A one-dimensional adiabatic mathematical model was developed for the riser reactor of an industrial residue fluid catalytic cracking unit (RFCCU). A seven-lump kinetic model was presented for the catalytic cracking of vacuum residue, taking cognisance of diffusion resistance, which is a departure from the general norm in the literature. Also, heat transfer resistance between the fluid and solid phases was incorporated into the energy balances for instantaneous and one-dimensional vaporization of feedstock. The developed model was a set of twelve coupled, highly non-linear and stiff ordinary differential equations, ODEs, which was numerically solved with an implicit MATLAB built-in solver, ode23t, designed deliberately for handling stiff differential equations to circumvent the problem of instability associated with explicit methods. An excellent agreement was achieved between the industrial RFCCU plant data and the simulated results of this study, with average absolute deviation being < ± 5% for instantaneous vaporization of feedstock in all cases investigated. Moreover, the simulated results revealed that half of the reactor was relatively redundant as this accounted for only 3% of the conversion. Hence, the findings of this study could be useful to the production practice for the Khartoum Refinery Company.

中文翻译：

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工业RFCCU立式反应釜中减压渣油催化裂化的建模与仿真

针对工业渣油流化催化裂化装置（RFCCU）的提升管反应器建立了一维绝热数学模型。考虑到扩散阻力，提出了一种七块动力学模型，用于真空渣油的催化裂化，这与文献中的一般规范背道而驰。同样，在液相和固相之间的传热阻力被并入能量平衡中，以进行原料的瞬时和一维汽化。开发的模型是一组十二个耦合的，高度非线性且刚性的常微分方程（ODE），使用隐式MATLAB内置求解器ode23t对其进行了数值求解，该求解器专门设计用于处理刚性微分方程，以解决不稳定问题与显式方法关联。在工业RFCCU工厂数据和本研究的模拟结果之间达成了极好的协议，在所研究的所有情况下，瞬时瞬时进料的平均绝对偏差均小于±5％。而且，模拟结果表明，反应器的一半相对多余，因为这仅占转化率的3％。因此，这项研究的结果可能对喀土穆炼油公司的生产实践有用。