【作者】 车圆圆；

【导师】 何潮洪；

【作者基本信息】 浙江大学 ， 化学工程， 2012， 博士

【摘要】 典型含能化合物的合成往往涉及易失控反应过程,反应过程的温度变化较剧烈,温度场、速度场、浓度场之间的耦合效应大,若工艺条件控制不当,容易产生大量副产物,并可能导致反应失控、飞温爆炸。论文对含能化合物合成中广泛应用的釜式和管式反应过程进行了研究,开发了一种适合于易失控反应过程的搅拌桨,设计了新型釜式反应器和管式反应器,并对其进行了模拟和优化,较好地实现了易失控反应过程的安全调控。主要研究内容如下：1.在易失控半间歇反应过程中实际搅拌器的安装高度往往较低,流体对桨叶背部的冲击较大,且为了搅拌混合均匀,一般都设置较高的转速,耗能较大。通过研究在强放热条件下九种不同类型、尺寸的搅拌桨转速不同时对反应釜内传热过程的影响,选择了传热效果优良的搅拌桨,并在此基础上设计了适用于易失控反应过程的新型搅拌器(CBY-H)。新型搅拌器通过在桨叶片上开设的梯形孔槽减少了流体对搅拌桨叶面背部的冲击力,减小搅拌器的振动,加强轴向循环和流动,且可以让反应生成的气体顺利的传输与逸出。此外,所述的翼型搅拌器的搅拌功率小于一般的翼型桨,能耗低。2.由于搅拌器的复杂性和多样性,基于计算流体力学(CFD)的预测技术在搅拌器的设计中得到了广泛的应用。深入了解不同搅拌器搅拌釜内流场的分布、搅拌功率和传热系数的大小对含能化合物合成过程中使用的搅拌设备的优化设计具有重要的意义。本文采用数值模拟的方法对CBY-H桨无挡板搅拌釜内流场的速度分布和搅拌功率进行了详细的研究。通过将研究结果与标准的CBY桨流动性能进行比较,对CBY-H桨的流场特性和能耗进行了评定。同时,测定了CBY和CBY-H桨的传热系数,获得了釜内流体对流传热系数的关联式,为搅拌器的优化设计和工业放大提供一定的指导。3.许多含能化合物的合成过程涉及硫酸铵+硝酸铵+水等三元电解质体系。本文在T=(278.15～333.15)K下,较大浓度范围内测定了硫酸铵+水、硝酸铵+水和硫酸铵+硝酸铵+水体系的导热系数和密度数据,并获得相应体系的密度和导热系数的关联方程,用于易失控反应过程的优化设计。4.在含能化合物生产过程中,很多化学反应是在搅拌反应釜中进行的强放热反应,当反应热不能有效移出时,便会导致反应热的蓄积,温度进一步升高,使反应釜局部过热,出现“热点”、飞温失稳现象,进而引起反应失控,甚至是热爆炸,严重影响财产和生命安全。因此,本文针对某易失控釜式缩合过程展开了研究,确定了快速传递热量的反应釜的结构,设计了一种新型缩合反应釜,建立了某易失控釜式缩合过程的数学模型,模拟了含能中间体合成过程中缩合反应的失控、飞温情况,提出了相应的技术预防与应急措施,优化了缩合反应过程的工艺条件,获得了操作安全、收率较高的含能化合物的生产工艺。在中试装置上进行了稳定批实验,数值模拟结果与实际工艺优化的结果相符,可用于对含能中间体的工业生产进行指导和预测。5.由含能中间体制备某含能化合物的合成过程包括混合、硝解和热解等阶段,硝解反应机理复杂,副反应多,是该过程的控制步骤,硝解反应工艺的优化对含能化合物收率和选择性的提高具有重要的意义。本文针对某易失控管式硝解过程展开了研究,建立了含能中间体硝解过程管式反应器的流动-扩散-反应模型,利用脉冲进样模拟了螺旋管式反应器的流动特性,通过停留时间分布计算了实际硝解反应的轴流扩散系数、Peclect数以及Dα数,模拟了经管式反应合成含能目标产物的收率,在中试装置上进行了稳定批实验,数值模拟结果与实验结果吻合很好,可用于指导和预测含能化合物的工业生产。同时,基于上述研究设计了一种新型的适用于反应中生成气体的内置弹簧管式反应器,它具有比普通管式反应器更优良的传热性能,且能有效防止气液两相段塞流的形成,具有良好的反应效果。更多还原

