Mathematical modelling of coke formation in thermal cracking units

乙烷热裂解是天然气制取乙烯等低碳烯烃的重要工业工艺。这些烯烃被用来制造聚乙烯和其他重要的商业塑料。热裂解过程是由乙烷和蒸汽在通过炉子的金属管中反应而成的。在管子外部的燃烧室中产生的热量使管子内部的裂化反应以高速率发生。热裂解过程的一种不受欢迎的副产品是焦炭。焦炭是沉积在管子内表面的固体材料(主要是碳)，影响化学反应的速度和从反应器中涌出的化学产品的分布。Nova化学公司和其他设计和运营热裂解炉的公司希望彻底了解影响乙烷裂解、结焦和焦炭去除的化学反应和操作条件。这项研究的目的是开发和验证一个模型(即，计算机程序中的一组数学方程)，NOVA将使用该模型来预测工业乙烷裂解炉中的焦炭形成和清除。该模型将解释一系列详细的化学反应，并将能够根据反应堆运行条件和炉子设计的变化预测焦炭积累。来自文献的数据和Nova生成的数据将被用来估计模型参数(在方程中使用的数字)，以便模型将给出准确的预测。由此产生的动态管式反应器模型将被Nova的科学家和工程师用来模拟和改进工业裂解反应器的运行，从而实现更经济的乙烯生产。此外，还将加强对导致焦炭形成的各种化学反应的重要性的认识。该模型将为女王学院开发的统计方法提供一个有价值的测试问题，导致对复杂模型的参数选择和估计方法的新见解。硕士研究生将在Nova获得经验，并将发展建模和统计技能，这将对未来的雇主有利。

Thermal cracking of ethane is an important industrial process for making ethylene and other light olefins from natural gas. These olefins are used to make polyethylene and other commercially important plastics. The thermal cracking process is performed by reacting ethane and steam in metal tubes that pass through a furnace. Heat generated in the combustion chamber outside the tubes makes the cracking reactions inside the tubes occur at high rates. An undesirable side product of the thermal cracking process is coke. Coke is solid material (primarily carbon) that deposits on the inner surface of the tubes, influencing rates of chemical reactions and the distribution of chemical products that emerge from the reactor. NOVA Chemicals and other companies who design and operate thermal cracking furnaces want to have a thorough understanding of the chemical reactions and operating conditions that influence ethane cracking, coke formation and coke removal. The objective of this research is to develop and validate a model (i.e., a set of mathematical equations inside a computer program) that NOVA will use to predict coke formation and removal in industrial ethane cracking furnaces. This model will account for a detailed array of chemical reactions and will be able to predict coke accumulation in response to changes in reactor operating conditions and furnace design. Data from the literature and data generated by NOVA will be used to estimate model parameters (numbers to use in the equations) so that the model will give accurate predictions. The resulting dynamic tubular reactor model will be used by NOVA scientists and engineers to simulate and improve the operation of industrial cracking reactors, resulting in more economical production of ethylene. In addition, enhanced knowledge of the importance of the various chemical reactions that lead to coke formation will be obtained. The model will provide a valuable test problem for statistical methods developed at Queen's, leading to new insights about parameter selection and estimation methodology for complex models. A Master's student will obtain experience at NOVA and will develop modeling and statistical skills that will be of benefit to future employers.