To illustrate the parametric sensitivity analysis, the case of gaseous phase catalytic oxidation of benzene to maleic anhydride was considered (Lupușor et al., 1981). The multi-tubular reactor (heat exchanger type) with the fixed bed catalyst inside a small diameter tubes (under 3 -4 cm) is continously cooled by molten salt mixture (nitrates and nitrites mixture; Maria , 2007). The raw materials are air (oxygen) and benzene. The compressed and filtered air is heated into a preaheter (using the heat coming from the reactor outlet) is mixd with benzene vapours at a concentration below the lower explosion limit (LEL, 1.5%). The benzene/air …show more content…
1. Chemical reactions involved in the oxidation of benzene (adapted from Lupușor et al., 1981)
In order to achieve such an analysis, a simplified mathematical model of the reactor was used considering a pseudo-homogeneous, one-dimensional, plug-flow reactor. Model equations are presented in the Table 1 in terms of the mass balance of the considered chemical species, heat and moment balance, with the rate constants given in Table 2:
Table 1. The fixed bed multi-tubular reactor model used for benzen oxidation to maleic anhydride
Mass balance differential …show more content…
Momentum balance: - friction coefficient calculated by Ergun and Hicks formula:
- Reynolds number for flow through the catalytic bed. - catalyst particle diameter, m; - gas flow velocity, ; - gas density, ; - gas viscosity, . (Froment and Bischoff , 1990)
The model hypotheses:
Molten salt bath temperature (cooling agent) is considered