Thermal Oxidizer Scrubbers

THERMAL OXIDIZER SCRUBBERS

High-temperature scrubber systems are used widely for processes like RTOs, direct fired thermal oxidizers, furnaces, boilers, dryers and other fired equipment. Contaminants commonly found in these systems include acid gases like SO2, HCl, Cl2, HF and/or particulates.

Inlet temperatures may vary from 300 – 2000° F and require processing through a quenching system prior to scrubbing the acid gases and other contaminants. When designing for high temperatures and a dry/wet environment, your choice of material and its level of corrosion resistance are critical considerations.

Depending on the corrosiveness of the environment and operating temperatures, you may want to choose stainless steel, alloy 20, titanium, alloy 2205, AL6XN or Hastelloy C276. In most cases the quench is oriented to provide a vertical downflow, though it may be installed horizontally for some, low-temperature applications.

High-Efficiency Packed Tower

A venturi scrubber is a method for removing particulates, from 0.2 to 2 microns in size, with more than 99 percent effectiveness. The size and particle-size distribution of the contaminants affect pressure levels.

Once combustion gases have cooled, the acid gases are scrubbed in a packed tower scrubber constructed of high-temperature, fire-resistant fiberglass. Tower internals may include polypropylene, glass-filled polypropylene, Kynar or Teflon.

Key factors for properly sizing an oxidizer off-gas scrubber include:

1. Inlet temperature
2. Water vapor content
3. Ventilation rate
4. Particulate loading
5. Removal efficiency
6. Corrosion and temperature resistance of materials

The scope of supply for a high-temperature scrubber system generally includes an alloy quenching system, venturi scrubber, packed tower, recycle pumps and piping, electrical control panel, and instrumentation. A high-efficiency packed tower completes the scrub­bing action for removal efficiencies exceeding 99.99 percent.

Pre-scrubbers for thermal oxidizers may be required, if corrosive acid gases require removal before the oxidizer to prevent condensation and corrosion of the oxidizer. In addition, removal of ammonia and amines may be desirable to reduce the amount of NOx generated in the combustion chamber.