A kinetic model for gasification of heavy oil with in situ CO2 capture

Gasification process is being developed to obtain environmentally clean and efficient syngas from solid (coal, biomass, and municipal solid waste) or liquid (heavy oil and waste lubricant oil) fuels for power generation. A gasification kinetic model of heavy oil in the presence of CaO that can predict syngas yield, tar concentration, and performance parameters has been developed. Results showed that the CaO plays a major role for a significant reduction in carbon dioxide during the process. Based on the operating conditions, it was also found that there is an optimum condition for tar yield. Modeling results were validated against experimental data and found to be in good agreement.     

Aspen plus simulation of heavy oil gasification in a fluidized bed gasifier

Gasification is a clean technology to convert fuels to high-quality syngas in presence of a gasifying agent. In this study, an Aspen Plus model of heavy oil gasification was developed to produce the hydrogen rich syngas. Effect of some parameters such as gasification temperature and steam/fuel ratio on the hydrogen yield and was investigated. Results showed that the temperature plays a major role in the process; higher temperatures produce the higher hydrogen content. It was also found that the operation under high steam/fuel ratio can cause a significant increase in the hydrogen yield. The modeling results were compared with the experimental data available in the literature and found to be in good agreement.     

Computer-based model of crude oil gasification in a fluidized bed

Gasification is a high-temperature, low-cost, and environmentally friendly process with uses as an alternative method to convert the carbon-based fuels into a clean syngas for engineering applications. In this work, the authors developed a mathematical model of crude oil for evaluating the crude oil potential to produce a clean and high caloric value syngas. The influence of some critical parameters during crude oil gasification including equivalence ratio, excess oxygen ratio (EOR), and residence time on tar yield, syngas caloric value, and char conversion was investigated. Results showed that with increasing the EOR, the char was converted continuously due to a significant improvement in the nature of endothermic reactions involved. It is also found that when the EOR increases from 0.2 to 0.8, gas caloric value improves, slightly.     

A computational fluid dynamic model for evaluating the performance of crude oil gasification

Gasification is a clean technology which converts the liquid or solid fuels into a high caloric value syngas for power generation. In this research work, we developed a computational fluid dynamic model of crude oil gasification for hydrogen production; the accuracy of the model was approved in our previous work. Effects of some important factors such as residence time, steam/fuel ratio and equivalence ratio on hydrogen yield, and char conversion were explored. Results showed that the residence time and steam/fuel ratio play a major role in the process. It was also found that the equivalence ratio has a negative effect on the hydrogen yield and a positive effect on the char conversion.     

聚集辐照下甲烷水蒸气重整制氢过程参数研究

基于自行设计的小型太阳能热化学反应器,建立了聚集辐照下甲烷水蒸气重整数学模型,该模型耦合导热、对流、辐射以及化学反应动力学,计算得到了反应器内甲烷重整过程反应物及产物的浓度、反应速率及温度场的分布,获得了不同工况参数(孔隙率、气体入口温度、水碳比)对甲烷转化率的影响规律。研究结果表明:甲烷水蒸气重整在多孔区域入口处反应迅速,沿反应器中心线方向,反应速率由于反应物浓度的不断降低而减小,导致混合气体的浓度及温度趋于稳定。孔隙率、水碳比及气体入口温度的增加都会导致甲烷转化率增加。当入口温度为500 K、孔隙率为0.75、水碳比为2.5、入口速度为0.006 m/s时,甲烷的转化率为96%,氢气产率为28%。该研究结果对甲烷水蒸气重整制氢过程参数优化具有一定的参考意义。      

CFD simulation of entrained-flow gasification of liquid fuels

In this study, a CFD model of entrained-flow gasification of petroleum residue proposed to simulate the effects of some critical parameters such as equivalence ratio and system pressure on carbon conversion efficiency, tar yield, hydrogen concentration, and higher heating value of the syngas. It is a 2D model and steady state, which can be used as a general model to evaluate the performance parameters of other fuels (coal, biomass, and municipal solid wastes) during gasification process. Results showed the equivalence ratio has a negative effect on the higher heating value of the syngas and a positive impact on the gasification efficiency. It also found that the carbon conversion efficiency strongly depends on the equivalence ratio and gasification temperature. The model validated against experimental observations and found to be in good agreement.     

