The role of a coal gasification fly ash as clay additive in building ceramic

The clean coal integrated gasification in combined cycle (IGCC) technology of electrical power generation is different than conventional process in combustible treatment which generates inorganic wastes in the form of glassy slag and fly ash with singular properties. We have studied the fly ash coming from ELCOGAS IGCC power plant as additive to clays for building ceramic fabrication.

The addition of this new kind of fly ash to a clay of medium plasticity to elaborate pressed specimens, that were baked at 900 °C, improves the sintering of the paste and consequently an improvement of absorption, saturation and mechanical properties of the fired bodies, with no negative effects on shrinkage, colour alteration or efflorescence. In contrast, this fly ash does not mend the excessive firing shrinkage when added to a clay of a high plasticity index.     

煤气化残渣基多孔陶瓷的制备研究

为拓展煤气化残渣综合利用途径,提高煤气化渣的附加值,以工业固体废弃物煤气化残渣为主要原料,采用模压成型工艺,在较低温度下烧结制备了煤气化残渣基多孔陶瓷,着重研究了不同烧结温度对多孔陶瓷的机械性能、物相结构、孔隙率以及N_2通量的影响。结果表明,多孔陶瓷烧结物相主要以莫来石相和石英相为主,反应烧结是主要的烧结过程机制。烧结温度为1 100℃时,煤气化残渣基多孔陶瓷性能最优,孔隙率为49.2%,平均孔径为5.96μm,0.01 MPa压力下平均N2通量达到2 452.6 m~3/(m~2·h),抗弯强度达到8.96 MPa。制备的煤气化残渣基多孔陶瓷具有高强度、高通量以及低成本的优异性能,有望用于高温气体过滤以及污水处理,解决煤气化残渣的环境污染问题。     

Hydrogen production from allothermal biomass gasification by means of palladium membranes

One of the most promising technologies for the production of hydrogen is the use of a Palladium Membrane in order to separate hydrogen from a gas mixture coming from the allothermal biomass gasification process. At the TU München, an innovative allothermal gasifier called Biomass Heat Pipe Reformer (BioHPR) has been developed. This gasifier produces a hydrogen rich gas which can be further used for energy production. A Palladium Membrane can be installed in the gasifier in order to gain pure hydrogen from this gas mixture. This gas can be then used in applications which demand high purified hydrogen like for example Polymer Electrolyte Membrane Fuel Cells (PEMFC). The present paper describes the aforementioned gasification technology combined with a palladium filter and investigates the results from the simulation of these systems.     

Possibilities and state of development of nuclear coal gasification processes

By the development work of the last years and the successful operation of a experimental reactor it is clear today that the high temperature reactor is capable to produce heat at a temperature level of 950° C. This heat can be used in different industrial processes, especially for coal gasification. The processes of hydrogasification and steam gasification have been tested in large pilot plants in the past and are thought to be feasible today in connection with use of nuclear energy. In this paper the main aspects of these processes, of the nuclear reactor and of the heat exchanger system are presented and discussed. Questions like the choice and qualification of high temperature materials, the tritium contamination of the product gas and the aspects of licensing are key points of the technical realisation of nuclear process heat applications. This paper tries to summarize some of these results of the development programm of the PNP-Project (Prototyp Nukleare Prozeβwärme) in Germany, which is a common Projekt of German Companies financed by the government.     

铁碳微电解深度处理煤制气废水的条件优化

采用铁碳微电解对煤制气项目生化处理后的废水进行深度处理。分别考察了静态实验条件下废水的初始p H值、反应时间、铁碳微电解一体化填料的类型及投加量对微电解反应效果的影响。经过实验筛选出最佳的铁碳微电解填料为Poten-ICME05及p H值为3.01、投加量80 g/L及反应时间为60 min是最佳反应条件。在此条件下,废水CODCr从初始的133.6 mg/L降到27.0 mg/L,去除率为79.79%;废水浊度由初始的0.63 NTU降到0.29 NTU,去除率为53.97%;废水色度由初始的260倍降到10倍,去除率为96.15%;BOD5/CODCr由初始的0.166提高到0.353,废水的可生化性得到较好的改善。经处理后出水水质主要指标完全可以达到地方排放标准CODCr≤40 mg/L。结果表明:Poten-ICME05是一种性能良好的微电解一体化填料,对去除废水中CODCr、浊度、色度等的效果最好,能有效地应用于煤制气废水的深度处理。     

Development of a gastight sealing material for ceramic components

Within the framework of a cooperation project, ceramic components of alumina, Al₂O₃, were sealed in a gastight manner for chemical applications using a sealing compound based on ceramic raw materials. The sealing is adapted to the Al₂O₃ ceramic with respect to expansion coefficient and wettability and it is inert, mechanically stable, chemically resistant and above all gastight at application temperatures of approx. 1000 °C. This was achieved with high reproducibility by a composition in the SiO₂–Al₂O₃–CaO–K₂O quaternary system. The ceramic sealing compound is selectively crystallized by adequate temperature control and shows then the required high temperature resistance. The strengths achieved are sufficient for the planned application as a sealing material for a ceramic microreactor. The temperature cycling resistance and the thermal shock resistance are also adapted to Al₂O₃. Additional tests of commercial glass sealants were carried out to evaluate the results obtained.     

