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The Residence Time Distribution program, RTD®, is intended for investigation of hydrodynamic flows in chemical apparatuses on the basis of the stimulus - response technique This technique includes the injection of a small amount of tagged inert particles (tracer) in the inlet stream with the observation of the corresponding response in the outlet stream. A flow model is then selected by matching the experimental RTD curve with that obtained from the mathematical model. The suitable model is one that matches the experimental data with the smallest error and describes the flow in a reactor with the smallest number of physical parameters.


The program provides the convenient interface and powerful tools for:

  • Initial experimental data processing

  • Creation of flow model in the reactor using the predefined flow patterns as the building blocks

  • Estimation of the flow model parameters

  • Simulation of system responses to different types of input signals

  • Creation of user-defined flow patterns


RTD is based on Experts - a proprietary software package that assists the user in the investigation of the structure of hydrodynamic flows in reactors.

  • Expert assists the user to estimate model parameters, input experimental data, and create new flow models, etc.

  • Expert provides the user with sequential directions and legends for a better understanding of the immediate procedure.

Initial Data Processing:

  • The following kinds of initial data processing are available:

  • Spike correction

  • Filtration (median, linear and parabolic filters)

  • Linear transformation

  • Normalization

  • Baseline correction (from start to end, horizontal through start or end point);

  • Tail correction (according to an exponential law)

  • Cutting a fragment of pertinent data

  • Evaluations of moments of the zero, first, second and third order

Flow Models:

The Model Expert provides the convenient graphical interface for creation and modification of the flow models on the basis of the followings flow patterns:


CSTR with bypass

CSTR with bypass and dead zone in series (n)

CSTRs in series (n)

CSTR with dead zone

Plug Flow Reactor with back mixing

CSTRs in series (n) with back mixing

CSTR with bypass and dead zone

Plug Flow Reactor

The flow model is described by its transfer function. Flow models of different complexity may be constructed by combination of several flow patterns. The transfer function of the whole model is generated automatically.


Flow Parameters Estimation:

With the Estimation Expert user can estimate the best values for hydrodynamic flow models. Estimation is done in the time domain by the least square method.


The convolution approach is used. In order to do this, the model output signal is calculated as a convolution of the model transfer function (in the time domain) and experimental input signal. It is then compared with the experimental signal.


Parameter values are changed to reduce the lack of fit and the process is repeated automatically, if necessary.

The manuals are included in the archive.

Note! The latest version of the program RTD 3.14.w7 has been modified to provide full compatibility with MS Windows 7,8

Download latest version of RTD

© 2011
CISP Ltd., (ООО "Химинформ"), Saint-Petersburg, Russian Federation