In a recent milestone achievement, PSS successfully completed the hydraulic rerate of two crucial API pumps at a prominent refinery in Rayong. The endeavor aimed to enhance the head of the German OH2 pump by 20% while maintaining the existing flow conditions. The medium for this operation was Light Cycle Oil (LCO), a byproduct derived from the catalytic cracking process (FCC) in refineries, known for its significance in producing valuable products such as gasoline.
While initially perceived as a straightforward task involving a new impeller trim with a larger diameter, the project posed unexpected challenges. The low specific speed of the pump (Ns < 500) resulted in efficiency issues, registering below 30%. The 55 kW motor was tripping at levels below 70% of Best Efficiency Point (BEP).
Given the low specific speed and flow conditions, a positive displacement pump would have been a more conventional choice. However, the customer’s specifications mandated the rerating of the existing centrifugal pump with an enlarged trim.
Undeterred, PSS Engineering embarked on a new performance mapping of the pump with help from the customer. Based on this, PSS engineers did a comprehensive redesign, incorporating A743 CA15, a martensite stainless steel, for the impeller and wear rings. The motor had to be upgraded to a 75 kW motor tailored for the expanded impeller and higher-rated conditions. PSS engineers innovatively redesigned the baseplate pedestal to seamlessly accommodate the new motor.
The entire modification process, from impeller redesign to the manufacture of the motor pedestal, was executed at the state-of-the-art PSS Rayong workshop. The pump was completely overhauled in the workshop as well. A testament to our engineering prowess, both pumps underwent successful commissioning in the last 1-2 months, marking another significant achievement in our commitment to elevating the performance of rotating equipment.