焦炉煤气非催化部分氧化制合成气实验研究与数值模拟

在带有单孔喷嘴石英管反应器实验的基础上,对焦炉煤气非催化部分氧化工艺制合成气进行了研究,分析了O_2/GAS比对合成气各组分含量的影响,反应器中反应过程和温度分布及出口产品组成.实验结果表明CH4转化率随O_2/GAS比增大而增大,O_2/GAS比调节到0.22～0.26时,CH_4转化率达到95%～97%,此时合成气CH_4含量低于1%.利用CFD软件平台对转化反应器进行了数值模拟.模拟结果显示,流量一定时出口气体组分H_2与CH4分别随着进气氧气与焦炉煤气体积流量比值的增加而减少.CO和CO_2分别随着比值的增加而增加.出口气体有效组分摩尔分数随进气流量的变化不是非常明显.在壁面温度为1 100 K时转化效果最好.     

合成气制乙二醇羰化径向反应器床层换热模拟

为考察生成草酸二甲酯的羰化径向反应器中发生的换热、反应过程,采用COMSOL Multiphysics对羰化径向反应器二维模型进行模拟,将床层划分为进口绝热层和布管区2个区域,重点研究了换热管管径和位置对反应床层温度分布的影响,提出了两排一组,间隔排列的双排布管方案。结果表明:进口温度越低、进口速度越大,进口绝热层越厚;布管区换热能力和管心距与管径之比负相关;小管径换热管床层热点温度较低,随着管心距与管径之比下降,不同管径床层热点温度差异增大;单排换热管对间隙位置热点的影响有限,采用双排布管方案的床层温度分布更加均匀;在本模拟条件下,双排换热管排间距50 mm、后排管心距与管径之比在1.6—1.8时床层压降、平均温度、热点温度均较低。     

焦炉煤气转化反应器的数值模拟

通过对焦炉煤气和纯氧在双孔喷嘴石英管反应器内发生非预混燃烧的过程进行实验研究和数值模拟,得到了反应器内温度分布、流场、浓度分布和反应产品气(合成气)中H2/CO比.模拟结果显示,反应主要在靠近氧气入口的区域内发生,反应器壁温对反应结果有非常重要的影响.实验结果和模拟结果比较,表明温度和流场吻合得很好,组分分布略有误差.     

醋化反应器节能的数值模拟

针对特殊的醋化反应体系,在现有的醋化反应器传热条件基础上,采用数学模型计算并预测提升冷冻盐水温度的可行性。计算结果表明,将冷冻盐水的温度由-46℃提升至-30℃时,对温升曲线及峰值温度的影响可满足生产需求,并进一步由工业试验结果验证了模型的精度。     

搅拌反应器内计算流体力学模拟技术进展

综述了计算流体力学(CFD)技术应用在搅拌反应器的进展情况。重点对搅拌反应器内流动场模拟的各种处理方法,包括"黑箱"模型法、内外迭代法、多重参考系法和滑移网格法,进行了介绍与评价,指出了各种方法所具有的特点及存在的问题。阐述了搅拌反应器内CFD技术的发展方向,并就国内的研究现状进行了简单概述。     

自吸式反应器气液传质实验研究和CFD模拟

对一种自吸式反应器的气液分散性能进行了实验研究,并采用计算流体力学(CFD)ANSYS CFX中对自吸式反应器在600,800,1 000,1 200 r/min 4种转速条件下气液二相流的流场、局部气含率及整体气含率进行了数值模拟,并采用Higbie溶质渗透模型模拟研究了反应器的容积传质系数。研究结果表明:气液二相流场与高速摄像机拍摄的结果相同,成对称分布;自吸式反应器的局部气含率分布均匀,上下分布良好,整体气含率的模拟结果与实验结果一致,实验值和模拟值误差为5.1%;局部容积传质系数分布良好,气体出口附近较好,容积传质系数模拟值与实验值变化趋势一致。     

浸没板式膜生物反应器中流体运动的数值模拟

利用计算流体动力学（CFD）技术,以浸没板式膜生物反应器（MBR）中曝气槽内的流体为研究对象,将固相和液相视作“假想的均-混合相”,将气、液、固三相流简化为“气-液两相流”问题。选用FLUENT软件中的多项流Eulerian模型,对曝气槽的内部流场的流态进行了模拟分析。结果得到包括气液两相多个截面的速度场及局部气含率分布等信息。模拟结果显示浸没板式MBR具有较好的水力条件,在一定的曝气强度条件下,在获得较大的升流区上升流速的同时,也获得了较大的膜面剪切力;一定的曝气条件会在曝气槽中产生固定的影响微生物生长的缺氧区,通过改变曝气强度可以解决这一问题。以上模拟结果能够合理解释实际工况中存在的膜污染等现象,证明了CFD技术在膜生物反应器中应用的可行性。数值求解结果可以为MBR的实际工程设计提供理论依据。     

