Characteristics of air-blown gasification in a pebble bed gasifier

High temperature air-blown gasification is a new concept to utilize the waste heat from gasifier that is called multi-staged enthalpy extraction technology. This process was developed to solve the economic problems due to air separation costs for the oxygen-blown as a gasifying agent. In this study, we have constructed a pebble bed gasifier and operated it by controlling the pebble size and bed height with three different types of coal (Kideco, Datong and Drayton coal). As a result, we can produce syngas with a calorific value of 700 kcal/Nm³ at an air temperature of 650 °C; the performance of high temperature air gasification was strong in the order of Kideco coal, Datong coal and Drayton coal. Also, from the data of the exterior analysis of slag that is attached to the surface of pebbles, we can know that the iron component is considerably high. This means the increase in restored metallic iron component seems to contribute to the solidification of slag.     

Effect of radiation intensity on photo-oxidation of an air-blown bitumen

Xenon-arc irradiation was used to study the influence of a wide range of radiation intensity on the rate of photo-oxidation of a sample of air-blown bitumen as determined by infra-red spectroscopy. The xenon-arc was monitored to provide information on its rate of decay, and its range of intensity was compared with that of total solar radiation in Melbourne. Thermal (dark) oxidation rates were also determined at various temperatures. The information obtained is discussed in terms of the mechanism of photo-oxidation of bitumen and the relation to climatological data. Acceleration factors for oxidation of bitumen in the laboratory for prediction of durability were determined by applying the superposition principle to the data.     

生物质多元醇的研究进展

当前,日益严重的全球性能源和环境问题促使开发利用可再生的生物质资源成为研究热点。在可再生资源中,生物质多元醇以其来源多样、应用广泛备受人们关注。概述了生物质多元醇的来源、合成和应用方面的最新进展。以淀粉、纤维素等制备多元醇,再以多元醇制备氢气、燃油、化学品等众多物质,以及将多元醇与松香、植物油等聚合成可降解材料。指出生物质多元醇将成为今后合成可再生燃料和化学品等的新型平台分子。     

Biomass-derived materials for electrochemical energy storages

During the past decade humans have witnessed dramatic expansion of fundamental research as well as the commercialization in the area of electrochemical energy storage, which is driven by the urgent demand by portable electronic devices, electric vehicles, transportation and storage of renewable energy for the power grid in the clean energy economy. Li-secondary batteries and electrochemical capacitors can efficiently convert stored chemical energy into electrical energy, and are currently the rapid-growing rechargeable devices. However, the characteristic (including energy density, cost, and safety issues, etc.) reported for these current rechargeable devices still cannot meet the requirements for electric vehicles and grid energy storage, which are mainly caused by the limited properties of the key materials (e.g. anode, cathode, electrolyte, separator, and binder) employed by these devices. Moreover, these key materials are normally far from renewable and sustainable. Therefore great challenges and opportunities remain to be realized are to search green and low-cost materials with high performances. A large number of the properties of biomass materials-such as renewable, low-cost, earth-abundant, specific structures, mechanical property and many others-are very attractive. These properties endow that biomass could replace some key materials in electrochemical energy storage systems. In this review, we focus on the fundamentals and applications of biomass-derived materials in electrochemical energy storage techniques. Specifically, we summarize the recent advances of the utilization of various biomasses as separators, binders and electrode materials. Finally, several perspectives related to the biomass-derived materials for electrochemical energy storages are proposed based on the reported progress and our own evaluation, aiming to provide some possible research directions in this field.     

生物质炭基材料在有机催化转化中的应用

近年来,生物质因具有富碳可再生、储量丰富、环境友好、价格低廉等特点被作为原料广泛应用于制备生物质炭基材料。本文综述了以生物质为原料衍生炭基材料作为催化剂在有机转化反应中的相关研究进展,重点介绍了杂原子掺杂、金属杂化策略所制备炭基催化材料在液相催化加氢、氧化、偶联等有机转化反应中的催化性能,进而阐明了炭基催化剂与催化活性之间的构效关系。最后,本文总结了生物质炭基催化剂在有机催化反应中的优势,指出了目前生物质衍生炭基催化剂材料合成和有机转化研究领域面临的挑战,并对此领域的未来发展趋势进行了分析与展望。     

Carbon conversion in an atmospheric-pressure entrained coal gasifier

Entrained gasification tests with a Utah high-volatile bituminous coal were performed at atmospheric pressure to assess the influence of particle size, coal feed rate, steam-coal ratio and oxygen-coal ratio. Independent argon-carbon balance and ash balance methods were used to evaluate carbon conversion, with good agreement observed between the methods. A higher O₂-coal ratio and finer particles increased the carbon conversion. Carbon conversion and hydrogen formation showed little dependence on the amount of steam injected in the secondary stream, indicating minimal steam-coal reaction. When the coal feed rate was varied from 23 to 27 kg h⁻¹, a small increase in carbon conversion was observed with no significant change in the gas composition.     

