Hydrofluoric acid alkylation is a chemical/hydrocarbon processing application which poses particular challenges to process operators, including the risks associated with the handling of a lethal, highly corrosive fluid which poses a potential hazard to plant equipment, the people who work on site and the wider environment should leaks occur.
The process
HF Alkylation combines olefins (primarily a mixture of propylene and butylene) with isobutene in the presence of a hydrofluoric acid catalyst to produce alkylate. A high-octane additive, alkylate is a critical safety component that offsets the high vapour pressure of the ethanol mandated in today’s low-sulphur unleaded petrol and gasoline supplies. The continual tightening of clean fuels’ legislation has increased the demand for alkylate, which is also responsible for the anti-knocking property of unleaded petrol/gasoline in modern vehicles.
Potential risks
The HF alkylation process poses a number of serious environmental and health and safety risks if poorly managed, with the potential for acid runaway, accelerated equipment corrosion and associated HF release. HF acid by its nature seeks out and attacks imperfections in cast metal components that will ultimately reduce the life of pumps, valves and other equipment and worse still, result in product leakage. Failure-prone mechanical seals can leak harmful process fluids. The aggressive and damaging nature of HF acid places great importance on the choice of material of cast components, particularly in terms of the pump casing and impeller.
Designed for resistance against highly corrosive fluids such as HF acids, magnetic drive sealless pumps offer total containment with built-in reliability. Magnetic drive sealless pumps featuring new technologies have been specifically designed for use in hydrofluoric acid alkylation units and were developed in response to the challenges of handling HF acid.
HMD Kontro HF pump
The result of close collaboration between UOP Honeywell, the leading licensor of HF alkylation technology and HMD Kontro, and using an innovative development process, the HMD Kontro HF pump features a high integrity pump casing manufactured from Alloy C22 (ASTM A194 Gr. CX2MW) which has been tested using new methods of Non-Destructive Examination (NDE).
Specialist design features
Built into the design of these next generation pumps are features which meet operator-specific needs for the HF alkylation process. They include a pump casing in Alloy C22 materials, which has been proven to offer the necessary resistance to corrosion and also meets NDE requirements for HF acid. In addition, the pump’s secondary containment system is rated to 40 bar (580 psi), eliminating the possibility of leakage into the environment, and reducing operational risks and the associated costs to meet stringent environmental and health and safety goals. Finally, there is continuous monitoring to ensure a reliable sealless pump performance which includes leak detection instrumentation and protection against dry pump running (power control monitor).
With no seals to leak, no seal buffer systems to support and maintain and no supporting systems, the latest magnetic drive sealless pump technology offers significant safety, cost and operational benefits. Lower end-user installation costs and simplified maintenance requirements, make it an effective whole-life proposition compared to conventional mechanically sealed pumps.
