RTO Design Details Can Make a Big Difference

The goal of any add-on air emission control system is to minimize both capital and operating costs while meeting emission control requirements and maintaining consistent and reliable operation. However, the highly variable nature of many industrial emission sources and the potential for process fluctuations can make it challenging to select the best and most economical solution.

Equipment design experience combined with in-depth knowledge of all intrinsic detail features permits equipment that automatically adjusts to maintain maximum performance.  

Thermal or Catalytic oxidation is one of the most common methods to control the emission of Volatile Organic Compounds (VOC), Hazardous Air Pollutants (HAP), and hydrocarbons (HC) into the atmosphere. In the oxidation process, hydrocarbons are converted at an elevated temperature to carbon dioxide and water vapor. Several types of oxidation systems are widely used today, with Regenerative Thermal Oxidation (RTO) being the most common.

Thermal oxidizer includes the following:

1. Regenerative Thermal Oxidizer is a combustion device in which the burner(s) directly heats VOCs or HCs after the gas stream is preheated to the destruction temperature by the periodic flow reversal of the gas stream through heat storage media that alternately have been heated by the product gases during an exhaust cycle and then have given up their heat to the incoming reactant gases during an inlet cycle.
2. Regenerative Catalytic Oxidizer (RCO) is a combustion system in which the burner(s) directly heats VOCs or HCs after the gas stream is preheated to the destruction temperature by the periodic flow reversal of the gas stream through beds of ceramic heat recovery media with a coating or layer of catalyst that alternately have been heated by the product gases during an exhaust cycle and then have given up their heat to the incoming reactant gases during an inlet cycle.
3. Afterburner (Direct Thermal Oxidizer) is a direct thermal oxidizer, installed in series and downstream of process equipment, that generates VOC or HC; also, referred to as secondary combustion chamber.
4. Direct Thermal Oxidizer is a combustion system in which the burner(s) directly heats VOCs or HCs to the destruction temperature without heat recovery to the incoming gases.
5. Direct Catalytic Oxidizer is a combustion system in which the burner(s) directly heats volatile organic compounds (VOCs) or hydrocarbons (HCs) to the destruction temperature, prior to their introduction to a destruction catalyst, without heat recovery to the incoming gases, and in which the catalytic destruction temperature is lower than the non-catalytic (direct thermal) destruction temperature.
6. Fume Incinerators
7. Recuperative Thermal Oxidizer is a combustion device in which the burner(s) directly heats VOCs or HCs to the destruction temperature and in which the hot products of combustion are used to indirectly heat the incoming gas stream before it contacts the burner flame.
8. Recuperative Catalytic Oxidizer is a combustion system in which the burner(s) directly heats VOCs or HCs to the catalytic destruction temperature prior to their introduction to a destruction catalyst, after which products of combustion are used to indirectly heat the incoming gas stream before it contacts the burner flame, and in which the catalytic destruction temperature is lower than the non-catalytic (direct thermal) destruction temperature.
9. Flameless Thermal Oxidizer is a direct recuperative or regenerative combustion system in which the burner(s) preheats the heat storage media prior to the introduction of VOCs or HCs and in which, subsequently; the destruction is carried out in interstices of the heat storage media in a flameless self-sustaining manner.  

NESTEC offers several Multi-Combustion Chamber (MCC) design features that can be added to existing RTO/RCO units. The design features are standard with NESTEC’s MCC RTO/RCO system offers.

If you have a potential process change and/or new process exhaust that requires an RTO air emission control, contact NESTEC for a free process analysis.

Uniform airflow distribution is a key design feature in all RTOs. It is crucial to achieving maximum Thermal Energy Recovery (TER) and Destruction Removal Efficiency (DRE), especially with larger heat recovery chamber units.

Both mass flow and cycle time will also have a major effect on the RTO/RCO thermal efficiency and associated performance for both operating and destruction efficiency. Both are design features that NESTEC evaluates in all of their MCC RTO/RCO equipment offers to achieve the best and most economical solution for the application.

As shown in the following graphs, a 10% reduction in mass flow design will result in a nine (9°F) to four (4°F) reduction in exhaust temperature, depending on the cycle time. This can result in a $35,000 per year operating savings.

In addition, NESTEC includes an Auto-Thermal Alignment feature with their MCC RTO/RCO units to maintain the mass balance in all heat recovery chambers. This feature helps maintain maximum thermal energy recovery, providing additional operating energy savings. The typical savings is shown in the graph below which reflects actual data from a NESTEC MCC RTO/RCO operating unit, with and without Auto-Thermal Alignment.

NESTEC’s Auto-Thermal Alignment Control

Several other features are also available with NESTEC designs, many of which can be applied to existing RTO systems.

If you have a potential process change and/or new process exhaust that requires an RTO air emission control, contact NESTEC for a free process analysis.

For assistance from our extensive experience, call or e-mail NESTEC Inc. for a free evaluation of your air emission control equipment needs.  

Office: 610.323.7670

Jim Nester, CEO: jnester@nestecinc.com

Rick Reimlinger, Vice President: rick.reimlinger@nestecinc.com

Rodney L Pennington, PE, Vice President of Key Accounts: rpennington@nestecinc.com

William Holden, Aftermarket & Services Manager: jwholden@nestecinc.com