基于超临界流体萃取的渣油掺炼煤焦油的脱沥青油性能评价

为寻求减压渣油的有效利用,采用"超临界流体萃取技术"对减压渣油/煤焦油混合原料进行溶剂脱沥青实验,并对脱沥青油(DAO)性质进行了详细评价。结果表明,当煤焦油掺炼量低于20%时,脱沥青油收率明显提高;且相同收率下脱沥青油性质有所改善,其催化裂化反应性能明显优于减压渣油的脱沥青油。减压渣油掺炼煤焦油以溶剂脱沥青-催化裂化组合工艺进行加工有一定的优势和可行性。     

Effects of coal cleaning on the short contact time liquefaction of Illinois No. 6 coal

This study was carried out to determine the effect of coal cleaning by oil agglomeration and sink-float methods on yields from short contact time liquefaction of Illinois No. 6 coal. The runs were made in a continuous unit using SRC-II distillates as process solvent. Measured yields included hydrogen (consumption), hydrocarbon gas, distillate oil, SRC (the pyridine-soluble portion of the residue) and insoluble organic matter, the pyridine-insoluble organic residue. The solubility of product SRC in hexane, toluene and pyridine was also determined. The principal finding was that coal cleaning by density methods reduced the yield of IOM obtained in subsequent liquefaction and this is attributed to the removal of inert components from the feed coal. In addition, cleaning which significantly reduced pyrite content of the feed coal also reduced the yield of distillate oil and tended to give a less soluble SRC during liquefaction. Deep cleaning by gravity methods gave the lowest IOM, but reduced pyrite content to the point where distillate oil was consumed rather than produced. Oil agglomeration reduced total ash to 50% of that in the run-of-mine coal, but left the pyrite level in the coal high. The relevance of these results to two-stage liquefaction is discussed.     

溶胀对神华煤结构及液化性能的影响

采用甲苯和吡啶对中国神华煤进行直接液化前的溶胀处理,通过对溶胀度及抽提率的测定、IR光谱分析、热重分析以及溶胀煤的直接液化实验,探讨了溶胀预处理对神华煤结构及液化性能的影响.结果表明:经溶胀预处理,煤的溶胀度、抽提率获得了显著提高,煤结构中的弱共价键断裂,进而改善了其液化性能并提高了煤的直接液化转化率和油气产率.     

Solvent de-ashing from heavy product of brown coal liquefaction using toluene:: 2. concentration and separation of ash with a continuous de-ashing system

The brown coal liquefaction (BCL) process is a two-stage liquefaction (hydrogenation) process developed for Victorian brown coal in Australia. The BCL process has a solvent de-ashing step to remove the ash and heavy preasphaltenes from the heavy liquefaction product (vacuum residue) derived from the coal in primary hydrogenation and named CLB (coal liquid bottom). This solvent de-ashing step uses toluene or coal-derived naphtha as a de-ashing solvent (DAS). After dissolving the CLB into the solvent (CLB/solvent ratio, 1/8–1/4, w/w) under high temperature (200–290°C) and high pressure (4–5 MPa), insoluble solid particles which consist of ash and heavy preasphaltenes are settled by gravity and separated from the solution as an ash-concentrated slurry. The ash-concentrated slurry and the de-ashed solution are withdrawn from the settler as an underflow and overflow, respectively. The de-ashed heavy product is recovered from the solution by eliminating the solvent and is further hydrogenated in secondary hydrogenation. The authors have reported on the solubility of CLB in toluene and the settling velocity (V) of the boundary of ash content in the settler under de-ashing conditions. This paper discusses the effects of de-ashing conditions on ash concentration in the settler bottom and the operating conditions of a continuous de-ashing system. The ash content in underflow (C_UF, kg/kg or wt.%) at the settler bottom was found to increase with temperature and to decrease with the rate (flux) of downward flow (underflow). The maximum C_UF, Z, is expressed by the equation: Z=B_CLB(FL/0.35)^−0.32(T/523)^4.26, where B_CLB, FL and T are the characteristic parameters of organic CLB (kg/kg or wt.%), flux of underflow in the settler (kg/m² s) and temperature (K), respectively. B_CLB is also expressed by using the analytical results of organic insolubles in the CLB under de-ashing conditions. Finally, stable operating conditions of a continuous de-ashing system are confirmed to be determined as the following qualifications: |V_u|<|V|, W_UF>W_SA/C_UF and Z>C_UF, where |V_u|, |V|, W_SA and W_UF are the upward velocity of the solution in the settler (mm/s), settling velocity of the ash boundary (mm/s) in the settler, flow rate of ash in the feed slurry (kg/h) and flow rate of underflow (kg/h), respectively. Under these qualified conditions, the 50 t/d pilot plant constructed in Australia was operated under stable conditions for 3700 h using toluene as a DAS.     

