蒙古国巴嘎诺尔(Baganuur)褐煤水蒸气气化制富氢合成气及其固有矿物质的催化作用

利用固定床气化-色谱联用装置,考察了蒙古国巴嘎诺尔(Baganuur)褐煤的水蒸气气化反应性能,研究对比了巴嘎诺尔褐煤原煤BN-R、盐酸洗煤BN-HCl、氨水洗煤BN-NH₄OH、先酸洗后碱处理煤BN-HCl-NaOH及原煤和盐酸洗煤热解预处理煤样BN-R-Char与BN-HCl-Char在水蒸气气化过程中气态产物H₂、CO和CO₂的生成规律.研究结果表明,上述煤样的水蒸气气化过程中H₂、CO和CO₂的生成速率存在明显差异,与盐酸洗煤样相比,BN-R、BN-HCl-NaOH及BN-R-Char比对应矿物质脱除煤样的水蒸气气化速率高,充分说明巴嘎诺尔褐煤中某些固有矿物质对其水蒸气气化反应具有显著的催化作用,显著提高了其气化反应速率,使起始气化温度和气化反应主体温度均降低100 ℃以上,在提高H₂和CO₂生成量同时,还降低了CO生成量,制得了高H₂/CO(物质的量比)的合成气.用盐酸脱除矿物质所得BN-HCl同BN-HCl-Char的水蒸气气化性能相似.与BN-R相比,BN-HCl与BN-HCl-Char水蒸气气化反应性明显下降,说明对巴嘎诺尔褐煤水蒸气气化起催化作用的矿物质成分在盐酸洗脱的矿物质中.经过分析,发现矿物质对巴嘎诺尔褐煤水蒸气气化反应的催化作用,主要是通过提高水煤气变换反应速率实现的.最后,结合文献报道,提出了巴嘎诺尔褐煤水蒸气气化反应过程中矿物质的原位催化机理.     

Modeling of a MED-TVC desalination system by considering the effects of nanoparticles: energetic and exergetic analysis

In this study, the energetic and exergetic analysis of a multi-effect desalination system with a thermal vapor compression desalination system has been numerically evaluated. For this purpose, the mass, energy, and exergy balance equations for the thermo-compressor, first effect as well as middle effects, and condenser have been developed. The effects of motive steam pressure and number of effects on yield, gained output ratio (GOR), performance ratio (PR) and irreversibility have been examined. Nanoparticles were used to improve the heat transfer properties at different stages. The highest rate of exergy destruction with 61.67% is concerned with thermo-compressor, owing to the large difference between the motive steam pressure and the entrained steam. The lowest exergy losses rate among the various components was 4.89% for the condenser, due to the fact that much of the final distillate steam entrained the thermo-compressor. As the number of effects increased from 1 to 7, the yield, GOR as well as PR, improved by approximately 590% and the irreversibility reduced by 1.88%. As the motive steam pressure increased from 400 to 1290 kPa, the yield decreased by 25.45% while the GOR and PR improved by 12.62 and 14.8%, respectively. From the second law viewpoint, irreversibility intensified by 16.11% which in turn diminished the second efficiency by 3.17%.

     

Decay rate of critical fluctuations in steam along the critical isochore

The decay rate of critical fluctuations in steam along the critical isochore as a function of the temperature difference (T-T_c) has been measured by the techniques of photon correlation spectroscopy. They are the first results which have been obtained on steam. The experimental data agree reasonably with the predictions of the renormalisation group and mode-mode coupling theories when using the thermodynamic property values proposed by one of the authors.     

工业气化装置原料煤及残余物气化反应特性研究

考察了某工业气化装置中的原煤、滤饼及除沫器灰渣在不同温度下与水蒸气和CO₂的气化反应特性,采用扫描电子显微镜和吸附仪测试了样品的初始结构及表面特性。研究表明,采用相同气化剂进行气化反应时,原煤的气化活性要高于除沫器灰渣,而除沫器灰渣的气化活性则与滤饼相近,但略好于滤饼。这主要是由于三种样品的表面和内部结构存在很大的差异。由于水蒸气和CO₂与样品的反应机理存在差异,使得样品的水蒸气气化活性比CO₂气化活性高三倍左右。     

高温法和烘箱法测定水体中总氮的比较

分别采用烘箱法和高压蒸汽消解法对纯水和电解质溶液中的含氮有机化合物进行了消解,并用镉铜还原法测定了溶液中总氮的含量。实验表明,这两种消解方式无显著性差异,可以采用烘箱法代替压力蒸汽消毒器在电解质溶液中对含氮有机化合物进行消解,且烘箱法操作简单。     

A comparative study of the water-dimer gas-phase thermodynamics in the BJH- and MCYL-type flexible potentials

The standard thermodynamic terms for the gas-phase water-dimer formation and the steam second-virial coefficient isotopic difference have been evaluated for BJH- and MCYL-type flexible potentials (four potential mutations in each family). Generally, a reasonable agreement with available observed data has been found. The standard enthalpy, entropy, and Gibbs free energy terms are best described in the BJH/G, MCY-I, and MCY-L potentials, respectively. A set of thermodynamic characteristics based on the flexible potentials is selected for a further use.     

