Frequently Asked Questions

We love to share our knowledge of thermal oxidizers and regenerative thermal oxidizers to help business owners and future owners navigate the sometimes confusing world of oxidizers. Below are some of the questions Kono Kogs deals with on a daily basis. If you don’t see what you're looking for, don’t hesitate to contact us and we will be happy to answer any of your oxidizer questions.

Are process emissions visible to the naked eye?
  • A puff capture feature can help eliminate visible emissions
Are the PLC controls configured with remote access for troubleshooting?
  • Remote access can ease troubleshooting and reduce the frequency of service visits
At what temperature does a regenerative thermal oxidizer operate?

RTOs typically operate at 1500o – 1600o Fahrenheit.

Can I convert an existing RTO to an RCO?

Yes. It is normally a simple conversion

Can we install catalyst in our RTO?

In most cases, yes. But proper evaluation is recommended to establish that no potential catalyst poisons or masking agents are present in your airstream.

Do the local government codes require low NOX operation?
  • Low NOX burners can be retrofit for these applications
  • Case study: RTO solution for industrial NOx emissions
  • Does the RTO main fan use a variable frequency drive (VFD)?
    • VFDs are important for efficient operation, volume turn-down and idle operation
    Does the RTO need to handle potentially corrosive emissions/halogens?
    • Special materials of construction may be required
    How do thermal and catalytic oxidizers differ?

    Catalyst in an RCO allows chemical reactions to occur at lower temperatures (850F) than an RTO’s typical 1600F operating temperature.

    How efficient is a regenerative oxidizer?

    Regenerative thermal oxidizers have a heat recovery (efficiency) of 95% typically. This technology has the lowest operating cost of all thermal oxidizer systems – not to mention the longest service life and highest reliability. It’s even possible for an RTO to operate with no auxiliary fuel use whatsoever if process VOC concentration levels are >3-4% lower flammability limit (LFL).

    How often should RCO catalysts be tested?

    Annually (and is usually determined by your operating permit)

    How to choose between RCOs and recuperative units?

    RCOs offer greatest fuel economy by far, but recuperative units may be best for high VOC concentration airstreams (or an RTO can be considered).

    Is a catalytic oxidizer the most cost-effective oxidizer solution for my airstream?

    It depends on numerous factors. See Selecting an Oxidizer for guidance or call us for guidance

    Is the RTO optimized for my exhaust airstream?
  • RTOs typically treat airstreams with a 0-10% Lower Explosive Limit (LEL)
  • RTO systems can handle 25% LFL airstreams, though hot gas bypass systems and other features may be needed
  • Is the RTO skid mounted with little welding required in the field?
    • Ease of installation results in lower turnkey cost
    Is the ceramic media in the RTO optimized for my exhaust airstream to achieve?
    • Maximum thermal efficiency
    • Lowest pressure drop
    • Ability to handle organic/inorganic particulates
    Is the process sensitive to pressure pulses that can occur with poppet valve technology?
    • Rotary valve technology may be a better option
    Is there a risk of ceramic media plugging due to condensing VOCs?
    • A bake-out feature can address organic compound build-up
    Is there a used RTO system available with the features needed?
    Our heat exchanger media is plugging up due to particulate. How do we alleviate this problem and deal with it?

    Provide us your particulate description, or send us a sample. We can recommend a cleaning cycle and procedure, new more plug-resistant media, upstream filtering, and/or regular media change outs. A site visit will be needed to fully evaluate the issue.

    Our oxidizer didn’t pass the emission test and the state is going to fine us and shut us down. We need some help as soon as possible. Can Kono Kogs help?

    Yes we can come out and help to determine what the problem is. Whether it be switching valves leaking; a leaking heat exchanger; poor air flow distribution; or poor catalyst performance. We can do a thorough evaluation and provide a turnkey solution in a short period of time and help to keep you in operation. If your system is a regenerative thermal oxidizer (RTO) see this blog post about stack test failures for more details on troubleshooting your RTO and test method.

    Our oxidizer is faulting out and it just isn’t reliable, how can we fix this issue?

    We can come in and evaluate the controls and make recommendations for changes to alleviate this situation. Your oxidizer shouldn’t be dictating your production. Our service technicians are working throughout the USA on a regular basis. We may have someone near you right now. Check out our service page for more details or contact us.

