几种年轻煤在氮热等离子体中的热解

研究了几种中国年轻煤在氮电弧热等离子体中的热解行为,考察了煤的基本性质、煤的粒度及加煤速率等条件对煤热解特性的影响.结果发现,煤在氮等离子体条件下热解所得气体产物中的主要成分是氢、乙炔、一氧化碳和丙炔腈,此外还有甲烷和乙烯等小分子烃.乙炔的收率随煤种的不同和操作条件的变化而波动.煤中的挥发分含量愈高、加煤速率愈低,乙炔收率则愈高.其中扎赉诺尔褐煤的乙炔收率最高可达22.3%(以煤中碳为基准);原料煤在氮等离子体中热解后,除部分芳香C—C键得以保留外,煤有机结构中的外围官能团全部消失,同时在热解半焦中有新的氮基官能团(如—C(?)N)引入.     

煤热解特性研究

对大雁、协庄和昔阳3个不同煤化程度的煤样，在N2，CO2和水蒸气3种不同气氛及不同温度下进行了热解研究，考察了煤化程度、热解气氛和热解温度对煤热解产物产率和热解气性质的影响规律．研究表明，对上述3个煤样，随煤化程度加深，焦产率增加，油和气产率一般随煤中挥发分增加而增加，但又与煤的大分子结构、热解温度和加热速率等有密切关系；干馏气组成H2和CH4含量协庄煤样最高，而(CO CO2)含量因煤中氧含量的降低而下降．与N2气氛相比，CO2和水蒸气气氛中半焦产率下降，气产率增加；油产率水蒸气气氛下最高．H2组分含量在水蒸气气氛下最高，而CO，CH4和烃类C2～C5组分则最低．LHV在N2，CO2和水蒸气气氛下逐次降低．     

TPD技术在煤／半焦气化研究中的应用

本文综述了近年来国外用程序升温脱附(TPD)技术在煤／半焦气化研究中的应用，着重讨论了担载金属半焦在含氧气化剂作用下碳-氧-金属之间的相互作用，H2O和CO2脉冲气化后的TPD可以分析担载不同金属盐类后脉冲气化所生成的H2，CO和CO2．一般来说。随担载金属量的增加．其反应掉的H2O和CO2量增加，生成的CO和H2增加。从碳和CO2及H2O的气化反应的氧平衡可以求出在反应过程中吸附在试样表面的氧量，由表面含氧络合物的形态和含量可以分析碳和金属与氧的相互作用，氧迁移机理及催化活性的大小等重要问题。     

等离子体热解煤制乙炔工程化过程中的关键问题

从等离子体热解煤制乙炔的特点出发,总结了国内外的研究现状,探讨了煤种、气氛及淬冷3个因素对乙炔收率和能耗的影响,结果表明:挥发分在25%￣40%、氧含量低、H/C比较高的煤种有利于乙炔的生成;在惰性气体中引入氢气可以提高煤的转化率和乙炔的生成率;淬冷能够促进生成乙炔的反应、提高乙炔的收率、降低反应能耗,并分析了实现工业化过程中需要解决的几个关键问题。     

氢/氩热等离子体裂解煤碳-氢-氧-氩多相多组分体系的热力学分析

采用Gibbs自由能极小化法对等离子体裂解煤制乙炔碳-氢-氧-氩多相多组分体系的化学反应平衡组成进行了计算,结果表明,在C-H-Ar平衡体系中,惰性组分氩的存在降低了乙炔的最高平衡产率,氩在5000 K以下基本不电离,典型组成为C:H:Ar=1:13.39:0.6的液化石油气裂解反应体系的最佳反应温度区间为2800~3200 K. 在C-H-Ar-O多相平衡体系中,氧作为杂质同样降低了乙炔的平衡产率,体系中氧以CO的形式存在,典型组成为C:H:O:Ar=1:8.638:0.160:3.339的煤裂解反应体系的最佳反应温度区间为3000~3200 K.     

含油污泥混煤热解动力学及气体产物分析

采用热重分析法在不同掺混比例、不同升温速率和不同掺混煤种下对含油污泥混煤进行热解实验研究,并通过气相色谱仪分析热解产生的气体产物.结果表明,含油污泥混煤的热解失重过程可以分为水分及吸附气的挥发、轻烃的析出、重烃的裂解和煤小分子链脱除、重烃的二次裂解和煤大分子链脱除、半焦的缩聚反应以及无机矿物质的分解5个阶段.进行热解动力学分析,采用Coats-Redfern积分方法求解含油污泥混煤的热解动力学参数,并得到了掺混比例、升温速率、煤种对动力学参数的影响规律.利用气相色谱仪检测生成的气体产物有H2,N2,CO2,CO,CH4,C2H6,C2H4,C3H8和C3H6等,并分析了主要气体产物H2,N2,CO2和CH4的生成规律.     

