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Carcinogenic and mutagenic polycyclic aromatic hydrocarbons (PAHs) generated in coal combustion have caused great environmental health concern. Seventeen PAHs (16 high priority PAHs recommended by USEPA plus Benzo[e]pyrene) present in five raw bituminous coals and released during bituminous coal combustion were studied. The effects of combustion temperature, gas atmosphere, and chlorine content of raw coal on PAHs formation were investigated. Two additives (copper and cupric oxide) were added when the coal was burned. The results indicated that significant quantities of PAHs were produced from incomplete combustion of coal pyrolysis products at high temperature, and that temperature is an important causative factor of PAHs formation. PAHs concentrations decrease with the increase of chlorine content in oxygen or in nitrogen atmosphere. Copper and cupric oxide additives can promote PAHs formation (especially the multi-ring PAHs) during coal combustion. 相似文献
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An improved mathematical model for a circulating fluidized bed (CFB) boiler based on the model developed earlier by the authors was applied to simulate the operation of a 12 MW CFB boiler. The influences of the excess air ratio, primary air ratio, coal particle size distribution, coal properties (ash content and volatile content) and Ca/S ratio on the boiler operation were analyzed. The results showed that the model simulation may be applied to the optimum design and economic operation of the CFB boiler. 相似文献
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Development of an evaporation crystallizer for desalination of alkaline organic wastewater before incineration 总被引：2，自引：0，他引：2
A wastewater evaporation-desalination pretreatment method was introduced to remove the Na^＋ and K^＋ salts in volatile organic compounds （VOCs） wastewater before it was fed into the incinerator. VOCs in the wastewater were volatilized in the evaporation system and then the vapor was combusted in an incinerator. Simulated phenol wastewater containing sodium chloride was evaporated and concentrated and sodium chloride was crystallized in different parameters. The experimental results showed that the higher initial concentration of sodium chloride increases the ratio of volatilization of VOCs, which was due to the effect of “salting out” （a decrease in the solubility of the nonelectrolyte in the solution, or more rigorously, an increase in its activity coefficient, caused by the salt addition （Furter and Cook, 1967））. When evaporation speed was increased from 1.67 ml/min to 2.73 ml/min, the total removal coefficient of sodium chloride was about 99.88%-99.99%. This pretreatment procedure eliminates the slag phenomenon caused by Na^＋ and K^＋ salts during wastewater incineration, so the incinerator could operate continuously, and the wastewater evaporation could increase the heat value of wastewater, and the operation cost would be reduced. 相似文献
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城市生活垃圾气化处理技术 总被引：1，自引：0，他引：1
城市生活垃圾的气化是一种新型的垃圾处理技术,它具有高效的能源利用率和良好的环保特性,并且气化和熔融技术相结合以其严格的污染控制、显著的减容性和高效的资源回收率等优点被认为是城市生活垃圾焚烧处理最具有潜力的替代技术.本文综述了城市生活垃圾气化处理技术的原理、工艺流程及其国内外发展现状.列举讨论了固定床、气流床、流化床和回转窑等主要垃圾气化反应器的特点,并对影响垃圾气化的重要因素进行了分析.此外本文对废物衍生燃料(RDF)的气化以及垃圾气化熔融处理技术也作了介绍. 相似文献
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在自行设计的流化床实验台上进行废纸热解实验研究.当热解温度从400℃升高到700℃时,固体残渣产率从36%降低到18%,而热解油、热解气产率分别从19%增加到30%和9%增加到42%.实验的质量平衡达到80%～95%.各温度下,液体产物特性相似,热值都为10 MJ/kg左右,说明在此温度范围内,热解反应机理相似.当反应温度从500℃提高到600℃以上时,热解气产量几乎提高一倍,其中CO2与CO产量分别从大约70L/kg提高到230L/kg和50L/kg提高到l06L/kg;而温度从600℃提高到700℃时,热解气产量仅提高5%.研究表明,热解油的二次裂解会影响热解气产量. 相似文献
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Carcinogenic and mutagenic polycyclic aromatic hydrocarbons (PAHs) generated in coal combustion have caused great environmental health concern. Seventeen PAHs (16 high priority PAHs recommended by USEPA plus Benzo[e]pyrene) present in five raw bituminous coals and released during bituminous coal combustion were studied. The effects of combustion temperature, gas atmosphere, and chlorine content of raw coal on PAHs formation were investigated. Two additives (copper and cupric oxide) were added when the coal was burned. The results indicated that significant quantities of PAHs were produced from incomplete combustion of coal pyrolysis products at high temperature, and that temperature is an important causative factor of PAHs formation. PAHs concentrations decrease with the increase of chlorine content in oxygen or in nitrogen atmosphere. Copper and cupric oxide additives can promote PAHs formation (especially the multi-ring PAHs) during coal combustion. 相似文献
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工程教育改革既要注重创新,也要善于继承与借鉴 总被引：1，自引：0，他引：1
倪明江 《高等工程教育研究》1997,(4)
最近一个美国教授的专栏文章提到制度化（Institutionalization）问题。他认为，“我们似乎知道需要改变什么，似乎能够开展实验和试验研究来确定什么是有效的，但我们似乎不知道怎样实施——怎样将现行工程教育模式转变成希望的模式。或许我们应当把重点从开发新的工程教育模式转移到评估我们已知的模式上来，并将其制度化，同时促进学术文化观念的变革，这是为支持系统性工程教育改革所必需的。”将工程教育计划的重大改革制度化，至少提出了两大挑战：一是如何使改革到位，不仅仅停留在口头上或纸上，也不仅仅局限于某个点或某个方面；… 相似文献
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Heat transfer between gas-solid multiphase flow and tubes occurs in many industry processes, such as circulating fluidized
bed process, pneumatic conveying process, chemical process, drying process, etc. This paper focuses on the influence of the
presence of particles on the heat transfer between a tube and gas-solid suspension. The presence of particles causes positive
enhancement of heat transfer in the case of high solid loading ratio, but heat transfer reduction has been found for in the
case of very low solid loading ratio (M
s of less than 0.05 kg/kg). A useful correlation incorporating solid loading ratio, particle size and flow Reynolds number
was derived from experimental data. In addition, thek-∈ two-equation model and the Fluctuation-Spectrum-Random-Trajectory Model (FSRT Model) are used to simulate the flow field
and heat transfer of the gasphase and the solid-phase, respectively. Through coupling of the two phases the model can predict
the local and total heat transfer characteristics of tube in gas-solid cross flow. For the total heat transfer enhancement
due to particles loading the model predictions agreed well with experimental data.
Project supported by National Natural Science Foundation for Distinguished Young Scholars (No. 50025618) 相似文献
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洗选煤泥是从选煤厂排出的浆状物料。由于它水份大,灰份高,热值低,持水性强,要加以利用非常困难,因此难以销售,大量堆积。这不仅严重的影响环境卫生,而且还造成大量能源损失。在当前原煤入洗率仅为18％的情况下,每年约排放600万吨煤泥,相当于200万吨原煤。为此国家科委和煤炭部与浙江大学,煤科院煤化所,永荣矿务局电厂签订了一项利用选煤厂洗选煤泥的攻关合同。沸腾燃烧洗选煤泥的研究工作是在浙江大学燃烧实验室进行,在取得了充分的基础数据及设计依据之后在永荣矿务局电厂进行了10吨/时洗选煤泥沸腾锅炉的中间试验,并于1986年2月通过国家鉴定。 相似文献
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