高硫煤中形态硫的热解迁移特性

对西北地区石炭纪高硫煤进行热解实验,考察了热解温度(200℃～1 000℃)和热解停留时间(20min～100min)对煤中形态硫的迁移特性的影响,并通过FTIR分析了热解过程中半焦的结构变化情况.研究表明,高硫煤中全硫随热解温度的升高先减小后增大,在600℃时达到最低;硫酸盐硫的含量较低,维持在0%～0.5%之间;硫化铁硫随着热解温度的升高逐渐减小;有机硫随热解温度的升高先减小后增大,在500℃时达到最低.无机硫脱除率高于有机硫脱除率.煤热解过程中氧和硫等杂原子官能团在半焦中不断减弱.     

煤炭直接液化反应机理研究进展

为探讨煤炭直接液化反应机理,论述了煤炭直接液化反应历程,分析了煤的浸润溶胀、煤的热解、供氢溶剂热解、H2溶解、H2活化、自由基之间的相互反应等过程。研究发现,在合适的温度范围内,煤热解10 min以内即接近自由基浓度的最大值,与煤热解自由基反应活性强弱分别为:煤热解提供的活性氢及小分子自由基供氢溶剂提供活性氢H2提供活性氢,并指出H2与煤热解自由基的反应程度是决定最终液化产物整体H/C原子比的重要因素。基于液化反应机理,提出进一步明确H2在不同催化剂作用下被活化与煤热解自由基反应的机理,降低反应温度、压力,开发高活性催化剂是下一步研究方向。     

炼焦煤尾煤热重动力学分析及热解产氢

基于热重分析和固定床热解实验,研究了升温速率和温度对高矿物质含量的炼焦煤尾煤热解特性的影响. 尾煤热解过程可分为室温至400, 400~600及600~950℃三个阶段. 尾煤与焦煤热解曲线基本吻合,尾煤热解特征温度略向高温区推移. 采用Coats-Redfern积分法拟合计算了尾煤热解的动力学参数,得出反应活化能为22.6~66.2 kJ/mol,热解过程可用3个二级反应描述. 30 g尾煤固定床实验结果表明,氢气在低于400℃析出很少,400~600℃缓慢析出,之后随温度升高析出增加,600℃后大量析出,900℃左右达到最大析出量. 终温950℃时,30 g尾煤热解产气4300 mL,氢气产量1722 mL;焦煤产气7950 mL,氢气产量2716 mL. 尾煤热解富氢气体产量达焦煤热解气产量的54%,具有较高的再利用价值.     

呼伦贝尔煤与3种富氢有机物共热解相互作用研究

通过考察呼伦贝尔煤与3种富氢有机物(纤维素、聚乙烯吡咯烷酮(PVP)、高密度聚乙烯(HDPE))共热解过程热失重、自由基浓度、固定床热解产物产率变化,并与单独热解对比,解析共热解过程中不同原料热解产生的自由基碎片在逸出床层过程中的相互作用。试验发现,煤/纤维素、煤/PVP、煤/HDPE共热解在150~600℃的失重量分别为61.18%、60.26%和64.31%,均低于计算值62.55%、63.53%和66.76%;温度高于400℃时,共热解过程自由基浓度试验值均低于计算值(单独热解结果平均值);固定床热解试验中,固体产率分别为37.9%、39.0%和34.0%,与计算值(37.5%、36.5%和33.6%)相当或略高,液体(包含水和焦油)产率试验值分别为33.3%、44.9%和53.2%,均低于计算值(39.8%、51.3%和57.1%),气体产率试验值分别为28.8%、16.1%和12.9%,均高于计算值(22.7%、12.2%和9.3%)。因此共热解过程中,不同原料热解产生的自由基碎片在逸出床层过程中会相互作用,挥发性自由基和稳定自由基之间的结合最明显,挥发性自由基逸出阻力增加,二次反应增大。     

