脱水污泥超临界水气化利用中C:H:O对反应过程的影响

The high water content in dewatered sludge, which was coming from the wastewater treatment plant, had become an important limiting factor of sludge treatment and disposal process. However, supercritical water gasification was precisely using this shortcoming, which was changed the water in the sludge to supercritical water via high temperature and high pressure, and to achieve the purpose of sewage disposal. Moreover, supercritical water gasification could convert the organic matter to clean energy of hydrogen. Because of the complex distribution of water form and complex composition of the sludge (e.g.heavy metals, POPs, protein, polysaccharide), the problem of lower reaction efficiency and derivative pollutants produced has existing in supercritical water gasification reaction. How to achieve high efficiency, clean, industrialization gasification processes should be investigated. Based on four years of research on gasification sludge in supercritical water to produce hydrogen, propose an efficient technology that to use of the sludge dewatering direct supercritical water gasification. As the high concentrations reactant reaction process mainly by the C: H: O ratio influence. So in this study follow the principle of C: H: O ratio of change on reactant to influence the supercritical water reaction, to research the process of sludge gasification via supercritical water, know the key product of sludge gasification, and the control of the reaction conditions. Besides, according to this study, a theoretical basis and technical support could be provided to achieve clean and high efficient sludge gasification technology via supercritical water.

污水厂污泥的处理处置过程中，污泥的高含水率成为处理处置方式的重要限制因素。而超临界水气化技术恰恰能够利用高含水率这个特点，将其转化为优势。通过将污泥中水分转化为超临界水，达到处理的目的之外，还能转化为清洁能源-氢气。由于污泥中水分形态复杂，物质成分复杂，超临界水气化中存在效率低，出现衍生污染物的问题，高效、清洁、可产业化的气化原理成为关键。基于对污泥超临界水气化处理产氢的四年基础性探索，提出了脱水污泥直接气化的高效超临界技术，而高浓度的反应过程主要受到C：H:O的影响。因此，从C:H:O变化条件下超临界反应的原理出发，研究污泥气化过程、产物、制御条件，为形成高效、清洁的污泥超临界水气化技术提供基础性理论依据。

超临界水气化制氢技术因其利用水的超临界状态，分解、气化有机物形成富氢的可燃气体。若将该技术用于污泥的处理与处置上，不但能解决污泥含水率高的问题，而且能将污泥中有机物气化为富氢的可燃气体。由于污泥中水分形态复杂，物质成分复杂，超临界水气化中存在效率低，出现衍生污染物的问题，高效、清洁、可产业化的气化原理成为关键。.对于理论上或者热力学上认为的超临界水完全气化反应，生成物仅为二氧化碳、 氢气、 一氧化碳及甲烷。反应物则简单的可以表示为 CHxOy 的化合物。可以认为在超临界条件下主导有机物与水反应过程的主要因素就是 C:H:O。而污泥浓度的变化，主要是参与反应水分的变化，也就是 H，O 的数量发生了变化。可以认为C:H:O 对超临界水气化反应过程的影响就是高浓度污泥（脱水污泥）超临界水处理中的 关键科学问题。.研究主要针对10种不同性质的脱水污泥，研究了以下内容：.①C:H:O变化条件下脱水污泥直接超临界水气化关键产物特性：不同性质脱水污泥进行超临界水气化，反应后总产气量随污泥有机质含量及C/H2O的增加而增加；焦炭含量随污泥含水率的降低及C/H的增加而增加；多环芳烃(PAHs)生成量随污泥挥发分含量及C/O的增加而增加。.②基于C:H:O脱水污泥超临界水气化介观反应动力学方程：基于集总的思想，将产物归为气相、水相、固相、油相四部分，提出了可能的反应路径，构建了脱水污泥超临界水气化反应动力学。.③阻断碳化反应及避免POPs合成的超临界水气化调控方式。以PAHs为例明确了脱水污泥超临界水气化反应过程中有机污染物的分布规律、生成机理、影响因素及抑制机理。通过添加Ni-H2O2复合催化剂可有效抑制中间产物的聚合反应，促进原有芳环化合物的开环反应，并促进开环产物气化产氢，在有效抑制PAHs生成的前提下，促进氢气产率提高约29倍。