Equilibrium Reactor - Technical Information
The Equilibrium Reactor simulates a chemical reactor by solving the heat and material balances based on supplied reaction equilibrium data. There is no limit to the number of simultaneous reactions which may be modeled.
The reaction stoichiometry must be defined in the Reaction Data Sets Window before the reactor performance can be specified. Note that reaction sets may contain more than one reaction. Equilibrium equation data may be entered in the reaction set or in the reactor unit operation. Data entered in the unit operation override data entered in the reaction set for that unit only.
Calculation Method
The composition of the feeds and products of a reaction at equilibrium are calculated from the equilibrium constant, K, by the following equation:
For example, in the reaction:
then, 
where 
etc. are the activities of components A, B etc.
PRO/II expresses Liquid Activity in terms of Mole Fraction, Molar Concentration, Activity, and Fugacity & Vapor Activity as Partial Pressure, Mole Fraction, Molar Concentration and Fugacity.
You define the equilibrium constant K by entering the coefficients A, B, etc., of the equation:
You can impose an approach to equilibrium in the Equilibrium Reactor - Extent of Reaction Window. This may be either a temperature or fractional approach. If a temperature approach, DT, is entered, the equilibrium constant is calculated at the temperature, T, where:
- endothermic reaction
- exothermic reaction
A fractional approach may be defined as a function of temperature, T, by entering the coefficients for the equation:
The conversion of the defined base component is then determined by:
Actual Conversion = Approach * Equilibrium Conversion
When only library components are present, heat of reaction is normally calculated by PRO/II from heat of formation data. Alternatively, heat of reaction data may be supplied in the Reaction Data - Heat of Reaction Data Window for any or all reactions. If non-library components take part in a reaction, either heat of formation or heat of reaction data must be entered.
By default, the reactor operates isothermally at the feed temperature. A different isothermal temperature or a duty may be specified instead.
Rigorous modeling of two liquid phases is possible by specifying VLLE thermodynamics in the Thermodynamics Main Window.
Feeds and Products
The equilibrium reactor unit can have any number of feed streams. The inlet pressure is taken to be the lowest pressure of all the feed streams.
The reactor can have up to four process product streams, with each stream containing a different phase. The possible phases are vapor, liquid, decanted water or second liquid, a mixture of liquid and vapor, and solids. If there are multiple product streams leaving the reactor, the phase condition for each stream must be specified using the Product Phases Window.