热解温度对低阶煤热解水中挥发酚的影响

中国低价煤储量丰富,而且自身挥发分较高,将其热解转化是一条科学的利用途径。选取5种典型低阶煤,在1 kg外热式固定床热解装置上进行热解试验,测定了热解水中挥发酚含量,并初步探讨了影响水中挥发酚含量的因素。结果表明:热解温度550~750℃,低阶煤热解水中挥发酚质量浓度为(1~9)×103mg/L,1 kg煤样热解进入水中的挥发酚总量约为(1.0~2.0)×103mg;氧含量和单位干燥无灰基煤样热解水中挥发酚总量并没有明显的相关性;随着热解温度的升高水中挥发酚质量浓度和总量基本呈上升趋势。     

KOH对低阶煤在超临界水中制取富氢气体的影响

以超临界水介质中低阶煤制取富氢气体为目的,利用120 ml小型间歇反应装置,在KOH/煤为0.7％～10％(质量)、温度400～650℃、压力12～30 MPa、停留时间0～30 min的范围内,考察了KOH催化下操作参数对小龙潭褐煤反应特性的影响。结果表明,随着KOH/煤质量比的增加,煤转化率和气体产率升高。KOH/煤质量比为10％时,气相产物中H_2百分含量增加一倍,H_2产率提高1.7倍。升高反应温度可以使KOH的催化作用更显著。对比氮气气氛和超临界水中煤催化热解反应发现,反应温度为600℃时,添加相同量的KOH催化剂,氮气气氛下煤转化率升高4.4％(质量),SCW条件下煤转化率升高7.8％(质量),说明超临界水反应环境下KOH的催化作用更加明显。提高反应压力可以促使煤转化率和气体产率升高。与KOH添加量和温度相比,停留时间对H_2产率的影响较小,随着停留时间的延长,CH_4产率略有增加。     

低阶煤催化热解研究进展

煤热解是煤热转化过程中最先和必经的阶段,受热分解为煤气、焦油及半焦/焦炭三相产品.基于煤(催化)热解可实现低阶煤的高效分质利用,对煤催化热解机理、不同种类催化剂及在煤热解中的应用、煤催化热解的影响因素进行了阐述,同时对低阶煤催化热解的发展进行展望,期望开发出煤热解反应条件温和化、热解转化率更高、热解焦油轻质化及可对目标...     

韩家湾煤及其热解半焦中多环芳烃分布特征研究

低阶煤的热解是其深加工工艺的基础，为探究其固体产物半焦中多环芳烃(PAHs)的含量水平及组成特征，以陕西榆林韩家湾次烟煤及其不同温度条件下(350℃～700℃)生成的热解半焦为样品，采用溶剂萃取结合GC/MS方法分析其中PAHs分布特征。结果显示：韩家湾原煤中16种优控母体(美国环保署规定)PAHs含量(∑16PAHs, 15 161 ng/g)低于对应烷基取代PAHs含量(∑aPAHs, 24 055 ng/g),380℃热解半焦中∑16PAHs(19 003 ng/g)和∑aPAHs(45 009 ng/g)均呈极大值；半焦中∑16PAHs和∑aPAHs随温度呈先增后降的变化趋势，但aPAHs含量随热解温度变化的幅度大于16PAHs含量变化的幅度，推测热解过程释放的PAHs可能以aPAHs为主；16PAHs组成上，原煤以4环母体PAHs为主,半焦中则以2～3环PAHs为主；350℃～400℃热解半焦中萘和烷基萘含量显著高于原煤中相应成分的含量，表明煤在低温热解时发生裂解反应并生成大量萘系物。     

煤热解技术及其运行影响因素分析

系统阐述了低阶煤热解的基本过程以及低阶粉煤气固热载体双循环快速热解技术（SM-SP）的优势,探讨了煤热解反应的影响因素：原料煤性质、煤样粒径、热解温度、热解升温速率、热解压力、停留时间、气速、粉焦循环量等,并对煤热解技术的发展前景进行了展望。     

