Characterization of Chinese, American and Estonian oil shale semicokes and their sorptive potential

The primary byproduct of current oil shale oil extraction processes is semicoke. Its landfill deposition presents a potential threat to the environment and represents a waste of a potentially useable byproduct. Here we examine the sorptive characteristics of oil shale semicoke. Oil shale samples from Estonia, China and the United States were pyrolyzed at 500 and 1000 °C and their products analyzed for organic char content, surface area and porosity. Pyrolysis of the oil shales at temperatures of 500-1000 °C yields semicokes with organic char contents from 1.7% to 17.5% and BET surface areas of 4.4-57 m² g⁻¹, corresponding to 100-550 m² g⁻¹ of organic char. For comparison, the BET surface areas of class F coal fly ashes (combustion byproducts of bituminous coals) typically range from 2 to 5 m² g⁻¹, corresponding to 30-60 m² g⁻¹ of carbon while class C fly ash (from low rank coals) have carbon BET surface areas comparable to oil shale semicoke organic char surface areas.     

油页岩矿物质催化半焦燃烧特性及机理

利用微型流化床反应分析仪（MFBRA）研究了油页岩矿物质催化半焦燃烧特性,重点考察了半焦内部矿物质和外部页岩灰床料对半焦燃烧的催化作用,揭示了流化床反应器中半焦燃烧过程和机理。结果表明：内部矿物质和外部床料对半焦燃烧均具有明显催化作用,而两者共同催化效果最为显著。矿物质中CaO和Fe₂O₃对半焦燃烧具有催化活性,CaO催化作用强于Fe₂O₃。油页岩半焦燃烧反应活化能在60.41~78.97 kJ/mol之间,矿物质的催化作用会明显降低反应活化能。流化床反应器中,矿物质对半焦燃烧的催化作用主要表现在四个反应,即：挥发分裂解和燃烧、半焦表面炭燃烧、半焦内部炭燃烧以及一氧化碳燃烧。     

Characteristics and mechanism of catalytic effect of inner minerals on combustion of oil shale coke

The micro fluidized bed reaction analyzer (MFBRA) was used to study the combustion characteristics of oil shale mineral catalytic semi-coke. This study compared the effect of minerals inside char and bed material (oil shale ash) outside char on char combustion, and the process and mechanism of char combustion in the fluidized bed were further revealed. Both of minerals inside char and bed material outside char had a marked catalysis for char combustion and their combined catalysis was most notable. It is found that the CaO and Fe₂O₃ were the major active components in oil shale minerals for catalytic combustion of char, and the catalysis of CaO was stronger than that of Fe₂O₃. The activation energy of char combustion ranged from 60.41 kJ/mol to 78.97 kJ/mol, and it would significantly decrease with presence of the catalysis by minerals in oil shale. For char combustion in a fluidized bed, the contribution of minerals to catalytic combustion was mainly reflected in four reactions, such as volatiles cracking and combustion, surface carbon combustion, internal carbon combustion and CO combustion.     

神木烟煤等离子体气化所制半焦的特性研究

在实验室中采用三相交流等离子体电弧发生炉对神木烟煤进行等离子体气化制得实验用半焦,并对其进行工业分析和流化床燃烧实验。工业分析结果表明,所制得半焦中挥发分含量几乎为零,而部分灰分和固定碳也参与反应挥发出去。半焦在流化床中燃烧实验结果表明,所制得半焦能够在流化床中持续稳定燃烧,并且燃烧过程中燃烧产物能够稳定排放。通过建立数学模型求得半焦燃烧动力学参数,结果表明,半焦的活化能远大于原煤的活化能,其反应活性则低于原煤的反应活性。     