等离子体裂解煤过程中影响乙炔收率因素的探讨

综述了在等离子体裂解煤生产乙炔过程中，反应装置，操作条件，煤的特性以及急冷对煤转化率和乙炔收率的影响，探讨了提高乙炔收率和煤转化率的有效途径。     

煤与木屑共液化号体产物分析

采用500mL带搅拌的高压反应釜,考察了煤与木屑共液化反应,分析了气体产物分布及变化规律。实验结果表明：木屑单独液化气体产率远远高于胜利褐煤单独液化气体产率;木屑的加入降低了共液化气体总产率,尤其对液化气体中CH4,C2H6含量影响比较显著,对CO和CO2含量的降低影响不明显;在煤与木屑共液化过程中,总气体产率、C1～C4烃类气体及CO＋CO2非烃类气体基本均随着温度的升高逐渐增加,尤其在360～420℃增加幅度较大;液化气体产物组成以C1～C4烃类气体为主,且以CH4含量最高,高低次序为CH4〉C2H6〉C3H8〉C4H10另外还有少量C2H4,非烃类气体主要是CO和CO2。     

CO〈sub〉2〈/sub〉抑制煤氧吸附过程的实验研究

煤对CO2的吸附能力较强,CO2分子会优先吸附在煤表面,减少O2的吸附量,抑制煤氧吸附过程。通过程序升温实验,研究CO2对煤氧吸附的抑制作用,测定煤样在不同CO2浓度下产生O2、CO、CH4的浓度值,分析CO2浓度对耗氧速率、CO产生率的影响规律。结果表明,37%～50%浓度的CO2对煤体耗氧速率的抑制效果明显,对煤样的CO产生率及甲烷浓度有降低作用,说明CO2能够有效抑制煤氧吸附过程,防止煤炭氧化自燃的发生。研究结果对CO2防灭火技术的开发与应用具有指导作用。     

CO2抑制煤氧吸附过程的实验研究

煤对CO2的吸附能力较强,CO2分子会优先吸附在煤表面,减少O2的吸附量,抑制煤氧吸附过程。通过程序升温实验,研究CO2对煤氧吸附的抑制作用,测定煤样在不同CO2浓度下产生O2、CO、CH4的浓度值,分析CO2浓度对耗氧速率、CO产生率的影响规律。结果表明,37%~50%浓度的CO2对煤体耗氧速率的抑制效果明显,对煤样的CO产生率及甲烷浓度有降低作用,说明CO2能够有效抑制煤氧吸附过程,防止煤炭氧化自燃的发生。研究结果对CO2防灭火技术的开发与应用具有指导作用。     

太阳能煤气化技术及发展前景

通过太阳能水煤气实验,研究了温度、反应物成分、气流速率等因素对煤气转换率的影响。经多次实验测得混合气中H2,CO和CO2的组分比,结果表明:温度较低时,反应不稳定,H2转化率较高,生成少量CO;随温度升高,H2转化率缓慢降低,CO和CO2相互转化明显,在1000～1050℃范围内煤炭转化率最高,近似99%,其中H2约占49%。在煤气转化过程中,升高温度可显著提高反应速率和有效气体的转化率;降低氧气含量可使反应简单,促进水煤气变换反应的持续进行,可进一步提高煤气生成率。     

Relation between coal properties and acetylene yield in plasma pyrolysis

If coal is injected into hydrogen plasma generated by arc discharge the volatiles are released within a few milliseconds and form acetylene as the main product by reaction with the plasma. Experiments with different coals indicate that the yield of acetylene is determined not only by the amount of volatiles but depends also on their composition. Oxygen compounds in the coal and, in some cases, even the oxygen content of the mineral matter decrease the acetylene yield.     

Pyrolysis of brown coals. 3. Effect of cation content on the gaseous products containing oxygen from Yallourn coal

A study has been made of the evolution of water, carbon dioxide and carbon monoxide during the pyrolysis of Australian Yallourn brown coal, and of the way in which the evolution is influenced by exchange of the carboxyl groups in the coal with magnesium and barium cations. Virtually all the oxygen in the coal can be removed as carbon dioxide, water and carbon monoxide with the greatest rate of loss occurring at 300, 350 and 500 to 600 °C respectively. Increasing levels of cation alter the proportion of the volatile constituents but not the total amount of volatile matter evolved. Increased evolution of oxygen as carbon dioxide from a magnesium-form coal over that from acid-form coal is accompanied by a decrease in the amount evolved as water and carbon monoxide. Barium-form coals, however, show an increase in the amount of carbon monoxide evolved as the cation content increases. This is due in part to reactions involving the nitrogen gas used to provide a non-oxidizing atmosphere during pyrolysis. These reactions do not occur with magnesium-form coals. The amount of char formed by pyrolysis is the same for different levels of cation exchanged on the carboxyl groups. The results support conclusions that the carboxyl groups in a brown coal are associated with other oxygen groups, and that the mode of decomposition of the groups in this association (including carboxyl) is altered by the exchange of the carboxyl groups with cation.     