强化混凝技术在煤气化废水深度处理中的应用

对内蒙古某煤化工企业废水处理系统生化段二沉池出水进行混凝沉淀试验研究,通过选择具有针对性的药剂来强化混凝沉淀的处理效果。结果表明,当煤化工废水专用混凝剂(M180-3A配合M180-3B)和脱色剂T6组合使用时,能同时达到去除废水中CODCr和色度的目的。M180-3A和M180-3B的投加量均为300 mg/L,脱色剂T6的投加量为100 mg/L时,出水CODCr的质量浓度为77 mg/L,色度为40倍,满足HG/T 3923—2007《循环冷却水用再生水水质标准》的要求。     

Catalytic coal gasification: use of calcium versus potassium

A comparative study is made of the relative catalytic effects of potassium and calcium on the gasification in air and 3.1 kPa steam of North Dakota lignitic chars prepared under slow and rapid pyrolysis conditions. It is indicated that potassium achieves relatively high catalytic activity by chemical interaction with the carbonaceous support, no matter how it is added to the lignite or its char. Deactivation of the catalytic potassium is brought about by interaction with inherent aluminosilicates. However, deactivation of calcium is related to its sintering via crystallite growth.     

煤炭气化焦化废水的微生物处理技术现状

重点介绍了微生物处理技术在煤气化及焦化废水处理中的应用,简单介绍了煤炭地下气化可能造成地下水污染中有机物组分以及所造成有机污染的微生物处理方法。     

煤气化废水处理工艺的现状及发展方向

对煤气化产生废水的特点及其处理难点进行了分析。针对煤气化废水处理的3个主要阶段,分别介绍了近年来一些煤气化废水处理新工艺的应用情况及今后的发展方向,并且提出了企业在选择处理工艺时应注意的问题。     

Application of catalysts to coal gasification processes. Incentives and perspectives

There are several processes used for coal gasification, but these have three characteristic types of reactors — moving-bed, fluidized-bed and entrained phase. Design and comparison of different processes and reactors is possible if kinetic data relevant to technical performance of processes are available. The state of reaction kinetics of the non-catalysed and catalysed steam-carbon reaction as the basic coal gasification reaction is discussed. Catalysts only have effects on gasification rates in the temperature range of chemical reaction or pore diffusion control. Furthermore the increase in reaction rates by catalysts can also be reached without using catalysts. Therefore the application of catalysts seems not to be attractive in conventional gasification processes because the advantages (less coal and oxygen consumption and lower heat losses) are compensated by their disadvantages (additional costs, side effects). Only such processes in which a temperature increase is limited for different reasons does the application of catalysts have significant advantages. Such processes are the allothermal gasification using nuclear heat and processes leading to synthetic natural gas (SNG).     

Caustic oxidation as a pretreatment to high pressure bituminous coal gasification

Illinois No. 6 bituminous coal, which had been pretreated with potassium hydroxide, could not be efficiently gasified at the high pressure of 3.5 MPa in a fluidized-bed gasifier. The same feedstock performed well at a much lower operating pressure. However, at the high pressure the pyrolysed coal swelled significantly. The resulting low bed density produced a small carbon inventory in the gasifier. In addition, the coal char was very friable and large quantities of fine particulate material were entrained by the product gas. To prevent the swelling the coal was initially oxidized. A way was discovered to selectively convert the coal bitumen to humic acid, a substance that is rich in carboxylic acid groups. A direct correlation was found between the humic acid's carboxylate content and the swelling characteristics of the pyrolysed coal. The char bulk density was greatest when the humate carboxylic acid group content was maximized. It appears that when the coal was fed to the hot gasifier, these carboxylic acids decarboxylated and produced radical centres. The crosslinks that resulted from these radicals formed relatively stable carbon-carbon bridges, and this was sufficient to prevent the pyrolytic swelling.     

适宜"三高"煤利用的煤气化技术探讨

我国煤炭资源中高灰、高硫、高灰熔点煤(简称"三高"煤)所占比例较高,开发高效、洁净的"三高"煤加工技术对我国煤炭资源的可持续发展和利用有重要意义.本文通过对"三高"煤煤质特点进行分析,结合国内外发展较快的粉煤气化技术,综述了"三高"粉煤气流床气化的可行性,为促进"三高"煤高效、洁净利用提出了积极的建议.     

