石油焦水煤浆在新型气化炉内气化过程的数值计算

对石油焦水煤浆(PCCWS)在多喷嘴新型水煤浆气化炉内的气化过程进行了数值计算,考察了气化炉内的温度分布、各种气化产物浓度分布规律.结果表明:同浓度的石油焦水煤浆气化与普通水煤浆气化相比,气化炉内平均温度略有上升,碳转化率提高,气化炉出口粗煤气中有效气(CO H2)含量提高7.91%,CO2和H2O浓度大幅下降,水分解率大大提高;石油焦水煤浆气化可以节约氧气约6%,气化效果明显优于普通水煤浆.     

煤浆浓度对水煤浆气化影响的数值模拟

采用数值方法模拟了应用于IGCC的水煤浆气化过程中煤浆浓度对出口煤气成分以及碳转化率的影响效果。总结了在具有复杂化学反应的高温、高压容器中,对水煤浆气化过程的数值模拟时经常遇到的问题和解决方法。得到了气化炉内的温度场、流场、浓度场以及出口粗煤气成分,其结果与工程实际相比非常接近;并利用得到的结果分析了影响水煤浆气化过程和出口煤气成分的主要因素之一的煤浆浓度,提出了提高出口煤气有效成分(CO H2)的措施。图7表1参8     

氧煤比对气流床煤气化过程的影响

为研究氧煤比对气流床煤气化炉气化过程的影响,对某厂运行的Texaco气化炉进行了数值模拟研究。利用所建立的数学模型,分析了Texaco气化炉内的气化过程,以及氧煤比对炉内温度、气相成分及炉膛出口合成气成分的影响规律。结果表明:Texaco气化炉内下行火焰的长度约占气化炉高度的1/3,炉膛上部火焰高度区域内气相温度及主要成分浓度的变化梯度最大,而在炉膛下部气相成分及温度的变化均不明显;随着氧煤比的增大(0.95~1.10),气化炉出口合成气有效成分(H2+CO)浓度逐渐降低,CO2和H2O的浓度及气化炉内气相温度逐渐升高;在保证顺利排渣和合适的出口合成气成分的条件下,存在一个最佳氧煤比。     

煤质对水煤浆气化性能的影响研究

煤质与气流床气化炉的匹配性至关重要,其不但影响气化炉的运行条件,也影响气化性能。本文选择了10种来自新疆和陕西北部的煤样进行了工业分析、元素分析、灰组成分析、灰熔点分析以及成浆性测试,并筛选出适合水煤浆气化的煤样。同时借助Aspen Plus软件对适合水煤浆气化的煤样在相同的煤浆浓度、碳转化率及操作压力条件下开展煤质对水煤浆气化性能影响的模拟分析。结果表明煤中灰含量越高,冷煤气效率和有效气含量越低,比氧耗和比煤耗越高;煤中O/C质量比和H/C质量比的增加也会导致冷煤气效率和有效气含量降低,比氧耗和比煤耗增加。因此从水煤浆气化经济性考虑,建议水煤浆气化煤质灰含量小于9.0wt%,煤中O/C质量比小于0.173,H/C质量比小于0.065。     

气化参数对IGCC系统中气化炉性能的影响

首先单独对气化炉出口合成气成分含量进行核算,计算结果与文献基本吻合.然后建立200 MW级整体煤气化联合循环(IGCC)系统模型,对基本参数下的IGCC系统进行计算,得出整个系统的性能参数.最后对不同气化参数温度、水煤浆浓度、氧气浓度、O/C比的气化炉性能及其整个IGCC系统效率进行比较,分析不同气化条件下的合成气成分体积含量、冷煤气效率、有效气(CO+H2)体积含量、比氧耗、比煤耗及整个IGCC系统效率的变化.结果表明:提高水煤浆的浓度,有利于提高气化炉的冷煤气效率;气化温度对IGCC系统性能影响较大;提高氧气浓度有利于提高气化冷气效率和系统的效率,本系统对应的最佳O/C比为1.02左右.     

