有限元方法求解化学气相淀积反应器模型(Ⅰ)——冷壁反应器模型及有限元解

建立了冷壁化学气相淀积反应器的数学模型,用Galerkin有限元方法对模型予以求解.计算中考虑了温度对物性参数的影响及自然对流因素,计算值和实验结果基本上一致.     

加氢反应器简体热应力有限元分析

通过有限元软件ANSYS,分别计算了加氢反应器筒体在启动和稳态操作情况下的温度及热应力分布.结果表明,加氢反应器堆焊层与基层的交接区产生热应力集中,同时温度的快速上升对筒体热应力也有一定的影响.     

复合式生物反应器硝化作用动力学模型

依据物料平衡方程和Fick定律,结合活性污泥.生物膜复合工艺的实际情况,建立了一个可指导实际工程设计的简单硝化动力学模型,并通过实验室试验和生产性试验对模型进行了验证.验证结果表明理论值和实测值符合的很好,模型能够较好地预测系统出水的氨氮浓度,且适合工程实际计算.     

大型精制反应器的有限元分析

使用ANSYS有限元分析软件建立了大型精制反应器的三维有限元模型,在考虑包括地震等各种载荷的基础上,对它在不同载荷工况下的应力强度进行了计算,并依据JB4732《钢制压力容器-分析设计标准》进行了应力评定。结果表明该精制反应器各部分满足强度条件。     

费托合成浆态床反应器模型研究进展

基于文献中的热态研究成果,总结了费托合成浆态床反应器模型的研究进展,并根据流动状态的理想性、气泡分类、模型的维度和模型研究方法对相关的研究工作进行了梳理和总结. 经过分析归纳,认为费托合成浆态床反应器模型的复杂度日益提高,与实际反应情况越来越接近,结合CFD技术,以多维度、多气泡群、非理想流动为特征的模型是未来研究工作的趋势. 对模型建立过程中必需的气液平衡和产物分布计算方法进行了系统的调研与分析,认为Henry定律适于合成气溶解度计算,而状态方程适于产物分布计算.     

喷雾反应器中甲烷水合物生长动力学模型

提出了喷雾反应器中甲烷水合物的形成机理,并引入传质对水合反应影响的有效因子等参数,得到了喷雾法生成水合物的改进动力学方程.通过实验验证,实验数据与模型计算数据基本吻合,平均误差为4.63%.方程回归得出甲烷水合物表观活化能(Ea)为54.25 kJ/mol,根据文献结果,说明喷雾反应器中甲烷水合物生长过程由表面反应所控制.     

重油加氢反应器八角垫动态密封失效有限元分析

采用有限元方法 ,建立了在高温条件下的法兰八角垫联接的三维力学 -热传导耦合的计算模型 ,并对其动态密封性能等进行了分析。计算结果和实测数据较为吻合 ,表明数值模拟较好地反映了法兰联接的动态密封特点。对高温动态密封失效的机理进行分析 ,在此基础上提出了防止泄漏的基本措施。     

SCR反应器结构有限元分析及其改进措施

利用Ansys软件,按照实际工程的结构形式和尺寸建立SCR反应器的三维有限元模型,在考虑自重、烟气压力及风载等荷载的组合工况下,计算反应器各个构件的内力和整体变形,参考分析设计标准,校核数值模拟结果,为反应器结构的可靠性和优化措施提供了依据。     

有限元方法求解化学气相淀积反应器模型(Ⅱ)——热壁反应器模型及反应器中流动及传递过程的分析

分析了热壁化学气相淀积反应器在流型、温度和浓度分布以及淀积速率等方面与冷壁反应器的异同,探讨了流动特性、传递过程和反应器几何尺寸对淀积过程的影响,为淀积不同薄膜时反应器的选型及设计提供了方法和依据.     

鼓泡塔反应器的多级回流模型

对鼓泡塔反应器提出:气相用多级串连混合器模型,对其液相用带回流的多级混合器模型.中间各级液相中气体组分浓度假定为前后两级的平均值.从而可以逐级计算气、液浓度和气量沿塔高的分布.模型应用的范围可包括非一级反应及气体压强、气体量和气体组成沿塔高变化的情况.用所提出的模型验算了两个小型鼓泡反应塔的热模试验情况,所得结果与所观察到的现象相符.     

