华中地区某县农田土壤黑碳分布特征及来源解析

以华中地区阳新县农田土壤为研究对象,采用热光反射法研究了不同类型农田土壤(水稻土、红壤、潮土)中黑碳、焦炭、烟炱含量的变化特征,并探讨了影响黑碳、焦炭和烟炱分布的影响因素以及黑碳的可能来源。结果表明,农田土壤中黑碳、焦炭和烟炱含量变幅较大,分别为0.17—3.18 g?kg~(~(-1)),0.03—2.37 g?kg~(-1)和0.09—1.50 g?kg~(-1),平均值分别为0.85 g?kg~(-1),0.45 g?kg~(-1)和0.40 g?kg~(-1)。不同类型土壤中黑碳、焦炭、烟炱含量的大小顺序是:水稻土红壤潮土。黑碳占有机碳的比例变化范围在1.45%—26.43%,平均值为6.76%。相关分析结果表明土壤黑碳含量与有机碳、焦炭和烟炱含量之间都呈显著的正相关关系。根据焦炭/烟炱比值分析结果推测农田土壤中的黑碳主要来源于化石燃料燃烧,如工业燃煤及机动车尾气排放等。     

饮食业油烟废气污染净化技术分析研究

随着国民经济的发展和人民生活水平的提高,人们对食物烹制要求越来越高.相应地,饮食业的蓬勃发展带来饮食业油烟产生量在逐渐增多,对室内、外大气环境有重要影响.饮食业油烟气对大气环境影响日益加重,对人体健康和环境危害被广泛关注.文章分析了饮食业油烟气污染形成、组成及危害,介绍了机械式净化技术、静电式、液体洗涤式、织物过滤式等油烟气净化技术的工作原理、优缺点及性能比较,并对今后的油烟净化技术的发展趋势进行了展望.     

铈锆固溶体负载LaCoO3催化碳烟的性能和表征

用柠檬酸法制备了铈锆固溶体负载不同量LaCoO3的催化剂。用热重法测试了催化剂样品对碳烟的催化活性。采用程序升温还原法（H2-TPR）、BET、X-射线衍射仪（XRD）和X-射线光电子能谱仪（XPS）对催化剂进行了测试。结果表明,铈锆固溶体表面形成了稳定的LaCoO3钙钛矿相结构;负载量为30%LaCoO3的催化剂具有最高的催化活性,起燃温度降到530℃;催化剂的催化活性与催化剂还原峰强度以及催化剂表面氧物种OII的含量紧密相关。     

餐饮业油烟排放监测模拟工况研究

在现行《饮食业油烟排放标准(试行)》(GB18483—2001)的执行过程中,工况难以控制,影响监测结果的准确性。在对不同餐饮业的主要烹饪方式(炸、煎、煮、炒)餐饮油烟的初始排放浓度进行实测的基础上,模拟出和以上4种烹饪方式相匹配的工况,分析各种类型餐饮业不同工况下的油烟排放规律,建立了一组能够由监测人员主动控制的油烟监测模拟工况。     

无人机技术在锅炉内部检验中的应用

传统锅炉内部检验方法有着工作周期长、经济效益差、危险性高的局限性,而无人机检验具有成本低、反应灵活、空间适用性强等优势,本文旨在通过将无人机应用于电站锅炉及垃圾焚烧锅炉内部检验的应用实例,根据无人机本身特性及锅炉内部结构特点,确定无人机检验方案,完善无人机检验方法,并指出目前在锅炉内部进行无人机检验时存在的问题以及改进...     

锅炉空预器堵灰的原因分析及处理措施

介绍了某电厂空预器的设计特点,该空预器运行过程中出现了一、二次风压与炉膛压力周期性波动、进出口差压偏大的问题.对该空预器实际运行情况的分析研究表明：燃用煤种含硫量超标、吹灰蒸汽带水、冬天暖风器投用不及时以及蓄热元件布置紧密是造成空预器堵灰的关键问题.通过控制入炉煤含硫量、加强吹灰、提高综合冷端温度和蓄热元件改造等措施,保证了空预器安全经济运行.     

