煤的加氢热解

煤的加氢热解是目前受到充分关注的新的煤转化途径。本文详细讨论了煤加氢热解技术的装置(反应器部分、回收与分析系统部分)、研究成果和最新研究动向。     

煤与油页岩热预处理特性及对热解的影响

对比研究了神木煤和桦甸油页岩在150~400℃热预处理时的孔隙变化和挥发分析出规律以及热预处理对后续慢速升温热解反应产物的影响。结果表明,热预处理显著增加了油页岩的孔隙结构,其比表面积提高4倍、孔体积提高5倍以上,而神木煤的孔隙结构则减少了,特别是孔径大于1 nm的孔体积减少了近60%、比表面积减少了近80%,而其1 nm以下的孔则相对稳定,孔体积和比表面积分别只减少了10%左右。低于400℃时热预处理过程中除脱去吸附水外,其他挥发分也有一定析出,并以CO₂为主,另有少量CO,但挥发分总失重量不超过5%。固定床慢速升温热解研究表明,经热预处理后,油页岩的油产率最高提高了22.7%,而水和气的产率则相应降低,气体中CH₄增加而H₂降低。热预处理对煤的热解油产率影响不明显,但热解水产率降低而热解气产率增加且其中CH₄增多而H₂降少。     

煤直接液化加氢工艺氢气系统优化研究

介绍了煤直接液化加氢工艺的氢气需求和为提高氢气利用率所采取的措施。该工艺采用两套煤气化制氢、一套天然气制氢和一套重整装置制氢为煤炭液化和液化油品加氢等提供所需的氢气。煤直接液化装置采用膜分离系统将循环氢中的氢气含量从86%提高到96%。同时,采用变压吸附装置(PSA)回收煤直接液化加氢工艺的富氢排放气中的氢气。因膜分离系统受原料制约,其使用效率随运行周期逐渐降低,致使氢气回收率下降、尾气中氢气含量逐渐升高,即降低了膜分离效率,又增加了后续PSA运行能耗;各工段塔顶气经过轻烃回收后所产干气含氢量在49～61%之间,氢气没有得到有效回收利用,直接进入燃料气管网用于燃烧加热,造成了氢气的浪费。因此膜分离系统进行优化配置、干气系统进行氢气回收,对提高煤直接液化加氢工艺的氢气利用率及整个工艺过程的节能降耗具有重要意义。     

气氛及溶剂预处理对煤热解行为的影响

<正>近年来由于石油资源短缺,煤热解生产低温煤焦油受到越来越多的关注[1]。现有热解技术普遍存在析出物产率低的问题。如何通过改变工艺条件及预处理提高热解析出物产率成为热解研究的核心问题。杨会民等[2]研究发现CO2气氛可以影响热解气相产物的释放特征。研究者[3,4]在不同气氛下进行热解发现,CO2的存在对焦油的生成有抑制作用。由于煤分子结构既有供氢能力,又有受氢能力,因此在供氢溶剂作用下能打破或消弱分子间的氢     

提高煤加氢热解焦油产量的途径分析

结合煤加氢热解最新研究进展，从煤加氢热解焦油形成机理出发，综合论述了提高热解焦油产量的６条途径和方法。提出煤－焦炉气催化加氢热解的新构想，以期实现“煤→热解煤气内循环→焦油”新工艺。     

焦炉气气氛下煤加氢热解研究进展

煤－焦炉气共热解是力图降低传统煤加氢热解工艺投资和工业运转 和的新工艺，近年来已引起人们广泛注意。本文平述了近期国内外利用焦炉气代替氢气作煤加氢热解反应气工艺的可行性以及热解温度和焦炉气组分对热角产品影响方面的研究进展。     

还原性气氛下煤中硫热解迁移规律 (Ⅱ)氢气气氛与煤半焦中有机硫反应的动力学研究

在常压固定床反应器上考察了氢气分压对煤热解残焦中硫释出的影响,并通过差减微分法求取了反应的宏观动力学参数.研究结果表明:不同的氢气分压对反应具有一定的影响.氢气分压在0.02 MPa～0.1 MPa范围内,较高的氢气分压条件下,煤焦中有机硫与氢气的反应速率较快.通过动力学计算得出:不同的氢气分压下对应的反应级数、活化能和指前因子均不相同.实验结果表明,氢气与热解残焦中硫的作用是一个复杂的过程,反应过程可能受气体扩散控制.     

