PTQ Q1 2025 Issue

a good system for distribution of liquids in the whole cross-section of the device, avoiding channelling problems that might be associated with random packings or structured packings without intermediate re-distribution. Optimal treating systems are custom- designed to meet refiner requirements, then engineered and fabricated to the customer’s specifications, whether the need is for a completely new facility or a minimal retrofit to upgrade existing equipment.

mercaptan as sulphur. The feed contained a C1/C2 /C 3 mix of mercaptans, and the treated product stream had to contain less than 100 wtppm total sulphur. The treated NGL streams had to each contain less than 16 wtppm mixed mercaptans and pass a maximum 1 rating on the copper strip test. Shortly after the new unit start-up, Merichem was asked to revise the initial process design information based on new design basis information the operator dis- covered. Working collaboratively with the operator through the COVID-19 pandemic period, several relatively minor changes were identified in the unit infrastructure, resulting in the implementation of some minor equipment upgrades. Following these changes, a minimum 33% increase in design nameplate capac- ity was successfully demonstrated. The next challenge was to improve product purity coming from the Merichem process, given the changes in feed characteristics. Working in the same manner, changes to improve recycled caustic quality were identified, thus increasing the efficiency of the mass transfer in the Thiolex process, which produced a cleaner product at the

Hydrocarbon

Fresh caustic

Fibre

This technology offers a unique design with a significantly larger interfacial sur - face area, using minimum mixing energy. It allows for enhanced microscopic dif- fusion and a continuous renewal of the aqueous phase. Mass transfer efficiency is improved by an order of magnitude, which reduces operating costs. The liq- uid surface area is significantly increased, which improves the efficiency of the pro - cess and allows for higher flow rates with little to no emulsification, carryover, or high-pressure drop during phase transfer. Pressure drop through this mass transfer device is low and on par with pressure drop experienced in traditional random and structured packing implementations. This mass transfer device has low fouling characteristics in most hydrocarbon/caustic treating systems and can nor- mally be restored to clean condition by simple water wash- ing. There are no moving parts in the Merichem device, and in most cases the fibre-packed bundle can be easily removed from the service vessel for cleaning or replace- ment. The robust design of the equipment allows this mass transfer device to extend its life through several turna - rounds with proper care and regular cleaning. In the proprietary FFC Plus Contactors, Merichem com- bines the Fiber Film Contactor with a typical coalescing element directly to further enhance the separation of the hydrocarbon and liquid treating layers. This results in very low to no carryover of the aqueous phase in the hydrocar- bon product. This improved mass transfer and separation can lead to a significant capacity increase and improvement in impurity removal. Results from case examples Selecting the optimum treatment for removing impurities from hydrocarbon streams is a challenging task for any cus- tomer. By providing the means to offer a series of proven liquid hydrocarbon treating technologies, companies can offer services that complement their own technology port- folios. Examples include:  For an operator in Western Canada, Merichem Technologies (formerly Merichem Company) originally designed Thiolex/Regen technologies to treat a natural gas liquid (NGL) stream containing more than 900 wtppm of

Figure 2 Fiber Film mass transfer device

higher throughput rates. Due to the flexibility of Fiber Film as a mass transfer device, there was no requirement for internal modifica - tions to any vessel or system. An available hydrocarbon solvent was introduced into the caustic regeneration pro- cess, which increased the removal of oxidised sulphur com - pounds and oils from the circulating caustic. The end result was less sulphur in the hydrocarbon product stream and reduced sulphur removal load on downstream equipment, even with design impurity changes.  At a client site in central Louisiana, Merichem identified issues with mercaptan sulphur removal from their liquefied petroleum gas (LPG) stream. The operator was using a fixed solid bed of caustic to treat the LPG, and mass transfer was limited. Frequent changeout of the solid bed was costly and messy to manage. Merichem designed a system capable of treating a stream of saturated LPG containing 566 wtppm of H 2 S and 500 wtppm of mercaptans as sulphur. The treated product specification was set to contain nil H 2 S, less than 10 wtppm total sulphur, pass the copper strip corrosion test at 1A, and contain less than 1 wtppm of caustic entrainment measured as Na+. The bed of solid caustic pellets was replaced with a single-stage Thiolex caustic wash system to improve mass transfer and reduce caustic entrainment in the downstream product, with the added benefit of reducing chemical use and frequent main - tenance requirements.  The same end user in Louisiana was also treating a ker- osene stream for the production of jet fuel for the aviation industry. Jet fuel has many stringent specifications, not the least of which is appearance. The presence of alkaline

PTQ Q1 2025