煤气化技术进展

介绍近年来国内外开发的几种先进煤气化技术以及变压吸附制氧工艺在富氧气化炉上的应用情况。     

煤气化过程中钙催化作用的研究进展

煤的催化气化在国内外已被广泛研究, Ca作为一种对煤气化反应具有催化作用的碱土金属催化剂也受到许多研究者的关注。本文总结了可作为煤气化反应催化剂的Ca的类型, 论述了Ca催化煤气化反应的机理, 分析了影响Ca催化作用的主要因素, 指出当Ca与其他物质共同作为煤气化反应的催化剂时, 往往可以产生协同效应, 更有效地催化煤气化反应的进行。同时提出了今后在Ca催化煤气化反应方面所应进行的研究内容, 认为进一步探讨Ca在煤气化反应过程中发生的催化机理, 开发使用廉价的石灰石、熟石灰, 并且与其他物质, 尤其是纸浆黑液共同作为煤气化反应的催化剂很有必要。     

High Catalytic Performance of Fine Particles of Metallic Iron Formed from Limonite in the Decomposition of a Low Concentration of Ammonia

Catalytic NH₃ decomposition with limonite rich in α-FeOOH has been studied as a hot gas cleanup method to remove a low concentration of NH₃ from fuel gas produced in coal gasification. Fine particles of metallic Fe formed from α-FeOOH achieve the almost complete decomposition of 2000 ppm NH₃ to N₂ at 500°C under a high space velocity of 45,000 h⁻¹ and show the stable catalytic performance for 50 h. The predominant catalytic mechanism involving the formation and subsequent decomposition of Fe nitrides may be proposed on the basis of the XRD and TPD results.     

合成氨生产中型煤气化工艺条件的优化

从型煤气化在合成氨生产中的重要意义、气化特性、工艺条件优化、到型煤气化的不足之处与发展前景等方面,系统总结了合成氨生产中型煤气化技术。     

新河烟煤地下气化模型

为了探索烟煤地下气化过程的基本规律,为新河“煤炭地下气化发电示范工程”制定合理的工艺参数,测定了新河烟煤反应活性,并进行了富氧-水蒸气地下气化模型实验;研究了不同工艺条件下,出口煤气有效组分含量、热值的变化规律.实验结果表明,气化初期因煤层中含水,纯氧直接气化,可获得合格的煤气;在保持汽氧比在1.5∶1～2∶1之间时,新河烟煤采用富氧-水蒸气正向供风、辅助孔供风和反向供风连续气化可获得有效气体组分在70%、热值在10 MJ·m^-3左右的煤气;新河烟煤的产气率平均为1950 m³·t^-1,煤层气化率可达到74.6%.     

适宜"三高"煤利用的煤气化技术探讨

我国煤炭资源中高灰、高硫、高灰熔点煤(简称"三高"煤)所占比例较高,开发高效、洁净的"三高"煤加工技术对我国煤炭资源的可持续发展和利用有重要意义.本文通过对"三高"煤煤质特点进行分析,结合国内外发展较快的粉煤气化技术,综述了"三高"粉煤气流床气化的可行性,为促进"三高"煤高效、洁净利用提出了积极的建议.     

Reactive intermediate in the alkali-carbonate-catalysed gasification of coal char

Based on results from a variety of experimental measurements, a detailed mechanism is postulated for the action of the inorganic catalyst in char gasification. In this mechanism, a catalyst such as potassium carbonate in contact with char undergoes a chemical and physical transformation to form a molten potassium oxide film that covers the char surface. This film serves as an oxygen transfer medium between the gaseous reactant (H₂O or CO₂) and the char. At the catalyst/char interface, an oxidation-reduction reaction occurs and the anions in the catalyst react with the oxidized char to form a phenolate-type functional group that subsequently splits out CO. The anions are replenished by reaction between the oxidizing gas (H₂O or CO₂) and the oxide at the gas/catalyst interface. Net transport of oxygen from gas to char occurs by diffusion of the species in the molten catalyst film.     

