APMonitor is advanced process control and optimization software for industrial-scale systems. The software interfaces to live systems to provide advanced diagnostics, meet safety and environmental constraints, and drive the process to economic optimum. With rapidly changing feedstock and commodity pricing, this application enables instant and continual realignment to real operating objectives. These may include:
  • Meet regulatory reporting requirements
  • Flow assurance of oil and gas transport pipelines
  • Visualize data from remote locations
  • Reduce alarms by consolidating relevant information
  • Provide soft sensing
  • Automatic control of continuous and batch systems
  • Increase production 3-5% without equipment changes

A number of prebuilt asset models are available with the APMonitor software. The chemical processing modeling package includes reactors, distillation columns, and compressors necessary for industrial scale processes.


APMonitor, or "Advanced Process Monitor" is a modeling language for differential and algebraic (DAE) equations. It is used for describing and solving representations of physical systems in the form of implicit DAE models. APMonitor is suited for large-scale problems and allows solutions of dynamic simulation, moving horizon estimation, and nonlinear control. APMonitor does not solve the problems directly, but calls appropriate external solvers.


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Differential and Algebraic Equations

Differential and algebraic (DAE) models are a natural expression of systems that change with time. These dynamic systems may be as simple as a falling apple or as complex as biological metabolic pathways. DAE models are generally easy to write but often difficult to solve analytically. Entire university level courses are devoted to the solution of particular types of differential equations in analytic form. Solution of more complex systems is better handled through numeric approaches. There are many software packages that can solve DAE models for small and medium size problems. APMonitor is designed to solve large-scale problems. Additionally, other software packages often require the user to reformulate the equations into a restrictive form. APMonitor allows an open-equation format that is less restrictive.


APMonitor Overview

APMonitor software is a modeling, simulation, and optimization environment for large-scale models of differential and algebraic equations (DAEs). These models are employed in seven solution modes:

The DAE model does not have to be changed to switch between the modes. The same model is used for parameter fitting, dynamic simulation, optimization, and control. The user is required to define the model and the software automatically configures the various simulation options.

Solution options

APMonitor uses a simultaneous solution approach to solve the differential equations. The differential equations are converted to algebraic equations and solved with large-scale sparse solvers. There are an assortment of solvers available with various user's licenses, ranging from free and open-source to commercial.

Chemical Process Flowsheets

A thermodynamic database and a number of prebuilt nonlinear models are available with APMonitor. The chemical processing modeling package includes polymer reactors, distillation columns, compressors, valves, etc. These models are combined to form a flowsheet in an object-oriented environment.

Essential Files for Simulation

  • model.apm: To generate a new model, create a text file and save it with an apm extension.
  • model.info: The info file contains designation of special variables for trending, data acquisition, and mode-specific actions. If no variables are treated specially, the info file can be blank.
  • model.dbs: The dbs file contains all of the user-defined options that control how the solution is performed. When no dbs file is present, a new file is generated with default parameters.

Documentation Overview

The basic structure of the documentation is outlined into four main sections: model structure, modes of operation, system files, and obtaining solutions. The documentation is presented in a Wiki format to allow collaborative modification by any user. This format is well suited to APMonitor as it allows for collaboration and continuing development.