Effects of fuel reactivity and injection timing on diesel engine combustion and emissions

Recent strategies for simultaneously reducing NOx and soot emissions have focused on achieving nearly premixed, low-temperature combustion (LTC) in diesel engines. A promising approach in this regard is to vary fuel reactivity in order to control the ignition delay and optimize the level of premixing and reduce emissions. The present study examines such a strategy by performing 3-D simulations in a single-cylinder of a diesel engine. Simulations employ the state-of-the-art two-phase models and a validated semi-detailed reaction mechanism. The fuel reactivity is varied by using a blend of n-heptane and iso-octane, which represent surrogates for gasoline and diesel fuels, respectively. Results indicate that the fuel reactivity strongly influences ignition delay and combustion phasing, whereas the start of injection (SOI) affects combustion phasing. As fuel reactivity is reduced, the ignition delay is increased and the combustion phasing is retarded. The longer ignition delay provides additional time for mixing, and reduces equivalence ratio stratification. Consequently, the premixed combustion is enhanced relative to diffusion combustion, and thus the soot emission is reduced. NO_x emission is also reduced due to reduced diffusion combustion and lower peak temperatures caused by delayed combustion phasing. An operability range is observed in terms of fuel reactivity and SOI, beyond which the mixture may not be sufficiently well mixed, or compression ignited. The study demonstrates the possibility of finding an optimum range of fuel reactivity, SOI, and EGR for significantly reducing engine out emissions for a given load and speed.     

Numerical simulation of DPF thermal regeneration process based on an improved dynamic model

ABSTRACT

In this paper, an improved kinetics model of soot oxidation based on the traditional B-K model is employed to characterize the thermal regeneration process of diesel particulate filters (DPF). Considering the influence of specific surface area and inhibition factor on soot oxidation, the regeneration process is simulated and analyzed using the commercial FLUENT software combined with UDF method. The results show that soot particles react from the middle of the filter to both ends, and the temporal profile of soot mass in the thermal regeneration process could be divided into three sections: smooth reaction, rapid reaction, and late reaction. The regeneration time decreases with the increasing of the incoming oxygen volume fraction. When the thickness of the deposited soot layer is less than 0.1 mm, the regeneration time is prolonged as the thickness of the deposited layer decreases. When the thickness is more than 0.1 mm, the regeneration time shows the opposite trend with the thickness of the deposited layer. Meanwhile, the curve of maximum wall temperature changing with time is divided into heating, rapid-burning, and slow-burning regimes. The maximum wall temperature increases as the volume fraction of oxygen flow increases, and as the deposited layer thickness increases.     

锅炉烟尘监测过程质量控制及现场采样应注意的问题

以生态文明全面取代工业文明,是实现人类生存进步及经济可持续发展的唯一途径。以我国为例,在经历40年社会改革开放、经济高速增长之后,工业化、城市化、现代化所取得巨大成就的背后,是生态环境的严重破坏,尤其近年来"雾霾"成为生态环境治理中最为顽固的诟病。锅炉烟尘是造成雾霾现象的"主要元凶",从环境监测角度出发,加强锅炉烟尘监测过程及现场采样质量控制,精准地获取相关数据,能够为环境治理方案提供科学依据。但同时,锅炉烟尘监测及采样是十分复杂且具有系统性的工作,在整个过程中需要加强质量控制。本文列举相关注意问题,以供技术人员在操作中参考借鉴。     

柴油车尾气碳烟颗粒物催化燃烧催化剂的最新研究进展

柴油车尾气排放的碳烟颗粒已经引起了严重的环境污染问题,必须加以净化处理.柴油车碳烟颗粒的低温燃烧离不开高活性的催化剂.针对柴油车排放的碳烟颗粒物后处理方法中的催化氧化技术,总结了近年来几种主要类型的碳烟燃烧催化剂(贵金属催化剂、碱金属催化剂、单组分过渡金属氧化物催化剂、多组分混合氧化物催化剂和固定结构复合氧化物催化剂)的最新研究进展,并对该研究方向存在的主要问题和应用前景进行了探讨.