合成气制二甲醚三相淤浆床反应器的数学模型研究

A mathematical model for a bubble column slurry reactor is presented for dimethyl ether synthesis from syngas. Methanol synthesis from carbon monoxide and carbon dioxide by hydrogenation and the methanol dehydration are considered as independent reactions, in which methanol, dimethyl ether and carbon dioxide are the key components. In this model, the gas phase is considered to be in plug flow and the liquid phase to be in partly back mixing with axial distribution of solid catalyst. The simulation results show that the axial dispersion of solid catalysts, the operational height of the slurry phase in the bubble column slurry reactor, and the reaction results are influenced by the reaction temperature and pressure, which are the basic data for the scale-up of reactor.     

操作温度对褶皱型不锈钢编织型过滤器阻力特性的影响

Effect of working temperature on the resistance characteristic including the permeability coefficient and the pressure drop evolution of a pleated stainless steel woven filter with a nominal pore size of 0.5 μm has been studied. The permeability coefficient was obtained based on the pressure drop data and the Darcy’s law. In three filtration experiments, pure carbon dioxide at 283 K, nitrogen at 85 K and liquid helium at 18 K are adopted, respectively. It is found that the permeability coefficient decreases at the working temperature due to the cold shrink of the filter element at cryogenic temperature. Then, two kinds of feed slurries, mixture of liquid nitrogen and solid carbon dioxide at 85 K, and mixture of liquid helium and solid nitrogen at 18 K, flow into the filter cell. The solid particles are deposited on the filter surface to form a filter cake and the purified liquid flows through the filter. It is found that the pressure drop evolution shows the same trend on these two temperatures, which can be divided into three stages with high filtration efficiency, indicating the feasibility of the filter for cryogenic application. However, variant cake resistances are obtained, which is resulted from the different interactions between solid particles in the feed slurry at lower working temperature.     

A review of chemical absorption of carbon dioxide for biogas upgrading

Significant attention has been given to biogas production, purification and upgrading as a renewable and clean fuel supplement. Biogas is a product of an anaerobic digestion process comprising methane, carbon dioxide, and trace amounts of other gases. Biogas purification removes trace gases in biogas for safe utilisation. Biogas upgrading produces methane-rich biogas by removing bulk carbon dioxide from the gas mixture. Several carbon dioxide removal techniques can be applied for biogas upgrading. However, chemical absorption of carbon dioxide for biogas upgrading is of special significance due to its operation at ambient or near ambient temperature and pressure, thus reducing energy consumption. This paper reviews the chemical absorption of carbon dioxide using amine scrubbing, caustic solvent scrubbing, and amino acid salt solution scrubbing. Each of these tech-niques for biogas upgrading is discussed. The paper concludes that an optimised implementation of the chemical absorption techniques for biogas upgrading requires further research.     

ADSORPTION EQUILIBRIUM OF ETHYLENE-CARBON DIOXIDE MIXTURE ON ZEOLITE ZSM5 AND ITS CORRELATION

Binary gas mixture adsorption equilibrium data for the ethylene-carbon dioxide system were obtained for cation exchanged forms of ZSM5 (Li~ , Na~ , K~ , Rb~ , Mg~( 2), Ca~( 2), Sr~( 2), and Ba~( 2)) for the gas phase CO_2 mole fracion of 0.766 at 308K and 101. 3kPa. The experimental adsorption phase diagrams were obtained for CO_2-C_2H_4 on NaZSM5 and MgZSM5. Single component adsorption isotherms for CO_2 and C_2H_4 were also obtained for these two zeolites. The single component data were used to obtain parameters derived in the vacancy solution model (VSM) and the statistical thermodynamic model(STM). These parameters were, in turn, used to predict binary mixture isotherms for these two zeolites. The agreement between experimental data and predicted value is generally good.     

Effect of KCI on Growth of Carbon Fibers During Carbonization of Phenolic Resin

Effects of the KCl additions( 1%,3%,5% and7% of the phenolic resin mass) on phase composition and microstructure of the resin carbon and the growth mechanism of carbon fibers were investigated by using commercial liquid phenolic resin as carbon source and micron-scaled KCl as catalyzer,mixing,hexamethylenetetramine solidification treating,carbon-embedded firing at 1 000 ℃ for 3h in order to accelerate the graphitization of phenolic resin during carbonization. The results show that the graphitization degree of resin carbon is improved by catalysis of KCl,numerous carbon fibers with30-200 nm in diameter and 10-20 μm in length and sheet-like carbon in situ grow in resin carbon. The optimal addition of KCl is 5% when lots of carbon fibers can be found in resin carbon,and d002 diffraction peak of graphite appears obviously in the XRD pattern. The growth mechanism of carbon fiber is that the molten KCl at high temperatures absorbs carbonaceous gas from the decomposition of phenolic resin,accelerating the diffusion of solid C atoms in liquid KCl; after the dissolution of C saturates,carbon atoms separate continuously in local parts to form carbon fibers or flakes; meanwhile,the concentration gradient formed by local carbon atoms in the melt offers growth drive for the separation of carbon fibers or flakes on KCl surface.     

