Dryer Software

INTRODUCTION

PEDCO's Adsorptive Gas-Dryer Simulation software predicts the performance of adsorptive desiccant dryers. The program user specifies the dryer type, dryer geometry, desiccant type, operating conditions, and ambient conditions and the program simulates the dryer performance by solving the conservation equations of mass, energy, and momentum for the specified system. Output includes dew point, desiccant loading, temperature, etc. as a function of time and bed position.

PEDCO's Adsorptive Gas-Dryer Simulation is intended for;

manufacturers of desiccant and desiccant dryers,
engineering companies specifying and evaluating desiccant dryers,
compressed air system auditors optimizing performance of desiccant dryers,
end users comparing, evaluating, and selecting desiccant dryers,
system engineers using desiccant dryers as an integral part of the system,
service personnel troubleshooting desiccant dryer performance, etc.

The Instruction Manual is available in pdf format. An evaluation copy of the program will be provided upon request.

DRYER TYPES

The software can be used to simulate performance of Thermal Swing Dryers (Atmospheric Pressure Blower Purge, Closed Loop Blower Purge, Heated Purge, and Heat of Compression), Pressure Swing Dryers (Conventional Pressure Swing, Vacuum Assisted Pressure Swing, and Single Tower Pressure Swing) and Once Through Dryers. The Dryer Engineer can select from a total of 146 different dryer configuration.

GASES

Drying of Air, Argon, Carbon Dioxide, Ethane, Helium, Hydrogen, Methane, Nitrogen, Oxygen, and any mixture of up to four of these gases can be simulated. Based on the dryer type, the gas being dried and gas used to regenerate the desiccant can be different.

The graph to the left shows comparative dew point breakthrough curves for the nine different gases.

DESICCANTS

The program contains isotherms and property data for all the typical desiccants; activated alumina, 4A and 13X molecular sieves, granular silica gel, and spherical silica gel. Any desiccant diameter can be specified. Aging factors can be specified to study the impact of desiccant aging and contamination on dryer performance.

Up to four layers of desiccant can be specified. The desiccant can be layered based on desiccant type, desiccant diameter, or aging factor for example to simulate a layer of contaminated desiccant near the inlet.

Within each layer a mixture of up to four desiccants can be specified. As with layering, the mixture can be of different desiccant types or the same desiccant type with different properties, e.g. bead diameter.

APPLICATIONS

Uses for the program are unlimited for the Desiccant Dryer Engineer. Just a few examples of its use include:

Predict performance of an existing dryer operating at off-design conditions,
Assist in development of an energy management system,
Enable a better understanding of the inner workings of a desiccant dryer to optimize performance and design,
Evaluate reactivation scheme options to intelligently conduct a cost-benefit analysis,
Conduct a sensitivity analysis to determine purge air requirements for a pressure swing dryer as a function of required dew point, inlet temperature, inlet pressure, inlet relative humidity, desiccant type, desiccant diameter, etc.,
Study the effects of desiccant particle size distribution on dryer performance,
Study the effect of desiccant layering on drying and reactivation performance,
Develop new energy efficient dryers,
Create support documents for proposal presentation,
Etc.

Insight into the inner workings of a desiccant dryer NOT ATTAINABLE BY ANY OTHER METHOD is possible by studying the output from this simulation.

DATA INPUT

Input data describing the dryer and operating conditions is entered by the Engineer into intuitively designed input forms. Alternatively, a data file from a previous simulation run can be specified and data from that run will be read into the input forms. Any desired changes from the previous run can then be made.

Desiccant properties, transport coefficients, numerical system specifications, output control parameters, etc can be provided by the Engineer - or the programs defaults can be selected.

Four levels of input data checking are included to assure a valid data set is provided. If a data value is deemed unusual, a warning is issued that the operator can ignore. If an error is detected, a change must be made before continuing.

Individual values are checked as entered and low and high warnings and errors are issued as appropriate.
Upon exiting an input data form, all data fields are checked to assure a complete set of data is provided.
Prior to running the simulation, all data forms are checked to assure they have been completed. If not, the program prompts the operator to enter data or use the programs default values.
When the program begins, relationships between data are checked. For example, the program checks to see if desiccant fluidization is a potential problem.

SOLUTION ALGORITHM

This program solves the system of non-linear partial-differential conservation equations of mass, momentum, and energy describing the physics of adsorption. Constitutive relations such as the ideal gas law, desiccant isotherms, correlations for molecular diffusivity in a desiccant particle, etc are utilized. The system of differential equations is solved using a finite-difference technique. The system of non-linear algebraic equations created by discretizing the differential equations is solved using the Newton-Raphson method.

OUTPUT

Simulated data is output to an Excel spreadsheet. Output data includes:

Dryer outlet Dew Point and Temperature as a function of Time,
Desiccant Bed Temperature, Loading, and Dew Point distributions as a function of Time (output in tabular and plotted formats),
Water Loading Distribution in a Desiccant Particle as a function of Bed Position and Time,
Desiccant and Gas Properties, and
Transport Coefficients - Gas-to-Vessel Heat Transfer Coefficient, Gas-to-Desiccant Mass Transfer Coefficient, Desiccant Bead Effective Diffusivity, etc.

Links to sample output files are listed below. These files are Microsoft Excel files and Excel 97 or later must be installed on your computer to view them.

The capabilities of Excel can be utilized to manipulate and plot data in a format most suitable for the objectives of the immediate project.

PRICING

Perpetual License

Complete Program - $10,000 U.S.
Pressure Swing (Heatless) Only - $5,000 U.S.
Thermal Swing (Heated) Only - $5,000 U.S.

Training

$1,200 U.S. / day plus travel expenses