INVESTIGATION OF THE RELATION BETWEEN CHEMICAL COMPOSITION AND ASH FUSION TEMPERATURES FOR SOKE TURKISH LIGNITES

Abstract

The purpose of this paper was to investigate the relationship between ash composition and ash fusion characteristic temperatures for some Turkish lignites. The lignite samples used are from different areas in Turkey. Regression analysis was used to relate the ash composition to the ash fusion behaviour. The results suggest that the chemical composition has a significant effect on the ash fusion temperatures. To consider Fe₂O₃ as an acidic ash constituent makes the realtionships between the selected ash composition parameters and ash fusion temperatures clearer.     

基于拟三元等温图对宁东粉煤灰高温熔融流动特性的研究

在气流床气化炉的实际运行中,经常需要寻求最优的进料煤调配方案以调控煤灰的熔融流动特性。借助SiO₂-Al₂O₃-AAEM(CaO+MgO+Na₂O+K₂O)拟三元等温图,分析了不同组成的宁东煤灰熔融特性,并结合X-射线衍射(XRD)探究了灰在熔化过程中的矿物质转化规律。发现熔融温度在拟三元等温图中呈现U型分布。当SiO₂、Al₂O₃和AAEM质量分数分别为37.5%、25.0%和37.5%时,灰的熔融温度达到最低,流动温度比宁东煤灰降低40 ℃。对灰熔化过程中矿物质转化分析发现,熔化过程中石英与氧化钙会发生矿物质转化反应生成低熔点的钙黄长石和长石,对其熔化具有明显的促进作用;对灰熔化后形成液态熔渣的黏-温特性曲线分析发现,该比例下灰样品同时具有最低的临界黏性温度(T_CV=1107 ℃)和最低的黏性流动活化能(E_a=282.86 kJ/mol),可有效降低气化炉的操作温度。研究表明,拟三元等温图对于气化原料配煤方案可起到一定的指导作用。     

石油焦中钒和镍对高铁煤灰渣黏-温特性的影响

高硫石油焦与煤气流床共气化是其高效洁净利用的可行途径,气化灰渣的黏-温特性决定着气化炉的稳定运行,石油焦灰富含的V和Ni可引起共气化灰渣的黏-温特性变化,然而石油焦中的V和Ni对高铁煤灰黏-温特性的影响尚不清楚。选择一种高铁的气化煤灰,通过添加V₂O₅和NiO研究了V和Ni对高铁煤灰渣黏-温特性的影响规律。结果表明：随着V₂O₅和NiO添加量的增加,全液相的灰渣黏度呈降低趋势,降温过程中V与Al、Fe形成了尖晶石,导致灰渣黏度急剧增加,使灰渣黏-温特征曲线逐渐趋向结晶渣,导致气化炉可操作温度范围变窄;灰渣中Fe更易与V形成尖晶石(FeV₂O₄)晶体析出,Fe可促进灰渣中Ni还原为金属Ni, Ni与Fe团聚形成合金小球析出,并起到非均相晶核作用,促进尖晶石在其表面析出;V和Ni均可导致FeO以固相析出,进而使降温过程中液相渣的黏度增加,这也使含V和Ni的高铁煤灰渣黏度随着温度降低时的增加速率比高钙灰渣更快。     

化学链气化过程中昭通褐煤灰对锰矿石载氧体的影响

为探究化学链气化过程中煤灰及其组分对锰矿石载氧体的影响及作用机理,制备了昭通褐煤煤灰,以煤灰中主要组分Fe₂O₃、CaO和MgO等氧化物颗粒配制单一及混合组分的模拟煤灰,在高温流化床反应器中以水蒸气为气化剂进行了系列研究。结果表明：添加5%(质量分数)褐煤煤灰后,合成气产量升高而碳转化率降低,且随着煤灰添加量的继续增多,合成气产量呈先降低后升高趋势,而碳转化率则呈现先升高后降低趋势,在煤灰添加质量分数为15%时,出现最高的碳转化率79.7%和最低的合成气产量0.702 L。Fe₂O₃组分明显提高了碳转化率和合成气产量;CaO与Mn₂O₃高温反应生成了Ca₂Mn₂O₅,提高了载氧体选择性,使得合成气产量增大;MgO显著降低了碳转化率和合成气产量。双组分及MgO-Fe₂O₃-CaO三组分模拟煤灰的研究发现,MgO对气化反应进程抑制作用强于Fe₂O₃和CaO的促进作用,相比于Fe₂O₃-MgO双组分模拟煤灰,CaO-MgO模拟煤灰对载氧体气化活性的抑制作用影响最大。     