Experimental and numerical analysis of oil shale drying in fluidized bed

The main objective of this work was to experimentally and numerically investigate the Liu Shu River oil shale drying by the means of flue gas in a fluidized bed dryer. Several experiments were performed under different temperatures conditions. The moisture content of oil shale was measured during the experiments. The two-stage drying model was incorporated in computational fluid dynamics (CFD) package FLUENT via user-defined functions (UDF) and utilized for simulation of heat and mass transfer of oil shale drying in the fluidized bed dryer. The simulation results for solid moisture content agreed well with experimental data. The effects of the temperature and velocity of flue gas, initial bed height, and the particle size on the drying characteristics were predicted and analyzed. It is shown that the gas temperature and velocity are the important parameters in the whole drying process. The particle size has more obvious influence in the falling drying period than the constant drying period. The temperatures of gas and solid phases were monitored. It is shown that the so-called “near gas distributor zone” is the most effective heat transfer zone, which agrees well with the calculated value. The system quickly reached thermal equilibrium, characterizing a nearly isothermal bed. The developed model provides a very good demonstration to describe the oil shale drying in the fluidized bed dryer, and may provide important information for design, optimization of operation conditions.     

油页岩循环流化床燃烧室密相区物料颗粒与燃烧特性

在 65t/h油页岩循环流化床锅炉上进行了燃烧室密相区物料特性与燃烧特性的工业试验。得到了极具片状结构特点的油页岩颗粒特性 ,经燃烧破碎磨损后的密相区床料和循环物料的颗粒特性与燃烧特性及相应的锅炉运行参数。试验结果对油页岩循环流化床锅炉的放大设计与运行调节具有一定的参考价值。同时为进一步建立油页岩循环流化床燃烧室密相区的流动、燃烧、传热、磨损、扬析与夹带模型奠定了基础。     

油页岩循环流化床燃烧特性研究

摘要:在循环流化床燃烧试验台上对油页岩的着火、稳定燃烧、燃尽特性等燃烧特性进行详细地试验方案分析,同时提出了油页岩循环流化床锅炉的设计与运行的特点。根据拟做试验方案进行试验研究,可以测试出油页岩的燃烧特性,为油页岩CFB锅炉燃烧特性的试验研究,以及大型化油页岩循环流化床锅炉的设计提供了借鉴。     

油页岩循环床锅炉中温分离回输系统Loop Seal工作特性的研究

在目前世界上投入商业运行最大容量的 65t/h油页岩循环流化床锅炉上 ,进行了全尺寸的中温分离系统中LoopSeal型返料装置的工作特性热态试验 ,得到了油页岩循环流化床燃烧中温分离回输系统中LoopSeal型返料装置的运行参数、温度特性及其循环物料的颗粒特性和含碳量分布 ,试验结果对油页岩循环流化床锅炉的放大设计与运行调节具有一定的参考价值     

Method for determining the kinetics of cracking and coking of shale oil vapours in fluidized beds

The secondary cracking and coking of oil vapours produced from oil shale retorting have been previously shown to depend upon the nature and temperature of the substrate over which these reactions occur. To realistically examine the kinetics of these reactions during fluidized bed retorting, an apparatus has been developed which permits shale oil vapours generated in one fluidized bed to pass over selected substrates in a second fluidized bed. Substrates can be fed as a batch or continuously. In the batch mode, the substrate is heated to reaction temperature and is then exposed to shale oil vapours for a chosen period of time. Carbon deposition onto the solid is monitored in real-time by combusting the pyrolysis products and measuring the oxides of combustion with an on-line mass spectrometer. The extent of carbon uptake is also determined by elemental analysis of the substrate following reaction. These two methods of analysis were shown to correspond well under all the conditions investigated. In the continuous mode, substantial amounts of product oil can be collected so the effects of cracking may be evaluated. The rates of carbon deposition onto processed shales and pure minerals have been measured.     