串联交替式炉膛高热值生物质气化炉数值模拟及试验研究

对串联交替式炉膛高热值燃气生物质气化炉进行了研究,气化炉以木质颗粒为燃料、空气-水蒸气为气化剂,采用Fluent软件数值模拟了气化炉内水蒸气入口距离炉栅位置高度h、水蒸气入口流量Vs与空气入口流量V03个参数对燃气组分CO,H2和CH4体积浓度的影响。采用正交试验优化了上述3个参数,并试验测试了3个参数下燃气组分CO,H2和CH4体积浓度及燃气热值。数值模拟与试验结果表明,当h为175 mm,V0为0.92 m3/h,Vs为1.33 m3/h时,生物质燃气热值Q最大值为10.46 MJ/m3,比单一空气气化剂作用下提高了107.95%。     

煤粉加压气化炉操作参数对气化特性的影响

采用基于平衡态模型的气流床气化炉煤气组分预测程序,分析研究了气化压力、氧煤比以及蒸汽煤比等操作参数对气化温度、煤气组分、碳转化率和气化效率的影响规律。研究结果表明:气化压力对气化特性指标影响甚微,而氧煤比和蒸汽煤比的影响较为显著。随氧煤比的增加,气化温度升高,碳转化率升高,气化效率先升高再降低,CO浓度先增加后降低。CH_4的体积浓度可用于预测气化温度。在蒸汽煤比较低时,提高蒸汽煤比可增加H_2的浓度,提高碳转换率和气化效率,但进一步提高蒸汽煤比仅会降低气化炉内的气化温度,提高H_2O和CO_2浓度。对于所研究的煤种,合理的氧煤比应在0.7左右,合理的蒸汽煤比在0.1左右。     

大型海藻生物质气化的建模与计算

采用Aspen Plus流程模拟软件对以条浒苔为代表的大型海藻的气化进行数值模拟.研究了海藻气化炉的重要相关参数(即条浒苔含水量、氧气条浒苔比、气化温度、氧气浓度)对气化结果的影响.结果显示:随着条浒苔含水量的增加,合成气的有效成分(H2+CO)总含量减少;当氧气条浒苔比为0.56时,气化温度增大到800℃,合成气中(H2 +CO)的摩尔比例达到最大值;氧气的纯度提高,有利于合成气中有效成分的增加.     

炭化气氛对黑液煤浆及不同煤种气化反应特性的影响

煤气化前阶段的炭化气氛(温度、时间)影响到煤焦的气化反应特性.采用不同的炭化温度和炭化时间制备了黑液水煤浆、普通水煤浆以及其他5种煤的焦样,得到了各种煤焦气化反应的碳转化率;同时,通过扫描电子显微镜分析手段鉴别焦炭表面孔隙分布情况.试验结果表明,相同炭化气氛下得到的7种不同煤焦中,黄陵煤焦的气化活性最高,说明煤化程度越高反应性越低;由于黑液中有机物和无机物钠盐的影响,黑液水煤浆焦的气化特性高于普通水煤浆焦和新汶煤焦.煤焦的气化反应性,不仅与煤阶有关,还和煤焦中含氧官能团和无机化合物的含量有关,同时煤浆中外在添加的无机物组分也影响到煤焦的气化活性.     

干煤粉加压气流床气化试验研究

介绍了36t/d加压气流床气化中试装置主要设备、工艺流程及工艺条件的选择,并给出试验研究中多个煤种在气化压力3.0MPa、投干粉煤量1t/h条件下取得的主要试验数据。从试验数据看出,干法气化指标明显优于水煤浆气化,主要是CO2含量低,有效成分(CO H2)含量高(均大于89%),证明了干煤粉气化的优越性。试验结果基本达到预期目的,积累了干粉煤气流床气化数据。     

下吸式生物质气化炉热力学平衡模型研究

建立下吸式生物质气化炉热力学平衡模型,该模型包括焦炭、焦油和气体,并用已公布的实验数据对模型进行验证,均方根（RMS）在1.304~3.814之间,结果表明该模型的预测值与实验数据吻合较好,可认为模型可靠。然后模拟棉秆在下吸式生物质气化炉中以空气和富氧气体2种气化氛围下,不同操作参数(当量比、预热温度和气化炉反应温度)下对棉秆气化的气体组分、热值和产率的影响。模拟结果表明：富氧气体为气化剂时,当量比从0.20增至0.35时,气体中N₂含量比空气显著下降,达10%以上,同时发现能提高气体中H₂和CO的含量和热值,热值比空气提高约20%。预热温度对气化成分变化影响有限,随预热温度从30 ℃变化到130 ℃,气体的平均热值从空气的5.2 MJ/m³提高到富氧气体的7.0 MJ/m³。随气化炉内反应温度从750 ℃升至1250 ℃,空气和富氧气体2种气化剂下的H₂和CO分别从20.94%、26.84%和21.77%、28.67%下降到4.06%、9.12%和10.49%、21.60%,导致气体的热值降低。     

The Dynamic Temperature Field of Two-Stage Underground Coal Gasification (UCG)

