Piston flow reactor liquid-phase

Solution of the design equations for liquid-phase piston flow reactors is usually easier than for gas-phase reactors because pressure t5q)icaUy has no effect on the fluid density or the reaction kinetics. Extreme pressures are an exception that theoretically can be handled by the same methods used for gas-phase systems. The difficulty will be finding an equation of state. For ordinary pressures, the... 

Computational Scheme for Liquid-Phase PFRs. The following is a procedure for solving the reactor design equations for a moderate-pressure, liquid-phase, piston flow reactor using the marching-ahead technique (Euler s method) ... 

Piston Flow in Contact with a CSTR. A liquid-phase reaction in a spray tower is conceptually similar to the transpired-wall reactors in Section 3.3. The liquid drops are in piston flow but absorb components from a well-mixed gas phase. The rate of absorption is a function of as it can be in a transpired-wall reactor. The component balance for the piston flow phase is... 

In a properly operated bubble-column reactor, the liquid phase can be considered to be perfectly mixed, i.e. concentrations in the liquid are the same everywhere and correspond to those in the effluent. The gas is supposed to flow like a piston, i.e. the reactor is a plug-flow reactor with respect to the gas. These two assumptions are not entirely true, but within a certain flow regime they are not far from the reality. 

The value oik a can, in certain circumstances, be determined by purely physical experiments in the reactor. For instance, kifi may be evaluated from the observed total rate of absorption in the case of a piston-like countercurrent flow of the two phases, where C% becomes a known function of CaOj or where the gas and the liquid are well stirred, so that and Cao are the same at all points. 

The value of kga can in certain circumstances be determined by purely physical experiments in the reactor, for instance in the case of piston-like countercurrent gas-liquid flow or when both phases are wel1-stirred. However, the rate of absorption depends on the residence time distribution in both phases that may be undetermined and in addition there is normally an appreciable resistance on the liquid side that must be taken into account. Thus the liquid side resistance can be eliminated and the rate of absorption can be made independent of the liquid side residence time distribution by using a solution which reacts instantaneously and irreversibly with the dissolved gas so that there is no back-pressure. Therefore,... 

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