Batch Equilibrium Reaction

General Description

This operation can handle any number of equilibrium reactions and supports a wide variety of reaction equilibrium expressions. It computes the conversion for any number of simultaneous reactions based on the equilibrium constants, the stoichiometric coefficients, and the component concentration exponents that the user specifies.

Unit Procedure Availability

      Batch Vessel Procedure in a Reactor

      Batch Vessel Procedure in a Seed Reactor

      Batch Vessel Procedure in a Bioreactor

      Batch Vessel Procedure in a Seed Bioreactor

      Batch Vessel Procedure in a Disposable Bioreactor

      Batch Vessel Procedure in a Disposable Seed Bioreactor

      Batch Vessel Procedure in a Fermentor

      Batch Vessel Procedure in a Seed Fermentor

      Batch Vessel Procedure in a Disposable Bioreactor

      Inoculum Preparation Procedure in a Rocking Bioreactor

      Inoculum Preparation Procedure in a Roller Bottle

      Inoculum Preparation Procedure in a T-Flask

      Inoculum Preparation Procedure in a Shake Flask

      Inoculum Preparation Procedure in a Test Tube

      Batch 1x1 Generic Box Procedure

      Batch 3x3 Generic Box Procedure

      Batch 5x5 Generic Box Procedure

      Batch 10x10 Generic Box Procedure

Equilibrium Reaction Operations: Modeling Calculations

Material Balances

Consider the following equilibrium reaction

BatchEquilRxn.jpg 

eq. (A.47)

Define the extent of reaction, ξ, as follows:

BatchEquilRxnExtent.jpg 

eq. (A.48)

If νi is the stoichiometric coefficient of component i (negative for reactants, positive for products), the above equation can be rewritten as

BatchEquilRxnCompMB.jpg 

eq. (A.49)

and for multiple reactions, the above equation becomes:

BatchEquilRxnTotalCompMB.jpg 

eq. (A.50)

where:

      q is the number of simultaneous reactions,

      ni0 is the mole flowrate of component i in the feed, and

      ni is the mole flowrate of component i in the outlet stream (at equilibrium).

Further, for each reaction j we have the equilibrium relationship which can be written as:

BatchEquilRxnConst.jpg 

eq. (A.51)

If ξ= [ξ1, ξ2, ..., ξq] is used as a vector of independent variables with an initial value of zero, the above equations become equivalent to a system of nonlinear algebraic equations which are solved numerically for ξ. Substitution of the calculated ξ values into the above equations yields the composition of the reaction mixture at equilibrium. For the non-isothermal case, the temperature of the mixture T is another unknown and the energy balance relationship provides the additional equation for solving the system.

To account for emissions, the user can specify the percentage of each component that is emitted. Please note that the specified percentage is based on the composition of the reaction mixture after equilibrium is reached.

Thermal Mode

The equilibrium reactor can operate isothermally, adiabatically or with a specified heating or cooling duty. For adiabatic operation or for specified heating or cooling duty, the equilibrium temperature is an unknown variable that is calculated by the model. For isothermal operation (specified operating temperature), the energy balance equation is used to calculate the heating or cooling requirement.

Power Consumption

The average agitation power is estimated by multiplying the agitation rate (kW/m3 of liquid mixture) by the total liquid volume of the step. It is assumed that all agitation power eventually dissipates into heat that contributes to the heating or cooling requirements of the step.

Equipment Sizing

See Batch Vessel Operations: Equipment Sizing.

Vacuum Pump Power Consumption

See Vacuum Pump Auxiliary Equipment Calculations.

References

1.   Fogler, H. S. 1992. Elements of Chemical Reaction Engineering, 2nd edition, Prentice Hall.

Batch Equilibrium Reaction: Interface

The interface of this operation has the following tabs:

      Oper. Cond’s, see Batch Reaction Operations: Oper. Conds Tab

      Volumes, see Batch Vessel Operations: Volumes Tab

      Reactions, see Equilibrium Reaction Operations: Reactions Tab

      Vent/Emissions, see Reaction Operations: Vent/Emissions Tab

      Labor, etc, see Operations Dialog: Labor etc. Tab

      Description, see Operations Dialog: Description Tab

      Batch Sheet, see Operations Dialog: Batch Sheet Tab

      Scheduling, see Operations Dialog: Scheduling Tab