TWO STAGE DIRECT COAL GASIFICATION TO C2-C4 HYDROCARBONS

Results of a study conducted to convert coal to C₂-C₄ hydrocarbons in a two-stage reactor system are presented. Coal was converted to liquids at 440° C in a stirred batch autoclave using tetralin as the hydrogen donor solvent. The liquids produced were separated from the unreacted coal and ash by filtration. The liquids were then fed into a second stage fixed bed reactor containing sulfided Ni-M0/AI₂O₃ and Si0₂-AbO;5 catalyst. The liquids were hydrocracked on the dual-functional catalyst giving high yields of C₂-C₄ hydrocarbons. The pressure was 1800 psig and the temperatures were in the range of 425 to 500° C. Reaction mechanisms of conversion of coal derived liquids to C₂-C₄ hydrocarbons are presented. The kinetic parameters of the conversion of coal liquids to gases were determined. The activation energy was determined to be 23.9 Kcal/mol Cracking reactions involving C-C bonds appear to be rate-controlling.     

KINETICS OF CORN COB CHAR GASIFICATION IN CARBON DIOXIDE

The Reactivity of corn cob char in CO₂ has been studied on a thermogravimetric balance to develop a rate equation for the design of biomass gasifiers operating on corn cob char. Experiments in the range of 650-1000^°C were conducted with cylindrical shaped pellets of 1 cm diameter having L/D=l. The average porosity of the pellets was 0.5. It was observed that the rate of the CO₂/char reaction decreased with increase in temperature from 650-750^°C and then increased with temperature upto 1000^°C.

The data obtained at temperatures 750^°C and above has been used to determine a rate equation for char gasification. It has been found that the reaction proceeds according to the Sharp Interface Model (SIM) with a first order chemical reaction as the rate controlling step. The activation energy is found to be 40 Kcal/mole with frequency factor being 1.2 × 10⁷ mm/sec. Analysis of the data obtained for the decreasing reaction rate regime (650-750^°C) indicates that the change in the ash structure result in this kind of behavior.     

降低石油焦灰分的措施研究

根据高灰分石油焦的特性及应用领域,研究了降低石油焦灰分的措施。分析结果显示,石油焦灰分中的主要元素为O,Ca,S,Fe,Ni,Si,Mn等,金属和非金属元素对石油焦灰分的总贡献比例分别约为43%和57%。X射线衍射分析结果表明,在原油中Ca含量较高的情况下,石油焦灰分中的物质大都以金属氧化物的形态存在,尤其以结构较稳定的CaSO₄和CaO的比例为最高,两种含钙化合物在灰分中合计占比约为90%。对高钙原油实施脱钙处理,可以明显降低延迟焦化焦炭的灰分,且可减小CaSO₄和CaO在灰分中的占比。对原油进行深度脱钙后,原油钙含量与延迟焦化石油焦的灰分对应关系的研究结果表明,石油焦灰分与原油中钙含量之间大体呈线性关系。此结论可为石油焦的生产和销售提供一定的参考。     

KINETIC INVESTIGATION OF METHYLCYCLOPENTANE REFORMING ON FRESH AND DEACTIVATING Pt/Al2O3 CATALYST

The conversion of methylcyclopentane (MCP) in hydrogen on fresh and deactivating Pt/Al₂O₃ catalyst to hydrogenolysis products (2-methylpentane, 3-methylpentane and n-hexane), cyclohexane and benzene was studied in a Berty CSTR at various partial pressures of MCP and H₂, and at a total pressure of 1 atm. For the kinetic studies, temperatures between 370 - 400° and W/F values up to 0.33 g min/cm³ were used. The conversion of MCP was found to increase with increase in temperature at all the MCP partial pressures investigated. The hydrogenolysis products and benzene composition generally increased with increase in temperature and W/F. The mechanism for the reforming of MCP was similar to that proposed by Dartigues et al. (1978) except that the formation of hydrogenolysis products was accounted for in this formulation. Eleven rate models were developed and tested and six satisfied the set criteria. Since hydrogenation/dehydrogenation and desorption steps are relatively rapid, the conversion step to hydrogenolysis products was deemed the only rate determining step with an activation energy of 36.31 kcal/gmol. For the deactivation studies, the model of Corella and Asua (1982) was used for the development of two deactivation models. The only model found to predict the deactivation behavior was the step leading to the formation of the coke precursor as rate controlling.     