干馏温度对油页岩半焦着火的影响

基于石油价格的增长和环保要求的日益提高,提出了油页岩资源的炼油、发电、供热、建材的综合利用方案,其中油页岩半焦干馏温度是该方案的一个关键参数。采用热分析方法研究干馏温度对半焦着火方式影响的实验,结果表明:随着干馏温度的升高,油页岩半焦的着火方式将由均相着火转变为多相着火;干馏温度500℃不仅有利于炼制页岩油,从燃烧角度来说,该温度所制取的半焦着火温度低且着火方式为均相着火,因此也有利于锅炉的燃烧。     

大庆油页岩及干馏产物的利用途径分析

大庆油页岩的舍油率大部分都在10%以上,具有很好的经济开发价值.对大庆油页岩及其干馏产物性质的实验研究表明,油页岩的机械强度较低,应选择粉末、颗粒干馏炉进行加工处理;页岩油主要由柴油馏分和重油馏分组成,分别可加工成成品油和直接用作燃料油;热解干馏气热值约为17MJ/m3,可以在除作自身干馏所需的热量燃料外,用作城市煤气或工业锅炉的燃料;半焦着火点低,热值约为23 MJ/kg,可作为清洁燃料用于发电或民用;页岩灰的主要组分是氧化钙争氧化硅,可用于生产建筑材料.     

程序升温下页岩油泥热解机理

采用热重分析仪,进行了桦甸和汪清页岩油泥在不同升温速率（5 ℃/min,10 ℃/min,20 ℃/min,40 ℃/min）下热失重实验,并通过瓦斯气析出情况研究页岩油泥热解机理。结果表明,页岩油泥热解分为3个阶段：第一阶段（20～180 ℃）为水分和轻质组分析出;第二阶段（180～360 ℃）重质组分稳定析出,是动力学研究的重点;第三阶段（360～600 ℃）为半焦炭化及矿物质失重过程。研究发现,催化剂K2CO3能有效降低油泥热解温度及其残渣率,而Al2O3对油泥热解催化不明显甚至起抑制作用。在页岩油泥热解过程中,生成的有机大分子侧链发生C—C键断链,生成小分子的烷烃和不饱和烃,在低压高温条件下,其断链位置倾向于碳链端部,使得小分子烃含量较多。     

基于Aspen Plus的桦甸式油页岩干馏工艺系统模拟

引言油页岩是一种富含有机质、具有微细层理、可燃烧的细粒沉积岩,油页岩作为能源资源,既可以干馏炼油也可以燃烧发电。油页岩储量丰富,截至2005年底,37个国家油页岩探明总储量折算     

Comparison of dual fluidized bed steam gasification of biomass with and without selective transport of CO2

A comparison of dual fluidized bed gasification of biomass with and without selective transport of CO₂ from the gasification to the combustion reactor is presented. The dual fluidized bed technology provides the necessary heat for steam gasification by circulating hot bed material that is heated in a separate fluidized bed reactor by combustion of residual biomass char. The hydrogen content in producer gas of gasifiers based on this concept is about 40 vol% (dry basis). Addition of carbonates to the bed material and adequate adjustment of operation temperatures in the reactors allow selective transport of CO₂ (absorption enhanced reforming—AER concept). Thus, hydrogen contents of up to 75 vol% (dry basis) can be achieved. Experimental data from a 120 kW_{Fuel input} pilot plant as well as thermodynamic data are used to determine the mass- and energy-balances. Carbon, hydrogen, oxygen, and energy balances for both concepts are presented and discussed.     

Flow structure and combustion characteristic of 65 t/h oil shale-fired circulating fluidized bed riser—2: Dilute phase

In this paper, a 65 t/h oil shale-fired circulating fluidized bed (CFB) boiler was put into commercial operation in Huadian of China in 1996 and industrial hot experiment was done for studying the flow structure and combustion characteristic of CFB dilute phase regime. Flow structure and solid flux of dilute phase regime were investigated along both vertical direction and horizontal direction under different boiler loads. Particle-size distribution and carbon content of oil shale combustion residues were obtained. Experimental investigation shows that SO₂ concentration decreases with increasing the furnace height, and NO_X emission can be reduced by adopting staged combustion technology, low-temperature combustion and circulating combustion. Experimental results are valuable for adjusting the 65 t/h boiler and designing large-scale oil shale-fired CFB boiler. At the same time, the experiment lays a foundation for modeling the flow structure, combustion, heat transfer and abrasion of oil shale-fired CFB dilute phase regime.     

