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排序方式: 共有9338条查询结果,搜索用时 9 毫秒
51.
污泥中总磷测定方法的探讨 总被引:1,自引:0,他引:1
污泥样品与氢氧化钠熔融,使污泥中含磷有机化合物全部转化为可溶性的正磷酸盐,然后测定污泥中的总磷含量.此方法方便易行,平行性好,准确度高,可作为测定污泥中总磷的标准方法. 相似文献
52.
催化剂烧炭再生是非定态过程。本文建立了绝热反应器内催化剂烧炭模型,利用移动边界正交配置法求解。以结炭的BO2催化剂再生为工作反应,模拟预测与实验值吻合良好。模拟计算表明,用递升进口温度序列烧炭,使再生时间明显缩短。 相似文献
53.
Hyun-Seob?Song Joo?Sung?Lee Jae?Chun?HyunEmail author 《Korean Journal of Chemical Engineering》2002,19(6):949-953
A mathematical model for the pyrolysis reaction of polystyrene (PS) in a semi-batch reactor has been presented. The thermal
degradation of PS was flexibly modeled by a combination of random and specific chain-end scissions. Numerical simulation was
used to investigate the effect of operating conditions on the PS products spectrum, the results of which were validated by
the experimental data. It was found that as the reaction temperature increased (decreased), the monomer fraction in the products
became lower (higher) while the trimer higher (lower). No significant variation in the product composition was, however, observed
while constant temperature was maintained. These results indicate the reaction temperature is an effective manipulated variable
for the control of products composition of PS pyrolysis. The calculation of the optimum temperature trajectories through the
optimization study can thus be of interest for achieving productivity enhancement in plastics pyrolysis processes.
This paper is dedicated to Professor Dong Sup Doh on the occasion of his retirement from Korea University. 相似文献
54.
Pt-V2O5-WO3/TiO2 catalysts supported on SiC filter for NO reduction at low temperature 总被引:1,自引:0,他引:1
Joo-Hong Choi Jin-Hyun Kim Young-Cheoul Bak Rose Amal Jason Scott 《Korean Journal of Chemical Engineering》2005,22(6):844-851
The catalytic filter, V2O5-WO3-TiO2 supported on a ceramic filter, is known as a promising material for treating particulates and NO
x
simultaneously at optimum temperatures around 320°C. In order to improve its catalytic activity at low temperatures, the
effect of Pt addition on the catalytic filter has been investigated. Catalytic filters, Pt-V2O5-WO3-TiO2/SiC, were prepared by co-impregnation of Pt, V, and W precursors on TiO2 coated-SiC filter by vacuum aided-dip coating. The Pt-added catalytic filter shifted the optimum working temperature from
280–330°C (for the non Pt-impregnated filter) to 180–230°C, providing N
x
slip concentration less than 20 ppm for the treatment of 700 ppm NO at a face velocity of 2 cm/s with the same value over
the non Pt-added catalytic filters. The promotional effect following the addition of Pt is believed to result from electrical
modification of the catalyst maintaining a high electron transfer state. Ammonia oxidation was also observed to be dominant
above the optimal temperature for SCR. 相似文献
55.
56.
57.
选取BT6组成点,采用不同的预合成温度、烧结温度和保温时间制备样品,研究各样品的体积密度、线收缩率、晶粒发育状况和压电性能,确定最佳的烧成工艺制度。 相似文献
58.
59.
Preparation and characterization of multi-walled carbon nanotubes supported PtRu catalysts for proton exchange membrane fuel cells 总被引:1,自引:0,他引:1
A series of PtRu nanocomposites supported on H2O2-oxidized multi-walled carbon nanotubes (MWCNTs) were synthesized via two chemical reduction methods—one used aqueous formaldehyde (HCHO method) and the other used ethylene glycol (EG method) as the reducing agents. The effects of the solvents (water and ethylene glycol) and the surface composition of the MWCNTs on the deposition and the dispersion of the metal particles were investigated using N2 adsorption, TEM, ICP-AES, FTIR and TPD. The wetting heats of the MWCNTs in corresponding solvents were also measured. The characterizations suggest that combination of the surface chemistry of the MWCNTs with the solvents decides the deposition and the dispersion of the metal nanoparticles. These nanocomposites were evaluated as proton exchange membrane fuel cell anode catalysts for oxidation of 50 ppm CO contaminated hydrogen and compared with a commercial PtRu/C catalyst. The data reveal superior performances for the nanocomposites prepared by the EG method to those by the HCHO method and even to that for the commercial analogue. Structure–performance relationship of the nanocomposites was also studied. 相似文献
60.
浸入式水口燃烧式烘烤预热温度场研究 总被引:4,自引:2,他引:4
浸入式水口在浇钢以前必须进行充分预热 ,利用燃烧的煤气烘烤水口是常用的预热烘烤方式。本工作运用有限元技术对浸入式水口燃烧式烘烤预热的瞬态传热过程进行了研究 ,得到了水口烘烤预热后的温度场分布和水口的升温曲线。研究结果表明 ,在燃烧式预热烘烤方式下 ,水口沿轴线方向的温度变化梯度较大 ,水口颈部预热后的温度较低 ,是导致水口颈部频繁断裂和较易出现竹节样裂纹的主要原因。欲提高水口颈部的预热温度 ,必须改进水口的预热烘烤方式 相似文献