氧化预处理法提高煤中全硫脱除率的研究

采用Ｂｏｘ－Ｗｉｌｓｏｎ实验设计方法进行了用过氧化氢氧化预处理ＩｌｌｉｎｏｉｓＢａｓｉｎ煤（ＩＢＣ－１０８煤）和用甲酸除预处理煤中全硫的研究。实验中选用２了四个过程变量；氧化预处理阶段过氧化氢的用量、脱硫阶段温度、时间和甲酸用量。结果表明：Ｅ和过氧化氢对煤进行氧化预处理能明显提高煤的脱硫效果；煤中硫的脱除率随过氧化氢 增加而提高。在本实验条件下，煤中全硫的最大相对脱除率经为７４．２％，其中有机硫的     

工艺参数对高硫煤加氢热解脱硫率的影响

An orthogonal experiment design was adopted for studying the macroscopic reaction kinetics of sulfur removal of high sulphur coal hydropyrolysis. The experimental data of reaction desulfurization rate were analysed by margin and variance analyses. The optimal sulphur removal reaction conditions were recommended.     

高硫强粘结性煤高温热解脱硫的研究

就高硫强粘结性煤与生物质在回转炉内共热解。研究了热解温度和煤种对无机硫脱除率、有机硫脱除率、硫和氮含量的影响。结果表明,随着煤化度的增高,脱硫和脱氮率降低,１２００℃左右脱硫和脱氮率明显增大,１６００℃煤中无机硫脱除率达９３％￣９８％,有机硫脱除率达８０％￣９５％,煤和生物质脱氮率达８５％￣９３％。     

大同煤热解和加氢热解过程中产物生成规律的研究

在压力2MPa,温度350—650℃范围内,对比研究了大同煤分别在氮气和氢气气氛下热解过程中产物的分布和气体生成规律。研究表明,煤的热解和加氢热解转化率和水产率都随温度上升而增加;在热解条件下,焦油产率在500℃出现最大值。氢气对煤热解转化只有超过一定温度才具有促进作用,此时与热解相比具有较高的CO、CH4和C2^＋产率以及较低的CO2产率。     

Hydropyrolysis of a high-sulphur-high-calcite Italian Sulcis coal. 1. Hydropyrolysis yields and catalytic effect of the calcite

Hydropyrolysis (HyPy) of a high-sulphur (4.3 wt% mf) and high-calcite (7.3 wt% mf) subbituminous coal (Sulcis coal) has been studied in a semi-batch fixed-bed reactor under a pressure of 1 or 3 MPa from 580 to 850 °C. The maximum temperature attained is not necessarily the temperature that the reactor is set but depends on the pressure and nature (reactive or not) of the gas; this phenomenon is due to the heat from the exothermic HyPy reaction. There is a correlation between the amount of heat released during the hydrogénation and the amount of water formed. The maximum conversion obtained is 62.5 wt% maf under H₂ at 3 MPa and 850 °C. The char, oil, water, gas (CH₄, C₂H₄, C₂H₆, CO, C0₂) yields and the oil analysis are reported. A significant proportion of the C0₂ evolved during the reaction results from the decomposition of the mineral matter rich in carbonates. A proportion of the CO evolved results from the degradation of phenols, a reaction which is catalysed by calcite and/or lime, and as a consequence the oil yield is reduced.     

氢气在煤液化反应中的作用

综述了近年来关于煤液化反应中氢气的作用及供氢机理方面的研究成果 ,并介绍了提高煤液化中活性氢的方法。     

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.     

Hydropyrolysis of a high-sulphur,high-calcite Italian Sulcis coal: 3. Pyrite behaviour

The chars obtained from hydtopytolysis of Sulcis coal were examined by scanning electron microscopy coupled with an energy dispersion analyser. Under 3 MPa of He at 540 °C, pyrite is transformed into FeS_1.5. Under H₂ pressure, pyrite reduction depends on the temperature. At 780 °C, pyrite is completely reduced to iron. The complete reduction is made possible because the H₂S formed reacts with the caleite of this coal and thus does not limit the reducing reaction.     