圆盘反应器流场数值模拟

以圆盘反应器的开发和应用为背景,根据反应器内气液两相的流动特点和接触方式,采用流体体积函数(VOF)模型研究圆盘表面液膜厚度、速度分布和槽内液相流型,得到反应器的流场特性。从轴功率、持液量两方面对反应器性能进行研究,并考察了流场和性能的关系。结果表明,圆盘表面液膜分为起始区、加速区和匀速区。起始区液膜厚,速度慢,部分液体回流;加速区液膜变薄,加速,表面更新快;匀速区膜厚和速度变化较小。液相主体以Stewartson流型为主,盘间距对液相流型影响明显。圆盘液膜与槽内液相通过垂直涡进行物质传递,当圆盘间距与圆盘直径之比(L/D)为0.2~0.4时,最有利于两者混合和物质传递。将数值模拟和量纲分析结合,得到功率数(NP)和平均膜厚表达式,并与文献进行比较,表明计算流体力学(CFD)方法能够较好的模拟圆盘反应器内流体力学特性,预测流场和性能。     

小试聚合反应器模拟

通常使用38×10~(-3)～190×10~(-3)m~3(10～50加仑)的水冷式实验用间歇反应器来制备聚合物试样,这项功能它们运用得很好。而且也能使用这些反应器获得关于装置安全而有效操作所必须的动力学数据,尽管在最初设计中很少涉及此功能。 可以通过测定循环冷却夹套进出口温差△T来确定反应热。因为该夹套也控制温度,当温度控制器试图克服变化着的热负荷时,进口温度会经受相当大的波动,为避免△T偏离较远,控制器精确调谐是必要的。     

合成气制乙二醇反应器的大型化措施

从反应羰化及加氢催化反应原理入手,提出采取径向蛇管结构的羰化及加氢反应器,不仅解决了乙二醇反应器大型化的难题,而且从源头控制羰化及加氢副产物的生产,降低羰化及加氢循环机的功耗与工程投资,有效提高了大型乙二醇装置的市场竞争力。     

焦炉气催化部分氧化的数值模拟

利用F luent中标准κ-ε模型和多孔介质模型对焦炉气催化部分氧化转化炉进行模拟计算。整个反应床层分为氧化反应区和转化区,氧化反应区主要发生燃烧反应;转化区则装填催化剂,发生甲烷重整反应。通过模拟计算给出了转化炉内温度分布、压力分布、组分摩尔分数分布。转化炉出口的温度与气体摩尔分数与Aspen P lus软件模拟结果相吻合。表明CFD模拟结果是准确的,可用于焦炉气催化部分氧化转化炉的工艺和结构设计中。     

焦炉煤气再利用系统仿真模型研究

以系统动力学（SD）为手段,建立了焦炉煤气制甲醇的生产经营系统动态仿真模型。首先绘制了甲醇生产经营系统的因果关系图,并且根据因果关系图绘制系统动力学流图,编写了系统动力学方程。在模型通过真实性真检验后,对LH化工园的煤化工制甲醇项目进行了动态仿真与预测。研究表明,所建立的模型是有效和可信的,能够充分代表现实系统,中国煤炭企业利用废弃的焦炉煤气制备甲醇项目中,模型对制定正确的发展战略以及促进其持续、协调和可持续发展,都具有理论参考价值和实践指导意义。     

Numerical simulation of nanoparticle synthesis in diffusion flame reactor

A computational model combining the fluid dynamics with the particle kinetics was employed to study TiO₂ nanoparticle synthesis in a diffusion flame reactor. A one-step chemical kinetics approach was used to model titanium tetraisopropoxide (TTIP) decomposition that leads to homogeneous nucleation and particle formation. The momentum, heat, and mass transfer, Brownian coagulation and diffusion, surface growth, coalescence and thermophoresis have been taken into account. Based on the particle size distributions, an efficient quadrature method of moments was allowed to approximate the general dynamics equation of particle, and the eddy dissipation concept (EDC) combustion model was used to estimate the flame temperature field. Excellent agreements between the model predictions and experimental data, with respect to the flame temperature distribution and particle kinetics, are reached. By taking the particle size and surface area as independent variables, the full distributions of volume equivalent diameters, evolution of the agglomerate number, the geometric standard deviation based on volume and agglomerate fractal nature, mean primary particle size and the number of primary particles per agglomerate are revealed. The variation of oxygen flow rate has an important influence on the temperature distribution and hence on the particle kinetics accordingly.     

Performance of an oxygen-permeable membrane reactor for partial oxidation of methane in coke oven gas to syngas

Perovskite-type oxygen-permeable membrane reactors of BaCo_0.7Fe_0.2Nb_0.1O_3−δ packed with Ni-based catalyst had high oxygen permeability and could be used for syngas production by partial oxidation of methane in coke oven gas (COG). The BCFNO membrane itself had a poor catalytic activity to partial oxidation of CH₄ in COG. After the catalyst was packed on the membrane surface, 92% of methane conversion, 90% of H₂ selectivity, 104% of CO selectivity and as high as 15 ml/cm²/min of oxygen permeation flux were obtained at 1148 K. During continuously operating for 550 h at 1148 K, no degradation of performance of the BCFNO membrane reactor was observed under the condition of hydrogen-rich COG. The possible reaction pathways were proposed to be an oxidation-reforming process. The oxidation of H₂ in COG with the surface oxygen on the permeation side improves the oxygen flux through the membrane, and H₂O reacts with CH₄ by reforming reactions to form H₂ and CO.     