Isotopic difference in the second virial coefficient of water: Another test of the MCY-B description of water dimer thermodynamics

Evaluation has been carried out of the component of the second virial coefficient of steam related to the formation of dimers. The necessary equilibrium constants of dimerization have been evaluated within the MCY-B water pair interaction potential. The calculated isotopic difference in the second virial coefficient reflects the qualitative features found by observation but, nevertheless, the calculation quite distinctly overestimates the value of this isotopic difference as compared with the observation. The nature of these differences and the relation to the state behaviour of water are discussed.     

Effects of molecular weight on macropore sizes and characterization of porous hydroxyapatite ceramics fabricated using polyethylene glycol: mechanisms to generate macropores and tune their sizes

Hydroxyapatite (HAp) is a raw material used to fabricate scaffolds. Scaffolds are required to be porous to facilitate nutrient flow and vascularization. This study aims to produce porous HAp ceramics with macropores (>200 μm) and bioactivity and tune their macropore size. Polyethylene glycol (PEG) with molecular weights of 400, 3,400, and 8,300 was used to generate macropores. The macropore size increased as the molecular weight of PEG increased. In this method, emulsions were formed by hydrophobic PEG binding HAp nanoparticles during chemical syntheses. Water foams, as a core of the emulsion, were transformed into steam, and the steam expanded under heat treatment. Macropores were generated by the evaporation of the steam and consolidation of HAp nanoparticles. The difference in the molecular weight of PEG did not affect cell adhesion to the porous HAp ceramics. Cells adhered well to and spread widely on the HAp ceramics regardless of macropore size.     

Physical and chemical changes of medicinals in mixtures with adsorbents in the solid state. III. Determination of vapor pressure of solid drugs by steam distillation

The vapor pressures of solid drugs were determined by the steam distillation method. Experiments using a series of benzoic acid derivatives indicated that this method offered consistent and satisfactory values for vapor pressure at about 100 degrees C. The vapor pressures of two nonsteroidal antiinflammatory drugs, flufenamic acid (FFA) and mefenamic acid (MFA), were found to be 3.8 x 10(-3) and 1.8 x 10(-4) mmHg, respectively. These values explain the difference in the rate of change to the amorphous state between mixtures of each with magnesium aluminum silicate (MAS) when they were stored under reduced pressure. It was concluded that the vapor pressures of solid drugs at about 100 degrees C, as determined by steam distillation, may be suitable indices for predicting whether or not these drugs have an inherent propensity to become amorphous readily in mixtures with an adsorbent.     

水蒸汽对PtSn／Al2O3催化剂结构及反应性能的影响

比较研究了Ａｌ２Ｏ３负载的铂及ＰｔＳｎ催化剂在氮气及水蒸汽稀释条件下的丙烷脱氢性能,并利用ＸＰＳ及氢脉冲吸附对催化剂进行了表征。结果表明,水蒸汽可促使Ｐｔ／Ａｌ２Ｏ３催化剂的铂晶粒烧结。与在氮气氛中相比,在水蒸汽存在下反应显著提高了Ｐｔ／Ａｌ２Ｏ３的丙烷转化率,却降低了丙烯的选择性。另一方面,水蒸汽可调变ＰｔＳｎ／Ａｌ２Ｏ３催化剂的结构,破坏了ＰｔＳｎ／Ａｌ２Ｏ３中与锡相互作用的铂簇团结构。从而导     

Analytical modeling on the geo-stress and casing damage prevention with the thermo-hydro-mechanical (THM) coupling of multi-field physics

Journal of Thermal Analysis and Calorimetry - Understanding the rule of squeezing force on casing changing with the working parameters of wells, such as steam injection pressure, steam injection...     

甲醇POSR制氢的反应网络热力学分析和有效因子的估算

在Cu/ZnO/Al2O3催化剂上对甲醇部分氧化蒸汽重整制备氢气反应的动力学过程进行了研究。在常压和473 K～1 073 K温度范围内对该反应网络中的甲醇部分氧化、甲醇蒸汽重整、甲醇分解和水煤气反应的化学平衡进行了分析。在对这些反应的催化剂Cu/ZnO/Al2O3动力学研究的基础上，根据有效因子的基本概念，考虑催化剂颗粒内的扩散限制，对每个反应沿反应器床层的有效因子进行了估算。     

Influence of pre-curing time on the hydration of binder and the properties of concrete under steam curing condition

There is a pre-curing period before the freshly made concrete elements were exposed to steam curing in the steam curing process. In this paper, the influence of pre-curing time on the hydration of binder and the properties of concrete under steam curing condition was investigated. Three binders were used: the pure cement, the binder containing high content of GGBS, and the binder containing high content of fly ash. Three pre-curing times (1, 3, and 6 h) and one steam curing period at 60 °C (over 8 h) were adopted. Results show that pre-curing time has limited influence on the hydration degree of binder, and compressive strength and pore structure of paste. The influence of pre-curing time has limited influence on the compressive strength and chloride permeability of the pure cement concrete and the concrete containing high content of GGBS at whether early or late ages, indicating that the proper pre-curing time can be as short as 1 h for these two concretes. Increasing pre-curing time enhances the late-age compressive strength of the concrete containing high content of fly ash significantly, but it has limited influence on the late-age permeability.     