大河矿树皮残植煤热解特性及焦油组成研究

采用固定床热解及TG/DTG分析研究了晚二叠世龙潭组树皮煤热解过程中不同热解因素与产物组成的相关性,利用GC/MS系统研究了树皮体含量为40%的大河矿树皮煤和黄陵气煤低温热解焦油(530℃)组分的差异。结果表明,树皮煤热解产物组成与热解终温显著相关,与保温时间和升温速率的相关性较小,在530℃、60 min、8℃/min条件下热解焦油产率最大,该焦油主要由烷烃、萘、苯、芳烃和酚等45种有机物组成,分子中含9～16个碳的有机物含量占78.05%。同条件下,与黄陵气煤热解焦油相比,其高分子有机物和含氧有机物含量显著降低。两种焦油中碳数≤16的有机物含量分别为90.042%,77.924%,表明低阶煤低温焦油以轻质油为主,树皮体含量高有助于提高轻质油产量。     

Changes in free radicals in coal-derived pyrites upon heating in N2, H2, and vacuum: Role of pyrite—pyrrhotite conversion

Through electron spin resonance (e.s.r.) studies, three different kinds of free radicals have been identified in pyrite samples containing coal impurities. Changes in the e.s.r. parameters (g-value, linewidths, and concentration n) of free radicals have been monitored as the coal-derived pyrites are heated in different atmospheres (vacuum, N₂ and H₂) from room temperature to 500°C in 50°C steps for a residence time of 30 min at each temperature. Changes in n (concentration/g) and other parameters begin to occur at 300°C in vacuum, at 200°C in N₂, and at 100°C in H₂ amtospheres. At these temperatures conversion of pyrite to pyrrhotite is also observed to occur. It is argued that the enhancement of n in these samples is related to the conversion mechanism of pyrite to pyrrhotites. The maximum relative increase in n follows the sequence n (vacuum)>n(N₂)>n(H₂). At high temperature n decreases due to recombination of free radicals formed so that at 500°C, all three types of radicals have small but equal concentrations.     

N2气氛下温度和压力对煤热解的影响

研究煤热解的反应特性有助于提高煤热解的转化率和焦油收率并且能够改善焦油的品质。本文在固定床反应器上研究了N₂气氛中,不同压力和温度下的唐山烟煤热解反应,考察了温度和压力对热解失重率、热解气体组成及液相产物产率的影响规律。结果表明当热解压力由1MPa增加至3MPa时,唐山烟煤的失重率和焦油产率均先增加后降低,在2MPa时达到最大值。当温度低于600℃时,压力不影响CH₄、H₂和CO的收率,当温度超过600℃时,CH₄、H₂和CO的收率随热解压力的升高而降低。随着热解温度的升高,煤热解的失重率、水的产率以及CH₄、H₂的收率不断增大,焦油的收率和CO的收率先增大后降低,在2MPa下600℃时焦油的收率达最大值为9.23%。     

Free radicals in coal and coal conversions. 5. Methodology for the in-situ investigation of free radicals in coal depolymerization under SRC-II preheater/reactor conditions

In a continuing series of publications, a systematic investigation of the free radicals during coal depolymerization under SRC-II preheater/reactor conditions has been made. A uniquely designed electron spin resonance (e.s.r.) cavity allows the monitoring of free radicals and how they are affected by residence time, temperature and pressure changes. This paper summarizes the methodology that has been developed to study systematically free radical formation and behaviour in-situ during coal liquefaction. The methodology involved is to be used extensively in subsequent papers that examine in detail the manifold parameters that affect coal depolymerization. Also, results are given on the dependence of free radicals on temperature, pressure and gases in the presence of tetralin. The free radical concentration can be measured 3–4 min after the initiation of the heating process to an accuracy of ± 20%, while the process variables may cause several-fold changes in the free radical concentration.     

