Regenerative Thermal Oxidizer (RTO) Design Software

Analysis software to determine thermal efficiency, burner firing rate, and pressure drop for new or existing RTOs to evaluate the impacts of airflow, bed depth, cycle time, bypassing, and media characteristics.

The Klobucar regenerative thermal oxidizer (RTO) design software is available for predicting thermal and pressure drop performance of regenerative heat transfer systems. The RTO software works by breaking the heat transfer regenerators or beds down into discrete elements and then solving the heat transfer equations between the solid regenerator and flowing gas for discrete time intervals. The model repeats the calculations for the complete regeneration cycle including the regenerators switching role from heat absorption to heat release. The model repeats the regeneration cycle until the results converge to a steady state value. The model then calculates thermal and pressure drop results.


The results include thermal efficiency which is calculated based on the output temperature profiles. Burner firing rate is also calculated based on the thermal input needs to maintain the combustion chamber temperature. The software provides temperature profiles at the RTO combustion chamber and RTO outlet for each time increment of the full regeneration cycle. The software also provides temperature profiles through the height of the bed. The temperature profiles in the bed include minimum, maximum, and average values at each discrete point in the bed height. The model calculates the pressure drop based on hydraulic resistance calculated at the bed temperatures predicted by the thermal modeling.

The heat release from exothermic combustion of incoming pollutants or gas injection are included in this calculation. The effects of burner stoichiometry are included. The temperature output profiles can be used to predict thermal cleaning or bake-out of the cold face of the regenerator beds. Variations in burner control algorithm such as constant temperature or constant burner heat input can be accommodated.

The model uses a one dimensional discretization of the regenerator beds with each bed divided into elements in the height direction. The flow is assumed to be equally distributed across the face area of the regenerator and that wall heat losses are negligible. Flow maldistribution can be accounted for using empirical corrections. The model performs the complete cyclic calculation for each specific design case so it can accurately calculate the effects of unit design, unit operation, and packing parameters.

Typical Results 



Unit Design Parameters

Regenerator Face Area

Regenerator Height

Air to Fuel Ratio


Unit Operating Parameters

Inlet Flow

Inlet Temperature

Cycle Time

Chamber Setpoint

Fuel Heating Value

Pollutant Oxidation Heat Content

Bypass Percentage (Hot or Cold Side)


Packing Properties

Passage Width

Wall Thickness

Layer Height

Material Specific Gravity

Heat Capacity

Surface Area

Open Area

Bulk Density



burner heat input – average and peak

combustion chamber temperature

outlet temperature

burner temperature rise

thermal efficiency

bed average temperatures

bed Reynolds number

pressure drop