Specifying Pumps. Prepared by Martin Ryan, 2013 Training Series: Using Aspen Technology Economic Evaluation Suite

Centrifugal Pumps: images

Centrifugal Pumps: The API 610 pump model is the most commonly used for process pumps, design is for 20 year service life, 3 years uninterrupted service, heavy duty casing, costs more than ANSI. Over 300HP the system adds TEWAC motor, cooling lines, temperature control loop. Guidelines for conceptual estimates: Use ANSI pumps for non-critical service Use API 610 pumps for hydrocarbon services Use single seal for water service Use double mechanical seal for hydrocarbons Specify seal plans 11/52 with double mechanical seal Allow the system to size motors with ~70% efficiency If head not given see below Design pressure affects casing weight & cost Lower speed (e.g rpm) pumps cost more See Icarus Reference, Chapter 7 Pumps. Head (m) = Differential Pressure (kpa) * / SG Head (feet) = Differential Pressure (psi) * 2.31 / SG Often the equipment list will provide differential pressure instead of head:

Centrifugal Pumps: specific cases For larger pumps which exceed the limits on other models, the CENTRIF multi-stage can be used. For sump pumps (immersed with no inlet line) use the vertical turbine pump model. Axial flow pumps operate at much lower pressures, low head, and high flow rates. Canned motor pumps avoid seal failures. ANSI pumps follow the ASME B pump spec. They are dimensionally interchangeable, may be horizontal or vertical. They are available in a wide variety of materials, are single stage overhung impeller type, cost is typically less than API 610. Cast iron pumps, low cost, general service. In-line pumps (generally smaller sizes <40HP) are mounted in the piping line, eliminating the foundation or reducing it to a small block.

Gear/Positive Displacement Pumps: specific cases Reciprocating positive displacement pumps use piston(s), plunger(s) or membrane(s) to move fluids. Use the diaphragm pump model for chemical dosing applications or metering, typically <25gpm. Seals are not exposed to the liquid being pumped. Triplex plunger pumps are versatile pumps, used for injection (e.g. fracking) and circulating drilling mud. Gear pumps are used for pumping viscous liquids such as resins.

Centrifugal pumps, default P&ID Three piping valves, one strainer, one flow control valve, one pressure gauge, per item.

Pump data input: The API materials available. Use double mechanical seal for hydrocarbons Variable Frequency Drive available – cost is output in the electrical account. If this is an installed spare pump, use the SPARE keyword to adjust P&ID

Pump data input for spare pump: Under the Options menu on the spare pump, choose the “Mat’l/Man-hours % Adj.” form. Under Installation option choose SPAR The SPAR keyword will reduce the pipe, assuming the other pump has a manifold, and will remove the control valve loop.