Two-stage UCG is an effective technique to produce water gas with high heating value; its gas producing process is mainly determined by temperature. On the basis of the model experiment, via the analysis of the temperature field distribution regularity in the gasified coal layers in the gasifier and the generalization and treatment of the boundary conditions, two-dimension nonlinear unstable mathematical models of the temperature field in the two-stage UCG are established, and the method of selecting model parameters is illustrated. Solution is made through the method of volume controlling. This article also analyzes the results of calculation. In the light of the numerical computation results, the calculation value of the temperature field for coal seams of combustion and gasification can better fit with the experimental one under the condition of the model experiment. Except for some measuring points in the vicinity of the flame working face, where the relative error between computation value and test value is comparatively high, those of other measuring points are all below 15%, which completely meets the accuracy requirements for the numerical simulation on the temperature field of UCG. The consistency between the calculation value and the measurement value indicates that the numerical simulation of dynamic temperature field of coal media in the gasifier is correct, which provides necessary theoretical basis for further quantitative study of the UCG process.     

Simulation of hybrid biomass gasification using Aspen plus: A comparative performance analysis for food, municipal solid and poultry waste

Steady state simulation model for gasification has been developed using Aspen Plus. The model can be used as a predictive tool for optimization of the gasifier performance.The Gasifier has been modeled in three stages. In first stage moisture content of biomass feed is reduced. In second stage biomass is decomposed into its elements by specifying yield distribution. In third stage gasification reactions have been modeled using Gibbs free energy minimization approach. The simulation results are compared with the experimental results obtained through hybrid biomass gasifier. In the simulation study, the operating parameters like Temperature, Equivalence Ratio (ER), Biomass Moisture Content and Steam Injection have been varied over wide range and the effect of these parameters on syngas composition, High Heating Value (HHV) and Cold Gas Efficiency (CGE) has been investigated. Temperature increases the production of CO and H₂. Increasing ER decreases the production of CO and H₂ which decreases the CGE. Biomass moisture content is an important parameter affecting the heating value of the gas. Steam injection favors hydrogen production. The performance of the simulated gasifier has been compared using experimental data for Municipal Solid Waste (MSW), Food Waste (FW) and Poultry Waste (PW).     

Coal conversion submodels for design applications at elevated pressures. Part II. Char gasification

This paper surveys the database on char gasification at elevated pressures, first, to identify the tendencies that are essential to rational design of coal utilization technology, and second, to validate a gasification mechanism for quantitative design calculations. Four hundred and fifty-three independent tests with 28 different coals characterized pressures from 0.02 to 3.0 MPa, CO₂ and steam mole percentages from 0 to 100%, CO and H₂ levels to 50%, gas temperatures from 800 to 1500 °C, and most of coal rank spectrum. Only a handful of cases characterized inhibition by CO and H₂, and only a single dataset represented the complex mixtures of H₂O, CO₂, CO, and H₂ that arise in practical applications. With uniform gas composition, gasification rates increase for progressively higher pressures, especially at lower pressures. Whereas the pressure effect saturates at the higher pressures with bituminous chars, no saturation is evident with low-rank chars. With fixed partial pressures of the gasification agents, the pressure effect is much weaker. Gasification rates increase for progressively higher gas temperatures. In general, gasification rates diminish for coals of progressively higher rank, but the data exhibit this tendency only for ranks of hv bituminous and higher.

These tendencies are interpreted with CBK/G, a comprehensive gasification mechanism based on the Carbon Burnout Kinetics Model. CBK/G incorporates three surface reactions for char oxidation plus four reactions for gasification by CO₂, H₂O, CO and H₂. Based on a one-point calibration of rate parameters for each coal in the database, CBK/G predicted extents of char conversion within ±11.4 daf wt% and gasification rates within ±22.7%. The predicted pressure, temperature, and concentration dependencies and the predicted inhibiting effects of CO and H₂ were generally confirmed in the data evaluations. The combination of the annealing mechanism and the random pore model imparts the correct form to the predicted rate reductions with conversion. CBK/G in conjunction with equilibrated gas compositions accurately described the lone dataset on complex mixtures with all the most important gasification agents, but many more such datasets are needed for stringent model evaluations.

Practical implications are illustrated with single-particle simulations of various coals, and a 1D gasifier simulation for realistic O₂ and steam stoichiometries. The rank dependence of gasification rates is the determining factor for predicted extents of char conversion at the gasifier outlet. But soot gasification kinetics will determine the unburned carbon emissions for all but the highest rank fuels. Only gasification kinetics for gas mixtures with widely variable levels of H₂O, H₂, and CO are directly relevant to gasifier performance evaluations.     

