Combustion and decomposition of VOCs from shell moulds by regenerative thermal oxidiser

Abstract

In the present work, the regenerative thermal oxidiser (RTO) with preheating and baking system was applied to treating volatile organic compounds (VOCs) discharged from the shell mould casting. As a result, it was found that the tar characterised by more than 523 K of high boiling point was formed by the shell mould casting. The Fourier transform infrared spectrometry analysis showed that the tar was composed of paraffin, zinc stearate and quartz. A part of the tar was deposited on the ceramic honeycombs in the heat exchanger. However, the tar can be almost completely removed by means of baking treatment at 623 K in the RTO. Regarding the decomposition of VOCs, it was found that the concentrations of all VOCs were reduced to less than 1 ppm. Further, 98% of offensive odour was removed by the treatment. Thus, it can be concluded that the RTO is suitable for decreasing VOCs from the shell mould casting in the foundry.     

室内装修烘烤气体的生物强化技术

为了减轻由室内装修所造成的污染,通过生物滴滤处理装置处理室内装修烘烤后排出的挥发性有机气体(甲醛、苯、甲苯、二甲苯).在气体流量为600 L/h、表面液体速度为3.14~3.93 m/h,pH为6~7,进气温度为30℃条件下采用生物强化技术,当入口甲醛浓度小于30.86 mg/m3,生物滴滤塔对甲醛净化效率一直保持100%;当入口苯浓度在2.07~43.22 mg/m3,生物滴滤塔对苯的净化效率是86.2%~88.4%;当入口甲苯浓度在0.76~31.61 mg/m3,生物滴滤塔对甲苯净化效率是93.2%~94%;当入口二甲苯浓度在3~55.20 mg/m3,生物滴滤塔对二甲苯净化效率是90%~91.6%.从《大气污染物综合排放标准(GB16297-1996)》的指标考察,室内装修烘烤污染物经生物滴滤处理后均可达到现有污染源和新污染源排放标准,生物强化处理是可行的.     

Enhancement of VOCs removal using a novel double-tube packed bed catalytic dielectric barrier discharge (DPDBD) reactor

We developed a novel double-tube packed bed catalytic dielectric barrier discharge (DPDBD) reactor to degrade toluene. The DPDBD reactor contains four discharge cells with one power supply, namely, A–D. NiO/γ-Al₂O₃ is packed in cell A to effectively destroy the branched chains in toluene. TiO₂/γ-Al₂O₃ is packed in cell B owing to its high catalytic oxidation activity to weaken the benzene rings and mineralize the generated partial aromatic compounds. Cell C is a pure DBD process without any catalyst packed to thoroughly mineralize all the generated aromatic compounds and convert CO into CO₂ and NO into NO₂. γ-Al₂O₃ is packed in cell D to reduce the concentrations of byproducts, including O₃ and NO generated by air through oxidation. The combinations of the four discharge cells are optimized by the treatment of −3000 mg m⁻³ of toluene at 11 kV. In comparison with a double-tube dielectric barrier discharge (DDBD) reactor without catalyst packing and with a total discharge length of 6 cm, the selectivity of CO₂ was significantly improved from 45% to 57% when the discharge lengths of A, B, C, and D are 2, 4, 4, and 2 cm, respectively. Furthermore, the concentrations of O₃ and NO in the outlet can also be effectively reduced from 2.80 and 210 mg m⁻³ to 1.30 and 60 mg m⁻³, respectively. We also investigated the effects of applied voltage and styrene initial concentration.     

