“干燥无挥基”指标的确立及其在褐煤制半焦中的应用

在阐述煤的工业分析指标及煤质分析基准的基础上,提出了一个新的基准状态——"干燥无挥基",并分析了不同基准之间的换算关系。利用干燥无灰基的组分之和对应收到基褐煤的产率将褐煤分为3个级别,即产率=50%为三级、产率=55%为二级、产率=60%为一级,其对应的产品分别称为三级半焦、二级半焦和一级半焦。最后对各级别褐煤及半焦指标进行了分析,结果表明:干燥无灰基(挥发分+固定碳)=50%时,应将制焦煤质的上限定为收到基(水分+灰分)不大于50%,且单一指标收到基水分上限不大于40%,收到基灰分上限不大于20%;当干燥无灰基(挥发分+固定碳)=55%时,半焦产品的产率为40%～45%;当干燥无灰基(挥发分+固定碳)=60%时,半焦产品的产率为41%～43%。     

生物质和煤基活性炭制备过程的活化特性比较

分别以稻壳、木屑及褐煤为原料用水蒸气活化法制备了活性炭,比较了所得活性炭的吸附性能和炭化料的反应活性,探明了造成不同原料活化特性差异的原因。结果表明,活化过程中生物质原料的反应活性优于褐煤,炭化料的活化速率遵循脱灰稻壳>木材炭化料>稻壳炭化料>褐煤炭化料。通过对炭化料进行元素分析、气化反应活性分析、BET、SEM、XRD、FTIR、XPS等物理和化学性质的表征,揭示了不同原料表现出不同活化特性的原因。结果表明,在相同炭化和活化条件下,原料挥发分越高,灰分越低,炭化料有机含氧量越高,则水蒸气的活化速率越快,更容易在短时间内制备出高性能的活性炭。     

煤炭化过程中结焦压力的产生机理

论述了结焦压力的产生机理,从实际现象到内在本质,深入到炭化过程中煤大分子结构变化、脱挥发分速率、半焦及焦炭结构等多方面探讨了压力产生的来源与主要影响因素,并指出炭化室中心焦炭形成时会产生最大膨胀压力．最后提到了已有的一些鉴别危险结焦煤并预测其可能产生的结焦压力的一些方法．     

内蒙半焦的脱灰工艺研究

选用内蒙褐煤制得的半焦,用酸碱法进行脱灰实验。考察了硝酸浓度和KOH溶液对脱灰效果的影响。结果表明,热的KOH溶液比常温KOH溶液的脱灰效果好;KOH溶液的脱灰能力比HNO3溶液的脱灰能力强;先进行热KOH溶液处理再进行硝酸处理有利于半焦更好地脱灰。对比脱灰前后半焦孔隙结构的变化,发现灰分从23.76%降到9.83%,比表面积由2.10 m2/g增加到27.69 m2/g。     

钙元素对褐煤热解和气化特性的影响

综述了钙元素对褐煤热解和气化特性的影响,讨论了钙元素对热解产物中挥发分、焦油产率和气体产物分布的影响,以及对褐煤半焦气化的催化作用。结果表明,与酸洗煤相比,热解过程中,钙元素降低焦油产率,提高半焦产率;气化过程中,钙元素的植入提高褐煤半焦的反应活性,缩短了反应时间。高温时钙元素主要以氧化态的形式存在,低温时则不断与半焦基体键合而参与交联反应,少部分挥发。     

褐煤新法干馏制取高炉喷吹料和城市煤气初步研究

主要介绍了在１０ｋｇ／ｈ处理量的连续实验装置上进行扎赉诺尔褐煤制取高炉喷吹料和城市煤气研究的初步结果。干馏煤气是中热值煤气，符合城市煤气要求。干馏半焦具有低灰、低硫、低挥发分和高活性等特点，是一种优质的新型高炉喷吹料。     

碱熔融法对褐煤半焦脱灰的研究

半焦是煤在较低温度(低于700℃)下热解的产物,具有相对发达的孔结构,有一定的吸附性能力,但未经改性半焦的吸附能力不及普通活性炭,且灰分含量较高,需要对其进行脱灰处理以提高其性能。本文选用白音华褐煤,在500℃制备半焦,利用碱熔融法对半焦进行脱灰实验。其中着重考察了粒度、碱焦比、反应温度、反应时间以及酸浸条件对脱灰的影响。     

褐煤两步炭化法制炭分子筛

本文针对高挥发分的褐煤原料，提出两步炭化法制炭分子筛概念，并考察了工艺条件和产品空分性能。结果表明，与一步法相比，两步炭化法制炭分子筛具有易成型、粘结剂用量少，炭分子筛强度高和空分性能好等优点。     