CHARACTERIZATION OF KUWAITI CRUDE TBF-FRACTIONS WITH EMPHASIS ON KINEMATIC VISCOSITY - TEMPERATURE BEHAVIOR

Characterization of Kuwaiti crude oil, has been carried out in terms o API gravity, debutanized gravity, total sulfur content, Reid Vapor pressure ash content, heating value, salt content, viscosity SUS, vanadium content a: V2 O5, pour point and analysis of various metals. The true boiling poinl (TBP) fractions of this crude (IBP - 95^° C, 95 - 205^°C, 205 - 260^° C, 260 - 345^° C and 455^° C⁺;) were also characterized in terms of API gravity, total sulfui content, H₂S content, mercaptans content, molecular weight and elementa analyses for total carbon, hydrogen and nitrogen. The kinematic viscosity temperature data have been obtained for 95^°C⁺; TBP fractions for a wide range of temperatures.     

塔里木盆地塔中地区下奥陶统白云岩的成岩流体演化:来自团簇同位素的证据

基于碳酸根中¹³C-¹⁸O键的相对丰度与温度的关系,碳酸盐团簇同位素（Δ₄₇）具有独特的温度指示特征,而且不受碳酸盐沉淀时流体的化学和同位素组成的影响,是成岩流体研究中很好的温度指标。应用该指标可以更好地解决与温度相关的成岩流体来源及演化的问题。论文主要针对塔里木盆地塔中地区下奥陶统鹰山组白云岩样品,在详细的岩矿观察基础上,选取了基质（孔隙发育处）、孔洞内充填物和裂缝内充填物进行了团簇同位素测试分析,解析了深层-超深层碳酸盐岩储层的流体性质、演化与其对储层发育的影响。测试结果表明,塔中地区下奥陶统鹰山组白云岩主要经历了3期成岩流体改造：第一期流体为浅-中埋藏,为粉晶-细晶结构,团簇同位素形成温度T（Δ₄₇）分布范围为69~94℃,流体氧同位素值（δ¹⁸O_w,SMOW）分布范围为+1.81‰~+5.19‰,为奥陶系改造海水;第二期流体为晚期深埋藏卤水,多表现为细晶与中-粗晶结构,T（Δ₄₇）为111~113℃,δ¹⁸O_w（SMOW）值为+8.46‰~+8.95‰,指示进一步增加的水-岩相互作用;第三期为热流体,T（Δ₄₇）为130~147℃,δ¹⁸O_w（SMOW）值为+7.93‰~+9.42‰,矿物氧同位素较第二期明显偏负,且鞍状白云石发育。孔洞和裂缝内充填碳酸盐岩的碳、氧同位素分布范围较宽,δ¹⁸O_carb（VPDB）值为-17.38 ‰~-5.84‰,δ¹³C_carb（VPDB）值为-3.57‰~-1.33‰,也揭示了多期次流体活动的叠加改造。岩心和显微观测结果显示,白云岩具有很好的储集空间,埋藏溶蚀作用和断裂带附近的热流体活动叠加是鹰山组白云岩储层发育的主要建设性成岩作用。     

新型抗高温粉煤灰低密度水泥浆

针对目前粉煤灰低密度水泥浆体系高温下沉降稳定性差及顶部水泥石抗压强度发展缓慢等问题,测试了在中高温条件下粉煤灰、微硅类稳定剂加量对水泥石强度的影响,实验发现微硅类稳定剂在高温条件下(≥125℃)会阻止粉煤灰水泥浆抗压强度正常发展。通过研究出一种新型高温增强剂,保证了粉煤灰低密度水泥浆体系的高温稳定性,并解决了目前粉煤灰低密度水泥浆体系存在的高温强度发展异常、强度很低等问题,最后开发出一套密度为1.50~1.60 g/cm3的粉煤灰低密度水泥浆体系。该体系具有沉降稳定性好、API失水量小、稠化时间可调等性能,水泥石抗压强度较高且顶部抗压强度发展良好,130℃下静胶凝强度的过渡时间为18 min,能够满足85~130℃的大温差高温固井。     