Approach for promoting liquid yield in direct liquefaction of Shenhua coal

Single and multi-stage liquefaction of Shenhua (SH) bituminous coal and re-liquefaction of its liquefaction residue (SHLR) were carried out in an autoclave reactor to investigate the essential approach for promoting oil yield and conversion in SH coal direct liquefaction (SHDL). The multi-stage liquefaction includes pretreatment, keeping the reactor at 250 °C for 40 min before heating up to the reaction temperature, and two-stage liquefaction processes consisting of low temperature stage, 400 °C, and high temperature stage, 460 °C. The results show that the pretreatment has slight effect on oil yield and conversion of SHDL, especially for liquefaction at 460 °C. There is a positive function of two-stage liquefaction in shortening reaction time at high temperature. Increasing ratio of solvent to SHLR can promote the oil yield and abate reaction condition in SHLR re-liquefaction, that is, it can promote the conversion from preasphaltene and asphaltene to oil. The primary factor to inhibit coal liquefaction is the consumption of hydrogen free radical (H·) from solvent or H₂ and condensation of free radicals from coal pyrolysis after a period of reaction. So the essential approach for increasing oil yield and conversion of SHDL is to provide enough H· to stabilize the free radicals from coal pyrolysis.     

Effect of pre-swelling of coal on its solvent extraction and liquefaction properties

Effects of pre-swelling of coal on solvent extraction and liquefaction properties were studied with Shenhua coal. It was found that pre-swelling treatments of the coal in three solvents, i.e., toluene (TOL), N-methyl-2-pyrrolidinone (NMP) and tetralin (THN) increased its extraction yield and liquefaction conversion, and differed the liquefied product distributions. The pre-swollen coals after removing the swelling solvents showed increased conversion in liquefaction compared with that of the swollen coals in the presence of swelling solvents. It was also found that the yields of (oil + gas) in liquefaction of the pre-swollen coals with NMP and TOL dramatically decreased in the presence of swelling solvent. TG and FTIR analyses of the raw coal, the swollen coals and the liquefied products were carried out in order to investigate the mechanism governing the effects of pre-swelling treatment on coal extraction and liquefaction. The results showed that the swelling pre-treatment could disrupt some non-covalent interactions of the coal molecules, relax its network structure and loosened the coal structure. It would thus benefit diffusion of a hydrogen donor solvent into the coal structure during liquefaction, and also enhance the hydrogen donating ability of the hydrogen-rich species derived from the coal.     

Two-stage coal liquefaction using sequential mineral and hydrotreating catalysts

Two-stage coal liquefaction offers significant improvements over single-stage processing in terms of product yields. The proposed two-stage operation utilizes an inexpensive and readily available mineral or disposable catalyst in the first stage followed by a commercial hydrotreating catalyst in the second stage. Single stage processing at 450°C and 425°C both show metal sulfides, i.e. pyrite, to be effective in increasing oil yields. In two-stage processing at 450°/410°C the sequence of pyrite followed by NiMo/Al₂O₃ is the most effective combination for producing oil (pentane soluble materials). Two stage processing at 425°/425°C utilizing sulfided liquefaction residue ash or pyrite as first-stage catalysts yields the highest percentage of oil. The improvements shown by solubility product distributions are verified by distillation curves of the reaction product. Evidence of pore diffusion limitation is apparent in the pelletized NiMo/Al₂O₃. Changes in catalyst morphology may be necessary to achieve maximum yields.     

