| Tubular reactor of multiphase turbulent flow is a common process in chemical engineering. Solid particles, usually in fine mesh size, mixed with solvent or reactants in a liquid phase, are fed into the reactor with pressurized gas. Heat released from the reaction, or supplied from the wall side, normally will keep the reaction occurring continuously. The local composition of the species is a function of temperature and pressure. To predict the pressure across the reactor requires knowledge of the flow regime, the flow rates of each phase, as well as the physical properties such as density and viscosity of the fluid. However, the flow rates of each phase and the flow regime of the flow is governed by the mass interchange between the gas and liquid phase. Furthermore, the temperature of the fluid is related to the reaction heat released and/or the heat input along the reactor. An overall heat and mass balance must be solved simultaneously at each station along the flow path. A simplified model is proposed to solve such problems. The physical properties such as density and specific heat are assumed to be a linear function of temperature only. The reaction will be limited to a first order reaction and only the turbulent annular flow regime will be considered. A computer program, based upon the finite difference method, is developed to solve these governing equations. Results are checked against the Wilsonville pilot plant data for the Solvent Refined Coal (SRC) process. Model parameters such as pressure drop, skin temperature, and viscosity are proposed to design the 6000 ton/day demonstration plant unit. Applications for this type of "pseudo" (the actual case is in fact a three-phase, solid, liquid, gas problem, but in this treatment the solid entrained in the liquid is approximated as a "single" phase) two phase flow (including reacting species) include: the destruction of PCBs and the cyanide waste treatment process. |