胜利褐煤快速热解特性

为考察热解温度对热解产物品质及挥发分残留的影响,在10 kg/h自制褐煤快速热解提质试验设备上,以胜利褐煤为试验原料,考察了400~900℃热解提质温度对热解产物产率、气体产物组成、半焦微观结构以及残余挥发分的影响。结果表明,随着热解温度的升高,半焦产率逐渐降低,气体产率升高,焦油的产率先升高后降低,700℃时焦油产率最大;热解气体中的CO_2随着热解温度的升高逐渐降低,H_2和CO含量随着热解温度的升高而增加;随着热解温度的升高,挥发分不断释放导致半焦含氧官能团以及高活性的小的缩合芳环减少;热解温度≥700℃,半焦残留的挥发分较低,固定碳较多,基本满足电石用焦的要求。     

低阶褐煤制作冶金焦的可行性研究

印尼褐煤具有灰分、硫分低,水分、挥发分、热值高的特点。将印尼褐煤通过一定加工工艺制成冶金焦,可以大幅度提高印尼褐煤的能级利用水平。文章通过煤质分析及针对印尼褐煤制作冶金焦的工艺参数的实验,对印尼褐煤制作冶金焦的可行性进行了深入研究。结果表明,褐煤半焦挥发分残留率、灰分、硫分表现出一定的相关性。通过一定的工艺控制,印尼褐煤可以制作出指标合格的冶金焦。     

Measurement of volatile matter in Victorian brown coal

The effects of using one-stage and two-stage heating, using air-dried coal and coal oven-dried under nitrogen, and using final temperatures of 850°C and 900°C on the measured volatile matter for twelve Victorian brown coals have been examined by the use of a statistically controlled experiment. The repeatability of the two-stage method was found to be significantly better than that of the one-stage method (0.7% abs. compared to 0.9% abs.). The volatile matter of coals at the front of the furnace was found to be significantly different from that of coals at the back of the furnace for the one stage method but not for the two-stage method. A two-stage heating method (7 min at 400°C and then 7 min at 900°C) using oven-dried coal is recommended for the routine determination of volatile matter in brown coal.     

Flash pyrolysis of coals: influence of cations on the devolatilization behaviour of brown coals

The influence of cations on the pyrolysis behaviour of brown coals under flash heating conditions was investigated by means of a small fluidized-bed pyrolyser. A stream of coal particles in nitrogen was injected at rates of 1–3 g coal/h directly into a heated bed of sand fluidized by nitrogen. Yields of tar, C₁–C₃ hydrocarbons and total volatile matter from four Gelliondale brown coals and a Montana lignite were determined as a function of pyrolysis temperature. With all coals the maximum tar yield was obtained at 600 °C. Removal of cations present in the coals markedly increased the yields of tar and total volatile matter, with little effect on the yields of hydrocarbon gases. The converse was also observed in that the addition of Ca²⁺ to a cation-free coal decreased the yields of tar and total volatile matter. The extent of the reduction in tar yield at 600 °C in the presence of cations was found to be similar for all coals. After acid washing, tar yields appear to correlate with the atomic $\text{H}\text{C}$ ratios of the coals in a manner similar to that observed previously with bituminous coals.     

Simulation of the process of coal dust ignition in the presence of metal particles

A mathematical model was developed for the gas-phase ignition of a layer of the dust of typical 2B brown coal by a metal particle heated to high temperatures (above 1100 K) under ideal thermal contact conditions. This model took into account the heating and thermal decomposition of ground coal upon the cooling of a local source, the yield of volatile components, and the formation, heating, and ignition of the gas mixture. The effect of heat source parameters (shape and dimensions) on the fundamental process characteristic—the delay time of ignition—was found. A relationship of the ignition zone position near a hot particle with the heating intensity of a gas mixture of volatile substances and an oxidizing agent was revealed. The results of numerical studies are consistent with well-known experimental data on the conditions and characteristics of ground coal burning on local heating by sources of limited energy capacity.     