Liquefaction of coal in a petroleum fraction under mild conditions

Experimental studies on a mild coal liquefaction process for extending the petroleum fuel supply are presented. In this process, coal is dissolved in bottoms from fluid catalytic cracking (FCC), a thermally stable, highly aromatic refinery stream, without added hydrogen and under mild conditions. After ash removal, the product mixture of coal liquid and FCC bottoms is a pumpable fluid and can be used as a boiler fuel. Further upgrading to turbine fuel may be possible.At 600–800°F, 0.1 to 5 h, and 0–1000 psig, conversion of a bituminous coal to pyridine soluble, gas and water was about 90%, while that of lignite was about 60%. Improved product quality was favored by increased reaction pressure. The operable solvent to coal ratio can be as low as 1.3. This ratio can be further reduced if provisions are made to recycle part of the solvent. However, the efficiency of the recovered solvent decreases with each recycle due to a gradual replacement of labile α hydrogen by β hydrogen.     

An overview of solid–liquid separation of residues from coal liquefaction processes

Direct coal liquefaction process typically produces mixed oils (60%) and gases (15%). The remainder is a high‐boiling viscous residue that contains oils, asphaltenes, unreacted coal, mineral matter and potentially valuable liquefaction catalyst. Effective separation of the components of the residue stream is important to the economic and environmental performance of the process. Solid–liquid separation technologies, such as filtration, hydrocyclones, centrifugation, critical solvent deashing and distillation have been reviewed in relation to their use in coal liquefaction processes. Individual operations used have not been completely satisfactory, and a better overall result is obtained when they are used in combination. © 2012 Canadian Society for Chemical Engineering     

Kinetics of short contact time coal liquefaction. Part I: Effect of operating variables

The liquefaction kinetics of Powhatan No.5 mine coal (Pittsburgh Seam) in the presence of SRC-II recycle solvent at short contact times (<10 min) and temperature and pressure ranges of 573–723 K and 10.3–13.8 MPa is examined in a well-mixed reactor. In the initial stages of liquefaction, while overall coal conversion (tetrahydrofuran solubles) increases with temperature, oil (pentane solubles) is lost with an increase in temperature. An increase in solvent-to-coal ratio results in an increase of conversion. The initial coal particle size distribution, total pressure, and nature of gas phase (nitrogen or hydrogen) have no significant effect on the production of any of the product of liquefaction for contact times up to 10 min. A lumped kinetic model is presented to describe the product distribution.     

煤直接液化中溶剂的作用和种类

讨论了煤液化中溶剂的作用和种类,煤液化中溶剂的作用为溶解溶胀作用,稀释分散粒以及对煤热裂解生成的自由基的保护作用。并着重讨论了供氢溶剂的供氢作用和转移氢作用。溶剂的各类分为工业和研究中常用的普通混合溶剂,煤焦油,石油渣油等重质油溶剂和废塑料、废橡胶等废化学品溶剂,初步分析了它们的供氢作用和传递转移活性氢作用。     

神府煤的液化性能及其重质产物结构表征

利用管式高压反应釜,以四氢萘为溶剂、FeS和S为催化剂,对神府煤进行了加氢液化研究,考察了催化剂、反应温度和反应气氛等因素对煤液化性能和产物组成分布的影响,同时对液化产物进行了红外光谱、元素分析以及酸性含氧官能团等结构表征。结果表明,FeS+S催化神府煤液化的最高四氢呋喃(THF)抽提率和油+气收率分别为69.5%和35.9%;未加催化剂时,神府煤液化THF抽提率和油+气收率都是最低的。     