【Abstract】 Typical energetic compound synthesis often involves easily runaway reaction. In the process, the temperature rapidly change and coupling effects among the temperature, velocity, and concentration fields are significant. If the process conditions are not properly controlled, a large amount of byproducts are easily produced, which results in reaction runaway and temperature explosion. In the dissertation, tank and tubular reaction processes widely used in the energetic compound synthesis have been studied, a novel impeller applied to easily runaway reaction has been developed, a new pattern of stirred tank reactor and tubular reactor have been designed, simulated, and optimized, thus the security regulation of easily runaway reaction processes has been fully realized in the industrial production of energetic compounds.The main contents are generalized as follows:1. In the easily runaway semi-batch reaction processes, the actual impeller installation height is often low, the impact of fluid on the blade back is very remarkable, and a high stirred speed has been set so as to mixing evenly, which cause high energy consumption. Through the research on heat transfer performances in the stirred tank reactor with nine types of impellers under different dimensions and rotational speeds, the adequate impeller was determined, and thus a novel impeller (CBY-H) applied to easily runaway reaction was devised. The new impeller reduces the impact of fluid on the blade back surface and the vibration of agitators, allows smooth transmission and escape of gases generated in the reaction as well. In addition, the power consumption of the new impeller is much lower than general hydrofoil impeller.2. Due to the complexity and diversity of impeller, forecasting techniques based on computational fluid dynamics (CFD) have been widely used in the design of impellers. Comprehensive understandings of flow field distribution and the magnitude of stirring power and heat transfer coefficients are of great significance in optimization and design of mixing equipments used in the energetic compound synthesis. In the dissertation, the velocity field distribution in the unbaffled stirred tank reactor and stirring power of CBY-H paddle have been detailedly studied by CFD method. The flow field characteristics and energy consumption of CBY-H were evaluated through simulation results compared with the standard CBY impeller. The convective heat transfer coefficients of CBY and CBY-H impeller have been meanwhile determined and correlated, which could be applied to guide the industrialization and optimization design of impellers.3. Due to many energetic compound synthetic processes involving ammonium sulfate+ammonium nitrate+water ternary electrolyte systems, the thermal conductivity and density of ammonium sulfate+water, ammonium nitrate+water, and ammonium sulfate+ammonium nitrate+water have been measured covering a temperature from (278.15to333.15) K over a wide range of concentrations. The correlation equations of the thermal conductivity and density for corresponding systems determined could be used to optimize the easily runway processes.4. In the energetic compound synthesis, the majority of chemical reactions carried out in stirred tank reactors is highly exothermic. When the reaction heat is not effectively removed, it will lead to reaction heat accumulation and temperature further increasing, thereby causing local overheating of the reactor and emerging of hot spots and runaway instability phenomena, which further leads to the reaction out of control and thermal explosion, and thus threatens the safety of properties and lives. In the dissertation, the easily runaway tank condensation process has been studied to determine the structure of the reactor for released heat rapid transmission, a novel type of condensation reactor has been designed, the mathematical model for the easily runaway condensation process has been established, the runaway and out-of-control cases of the condensation reaction in the synthetic process have been simulated, the appropriate prevention and emergency measures have been proposed, the process conditions of the condensation reaction process have been optimized, and thus the safe-operation and high-yield production technology of the energetic compound has been acquired as well. The stable batch experiments have been carried out in the pilot-scale equipments. It is found that simulation results are consistent with results of the actual process optimization, which therefore could be used for guiding and forecasting the industrial production of the energetic intermediate.5. The preparation process of the energetic compound from the energetic intermediate contains several stages, including mixing, nitrolysis and thermolysis. Because of complex reaction mechanism and excessive side reactions, the nitrolysis reaction is the control step of the process. In the dissertation, the easily runaway tubular nitrolysis process has been studied, the mathematical flow-diffusion-reaction model for the tubular reactor used in the easily runaway nitrolysis process has been established, the flow characteristics of the spiral tubular reactor has been simulated using pulse injection, axial diffusion coefficient, Peclect number and Da number of the actual nitrolysis reaction have been calculated by analysis of residence time distribution, the yield of manufacturing the target energetic product through tubular reaction has been simulated as well. The stable batch experiments have also been carried out in the pilot-scale equipments. It is found that the agreement between the simulation and experimental results is pretty good, which therefore could be used for guiding and forecasting the industrial production of the energetic compound. Meanwhile, a new type of tubular reactor with spring internally installed applied to the process of gases generated in the reaction has been developed. The newly designed tubular reactor has more excellent heat transfer performances than ordinary ones, and can effectively prevent the slug flow generated in the binary gas-liquid phases. In addition, it has an outstanding reaction performance.更多还原