| dc.description.abstract | An end suction pump for amine service at an Ammonia plant was successfully upgraded by improvement of its components. Two 290 kW (390 HP) pumps, turbine/motor driven, rated for 262 m^3/hr (1,153 gpm) and 271 m (889 ft), operate in severe service conditions due low NPSHA and part-load operation. The equipment exhibited rough operation with high vibration and an elevated repair frequency by recurrent fatigue failure of shaft, severe wear ring rubs, impeller corrosion/erosion, mechanical seal leakage and bearing damages. After a catastrophic failure, involving pump and electric motor, that caused an emergency plant shutdown, an upgrade for the pumps was engineered. The objective was to overcome design weaknesses and incorporate features to increase reliability. Impeller deficiencies were identified and corrected and its metallurgy improved to endure severe cavitation/recirculation damage. The power end was completely redesigned, incorporating larger shaft and bearing housing stiffness, together with a material upgrade, oversized bearings and lubrication enhancements. As a result, a failure frequency as large as 9 a year has been eliminated since the upgrade and the pump presently accumulates 3 years of continuous operation. An outstanding improvement in reliability was obtained together with considerable savings in investment & maintenance costs. | en |