    Our oxidizer is in poor shape, can it be repaired?

    Our experience is that regenerative thermal oxidizer (RTOs) systems less than 20 years old are good candidates for rebuild/repair/upgrade rather than for RTO replacement. Replacement costs including removal of existing, capital cost of a replacement system and shipping, ductwork, mechanical assembly, etc. add up quickly making it more cost effective to repair the system, upgrade the PLC, and/or add energy saving updates. Thermal recuperative oxidizer systems on the other hand usually are not cost effective to repair for long term use, but simple repairs may help limp these systems along until a replacement can be budgeted for. Catalytic recuperative oxidizers can be repaired, but the cost of catalyst replacement may justify replacement of the system if the catalyst has a history of contaminating quickly. Contact us and we can visit to make an evaluation. We want long term relationships with our customers so we provide our best evaluation of the total cost of ownership of each option so you can make an objective decision.

    We are adding a new process line and we are looking for someone to help us with a turnkey approach or maybe just size ductwork to the oxidizer. Can you help?

    Yes we can help with either one of these scenarios. We have extensive fabrication capability and can provide some or all of the ductwork needed. Our crews can install the oxidizer and cutwork as turnkey or any portion of the project you would like to hand off to an experienced professional. Check out a few of our case studies for examples of our capabilities.

    We are buying a new piece of process equipment. Do we have capacity in our existing oxidizer or can we make changes to achieve the needed capacity?

    We can evaluate the existing oxidizer capacity and the requirements of the new process and determine the best approach to upgrade the oxidizer. This could include new heat exchanger media, a larger fan or possibly both. We would also evaluate things like the burner system and combustion chamber size to verify it can provide the required destruction levels. Some applications would be a good match for a VOC concentrator that can significantly concentrate (>10:1) airstreams currently exhausting to the oxidizer.

    We are considering a refurbished regenerative thermal oxidizer (RTO) to reduce the capital investment for an planned expansion. What warranty is available for the equipment and individual parts, and also what system performance is available?

    This is a common concern.  Will the buyer be left with only promises, or will Kono Kogs provide robust support after the purchase and commissioning of the oxidizer? We have never failed to meet our warranty in either parts or oxidizer performance. We have references that will attest to this in every business size- from start-up bootstrapping companies, to growing small and mid-size companies, to Fortune 500 companies. Our experienced staff can handle any technical or maintenance issue, both on-site, and via remote monitoring to ensure a successful project, now and into the future with our long-life refurbished oxidizers.

    Our warranty rivals that of new equipment OEMs and we can even extend the period, if desired. How do we do that?  We offer only the best built systems from the best names in the industry. We also perform extensive sub-system and parts checkouts and replace faulty or questionable parts, many times with upgraded parts. Our goal is a flawless project- achieved with proper planning and with our staff’s extensive oxidizer experience. We are honored that our customers are our best advocates. They affirm that we deliver what we promise- which has been true since day one of Kono Kogs.

    We are considering a refurbished regenerative thermal oxidizer (RTO) to reduce the capital investment for an planned expansion. What warranty is available for the equipment and individual parts, and also what system performance is available?

    This is a common concern.  Will the buyer be left with only promises, or will Kono Kogs provide robust support after the purchase and commissioning of the oxidizer? We have never failed to meet our warranty in either parts or oxidizer performance. We have references that will attest to this in every business size- from start-up companies, to growing small, and mid-size companies, to Fortune 500 companies. Our experienced staff can handle any technical or maintenance issue, both on-site, and via remote monitoring to ensure a successful project, now and into the future with our long-life refurbished oxidizers.

    Our warranty rivals that of new equipment OEMs and we can even extend the period, if desired. How do we do that?  We offer only the best built systems from the best names in the industry. We also perform extensive sub-system and parts checkouts and replace faulty or questionable parts, many times with upgraded parts. Our goal is a flawless project- achieved with proper planning and with our staff’s extensive oxidizer experience. We are honored that our customers are our best advocates. They affirm that we deliver what we promise- which has been true since day one of Kono Kogs.

    We changed our process to be more water based and less solvent based and now my oxidizer is burning a lot more gas. Is there anything we can do to reduce the amount of gas used?

