In alkylation processes, the hydrofluoric or sulfuric acid catalyst is removed from the alkylate stream in an acid settler where it is collected in the acid boot.



In alkylation processes, the hydrofluoric or sulfuric acid catalyst is removed from the alkylate stream in an acid settler where it is collected in the acid boot (see Figure 1). Veolia Water Technologies has repurposed its Tilted Plate Separator Systems (TiPSS) technology to significantly improve the performance of standard acid settlers already installed in the market according UOP and Phillips design.



Internals for the acid settler can be applied to optimize the segregation of acid droplets from a continuous flow of alkylate. These internals are part of the TiPSS design and comprise a lamella plate pack that is used to maximize the removal of acid droplets from the light oil phase down to 25 microns. Upon request, optional computational fluid dynamics can be used to verify the design needed to meet specific performance requirements.


Veolia has the knowhow for design, engineering and manufacturing of the special material plate packs that enhance the separation process. The plate pack can be assembled through a manhole in the settler using an advanced clamping system that ensures installation with no welding on the vessel required.



Installation of the pack plates is typically scheduled during turnarounds when the settler is out of service. For urgent turnaround applications, plate packs can be supplied Ex Works within 2 to 8 weeks. Plate packs can be supplied for both horizontal and vertical vessels.The internals can be constructed of carbon steel or specialty alloys, if requested, for longer service life.



TiPPS is a proven technology originally designed for removal of suspended solids from stormwater in refineries. This new application of proven technology is helping to improve the performance of acid settlers in alkylation units around the globe. One example is the upgrade of the Saudi Arabia Yanbu acid settler Phillips66 recontacter drum as shown in the photograph. In this case, the horizontal vessel had an internal diameter of 3,000 mm. The plate pack used to remove the HF acid is 6 meters long, constructed of low alloy carbon steel.Weight of the internals shown is 7 tons. Design requirements included temperature of 50°C, pressure of 25 barg and performance of ds >25μm.


Turnaround (TAR)

A turnaround (commonly abbreviated TAR) is a scheduled event wherein an entire process unit of an industrial plant (refinery, petrochemical plant, power plant, pulp and paper mill, etc.) is taken offstream for an extended period for revamp and/or renewal. Turnaround is a blanket term that encompasses more specific terms such as I&Ts (inspection & testing), debottlenecking projects, revamps and catalyst regeneration projects. Turnaround can also be used as a synonym of shutdowns and outages.


Turnarounds are expensive - both in terms of lost production while the process unit is offline and in terms of direct costs for the labour, tools, heavy equipment and materials used to execute the project. They are the most significant portion of a plant's yearly maintenance budget and can affect the company's bottom line if mismanaged. Turnarounds have unique project management characteristics which make them volatile and challenging.