4. Process simulation
The main aim of the process simulation was to define the opti- mal characteristics and operating conditions of the unit of an industrial multi-tubular fixed bed reactor for ethylene production.
4.1. Model equations
Mathematical modeling of the ethanol dehydration process was performed by using the previously elaborated comprehen- sive mathematical model of tubular fixed bed reactor incorporated with a dusty-gas model for a catalyst grain solution [14]. A
two-dimensional pseudo-homogeneous model accounts for heat transfer between the tube wall and catalyst bed, conductivity and diffusivity in the radial direction in the packed bed and intraparti- cle diffusion. Kinetic rate expressions, presented in Section 2, were used for determination the apparent rates over the catalyst pel- let.
and the index of ethanol/raw ethylene consumption just slightly decreases because of the increase in ethanol conversion. The outlet dry gas composition at temperature 423 ◦ C and the residence time
2.1 s is presented in Table 4.
Long-term catalyst stability testing was carried out at the ther- mostat temperature 450 ◦ C and the residence time 4.1 s. The run time was about 72 h in total. Initial and final values of ethanol con- version and ethylene selectivity during stability tests practically have not change.
The differences between initial and final catalyst character- istics during stability tests practically have not changed. During long-term testing at conditions described above ethanol conver-
was performed for series of experiments obtained in the pilot reactor. The experimentally determined data viz. temperature profiles in reactor, ethanol conversion and product selectivities were compared with the calculated ones for different operation regimes.
In Fig. 8 the comparison between measured and simulated tem- perature profiles in pilot reactor is demonstrated. Corresponding data on the outlet ethanol conversion and product selectivities are presented in Table 5. From Fig. 8 and Table 5 it is evidently that simulated and experimental data are in a good agreement. This fact proves that the reactor model and kinetic equations can be applied in design and optimization of the industrial multi-tubular reactor for ethylene production.