纺织品甲醛污染及空间除醛技术

甲醛作为严重危害生命安全的常见有毒致癌物质已受到人们的高度重视。目前国内外对甲醛的研究主要集中在医学和居室空气质量控制范畴,对纺织品甲醛感染系统性研究的报道还不多见。研究产业用纺织品、装饰用纺织品和仓存空间的甲醛污染问题,介绍三大纺织品产生甲醛超标的根源、释放特点和治理措施等,同时分析空间甲醛污染的可能性和研究进展。     

纳米微胶囊相变材料杀菌及降解VOCs的性能试验

在自制了纳米微胶囊相变材料的基础上,进行了纳米微胶囊相变材料的杀菌、降解VOCs等性能试验,展望了此材料对提高室内空气品质的应用前景。试验分析表明:纳米微胶囊相变过滤材料具有强劲的杀菌效果,降解VOCs的能力显著,但微胶囊相变材料浓度在60g/L～120g/L为宜。     

溶剂蒸馏气相色谱-质谱法研究菜籽油挥发性成分

溶剂蒸馏气相色谱-质谱法是一种有效的检测挥发性物质的研究方法,在本研究中对菜籽油中挥发性成分进行分析：将菜籽油和乙酸乙酯（V／V=2：1）混合溶解后蒸馏出溶剂,同时将蒸馏出来的挥发性组分进行富集,然后加热并用N2吹扫蒸馏液浓缩得到待测液,最后用GC／MS分析检测待测液成分。结果检测到挥发性成分46种,通过NIST 2006标准谱库检索、Wiley数据库和文献比较确定挥发性成分28种,分别是酮类、醛类、烷烃类、烯烃类以及其他少量化合物。     

Development of a test method using a VOC analyzer to measure VOC emission from adhesives for building materials

A volatile organic compound (VOC) analyzer is a portable device to measure the four main aromatic hydrocarbon gases: toluene, ethylbenzene, xylene and styrene. With the VOC analyzer, a semiconductor gas sensor eliminates the need for the carrier gas which is required for conventional gas chromatography. In addition, since the semiconductor gas sensor is supersensitive to gas components, it is not necessary to use a conventional gas concentrator or other complicated equipment. Compared with other measurement methods, the VOC analyzer is useful for measuring toluene, ethylbenzene, xylene and styrene in new buildings because of its ease in obtaining field results and repeating the test. For easy, fast and economic testing of total (TVOC) emission from adhesives used for building materials, we developed a test method using the VOC analyzer and compared its measurement of VOC emissions from building materials such as adhesives, paints and wood-based panels with that of the 20-l chamber method, which is the standardized test method in Korea. There was a good correlation between the TVOC emission concentrations determined by the VOC analyzer and the TVOC emission factor (EF) by the 20-l chamber. Based on this good correlation, the VOC analyzer is expected to gain widespread use in the manufacturing field application where a quick and easy test for VOC emission from adhesives for building materials is required. Furthermore, the VOC analyzer offers the potential to become an easier, faster and more economical technique than the currently used standard methods.     

涂层设备混合溶剂废气排放的处理

介绍了某公司涂布废气处理项目的方案确定过程,及设备在运行过程中活性碳着火问题的处理措施.整套废气处理工艺设备既保证达到国家环保局的废气排放标准,又取得了相应的经济效益.     

基于RBF神经网络的流向变换催化燃烧反应器床层温度分布的动态模型

清除工业废气中低浓度挥发性有机物(VOCs)的流向变换催化燃烧反应器的床层温度依时变化，为了实现实时预测和控制，用动态RBF(Radial Basis Function)神经网络建立了反应器床层瞬态温度分布的预测模型。着重讨论了动态RBF神经网络的基本结构，依据RBF网络线性输出的特点，给出了预测模型参数的在线修正方法。仿真结果与中试装置现场数据的对照表明，所建立的模型简单、精度高，能满足控制要求。     

VOC_S在线气相色谱自动监测技术及相关仪器简介

VOCS是环境空气中非常重要的污染物之一,它不但对人体危害极大,还能参与光化烟雾污染反应,对VOCS进行长期在线观测是环境管理和科学研究的要求。本文以荷兰SYNSPEC生产的GC955系列在线气相色谱仪为例,介绍在线气相色谱方法及GC955系列监测设备的工作原理、仪器构造以及校准方法和日常维护等内容。