油酸包覆型Fe_2O_3对铁厂沟煤加氢热解特性的影响

采用固定床反应器考察了干混法添加油酸包覆型Fe2O3对煤加氢热解特性的影响,并与添加常规Fe2O3进行比较。对其催化作用下得到的半焦进行了TG、BET和XRD表征,焦油进行GC模拟蒸馏分析。结果表明:(1)采用常规Fe2O3考察铁的添加量时,在添加量为5%时焦油产率最高,由不加催化剂时的14.3%提高到16.3%。添加油酸包覆型Fe2O3时,煤的热解转化率更高,焦油产率由不加催化剂时的14.3%提高到18.0%。(2)添加油酸包覆型Fe2O3和常规Fe2O3得到的半焦反应性基本相同,半焦的孔结构则是添加油酸包覆型Fe2O3时最发达;添加油酸包覆型Fe2O3的半焦表面Fe晶粒的直径28 nm,小于添加常规Fe2O3的半焦表面Fe晶粒的直径39.5 nm。(3)加入常规Fe2O3和油酸包覆型Fe2O3都使得焦油品质得到提高,但两者相比,常规Fe2O3作用下得到的焦油品质更高。     

混凝法预处理煤气化废水实验研究

采用絮凝沉降的方法,以硫酸为破乳剂,聚合氯化铝作无机絮凝剂,搭配使用有机絮凝剂聚丙烯酰胺,将煤气化废水进行预处理,显著降低了固体悬浮物含量和含油量。经加热蒸氨处理后,除油率达到85.5%,SS质量浓度降到25.9 mg/L,为生化处理提供了一个较清洁的环境。因脱酚率不高,后续生化处理需配合采用酚氨回收工艺。     

Hydropyrolysis of a high-sulphur-high-calcite Italian Sulcis coal. 2. Importance of the mineral matter on the sulphur behaviour

The sulphur distribution among the char, oil and gas obtained after hydropyrolysis of a high-sulphur (4.3 wt%) and high-calcite (7.3 wt%) coal has been investigated. The chars were examined by scanning electron microscopy coupled with an energy dispersion analyser and by X-ray diffraction. The proportion of the combustible and non-combustible sulphur in the char has been determined. Hydrogen pressure promotes reaction with sulphur but the sulphur content of the chars increases from 3 to 4.5 wt% when the temperature is increased from 616 to 845 °C. This increase in sulphur is a consequence of the reaction between hydrogen sulphide, produced during hydropyrolysis of coal, with the alkaline-earth mineral matter to produce alkaline-earth sulphide. The SEM and X-ray diffraction images show that in the char formed at 780 °C the sulphur, calcium and magnesium are localized in the same compounds. This is not the case when hydropyrolysis is performed at lower temperature. Combustion of the chars produces only <0.6 S0₂ MJ^?1 compared to 2.2 g S0₂ MJ^?1 for untreated coal. X-ray diffraction has shown that the sulphur in the char is oxidized and fixed in the ashes mainly as CaS0₄ and also some as MgS0₄. Although sulphur remains partly in the chars after hydropyrolysis, 75% of it is non-combustible. The hydropyrolysis of a high-sulphur coal containing calcite, produces a char which may be used as a clean fuel.     

铁基催化剂对煤加氢热解和半焦结构的影响

应用固定床反应器研究了铁基催化剂Fe2O3、Fe S、Fe（NO3）3对伊犁南台子煤催化加氢热解产物分布和半焦结构的的影响。结果表明：添加铁基催化剂后,加氢热解中气产率增加最大为17.78个百分点,半焦产率下降最大为21.41个百分点。利用BET法对半焦进行了结构分析,结果发现,添加Fe（NO3）3后所制得的半焦的比表面积和总孔体积分别为不添加催化剂所制得的半焦的6倍和1.7倍。从TG和DTG图中发现,加入铁基催化剂后,半焦活性增加,其中Fe（NO3）3的作用最明显,热失重速率最大,说明半焦活性较大。