This is on a loading facility in Venezuela which, at 100,000 barrels per hour, is the biggest heavy oil loading facility in the world. I offered a rerate package consisting of a new low capacity impeller, set of new wear rings and bushings, and volute modification to move the pump s BEP closer to duty point. The rerate will increase the pump efficiency 12 points at the proposed new duty compared to operating the pump without the rerate. The customer is not very motivated with the rerate because his analysis shows that the cost of rerate has a long payback period of 5 years based on energy saved due to increased pump efficiency. A - Don t sell the rerate on cost alone.
Reliability is a strong selling point.
Operating a pump at low flow is normally not recommended because of potential problems with internal flow recirculation and thrust imbalance. The occurrence of flow recirculation and thrust imbalance will result in shorter bearing and mechanical seal life, frequent service, and higher maintenance cost, in addition to higher levels of noise and vibration. Find out how old is the pump and what the condition is of its impeller and wear parts. You may be able to shift part of the rerate cost as maintenance cost. For instance, if the impeller, wear rings, or other wear parts are already worn-out and need replacement regardless of the rerate, then the cost of such replacement parts is truly a maintenance cost and should be separated from the rerate cost evaluation.