State multiplicity in CSTR-separator-recycle polymerisation systems

This article continues earlier work (Comput. Chem. Eng. 24 (2000) 209) concerning the design and control of isothermal reactor-separator-recycle systems. The multiplicity behaviour of six reaction systems of increasing complexity, from one-reactant, first-order reaction to chain-growth polymerisation, is investigated. Below a critical value of the plant Damkohler number, Da<Da^cr, the only steady state involves infinite flow rates. Feasible steady states become possible if the critical value is exceeded, Da>Da^cr. For one-reaction systems, one stable steady state is born at a transcritical bifurcation. For consecutive-reaction systems, including polymerisation, a fold bifurcation can lead to two feasible steady states. Moreover, the transcritical bifurcation is destroyed when two reactants are involved. If the gel-effect is included, a maximum of four steady states are possible. When multiple steady states exist, the achievable conversion is constrained by the instability of the low-conversion branch. This has practical importance for polymerisation systems when the radicals’ quasi-steady state assumption is not valid or the gel effect is significant.     

Technology for recycling and regenerating graphite from spent lithium-ion batteries

With the annual increase in the amount of lithium-ion batteries (LIBs), the development of spent LIBs recycling technology has gradually attracted attention. Graphite is one of the most critical materials for LIBs, which is listed as a key energy source by many developed countries. However, it was neglected in spent LIBs recycling, leading to pollution of the environment and waste of resources. In this paper, the latest research progress for recycling of graphite from spent LIBs was summarized. Especially, the processes of pretreatment, graphite enrichment and purification, and materials regeneration for graphite recovery are introduced in details. Finally, the problems and opportunities of graphite recycling are raised.     

发展循环经济解决辽宁老工业基地的环境问题

在介绍循环经济的内涵和发展的基础上 ,结合辽宁省的环境问题 ,提出了只有通过大力发展循环经济 ,才能尽快解决辽宁省的结构性、区域性环境污染问题     

强化环保设计,促进水泥工业的可持续发展

从烟(粉)尘排放总量控制、大气污染物排放标准、清洁生产、中水回用、环境绿化和加强环境法制观念等方面,提出强化水泥建设项目环保设计和建设、促进水泥工业可持续发展的想法和建议。     

熔模铸造型壳废弃物组成及其再利用分析

分别分析了最常用的水玻璃型壳和硅溶胶型壳在脱蜡后的型壳，焙烧后的型壳和浇注后清理的型壳废弃物的物相组成，即水玻璃型壳的主要物相是石英或Al-Si系材料物相；硅溶胶型壳的主要物相是Al-Si系材料物相。并依此提出了型壳废弃物资源化利用的一些途径：①作建筑材料，如水泥、沙料、砖、填料；②作熔模铸造的原材料，如耐火粉料和砂料、粘接剂、硬化剂。     

AZ91D镁合金中的夹杂物

就镁合金铸件中夹杂物的形成过程以及它们对镁合金铸件质量的影响进行了分析。试验研究表明,在镁合金中,主要存在有氧化物夹杂、熔剂夹杂和外来夹杂等几种夹杂物,其中最主要的夹杂物是氧化物夹杂。通过适当工艺可以去除大部分夹杂物。     

Windows系统回收站核心控制文件的作用分析

Windows 9x操作系统的回收站实际是系统实施特殊管理和维护的一个文件夹 ,而回收站文件夹的特殊性来源于该文件夹下面由操作系统自动建立的两个控制文件 ,对这两个特殊控制文件的结构与作用进行详细分析将揭示回收站文件夹的工作机理。本文通过分析控制文件的结构与作用 ,彻底揭开了回收站神秘的工作模型和算法。理解回收站文件夹的工作原理将十分有利于借鉴操作系统管理特殊文件夹的模式并在更高层次上发挥回收站的作用。     

邯钢10#转炉煤气回收系统的自动化控制

本文主要介绍邯钢三炼钢厂10#转炉煤气回收系统的自动化控制,结合生产应用,对回收过程中所发生的各种问题进行了优化。     

坪北油田伴生气的回收利用

坪北油田开发初期,富余伴生气直接放空燃烧,既浪费能源,又污染环境。要解决这个问题可以三个方面入手:一是建设集气管网,增压回收套管气;二是完善配套工艺,回收更多伴生气;三是研发节能设备,减少伴气损耗。同时要应利用富余伴生气发电,提高能源利用率,降低电力成本。     

有机溶剂分离法处理废旧锂离子电池

针对现有废旧锂电池回收钴金属工艺中铝钴分离的问题,采用特定的有机溶剂分离法,使锂电池正极材料中的钴酸锂从铝箔上溶解下来,直接分离钴酸锂和铝箔,铝箔经清洗后直接回收,所用的有机溶剂通过蒸馏方式脱除粘结剂,实现循环使用。该工艺简化废旧锂电池正极材料的回收处理工艺流程,有效地回收钴与铝。