低阶煤固定流化床热解及半焦气化实验研究

采用固定流化床研究了三种低阶煤的常压热解及其热解半焦的气化特性,探究了样品粒度、反应温度、反应时间及流化气中O2含量对上述过程的影响,确定了循环流化床热解-气化耦合工艺适宜的反应条件。结果表明,在实验选择范围内,样品的粒度基本不会影响热解过程,在水蒸气气氛下,温度越高,热解气体产率越高,半焦产率越低;600 ℃和20 min时能获得最高的焦油产率。循环流化床热解-气化耦合工艺碳的有效利用率率高于原煤固定流化床气化工艺,同时副产煤焦油;温度越高,有效气产率和有效碳转化率越高;实验范围内,O2含量对合成气产率的影响较小,但可以调节H2和CO的相对含量;900 ℃、半焦气化15 min即可获得较理想的合成气产率及有效碳转化率。     

生物质低温气化及催化重整制氢

对生物质低温气化及催化重整制氢进行了研究。在流化床反应器中考察了较低的气化温度下气相停留时间(12～22s)对气、液、固三相及氢气产率的影响;同时在固定床反应器中对流化床反应器中较长停留时间下的气态产物进行了催化重整,考察了温度和催化剂粒径对氢气产率的影响。实验结果表明,在气化温度600℃下,气体、固体和氢气产率随气相停留时间的延长而增大,液体产率则相反;经过流化床反应器内较长停留时间的焦油只有在催化重整温度高于800℃时才有大幅的裂解;催化剂宜在接近原始尺寸的条件下使用;在气化温度600℃、气相停留时间16s、催化重整温度900℃、GHSV=1716h~(-1)、催化剂粒径大于5mm时,可获得1447.32 mL/g的氢气产率、47.50 mL/g的CO产率和7.20 mL/g的甲烷产率。     

富甲烷气自热转化催化剂及工艺条件研究

在固定床反应器中,对适合富甲烷气自热转化要求的Ni/α-Al2O3催化剂进行了一系列的工艺条件试验,考察了温度、压力、空速、水碳比和氧碳比对甲烷转化率、氢收率和CO选择性的影响,并进行了120h的寿命试验。结果显示,在甲烷空速GHSV=2000h-1,nH2O/nCH4=1.0,nO2/nCH4=0.6,P=0.5MPa,T=1073K的条件下,甲烷转化率、氢收率和CO选择性分别一直保持在96.7%、70.8%和62.4%左右,以上结果表明该催化剂具有很好的稳定性和较高的活性。     

Hydrogen production from co-gasification of asphaltene and plastic

At present, due to the environmental considerations and world energy crisis, there is a growing trend towards using gasification instead of combustion as a thermochemical route for power generation. The purpose of this work was to provide a computer-based model to predict the potential of gasification process for syngas production. The influence of the most important operational conditions namely asphaltene/plastic mass ratio (A/P), steam/fuel ratio (S/F), gasification temperature (T_gas), and equivalence ratio (ER) on gas composition and tar concentration was evaluated. With the asphaltene/plastic ratio (A/P) increasing from 0.2 (wt/wt) to 0.6 (wt/wt), the carbon conversion efficiency (CCE) initially increases from 47.88% to 54.61% for S/F = 0.25, from 49.80% to 54.11% for S/F = 0.5, from 51.83% to 58.36% for S/F = 0.75, and from 52.69% to 60.57% for S/F = 1.0, then steadily decreased. The gas yield also increased from 45.12 (%) to 92.08 (%) with increasing ER from 0.1 to 0.8, while the tar yield decreased from 12.24 (%) to 00.14 (%).     