生物质型焦生产工艺的研究

用生物质做粘结剂以干法冷压成型生产生物质型煤,再经炭化制得生物质型焦．研究了生物质（玉米秸、稻杆）配入量、成型压力、烟煤种类（气煤、气肥煤、肥煤、焦煤）及配入量对型煤和型焦的抗压强度的影响．实验结果表明,烟煤配入量和成型压力对型焦的抗压强度有显著影响,适宜的工艺条件为生物质配入量１８％,肥煤与无烟煤配比１：２,成型压力４６０ｋＮ．此外,分析了型焦和热解挥发物的组成和性质．     

Some recent advances in the understanding of the pyrolysis and gasification behaviour of Victorian brown coal

The brown coal in the Latrobe Valley, Victoria, Australia, has many unique structural features and properties. The brown coal has a very low ash yield and contains highly dispersed alkali and alkaline earth metallic (AAEM) species, either as carboxylates forming part of its organic matter or as NaCl dissolved in its moisture. Owing to its unique structural features and properties, the brown coal behaves very differently from many other solid fuels such as biomass, bituminous coals and anthracites. For example, the highly reactive nature of its volatiles, the vulnerable nature of its nascent char and the presence of finely distributed AAEM species mean that the volatile–char interactions, a common phenomenon in all gasifiers, especially in the fluidised-bed gasifiers, would influence almost every aspect of its pyrolysis and gasification behaviour. Some recent progress in the understanding of the pyrolysis and gasification behaviour of Victorian brown coal will be reviewed in this paper. After a brief account of the effects of AAEM species on the pyrolysis yields, the factors influencing the volatilisation of AAEM species will be summarised. This will be followed by the discussion of the factors influencing the reactivity of brown coal char and the catalytic reforming/cleaning of volatiles and gasification products by char-supported catalysts. The effects of dewatering/drying on the pyrolysis behaviour of Victorian brown coal and the conversion of pollutant-forming elements will be mentioned briefly. The progress in the fundamental understanding of the pyrolysis and gasification behaviour of Victorian brown coal has laid solid foundation for the further development of advanced gasification technologies for the clean and efficient utilisation of this cheap but important resource.     

煤热解工艺中挥发分除尘技术的现状分析及建议

针对粉煤热解多联产工艺中热解挥发分除尘的技术难题,阐述了热解挥发分所含粉焦及煤灰颗粒的特性、热解工艺对除尘器的要求,对热解挥发分除尘技术的研究现状进行分析并提出建议,认为煤热解工艺中挥发分除尘技术应该从热解工艺本身出发,采用加氢(催化)热解方式,促进热解气中重质焦油组分裂解,使热解产物轻质化,从而降低煤热解挥发分的除尘难度。此外,可以采用多种除尘设备有机组合的方式并辅以分离前对细小粉尘进行预团聚等手段,强化除尘效果、提高煤热解工艺中挥发分的除尘效率。     

水煤浆挥发分热解的FG-DVC模型

采用FG-DVC模型对水煤浆不同升温速率下的热重实验数据进行处理.结果表明,在挥发分析出温度范围内,表观活化能随升温速率升高而减小,DTG曲线峰值随升温速率升高而增大,符合实验数据的规律;模拟结果与实验曲线十分接近,且n=1情况下吻合情况最好,说明用FG-DVC模型描述水煤浆挥发分析出机理比较适合.     

Product composition of the dynamic conversion of brown coal in supercritical water

The product composition of the dynamic conversion of brown coal, which was continuously supplied as a water-coal slurry to a flow reactor at 30 MPa, was studied. The temperature of water and coal particles was increased from room temperature to 400°C (top part of the reactor). The conversion of the organic matter of coal was ～48%, and the products collected at the reactor outlet consisted of solid tar components, substances dissolved and emulsified in water, and volatile substances, whose major constituent was CO₂. The composition of solid tar components and oils was determined.     

Pyrolysis of brown coals. 3. Effect of cation content on the gaseous products containing oxygen from Yallourn coal

A study has been made of the evolution of water, carbon dioxide and carbon monoxide during the pyrolysis of Australian Yallourn brown coal, and of the way in which the evolution is influenced by exchange of the carboxyl groups in the coal with magnesium and barium cations. Virtually all the oxygen in the coal can be removed as carbon dioxide, water and carbon monoxide with the greatest rate of loss occurring at 300, 350 and 500 to 600 °C respectively. Increasing levels of cation alter the proportion of the volatile constituents but not the total amount of volatile matter evolved. Increased evolution of oxygen as carbon dioxide from a magnesium-form coal over that from acid-form coal is accompanied by a decrease in the amount evolved as water and carbon monoxide. Barium-form coals, however, show an increase in the amount of carbon monoxide evolved as the cation content increases. This is due in part to reactions involving the nitrogen gas used to provide a non-oxidizing atmosphere during pyrolysis. These reactions do not occur with magnesium-form coals. The amount of char formed by pyrolysis is the same for different levels of cation exchanged on the carboxyl groups. The results support conclusions that the carboxyl groups in a brown coal are associated with other oxygen groups, and that the mode of decomposition of the groups in this association (including carboxyl) is altered by the exchange of the carboxyl groups with cation.