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  Series Crude Oil Pipeline Stations Using Rotary Positive Displacement Pumps 

The initiating station will have storage tanks/tank farm from which this station draws oil, sometimes via a low pressure boost pump unless the high pressure pumps are in close proximity to the tanks. The most common arrangement uses three 1/2 capacity pumps (one or two running, one a hot spare). This first station pumps the oil to the inlet of the next station. The receiving station has a bypass control valve from station discharge to station inlet. The bypass control valve senses station inlet pressure and bypasses whatever flow is necessary to maintain station inlet pressure at set point, usually 50 to 75 PSIG (3.5 to 5.2 BarG).

Normally, one of the second or subsequent station pumps is started. If station inlet pressure rises above set pressure, a second pump is started and the bypass control valve recirculates whatever volume of oil is necessary to maintain station inlet pressure at set point.

An alternative approach uses a variable speed drive to control pump speed maintaining station inlet pressure at the desired point. Since any combination of pumps could be running at the same time, all of the pumps should be equipped with variable speed drivers.

Regardless of method, each pump needs its own pressure relief valve (not shown below for clarity) connected from pump discharge to pump inlet. Their set pressure needs to be about 8 to 10 percent above normal station discharge pressure.

I attended the fourth annual PumpTec conference (Holiday Inn Select on Peachtree Industrial Drive) in Norcross (Atlanta), GA, USA last week. There were 45 attendees taking the technical courses, some from as far away as the Philippines. The symposium was a two day event covering such topics as:

End suction centrifugal pumps by Lev Nelik, Pumping Machinery LLC

Double suction centrifugal pumps by Pete Noll, Peerless Pumps

Vertical turbine pumps by Rick Silcox, Peerless Pump

Internal and external gear pumps by John Petersen, Viking/Idex

Progressive cavity pumps by Jim Siebolt, Colfax Corp.

Multiple screw pumps (two screw and three screw) by Jim Brennan, Colfax Corp., retired

The symposium included “hands-on” disassembly and assembly of pumps by attendees as well as NPSH demonstration testing of small centrifugal pumps. Tuesday afternoon included Bearings and Lubrication and Alignment and Vibration Fundamentals.

PumpTec 2009 will be held September 14 & 15, 2009. For additional information, go to www.PumpingMachinery.com.