Repairing your Recuperative Thermal Oxidizer

January 13, 2021

Repairing your recuperative thermal oxidizer is no small investment, so performing routine maintenance is an important part of keeping your pollution control system operating efficiently and effectively. Regularly scheduled inspections by both your staff and our technicians will prevent costly repairs and downtime of your system.

However, even with regular inspections, breakdowns happen. Our expert team at Kono Kogs can help troubleshoot and repair your thermal oxidizer 24/7 365 days a year. From one-time problems, to lingering problems that have baffled you or your OEM, we have seen and repaired nearly every oxidizer issue and so we have created the attached troubleshooting table that will give you a place to start.

If you are unable to solve your issue by utilizing the table, below are a few less common thermal oxidizer repairs that our company deals with on a more regular basis.

Four Things You Should Check When Repairing Your Recuperative Thermal Oxidizer

  1. Heat exchanger/economizer issues – The heart of a recuperative thermal oxidizer is the heat exchanger. Plugging or cracking are common problems that may result in increased gas use. They may also cause the oxidizer to fall short of its destruction efficiency, leading to increased downtime. Cracks in the plate or shell/tube of the heat exchanger provide a path for dirty air to short circuit to the exhaust stack thereby allowing cross-contamination of the clean and dirty air. Due to the thin walls typical in a plate heat exchanger, repair is not usually practical or possible and will require a complete replacement. 

    Shell and tube type exchangers typically are constructed of components and because of this are better candidates for repair, depending upon the crack location. Plugging may require flushing or vacuuming to return to the original flow capacity. Photos of the heat exchanger cracks and their locations, or information on the nature of the material causing the plugging, will help us determine the best solution. Give us a call we can help.
  1. Insulation hot spots – Due to the high operating temperature of these systems, hot spots are common. Paint discoloration is the first sign of a problem and metal deformity and rust spots point to a more concerning issue. Thermal oxidizers usually operate at positive pressure so hot spots can breech due to metal oxidation eventually releasing hot air outside to the atmosphere. This condition will need immediate repair to protect the system, as well as your personnel. Our team can provide guidance to identify the problem and repair the hot spot. We also dispatch our team quickly for repairs if help is needed. Give us a call and send photos for the fastest support.
  1. Exhaust stack test failure – Thermal oxidizer repairs to address a failed exhaust stack test might include inspecting the heat exchanger (see note above). Strategic placement of sensors when the testing agency is still on site can help identify the source of the problem. It may be due to a crack in the heat exchanger or poor burner set-up resulting in undesirable products of combustion.

    Also, poor flow characteristics due to heat exchanger plugging could reduce dwell time in the unit; this is one of the primary criteria that must be met to ensure the conversion of the VOC to CO² and water vapor. If you can reach us when the testing firm is still on site, we can direct the troubleshooting and assist with determining a solution. Even if the testing agency has left, our team can still review test data and the testing protocol to help narrow down the source of the poor performance.  
  1. Pneumatic actuator freeze up – This is one of the most common early winter problems. Many oxidizer systems utilize pneumatic actuators which work well if compressed air dryers are operating properly.  Any hiccup in the air dryer operation during the year can result in lingering moisture in the air lines when the cold weather arrives and the moisture freezes. 

    A common location affected are the ports in the actuator solenoid valve, effectively locking up the actuator, causing an oxidizer fault. To correct this problem is typically a tedious task involving tracing lines and devices with heat tape, using heat guns to thaw ice, and weather shields (blankets, etc.) to protect critical components. Give us a call and we can tell you what works best.

    To avoid this problem before it starts follow these steps:
    • Purge your air lines especially at the low spots and the furthest point from the air dryer.
    • Install a dessicant dryer. A dessicant style is the best air dryer technology available and we recommend -40⁰ F dew point desiccant but have also used -100⁰ F dessicant in some applications.

    Be sure to service your air dryer per the OEM guidelines. Desiccant can foul over time due to poor air filtering. Desiccant is inexpensive, so replace it as often (or more) as your OEM specifies. A maintenance agreement with a compressed air service firm keeps the dryer in focus and running properly.

Still Looking for Air Pollution Control Equipment Repair Solutions?

We could list many more repair scenarios, but if your thermal oxidizer repair needs did not make the troubleshooting table or the list above, give us a call with your challenge. We have likely seen the problem and know the solution. 

