Ideal Plug Flow Reactors

The plug flow reactor shall describe the chemical reactions in continuously flowing system. The plug flow reactor model will explain the chemical reactor behavior and key factors variables. The dimension of the reactor is well explained. The plug flow reactor is also defined as continuous tubular reactor (CTR’s). Fluid which passes through plug flow reactor can be modeled in series where in the fluid has the uniform composition and it travels in an axial direction of a reactor. The ideal plug flow reactor assumes that the fluid is completely mixed in radial direction and not in an axial direction. The plug of differential volume has a separate entity and act as an infinitesimally batch reactor which limit to zero volume.  When the fluid flows down through tubular plug flow reactor, the residence time denoted as τ is a function of reactor position. The ideal plug flow reactor has a residence time distribution which is a factor of Dirac delta function and is equal to τ.

Characteristics of ideal plug flow reactor

Following are characteristics of ideal plug flow reactor.

• There is a perfect mixing of fluid in the radial direction that is there exists uniform concentration in cross sectional area.
• In general, mixing does not occur in axial direction and also there is no axial dispersion of fluids.

The ideal plug flow reactor has concentration as a function of distance which flows along path, x and time, t and are represented as follows.

C = C(x, t)

The mass balance of axial element is represented as follows.

In = QCx and Out = QCx +dx

Generation = dVr_C = Adxr_C

Accumulation = dv (δCx/ δt) = Adx (δCx/ δt)

By partially differentiating the mass balance equation at steady state where (δCx/ δt) =0 shall yield

(dCx/dτ) = r_C

Questions:

• What is ideal plug flow reactor?
• Derive mass balance equation of ideal plug flow reactor.
• What are characteristics of ideal plug flow reactor?