    Yes, we can evaluate the heat exchanger whether it be metal (recuperative) or ceramic media (regenerative) and determine whether it can be upgraded to a more efficient type. Or maybe catalyst could be added in this case. In some cases it may be better to replace the current oxidizer with something more efficient. In that case we can look at our inventory and determine whether we have something that will provide better gas efficiency. If not, we can provide a custom system designed specifically for your needs.

    We have hot spots on the outside of our RTO. Can you fix this?

    Yes we have a team of experienced fabricators and insulators we can bring in to repair your oxidizer. Damaged metal may have to be replaced to ensure a secure surface is available to weld the insulation modules to.

    We just did our state emissions test and the capture efficiency was very low. What can we do to get it up to where we need it to be?

    We can come in and evaluate the current system by taking flows and readings at certain points of the system. Then we can determine whether the current system is optimized. If it isn’t we can recommend how to do that. If area capture hoods or enclosures need to be added we can recommend that as an option as well. We can also provide these things on a new system.

    What are common applications for RCOs?

    Chemical, pharmaceutical, OSB (oriented strand board) press, particle board dryer, MDF (medium density fiberboard) dryer, plywood, paint spray booths; and any application under 2% LFL is a good candidate

    What are the operating considerations for catalytic oxidizers?

    Particulate free or well filtered airstreams with no catalyst-masking chemicals

    What are the types of catalytic oxidizers?

    Regenerative and Recuperative

    What are the unique features of a KonoKogs RCO system?

    Extensive catalyst application experience allows our engineers to select the right catalyst type, and pair it with an optimized ceramic media mix for long life, and for low fuel and electric use.

    What does regenerative mean?

    The term “regenerative” in regenerative thermal oxidizer is drawn from the type of ceramic media heat exchanger used in these systems. It is unique in that it captures heat from the exhausting, clean airstream during one cycle and releases the heat to the incoming, dirty airstream in the next cycle. The heat is captured (and released) from beds of ceramic media. The RTO incorporates switching valves to cycle the direction of the airflow through the RTO heat exchanger beds to enable regenerative heat recovery.

    What industrial applications are best for regenerative thermal oxidizers?

    Clean process airstreams with high air flow and low VOC content (<10% LFL) are ideal applications. Higher VOC concentrations can be tolerated, as well as organic/inorganic particulates with proper planning and design, and possibly filters. See our case studies for a sample of possible applications.

    What is the dwell time in a regenerative thermal oxidizer?

    RTOs typically have a 0.5 second to 1.0 second dwell time for most applications.

    What is the dwell time of a thermal oxidizer?

    Typically 0.5 seconds to greater than 1.0 seconds depending upon the VOC characteristics and the local codes. Given a constant rate of flow, the larger the combustion chamber, the longer the dwell time. More time typically equates to greater VOC destruction efficiency. In most applications the dwell time requirement is between .5 – 1 second.

    What is the efficiency of RCOs?

    Up to 99% VOC destruction efficiency; and up to 97+% thermal efficiency.

    What is the operating temperature of a thermal oxidizer?

    Typically 1400 F minimum up to 1600+F depending upon the VOC characteristics. Thermocouples inside the chamber monitor temperature and adjust gas burner firing as needed. Adequate temperature is essential to ensure VOC destruction efficiency. In most cases a data log of chamber temperature is required for air quality compliance.

    What is the role of heat recovery chambers in thermal oxidizers?

    An RCO is essentially an RTO with a catalyst layer added. (See What is an RTO?).

    What is the role of turbulence in a thermal oxidizer?

    VOCs must combine with oxygen and heat to trigger the chemical reaction that breaks them down into CO2 and H2O. There are many successful thermal oxidizer designs that ensure sufficient turbulence, such as introducing the process air at an angle to induce spin or creating internal choke points. The better the mixing and heat distribution, the higher the VOC destruction.

    Which Industries are most likely to need an RCO?

    Chemical, pharmaceutical, and wood products.

    Would a fuel gas injection system be a wise choice for this application?

    Fuel injection can provide significant fuel savings

    Would an induced draft fan be a better choice than a forced draft fan?

    Solvents with a high boiling point can build up on a forced draft fan wheel

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