论文总字数：40013字
摘 要
近年来，塑料制品需求量不断上升，但塑料难以自然降解，导致其固体废弃物大量积累，由此带来了严重的能源浪费和环境污染问题。快速热解技术可实现废塑料向高附加值燃油和化学品的高效转化，然而废塑料中氯元素含量较高，热解过程中会转移到产物中，造成产品氯污染，限制了后续利用。基于此，本文提出了废塑料水热-快速热解高效制备清洁无氯燃油的工艺。首先研究了未经预处理处理的废塑料快速热解制油特性和氯迁移规律，然后研究了废塑料水热预处理后，快速热解制油产物分布和氯迁移规律，并进行了详细对比。具体研究结果如下：
废塑料快速热解制油实验研究：选取PE、PP、PS与PVC混合物模拟废塑料原料，探究了热解温度、载气流速和原料粒径对废塑料快速热解产物分布和氯元素迁移规律的影响。结果表明，热解温度500℃、载气流速40ml/min为快速热解制油最佳工况，所得液体产率为67.88wt%，其中苯乙烯相对含量为33.14%。气体产率11.44wt%，其主要产物甲烷含量占27.64%。高热解温度、高载气流速与小颗粒粒径可促进快速热解过程中液体产物中的有机氯向气体产物中无机氯的转化。
废塑料水热预处理联合快速热解实验研究：该工艺首先对废塑料进行水热脱氯，同时废塑料表面得到预处理，而后进行快速热解制油实验研究。结果表明，水热预处理可实现废塑料原料的高效脱氯，水热脱氯率为90.86%。经水热预处理后，废塑料热解液体产物中有机氯含量降低89.62%，液体产率提升7.05wt%，油中轻质化组分含量升高。同时气体产物中甲烷含量提升17.81%。证实废塑料水热预处理联合快速热解是一种高效制备高品质无氯燃油的方法。
关键词：塑料；快速热解；生物油；水热；氯迁移；
ABSTRACT
In recent years, the demand for plastic products has been rising, but the plastic is difficult to be naturally degraded, resulting in a large accumulation of plastic solid wastes, which has caused serious energy waste and environmental problems. Through fast pyrolysis, waste plastics can be converted to high value-added fuels and chemicals efficiently. However, the chlorine contained in waste plastics will be transferred to the products during pyrolysis, which causes chlorine pollution and limits subsequent utilization. In this paper, the process of preparing clean chlorine-free fuel by hydrothermal-fast pyrolysis of waste plastics was proposed. The characteristics of pyrolysis oil and chlorine migration characters without pretreatment were investigated. And the distribution of fast pyrolysis oil products and the migration of chlorine after hydrothermal pretreatment of waste plastics were studied . The main research results are summarized as follows:
Experimental on fast pyrolysis of waste plastics: The mixture of PE, PP, PS and PVC was used to simulate waste plastics. The effect of pyrolysis temperature, carrier gas flow rate and particle size of the product distribution of fast pyrolysis and chlorine migration characters were analyzed. The results show that the yield of liquid products is 67.88wt% under the optimum conditions of pyrolysis temperature of 500℃and carrier gas flow rate of 40ml/min, and the relative content of styrene was 33.14%. The gas product yield was 11.44wt%, wherein methane was the main product and its content was 27.64%. For the chlorine migration characters, high pyrolysis temperature, high carrier gas flow rate and small particle size facilitate the conversion of organic chlorine to inorganic chlorine during fast pyrolysis.
Experimental on hydrothermal-fast pyrolysis of waste plastics: The process comprises the following steps: firstly, hydrothermal dechlorination of waste plastics, and the surface of the waste plastic is pretreated simultaneously, then a fast pyrolysis experiment research is carried out. The results show that the hydrothermal pretreatment can achieve high-efficiency dechlorination of waste plastics. The hydrothermal dechlorination efficiency was 90.86%. After hydrothermal pretreatment, the chlorine content in the liquid product obtained through fast pyrolysis is reduced by 89.62%, the liquid yield is increased by 7.05wt%, the content of light components is increased. Meanwhile, the methane content in the gas product is increased by 17.81%, which can be further recycled. It is confirmed that the hydrothermal-fast pyrolysis is an effective method for preparing high quality chlorine-free fuel.
Keywords: plastics; fast pyrolysis;bio-oil; hydrothermal; chlorine migration;
目 录
摘 要 Ⅰ
ABSTRACT Ⅱ
目 录 Ⅲ
第一章 绪论 1
1.1研究背景 1
1.2研究进展 2
1.2.1废塑料热解研究进展 2
1.2.2废塑料水热脱氯研究进展 3
1.3课题研究目标及内容 4
1.3.1研究目标 4
1.3.2 研究内容 4
1.3.3 研究路线 5
第二章 材料和方法 6
2.1实验材料 6
2.2实验方案 6
2.2.1水热预处理 6
2.2.2快速热解 6
2.2.3实验流程 7
2.3产物分析 8
2.3.1气相产物分析 8
2.3.2 液相产物分析 8
2.3.3固相产物分析 8
2.3.4无机氯的测定 8
2.3.5有机氯的测定 8
2.3.6脱氯效果分析 9
第三章 废塑料快速热解产物分布及氯元素迁移特性研究 10
3.1温度的影响 10
3.1.1产物产率 10
3.1.2油产物特征 11
3.1.3气产物特征 14
3.1.4氯元素迁移特性 16
3.2载气流速的影响 17
3.2.1产物产率 17
3.2.2油产物特征 17
3.2.3气产物特征 20
3.2.4氯元素迁移规律 21
3.3.颗粒粒径的影响 22
3.3.1产物产率 22
3.3.2油产物特征 23
3.3.3气产物特征 25
3.3.4氯元素迁移规律 25
3.5本章小结 26
第四章 水热预处理对废塑料快速热解的影响 28
4.1 热解产物分布 28
4.1.1产物产率 28
4.1.2油产物特征 29
4.1.3气产物特征 31
4.2氯元素迁移规律 32
4.3本章小结 32
第五章 结论与展望 33
5.1结论 33
5.2展望 34
致 谢 35
参考文献 36
第一章 绪论
1.1研究背景
塑料是一种由单种或多种小分子聚合成链状或网状具有特定功能的高分子量聚合物。由于其优异的性能和广泛的实用性，被广泛用于包装、建筑、航空、电子等行业中。2016年至2017年全球塑料产量由3.35亿吨增长到3.48亿吨。2018年，全世界的塑料生产量约为3.8亿吨[1]。据估计，世界各地的塑料产量以每年约5%的速度增长，塑料产量的提升使得塑料固体废物量逐年增长。2014年，全世界产生的25.8百万吨塑料固体废物中有30%被填埋处理[2]。而在许多发展中国家，超过60%的塑料固体废物被丢弃在空地或被填埋[3]。然而大多数塑料不可生物降解，在垃圾填埋场会持续存在近百年才能自然降解。由塑料固体废物的积累带来的环境问题不容小觑，其不仅导致温室气体排放量增加，提高火灾和爆炸的危险[4]；同时经过雨水或其他水源的浸泡，致使废塑料中相对亲水的毒性物质溶于其中渗入地下水造成地下水污染及一系列环境问题[5]。此外，随着塑料进入海洋，其分解为微塑料富集在海洋生物的体内，对人类和自然环境安全造成了严重的威胁，然而研究显示只有从地面阶段进行塑料垃圾的防治才可能由根本上解决塑料的污染问题[6]。
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