You May Need To Consider Long Term Solutions 

Together we may ultimately discover that the repairs will only buy time, with no permanent, viable, economically reasonable solution possible. If a replacement oxidizer is needed FAST—and in an emergency that is usually the case—we have the world’s largest inventory of quality used thermal oxidizer systems. Many of our oxidizers are ready to ship immediately! We can configure them to match nearly every process flow rate and solvent mix, and expedite delivery to get you operational as soon as possible. 

If we have been helping you with the repair we may already know all we need to know to propose an alternative to your current oxidizer. Though this may be a larger capital outlay than a simple repair, the new technology we offer will always result in fuel and electric savings with HIGHER RELIABILITY, allowing you to return your focus to what you do best. 

You Can Depend on Kono Kogs for Emergency Repairs 

At Kono Kogs, we want to be a resource for repairing your thermal oxidizer. Expert guidance will get it done right the first time. Getting your system back on-line is our top priority. After that we can consider any short-term solutions to keep you running into the future or possibly a long-term solution. Let us help! Whether it’s 2 a.m. Saturday morning or first thing Monday, we are available to help with your emergency thermal oxidizer repairs. Call us at 920-615-8804.

Thermal Oxidizer Repair

Troubleshooting Guide

CONDITION CHECK CORRECTIVE ACTION
Emergency Stop Fault E-Stop push buttons. Pull out and lightly turn the push button clockwise to reset.
Electrical connections. Tighten any loose connections.
Combustion Blower Fault Combustion blower starter heaters are tripped. Reset the combustion blower starter heaters.
Verify the blower motor turns freely. Remove obstructions from the blower / replace the bad motor.
Verify the current draw of the motor and compare it to the motor nameplate. If the current draw is high, check the motor and blower (bearings…).
Combustion Blower Pressure Fault Is the combustion blower running? See combustion blower fault.
Verify the pressure switch sensing lines are connected and clean. Replace broken tubing, and or clean out debris or condensation in the tubing.
Proper operation of the switch. Repair or replace the pressure switch.
Electrical connections. Tighten any loose connections.
Fan Run Fault Electrical connections. Tighten any loose connections.
Proper signal from the VFD. Repair or replace any malfunctioning cards in the PLC or VFD.
VFD Fault (Exhaust Fan Drive Fault, Exhaust Fan Out of Range) Electrical connections. Tighten any loose connections.
Proper signal from the VFD. Repair or replace any malfunctioning card in the PLC or VFD.
Fan Pressure Fault Is the system fan running? See VFD fault.
Verify the pressure switch sensing lines are connected and clean. Replace broken tubing, and or clean out debris or condensation in the tubing.
Proper operation of the switch. Repair or replace the pressure switch.
Electrical connections. Tighten any loose connections.
High Negative Pressure Fault (Fan) Verify the pressure switch sensing lines are connected and clean. Replace broken tubing, and or clean out debris or condensation in the tubing.
Fan operating properly? Verify proper control with associated signals.
Proper operation of the switch. Repair or replace the pressure switch.
Electrical connections. Tighten any loose connections.
Isolation Damper/T-Damper (Vent Collect Damper) Close Fault Electrical connections on the solenoid valve or actuator. Tighten any loose connections.
Airline leaks (if applicable). Tighten or repair any broken or leaking airline.
(Electric actuator) Verify actuator operation. Repair or replace the actuator.
(Pneumatic actuator) Verify cylinder operation. Repair or replace the cylinder.
Limit switch location. Adjust internal limit switch.
Obstruction between the blade and seat. Remove any obstructions between the blade and seat.
Isolation Damper/ T-Damper (Vent Collect Damper) Open Fault Electrical connections on the solenoid valve or actuator. Tighten any loose connections.
Airline leaks (if applicable). Tighten or repair any broken or leaking airline.
(Electric actuator) Verify actuator operation. Repair or replace the actuator.
(Pneumatic actuator) Verify cylinder operation. Repair or replace the cylinder.
Limit switch location. Adjust internal limit switch.
Obstruction between the blade and seat. Remove any obstructions between the blade and seat.
Inlet (TE0721) High Temperature Fault Electrical connections. Tighten any loose connections.
Fire in ductwork. Shut down the system and put out the fire.
Combustion (TE1028) High Temperature Fault Electrical connections. Tighten any loose connections.
