‘The Obvious Often Escapes Us’

New pump innovation saves energy through efficiency

By W.E. Murray
Split Flow Inventor

It is common practice for most API pump installations to install 100% capacity spares. It is also common practice to install two pairs of pumps, taking suction from the same source, for different process services. (See Ref. PFD 1.)

Process designs using two 100% capacity pumps instead of four are sometimes used, e.g. oversizing pumps to envelop two different process conditions: typically low-flow, high head; and high-flow, low-head. (See Ref. PFD 2.) The larger motors required for this option waste energy compared with the common practice, four-pump designs.

Another option is to use two 100% capacity pumps with the Split Flow feature. (See Ref. PFD 3.)

Split Flow Pumps separate/split a pump inlet flowstream into two separate outlet flowstreams. Hybrid Hydraulics™ is the use of two different impellers in the same pump casing, i.e., the first stage is selected for the total flow of both outlet streams at the head of the first outlet stream. The second stage is selected for the lower-flow at the higher additional head of the second outlet stream.

When the process designs use API Standard 610 centrifugal pumps for dual-service applications, use of the split Flow feature provides unique benefits, i.e.,

• Permits use of two pumps instead of four, thus resulting in capital and space savings.
• Half the number of seals reduces maintenance costs and risks of hazardous leaks.
• Allows use of smaller motors, resulting in kW savings.

Hybrid Hydraulics helps optimize pump-to-system hydraulic fits, e.g. results in longer MTBR (Mean Time Between Repairs) for seals and bearings, Ref. API Standard 610 – Par.2.8.3 – Vibration vs. Best Efficiency Point (BEP).

The Split Flow feature, Ref. U.S. Patent No. 9,080,572, may be used with API Standard 610 overhung horizontal OH2 or vertical inline OH3 types (typically less than 200 hp) and BB2 two-stage between bearings type for larger sizes and when between bearings types are specified.

Split Flow Pumps are simple, efficient, reliable and cost effective, i.e., SERC.

API STANDARD 610, CENTRIFUGAL PUMPS FOR PETROLEUM SERVICES

Excerpt from Forword

Energy conservation is of concern and has become increasingly important in all aspects of equipment design, application and operation. Thus, innovative energy-conserving approaches should be aggressively pursued by the manufacturer and the user during these steps.

Alternative approaches that may result in improved energy utilization should be thoroughly investigated and brought forth.