Light aromatics from the hydropyrolysis of coal

The hydropyrolysis of British coals was studied at hydrogen pressures of 5–15 MPa using heating rates of up to 30 K s^?1. In a single-stage reactor, hydropyrolysis of a high-volatile coal gave a maximum yield of 4.5 Wt % of single-ring aromatics. The results suggested that the evolution of volatiles and their cracking to benzene, toluene and xylenes were sequential reactions. This was confirmed using a two-stage reactor in which the coal was heated in one zone and the volatiles cracked in a separate, isothermally heated zone. Yields of up to 12 wt % benzene were then obtained from a high-volatile bituminous coal in hydrogen at 15 MPa, both the cracking temperature and the vapour residence time being separately optimized. Hydropyrolysis of model compounds showed that benzene was a major product of the cracking of polynuclear aromatics under hydrogen pressure.     

Pore distribution in high-volatile bituminous coal: An e.p.r. study using nitroxide spin labels

Nitroxide spin labels of different size were diffused into high-volatile bituminous coal from the Mary Lee and Black Creek Coal seams of Alabama in an effort to study the relative pore size and number distributions. The nitrogen coupling in the principal z direction of the incorporated spin label exhibits a temperature dependence above 250 K that is largely a result of librational motion of the nitroxide moiety about an N-C bond. Below 250 K, the temperature dependence of the nitrogen coupling behaves in the same manner as found for spin labels in solids that exhibit a hydrogen bond equilibrium at low temperatures. The distribution of pore sizes differs considerably between the Mary Lee and Black Creek coals. Similar studies of selected coal samples from the Penn State coal sample bank indicate that the spin-label doping method proposed is not applicable to all types of coal; however, it can be used to study selected samples of high-volatile bituminous coal.     

On “partial” coal conversion by extraction with supercritical H2O

This paper presents the results of an exploratory study in which two Western Canadian coals — both furnishing unusually low tar yields by Fischer assays — were extracted with supercritical water at 400–425°C/14–24.5 MPa. In some experiments, CO was used to generate “external” hydrogen for stabilization of coal radicals by the shift reaction; and in others, the effect of a disposable iron catalyst on conversion was examined. Also reported are some observations on the effect of coal pretreatment — specifically: acid leaching, ion exchange against Na⁺, and preheating — on conversion.Data for a Saskatchewan lignite and an Alberta high-volatile bituminous (hvb) coal show that total conversion (to toluene-soluble primary liquids, co-produced water and gas) can range as high as 50 and 35 wt%, respectively, of the d.a.f. coal; that extraction proceeds to virtual completion within 10 min; and that conversion yields can be substantially enhanced by Fe-based catalysts which also allow operation at lower system-pressures than would otherwise required.     

烟煤和白煤结构表征及煤净洁添加剂的研制

运用远红外傅立叶变换光谱、超导核磁、光栅发射光谱、元素分析、X射线荧光光谱等分析测试手段,对烟煤和白煤的基本结构单元进行了表征。研究表明,白煤骨架中的芳环聚合度比烟煤大,碳支链较烟煤少;而且在白煤骨架中部分三维碳骨架中可能存在C—O—Si—O—C化学键。研制出了型煤净洁剂,将其与白煤粉、烟煤粉进行拌合,冷压后制成的型煤着火点降低,燃烧速度加快,不仅燃煤效率提高了20%,而且消烟除尘效果已达排放标准,有害气体二氧化硫降低了48%。     

Reaction of coal with nitrogen in a microwave discharge

In a microwave discharge in nitrogen, high-volatile bituminous coal produces gaseous products, namely hydrogen cyanide, acetylene, small amounts of cyanogen and lowmolecular-weight hydrocarbon gases, and nitrogen-containing compounds, in addition to the usual hydrogen and carbon oxides. The reaction of coal in the nitrogen discharge occurs in two stages: interaction of active nitrogen with the coal molecule to cause rapid volatilization of gaseous products, and slow gasification of residual char by active nitrogen. Various factors influencing product type, yield, and distribution are examined. Under conditions where the gaseous products can be quickly quenched or removed, as by trapping at a very low temperature, more than 42% of carbon in the coal can be converted mainly to hydrogen cyanide and acetylene, which together constitute about 90% of the total products.     

