Chemical Process Calculations (CPC) is computer software for solving industrial chemical kinetics problems. The CPC program uses the well-known DARC model to calculate the concentrations of one or more species involved in a chemical process. The relative rates of formation and consumption of each species are expressed as temperature, pressure, space velocity (flow rate), catalyst activity, reactor geometry, and composition.
The program is flexible enough to handle a wide variety of chemical reactions.
In the past, CPC has been used for applications in petroleum technology, synthetic fuels, pharmaceuticals, food chemistry, and environmental protection. Chemical process calculations have also been performed as part of ongoing R&D at companies such as Union Carbide Corp., Inco Ltd., PPG Industries, Inc., Monsanto Chemical Co., Allied Chemical Corp, and BASF-Wyandotte Corp.
CPC was first released in the mid-1970s for IBM mainframe computers (OS/MVS), and later ported to other operating systems such as Unix and Linux. CPC is written in Fortran 77, with some statements in Fortran 90.
The DARC 2.1 version of CPC has been updated with a new graphical user interface (GUI). The original command-line version remains available and uses the same input files as before.
Input data formats for chemical process calculations have changed from earlier versions. New input file templates are used, which provide an opportunity for more thorough data checking. Some mandatory information can be entered as text comments which are not processed by the program.
In addition to chemical kinetics, a wide range of thermodynamic and transport properties for pure chemicals and mixtures can be calculated from either published or user-defined reference equations. An extensive collection of physical property correlation equations is included with all standard methods for vapor pressure, viscosity, thermal conductivity, and many others.

Use cases

The following are some examples of how CPC has been used in the past. Future changes to the DARC 2.1 version may include new features suitable for users within these categories of application:

Petroleum-refinery optimization
Biomass gasification
Chemical reactor design by simulation
Catalyst deactivation
CPC software can be used to predict reactions and rates of chemical processes under a variety of conditions. The CPC program solves a set of first-order differential equations with respect to a single independent variable for a number of species simultaneously. This includes the traditional “transport” variables (mass fraction, molar concentration) and more advanced variables, including activity coefficient or molar excess. Standard methods for pressure, temperature, and composition are available in the calculation of transport properties. A wide range of advanced equations for vapor-liquid equilibrium properties are also included.