Transformation of the reabsorption characteristics of lignite treated by low and high temperature drying process

Abstract

The reabsorption characteristics of the lignite treated by low and high temperature drying process were addressed in the paper. The information about the moisture form, functional groups, effective water-filled porosities and equilibrium moisture content of the lignite before and after the drying process was investigated using Differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy and a self-made reabsorption device, respectively. The results show that the low drying temperature (140, 190, 230?°C, 10?min, N₂) has little impact on the effective water-filled porosities of the resulted samples, whereas it has a great influence on the main oxygen-containing functional groups, which amount firstly decreases and then increases with the drying temperature increasing. In the case of the lignite samples dried under high-temperature (600, 700, 800?°C, 30?s, N₂), the amount of the effective water-filled porosity of the sample decreases and the amount of oxygen-containing functional groups increases as the temperature increasing. The reabsorption capability of the high temperature dried sample is much lower than that of the sample treated under low drying temperature. The reabsorption characteristics of the low-temperature dried samples are affected by the amount of the oxygen-containing functional groups, while the effective water-filled porosity is main factor for the lignite samples derived from high temperature drying process. Moreover, the work gives a good evidence that the high-temperature drying process is an effective choose for lignite upgrading.     

垦71井区三维VSP资料波场分离方法应用研究

三维VSP资料是多偏移距VSP资料，资料中多种类型的波叠合在一起形成复杂波场。从复杂波场中分离出单一的保幅反射波波场是三维VSP波场分离的重要工作。常规二维VSP波场处理方法单一，难以适用于复杂的三维波场处理。针对三维VSP资料的波场特点，以分离上行反射P波为例，将单一波场分离方法加以适当组合，对垦71井区三维VSP实际资料进行了应用研究。结果表明，波场分离处理中叠加消去法和中值滤波相结合以及F—K滤波和中值滤波相结合的方法克服了单一方法的缺陷，波场处理后获得了波组特征明显、波场清晰单一的上行反射P波保幅波场，取得了较好的波场分离效果。     

High char‐yielding poly[acrylonitrile‐co‐(itaconic acid)‐co‐(methyl acrylate)]: synthesis and properties

Polyacrylonitrile terpolymers of various compositions consisting of acrylonitrile (AN), itaconic acid (IA) and methyl acrylate (MA) were synthesized by solution polymerization in dimethylsulfoxide. Increase in concentration of either IA or MA retarded the overall polymerization rate and the polymer molecular weight. The system consisting of AN + MA and varying IA concentration was more prone to retardation in comparison with the system composed of AN + IA with variable MA concentration. The retardation factors were quantified. Minor quantities of MA boost the reactivity of IA in the terpolymer system. The terpolymer was richer in MA vis‐à‐vis the feed. The thermal characteristics of the terpolymer were examined as a function of its composition. In contrast to the copolymer of AN and IA requiring 1–1.5 mol% IA, the terpolymer required an IA content of approximately 2.5 mol% for optimum thermal stability. The polymer with 90 mol% AN, 2.5 mol% IA and 7.5 mol% MA exhibited reasonably good char‐forming characteristics and thermal stability. The overall crystallinity and crystallite size of the polymers were found to decrease on incorporation of the comonomers. The ‘aromatization index’ of the copolymer increased with the temperature of pyrolysis through re‐organization of the tetrahydropyridine ladder structure. Copyright © 2005 Society of Chemical Industry     

制作矢量轮廓字库

本文介绍了一种如何从常见的点阵字库制作矢量轮廓字库的算法。算法采用了预处理、轮廓跟踪和轮廓逼近这三个主要步骤来制作每一个矢量文字，然后采用一种２字节的索引结构加以存储。     

树脂热解炭制备碳化硅晶须

用自制的配合醛树脂热解和炭源，用ＳＩＯ２超细汾作原，根据碳热还原原理，利用常规加热和微波加热两种方式，分别制备了直径在纳米级的ＳｉＣ晶须，Ｘ射线衍射、透射电检测结果表明：制备工艺和条件对ＳｉＣ晶须的性质有较大的影响。     

Biodesulphurization of Hungarian lignite and sub-bituminous coal

The annual SO₂ emission is approx. 0.6 million tons in Hungary because of the high amount of sulphur in the power plant coals. Since Hungary has signed the European Environmental Agreement, the high sulphur emission has to be gradually reduced. To overcome the acid rain problem, the biodesulphurization of Hungarian power plant coals has also been started in Hungary. The R&D programe of biodesulphurization has been launched in 1990. According to our findings the biodesulphurization process is a suitable tool for reducing the pyritic sulphur content in lignite and sub-bituminous coal.     