换热型一段炉运行状况的分析

本文对LCA流程中的转化炉管内外运行过程进行了分析及讨论。结果表明,管内外传热温差较小,且由上至下呈增加趋势。     

连续换热式耐硫甲烷化反应器的模拟与分析

建立了逆流换热的耐硫甲烷化列管式反应器的拟均相二维模型。运用差分将模型降阶为一阶常微分方程组,采用Ｒｕｎｇｅ－Ｋｕｔａ法求解。模拟结果是可信的。分别考察了设备参数和操作条件对反应床层的影响,结果表明：管径对温度分布影响很大;反应温度和压力是反应器操作的控制因素;原料气组成制约反应结果     

ON THE ANALYSIS OF NONCATALYTIC GAS-SOLID KINETICS DATA HAVING WEAK TEMPERATURE DEPENDENCE

Noncatalytic gas-solid reactions should exhibit strong temperature dependence when the rate is controlled by surface kinetics. However, there are a number of examples in the literature where apparent activation energies less than 10 kcal/mol have been reported as being representative of intrinsic kinetics. This conclusion is often based on electrobalance data in which large gas Row rates were used to eliminate mass transfer resistance and the fact that fractional conversion-time results are consistent with the surface kinetics control version of a gas-solid reaction model.

The oxidation of FeS was studied in an electrobalance reactor as a function of O₂ mol fraction, temperature, and gas flow rate. The global rate was first-order in O₂ and weakly dependent on temperature and flow rate. Data analysis used the approximate solution to the grain model. The single-resistance surface kinetics variation of the model provided good match with the conversion-time data, but the apparent activation energy was only about 7 kcal/mol. A two-resistance mass transfer-product layer diffusion variation provided equally good match with the data, and the dependence of reaction coefficients on reaction variables was in general agreement with theory.     

EFFECTS OF HYDROCARBON LIQUID FEED IN POLYETHYLENE POLYMERIZATION PROCESS ON PARTICLE SURFACE TEMPERATURE

In the fluidized bed gas phase polymerization of polyethylene (PE), the heat generated by the exothermic polymerization process is dissipated into the gas mixture flowing past the polymer particles. The polymer particle temperature is determined by the extent of convective heat transfer and other mechanisms of heat removal. In addition to the heat removal by convective heat transfer, liquid hydrocarbon (HC) is often injected into the reactor to further remove heat by evaporation but without partaking in the reaction. The effects of adding this liquid HC on the particle surface temperature have been investigated numerically by means of a one-dimensional polar model. Results indicate that the primary mechanism for removal of the heat of polymerization from the particles is by means of convective heat transfer to the bulk gas, which amounts to 99.5% removal of total heat of polymerization. The PE particle temperature rises only by 1–2°C above the surrounding bed gas mixture. The addition of liquid HC to the feed, however, has a pronounced effect on controlling the reactor gas temperature as most of this liquid is evaporated to the gaseous phase before it reaches the polymer particles. To state it clearly, heat of polymerization is transferred from the particles to the reactor bulk gas predominantly by convection, and part of this heat is subsequently absorbed by evaporation of the fresh liquid HC in the feed. Comparison with a detailed computational fluid dynamic (CFD) model of polymerization in a generic gas phase reactor has also been conducted. The results confirm that the particle temperature rise above the reactor gas temperature is consistent with the one-dimensional model. However, local gas temperature variations are present in the reactor due to the unsteady gas-solid hydrodynamics. Hence, there are some zones that are a few degrees hotter/colder than the bulk reactor temperature with corresponding increase/decrease in particle temperature in these zones.     

