According to a major centrifugal pump OEM, energy consumption accounts for 44% of the life cycle cost of a centrifugal pump. With a multi-stage horizontal pump, improving pump efficiency by using Vespel® CR-6100 can make a significant contribution to reducing this cost.
The efficiency improvement from DuPont™ Vespel® CR-6100 results from reduced clearance at the internal wear components in the pump: pump wear rings, inter-stage rings, center-stage bushing, and throttle bushing. These components form the barriers between high-pressure and low-pressure areas within the pump. Because Vespel® CR-6100 is a non-seizing material, the clearance at these interfaces can be reduced, reducing internal leakage losses from high-pressure to low-pressure areas, and thereby increasing efficiency.
For a typical multi-stage horizontal pump (API types BB3, BB4, or BB5), reducing the clearance at the wear components will create a 3-5% efficiency improvement. Just looking at the efficiency gain, upgrading these pumps to Vespel® CR-6100 can be a compelling investment.
Cost of Upgrading a 500 kW (700 HP) pump
Consider a recent application at a refinery where the plant engineers upgraded an API type BB3, 7-stage unit charge pump with Vespel® CR-6100. The fluid pumped is gas oil at 23 ⁰C (73 ⁰F) with a total differential head of 1371 meters (4497 feet). The pump has a rated power of 508 kW and uses a double-suction first stage impeller, a center bushing between the 4th and 7th stage, and a throttle bushing at the 5th stage suction.
Fully upgrading this pump with Vespel® CR-6100 requires 8 wear rings, 4 inter-stage rings, 1 bushing between 1st and 2nd stage, a center bushing, and a throttle bushing. The wear rings of this pump are 200 mm diameter (8”) and the inter-stage rings and bushings are approximately 140 mm (5.5”) diameter. Using the geometry of the actual parts from the pump and including Boulden’s PERF-Seal™ design for the center and throttle bushings, the estimated cost for all of the stationary wear parts in this pump manufactured from Vespel® CR-6100 is $15,800.
How much the customer saves is a function of the cost of power. Table 1 shows the annual savings from a 4% efficiency gain from a 508 kW pump based on different power costs:
|Local cost of power ($/kW-hr)||$0.05||$0.08||$0.10||$0.12|
|Annual Savings (4% of 508 kW)||$8,970||$14,400||$17,900||$21,500|
If we only account for the energy savings in this pump, the upgrade to Vespel® CR-6100 pays for itself in a range of about 20 months in regions with low cost power to less than a year in regions with higher power costs. If you are interested in saving money with your charge pumps, boiler feed pumps, amine pumps, or product shipping pumps, contact Boulden today to discuss an upgrade to Vespel® CR-6100 in your service.