Solvent loading too high. Reduce VOC concentration entering oxidizer.
Combustion chamber temperature >1900°F. Allow the system to cool down and go through a normal startup.
Exhaust (TE0740) High Temperature Fault Electrical connections. Tighten any loose connections.
Poppet valve has not switched. See poppet valve fault.
Solvent loading too high. Reduce VOC concentration entering oxidizer.
The exhaust duct to the stack has exceeded 400°F. Allow the system to cool down and go through a normal startup.
Gas Pressure Fault Electrical connections. Tighten any loose connections.
Incoming gas pressure too high or low. Set the gas pressure to the original setting.
Regulator setting. Repair or replace the regulator.
Ignition/Burner Failure Fault Flame safeguard not reset. Reset the flame safeguard unit.
Pilot solenoid valve failed. Repair or replace the pilot solenoid valve.
Pilot regulator failed. Repair or replace the pilot regulator.
Pilot regulator out of calibration. Reset the pilot regulator back to the original start-up settings found on the start-up sheets.
Proper incoming gas pressure. Verify the incoming gas pressure is the same as what was indicated on the initial start-up sheets.
Electrical connections. Tighten any loose connections.
Proper operation of the flame safeguard. Repair or replace the flame safeguard as needed.
Proper operation of the spark ignitor and spark generator. Reset the dimension of the spark ignitor.
Repair or replace the spark generator.
Proper operation of the UV scanner. Repair or replace the UV scanner.
Flame Out Fault Electrical connections. Tighten any loose connections.
Proper operation of the flame safeguard. Repair or replace the flame safeguard as needed.
Proper operation of the spark ignitor and spark generator. Reset the dimension of the spark ignitor.
Repair or replace the spark generator.
Proper operation of the UV scanner. Repair or replace the UV scanner.
Process Line Fault Proper operation of dampers. Check dampers, limits, prox. switches.
Proper operation of exhaust fans. Reset breakers repair belts electrical connections.
High Negative Pressure Fault (Header)
Verify the pressure switch sensing lines are connected and clean. Replace broken tubing, and or clean out debris or condensation in the tubing.
Proper operation of the switch. Repair or replace the pressure switch.
Fan operating properly? Verify proper control with associated signals.
Electrical connections. Tighten any loose connections.
Low Negative Pressure Fault (Header) Verify the pressure switch sensing lines are connected and clean Replace broken tubing, and or clean out debris or condensation in the tubing.
Proper operation of the switch. Repair or replace the pressure switch.
Fan operating properly? Verify proper control with associated signals.
Electrical connections. Tighten any loose connections.
Fresh Air Damper Open Fault (Stuck Open, Not Open) Electrical connections on the solenoid valve or actuator. Tighten any loose connections.
Airline leaks (if applicable). Tighten or repair any broken or leaking airline.
(Electric actuator) Verify actuator operation. Repair or replace the actuator.
(Pneumatic actuator) Verify cylinder operation. Repair or replace the cylinder.
Limit switch location. Adjust internal limit switch.
Obstruction between the blade and seat. Remove the obstruction between the blade and seat.
Fresh Air Damper Closed Fault (Stuck Closed, Not Closed) Electrical connections on the solenoid valve or actuator. Tighten any loose connections.
Airline leaks (if applicable). Tighten or repair any broken or leaking airline.
(Electric actuator) Verify actuator operation. Repair or replace the actuator.
(Pneumatic actuator) Verify cylinder operation. Repair or replace the cylinder.
Limit switch location. Adjust internal limit switch.
Obstruction between the blade and seat. Remove the obstruction between the blade and seat.
Low Fire Fault Actuator motor. Verify the actuator motor is responding to the control signals, if not have the motor repaired or replaced.
Electrical connections. Tighten any loose connections.
Limit switch location. Adjust internal limit switch
Obstruction between the blade and seat. Remove the obstruction between the blade and seat.
High Fire Fault Actuator motor. Verify the actuator motor is responding to the control signals, if not have the motor repaired or replaced.
Electrical connections. Tighten any loose connections
Limit switch location. Adjust internal limit switch.
Obstruction between the blade and seat. Remove the obstruction between the blade and seat.
PLC Battery Fault Electrical connections. Attach the battery connections to the battery.
Battery is dead or missing. Replace the battery.