Feasibility study of Jatropha seed husk as an open core gasifier feedstock

This paper presents the results of investigation carried out in studying the fuel properties of Jatropha seed husk and its gasification feasibility for open core down draft gasifier. Jatropha seed husk was converted to producer gas in an open core down draft gasifier whose performance was evaluated in terms of fuel consumption rate, calorific value of producer gas and gasification efficiency at different gas flow rates. It was found that producer gas calorific value and concentration of CO, along with gasification efficiency, in general, increased with the increase in gas flow rate. The maximum gasification efficiency was found to be 68.31% at a gas flow rate of 5.5 m³ h⁻¹ and specific gasification rate of 270 kg h⁻¹ m⁻². Studies revealed that Jatropha seed husk could successfully be used as feedstock for open core down draft gasifier.     

高温快速加热条件下压力对煤气化反应特性的影响

建立了一套能同时实现高温高压和快速加热的实验设备和研究方法,使煤气化反应动力学基础研究能在与实际气流床煤气化炉相近的条件下进行.研究表明,当CO2体积分数相同时,最大CO生成速度随压力的升高而升高;煤焦的气化反应速度随全压的升高而升高.即使全压和CO2体积分数不同,只要CO2的分压、温度等其他条件相同,煤焦的气化反应速度就基本上一致.说明全压和CO2体积分数对煤焦气化反应速度的影响可以归纳为CO2分压的影响.高温快速加热条件下,除了温度以外,CO2分压是影响煤气化特性的重要因素.     

不同气化剂下海藻粉在气流床下气化特性试验研究

为考察O2/水蒸气和O2/CO2作为气化剂对海藻粉气化特性的影响,在自制的小型生物质气流床气化炉上开展海藻粉在气流床下气化特性试验研究。当氧气/生物质比（O/B）为0.3、气化温度为1200℃时,不同水蒸气/生物质比（S/B=0～1.2）对合成气组成有较大影响,其中H2产量的上升趋势最为明显,S/B=1.2时比单纯氧气气化提高了81.4%。而在O2/CO2气化条件下,由生物质产生的CO2随二氧化碳/生物质比（CO2/B）的增加而下降,当CO2/B=0.9时,H2、CO的产量分别比单纯氧气气化提高了33.9%和75.8%,热值由5521 kJ/m3上升至8576 kJ/m3。结果表明,如果以提高热值为制取合成气的目标时,添加CO2在一定范围内可以达到水蒸气的效果,同时降低了系统能耗及简化了气化设备。     

Hydrogen-rich syngas production via integrated configuration of pyrolysis and air gasification processes of various algal biomass: Process simulation and evaluation using Aspen Plus software

In the present study, hydrogen-rich syngas production via integrated configuration of pyrolysis and air gasification processes of different algal biomass is investigated at relevant industrial condition. A comprehensive steady state equilibrium simulation model is developed using Aspen Plus software, to investigate and evaluate the performance of pyrolysis and air gasification processes of different algal biomass (Algal waste, Chlorella vulgaris, Rhizoclonium sp and Spirogyra). The model can be used as a predictive tool for optimization of the gasifier performance. The developed process consists of three general stages including biomass drying, pyrolysis and gasification. The model validation using reported experimental results for pyrolysis of algal biomass indicated that the predicted results are in good agreement with experimental data. The effect of various operational parameters, such as gasifier temperature, gasifier pressure and air flow rate on the gas product composition and H₂/CO was investigated by sensitivity analysis of parameters. The achieved optimal operating condition to maximize the hydrogen and carbon monoxide production as the desirable products were as follows: gasifier temperature of 600 °C, gasifier pressure of 1 atm and air flow rate of 0.01 m³/h.     

Numerical Simulation of Pressure Effects on the Gasification of Australian and Indian Coals in a Tubular Gasifier

This article presents a numerical study on the effect of pressure on the gasification performance of an entrained flow tubular gasifier for Australian and Indian coals. Gasification using a substoichiometric amount of air, with or without steam addition, is considered. The model takes into account phenomena such as devolatilization, combustion of volatiles, char combustion, and gasification. Continuous-phase conservation equations are solved in an Eulerian frame and those of the particle phase are solved in a Lagrangian frame, with coupling between the two phases carried out through interactive source terms. The numerical results obtained show that the gasification performance increases for both types of coal when the pressure is increased. Locations of devolatilization, combustion, and gasification zones inside the gasifier are analyzed using the temperature plots, devolatilization plots, and mass depletion histories of coal particles. With increase in pressure, the temperature inside the gasifier increases and also the position of maximum temperature shifts upstream. For the high-ash Indian coal, the combustion of volatiles and char and the gasification process are relatively slower than those for the low-ash Australian coal. The mole fractions of CO and H₂ are found to increase with increase in pressure, in all the cases considered. Further, the effects of pressure on overall gasification performance parameters such as carbon conversion, product gas heating value, and cold gas efficiency are also discussed for both types of coals.