pyrolysis of six kinds of plastic products is higher than that of plastic particles with the same composition.更多还原