Low Temperature Oxidation (LoTOx™) – AECOM Process Technologies

The LoTOx^TM process uses ozone to oxidize insoluble NO_x to higher oxides that are then captured in a wet or semi-dry FGD process. The low temperature process allows stable and constant NO_x control regardless of load or concentration.

AECOM Process Technologies is the licensee of Linde LLC's patented LoTOx process for power industry applications. LoTOx involves the injection of ozone into low-temperature flue gas (optimally ≤300°F) to oxidize NO and NO₂ to N₂O₅, which is highly soluble. The flue gas moisture and the liquid in the downstream wet or semi-dry FGD process easily and quickly converts N₂O₅ to nitric acid (HNO₃). The conversion of the N₂O₅ into the aqueous phase is rapid and irreversible, allowing for near-complete removal of NO_x.

In LoTOx applications, the amount of ozone production capacity is determined by the amount of NO_x present in the flue gas and the targeted removal efficiency. During operation, the ozone is generated “on demand” based on the incoming NO_x level, so that no onsite ozone storage is required – ozone is produced by passing oxygen through a conventional ozone generator.

There are different ozone delivery models available, depending on the client’s preference. The utility may elect to procure the equipment necessary for onsite oxygen and ozone generation. Alternatively, Linde provides an “over-the-fence” ozone supply model, in which they own and operate a plant that purchases power from the utility and supplies ozone for the LoTOx process on a contract basis. These contracts can be tailored to a particular need and significantly reduce the capital investment.

When used in combination with combustion tuning or SNCR, LoTOx provides a cost-effective alternative for achieving emissions comparable to SCR. This approach ha a number of advantages over SCR, including:

Higher potential NO_x removal (>90%)
Lower capital cost
No catalyst poisoning
No catalyst deactivation or periodic outages for replacment
No minimum operating temperature restriction
No air heater fouling
Minimal increase in pressure drop
Shorter outage required for implementation

The LoTOxTM process uses ozone to oxidize insoluble NOx to higher oxides that are then captured in a wet or semi-dry FGD process. The low temperature process allows stable and constant NOx control regardless of load or concentration.

The LoTOx^TM process uses ozone to oxidize insoluble NO_x to higher oxides that are then captured in a wet or semi-dry FGD process. The low temperature process allows stable and constant NO_x control regardless of load or concentration.