SCHEMES OF GAS PRODUCTION FROM NATURAL GAS HYDRATES

Natural gas hydrates are a kind of nonpolluting and high quality energy resources for future, the reserves of which are about twice of the carbon of the current fossil energy (petroleum, natural gas and coal) on the earth. And it will be the most important energy for the 21st century. The energy balance and numerical simulation are applied to study the schemes of the natural gas hydrates production in this paper, and it is considered that both depressurization and thermal stimulation are effective methods for exploiting natural gas hydrates, and that the gas production of the thermal stimulation is higher than that of the depressurization. But thermal stimulation is non-economic because it requires large amounts of energy. Therefore the combination of the two methods is a preferable method for the current development of the natural gas hydrates. The main factors which influence the production of natural gas hydrates are: the temperature of injected water, the injection rate, the initial saturation of the hydrates and the initial temperature of the reservoir which is the most important factor. 1 Lei Huaiyan, Wang Xianbin. Current Situation of Gas Hydrates Research and Challenges for Future. Acta Sedimentological Sinica, 1999, 17 (3)2 Shi Dou, Zheng Junwei. The Status and Prospects of Research and Exploitation of Natural Gas Hydrate in the World. Advance in Earth Sciences, 1999, 14 (4)3 Chen Huifan4g. Prediction of the Conditions for the Forming of Natural Gas Hydrate. Journal of Xi'an Petroleum Institute, 1994, 9 (1)4 Yao Yucheng, Yin Fushan. Progressin Study of Natural Gas Hydrates. Progress in Chemistry, 1997, 9 (3)5 Zhao Shengeai. Current Situation of Gas Hydrate and Our ??Country's Policy. Advancein Earth Sciences, 2002, 17 (3)6 Zhou Huaiyang, Peng Xiaotong. Development in Technology of Prospecting and Exploitation for Gas Hydrates. Geology and Prospecting, 2001, 38 (1)7 Zhu Yuenian, Shi Buqing. Control Effects of Natural Gas Hydrates on Oil and Gas Accumulation and Reservoir Preservation. Natural Gas Industry, 2000, 20 (3)8 Wim J A M Swinkels, Rik J J Drenth. Thermal Reservoir Simulation Model of Production from Naturally Occurring Gas Hydrate Accumulations. SPE 565509 Moridis G J, Collett T S, Dallimore S R, Tohru Satoh. Numerical Studies of Gas Production from Several CH_4-Hydrate Zones at the Mallik Site. LBNL 50257. Mackenzie Delta, Canada     

上升管中严重段塞流的流型和压力波动特性

During the exploitation of offshore oil and gas, it is easy to form severe slugging which can cause great harm in the riser connecting wellheads and offshore platform preprocessing system. The flow pattern and pressure fluctuation of severe slugging were studied in an experimental simulation system with inner diameter of 0.051 m. It is found that severe slugging can be divided into three severe slugging regimes: regime I at low gas and liquid flow rates with large pressure fluctuation, intermittent flow of liquid and gas in the riser, and apparent cutoff of liquid phase, regime II at high gas flow rate with non-periodic fluctuation and discontinuous liquid outflow and no gas cutoff, regime III at high liquid flow rate with degenerative pressure fluctuation in form of relatively stable bubbly or plug flow. The results indicate that severe slugging still occurs when the declination angle of pipeline is 0˚, and there are mainly two kinds of regimes: regime I and regime II. As the angle increases, the formation ranges of regime I and regime III increase slightly while that of regime II is not affected. With the increase of gas superficial velocity and liquid superficial velocity, the pressure fluctuation at the bottom of riser increases initially and then decreases. The maximum value of pressure fluctuation occurs at the transition boundary of regimes I and II.     