DEMINERALIZATION OF PETROLEUM COKES AND FLY ASH SAMPLES OBTAINED FROM THE UPGRADING OF ATHABASCA OIL SANDS BITUMEN

Ash reduction of the cokes and fly ash samples derived from the Athabasca oil sands bitumen was attempted by dissolving the mineral matter in acids. The samples used for this investigation included Syncrude fluid coking coke, Suncor delayed coking coke and the two fly ash samples obtained from the combustion of these cokes. All samples were analyzed for C,H,N,0 and S before and after acid demineralization and the analyses results compared. Further, the ash from the samples before and after acid demineralization was analyzed for silica, alumina, iron, titanium, nickel and vanadium to assess the acid leaching of these elements. CP/ MAS, ¹³C NMR spectroscopic study of the demineralized coke and fly ash samples was also attempted     

INFLUENCE OF TEMPERATURE AND SOLVENT ON THE PRECIPITATION OF ASPHALTENES

Asphaltenes has been precipitated from a Kuwait flash residue using different n-alkanes (n-C5 to n-C8) at various temperatures ranging from 4^°C to reflux temperatures of the used precipitants. Structures in the asphaltene fractions has been revealed using U.V. fluorescence spectroscopy, elemental analysis and to some extent 1H-nmr. These analysis shows that asphaltenes precipitated in the same amount but at different temperature and with different solvents have merely the same composition. For all n-alkanes the curves of precipitated amount versus temperature show maxima at about 25^°C, implying a shift in the solubility of the asphaltenes.The impact of alkane chain length on the aggregation of asphaltenes through hydrogen bonds is discussed using the alkane-alcohol system as a model. The asphaltene solubility is discussed with the help of the Scatchard-Hildebrand equation.     

减氧对空气泡沫驱井下管柱的缓蚀作用及减氧界限

氧腐蚀是限制空气泡沫驱油技术应用推广的主要因素，减氧能够降低腐蚀速率。笔者利用高压腐蚀反应釜模拟工况条件，采用失重法测试了N80套管钢在不同氧含量（2%~21%）、不同压力（20~50 MPa）、不同温度（70~120℃）条件下的腐蚀速率，根据测试结果拟合建立了腐蚀速率与氧分压关系的数学模型；采用扫描电镜、能谱仪和X射线衍射分析表征了腐蚀产物的微观形貌和成分。结果表明，空气泡沫驱过程中N80钢的腐蚀速率随空气氧含量的降低呈非线性下降，但无法将腐蚀速率控制在0.076 mm/a标准以下。温度120℃、压力50~20 MPa，N80钢标准挂片的减氧界限为0.021%~0.054%，已经达到纯氮气的标准。工况条件下不同氧含量的N80钢材腐蚀产物疏松多孔，其成分为Fe₂O₃、FeOOH和Fe₃O₄，腐蚀产物对基体金属无保护作用，工况的改变并不会显著改变腐蚀产物的形貌和成分。     

CHARACTERIZATION of ARAB MEDIUM CRUDE FRACTIONS WITH EMPHASIS ON KINEMATIC VISCOSITY - TEMPERATURE BEHAVIOR

Characterization of Arab medium Crude Oil, has been carried out in terms of API gravity, debutanized crude gravity, total sulfur content, Reid vapour pressure ash content, heating value, salt content, viscosity SUS, vanadium content as V₂O₅, pour point and analysis of various metals. Further, six true boiling point (TBP) fractions (IBP-95^°C, 95-205^°C, 205-260^°C, 260-345^°C, 345-455^°C and 455^°C+) of this crude were characterized in terms of API gravity, total sulfur contents H2S content, mercaptons content, molecular weight, elemental analyse; for total carbon, hydrogen and nitrogen, analyses of various metals and paraffin, aromatic and naphthene contents of lighter fractions. The kinematic viscosity-temperature data have been obtained for 95^°C+ TBP fractions for a wide range of temperatures.     