工业级错流列管式固定床反应器的CFD模拟

工业级大型列管式固定床反应器壳程温度场与流场的均匀程度与反应的转化率及选择性密切相关。通过添加阻力源项和分散热源项,对工业级全尺寸错流列管式固定床壳程流场及温度场进行了CFD模拟研究,并进一步考察了折流板窗口区大小及其位置对壳程压降与温度分布的影响。结果表明,模拟得到壳程压降与由经验公式计算得到的压降较为接近,且壳程温度分布与工业实际数据吻合;增大窗口区面积,壳程压降呈现指数下降,同时高温差区（径向温差大于2 K）的范围与径向温差变大;随着第1块折流板位置降低,高温差区范围及径向温差均减小,但压降并不呈现规律性变化。模拟方法可用于工业级大型列管式固定床反应器的优化及设计。     

Colourless distributed combustion effects on a pre-mixed coke oven gas flame

Fuels consisting of high hydrogen concentration can be consumed under colourless distributed combustion (CDC) to suppress flashback tendency in premixed conditions. Higher NO_X challenges can also be overcome through CDC. For those purposes, coke oven gas was consumed under CDC within the scope of this study. To achieve CDC, ${\mathrm{N}}_2$ or ${\mathrm{CO}}_2$ diluents were introduced into the oxidizer so that oxygen concentration in the oxidizer would be decreased from 21% O₂ to its lean blow-off limits. Excess air ratios were determined as λ = 1.2 and λ = 1.5 along with a thermal power of 10 kW under premixed conditions. A commercial computational fluid dynamics code was used to predict temperature distribution and ${\mathrm{NO}}_X$, CO, and ${\mathrm{CO}}_2$ emissions. 162-step reactions created with GRI-Mech 3.0 chemical kinetics was integrated to the eddy dissipation concept combustion model. The temperature and ${\mathrm{NO}}_X$ profiles predicted were compared with the experimental results. Consistency was achieved at ~95% for temperature profiles, and almost 100% for ${\mathrm{NO}}_X$ profiles between the measured and the predicted ones. According to the results, it is concluded that a more homogeneous temperature distribution with the ~21% decrease in the maximum temperature was observed, and there was about 96% decrease in ${\mathrm{NO}}_X$ level. It was also demonstrated that using ${\mathrm{CO}}_2$ as a diluent is more effective in terms of temperature distribution over the combustor and ${\mathrm{NO}}_X$ reduction, while dilution with ${\mathrm{N}}_2$ is more effective in terms about 70% in decrease on CO.     

Numerical simulation of liquid-solid two-phase flow in a tubular loop polymerization reactor

Understanding hydrodynamics of tubular loop reactors is crucial in proper scale-up and design of these reactors. Computational fluid dynamics (CFD) models have shown promise in gaining this understanding. In this paper, a three-dimensional (3D) CFD model, using a Eulerian-Eulerian two-fluid model incorporating the kinetic theory of granular flow, was developed to describe the steady-state liquid-solid two-phase flow in a tubular loop propylene polymerization reactor composing of loop and axial flow pump. Corresponding simulations were carried out in the commercial CFD code Fluent. The entire flow field in the loop reactor was calculated by the model. The predicted pressure gradient data were found to agree well with the classical calculated data. Furthermore, the model was used to investigate the influences of the circulation flow velocity and the sold particle size on the solid hold-up. The simulation results showed that the solid hold-up has a relatively uniform distribution in the loop reactor at small particles in volume and high-circulation flow velocities.     

热回收焦炉桥管和集气管烟气流动特性的研究

针对某热回收焦炉桥管和集气管存在的问题,建立数学模型,利用CFD数值模拟软件,对管内的流动传热进行分析研究,结果表明,在集气总管尺寸固定、集气支管保温效果良好的情况下,应尽可能增大集气支管内径,以平衡各炭化室对应桥管的吸力,进而增大集气支管末端炭化室所供烟气体积流率。     

焦炉煤气合成甲醇工艺优化研究

为了提升焦炉煤气提炼甲醇的效率,利用数值模拟软件对不同参数下合成甲醇的最佳值进行模拟分析,发现当补碳位置在工段前更有益于CO的补充,同时通过对补碳量对合成气中H2、CO、CO2含量影响曲线及水蒸气、氧气量对氢碳比的影响曲线进行分析,确定反应最佳的补碳量为125 kmol/h,最佳氧气注入量为240 kmol/h,最佳水蒸气注入量为650 kmol/h。以期为焦炉煤气合成甲醇作出一定的参考。