煤制氢气化炉—洗涤塔开工线的使用与维护

中国石化九江分公司通过对化肥装置进行产业结构调整,引进GE水煤浆气化技术,并对其进行技术改进,引进了气化炉与洗涤塔之间的黑水管线(简称开工线),从而设计了制氢能力105 000 m~3/h煤制氢装置,阐述了开工线在气化炉的开车、停车、气化炉连投事故状态下的使用以及日常维护。     

Design of an indirect heat rotary kiln gasifier

A non-ordinary type of solid fuel gasification reactor, which was under development for the few past decades and it is briefly described as indirect heat rotary kiln gasifier, seems to be capable of sufficiently satisfying the incorporated gasification needs in the most challenging contemporary power technologies using solid fuels, like IGCC and CLC combustion. The design of such a gasifier emerges in this work, while the focus is mostly on the presentation of the relevant theoretical model. Moreover, model predictions are compared and optimized with respect to experimental data that were acquired in a pilot scale gasification unit including the suggested type of gasifier. Comparisons showed successful predictions of such a marginal error that could be characterized as quite sufficient for a primary model validation. However, the model flexibility to a wide variety of different solid fuels, rotary kiln configurations and operating conditions has to be verified by assessment of further experimental results.     

Styrenation of air-blown linseed oil by nitroxide-mediated radical polymerization

Styrenation of air-blown linseed oil by a nitroxide-mediated radical polymerization (NMRP) technique is described. In this technique, air-blown linseed oil bearing hydroperoxide groups was used as a macroinitiator in NMRP of styrene in the presence of 2,2′,6,6′-tetramethylpiperidinyl-1-oxy (TEMPO). The effects of various parameters, such as the amount of TEMPO and hydroperoxide groups, were investigated in terms of molecular weight and polydispersity. For comparison, a copolymer sample of air-blown linseed oil with styrene was also prepared in the absence of TEMPO. The film properties of all samples were determined according to the related standards and were compared with respect to surface protection. Samples prepared by the NMRP technique exhibited relatively narrow polydispersity and better film properties compared to those of the samples obtained by the conventional method.     

奥里乳化油气流床气化过程的数值模拟研究

采用欧拉-拉格朗日方法对奥里乳化油气流床气化过程进行数值模拟研究,对气化炉内的非均相反应过程采用颗粒表面化学反应模型描述,对均相反应过程采用考虑了湍流对均相反应影响的有限速率/涡耗散反应模型。研究结果表明,气化炉内靠近喷嘴区域反应剧烈,温度及组分变化明显,但在气化炉的后半段变化较小。同时考察了氧气当量比对气化炉性能的影响,高氧气当量比可以得到较高的炉内温度和碳转化率以及较低的CO和H2摩尔分数。     

Characterization of air-blown asphalt/trans-polyoctenamer rubber blends

Air-blown asphalt (ABA) was modified by blending with trans-polyoctenamer rubber (TOR). The thermal properties examined by differential scanning calorimetry indicated that flexible aliphatic hydrocarbons in maltene phase or paraffin wax, preferentially dissolved into the TOR phase from the ABA phase. Rheological properties examined with a rheometer by frequency sweep and temperature sweep suggested that the polymer modified asphalt is a multiphase system composed of a phase formed by maltenes, a mesoscopic phase rich in asphaltenes, and a TOR phase swelled by dissolved maltenes. The elasticity, modulus, and the temperature susceptibility of ABA were improved by modification with TOR.     

Modeling and simulation of an entrained flow coal gasifier

A mathematical model has been developed to simulate the Texaco downflow entrained-bed pilot-plant gasifier using coal liquefaction residues and coal-water slurries as feedstocks. This model describes the physical and chemical processes occurring in an entrained coal gasifier. The gasification kinetics describes different complex reactions occurring in the gasifier and the hydrodynamics describes mass, momentum and energy balances for solid and gas phases. Temperature, concentration and velocity profiles along the reactor height were obtained by solving the mass, momentum and energy balances. Parameter studies were made to provide a better understanding of the reactor performance for various inlet feed conditions utilizing the model.     

Two-stage equilibrium model for a coal gasifier to predict the accurate carbon conversion in hydrogen production

The performance of the Texaco gasifier in hydrogen production was studied numerically. To estimate the accurate carbon conversion, a two-stage equilibrium model was proposed. In the proposed model, the two reactions which determined the carbon conversion were separated from other vapor–vapor reactions. The governing equations of the proposed model were derived and a self-consistent method was developed to solve the governing equations. The %AAD of the calculated carbon conversions from the measured values was 2.89 and that of the calculated gas production rate was 0.64. Calculated gas compositions showed a fairly good agreement with the experimental ones for commercial scale plants. It was found that the chemical reactions that occurred in the Texaco gasifier possess a mechanism for keeping the carbon conversion close to unity against a wide variation in the H₂O to coal ratios.     

