Air-to-Air Heat Exchanger Delivers Significant Savings to Food Processing Facility

A new Regenerative Thermal Oxidizer (RTO) was installed by a food processing facility to control odor from a roasting operation. The oxidizer delivered thermal rates of 95% efficiency and contained supplemental fuel injection (SFI) which is utilized during low VOC loading conditions to reduce fuel cost. The customer was exploring other options to further reduce its operating costs. Figure 1 shows the reported values with RTO.

Figure 1. Reported values with RTO

Waste Heat Recovery

One of the most effective ways of reducing operating costs is to recover waste heat. Exhaust heat from exhaust stacks and energy consuming processes is returned via a metal heat exchanger as preheated combustion air, process air, or plant comfort heat.

In any energy recovery product, the key design factors are the temperature of the air stream, airflow rate, the desired heat to be transferred to the heat exchanger, and the permissible pressure drop of the application.

Anguil examined the application data with a Heat Exchanger Performance Modeling Program which models flow rates and temperatures from ambient to 1,800°F. The program conducts a boundary layer analysis for the particular application and alters the plate thickness and spacing of the heat exchanger to improve performance.

Plate Type Heat Exchanger

Figure 2. Projected values with energy recovery system

For this application, a secondary plate type heat exchanger was selected due to its versatility, robust, and cleanable plates. The plate style heat exchanger is compact, has a low pressure drop and low capital cost, suitable for this application.

The RTO exhaust heat was utilized to preheat 7,000 SCFM of air to about 190°F. This hot air combines with external air to deliver 30,000 SCFM of heated air to the makeup air unit. About 1.5 MMBTU/hr of heat is transferred by the secondary heat exchanger from the RTO exhaust to the air going back to the makeup air unit. Expected annual savings for the project was pegged at about $45,000.00. Figure 2 shows the projected values with energy recovery system.


The principle design factors in any energy recovery product are temperature of the air stream, airflow rate, permissible pressure drop of the application, and the required heat to be transferred to the heat exchanger. Air-to-air heat exchanger offered significant savings to the food processing facility. The plate style heat exchanger is compact, has low pressure drop, and entails low capital cost, thus making it a low-cost option for odor control.

About Anguil Environmental Systems

Anguil Environmental Systems is a global provider of industrial air pollution control and energy recovery systems. The thermal and catalytic oxidizers supplied by Anguil are used to destroy Volatile Organic Compounds (VOCs) and Hazardous Air Pollutants (HAPs) that are by-products of various manufacturing processes. When released into the atmosphere these carcinogens are known to cause respiratory ailments, heart conditions, birth defects, nervous system damage and cancer in humans and animals.

In addition to their harmful effects on plants and trees, when left untreated VOCs and HAPs degrade in the presence of sunlight and contribute to low-lying ozone or smog. Anguil differentiates itself from the competition by offering all of the different vapor combustion technologies used for the destruction of these pollutants. This ensures an unbiased equipment selection for each application based on the destruction requirements, efficiency needs and process parameters. We not only design, manufacturer, service and install Regenerative Thermal Oxidizers (RTOs) but also direct-fired, catalytic and thermal recuperative systems. In addition, Anguil offers a wide variety of heat recovery and energy conservation technologies. Our energy recovery systems help manufacturers achieve greater energy efficiency, lower operating costs and reduce greenhouse gas emissions through the utilization of waste heat. The recovered energy is often used in process and comfort heating applications or converted into electricity.

This information has been sourced, reviewed and adapted from materials provided by Anguil Environmental Systems.

For more information on this source, please visit Anguil Environmental Systems.

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