Organic emissions in coal combustion in relation to coal structure and combustion temperature

The pulsed combustion of coal has been studied in a small fluidized-bed reactor. The effect of combustion temperature and coal rank on the organic composition of the off-gas was investigated. Results are presented for the combustion of an anthracite, a medium-volatile bituminous coal and a high-volatile bituminous coal at 700, 800 and 900°C. The analytical techniques used include on-line FT-i.r., O₂ monitoring, FID and off-line g.c.-m.s. using Tenax as adsorbent. About 120 hydrocarbons were found, of which over 80% have been identified. Overall combustion characteristics such as oxygen consumption, total amount of unburned hydrocarbons and swelling properties of the coal have been related to the composition of the organic substances in the off-gas. The distribution of the polycyclic aromatics, from benzene to chrysene, and of alkylated derivatives is discussed in detail. Oxygen-containing compounds have also been analysed, although detailed discussion would be premature.     

Fate of coal nitrogen during combustion

A total of 21 coals covering all ranks have been burned under a wide variety of conditions to ascertain the impact of coal properties on the fate of fuel nitrogen. Fuel NO was identified with a nitrogen-free oxidant consisting of Ar-O₂CO₂. In general, under fuel-lean conditions fuel NO formation increases with increasing fuel nitrogen content; however, other fuel properties also significantly affect the fate of fuel-bound nitrogen during combustion. In particular, fuel nitrogen conversion appears to be greater with coals containing a high fraction of volatile reactive nitrogen. Under fuel-rich conditions measurements of first-stage and exhaust-species concentrations suggest that the optimum stoichiometry for minimum emissions is a function of fuel composition. As first-stage stoichiometry is decreased, the NO formed in the first stage decreases, but other oxidizable gas nitrogen species increase as does nitrogen retention in the char. Total fixed nitrogen generally increases with increasing fuel nitrogen and correlates well with excess air exhaust emissions. The distribution of the total fixed nitrogen species leaving the first stage is strongly dependent upon the coal composition. Of the 12 coals tested in detail, only 1 (the high-volatile B bituminous from Utah) produced high HCN concentrations. The low-volatile Pennsylvania anthracite formed almost no HCN or NH₃ even under extremely fuel-rich conditions. In general, the first stage NO percentage decreased significantly with decreasing coal rank from anthracite to lignite. Conversely, the relative importance of NH₃ grew with decreasing rank. HCN was greater than NH₃ in all bituminous tests, but less than NH₃ with all subbituminous and lignite coals.     

流化床煤燃烧过程不同气氛下的气态氮释放特征

利用微型流化床反应装置,结合快速过程质谱仪,在850~940℃操作温度下,研究了三种不同粒度分布烟煤和无烟煤在热解、气化和燃烧反应条件下四种主要气态氮产物HCN、NH₃、NO和NO₂的释放规律。结果表明,微型流化床可以实时检测挥发分氮和焦炭氮的动态释放序和类型,热解、气化和燃烧反应气氛的改变主要影响HCN和NH₃的释放量。热解产物的气态氮主要是来自于挥发分,燃烧反应的HCN和NH₃的释放量与温度有明显关系,而气化反应的各类气态氮释放量随温度变化波动不大。煤颗粒尺寸和温度变化对烟煤和无烟煤中各类气态氮释放量产生影响比较复杂,其中NH₃的释放特性是区分挥发分N释放和半焦N释放的重要特征。     

Application of XPS to coal characterization

The use of X-ray photoelectron spectroscopy to probe the chemistry of coal surfaces is reviewed and its application to the functional group composition of bulk coals is discussed. The surface composition of a range of 19 coals (anthracite to brown coal), ground under heptane, was measured and compared with the results of bulk analysis. A good correlation was obtained for oxygen, with the bituminous and higher-rank coals showing surface enrichment in oxygen. The surface bulk correlation was less good for sulphur, nitrogen and chlorine and was poor for silicon, aluminium and iron. Silicon and aluminium are enriched at the surface while iron is surface deplected. These effects are either due to different particlesize distributions of the mineral and organic phases or to the mechanism of fracture in heptane preferentially exposing specific components of the coal. Oxidation and carbonization of a bituminous coal were also investigated. Oxidation was seen to occur initially via the exterior surface, producing a distribution of carbon—oxygen groups. Singly-bonded species predominate at all temperatures, stable carboxyl groups forming in significant proportions only at temperatures > 250 °C. Carbonization was seen to result in the formation of ether linkages by condensation of hydroxyl groups.     

