Improving The Reliability And Performance Of A Melt Pump Application In A Petrochemical Plant With Block Style Universal Joints

Abstract

A major chemical company has implemented a cost reduction and performance enhancement via universal joints on a melt pump application. The melt pump is used to push molten polyethylene through a die to produce pellets. The pump takes material at 30 psig and 200 C (390 F) and discharges at 3000 psig. Misalignment between the gearbox and melt pump gear centers is approximately one degree. The authors jointly studied the existing problems associated with the gear spindles (high angle gear coupling): primarily reduced life, high maintenance, and high repair costs due in large part to high operating temperatures and the seal design of gear spindle at high misalignment, and proposed block style universal joints to solve the problems. The universal joints replaced the gear spindles supplied originally by the pump manufacturer. This paper demonstrates the block style universal joints were able to: • Significantly reduce plant downtime. • Eliminate high repair costs associated with gear spindles, for the chemical company. • Reduce wear and tear on the melt pump compared to gear spindles. • Improve yield (or production) through superior performance and reliability. • Reduce noise levels. These block type universal joints have been running for over five years now and have been inspected once after 24 months of operation with only general wear and tear from normal operation. The paper will also demonstrates how the universal joints will continue to improve performance in the long term.