An experimental approach for measuring carbon dioxide diffusion coefficient in water and oil under supercritical conditions

Several direct or indirect approaches have been proposed to measure diffusion coefficient of gases into liquids. The main complexity of indirect techniques such as pressure decay method is interpreting early pressure–time data which strongly affected by incubation period effect or convective instability. In the current approach, accurate apparatus and precise experimental setup including a high pressure and temperature PVT cell, a high precision Sanchez pump, heating and recording sub-system are implemented and a novel data analysis procedure is applied to modify pressure decay method. The effect of incubation period is reduced remarkably and diffusion coefficient of carbon dioxide in water in wide range of pressures and temperatures is determined and the effects of temperature, pressure and carbon dioxide phase alteration from gas to supercritical are investigated and the value of uncertainty is estimated.Furthermore, diffusion coefficient of CO_2 and methane in an oil sample from one of the Iranian southwest oil formations is determined precisely using the experimental approach while no incubation period is detected. The results showed that incubation period duration decreases with increasing diffusion coefficient. Additionally, when CO_2 state is gas, rate of increasing diffusion coefficient with pressure is decreased with temperature and when CO_2 state is supercritical, the rate of increasing diffusion coefficient with pressure is decreased significantly.     

第三分散相液滴增强气体吸收的一维非稳态非均相传质模型

A model for one-dimensional unsteady heterogeneous mass transfer was developed based on Danckwerts’ surface renewal theory in order to describe the mass transfer enhancement of absorption process for a slightly soluble gas in a gas-liquid-liquid system. The model accounts for the mass transfer resistance within the dispersed phase and the effect of emulsion viscosity on mass transfer. An analytical solution for enhancement factor was obtained by Laplace domain transformation. The absorption rates of carbon dioxide in the dodecane-in-water and castor oil-in-water systems were measured in a thermostatic reactor, and the enhancement factors were calculated at different volume fractions of dispersed phase and stirrer speeds. The model predictions agree well with the experi-mental data.     

基于Aspen Plus的气流床煤气化炉三段平衡模型(英文)

A three stage equilibrium model is developed for coal gasification in the Texaco type coal gasifiers based on Aspen Plus to calculate the composition of product gas, carbon conversion, and gasification temperature. The model is divided into three stages including pyrolysis and combustion stage, char gas reaction stage, and gas phase reaction stage. Part of the water produced in the pyrolysis and combustion stage is assumed to be involved in the second stage to react with the unburned carbon. Carbon conversion is then estimated in the second stage by steam participation ratio expressed as a function of temperature. And the gas product compositions are calculated from gas phase reactions in the third stage. The simulation results are consistent with published experimental data.     

LNG管道输送工艺设计方法研究

LNG的管道输送技术作为一种新的LNG输送方式被越来越多学者的所关注。采用P-R方程进行LNG物性参数的计算,并讨论了压力温度以及相态的改变对LNG物性的影响;对LNG在过冷态、密相、超临界三种状态下管输工艺进行了工况的研究与分析,提出了过冷输送、密相输送、超临界输送三种输送方案。为天然气液化装置、LNG装卸装置和LNG冷能利用装置的管道输送提供理论指导,为LNG长距离管道输送提供理论基础。     

一种高效复合型气体水合物抑制剂的研究

在油气运输管道中,气体水合物的形成会造成管道堵塞,给油气行业带来巨大的损失。为了抑制水合物的形成,文章以二氧化碳水合物为实验对象,在低温高压带视镜悬浮搅拌试验装置中,分别采用聚乙烯吡咯烷酮(PVP),氯化钠以及这两者的复合液作为抑制剂进行实验。通过诱导时间和气体耗气量的比较,结果表明,单一的PVP能有效的延长气体水合物生成的诱导时间,单一的氯化钠能降低反应体系的耗气量,而由PVP与氯化钠复配得到的复合型抑制剂能延长反应的诱导时间和降低反应耗气量,是一种高效的气体水合物抑制剂。     

Development of an optimal multifloor layout model for the generic liquefied natural gas liquefaction process