烘焙稻壳与不同煤化程度的煤共热解特性

稻壳在250 ℃/30 min条件下烘焙后,与无烟煤、烟煤和褐煤3种不同煤化程度煤进行不同比例的混合,混合物分别进行热重分析和高温共热解特性研究。结果表明：热重分析中,添加烘焙稻壳有利于提高无烟煤和烟煤的转化率,其提高率低于5%,但是不利于提高褐煤的转化率;高温共热解实验中,随着烘焙稻壳添加比例的提高,无烟煤和烟煤与烘焙稻壳共热解固体产物减少,气体产物增加,而褐煤与烘焙稻壳共热解固体产量增加,气体产量略有下降;烘焙稻壳的添加有利于共热解产气中H2组分的增加和CO2组分的减少,通过改变烘焙稻壳在混合物中的比例可以对共热解气体组分进行调节。     

Current status of the hydrogenation of coals

The theoretical and experimental studies carried out at the Institute for Fossil Fuels during recent years in the modernization of hydrogenation technologies for coal conversion into a liquid fuel under low hydrogen pressure (10 MPa for bituminous coals and 6 MPa for a number of brown coals) are surveyed. These studies are based on the advances of catalysis science and on the current concepts of the hydrogenation of organic compounds and coal multimer. The capacity and cost efficiency of a coal chemical enterprise in the commercialization of the technology are substantiated.     

典型煤炭燃料在民用解耦炉中的燃烧实验研究

实验对比研究了烟煤块状半焦及烟煤型煤等煤炭燃料在民用解耦炉中燃烧时的污染物排放特性和炊事能力,并基于解耦测试炉对烟煤型煤的特征尺寸进行优化,验证了解耦炉具对不同种类民用煤炭燃料的适应性。结果表明,民用解耦燃煤炉具特有的结构特征和通风方式有利于NOx和CO的同时减排。若在解耦炉中燃烧烟煤洁净型煤,可进一步实现对SO2和颗粒物(PM)的有效控制。型煤尺寸对炉具污染物排放影响显著,尺寸优化后的烟煤洁净型煤在解耦炉中稳定燃烧时NO, SO2, CO和PM的平均排放浓度按基准氧含量9vol%折算后,分别低于190, 300, 380和30 mg/m3,炊事功率可达1.65 kW。     

Use of heavy oils (and derivatives) to process coal

Oil sands bitumen from the Athabasca and Cold Lake deposits, Lloydminster heavy oil and various liquid derivatives from oil sands bitumen can be successfully employed to solubilize an Alberta high-volatile C bituminous coal. In the presence of hydrogen, the degree of coal solvation is increased; catalytic hydrogenation is even more effective and gives higher yields of soluble products.     

半焦-烟煤混燃特性及动力学分析

掺烧烟煤是解决低挥发分热解半焦着火难、燃尽差的一种有效方法。采用热重实验研究了半焦、无烟煤与烟煤混燃特性的差别,分析了混燃过程中的交互作用和反应动力学。结果表明：陕煤半焦的燃烧过程分为可燃质的燃烧和CaCO₃的分解两个阶段。半焦-烟煤混烧的主失重峰靠近燃料比接近的单燃料的DTG峰。半焦-烟煤混合燃料较无烟煤-烟煤混合燃料的综合燃烧特性更优。掺混烟煤比例越高,混燃的表观活化能越低,可燃性和综合燃烧特性越好。烟煤与半焦或无烟煤混燃过程中存在一定的交互作用,且无烟煤-烟煤的交互作用较半焦-烟煤更显著。可燃性指数和综合燃烧指数与燃料比呈负线性相关性,表观活化能E与燃料比呈正线性相关性。     

Reaction of fluorine gas with coal and the aromaticity of coal

Molecular fluorine has been used for the study of coal and a small number of model compounds. It is shown that direct estimates can be made of the carbon aromaticity and of the sensitive carbon in cyclic form. The value for a high-volatile Illinois bituminous coal agrees well with that commonly accepted on the aromatic/aliphatic structural hypothesis and suggests that the polyamantane model is unsatisfactory. The reagent also results in removal of nitrogen and sulphur from coal.     