1 MWth 煤化学链气化过程模拟

基于Aspen Plus建立了1 MWth煤化学链气化模型,探讨了气化过程中不同煤种(宁夏煤、新疆煤、云南煤)、不同载氧体(赤铁矿、锰矿)、温度、氧/碳摩尔比、压力、水蒸气/煤质量比对合成气组分的影响及实现系统自热平衡运行的条件。结果表明：在700~1200 ℃范围内,随着反应温度升高,3种煤合成气产率及冷煤气效率先增加后趋于平缓;水蒸气/煤质量比在0.5~1.5范围内增大、压力在0.1~3.0 MPa范围内增加都会使合成气产率降低;随氧/碳摩尔比在0.1~1.7范围内增大,合成气产率显著降低,系统由外部供热变为向外放热;当系统实现自热平衡运行时,赤铁矿和天然锰矿载氧体的氧/碳摩尔比分别为1.1和1.5;在保证反应速率和经济成本的前提下,优先选择天然锰矿石作为载氧体。     

Hydrogen production via steam gasification of heavy oil: Effects of operating conditions

A heavy oil gasification model that can predict the hydrogen yield has been developed for a high pressure circulating fluidized bed. The model is based on the Aspen Plus package, which is a professional software for simulation of thermal process. To illustrate the effects of the steam/fuel ratio and temperature, several conditions have been examined. The results show that the gasification temperature plays a major role in the process. As gasification temperature increases from 600 to 800°C, the production of hydrogen increases dramatically. The influence of steam/fuel ratio (0.50–0.80) is also considerable, but shows a constant rate at the higher steam/fuel. Simulation results were validated against experimental data available in the literature.     

Catalytic activity of char produced from brown coal for steam-gasification of bitumen oil

There are several kinds of catalyst for tar reduction such as Ni-based catalysts, alkali catalysts, metal catalysts, and char. Char is a nonmetallic material which be generated by the devolatilization of organic materials. In this article, by using an experimental setup we tried to study the effect of char particles as a catalyst on the tar concentration and produced gas from steam gasification of bitumen oil and to introduce effective parameters in the process of syngas generation. With the increase of gasification temperature from 800 to 950°C, the hydrogen increased sharply from 28.4 vol% to 34.9 vol% and 18.5 vol% to 21.3 vol%, while CO decreased from 12.5 vol% to 14.9 vol% and 14.8 vol% to 18.1 vol% for gasification with and without char, respectively. As a result, it was found that the gas produced is not sensitive to the pressure changes.     

流化床中造纸黑液催化石油焦气化特性

利用实验室规模流化床气化反应器,考察了造纸黑液对石油焦水蒸气气化反应的催化效果,并分析了其催化反应机理。结果表明,造纸黑液不仅能显著提高石油焦的气化反应活性,还能大幅提高气化气中H₂的含量。脱水黑液添加量为黑液与石油焦质量之和的10%时催化效果较好,达到相同气化反应速率时的反应温度比纯石油焦气化低200℃左右;在相同反应温度下提高气化反应速率5倍左右,可提高气化气中H₂体积分数约8百分点。黑液中的碱金属活性组分能够破坏石油焦中的C=C芳香结构,同时与石油焦中的碳结合生成活性较高的碳氧复合物C(O),从而提高气化反应速率;碱金属还促进了水煤气变换和CH₄水蒸气重整反应,使得H₂的生成量增多。因此,造纸黑液是一种有效的石油焦气化生产富氢合成气的催化剂。     

Gasification of n-C7 asphaltenes using Ni-based catalysts

Catalytic performance of two Ni-based catalysts (Ni-Pt and Ni-Pt-Al) in steam gasification of n-C7 asphaltenes (C7A) was examined. The influence of the catalysts composition and operating parameters (residence time and temperature) on hydrogen yield and char conversion was studied showing a high hydrogen production and a low char formation compared to Ni-Pt alone. From the result of the gasification of rice C7A over Ni-Pt/Ni-Pt-Al catalysts, it is found that the raising the Pt/Ni ratio increases the quantity of generated hydrogen, but this increase is greater in the presence of the Ni-Pt-Al catalyst because the tar cracking process improves with increased collisions and also with improved activation energies of the reactions in the presence of Al.     