Modelling of an updraft fixed-bed gasifier operated with softwood pellets

This paper presents a one-dimensional steady state mathematical model for the simulation of a small scale fixed-bed gasifier. The model is based on a set of differential equations describing the entire gasification process of softwood pellets and is solved by a two step iterative method. The main features of the model are: homogeneous and heterogeneous combustion and gasification reactions, one-step global pyrolysis kinetics and drying, heat and mass transfer in the solid and gas phases as well as between phases, heat loss, particle movement and shrinkage within the bed. The pyrolysis model has been improved by partially cracking primary tar into lighter gases according to experimental data. The model is used to simulate a laboratory scale fixed-bed updraft gasifier. Good agreement is achieved between prediction and measurements for the axial temperature profiles and the composition of the producer gas. Moreover, results are presented for different air to fuel ratios and varying power inputs. The gasification process is improved by increasing the power input of the gasifier as a result of higher temperatures. Furthermore, a higher air to fuel ratio lowers the efficiency of the gasification process.     

Numerical analysis of the flow field inside an entrained-flow gasifier

The flow field of an entrained-flow gasifier was numerically simulated to describe coal gasification process. The standard k-ε turbulence model and SIMPLE procedure were used with the Primitive-Variable method during computation. In order to investigate the influencing factors on the flow field that may have a great effect on coal gasification process, some parametric studies were performed by changing the gas injection angle, gas inlet diameter, gas inlet velocity, extension in burner length and gasifier geometry. The calculation results showed that the basic patterns of the flow field inside the gasifier were nearly the same with a parabolic distribution irrespective of the change in parameters. There existed an obvious external recirculation zone with axial length less than 1.0 m and a narrow internal recirculation region was observed in the entrance of gasifier inlet. The geometry parameters of the burner, such as the oxygen inlet diameter and angle, influenced the flow field at the inlet region near the burner. But after a certain length along the gasifier, the flow field was nearly the same as that in the basic case.     

Experimental measurement of gas concentration distribution in an impinging entrained-flow gasifier

On a laboratory-scale testing platform of impinging entrained-flow gasifier with two opposed burners, the detailed measurements of gas concentration distribution have been performed for carbonaceous compound (diesel oil) at atmospheric pressure. Under the condition of 1.48–2.36 O/C ratios (kg/kg), radial gas samples are collected at three axial positions and the syngas exit position with stainless steel water-cooled probes, the concentration distribution of the major gases (H₂, CO, CO₂, CH₄ and O₂) under stable operating state was determined with a mass spectrometry. These data are used to clarify mixing and reaction characteristics within the reactor, to give insight into the combustion process and provide a database for evaluating predictive mathematical models.     

Corrosion of phosphate added high-chrome refractory materials in an entrained-flow gasifier

Durability of the refractory liner located in an entrained-flow gasifier is one of the main factors affecting the efficiency and cost of gasification process. This study investigates the corrosion mechanism of phosphate added high-chrome refractories in a commercial entrained-flow gasifier and the effect of phosphate additives on the improvement of service life combining thermodynamic simulation calculations. The microstructures, chemical compositions, and mineral phases of the corroded samples were analyzed by scanning electron microscopy (SEM and EDS) and X-ray powder diffraction (XRD). The results demonstrated that chemical corrosion mainly occurred at the slag-matrix interface and the junction of aggregates and matrix regions. Complex spinel solid solutions were formed at the slag-refractory interface. Phosphate additives decomposed into gaseous products (such as O₂, P₂O₃) and diffused into the interior of refractories at or close to the slag-refractory interface, not only causing an oxidizing environment but also increasing the phosphate contents in the interior of refractories. Phosphate additives in the infiltration layer occupied the gaps between crystal grains of (Cr, Al)₂O₃ solid solutions, reduced the infiltration of silicate phases, and absorbed Ca and Na in the slag, which subsequently increased the viscosity of the slag.     

气化炉水动力计算软件的开发及在GSP气化水汽系统中的应用

为核对气化炉水汽系统的水动力安全或优化气化炉水汽系统的操作,提出了通用水动力计算模型,开发了适用于干煤粉气化系统的水动力计算软件。以神华宁煤烯烃GSP干煤粉气化的水动力系统为算列,模拟结果表明,排渣口处水路出口温度软件计算值为168.8℃,运行监测值为168.3℃,其他水路出口温度计算值与监测值最高偏差2.2%;排渣口水路进出口温差的计算值比运行监测值低1.3℃,而烧嘴支撑和水冷盘管计算值与运行监测值的偏差0.3℃;循环水罐、汽包和泵相关参数的模拟值与工业实际运行数值完全一致。     

The thermal history of char samples taken from a gasifier

The thermal history of coal chars obtained from a fixed bed gasifier is of importance in understanding gasifier performance and behaviour. Several methods of assessing thermal history have been considered. The results show that Raman spectroscopy is a good method for estimating the heat treatment temperature in a thermally homogeneous coal char sample, whereas reflectance measurements provide a rapid means of characterizing thermal heterogeneity of the char samples in the temperature range 400–1000 °C. The advantages of the techniques over other char characterization methods are discussed.