四川盆地龙马溪组页岩的CH4和CO2气体高压吸附特征及控制因素

通过对四川盆地重庆地区下志留统龙马溪组的钻井岩心和野外露头等进行分析,利用高压吸附仪分析了页岩中CH₄、CO₂气体的吸附性能,并采用N₂吸附法、CO₂吸附法、场发射扫描电子显微镜(FE_SEM)和X-射线衍射(XRD)等技术,从孔隙结构、有机碳含量、矿物成分、温度和单位压力变化等方面探讨页岩吸附能力的影响关系。研究表明,龙马溪组页岩CH₄、CO₂吸附曲线具有Ⅰ型等温线特征,用Langmuir模型回归等温线能较好地拟合实验数据;页岩的总孔体积、比表面积与饱和吸附量体现良好的线性相关关系,且正相关;页岩有机质和矿物成分通过控制着微米_纳米级孔隙的相对丰度影响着气体的吸附和储存,微孔、中孔孔体积及孔隙度均随总有机碳含量(TOC)值增加而增大;TOC值越大,页岩的饱和吸附量就越大,二者具有良好的正相关性;吸附气量与黏土矿物含量呈正线性相关,与脆性矿物含量呈现相反的变化规律。温度升高会加快气体解吸速度,降低吸附量;此外,页岩对CO₂吸附能力高于CH₄。     

油页岩干馏残渣流化床燃烧过程中污染物排放控制特性

在一台小型鼓泡流化床燃烧实验台上,考察抚顺油页岩干馏残渣污染物排放特性;同时采用炉内石灰石脱硫技术和天然气再燃脱氮技术,考察石灰石添加量对油页岩干馏残渣脱硫效率和燃烧稳定性的影响,以及天然气再燃对脱氮效率和飞灰未燃碳含量的影响。结果表明：随着流化床床温的升高,SO₂和NO质量浓度均单调增加;当床温为800、850和900 ℃时,其Ca/S摩尔比临界值分别约为1.15、1.30和1.20;若Ca/S摩尔比小于临界值,则炉内脱硫反应为放热过程,石灰石的加入有助于提高炉内燃烧稳定性。此外,在流化床内采用天然气再燃脱氮在技术上是可行的,脱氮效率随再燃区温度、天然气再燃比和再燃区停留时间的增加而提高,且对飞灰未燃碳含量影响较小。     

SOLVENT EXTRACTION OF PAKISTANI COALS (ii): EXTRACTION AND CHARACTERIZATION OF METHANOL-BENZENE EXTRACTS

Structural characterization of the solvent extracts from four different Pakistani lignitic coals has been carried out by their proximate, elemental analysis and FT-Infrared and ¹H n.m.r. spectra. The yield of each extracts was greater with 1:1 benzene-methanol mixture in comparison to the total yield obtained by separate extractions with benzene and methanol. The extracts contained significantly less amount of ash and fixed carbon along with an increase in the percentage of volatile matter. The FTIR and ¹H n.m.r. spectra indicated that basically all the extracts contained less condensed aromatic rings in comparison to the coal. The FTIR spectra showed sharp well resolved peaks which have been assigned to various functional groups.

The ¹H n.m.r. spectra were used to obtain average structural parameters for all the extracts. A detailed analysis of the FTIR and n.m.r. spectra of the coal and their extracts provided an important in-sight into the differences between various extracts and also between various coals and their corresponding extracts.     

UNUSUAL RETROGRADE CONDENSATION AND ASPHALTENE PRECIPITATION IN A MODEL HEAVY OIL SYSTEM

A partial phase diagram for the system athabasca bitumen vacuum bottoms (ABVB) (24.6 wt% / 2 mole % ) + dodecane (73.8 wt. % / 47 mole % ) + hydrogen (1.6 wt % / 51 mole % ) was constructed in the temperature range 425 K to 725 K and the pressure range 2 MPa to 7 MPa using an X-ray view cell apparatus. This fluid system is shown to exhibit two phase L₁V and three phase L₁ L₂ V phase behaviour over parts of this P-T region. The shape of the low temperature boundary between the L₁V and L₁ L₂ V zones is characteristic of dilute asymmetric mixtures where a heavy liquid phase, L₂ appears then disappears within the light liquid phase L₁ on isothermal compression. Such phase behaviour is referred to as unusual retrograde condensation and is of both practical and theoretical interest. Transitions between the multiphase regions were found to be reversible at temperatures less than 660 K., in all cases. At higher temperatures irreversible “ asphaltene precipitation” arose within the L₂ phase “ Asphaltene precipitation” did not arise in the absence of the L₂ phase, i.e.: within the L₁ V region, even at temperatures in excess of 700 K. These data provide a strong link between “ asphaltene precipitation” and multiphase behaviour, and demonstrate a physical rather than kinetic basis for asphaltene precipitation at elevated temperatures     

燃油加热炉熔灰腐蚀研究进展

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