Experimental investigation into compression properties of integrated coal gasification combined cycle fly ashes on a ceramic filter

The compression properties of IGCC (integrated coal gasification combined cycle) fly ash cake on a ceramic filter were carefully investigated under well-controlled conditions. Overall cake porosity and pressure drop of dust cake of three different particles of geometric mean diameters of 3.7, 6.2, and 12.1 Μm, and dynamic shape factors of 1.37, 1.57 and 1.65, respectively, were investigated, at face velocities of 0.02-0.06 m/s. Overall cake porosity was strongly dependent on face velocity, mass load, and particle size. The expressions for overall cake porosity, considering the compression effect, and pressure drop across the dust cake were developed with good agreement with experimental results.     

PET as a support material for TiO2 in advanced oxidation processes

The use of polyethylene terephthalate (PET) as a support material for TiO₂ films in advanced oxidation processes (AOPs) for water treatment was investigated. A green, low‐cost immobilization procedure was developed and the amount of deposited photocatalyst ranged from 0.036 to 0.202 mg per cm² PET. Photocatalytic activity of the films was evidenced by degrading paracetamol solutions under UV radiation. The highest kinetic constants were observed for at least 0.09 mg TiO₂ per cm² PET. Scan electron microscopy (SEM) and energy‐dispersive X‐ray (EDX) analyses indicated 0.15 mg TiO₂ per cm² PET as enough to provide complete covering of the PET support. Characterization analyses were also performed with a film after 30 h of use in a UV/TiO₂/O₃ reactor. According to SEM analyses, the photocatalyst was not detached from the PET support, while EDX and gravimetric data indicated the possibility of the TiO₂ to have been contaminated by compounds present in the solution during the treatment. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40175.     

凝胶--封孔法制备不锈钢表面陶瓷膜层

为改善不锈钢的抗高温氧化性和耐磨性,拓宽其应用范围,采用凝胶－－封也法在不锈钢表面制得陶瓷膜层。介绍了该方法的工艺过程,探讨了电沉积及封孔机理以及各因素对成膜过程的影响。该方法所得陶瓷膜层光滑平整,具有好的耐磨性及抗高温氧化性。     

陶瓷膜在化工废水深度处理中的应用

研究了陶瓷膜过滤装置处理化工废水中污染物的工艺条件对处理效果的影响。研究结果表明,在操作压力为0.12MPa,膜面流速为6.0m/s的最佳工艺条件下,用陶瓷膜处理浊度为153mg/L的化工废水,可获得浊度6.8mg/L的净化水。     

Mineral attachment to calcium-based sorbent particles during in situ desulfurization in coal gasification processes

Minerals' attachment to calcium-based sorbent particles during in situ desulfurization of coal gasification process has been investigated. Results show that iron (Fe) from coal tends to attach itself to calcium (Ca) as a result of solid–solid reactions occurring during the process, and hence, forming complex compounds, e.g. calcium iron oxide (CaFe₃O₅) and ilvite (CaFe₃(SiO₄)₂OH). Other alkali metals included in the ash do not show much of this tendency. The occurrence of solid–solid reactions reduces the efficiency of the sorbents due to the reduction of effective absorption area and also leads to the agglomeration of particles. Results also show that these reactions tend to occur in very fine particles at localized locations. This suggests that a proper choice of sorbent particle sizes may reduce their effect.     

Modelling coal char gasification in a fluidized bed

Predictions obtained by using the accepted reaction model together with three different reactor models — plug-flow, complete-mixing and bubble-assemblage — are compared. In general, the three reactor models gave significantly different results. The bubble-assemblage model, therefore, represents a valid alternative when modelling fluidized-bed gasifiers. For small inverse space velocities, meaning high steam feed rates and shallow beds, the bubble-assemblage model predicts the lowest (among the three) steam conversions. For deep beds and low steam feed rates, the conversion predicted by the bubble-assemblage model becomes greater than that predicted by the completely mixed model and approaches the values for the plug-flow model. However, this occurs only at very large height/diameter ratios which are not generally used in operating fluidized beds. Increase in the reaction rate constant associated with the partial pressure of water, k₁, caused a marked increase in conversion. The effect of k₂,-associated with the partial pressure of hydrogen, was not so great, conversion decreasing as k₂ was increased. Inclusion of the water-gas shift reaction when calculating the gas composition in the kinetic rate expression may be of significance in predicting steam conversion by reactor model 3. However, varying the value of K_eq did not have a significant effect.     

现代煤气化技术及其煤种的适应性分析

结合国内外煤气化技术发展现状与趋势,讨论了煤质特性对气化过程的影响及其在不同气化炉型中的适应性。分析表明,煤种的多样性及气化工艺的选择促进了煤气化技术的快速发展,气流床和流化床代替固定床是煤气化技术发展的必然所趋。在充分认识各类煤气化技术优缺点的基础上,应发挥优势,针对煤种选用炉型,开发具有单炉生产能力高、煤种适应性强、气体成分可调等优势的加压气化技术以及可有效利用煤气高温显热的两段或多段式气化技术。