EFFECTS OF HYDROCARBON LIQUID FEED IN POLYETHYLENE POLYMERIZATION PROCESS ON PARTICLE SURFACE TEMPERATURE

In the fluidized bed gas phase polymerization of polyethylene (PE), the heat generated by the exothermic polymerization process is dissipated into the gas mixture flowing past the polymer particles. The polymer particle temperature is determined by the extent of convective heat transfer and other mechanisms of heat removal. In addition to the heat removal by convective heat transfer, liquid hydrocarbon (HC) is often injected into the reactor to further remove heat by evaporation but without partaking in the reaction. The effects of adding this liquid HC on the particle surface temperature have been investigated numerically by means of a one-dimensional polar model. Results indicate that the primary mechanism for removal of the heat of polymerization from the particles is by means of convective heat transfer to the bulk gas, which amounts to 99.5% removal of total heat of polymerization. The PE particle temperature rises only by 1-2°C above the surrounding bed gas mixture. The addition of liquid HC to the feed, however, has a pronounced effect on controlling the reactor gas temperature as most of this liquid is evaporated to the gaseous phase before it reaches the polymer particles. To state it clearly, heat of polymerization is transferred from the particles to the reactor bulk gas predominantly by convection, and part of this heat is subsequently absorbed by evaporation of the fresh liquid HC in the feed. Comparison with a detailed computational fluid dynamic (CFD) model of polymerization in a generic gas phase reactor has also been conducted. The results confirm that the particle temperature rise above the reactor gas temperature is consistent with the one-dimensional model. However, local gas temperature variations are present in the reactor due to the unsteady gas-solid hydrodynamics. Hence, there are some zones that are a few degrees hotter/colder than the bulk reactor temperature with corresponding increase/decrease in particle temperature in these zones.     

CONTRIBUTION TO THE ANALYSIS OF THE SELECTIVITY OF GAS-LIQUID REACTIONS PART II: COMPARISON OF EXPERIMENTAL RESULTS WITH MODEL PREDICTIONS

The chlorination of paracresol is used in an experimental study of selectivity in gas-liquid contactors.

Experiments in a batch reactor show the influence on selectivity of the dimensionless numbers presented in Part I and involving competition between mass transfer and chemical reaction together with the hydrodynamics.

The extension of open reactor model presented in Part 1 to the batch reactor permits a comparison between theory and experiments and shows a good agreement     

ON THE ANALYSIS OF NONCATALYTIC GAS-SOLID KINETICS DATA HAVING WEAK TEMPERATURE DEPENDENCE

Noncatalytic gas-solid reactions should exhibit strong temperature dependence when the rate is controlled by surface kinetics. However, there are a number of examples in the literature where apparent activation energies less than 10 kcal/mol have been reported as being representative of intrinsic kinetics. This conclusion is often based on electrobalance data in which large gas Row rates were used to eliminate mass transfer resistance and the fact that fractional conversion-time results are consistent with the surface kinetics control version of a gas-solid reaction model.

The oxidation of FeS was studied in an electrobalance reactor as a function of O₂ mol fraction, temperature, and gas flow rate. The global rate was first-order in O₂ and weakly dependent on temperature and flow rate. Data analysis used the approximate solution to the grain model. The single-resistance surface kinetics variation of the model provided good match with the conversion-time data, but the apparent activation energy was only about 7 kcal/mol. A two-resistance mass transfer-product layer diffusion variation provided equally good match with the data, and the dependence of reaction coefficients on reaction variables was in general agreement with theory.     

ESTIMATION AND ANALYSIS OF THE INFLUENCE OF INTERFACIAL GRADIENTS IN A FIXED BED ADIABATIC CATALYTIC REACTOR

The influence of the interfacial gradients on the performance of a fixed bed adiabatic catalytic reactor cannot generally be determined only at the reactor inlet conditions because the magnitude of the gradients vary along the reactor. A very simple method for the estimation from inlet conditions of the maximum interfacial temperature gradient is developed. A very good agreement with values obtained from the numerical solution of the balance equations is found.

An analysis of the relative importance of the interfacial concentration and temperature gradients is also carried out. A parameter Lm, that is a good measure of the influence of each one of these gradients in the reactor, is introduced.     

煤与生物质的共热解

对近年来煤与生物质共热解的研究作了综述，研究的焦点集中在富氢的生物质向贫氢的煤的转移，即寻找是否存在所谓的协同效应，在固定床，流化床等类型反应器中煤与生物质共热解的研究没有发现协同效应，这主要是因为煤与生物质热解温度的差异所造成的，至今还没见到在自由落下床中煤与生物质共热解的研究报道，在这种类型的反应器中，物料自由落下，物料粒子的温度很大程度上依赖于其黑度，由于煤的黑度远远大于生物质的黑度，在自由落下床中可以使二者达到同步热解，此外，生物质热解产生的富氢气体可以作为煤加氢热解的氢源，在这个基础上，提出了两步法共热解的思路。