What does TTO Units primarily do in a refinery?

The correct choice identifies that TTO Units primarily oxidize remaining acid gas in the feed. This is an essential function within a refinery, as it helps to remove toxic and corrosive compounds, ensuring that the products processed are safer and adhere to environmental regulations.

In the context of refining processes, TTO, or Total Treatment Oxidation units, are utilized to treat gases that contain residual acid components, often produced from earlier stages like hydrocracking or catalytic reforming. By oxidizing these acid gases, the TTO units convert them into less harmful substances, allowing for more efficient operation of downstream processes and contributing to the overall effectiveness of sulfur recovery systems.

The other options represent different processes found in refineries but do not accurately reflect the primary function of TTO Units. For instance, converting heavy oils into gasoline is typically the role of complex conversion units like fluid catalytic crackers or hydrocrackers, while generating steam and power is often associated with boilers or steam generation systems in power plants. On the other hand, stripping impurities from liquid sulfur is a specific operation that is generally handled in sulfur recovery units rather than TTO Units. Thus, the choice clearly highlights the primary role of TTO Units in dealing with acid gas removal.