Steam reforming of gaseous by-products from bitumen oil using various supported Ni-based catalysts

The steam reforming process is an efficient route for producing hydrogen gas which, along with lower costs compared to other methods, has an acceptable efficiency rate. In this study, by using an experimental setup we tried to investigate the effect of various catalysts on the amount of tar and produced hydrogen from steam reforming of gas by products from bitumen oil and to introduce effective parameters in the process of hydrogen production. As temperature increased, the amount of tar conversion to gas increases and the amount of hydrogen surged accordingly. With increase in temperatures from 400 to 900°C, tar elimination also improved from 39% to 99% for Ni/Al₂O₃, from 30.5 to 93.1 for Ni/olivine and from 25.7 to 83.6 for Ni/Fe₂O₃. As a result, it was concluded that the Ni/Al₂O₃ catalyst has been more successful in eliminating the tar, although there is not much difference between the activities of the three catalysts.     

有机固体废弃物化学链气化技术研究进展

化学链气化技术(CLG, Chemical looping gasification)是基于化学链燃烧技术(CLC, Chemical looping combustion)发展而来的一种新颖的固体燃料气化技术。相较于常规气化技术,化学链气化技术省去了氧气制备、且不需要燃料燃烧来提供热量,具有合成气不被氮气稀释、焦油及N/S/Cl等污染物含量低、能量梯级利用等优点。以有机固体废弃物(简称有机固废)种类、载氧体(OC, Oxygen carrier)类型和反应装置为切入点,较为系统地综述了化学链气化处理有机固废技术的发展现状,围绕有机固废的气化特性及相关反应机理与系统进行了较为全面的介绍,并对其未来的研究方向进行了展望。     

Prediction of gas composition obtained from steam-gasification of residual oil using an Artificial Neural Network (ANN) model

Steam-gasification is a promising technology for hydrogen-rich syngas production with low tar content. In this work, an Artificial Neural Network (ANN) modeling of steam-gasification of residual oil was developed. The aim of this paper was to study the effect of steam flow rate (SFR) and reaction temperature on gas yield (GSY) and hydrogen yield (HDY). Results showed that GSY and HDY increased from 27.3?Nm³/kg to 37.1?Nm³/kg and 0.27?mol/kg to 0.39?mol/kg as the reaction temperature increased from 850?°C to 1000?°C. It was also found that with increase of SFR from 0.08 to 0.32, HDY increased from 7.5?mol/kg to 27.3?mol/kg.     

Modeling Steam Gasification of Orimulsion in the Presence of KOH: A Strategy for High-Yield Hydrogen Production

Production of hydrogen rich gases from heavy oils via potassium-catalyzed steam gasification is a promising approach toward cleaner fuel production, suitable for fuel cell applications. The authors developed a zero-dimensional mathematical model to simulate the steam gasification of Orimulsion with KOH as a catalyst, based on an equilibrium model. The model is compared with the numerical results and data from an experimental study, showing a good agreement with it. This research activity presents a large number of predicted data of catalytic gasification, aiming to survey the effects of reaction temperature, gasification pressure, steam/fuel ratio, and KOH/fuel ratio on gas product compositions. It also provides useful indications for its optimal choice. Results illustrate that the pressurized operation slightly increases methane concentration as well as the production of higher heating value gas, while decreasing the hydrogen concentration.     

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氢气是燃料电池的首选燃料，而用天然气制氢则是化石燃料制氢工艺中最为经济与合理的，因而以甲烷作原料制备氢气的工艺在当前发挥着重要的作用。为此，对国内外甲烷制氢技术的研究现状、进展及发展方向等进行了论述：甲烷水蒸气重整工艺生产技术虽然较为成熟，但能耗高、生产成本高，设备投资大；甲烷催化部分氧化法过程能耗低，可采用大空速操作，无需外界供热而可避免使用耐高温的合金钢管反应器，可采用极其廉价的耐火材料堆砌反应器，使装置的固定投资明显降低，但尚未见到该技术工业化的相关报道；甲烷自热重整工艺是一种新型制氢方法，其基本原理是在反应器中耦合了放热的甲烷部分氧化反应和强吸热的甲烷水蒸气重整反应，反应体系本身可实现自供热；甲烷绝热转化制氢的原理是将甲烷经高温催化后分解为氢和碳，这是连接化石燃料和可再生能源之间的过渡工艺过程。