EXPERIMENTAL STUDY OF THE SELECTIVE HYDROGENATION OF STEAM CRACKING C2CUT. FRONT END AND TAIL END VARIANTS

Selective hydrogenation is the habitual industrial process to eliminate the most unsaturated hydrocarbons, which are harmful for later applications. In this paper, the kinetics of the selective hydrogenation of a C₂ mixture over two palladium/alumina catalysts with both front end and tail end variants, have been studied. Experiments have been carried out to analyse the influence of temperature, hydrogen/acetylene molar ratio, carbon monoxide content in the feed and hydrocarbon volumetric flow rate on the corresponding conversion and selectivity.

The experiments were performed in an integral plug flow reactor and the integral method was used for the kinetic analysis. The minimization of the objective function was made by the Marquardt algorithm for multiple response and the continuity equation set integrated by fourth order Runge-Kutta technique.

The most adequate models were the power law type for the experimental range. The comparison between experimental and observed values of the acetylene and ethane molar fraction in the hydrocarbon mixture, which are used for minimization, confirm the suitability of the fit.     

淮南煤气化工艺过程模拟

采用Aspen Plus软件对淮南煤气化进行了稳态流程模拟研究,结果表明:O2流量的增大导致气化温度快速升高;合成气中CO、H2以及有效合成气(CO+H2)的体积分率随O2流量的增加呈先增大后减小的趋势;CO2和H2O的变化趋势则相反。氧煤比在0.03~0.17kg/kg区域内,有效气体积分率均大于60%;且在氧煤比为0.1kg/kg时,有效合成气体积分率达到最大值64.2%。氧煤比在0.06~0.14kg/kg区域内,汽氧比的增大会导致气化温度随之减小,并直接影响合成气组分。合成气中,CO、H2、CH4以及有效合成气(CO+H2)的体积分率随汽氧比的增大而降低;H2O和CO2体积分率则随之增大。     

Products from the rapid pyrolysis of a brown coal in inert and reducing atmospheres

Yallourn brown coal and its calcium form have been pyrolysed in three different gas mixtures: 23% methane in argon, 50% hydrogen in argon, and 9.4% toluene in argon, at heating rates of 10⁷Ks^?1 and residence times of ≈2 ms. The products have been compared with those obtained in pure argon. The highly reactive molecule, ketene, was detected in the pyrolysate gases from both the ‘raw’ and calcium-form coals when pyrolysed in the above mixtures. Ketene was not detected in the pyrolysate gases, however, when the coals were pyrolysed in argon alone. When pyrolysed in 23% methane/argon the maximum yield of carbon monoxide from the ‘raw’ coal was found to be much lower than when pyrolysed in pure argon. The fully exchanged calcium-form coal when pyrolysed in pure argon, gave a maximum yield of carbon dioxide of oxygen content equal to the total oxygen content of the carboxyl groups originally present in the coal; the C0₂ yield from the ‘raw’ coal was about half that from the calcium-form in pure argon.     

煤制乙炔关键中间体BaC2合成的热力学分析

煤制电石(CaC₂)乙炔工艺在我国煤化工行业中占有重要地位。但其关键中间体CaC₂的工业生产过程具有反应温度高、能耗大、CO₂排放严重等问题,严重制约了电石及下游相关产业的发展。开发绿色环保的煤制电石替代工艺具有重要意义。本研究提出采用BaC₂替代CaC₂作为煤制乙炔工艺的关键中间体,从热力学角度分析了BaC₂合成反应体系的特点,并在1550℃进行了合成BaC₂的实验验证。结果表明,以BaC₂替代CaC₂为煤制乙炔的关键中间体、通过BaCO₃-BaC₂-Ba(OH)₂-BaCO₃的钡循环将碳和二氧化碳转化为乙炔和一氧化碳的新路线,具有反应温度低、零CO₂排放、联产CO、固废排放少等优点,可以为现代煤化工的绿色发展提供新的思路。     

煤新型气化的气体参数分析

利用自行发明的多热源电热气化炉，以煤和天然石英砂为原料合成煤气，同时伴生大量副产品SiC新材料．研究表明，煤气中以CO气体为主，平均含量可达78．5％，CO＋H2平均含量达85％，CO＋H2＋CH。平均含量达87．5％．实验分析了两种煤气化后合成气组成、酸碱性、气体流量和炉内气体压力等参数，研究了合成气组成随气化工艺的变化规律，探讨了装炉工艺和保温料厚度对气体流量和炉压的影响．