Growth kinetics of CaF2 in a pH-stat fluidized-bed crystallizer

In this study, experiments were first conducted in a stirred vessel to establish the metastable region of calcium fluoride, using a pH-stat apparatus for controlling the pH value of solution. The effects of pH value on the solubility and metastable region were observed. Then, operating variables, including supersaturation, superficial velocity, pH value, seed size, and types of seed and solution, that influenced the crystal growth of the same system were investigated in a fluidized-bed crystallizer. The crystal growth rates were determined from the consumption rates of fluoride ions. The growth kinetics was explored by using the two-step growth model. The effectiveness factor was used to judge whether a controlling step was existing. The kinetics of crystal growth in a lean bed and a dense bed was also discussed.     

不同放大级Fe/Cu/K/SiO2催化剂的表征及其浆态床费托合成反应性能

采用连续共沉淀和喷雾干燥成型相结合的方法,制备了实验室级和放大级微球状费托(FT)合成Fe/Cu/K/SiO2催化剂.实验室级催化剂的颗粒尺寸为5～15μm,放大级催化剂的颗粒尺寸为40～60μm.利用低温N2物理吸附、H2程序升温还原、CO2程序升温脱附、穆斯堡尔谱和X射线衍射等表征手段考察了催化剂的织构性质、还原行为、碳化行为及物相变化.结果表明,与实验室级催化剂相比,放大级催化剂具有较大的晶粒尺寸和孔径、较小的比表面积和较弱的表面碱性,催化剂的还原和碳化受到抑制.浆态床FT合成反应及扫描电子显微镜结果表明,放大级催化剂经诱导期达到稳定状态后,转化率可达到实验室级催化剂的水平,且具有很高的稳定性、重质烃选择性及抗磨损性.     

Oxidative coupling of methane in a fixed bed reactor over perovskite catalyst： A simulation study using experimental kinetic model

The oxidative coupling of methane （OCM） to ethylene over a perovskite titanate catalyst in a fixed bed reactor was studied experimentally and numerically. The two-dimensional steady state model accounted for separate energy equations for the gas and solid phases coupled with an experimental kinetic model. A lumped kinetic model containing four main species CH4, O2, COx （CO2, CO）, and C2 （C2H4 and C2H6） was used with a plug flow reactor model as well. The results from the model agreed with the experimental data. The model was used to analyze the influence of temperature and feed gas composition on the conversion and selectivity of the reactor performance. The analytical results indicate that the conversion decreases, whereas, C2 selectivity increases by increasing gas hourly space velocity （GHSV） and the methane conversion also decreases by increasing the methane to oxygen ratio.     

CATALYTIC WET PEROXIDE OXIDATION OF HYDROQUINONE WITH Co（II）/ACTIVE CARBON CATALYST LOADED IN STATIC BED

Catalysts based on Co（II） supported on active carbon were prepared and loaded in static bed. The hydroquinone would be degraded completely after treated by Catalytic wet peroxide oxidation method with Co（II）/active carbon catalyst. After activate treatment, the active carbon was immerged in cobaltous nitrate solution, then put into a drying oven, Co（II） could be loaded on the micro-surface of carbon. Taking the static bed as the equipment, the absorption of active carbon and catalysis of Co（II） was used to reduce activation energy of hydroquinone. Thus hydroquinone could be drastically degraded and the effluent can be drained under the standard. Referring to Fenton reaction mechanism, experiment had been done to study the heterogeneous catalyzed oxidation mechanism of Co（II）. The degradation rate of hydroquinone effluent could be achieved to 92% when treated in four columns at H2O2 concentration 10%, reaction temperature 40 ℃, pH 5 and reaction time 2.5h.     

准东煤流化床气化飞灰的理化特性研究

采用灰熔点测定仪、X射线荧光光谱仪、扫描电镜和热重分析仪等方法,研究了准东煤流化床气化飞灰的灰熔融特性、物理结构和化学组成及气化反应活性。结果表明,准东煤与其流化床气化飞灰中Si O2、Fe2O3、Na2O和Ca O等矿物质含量存在显著的差异,但飞灰的灰熔点与原煤无明显差异。准东煤气化飞灰具有较宽的粒径范围,呈现双峰分布特征,且不同粒径区间飞灰的元素含量存在显著差异。提高气化温度,有利于提高飞灰的气化反应活性。准东煤流化床气化飞灰石墨化程度比煤焦要高,但其孔隙结构更为发达,含有丰富的中孔和中大孔,使得飞灰的气化反应活性高于煤焦。可通过提高气化温度、循环再气化的方法提高气化效率。     

