【作者】 危丽琼；

【导师】 李成岳；

【作者基本信息】 北京化工大学 ， 化学工程， 2007， 硕士

【摘要】 丙烯腈是生产三大合成材料的重要化工原料,其吸收塔排放的尾气含有一氧化碳、丙烯、丙烷及痕量丙烯腈。该尾气如果直接放空,会对大气造成严重污染。本文相关的研究工作采用流向变换催化燃烧技术处理丙烯腈吸收塔尾气,考察了负载贵金属商业催化剂上丙烯腈尾气催化燃烧反应动力学,进行了中间带换热器的流向变换催化燃烧实验研究,在实验的基础上对流向变换催化燃烧反应器进行了模型化,并运用所得模型对反应器的操作性能进行了模拟和预测。首先,在消除内外扩散影响后,在微型固定床积分反应器中开展了国产HPA型负载贵金属催化剂上一氧化碳、丙烯和丙烷单组分及其三组分混合物催化燃烧的动力学实验研究。采用程序升温脱附手段考察了反应物在催化剂上的吸附、脱附情况,据此推测可能的反应机理,建立了单组分催化燃烧的Eley-Rideal本征速率模型。运用最小二乘估计和单纯形优化搜索方法对模型参数进行了估值,所得模型对反应物转化率的计算值与实验值吻合良好。将所得单组分动力学模型叠加用于预测多组分催化燃烧时,转化率的计算预测值与三组分混合物催化燃烧实验数据相容。其次,采用中间带换热器的流向变换反应器进行了丙烯腈尾气催化燃烧实验研究,考察了换向周期、进料浓度和空速等操作条件对混合物各组分转化率、床层热波特性以及反应器温度分布的影响,对极端情况如“飞温”和“熄火”等也进行了研究。然后,针对流向变换反应器的特点,建立了基于微分质量衡算和能量衡算,并考虑轴向弥散的一维非均相数学模型。运用半隐式、自适应、变步长有限差分法对模型微分方程组进行了求解。在广泛的参数变化范围内,将模型计算值与实验数据进行了比较,结果验证了模型的合理性和可靠性。最后,运用该模型计算了不同操作参数(如换向周期、空速、进料浓度)和设计参数(如催化剂装填量、惰性填料多少)对反应器特征温度的影响,初步预测了反应器维持正常操作的参数范围,为实际操作提供了理论指导。更多还原

【Abstract】 Acrylinotrile is one of the most important raw materials, and it has been widely used for synthetic materials, such as plastic, rubber and fiber. The off gas from the absorber of industrial plant contains carbon monoxide, propylene, propane, which will seriously pollute the environment if emitted freely. Thus, this study focused on the catalytic combustion of the absorber off gas using a reverse flow reactor. The intrinsic kinetics of catalytic combustion of the off gas were investigated, and the catalytic combustion in a reverse flow reactor with inter-heat exchanger was conducted, then modeling and simulation of the reverse flow reactor was used to predict the operating performance.Firstly, the catalytic combustion of the individual component and the mixtures of carbon monoxide, propylene and propane were investigated by using an integral microreactor under the condition without diffusion limitation. The adsorption properties of the reactants were probed by the TPD technique to distinguish the probable reaction mechanism. The Eley-Rideal kinetic models were selected to fit the experimental data of individual component conversions, and the parameters of the models were estimated through the partial least-square (PLS) method and simplex search optimization. The calculated conversion values of every component are in good agreement with the experimental data. Also, it is found that the conversions predicted by the individual component kinetic models are consistent with the experimental results of the mixture catalytic combustion.Secondly, the catalytic combustion of acrylinotrile off gas was systematically investigated in a reverse flow reactor with inter-heat exchanger. The influences of cycle period, space velocity, and feed concentration on operation performance of reactor with heat extraction were observed. The experimental results showed that, for the reverse flow reactor, cycle period, space velocity and feed concentration were three important operating parameters that obviously affect the axial asymmetry temperature profiles of the reactor. At the same time, the extinction and run-away behavior of reactor were observed to find the reasonable range of the operation parameters.Thirdly, a one-dimensional heterogeneous differential mathematic model describing the reverse flow reactor was derived carefully from mass and heat balance. The verification of this model was conducted by comparison of the simulated results with experimental data. The comparison showed that the mathematic model of reactor was reasonable, adaptable and robust. Then the model was employed to simulate the performance of the reactor with different operating and design parameters, and predict the range of suitable operating and design parameters.更多还原