水稻秸秆制备活性炭吸附剂工艺研究

以水稻秸秆为原料、氢氧化钠为活化剂制备活性炭。结果表明水稻秸杆活性炭的最佳工艺条件:碱碳比为2∶1,活化时间为60 min,活化温度为600℃,碳化温度为350℃,在此工艺条件下制备的水稻秸秆活性炭的亚甲基蓝吸附值和碘吸附值分别为29.2 mL/0.1 g和1 706.98 mg/g,制备出的活性炭吸附剂质量指标接近水质净化用活性炭标准。     

Free radicals in coal and coal conversions. 6. Effects of liquefaction process variables on the in-situ observation of free radicals

To determine the effects and relative importance of process variables in coal liquefaction, a uniquely designed and fabricated high-pressure/high-temperature electron spin resonance (e.s.r.) apparatus is used to monitor the in-situ formation and behaviour of free radicals, which are generally assumed to be the key factor. It is concluded that the temperature is the most significant single process variable that affects free radical formation; for Powhatan No. 5 coal there is a 9-fold increase in going from 400 to 460 °C. At 460 °C the other process variables tested can affect significantly the free radicals significantly, but at 400 °C these variables have essentially no effect on free radicals formation. The next most significant effect is due to the combination of solvent nature and residence time. Tetralin and the SRC-II heavy distillate quench the free radicals from Powhatan No. 5 to the same extent with one significant difference. In tetralin the maximum concentration is observed shortly after the slurry achieves its highest temperature, whereas in the SRC-II heavy distillate experiments the concentration is still increasing, at 460 °C, even after 1 h of reaction. The heating time, pressures and types of gas used affect the free radical concentration to a much smaller extent. The conversions obtained in the in-situ e.s.r. experiments using SRC-II heavy distillate as the solvent are somewhat lower than those obtained with tetralin as the solvent. The corresponding oil yields with tetralin are considerably higher than with SRC-II heavy distillate.     

胜利褐煤液化初期反应动力学研究

为研究胜利褐煤在初始阶段的煤液化反应动力学,在可快速升降温的微型高压釜中对胜利褐煤进行了加氢液化反应,得到了反应初期煤液化参数,并对胜利褐煤加氢液化反应初期的动力学行为进行分析。结果表明,虽然反应器升温速度较快,但到达反应温度时,仍有一定量的煤发生了转化,在反应温度440℃、反应时间为0时转化率达到28.12%;在较低温度下,胜利褐煤只发生了部分热解反应,反应后期几乎不再转化,在380℃、反应10 min后转化率已达28%,后续基本不变;随着反应温度的升高,反应转化率、油水产率、气产率等指标增大,反应前10 min增速较快,10~25 min时反应速率减缓,主要是沥青烯组分作为中间产物不断向油转化,速率较低。     

Free radicals in coals and coal conversion. 4. Investigation of the free radicals in selected macerals upon liquefaction

This study of the nature and role of free radicals in coals and coal conversion considers free radicals from selected macerals in the liquefaction process. High-purity macerals were liquefied to different extents at high temperature (425–480 °C) in the presence of naphthalene or tetralin and hydrogen or nitrogen. The initial concentrations of free radicals as well as the residual concentrations have been measured. The dependence of free radical concentrations on solvents, gases, and temperature is reported. Resinites show the least number of free radicals. They also liquefy almost completely under all conditions used. Fusinites have the highest concentration of residual free radicals and they are unaffected by solvent, gas or temperature changes: The vitrinites show intermediate free radical concentrations that depend very strongly on the solvent used, and on the temperature, but they are unaffected by the gas used. A correlation has been established between free radical concentration and degree of conversion.     

响应面法优化超声辅助银杏叶中黄酮的提取及其抗自由基活性研究

目的 对银杏黄酮的提取工艺进行优化,并对其清除自由基活性进行研究;方法 通过响应面法优化乙醇浓度、提取温度、超声时间、液固比对产率的影响,体外清除自由基对抗氧化性进行研究;结果 当乙醇浓度为75%、超声时间控制为2 h、提取温度为80 ℃、液固比为30时,提取产率最高为2.82%,抗自由基结果表明,反应时间10 min清除率趋于稳定,银杏黄酮加入量1.00 mL,抗自由基活性高达68.9%; 结论 银杏黄酮具有较强的抗自由基活性,可以作为食品药品或者美容产品的添加剂.