Simultaneous Continuous Removal of Cr(VI) and Phenol from Binary Synthetic Simulated Waste Water in Tea Waste Packed Bed Column: Kinetic Modeling

In this study, simultaneous co-adsorption of Cr(VI) and phenol was carried out in a continuous packed-bed reactor packed with tea waste biomass. The experiments were carried out using binary synthetic simulated solution containing 100 mg/L of Cr(VI) and 50 mg/L of phenol. The binary synthetic solution was passed through the packed-bed reactor at different flow rates (5.46, 8.19, and 16.3 mL/min) and bed height (36, 54, 72, and 93 cm). The pH of the binary synthetic solution was 5 as the maximum simultaneous percentage removal of Cr(VI) and phenol was obtained at this pH reported in our previous study.^[1 Gupta, A. and Balomajumder, C. (2015) J. Water Proc. Eng., 6: 1–10.[Crossref] , [Google Scholar]^] The effects of flow rate and bed depth onto the simultaneous percentage removal of Cr(VI) and phenol were investigated. According to the average percentage error (?%) and average relative error (ARE %) calculated for various kinetic models reveal that Yoon–Nelson model for Cr(VI) and Thomas model for phenol best describes the experimental data. The maximum adsorption capacity of tea waste biomass in a packed-bed reactor for Cr(VI) and phenol was 57.04 and 27.96 mg/g, respectively. The packed bed of the column was regenerated using 2 N NaOH.     

Comparative genomics for understanding the structure,function and sub-cellular localization of hypothetical proteins in Thermanerovibrio acidaminovorans DSM 6589 (tai)

The Thermanerovibrio acidaminovorans DSM 6589 (tai) is a unique bacterium isolated from anaerobic sludge bed reactor from sugar refinery in Netherland. The comparative genomic studies for understanding the hypothetical proteins in T. acidaminovorans DSM 6589 (tai) were carried out using different bioinformatic tools and web servers. In all 320 hypothetical proteins were screened from the total available genome. The Insilico function prediction for 320 hypothetical proteins was achieved by using different online servers like CDD-Blast, Interproscan and pfam whereas, the structure prediction for 202 hypothetical proteins were deciphered by using protein structure prediction server (PS2 server). The sub-cellular localization for the identified proteins was predicted by the use of cello v2.5 for 320. The study carried out has helped us to understand the structures and functions of unknown proteins available in T. acidaminovorans DSM 6589 (tai) through comparative genomic approach.     

The Flow Patterns and Wall Stresses in a Louvered‐Wall Moving Granular Filter Bed of Quartz Sand

The flow patterns and wall stresses in a two‐dimensional louvered moving granular filter bed of quartz sand were investigated. The flow pattern histories of granular solids in the filter bed were recorded using a digital camcorder and a pressure gauge for simultaneously measuring the normal stresses as well as shear stresses of the granular solids. The static wall stress distributions produced by the granular solids were measured, and agreed with a theoretical prediction formed using the differential slice and Runge‐Kutta (order four) methods. The variations in the dynamic wall stresses with time in a moving granular filter bed were obtained and the effect of the louver angle upon the flow patterns and wall stresses was also investigated. Employing the results obtained by stress measurements and image processing, the wall pressure pulsation phenomena in a moving granular filter bed may be further understood. The results reported here provide fundamental information for the design of moving granular filter beds to act as high‐temperature flue gas cleanup filters.     

造纸污泥与废水污泥流化床焚烧时NO_x和SO_2的排放特性研究

1前言流化床焚烧污犯是近年来发达国家广泛采用的方法，它能很好地实现污泥的稳定化、无害化、减容化和资源化处理。燃煤流化床锅炉污染物排放方面已做了大量的研究工作，由于污泥与煤在结构和性质方面的差异较大，因此有必要对流化床焚烧污泥时污染物排放特性进行研究。本文详细研究了造纸、废水污泥在流化床中焚烧时污泥水份、运行床温及过量空气对NO。和SO。的排放特性及污泥N－＋NO。、S－SO。的转化率的影响，并对这两种性质差异较大的污泥焚烧时的NO。和502的生成特性进行了对比分析，取得了许多有价值的结果，为污泥流化床焚烧…     

物料在多层流化床内非稳态干燥的实验研究

通过石英砂与绿豆在多层流化床内的非稳态干燥特性实验，得出与稳态干燥的重要区别即为没有稳定的值速干燥段。将Page方程修正后，可用于多层流化床非稳态干燥数据处理。推导出的非稳态干燥动力学方程证明在非稳态干燥时，不可能出现恒速干燥段，并表明变工况与快速高强度干燥是提高干燥速率的重要途径。