Liquefied natural gas (LNG) is attracting significant interest as a clean energy alternative to other fossil fuels, mainly for its ease of transport and low carbon dioxide emission. As worldwide demand for LNG consumption has increased, liquefied natural gas floating, production, storage, and offloading (LNG-FPSO) operations have been studied for offshore applications. In particular, the LNG-FPSO topside process systems are located in limited areas. Therefore, the process plant layout of the LNG-FPSO topside systems will be optimized to reduce the area cost occupied by the topside equipment, and this process plant layout will be designed as a multifloor concept. We describe an optimal layout for a generic offshore LNG liquefaction process operated by the dual mixed refrigerant (DMR) cycle. To optimize the multifloor layout for the DMR liquefaction cycle process, an optimization was performed by dividing it into first and the second cycles. A mathematical model of the multifloor layout problem based on these two cycles was formulated, and an optimal multifloor layout was determined by mixed integer linear programming. The mathematical model of the first cycle consists of 725 continuous variables, 198 equality constraints, and 1,107 inequality constraints. The mathematical model of the second cycle consists of 1,291 continuous variables, 286 equality constraints, and 2,327 inequality constraints. The minimization of the total layout cost was defined as an objective function. The proposed model was applied to DMR liquefaction cycle process to determine the optimal multifloor layout.     

初始压力对冰冻石英砂中CO2水合物生成特性的影响

利用冰冻石英砂模拟冻土水合物的赋存条件，研究了压力对二氧化碳水合物生成特性的影响，在300 mL高压水合物反应釜中于271 K下进行了多组CO2液化压力以上及以下的霰状冰粉包裹的石英砂中水合物生成实验。结果表明，充入的CO2未液化时，初始压力越大，水合反应速率越快，压力越早达稳定状态；充入压力达液化压力后，注入的CO2越多，水合反应速率越快。压力作为水合反应的驱动力，压力越高水合物生成越多，冰的最终转化率越高。采用CO2置换冻土区中甲烷水合物时，控制压力低于液化压力或注入过量的CO2，置换效果更好。     

城镇液化天然气点供市场推广前景展望

液化天然气(LNG)作为运输灵活的清洁能源,是目前管输天然气无法到达区域的主要气源或过渡气源。LNG点供具有建设周期短及迅速满足用气市场需求的优势,未来将逐渐在省内用气需求大的乡镇建成。在介绍LNG点供站的基本概念和优势的基础上,着重讨论了LNG点供站的工艺流程和主要设备,分析了LNG点供站的运行管理情况,并就LNG点供在乡镇市场推广的可行性进行了探讨。     

液化石油气中二甲醚含量检测方法研究

通过对液化石油气和二甲醚的物理、化学特性分析研究,建立恒温水浴气化取样手段,保证样品不失真。经过反复实验,建立了毛细管色谱柱气相色谱法测定液化石油气中二甲醚含量的分析方法。结果表明,该方法具有良好的准确度和精密度。     

Über Naturwachse XVI: Gas-Chromatographie der Wachsester

Natural Waxes XVI: Gas Chromatography of Wax Esters The authors have applied the method of high temperature gas chromatography of wax esters in the study on relationship between position of ester group in the carbon chain on the retention volumes of isomeric esters. In esters containing one double bond variations in retention data were observed. Gas chromatography and mass spectroscopy revealed that inspite of its apparent simplicity, spermaceti-ester is actually a complex mixture of esters, since each gas chromatographic peak, corresponding to a definite carbon number, contains a mixture of isomeric esters. These esters differ from each other only with respect to position of their ester group.     

烟道气回收CO2的工业应用

本文阐述烟道气CO2回收技术以及榆林天然气化工有限公司回收烟道气CO2的应用总结。     

气相色谱法分析检验液化石油气中甲缩醛

建立了用毛细管色谱法定量检验液化石油气中甲缩醛的方法。在优化色谱定性条件的基础上,采用切换液体阀进样,外标法定量。实验结果表明：甲缩醛在0.1%－50%（m/m）范围内的线性关系良好,加标回收率在96.0%－102.8%之间。     

Synthesis of heat exchanger networks at subambient conditions with compression and expansion of process streams

This article presents an optimization formulation for the synthesis of heat exchanger networks where pressure levels of process streams can be adjusted to improve heat integration. Especially important at subambient conditions, this allows for the interconversion of work, temperature, and pressure‐based exergy and leads to reduced usage of expensive cold utility. Furthermore, stream temperatures and pressures are tuned for close tracking of the composite curves yielding increased exergy efficiency. The formulation is showcased on a simple example and applied to a case study drawn from the design of an offshore natural gas liquefaction process. Aided by the optimization, it is demonstrated how the process can extract exergy from liquid nitrogen and carbon dioxide streams to support the liquefaction of a natural gas stream without additional utilities. This process is part of a liquefied energy chain, which, supplies natural gas for power generation while facilitating carbon dioxide sequestration. © 2010 American Institute of Chemical Engineers AIChE J, 2011