Catalytic activity of coal minerals in water vapour gasification of coal

Possible catalytic influences of coal minerals during water vapour gasification of coal have been studied by kinetic measurements and microanalytical methods. A bituminous coal without and with various pretreatments and also model chars synthesized from PVC and PVC-sulphur mixtures were used as raw materials. Kinetic measurements were performed in a fixed-bed flow reactor at pressures between 0.2 and 2 MPa and temperatures from 880 to 1010 °C using hydrogen/water vapour mixtures as gasification agents. It was found that coal gasification at and beyond 880 °C can be decisively catalysed by the iron as constituent of mineral matter. Preconditions are elimination of inorganic sulphur and reducing atmosphere to stabilize elemental iron. The optimum pressure is in the range of 0.5 to 1 MPa. Scanning electron microscopy and electron probe microanalysis confirm that catalytic gasification starts as soon as the iron is free of sulphur. The organic sulphur of coal does not prevent but lowers the catalytic activity of iron.     

合成氨用煤气化技术浅析

阐述合成氨装置采用的几种煤气化技术情况,分析煤气化技术工艺过程和气化炉结构特点。建议根据原料煤和产品路线,以及需要综合考虑的因素,选择合适的煤气化技术。并介绍国产煤气化技术和装备来源及发展情况。     

Laboratory-scale coal reactivity testing for entrained gasification

A relatively simple and rapid micro-gasification test has been developed for measuring gasification reactivities of carbonaceous materials under conditions which are more or less representative of an entrained gasification process, such as the Shell coal gasification process. Coal particles of < 100 μm are heated within a few seconds to a predetermined temperature level of 1000–2000 °C, which is subsequently maintained. Gasification is carried out with either CO₂ or H₂O. It is shown that gasification reactivity increases with decreasing coal rank. The CO₂ and H₂O gasification reactions of lignite, bituminous coal and fluid petroleum coke are probably controlled by diffusion at temperatures 1300–1400 °C. Below these temperatures, the CO₂ gasification reaction has an activation energy of about 100 kJ mol^?1 for lignite and 220–230 kJ mol^?1 for bituminous coals and fluid petroleum coke. The activation energies for H₂O gasification are about 100 kJ mol^?1 for lignite, 290–360 kJ mol^?1 for bituminous coals and about 200 kJ mol^?1 for fluid petroleum coke. Relative ranking of feedstocks with the micro-gasification test is in general agreement with 6 t/d plant results.     

The british coal spouted fluidised bed gasification process

British Coal Corporation has been developing an air-blown spouted fluidised bed gasification process for the production of low calorific value fuel gas. Development of the gasifier at atmospheric pressure for the industrial market has established the commercial basis for a flexible gasification process, which can achieve coal conversion efficiencies of up to 95%. For larger-scale use, a pressurised gasifier is under development as part of an integrated partial gasification combined cycle, coal-fired, electricity generating system. Known as the British Coal Topping Cycle, the system offers significant advantages in terms of improved thermal efficiency, reduced generating costs and low environmental impact. The paper outlines the gasifier development programme for both applications.     

鹤壁烟煤地下气化模型试验研究

通过自行研制的煤炭地下气化模拟试验系统,采用富氧空气/水蒸气两阶段气化工艺,完成了鹤壁煤的地下气化模型试验。文章就试验不同阶段的煤气组成、热值变化和气化过程的稳定性特征进行分析,结果如下:鹤壁煤地下气化水煤气平均热值达11.85 MJ/m3,空气煤气热值为4—6 MJ/m3,水煤气中氢气最高体积分数超过80%,相应的煤气热值达到12.91 MJ/m3;适当增大鼓风量有利于高温温度场的快速建立与恢复,试验条件下,最佳鼓风量为20 m3/h,最佳蒸汽流量为0.26 m3/h。试验为煤炭地下气化制氢提供了有力依据。     

压力对煤气化反应的影响

为了提高煤气化效率,分析了影响产能的重要因素——压力。研究了压力对煤热解过程、煤焦燃烧速度及煤焦气化反应的影响。研究发现:加压热解情况下,挥发分和焦油产率均下降,但煤气产量增加,推测是因为焦油发生二次反应造成的。随着压力的增大,煤焦明显膨胀且比表面积下降。但过高的压力下,膨胀度减弱,易生成孔隙率高、薄壁的煤焦颗粒。提高O2分压,煤燃烧速度加快且生成的小颗粒较多。提高气化剂分压,煤气化速度加快,且蒸汽分解速度大于CO2还原速度,但生成的煤气对气化反应有抑制作用。     

