An RTO consists of two or three towers which contain specialized thermal ceramic material, connected at the top by a high-temperature combustion chamber and direct-fired burner.
The basic operation of a Regenerative Thermal Oxidizer consists of four basic steps:
- Heating: Industrial process exhausts carrying VOCs & HAPs are passed through a heated ceramic material in one tower, heating the gas up to ~1300°F.
- Combustion: A natural gas-fired burner heats the polluted air stream from 1300°F to ~1450°F, thereby oxidizing all complex carbon solvents into CO2 and water vapor.
- Recovery: The post-combustion hot gas is passed down through the second tower, which contains the same heat sink ceramic material, and recovers 95% of the heat from the burner.
- Purge: Only in the 3-tower design, the third tower purges a small amount of fresh air into the combustion chamber to prevent any exhausts from escaping.
As the first tower cools and the second tower heats up, the direction of the air through the towers reverses periodically to recover the heat from the RTO burner.
Regenerative Thermal Oxidizers (RTOs) will oxidize:
- Volatile Organic Compounds (VOCs)
- Hazardous Air Pollutants (HAPs)
- Industrial Odors
- And more organic solvents, emissions, GHGs, and pollutants.
RTOs have been installed for use in the following industries:
Industrial process exhaust gas enters and is pushed through via in-line fan to the first chamber. The valve is open to accept incoming gas for treatment. The process gas move vertically through the ceramic media in chamber 1, absorbing waste heat stored in the ceramic media, and the incoming air is heated to approximately 1300°F. The air then travels into the combustion chamber, across the top of the tower, and reaches temperatures of 1500°F.
In the middle of the RTO's combustion chamber is a burner which is supplied with fresh air (oxygen source) via combustion blower and natural gas to supplement the combustion reaction to maintain the temperature set point. Process air that reaches Chamber 3 is fully combusted, clean air. It travels down chamber 3, releasing its heat to the ceramic media blocks. The pure, clean air exist the open valve and travels to the exhaust stack where it is emitted to atmosphere. In this design, chamber 2 is in purge mode and purges to the inlet air stream, upstream of the process inlet fan. Partially combusted air is purged via chamber 2.
After a few minutes in this mode of operation, the heating sequence will be complete and the RTO inlet valves will switch, with the chamber 3 becoming the new inlet source, chamber 2 becoming the new outlet, and chamber 1 becoming the new purge chamber. This method of rotation continues every few minutes