碱金属钾对Ni基催化剂纤维素水蒸气气化活性的影响

采用两段式催化气化方式研究了生物质热解气化过程中碱金属的挥发对Ni基催化剂活性的影响。实验结果表明,负载K盐的纤维素水蒸气催化气化过程中,K挥发后会在催化剂表面沉积,而少量K的存在和表面沉积不但能够提高镍基催化剂的抗积炭能力,而且有助于提高其催化活性,产生更多的氢气。然而纤维素中K的浓度过大,将会抑制Ni基催化剂的效果;K在催化剂上的沉积随催化剂循环次数的增加而增加,K的含量愈高,对催化剂的抑制效果愈明显,从而缩短了催化剂的使用寿命。     

神华煤直接液化残渣水蒸气和CO_2气化反应性研究

分别对神华煤和神华煤直接液化残渣的水蒸气和CO2气化反应性进行了研究。结果表明,水蒸气气化反应中,煤半焦的反应性强于残渣半焦;CO2气化反应中,残渣半焦的反应性强于煤半焦。这主要是影响煤和残渣水蒸气和CO2气化反应性的关键因素不同。水蒸气气化反应受煤化程度的影响较大,而CO2气化反应受煤化程度的影响较小,受矿物质催化作用的影响大。     

棉纤维素蒸汽闪爆改性及其羧甲基化研究

研究了采用高压蒸气闪爆技术对原棉纤维进行预处理，以改性后的纤维为原料合成羧甲基纤维素，并优化了合成工艺。以产品的取代度为指标，研究了高压蒸气闪爆处理条件对产品性能的影响。结果表明，随着闪爆压力的提高，产品的性能有不同程度的提高。     

Comparison of the pretreatment of sweetgum and white Oak by the steam explosion and RASH Processes

Applied Biochemistry and Biotechnology - Steam explosion and rapid steam hydrolysis/continuous extraction (RASH) processes were compared using sweetgum and white oak as the feedstocks. Both...     

Purification and opening of carbon nanotubes using steam

Purification and opening of carbon nanotubes has been carried out by treatment of as-made single-wall carbon nanotubes (SWNTs) with pure steam at 1 atm pressure. Treated samples have been characterized by high-resolution transmission electron microscopy and IR and Raman spectroscopy. Comparison between the steam purification and the standard nitric acid purification treatment shows that steam is less aggressive toward damage to the tubular nanotube wall structure and forms fewer functional groups.     

磷酸和水蒸气联合改性的HZSM-5的物化表征及催化研究

研究了磷和水蒸气联合改性HZSM-5样品的物化和催化性能。XRD和IR研究表明，没有新的晶相出现。NH3-TPD研究样品的酸性表明，经过磷改性后的样品的酸量明显下降。经过水热处理的样品的BET比表面明显降低，这可能归因于磷物种和铝物种对孔道的堵塞。氮吸附－脱附等温线研究表明，等温线为I型和IV型的复合型，滞后环为H4型。联合改性样品的正庚烷裂化转化率高于仅仅由水蒸气改性样品的正庚烷裂化转化率，从而显示出磷物种对沸石分子筛高温水蒸气脱铝的抑制作用。     

Catalytic activity of phosphorus and steam modified HZSM-5 and the theoretical selection of phosphorus grafting model

The modification of HZSM-5 zeolite with phosphorus and steam has been studied. Results show that 1% phosphorus and steam modified HZSM-5 has the highest catalytic activity for n-heptane. Physicochemical and catalytic properties of 1% phosphorus and steam modified HZSM-5 zeolites have been investigated. The X-ray diffraction （XRD） results exhibit that there is considerable variation in the relative intensity of the individual diffraction peaks. The acidity of the samples decreases with an increase in the steaming temperature, which is determined by the IR of adsorbed pyridine and temperature programmed desorption （TPD） of ammonia. The oxidation state of phosphorus shown by XPS is ＋5, and a model for surface structure modification is proposed. The nitrogen adsorption isotherm for all samples is a combination of type I and type IV, all hysteresis loops resemble the H4-type. The density functional and cluster model methods have been invoked to select the phosphorus grafting model, and it was found that the phosphorus grafting model were more probable in the form of the terminal oxygen coordinating with aluminum.