COCO - CAPE-OPEN to CAPE-OPEN simulation environment

Equilibrium reactor

The equilibrium reactor is a simplified reactor model for which only equilibrium reactions can be specified. It has one inlet and one outlet. Before running the equilibrium reactor, it needs to know about reactions. A reaction package must therefore be assigned to the equilibrium conversion reactor.

The equilibrium reactor implements a reactive flash: the phase equilibrium is calculated along with the reactive equilibrium. The reactions are in equilibrium in the phases in which the reactions take place (in the selected reaction package a phase is specified with a reaction). If the reaction phase is not present, the reaction will not take place.

If you know in advance that the resulting reactor product will only be single phase, it is advised to use a CSTR or Gibbs minimization reactor instead. If only equilibrium reactions are specified in a CSTR, the reactor volume is irrelevant; the CSTR, as opposed to the Equilibrium Reactor, is a single phase reactor. The Gibbs minimization reactor can be used for single-phase systems where the equilibrium constants are not known in advance.

Energy balance

The equilibrium reactor can be modeled either as an isothermal process, or as process with external heating or cooling. In the first case, outlet temperature is specified. In case of specified heat duty, the reactor temperature is calculated from the energy balance:

where H denotes the mixture enthalpy, Q the specified heat duty, rj the reaction extents and (-ΔHR,j) the heat of reaction for the j-th reaction (see enthalpy balance details below for heat of reaction).

For the enthalpy balance, three options are available: use enthalpyF, use enthalpy and heat of reaction, or use enthalpy and do not use heat of reaction. See reaction enthalpy for details.

The heat duty can be specified directly or via an energy inlet stream. If heat duty is not specified via an energy inlet stream, an energy outlet stream can be connected that will receive the heat duty for the reactor.

Other options

Pressure drop can be specified. The reaction takes place at the pressure after taking into account the pressure drop.

The equilibrium reactor is solved iteratively. Convergence tolerance and maximum number of iterations can be specified.


The last run report will show the extent of the reactions as they have taken place, the equilibrium constants as calculated at reaction conditions, the basis for which the equilibrium constants hold, and the heat balance details.