Modeling calcium dissolution from oil shale ash: Part 2.: Continuous washing of the ash layer

In the present work a possible approach to the utilization of oil shale ash containing free lime in precipitated calcium carbonate (PCC) production is elucidated. This paper investigates the Ca (calcium) dissolution process during continuous washing of pulverized firing (PF) and fluidized bed combustion (FBC) oil shale ash layers in a packed-bed leaching column. The main characteristics of the Ca dissolution process from ash are established. The effect of water flow rate is investigated by conducting leaching experiments of oil shale ashes formed in boilers operating with different combustion technologies. The values of the overall and liquid phase mass transfer coefficients are evaluated based on experiments using the developed ash layer washing model. The model is a set of partial differential equations that describe the changes in Ca content in the stagnant layer of ash and in the water flowing through the ash layer. An example in which the model is applied to environmental assessment and estimation of Ca leaching from industrial oil shale ash fields is provided.     

油页岩固体热载体流化干馏炼油工艺中试研究

介绍了以依兰粉末页岩作原料的页岩流化干流中试装置概况及试验流程,并对试验结果进行了分析。中试结果表明,中试装置页岩油产率为铝甑干馏法的90.15%,经冷凝回收系统及油泥处理后获得的页岩油收率为铝甑的82%;固体热载体流化干馏工艺所产页岩油较轻,337℃以前馏分大于80%。     

基于气固流态化原理的油页岩干燥动力学

为了考察气固流化床干燥器能否使油页岩含水质量分数达到要求,以柳树河油页岩颗粒为原料,研究进口气体温度和颗粒直径对油页岩干燥性能的影响,采用薄层干燥模型,对油页岩干燥实验数据进行模拟,确定油页岩干燥方程和干燥速率方程,建立油页岩干燥速率特征常数和有效扩散系数之间的关联式。研究结果表明:薄层干燥模型中修正Page模型Ⅰ适合描述油页岩的干燥过程;油页岩在流化床内干燥过程主要发生在降速干燥阶段,进口气体温度越高,油页岩颗粒直径越小,所需干燥时间越短,进口气体温度为350℃时,使2.4 mm油页岩含水质量分数低于5%,所需干燥时间为2.5 min。     

Elemental mercury vapor capture by powdered activated carbon in a fluidized bed reactor

A bubbling fluidized bed of inert material was used to increase the activated carbon residence time in the reaction zone and to improve its performance for mercury vapor capture. Elemental mercury capture experiments were conducted at 100 °C in a purposely designed 65 mm ID lab-scale pyrex reactor, that could be operated both in the fluidized bed and in the entrained bed configurations. Commercial powdered activated carbon was pneumatically injected in the reactor and mercury concentration at the outlet was monitored continuously. Experiments were carried out at different inert particle sizes, bed masses, fluidization velocities and carbon feed rates. Experimental results showed that the presence of a bubbling fluidized bed led to an increase of the mercury capture efficiency and, in turn, of the activated carbon utilization. This was explained by the enhanced activated carbon loading and gas-solid contact time that establishes in the reaction zone, because of the large surface area available for activated carbon adhesion/deposition in the fluidized bed. Transient mercury concentration profiles at the bed outlet during the runs were used to discriminate between the controlling phenomena in the process. Experimental data have been analyzed in the light of a phenomenological framework that takes into account the presence of both free and adhered carbon in the reactor as well as mercury saturation of the adsorbent.     

Thermal separation of coal-oil suspensions in a fluidised bed

A series of experiments were made on the thermal separation of various mixtures of coal in oil using a fluidized bed reactor. The majority of experiments were carried out on a mixture of 30% w/w Edmonton coal in 70% w/w Leduc crude oil in a temperature range of 700–900°F. The products of the reaction were a char, an oil and a gas. At temperatures above 700°F. the solid particles became dry and free-flowing; no agglomeration or channelling in the bed was apparent. An increase in reactor temperature in the 700–900°F. range decreased the amount of residual oil on the char from about 2% to 0.1% at the same time the heating value of the char rose from 11,900 to 12,600 Btu/lb. Carbon residue of the product oil was substantially less than that of the original oil, the reduction being about 50% in the case of Leduc oil and 75% for Lloydminster oil.