探讨溶剂脱沥青技术在当今炼厂中的地位和作用

介绍了脱碳和加氢2条重油转化路线各自典型的工艺技术及其特点,阐明在未来炼厂渣油加工过程中,溶剂脱沥青技术将发挥举足轻重的作用,其高兼容性的特点使其可与其他工艺技术进行灵活组合,显著提高渣油的转化率以及原油采购和产品结构的灵活性,从而提高炼厂经济效益。新建炼厂的渣油加工技术应是以溶剂脱沥青工艺为核心的脱碳工艺与加氢工艺的组合工艺,充分发挥二者优势,扬长避短,在提高渣油转化率的同时显著改善渣油加氢裂化装置的操作稳定性、降低装置的操作苛刻度以及投资和运行成本,实现经济效益最大化,提高炼厂的竞争力。     

Production of coal pitch by the oxidation of coal extracts in anthracene oil

If anthracene oil is used to produce extracts from 2B, D, 2G, GZh coal, coal pitch may be produced by oxidation of the extracts using atmospheric oxygen. The resulting pitch is characterized by higher yield and by a greater coke residue than is observed in pitch produced from anthracene oil without added coal in analogous conditions. Ultrasound treatment for 3 h on an IL10-0.63 unit ensures complete solution of the coal (4–9%) in the anthracene oil. The mineral component of the coal also enters the solution and is then concentrated in the pitch formed. To reduce the ash content of the pitch, ash must preliminarily be removed from the initial coal. For the example of 2B and D coal, it is found that reducing the ash content of the coal to ~1% and subsequent solution in the anthracene oil to a coal concentration of 5–8% yields a coal extract such that pitch with no more than 0.4% ash and up to 41% coke residue is formed on oxidation by atmospheric oxygen.     

Process analysis of the extract unit of vacuum residue through mixed C4 solvent for deasphalting

By employing the EXTRACT module in Aspen Plus Software with the aid of selected PSRK equation from our previous work [W. Li, P. Du, F. Cao, W. Ying, D. Fang, Simulation and optimization of the extract segment of solvent deasphalting plant, Computers and Applied Chemistry, 26 (2009) 455–460] [18], this work simulated a solvent deasphalting (SDA) process with mixed C4 solvent and the feedstock of vacuum residue (VR) obtained from a mixed crude oil (Zhongyuan oil:Tahe oil:Changqing oil:Oman crude oil:Zafiro crude oil = 35:5:2:40:18, wt/wt). The feed of VR was lumped as paraffinic, primitive and aromatic components according to their calculated K_UOP values. The relative errors not more than 3.94% illustrated the simulated results are comparable with the industrial data for both feedstock (VR and mixed C4 solvent) and products (deasphalted oil—DAO and deoiled asphalt—DOA). The DAO yield was predicted to reduce to 47.2% from 58.0% with increasing temperature of mixed C4 solvent from 100 to 120 °C under operating model-I, but increased from 51.6% to 56.1% with solvent–VR ratio up to 6.5 from 4.5. In addition, a heavier mixed C4 solvent would facilitate remarkable improvement of DAO yield but deteriorate its quality.     

Kinetics of coal liquefaction during heating-up and isothermal stages

Direct liquefaction of Shenhua bituminous coal was carried out in a 500 ml autoclave with iron catalyst and coal liquefaction cycle-oil as solvent at initial hydrogen of 8.0 MPa, residence time of 0–90 min. To investigate the liquefaction kinetics, a model for heating-up and isothermal stages was developed to estimate the rate constants of both stages. In the model, the coal was divided into three parts, easy reactive part, hard reactive part and unreactive part, and four kinetic constants were used to describe the reaction mechanism. The results showed that the model is valid for both heating-up and isothermal stages of liquefaction perfectly. The rate-controlled process for coal liquefaction is the reaction of preasphaltene plus asphaltene (PAA) to oil plus gas (O + G). The upper-limiting conversion of isothermal stage was estimated by the kinetic calculation.     