钙基添加剂对不同煤种解耦燃烧下硫释放的影响

煤燃烧后排放的硫氧化物导致的环境污染问题已经引起人们的日益关注。基于一段式和两段式卧式炉,本文探究在传统燃烧和解耦燃烧条件下,温度、煤种以及CaO对燃煤释放SO₂规律的影响。试验结果表明：不同煤种的SO₂释放规律存在差异。随着温度的升高,不同煤种燃烧SO₂的释放量均不断增加,硫的动态析出曲线逐渐由单峰分布转化为双峰分布。传统燃烧模式下,添加的CaO对烟煤、无烟煤和褐煤脱硫效率可以达到70%以上,高氯煤脱硫效率则较低,仅有12.09%～20.45%;随温度升高,烟煤、褐煤和高氯煤的脱硫效率呈现先略微下降,后升高再下降的趋势,烟煤脱硫效率则逐渐降低。解耦燃烧模式下,CaO对烟煤、无烟煤脱硫效率在42.35%～76.23%,褐煤在21.35%～52.63%,高氯煤脱硫效率仍然较低,在8.93%～10.57%;随温度升高,烟煤、褐煤和高氯煤的脱硫效率呈现先增加后降低的趋势,烟煤脱硫效率逐渐降低。解耦燃烧模式下,不同煤种SO₂的总释放量大于传统燃烧模式,添加CaO后脱硫效率小于传统燃烧模式。     

无烟煤配煤炼焦试验研究

简述了无烟煤配煤炼焦的意义、要求及对焦炭质量的影响,介绍了涟钢配无烟煤炼焦的试验研究,重点介绍了40kg小焦炉配无烟煤试验,包括试验步骤及条件,并进行了试验结果分析评价。在涟钢现有烟煤煤源的基础上,配入3%￣5%的无烟煤炼焦是可行的,具有较好的经济效益。     

Relative reactivity of hydrogen donor solvent in coal liquefaction

Hydrogen transfer from donor solvent to coal must involve reactions such as hydrogen donation to free radicals and hydrogenation of aromatic structures. The relative reactivities of five typical hydrogen donor solvents, more reactive than tetralin, were determined using a competing elimination reaction in the liquefaction of a bituminous coal at 400 °C and a brown coal at 350 °C. 9,10-Dihydroanthracene, 9,10-dihydrophenanthrene and 1,2,3,4-tetrahydroquinoline exhibited outstanding hydrogen donating ability. Further, the relative reactivities of five mild hydrogen donor solvents such as acenaphthene and indan were determined by a similar elimination reaction using a bituminous coal at 450 °C.     

Micrinite and exudatinite in some Australian coals,and their relation to the generation of petroleum

The occurrence and microscopic features of micrinite and exudatinite in some Australian coals are reported. The origin of these macerals and also the significance of their occurrence are discussed in connection with hydrocarbon genesis. In Australia, micrinite occurs in bituminous and sub-bituminous coals which are very rich in inertinite, and also in brown coal rich in inertinite. One of the possible progenitors of micrinite is oxidized porigelinite. There is little reason to conclude that micrinite was formed from resinite and other macerals at an early stage of coalification and that liquid hydrocarbons were formed during this process. Exudatinite occurs in sub-bituminous and high-volatile bituminous coals in the Gippsland Basin. There is no positive evidence of a genetic relation between liquid hydrocarbons, exudatinite, micrinite and liptinite macerals. The formation of liquid hydrocarbons from solid liptinite etc. may take place just before and during Teichmüller's so-called ‘2nd coalification jump’.     

原料煤粒度对型煤性能的影响

阐述了采用不同成型工艺和使用不同变质程度煤成型时,原料煤粒度对型煤强度的影响。无粘结剂高压成型时,随着煤的粒度的减小,型煤强度增大;有粘结剂低压成型时,无烟煤和烟煤的粒度可适当偏大,褐煤要保持较小的成型粒度。粒度分布对于型煤强度的影响较大。