煤粉性状对残炭颗粒微结构及其燃烧特性的影响

本文研究了不同粒主工的烟煤和无烟煤经高温气流燃烧后残炭颗粒的形态及孔隙结构，对其燃烧方式和燃尽特性进行了讨论，并比较了两种煤的差别。结果表明，由镜质组形成的残炭表面和内部同时燃烧，并比较了两种煤的差别。结果表明，由镜质组形成的球残炭表面和内部时燃烧，容易燃尽；由惰性组形成的不规则残炭以外部反应为主，较难燃尽，同无烟煤相比，烟煤残炭孔隙多，燃烧剧列，且孔穴内部燃烧所占比重更大。     

Directions for improving manual fire suppression using a physically based computer simulation

The Swedish Fire Research Board and the U.S. Federal Emergency Management Agency are sponsoring a project to further the understanding of the basic mechanisms involved, as well as to support the development of standards for and to seek ways of improving the performance of portable fire suppression systems used by fire departments.This paper describes a physically based computer model developed to simulate one aspect of the problem: the manual suppression of postflashover fires. This includes: (1) an overview of the physical basis behind the model; (2) a comparison of model predictions with available experimental data, and (3) an analysis of fire suppression effectiveness using the model.The analysis concludes that, when direct access and extinguishment of the burning fuel is not possible, improved fire control occurs with water sprays having a Rosin-Rammler distribution of droplet sizes with volume-median-drop diameters in the 0.15 to 0.35 mm range. This agrees with available experimental data. It is also shown that fire fighting venting and standoff distance requirements may lead to more severe fires requiring more water for control; although venting and water spray induced air/gas flow also serve to channel hot steam and gases away from the fire fighter adding to his safety. The analysis also shows that allowing higher gas and surface temperatures at fire control through improved fire fighter protective clothing and equipment design reduces water flow rate requirements. Additional experimental work is recommended before all these conclusions are considered definitive. Reference: L. M. Pietrzak and G. A. Johanson, Directions for Improving Manual Fire Suppression Using a Physically Based Computer Simulation,Fire Technology, Vol. 22, No. 3, August, 1986, p. 184.     

Experimental and numerical simulation of lignite chemical looping gasification with phosphogypsum as oxygen carrier in a fluidized bed

Phosphogypsum (PG) is a solid waste produced in the wet process of producing phosphoric acid.Lignite is a kind of promising chemical raw material.However,the high sulfur of lignite limits the utilization of lig-nite as a resource.Based on fluidized bed experiments,the optimal reaction conditions for the production syngas by lignite chemical looping gasification (CLG) with PG as oxygen carrier were studied.The study found that the optimal reaction temperature should not exceed 1123 K;the mole ratio of water vapor to lignite should be about 0.2;the mole ratio of PG oxygen carrier to lignite should be about 0.6.Meanwhile,commercial software Comsol was used to establish a fuel reaction kinetics model.Through computational fluid dynamics (CFD) numerical simulation,the process of reaction in fluidized bed were well captured.The model was based on a two-fluid model and coupled mass transfer,heat transfer and chemical reac-tions.This study showed that the fluidized bed presents a flow structure in which gas and solid coexist.There was a high temperature zone in the middle and lower parts of the fluidized bed.It could be seen from the results of the flow field simulated that the fluidized bed was beneficial to the progress of the gasification reaction.     

Corrosion of Fe-10Al-Cr alloys by coal char

Corrosion of iron-base alloys at 982°C (1800°F) by coal char is observed and the phase morphologies are discussed. No sulfidation was observed at 50 hr exposure. After 100 hr internal aluminum-rich sulfides were observed along with thick outer scales of iron oxide. The species causing the hightemperature-induced corrosion are probably sulfides and sulfates, present in most coal chars. Possible mechanisms for the corrosion are also discussed.Department of Materials Science and Mineral Engineering.