Liquefaction of subbituminous coals with a basic nitrogenous model process solvent

Liquefaction reactions in a tubing-bomb reactor have been carried out as a function of coal, coal sampling source, reaction time, atmosphere, temperature, coal pre-treatment, SRC post-treatment and process solvent. Pyridine as well as toluene conversions ranging from 70 to > 90 wt% involving both eastern bituminous and western subbituminous coals are obtained. 1,2,3,4-Tetrahydroquinoline (THQ) has been extensively used as a process solvent under optimized liquefaction conditions of 2:1 solvent: coal, 7.5 MPa H₂, 691 K and 30 min reaction time. Comparisons of THQ with other model process solvents such as methylnaphthalene and tetralin are described. Liquefaction product yield for conversion of subbituminous coal is markedly decreased when surface water is removed from the coal by drying in vacuo at room temperature prior to liquefaction. The effect of mixing THQ with Wilsonville hydrogenated process solvent in the liquefaction of Wyodak and Indiana V coals is described.     

The effect of extraction condition on ‘HyperCoal’ production (1)—under room-temperature filtration

In order to produce ashless coal (HyperCoal) in a high yield, extractions with several organic solvents—tetralin, 1-methylnaphthalene, dimethylnaphthalene and light cycle oil (LCO) at 200–380 °C were conducted for various ranks of coals, and subsequent solid/solution separation was done at room temperature. LCO was found to be a useful, cost-effective solvent, since it gave similar extraction yields to three other reagent solvents. The extraction yield for Illinois No. 6 coal gradually increased over 200 °C, and a significant increase in extraction yield was observed from 350 to 360 °C. We succeeded in producing ashless coal with less than 0.1% in ash content for seven of nine coals used in this study.     

神华上湾煤恒温阶段直接液化反应动力学

为考察神华上湾煤的直接液化性能及反应动力学,以加氢蒽油-洗油混合油作为溶剂、负载型FeOOH作为催化剂,在0.01 t·d^-1煤直接液化连续实验装置上考察了不同反应温度（435~465℃）、不同停留时间（7~110 min）下液化产品组成的演变规律。研究发现,随着煤的裂解及加氢反应的进行,煤及沥青类物质（PAA）收率不断减小,重质液化产物逐步向轻质液化产物转化。当反应温度为455℃、停留时间为90 min时,煤转化率为90.41%（质量分数（,油收率为61.28%（质量分数（。随着反应条件进一步苛刻,油收率下降。基于上湾煤直接液化反应特性及其产物收率变化规律建立了11集总煤直接液化反应动力学候选模型,以BFGS优化算法对实验数据搜索、选优,确定了动力学模型参数。检验结果表明所建立的动力学模型可用于恒温阶段直接液化行为的模拟计算。     

催化裂化（FCC）油浆作煤直接液化溶剂的研究进展

煤制油工艺等煤炭清洁高效转化技术是能源化工领域的研究热点,溶解性好、提供/传递氢能力强且热稳定性高,其溶剂选择、使用是影响煤制油工艺经济运行的关键。本文以煤液化溶剂作用为基础,通过对液化自身产物、废塑料及FCC油浆等煤直接液化溶剂的组成、性质及作用效果的综合评述,指出煤、溶剂、氢气间的混合并非理想混合,与煤H/C适宜、极性相近的溶剂在共处理过程表现出良好的协同作用,液化过程的转化率、轻质产物选择性明显提高。分析表明,协同作用的大小取决于煤、溶剂的组成、性质匹配。煤-重质烃共处理工艺利用富芳烃油浆溶解性好、提供/传递氢能力强的特点强化了煤热解加氢反应的进行,同时煤加氢液化产生的多孔残煤具有吸附性强的特点,有助于重质烃改质,使共处理转化率显著提高、轻质产物选择性增大。最后指出,煤-重质烃共处理的协同作用为改善煤、中质/重质芳烃的综合利用提供了可能。