激冷流程气化技术循环气压缩机设备布置的合理性分析

在全世界范围内已实现工业化生产的煤气化技术中,只有壳牌煤气化技术采用了激冷流程,由于该工艺在节能减排降本增效方面突出的优势,未来其他新型煤气化技术也存在采用此工艺的可能。分析和论述了以壳牌煤气化技术为代表的粉煤气化技术(激冷流程)的优势及其广阔的应用前景,着重对目前壳牌煤气化装置循环气压缩机的布置进行分析,对比国内现行的防火设计规范,论证了现有循环气压缩机的布置方案是满足国内现行设计规范要求的,为未来中国其他采用激冷流程的新型煤气化工艺的研究与发展奠定坚实的理论基础。     

Texaco煤气化工艺的影响因素

介绍了Texaco煤气化流程的特点,分别对影响工艺操作的煤种性质、煤浆浓度、气化温度和气化压力等方面进行了分析,对如何合理、有效利用煤炭资源以及气化炉如何能达到最佳的长周期稳定运行状态,具有一定的借鉴意义。     

沉降炉中粉煤气化的实验研究

以O_2为气化剂N_2为输送介质,在常压沉降炉装置上进行了几种粉煤的气化试验。试验考察了温度、氧碳比、停留时间对气化产气组成、碳转化率以及冷煤气效率的影响。     

H2O/O2气氛下胜利褐煤气化半焦的孔隙特性

采用实验室气流床反应器, 在H₂O、O₂及其混合气氛, 900℃条件下进行了胜利褐煤气化实验, 研究了气化半焦的孔隙结构特征。结果表明, 在所有气氛下, 半焦的吸附等温线均属于第II类型, 吸附回线为H3型, 褐煤气化半焦具有连续的较完整的孔体系, 孔隙结构类似。反应气氛影响气化半焦的孔径分布, 半焦中的大孔在3种气氛下均较少, 中孔从多到少的顺序是:H₂O > O₂ > H₂O+1%O₂, 微孔与之相反。在水蒸气气氛下, 随水蒸气浓度增加, 半焦的比表面积先增大后趋于稳定。添加1%O₂后, 比表面积提升30多倍。低浓度O₂气氛下, 随O₂浓度的增加, 比表面积呈线性增长。褐煤转化率与微孔容积和总孔容积的比值以及比表面积的关系式为X=0.196(V_m/V)+45.651, X=0.037S+48.066。     

煤气化残渣基多孔陶瓷的制备研究

为拓展煤气化残渣综合利用途径,提高煤气化渣的附加值,以工业固体废弃物煤气化残渣为主要原料,采用模压成型工艺,在较低温度下烧结制备了煤气化残渣基多孔陶瓷,着重研究了不同烧结温度对多孔陶瓷的机械性能、物相结构、孔隙率以及N_2通量的影响。结果表明,多孔陶瓷烧结物相主要以莫来石相和石英相为主,反应烧结是主要的烧结过程机制。烧结温度为1 100℃时,煤气化残渣基多孔陶瓷性能最优,孔隙率为49.2%,平均孔径为5.96μm,0.01 MPa压力下平均N2通量达到2 452.6 m~3/(m~2·h),抗弯强度达到8.96 MPa。制备的煤气化残渣基多孔陶瓷具有高强度、高通量以及低成本的优异性能,有望用于高温气体过滤以及污水处理,解决煤气化残渣的环境污染问题。     

Exxon catalytic coal gasification process: Fundamentals to flowsheets

This Paper reviews basic features of the reaction kinetics of potassium-catalysed coal gasification and describes how small-scale data were used for the conceptual design of large fluidized-bed gasifiers. It shows how potassium was chosen from among the alkali metals, the importance of the methanation reaction, and of steam conversion.     

Catalytic coal gasification: use of calcium versus potassium

A comparative study is made of the relative catalytic effects of potassium and calcium on the gasification in air and 3.1 kPa steam of North Dakota lignitic chars prepared under slow and rapid pyrolysis conditions. It is indicated that potassium achieves relatively high catalytic activity by chemical interaction with the carbonaceous support, no matter how it is added to the lignite or its char. Deactivation of the catalytic potassium is brought about by interaction with inherent aluminosilicates. However, deactivation of calcium is related to its sintering via crystallite growth.